Abalone utilizes a system of macromolecular matrices and soluble proteins to produce beautiful and mechanically robust shells. The cover shows work by Qiu and co‐workers reported on p. 2678, in which AP8 proteins iso...
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Abalone utilizes a system of macromolecular matrices and soluble proteins to produce beautiful and mechanically robust shells. The cover shows work by Qiu and co‐workers reported on p. 2678, in which AP8 proteins isolated from the shell of red abalone are shown to alter the growth of calcite both by accelerating the rate and modifying the shape from the simple rhombohedra seen in the upper left of the scheme to the more complex form seem in the lower right. The changes are made manifest at an atomic scale through alterations in the growth speed and shape of the atomic steps that form the growth hillocks (background).
We conducted laboratory experiments aimed at studying the effect of several drilling variables on the shape, size, and failure mechanism of borehole breakouts in Mansfield sandstone. The objective was to acquire a bet...
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We conducted laboratory experiments aimed at studying the effect of several drilling variables on the shape, size, and failure mechanism of borehole breakouts in Mansfield sandstone. The objective was to acquire a better understanding of the counterintuitive long and narrow fracture-like breakouts observed in this sandstone, and to examine whether the dimensional characteristics can be controlled by manipulating the drilling operation. Initial tests conducted with two common types of drill-bits proved inconclusive as to whether an affect on breakout characteristics exists. Larger-diameter boreholes produced longer breakouts, suggesting that field-scale wellbore drilling could induce breakouts approaching several meters in length. Boosting the drilling-fluid flow rate was found to cause significant breakout lengthening under high far-field stress conditions. On the contrary, drill-bit penetration rate increases shortened the breakout length under the same far-field stress conditions. Heavier drilling-fluids were found to improve borehole stability by yielding shorter breakouts due to a thin "mud cake" deposited on the borehole wall and along the breakout. Despite the varying drilling conditions, in most cases the breakout width remained surprisingly constant. Copyright 2004, ARMA, American Rock Mechanics Association.
Laboratory experiments were conducted to study the micromechanics leading to fracture-like breakouts in vertical holes drilled into Mansfield sandstone and the relationship between their geometric characteristics and ...
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Laboratory experiments were conducted to study the micromechanics leading to fracture-like breakouts in vertical holes drilled into Mansfield sandstone and the relationship between their geometric characteristics and the applied far-field state of stress (σh, σH, σv). Fracture-like breakouts are tabular, long, and very narrow, originating and extending along the σh springline, where the maximum compressive stress concentration occurs. Several series of tests revealed a clear correlation between the applied stress regime and breakout length, indicating a potential use of these breakouts as stress magnitude indicators. The average breakout width in all the tests is constant regardless of the far-field stress conditions, suggesting that this is a material property related to the lower porosity narrow band developed ahead of the breakout tip. The latter is viewed as a zone of localized compaction formed by the debonding of weakly-sutured grains and their repacking as a result of the high stress concentration along σh springline. Fracture-like breakouts are produced by the removal, with the help of the circulating drilling fluid, of loosened intact and cracked grains from within this compaction band. Copyright 2004, ARMA, American Rock Mechanics Association.
Polymer blend technology was used to create highly anisotropic membranes for fuel cell applications. An important factor for creating structures of high proton conductivity and low methanol permeability was the applic...
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Polymer blend technology was used to create highly anisotropic membranes for fuel cell applications. An important factor for creating structures of high proton conductivity and low methanol permeability was the application of electric fields of selected magnitude and frequency during the formation of the membrane.
Magnetic semiconductors are of interest for emerging spintronic applications, such as the integration of electronic information processing with magnetic data storage. We report on a new approach - furnace annealing un...
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Anodic aluminum oxide (AAO) has long been considered n viable material for templuted growth of nanomaterials for electronic, magnetic and optical applications due to the ability to form self-organized, high aspect-rat...
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The specific sensing of antigen-antibody interaction was examined by using a PEGylated sensor. For the surface modification, acetal-PEG-SH was prepared and by using acetal-PEG-SH, PEG brush was constructed on the gold...
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ISBN:
(纸本)1877040193
The specific sensing of antigen-antibody interaction was examined by using a PEGylated sensor. For the surface modification, acetal-PEG-SH was prepared and by using acetal-PEG-SH, PEG brush was constructed on the gold sensor chip surface. Modification of antibody was carried out by conjugation of SH group in Fab' to the maleimide group at the distal end of PEG chains on the surface. The result shows that the suitable modification of antibody on the PEG brush surface is very important to obtain high sensing character.
Surface forces and shape changes were simultaneously measured during the approach and coalescence of two liquid-liquid and liquid-air interfaces. Large normal and lateral deformations were observed that are neverthele...
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Surface forces and shape changes were simultaneously measured during the approach and coalescence of two liquid-liquid and liquid-air interfaces. Large normal and lateral deformations were observed that are nevertheless consistent with a simple theoretical analysis of the long-range effects of short-range attractive van der Waals forces. The results imply that two fluidlike structures such as liquid droplets and soft biological cells can sense each other at much larger separations than previously assumed based on criteria taken from the interactions of hard particles.
Lightweight metal matrix nemo-composites (MMNCs) (metal matrix with nano-sized ceramic particles) can be of significance for automobile, aerospace and numerous other applications. However, it is extremely difficult to...
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