Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 40
Filtrar
Mais filtros










Base de dados
Intervalo de ano de publicação
1.
Swiss J Palaeontol ; 141(1): 1, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35250843

RESUMO

An important component of the Alpine vertebrate record of Late Triassic age derives from the Kössen Formation, which crops out extensively in the eastern Alps. Here, we present an isolated and only partially preserved large rib, which carries an osteoderm on a low uncinate process. Osteological comparison indicates that the specimen likely belongs to a small clade of marine reptiles, Saurosphargidae. Members of the clade are restricted to the western (today Europe) and eastern margins of the Tethys (today China) and were so far known only from the Anisian stage of the Middle Triassic. The assignment of the new find to cf. Saurosphargidae, with potential affinities to the genus Largocephalosaurus from the Guanling Formation of Yunnan and Guizhou Provinces, China, would extend the occurrence of the clade about 35 million years into the Late Triassic.

2.
Science ; 374(6575): eabf5787, 2021 Dec 24.
Artigo em Inglês | MEDLINE | ID: mdl-34941418

RESUMO

Body sizes of marine amniotes span six orders of magnitude, yet the factors that governed the evolution of this diversity are largely unknown. High primary production of modern oceans is considered a prerequisite for the emergence of cetacean giants, but that condition cannot explain gigantism in Triassic ichthyosaurs. We describe the new giant ichthyosaur Cymbospondylus youngorum sp. nov. with a 2-meter-long skull from the Middle Triassic Fossil Hill Fauna of Nevada, USA, underscoring rapid size evolution despite the absence of many modern primary producers. Surprisingly, the Fossil Hill Fauna rivaled the composition of modern marine mammal faunas in terms of size range, and energy-flux models suggest that Middle Triassic marine food webs were able to support several large-bodied ichthyosaurs at high trophic levels, shortly after ichthyosaur origins.


Assuntos
Evolução Biológica , Tamanho Corporal , Cetáceos/anatomia & histologia , Fósseis , Répteis/anatomia & histologia , Animais , Organismos Aquáticos , Cetáceos/fisiologia , Simulação por Computador , Dieta , Ecossistema , Cadeia Alimentar , Filogenia , Répteis/classificação , Répteis/fisiologia , Crânio/anatomia & histologia , Vertebrados/anatomia & histologia , Vertebrados/fisiologia
3.
Proc Biol Sci ; 288(1955): 20211166, 2021 07 28.
Artigo em Inglês | MEDLINE | ID: mdl-34284632

RESUMO

Histology-based skeletochronology is a widely used approach to determine the age of an individual, and is based on the assumption that temporal cessations or decelerations of bone growth lead to incremental growth marks (GM), reflecting annual cycles. We studied the reliability of histology-based skeletochronology in a variety of extant tetrapods by comparing two different approaches: petrographic ground sections versus stained microtomized sections. Each bone was cut into two corresponding halves at its growth centre in order to apply both approaches to one and the same sample. None of the samples unequivocally revealed the actual age of the specimens, but truly concerning is the fact that the majority of samples even led to conflicting age estimates between the two approaches. Although the microtomized sections tended to yield more GM and thus indicated an older age than the ground sections, the contrary also occurred. Such a pronounced ambiguity in skeletochronological data strongly challenges the value of the respective age determinations for both extant and extinct animals. We conclude that much more research on the fundamental methodological side of skeletochronology-especially regarding the general nature and microscopic recognition of GM-is required.


Assuntos
Desenvolvimento Ósseo , Osso e Ossos , Animais , Reprodutibilidade dos Testes
4.
NASN Sch Nurse ; 35(4): 219-223, 2020 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-32496933

RESUMO

The Framework for 21st Century School Nursing Practice™, created by the National Association of School Nurses (NASN), explains school nursing practice, providing guidance, organization, prioritization, and meaning. This is the second article in a series for The Framework for 21st Century School Nursing Practice. This article focuses on case management, one of the practice components in the principle of care coordination. Case management focuses on school nurse support of individual at-risk students and collaborative actions to reduce barriers to their academic success. This article will clarify how the terms care coordination and case management are used in context of the Framework and provide an example to help the reader apply the concept to practice. Washington's School Nurse Case Management Program will serve as a model. The program outlines evidence for effective practice and shares practical examples of how school nurses can implement case management into their daily work. Any school nurse, no matter how large or small their workload, can provide case management.


