Improved Cognition While Cycling in Parkinson’s Disease Patients and Healthy Adults

PubMed Central

Hazamy, Audrey A.; Altmann, Lori J. P.; Stegemöller, Elizabeth; Bowers, Dawn; Lee, Hyo Keun; Wilson, Jonathan; Okun, Michael S.; Hass, Chris J.

2017-01-01

Persons with Parkinson’s disease (PD) are typically more susceptible than healthy adults to impaired performance when two tasks (dual task interference) are performed simultaneously. This limitation has by many experts been attributed to limitations in cognitive resources. Nearly all studies of dual task performance in PD employ walking or balance-based motor tasks, which are commonly impaired in PD. These tasks can be performed using a combination of one or two executive function tasks. The current study examined whether persons with PD would demonstrate greater dual task effects on cognition compared to healthy older adults (HOAs) during a concurrent cycling task. Participants with and without PD completed a battery of 12 cognitive tasks assessing visual and verbal processing in the following cognitive domains: speed of processing, controlled processing, working memory and executive function. Persons with PD exhibited impairments compared to healthy participants in select tasks (i.e., 0-Back, 2-Back and operation span). Further, both groups unexpectedly exhibited dual task facilitation of response times in visual tasks across cognitive domains, and improved verbal recall during an executive function task. Only one measure, 2-back, showed a speed-accuracy trade-off in the dual task. These results demonstrate that, when paired with a motor task in which they are not impaired, people with PD exhibit similar dual task effects on cognitive tasks as HOAs, even when these dual task effects are facilitative. More generally, these findings demonstrate that pairing cognitive tasks with cycling may actually improve cognitive performance which may have therapeutic relevance to cognitive decline associated with aging and PD pathology. PMID:28088064

STOCKPILED PRAIRIEGRASS PROVIDES HIGH-QUALITY FALL GRAZING FOR LAMBS

USDA-ARS?s Scientific Manuscript database

New varieties of prairiegrass (Bromus catharticus Vahl. = B. willdenowii Kunth.) exhibit improved persistence over ‘Matua’ under USA growing conditions, but animal performance data is lacking. We evaluated performance of lambs grazing stockpiled ‘Dixon’ prairiegrass on West Virginia hill pasture in...

Effects of manipulating the duration and intensity of aerobic training sessions on the physical performance of rats.

PubMed

Teixeira-Coelho, Francisco; Fonseca, Cletiana Gonçalves; Barbosa, Nicolas Henrique Santos; Vaz, Filipe Ferreira; Cordeiro, Letícia Maria de Souza; Coimbra, Cândido Celso; Pires, Washington; Soares, Danusa Dias; Wanner, Samuel Penna

2017-01-01

This study investigated the effects of manipulating the load components of aerobic training sessions on the physical performance of rats. To achieve this purpose, adult male Wistar rats were divided into four groups: an untrained control (CON) group and training groups with a predominant overload in intensity (INT) or duration (DUR) or alternating and similar overloads in intensity and duration (ID). Prior to, during, and after 8 weeks of the control or training protocols, the performance of the rats (evaluated by their workload) was determined during fatiguing, incremental-speed treadmill running. Two additional incremental running tests were performed prior to and at the end of the protocols to measure the peak rate of oxygen consumption (VO2peak). As expected, the rats in the trained groups exhibited increased performance, whereas the untrained rats showed stable performance throughout the 8 weeks. Notably, the performance gain exhibited by the DUR rats reached a plateau after the 4th week. This plateau was not present in the INT or ID rats, which exhibited increased performance at the end of training protocol compared with the DUR rats. None of the training protocols changed the VO2peak values; however, these values were attained at faster speeds, which indicated increased running economy. In conclusion, our findings demonstrate that the training protocols improved the physical performance of rats, likely resulting from enhanced running economy. Furthermore, compared with overload in duration, overload in the intensity of training sessions was more effective at inducing performance improvements across the 8 weeks of the study.

Effects of manipulating the duration and intensity of aerobic training sessions on the physical performance of rats

PubMed Central

Teixeira-Coelho, Francisco; Fonseca, Cletiana Gonçalves; Barbosa, Nicolas Henrique Santos; Vaz, Filipe Ferreira; Cordeiro, Letícia Maria de Souza; Coimbra, Cândido Celso; Pires, Washington; Soares, Danusa Dias

2017-01-01

This study investigated the effects of manipulating the load components of aerobic training sessions on the physical performance of rats. To achieve this purpose, adult male Wistar rats were divided into four groups: an untrained control (CON) group and training groups with a predominant overload in intensity (INT) or duration (DUR) or alternating and similar overloads in intensity and duration (ID). Prior to, during, and after 8 weeks of the control or training protocols, the performance of the rats (evaluated by their workload) was determined during fatiguing, incremental-speed treadmill running. Two additional incremental running tests were performed prior to and at the end of the protocols to measure the peak rate of oxygen consumption (VO2peak). As expected, the rats in the trained groups exhibited increased performance, whereas the untrained rats showed stable performance throughout the 8 weeks. Notably, the performance gain exhibited by the DUR rats reached a plateau after the 4th week. This plateau was not present in the INT or ID rats, which exhibited increased performance at the end of training protocol compared with the DUR rats. None of the training protocols changed the VO2peak values; however, these values were attained at faster speeds, which indicated increased running economy. In conclusion, our findings demonstrate that the training protocols improved the physical performance of rats, likely resulting from enhanced running economy. Furthermore, compared with overload in duration, overload in the intensity of training sessions was more effective at inducing performance improvements across the 8 weeks of the study. PMID:28841706

Teflon/SiO2 Bilayer Passivation for Improving the Electrical Reliability of Oxide TFTs Fabricated Using a New Two-Photomask Self-Alignment Process

PubMed Central

Fan, Ching-Lin; Shang, Ming-Chi; Li, Bo-Jyun; Lin, Yu-Zuo; Wang, Shea-Jue; Lee, Win-Der; Hung, Bohr-Ran

2015-01-01

This study proposes a two-photomask process for fabricating amorphous indium–gallium–zinc oxide (a-IGZO) thin-film transistors (TFTs) that exhibit a self-aligned structure. The fabricated TFTs, which lack etching-stop (ES) layers, have undamaged a-IGZO active layers that facilitate superior performance. In addition, we demonstrate a bilayer passivation method that uses a polytetrafluoroethylene (Teflon) and SiO2 combination layer for improving the electrical reliability of the fabricated TFTs. Teflon was deposited as a buffer layer through thermal evaporation. The Teflon layer exhibited favorable compatibility with the underlying IGZO channel layer and effectively protected the a-IGZO TFTs from plasma damage during SiO2 deposition, resulting in a negligible initial performance drop in the a-IGZO TFTs. Compared with passivation-free a-IGZO TFTs, passivated TFTs exhibited superior stability even after 168 h of aging under ambient air at 95% relative humidity. PMID:28788026

Auditory enhancement of visual perception at threshold depends on visual abilities.

PubMed

Caclin, Anne; Bouchet, Patrick; Djoulah, Farida; Pirat, Elodie; Pernier, Jacques; Giard, Marie-Hélène

2011-06-17

Whether or not multisensory interactions can improve detection thresholds, and thus widen the range of perceptible events is a long-standing debate. Here we revisit this question, by testing the influence of auditory stimuli on visual detection threshold, in subjects exhibiting a wide range of visual-only performance. Above the perceptual threshold, crossmodal interactions have indeed been reported to depend on the subject's performance when the modalities are presented in isolation. We thus tested normal-seeing subjects and short-sighted subjects wearing their usual glasses. We used a paradigm limiting potential shortcomings of previous studies: we chose a criterion-free threshold measurement procedure and precluded exogenous cueing effects by systematically presenting a visual cue whenever a visual target (a faint Gabor patch) might occur. Using this carefully controlled procedure, we found that concurrent sounds only improved visual detection thresholds in the sub-group of subjects exhibiting the poorest performance in the visual-only conditions. In these subjects, for oblique orientations of the visual stimuli (but not for vertical or horizontal targets), the auditory improvement was still present when visual detection was already helped with flanking visual stimuli generating a collinear facilitation effect. These findings highlight that crossmodal interactions are most efficient to improve perceptual performance when an isolated modality is deficient. Copyright © 2011 Elsevier B.V. All rights reserved.

Preliminary evaluation of the Community Multiscale Air Quality model for 2002 over the Southeastern United States.

PubMed

Morris, Ralph E; McNally, Dennis E; Tesche, Thomas W; Tonnesen, Gail; Boylan, James W; Brewer, Patricia

2005-11-01

The Visibility Improvement State and Tribal Association of the Southeast (VISTAS) is one of five Regional Planning Organizations that is charged with the management of haze, visibility, and other regional air quality issues in the United States. The VISTAS Phase I work effort modeled three episodes (January 2002, July 1999, and July 2001) to identify the optimal model configuration(s) to be used for the 2002 annual modeling in Phase II. Using model configurations recommended in the Phase I analysis, 2002 annual meteorological (Mesoscale Meterological Model [MM5]), emissions (Sparse Matrix Operator Kernal Emissions [SMOKE]), and air quality (Community Multiscale Air Quality [CMAQ]) simulations were performed on a 36-km grid covering the continental United States and a 12-km grid covering the Eastern United States. Model estimates were then compared against observations. This paper presents the results of the preliminary CMAQ model performance evaluation for the initial 2002 annual base case simulation. Model performance is presented for the Eastern United States using speciated fine particle concentration and wet deposition measurements from several monitoring networks. Initial results indicate fairly good performance for sulfate with fractional bias values generally within +/-20%. Nitrate is overestimated in the winter by approximately +50% and underestimated in the summer by more than -100%. Organic carbon exhibits a large summer underestimation bias of approximately -100% with much improved performance seen in the winter with a bias near zero. Performance for elemental carbon is reasonable with fractional bias values within +/- 40%. Other fine particulate (soil) and coarse particular matter exhibit large (80-150%) overestimation in the winter but improved performance in the summer. The preliminary 2002 CMAQ runs identified several areas of enhancements to improve model performance, including revised temporal allocation factors for ammonia emissions to improve nitrate performance and addressing missing processes in the secondary organic aerosol module to improve OC performance.

Informal Learning in Science Museum: Development and Evaluation of a Mobile Exhibit Label System with iBeacon Technology

ERIC Educational Resources Information Center

Chen, Guang; Xin, Youlong; Chen, Nian-Shing

2017-01-01

Informal science learning has drawn the attention of researchers, educators and museum administrators for a long time. However, the problem of how to better support visitors to be more engaged while visiting exhibits and improve informal science learning performance is still missing. Context-aware technologies have the advantages of fostering…

Two-D results on human operator perception

NASA Technical Reports Server (NTRS)

Siapkara, A. A.; Sheridan, T. B.

1981-01-01

The application of multidimensional scaling methodology in human factors engineering is presented. The nonorthogonality of internally perceived task variables is exhibited for first and second order plants with both dependent and independent task variables. Directions of operator preference are shown for actual performance, pilot opinion rating, and subjective measures of fatigue, adaptability, and system recognition. Improvement of performance in second order systems is exhibited by the use of bang-bang feedback information. Dissimilarity measures for system comparison are suggested in order to account for human operator rotations and subjective sense of time.

Education Reforms and Innovations to Improve Student Assessment Performance

ERIC Educational Resources Information Center

McAfee, Wade J.

2014-01-01

International assessments such as the Trends in International Mathematics and Science Study (TIMSS) and Program for International Student Assessment (PISA) have exhibited United States students specifically in the fourth and eighth grades, are not performing well when compared to their international peers. Educational stakeholders including…

Method of improving system performance and survivability through changing function

NASA Technical Reports Server (NTRS)

Hinchey, Michael G. (Inventor); Vassev, Emil I. (Inventor)

2012-01-01

A biologically-inspired system and method is provided for self-adapting behavior of swarm-based exploration missions, whereby individual components, for example, spacecraft, in the system can sacrifice themselves for the greater good of the entire system. The swarm-based system can exhibit emergent self-adapting behavior. Each component can be configured to exhibit self-sacrifice behavior based on Autonomic System Specification Language (ASSL).

Shared vision promotes family firm performance.

PubMed

Neff, John E

2015-01-01

A clear picture of the influential drivers of private family firm performance has proven to be an elusive target. The unique characteristics of private family owned firms necessitate a broader, non-financial approach to reveal firm performance drivers. This research study sought to specify and evaluate the themes that distinguish successful family firms from less successful family firms. In addition, this study explored the possibility that these themes collectively form an effective organizational culture that improves longer-term firm performance. At an organizational level of analysis, research findings identified four significant variables: Shared Vision (PNS), Role Clarity (RCL), Confidence in Management (CON), and Professional Networking (OLN) that positively impacted family firm financial performance. Shared Vision exhibited the strongest positive influence among the significant factors. In addition, Family Functionality (APGAR), the functional integrity of the family itself, exhibited a significant supporting role. Taken together, the variables collectively represent an effective family business culture (EFBC) that positively impacted the long-term financial sustainability of family owned firms. The index of effective family business culture also exhibited potential as a predictive non-financial model of family firm performance.

Shared vision promotes family firm performance

PubMed Central

Neff, John E.

2015-01-01

A clear picture of the influential drivers of private family firm performance has proven to be an elusive target. The unique characteristics of private family owned firms necessitate a broader, non-financial approach to reveal firm performance drivers. This research study sought to specify and evaluate the themes that distinguish successful family firms from less successful family firms. In addition, this study explored the possibility that these themes collectively form an effective organizational culture that improves longer-term firm performance. At an organizational level of analysis, research findings identified four significant variables: Shared Vision (PNS), Role Clarity (RCL), Confidence in Management (CON), and Professional Networking (OLN) that positively impacted family firm financial performance. Shared Vision exhibited the strongest positive influence among the significant factors. In addition, Family Functionality (APGAR), the functional integrity of the family itself, exhibited a significant supporting role. Taken together, the variables collectively represent an effective family business culture (EFBC) that positively impacted the long-term financial sustainability of family owned firms. The index of effective family business culture also exhibited potential as a predictive non-financial model of family firm performance. PMID:26042075

Accelerated Dimension-Independent Adaptive Metropolis

DOE PAGES

Chen, Yuxin; Keyes, David E.; Law, Kody J.; ...

2016-10-27

This work describes improvements from algorithmic and architectural means to black-box Bayesian inference over high-dimensional parameter spaces. The well-known adaptive Metropolis (AM) algorithm [33] is extended herein to scale asymptotically uniformly with respect to the underlying parameter dimension for Gaussian targets, by respecting the variance of the target. The resulting algorithm, referred to as the dimension-independent adaptive Metropolis (DIAM) algorithm, also shows improved performance with respect to adaptive Metropolis on non-Gaussian targets. This algorithm is further improved, and the possibility of probing high-dimensional (with dimension d 1000) targets is enabled, via GPU-accelerated numerical libraries and periodically synchronized concurrent chains (justimore » ed a posteriori). Asymptotically in dimension, this GPU implementation exhibits a factor of four improvement versus a competitive CPU-based Intel MKL parallel version alone. Strong scaling to concurrent chains is exhibited, through a combination of longer time per sample batch (weak scaling) and yet fewer necessary samples to convergence. The algorithm performance is illustrated on several Gaussian and non-Gaussian target examples, in which the dimension may be in excess of one thousand.« less

Accelerated Dimension-Independent Adaptive Metropolis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chen, Yuxin; Keyes, David E.; Law, Kody J.

This work describes improvements from algorithmic and architectural means to black-box Bayesian inference over high-dimensional parameter spaces. The well-known adaptive Metropolis (AM) algorithm [33] is extended herein to scale asymptotically uniformly with respect to the underlying parameter dimension for Gaussian targets, by respecting the variance of the target. The resulting algorithm, referred to as the dimension-independent adaptive Metropolis (DIAM) algorithm, also shows improved performance with respect to adaptive Metropolis on non-Gaussian targets. This algorithm is further improved, and the possibility of probing high-dimensional (with dimension d 1000) targets is enabled, via GPU-accelerated numerical libraries and periodically synchronized concurrent chains (justimore » ed a posteriori). Asymptotically in dimension, this GPU implementation exhibits a factor of four improvement versus a competitive CPU-based Intel MKL parallel version alone. Strong scaling to concurrent chains is exhibited, through a combination of longer time per sample batch (weak scaling) and yet fewer necessary samples to convergence. The algorithm performance is illustrated on several Gaussian and non-Gaussian target examples, in which the dimension may be in excess of one thousand.« less

Sensorimotor Rhythm Neurofeedback Enhances Golf Putting Performance.

PubMed

Cheng, Ming-Yang; Huang, Chung-Ju; Chang, Yu-Kai; Koester, Dirk; Schack, Thomas; Hung, Tsung-Min

2015-12-01

Sensorimotor rhythm (SMR) activity has been related to automaticity during skilled action execution. However, few studies have bridged the causal link between SMR activity and sports performance. This study investigated the effect of SMR neurofeedback training (SMR NFT) on golf putting performance. We hypothesized that preelite golfers would exhibit enhanced putting performance after SMR NFT. Sixteen preelite golfers were recruited and randomly assigned into either an SMR or a control group. Participants were asked to perform putting while electroencephalogram (EEG) was recorded, both before and after intervention. Our results showed that the SMR group performed more accurately when putting and exhibited greater SMR power than the control group after 8 intervention sessions. This study concludes that SMR NFT is effective for increasing SMR during action preparation and for enhancing golf putting performance. Moreover, greater SMR activity might be an EEG signature of improved attention processing, which induces superior putting performance.

Ion-exchange composite membranes pore-filled with sulfonated poly(ether ether ketone) and Engelhard titanosilicate-10 for improved performance of vanadium redox flow batteries

NASA Astrophysics Data System (ADS)

Kim, Jihoon; Lee, Yongkyu; Jeon, Jae-Deok; Kwak, Seung-Yeop

2018-04-01

A series of ion-exchange membranes for vanadium redox flow batteries (VRBs) are prepared by filling the pores of a poly(tetrafluoroethylene) (PTFE) substrate with sulfonated poly(ether ether ketone) (SPEEK) and microporous Engelhard titanosilicate-10 (ETS-10). The effects of ETS-10 incorporation and PTFE reinforcement on membrane properties and VRB single-cell performance are investigated using various characterization tools. The results show that these composite membranes exhibit improved mechanical properties and reduced vanadium-ion permeabilities owing to the interactions between ETS-10 and SPEEK, the suppressed swelling of PTFE, and the unique ETS-10 framework. The composite membrane with 3 wt% ETS-10 (referred to as "SE3/P") exhibits the best membrane properties and highest ion selectivity. The VRB system with the SE3/P membrane exhibits higher cell capacity, higher cell efficiency, and lower capacity decay than that with a Nafion membrane. These results indicate that this composite membrane has potential as an alternative to Nafion in VRB systems.

Enhanced performance of Zn(II)-doped lead-acid batteries with electrochemical active carbon in negative mass

NASA Astrophysics Data System (ADS)

Xiang, Jiayuan; Hu, Chen; Chen, Liying; Zhang, Dong; Ding, Ping; Chen, Dong; Liu, Hao; Chen, Jian; Wu, Xianzhang; Lai, Xiaokang

2016-10-01

The effect and mechanism of Zn(II) on improving the performances of lead-acid cell with electrochemical active carbon (EAC) in negative mass is investigated. The hydrogen evolution of the cell is significantly reduced due to the deposition of Zn on carbon surface and the increased porosity of negative mass. Zn(II) additives can also improve the low-temperature and high-rate capacities of the cell with EAC in negative mass, which ascribes to the formation of Zn on lead and carbon surface that constructs a conductive bridge among the active mass. Under the co-contribution of EAC and Zn(II), the partial-state-of-charge cycle life is greatly prolonged. EAC optimizes the NAM structure and porosity to enhance the charge acceptance and retard the lead sulfate accumulation. Zn(II) additive reduces the hydrogen evolution during charge process and improves the electric conductivity of the negative electrode. The cell with 0.6 wt% EAC and 0.006 wt% ZnO in negative mass exhibits 90% reversible capacity of the initial capacity after 2100 cycles. In contrast, the cell with 0.6 wt% EAC exhibits 84% reversible capacity after 2100 cycles and the control cell with no EAC and Zn(II) exhibits less than 80% reversible capacity after 1350 cycles.

Covalent bonding of YIGSR and RGD to PEDOT/PSS/MWCNT-COOH composite material to improve the neural interface.

PubMed

Wang, Kun; Tang, Rong-Yu; Zhao, Xiao-Bo; Li, Jun-Jie; Lang, Yi-Ran; Jiang, Xiao-Xia; Sun, Hong-Ji; Lin, Qiu-Xia; Wang, Chang-Yong

2015-11-28

The development of coating materials for neural interfaces has been a pursued to improve the electrical, mechanical and biological performances. For these goals, a bioactive coating was developed in this work featuring a poly(3,4-ethylenedioxythiophene) (PEDOT)/carbon nanotube (CNT) composite and covalently bonded YIGSR and RGD. Its biological effect and electrical characteristics were assessed in vivo on microwire arrays (MWA). The coated electrodes exhibited a significantly higher charge storage capacity (CSC) and lower electrochemical impedance at 1 kHz which are desired to improve the stimulating and recording performances, respectively. Acute neural recording experiments revealed that coated MWA possess a higher signal/noise ratio capturing spikes undetected by uncoated electrodes. Moreover, coated MWA possessed more active sites and single units, and the noise floor of coated electrodes was lower than that of uncoated electrodes. There is little information in the literature concerning the chronic performance of bioactively modified neural interfaces in vivo. Therefore in this work, chronic in vivo tests were conducted and the PEDOT/PSS/MWCNT-polypeptide coated arrays exhibited excellent performances with the highest mean maximal amplitude from day 4 to day 12 during which the acute response severely compromised the performance of the electrodes. In brief, we developed a simple method of covalently bonding YIGSR and RGD to a PEDOT/PSS/MWCNT-COOH composite improving both the biocompatibility and electrical performance of the neural interface. Our findings suggest that YIGSR and RGD modified PEDOT/PSS/MWCNT is a promising bioactivated composite coating for neural recording and stimulating.

Singing can improve speech function in aphasics associated with intact right basal ganglia and preserve right temporal glucose metabolism: Implications for singing therapy indication.

PubMed

Akanuma, Kyoko; Meguro, Kenichi; Satoh, Masayuki; Tashiro, Manabu; Itoh, Masatoshi

2016-01-01

Clinically, we know that some aphasic patients can sing well despite their speech disturbances. Herein, we report 10 patients with non-fluent aphasia, of which half of the patients improved their speech function after singing training. We studied ten patients with non-fluent aphasia complaining of difficulty finding words. All had lesions in the left basal ganglia or temporal lobe. They selected the melodies they knew well, but which they could not sing. We made a new lyric with a familiar melody using words they could not name. The singing training using these new lyrics was performed for 30 minutes once a week for 10 weeks. Before and after the training, their speech functions were assessed by language tests. At baseline, 6 of them received positron emission tomography to evaluate glucose metabolism. Five patients exhibited improvements after intervention; all but one exhibited intact right basal ganglia and left temporal lobes, but all exhibited left basal ganglia lesions. Among them, three subjects exhibited preserved glucose metabolism in the right temporal lobe. We considered that patients who exhibit intact right basal ganglia and left temporal lobes, together with preserved right hemispheric glucose metabolism, might be an indication of the effectiveness of singing therapy.

Adsorption and photocatalytic degradation of methylene blue using high surface area titanate nanotubes (TNT) synthesized via hydrothermal method

NASA Astrophysics Data System (ADS)

Subramaniam, M. N.; Goh, P. S.; Abdullah, N.; Lau, W. J.; Ng, B. C.; Ismail, A. F.

2017-06-01

Removal of methylene blue (MB) via adsorption and photocatalysis using titanate nanotubes (TNTs) with different surface areas were investigated and compared to commercial titanium dioxide (TiO2) P25 Degussa nanoparticles. The TNTs with surface area ranging from 20 m2/g to 200 m2/g were synthesized via hydrothermal method with different reaction times. TEM imaging confirmed the tubular structure of TNT while XRD spectra indicated all TNTs exhibited anatase crystallinity. Batch adsorption rate showed linearity with surface properties of TNTs, where materials with higher surface area showed higher adsorption rate. The highest MB adsorption (70%) was achieved by TNT24 in 60 min whereas commercial TiO2 exhibited the lowest adsorption of only 10% after 240 min. Adsorption isotherm studies indicated that adsorption using TNT is better fitted into Langmuir adsorption isotherm than Freundlich isotherm model. Furthermore, TNT24 was able to perform up to 90% removal of MB within 120 min, demonstrating performance that is 2-fold better compared to commercial TiO2. The high surface area and surface Bronsted acidity are the main reasons for the improvement in MB removal performance exhibited by TNT24. The improvement in surface acidity enhanced the adsorption properties of all the nanotubes prepared in this study.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Das, Atanu Kumar; Vemuri, Rama Sesha; Kutnyakov, Igor

Here, vapor-assisted dry-gel synthesis of MOF-74 structure, specifically NiMOF-74 from its synthetic precursors, was conducted with high yield and improved performance showing promise for gas (CO 2) and water adsorption applications. Unlike conventional synthesis, which takes 72 h, this kinetic study showed that NiMOF-74 forms within 12 h under dry-gel conditions with similar performance characteristics and exhibits the best performance characteristics after 48 h of heating.

Surface design and engineering of hierarchical hybrid nanostructures for asymmetric supercapacitors with improved electrochemical performance.

PubMed

Achilleos, Demetra S; Hatton, T Alan

2015-06-01

With the current rising world demand for energy sufficiency, there is an increased necessity for the development of efficient energy storage devices. To address these needs, the scientific community has focused on the improvement of the electrochemical properties of the most well known energy storage devices; the Li-ion batteries and electrochemical capacitors, also called supercapacitors. Despite the fact that supercapacitors exhibit high power densities, good reversibility and long cycle life, they still exhibit lower energy densities than batteries, which limit their practical application. Various strategies have been employed to circumvent this problem, specifically targetting an increase in the specific capacitance and the broadening of the potential window of operation of these systems. In recent years, sophisticated surface design and engineering of hierarchical hybrid nanostructures has facilitated significant improvements in the specific and volumetric storage capabilities of supercapacitors. These nanostructured electrodes exhibit higher surface areas for ion adsorption and reduced ion diffusion lengths for the electrolyte ions. Significant advances have also been achieved in broadening the electrochemical window of operation of these systems, as realized via the development of asymmetric two-electrode cells consisting of nanocomposite positive and negative electrodes with complementary electrochemical windows, which operate in environmentally benign aqueous media. We provide an overview of the diverse approaches, in terms of chemistry and nanoscale architecture, employed recently for the development of asymmetric supercapacitors of improved electrochemical performance. Copyright © 2014 Elsevier Inc. All rights reserved.

Feasibility analysis of ultra high performance concrete for prestressed concrete bridge applications.

DOT National Transportation Integrated Search

2010-07-01

UHPC is an emerging material technology in which concrete develops very high : compressive strengths and exhibits improved tensile strength and toughness. A : comprehensive literature and historical application review was completed to determine the :...

Modeling and analysis of Galfenol cantilever vibration energy harvester with nonlinear magnetic force

NASA Astrophysics Data System (ADS)

Cao, Shuying; Sun, Shuaishuai; Zheng, Jiaju; Wang, Bowen; Wan, Lili; Pan, Ruzheng; Zhao, Ran; Zhang, Changgeng

2018-05-01

Galfenol traditional cantilever energy harvesters (TCEHs) have bigger electrical output only at resonance and exhibit nonlinear mechanical-magnetic-electric coupled (NMMEC) behaviors. To increase low-frequency broadband performances of a TCEH, an improved CEH (ICEH) with magnetic repulsive force is studied. Based on the magnetic dipole model, the nonlinear model of material, the Faraday law and the dynamic principle, a lumped parameter NMMEC model of the devices is established. Comparisons between the calculated and measured results show that the proposed model can provide reasonable data trends of TCEH under acceleration, bias field and different loads. Simulated results show that ICEH exhibits low-frequency resonant, hard spring and bistable behaviors, thus can harvest more low-frequency broadband vibration energy than TCEH, and can elicit snap-through and generate higher voltage even under weak noise. The proposed structure and model are useful for improving performances of the devices.

Tuning anion-functionalized ionic liquids for improved SO2 capture.

PubMed

Cui, Guokai; Zheng, Junjie; Luo, Xiaoyan; Lin, Wenjun; Ding, Fang; Li, Haoran; Wang, Congmin

2013-09-27

You can have your cake and eat it too: A "dual-tuning" strategy for improving the capture of SO2 was developed by introducing electron-withdrawing sites on the anions to produce several kinds of functionalized ionic liquids. Those functionalized with a halogen group exhibited improved performance over their non-halogenated counterparts, leading to highly efficient and reversible capture. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Evaluation and field verification of strength and structural improvement of chemically stabilized subgrade soil.

DOT National Transportation Integrated Search

2008-07-01

Often subgrade soils exhibit properties, particularly strength and/or volume change properties that limit their performance as a support element for pavements. : Typical problems include shrink-swell, settlement, collapse, erosion or simply insuffici...

Improving specific activity and thermostability of Escherichia coli phytase by structure-based rational design.

