14 research outputs found

    “Fracture” phenomena in shearing flow of viscous liquids

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    In start-up of steady shearing flow of two viscous unentangled liquids, namely low-molecular-weight polystyrene and α-D-glucose, the shear stress catastrophically collapses if the shear rate is raised above a value corresponding to a critical initial shear stress of around 0.1–0.3 MPa. The time dependence of the shear stress during this process is similar for the two liquids, but visualization of samples in situ and after quenching reveals significant differences. For α-D-glucose, the stress collapse evidently results from debonding of the sample from the rheometer tool, while in polystyrene, bubbles open up within the sample, as occurs in cavitation. Some similarities are pointed out between these phenomena and that of “lubrication failure” reported in the tribology literature.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/47212/1/397_2004_Article_BF00368135.pd

    Ensaio clĂ­nico comparando trĂȘs modalidades de crioterapia em mulheres nĂŁo grĂĄvidas Ensayo clĂ­nico comparando tres tipos de crioterapia en mujeres no embarazadas Clinical trial comparing three types of cryotherapy in non-pregnant women

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    O estudo teve como objetivo comparar trĂȘs modalidades de crioterapia em mulheres saudĂĄveis e nĂŁo grĂĄvidas. Trata-se de um ensaio clĂ­nico randomizado, nĂŁo controlado, com 32 alunas do curso de graduação de uma faculdade de enfermagem particular da cidade de SĂŁo Paulo, divididas em trĂȘs grupos (gelo ĂĄgua, gelo mole, gelo gel). Foram verificadas as temperaturas (axilar, coxa e das trĂȘs bolsas de gelo) entre zero e vinte minutos. As temperaturas das bolsas foram: gelo mole de 9°C negativos a 2°C, gelo ĂĄgua de 0°C a 8°C e gelo gel de 11°C negativos a 2°C. Houve diferença significativa entre as mĂ©dias das temperaturas da coxa com 10 minutos (p=0,007), 15 minutos (p=0,003) e 20 minutos (p=0,005). O gel foi mais eficiente no resfriamento comparado aos outros dois mĂ©todos. As trĂȘs modalidades de crioterapia atingem a temperatura recomendada para analgesia e podem ser aplicadas em puĂ©rperas com dor perineal apĂłs o parto normal.<br>El estudio tuvo como objetivo comparar tres modalidades de crioterapia en mujeres saludables y no grĂĄvidas. Se tratĂł de un ensayo clĂ­nico randomizado no controlado con 32 alumnas del curso de graduaciĂłn de una facultad de enfermerĂ­a particular de la ciudad de SĂŁo Paulo (Brasil). Las alumnas fueron divididas en tres grupos (agua helada, hielo blando, gel helado). Fueron verificadas las temperaturas (axilar, del muslo y de las tres bolsas de hielo) entre cero y veinte minutos. Las temperaturas de las bolsas fueron: hielo blando, de -9°C a 2°C; agua helada, de 0°C a 8°C; gel helado, de -11°C a 2°C. Hubo diferencia significativa entre las medias de las temperaturas del muslo tomadas a los 10 minutos (p=0,007), 15 minutos (p=0,003) y 20 minutos (p=0,005). El gel fue mĂĄs eficiente en el enfriamiento comparado con los otros dos mĂ©todos. Las tres modalidades de crioterapia alcanzan la temperatura recomendada para la analgesia y pueden ser aplicadas en mujeres con dolor perineal posparto.<br>The objective of the present study was to compare three methods of cryotherapy in healthy non-pregnant women. This is a randomized controlled clinical trial that was conducted by 32 undergraduates of a private nursing college in the city of Sao Paulo, divided into three groups (iced water, soft ice, ice gel). The temperatures were verified (axillary, thigh, of the three ice packs) between zero and twenty minutes. The temperatures of the packs were the following: soft ice, from negative 9°C to 2°C; iced water, from 0°C to 8°C; and ice gel from negative 11°C to 2°C. There was a significant difference between the average thigh temperature values at 10 minutes (p=0.007), 15 minutes (p=0.003) and 20 minutes (p=0.005). The gel was the most efficient cooling method. The three cryotherapy methods achieved the recommended temperature for analgesia and may be tested in women with perineal pain after childbirth
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