نتایج جستجو برای: mechanical weathering

تعداد نتایج: 242214  

In order to assess mineralogical composition influence on durability and strength of rocks, four samples of hornfelsic rocks were selected from southern and western parts of the city of Hamedan, west of Iran. These rock samples were subjected to mineralogical, physical and mechanical tests in the laboratory. Also, they were evaluated in 15 cycles of slake-durability testing in different pH of s...

2012
Gregory J. Retallack

Despite evidence that weathering plays a role in forming intertidal, estuarine, and fluvial rock platforms, many publications uncritically refer to “wave-cut” or “stream-cut” rock platforms. The alternative explanations of chemical weathering and physical water erosion of rock platforms have been debated since 1839. Our new approach to this long-standing problem introduces data from fluvial as ...

2008
J. Brink

Papers published in Hydrology and Earth System Sciences Discussions are under open-access review for the journal Hydrology and Earth System Sciences Abstract Major environmental stressors of boreal and sub-arctic rivers are hydrological changes and global warming and both factors will significantly influence the future evolution of the river chemistry in high latitudes. We tested the hypothesis...

2009
J. A. Cartwright J. D. Gilmour

The halogen concentrations of a number of Martian meteorites vary significantly, with larger variations observed in I/Cl compared to Br/Cl. One striking feature is the high I/Cl ratios associated with those meteorites found in Antarctica. Removal of low temperature, superficial contamination does not significantly reduce the I/Cl ratio [1], indicating that processing in Antarctica is responsibl...

2004
MICHAEL A. VELBEL

Common naturally occurring orthosilicates can be grouped into those in which the major non-tetrahedral cations are (1) FeII and/or Mg, plus or minus Al (olivine, pyralspite garnets, staurolite); (2) Al (Al2SiO5 polymorphs), or (3) Zr. Feand Mg-bearing orthosilicates have the weakest bonds between non-tetrahedral cations and structural oxygen (M-O bonds), and zircon the strongest, with Al-O bond...

2000
MAGNUS LAND BJÖRN ÖHLANDER

Chemical weathering rates and erosion rates of granitic till in northern Sweden have been estimated. The present-day chemical weathering rate is compared with the long-term average weathering rate since the last deglaciation approximately 8,700 years ago. Also, the present-day release rates of major and trace elements due to chemical weathering are compared with the mobility of these elements i...

2011
Y. Ogawa J. Haruyama T. Matsunaga

Space weathering causes the change in optical properties, such as darkening, reddening, and decrease of absorption depths of the planetary surfaces. Two competing processes have been proposed so far as the main mechanism of such space weathering; hydrogen irradiation by solar wind and bombardment of micrometeorites. We use the new data set obtained by Spectral Profiler (SP) onboard SELENE/Kaguy...

Journal: :Frontiers of Structural and Civil Engineering 2021

After publication of our article [1], the authors became aware that they had omitted to include credit line for Fig. 1 [2]. The corrected caption with is given below: “Fig. (a) Photograph wood-plastic composite samples; (b) photographs experimental setups used 1) pin on disk, 2) tensile testing, 3) three-point bending, 4) impact, 5) injection molding, 6) effect weathering [12]. Reprinted from C...

Journal: :The Journal of prosthetic dentistry 1999
S P Haug C J Andres B K Moore

STATEMENT OF PROBLEM Maxillofacial prostheses are serviceable for approximately 6 months, after which they need to be refabricated because of the deterioration of color and physical properties. PURPOSE This third article in a 3-part series evaluated the color stability of commonly used colorant-elastomer combinations as a result of exposure to weathering. METHODS AND MATERIAL Fifteen specim...

2010
Nicholas P. ROSENSTOCK

Ectomycorrhizal fungi may make a significant contribution to mineral weathering in temperate and boreal forests. It is important to know how this weathering activity will be affected by the changing nutrient demands of forests impacted by global change and nitrogen deposition. This review examines what is known about how plants sense and respond to nutrient demand and discusses the existing lit...

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