PubMed

Wu, Tzu-Hui; Chen, Chun-Chi; Cheng, Ya-Shan; Ko, Tzu-Ping; Lin, Cheng-Yen; Lai, Hui-Lin; Huang, Ting-Yung; Liu, Je-Ruei; Guo, Rey-Ting

2014-04-10

Escherichia coli phytase (EcAppA) which hydrolyzes phytate has been widely applied in the feed industry, but the need to improve the enzyme activity and thermostability remains. Here, we conduct rational design with two strategies to enhance the EcAppA performance. First, residues near the substrate binding pocket of EcAppA were modified according to the consensus sequence of two highly active Citrobacter phytases. One out of the eleven mutants, V89T, exhibited 17.5% increase in catalytic activity, which might be a result of stabilized protein folding. Second, the EcAppA glycosylation pattern was modified in accordance with the Citrobacter phytases. An N-glycosylation motif near the substrate binding site was disrupted to remove spatial hindrance for phytate entry and product departure. The de-glycosylated mutants showed 9.6% increase in specific activity. On the other hand, the EcAppA mutants that adopt N-glycosylation motifs from CbAppA showed improved thermostability that three mutants carrying single N-glycosylation motif exhibited 5.6-9.5% residual activity after treatment at 80°C (1.8% for wild type). Furthermore, the mutant carrying all three glycosylation motifs exhibited 27% residual activity. In conclusion, a successful rational design was performed to obtain several useful EcAppA mutants with better properties for further applications. Copyright © 2014 Elsevier B.V. All rights reserved.

Speech Motor Sequence Learning: Acquisition and Retention in Parkinson Disease and Normal Aging.

PubMed

Whitfield, Jason A; Goberman, Alexander M

2017-06-10

The aim of the current investigation was to examine speech motor sequence learning in neurologically healthy younger adults, neurologically healthy older adults, and individuals with Parkinson disease (PD) over a 2-day period. A sequential nonword repetition task was used to examine learning over 2 days. Participants practiced a sequence of 6 monosyllabic nonwords that was retested following nighttime sleep. The speed and accuracy of the nonword sequence were measured, and learning was inferred by examining performance within and between sessions. Though all groups exhibited comparable improvements of the nonword sequence performance during the initial session, between-session retention of the nonword sequence differed between groups. Younger adult controls exhibited offline gains, characterized by an increase in the speed and accuracy of nonword sequence performance across sessions, whereas older adults exhibited stable between-session performance. Individuals with PD exhibited offline losses, marked by an increase in sequence duration between sessions. The current results demonstrate that both PD and normal aging affect retention of speech motor learning. Furthermore, these data suggest that basal ganglia dysfunction associated with PD may affect the later stages of speech motor learning. Findings from the current investigation are discussed in relation to studies examining consolidation of nonspeech motor learning.

Improved stability and efficiency of perovskite solar cells with submicron flexible barrier films deposited in air

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rolston, Nicholas; Printz, Adam D.; Hilt, Florian

Here in this paper, we report on submicron organosilicate barrier films produced rapidly in air by a scalable spray plasma process that improves both the stability and efficiency of perovskite solar cells. The plasma is at sufficiently low temperature to prevent damage to the underlying layers. Oxidizing species and heat from the plasma improve device performance by enhancing both interfacial contact and the conductivity of the hole transporting layer. The thickness of the barrier films is tunable and transparent over the entire visible spectrum. The morphology and density of the barrier are shown to improve with the addition of amore » fluorine-based precursor. Devices with submicron coatings exhibited significant improvements in stability, maintaining 92% of their initial power conversion efficiencies after more than 3000 h in dry heat (85 °C, 25% RH) while also being resistant to degradation under simulated operational conditions of continuous exposure to light, heat, and moisture. X-ray diffraction measurements performed while heating showed the barrier film dramatically slows the formation of PbI 2. The barrier films also are compatible with flexible devices, exhibiting no signs of cracking or delamination after 10000 bending cycles on a 127 μm substrate with a bending radius of 1 cm.« less

Improved stability and efficiency of perovskite solar cells with submicron flexible barrier films deposited in air

DOE PAGES

Rolston, Nicholas; Printz, Adam D.; Hilt, Florian; ...

2017-10-27

Here in this paper, we report on submicron organosilicate barrier films produced rapidly in air by a scalable spray plasma process that improves both the stability and efficiency of perovskite solar cells. The plasma is at sufficiently low temperature to prevent damage to the underlying layers. Oxidizing species and heat from the plasma improve device performance by enhancing both interfacial contact and the conductivity of the hole transporting layer. The thickness of the barrier films is tunable and transparent over the entire visible spectrum. The morphology and density of the barrier are shown to improve with the addition of amore » fluorine-based precursor. Devices with submicron coatings exhibited significant improvements in stability, maintaining 92% of their initial power conversion efficiencies after more than 3000 h in dry heat (85 °C, 25% RH) while also being resistant to degradation under simulated operational conditions of continuous exposure to light, heat, and moisture. X-ray diffraction measurements performed while heating showed the barrier film dramatically slows the formation of PbI 2. The barrier films also are compatible with flexible devices, exhibiting no signs of cracking or delamination after 10000 bending cycles on a 127 μm substrate with a bending radius of 1 cm.« less

Ownership conversions and nursing home performance.

PubMed

Grabowski, David C; Stevenson, David G

2008-08-01

To examine the effects of ownership conversions on nursing home performance. Online Survey, Certification, and Reporting system data from 1993 to 2004, and the Minimum Data Set (MDS) facility reports from 1998 to 2004. Regression specification incorporating facility fixed effects, with terms to identify trends in the pre- and postconversion periods. The annual rate of nursing home conversions almost tripled between 1994 and 2004. Our regression results indicate converting facilities are generally different throughout the pre/postconversion years, suggesting little causal effect of ownership conversions on nursing home performance. Before and after conversion, nursing homes converting from nonprofit to for-profit status generally exhibit deterioration in their performance, while nursing homes converting from for-profit to nonprofit status generally exhibit improvement. Policy makers have expressed concern regarding the implications of ownership conversions for nursing home performance. Our results imply that regulators and policy makers should not only monitor the outcomes of nursing home conversions, but also the targets of these conversions.

Synthesis of Co 2SnO 4@C core-shell nanostructures with reversible lithium storage

NASA Astrophysics Data System (ADS)

Qi, Yue; Du, Ning; Zhang, Hui; Wu, Ping; Yang, Deren

This paper reports the synthesis of Co 2SnO 4@C core-shell nanostructures through a simple glucose hydrothermal and subsequent carbonization approach. The as-synthesized Co 2SnO 4@C core-shell nanostructures have been applied as anode materials for lithium-ion batteries, which exhibit improved cyclic performance compared to pure Co 2SnO 4 nanocrystals. The carbon matrix has good volume buffering effect and high electronic conductivity, which may be responsible for the improved cyclic performance.

Carbon-coated SnO2 nanotubes: template-engaged synthesis and their application in lithium-ion batteries

NASA Astrophysics Data System (ADS)

Wu, Ping; Du, Ning; Zhang, Hui; Yu, Jingxue; Qi, Yue; Yang, Deren

2011-02-01

This paper reports the synthesis of carbon-coated SnO2 (SnO2-C) nanotubes through a simple glucose hydrothermal and subsequent carbonization approach by using Sn nanorods as sacrificial templates. The as-synthesized SnO2-C nanotubes have been applied as anode materials for lithium-ion batteries, which exhibit improved cyclic performance compared to pure SnO2 nanotubes. The hollow nanostructure, together with the carbon matrix which has good buffering effect and high electronic conductivity, can be responsible for the improved cyclic performance.

Towards highly stable polymer electronics (Conference Presentation)

NASA Astrophysics Data System (ADS)

Nikolka, Mark; Nasrallah, Iyad; Broch, Katharina; Sadhanala, Aditya; Hurhangee, Michael; McCulloch, Iain; Sirringhaus, Henning

2016-11-01

Due to their ease of processing, organic semiconductors are promising candidates for applications in high performance flexible displays and fast organic electronic circuitry. Recently, a lot of advances have been made on organic semiconductors exhibiting surprisingly high performance and carrier mobilities exceeding those of amorphous silicon. However, there remain significant concerns about their operational and environmental stability, particularly in the context of applications that require a very high level of threshold voltage stability, such as active-matrix addressing of organic light-emitting diode (OLED) displays. Here, we report a novel technique for dramatically improving the operational stress stability, performance and uniformity of high mobility polymer field-effect transistors by the addition of specific small molecule additives to the polymer semiconductor film. We demonstrate for the first time polymer FETs that exhibit stable threshold voltages with threshold voltage shifts of less than 1V when subjected to a constant current operational stress for 1 day under conditions that are representative for applications in OLED active matrix displays. The approach constitutes in our view a technological breakthrough; it also makes the device characteristics independent of the atmosphere in which it is operated, causes a significant reduction in contact resistance and significantly improves device uniformity. We will discuss in detail the microscopic mechanism by which the molecular additives lead to this significant improvement in device performance and stability.

Effects of Inductively Coupled Plasma Hydrogen on Long-Wavelength Infrared HgCdTe Photodiodes

NASA Astrophysics Data System (ADS)

Boieriu, P.; Buurma, C.; Bommena, R.; Blissett, C.; Grein, C.; Sivananthan, S.

2013-12-01

Bulk passivation of semiconductors with hydrogen continues to be investigated for its potential to improve device performance. In this work, hydrogen-only inductively coupled plasma (ICP) was used to incorporate hydrogen into long-wavelength infrared HgCdTe photodiodes grown by molecular-beam epitaxy. Fully fabricated devices exposed to ICP showed statistically significant increases in zero-bias impedance values, improved uniformity, and decreased dark currents. HgCdTe photodiodes on Si substrates passivated with amorphous ZnS exhibited reductions in shunt currents, whereas devices on CdZnTe substrates passivated with polycrystalline CdTe exhibited reduced surface leakage, suggesting that hydrogen passivates defects in bulk HgCdTe and in CdTe.

Reducing Communication in Algebraic Multigrid Using Additive Variants

DOE Office of Scientific and Technical Information (OSTI.GOV)

Vassilevski, Panayot S.; Yang, Ulrike Meier

Algebraic multigrid (AMG) has proven to be an effective scalable solver on many high performance computers. However, its increasing communication complexity on coarser levels has shown to seriously impact its performance on computers with high communication cost. Moreover, additive AMG variants provide not only increased parallelism as well as decreased numbers of messages per cycle but also generally exhibit slower convergence. Here we present various new additive variants with convergence rates that are significantly improved compared to the classical additive algebraic multigrid method and investigate their potential for decreased communication, and improved communication-computation overlap, features that are essential for goodmore » performance on future exascale architectures.« less

Reducing Communication in Algebraic Multigrid Using Additive Variants

DOE PAGES

Vassilevski, Panayot S.; Yang, Ulrike Meier

2014-02-12

Algebraic multigrid (AMG) has proven to be an effective scalable solver on many high performance computers. However, its increasing communication complexity on coarser levels has shown to seriously impact its performance on computers with high communication cost. Moreover, additive AMG variants provide not only increased parallelism as well as decreased numbers of messages per cycle but also generally exhibit slower convergence. Here we present various new additive variants with convergence rates that are significantly improved compared to the classical additive algebraic multigrid method and investigate their potential for decreased communication, and improved communication-computation overlap, features that are essential for goodmore » performance on future exascale architectures.« less

Titanium dioxide@polypyrrole core-shell nanowires for all solid-state flexible supercapacitors.

PubMed

Yu, Minghao; Zeng, Yinxiang; Zhang, Chong; Lu, Xihong; Zeng, Chenghui; Yao, Chenzhong; Yang, Yangyi; Tong, Yexiang

2013-11-21

Herein, we developed a facile two-step process to synthesize TiO2@PPy core-shell nanowires (NWs) on carbon cloth and reported their improved electrochemical performance for flexible supercapacitors (SCs). The fabricated solid-state SC device based on TiO2@PPy core-shell NWs not only has excellent flexibility, but also exhibits remarkable electrochemical performance.

X-ray Diffraction as a Means to Assess Fatigue Performance of Shot-Peened Materials

DTIC Science & Technology

2012-06-01

titanium 6 - 4 fatigue data exhibited similar trends to the 9310 steel material. Low shot- peening intensities (4A and 8A) improved fatigue performance... 6 Figure 4 ...7 Figure 4 . Residual stress and diffraction peak width data from the beta-STOA titanium 6Al-4V disks. attributed to the hardness of the

Carbon and graphene double protection strategy to improve the SnO(x) electrode performance anodes for lithium-ion batteries.

PubMed

Zhu, Jian; Lei, Danni; Zhang, Guanhua; Li, Qiuhong; Lu, Bingan; Wang, Taihong

2013-06-21

SnOx is a promising high-capacity anode material for lithium-ion batteries (LIBs), but it usually exhibits poor cycling stability because of its huge volume variation during the lithium uptake and release process. In this paper, SnOx carbon nanofibers (SnOx@CNFs) are firstly obtained in the form of a nonwoven mat by electrospinning followed by calcination in a 0.02 Mpa environment at 500 °C. Then we use a simple mixing method for the synthesis of SnOx@CNF@graphene (SnOx@C@G) nanocomposite. By this technique, the SnOx@CNFs can be homogeneously deposited in graphene nanosheets (GNSs). The highly scattered SnOx@C@G composite exhibits enhanced electrochemical performance as anode material for LIBs. The double protection strategy to improve the electrode performance through producing SnOx@C@G composites is versatile. In addition, the double protection strategy can be extended to the fabrication of various types of composites between metal oxides and graphene nanomaterials, possessing promising applications in catalysis, sensing, supercapacitors and fuel cells.

Method for manufacturing compound semiconductor field-effect transistors with improved DC and high frequency performance

DOEpatents

Zolper, John C.; Sherwin, Marc E.; Baca, Albert G.

2000-01-01

A method for making compound semiconductor devices including the use of a p-type dopant is disclosed wherein the dopant is co-implanted with an n-type donor species at the time the n-channel is formed and a single anneal at moderate temperature is then performed. Also disclosed are devices manufactured using the method. In the preferred embodiment n-MESFETs and other similar field effect transistor devices are manufactured using C ions co-implanted with Si atoms in GaAs to form an n-channel. C exhibits a unique characteristic in the context of the invention in that it exhibits a low activation efficiency (typically, 50% or less) as a p-type dopant, and consequently, it acts to sharpen the Si n-channel by compensating Si donors in the region of the Si-channel tail, but does not contribute substantially to the acceptor concentration in the buried p region. As a result, the invention provides for improved field effect semiconductor and related devices with enhancement of both DC and high-frequency performance.

Working Memory Updating Training Improves Mathematics Performance in Middle School Students With Learning Difficulties.

PubMed

Zhang, Hongxia; Chang, Lei; Chen, Xiaoying; Ma, Liang; Zhou, Renlai

2018-01-01

Working memory (WM) deficit is considered the key cause of learning difficulties (LDs). Studies have shown that WM is plastic and thus can be improved through training. This positive effect is transferable to fluid intelligence and academic performance. This study investigated whether WM updating ability and academic performance in children with LDs could be improved through WM updating training and explored the effects of this training on the children's brain activity. We used a running memory task lasting approximately 40 min per day for 28 days to train a group of 23 children with LDs (TLDs group). We also selected two control groups of 22 children with LDs (CLDs group) and 20 children without LDs (normal control [NC] group). The behavioral results of a pretest indicated that WM updating ability and academic performance in the TLDs and CLDs groups were significantly lower than those in the NC group before training. Compared with the CLDs group, the TLDs group exhibited significant performance improvement in a 2-back WM task, as well as in mathematical ability. Event-related potentials (ERPs) results suggested that the amplitudes of N160 (representative of visual recognition) and P300 (representative of updating processing, which is a valid index for updating WM) in the TLDs and CLDs groups were markedly lower than those in the NC group before training. In the TLDs group, these two components increased considerably after training, approaching levels similar to those in the NC group. The results of this study suggest that WM updating training can improve WM updating ability in children with LDs and the training effect can transfer to mathematical performance in such children. Furthermore, the participants' brain activity levels can exhibit positive changes. This article provides experimental evidence that WM updating training could mitigate the symptoms of LDs to a certain degree.

Highly Conductive Solid-State Hybrid Electrolytes Operating at Subzero Temperatures.

PubMed

Kwon, Taeyoung; Choi, Ilyoung; Park, Moon Jeong

2017-07-19

We report a unique, highly conductive, dendrite-inhibited, solid-state polymer electrolyte platform that demonstrates excellent battery performance at subzero temperatures. A design based on functionalized inorganic nanoparticles with interconnected mesopores that contain surface nitrile groups is the key to this development. Solid-state hybrid polymer electrolytes based on succinonitrile (SN) electrolytes and porous nanoparticles were fabricated via a simple UV-curing process. SN electrolytes were effectively confined within the mesopores. This stimulated favorable interactions with lithium ions, reduced leakage of SN electrolytes over time, and improved mechanical strength of membranes. Inhibition of lithium dendrite growth and improved electrochemical stability up to 5.2 V were also demonstrated. The hybrid electrolytes exhibited high ionic conductivities of 2 × 10 -3 S cm -1 at room temperature and >10 -4 S cm -1 at subzero temperatures, leading to stable and improved battery performance at subzero temperatures. Li cells made with lithium titanate anodes exhibited stable discharge capacities of 151 mAh g -1 at temperatures below -10 °C. This corresponds to 92% of the capacity achieved at room temperature (164 mAh g -1 ). Our work represents a significant advance in solid-state polymer electrolyte technology and far exceeds the performance available with conventional polymeric battery separators.

Hierarchical NiCo2 O4 nanosheets grown on Ni nanofoam as high-performance electrodes for supercapacitors.

PubMed

Gao, Guoxin; Wu, Hao Bin; Ding, Shujiang; Liu, Li-Min; Lou, Xiong Wen David

2015-02-18

A high-performance electrode for supercapacitors is designed and synthesized by growing electroactive NiCo2 O4 nanosheets on conductive Ni nanofoam. Because of the structural advantages, the as-prepared Ni@NiCo2 O4 hybrid nanostructure exhibits significantly improved electrochemical performance with high capacitance, excellent rate capability, and good cycling stability. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Subsurface Thermal Energy Storage for Improved Heating and Air Conditioning Efficiency

DTIC Science & Technology

2016-11-21

This project involved a field demonstration of subsurface thermal energy storage for improving the geothermal heat pump air conditioning efficiency... geothermal heat pump systems, undesirable heating of the ground may occur. This demonstration was performed at the MCAS, Beaufort, SC, where several...buildings with geothermal heat pump systems were exhibiting excessively high ground loop temperatures. These buildings were retrofitted with dry fluid

High-performance solid-state supercapacitors based on graphene-ZnO hybrid nanocomposites.

PubMed

Li, Zijiong; Zhou, Zhihua; Yun, Gaoqian; Shi, Kai; Lv, Xiaowei; Yang, Baocheng

2013-11-12

In this paper, we report a facile low-cost synthesis of the graphene-ZnO hybrid nanocomposites for solid-state supercapacitors. Structural analysis revealed a homogeneous distribution of ZnO nanorods that are inserted in graphene nanosheets, forming a sandwiched architecture. The material exhibited a high specific capacitance of 156 F g-1 at a scan rate of 5 mV.s-1. The fabricated solid-state supercapacitor device using these graphene-ZnO hybrid nanocomposites exhibits good supercapacitive performance and long-term cycle stability. The improved supercapacitance property of these materials could be ascribed to the increased conductivity of ZnO and better utilization of graphene. These results demonstrate the potential of the graphene-ZnO hybrid nanocomposites as an electrode in high-performance supercapacitors.

High-performance solid-state supercapacitors based on graphene-ZnO hybrid nanocomposites

NASA Astrophysics Data System (ADS)

Li, Zijiong; Zhou, Zhihua; Yun, Gaoqian; Shi, Kai; Lv, Xiaowei; Yang, Baocheng

2013-11-01

In this paper, we report a facile low-cost synthesis of the graphene-ZnO hybrid nanocomposites for solid-state supercapacitors. Structural analysis revealed a homogeneous distribution of ZnO nanorods that are inserted in graphene nanosheets, forming a sandwiched architecture. The material exhibited a high specific capacitance of 156 F g-1 at a scan rate of 5 mV.s-1. The fabricated solid-state supercapacitor device using these graphene-ZnO hybrid nanocomposites exhibits good supercapacitive performance and long-term cycle stability. The improved supercapacitance property of these materials could be ascribed to the increased conductivity of ZnO and better utilization of graphene. These results demonstrate the potential of the graphene-ZnO hybrid nanocomposites as an electrode in high-performance supercapacitors.

High-performance solid-state supercapacitors based on graphene-ZnO hybrid nanocomposites

PubMed Central

2013-01-01

In this paper, we report a facile low-cost synthesis of the graphene-ZnO hybrid nanocomposites for solid-state supercapacitors. Structural analysis revealed a homogeneous distribution of ZnO nanorods that are inserted in graphene nanosheets, forming a sandwiched architecture. The material exhibited a high specific capacitance of 156 F g−1 at a scan rate of 5 mV.s−1. The fabricated solid-state supercapacitor device using these graphene-ZnO hybrid nanocomposites exhibits good supercapacitive performance and long-term cycle stability. The improved supercapacitance property of these materials could be ascribed to the increased conductivity of ZnO and better utilization of graphene. These results demonstrate the potential of the graphene-ZnO hybrid nanocomposites as an electrode in high-performance supercapacitors. PMID:24215772

Mechanical, Thermal and Acoustic Properties of Open-pore Phenolic Multi-structured Cryogel

NASA Astrophysics Data System (ADS)

Yao, Rui; Yao, Zhengjun; Zhou, Jintang; Liu, Peijiang; Lei, Yiming

2017-09-01

Open-pore phenolic cryogel acoustic multi-structured plates (OCMPs) were prepared via modified sol gel polymerization and freeze-dried methods. The pore morphology, mechanical, thermal and acoustic properties of the cryogels were investigated. From the experimental results, the cryogels exhibited a porous sandwich microstructure: A nano-micron double-pore structure was observed in the core layer of the plates, and nanosized pores were observed in the inner part of the micron pores. In addtion, compared with cryogel plates with uniform-pore (OCPs), the OCMPs had lower thermal conductivities. What’s more, the compressive and tensile strength of the OCMPs were much higher than those of OCPs. Finally, the OCMPs exhibited superior acoustic performances (20% solid content OCMPs performed the best) as compared with those of OCPs. Moreover, the sound insulation value and sound absorption bandwidth of OCMPs exhibited an improvement of approximately 3 and 2 times as compared with those of OCPs, respectively.

Three Dimensional Nitrogen-Doped and Nitrogen, Sulfur-Codoped Graphene Hydrogels for Electrode Materials in Supercapacitors.

PubMed

Yuan, Zhao; Qiao, Fei; Wang, Guiqiang; Zhou, Jin; Cui, Hongyou; Zhuo, Shuping; Xing, Ling-Bao

2018-08-01

In present work, reduced graphene oxide hydrogels (RGOHs) with three-dimensional (3D) porous structure are prepared through chemical reduction method by using aminourea (NRGOHs) and aminothiourea (NSRGOHs) as reductants. The as-prepared RGOHs are considered not only as promising electrode materials for supercapacitors, but also the doping of nitrogen (aminourea, NRGOHs) or nitrogen/sulfur (aminothiourea, NSRGOHs) can improve electrochemical performance through faradaic pseudocapacitance. The optimized samples have been prepared by controlling the mass ratios of graphene oxide (GO) to aminourea or aminothiourea to be 1:1, 1:2 and 1:5, respectively. With adding different amounts of aminourea or aminothiourea, the obtained RGOHs exhibited different electrochemical performance in supercapacitors. With increasing the dosage of the reductants, the RGOHs revealed better specific capacitances. Moreover, NSRGOHs with nitrogen, sulfur-codoping exhibited better capacitance performance than that of NRGOHs with only nitrogen-doping. NSRGOHs showed excellent capacitive performance with a very high specific capacitance up to 232.2, 323.3 and 345.6 F g-1 at 0.2 A g-1, while NRGOHs showed capacitive performance with specific capacitance up to 220.6, 306.5 and 332.7 F g-1 at 0.2 A g-1. This provides a strategy to improve the capacitive properties of RGOHs significantly by controlling different doping the materials.

Focusing Light Beams To Improve Atomic-Vapor Optical Buffers

NASA Technical Reports Server (NTRS)

Strekalov, Dmitry; Matsko, Andrey; Savchenkov, Anatoliy

2010-01-01

Specially designed focusing of light beams has been proposed as a means of improving the performances of optical buffers based on cells containing hot atomic vapors (e.g., rubidium vapor). There is also a companion proposal to improve performance by use of incoherent optical pumping under suitable conditions. Regarding the proposal to use focusing: The utility of atomic-vapor optical buffers as optical storage and processing devices has been severely limited by nonuniform spatial distributions of intensity in optical beams, arising from absorption of the beams as they propagate in atomic-vapor cells. Such nonuniformity makes it impossible to optimize the physical conditions throughout a cell, thereby making it impossible to optimize the performance of the cell as an optical buffer. In practical terms simplified for the sake of brevity, "to optimize" as used here means to design the cell so as to maximize the group delay of an optical pulse while keeping the absorption and distortion of the pulse reasonably small. Regarding the proposal to use incoherent optical pumping: For reasons too complex to describe here, residual absorption of light is one of the main impediments to achievement of desirably long group delays in hot atomic vapors. The present proposal is directed toward suppressing residual absorption of light. The idea of improving the performance of slow-light optical buffers by use of incoherent pumping overlaps somewhat with the basic idea of Raman-based slow-light systems. However, prior studies of those systems did not quantitatively answer the question of whether the performance of an atomic vapor or other medium that exhibits electromagnetically induced transparency (EIT) with Raman gain is superior to that of a medium that exhibits EIT without Raman gain.

Carbon and graphene double protection strategy to improve the SnOx electrode performance anodes for lithium-ion batteries

NASA Astrophysics Data System (ADS)

Zhu, Jian; Lei, Danni; Zhang, Guanhua; Li, Qiuhong; Lu, Bingan; Wang, Taihong

2013-05-01

SnOx is a promising high-capacity anode material for lithium-ion batteries (LIBs), but it usually exhibits poor cycling stability because of its huge volume variation during the lithium uptake and release process. In this paper, SnOx carbon nanofibers (SnOx@CNFs) are firstly obtained in the form of a nonwoven mat by electrospinning followed by calcination in a 0.02 Mpa environment at 500 °C. Then we use a simple mixing method for the synthesis of SnOx@CNF@graphene (SnOx@C@G) nanocomposite. By this technique, the SnOx@CNFs can be homogeneously deposited in graphene nanosheets (GNSs). The highly scattered SnOx@C@G composite exhibits enhanced electrochemical performance as anode material for LIBs. The double protection strategy to improve the electrode performance through producing SnOx@C@G composites is versatile. In addition, the double protection strategy can be extended to the fabrication of various types of composites between metal oxides and graphene nanomaterials, possessing promising applications in catalysis, sensing, supercapacitors and fuel cells.SnOx is a promising high-capacity anode material for lithium-ion batteries (LIBs), but it usually exhibits poor cycling stability because of its huge volume variation during the lithium uptake and release process. In this paper, SnOx carbon nanofibers (SnOx@CNFs) are firstly obtained in the form of a nonwoven mat by electrospinning followed by calcination in a 0.02 Mpa environment at 500 °C. Then we use a simple mixing method for the synthesis of SnOx@CNF@graphene (SnOx@C@G) nanocomposite. By this technique, the SnOx@CNFs can be homogeneously deposited in graphene nanosheets (GNSs). The highly scattered SnOx@C@G composite exhibits enhanced electrochemical performance as anode material for LIBs. The double protection strategy to improve the electrode performance through producing SnOx@C@G composites is versatile. In addition, the double protection strategy can be extended to the fabrication of various types of composites between metal oxides and graphene nanomaterials, possessing promising applications in catalysis, sensing, supercapacitors and fuel cells. Electronic supplementary information (ESI) available. See DOI: 10.1039/c3nr00467h

Spectrum-enhanced Au@ZnO plasmonic nanoparticles for boosting dye-sensitized solar cell performance

NASA Astrophysics Data System (ADS)

Liu, Qisheng; Wei, Yunwei; Shahid, Malik Zeeshan; Yao, Mingming; Xu, Bo; Liu, Guangning; Jiang, Kejian; Li, Cuncheng

2018-03-01

Spectrum-enhanced Au@ZnO plasmonic nanoparticles (NPs) are developed for fabrication of the dye-sensitized solar cells (DSSCs), and their remarkable enhanced performances are achieved due to Surface Plasmon Resonance (SPR) effects. When being doped different blended amounts of the Au@ZnO NPs within the photoanode layers, various enhanced effects in the SPR-based DSSCs are exhibited. Compared with the power conversion efficiency (PCE, 7.50%) achieved for bare DSSC, device with doped Au@ZnO NPs of 1.93% delivers the top PCE of 8.91%, exhibiting about 20% enhancement. To elaborate the charge transfer process in the Au@ZnO NPs blended DSSCs, the photoluminescence (PL), electrochemical impedance spectra (EIS), etc are performed. We find that both the enhanced SPR absorption properties and the suppressed recombination process of charges contribute much to the improved performance of Au@ZnO-incorporated DSSCs.

The External Performance Appraisal of China Energy Regulation: An Empirical Study Using a TOPSIS Method Based on Entropy Weight and Mahalanobis Distance.

PubMed

Wang, Zheng-Xin; Li, Dan-Dan; Zheng, Hong-Hao

2018-01-30

In China's industrialization process, the effective regulation of energy and environment can promote the positive externality of energy consumption while reducing negative externality, which is an important means for realizing the sustainable development of an economic society. The study puts forward an improved technique for order preference by similarity to an ideal solution based on entropy weight and Mahalanobis distance (briefly referred as E-M-TOPSIS). The performance of the approach was verified to be satisfactory. By separately using traditional and improved TOPSIS methods, the study carried out the empirical appraisals on the external performance of China's energy regulation during 1999~2015. The results show that the correlation between the performance indexes causes the significant difference between the appraisal results of E-M-TOPSIS and traditional TOPSIS. The E-M-TOPSIS takes the correlation between indexes into account and generally softens the closeness degree compared with traditional TOPSIS. Moreover, it makes the relative closeness degree fluctuate within a small-amplitude. The results conform to the practical condition of China's energy regulation and therefore the E-M-TOPSIS is favorably applicable for the external performance appraisal of energy regulation. Additionally, the external economic performance and social responsibility performance (including environmental and energy safety performances) based on the E-M-TOPSIS exhibit significantly different fluctuation trends. The external economic performance dramatically fluctuates with a larger fluctuation amplitude, while the social responsibility performance exhibits a relatively stable interval fluctuation. This indicates that compared to the social responsibility performance, the fluctuation of external economic performance is more sensitive to energy regulation.

