3,598 research outputs found
Ureteral Injury Due to a Harmonic Scalpel During Laparoscopic Salpingo-oophorectomy
This report highlights the need for vigilance when using laparoscopic energy sources and suggests surgeons who use the Harmonic scalpel pay close attention to application times during tissue dissection
Viscosity of andesite melts and its implication for magma mixing prior to Unzen 1991-1995 eruption
The viscosity of an iron-bearing melt with composition similar to Unzen andesite was
determined experimentally in the high (109-1010.5 Pa·s) and low (5-1000 Pa·s) viscosity range
using a parallel plate viscometer and the falling sphere method, respectively. Falling sphere
experiments were carried out in an internally heated argon pressure vessel and in a piston
cylinder apparatus at 1323 to 1573 K and 200 to 2000 MPa. Creep experiments were
performed in the temperature range of 747 - 845 K at 300 MPa. The water content of the melt
varies from nominally dry to 6.2 wt% H2O. The Fe2+/Fetot ratio was determined for each
sample in the quenched glass using a colorimetric method. Pressure has minor influence on
the viscosity compared with the effect of temperature, water content (main compositional
parameter controlling the viscosity) or with the Fe2+/Fetot ratio (especially important at low
water content of the melt). Based on our new viscosity data and literature data with measured
Fe2+/Fetot ratio we propose a new empirical equation to estimate the viscosity η (in Pa·s) of
andesitic melts as a function of temperature T (in K), water content w (in wt%) and Fe2+/Fetot
ratio. The derived relationship reproduces the experimental data (87 in total) in the viscosity
range from 100.5 to 1013 Pa·s with a 1σ standard deviation of 0.17 log units. However,
application of this calculation model is limited to Fe2+/Fetot>0.3 and to temperatures above Tg.
Moreover, in the high viscosity range the variation of viscosity with water content is
constrained only by few experimental data and needs verification by additional
measurements.
The viscosity data are used to interpret mixing processes in the Unzen magma chamber prior
to 1991-1995 eruption. We demonstrate that the viscosities of the rhyolite and andesite melts
from the two end-member magmas are nearly identical prior and during mixing, enabling
efficient magma mixing
The viscosity of shoshonitic melts (Vulcanello Peninsula, Aeolian Islands, Italy): insight on the magma ascent in dikes
The viscosity of shoshonitic melts from Vulcanello Peninsula (Vulcano Island, Italy) is
experimentally determined at temperatures between 733 K and 1673 K. The water content of the
melts varies from 0.03 to 4.75 wt% H2O. The micropenetration technique is employed at ambient
pressure in the high viscosity range (109-1012 Pa·s). Falling sphere(s) experiments are performed
at 500 and 2000 MPa in the low viscosity range (100.5-103 Pa·s). Results show a decrease of about
2 orders of magnitude in viscosity if ~ 3 wt% of water is added to the dry melt at 1300 K. At high
temperature the viscosity of Vulcanello melts is intermediate between that of andesitic and
basaltic melts. In contrast, at low temperatures (≤1050 K), the shoshonitic melt is characterized
by a lower viscosity with respect to the two previous melts. Based on our new data set, a
calculation model is proposed to predict the viscosity of the shoshonitic melts as a function of
temperature and water content. The viscosity data are used to constrain the ascent velocity of
shoshonitic magmas from Vulcanello within dikes. Using petrological data (temperature and
crystal content of the magma) and volcanological information (geometrical parameters of the
eruptive fissure and depth of magma storage), we estimate the time scale for the ascent of magma
from the main reservoir to the surface. Results show time scales in the order of hours to few days.
