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1.
J Exp Biol ; 226(19)2023 10 01.
Artigo em Inglês | MEDLINE | ID: mdl-37724664

RESUMO

Hovering hawkmoths expend significant energy while feeding, which should select for greater feeding efficiency. Although increased feeding efficiency has been implicitly assumed, it has never been assessed. We hypothesized that hawkmoths have proboscises specialized for gathering nectar passively. Using contact angle and capillary pressure to evaluate capillary action of the proboscis, we conducted a comparative analysis of wetting and absorption properties for 13 species of hawkmoths. We showed that all 13 species have a hydrophilic proboscis. In contradistinction, the proboscises of all other tested lepidopteran species have a wetting dichotomy with only the distal ∼10% hydrophilic. Longer proboscises are more wettable, suggesting that species of hawkmoths with long proboscises are more efficient at acquiring nectar by the proboscis surface than are species with shorter proboscises. All hawkmoth species also show strong capillary pressure, which, together with the feeding behaviors we observed, ensures that nectar will be delivered to the food canal efficiently. The patterns we found suggest that different subfamilies of hawkmoths use different feeding strategies. Our comparative approach reveals that hawkmoths are unique among Lepidoptera and highlights the importance of considering the physical characteristics of the proboscis to understand the evolution and diversification of hawkmoths.


Assuntos
Borboletas , Manduca , Animais , Néctar de Plantas , Molhabilidade , Comportamento Alimentar
2.
ACS Appl Mater Interfaces ; 14(50): 55587-55593, 2022 Dec 21.
Artigo em Inglês | MEDLINE | ID: mdl-36484529

RESUMO

Transition metal phosphide alloying is an effective approach for optimizing the electronic structure and improving the intrinsic performance of the hydrogen evolution reaction (HER). However, obtaining 3d transition metal phosphides alloyed with noble metals is still a challenge owing to their difference in electronegativity, and the influence of their electronic structure modulated by noble metals on the HER reaction also remains unclear. In this study, we successfully incorporated Ru into an Fe2P single crystal via the Bridgeman method and used it as a model catalyst, which effectively promoted HER. Hall transport measurements combined with first-principles calculations revealed that Ru acted as an electron dopant in the structure and increased the Fermi level, leading to a decreased water dissociation barrier and an improved electron-transfer Volmer step at low overpotentials. Additionally, the (21̅1) facet of Ru-Fe2P was found to be more active than its (001) facet, mainly due to the lower H desorption barrier at high overpotentials. The synergistic effect of Ru and Fe sites was also revealed to facilitate H* and OH* desorption compared with Fe2P. Therefore, this study elucidates the boosting effect of Ru-alloyed iron phosphides and offers new understanding about the relationship between their electronic structure and HER performance.

3.
Phys Rev Lett ; 127(9): 097203, 2021 Aug 27.
Artigo em Inglês | MEDLINE | ID: mdl-34506205

RESUMO

Since the discovery of charge disproportionation in the FeO_{2} square-lattice compound Sr_{3}Fe_{2}O_{7} by Mössbauer spectroscopy more than fifty years ago, the spatial ordering pattern of the disproportionated charges has remained "hidden" to conventional diffraction probes, despite numerous x-ray and neutron scattering studies. We have used neutron Larmor diffraction and Fe K-edge resonant x-ray scattering to demonstrate checkerboard charge order in the FeO_{2} planes that vanishes at a sharp second-order phase transition upon heating above 332 K. Stacking disorder of the checkerboard pattern due to frustrated interlayer interactions broadens the corresponding superstructure reflections and greatly reduces their amplitude, thus explaining the difficulty of detecting them by conventional probes. We discuss the implications of these findings for research on "hidden order" in other materials.