Assuntos
Serviços de Enfermagem Escolar , Administração de Caso , Humanos
5.
J Adv Nurs ; 75(12): 3677-3688, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31566808

RESUMO

AIMS: To develop a theory describing the processes and actions involved with school nurse case management for school-aged children with chronic conditions in the K12 system. DESIGN: Case management is an essential practice for the school nurse. Little is known about actual case management practice in real-world settings. Grounded theory methodology following a literature-based conceptual model of school nurse case management. METHODS: A purposive maximum variation sampling was used for data collection and analysis. Semi-structured interviews conducted in-person and via conferencing software from January to March 2017 with school nurses practicing in Washington State until data saturation was achieved. A condition lasting at least 6 months was also used to define a chronic condition. RESULTS: In all, 14 school nurses with an average of 12 years of experience were interviewed. Analysis revealed that the core strategy used by participating nurses for case management involved navigating through ambiguity; balancing multiple roles; seeking guidance and training; acknowledging imperfect functioning and navigating poor system supports. CONCLUSION: The findings suggest that actual school nurse case management practice differs from best practice recommendations. Participants did not discuss health promotion or environmental management and did not act to set goals or prioritize care as suggested in the literature. IMPACT: This article informs nursing leadership of the real-world challenges faced by nurses performing case management in the school setting. These findings indicate that improvements in system supports and training, together with tolerance for the challenges nurses face in providing such care, might improve case management practice in the schools.


Assuntos
Atitude do Pessoal de Saúde , Administração de Caso/organização & administração , Serviços de Enfermagem Escolar , Adolescente , Adulto , Criança , Pré-Escolar , Doença Crônica/enfermagem , Atenção à Saúde/organização & administração , Teoria Fundamentada , Humanos , Entrevistas como Assunto , Liderança , Pessoa de Meia-Idade , Serviços de Saúde Escolar/organização & administração , Instituições Acadêmicas , Washington
6.
Sci Rep ; 9(1): 10430, 2019 07 18.
Artigo em Inglês | MEDLINE | ID: mdl-31320733

RESUMO

Unlike any other tetrapod, turtles form their dorsal bony shell (carapace) not from osteoderms, but by contribution of the ribs and vertebrae that expand into the dermis to form plate-like shell components. Although this was known from embryological studies in extant turtles, important steps in this evolutionary sequence have recently been highlighted by the Triassic taxa Pappochelys, Eorhynchochelys and Odontochelys, and the Permian Eunotosaurus. The discovery of Pappochelys shed light on the origin of the ventral bony shell (plastron), which formed from enlarged gastralia. A major question is whether the turtle shell evolved in the context of a terrestrial or aquatic environment. Whereas Odontochelys was controversially interpreted as aquatic, a terrestrial origin of turtles was proposed based on evidence of fossorial adaptations in Eunotosaurus. We report palaeohistological data for Pappochelys, a taxon that exemplifies earlier evolutionary stages in the formation of the bony shell than Odontochelys. Bone histological evidence reveals (1) evolutionary changes in bone microstructure in ribs and gastralia approaching the turtle condition and (2) evidence for a predominantly amphibious or fossorial mode of life in Pappochelys, which support the hypothesis that crucial steps in the evolution of the shell occurred in a terrestrial rather than fully aquatic environment.


