27 research outputs found
Influence of surfactants on the structure of titanium oxide gels : experiments and simulations
We report here on experimental and numerical studies of the influence of
surfactants on mineral gel synthesis. The modification of the gel structure
when the ratios water-precursor and water-surfactant vary is brought to the
fore by fractal dimension measures. A property of {\em polydispersity of the
initial hydrolysis} is proposed to explain these results, and is successfuly
tested through numerical experiments of three dimensional chemically limited
aggregation.Comment: 12 pages, 4 Postscript figures, uses RevTe
Femoral and obturator neuropathy secondary to retroperitoneal hemorrhage the value of the ct scan
A man developed signs of femoral and obturator neuropathy due to spontaneous retroperitoneal hemorrhage while taking anticoagulant drugs for suspected thrombophlebitis. The hemorrhage was demonstrated by CT scan. CT scans should be used in all patients developing signs of peripheral nerve entrapment during anticoagulant therapy.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/24328/1/0000595.pd
What do cyclists need to see to avoid single-bicycle crashes?
The number of single-bicycle crash victims is substantial in countries with high levels of cycling. To study the role of visual characteristics of the infrastructure, such as pavement markings, in single-bicycle crashes, a study in two steps was conducted. In Study 1, a questionnaire study was conducted among bicycle crash victims (n = 734). Logistic regression was used to study the relationship between the crashes and age, light condition, alcohol use, gaze direction and familiarity with the crash scene. In Study 2, the image degrading and edge detection method (IDED-method) was used to investigate the visual characteristics of 21 of the crash scenes. The results of the studies indicate that crashes, in which the cyclist collided with a bollard or road narrowing or rode off the road, were related to the visual characteristics of bicycle facilities. Edge markings, especially in curves of bicycle tracks, and improved conspicuity of bollards are recommended. Statement of Relevance: Elevated single-bicycle crash numbers are common in countries with high levels of cycling. No research has been conducted on what cyclists need to see to avoid this type of crash. The IDED-method to investigate crash scenes is new and proves to be a powerful tool to quantify 'visual accessibility'. © 2011 Taylor & Francis
The choroid plexus as a sex hormone target: Functional implications
The choroid plexuses (CPs) are highly vascularized branched structures that protrude into the ventricles of the brain, and form a unique interface between the blood and the cerebrospinal fluid (CSF). In recent years, novel functions have been attributed to this tissue such as in immune and chemical surveillance of the central nervous system, brain development, adult neurogenesis and circadian rhythm regulation. Sex hormones (SH) are widely recognized as modulators in several neurodegenerative diseases, and there is evidence that estrogens and androgens regulate several fundamental biological functions in the CPs. Therefore, SH are likely to affect the composition of the CSF impacting on brain homeostasis. This review will look at implications of the CPs' sex-related specificities.Portuguese Foundation for Science and Technology (FCT, Portugal – http://www.fct.pt) project grants (PTDC/SAU-NEU/114800/2009); and by FEDER funds through the POCI – COMPETE 2020 – Operational Programme Competitiveness and Internationalisation in Axis I – Strengthening research, technological development and innovation (Project No. 007491) and National Funds by FCT – Foundation for Science and Technology (Project UID/Multi/00709). Joana Tomás was supported by a grant from CENTRO-07-ST24-FEDER-002015. Telma Quintela is a recipient of a FCT fellowship (SFRH/BPD/70781/2010).
The work at ICVS/3B’s has the support of Portuguese North Regional Operational Program (ON.2 – O Novo Norte) under the National Strategic Reference Framework (QREN), through the European Regional Development Fund (FEDER). Fernanda Marques is a recipient of a FCT Investigator award (IF/00231/2013) of the Fundação para a Ciência e Tecnologia (FCT, Portugal)info:eu-repo/semantics/publishedVersio
Estudo comparativo entre as osteossĂnteses com placas e osteossĂnteses com placas associadas a enxertos de proteĂna morfogenĂ©tica Ăłssea (Gen-Tech®) em fraturas distais de rádio-ulna em cĂŁes com menos de 6 quilos
Uso do processo sol-gel na obtenção de materiais hĂbridos organo-inorgânicos: preparação, caracterização e aplicação em eletrĂłlitos de estado sĂłlido Utilization of the sol-gel process to obtain organic-inorganic hybrid materials: preparation, characterization and application as solid state electrolytes
Neste trabalho Ă© descrita a preparação de materiais hĂbridos constituĂdos de um copolĂmero orgânico contendo segmentos Ăłxido de etileno e de sĂlica. A rede inorgânica foi formada na solução polimĂ©rica a partir da hidrĂłlise e condensação do tetraetoxisilano, TEOS. Como copolĂmero foi utilizado o poli(Ăłxido de etileno-b-amida-6), PEBAX. Foram preparados tambĂ©m hĂbridos contendo perclorato de lĂtio, denominados aqui hĂbridos eletrĂłlitos. Os materiais foram caracterizados por microscopia eletrĂ´nica de transmissĂŁo, ensaios de tensĂŁo-deformação, análise dinâmico-mecânica e difratometria de raios-X. Os sistemas PEBAX/TEOS/LiClO foram tambĂ©m caracterizados por espectroscopia de impedância eletroquĂmica e voltametria cĂclica para avaliação de suas propriedades como eletrĂłlito de estado sĂłlido.<br>In this work it was described the preparation of hybrid materials constituted by a organic copolymer, which contains ethylene oxide blocks, and silica. The inorganic network was formed by the hydrolysis and condensation of tetraethoxysilane, TEOS, into the polymeric solution. As a copolymer, it was used poly(ethylene oxide-b-amide-6), PEBAX. Hybrids containing lithium perchlorate, known as hybrid electrolytes, were also prepared. The materials were characterized by transmission electron microscopy, stress-strain tests, dynamic-mechanical analysis and X-ray diffractometry. The PEBAX/TEOS/LiClO4 systems were also characterized by electrochemical impedance spectroscopy and cyclic voltammetry to evaluate their properties as a solid state electrolyte