4.
Adv Sci (Weinh) ; 8(17): e2100782, 2021 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-34240573

RESUMO

The interplay between topology and magnetism has recently sparked the frontier studies of magnetic topological materials that exhibit intriguing anomalous Hall and Nernst effects owning to the large intrinsic Berry curvature (BC). To better understand the anomalous quantum transport properties of these materials and their implications for future applications such as electronic and thermoelectric devices, it is crucial to discover more novel material platforms for performing anomalous transverse transport studies. Here, it is experimentally demonstrated that low-cost Fe-based Heusler compounds exhibit large anomalous Hall and Nernst effects. An anomalous Hall conductivity of 250-750 S cm-1 and Nernst thermopower of above 2 µV K-1 are observed near room temperature. The positive effect of anti-site disorder on the anomalous Hall transport is revealed. Considering the very high Curie temperature (nearly 1000 K), larger Nernst thermopowers at high temperatures are expected owing to the existing magnetic order and the intrinsic BC. This work provides a background for developing low-cost Fe-based Heusler compounds as a new material platform for anomalous transport studies and applications, in particular, near and above room temperature.

5.
Sci Rep ; 9(1): 3451, 2019 03 05.
Artigo em Inglês | MEDLINE | ID: mdl-30837584

RESUMO

Blood clotting at wound sites is critical for preventing blood loss and invasion by microorganisms in multicellular animals, especially small insects vulnerable to dehydration. The mechanistic reaction of the clot is the first step in providing scaffolding for the formation of new epithelial and cuticular tissue. The clot, therefore, requires special materials properties. We have developed and used nano-rheological magnetic rotational spectroscopy with nanorods to quantitatively study nucleation of cell aggregates that occurs within fractions of a second. Using larvae of Manduca sexta, we discovered that clot nucleation is a two-step process whereby cell aggregation is the time-limiting step followed by rigidification of the aggregate. Clot nucleation and transformation of viscous blood into a visco-elastic aggregate happens in a few minutes, which is hundreds of times faster than wound plugging and scab formation. This discovery sets a time scale for insect clotting phenomena, establishing a materials metric for the kinetics of biochemical reaction cascades. Combined with biochemical and biomolecular studies, these discoveries can help design fast-working thickeners for vertebrate blood, including human blood, based on clotting principles of insect blood.


Assuntos
Coagulação Sanguínea , Insetos/fisiologia , Algoritmos , Animais , Hemolinfa , Larva , Manduca , Modelos Teóricos , Fatores de Tempo , Imagem com Lapso de Tempo
6.
Univ. sci ; 23(2): 291-317, May-Aug. 2018. tab, graf
Artigo em Inglês | LILACS, COLNAL | ID: biblio-979549

RESUMO

Abstract Black flies are abundant benthic organisms in well-oxygenated running water and are considered effective bioindicators of water quality. Information on the ecology of these organisms at the species level is important, since up to now information has mainly been available on a family level. The aim of this study was to evaluate the composition of black flies and their relationships to a group of physical and chemical factors in four small rivers of the Eastern Hills around Bogotá, Colombia. These headwaters are protected by the Empresa de Acueducto y Alcantarillado de Bogotá. Black fly larvae and pupae were collected during four sampling periods during the dry season to the early rainy season of 2012. Multivariate methods were used to determine the presence of each species in relation to dissolved oxygen, nitrates, pH, temperature, and water velocity. PCA ordination revealed a physicochemical environment with a tendency towards a certain homogeneity in the four rivers studied. The DCA ordination confirmed that in La Vieja River the G. ortizi complex dominated while S. muiscorum was dominant in the other three rivers. Similarly, according to the NMDS, the composition of black flies in Arzobispo and Chorro de Padilla rivers was similar, while that of El Delirio and La Vieja rivers were different, especially in this last river. The rivers had low species richness (four species and one species complex). Simulium muiscorum was negatively correlated with dissolved oxygen, temperature and current velocity while S. ignescens was associated with slightly more oxygenated waters and S. furcilatum with faster currents. The low species diversity and richness for the four rivers is consistent with previous reports of low Neotropical diversity of black flies. Results showed that simuliid species could possibly be good indicators of the environmental conditions of Eastern Hills rivers around Bogotá.