We conclude that the rapid ascent of poorly evolved melts from Moho depths should be taken
into account for the hazard assessment of Vulcano Island
Concomitant Congenital Diaphagmatic Hernia (CDH) and bilateral bacterial glomerulonephritis in a pet chinchilla (Chinchilla lanigera)
Background: The domestic chinchilla has been descended from Chinchilla lanigera (long-tailed Chinchilla) or Chinchilla chinchilla (short-tailed Chinchilla). Both species of chinchilla are currently listed as endangered by the IUCN Red List of Threatened Species. Over the past 20 years, they have spread as pets and overall knowledge about their care is improving. The present case report describes a congenital diaphragmatic hernia in a Chinchilla lanigera. Case presentation: A 1-year-old, 420 g female chinchilla (Chinchilla lanigera) was presented for clinical examination due to 2 days haematuria episodes and anorexia. A complete haematological analysis was performed, showing a moderate neutrophilia and severe renal involvement. X-rays showed severe intestinal meteorism affecting mostly the cecum, and a soft tissue density mass with translucent areas located in the caudal thorax, making it hard to distinguish the cardiac silhouette. A barium swallow (barium sulfate) was performed and after 20 min, radiograms were performed again, showing part of the stomach dislocated in thorax. Ultrasound was also carried out, confirming the partial stomach herniation into the thoracic cavity and a severe nephropathy. The patient was euthanized according to the owner’s wish and a complete necropsy was performed. The diagnosis was congenital diaphragmatic hernia concomitant to a severe bilateral bacterial glomerulonephritis. Discussion and conclusions: Diaphragmatic hernias can be either congenital or acquired. About CDHs in pet chinchillas, literature is still lacking. In this patient there was no history of previous traumas. No scar tissue or thickening involved margins of the pathological diaphragm window at the necropsy, supporting the hypothesis of a congenital defect. Glomerulonephritis most often results from immune-mediated mechanisms, generally after the deposition of soluble immune complexes within the glomeruli. This mechanism is favoured by a prolonged antigenemia that could occur during specific viral infections, chronic bacterial infections, chronic parasitism, autoimmune diseases and neoplasia. Few cases of nephritis are described in chinchillas (Chinchilla lanigera), mostly related to bacterial sepsis or less commonly involving fungi. The evidence of bacterial aggregates in kidneys at the histopathology, confirmed the infective aetiology. No relationship between the diaphragmatic hernia and glomerulonephritis was found in this report
Viscosity of Pyroxenite Melt and Its Evolution During Cooling
New viscosity experiments at superliquidus temperatures and during cooling at a rate of 10 K/hr have been performed at different shear rates on a synthetic pyroxenite melt. Results revealed that this melt is extremely fluid at temperature between 1646 and 1530 K and measured viscosities are between 2.2 and 7.8 Pa·s. Such very low viscosities allow the lava to flow in turbulent regime as confirmed by the high Reynolds numbers, which are always >2,000. As a consequence, very long distance could be covered by the lava flow. If we consider this studied composition as proxy for Mars lava flows coupled with very high effusion rates, our results might explain the presence of extraordinary large volcanic channels, as recently hypothesized for the Kasei Valles on Mars, even considering that the gravity is approximately one third that of Earth. Few literature data tracking viscosity during cooling are available, and they reported shear thinning effect on different compositions. Our experiments performed at 0.1 and 1 s−1 have shown complex variation in the apparent viscosity, confirming that nonequilibrium rheology represents a still unexplored field of investigation useful to better understand the real geological scenarios occurring in magmatic and volcanic systems. ©2019. American Geophysical Union. All Rights Reserved
Strategies to Minimize Adhesion Formation After Surgery
No benefit was found for adhesion prevention with the addition of hyaluronate-carboxymethylcellulose
A general viscosity model of Campi Flegrei (Italy) melts
Viscosities of shoshonitic and latitic melts, relevant to the Campi Flegrei caldera
magmas, have been experimentally determined at atmospheric pressure and 0.5 GPa,
temperatures between 840 K and 1870 K, and H2O contents from 0.02 to 3.30 wt%.
The concentric cylinder technique was employed at atmospheric pressure to determine
viscosity of nominally anhydrous melts in the viscosity range of 101.5 - 103 Pa·s. The
micropenetration technique was used to determine the viscosity of hydrous and anhydrous
melts at atmospheric pressure in the high viscosity range (1010 Pa·s). Falling sphere
experiments were performed at 0.5 GPa in the low viscosity range (from 100.35 to 102.79 Pa·s)
in order to obtain viscosity data of anhydrous and hydrous melts. The combination of data
obtained from the three different techniques adopted permits a general description of viscosity
as a function of temperature and water content using the following modified VFT equation:
where η is the viscosity in Pa·s, T the temperature in K, w the H2O content in wt%, and a, b, c,
d, e, g are the VFT parameters. This model reproduces the experimental data (95
measurements) with a 1σ standard deviation of 0.19 and 0.22 log units for shoshonite and
latite, respectively. The proposed model has been applied also to a more evolved composition
(trachyte) from the same area in order to create a general model applicable to the whole
compositional range of Campi Flegrei products.
Moreover, speed data have been used to constrain the ascent velocity of latitic,
shoshonitic, and trachytic melts within dikes. Using petrological data and volcanological
information (geometrical parameters of the eruptive fissure and depth of magma storage), we
estimate a time scale for the ascent of melt from 9 km to 4 km depth (where deep and shallow
reservoirs, respectively, are located) in the order of few minutes. Such a rapid ascent should
be taken into account for the hazard assessment in the Campi Flegrei area
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