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991.
Rahul Shankar Lisa K. Kemp Nicholas A. Smith Jacob A. Cross Beibei Chen Sergei I. Nazarenko Jin Gyu Park Travis L. Thornell John K. Newman Sarah E. Morgan 《应用聚合物科学杂志》2021,138(23):50537
Polyhedral oligomeric silsesquioxane (POSS) nanostructured chemicals, when incorporated at low levels in thermoplastics, provide processability enhancement and viscosity reduction without compromising other bulk physical properties. POSS has been relatively unexplored in high performance polymers, and there is incomplete understanding of the mechanisms by which POSS produces flow improvements. In this study, polyethersulfone (PES) was melt-blended with trisilanolphenyl (TSP)-POSS and dodecaphenyl (DP)-POSS; and rheological, dielectric spectroscopy, and scanning electron microscopy evaluations were conducted to identify structure/property/processing relationships. TSP-POSS yielded greater processability improvements and viscosity reductions than DP-POSS, suppressed low temperature relaxations to a larger extent, and displayed a greater degree of nanoscale dispersion in the polymer matrix. The findings are evaluated in terms of competing theories of POSS viscosity reduction. 相似文献
992.
Lester J Lambert Stefan Grotegut Maria Celeridad Palak Gosalia Laurent JS De Backer Andrey A Bobkov Sumeet Salaniwal Thomas DY Chung Fu-Yue Zeng Ian Pass Paul J Lombroso Nicholas DP Cosford Lutz Tautz 《International journal of molecular sciences》2021,22(9)
Many human diseases are the result of abnormal expression or activation of protein tyrosine kinases (PTKs) and protein tyrosine phosphatases (PTPs). Not surprisingly, more than 30 tyrosine kinase inhibitors (TKIs) are currently in clinical use and provide unique treatment options for many patients. PTPs on the other hand have long been regarded as “undruggable” and only recently have gained increased attention in drug discovery. Striatal-enriched tyrosine phosphatase (STEP) is a neuron-specific PTP that is overactive in Alzheimer’s disease (AD) and other neurodegenerative and neuropsychiatric disorders, including Parkinson’s disease, schizophrenia, and fragile X syndrome. An emergent model suggests that the increase in STEP activity interferes with synaptic function and contributes to the characteristic cognitive and behavioral deficits present in these diseases. Prior efforts to generate STEP inhibitors with properties that warrant clinical development have largely failed. To identify novel STEP inhibitor scaffolds, we developed a biophysical, label-free high-throughput screening (HTS) platform based on the protein thermal shift (PTS) technology. In contrast to conventional HTS using STEP enzymatic assays, we found the PTS platform highly robust and capable of identifying true hits with confirmed STEP inhibitory activity and selectivity. This new platform promises to greatly advance STEP drug discovery and should be applicable to other PTP targets. 相似文献
993.
Marta Salvador-Castell Nicholas J. Brooks Roland Winter Judith Peters Philippe M. Oger 《International journal of molecular sciences》2021,22(11)
The modification of archaeal lipid bilayer properties by the insertion of apolar molecules in the lipid bilayer midplane has been proposed to support cell membrane adaptation to extreme environmental conditions of temperature and hydrostatic pressure. In this work, we characterize the insertion effects of the apolar polyisoprenoid squalane on the permeability and fluidity of archaeal model membrane bilayers, composed of lipid analogues. We have monitored large molecule and proton permeability and Laurdan generalized polarization from lipid vesicles as a function of temperature and hydrostatic pressure. Even at low concentration, squalane (1 mol%) is able to enhance solute permeation by increasing membrane fluidity, but at the same time, to decrease proton permeability of the lipid bilayer. The squalane physicochemical impact on membrane properties are congruent with a possible role of apolar intercalants on the adaptation of Archaea to extreme conditions. In addition, such intercalant might be used to cheaply create or modify chemically resistant liposomes (archeaosomes) for drug delivery. 相似文献
994.
Gang Wang Xiaohu Liu Shaofan Li Nicholas Sitar 《International journal for numerical methods in engineering》2005,64(10):1303-1333
In this study, we apply the newly derived finite Eshelby tensor in a variational multiscale formulation to construct a smart element through a more accurate homogenization procedure. The so‐called Neumann–Eshelby tensor for an inclusion in a finite domain is used in the fine scale feedback procedure to take into account the interactions among different scales and elements. Numerical experiments have been conducted to compare the performance and robustness of the new element to earlier formulations. The results showed that the smart element constructed via the Neumann–Eshelby tensor of a finite domain provides better numerical accuracy than that constructed via the Eshelby tensor of an infinite domain. Moreover, it can relieve volumetric locking. Copyright © 2005 John Wiley & Sons, Ltd. 相似文献
995.