Resumen Las moscas negras son organismos bénticos abundantes en corrientes de agua bien oxigenadas y se consideran bioindicadores efectivos de la calidad de agua. La información sobre la ecología de estos organismos a nivel de especie es importante, ya que hasta el momento, ha estado disponible principalmente solo a nivel de familia. El objetivo de este estudio fue evaluar la composición de moscas negras y sus relaciones con un grupo de factores físicos y químicos en cuatro ríos pequeños de los Cerros Orientales alrededor de Bogotá, Colombia. Estos nacimientos están protegidos por la Empresa de Acueducto y Alcantarillado de Bogotá, Colombia. Se colectaron larvas y pupas de moscas negras a lo largo de cuatro períodos de muestreo, desde la estación seca hasta la estación lluviosa de 2012. Se utilizaron métodos multivariados para determinar la presencia de cada especie en relación con: oxígeno disuelto, nitratos, pH, temperatura y velocidad del agua. La ordenación por PCA reveló un ambiente fisicoquímico con tendencia hacia la homogeneidad en los cuatro ríos estudiados. La ordenación por DCA confirmó que en el río La Vieja dominó el complejo G. orti%i, mientras que S. muiscorum fue dominante en los otros tres. De igual forma de acuerdo con el análisis NMDS, la composición de moscas negras en los ríos Arzobispo y Chorro de Padilla fue similar, mientras que en los ríos El Delirio y La Vieja fue diferente, especialmente en este último. Los ríos presentaron baja riqueza de especies (cuatro especies y un complejo de especies). Simulium muiscorum se correlacionó negativamente con el oxígeno disuelto, temperatura y velocidad de la corriente, mientras que S. ignescens estuvo asociado con aguas ligeramente más oxigendas y S. furcilatum, con corrientes más rápidas. La baja diversidad y riqueza para los cuatro ríos es consistente con reportes previos de baja diversidad neotropical de moscas negras. Los resultados muestran que las especies de simúlidos podrían ser buenos indicadores de las condiciones ambientales de los ríos de los Cerros Orientales de Bogotá.


Resumo As moscas negras são organismos bentônicos abundantes em correntes de água bem oxigenadas e se consideram bioindicadores efetivos da calidade de água. A informação sobre a ecologia de estes organismos quanto a espécie é importante, pois até o momento, há informação somente em nível de família. O objetivo de este estudo foi avaliar a composição de moscas negras e suas relações com um grupo de fatores físicos e químicos em quatro rios pequenos dos Cerros Orientais nas redondezas de Bogotá, Colômbia. As nascentes estão protegidas pela Empresa de Acueducto y Alcantarillado de Bogotá, Colômbia. Foram coletadas larvas e poupas de moscas negras ao longo de quatro períodos de amostragem, desde a estação seca até a estação chuvosa de 2012. Foram utilizados métodos multivariados para determinar a presença de cada espécie em relação com: oxigênio dissolvido, nitratos, pH, temperatura e velocidade da água. A ordenação por PCA revelou um ambiente físico-químico com tendência à homogeneidade nos quatro rios estudados. A ordenação por DCS confirmou que no rio La Vieja dominou o complexo G. orti%i, enquanto que S. muiscorum foi dominante nos outros três rios. Igualmente, de acordo com a análise NMDS, a composição de moscas negras nos rios Arzobispo e Chorro de Padilla foi similar, enquanto que nos rios El delírio e La Vieja foi diferente, em especial neste último. Os rios apresentaram baixa riqueza de espécies (quatro espécies e um complexo de espécies). S. muiscorum se correlacionou negativamente com o oxigênio dissolvido, temperatura e velocidades da corrente, enquanto que S. ignescens foi associado com águas ligeiramente mais oxigenadas e S. furcilatum, com correntes mais rápidas. A baixa diversidade e riqueza para os quatro rios é consistente com reportes prévios de baixa diversidade neotropical de moscas negras. Os resultados mostram que espécies de Simulium poderiam ser boas indicadoras das condições ambientais dos rios dos Cerros Orientais de Bogotá.