Assuntos
Exoesqueleto/anatomia & histologia , Fósseis/anatomia & histologia , Tartarugas/anatomia & histologia , Adaptação Fisiológica/fisiologia , Animais , Evolução Biológica , Placas Ósseas , Filogenia , Costelas/anatomia & histologia , Crânio/anatomia & histologia , Coluna Vertebral/anatomia & histologia
7.
Anat Rec (Hoboken) ; 302(10): 1770-1791, 2019 10.
Artigo em Inglês | MEDLINE | ID: mdl-30989828

RESUMO

Isolated ribs and vertebrae of Middle Triassic sauropterygians are studied. The vertebrae have a well-defined large cavity in their centra, which is a unique feature and is without any modern analogue. The articular facets of vertebrae are made of endochondral bone including calcified as well as uncalcified cartilage. Vertebrae are pachyosteosclerotic in the pachypleurosaurs Neusticosaurus and Serpianosaurus from the Alpine Triassic, and osteosclerotic in the placodont, in the medium-sized Nothosaurus marchicus, and in the pachypleurosaur Anarosaurus. In large Nothosaurus specimens, the vertebrae are cavernous. The ribs of all sampled specimens are osteosclerotic, which resembles the microanatomy of long bones in all studied taxa. The proximal to medial part of ribs mainly consists of a compact periosteal cortex surrounding an inner endosteal territory. Toward the distal end of the ribs, the periosteal thickness decreases whereas the endosteal territory increases. Despite a shift from periosteal versus endosteal tissues, global rib compactness remains relatively constant. Osteosclerosis in ribs and vertebrae is reached by the same processes as in the long bones: by a relative increase in cortex thickness that is coupled by a reduction of the medullary cavity, by the persistence of calcified cartilage, and by an inhibition of remodeling although some resorption may occur but without complete redeposition of bone. Processes differ from those observed in Permian marine reptiles and some mosasaurines, where either extensive remodeling or inhibition of bone resorption leads to osteosclerosis. Besides differences regarding the microanatomy, all studied bones of a taxon are consistent in their bone tissue type. Anat Rec, 302:1770-1791, 2019. © 2019 American Association for Anatomy.


Assuntos
Adaptação Fisiológica , Evolução Biológica , Dinossauros/anatomia & histologia , Costelas/anatomia & histologia , Coluna Vertebral/anatomia & histologia , Animais , Fósseis/anatomia & histologia , Natação/fisiologia
8.
Adv Mater ; 30(37): e1704679, 2018 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-29921016

RESUMO

The quest for advanced designer adsorbents for air filtration and monitoring hazardous trace gases has recently been more and more driven by the need to ensure clean air in indoor, outdoor, and industrial environments. How to increase safety with regard to personal protection in the event of hazardous gas exposure is a critical question for an ever-growing population spending most of their lifetime indoors, but is also crucial for the chemical industry in order to protect future generations of employees from potential hazards. Metal-organic frameworks (MOFs) are already quite advanced and promising in terms of capacity and specific affinity to overcome limitations of current adsorbent materials for trace and toxic gas adsorption. Due to their advantageous features (e.g., high specific surface area, catalytic activity, tailorable pore sizes, structural diversity, and range of chemical and physical properties), MOFs offer a high potential as adsorbents for air filtration and monitoring of hazardous trace gases. Three advanced topics are considered here, in applying MOFs for selective adsorption: (i) toxic gas adsorption toward filtration for respiratory protection as well as indoor and cabin air, (ii) enrichment of hazardous gases using MOFs, and (iii) MOFs as sensors for toxic trace gases and explosives.

9.
PLoS One ; 13(2): e0192322, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-29466442

RESUMO

AIMS: In contrast to the membrane bound adenylyl cyclases, the soluble adenylyl cyclase (sAC) is activated by bicarbonate and divalent ions including calcium. sAC is located in the cytosol, nuclei and mitochondria of several tissues including cardiac muscle. However, its role in cardiac pathology is poorly understood. Here we investigate whether sAC is involved in hypertrophic growth using two different model systems. METHODS AND RESULTS: In isolated adult rat cardiomyocytes hypertrophy was induced by 24 h ß1-adrenoceptor stimulation using isoprenaline (ISO) and a ß2-adrenoceptor antagonist (ICI118,551). To monitor hypertrophy cell size along with RNA/DNA- and protein/DNA ratios as well as the expression level of α-skeletal actin were analyzed. sAC activity was suppressed either by treatment with its specific inhibitor KH7 or by knockdown. Both pharmacological inhibition and knockdown blunted hypertrophic growth and reduced expression levels of α-skeletal actin in ISO/ICI treated rat cardiomyocytes. To analyze the underlying cellular mechanism expression levels of phosphorylated CREB, B-Raf and Erk1/2 were examined by western blot. The results suggest the involvement of B-Raf, but not of Erk or CREB in the pro-hypertrophic action of sAC. In wild type and sAC knockout mice pressure overload was induced by transverse aortic constriction. Hemodynamics, heart weight and the expression level of the atrial natriuretic peptide were analyzed. In accordance, transverse aortic constriction failed to induce hypertrophy in sAC knockout mice. Mechanistic analysis revealed a potential role of Erk1/2 in TAC-induced hypertrophy. CONCLUSION: Soluble adenylyl cyclase might be a new pivotal player in the cardiac hypertrophic response either to long-term ß1-adrenoceptor stimulation or to pressure overload.