Detailed performance analysis of the A.A.D. - concept B

NASA Technical Reports Server (NTRS)

Sekar, R.; Tozzi, L.

1983-01-01

New concepts for engine performance improvement are seen through the adoption of heat regeneration techniques; advanced methods to enhance the combustion; and higher efficiency air handling machinery, such as the positive displacement helical screw expander and compressor. Each of these concepts plays a particular role in engine performance improvement. First regeneration has a great potential for achieving higher engine thermal efficiency through the recovery of waste energy. Although the concept itself is not new (this technique is used in the gas turbine), the application to reciprocating internal combustion engines is quite unusual and presents conceptual difficulties. The second important area is better control of the combustion process in terms of heat transfer characteristics, combustion products, and heat release rate. The third area for performance improvement is in the adoption of high efficiency air handling machinery. In particular, positive displacement helical expander and compressor exhibit an extremely high efficiency over a wide range of operating conditions.

Cu₂O template synthesis of high-performance PtCu alloy yolk-shell cube catalysts for direct methanol fuel cells.

PubMed

Ye, Sheng-Hua; He, Xu-Jun; Ding, Liang-Xin; Pan, Zheng-Wei; Tong, Ye-Xiang; Wu, Mingmei; Li, Gao-Ren

2014-10-21

Novel PtCu alloy yolk-shell cubes were fabricated via the disproportionation and displacement reactions in Cu2O yolk-shell cubes, and they exhibit significantly improved catalytic activity and durability for methanol electrooxidation.

Conscious knowledge influences decision-making differently in substance abusers with and without co-morbid antisocial personality disorder.

PubMed

Mellentin, Angelina I; Skøt, Lotte; Teasdale, Thomas W; Habekost, Thomas

2013-08-01

Decision-making impairment, as measured by the Iowa Gambling Task (IGT), is a consistent finding among individuals with substance use disorder (SUD). We studied how this impairment is influenced by co-morbid antisocial personality disorder (ASPD) and conscious knowledge of the task. Three groups were investigated: SUD individuals without co-morbid ASPD (n = 30), SUD individuals with co-morbid ASPD (n = 16), and healthy controls (n = 17). Both SUD and SUD+ASPD participants had poor overall IGT performance. A block-by-block analysis revealed that SUD participants exhibited slow but steady improvement across the IGT, whereas SUD+ASPD participants exhibited initial normal improvement, but dropped off during the last 40 trials. Conscious knowledge of the task was significantly correlated to performance for controls and SUD participants, but not for SUD+ASPD participants. Our findings suggest that decision-making proceeds differently in SUD and SUD+ASPD individuals due to differences in acquisition and application of conscious knowledge. © 2013 The Scandinavian Psychological Associations.

n-MoS2/p-Si Solar Cells with Al2O3 Passivation for Enhanced Photogeneration.

PubMed

Rehman, Atteq Ur; Khan, Muhammad Farooq; Shehzad, Muhammad Arslan; Hussain, Sajjad; Bhopal, Muhammad Fahad; Lee, Sang Hee; Eom, Jonghwa; Seo, Yongho; Jung, Jongwan; Lee, Soo Hong

2016-11-02

Molybdenum disulfide (MoS 2 ) has recently emerged as a promising candidate for fabricating ultrathin-film photovoltaic devices. These devices exhibit excellent photovoltaic performance, superior flexibility, and low production cost. Layered MoS 2 deposited on p-Si establishes a built-in electric field at MoS 2 /Si interface that helps in photogenerated carrier separation for photovoltaic operation. We propose an Al 2 O 3 -based passivation at the MoS 2 surface to improve the photovoltaic performance of bulklike MoS 2 /Si solar cells. Interestingly, it was observed that Al 2 O 3 passivation enhances the built-in field by reduction of interface trap density at surface. Our device exhibits an improved power conversion efficiency (PCE) of 5.6%, which to our knowledge is the highest efficiency among all bulklike MoS 2 -based photovoltaic cells. The demonstrated results hold the promise for integration of bulklike MoS 2 films with Si-based electronics to develop highly efficient photovoltaic cells.

Experimental and Numerical Study of the Effect of Gas-Shrouded Plasma Spraying on Cathode Coating of Alkaline Electrolysis Cells

NASA Astrophysics Data System (ADS)

Liu, T.; Reißner, R.; Schiller, G.; Ansar, A.

2018-01-01

The aim of this work is to improve the performance of electrodes prepared via atmospheric plasma spray by means of gas shrouding which is expected to apparently reduce the oxygen content of the plasma plume and subsequently improve the coating quality. Electrodes with dual-layer coating for alkaline water electrolysis were deposited on Ni-coated perforated substrates. Microstructure and morphology were studied by SEM. Element content was measured by EDS. Enthalpy probe was employed for measuring plasma temperature and velocity as well as the gas composition. For verifying and better understanding the shrouding effect numerical calculation was carried out according to the experimental settings. Electrochemical test was carried out to validate the shrouding effect. The results showed slight protecting effect of gas shrouding on plasma plume and the final coating. Over the dual-layer section, the measured oxygen fraction was 3.46 and 3.15% for the case without gas shrouding and with gas shrouding, respectively. With gas shrouding the coating exhibited similar element contents as the coating sprayed by VPS, while no obvious improvement was observed in the microstructure or the morphology. Evident electrochemical improvement was nevertheless achieved that with gas shrouding the electrode exhibited similar performance as that of the VPS-sprayed electrode.

Intensive walking exercise for lower extremity peripheral arterial disease: A systematic review and meta-analysis.

PubMed

Lyu, Xiafei; Li, Sheyu; Peng, Shifeng; Cai, Huimin; Liu, Guanjian; Ran, Xingwu

2016-05-01

Supervised treadmill exercise is the recommended therapy for peripheral arterial disease (PAD) patients with intermittent claudication (IC). However, most PAD patients do not exhibit typical symptoms of IC. The aim of the present study was to explore the efficacy and safety of intensive walking exercise in PAD patients with and without IC. The PubMed, Embase and Cochrane Library databases were systematically searched. Randomized controlled trials comparing the effects of intensive walking exercise with usual care in patients with PAD were included for systematic review and meta-analysis. Eighteen trials with 1200 patients were eligible for the present analysis. Compared with usual care, intensive walking exercise significantly improved the maximal walking distance (MWD), pain-free walking distance, and the 6-min walking distance in patients with PAD (P < 0.00001 for all). Subgroup analyses indicated that a lesser improvement in MWD was observed in the subgroup with more diabetes patients, and that the subgroup with better baseline walking ability exhibited greater improvement in walking performance. In addition, similar improvements in walking performance were observed for exercise programs of different durations and modalities. No significant difference was found in adverse events between the intensive walking and usual care groups (relative risk 0.84; 95% confidence interval 0.51, 1.39; P = 0.50). Regardless of exercise length and modality, regularly intensive walking exercise improves walking ability in PAD patients more than usual care. The presence of diabetes may attenuate the improvements in walking performance in patients with PAD following exercise. © 2015 Ruijin Hospital, Shanghai Jiaotong University School of Medicine and Wiley Publishing Asia Pty Ltd.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lee, Juhee; Lee, Sungpyo; Lee, Moo Hyung

Quasi-unipolar non-volatile organic transistor memory (NOTM) can combine the best characteristics of conventional unipolar and ambipolar NOTMs and, as a result, exhibit improved device performance. Unipolar NOTMs typically exhibit a large signal ratio between the programmed and erased current signals but also require a large voltage to program and erase the memory cells. Meanwhile, an ambipolar NOTM can be programmed and erased at lower voltages, but the resulting signal ratio is small. By embedding a discontinuous n-type fullerene layer within a p-type pentacene film, quasi-unipolar NOTMs are fabricated, of which the signal storage utilizes both electrons and holes while themore » electrical signal relies on only hole conduction. These devices exhibit superior memory performance relative to both pristine unipolar pentacene devices and ambipolar fullerene/pentacene bilayer devices. The quasi-unipolar NOTM exhibited a larger signal ratio between the programmed and erased states while also reducing the voltage required to program and erase a memory cell. This simple approach should be readily applicable for various combinations of advanced organic semiconductors that have been recently developed and thereby should make a significant impact on organic memory research.« less

Application of an imaging system to a museum exhibition for developing interactive exhibitions

NASA Astrophysics Data System (ADS)

Miyata, Kimiyoshi; Inoue, Yuka; Takiguchi, Takahiro; Tsumura, Norimichi; Nakaguchi, Toshiya; Miyake, Yoichi

2009-10-01

In the National Museum of Japanese History, 215,759 artifacts are stored and used for research and exhibitions. In museums, due to the limitation of space in the galleries, a guidance system is required to satisfy visitors' needs and to enhance their understanding of the artifacts. We introduce one exhibition using imaging technology to improve visitors' understanding of a kimono (traditional Japanese clothing) exhibition. In the imaging technology introduced, one data projector, one display with touch panel interface, and magnifiers were used as exhibition tools together with a real kimono. The validity of this exhibition method was confirmed by results from a visitors' interview survey. Second, to further develop the interactive guidance system, an augmented reality system that consisted of cooperation between the projector and a digital video camera was also examined. A white paper board in the observer's hand was used as a projection screen and also as an interface to control the images projected on the board. The basic performance of the proposed system was confirmed; however continuous development was necessary for applying the system to actual exhibitions.

High Per formance and Flexible Supercapacitors based on Carbonized Bamboo Fibers for Wide Temperature Applications

PubMed Central

Zequine, Camila; Ranaweera, C. K.; Wang, Z.; Singh, Sweta; Tripathi, Prashant; Srivastava, O. N.; Gupta, Bipin Kumar; Ramasamy, K.; Kahol, P. K.; Dvornic, P. R.; Gupta, Ram K.

2016-01-01

High performance carbonized bamboo fibers were synthesized for a wide range of temperature dependent energy storage applications. The structural and electrochemical properties of the carbonized bamboo fibers were studied for flexible supercapacitor applications. The galvanostatic charge-discharge studies on carbonized fibers exhibited specific capacity of ~510F/g at 0.4 A/g with energy density of 54 Wh/kg. Interestingly, the carbonized bamboo fibers displayed excellent charge storage stability without any appreciable degradation in charge storage capacity over 5,000 charge-discharge cycles. The symmetrical supercapacitor device fabricated using these carbonized bamboo fibers exhibited an areal capacitance of ~1.55 F/cm2 at room temperature. In addition to high charge storage capacity and cyclic stability, the device showed excellent flexibility without any degradation to charge storage capacity on bending the electrode. The performance of the supercapacitor device exhibited ~65% improvement at 70 °C compare to that at 10 °C. Our studies suggest that carbonized bamboo fibers are promising candidates for stable, high performance and flexible supercapacitor devices. PMID:27546225

High Per formance and Flexible Supercapacitors based on Carbonized Bamboo Fibers for Wide Temperature Applications.

PubMed

Zequine, Camila; Ranaweera, C K; Wang, Z; Singh, Sweta; Tripathi, Prashant; Srivastava, O N; Gupta, Bipin Kumar; Ramasamy, K; Kahol, P K; Dvornic, P R; Gupta, Ram K

2016-08-22

High performance carbonized bamboo fibers were synthesized for a wide range of temperature dependent energy storage applications. The structural and electrochemical properties of the carbonized bamboo fibers were studied for flexible supercapacitor applications. The galvanostatic charge-discharge studies on carbonized fibers exhibited specific capacity of ~510F/g at 0.4 A/g with energy density of 54 Wh/kg. Interestingly, the carbonized bamboo fibers displayed excellent charge storage stability without any appreciable degradation in charge storage capacity over 5,000 charge-discharge cycles. The symmetrical supercapacitor device fabricated using these carbonized bamboo fibers exhibited an areal capacitance of ~1.55 F/cm(2) at room temperature. In addition to high charge storage capacity and cyclic stability, the device showed excellent flexibility without any degradation to charge storage capacity on bending the electrode. The performance of the supercapacitor device exhibited ~65% improvement at 70 °C compare to that at 10 °C. Our studies suggest that carbonized bamboo fibers are promising candidates for stable, high performance and flexible supercapacitor devices.

High Per formance and Flexible Supercapacitors based on Carbonized Bamboo Fibers for Wide Temperature Applications

NASA Astrophysics Data System (ADS)

Zequine, Camila; Ranaweera, C. K.; Wang, Z.; Singh, Sweta; Tripathi, Prashant; Srivastava, O. N.; Gupta, Bipin Kumar; Ramasamy, K.; Kahol, P. K.; Dvornic, P. R.; Gupta, Ram K.

2016-08-01

High performance carbonized bamboo fibers were synthesized for a wide range of temperature dependent energy storage applications. The structural and electrochemical properties of the carbonized bamboo fibers were studied for flexible supercapacitor applications. The galvanostatic charge-discharge studies on carbonized fibers exhibited specific capacity of ~510F/g at 0.4 A/g with energy density of 54 Wh/kg. Interestingly, the carbonized bamboo fibers displayed excellent charge storage stability without any appreciable degradation in charge storage capacity over 5,000 charge-discharge cycles. The symmetrical supercapacitor device fabricated using these carbonized bamboo fibers exhibited an areal capacitance of ~1.55 F/cm2 at room temperature. In addition to high charge storage capacity and cyclic stability, the device showed excellent flexibility without any degradation to charge storage capacity on bending the electrode. The performance of the supercapacitor device exhibited ~65% improvement at 70 °C compare to that at 10 °C. Our studies suggest that carbonized bamboo fibers are promising candidates for stable, high performance and flexible supercapacitor devices.

Controllable Fabrication of Amorphous Co-Ni Pyrophosphates for Tuning Electrochemical Performance in Supercapacitors.

PubMed

Chen, Chen; Zhang, Ning; He, Yulu; Liang, Bo; Ma, Renzhi; Liu, Xiaohe

2016-09-07

Incorporation of two transition metals offers an effective method to enhance the electrochemical performance in supercapacitors for transition metal compound based electrodes. However, such a configuration is seldom concerned in pyrophosphates. Here, amorphous phase Co-Ni pyrophosphates are fabricated as electrodes in supercapacitors. Through controllably adjusting the ratios of Co and Ni as well as the calcination temperature, the electrochemical performance can be tuned. An optimized amorphous Ni-Co pyrophosphate exhibits much higher specific capacitance than monometallic Ni and Co pyrophosphates and shows excellent cycling ability. When employing Ni-Co pyrophosphates as positive electrode and activated carbon as a negative electrode, the fabricated asymmetric supercapacitor cell exhibits favorable capacitance and cycling ability. This study provides facile methods to improve the transition metal pyrophosphate electrodes for efficient electrodes in electrochemical energy storage devices.

Preparation of Co-Zn ferrite nano-based materials and their enhanced magnetic performance via inverse miniemulsion method

NASA Astrophysics Data System (ADS)

Ji, Juejin; Zhang, Zhenqian; Fang, Bijun; Ding, Jianning

2017-11-01

The well dispersed CZF/PAM nanoparticles were prepared by the inverse miniemulsion method, which present high calcining and sintering activity for preparing Co0.875Zn0.125Fe2O4 (CZF) films, powders and ceramics at rather low temperatures. The prepared CZF/PAM inverse miniemulsion exhibits excellent film-formation performance, which is feasible for coating CZF films. XRD and FT-IR measurements confirmed that phase pure spinel structure and well crystalline CZF powders can be prepared calcined at the least temperature of 400 °C. The 450 °C-calcined CZF powders exhibit nearly spherical shape grains with average particle size 20-30 nm accompanied by apparent conglomeration. Improved external magnetic performance and electrical properties are obtained in the synthesized CZF powders and ceramics, which provide versatile promising applications.

Beneficial Properties of Probiotics.

PubMed

Shi, Lye Huey; Balakrishnan, Kunasundari; Thiagarajah, Kokila; Mohd Ismail, Nor Ismaliza; Yin, Ooi Shao

2016-08-01

Probiotics are live microorganisms that can be found in fermented foods and cultured milk, and are widely used for the preparation of infant food. They are well-known as "health friendly bacteria", which exhibit various health beneficial properties such as prevention of bowel diseases, improving the immune system, for lactose intolerance and intestinal microbial balance, exhibiting antihypercholesterolemic and antihypertensive effects, alleviation of postmenopausal disorders, and reducing traveller's diarrhoea. Recent studies have also been focused on their uses in treating skin and oral diseases. In addition to that, modulation of the gut-brain by probiotics has been suggested as a novel therapeutic solution for anxiety and depression. Thus, this review discusses on the current probiotics-based products in Malaysia, criteria for selection of probiotics, and evidences obtained from past studies on how probiotics have been used in preventing intestinal disorders via improving the immune system, acting as an antihypercholesterolemic factor, improving oral and dermal health, and performing as anti-anxiety and anti-depressive agents.

Functional solid additive modified PEDOT:PSS as an anode buffer layer for enhanced photovoltaic performance and stability in polymer solar cells

PubMed Central

Xu, Binrui; Gopalan, Sai-Anand; Gopalan, Anantha-Iyengar; Muthuchamy, Nallal; Lee, Kwang-Pill; Lee, Jae-Sung; Jiang, Yu; Lee, Sang-Won; Kim, Sae-Wan; Kim, Ju-Seong; Jeong, Hyun-Min; Kwon, Jin-Beon; Bae, Jin-Hyuk; Kang, Shin-Won

2017-01-01

Poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) is most commonly used as an anode buffer layer in bulk-heterojunction (BHJ) polymer solar cells (PSCs). However, its hygroscopic and acidic nature contributes to the insufficient electrical conductivity, air stability and restricted photovoltaic (PV) performance for the fabricated PSCs. In this study, a new multifunctional additive, 2,3-dihydroxypyridine (DOH), has been used in the PEDOT: PSS buffer layer to obtain modified properties for PEDOT: PSS@DOH and achieve high PV performances. The electrical conductivity of PEDOT:PSS@DOH films was markedly improved compared with that of PEDOT:PSS. The PEDOT:PSS@DOH film exhibited excellent optical characteristics, appropriate work function alignment, and good surface properties in BHJ-PSCs. When a poly(3-hexylthiohpene):[6,6]-phenyl C61-butyric acid methyl ester blend system was applied as the photoactive layer, the power conversion efficiency of the resulting PSCs with PEDOT:PSS@DOH(1.0%) reached 3.49%, outperforming pristine PEDOT:PSS, exhibiting a power conversion enhancement of 20%. The device fabricated using PEDOT:PSS@DOH (1.0 wt%) also exhibited improved thermal and air stability. Our results also confirm that DOH, a basic pyridine derivative, facilitates adequate hydrogen bonding interactions with the sulfonic acid groups of PSS, induces the conformational transformation of PEDOT chains and contributes to the phase separation between PEDOT and PSS chains. PMID:28338088

Functional solid additive modified PEDOT:PSS as an anode buffer layer for enhanced photovoltaic performance and stability in polymer solar cells

NASA Astrophysics Data System (ADS)

Xu, Binrui; Gopalan, Sai-Anand; Gopalan, Anantha-Iyengar; Muthuchamy, Nallal; Lee, Kwang-Pill; Lee, Jae-Sung; Jiang, Yu; Lee, Sang-Won; Kim, Sae-Wan; Kim, Ju-Seong; Jeong, Hyun-Min; Kwon, Jin-Beon; Bae, Jin-Hyuk; Kang, Shin-Won

2017-03-01

Poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) is most commonly used as an anode buffer layer in bulk-heterojunction (BHJ) polymer solar cells (PSCs). However, its hygroscopic and acidic nature contributes to the insufficient electrical conductivity, air stability and restricted photovoltaic (PV) performance for the fabricated PSCs. In this study, a new multifunctional additive, 2,3-dihydroxypyridine (DOH), has been used in the PEDOT: PSS buffer layer to obtain modified properties for PEDOT: PSS@DOH and achieve high PV performances. The electrical conductivity of PEDOT:PSS@DOH films was markedly improved compared with that of PEDOT:PSS. The PEDOT:PSS@DOH film exhibited excellent optical characteristics, appropriate work function alignment, and good surface properties in BHJ-PSCs. When a poly(3-hexylthiohpene):[6,6]-phenyl C61-butyric acid methyl ester blend system was applied as the photoactive layer, the power conversion efficiency of the resulting PSCs with PEDOT:PSS@DOH(1.0%) reached 3.49%, outperforming pristine PEDOT:PSS, exhibiting a power conversion enhancement of 20%. The device fabricated using PEDOT:PSS@DOH (1.0 wt%) also exhibited improved thermal and air stability. Our results also confirm that DOH, a basic pyridine derivative, facilitates adequate hydrogen bonding interactions with the sulfonic acid groups of PSS, induces the conformational transformation of PEDOT chains and contributes to the phase separation between PEDOT and PSS chains.

Performance model-directed data sieving for high-performance I/O

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chen, Yong; Lu, Yin; Amritkar, Prathamesh

2014-09-10

Many scientific computing applications and engineering simulations exhibit noncontiguous I/O access patterns. Data sieving is an important technique to improve the performance of noncontiguous I/O accesses by combining small and noncontiguous requests into a large and contiguous request. It has been proven effective even though more data are potentially accessed than demanded. In this study, we propose a new data sieving approach namely performance model-directed data sieving, or PMD data sieving in short. It improves the existing data sieving approach from two aspects: (1) dynamically determines when it is beneficial to perform data sieving; and (2) dynamically determines how tomore » perform data sieving if beneficial. It improves the performance of the existing data sieving approach considerably and reduces the memory consumption as verified by both theoretical analysis and experimental results. Given the importance of supporting noncontiguous accesses effectively and reducing the memory pressure in a large-scale system, the proposed PMD data sieving approach in this research holds a great promise and will have an impact on high-performance I/O systems.« less

Improvements in Concentration, Working Memory, and Sustained Attention Following Consumption of a Natural Citicoline-Caffeine Beverage

PubMed Central

Bruce, Steven E.; Werner, Kimberly B.; Preston, Brittany F.; Baker, Laurie M.

2015-01-01

The present study examined the neurocognitive and electrophysiological effects of a citicoline-caffeine-based beverage in 60 healthy adult participants enrolled in a randomized, double-blind, placebo-controlled trial. Measures of electrical brain activity using electroencephalogram (EEG) and neuropsychological measures examining attention, concentration, and reaction time were administered. Compared to placebo, participants receiving the citicoline-caffeine beverage exhibited significantly faster maze learning times and reaction times on a continuous performance test, fewer errors in a Go No-Go task, and better accuracy on a measure of information processing speed. EEG results examining P450 event related potentials (ERP) revealed that participants receiving the citicoline-caffeine beverage exhibited higher P450 amplitudes than controls, suggesting an increase in sustained attention. Overall, these findings suggest that the beverage significantly improved sustained attention, cognitive effort, and reaction times in healthy adults. Evidence of improved P450 amplitude indicates a general improvement in the ability to accommodate new and relevant information within working memory and overall enhanced brain activation. PMID:25046515

Relative health performance in BRICS over the past 20 years: the winners and losers.

PubMed

Petrie, Dennis; Tang, Kam Ki

2014-06-01

To determine whether the health performance of Brazil, the Russian Federation, India, China and South Africa--the countries known as BRICS--has kept in step with their economic development. Reductions in age- and sex-specific mortality seen in each BRICS country between 1990 and 2011 were measured. These results were compared with those of the best-performing countries in the world and the best-performing countries with similar income levels. We estimated each country's progress in reducing mortality and compared changes in that country's mortality rates against other countries with similar mean incomes to examine changes in avoidable mortality. The relative health performance of the five study countries differed markedly over the study period. Brazil demonstrated fairly even improvement in relative health performance across the different age and sex subgroups that we assessed. India's improvement was more modest and more varied across the subgroups. South Africa and the Russian Federation exhibited large declines in health performance as well as large sex-specific inequalities in health. Although China's levels of avoidable mortality decreased in absolute terms, the level of improvement appeared low in the context of China's economic growth. When evaluating a country's health performance in terms of avoidable mortality, it is useful to compare that performance against the performance of other countries. Such comparison allows any country-specific improvements to be distinguished from general global improvements.

Exercise improves behavioral, neurocognitive, and scholastic performance in children with attention-deficit/hyperactivity disorder.

PubMed

Pontifex, Matthew B; Saliba, Brian J; Raine, Lauren B; Picchietti, Daniel L; Hillman, Charles H

2013-03-01

To examine the effect of a single bout of moderate-intensity aerobic exercise on preadolescent children with attention-deficit/hyperactivity disorder (ADHD) using objective measures of attention, brain neurophysiology, and academic performance. Using a within-participants design, task performance and event-related brain potentials were assessed while participants performed an attentional-control task following a bout of exercise or seated reading during 2 separate, counterbalanced sessions. Following a single 20-minute bout of exercise, both children with ADHD and healthy match control children exhibited greater response accuracy and stimulus-related processing, with the children with ADHD also exhibiting selective enhancements in regulatory processes, compared with after a similar duration of seated reading. In addition, greater performance in the areas of reading and arithmetic were observed following exercise in both groups. These findings indicate that single bouts of moderately intense aerobic exercise may have positive implications for aspects of neurocognitive function and inhibitory control in children with ADHD. Copyright © 2013 Mosby, Inc. All rights reserved.

Investigation of Fluorination on Donor Moiety of Donor-Acceptor 4,7-Dithienylbenzothiadiazole-Based Conjugated Polymers toward Enhanced Photovoltaic Efficiency.

PubMed

Li, Yonghai; Wang, Junyi; Liu, Yan; Qiu, Meng; Wen, Shuguang; Bao, Xichang; Wang, Ning; Sun, Mingliang; Yang, Renqiang

2016-10-05

It is known that fluorination on π-conjugated donor-acceptor (D-A) polymers can significantly affect the optoelectronic properties and fluorination on A moiety has been well established for design of efficient photovoltaic materials. For example, polymers based on 4,7-dithienyl-5,6-difluorobenzothiadiazole (DTffBT) have been intensively investigated and exhibited excellent performance, but the corresponding DTBT-based polymers without fluorine often display an unfavorable efficiency. With the purpose of improving photovoltaic efficiency of DTBT-based D-A polymers, we design three polymers PDTBT-TxfBT (x = 0, 1, 2) with fluorination on D moiety (TxfBT) and systematically investigate fluorination on the photophysical/electrochemical and photovoltaic properties. The results show that polymer solar cells (PSCs) based on PDTBT-TBT exhibit moderate power conversion efficiency (PCE) of 5.84%. However, the bis-fluorination on TffBT moiety (PDTBT-TffBT) can greatly enhance the molecular planarity and intermolecular interaction, improve the charge transport and heterojunction morphology, and further suppress the charge recombination losses. PSCs based on PDTBT-TffBT demonstrate obviously improved photovoltaic efficiency with the best PCE up to 7.53% without any processing additives, which ranks among the top DTBT-based PSCs. However, it should be noted that unsymmetrical fluorination on TfBT moiety (PDTBT-TfBT) impairs the regularity of polymer backbone and intermolecular interaction, increases the recombination losses, and seriously reduces the short-circuit current density and efficiency (5.44%). The results exhibit that fluorination on D moiety is a helpful strategy for design high-performance photovoltaic materials and the regularity of fluorination is crucial to improving efficiencies.

Electrocatalysis for oxygen electrodes in fuel cells and water electrolyzers for space applications

NASA Technical Reports Server (NTRS)

Prakash, Jai; Tryk, Donald; Yeager, Ernest

1990-01-01

The lead ruthenate pyrochlore Pb2Ru2O6.5, in both high- and low-area forms, has been characterized using thermogravimetric analysis, X-ray photoelectron spectroscopy, X-ray diffraction, cyclic voltammetry, and O2 reduction and generation kinetic-mechanistic studies. Mechanisms are proposed. Compounds in which part of the Ru is substituted with Ir have also been prepared. They exhibit somewhat better performance for O2 reduction in porous, gas-fed electrodes than the unsubstituted compound. The anodic corrosion resistance of pyrochlore-based porous electrodes was improved by using two different anionically conducting polymer overlayers, which slow down the diffusion of ruthenate and plumbate out of the electrode. The O2 generation performance was improved with both types of electrodes. With a hydrogel overlayer, the O2 reduction performance was also improved.

Analysis of gait symmetry during over-ground walking in children with autism spectrum disorder.

PubMed

Eggleston, Jeffrey D; Harry, John R; Hickman, Robbin A; Dufek, Janet S

2017-06-01

Gait symmetry is utilized as an indicator of neurologic function. Healthy gait often exhibits minimal asymmetries, while pathological gait exhibits exaggerated asymmetries. The purpose of this study was to examine symmetry of mechanical gait parameters during over-ground walking in children with Autism Spectrum Disorder (ASD). Kinematic and kinetic data were obtained from 10 children (aged 5-12 years) with ASD. The Model Statistic procedure (α=0.05) was used to compare gait related parameters between limbs. Analysis revealed children with ASD exhibit significant lower extremity joint position and ground reaction force asymmetries throughout the gait cycle. The observed asymmetries were unique for each subject. These data do not support previous research relative to gait symmetry in children with ASD. Many individuals with ASD do not receive physical therapy interventions, however, precision medicine based interventions emphasizing lower extremity asymmetries may improve gait function and improve performance during activities of daily living. Copyright © 2017 Elsevier B.V. All rights reserved.