Assuntos
Qualidade da Água , Simuliidae , Biomarcadores Ambientais , Invertebrados
7.
PLoS One ; 11(6): e0158272, 2016.
Artigo em Inglês | MEDLINE | ID: mdl-27348428

RESUMO

A macrogenomic investigation of a Holarctic clade of black flies-the Simulium cholodkovskii lineage-provided a platform to explore the implications of a unique, synapomorphic whole-arm interchange in the evolution of black flies. Nearly 60 structural rearrangements were discovered in the polytene complement of the lineage, including 15 common to all 138 analyzed individuals, relative to the central sequence for the entire subgenus Simulium. Three species were represented, of which two Palearctic entities (Simulium cholodkovskii and S. decimatum) were sympatric; an absence of hybrids confirmed their reproductive isolation. A third (Nearctic) entity had nonhomologous sex chromosomes, relative to the other species, and is considered a separate species, for which the name Simulium nigricoxum is revalidated. A cytophylogeny is inferred and indicates that the two Palearctic taxa are sister species and these, in turn, are the sister group of the Nearctic species. The rise of the S. cholodkovskii lineage encompassed complex chromosomal and genomic restructuring phenomena associated with speciation in black flies, viz. expression of one and the same rearrangement as polymorphic, fixed, or sex linked in different species; taxon-specific differentiation of sex chromosomes; and reciprocal translocation of chromosome arms. The translocation is hypothesized to have occurred early in male spermatogonia, with the translocated chromosomal complement being transmitted to the X- and Y-bearing sperm during spermatogenesis, resulting in alternate disjunction of viable F1 translocation heterozygotes and the eventual formation of more viable and selectable F2 translocation homozygous progeny. Of 11 or 12 independently derived whole-arm interchanges known in the family Simuliidae, at least six are associated with subsequent speciation events, suggesting a facilitating role of translocations in adaptive radiations. The findings are discussed in the context of potential structural and functional interactions for future genomic research.


Assuntos
Cromossomos de Insetos , Tolerância a Radiação/genética , Simuliidae/genética , Simuliidae/efeitos da radiação , Translocação Genética , Animais , Evolução Biológica , Mapeamento Cromossômico , Feminino , Ligação Genética , Masculino , Filogenia , Cromossomos Politênicos , Simuliidae/classificação
8.
J Law Med Ethics ; 44(2): 263-82, 2016 06.
Artigo em Inglês | MEDLINE | ID: mdl-27338602

RESUMO

The foreskin is a complex structure that protects and moisturizes the head of the penis, and, being the most densely innervated and sensitive portion of the penis, is essential to providing the complete sexual response. Circumcision-the removal of this structure-is non-therapeutic, painful, irreversible surgery that also risks serious physical injury, psychological sequelae, and death. Men rarely volunteer for it, and increasingly circumcised men are expressing their resentment about it.Circumcision is usually performed for religious, cultural and personal reasons. Early claims about its medical benefits have been proven false. The American Academy of Pediatrics and the Centers for Disease Prevention and Control have made many scientifically untenable claims promoting circumcision that run counter to the consensus of Western medical organizations.Circumcision violates the cardinal principles of medical ethics, to respect autonomy (self-determination), to do good, to do no harm, and to be just. Without a clear medical indication, circumcision must be deferred until the child can provide his own fully informed consent.In 2012, a German court held that circumcision constitutes criminal assault. Under existing United States law and international human rights declarations as well, circumcision already violates boys> absolute rights to equal protection, bodily integrity, autonomy, and freedom to choose their own religion. A physician has a legal duty to protect children from unnecessary interventions. Physicians who obtain parental permission through spurious claims or omissions, or rely on the American Academy of Pediatrics' position, also risk liability for misleading parents about circumcision.


