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排序方式: 共有1689条查询结果,搜索用时 31 毫秒
81.
Paul J. Steiner Matthew A. Bedewitz Angélica V. Medina-Cucurella Sean R. Cutler Timothy A. Whitehead 《American Institute of Chemical Engineers》2020,66(3):e16767
Small-molecule biosensors have major applications in biotechnology and medicine but remain difficult to engineer. Plant hormone receptors represent an attractive platform for engineering such biosensors because their chemically induced dimerization architectures naturally decouple small-molecule sensing and sensor actuation. Rapid biosensor engineering will require quantitative high-throughput screening methods. Here we develop a yeast surface display (YSD) platform for the PYR1/HAB1 abscisic acid sensor of Arabidopsis thaliana. We extensively optimized PYR1 surface display, HAB1 purification, and binding reaction conditions. Our system reproduces previous results with wild-type and engineered receptors, and a mathematical analysis of the PYR1/HAB1 system allows us to infer all binding constants. Critically, we find that a previously engineered PYR1 receptor with altered ligand specificity binds HAB1 with identical affinity, suggesting that substantial reengineering of the PYR1 binding pocket does not compromise sensor actuation. This YSD platform for A. thaliana PYR1/HAB1 will facilitate future biosensor engineering efforts. 相似文献
82.
Anderson Ryan Terrell Jordan Schneider Judy Thompson Sean Gradl Paul 《Metallurgical and Materials Transactions B》2019,50(4):1921-1930
Metallurgical and Materials Transactions B - Various additive manufacturing processes are being evaluated to reduce the time and cost for fabrication of low volume, complex, and multifunctional... 相似文献
83.
Nan Fu Meng Wai Woo Sean Xu Qi Lin Zihao Zhou Xiao Dong Chen 《Chemical engineering science》2011,(8):138
Droplets with different initial sizes, which are typical in conventional liquid atomization for spray drying applications, will result in varying drying and crust formation histories. It is essential for any droplet drying model to accurately capture such fundamental phenomena. This study used a newly constructed glass-filament single droplet rig to evaluate the applicability of the Reaction Engineering Approach (REA) in describing such effect. For the three initial sizes (1, 2 and 3 μL) tested, the glass filament gravimetric method clearly distinguished the different drying kinetics and the crust formation phenomenon, delineated by the drying behavior. Analysis from the drying kinetics revealed that the main premise of the REA, which utilizes a material-specific master activation energy curve, is applicable to droplets of different initial sizes at all the three air temperatures tested. This allowed the REA to accurately predict the different temperature and moisture histories given by droplets with different initial sizes. The result supports the REA as a good modeling approach for a wide range of initial droplet conditions. A new master curve approach was proposed to predict the diameter change of droplets with different initial concentrations. Validation with the current and past experimental data revealed that this approach has strong potential to account for the different feed concentrations typically found in spray drying applications. 相似文献
84.
Jesse Carter E.G. Fu Michael Martin Guoqiang Xie X. Zhang Y.Q. Wang D. Wijesundera X.M. Wang Wei-Kan Chu Sean M. McDeavitt Lin Shao 《Nuclear instruments & methods in physics research. Section B, Beam interactions with materials and atoms》2009,267(17):2827-2831
Ion irradiation can be used to induce partial crystallization in metallic glasses to improve their surface properties. We investigated the microstructural changes in ribbon Zr55Cu30Al10Ni5 metallic glass after 1 MeV Cu-ion irradiation at room temperature, to a fluence of 1.0 × 1016 cm−2. In contrast to a recent report by others that there was no irradiation induced crystallization in the same alloy [S. Nagata, S. Higashi, B. Tsuchiya, K. Toh, T. Shikama, K. Takahiro, K. Ozaki, K. Kawatusra, S. Yamamoto, A. Inouye, Nucl. Instr. and Meth. B 257 (2007) 420], we have observed nanocrystals in the as-irradiated samples. Two groups of nanocrystals, one with diameters of 5–10 nm and another with diameters of 50–100 nm are observed by using high resolution transmission electron microscopy. Experimentally measured planar spacings (d-values) agree with the expectations for Cu10Zr7, NiZr2 and CuZr2 phases. We further discussed the possibility to form a substitutional intermetallic (NixCu1−x)Zr2 phase. 相似文献
85.