Improvement in top-gate MoS2 transistor performance due to high quality backside Al2O3 layer

NASA Astrophysics Data System (ADS)

Bolshakov, Pavel; Zhao, Peng; Azcatl, Angelica; Hurley, Paul K.; Wallace, Robert M.; Young, Chadwin D.

2017-07-01

A high quality Al2O3 layer is developed to achieve high performance in top-gate MoS2 transistors. Compared with top-gate MoS2 field effect transistors on a SiO2 layer, the intrinsic mobility and subthreshold slope were greatly improved in high-k backside layer devices. A forming gas anneal is found to enhance device performance due to a reduction in the charge trap density of the backside dielectric. The major improvements in device performance are ascribed to the forming gas anneal and the high-k dielectric screening effect of the backside Al2O3 layer. Top-gate devices built upon these stacks exhibit a near-ideal subthreshold slope of ˜69 mV/dec and a high Y-Function extracted intrinsic carrier mobility (μo) of 145 cm2/V.s, indicating a positive influence on top-gate device performance even without any backside bias.

Performance improvement for solution-processed high-mobility ZnO thin-film transistors

NASA Astrophysics Data System (ADS)

Sha Li, Chen; Li, Yu Ning; Wu, Yi Liang; Ong, Beng S.; Loutfy, Rafik O.

2008-06-01

The fabrication technology of stable, non-toxic, transparent, high performance zinc oxide (ZnO) thin-film semiconductors via the solution process was investigated. Two methods, which were, respectively, annealing a spin-coated precursor solution and annealing a drop-coated precursor solution, were compared. The prepared ZnO thin-film semiconductor transistors have well-controlled, preferential crystal orientation and exhibit superior field-effect performance characteristics. But the ZnO thin-film transistor (TFT) fabricated by annealing a drop-coated precursor solution has a distinctly elevated linear mobility, which further approaches the saturated mobility, compared with that fabricated by annealing a spin-coated precursor solution. The performance of the solution-processed ZnO TFT was further improved when substituting the spin-coating process by the drop-coating process.

Feedback associated with expectation for larger-reward improves visuospatial working memory performances in children with ADHD.

PubMed

Hammer, Rubi; Tennekoon, Michael; Cooke, Gillian E; Gayda, Jessica; Stein, Mark A; Booth, James R

2015-08-01

We tested the interactive effect of feedback and reward on visuospatial working memory in children with ADHD. Seventeen boys with ADHD and 17 Normal Control (NC) boys underwent functional magnetic resonance imaging (fMRI) while performing four visuospatial 2-back tasks that required monitoring the spatial location of letters presented on a display. Tasks varied in reward size (large; small) and feedback availability (no-feedback; feedback). While the performance of NC boys was high in all conditions, boys with ADHD exhibited higher performance (similar to those of NC boys) only when they received feedback associated with large-reward. Performance pattern in both groups was mirrored by neural activity in an executive function neural network comprised of few distinct frontal brain regions. Specifically, neural activity in the left and right middle frontal gyri of boys with ADHD became normal-like only when feedback was available, mainly when feedback was associated with large-reward. When feedback was associated with small-reward, or when large-reward was expected but feedback was not available, boys with ADHD exhibited altered neural activity in the medial orbitofrontal cortex and anterior insula. This suggests that contextual support normalizes activity in executive brain regions in children with ADHD, which results in improved working memory. Copyright © 2015 The Authors. Published by Elsevier Ltd.. All rights reserved.

Implicit Coordination Strategies for Effective Team Communication.

PubMed

Butchibabu, Abhizna; Sparano-Huiban, Christopher; Sonenberg, Liz; Shah, Julie

2016-06-01

We investigated implicit communication strategies for anticipatory information sharing during team performance of tasks with varying degrees of complexity. We compared the strategies used by teams with the highest level of performance to those used by the lowest-performing teams to evaluate the frequency and methods of communications used as a function of task structure. High-performing teams share information by anticipating the needs of their teammates rather than explicitly requesting the exchange of information. As the complexity of a task increases to involve more interdependence among teammates, the impact of coordination on team performance also increases. This observation motivated us to conduct a study of anticipatory information sharing as a function of task complexity. We conducted an experiment in which 13 teams of four people performed collaborative search-and-deliver tasks with varying degrees of complexity in a simulation environment. We elaborated upon prior characterizations of communication as implicit versus explicit by dividing implicit communication into two subtypes: (a) deliberative/goal information and (b) reactive status updates. We then characterized relationships between task structure, implicit communication, and team performance. We found that the five teams with the fastest task completion times and lowest idle times exhibited higher rates of deliberative communication versus reactive communication during high-complexity tasks compared with the five teams with the slowest completion times and longest idle times (p = .039). Teams in which members proactively communicated information about their next goal to teammates exhibited improved team performance. The findings from our work can inform the design of communication strategies for team training to improve performance of complex tasks. © 2016, Human Factors and Ergonomics Society.

Thallium bromide radiation detectors

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shah, K.S.; Lund, J.C.; Olschner, F.

1989-02-01

Radiation detectors have been fabricated from crystals of the semiconductor material thallium bromide (TlBr) and the performance of these detectors as room temperature photon spectrometers has been measured. These detectors exhibit improved energy resolution over previously reported TlBr detectors. These results indicate that TlBr is a very promising radiation detector material.

Targeting L-Selectin to Improve Neurologic and Urologic Function After Spinal Cord Injury

DTIC Science & Technology

2013-10-01

locomotor recovery. When cystometry was performed at the end of the study, 29/34 (~85%) of mice exhibited partial or complete voluntary bladder...0.05). Following euthanasia , bladders were removed, weighed, and normalized to total bodyweight (Figure 11C). One-way ANOVA demonstrated no

Short-term music training enhances verbal intelligence and executive function.

PubMed

Moreno, Sylvain; Bialystok, Ellen; Barac, Raluca; Schellenberg, E Glenn; Cepeda, Nicholas J; Chau, Tom

2011-11-01

Researchers have designed training methods that can be used to improve mental health and to test the efficacy of education programs. However, few studies have demonstrated broad transfer from such training to performance on untrained cognitive activities. Here we report the effects of two interactive computerized training programs developed for preschool children: one for music and one for visual art. After only 20 days of training, only children in the music group exhibited enhanced performance on a measure of verbal intelligence, with 90% of the sample showing this improvement. These improvements in verbal intelligence were positively correlated with changes in functional brain plasticity during an executive-function task. Our findings demonstrate that transfer of a high-level cognitive skill is possible in early childhood.

The External Performance Appraisal of China Energy Regulation: An Empirical Study Using a TOPSIS Method Based on Entropy Weight and Mahalanobis Distance

PubMed Central

Li, Dan-Dan; Zheng, Hong-Hao

2018-01-01

In China’s industrialization process, the effective regulation of energy and environment can promote the positive externality of energy consumption while reducing negative externality, which is an important means for realizing the sustainable development of an economic society. The study puts forward an improved technique for order preference by similarity to an ideal solution based on entropy weight and Mahalanobis distance (briefly referred as E-M-TOPSIS). The performance of the approach was verified to be satisfactory. By separately using traditional and improved TOPSIS methods, the study carried out the empirical appraisals on the external performance of China’s energy regulation during 1999~2015. The results show that the correlation between the performance indexes causes the significant difference between the appraisal results of E-M-TOPSIS and traditional TOPSIS. The E-M-TOPSIS takes the correlation between indexes into account and generally softens the closeness degree compared with traditional TOPSIS. Moreover, it makes the relative closeness degree fluctuate within a small-amplitude. The results conform to the practical condition of China’s energy regulation and therefore the E-M-TOPSIS is favorably applicable for the external performance appraisal of energy regulation. Additionally, the external economic performance and social responsibility performance (including environmental and energy safety performances) based on the E-M-TOPSIS exhibit significantly different fluctuation trends. The external economic performance dramatically fluctuates with a larger fluctuation amplitude, while the social responsibility performance exhibits a relatively stable interval fluctuation. This indicates that compared to the social responsibility performance, the fluctuation of external economic performance is more sensitive to energy regulation. PMID:29385781

Heterologous expression of Spathaspora passalidarum xylose reductase and xylitol dehydrogenase genes improved xylose fermentation ability of Aureobasidium pullulans.

PubMed

Guo, Jian; Huang, Siyao; Chen, Yefu; Guo, Xuewu; Xiao, Dongguang

2018-04-30

Aureobasidium pullulans is a yeast-like fungus that can ferment xylose to generate high-value-added products, such as pullulan, heavy oil, and melanin. The combinatorial expression of two xylose reductase (XR) genes and two xylitol dehydrogenase (XDH) genes from Spathaspora passalidarum and the heterologous expression of the Piromyces sp. xylose isomerase (XI) gene were induced in A. pullulans to increase the consumption capability of A. pullulans on xylose. The overexpression of XYL1.2 (encoding XR) and XYL2.2 (encoding XDH) was the most beneficial for xylose utilization, resulting in a 17.76% increase in consumed xylose compared with the parent strain, whereas the introduction of the Piromyces sp. XI pathway failed to enhance xylose utilization efficiency. Mutants with superior xylose fermentation performance exhibited increased intracellular reducing equivalents. The fermentation performance of all recombinant strains was not affected when glucose or sucrose was utilized as the carbon source. The strain with overexpression of XYL1.2 and XYL2.2 exhibited excellent fermentation performance with mimicked hydrolysate, and pullulan production increased by 97.72% compared with that of the parent strain. The present work indicates that the P4 mutant (using the XR/XDH pathway) with overexpressed XYL1.2 and XYL2.2 exhibited the best xylose fermentation performance. The P4 strain showed the highest intracellular reducing equivalents and XR and XDH activity, with consequently improved pullulan productivity and reduced melanin production. This valuable development in aerobic fermentation by the P4 strain may provide guidance for the biotransformation of xylose to high-value products by A. pullulans through genetic approach.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fu, Fang; Yao, Yuze; Wang, Haiyan

Rational and precise control of the structure and dimension of electrode materials is an efficient way to improve their electrochemical performance. In this work, solvothermal or co-precipitation method is used to synthesize lithium-rich layered oxide materials of Li1.2Mn0.56Co0.12Ni0.12O2 (LLO) with various morphologies and structures, including microspheres, microrods, nanoplates, and irregular nanoparticles. These materials exhibit strong structure- dependent electrochemical properties. The porous hierarchical structured LLO microrods exhibit the best performance, delivering a discharge capacity of 264.6 mAh g(-1) at 0.5 C with over 91% retention after 100 cycles. At a high rate of 5 C, a high discharge capacity of 173.6more » mAh g(-1) can be achieved. This work reveals the relationship between the morphologies and electrochemical properties of LLO cathode materials, and provides a feasible approach to fabricating robust and high-performance electrode materials for lithium-ion batteries.« less

Thermal oxidation synthesis hollow MoO{sub 3} microspheres and their applications in lithium storage and gas-sensing

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhao, Xinyu; School of Petrochemical Engineering, Shenyang University of Technology, Liaoyang 111003; Cao, Minhua, E-mail: caomh@bit.edu.cn

2013-06-01

Graphical abstract: MoO{sub 3} hollow microspheres were synthesized via a facile and template-free solvothermal route and subsequent heat treatment in air. The MoO{sub 3} hollow microspheres exhibit an improved lithium storage and gas-sensing performance. Highlights: ► Hollow MoO{sub 3} microspheres were synthesized by thermal oxidation of hollow MoO{sub 2}. ► The MoO{sub 3} hollow microspheres have a relatively high specific surface area. ► The MoO{sub 3} hollow microspheres exhibit improved lithium storage performance. ► The MoO{sub 3} hollow microspheres show good responses to ammonia gas. - Abstract: In this paper, MoO{sub 3} hollow microspheres were synthesized via a facile andmore » template-free solvothermal route and subsequent heat treatment in air. The MoO{sub 3} hollow microspheres have a relatively high specific surface area, and with such a feature, the as-synthesized MoO{sub 3} hollow microspheres have potential applications in Li-ion battery and gas-sensor. When tested as a Li-storage anode material, the MoO{sub 3} hollow microspheres show a higher discharge capacity of 1377.1 mA h g{sup −1} in the first discharge and a high reversible capacity of 780 mA h g{sup −1} after 100 cycles at a rate of 1 C. Furthermore, as a gas sensing material, the MoO{sub 3} hollow microspheres exhibit an improved sensitivity and short response/recovery time to trace levels of ammonia gas.« less

Electrochemical doping for lowering contact barriers in organic field effect transistors

PubMed Central

Schaur, Stefan; Stadler, Philipp; Meana-Esteban, Beatriz; Neugebauer, Helmut; Serdar Sariciftci, N.

2012-01-01

By electrochemically p-doping pentacene in the vicinity of the source-drain electrodes in organic field effect transistors the injection barrier for holes is decreased. The focus of this work is put on the influence of the p-doping process on the transistor performance. Cyclic voltammetry performed on a pentacene based transistor exhibits a reversible p-doping response. This doped state is evoked at the transistor injection electrodes. An improvement is observed when comparing transistor characteristics before and after the doping process apparent by an improved transistor on-current. This effect is reflected in the analysis of the contact resistances of the devices. PMID:23483101

A concentrated electrolyte for zinc hexacyanoferrate electrodes in aqueous rechargeable zinc-ion batteries

NASA Astrophysics Data System (ADS)

Kim, D.; Lee, C.; Jeong, S.

2018-01-01

In this study, a concentrated electrolyte was applied in an aqueous rechargeable zinc-ion battery system with a zinc hexacyanoferrate (ZnHCF) electrode to improve the electrochemical performance by changing the hydration number of the zinc ions. To optimize the active material, ZnHCF was synthesized using aqueous solutions of zinc nitrate with three different concentrations. The synthesized materials exhibited some differences in structure, crystallinity, and particle size, as observed by X-ray diffraction and scanning electron microscopy. Subsequently, these well-structured materials were applied in electrochemical tests. A more than two-fold improvement in the charge/discharge capacities was observed when the concentrated electrolyte was used instead of the dilute electrolyte. Additionally, the cycling performance observed in the concentrated electrolyte was superior to that in the dilute electrolyte. This improvement in the electrochemical performance may result from a decrease in the hydration number of the zinc ions in the concentrated electrolyte.

An insight into actual energy use and its drivers in high-performance buildings

DOE PAGES

Li, Cheng; Hong, Tianzhen; Yan, Da

2014-07-12

Using portfolio analysis and individual detailed case studies, we studied the energy performance and drivers of energy use in 51 high-performance office buildings in the U.S., Europe, China, and other parts of Asia. Portfolio analyses revealed that actual site energy use intensity (EUI) of the study buildings varied by a factor of as much as 11, indicating significant variation in real energy use in HPBs worldwide. Nearly half of the buildings did not meet the American Society of Heating, Refrigerating, and Air Conditioning Engineers (ASHRAE) Standard 90.1-2004 energy target, raising questions about whether a building’s certification as high performing accuratelymore » indicates that a building is energy efficient and suggesting that improvement in the design and operation of HPBs is needed to realize their energy-saving potential. We studied the influence of climate, building size, and building technologies on building energy performance and found that although all are important, none are decisive factors in building energy use. EUIs were widely scattered in all climate zones. There was a trend toward low energy use in small buildings, but the correlation was not absolute; some small HPBs exhibited high energy use, and some large HPBs exhibited low energy use. We were unable to identify a set of efficient technologies that correlated directly to low EUIs. In two case studies, we investigated the influence of occupant behavior as well as operation and maintenance on energy performance and found that both play significant roles in realizing energy savings. We conclude that no single factor determines the actual energy performance of HPBs, and adding multiple efficient technologies does not necessarily improve building energy performance; therefore, an integrated design approach that takes account of climate, technology, occupant behavior, and operations and maintenance practices should be implemented to maximize energy savings in HPBs. As a result, these findings are intended to help architects, engineers, operators, and policy makers improve the design and operation of HPBs.« less

Bio-lubricants derived from waste cooking oil with improved oxidation stability and low-temperature properties.

PubMed

Li, Weimin; Wang, Xiaobo

2015-01-01

Waste cooking oil (WCO) was chemically modified via epoxidation using H2O2 followed by transesterification with methanol and branched alcohols (isooctanol, isotridecanol and isooctadecanol) to produce bio-lubricants with improved oxidative stability and low temperature properties. Physicochemical properties of synthesized bio-lubricants such as pour point (PP), cloud point (CP), viscosity, viscosity index (VI), oxidative stability, and corrosion resistant property were determined according to standard methods. The synthesized bio-lubricants showed improved low temperature flow performances compared with WCO, which can be attributing to the introduction of branched chains in their molecular structures. What's more, the oxidation stability of the WCO showed more than 10 folds improvement due to the elimination of -C=C-bonds in the WCO molecule. Tribological performances of these bio-lubricants were also investigated using four-ball friction and wear tester. Experimental results showed that derivatives of WCO exhibited favorable physicochemical properties and tribological performances which making them good candidates in formulating eco-friendly lubricants.

Organic light emitting device having multiple separate emissive layers

DOEpatents

Forrest, Stephen R [Ann Arbor, MI

2012-03-27

An organic light emitting device having multiple separate emissive layers is provided. Each emissive layer may define an exciton formation region, allowing exciton formation to occur across the entire emissive region. By aligning the energy levels of each emissive layer with the adjacent emissive layers, exciton formation in each layer may be improved. Devices incorporating multiple emissive layers with multiple exciton formation regions may exhibit improved performance, including internal quantum efficiencies of up to 100%.

Polyoxometalate-modified TiO2 nanotube arrays photoanode materials for enhanced dye-sensitized solar cells

NASA Astrophysics Data System (ADS)

Liu, Ran; Sun, Zhixia; Zhang, Yuzhuo; Xu, Lin; Li, Na

2017-10-01

In this work, we prepared for the first time the TiO2 nanotube arrays (TNAs) photoanode with polyoxometalate(POMs)-modified TiO2 electron-transport layer for improving the performance of zinc phthalocyanine(ZnPc)-sensitized solar cells. The as-prepared POMs/TNAs/ZnPc composite photoanode exhibited higher photovoltaic performances than the TNAs/ZnPc photoanode, so that the power conversion efficiency of the solar cell device based on the POMs/TNAs/ZnPc photoanode displayed a notable improvement of 45%. These results indicated that the POMs play a key role in reducing charge recombination in phthalocyanine-sensitized solar cells, together with TiO2 nanotube arrays being helpful for electron transport. The mechanism of the performance improvement was demonstrated by the measurements of electrochemical impedance spectra and open-circuit voltage decay curves. Although the resulting performance is still below that of the state-of-the-art dye-sensitized solar cells, this study presents a new insight into improving the power conversion efficiency of phthalocyanine-sensitized solar cells via polyoxometalate-modified TiO2 nanotube arrays photoanode.

An Electrochemical Processing Strategy for Improving Tribological Performance of Aisi 316 Stainless Steel Under Grease Lubrication

NASA Astrophysics Data System (ADS)

Zou, Jiaojuan; Li, Maolin; Lin, Naiming; Zhang, Xiangyu; Qin, Lin; Tang, Bin

2014-12-01

In order to improve the tribological performance of AISI 316 stainless steel (316 SS) under grease lubrication, electrochemical processing was conducted on it to obtain a rough (surface texturing-like) surface by making use of the high sensitivity of austenitic stainless steel to pitting corrosion in Cl--rich environment. Numerous corrosion pits or micro-ditches acted as micro-reservoirs on the obtained surface. While the grease could offer consistent lubrication, and then improve the tribological performance of 316 SS. Tribological behaviors of raw 316 SS and the treated sample were measured using a reciprocating type tribometer sliding against GCr15 steel counterpart under dry and grease lubrication conditions. The results showed that the mass losses of the two samples were in the same order of magnitude, and the raw sample exhibited lower friction coefficient in dry sliding. When the tests were conducted under grease lubrication condition, the friction coefficients and mass losses of the treated sample were far lower than those of the raw 316 SS. The tribological performance of 316 SS under grease lubrication was drastically improved after electrochemical processing.

Relative health performance in BRICS over the past 20 years: the winners and losers

PubMed Central

Petrie, Dennis

2014-01-01

Abstract Objective To determine whether the health performance of Brazil, the Russian Federation, India, China and South Africa – the countries known as BRICS – has kept in step with their economic development. Methods Reductions in age- and sex-specific mortality seen in each BRICS country between 1990 and 2011 were measured. These results were compared with those of the best-performing countries in the world and the best-performing countries with similar income levels. We estimated each country’s progress in reducing mortality and compared changes in that country’s mortality rates against other countries with similar mean incomes to examine changes in avoidable mortality. Findings The relative health performance of the five study countries differed markedly over the study period. Brazil demonstrated fairly even improvement in relative health performance across the different age and sex subgroups that we assessed. India’s improvement was more modest and more varied across the subgroups. South Africa and the Russian Federation exhibited large declines in health performance as well as large sex-specific inequalities in health. Although China’s levels of avoidable mortality decreased in absolute terms, the level of improvement appeared low in the context of China’s economic growth. Conclusion When evaluating a country’s health performance in terms of avoidable mortality, it is useful to compare that performance against the performance of other countries. Such comparison allows any country-specific improvements to be distinguished from general global improvements. PMID:24940013

Enhanced mood and psychomotor performance by a caffeine-containing energy capsule in fatigued individuals.

PubMed

Childs, Emma; de Wit, Harriet

2008-02-01

Caffeine produces mild psychostimulant effects that may be particularly evident in individuals whose mood or performance is impaired by sleep restriction or caffeine withdrawal. Caffeinated energy drinks have been shown to improve energy and cognition but expectancy effects cannot be ruled out in these studies. Very few studies have examined the effects of caffeine-containing energy capsules upon behavioral and subjective measures. This study compared the effects of a caffeine-containing (200 mg) supplement (CAF) or placebo in capsule form after prolonged wakefulness, in participants who varied in their level of habitual caffeine use. Thirty-five healthy volunteers (16 male, 19 female) participated in two experimental sessions in which they remained awake between 5 p.m. and 5 a.m. At 3:30 a.m. they consumed CAF or placebo in random order under double-blind conditions. Participants completed subjective effects questionnaires and performed computerized attention tasks before and after consuming capsules. Heart rate and blood pressure were monitored at regular intervals. Compared to measures at 5 p.m., participants reported more tiredness and mood disturbance at 3 a.m., and exhibited longer reaction times and more attentional lapses. Heavier caffeine consumers exhibited the greatest decreases in Profile of Mood States (POMS) Vigor. CAF produced stimulant-like effects and significantly improved mood and reaction times upon the tasks. These effects did not vary with level of habitual caffeine consumption. These findings indicate that consumption of a caffeine-containing food supplement improves subjective state and cognitive performance in fatigued individuals that is likely a result of its caffeine content. 2008 APA

Long-range correlation properties in timing of skilled piano performance: the influence of auditory feedback and deep brain stimulation.

PubMed

Herrojo Ruiz, María; Hong, Sang Bin; Hennig, Holger; Altenmüller, Eckart; Kühn, Andrea A

2014-01-01

Unintentional timing deviations during musical performance can be conceived of as timing errors. However, recent research on humanizing computer-generated music has demonstrated that timing fluctuations that exhibit long-range temporal correlations (LRTC) are preferred by human listeners. This preference can be accounted for by the ubiquitous presence of LRTC in human tapping and rhythmic performances. Interestingly, the manifestation of LRTC in tapping behavior seems to be driven in a subject-specific manner by the LRTC properties of resting-state background cortical oscillatory activity. In this framework, the current study aimed to investigate whether propagation of timing deviations during the skilled, memorized piano performance (without metronome) of 17 professional pianists exhibits LRTC and whether the structure of the correlations is influenced by the presence or absence of auditory feedback. As an additional goal, we set out to investigate the influence of altering the dynamics along the cortico-basal-ganglia-thalamo-cortical network via deep brain stimulation (DBS) on the LRTC properties of musical performance. Specifically, we investigated temporal deviations during the skilled piano performance of a non-professional pianist who was treated with subthalamic-deep brain stimulation (STN-DBS) due to severe Parkinson's disease, with predominant tremor affecting his right upper extremity. In the tremor-affected right hand, the timing fluctuations of the performance exhibited random correlations with DBS OFF. By contrast, DBS restored long-range dependency in the temporal fluctuations, corresponding with the general motor improvement on DBS. Overall, the present investigations demonstrate the presence of LRTC in skilled piano performances, indicating that unintentional temporal deviations are correlated over a wide range of time scales. This phenomenon is stable after removal of the auditory feedback, but is altered by STN-DBS, which suggests that cortico-basal ganglia-thalamocortical circuits play a role in the modulation of the serial correlations of timing fluctuations exhibited in skilled musical performance.

Recent Development of TlBr Gamma-Ray Detectors

NASA Astrophysics Data System (ADS)

Hitomi, Keitaro; Tada, Tsutomu; Kim, Seong-Yun; Wu, Yan; Tanaka, Tomonobu; Shoji, Tadayoshi; Yamazaki, Hiromichi; Ishii, Keizo

2011-08-01

Planar detectors, strip detectors, and double-sided strip detectors were fabricated from TlBr crystals grown by the traveling molten zone method using zone-purified material. The detector performance including the leakage current, energy resolutions, and timing performance were evaluated in order to assess the capability of the detectors for PET and SPECT applications. The TlBr detectors exhibited excellent spectroscopic performance at room temperature. An energy resolution of 3.4% FWHM at 511 keV was obtained from a TlBr planar detector 1 mm thick. A TlBr strip detector 1 mm thick with four anode strip electrodes exhibited almost uniform detector performance over the strips with the average energy resolution of 4.4% FWHM at 511 keV. A TlBr double-sided strip detector exhibited an energy resolution of 6.3% FWHM for 122 keV gamma-rays. Coincidence timing spectra between a TlBr planar detector and a BaF2 scintillation detector were recorded at room temperature. Timing resolutions of 14 ns and 24 ns were obtained from TlBr detectors 0.5 mm and 1 mm thick, respectively. By cooling the detector to 0° C, an improved timing resolution of 12 ns was obtained from a TlBr detector 1 mm thick.

Problem-Solving Phase Transitions During Team Collaboration.

PubMed

Wiltshire, Travis J; Butner, Jonathan E; Fiore, Stephen M

2018-01-01

Multiple theories of problem-solving hypothesize that there are distinct qualitative phases exhibited during effective problem-solving. However, limited research has attempted to identify when transitions between phases occur. We integrate theory on collaborative problem-solving (CPS) with dynamical systems theory suggesting that when a system is undergoing a phase transition it should exhibit a peak in entropy and that entropy levels should also relate to team performance. Communications from 40 teams that collaborated on a complex problem were coded for occurrence of problem-solving processes. We applied a sliding window entropy technique to each team's communications and specified criteria for (a) identifying data points that qualify as peaks and (b) determining which peaks were robust. We used multilevel modeling, and provide a qualitative example, to evaluate whether phases exhibit distinct distributions of communication processes. We also tested whether there was a relationship between entropy values at transition points and CPS performance. We found that a proportion of entropy peaks was robust and that the relative occurrence of communication codes varied significantly across phases. Peaks in entropy thus corresponded to qualitative shifts in teams' CPS communications, providing empirical evidence that teams exhibit phase transitions during CPS. Also, lower average levels of entropy at the phase transition points predicted better CPS performance. We specify future directions to improve understanding of phase transitions during CPS, and collaborative cognition, more broadly. Copyright © 2017 Cognitive Science Society, Inc.

Evaluative and Behavioral Correlates to Intrarehearsal Achievement in High School Bands

ERIC Educational Resources Information Center

Montemayor, Mark

2014-01-01

The purpose of this study was to investigate relationships of teaching effectiveness, ensemble performance quality, and selected rehearsal procedures to various measures of intrarehearsal achievement (i.e., musical improvement exhibited by an ensemble during the course of a single rehearsal). Twenty-nine high school bands were observed in two…

Paraphrasing and Prediction with Self-Explanation as Generative Strategies for Learning Science Principles in a Simulation

ERIC Educational Resources Information Center

Morrison, Jennifer R.; Bol, Linda; Ross, Steven M.; Watson, Ginger S.

2015-01-01

This study examined the incorporation of generative strategies for the guided discovery of physics principles in a simulation. Participants who either paraphrased or predicted and self-explained guided discovery assignments exhibited improved performance on an achievement test as compared to a control group. Calibration accuracy (the…

Further Analysis of the Effects of Positive Reinforcement on Working Memory in Children with Autism

ERIC Educational Resources Information Center

Baltruschat, Lisa; Hasselhorn, Marcus; Tarbox, Jonathan; Dixon, Dennis R.; Najdowski, Adel C.; Mullins, Ryan D.; Gould, Evelyn R.

2011-01-01

Individuals with autism spectrum disorders (ASD) often exhibit impaired executive function (EF) performance, including difficulty with working memory (WM), in particular. While research has documented the existence of these deficits, surprisingly little research exists that evaluates potential treatment strategies for improving EF or WM. One…

Superior capacitive performance of hydrochar-based porous carbons in aqueous electrolytes.

