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On-the-fly dopant redistribution in a silicon nanowire p-n junction

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Nano research 2017年第8期10卷 2845-2855页

作者： Dong-II Moon Myeong-Lok Seol Jin-Woo Han M. Meyyappan center for Nanotechnology NASA Ames Research Center Moffett Field CA 94035 USA

Dopant redistribution in a silicon nanowire （SiNW） p-n junction is found to occur owing to self-heating effects. A SiNW is doped to form back-to-back diodes and is thermally isolated by an oxide layer on its bottom side and by air on the other sides. When a high level of current flows, the inner body temperature is found to increase enough to cause dopant diffusion and even to reach the silicon melting point due to Joule heating. This experimentally observed electrothermal behavior is also validated through numerical simulation. The conductivity change is dependent on the total power density and the change becomes permanent once the device suffers self-heating beyond a threshold point. Finally, the dopant redistribution is directly visualized using scanning capacitance microscopy for the first time.

关键词： nanowire degradation Joule heating dopant redistribution scanning capacitance microscopy

Dynamic Responses of Atmospheric Carbon Dioxide Concentration to Global Temperature Changes between 1850 and 2010

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Advances in Atmospheric Sciences 2016年第2期33卷 247-258页

作者： Weile WANG Ramakrishna NEMANI Department of Science and Environmental Policy California State University at Monterey Bay Earth Science Division NASA Ames Research Center nasa Advanced Supercomputing Division NASA Ames Research Center

Changes in Earth＇s temperature have significant impacts on the global carbon cycle that vary at different time scales, yet to quantify such impacts with a simple scheme is traditionally deemed difficult. Here, we show that, by incorporating a tem- perature sensitivity parameter （1.64 ppm yr-1 ℃-1） into a simple linear carbon-cycle model, we can accurately characterize the dynamic responses of atmospheric carbon dioxide （CO2） concentration to anthropogenic carbon emissions and global temperature changes between 1850 and 2010 （r2 〉 0.96 and the root-mean-square error 〈 1 ppm for the period from 1960 onward）. Analytical analysis also indicates that the multiplication of the parameter with the response time of the atmospheric carbon reservoir （-12 year） approximates the long-term temperature sensitivity of global atmospheric CO2 concentration （-15 ppm ℃ 1）, generally consistent with previous estimates based on reconstructed CO2 and climate records over the Little Ice Age. Our results suggest that recent increases in global surface temperatures, which accelerate the release of carbon from the surface reservoirs into the atmosphere, have partially offset surface carbon uptakes enhanced by the elevated atmo- spheric CO2 concentration and slowed the net rate of atmospheric CO2 sequestration by global land and oceans by -30% since the 1960s. The linear modeling framework outlined in this paper thus provides a useful tool to diagnose the observed atmospheric CO2 dynamics and monitor their future changes.

关键词： atmospheric CO2 dynamics climate-carbon interactions climate change carbon cycle

Robust Adaptive Model Tracking for Distributed Parameter Control of Linear Infinite-dimensional Systems in Hilbert Space

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IEEE/CAA Journal of Automatica Sinica 2014年第3期1卷 294-301页

作者： Mark J.Balas Susan A.Frost the Embry-Riddle Aeronautical University the nasa ames research center

This paper is focused on adaptively controlling a linear infinite-dimensional system to track a finite-dimensional reference *** a linear continuous-time infinite-dimensional plant on a Hilbert space with disturbances of known waveform but unknown amplitude and phase,we show that there exists a stabilizing direct model reference adaptive control law with the properties of certain disturbance rejection and *** plant is described by a closed,densely defined linear operator that generates a continuous semigroup of bounded operators on the Hilbert space of *** central result will show that all errors will converge to a prescribed neighborhood of zero in an infinitedimensional Hilbert *** result will not require the use of the standard Barbalat’s lemma which requires certain signals to be uniformly *** result is used to determine conditions under which a linear infinite-dimensional system can be directly adaptively controlled to follow a reference *** particular,we examine conditions for a set of ideal trajectories to exist for the tracking *** results are applied to adaptive control of general linear diffusion systems described by self-adjoint operators with compact resolvent.