Assuntos
Circuncisão Masculina/ética , Ética Médica , Autonomia Pessoal , Circuncisão Masculina/legislação & jurisprudência , Liberdade , Humanos , Recém-Nascido , Masculino , Religião e Medicina , Estados Unidos
10.
Acta biol. colomb ; 20(1): 217-220, ene.-abr. 2015. ilus, tab
Artigo em Inglês | LILACS | ID: lil-734923

RESUMO

Little is known about the oviposition habits and egg structure of Neotropical members of the Simuliidae family. The oviposition behavior of Simulium dinellii (Joan) was observed near at Otún Quimbaya, Colombia. Small groups of females hovered about 2 cm above the water surface to oviposit. Some of these females had been capture and the eggs were obtained. These eggs were counted, measured and processed by scanning electron microscopy. Subtriangular eggs had a latticework of polygons on the endochorionic surface. Chorionic differences between the eggs of S. dinellii and the few previously studied species suggest potential taxonomic value of egg microstructure.


El conocimiento sobre los hábitos de oviposición y estructura de los huevos de la familia Simuliidae es muy escaso. En este estudio se observó el comportamiento de oviposición de Simulium dinellii (Joan) en quebradas cercanas al Santuario de fauna y flora Otún Quimbaya, Colombia. El cual consistió en la formación de pequeños grupos de hembras que sobrevolaban a 2 cm de la superficie del agua para ovipositar, algunas de estas hembras fueron colectadas, obteniendo así los huevos, los cuales fueron contados, medidos y procesados por Microscopia Electrónica de Barrido con el fin de caracterizar la estructura endocoriónica. Los huevos presentaron una forma subtriangular, con una entramado poligonal sobre la superficie. Las características morfológicas observadas en los huevos de S. dinellii fueron diferentes a las previamente reportadas en otras especies de la familia Simuliidae, sugiriendo un posible valor taxonómico de la microestructura del huevo.

11.
Fungal Biol ; 115(4-5): 381-92, 2011.
Artigo em Inglês | MEDLINE | ID: mdl-21530920

RESUMO

The Blastocladiomycota is a recently described phylum of ecologically diverse zoosporic fungi whose species have not been thoroughly sampled and placed within a molecular phylogeny. In this study, we investigated the phylogeny of the Blastocladiomycota based on ribosomal DNA sequences from strains identified by traditional morphological and ultrastructural characters. Our results support the monophyly of the Coelomomycetaceae and Physodermataceae but the Blastocladiaceae and Catenariaceae are paraphyletic or polyphyletic. The data support two clades within Allomyces with strains identified as Allomyces arbusculus in both clades, suggesting that species concepts in Allomyces are in need of revision. A clade of Catenaria species isolated from midge larvae group separately from other Catenaria species, suggesting that this genus may need revision. In the Physodermataceae, Urophlyctis species cluster with a clade of Physoderma species. The algal parasite Paraphysoderma sedebokerensis nom. prov. clusters sister to other taxa in the Physodermataceae. Catenomyces persicinus, which has been classified in the Catenariaceae, groups with the Chytridiomycota rather than Blastocladiomycota. The rDNA operon seems to be suitable for classification within the Blastocladiomycota and distinguishes among genera; however, this region alone is not suitable to determine the position of the Blastocladiomycota among other basal fungal phyla with statistical support. A focused effort to find and isolate, or directly amplify DNA from additional taxa will be necessary to evaluate diversity in this phylum. We provide this rDNA phylogeny as a preliminary framework to guide further taxon and gene sampling and to facilitate future ecological, morphological, and systematic studies.


