نتایج جستجو برای: brittle star

تعداد نتایج: 83962  

Ophiocoma erinaceus Muller &Troschel (Ophiocomidae) is part of the extensive group of echinoderm that contains bioactive metabolites. As, the anti cancer potential of brittle star saponin has not been reported against cervical cancer, the present study was conducted to evaluate the anticancer effect of extracted crude saponin. Saponin extraction was conducted using conventional method such as f...

Journal: :Physical review letters 2015
Alessandro Lucantonio Giovanni Noselli Xavier Trepat Antonio DeSimone Marino Arroyo

Brittle materials propagate opening cracks under tension. When stress increases beyond a critical magnitude, then quasistatic crack propagation becomes unstable. In the presence of several precracks, a brittle material always propagates only the weakest crack, leading to catastrophic failure. Here, we show that all these features of brittle fracture are fundamentally modified when the material ...

2007
Jonathan M. Bull

_Abstract. Two major hypotheses have been advanced for the formation of the long wavelength (100-300 km) undulations of oceanic basement and overlying sediments developed in the central Indian Ocean basin: whole layer folding (buckling) and local thickening (inverse boudinage). Using appropriately scaled two-layer analogue models for the oceanic lithosphere comprising a brittle layer above a du...

2008
Philippe Jäger Paul Steinmann Ellen Kuhl

The aim of the present paper is a systematic elaboration of a three dimensional finite element analysis tool for discontinuous fracture in brittle solids. Brittle or quasi-brittle fracture usually occurs when a material reaches the limit of its strength and no plastic deformation has been observed prior to failure. In this novel approach, this kind of failure is characterized by three sets of g...

2016
G. Viola T. Scheiber O. Fredin H. Zwingmann A. Margreth J. Knies

Brittle deformation can saturate the Earth's crust with faults and fractures in an apparently chaotic fashion. The details of brittle deformational histories and implications on, for example, seismotectonics and landscape, can thus be difficult to untangle. Fortunately, brittle faults archive subtle details of the stress and physical/chemical conditions at the time of initial strain localizatio...

Journal: :Physical review letters 2010
Dipanjan Sen Christian Thaulow Stella V Schieffer Alan Cohen Markus J Buehler

At low temperatures silicon is a brittle material that shatters catastrophically, whereas at elevated temperatures, the behavior of silicon changes drastically over a narrow temperature range and suddenly becomes ductile. This brittle-to-ductile transition has been observed in experimental studies, yet its fundamental mechanisms remain unknown. Here we report an atomistic-level study of a funda...

Journal: :Physical review letters 2005
X K Xi D Q Zhao M X Pan W H Wang Y Wu J J Lewandowski

We report a brittle Mg-based bulk metallic glass which approaches the ideal brittle behavior. However, a dimple structure is observed at the fracture surface by high resolution scanning electron microscopy, indicating some type of "ductile" fracture mechanism in this very brittle glass. We also show, from the available data, a clear correlation between the fracture toughness and plastic process...

Journal: :Journal of the American Academy of Dermatology 2005
Peter C M van de Kerkhof Marcel C Pasch Richard K Scher Martina Kerscher Uwe Gieler Eckard Haneke Philip Fleckman

Brittle nail syndrome is a heterogeneous abnormality, characterized by increased fragility of the nail plate. Brittle nails affect about 20% of the population and women are affected twice as frequently as men. The vast majority of patients experience brittle nails as a significant cosmetic problem and a substantial number indicate that these nail abnormalities are painful, impair daily activiti...

In this paper our focus is to study certain covering properties in topological spaces by using semi-open covers. A part of this article deals with Rothberger-type covering properties. The notions of s-Rothberger, almost s-Rothberger, star s-Rothberger, almost star s-Rothberger, strongly star s-Rothberger spaces are defined and corresponding properties are investigated.

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