Influence of sand grain size and nest microenvironment on incubation success, hatchling morphology and locomotion performance of green turtles (Chelonia mydas) at the Chagar Hutang Turtle Sanctuary, Redang Island, Malaysia

2018 ◽  
Vol 66 (6) ◽  
pp. 356 ◽  
Author(s):  
Taylor A. Stewart ◽  
David T. Booth ◽  
Mohd Uzair Rusli
Keyword(s):  
Particle Size ◽  
Grain Size ◽  
Oxygen Partial Pressure ◽  
Partial Pressure ◽  
Swimming Speed ◽  
Green Turtle ◽  
Chelonia Mydas ◽  
Sand Particle ◽  
Emergence Success ◽  
Sand Grain Size

The nest microenvironment affects hatching and emergence success, sex ratios, morphology, and locomotion performance of hatchling sea turtles. Sand grain size is hypothesised to influence the nest microenvironment, but the influence of sand grain size on incubation of sea turtle eggs has rarely been experimentally tested. At the Chagar Hutang Turtle Sanctuary, Redang Island, Malaysia, green turtle (Chelonia mydas) nests were relocated to sands with different sand grain sizes on a natural beach to assess whether grain size affects nest temperature, oxygen partial pressure inside the nest, incubation success, hatchling morphology and hatchling locomotion performance. Green turtle nests in coarse sand were cooler; however, hatching success, nest emergence success, oxygen partial pressure, incubation length and hatchling size were not influenced by sand particle size. Nests in medium-grained sands were warmest, and hatchlings from these nests were better self-righters but poorer crawlers and swimmers. Hatchling self-righting ability was not correlated with crawling speed or swimming speed, but crawling speed was correlated with swimming speed, with hatchlings typically swimming 1.5–2 times faster than they crawled. Hence, we found that sand particle size had minimal influence on the nest microenvironment and hatchling outcomes.

Recrystallization of Oxygen Contaminated Al Films

1986 ◽  
Vol 71 ◽  
Author(s):  
G.J. Van Der Kolk ◽  
M.J. Verkerk
Keyword(s):  
Grain Size ◽  
Silicon Nitride ◽  
Substrate Temperature ◽  
Oxygen Partial Pressure ◽  
Partial Pressure ◽  
Size Distribution ◽  
Grain Size Distribution ◽  
Relative Increase ◽  
Partial Pressures ◽  
Average Grain Size

AbstractAl was evaporated at oxygen partial pressures, PO2, varying between 10−7 and 10−4 Pa on substrates of silicon nitride. The substrate temperature was varied between 20 °C and 250°C. The films were annealed at temperatures up to 500°C.For Al films deposited at 20°C, it was found that the average grain size decreases with increasing oxygen partial pressure. After annealing recrystallization was observed. The relative increase of grain size was less for higher values of pO2. Annealing gave rise to a broad grain size distribution.For Al films deposited at 250°C, the presence of oxygen caused the growth of rough inhomogeneous films. This inhomogeneous structure remained during annealing.

scholarly journals Hatching and emergence success in green turtle Chelonia mydas nests in the Galápagos Islands

2013 ◽  
Vol 19 (3) ◽  
pp. 217-229 ◽  
Author(s):  
P Zárate ◽  
KA Bjorndal ◽  
M Parra ◽  
PH Dutton ◽  
JA Seminoff ◽  
...  
Keyword(s):  
Green Turtle ◽  
Chelonia Mydas ◽  
Galapagos Islands ◽  
Galápagos Islands ◽  
Emergence Success

Effects of Sand Particle Size and Gradation on Strength of Reactive Powder Concrete

2011 ◽  
Vol 261-263 ◽  
pp. 208-211 ◽  
Author(s):  
Tao Ji ◽  
Bao Chun Chen ◽  
Yi Zhou Zhuang ◽  
Feng Li ◽  
Zhi Bin Huang ◽  
...  
Keyword(s):  
Particle Size ◽  
Grain Size ◽  
Strength Test ◽  
Reactive Powder Concrete ◽  
Sand Particle ◽  
Particle Sizes ◽  
Test Results ◽  
Sand Mixture ◽  
Different Types ◽  
Reactive Powder

After modification, Toufar model was used to calculate the packing degrees of sand mixtures with different particle sizes. For four gradations of sands, the weight ratios of different types of sands with different size ranges, which achieve maximum packing degrees, have been obtained using the modified Toufar model. A strength test of reactive powder concretes (RPCs) with the four gradations of sands was reported. The test results show that the strength of RPC is related to both the maximum grain size and the packing degree of sand mixture. The smaller maximum grain size and larger packing degree of sand mixture can achieve the higher strength of RPC.