Brook trout (Salvelinus fontinalis) are found throughout Lake Superior, Lake Nipigon, and their tributaries. Lacustrine and adfluvial life history variants were historically popular with anglers and were called coasters; coaster brook trout populations are now severely reduced and are of conservation concern. Coasters were known to grow larger and mature later than their stream resident counterparts. This study compared movement patterns, age, size, condition, and relative weight of wild coaster and resident brook trout from the Hurricane River, Pictured Rocks National Lakeshore, Michigan. Wild brook trout ≥ 100 mm from the Hurricane River downstream from Hurricane Falls were tagged with passive integrated transponder tags and monitored for stream-lake movement behavior from May 2003 to November 2007. During 2006 and 2007, brook trout were scale sampled and aged to construct a regression that was then used to calculate the age of all brook trout tagged from 2003 to 2007. Most brook trout movement took place in the fall with October the peak month of emigration with a secondary peak in late spring/early summer and some activity nearly year round. There were no differences found in age structure, size or condition between coasters and residents while in the stream. Our data suggest that a priori growth differences are not determining the expression of coaster outmigration and that stream-lake movements made by coasters, likely driven by habitat requirements, may be highly flexible and facultative. 相似文献
86.
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88.
Metal oxide nanosheets have potential applications in novel nanoelectronics as nanocrystal building blocks. In this work, the devices with a structure of Au/p-type Co3O4 nanosheets/indium tin oxide/glass having bipolar resistive switching characteristics were successfully fabricated. The experimental results demonstrate that the device have stable high/low resistance ratio that is greater than 25, endurance performance more than 200 cycles, and data retention more than 10,000 s. Such a superior performance of the as-fabricated device could be explained by the bulk film and Co3O4/indium tin oxide glass substrate interface effect. 相似文献
89.
This paper presents the results of discrete element simulations applied to a bucket elevator model with particular reference
to the head pulley transition zone. This is the first stage in a larger study to better understand the mechanics of bucket
elevator operation with reference to the discharge of particles at the head end. At the head end two issues arise; mechanically,
the buckets are bolted to the conveying media (typically a fabric reinforced belt) and at the point of belt to headpulley
tangency, the tip of the bucket undergoes a theoretical step change in velocity. This theoretical step change results in a
classical under-damped response in the buckets tip velocity. In undergoing this motion, there are stresses that are passed
to the carcass of the conveying media; understanding the magnitude of these stresses is one longer term goal of this research
allowing a quantitative basis for the existing qualitative design guidelines such as (Handbook for conveyor and elevator belting,
Apex Belting Pty Ltd). The discharge of the bulk material from the bucket has been addressed Beverly et al. (Bulk Solids Handling,
1983) but this analysis is dependent on simple, but common, bucket geometry and ignores the initial transition to the headpulley.
Ignoring the transition with a low speed discharge elevator is not likely to impact on the predicted discharge pattern, however
with high speed discharge elevators, the destabilising effect of the transition is expected to promote premature discharge
of bulk material from the bucket. Depending on the design of the elevator casing this early discharge may or may not impact
on the overall conveying efficiency. 相似文献
90.
How does one repeatedly choose actions so as to be fairest to the multiple beneficiaries of those actions? We examine approaches to discovering sequences of actions for which the worst-off beneficiaries are treated maximally well, then secondarily the second-worst-off, and so on. We formulate the problem for the situation where the sequence of action choices continues forever; this problem may be reduced to a set of linear programs. We then extend the problem to situations where the game ends at some unknown finite time in the future. We demonstrate that an optimal solution is intractable, and present two good approximation algorithms. 相似文献