关键词： Adaptation models Adaptive control Hilbert space Learning (artificial intelligence) Robustness Trajectory adaptive control algorithm adaptive theory distributed parameter system Distributed parameter systems Hilbert space trajectory Adaptation models reference model adaptive control Robustness Computer algorithms

The emerging role of mesenchymal stem cell-derived extracellular vesicles to ameliorate hippocampal NLRP3 inflammation induced by binge-like ethanol treatment in adolescence

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Neural Regeneration research 2025年第4期20卷 1153-1163页

作者： Susana Mellado María JoséMorillo-Bargues Carla Perpiñá-Clérigues Francisco García-García Victoria Moreno-Manzano Consuelo Guerri María Pascual Department of Physiology School of Medicine and DentistryUniversity of ValenciaValenciaSpain Bioinformatics and Biostatistics Unit Príncipe Felipe Research CenterValenciaSpain Neuronal and Tissue Regeneration Laboratory Príncipe Felipe Research CenterValenciaSpain

Our previous studies have reported that activation of the NLRP3(NOD-,LRR-and pyrin domain-containing protein 3)-inflammasome complex in ethanol-treated astrocytes and chronic alcohol-fed mice could be associated with neuroinflammation and brain *** stem cell-derived extracellular vesicles(MSC-EVs)have been shown to restore the neuroinflammatory response,along with myelin and synaptic structural alterations in the prefrontal cortex,and alleviate cognitive and memory dysfunctions induced by binge-like ethanol treatment in adolescent *** the therapeutic role of the molecules contained in mesenchymal stem cell-derived extracellular vesicles,the present study analyzed whether the administration of mesenchymal stem cell-derived extracellular vesicles isolated from adipose tissue,which inhibited the activation of the NLRP3 inflammasome,was capable of reducing hippocampal neuroinflammation in adolescent mice treated with binge *** demonstrated that the administration of mesenchymal stem cell-derived extracellular vesicles ameliorated the activation of the hippocampal NLRP3 inflammasome complex and other NLRs inflammasomes(e.g.,pyrin domain-containing 1,caspase recruitment domain-containing 4,and absent in melanoma 2,as well as the alterations in inflammatory genes(interleukin-1β,interleukin-18,inducible nitric oxide synthase,nuclear factor-kappa B,monocyte chemoattractant protein-1,and C–X3–C motif chemokine ligand 1)and miRNAs(miR-21a-5p,miR-146a-5p,and miR-141-5p)induced by binge-like ethanol treatment in adolescent *** analysis further revealed the involvement of miR-21a-5p and miR-146a-5p with inflammatory target genes and NOD-like receptor signaling *** together,these findings provide novel evidence of the therapeutic potential of MSC-derived EVs to ameliorate the hippocampal neuroinflammatory response associated with NLRP3 inflammasome activation induced by binge drinking in adolescence.

关键词： adolescence binge-like ethanol treatment extracellular vesicles hippocampus mesenchymal stem cells neuroinflammation NOD-,LRR-and pyrin domain-containing protein 3(NLRP3)

Bi-Objective Optimal Control Modification Adaptive Control for Systems with Input Uncertainty

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IEEE/CAA Journal of Automatica Sinica 2014年第4期1卷 423-434页

作者： Nhan T.Nguyen Sivasubramanya N.Balakrishnan the nasa ames research center Moffett Field the Missouri University of Science and Technology

This paper presents a new model-reference adaptive control method based on a bi-objective optimal control formulation for systems with input uncertainty. A parallel predictor model is constructed to relate the predictor error to the estimation error of the control effectiveness matrix. In this work, we develop an optimal control modification adaptive control approach that seeks to minimize a bi-objective linear quadratic cost function of both the tracking error norm and the predictor error norm simultaneously. The resulting adaptive laws for the parametric uncertainty and control effectiveness uncertainty are dependent on both the tracking error and the predictor error, while the adaptive laws for the feedback gain and command feedforward gain are only dependent on the tracking error. The optimal control modification term provides robustness to the adaptive laws naturally from the optimal control framework. Simulations demonstrate the effectiveness of the proposed adaptive control approach.

