921 research outputs found

    Quality Control of Cement Deep Soil Mixing Work for the Port of Oakland Projects

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    The Cement Deep Soil Mixing (CDSM) method is an in situ soil treatment technology that introduces and mixes cementitious materials with native soils using hollow-stem rotating shafts equipped with a cutting tool at the tip and mixing paddles above the tip. The successful use of the soil-cement produced by CDSM relies on the selection of acceptance criteria and construction quality control during the in situ soil mixing process. Two CDSM projects for the Port of Oakland are used as case examples to present the acceptance criteria set and the execution of the quality control program for the soil mixing work. This quality control program ensures that the geometric and material design parameters of the CDSM structure have been obtained. The data acquired from these two projects are presented and compared with strength data from two other projects to illustrate the influence of acceptance criteria over the CDSM products

    Crosslinked Polypeptide Films via RAFT-Mediated Continuous Assembly of Polymers

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    Polypeptide coatings are a cornerstone in the field of surface modification due to their widespread biological potential. As their properties are dictated by their structural features, subsequent control thereof using unique fabrication strategies is important. Herein, we report a facile method of precisely creating densely crosslinked polypeptide films with unusually high random coil content through continuous assembly polymerization via reversible addition–fragmentation chain transfer (CAP‐RAFT). CAP‐RAFT was fundamentally investigated using methacrylated poly‐l‐lysine (PLLMA) and methacrylated poly‐l‐glutamic acid (PLGMA). Careful technique refinement resulted in films up to 36.1±1.1 nm thick which could be increased to 94.9±8.2 nm after using this strategy multiple times. PLLMA and PLGMA films were found to have 30–50 % random coil conformations. Degradation by enzymes present during wound healing reveals potential for applications in drug delivery and tissue engineering

    Is there an integrative center in the vertebrate brain-stem? A robotic evaluation of a model of the reticular formation viewed as an action selection device

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    Neurobehavioral data from intact, decerebrate, and neonatal rats, suggests that the reticular formation provides a brainstem substrate for action selection in the vertebrate central nervous system. In this article, Kilmer, McCulloch and Blum’s (1969, 1997) landmark reticular formation model is described and re-evaluated, both in simulation and, for the first time, as a mobile robot controller. Particular model configurations are found to provide effective action selection mechanisms in a robot survival task using either simulated or physical robots. The model’s competence is dependent on the organization of afferents from model sensory systems, and a genetic algorithm search identified a class of afferent configurations which have long survival times. The results support our proposal that the reticular formation evolved to provide effective arbitration between innate behaviors and, with the forebrain basal ganglia, may constitute the integrative, ’centrencephalic’ core of vertebrate brain architecture. Additionally, the results demonstrate that the Kilmer et al. model provides an alternative form of robot controller to those usually considered in the adaptive behavior literature

    A disilene base adduct with a dative Si–Si single bond.

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    An experimental and theoretical study of the base- stabilized disilene 1 is reported, whichforms at lowtemper- atures in the disproportionation reaction of Si 2 Cl 6 or neo- Si 5 Cl 12 with equimolar amounts of NMe 2 Et. Single-crystal X- ray diffraction and quantum-chemical bonding analysis dis- close an unprecedented structure in silicon chemistry featuring adative Si!Si single bond between two silylene moieties, Me 2 EtN!SiCl 2 !Si(SiCl 3 ) 2 .The central ambiphilic SiCl 2 group is linked by dative bonds to the amine donor and the bis(trichlorosilyl)silylene acceptor,which leads to push–pull stabilization. Based on experimental and theoretical examina- tions aformation mechanism is presented that involves an autocatalytic reaction of the intermediately formed anion Si(SiCl 3 ) 3 ± with neo-Si 5 Cl 12 to yield 1

    Effects of Chronic Ethanol Treatment on Neocortex

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    Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/66043/1/j.1530-0277.1986.tb05133.x.pd
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