Assuntos
Adenilil Ciclases/metabolismo , Agonistas Adrenérgicos beta/efeitos adversos , Cardiomegalia/enzimologia , Isoproterenol/efeitos adversos , Animais , Cardiomegalia/induzido quimicamente , Camundongos , Pressão , Ratos
10.
R Soc Open Sci ; 5(1): 171800, 2018 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-29410873

RESUMO

Today, the UNESCO World Heritage Site of Aldabra Atoll is home to about 100 000 giant tortoises, Aldabrachelys gigantea, whose fossil record goes back to the Late Pleistocene. New Late Pleistocene fossils (age ca. 90-125 000 years) from the atoll revealed some appendicular bones and numerous shell fragments of giant tortoises and cranial and postcranial elements of crocodylians. Several tortoise bones show circular holes, pits and scratch marks that are interpreted as bite marks of crocodylians. The presence of a Late Pleistocene crocodylian species, Aldabrachampsus dilophus, has been known for some time, but the recently found crocodylian remains presented herein are distinctly larger than those previously described. This indicates the presence of at least some larger crocodylians, either of the same or of a different species, on the atoll. These larger crocodylians, likely the apex predators in the Aldabra ecosystem at the time, were well capable of inflicting damage on even very large giant tortoises. We thus propose an extinct predator-prey interaction between crocodylians and giant tortoises during the Late Pleistocene, when both groups were living sympatrically on Aldabra, and we discuss scenarios for the crocodylians directly attacking the tortoises or scavenging on recently deceased animals.

11.
Infect Dis Clin Pract (Baltim Md) ; 25(2): 62-65, 2017 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-28286403

RESUMO

Mycobacterium goodii, a rapidly growing nontuberculous mycobacterium, is an emerging pathogen in nosocomial infections. Its inherent resistance patterns make it a challenging organism to treat, and delays in identification can lead to poor outcomes. We present a case of cardiac device pocket infection with M. goodii, complicated by both antibiotic resistance and drug reactions that highlight the challenges faced by clinicians trying to eradicate these infections. We also present a brief review of the English literature surrounding this disease, including a table of all reported cases of M. goodii infections and their outcomes to act as guide for clinicians formulating treatment plans for these infections. A clear understanding of diagnostic methods and treatment caveats is essential to curing infections caused by these organisms.

12.
J Am Coll Health ; 65(1): 50-57, 2017 01.
Artigo em Inglês | MEDLINE | ID: mdl-27661542

RESUMO

OBJECTIVE: The purpose of this study was to examine the proportion of higher education institutions in the United States that require a personal health course (PHC) for graduation and to describe the nature of such requirements. Participants: This study included a random sample of public and private institutions of higher education (IHE) with undergraduate programs within the United States (N = 310). Data were collected between September 2014 and May 2015. METHODS: University catalogs were accessed from the institutions' public Web sites to determine whether a PHC was offered, and whether it was exclusively or optionally required for graduation. RESULTS: The majority (55.8%) of the sample offered at least 1 PHC, with only 10% exclusively requiring the course and an additional 10% optionally required the course. CONCLUSIONS: Although the utility of undergraduate students completing a PHC is clear, the majority of institutions do not require such a course for degree conferral.