PubMed

Fuertes, Antonio B; Sevilla, Marta

2015-03-01

Biomass-based highly porous carbons with excellent performances in aqueous electrolyte-based supercapacitors have been developed. The synthesis of these materials is based on the chemical activation of biomass-based hydrochar. The addition of melamine to the activation mixture leads to porous carbons with a porosity consisting of micropores/small mesopores. Furthermore, melamine promotes the introduction of nitrogen heteroatoms in the carbon framework, along with abundant oxygen functionalities, to improve the wettability. The materials produced in the presence or absence of melamine exhibit high specific capacitances in aqueous electrolytes (>270 F g(-1) in H2 SO4 and >190 F g(-1) in Li2SO4). Additionally, the mesopores present in the melamine-based micro-/mesoporous carbons notably improve the ion-transport kinetics, especially in Li2SO4. Furthermore, in Li2SO4, they remain stable up to a cell voltage of 1.6 V; thus exhibiting superior energy and power characteristics than those in H2 SO4. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Significance of the Cytological Signs of Human Papillomavirus Infection in Anal Pap Smears of Human Immunodeficiency Virus-Infected Japanese Men Who Have Sex with Men

PubMed

Okayama, Kaori; Okodo, Mitsuaki; Kitamura, Hiroshi; Itoda, Ichiro

2017-11-26

Purpose: The incidence of invasive anal cancer (IAC) has been increasing among human immunodeficiency virus (HIV)-positive men who have sex with men (MSM). Although cytological diagnosis is the modality of choice for screening cases of IAC, it is associated with lower sensitivity and specificity. Therefore, the present study aimed to evaluate new cytological signs of human papillomavirus (HPV) infection that may contribute to improving anal cytology. Methods: Anal cytology and HPV testing were performed using SurePath liquid-based cytology on samples obtained from 37 HIV-positive Japanese MSM. Subsequently, a histological biopsy based on high-resolution anoscopy was performed in MSM with abnormal cytological findings indicative of atypical squamous cells of undetermined significance (ASC-US) +. Also, anal Papanicolaou (Pap) smears were performed to determine cellularity, presence of dysplastic squamous cells, and other cytological signs of HPV infection. Results: Of the 37 MSM who underwent anal cytology, six tested negative for intraepithelial lesion or malignancy, three cases exhibited ASC-US, 17 exhibited low-grade squamous intraepithelial lesion (LSIL), nine exhibited high-grade squamous intraepithelial lesion (HSIL), and two remained undiagnosed. The anal Pap smears of 28 (96.6%) of the 29 MSM with abnormal cytological findings of ASC-US+ exhibited anal intraepithelial neoplasia (AIN), as revealed by histological biopsy. The median value (minimum–maximum) of the cellularity of anal Pap smears was 12 (0–70.5) nsc/hpf. In 26 MSM with LSIL and HSIL, the median dysplastic squamous cells count was 14 (2–152) dsc/smear and the cytological sign of HPV infection was 11 (2–71) hpv/smear. Of all anal Pap smears that revealed ASC-US+, 96.6% exhibited cytological signs of HPV infection. Compression-positive binucleated cells were the most prevalent among all cytological signs of HPV infection. Conclusion: For anal cytology, instead of considering a small number of dysplastic squamous cells, screening based on cytological signs of HPV infection may be beneficial for improving the diagnosis of AIN. Creative Commons Attribution License

Retrospective analysis of the treatment of melasma lesions exhibiting increased vascularity with the 595-nm pulsed dye laser combined with the 1927-nm fractional low-powered diode laser.

PubMed

Geddes, Elizabeth R C; Stout, Ashlyn B; Friedman, Paul M

2017-01-01

Melasma presents a significant challenge to laser surgeons. Aggressive treatments often result in rebound melasma or post-inflammatory pigmentary alteration. Recent reports suggest melasma pathogenesis may have a vascular component. Spectrocolorimetry can detect subtle or sub-clinical telangiectatic erythema within melasma lesions. For certain patients identified by spectrocolorimetry, effective melasma treatment may include vascular-targeted therapy together with pigment-specific treatment modalities. Such combined therapies may reduce the likelihood of melasma recurrence. To evaluate the efficacy of treating melasma lesions exhibiting subtle or sub-clinical telangiectatic erythema with the 595-nm pulsed dye laser (PDL) combined with the 1927-nm fractional low-powered diode laser (FDL). A retrospective review was performed over a 2-year period as follows. Evaluated patients (n = 11) include 10 women and 1 man, average age of 38.7 years, and Fitzpatrick skin types II-IV. Each patient exhibited melasma lesions with subtle or sub-clinical telangiectatic erythema identified by spectrocolorimetry. Each underwent a series of treatments (average of four) at approximate 4-6 week intervals of the PDL followed by the FDL. Treatments were performed same-day, sequentially, with 10-15 minute interim time allowance for skin cooling. The following PDL parameters were utilized: 10 mm spot, 10-20 ms pulse duration, 7.5-8.5 J/cm 2 fluence, 30/30 DCD. Eight passes with the FDL (Clear + Brilliant ® Permea™, Solta Medical, Hayward, CA) were then performed utilizing a "low" treatment level. Clinical endpoint was mild erythema and edema. Patients were encouraged to practice strict photoprotection and apply topical skin lightening agents, but compliance was not measured. An independent physician evaluated photographs taken at baseline and at follow-up after last treatment session (average follow-up of 96 days). A quartile improvement score was used to grade the improvement of melasma and underlying telangiectatic erythema. At time of data analysis, patient satisfaction was self-graded on a three-point scale (0 = not satisfied, 1 = satisfied, 2 = very satisfied). Six out of eleven patients (54%) demonstrated greater than 50% improvement in melasma presentation. Improvement in melasma generally paralleled improvement in erythema. No rebound melasma, post-inflammatory changes, or adverse events were noted. Patient satisfaction responses averaged 1.6, with all (10) patients reporting 1 "satisfied" or 2 "very satisfied." Melasma lesions exhibiting subtle or sub-clinical telangiectatic erythema may be improved by combined vascular-targeted laser therapy together with fractional low-powered diode laser therapy. A parallel improvement in telangiectatic erythema suggests a relationship between the underlying vasculature and hyperpigmentation. There is a low risk of adverse effects and overall patient satisfaction is high. Follow-up to optimize treatment parameters and determine long-term durability is needed. Lasers Surg. Med. 49:20-26, 2017. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

Mechanical performance of porous concrete pavement containing nano black rice husk ash

NASA Astrophysics Data System (ADS)

Ibrahim, M. Y. Mohd; Ramadhansyah, P. J.; Rosli, H. Mohd; Ibrahim, M. H. Wan

2018-01-01

This paper presents an experimental research on the performance of nano black rice husk ash on the porous concrete pavement properties. The performance of the porous concrete pavement mixtures was investigated based on their compressive strength, flexural strength, and splitting tensile strength. The results indicated that using nano material from black rice husk ash improved the mechanical properties of porous concrete pavement. In addition, the result of compressive, flexural, and splitting tensile strength was increased with increasing in curing age. Finally, porous concrete pavement with 10% replacement levels exhibited an excellent performance with good strength compared to others.

Apollo oxygen tank stratification analysis, volume 2

NASA Technical Reports Server (NTRS)

Barton, J. E.; Patterson, H. W.

1972-01-01

An analysis of flight performance of the Apollo 15 cryogenic oxygen tanks was conducted with the variable grid stratification math model developed earlier in the program. Flight conditions investigated were the CMP-EVA and one passive thermal control period which exhibited heater temperature characteristics not previously observed. Heater temperatures for these periods were simulated with the math model using flight acceleration data. Simulation results (heater temperature and tank pressure) compared favorably with the Apollo 15 flight data, and it was concluded that tank performance was nominal. Math model modifications were also made to improve the simulation accuracy. The modifications included the addition of the effects of the tank wall thermal mass and an improved system flow distribution model. The modifications improved the accuracy of simulated pressure response based on comparisons with flight data.

The use of synthetic and natural vitamin D sources in pig diets to improve meat quality and vitamin D content.

PubMed

Duffy, Sarah K; Kelly, Alan K; Rajauria, Gaurav; Jakobsen, Jette; Clarke, Louise C; Monahan, Frank J; Dowling, Kirsten G; Hull, George; Galvin, Karen; Cashman, Kevin D; Hayes, Aoife; O'Doherty, John V

2018-09-01

This study investigated the effects of synthetic and natural sources of vitamin D biofortification in pig diets on pork vitamin D activity and pork quality. One hundred and twenty pigs (60 male, 60 female) were assigned to one of four dietary treatments for a 55 d feeding period. The dietary treatments were (1)50 μg vitamin D₃/kg of feed; (2)50 μg of 25-hydroxvitamin D₃/kg of feed (25-OH-D₃); (3)50 μg vitamin D₂/kg of feed; (4)50 μg vitamin D₂-enriched mushrooms/kg of feed (Mushroom D₂). The pigs offered the 25-OH-D₃ diet exhibited the highest (P < 0.001) serum total 25-hydroxyvitamin D concentration and subsequently exhibited the highest (P < 0.05) Longissimus thoracis (LT) total vitamin D activity. Mushroom D 2 and 25-OH-D 3 supplementation increased pork antioxidant status. The vitamin D₂-enriched mushrooms improved (P < 0.05) pig performance, carcass weight and LT colour. In conclusion, 25-OH-D₃ is the most successful source for increasing pork vitamin D activity, while Mushroom D 2 may be a new avenue to improve animal performance and pork quality. Copyright © 2018 Elsevier Ltd. All rights reserved.

Aircrew Performance Cutting-Edge Tech: Emerging Human Performance Enhancement Technology Vision in Support of Operational Military Aviation Strategy

DTIC Science & Technology

2002-04-01

Origin and History, (RK, PRK , LASIK ) Refractive surgery was first considered as early as 1898 by a Dutch professor and was unsuccessfully attempted in...Keratomileusis ( LASIK ) LASIK offers the greatest potential for improving aviator vision and is the latest PRK -similar procedure. First, a flap of...showed that after LASIK , subjects did not exhibit a refractive shift of clinical significance.39 Therefore LASIK and PRK , recipients had no significant

Improving Biopharmaceutical Properties of Vinpocetine Through Cocrystallization.

PubMed

Golob, Samuel; Perry, Miranda; Lusi, Matteo; Chierotti, Michele R; Grabnar, Iztok; Lassiani, Lucia; Voinovich, Dario; Zaworotko, Michael J

2016-12-01

Vinpocetine is a poorly water soluble weakly basic drug (pK a  = 7.1) used for the treatment of several cerebrovascular and cognitive disorders. Because existing formulations exhibit poor bioavailability and scarce absorption, a dosage form with improved pharmacokinetic properties is highly desirable. Cocrystallization represents a promising approach to generate diverse novel crystal forms and to improve the aqueous solubility and in turn the oral bioavailability. In this article, a novel ionic cocrystal of vinpocetine is described, using boric acid as a coformer, and fully characterized (by means of differential scanning calorimetry, solid-state nuclear magnetic resonance, powder and single-crystal X-ray diffraction, and powder dissolution test). Pharmacokinetic performance was also tested in a human pilot study. This pharmaceutical ionic cocrystal exhibits superior solubilization kinetics and modulates important pharmacokinetic values such as maximum concentration in plasma (C max ), time to maximum concentration (t max ), and area under the plasma concentration-time curve (AUC) of the poorly soluble vinpocetine and it therefore offers an innovative approach to improve its bioavailability. Copyright © 2016 American Pharmacists Association®. Published by Elsevier Inc. All rights reserved.

Ascorbic acid enhances oxidative stress tolerance and biological control efficacy of Pichia caribbica against postharvest blue mold decay of apples.

PubMed

Li, Chaolan; Zhang, Hongyin; Yang, Qiya; Komla, Mahunu Gustav; Zhang, Xiaoyun; Zhu, Shuyun

2014-07-30

The effect of ascorbic acid (VC) on improving oxidative stress tolerance of Pichia caribbica and biocontrol efficacy against blue mold caused by Penicillium expansum on apples was investigated. P. caribbica showed susceptibility to the oxidative stress in vitro test, and 250 μg/mL VC treatment improved its oxidative stress tolerance. The higher viability exhibited by VC-treated yeast was associated with a lower intracellular ROS level. The activities of antioxidant enzymes of P. caribbica were improved by VC treatment, including catalase (CAT), superoxide dismutase (SOD), and glutathione peroxidase (GPX). Additionally, VC-treated yeast exhibited greater biocontrol activity against P. expansum and faster growth when stored at 25 and 4 °C, respectively, compared to the performance of the non-VC-treated yeast. In response to the VC treatment under oxidative stress, several differentially expressed proteins were identified in P. caribbica, and most of the poteins were confirmed to be related to basic metabolism. Therefore, the application of ascorbic acid is a useful approach to improve oxidative stress tolerance of P. caribbica and its biocontrol efficacy on apples.

Maternal choline supplementation improves spatial learning and adult hippocampal neurogenesis in the Ts65Dn mouse model of Down syndrome.

PubMed

Velazquez, Ramon; Ash, Jessica A; Powers, Brian E; Kelley, Christy M; Strawderman, Myla; Luscher, Zoe I; Ginsberg, Stephen D; Mufson, Elliott J; Strupp, Barbara J

2013-10-01

In addition to intellectual disability, individuals with Down syndrome (DS) exhibit dementia by the third or fourth decade of life, due to the early onset of neuropathological changes typical of Alzheimer's disease (AD). Deficient ontogenetic neurogenesis contributes to the brain hypoplasia and hypocellularity evident in fetuses and children with DS. A murine model of DS and AD (the Ts65Dn mouse) exhibits key features of these disorders, notably deficient ontogenetic neurogenesis, degeneration of basal forebrain cholinergic neurons (BFCNs), and cognitive deficits. Adult hippocampal (HP) neurogenesis is also deficient in Ts65Dn mice and may contribute to the observed cognitive dysfunction. Herein, we demonstrate that supplementing the maternal diet with additional choline (approximately 4.5 times the amount in normal rodent chow) dramatically improved the performance of the adult trisomic offspring in a radial arm water maze task. Ts65Dn offspring of choline-supplemented dams performed significantly better than unsupplemented Ts65Dn mice. Furthermore, adult hippocampal neurogenesis was partially normalized in the maternal choline supplemented (MCS) trisomic offspring relative to their unsupplemented counterparts. A significant correlation was observed between adult hippocampal neurogenesis and performance in the water maze, suggesting that the increased neurogenesis seen in the supplemented trisomic mice contributed functionally to their improved spatial cognition. These findings suggest that supplementing the maternal diet with additional choline has significant translational potential for DS. Copyright © 2013 Elsevier Inc. All rights reserved.

Mo-doped SnO2 mesoporous hollow structured spheres as anode materials for high-performance lithium ion batteries

NASA Astrophysics Data System (ADS)

Wang, Xuekun; Li, Zhaoqiang; Zhang, Zhiwei; Li, Qun; Guo, Enyan; Wang, Chengxiang; Yin, Longwei

2015-02-01

We designed a facile infiltration route to synthesize mesoporous hollow structured Mo doped SnO2 using silica spheres as templates. It is observed that Mo is uniformly incorporated into SnO2 lattice in the form of Mo6+. The as-prepared mesoporous Mo-doped SnO2 LIBs anodes exhibit a significantly improved electrochemical performance with good cycling stability, high specific capacity and high rate capability. The mesoporous hollow Mo-doped SnO2 sample with 14 at% Mo doping content displays a specific capacity of 801 mA h g-1 after 60 cycles at a current density of 100 mA g-1, about 1.66 times higher than that of the pure SnO2 hollow sample. In addition, even if the current density is as high as 1600 mA g-1 after 60 cycles, it could still retain a stable specific capacity of 530 mA h g-1, exhibiting an extraordinary rate capability. The greatly improved electrochemical performance of the Mo-doped mesoporous hollow SnO2 sample could be attributed to the following factors. The large surface area and hollow structure can significantly enhance structural integrity by acting as mechanical buffer, effectively alleviating the volume changes generated during the lithiation/delithiation process. The incorporation of Mo into the lattice of SnO2 improves charge transfer kinetics and results in a faster Li+ diffusion rate during the charge-discharge process.

Maternal choline supplementation improves spatial learning and adult hippocampal neurogenesis in the Ts65Dn mouse model of Down syndrome

PubMed Central

Velazquez, Ramon; Ash, Jessica A.; Powers, Brian E.; Kelley, Christy M.; Strawderman, Myla; Luscher, Zoe I.; Ginsberg, Stephen D.; Mufson, Elliott J.; Strupp, Barbara J.

2014-01-01

In addition to intellectual disability, individuals with Down syndrome (DS) exhibit dementia by the third or fourth decade of life, due to the early onset of neuropathological changes typical of Alzheimer’s disease (AD). Deficient ontogenetic neurogenesis contributes to the brain hypoplasia and hypocellularity evident in fetuses and children with DS. A murine model of DS and AD (the Ts65Dn mouse) exhibits key features of these disorders, notably deficient ontogenetic neurogenesis, degeneration of basal forebrain cholinergic neurons (BFCNs), and cognitive deficits. Adult hippocampal (HP) neurogenesis is also deficient in Ts65Dn mice and may contribute to the observed cognitive dysfunction. Herein, we demonstrate that supplementing the maternal diet with additional choline (approximately 4.5 times the amount in normal rodent chow) dramatically improved the performance of the adult trisomic offspring in a radial arm water maze task. Ts65Dn offspring of choline-supplemented dams performed significantly better than unsupplemented Ts65Dn mice. Furthermore, adult hippocampal neurogenesis was partially normalized in the maternal choline supplemented (MCS) trisomic offspring relative to their unsupplemented counterparts. A significant correlation was observed between adult hippocampal neurogenesis and performance in the water maze, suggesting that the increased neurogenesis seen in the supplemented trisomic mice contributed functionally to their improved spatial cognition. These findings suggest that supplementing the maternal diet with additional choline has significant translational potential for DS. PMID:23643842

Training to improve manual control in 7-8 and 10-12 year old children: Training eliminates performance differences between ages.

PubMed

Snapp-Childs, Winona; Fath, Aaron J; Watson, Carol A; Flatters, Ian; Mon-Williams, Mark; Bingham, Geoffrey P

2015-10-01

Many children have difficulty producing movements well enough to improve in perceptuo-motor learning. We have developed a training method that supports active movement generation to allow improvement in a 3D tracing task requiring good compliance control. We previously tested 7-8 year old children who exhibited poor performance and performance differences before training. After training, performance was significantly improved and performance differences were eliminated. According to the Dynamic Systems Theory of development, appropriate support can enable younger children to acquire the ability to perform like older children. In the present study, we compared 7-8 and 10-12 year old school children and predicted that younger children would show reduced performance that was nonetheless amenable to training. Indeed, the pre-training performance of the 7-8 year olds was worse than that of the 10-12 year olds, but post-training performance was equally good for both groups. This was similar to previous results found using this training method for children with DCD and age-matched typically developing children. We also found in a previous study of 7-8 year old school children that training in the 3D tracing task transferred to a 2D drawing task. We now found similar transfer for the 10-12 year olds. Copyright © 2015 Elsevier B.V. All rights reserved.

Improving proprioceptive deficits after stroke through robot-assisted training of the upper limb: a pilot case report study.

PubMed

Colombo, R; Sterpi, I; Mazzone, A; Delconte, C; Pisano, F

2016-01-01

The purpose of this study was to determine whether a conventional robot-assisted therapy of the upper limb was able to improve proprioception and motor recovery of an individual after stroke who exhibited proprioceptive deficits. After robotic sensorimotor training, significant changes were observed in kinematic performance variables. Two quantitative parameters evaluating position sense improved after training. Range of motion during shoulder and wrist flexion improved, but only wrist flexion remained improved at 3-month follow-up. These preliminary results suggest that intensive robot-aided rehabilitation may play an important role in the recovery of sensory function. However, further studies are required to confirm these data.

A green synthesis of a layered titanate, potassium lithium titanate; lower temperature solid-state reaction and improved materials performance

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ogawa, Makoto, E-mail: waseda.ogawa@gmail.com; Department of Earth Sciences, Waseda University, 1-6-1 Nishiwaseda, Shinjuku-ku, Tokyo 169-8050; Morita, Masashi, E-mail: m-masashi@y.akane.waseda.jp

2013-10-15

A layered titanate, potassium lithium titanate, with the size range from 0.1 to 30 µm was prepared to show the effects of the particle size on the materials performance. The potassium lithium titanate was prepared by solid-state reaction as reported previously, where the reaction temperature was varied. The reported temperature for the titanate preparation was higher than 800 °C, though 600 °C is good enough to obtain single-phase potassium lithium titanate. The lower temperature synthesis is cost effective and the product exhibit better performance as photocatalysts due to surface reactivity. - Graphical abstract: Finite particle of a layered titanate, potassiummore » lithium titanate, was prepared by solid-state reaction at lower temperature to show modified materials performance. Display Omitted - Highlights: • Potassium lithium titanate was prepared by solid-state reaction. • Lower temperature reaction resulted in smaller sized particles of titanate. • 600 °C was good enough to obtain single phased potassium lithium titanate. • The product exhibited better performance as photocatalyst.« less

Beneficial Properties of Probiotics

PubMed Central

Shi, Lye Huey; Balakrishnan, Kunasundari; Thiagarajah, Kokila; Mohd Ismail, Nor Ismaliza; Yin, Ooi Shao

2016-01-01

Probiotics are live microorganisms that can be found in fermented foods and cultured milk, and are widely used for the preparation of infant food. They are well-known as “health friendly bacteria”, which exhibit various health beneficial properties such as prevention of bowel diseases, improving the immune system, for lactose intolerance and intestinal microbial balance, exhibiting antihypercholesterolemic and antihypertensive effects, alleviation of postmenopausal disorders, and reducing traveller’s diarrhoea. Recent studies have also been focused on their uses in treating skin and oral diseases. In addition to that, modulation of the gut-brain by probiotics has been suggested as a novel therapeutic solution for anxiety and depression. Thus, this review discusses on the current probiotics-based products in Malaysia, criteria for selection of probiotics, and evidences obtained from past studies on how probiotics have been used in preventing intestinal disorders via improving the immune system, acting as an antihypercholesterolemic factor, improving oral and dermal health, and performing as anti-anxiety and anti-depressive agents. PMID:27688852

Reducing numerical diffusion for incompressible flow calculations

NASA Technical Reports Server (NTRS)

Claus, R. W.; Neely, G. M.; Syed, S. A.

1984-01-01

A number of approaches for improving the accuracy of incompressible, steady-state flow calculations are examined. Two improved differencing schemes, Quadratic Upstream Interpolation for Convective Kinematics (QUICK) and Skew-Upwind Differencing (SUD), are applied to the convective terms in the Navier-Stokes equations and compared with results obtained using hybrid differencing. In a number of test calculations, it is illustrated that no single scheme exhibits superior performance for all flow situations. However, both SUD and QUICK are shown to be generally more accurate than hybrid differencing.

Performing the unexplainable: Implicit task performance reveals individually reliable sequence learning without explicit knowledge

PubMed Central

Sanchez, Daniel J.; Gobel, Eric W.; Reber, Paul J.

2015-01-01

Memory-impaired patients express intact implicit perceptual–motor sequence learning, but it has been difficult to obtain a similarly clear dissociation in healthy participants. When explicit memory is intact, participants acquire some explicit knowledge and performance improvements from implicit learning may be subtle. Therefore, it is difficult to determine whether performance exceeds what could be expected on the basis of the concomitant explicit knowledge. Using a challenging new sequence-learning task, robust implicit learning was found in healthy participants with virtually no associated explicit knowledge. Participants trained on a repeating sequence that was selected randomly from a set of five. On a performance test of all five sequences, performance was best on the trained sequence, and two-thirds of the participants exhibited individually reliable improvement (by chi-square analysis). Participants could not reliably indicate which sequence had been trained by either recognition or recall. Only by expressing their knowledge via performance were participants able to indicate which sequence they had learned. PMID:21169570

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gupta, Shashaank; Belianinov, Alex; Okatan, Mahmut B

(001)pc textured K0.5Na0.5NbO3 (KNN) ceramic was found to exhibit a 65% improvement in the longitudinal piezoelectric response as compared to its random counterpart. Piezoresponse force microscopy study revealed the existence of larger 180 and non-180 domains for textured ceramic as compared to that of the random ceramic. Improvement in piezoresponse by the development of (001)pc texture is discussed in terms of the crystallographic nature of KNN and domain morphology. A comparative analysis performed with a rhombohedral composition suggested that the improvement in longitudinal piezoresponse of polycrystalline ceramics by the development of (001)pc texture is limited by the crystal structure.

Auditory and language development in Mandarin-speaking children after cochlear implantation.

PubMed

Lu, Xing; Qin, Zhaobing

2018-04-01

To evaluate early auditory performance, speech perception and language skills in Mandarin-speaking prelingual deaf children in the first two years after they received a cochlear implant (CI) and analyse the effects of possible associated factors. The Infant-Toddler Meaningful Auditory Integration Scale (ITMAIS)/Meaningful Auditory Integration Scale (MAIS), Mandarin Early Speech Perception (MESP) test and Putonghua Communicative Development Inventory (PCDI) were used to assess auditory and language outcomes in 132 Mandarin-speaking children pre- and post-implantation. Children with CIs exhibited an ITMAIS/MAIS and PCDI developmental trajectory similar to that of children with normal hearing. The increased number of participants who achieved MESP categories 1-6 at each test interval showed a significant improvement in speech perception by paediatric CI recipients. Age at implantation and socioeconomic status were consistently associated with both auditory and language outcomes in the first two years post-implantation. Mandarin-speaking children with CIs exhibit significant improvements in early auditory and language development. Though these improvements followed the normative developmental trajectories, they still exhibited a gap compared with normative values. Earlier implantation and higher socioeconomic status are consistent predictors of greater auditory and language skills in the early stage. Copyright © 2018 Elsevier B.V. All rights reserved.

Middle school students' learning of the impact of methamphetamine abuse on the brain through serious game play

NASA Astrophysics Data System (ADS)

Cheng, Meng-Tzu

In response to the solicitation of the National Institute on Drug Use (NIDA) (NIDA, 2006) for the Development of a Virtual Reality Environment for Teaching about the Impact of Drug Abuse on the Brain, a virtual brain exhibit was developed by the joint venture of Entertainment Science, Inc. and Virtual Heroes, Inc.. This exhibit included a virtual reality learning environment combined with a video game, aiming at improving the neuroscience literacy of the general public, conveying knowledge about the impacts of methamphetamine abuse on the brain to the population, and establishing a stronger concept of drug use prevention among children. This study investigated the effectiveness of this interactive exhibit on middle school students' understanding and attitudes toward drug use. Three main research questions are addressed: (1) What do students learn about basic concepts of neuroscience and the impact of methamphetamine abuse on the brain via the exhibit? (2) How are students' attitudes toward methamphetamine use changed after exposure to the exhibit? (3) What are students' experiences and perceptions of using the exhibit to learn the impact of methamphetamine abuse on the brain? A mixed-method design, including pre/post/delayed-post test instruments, interviews, and video recordings, was conducted for 98 middle school students ranging from sixth to eighth grades to investigate these questions. The results show that students' understanding of the impact of methamphetamine abuse on the brain significantly improved after exposure to the exhibit regardless of grade or gender. Their pre-existing knowledge and their understanding after the exhibit indicated a tendency of progression. Most of the students consistently expressed negative attitudes toward general methamphetamine use regardless of whether it was before or after exposure to the exhibit. However, this exhibit gave them a better reason and made them feel more confident to refuse drugs. Finally, student learning experiences through using the exhibit was a self-regulated learning process. This exhibit possessed several intrinsic values that motivated students to participate and persist in the activity, whereby students performed several cognitive and metacognitive strategies to help the learning activity to best fit individual learning styles and to make the cognitive processes more efficient.

Laser Nitriding of the Newly Developed Ti-20Nb-13Zr at.% Biomaterial Alloy to Enhance Its Mechanical and Corrosion Properties in Simulated Body Fluid

NASA Astrophysics Data System (ADS)

Hussein, M. A.; Kumar, A. Madhan; Yilbas, Bekir S.; Al-Aqeeli, N.

2017-11-01

Despite the widespread application of Ti alloy in the biomedical field, surface treatments are typically applied to improve its resistance to corrosion and wear. A newly developed biomedical Ti-20Nb-13Zr at.% alloy (TNZ) was laser-treated in nitrogen environment to improve its surface characteristics with corrosion protection performance. Surface modification of the alloy by laser was performed through a Nd:YAG laser. The structural and surface morphological alterations in the laser nitrided layer were investigated by XRD and a FE-SEM. The mechanical properties have been evaluated using nanoindentation for laser nitride and as-received samples. The corrosion protection behavior was estimated using electrochemical corrosion analysis in a physiological medium (SBF). The obtained results revealed the production of a dense and compact film of TiN fine grains (micro-/nanosize) with 9.1 µm below the surface. The mechanical assessment results indicated an improvement in the modulus of elasticity, hardness, and resistance of the formed TiN layer to plastic deformation. The electrochemical analysis exhibited that the surface protection performance of the laser nitrided TNZ substrates in the SBF could be considerably enhanced compared to that of the as-received alloy due to the presence of fine grains in the TiN layer resulting from laser nitriding. Furthermore, the untreated and treated Ti-20Nb-13Zr alloy exhibited higher corrosion resistance than the CpTi and Ti6Al4V commercial alloys. The improvements in the surface hardness and corrosion properties of Ti alloy in a simulated body obtained using laser nitriding make this approach a suitable candidate for enhancing the properties of biomaterials.

Extrusion cast explosive

DOEpatents

Scribner, Kenneth J.

1985-01-01

Improved, multiphase, high performance, high energy, extrusion cast explosive compositions, comprising, a crystalline explosive material; an energetic liquid plasticizer; a urethane prepolymer, comprising a blend of polyvinyl formal, and polycaprolactone; a polyfunctional isocyanate; and a catalyst are disclosed. These new explosive compositions exhibit higher explosive content, a smooth detonation front, excellent stability over long periods of storage, and lower sensitivity to mechanical stimulants.

High-performance a-IGZO thin-film transistor with conductive indium-tin-oxide buried layer

NASA Astrophysics Data System (ADS)

Ahn, Min-Ju; Cho, Won-Ju

2017-10-01

In this study, we fabricated top-contact top-gate (TCTG) structure of amorphous indium-gallium-zinc oxide (a-IGZO) thin-film transistors (TFTs) with a thin buried conductive indium-tin oxide (ITO) layer. The electrical performance of a-IGZO TFTs was improved by inserting an ITO buried layer under the IGZO channel. Also, the effect of the buried layer's length on the electrical characteristics of a-IGZO TFTs was investigated. The electrical performance of the transistors improved with increasing the buried layer's length: a large on/off current ratio of 1.1×107, a high field-effect mobility of 35.6 cm2/Vs, a small subthreshold slope of 116.1 mV/dec, and a low interface trap density of 4.2×1011 cm-2eV-1 were obtained. The buried layer a-IGZO TFTs exhibited enhanced transistor performance and excellent stability against the gate bias stress.