Impedance spectroscopy of grain boundaries in nanophase ZnO

1995 ◽  
Vol 10 (9) ◽  
pp. 2295-2300 ◽  
Author(s):  
J. Lee ◽  
J.-H. Hwang ◽  
J.J. Mashek ◽  
T.O. Mason ◽  
A.E. Miller ◽  
...  
Keyword(s):  
Activation Energy ◽  
Grain Size ◽  
Electrical Properties ◽  
Oxygen Partial Pressure ◽  
Partial Pressure ◽  
Grain Boundaries ◽  
Defect Characterization ◽  
Impedance Spectra ◽  
Gas Condensation ◽  
Average Grain Size

Sintered compacts of nanophase ZnO (∼60 nm average grain size, presintered at 600 °C) were made from powders (∼13 nm) prepared by the gas-condensation technique. Impedance spectra were taken as a function of temperature over the range 450–600 °C and as a function of oxygen partial pressure over the range 10−3−1 atm (550 and 600 °C only). The activation energy was determined to be 55 kJ/mole (0.57 eV) and was independent of oxygen partial pressure. The oxygen partial pressure exponent was −1/6. Impedance spectra exhibited nonlinear I-V behavior, with a threshold of approximately 6 V. These results indicate that grain boundaries are governing the electrical properties of the compact. Ramifications for oxygen sensing and for grain boundary defect characterization are discussed.

scholarly journals Acoustic emission study of microcracking in 123-type ceramic superconductors

1990 ◽  
Vol 5 (10) ◽  
pp. 2066-2074 ◽  
Author(s):  
T. J. Richardson ◽  
L. C. De Jonghe
Keyword(s):  
Grain Size ◽  
Acoustic Emission ◽  
Oxygen Partial Pressure ◽  
Partial Pressure ◽  
Ybco Superconductor ◽  
Sintered Ceramic ◽  
Average Grain Size ◽  
Superconducting Compounds ◽  
Emission Study ◽  
Acoustic Emission Study

Acoustic emission from sintered ceramic YBa2Cu3O7−x (YBCO) superconductor pellets provides a direct measure of microcracking behavior during processing. By detection and statistical analysis of acoustic events, the effects of cooling rates, processing atmosphere, average grain size, additives, and grain alignment on microcracking in YBCO have been studied. The onset temperature and duration of acoustic emission during cooling correlate well with the oxygen partial pressure in the furnace. Rapid changes in oxygen partial pressure at constant temperature produce acoustic emission that is characteristic of microcracking. A reported critical grain size for microcracking in sintered polycrystalline YBCO of about 1 μm has been confirmed. Two superconducting compounds, YSrBaCu3O7−x and LaBaCaCu3O7−x with the 123 structure but with smaller crystallographic anisotropy were also examined. Recommendations are made for minimizing microcracking during processing of superconducting ceramics.

scholarly journals Stochastic modeling of kaolinite transport through a sand filter

2019 ◽  
Vol 56 (11) ◽  
pp. 1573-1583 ◽  
Author(s):  
Jongmuk Won ◽  
Susan E. Burns
Keyword(s):  
Particle Size ◽  
Grain Size ◽  
Porous Media ◽  
Clay Particle ◽  
Coarse Grained ◽  
Sand Particle ◽  
Soil Matrix ◽  
Clay Particles ◽  
Grain Size Distributions ◽  
Coarse Grained Soil

Accurately modeling the transport of clay particles through coarse-grained porous media is essential to engineering applications ranging from filtration and drainage, groundwater flow modeling, to contaminant transport. However, predicting the retention and clogging behavior of clay particles within a coarse-grained soil matrix is extremely challenging because clay particles can aggregate and form clusters with a variety of fabrics depending on the prevailing geochemistry of the pore fluid (i.e., pH and ionic strength). The work performed in this study developed a stochastic model to investigate the uncertainty of clay particle transport in porous media using random sampling at a given grain-size distribution to account for inherent uncertainty of the size of clay clusters being transported. Results demonstrated that the model proposed in this work can evaluate upper and lower boundaries of retention profiles of clay particles in a sand medium at given mean and standard deviation of grain-size distributions. In addition, the deterministic approach (using median sizes of sand and clay particles in the simulation) underestimated the mass of retained particles at small size ratios of clay particle size/sand particle size when compared with the stochastic prediction, which would result in nonconservative design.

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