نتایج جستجو برای: predominantly from pyrolytic origin
تعداد نتایج: 5719357 فیلتر نتایج به سال:
Pyrolysis techniques were used to characterize the organic matter contained within the penetrated section and to assess the presence of heavy hydrocarbon shows. The Rock-Eval data indicate a change in organic hydrogen enrichment within the middle Miocene sequence. It appears that the level of organic enrichment may be controlled by sedimentation rate, while the organic hydrogen enrichment, as s...
Simultaneous static-mode mass spectrometric measurements of nitrogen, carbon, helium, neon, and argon, extracted from the same aliquot of sample by high-resolution stepped combustion, have been made for a suite of five lunar soils. Noble gas isotope ratios show that the majority of noble gases are derived from a solar wind source; for example, at peak release temperatures of 500–600 C, Ne/Ne = ...
The relative contributions to modern European populations of Paleolithic hunter-gatherers and Neolithic farmers from the Near East have been intensely debated. Haplogroup R1b1b2 (R-M269) is the commonest European Y-chromosomal lineage, increasing in frequency from east to west, and carried by 110 million European men. Previous studies suggested a Paleolithic origin, but here we show that the ge...
We report the electrochemical properties of pristine monolayer, double layer and few-layer (termed quasi-) graphene grown via CVD and transferred using PMMA onto an insulating substrate (silicon dioxide wafers). Characterisation has been performed by Raman spectroscopy, optical spectroscopy, Atomic Force Microscopy and X-ray Photoelectron Spectroscopy, revealing 'true' pristine single-layer gra...
The articulating surfaces of four different sizes of unused pyrolytic carbon proximal interphalangeal prostheses (PIP) were evaluated though measuring several topographical parameters using a white light interferometer: average roughness (Sa); root mean-square roughness (Sq); skewness (Ssk); and kurtosis (Sku). The radii of the articulating surfaces were measured using a coordinate measuring ma...
Several studies have been conducted to develop more accurate and precise indices for hydrocarbons source apportionment. The present study, however, develops a new multi-metric index for hydrocarbons source apportionment. It measures Poly Aromatic Hydrocarbons (PAHs) concentration at six stations with well known petrogenic origin, calculating Phe/An, Flu/Py, Chr/BaA, BaA/Chr, An/(An+Ph), Flu/(Fl...
Near-isotropic pyrolytic carbon containing a small amount of co-deposited silicon carbide has been used for years as the materials from which prosthetic heart valves are fabricated [ 1 ]. Silicon carbide was introduced into this material to increase the hardness and thereby the wear resistance of the material. Silicon carbide, however, has poor thromboresistance relative to pyrolytic carbon, so...
New tunneling data are reported in underdoped Bi2Sr2CaCu2O8−δ using superconductor-insulator-superconductor break junctions. Energy gaps, ∆, of 51±2, 54±2 and 57±3 meV are observed for three crystals with Tc=77, 74, and 70 K respectively. These energy gaps are nearly three times larger than for overdoped crystals with similar Tc. Detailed examination of tunneling spectra over a wide doping rang...
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