Progress toward a performance based specification for diamond grinding wheels

DOE Office of Scientific and Technical Information (OSTI.GOV)

Taylor, J.S.; Piscotty, M.S.; Blaedel, K.L.

1996-11-12

This work sought to improve the communication between users and makers of fine diamond grinding wheels. A promising avenue for this is to formulate a voluntary product standard that comprises performance indicators that bridge the gap between specific user requirements and the details of wheel formulations. We propose a set of performance specifiers of figures-of-merit, that might be assessed by straightforward and traceable testing methods, but do not compromise proprietary information of the wheel user of wheel maker. One such performance indicator might be wheel hardness. In addition we consider technologies that might be required to realize the benefits ofmore » optimized grinding wheels. A non-contact wheel-to- workpiece proximity sensor may provide a means of monitoring wheel wear and thus wheel position, for wheels that exhibit high wear rates in exchange for improved surface finish.« less

AIB-OR: improving onion routing circuit construction using anonymous identity-based cryptosystems.

PubMed

Wang, Changji; Shi, Dongyuan; Xu, Xilei

2015-01-01

The rapid growth of Internet applications has made communication anonymity an increasingly important or even indispensable security requirement. Onion routing has been employed as an infrastructure for anonymous communication over a public network, which provides anonymous connections that are strongly resistant to both eavesdropping and traffic analysis. However, existing onion routing protocols usually exhibit poor performance due to repeated encryption operations. In this paper, we first present an improved anonymous multi-receiver identity-based encryption (AMRIBE) scheme, and an improved identity-based one-way anonymous key agreement (IBOWAKE) protocol. We then propose an efficient onion routing protocol named AIB-OR that provides provable security and strong anonymity. Our main approach is to use our improved AMRIBE scheme and improved IBOWAKE protocol in onion routing circuit construction. Compared with other onion routing protocols, AIB-OR provides high efficiency, scalability, strong anonymity and fault tolerance. Performance measurements from a prototype implementation show that our proposed AIB-OR can achieve high bandwidths and low latencies when deployed over the Internet.

AIB-OR: Improving Onion Routing Circuit Construction Using Anonymous Identity-Based Cryptosystems

PubMed Central

Wang, Changji; Shi, Dongyuan; Xu, Xilei

2015-01-01

The rapid growth of Internet applications has made communication anonymity an increasingly important or even indispensable security requirement. Onion routing has been employed as an infrastructure for anonymous communication over a public network, which provides anonymous connections that are strongly resistant to both eavesdropping and traffic analysis. However, existing onion routing protocols usually exhibit poor performance due to repeated encryption operations. In this paper, we first present an improved anonymous multi-receiver identity-based encryption (AMRIBE) scheme, and an improved identity-based one-way anonymous key agreement (IBOWAKE) protocol. We then propose an efficient onion routing protocol named AIB-OR that provides provable security and strong anonymity. Our main approach is to use our improved AMRIBE scheme and improved IBOWAKE protocol in onion routing circuit construction. Compared with other onion routing protocols, AIB-OR provides high efficiency, scalability, strong anonymity and fault tolerance. Performance measurements from a prototype implementation show that our proposed AIB-OR can achieve high bandwidths and low latencies when deployed over the Internet. PMID:25815879

An improved method to detect correct protein folds using partial clustering.

PubMed

Zhou, Jianjun; Wishart, David S

2013-01-16

Structure-based clustering is commonly used to identify correct protein folds among candidate folds (also called decoys) generated by protein structure prediction programs. However, traditional clustering methods exhibit a poor runtime performance on large decoy sets. We hypothesized that a more efficient "partial" clustering approach in combination with an improved scoring scheme could significantly improve both the speed and performance of existing candidate selection methods. We propose a new scheme that performs rapid but incomplete clustering on protein decoys. Our method detects structurally similar decoys (measured using either C(α) RMSD or GDT-TS score) and extracts representatives from them without assigning every decoy to a cluster. We integrated our new clustering strategy with several different scoring functions to assess both the performance and speed in identifying correct or near-correct folds. Experimental results on 35 Rosetta decoy sets and 40 I-TASSER decoy sets show that our method can improve the correct fold detection rate as assessed by two different quality criteria. This improvement is significantly better than two recently published clustering methods, Durandal and Calibur-lite. Speed and efficiency testing shows that our method can handle much larger decoy sets and is up to 22 times faster than Durandal and Calibur-lite. The new method, named HS-Forest, avoids the computationally expensive task of clustering every decoy, yet still allows superior correct-fold selection. Its improved speed, efficiency and decoy-selection performance should enable structure prediction researchers to work with larger decoy sets and significantly improve their ab initio structure prediction performance.

An improved method to detect correct protein folds using partial clustering

PubMed Central

2013-01-01

Background Structure-based clustering is commonly used to identify correct protein folds among candidate folds (also called decoys) generated by protein structure prediction programs. However, traditional clustering methods exhibit a poor runtime performance on large decoy sets. We hypothesized that a more efficient “partial“ clustering approach in combination with an improved scoring scheme could significantly improve both the speed and performance of existing candidate selection methods. Results We propose a new scheme that performs rapid but incomplete clustering on protein decoys. Our method detects structurally similar decoys (measured using either Cα RMSD or GDT-TS score) and extracts representatives from them without assigning every decoy to a cluster. We integrated our new clustering strategy with several different scoring functions to assess both the performance and speed in identifying correct or near-correct folds. Experimental results on 35 Rosetta decoy sets and 40 I-TASSER decoy sets show that our method can improve the correct fold detection rate as assessed by two different quality criteria. This improvement is significantly better than two recently published clustering methods, Durandal and Calibur-lite. Speed and efficiency testing shows that our method can handle much larger decoy sets and is up to 22 times faster than Durandal and Calibur-lite. Conclusions The new method, named HS-Forest, avoids the computationally expensive task of clustering every decoy, yet still allows superior correct-fold selection. Its improved speed, efficiency and decoy-selection performance should enable structure prediction researchers to work with larger decoy sets and significantly improve their ab initio structure prediction performance. PMID:23323835

Modulation of error-sensitivity during a prism adaptation task in people with cerebellar degeneration

PubMed Central

Shadmehr, Reza; Ohminami, Shinya; Tsutsumi, Ryosuke; Shirota, Yuichiro; Shimizu, Takahiro; Tanaka, Nobuyuki; Terao, Yasuo; Tsuji, Shoji; Ugawa, Yoshikazu; Uchimura, Motoaki; Inoue, Masato; Kitazawa, Shigeru

2015-01-01

Cerebellar damage can profoundly impair human motor adaptation. For example, if reaching movements are perturbed abruptly, cerebellar damage impairs the ability to learn from the perturbation-induced errors. Interestingly, if the perturbation is imposed gradually over many trials, people with cerebellar damage may exhibit improved adaptation. However, this result is controversial, since the differential effects of gradual vs. abrupt protocols have not been observed in all studies. To examine this question, we recruited patients with pure cerebellar ataxia due to cerebellar cortical atrophy (n = 13) and asked them to reach to a target while viewing the scene through wedge prisms. The prisms were computer controlled, making it possible to impose the full perturbation abruptly in one trial, or build up the perturbation gradually over many trials. To control visual feedback, we employed shutter glasses that removed visual feedback during the reach, allowing us to measure trial-by-trial learning from error (termed error-sensitivity), and trial-by-trial decay of motor memory (termed forgetting). We found that the patients benefited significantly from the gradual protocol, improving their performance with respect to the abrupt protocol by exhibiting smaller errors during the exposure block, and producing larger aftereffects during the postexposure block. Trial-by-trial analysis suggested that this improvement was due to increased error-sensitivity in the gradual protocol. Therefore, cerebellar patients exhibited an improved ability to learn from error if they experienced those errors gradually. This improvement coincided with increased error-sensitivity and was present in both groups of subjects, suggesting that control of error-sensitivity may be spared despite cerebellar damage. PMID:26311179

Polydopamine-mediated surface-functionalization of graphene oxide for heavy metal ions removal

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dong, Zhihui; University of Chinese Academy of Sciences, Chinese Academy of Sciences, Beijing 100049; Zhang, Feng

2015-04-15

By utilizing polydopamine (PD) nano-thick interlayer as mediator, polyethylenimine (PEI) brushes with abundant amine groups were grafted onto the surface of PD coated graphene oxide (GO) uniformly via a Michael-Addition reaction and produced a PEI–PD/GO composite nanosheets. The PEI–PD/GO composite exhibited an improved performance for adsorption of heavy metal ions as compared to PEI-coated GO and pure GO. The adsorption capacities for Cu{sup 2+}, Cd{sup 2+}, Pb{sup 2+}, Hg{sup 2+} are up to 87, 106, 197, and 110 mg/g, respectively. To further make the GO based composite operable, PEI–PD/RGO aerogel was prepared through hydrothermal and achieved a high surface areamore » up to 373 m{sup 2}/g. Although the adsorption capacity of PEI–PD/RGO aerogel for heavy metal ions decreases a little as compared to PEI–PD/GO composite dispersion (38, 32, 95, 113 mg/g corresponding to Cu{sup 2+}, Cd{sup 2+}, Pb{sup 2+}, and Hg{sup 2+}, respectively), it could be recycled several times in a simple way by releasing adsorbed metal ions, indicating its potential application for cleaning wastewater. - Graphical abstract: Polyethylenimine (PEI) brushes were grafted onto the surface of graphene oxide (GO) uniformly via a Michael-Addition reaction between the PEI and polydopamine interlayer coated on GO surface. The PEI–PD/GO composite exhibited an improved performance for adsorption of heavy metal ions compared to PEI-coated GO and pure GO. - Highlights: • We prepared polyethylenimine grafted polydopamine-mediated graphene oxide composites. • Introduction of PD layer increases metal ions adsorption capacity. • PEI–PD/RGO aerogel exhibited a superior adsorption performance. • PEI–PD/RGO aerogel can be recycled several times in a simple way.« less

Study of space shuttle orbiter system management computer function. Volume 1: Analysis, baseline design

NASA Technical Reports Server (NTRS)

1975-01-01

A system analysis of the shuttle orbiter baseline system management (SM) computer function is performed. This analysis results in an alternative SM design which is also described. The alternative design exhibits several improvements over the baseline, some of which are increased crew usability, improved flexibility, and improved growth potential. The analysis consists of two parts: an application assessment and an implementation assessment. The former is concerned with the SM user needs and design functional aspects. The latter is concerned with design flexibility, reliability, growth potential, and technical risk. The system analysis is supported by several topical investigations. These include: treatment of false alarms, treatment of off-line items, significant interface parameters, and a design evaluation checklist. An in-depth formulation of techniques, concepts, and guidelines for design of automated performance verification is discussed.

SRF niobium characterization using SIMS and FIB-TEM

DOE Office of Scientific and Technical Information (OSTI.GOV)

Stevie, F. A.

2015-12-04

Our understanding of superconducting radio frequency (SRF) accelerator cavities has been improved by elemental analysis at high depth resolution and by high magnification microscopy. This paper summarizes the technique development and the results obtained on poly-crystalline, large grain, and single crystal SRF niobium. Focused ion beam made possible sample preparation using transmission electron microscopy and the images obtained showed a very uniform oxide layer for all samples analyzed. Secondary ion mass spectrometry indicated the presence of a high concentration of hydrogen and the hydrogen content exhibited a relationship with improvement in performance. Depth profiles of carbon, nitrogen, and oxygen didmore » not show major differences with heat treatment. Niobium oxide less than 10 nm thick was shown to be an effective hydrogen barrier. Niobium with titanium contamination showed unexpected performance improvement.« less

Improving the Unsteady Aerodynamic Performance of Transonic Turbines using Neural Networks

NASA Technical Reports Server (NTRS)

Rai, Man Mohan; Madavan, Nateri K.; Huber, Frank W.

1999-01-01

A recently developed neural net-based aerodynamic design procedure is used in the redesign of a transonic turbine stage to improve its unsteady aerodynamic performance. The redesign procedure used incorporates the advantages of both traditional response surface methodology and neural networks by employing a strategy called parameter-based partitioning of the design space. Starting from the reference design, a sequence of response surfaces based on both neural networks and polynomial fits are constructed to traverse the design space in search of an optimal solution that exhibits improved unsteady performance. The procedure combines the power of neural networks and the economy of low-order polynomials (in terms of number of simulations required and network training requirements). A time-accurate, two-dimensional, Navier-Stokes solver is used to evaluate the various intermediate designs and provide inputs to the optimization procedure. The procedure yielded a modified design that improves the aerodynamic performance through small changes to the reference design geometry. These results demonstrate the capabilities of the neural net-based design procedure, and also show the advantages of including high-fidelity unsteady simulations that capture the relevant flow physics in the design optimization process.

Neural Net-Based Redesign of Transonic Turbines for Improved Unsteady Aerodynamic Performance

NASA Technical Reports Server (NTRS)

Madavan, Nateri K.; Rai, Man Mohan; Huber, Frank W.

1998-01-01

A recently developed neural net-based aerodynamic design procedure is used in the redesign of a transonic turbine stage to improve its unsteady aerodynamic performance. The redesign procedure used incorporates the advantages of both traditional response surface methodology (RSM) and neural networks by employing a strategy called parameter-based partitioning of the design space. Starting from the reference design, a sequence of response surfaces based on both neural networks and polynomial fits are constructed to traverse the design space in search of an optimal solution that exhibits improved unsteady performance. The procedure combines the power of neural networks and the economy of low-order polynomials (in terms of number of simulations required and network training requirements). A time-accurate, two-dimensional, Navier-Stokes solver is used to evaluate the various intermediate designs and provide inputs to the optimization procedure. The optimization procedure yields a modified design that improves the aerodynamic performance through small changes to the reference design geometry. The computed results demonstrate the capabilities of the neural net-based design procedure, and also show the tremendous advantages that can be gained by including high-fidelity unsteady simulations that capture the relevant flow physics in the design optimization process.

Can the Functional Movement Screen™ be used to capture changes in spine and knee motion control following 12 weeks of training?

PubMed

Frost, David M; Beach, Tyson A C; Campbell, Troy L; Callaghan, Jack P; McGill, Stuart M

2017-01-01

To examine whether objective measures of spine and frontal plane knee motion exhibited during Functional Movement Screen™ (FMS) task performance changed following a movement-guided fitness (MOV) and conventional fitness (FIT) exercise intervention. Secondary analysis of a randomized controlled experiment. Before and after 12 weeks of exercise, participants' kinematics were quantified while performing the FMS and a series of general whole-body movement tasks. Biomechanics laboratory. Fifty-two firefighters were assigned to MOV, FIT, or a control (CON) group. Peak lumbar spine flexion/extension, lateral bend and axial twist, and frontal plane knee motion. The post-training kinematic changes exhibited by trainees while performing the FMS tasks were similar in magnitude (effect size < 0.8) to those exhibited by CON. However, when performing the battery of general whole-body movement tasks, only MOV showed significant improvements in spine and frontal plane knee motion control (effect size > 0.5). Whether graded qualitatively, or quantitatively via kinematic analyses, the FMS may not be a viable tool to detect movement-based exercise adaptations. Amendments to the FMS tasks and/or scoring method are needed before it can be used for reasons beyond appraising the ability to move freely, symmetrically, and without pain. Copyright © 2016 Elsevier Ltd. All rights reserved.

Hydro-economic assessment of hydrological forecasting systems

NASA Astrophysics Data System (ADS)

Boucher, M.-A.; Tremblay, D.; Delorme, L.; Perreault, L.; Anctil, F.

2012-01-01

SummaryAn increasing number of publications show that ensemble hydrological forecasts exhibit good performance when compared to observed streamflow. Many studies also conclude that ensemble forecasts lead to a better performance than deterministic ones. This investigation takes one step further by not only comparing ensemble and deterministic forecasts to observed values, but by employing the forecasts in a stochastic decision-making assistance tool for hydroelectricity production, during a flood event on the Gatineau River in Canada. This allows the comparison between different types of forecasts according to their value in terms of energy, spillage and storage in a reservoir. The motivation for this is to adopt the point of view of an end-user, here a hydroelectricity production society. We show that ensemble forecasts exhibit excellent performances when compared to observations and are also satisfying when involved in operation management for electricity production. Further improvement in terms of productivity can be reached through the use of a simple post-processing method.

Radiation damage in lithium-counterdoped n/p silicon solar cells

NASA Technical Reports Server (NTRS)

Hermann, A. M.; Swartz, C. K.; Brandhorst, H. W., Jr.; Weinberg, I.

1980-01-01

Lithium counterdoped n+/p silicon solar cells were irradiated with 1 MV electrons and their post irradiation performance and low temperature annealing properties were compared to that of the 0.35 ohm cm control cells. Cells fabricated from float zone and Czochralski grown silicon were investigated. It was found that the float zone cells exhibited superior radiation resistance compared to the control cells, while no improvement was noted for the Czochralski grown cells. Room temperature and 60 C annealing studies were conducted. The annealing was found to be a combination of first and second order kinetics for short times. It was suggested that the principal annealing mechanism was migration of lithium to a radiation induced defect with subsequent neutralization of the defect by combination with lithium. The effects of base lithium gradient were investigated. It was found that cells with negative base lithium gradients exhibited poor radiation resistance and performance compared to those with positive or no lithium gradients; the latter being preferred for overall performance and radiation resistance.

High-performance III-V MOSFET with nano-stacked high-k gate dielectric and 3D fin-shaped structure.

PubMed

Chen, Szu-Hung; Liao, Wen-Shiang; Yang, Hsin-Chia; Wang, Shea-Jue; Liaw, Yue-Gie; Wang, Hao; Gu, Haoshuang; Wang, Mu-Chun

2012-08-01

A three-dimensional (3D) fin-shaped field-effect transistor structure based on III-V metal-oxide-semiconductor field-effect transistor (MOSFET) fabrication has been demonstrated using a submicron GaAs fin as the high-mobility channel. The fin-shaped channel has a thickness-to-width ratio (TFin/WFin) equal to 1. The nano-stacked high-k Al2O3 dielectric was adopted as a gate insulator in forming a metal-oxide-semiconductor structure to suppress gate leakage. The 3D III-V MOSFET exhibits outstanding gate controllability and shows a high Ion/Ioff ratio > 105 and a low subthreshold swing of 80 mV/decade. Compared to a conventional Schottky gate metal-semiconductor field-effect transistor or planar III-V MOSFETs, the III-V MOSFET in this work exhibits a significant performance improvement and is promising for future development of high-performance n-channel devices based on III-V materials.

High-performance III-V MOSFET with nano-stacked high-k gate dielectric and 3D fin-shaped structure

PubMed Central

2012-01-01

A three-dimensional (3D) fin-shaped field-effect transistor structure based on III-V metal-oxide-semiconductor field-effect transistor (MOSFET) fabrication has been demonstrated using a submicron GaAs fin as the high-mobility channel. The fin-shaped channel has a thickness-to-width ratio (TFin/WFin) equal to 1. The nano-stacked high-k Al2O3 dielectric was adopted as a gate insulator in forming a metal-oxide-semiconductor structure to suppress gate leakage. The 3D III-V MOSFET exhibits outstanding gate controllability and shows a high Ion/Ioff ratio > 105 and a low subthreshold swing of 80 mV/decade. Compared to a conventional Schottky gate metal–semiconductor field-effect transistor or planar III-V MOSFETs, the III-V MOSFET in this work exhibits a significant performance improvement and is promising for future development of high-performance n-channel devices based on III-V materials. PMID:22853458

Electrochemical performance of a solvent-free hybrid ceramic-polymer electrolyte based on Li7La3Zr2O12 in P(EO)15LiTFSI

NASA Astrophysics Data System (ADS)

Keller, Marlou; Appetecchi, Giovanni Battista; Kim, Guk-Tae; Sharova, Varvara; Schneider, Meike; Schuhmacher, Jörg; Roters, Andreas; Passerini, Stefano

2017-06-01

The preparation of hybrid ceramic-polymer electrolytes, consisting of 70 wt% of Li+ cation conducting Li7La3Zr2O12 (LLZO) and 30 wt% of P(EO)15LiTFSI polymer electrolyte, through a solvent-free procedure is reported. The LLZO-P(EO)15LiTFSI hybrid electrolytes exhibit remarkable improvement in terms of flexibility and processability with respect to pure LLZO ceramic electrolytes. The physicochemical and electrochemical investigation shows the effect of LLZO annealing, resulting in ion conduction gain. However, slow charge transfer at the ceramic-polymer interface is also observed especially at higher temperatures. Nevertheless, improved compatibility with lithium metal anodes and good Li stripping/plating behavior are exhibited by the LLZO-P(EO)15LiTFSI hybrid electrolytes with respect to P(EO)15LiTFSI.

Laser irradiation of Mg-Al-Zn alloy: Reduced electrochemical kinetics and enhanced performance in simulated body fluid.

PubMed

Florian, David C; Melia, Michael A; Steuer, Fritz W; Briglia, Bruce F; Purzycki, Michael K; Scully, John R; Fitz-Gerald, James M

2017-05-11

As a lightweight metal with mechanical properties similar to natural bone, Mg and its alloys are great prospects for biodegradable, load bearing implants. However, rapid degradation and H 2 gas production in physiological media has prevented widespread use of Mg alloys. Surface heterogeneities in the form of intermetallic particles dominate the corrosion response. This research shows that surface homogenization significantly improved the biological corrosion response observed during immersion in simulated body fluid (SBF). The laser processed Mg alloy exhibited a 50% reduction in mass loss and H 2 evolution after 24 h of immersion in SBF when compared to the wrought, cast alloy. The laser processed samples exhibited increased wettability as evident from wetting angle studies, further suggesting improved biocompatibility. Electrochemical analysis by potentiodynamic polarization measurements showed that the anodic and cathodic kinetics were reduced following laser processing and are attributed to the surface chemical homogeneity.

Parametric study of plasma-mediated thermoluminescence produced by Al2O3 sub-micron powders

NASA Astrophysics Data System (ADS)

Morávek, T.; Ambrico, P. F.; Ambrico, M.; Schiavulli, L.; Ráheľ, J.

2017-10-01

Sub-micron Al2O3 powders with a surface activated by dielectric barrier discharge exhibit improved performance in wet deposition of ceramic layers. In addressing the possible mechanisms responsible for the observed improvement, a comprehensive thermoluminescence (TL) study of plasma-activated powders was performed. TL offers the unique possibility of exploring the population of intrinsic electrons/holes in the charge trapping states. This study covers a wide range of experimental conditions affecting the TL of powders: treatment time, plasma working gas composition, change of discharge configuration, step-annealing of powder, exposure to laser irradiation and aging time. Deconvoluted TL spectra were followed for the changes in their relative contributions. The TL spectra of all tested gases (air, Ar, N2 and 5% He in N2) consist of the well-known main dosimetric peak at 450 K and a peak of similar magnitude at higher temperatures, centered between 700 and 800 K depending on the working gas used. N2 plasma treatment gave rise to a new specific TL peak at 510 K, which exhibited several peculiarities. Initial thermal annealing of Al2O3 powders led to its significant amplification (unlike the other peaks); the peak was insensitive to optical bleaching, and it exhibited slow gradual growth during the long-term aging test. Besides its relevance to the ceramic processing studies, a comprehensive set of data is presented that provides a useful and unconventional view on plasma-mediated material changes.

Improved Electrochemical Performance of LiFePO4@N-Doped Carbon Nanocomposites Using Polybenzoxazine as Nitrogen and Carbon Sources.

PubMed

Wang, Ping; Zhang, Geng; Li, Zhichen; Sheng, Wangjian; Zhang, Yichi; Gu, Jiangjiang; Zheng, Xinsheng; Cao, Feifei

2016-10-03

Polybenzoxazine is used as a novel carbon and nitrogen source for coating LiFePO 4 to obtain LiFePO 4 @nitrogen-doped carbon (LFP@NC) nanocomposites. The nitrogen-doped graphene-like carbon that is in situ coated on nanometer-sized LiFePO 4 particles can effectively enhance the electrical conductivity and provide fast Li + transport paths. When used as a cathode material for lithium-ion batteries, the LFP@NC nanocomposite (88.4 wt % of LiFePO 4 ) exhibits a favorable rate performance and stable cycling performance.

Performance comparison between p–i–n and p–n junction tunneling field-effect transistors

NASA Astrophysics Data System (ADS)

Yoon, Young Jun; Seo, Jae Hwa; Kang, In Man

2018-06-01

In this study, we investigated the direct-current (DC) and radio-frequency (RF) performances of p–i–n and p–n junction tunneling field-effect transistors (TFETs). Compared to the p–i–n junction TFET, the p–n junction TFET exhibited higher on-state current (I on) because the channel formation mechanism of the p–n junction TFET resulted in a narrower tunneling barrier and an expanded tunneling area. Further, the reduction of I on of the p–n junction TFET by the interface trap was smaller. Moreover, the p–n junction TFET exhibited lower gate-to-drain capacitance (C gd) because a depletion capacitance (C gd,dep) was formed by the depletion region under gate dielectric. Consequently, the p–n junction TFET achieved an improvement of cut-off frequency (f T) and intrinsic delay time (τ), which are related to the current performance and total gate capacitance (C gg). We confirmed the enhancement of device performances in terms of I on, f T, and τ by the conduction mechanism of the p–n junction TFET.

Improved performance of nanoscale junctionless tunnel field-effect transistor based on gate engineering approach

NASA Astrophysics Data System (ADS)

Molaei Imen Abadi, Rouzbeh; Sedigh Ziabari, Seyed Ali

2016-11-01

In this paper, a first qualitative study on the performance characteristics of dual-work function gate junctionless TFET (DWG-JLTFET) on the basis of energy band profile modulation is investigated. A dual-work function gate technique is used in a JLTFET in order to create a downward band bending on the source side similar to PNPN structure. Compared with the single-work function gate junctionless TFET (SWG-JLTFET), the numerical simulation results demonstrated that the DWG-JLTFET simultaneously optimizes the ON-state current, the OFF-state leakage current, and the threshold voltage and also improves average subthreshold slope. It is illustrated that if appropriate work functions are selected for the gate materials on the source side and the drain side, the JLTFET exhibits a considerably improved performance. Furthermore, the optimization design of the tunnel gate length ( L Tun) for the proposed DWG-JLTFET is studied. All the simulations are done in Silvaco TCAD for a channel length of 20 nm using the nonlocal band-to-band tunneling (BTBT) model.

Modulated CH3NH3PbI3−xBrx film for efficient perovskite solar cells exceeding 18%

PubMed Central

Tu, Yongguang; Wu, Jihuai; Lan, Zhang; He, Xin; Dong, Jia; Jia, Jinbiao; Guo, Panfeng; Lin, Jianming; Huang, Miaoliang; Huang, Yunfang

2017-01-01

The organic-inorganic lead halide perovskite layer is a crucial factor for the high performance perovskite solar cell (PSC). We introduce CH3NH3Br in the precursor solution to prepare CH3NH3PbI3−xBrx hybrid perovskite, and an uniform perovskite layer with improved crystallinity and apparent grain contour is obtained, resulting in the significant improvement of photovoltaic performance of PSCs. The effects of CH3NH3Br on the perovskite morphology, crystallinity, absorption property, charge carrier dynamics and device characteristics are discussed, and the improvement of open circuit voltage of the device depended on Br doping is confirmed. Based on above, the device based on CH3NH3PbI2.86Br0.14 exhibits a champion power conversion efficiency (PCE) of 18.02%. This study represents an efficient method for high-performance perovskite solar cell by modulating CH3NH3PbI3−xBrx film. PMID:28303938

Organizational citizenship behavior and the quantity and quality of work group performance.

PubMed

Podsakoff, P M; Ahearne, M; MacKenzie, S B

1997-04-01

Despite the widespread interest in the topic of organizational citizenship behaviors (OCBs), little empirical research has tested the fundamental assumption that these forms of behavior improve the effectiveness of work groups or organizations in which they are exhibited. In the present study, the effects of OCBs on the quantity and quality of the performance of 218 people working in 40 machine crews in a paper mill located in the Northeastern United States were examined. The results indicate that helping behavior and sportsmanship had significant effects on performance quantity and that helping behavior had a significant impact on performance quality. However, civic virtue had no effect on either performance measure.

Enhancing the value of commodity polymers: Part 1. Structure-property relationships in composite materials based on maleated polypropylene/inorganic phosphate glasses. Part 2. New value-added applications for polyesters

NASA Astrophysics Data System (ADS)

Gupta, Mohit

The first part of the thesis (Chapters 2 & 3) describes a new class of organic polymer/inorganic glass composite materials with property improvements that are impossible to achieve with classical polymer blends or composites. These materials exhibit good processability, superior mechanical performance, good thermal stability, and have excellent gas barrier properties. Low glass transition temperature phosphate glasses (Pglass) are used as inorganic fillers and slightly maleated polypropylene is used as the organic polymer matrix. The Pglass, which was dispersed as spherical droplets in the unoriented composites can be elongated into high aspect ratio platelets during the biaxial stretching process. Biaxially oriented films exhibited a brick wall type microstructure with highly aligned inorganic platelets in a ductile organic matrix and the oxygen barrier properties are significantly improved due to presence of Pglass platelets as impermeable inclusions. Mechanical properties of the biaxially oriented films showed significant improvements compared to neat polymer due to uniform dispersion of the Pglass platelets. Properly dispersed and aligned platelets have proven to be very effective for increasing the composite modulus. These developed materials therefore show promise to help fulfill the ever increasing demand for new advanced materials for a wide variety of advanced packaging applications because of their gas barrier properties, flexibility, transparency, mechanical strength and performance under humid conditions. The second part of the thesis (Chapters 4 & 5) describes new value-added applications for polyesters. Chapter 4 reports a novel process for the decolorization of green and blue colored PET bottle flakes using hydrogen peroxide. The decolorized flakes were characterized for color, intrinsic viscosity values. Decolorized flakes exhibited color values similar to those of colorless recycled PET and even though IV values decreased, bleached flakes still exhibit useful molecular weight. The consumption of H2O2 during the bleaching process was quantified by titrating the residual peroxide using a standard solution of potassium permanganate. Chapter 5 reports synthesis of ductile amorphous polymers which change their color as a function of mechanical deformation. Cyano--OPV moieties were covalently incorporated into the backbone of amorphous polyester PETG. The materials exhibit a significant color change upon compression consistent with efficient breakup of the dye aggregates upon deformation and therefore can be useful for technological applications that require smart coatings with integrated scratch detectors.