Assuntos
Currículo/tendências , Educação em Saúde/normas , Promoção da Saúde/métodos , Humanos , Estados Unidos , Universidades/organização & administração
13.
Naturwissenschaften ; 104(1-2): 4, 2017 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-28005148

RESUMO

The tuatara (Sphenodon punctatus) from New Zealand is often-erroneously-identified as a 'living fossil', although it is the lone survivor of a large, successful radiation of Rhynchocephalia, sister taxon to squamates (lizards and snakes), that thrived through the Mesozoic and Cenozoic and experienced an intricate evolution of life histories and feeding habits. Within Rhynchocephalia, only Pleurosauridae are thought to be marine and piscivorous. Here, we present bone histological data of the Jurassic pleurosaurid Palaeopleurosaurus, showing osteosclerosis (i.e. bone mass increase) in its gastralia, and some osteosclerosis in its rib but no increase in bone mass in the femur, supporting a gradual skeletal specialization for an aquatic way of life. Similar to Sphenodon, the bone tissue deposited in Palaeopleurosaurus is lamellar zonal bone. The femoral growth pattern in Palaeopleurosaurus differs from that of terrestrial Sphenodon in a more irregular spacing of growth marks and deposition of non-annual (i.e. non-continuous) rest lines, indicating strong dependency on exogenous factors. The annual growth mark count in adult but not yet fully grown Palaeopleurosaurus is much lower when compared to adult individuals of Sphenodon, which could indicate a lower lifespan for Palaeopleurosaurus. Whereas the gastral ribs of Palaeopleurosaurus and Sphenodon are similar in composition, the ribs of Sphenodon differ profoundly in being separated into a proximal tubular rib part with a thick cortex, and an elliptical, flared ventral part characterised by extremely thin cortical bone. The latter argues against a previously inferred protective function of the ventral rib parts for the vulnerable viscera in Sphenodon.


Assuntos
Osso e Ossos/anatomia & histologia , Fósseis , Traços de História de Vida , Lagartos/anatomia & histologia , Animais , Organismos Aquáticos , Evolução Biológica , Alemanha , Lagartos/crescimento & desenvolvimento
14.
Integr Comp Biol ; 56(6): 1349-1369, 2016 12.
Artigo em Inglês | MEDLINE | ID: mdl-27794536

RESUMO

Numerous amniote groups adapted to an aquatic life. This change of habitat naturally led to numerous convergences. The various adaptive traits vary depending on the degree of adaptation to an aquatic life, notably between shallow water taxa still able to occasionally locomote on land and open-marine forms totally independent from the terrestrial environment, but also between surface swimmers and deep divers. As a consequence, despite convergences, there is a high diversity within aquatic amniotes in e.g., shape, size, physiology, swimming mode. Bone microanatomy is considered to be strongly associated with bone biomechanics and is thus a powerful tool to understand bone adaptation to functional constraints and to make functional inferences on extinct taxa. Two opposing major microanatomical specializations have been described in aquatic amniotes, referred to as bone mass increase and a spongious organization, respectively. They are assumed to be essentially linked with the hydrostatic or hydrodynamic control of buoyancy and body trim and with swimming abilities and velocity. However, between extremes in these specializations, a wide range of intermediary patterns occurs. The present study provides a state-of-the-art review of these inner bone adaptations in semi-aquatic and aquatic amniotes. The analysis of the various microanatomical patterns observed in long bones, vertebrae, and ribs of a large sample of (semi-)aquatic extant and extinct amniotes reveals the wide diversity in microanatomical patterns and the variation in combination of these different patterns within a single skeleton. This enables us to discuss the link between microanatomical features and habitat, swimming abilities, and thus functional requirements in the context of amniote adaptation to an aquatic lifestyle.