Assuntos
Blastocladiomycota/genética , DNA Ribossômico/genética , Filogenia , Animais , Blastocladiomycota/classificação , Núcleo Celular/genética , DNA Fúngico/genética , Evolução Molecular , Insetos/microbiologia , Larva/microbiologia
12.
J Law Med ; 19(2): 335-53, 2011 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-22320007

RESUMO

Since 1965, tens of millions of boys have been circumcised under the Medicaid program, most at birth, at a cost to the United States Federal Government, the States and taxpayers of billions of dollars. Although 18 States have ended coverage since 1982, the United States Government and 32 States continue to pay for non-therapeutic circumcision, even though no medical association in the world recommends it. Many cite American medical association policy that the procedure has potential medical benefits as well as disadvantages, and that the circumcision decision should be left to parents. This article shows that Medicaid coverage of circumcision is not a policy issue because it is prohibited by federal and State law. As American medical associations concede, non-therapeutic circumcision is unnecessary, elective, cosmetic surgery on healthy boys, usually performed for cultural, personal or religious reasons. The fundamental principle of Medicaid law is that Medicaid only covers necessary medical treatments after the diagnosis of a current medical condition. Physicians and hospitals face severe penalties for charging Medicaid for circumcisions. Medicaid officials and the Federal and State Governments are also required to end coverage. It is unlawful to circumcise and to allow the circumcision of healthy boys at the expense of the government and taxpayers.


Assuntos
Circuncisão Masculina/economia , Medicaid/economia , Humanos , Masculino , Estados Unidos
13.
Mem. Inst. Oswaldo Cruz ; 100(3): 249-257, May 2005. ilus, mapas, tab
Artigo em Inglês | LILACS | ID: lil-411019

RESUMO

Simulium cauchense Floch & Abonnenc and Simulium quadrifidum Lutz are widely distributed in the Amazon region and are morphologically similar at the larval and pupal stages. Chromosomally, these species are readily distinguished by the position of the nucleolar organizer, which is in the short arm of chromosome I in S. cauchense and in the long arm of chromosomes III in S. quadrifidum. They also differ by three fixed inversions. Sex chromosomes are undifferentiated in both species. Chromosomal resolution of the two species allowed us to evaluate four structural features previously used as diagnostic aids at the larval stage. Characters that distinguish larvae of the two species are the number of branches and branching patterns of the dorsal abdominal setae and the dark band on each primary fan. Branching patterns of the gill histoblasts were often diagnostic, with S. quadrifidum exhibiting more proximal branching and S. cauchense more distal branching. Sites where both species occurred sometimes had larvae with one petiole branching proximally and the other distally; in these cases examination of the chromosomes permitted assignment of the specimen to species. Pigmentation patterns of larvae, on the other hand, are highly variable. Color typically is sex linked in both species.


Assuntos
Animais , Feminino , Masculino , Bandeamento Cromossômico , Simuliidae/genética , Brasil , Variação Genética , Larva/genética , Simuliidae/anatomia & histologia , Simuliidae/classificação
14.
Mem. Inst. Oswaldo Cruz ; 93(3): 317-25, May-Jun. 1998. ilus
Artigo em Inglês | LILACS | ID: lil-209949

RESUMO

The larva, pupa, male and female of Simulium daltanhani n.sp. are described and illustrated. This species shares diagnostic characteristics with Simulium quadrifidum Lutz, Simulium cauchense Floch & Abonnenc, Simulium brevifurcatum Lutz and Similium siolii Py-Daniel. It was collected in three countries (Manaus, Presidente Figueiredo and Itacoatiara) in the State of Amazonas, Brazil. Its habitat includes streams in disturbed, open areas where the forest has been cut for road constuction; it was not collected in adjacent forested streams, suggesting that it colonizes disturbed habitats. The larval subesophageal ganglion i discussed as a useful character, when pigmented, to distinguish this species within a limited geographic area.


Assuntos
Animais , Simuliidae/anatomia & histologia , Brasil
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