Improved Memory Function 12 Weeks after Bariatric Surgery

PubMed Central

Gunstad, John; Strain, Gladys; Devlin, Michael J.; Wing, Rena; Cohen, Ronald A.; Paul, Robert H.; Crosby, Ross D.; Mitchell, James E.

2010-01-01

Background There is growing evidence that obesity is associated with poor neurocognitive outcome. Bariatric surgery is an effective intervention for morbid obesity and improves many comorbid medical conditions that are associated with cognitive dysfunction. The effects of bariatric surgery on cognition are unknown. Methods Prospective study total of 150 individuals (109 bariatric surgery patients enrolled in the Longitudinal Assessment of Bariatric Surgery (LABS) project and 41 obese controls that did not undergo surgery) completed cognitive evaluation at baseline and 12 week follow-up. Demographic, medical, and psychosocial information was also collected to elucidate possible mechanisms of change. Results Many bariatric surgery patients exhibited impaired performance on cognitive testing at baseline (range from 4.6%–23.9%). However, surgery patients were no more likely to exhibit decline on two or more cognitive tests at 12-week follow-up than obese controls [12.84% vs. 23.26%; χ2 (1) = 2.51, p = .11]. Group comparisons using repeated measures MANOVA showed surgery patients had improved memory performance at 12 week follow-up [λ = .86, F(4, 147) = 5.88, p<.001], whereas obese controls actually declined. Regression analyses showed surgery patients without hypertension had better short delay recall at 12 weeks than those that did [β = 0.31, p = .005], though other demographic and medical variables were largely unrelated to test performance. Conclusion The current results suggest that cognitive impairment is common in bariatric surgery patients, though these deficits may be at least partly reversible. Future studies are needed to clarify underlying mechanisms, particularly longitudinal studies employing neuroimaging and blood markers. PMID:21145295

A non-chemically selective top-down approach towards the preparation of hierarchical TS-1 zeolites with improved oxidative desulfurization catalytic performance.

PubMed

Du, Shuting; Chen, Xiaoxin; Sun, Qiming; Wang, Ning; Jia, Mingjun; Valtchev, Valentin; Yu, Jihong

2016-02-28

Hierarchical TS-1 zeolites with secondary macropores have been successfully prepared by using two different fluoride-containing chemical etching post-treated routes. Hierarchical TS-1 zeolites exhibited a chemical composition similar to that of the parent material and showed remarkably enhanced catalytic activity in oxidative desulfurization reaction.

Conversion of methanol to propylene over hierarchical HZSM-5: the effect of Al spatial distribution.

PubMed

Li, Jianwen; Ma, Hongfang; Chen, Yan; Xu, Zhiqiang; Li, Chunzhong; Ying, Weiyong

2018-06-08

Different silicon sources caused diverse Al spatial distribution in HZSM-5, and this affected the hierarchical structures and catalytic performance of desilicated zeolites. After being treated with 0.1 M NaOH, HZSM-5 zeolites synthesized with silica sol exhibited relatively widely distributed mesopores and channels, and possessed highly improved propylene selectivity and activity stability.

Extrusion cast explosive

DOEpatents

Scribner, K.J.

1985-01-29

Improved, multiphase, high performance, high energy, extrusion cast explosive compositions, comprising, a crystalline explosive material; an energetic liquid plasticizer; a urethane prepolymer, comprising a blend of polyvinyl formal, and polycaprolactone; a polyfunctional isocyanate; and a catalyst are disclosed. These new explosive compositions exhibit higher explosive content, a smooth detonation front, excellent stability over long periods of storage, and lower sensitivity to mechanical stimulants. 1 fig.

One-step synthesis of three-dimensional Pd polyhedron networks with enhanced electrocatalytic performance.

PubMed

Xu, You; Xu, Rui; Cui, Jianhua; Liu, Yang; Zhang, Bin

2012-04-21

Three-dimensional Pd polyhedron networks (Pd PNs) have been fabricated for the first time through a one-step, Cu(2+)-assisted, solution-chemical approach. These as-prepared 3D Pd PNs exhibit high stability and remarkably improved electrocatalytic activity toward formic acid oxidation over commercially available Pd black. This journal is © The Royal Society of Chemistry 2012

Hypersonic Technology Developments with EU Co-Funded Projects

DTIC Science & Technology

2010-09-01

metal or even high performance alloys . The hollow sphere technology allows high degrees of porosities, reproducible properties and fair process control...sandwich structure configuration will be investigated. Titanium alloys and Ti-aluminides exhibit excellent mechanical properties for applications where...cooling techniques, new alloys , improved thermodynamic cycles by increased pressure ratios and TIT, etc… As the Olympus 593 engine was based on the

Extrusion cast explosive

DOEpatents

Scribner, K.J.

1985-11-26

Disclosed is an improved, multiphase, high performance, high energy, extrusion cast explosive compositions, comprising, a crystalline explosive material; an energetic liquid plasticizer; a urethane prepolymer, comprising a blend of polyvinyl formal, and polycaprolactone; a polyfunctional isocyanate; and a catalyst. These new explosive compositions exhibit higher explosive content, a smooth detonation front, excellent stability over long periods of storage, and lower sensitivity to mechanical stimulants. 1 fig.

Plasmonically enhanced electromotive force of narrow bandgap PbS QD-based photovoltaics.

PubMed

Li, Xiaowei; McNaughter, Paul D; O'Brien, Paul; Minamimoto, Hiro; Murakoshi, Kei

2018-05-30

Electromotive force of photovoltaics is a key to define the output power density of photovoltaics. Multiple exciton generation (MEG) exhibited by semiconductor quantum dots (QDs) has great potential to enhance photovoltaic performance owing to the ability to generate more than one electron-hole pairs when absorbing a single photon. However, even in MEG-based photovoltaics, limitation of modifying the electromotive force exists due to the intrinsic electrochemical potential of the conduction band-edges of QDs. Here we report a pronouncedly improved photovoltaic performance by constructing a PbS QD-sensitized electrode that comprises plasmon-active Au nanoparticles embedded in a titanium dioxide thin film. Significant enhancement on electromotive force is characterized by the onset potential of photocurrent generation using MEG-effective PbS QDs with a narrow bandgap energy (Eg = 0.9 eV). By coupling with localized surface plasmon resonance (LSPR), such QDs exhibit improved photoresponses and the highest output power density over the other QDs with larger bandgap energies (Eg = 1.1 and 1.7 eV) under visible light irradiation. The wavelength-dependent onset potential and the output power density suggest effective electron injection owing to the enhanced density of electrons excited by energy overlapping between MEG and LSPR.

Effects of the butyric acid-producing strain Clostridium butyricum MIYAIRI 588 on broiler and piglet zootechnical performance and prevention of necrotic enteritis.

PubMed

Takahashi, Motomichi; McCartney, Elinor; Knox, Anne; Francesch, Maria; Oka, Kentaro; Wada, Kaoruko; Ideno, Marie; Uno, Koji; Kozłowski, Krzysztof; Jankowski, Jan; Gracia, Marta I; Morales, Joaquin; Kritas, Spyridon K; Esteve-Garcia, Enric; Kamiya, Shigeru

2018-06-01

The objective of this study was to assess the effects of a probiotic strain Clostridium butyricumMIYAIRI 588 (CBM588) on broiler and weaned piglet health and zootechnical performance. Five field studies were carried out in broilers and five in weaned piglets under European feed additive guidelines. Each study followed a randomized blocked design with two treatments: Control (basal diet) and CBM588 supplemented groups. The zootechnical performance parameters selected were body weight, daily gain, feed intake and feed efficiency (feed:gain). Broilers fed diets with CBM588 gained significantly more weight (+2%, p < .001) and exhibited significantly better feed efficiency (-1.6%, p < .001) in comparison with Controls. Similarly, analysis of pooled data of weaned piglet trials showed that CBM588-fed piglets were significantly heavier than Controls (+2.6%, p = .014), exhibited significantly higher mean daily gain (+4.7%; p = .004), and significantly improved feed efficiency (-4.2%, p = .001). In addition to the zootechnical efficacy studies, the preventive effect of CBM588 on necrotic enteritis (NE) was assessed in a natural challenge model in broilers where CBM588 reduced the incidence and severity of NE lesions. These data indicate the potential of CBM588 to improve broiler and weaned piglet zootechnical performance, and to make a positive contribution to animal health. © 2018 Japanese Society of Animal Science.

Sulfonated Holey Graphene Oxide (SHGO) Filled Sulfonated Poly(ether ether ketone) Membrane: The Role of Holes in the SHGO in Improving Its Performance as Proton Exchange Membrane for Direct Methanol Fuel Cells.

PubMed

Jiang, Zhong-Jie; Jiang, Zhongqing; Tian, Xiaoning; Luo, Lijuan; Liu, Meilin

2017-06-14

Sulfonated holey graphene oxides (SHGOs) have been synthesized by the etching of sulfonated graphene oxides with concentrated HNO 3 under the assistance of ultrasonication. These SHGOs could be used as fillers for the sulfonated aromatic poly(ether ether ketone) (SPEEK) membrane. The obtained SHGO-incorporated SPEEK membrane has a uniform and dense structure, exhibiting higher performance as proton exchange membranes (PEMs), for instance, higher proton conductivity, lower activation energy for proton conduction, and comparable methanol permeability, as compared to Nafion 112. The sulfonated graphitic structure of the SHGOs is believed to be one of the crucial factors resulting in the higher performance of the SPEEK/SHGO membrane, since it could increase the local density of the -SO 3 H groups in the membrane and induce a strong interfacial interaction between SHGO and the SPEEK matrix, which improve the proton conductivity and lower the swelling ratio of the membrane, respectively. Additionally, the proton conductivity of the membrane could be further enhanced by the presence of the holes in the graphitic planes of the SHGOs, since it provides an additional channel for transport of the protons. When used, direct methanol fuel cell with the SPEEK/SHGO membrane is found to exhibit much higher performance than that with Nafion 112, suggesting potential use of the SPEEK/SHGO membrane as the PEMs.

Palladium nanoparticles functionalized graphene nanosheets for Li-O2 batteries: enhanced performance by tailoring the morphology of discharge product

NASA Astrophysics Data System (ADS)

Wang, Liangjun; Chen, Wei; SSL Team

Lithium oxygen (Li-O2) batteries represent a promising candidate for the next generation electric vehicle.1-3 Despite the attractive prospect, some issues including large overpotentials, poor recyclability and unstable electrolyte4-6 limit the wide applications of Li-O2 batteries. Due to the insoluble and non-conductive nature of discharge product Li2O2, it has been widely accepted that the performance of oxygen evolution reaction (OER) process is not only determined by the catalyst itself but also close linked to morphology and electronic conductivity of Li2O2 formed during oxygen reduction reaction (ORR) process. Herein, we report a strategy to improve the battery performance by tailoring the morphology of discharge product. By using graphene nanosheets (GNSs) functionalized with Pd nanoparticles (NPs) as cathode catalyst, the growth and morphology of the discharge products of Li2O2 can be effectively tailored, thereby leading to the improved Li-O2 battery performance. Surprisingly, on bare GNSs cathode, the discharge product showed widely observed large-sized toroidal morphology. While for Pd NPs functionalized GNSs, the discharge product was homogenously distributed on the cathode in the form of small nanoparticles with an average diameter of 25 nm. As a result, Pd NPs functionalized GNSs exhibited a high discharge capacity of 7690 mAh g-1. Meanwhile, the battery with tailored morphology exhibits lower charge overpotential.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sun, Hongyu; Ahmad, Mashkoor, E-mail: mashkoorahmad2003@yahoo.com; Luo, Jun

Graphical abstract: The synthesized SnS{sub 2} nanoflakes decorated multiwalled carbon nanotubes hybrid structures exhibit large reversible capacity, superior cycling performance, and good rate capability as compared to pure SnS{sub 2} nanoflakes. - Highlights: • Synthesis of SnS{sub 2} nanoflakes decorated multiwalled carbon nanotubes hybrid structures. • Simple solution-phase approach. • Morphology feature of SnS{sub 2}. • Enhanced performance as Li-ion batteries. - Abstract: SnS{sub 2} nanoflakes decorated multiwalled carbon nanotubes (MWCNTs) hybrid structures are directly synthesized via a simple solution-phase approach. The as-prepared SnS{sub 2}/MWCNTs structures are investigated as anode materials for Li-ion batteries as compared with SnS{sub 2} nanoflakes.more » It has been found that the composite structure exhibit excellent lithium storage performance with a large reversible capacity, superior cycling performance, and good rate capability as compared to pure SnS{sub 2} nanoflakes. The first discharge and charge capacities have been found to be 1416 and 518 mA h g{sup −1} for SnS{sub 2}/MWCNTs composite electrodes at a current density of 100 mA g{sup −1} between 5 mV and 1.15 V versus Li/Li{sup +}. A stable reversible capacity of ∼510 mA h g{sup −1} is obtained for 50 cycles. The improved electrochemical performance may be attributed to the flake-morphology feature of SnS{sub 2} and the addition of MWCNTs that can hinder the agglomeration of the active materials and improve the conductivity of the composite electrode simultaneously.« less

How do engineering attitudes vary by gender and motivation? Attractiveness of outreach science exhibitions in four countries

NASA Astrophysics Data System (ADS)

Salmi, Hannu; Thuneberg, Helena; Vainikainen, Mari-Pauliina

2016-11-01

Outreach activities, like mobile science exhibitions, give opportunities to hands-on experiences in an attractive learning environment. We analysed attitudes, motivation and learning during a science exhibition visit, their relations to gender and future educational plans in Finland, Estonia, Latvia and Belgium (N = 1210 sixth-graders). Pupils' performance in a knowledge test improved after the visit. Autonomous motivation and attitudes towards science predicted situation motivation awakened in the science exhibition. Interestingly, the scientist attitude and the societal attitude were clearly separate dimensions. The third dimension was manifested in the engineering attitude typical for boys, who were keener on working with appliances, designing computer games and animations. Scientist and societal attitudes correlated positively and engineering attitude correlated negatively with the future educational plans of choosing the academic track in secondary education. The societal perspective on science was connected to above average achievement. In the follow-up test, these attitudes showed to be quite stable.

Electrolysed reduced water decreases reactive oxygen species-induced oxidative damage to skeletal muscle and improves performance in broiler chickens exposed to medium-term chronic heat stress.

PubMed

Azad, M A K; Kikusato, M; Zulkifli, I; Toyomizu, M

2013-01-01

1. The present study was designed to achieve a reduction of reactive oxygen species (ROS)-induced oxidative damage to skeletal muscle and to improve the performance of broiler chickens exposed to chronic heat stress. 2. Chickens were given a control diet with normal drinking water, or diets supplemented with cashew nut shell liquid (CNSL) or grape seed extract (GSE), or a control diet with electrolysed reduced water (ERW) for 19 d after hatch. Thereafter, chickens were exposed to a temperature of either 34°C continuously for a period of 5 d, or maintained at 24°C, on the same diets. 3. The control broilers exposed to 34°C showed decreased weight gain and feed consumption and slightly increased ROS production and malondialdehyde (MDA) concentrations in skeletal muscle. The chickens exposed to 34°C and supplemented with ERW showed significantly improved growth performance and lower ROS production and MDA contents in tissues than control broilers exposed to 34°C. Following heat exposure, CNSL chickens performed better with respect to weight gain and feed consumption, but still showed elevated ROS production and skeletal muscle oxidative damage. GSE chickens did not exhibit improved performance or reduced skeletal muscle oxidative damage. 4. In conclusion, this study suggests that ERW could partially inhibit ROS-induced oxidative damage to skeletal muscle and improve growth performance in broiler chickens under medium-term chronic heat treatment.

Design, synthesis, and structure-property relationships of isoindigo-based conjugated polymers.

PubMed

Lei, Ting; Wang, Jie-Yu; Pei, Jian

2014-04-15

Conjugated polymers have developed rapidly due to their promising applications in low-cost, lightweight, and flexible electronics. The development of the third-generation donor-acceptor (D-A) polymers greatly improved the device performance in organic solar cells (OSCs) and field-effect transistors (FETs). However, for further improvement of device performance, scientists need to develop new building blocks, in particular electron-deficient aromatics, and gain an in-depth understanding of the structure-property relationships. Recently, isoindigo has been used as a new acceptor of D-A conjugated polymers. An isomer of indigo, isoindigo is a less well-known dye and can be isolated as a by-product from certain biological processes. It has two lactam rings and exhibits strong electron-withdrawing character. This electron deficiency gives isoindigo-based polymers intriguing properties, such as broad absorption and high open circuit voltage in OSCs, as well as high mobility and good ambient stability in FETs. In this Account, we review our recent progress on the design, synthesis, and structure-property relationship study of isoindigo-based polymers for FETs. Starting with some discussion on carrier transport in polymer films, we provide some basic strategies towards high-performance polymer FETs. We discuss the stability issue of devices, the impediment of the alkyl side chains, and the choice of the donor part of conjugated polymers. We demonstrate that introducing the isoindigo core effectively lowers the HOMO levels of polymers and provides FETs with long-time stability. In addition, we have found that when we use inappropriate alkyl side chains or non-centrosymmetric donors, the device performance of isoindigo polymers suffers. To further improve device performance and ambient stability, we propose several design strategies, such as using farther branched alkyl chains, modulating polymer energy levels, and extending π-conjugated backbones. We have found that using farther branched alkyl chains can effectively decrease interchain π-π stacking distance and improve carrier mobility. When we introduce electron-deficient functional groups on the isoindigo core, the LUMO levels of the polymers markedly decrease, which significantly improves the electron mobility and device stability. In addition, we present a new polymer system called BDOPV, which is based on the concept of π-extended isoindigo. By application of some strategies successfully used in isoindigo-based polymers, BDOPV-based polymers exhibit high mobility and good stability both in n-type and in ambipolar FETs. We believe that a synergy of molecular engineering strategies towards the isoindigo core, donor units, and side chains may further improve the performance and broaden the application of isoindigo-based polymers.

Planar-integrated single-crystalline perovskite photodetectors

PubMed Central

Saidaminov, Makhsud I.; Adinolfi, Valerio; Comin, Riccardo; Abdelhady, Ahmed L.; Peng, Wei; Dursun, Ibrahim; Yuan, Mingjian; Hoogland, Sjoerd; Sargent, Edward H.; Bakr, Osman M.

2015-01-01

Hybrid perovskites are promising semiconductors for optoelectronic applications. However, they suffer from morphological disorder that limits their optoelectronic properties and, ultimately, device performance. Recently, perovskite single crystals have been shown to overcome this problem and exhibit impressive improvements: low trap density, low intrinsic carrier concentration, high mobility, and long diffusion length that outperform perovskite-based thin films. These characteristics make the material ideal for realizing photodetection that is simultaneously fast and sensitive; unfortunately, these macroscopic single crystals cannot be grown on a planar substrate, curtailing their potential for optoelectronic integration. Here we produce large-area planar-integrated films made up of large perovskite single crystals. These crystalline films exhibit mobility and diffusion length comparable with those of single crystals. Using this technique, we produced a high-performance light detector showing high gain (above 104 electrons per photon) and high gain-bandwidth product (above 108 Hz) relative to other perovskite-based optical sensors. PMID:26548941

Enhanced solubility of piperine using hydrophilic carrier-based potent solid dispersion systems.

PubMed

Thenmozhi, Kathavarayan; Yoo, Young Je

2017-09-01

Piperine alkaloid, an important constituent of black pepper, exhibits numerous therapeutic properties, whereas its usage as a drug is limited due to its poor solubility in aqueous medium, which leads to poor bioavailability. Herein, a new method has been developed to improve the solubility of this drug based on the development of solid dispersions with improved dissolution rate using hydrophilic carriers such as sorbitol (Sor), polyethylene glycol (PEG) and polyvinyl pyrrolidone K30 (PVP) by solvent method. Physical mixtures of piperine and carriers were also prepared for comparison. The physicochemical properties of the prepared solid dispersions were examined using SEM, TEM, DSC, XRD and FT-IR. In vitro dissolution profile of the solid dispersions was recorded and compared with that of the pure piperine and physical mixtures. The effect of these carriers on the aqueous solubility of piperine has been investigated. The solid dispersions of piperine with Sor, PEG and PVP exhibited superior performance for the dissolution of piperine with a drug release of 70%, 76% and 89%, respectively after 2 h compared to physical mixtures and pure piperine, which could be due to its transformation from crystalline to amorphous form as well as the attachment of hydrophilic carriers to the surface of poorly water-soluble piperine. Results suggest that the piperine solid dispersions prepared with improved in vitro release exhibit potential advantage in delivering poorly water-soluble piperine as an oral supplement.

Few layer graphene wrapped mixed phase TiO2 nanofiber as a potential electrode material for high performance supercapacitor applications

NASA Astrophysics Data System (ADS)

Thirugnanam, Lavanya; Sundara, Ramaprabhu

2018-06-01

A combination of favorable composition and optimized anatase/rutile mixed-phase TiO2 (MPTNF)/Hydrogen exfoliated graphene (HEG) composite nanofibers (MPTNF/HEG) and anatase/rutile mixed-phase TiO2/reduced graphene oxide (rGO) composite nanofibers (MPTNF/rGO) have been reported to enhance the electrochemical properties for supercapacitor applications. These composite nanofibers have been synthesized by an efficient route of electrospinning together with the help of easy chemical methods. Both the composites exhibit good charge storage capability with enhanced pseudocapacitance and electric double-layer capacitance (EDLC) as confirmed by cyclic voltammetry studies. MPTNF/HEG composite showed maximum specific capacitance of 210.5 F/g at the current density of 1 A/g, which was mainly due to its availability of the more active sites for ions adsorption on a few layers of graphene wrapped TiO2 nanofiber surface. The synergistic effect of anatase/rutile mixed phase with one dimensional nanostructure and the electronic interaction between TiO2 and few layer graphene provided the subsequent improvement of ion adsorption capacity. Also exhibit excellent electrochemical performance to improve the capacitive properties of TiO2 electrode materials which is required for the development of flexible electrodes in energy storage devices and open up new opportunities for high performance supercapacitors.

Hybrid Modeling Approach to Estimate Exposures of Hazardous Air Pollutants (HAPs) for the National Air Toxics Assessment (NATA).

PubMed

Scheffe, Richard D; Strum, Madeleine; Phillips, Sharon B; Thurman, James; Eyth, Alison; Fudge, Steve; Morris, Mark; Palma, Ted; Cook, Richard

2016-11-15

A hybrid air quality model has been developed and applied to estimate annual concentrations of 40 hazardous air pollutants (HAPs) across the continental United States (CONUS) to support the 2011 calendar year National Air Toxics Assessment (NATA). By combining a chemical transport model (CTM) with a Gaussian dispersion model, both reactive and nonreactive HAPs are accommodated across local to regional spatial scales, through a multiplicative technique designed to improve mass conservation relative to previous additive methods. The broad scope of multiple pollutants capturing regional to local spatial scale patterns across a vast spatial domain is precedent setting within the air toxics community. The hybrid design exhibits improved performance relative to the stand alone CTM and dispersion model. However, model performance varies widely across pollutant categories and quantifiably definitive performance assessments are hampered by a limited observation base and challenged by the multiple physical and chemical attributes of HAPs. Formaldehyde and acetaldehyde are the dominant HAP concentration and cancer risk drivers, characterized by strong regional signals associated with naturally emitted carbonyl precursors enhanced in urban transport corridors with strong mobile source sector emissions. The multiple pollutant emission characteristics of combustion dominated source sectors creates largely similar concentration patterns across the majority of HAPs. However, reactive carbonyls exhibit significantly less spatial variability relative to nonreactive HAPs across the CONUS.

Improved perovskite phototransistor prepared using multi-step annealing method

NASA Astrophysics Data System (ADS)

Cao, Mingxuan; Zhang, Yating; Yu, Yu; Yao, Jianquan

2018-02-01

Organic-inorganic hybrid perovskites with good intrinsic physical properties have received substantial interest for solar cell and optoelectronic applications. However, perovskite film always suffers from a low carrier mobility due to its structural imperfection including sharp grain boundaries and pinholes, restricting their device performance and application potential. Here we demonstrate a straightforward strategy based on multi-step annealing process to improve the performance of perovskite photodetector. Annealing temperature and duration greatly affects the surface morphology and optoelectrical properties of perovskites which determines the device property of phototransistor. The perovskite films treated with multi-step annealing method tend to form highly uniform, well-crystallized and high surface coverage perovskite film, which exhibit stronger ultraviolet-visible absorption and photoluminescence spectrum compare to the perovskites prepared by conventional one-step annealing process. The field-effect mobilities of perovskite photodetector treated by one-step direct annealing method shows mobility as 0.121 (0.062) cm2V-1s-1 for holes (electrons), which increases to 1.01 (0.54) cm2V-1s-1 for that treated with muti-step slow annealing method. Moreover, the perovskite phototransistors exhibit a fast photoresponse speed of 78 μs. In general, this work focuses on the influence of annealing methods on perovskite phototransistor, instead of obtains best parameters of it. These findings prove that Multi-step annealing methods is feasible to prepared high performance based photodetector.

Influence of reactivation on the electrochemical performances of activated carbon based on coconut shell.

PubMed

Geng, Xin; Li, Lixiang; Zhang, Meiling; An, Baigang; Zhu, Xiaoming

2013-12-01

Coconut shell-based activated carbon (AC) were prepared by CO2 activation, and then the ACs with higher mesopore ratio were obtained by steam activation and by impregnating iron catalyst followed by steam activation, respectively. The AC with the highest mesopore ratio (AChmr) shows superior capacitive behavior, power output and high-frequency performance in supercapacitors. The results should attribute to the connection of its wide micropores and mesopores larger than 3 nm, which is more favorable for fast ionic transportation. The pore size distribution exhibits that the mesopore ratios of the ACs are significantly increased by reactivation of steam or catalyst up to 75% and 78%, respectively. As evidenced by cyclic voltammetry, electrochemical impedance spectroscopy, and galvanostatic measurements, the AChmr shows superior capacitive behaviors, conductivity and performance of electrolytic ionic transportation. The response current densities are evidently enhanced through the cyclic voltammery test at 50 mV/sec scan rate. The electrochemical impedance spectroscopy demonstrates that the conductivity and ion transport performance of the ACs are improved. The specific capacitances of the ACs were increased from 140 to 240 F/g at 500 mA/g current density. The AChmr can provide much higher power density while still maintaining good energy density, and demonstrate excellent high-frequency performances. The pore structure and conductivity of the AChmr also improve the cycleability and self-discharge of supercapacitors. Such AChmr exhibits a great potential in supercapacitors, particularly for applications where high power output and good high-frequency capacitive performances are required. Copyright © 2013 The Research Centre for Eco-Environmental Sciences, Chinese Academy of Sciences. Published by Elsevier B.V. All rights reserved.

Implementation of Patient Decision Support Interventions in Primary Care: The Role of Relational Coordination.

PubMed

Tietbohl, Caroline K; Rendle, Katharine A S; Halley, Meghan C; May, Suepattra G; Lin, Grace A; Frosch, Dominick L

2015-11-01

The benefits of patient decision support interventions (DESIs) have been well documented. However, DESIs remain difficult to incorporate into clinical practice. Relational coordination (RC) has been shown to improve performance and quality of care in health care settings. This study aims to demonstrate how applying RC theory to DESI implementation could elucidate underlying issues limiting widespread uptake. Five primary care clinics in Northern California participated in a DESI implementation project. We used a deductive thematic approach guided by behaviors outlined in RC theory to analyze qualitative data collected from ethnographic field notes documenting the implementation process and focus groups with health care professionals. We then systematically compared the qualitative findings with quantitative DESI distribution data. Based on DESI distribution rates, clinics were placed into 3 performance categories: high, middle, and low. Qualitative data illustrated how each clinic's performance related to RC behaviors. Consistent with RC theory, the high-performing clinic exhibited frequent, timely, and accurate communication and positive working relationships. The 3 middle-performing clinics exhibited high-quality communication within physician-staff teams but limited communication regarding DESI implementation across the clinic. The lowest-performing clinic was characterized by contentious relationships and inadequate communication. Limitations of the study include nonrandom selection of clinics and limited geographic diversity. In addition, ethnographic data collected documented only DESI implementation practices and not larger staff interactions contributing to RC. These findings suggest that a high level of RC within clinical settings may be a key component and facilitator of successful DESI implementation. Future attempts to integrate DESIs into clinical practice should consider incorporating interventions designed to increase positive RC behaviors as a potential means to improve uptake. © The Author(s) 2015.