关键词： Optimal control Adaptive control Uncertainty Adaptation models Robustness Cost function nasa Learning (artificial intelligence)

Treadmill exercise in combination with acousto-optic and olfactory stimulation improves cognitive function in APP/PS1 mice through the brain-derived neurotrophic factor-and Cygb-associated signaling pathways

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Neural Regeneration research 2025年第9期20卷 2706-2726页

作者： Biao Xiao Chaoyang Chu Zhicheng Lin Tianyuan Fang Yuyu Zhou Chuxia Zhang Jianghui Shan Shiyu Chen Liping Li Department of Physiology and Pharmacology Health Science CenterNingbo UniversityNingboZhejiang ProvinceChina Ningbo Key Laboratory of Behavioral Neuroscience Health Science CenterNingbo UniversityNingboZhejiang ProvinceChina Key Laboratory of Addiction research of Zhejiang Province NingboZhejiang ProvinceChina

A reduction in adult neurogenesis is associated with behavioral abnormalities in patients with Alzheimer's ***,enhancing adult neurogenesis represents a promising therapeutic approach for mitigating disease symptoms and ***,nonpharmacological interventions aimed at inducing adult neurogenesis are currently *** individual non-pharmacological interventions,such as aerobic exercise,acousto-optic stimulation,and olfactory stimulation,have shown limited capacity to improve neurogenesis and cognitive function in patients with Alzheimer's disease,the therapeutic effect of a strategy that combines these interventions has not been fully *** this study,we observed an age-dependent decrease in adult neurogenesis and a concurrent increase in amyloid-beta accumulation in the hippocampus of amyloid precursor protein/presenilin 1 mice aged 2-8 *** deposition became evident at 4 months,while neurogenesis declined by 6 months,further deteriorating as the disease ***,following a 4-week multifactor stimulation protocol,which encompassed treadmill running(46 min/d,10 m/min,6 days per week),40 Hz acousto-optic stimulation(1 hour/day,6 days/week),and olfactory stimulation(1 hour/day,6 days/week),we found a significant increase in the number of newborn cells(5'-bromo-2'-deoxyuridine-positive cells),immature neurons(doublecortin-positive cells),newborn immature neurons(5'-bromo-2'-deoxyuridine-positive/doublecortin-positive cells),and newborn astrocytes(5'-bromo-2'-deoxyuridine-positive/glial fibrillary acidic protein-positive cells).Additionally,the amyloid-beta load in the hippocampus *** findings suggest that multifactor stimulation can enhance adult hippocampal neurogenesis and mitigate amyloid-beta neuropathology in amyloid precursor protein/presenilin 1 ***,cognitive abilities were improved,and depressive symptoms were alleviated in amyloid precursor protein/presenilin 1 mice

关键词： acousto-optic stimulation adult neurogenesis Alzheimer's disease amyloid precursor protein/presenilin 1 mice amyloid-beta deposition brain cell apoptosis cognitive impairment depression-like behavior involuntary treadmill exercise olfactory stimulation serum metabolites

Carbon Nanotube Based Chemical Sensors

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稀有金属材料与工程 2006年第A03期35卷 7-8页

作者： M. Meyyappan center for Nanotechnology NASA Ames Research Center Mailtstop 229-3Moffett FieldCA 94035USA

Carbon nanotubes CNTs)have been receiving enormous attention in the last decade due to their extraordinary mechanical properties and unique elec- tronic *** combination has produced an unprecedented range of applications for CNTs:elec- tronic,logic and memory chips,chemical and biosen- sots,composites,lithium batteries,gas storage,filters and membranes,*** presentation will focus on carbon nanotube based sensors and discuss fabrication, testing and performance.