Assuntos
Adaptação Fisiológica , Organismos Aquáticos , Osso e Ossos/anatomia & histologia , Animais , Densidade Óssea , Ecossistema , Natação/fisiologia
15.
PLoS One ; 11(7): e0158448, 2016.
Artigo em Inglês | MEDLINE | ID: mdl-27391607

RESUMO

Mid-diaphyseal cortical bone tissue in humeri of Nothosaurus spp. consists of coarse parallel-fibered bone, finer and higher organized parallel-fibered bone, and lamellar bone. Vascular canals are mainly arranged longitudinally and radially in a dominantly radial system. Blood vessels are represented by simple vascular canals, incompletely lined primary osteons, and fully developed primary osteons. Nothosaurus spp. shows a variety of diaphyseal microanatomical patterns, ranging from thick to very thin-walled cortices. In the early Anisian (Lower Muschelkalk), small- and large-bodied Nothosaurus spp. generally exhibit bone mass increase (BMI). In the middle to late Anisian (Middle Muschelkalk) small-bodied nothosaurs retain BMI whereas larger-bodied forms tend to show a decrease in bone mass (BMD). During the latest Anisian to early Ladinian (Upper Muschelkalk), small- and few large-bodied nothosaurs retain BMI, whereas the majority of large-bodied forms exhibit BMD. The stratigraphically youngest nothosaurs document five microanatomical categories, two of which are unique among marine amniotes: One consists of a very heterogeneously distributed spongy periosteal organization, the other of very thin-walled cortices. The functional significance of the two unique microanatomical specializations seen in large-bodied nothosaurs is the reduction of bone mass, which minimizes inertia of the limbs, and thus saves energy during locomotion. Transitions between the various microanatomical categories are rather gradual. Our results suggest that small-bodied Nothosaurus marchicus and other, not further assignable small-bodied nothosaurs seem to have been bound to near-shore, shallow marine environments throughout their evolution. Some large-bodied Nothosaurus spp. followed the same trend but others became more active swimmers and possibly inhabited open marine environments. The variety of microanatomical patterns may be related to taxonomic differences, developmental plasticity, and possibly sexual dimorphism. Humeral microanatomy documents the diversification of nothosaur species into different environments to avoid intraclade competition as well as competition with other marine reptiles. Nothosaur microanatomy indicates that knowledge of processes involved in secondary aquatic adaptation and their interaction are more complex than previously believed.


Assuntos
Dinossauros/anatomia & histologia , Osteon/anatomia & histologia , Periósteo/anatomia & histologia , Tíbia/anatomia & histologia , Animais , Densidade Óssea/fisiologia , Dinossauros/fisiologia , Periósteo/fisiologia , Tíbia/fisiologia
16.
R Soc Open Sci ; 2(7): 140440, 2015 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-26587259

RESUMO

Placodontia is a clade of durophagous, near shore marine reptiles from Triassic sediments of modern-day Europe, Middle East and China. Although much is known about their primary anatomy and palaeoecology, relatively little has been published regarding their life history, i.e. ageing, maturation and growth. Here, growth records derived from long bone histological data of placodont individuals are described and modelled to assess placodont growth and life-history strategies. Growth modelling methods are used to confirm traits documented in the growth record (age at onset of sexual maturity, age when asymptotic length was achieved, age at death, maximum longevity) and also to estimate undocumented traits. Based on these growth models, generalized estimates of these traits are established for each taxon. Overall differences in bone tissue types and resulting growth curves indicate different growth patterns and life-history strategies between different taxa of Placodontia. Psephoderma and Paraplacodus grew with lamellar-zonal bone tissue type and show growth patterns as seen in modern reptiles. Placodontia indet. aff. Cyamodus and some Placodontia indet. show a unique combination of fibrolamellar bone tissue regularly stratified by growth marks, a pattern absent in modern sauropsids. The bone tissue type of Placodontia indet. aff. Cyamodus and Placodontia indet. indicates a significantly increased basal metabolic rate when compared with modern reptiles. Double lines of arrested growth, non-annual rest lines in annuli, and subcycles that stratify zones suggest high dependence of placodont growth on endogenous and exogenous factors. Histological and modelled differences within taxa point to high individual developmental plasticity but sexual dimorphism in growth patterns and the presence of different taxa in the sample cannot be ruled out.

17.
NASN Sch Nurse ; 30(6): 314-9, 2015 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-26515566

RESUMO

Managing asthma in the schools is complex and requires careful planning. This article highlights key steps in implementing guideline-based care for children with asthma in Washington State schools: assessing students, establishing acuity, communicating with parents, and training staff. Advance planning can improve outcomes for students, parents, and school staff in managing this complex and prevalent disease. NASN recently developed asthma management guidelines. Developing state-specific guidelines provides an opportunity to speak specifically to state laws and nurse practice acts while also reinforcing the importance of specialized practice to school nurses, school administrators and teachers, parents, and students.