Nicholas A Lesica Garrett B Stanley 《IEEE transactions on neural systems and rehabilitation engineering》2005,13(2):194-200
Traditional approaches to characterizing the transformation from stimulus to response in sensory systems assume both stationarity of the stimulus and time-invariance of the stimulus/response mapping. However, recent studies of sensory function under natural stimulus conditions have demonstrated important features of neural encoding that are in violation of these assumptions. Many sensory neurons respond to changes in the statistical distribution of the stimulus that are characteristic of the natural environment with corresponding changes in their encoding properties. In this paper, an extended recursive least-squares (ERLS) approach to adaptive estimation from stimulus/response observations is detailed. The ERLS approach improves the tracking ability of standard RLS approaches to adaptive estimation by removing a number of assumptions about the underlying system and the stimulus environment. The ERLS framework also incorporates an adaptive learning rate, so that prior knowledge of the relationship between the stimulus and the adaptive nature of the system under investigation can be used to improve tracking performance. Simulated and experimental neural responses are used to demonstrate the ability of the ERLS approach to track adaptation of encoding properties during a single stimulus/response trial. The ERLS framework lends tremendous flexibility to experimental design, facilitating the investigation of sensory function under naturalistic stimulus conditions. 相似文献
996.
Nicholas G. Grasby T.J. Fulgoni D.J.F. Beer C.S. Parsons J. Meuris M. Heyns M.M. 《Electron Device Letters, IEEE》2007,28(9):825-827
Compressively strained Ge long channel ring-type pMOSFETs with high-kappa Si/SiO2/HfO2/TiN gate stacks are fabricated on Si0.2Ge0.8 virtual substrates. Effective oxide thickness is approximately 1.4 nm with low gate leakage current. A peak hole mobility of 640 cm2/ Vldrs and up to a four times enhancement over the Si/SiO2 universal curve are observed. Parasitic conduction within the Si-cap layers degrades the mobility at large vertical fields, although up to a 2.5 times enhancement over universal remains at a field of 0.9 MV/cm. 相似文献
997.
Nicholas Mastronarde Deepak S. Turaga Mihaela Van Der Schaar 《Selected Areas in Communications, IEEE Journal on》2007,25(1):108-118
Peer-to-peer collaboration paradigms fundamentally change the passive way wireless stations currently adapt their transmission strategies to match available resources, by enabling them to proactively influence system dynamics through exchange of information and resources. In this paper, we focus on delay-sensitive multimedia transmission among multiple peers over wireless multi-hop enterprise mesh networks. We propose a distributed and efficient framework for resource exchanges that enables peers to collaboratively distribute available wireless resources among themselves based on their quality of service requirements, the underlying channel conditions, and network topology. The resource exchanges are enabled by the scalable coding of the video content and the design of cross-layer optimization strategies, which allow efficient adaptation to varying channel conditions and available resources. We compare our designed low complexity distributed resource exchange algorithms against an optimal centralized resource management scheme and show how their performance varies with the level of collaboration among the peers. We measure system utility in terms of the multimedia quality and show that collaborative approaches achieve ~50% improvement over non-collaborative approaches. Additionally, our distributed algorithms perform within 10% system utility of a centralized optimal resource management scheme. Finally, we observe 2-5 dB improvement in decoded PSNR for each peer due to the deployed cross-layer strategy 相似文献
998.
Erwin Povoden A. Nicholas Grundy Ludwig J. Gauckler 《Journal of Phase Equilibria and Diffusion》2006,27(4):353-362
A comprehensive compilation and evaluation of experimental and thermodynamic data for the Cr−O system is presented and, by
application of the CALPHAD method, a consistent set of thermodynamic model parameters is optimized based on new experiments.
Nonstoichiometry of eskolaite (Cr2O3-δ) is described using the compound energy model, and the liquid, is described using the two-sublattice model for ionic liquids.
Cr3O4 is described as a stoichiometric compound. Also the magnetic transition in Cr2O3 and the oxygen solubility in Cr are modeled. 相似文献
999.
Rajiv Sampath Nicholas Zabaras 《International journal for numerical methods in engineering》1999,44(9):1227-1265
This paper focuses on the numerical simulation of phase‐change processes using a moving finite element technique. In particular, directional solidification and melting processes for pure materials and binary alloys are studied. The melt is modelled as a Boussinesq fluid and the transient Navier–Stokes equations are solved simultaneously with the transient heat and mass transport equations as well as the Stefan condition. The various streamline‐upwind/Petrov–Galerkin‐based FEM simulators developed for the heat, flow and mass transport subproblems are reviewed. The use of classes, virtual functions and smart pointers to represent and link the particular simulators in order to model a phase change process is discussed. The freezing front is modelled using a spline interpolation, while the mesh motion is defined from the freezing front motion using a transfinite mapping technique. Various two‐ and three‐dimensional numerical tests are analysed and discussed to demonstrate the efficiency of the proposed techniques. Copyright © 1999 John Wiley & Sons, Ltd. 相似文献