关键词： SWNTs CNTs Carbon Nanotube Based Chemical Sensors

Exosomes:the next-generation therapeutic platform for ischemic stroke

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Neural Regeneration research 2025年第5期20卷 1221-1235页

作者： Wenjing Yin Hongyin Ma Yang Qu Jiaxin Ren Yingying Sun Zhen-Ni Guo Yi Yang Stroke center Department of NeurologyFirst Hospital of Jilin UniversityChangchunJilin ProvinceChina Neuroscience research center Department of NeurologyFirst Hospital of Jilin UniversityChangchunJilin ProvinceChina

Current therapeutic strategies for ischemic stroke fall short of the desired objective of neurological functional ***,there is an urgent need to develop new methods for the treatment of this *** are natural cell-derived vesicles that mediate signal transduction between cells under physiological and pathological *** have low immunogenicity,good stability,high delivery efficiency,and the ability to cross the blood–brain *** physiological properties of exosomes have the potential to lead to new breakthroughs in the treatment of ischemic *** rapid development of nanotechnology has advanced the application of engineered exosomes,which can effectively improve targeting ability,enhance therapeutic efficacy,and minimize the dosages *** in technology have also driven clinical translational research on *** this review,we describe the therapeutic effects of exosomes and their positive roles in current treatment strategies for ischemic stroke,including their antiinflammation,anti-apoptosis,autophagy-regulation,angiogenesis,neurogenesis,and glial scar formation reduction ***,it is worth noting that,despite their significant therapeutic potential,there remains a dearth of standardized characterization methods and efficient isolation techniques capable of producing highly purified *** optimization strategies should prioritize the exploration of suitable isolation techniques and the establishment of unified workflows to effectively harness exosomes for diagnostic or therapeutic applications in ischemic ***,our review aims to summarize our understanding of exosome-based treatment prospects in ischemic stroke and foster innovative ideas for the development of exosome-based therapies.

关键词： blood–brain barrier electroacupuncture engineering exercise exosomes ischemic stroke mesenchymal stem cells microglia neuroprotection stents

Reinforcement Learning Based Controller Synthesis for Flexible Aircraft Wings

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IEEE/CAA Journal of Automatica Sinica 2014年第4期1卷 435-448页

作者： Manoj Kumar Karthikeyan Rajagopal Sivasubramanya Nadar Balakrishnan Nhan T.Nguyen the Missouri University of Science&Technology the nasa ames research center Moffet Field

Aeroelastic study of flight vehicles has been a subject of great interest and research in the last several years. Aileron reversal and flutter related problems are due in part to the elasticity of a typical airplane. Structural dynamics of an aircraft wing due to its aeroelastic nature are characterized by partial differential equations. Controller design for these systems is very complex as compared to lumped parameter systems defined by ordinary differential equations. In this paper, a stabilizing statefeedback controller design approach is presented for the heave dynamics of a wing-fuselage model. In this study, a continuous actuator in the spatial domain is assumed. A control methodology is developed by combining the technique of “proper orthogonal decomposition” and approximate dynamic programming. The proper orthogonal decomposition technique is used to obtain a low-order nonlinear lumped parameter model of the infinite dimensional system. Then a near optimal controller is designed using the single-network-adaptive-critic technique. Furthermore,to add robustness to the nominal single-network-adaptive-critic controller against matched uncertainties, an identifier based adaptive controller is proposed. Simulation results demonstrate the effectiveness of the single-network-adaptive-critic controller augmented with adaptive controller for infinite dimensional systems.

关键词： Adaptation models Adaptive control Aircraft Atmospheric modeling Cost function Learning (artificial intelligence) Method of moments Optimal control Single-network-adaptive-critic adaptive control adaptive critic flexible wing partial differential equation proper orthogonal decomposition uncertainty METHOD OF MOMENTS flexible airfoils Optimal control Wings adaptive controller Learning Atmospheric models Partial differential equations Differential equations Control Methods adaptive control Aircraft flexible air vehicles Cost functions Adaptation models