Assuntos
Asma/enfermagem , Guias de Prática Clínica como Assunto , Serviços de Saúde Escolar , Humanos , Serviços de Enfermagem Escolar , Washington
18.
Angew Chem Int Ed Engl ; 54(43): 12588-91, 2015 Oct 19.
Artigo em Inglês | MEDLINE | ID: mdl-26314273

RESUMO

Metal-organic frameworks (MOFs) are promising materials for gas-separation and air-filtration applications. However, for these applications, MOF crystallites need to be incorporated in robust and manageable support materials. We used chitin-based networks from a marine sponge as a non-toxic, biodegradable, and low-weight support material for MOF deposition. The structural properties of the material favor predominant nucleation of the MOF crystallites at the inside of the hollow fibers. This composite has a hierarchical pore system with surface areas up to 800 m(2) g(-1) and pore volumes of 3.6 cm(3) g(-1) , allowing good transport kinetics and a very high loading of the active material. Ammonia break-through experiments highlight the accessibility of the MOF crystallites and the adsorption potential of the composite indicating their high potential for filtration applications for toxic industrial gases.


Assuntos
Filtros de Ar , Poluentes Atmosféricos/isolamento & purificação , Amônia/isolamento & purificação , Quitina/química , Compostos Organometálicos/química , Adsorção , Animais , Poríferos/química , Porosidade
19.
Phys Chem Chem Phys ; 17(26): 17471-9, 2015 Jul 14.
Artigo em Inglês | MEDLINE | ID: mdl-26079102

RESUMO

The "gate opening" mechanism in the highly flexible MOF Ni2(2,6-ndc)2dabco (DUT-8(Ni), DUT = Dresden University of Technology) with unprecedented unit cell volume change was elucidated in detail using combined single crystal X-ray diffraction, in situ XRD and EXAFS techniques. The analysis of the crystal structures of closed pore (cp) and large pore (lp) phases reveals a drastic and unique unit cell volume expansion of up to 254%, caused by adsorption of gases, surpassing other gas-pressure switchable MOFs significantly. To a certain extent, the structural deformation is specific for the guest molecule triggering the transformation due to subtle differences in adsorption enthalpy, shape, and kinetic diameter of the guest. Combined adsorption and powder diffraction experiments using nitrogen (77 K), carbon dioxide (195 K), and n-butane (272.5 K) as a probe molecules reveal a one-step structural transformation from cp to lp. In contrast, adsorption of ethane (185 K) or ethylene (169 K) results in a two-step transformation with the formation of intermediate phases. In situ EXAFS during nitrogen adsorption was used for the first time to monitor the local coordination geometry of the metal atoms during the structural transformation in flexible MOFs revealing a unique local deformation of the nickel-based paddle-wheel node.

20.
J Am Coll Health ; 62(6): 399-406, 2014.
Artigo em Inglês | MEDLINE | ID: mdl-24794273

RESUMO

OBJECTIVE: To investigate health-related impediments to academic success for bisexual college students. PARTICIPANTS: Respondents to the Fall 2011 American College Health Association-National College Health Assessment II (ACHA-NCHA II) survey who self-identified as bisexual, heterosexual, gay, or lesbian. METHODS: Secondary analyses of the ACHA-NCHA II data were conducted to compare the experiences of bisexual students with both each other (bisexual men and bisexual women) and those of their nonbisexual counterparts (heterosexual and gay/lesbian students). RESULTS: Bisexual college students are a large and distinct sexual minority group. On all measures with the exception of discrimination, bisexual college students reported the strongest threats to academic success of all sexual orientations. CONCLUSIONS: Given the unique impediments for bisexual students, college health professionals should consider specifically addressing needs for bisexual students, bisexual women in particular.


Assuntos
Bissexualidade , Comportamento Sexual/estatística & dados numéricos , Estudantes , Universidades/tendências , Feminino , Humanos , Masculino , Inquéritos e Questionários
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA
...