A vanadium-doped ZnO nanosheets-polymer composite for flexible piezoelectric nanogenerators

NASA Astrophysics Data System (ADS)

Shin, Sung-Ho; Kwon, Yang Hyeog; Lee, Min Hyung; Jung, Joo-Yun; Seol, Jae Hun; Nah, Junghyo

2016-01-01

We report high performance flexible piezoelectric nanogenerators (PENGs) by employing vanadium (V)-doped ZnO nanosheets (NSs) and the polydimethylsiloxane (PDMS) composite structure. The V-doped ZnO NSs were synthesized to overcome the inherently low piezoelectric properties of intrinsic ZnO. Ferroelectric phase transition induced in the V-doped ZnO NSs contributed to significantly improve the performance of the PENGs after the poling process. Consequently, the PENGs exhibited high output voltage and current up to ~32 V and ~6.2 μA, respectively, under the applied strain, which are sufficient to directly turn on a number of light emitting diodes (LEDs). The composite approach for PENG fabrication is scalable, robust, and reproducible during periodic bending/releasing over extended cycles. The approach introduced here extends the performance limits of ZnO-based PENGs and demonstrates their potential as energy harvesting devices.We report high performance flexible piezoelectric nanogenerators (PENGs) by employing vanadium (V)-doped ZnO nanosheets (NSs) and the polydimethylsiloxane (PDMS) composite structure. The V-doped ZnO NSs were synthesized to overcome the inherently low piezoelectric properties of intrinsic ZnO. Ferroelectric phase transition induced in the V-doped ZnO NSs contributed to significantly improve the performance of the PENGs after the poling process. Consequently, the PENGs exhibited high output voltage and current up to ~32 V and ~6.2 μA, respectively, under the applied strain, which are sufficient to directly turn on a number of light emitting diodes (LEDs). The composite approach for PENG fabrication is scalable, robust, and reproducible during periodic bending/releasing over extended cycles. The approach introduced here extends the performance limits of ZnO-based PENGs and demonstrates their potential as energy harvesting devices. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr07185b

Task-based statistical image reconstruction for high-quality cone-beam CT

NASA Astrophysics Data System (ADS)

Dang, Hao; Webster Stayman, J.; Xu, Jennifer; Zbijewski, Wojciech; Sisniega, Alejandro; Mow, Michael; Wang, Xiaohui; Foos, David H.; Aygun, Nafi; Koliatsos, Vassilis E.; Siewerdsen, Jeffrey H.

2017-11-01

Task-based analysis of medical imaging performance underlies many ongoing efforts in the development of new imaging systems. In statistical image reconstruction, regularization is often formulated in terms to encourage smoothness and/or sharpness (e.g. a linear, quadratic, or Huber penalty) but without explicit formulation of the task. We propose an alternative regularization approach in which a spatially varying penalty is determined that maximizes task-based imaging performance at every location in a 3D image. We apply the method to model-based image reconstruction (MBIR—viz., penalized weighted least-squares, PWLS) in cone-beam CT (CBCT) of the head, focusing on the task of detecting a small, low-contrast intracranial hemorrhage (ICH), and we test the performance of the algorithm in the context of a recently developed CBCT prototype for point-of-care imaging of brain injury. Theoretical predictions of local spatial resolution and noise are computed via an optimization by which regularization (specifically, the quadratic penalty strength) is allowed to vary throughout the image to maximize local task-based detectability index ({{d}\\prime} ). Simulation studies and test-bench experiments were performed using an anthropomorphic head phantom. Three PWLS implementations were tested: conventional (constant) penalty; a certainty-based penalty derived to enforce constant point-spread function, PSF; and the task-based penalty derived to maximize local detectability at each location. Conventional (constant) regularization exhibited a fairly strong degree of spatial variation in {{d}\\prime} , and the certainty-based method achieved uniform PSF, but each exhibited a reduction in detectability compared to the task-based method, which improved detectability up to ~15%. The improvement was strongest in areas of high attenuation (skull base), where the conventional and certainty-based methods tended to over-smooth the data. The task-driven reconstruction method presents a promising regularization method in MBIR by explicitly incorporating task-based imaging performance as the objective. The results demonstrate improved ICH conspicuity and support the development of high-quality CBCT systems.

Improved mechanical performance of PBO fiber-reinforced bismaleimide composite using mixed O2/Ar plasma

NASA Astrophysics Data System (ADS)

Liu, Dong; Chen, Ping; Yu, Qi; Ma, Keming; Ding, Zhenfeng

2014-06-01

The mixed O2/Ar plasma was employed to enhance mechanical properties of the PBO/bismaleimide composite. The interlaminar shear strength was improved to 61.6 MPa or by 38.1%, but the composite brittleness increased. The plasma gas compositions exhibited notable effects on the interfacial adhesion strength. XPS results suggested that the mixed plasma presented higher activation effects on the surface chemical compositions than pure gas plasmas and a larger number of oxygen atoms and hydrophilic groups were introduced on the fiber surface due to the synergy effect, but the synergy effect was considerably performed only within the O2 percentage range of 40-60%. The fibers surface was increasingly etched with growing the O2 contents in the plasma, deteriorating the fibers tensile strength. SEM micrographs demonstrated that the composite shear fracture changed from debonding to cohesive failure in the matrices, and the improving mechanisms were discussed.

Ultrasmooth Perovskite Film via Mixed Anti-Solvent Strategy with Improved Efficiency.

PubMed

Yu, Yu; Yang, Songwang; Lei, Lei; Cao, Qipeng; Shao, Jun; Zhang, Sheng; Liu, Yan

2017-02-01

Most antisolvents employed in previous research were miscible with perovskite precursor solution. They always led to fast formation of perovskite even if the intermediate stage existed, which was not beneficial to obtain high quality perovskite films and made the formation process less controllable. In this work, a novel ethyl ether/n-hexane mixed antisolvent (MAS) was used to achieve high nucleation density and slow down the formation process of perovskite, producing films with improved orientation of grains and ultrasmooth surfaces. These high quality films exhibited efficient charge transport at the interface of perovskite/hole transport material and perovskite solar cells based on these films showed greatly improved performance with the best power conversion efficiency of 17.08%. This work also proposed a selection principle of MAS and showed that solvent engineering by designing the mixed antisolvent system can lead to the fabrication of high-performance perovskite solar cells.

The Effects of a Brief Acceptance-based Behavior Therapy vs. Traditional Cognitive Behavior Therapy for Public Speaking Anxiety: Differential Effects on Performance and Verbal Working Memory

NASA Astrophysics Data System (ADS)

Glassman, Lisa Hayley

Individuals with public speaking phobia experience fear and avoidance that can cause extreme distress, impaired speaking performance, and associated problems in psychosocial functioning. Most extant interventions for public speaking phobia focus on the reduction of anxiety and avoidance, but neglect performance. Additionally, very little is known about the relationship between verbal working memory and social performance under conditions of high anxiety. The current study compared the efficacy of two cognitive behavioral treatments, traditional Cognitive Behavioral Therapy (tCBT) and acceptance-based behavior therapy (ABBT), in enhancing public speaking performance via coping with anxiety. Verbal working memory performance, as measured by the backwards digit span (BDS), was measured to explore the relationships between treatment type, anxiety, performance, and verbal working memory. We randomized 30 individuals with high public speaking anxiety to a 90-minute ABBT or tCBT intervention. As this pilot study was underpowered, results are examined in terms of effect sizes as well as statistical significance. Assessments took place at pre and post-intervention and included self-rated and objective anxiety measurements, a behavioral assessment, ABBT and tCBT process measures, and backwards digit span verbal working memory tests. In order to examine verbal working memory during different levels of anxiety and performance pressure, we gave each participant a backwards digit span task three times during each assessment: once under calm conditions, then again while experiencing anticipatory anxiety, and finally under conditions of acute social performance anxiety in front of an audience. Participants were asked to give a video-recorded speech in front of the audience at pre- and post-intervention to examine speech performance. Results indicated that all participants experienced a very large and statistically significant decrease in anxiety (both during the speech and BDS), as well as an improvement in speech performance regardless of intervention received. While not statistically significant, participants who received an acceptance-based intervention exhibited larger improvements in observer-rated speech performance at post-treatment in comparison to tCBT (F (1,21) = 1.91, p =.18, etap2 = .08) such that individuals in the ABBT condition exhibited a considerably greater improvement in observer-rated speech performance than those in the tCBT condition. There was no differential impact of treatment condition on subjective speech anxiety or working memory task performance. Potential mediators and moderators of treatment were also examined. Results provide support for a brief 90-minute intervention for public speaking anxiety, but more research is needed in a study with a larger sample to fully understand the relationship between ABBT strategies and improvements in behavioral performance.

Acute exercise performed close to the anaerobic threshold improves cognitive performance in elderly females.

PubMed

Córdova, C; Silva, V C; Moraes, C F; Simões, H G; Nóbrega, O T

2009-05-01

The objective of the present study was to compare the effect of acute exercise performed at different intensities in relation to the anaerobic threshold (AT) on abilities requiring control of executive functions or alertness in physically active elderly females. Forty-eight physically active elderly females (63.8 +/- 4.6 years old) were assigned to one of four groups by drawing lots: control group without exercise or trial groups with exercise performed at 60, 90, or 110% of AT (watts) and submitted to 5 cognitive tests before and after exercise. Following cognitive pretesting, an incremental cycle ergometer test was conducted to determine AT using a fixed blood lactate concentration of 3.5 mmol/L as cutoff. Acute exercise executed at 90% of AT resulted in significant (P < 0.05, ANOVA) improvement in the performance of executive functions when compared to control in 3 of 5 tests (verbal fluency, Tower of Hanoi test (number of movements), and Trail Making test B). Exercising at 60% of AT did not improve results of any tests for executive functions, whereas exercise executed at 110% of AT only improved the performance in one of these tests (verbal fluency) compared to control. Women from all trial groups exhibited a remarkable reduction in the Simple Response Time (alertness) test (P = 0.001). Thus, physical exercise performed close to AT is more effective to improve cognitive processing of older women even if conducted acutely, and using a customized exercise prescription based on the anaerobic threshold should optimize the beneficial effects.

A Novel Strategy of Ambiguity Correction for the Improved Faraday Rotation Estimator in Linearly Full-Polarimetric SAR Data.

PubMed

Li, Jinhui; Ji, Yifei; Zhang, Yongsheng; Zhang, Qilei; Huang, Haifeng; Dong, Zhen

2018-04-10

Spaceborne synthetic aperture radar (SAR) missions operating at low frequencies, such as L-band or P-band, are significantly influenced by the ionosphere. As one of the serious ionosphere effects, Faraday rotation (FR) is a remarkable distortion source for the polarimetric SAR (PolSAR) application. Various published FR estimators along with an improved one have been introduced to solve this issue, all of which are implemented by processing a set of PolSAR real data. The improved estimator exhibits optimal robustness based on performance analysis, especially in term of the system noise. However, all published estimators, including the improved estimator, suffer from a potential FR angle (FRA) ambiguity. A novel strategy of the ambiguity correction for those FR estimators is proposed and shown as a flow process, which is divided into pixel-level and image-level correction. The former is not yet recognized and thus is considered in particular. Finally, the validation experiments show a prominent performance of the proposed strategy.

Effects of Nanoimprinted Structures on the Performance of Organic Solar Cells

DOE PAGES

Gill, Hardeep Singh; Li, Lian; Ren, Haizhou; ...

2018-01-01

The effect of nanoimprinted structures on the performance of organic bulk heterojunction solar cells was investigated. The nanostructures were formed over the active layer employing the soft lithographic technique. The measured incident photon-to-current efficiency revealed that the nanostructured morphology over the active layer can efficiently enhance both light harvesting and charge carrier collection due to improvement of the absorption of incident light and the buried nanostructured cathode, respectively. The devices prepared with the imprinted nanostructures exhibited significantly higher power conversion efficiencies as compared to those of the control cells.

Effects of Nanoimprinted Structures on the Performance of Organic Solar Cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gill, Hardeep Singh; Li, Lian; Ren, Haizhou

The effect of nanoimprinted structures on the performance of organic bulk heterojunction solar cells was investigated. The nanostructures were formed over the active layer employing the soft lithographic technique. The measured incident photon-to-current efficiency revealed that the nanostructured morphology over the active layer can efficiently enhance both light harvesting and charge carrier collection due to improvement of the absorption of incident light and the buried nanostructured cathode, respectively. The devices prepared with the imprinted nanostructures exhibited significantly higher power conversion efficiencies as compared to those of the control cells.

Engineering the internal surfaces of three-dimensional nanoporous catalysts by surfactant-modified dealloying.

PubMed

Wang, Zhili; Liu, Pan; Han, Jiuhui; Cheng, Chun; Ning, Shoucong; Hirata, Akihiko; Fujita, Takeshi; Chen, Mingwei

2017-10-20

Tuning surface structures by bottom-up synthesis has been demonstrated as an effective strategy to improve the catalytic performances of nanoparticle catalysts. Nevertheless, the surface modification of three-dimensional nanoporous metals, fabricated by a top-down dealloying approach, has not been achieved despite great efforts devoted to improving the catalytic performance of three-dimensional nanoporous catalysts. Here we report a surfactant-modified dealloying method to tailor the surface structure of nanoporous gold for amplified electrocatalysis toward methanol oxidation and oxygen reduction reactions. With the assistance of surfactants, {111} or {100} faceted internal surfaces of nanoporous gold can be realized in a controllable manner by optimizing dealloying conditions. The surface modified nanoporous gold exhibits significantly enhanced electrocatalytic activities in comparison with conventional nanoporous gold. This study paves the way to develop high-performance three-dimensional nanoporous catalysts with a tunable surface structure by top-down dealloying for efficient chemical and electrochemical reactions.

CuI as Hole-Transport Channel for Enhancing Photoelectrocatalytic Activity by Constructing CuI/BiOI Heterojunction.

PubMed

Sun, Mingjuan; Hu, Jiayue; Zhai, Chunyang; Zhu, Mingshan; Pan, Jianguo

2017-04-19

In this paper, CuI, as a typical hole-transport channel, was used to construct a high-performance visible-light-driven CuI/BiOI heterostructure for photoelectrocatalytic applications. The heterostructure combines the broad visible absorption of BiOI and high hole mobility of CuI. Compared to pure BiOI, the CuI/BiOI heterostructure exhibited distinctly enhanced photoelectrocatalytic performance for the oxidation of methanol and organic pollutants under visible-light irradiation. The photogenerated electron-hole pairs of the excited BiOI can be separated efficiently through CuI, in which the CuI acts as a superior hole-transport channel to improve photoelectrocatalytic oxidization of methanol and organic pollutants. The outstanding photoelectrocatalytic activity shows that the p-type CuI works as a promising hole-transport channel to improve the photocatalytic performance of traditional semiconductors.

Improved battery performance using Pd nanoparticles synthesized on the surface of LiFePO4/C by ultrasound irradiation

NASA Astrophysics Data System (ADS)

Saliman, Muhammad Ali; Okawa, Hirokazu; Takai, Misaki; Ono, Yuki; Kato, Takahiro; Sugawara, Katsuyasu; Sato, Mineo

2016-07-01

LiFePO4 has been attracting interest as a cathode material for Li-ion batteries due to its high energy density, low cost, and eco-friendliness. The electrochemical performance of LiFePO4 is limited because it exhibits low Li-ion diffusivity and low electronic conductivity. Numerous solutions have been considered, such as carbon coating, which is widely known to improve the electronic conductivity of LiFePO4. The deposition of metal nanoparticles (NPs) on the surface of carbon-coated LiFePO4 further enhances the electronic conductivity. In this study, we deposited Pd NPs onto the surface of LiFePO4/C and investigated the resulting electrochemical performance. Sonochemical synthesis was used to prepare the metal NPs; the procedure did not require any surfactants and the reaction was rapid.

Transparent and Self-Supporting Graphene Films with Wrinkled- Graphene-Wall-Assembled Opening Polyhedron Building Blocks for High Performance Flexible/Transparent Supercapacitors.

PubMed

Li, Na; Huang, Xuankai; Zhang, Haiyan; Li, Yunyong; Wang, Chengxin

2017-03-22

Improving mass loading while maintaining high transparency and large surface area in one self-supporting graphene film is still a challenge. Unfortunately, all of these factors are absolutely essential for enhancing the energy storage performance of transparent supercapacitors for practical applications. To solve the above bottleneck problem, we produce a novel self-supporting flexible and transparent graphene film (STF-GF) with wrinkled-wall-assembled opened-hollow polyhedron building units. Taking advantage of the microscopic morphology, the STF-GF exhibits improved mass loading with high transmittance (70.2% at 550 nm), a large surface area (1105.6 m 2 /g), and good electrochemical performance: high energy (552.3 μWh/cm 3 ), power densities (561.9 mW/cm 3 ), a superlong cycle life, and good cycling stability (the capacitance retention is ∼94.8% after 20,000 cycles).

Ni-doped TiO2 nanotubes photoanode for enhanced photoelectrochemical water splitting

NASA Astrophysics Data System (ADS)

Dong, Zhenbiao; Ding, Dongyan; Li, Ting; Ning, Congqin

2018-06-01

Photoelectrochemical (PEC) water splitting hydrogen production provides a promising way for sustainable development. In this work, we prepared Ni-doped TiO2 (Ti-Ni-O) nanotubes through anodizing different Ti-Ni alloys and further annealing them at elevated temperatures, and reported their PEC water splitting performance. It was found that Ni doping could improve light absorption and facilitate separation of photo-excited electron-hole pair. The nanotubes fabricated on Ti-1 wt.% Ni alloy and annealed at 550 °C exhibited better PEC water splitting performance than those on Ti-10 wt.% Ni alloy. The photoconversion efficiency was 0.67%, which was 3.35 times the photoconversion efficiency of undoped TiO2. It demonstrated that it was feasible to fabricate high-performance Ti-Ni-O nanotubes on Ti-Ni alloys and used as photoanode for improving PEC water splitting.

Growing and testing mycelium bricks as building insulation materials

NASA Astrophysics Data System (ADS)

Xing, Yangang; Brewer, Matthew; El-Gharabawy, Hoda; Griffith, Gareth; Jones, Phil

2018-02-01

In order to improve energy performance of buildings, insulation materials (such as mineral glass and rock wools, or fossil fuel-based plastic foams) are being used in increasing quantities, which may lead to potential problem with materials depletions and landfill disposal. One sustainable solution suggested is the use of bio-based, biodegradable materials. A number of attempts have been made to develop biomaterials, such as sheep wood, hemcrete or recycled papers. In this paper, a novel type of bio insulation materials - mycelium is examined. The aim is to produce mycelium materials that could be used as insulations. The bio-based material was required to have properties that matched existing alternatives, such as expanded polystyrene, in terms of physical and mechanical characteristics but with an enhanced level of biodegradability. The testing data showed mycelium bricks exhibited good thermal performance. Future work is planned to improve growing process and thermal performance of the mycelium bricks.

Carotid Artery Stenting – Strategies to Improve Procedural Performance and Reduce the Learning Curve

PubMed Central

Van Herzeele, Isabelle

2013-01-01

Carotid artery stenting (CAS) remains an appealing intervention to reduce the stroke risk because of its minimal invasive nature. Nevertheless, landmark randomised controlled trials have not been able to resolve the controversies surrounding this complex procedure as the peri-operative stroke risk in a non-selected patient population still seems to be higher after CAS in comparison to carotid endarterectomy. What is more, these trials have highlighted that patient outcome after CAS is influenced by patient- and operator-dependant factors. The CAS procedure exhibits a definitive learning curve resulting in higher complication rates if the procedure is performed by inexperienced interventionists or in low-volume centres. This article will outline strategies to improve the performance of physicians carrying out the CAS procedure by means of proficiency-based training, credentialing, virtual reality rehearsal and optimal patient selection. PMID:29588751

Nanostructured aligned CNT platforms enhance the controlled release of a neurotrophic protein from polypyrrole

NASA Astrophysics Data System (ADS)

Thompson, Brianna C.; Chen, Jun; Moulton, Simon E.; Wallace, Gordon G.

2010-04-01

An aligned CNT array membrane electrode has been used as a nanostructured supporting platform for polypyrrole (PPy) films, exhibiting significant improvement in the controlled release of neurotrophin. In terms of linearity of release, stimulated to unstimulated control of NT-3 release and increased mass and % release of incorporated NT-3, the nanostructured material performed more favourably than the flat PPy film.

Longitudinal Development of Manual Motor Ability in Autism Spectrum Disorder from Childhood to Mid-Adulthood Relates to Adaptive Daily Living Skills

ERIC Educational Resources Information Center

Travers, Brittany G.; Bigler, Erin D.; Duffield, Tyler C.; Prigge, Molly D. B.; Froehlich, Alyson L.; Lange, Nicholas; Alexander, Andrew L.; Lainhart, Janet E.

2017-01-01

Many individuals with autism spectrum disorder (ASD) exhibit motor difficulties, but it is unknown whether manual motor skills improve, plateau, or decline in ASD in the transition from childhood into adulthood. Atypical development of manual motor skills could impact the ability to learn and perform daily activities across the life span. This…

Effects of leg dominance on performance of ballet turns (pirouettes) by experienced and novice dancers.

PubMed

Lin, Chia-Wei; Su, Fong-Chin; Wu, Hong-Wen; Lin, Cheng-Feng

2013-01-01

Turns (pirouettes) are an important movement in ballet and may be affected by "lateral bias". This study investigated physiological differences exhibited by experienced and novice dancers, respectively, when performing pirouette with dominant and non-dominant leg supports, respectively. Thirteen novice and 13 experienced dancers performed turns on dominant or non-dominant legs. The maximum ankle plantarflexion, knee extension and hip extension were measured during the single-leg support phase. The inclination angle of rotation axis is the angle between instantaneous rotation axis and global vertical axis in the early single-leg support phase. Both groups exhibited a greater hip extension, knee extension, and ankle plantarflexion when performing a turn on the non-dominant leg. For experienced dancers, the inclination angle of rotation axis during the pre-swing phase was generally smaller for dominant leg support than non-dominant leg. However, no significant difference was found in inclination angle of rotation axis of novice dancers. For experienced dancers, an improved performance is obtained when using the dominant leg for support. By contrast, for novice dancers, the performance is independent of choice of support leg. The significant lateral bias in experienced dancers indicates the possible influence of training. That is, repetitive rehearsal on the preferred leg strengthens the impact of side dominance in experienced dancers.

Interface-designed Membranes with Shape-controlled Patterns for High-performance Polymer Electrolyte Membrane Fuel Cells

NASA Astrophysics Data System (ADS)

Jeon, Yukwon; Kim, Dong Jun; Koh, Jong Kwan; Ji, Yunseong; Kim, Jong Hak; Shul, Yong-Gun

2015-11-01

Polymer electrolyte membrane fuel cell is a promising zero-emission power generator for stationary/automotive applications. However, key issues, such as performance and costs, are still remained for an economical commercialization. Here, we fabricated a high-performance membrane electrode assembly (MEA) using an interfacial design based on well-arrayed micro-patterned membranes including circles, squares and hexagons with different sizes, which are produced by a facile elastomeric mold method. The best MEA performance is achieved using patterned Nafion membrane with a circle 2 μm in size, which exhibited a very high power density of 1906 mW/cm2 at 75 °C and Pt loading of 0.4 mg/cm2 with 73% improvement compared to the commercial membrane. The improved performance are attributed to the decreased MEA resistances and increased surface area for higher Pt utilization of over 80%. From these enhanced properties, it is possible to operate at lower Pt loading of 0.2 mg/cm2 with an outstanding performance of 1555 mW/cm2 and even at air/low humidity operations.

Thermoelectric properties by high temperature annealing

NASA Technical Reports Server (NTRS)

Chen, Gang (Inventor); Kumar, Shankar (Inventor); Ren, Zhifeng (Inventor); Lee, Hohyun (Inventor)

2009-01-01

The present invention generally provides methods of improving thermoelectric properties of alloys by subjecting them to one or more high temperature annealing steps, performed at temperatures at which the alloys exhibit a mixed solid/liquid phase, followed by cooling steps. For example, in one aspect, such a method of the invention can include subjecting an alloy sample to a temperature that is sufficiently elevated to cause partial melting of at least some of the grains. The sample can then be cooled so as to solidify the melted grain portions such that each solidified grain portion exhibits an average chemical composition, characterized by a relative concentration of elements forming the alloy, that is different than that of the remainder of the grain.

Fuzzy control of a fluidized bed dryer

DOE Office of Scientific and Technical Information (OSTI.GOV)

Taprantzis, A.V.; Siettos, C.I.; Bafas, G.V.

1997-05-01

Fluidized bed dryers are utilized in almost every area of drying applications and therefore improved control strategies are always of great interest. The nonlinear character of the process, exhibited in the mathematical model and the open loop analysis, implies that a fuzzy logic controller is appropriate because, in contrast with conventional control schemes, fuzzy control inherently compensates for process nonlinearities and exhibits more robust behavior. In this study, a fuzzy logic controller is proposed; its design is based on a heuristic approach and its performance is compared against a conventional PI controller for a variety of responses. It is shownmore » that the fuzzy controller exhibits a remarkable dynamic behavior, equivalent if not better than the PI controller, for a wide range of disturbances. In addition, the proposed fuzzy controller seems to be less sensitive to the nonlinearities of the process, achieves energy savings and enables MIMO control.« less

Calcium metaborate as a cathode additive to improve the high-temperature properties of nickel hydroxide electrodes for nickel-metal hydride batteries

NASA Astrophysics Data System (ADS)

Li, Jing; Shangguan, Enbo; Guo, Dan; Li, Quanmin; Chang, Zhaorong; Yuan, Xiao-Zi; Wang, Haijiang

2014-10-01

In this paper, a novel additive, calcium metaborate (CMB), is proposed to improve the high-temperature characteristics of the nickel electrodes for nickel-metal hydride batteries. As a soluble calcium salt, CMB can easily and uniformly be dispersed in the nickel electrodes. The effects of CMB on the nickel electrode are investigated via a combination of cyclability, capacity retention, electrochemical impedance spectroscopy, scanning electron microscope and X-ray diffraction. Compared with conventional nickel electrodes, the electrode containing 0.5 wt.% CMB exhibits superior electrode properties including enhanced discharge capacity, improved high-rate discharge ability and excellent cycle stability at an elevated temperature (70 °C). The improved cell performance of the nickel electrode containing CMB additives can be attributable to the increased oxygen evolution overvoltage and slower oxygen evolution rate. Compared with insoluble calcium salts, such as Ca(OH)2, CaCO3, and CaF2, CMB is more effective as a cathode additive to improve the high-temperature performance of Ni-MH batteries.

Study of the use of truck tire beads as drainage pipe and analysis of the economics of tire disposal in Oklahoma. Part 1. Culverts. Final report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Everett, J.W.; Gattis, J.L.

1994-07-01

In an attempt to find alternate ways of dealing with waste truck tires, a private tire recycling company developed a pipe from the tire bead and sidewall. The tire-pipe has seen limited use as a roadway drainage culvert. To encourage wider use of this product, an evaluation of pipe performance was performed. The evaluation consisted of (1) inspections of existing installations; (2) structural tests; and (3) leakage tests. The study found that the majority of installations were performing well. Compared with corrugated steel and fiberglass pipes, the tire-pipe exhibited favorable structural performance. An individual tire-pipe section was found to bemore » watertight. However, when tested in the open-air (not in the ground), the tire-pipe joints were found to leak. Development of an improved end connection would improve the utility of the tire-pipe.« less

Reach performance while wearing the Space Shuttle launch and entry suit during exposure to launch accelerations

NASA Technical Reports Server (NTRS)

Bagian, James P.; Greenisen, M. C.; Schafer, L. E.; Probe, J. D.; Krutz, Robert W., Jr.

1990-01-01

A crew of four veteran astronaut/pilots were subjected to sustained linear accelerations of up to 3G(x) in order to quantify crew reach performance while wearing the currently used Launch and Entry Suit (LES). Photogrammetric techniques were used to quantify magnitudes of reach in any direction while subjects rode a centrifuge. Subjects exhibited small changes of reach capability in the +x (forward) direction which ranged from an improvement of 2.04 cm to a decrease of 14.4 cm while reach performance in the +z (overhead) direction was improved in three of four subjects, indicating that any task which could be accomplished under exposure to 1G(x) could definitely be done at 3G(x). The data from this experiment demonstrated that Shuttle crews in training can expect to maintain all of the overhead reach capability evident in good simulator runs and suffer only moderate degradation in the forward reach performance during the launch phase of an actual Shuttle mission.

Improving the performance of lithium-sulfur batteries by graphene coating

NASA Astrophysics Data System (ADS)

Zhou, Xiangyang; Xie, Jing; Yang, Juan; Zou, Youlan; Tang, Jingjing; Wang, Songcan; Ma, Lulu; Liao, Qunchao

2013-12-01

A graphene coating mesoporous carbon/sulfur (RGO@CMK-3/S) composite, which is characteristic of a hybrid structure by incorporating the merits of CMK-3 matrix and graphene (RGO) skin, is synthesized by a facile and scalable route. The CMK-3/S composite is synthesized via a simple melt-diffusion strategy, and then a thin RGO skin is absorbed on the CMK-3/S composite surface in aqueous solution. When evaluating the electrochemical properties of as-prepared RGO wrapped nanostructures as cathode materials in lithium-sulfur batteries, it exhibits much improved cyclical stability and high rate performance. The RGO@CMK-3/S composite with 53.14 wt.% sulfur presents a reversible discharge capacity of about 734 mA h g-1 after 100 cycles at 0.5 C. The improved performance is attributed to the unique structure of RGO@CMK-3/S composite. CMK-3 with extensively mesopores can offer buffering space for the volume change of sulfur and efficient diffusion channel for lithium ions during the charge/discharge process. Meanwhile, the conductive RGO coating skin physically and chemically prevents the dissolution of polysulfides from the cathode, both of which contribute to the reduced capacity fade and improved electrochemical properties.

Advances in rubber/halloysite nanotubes nanocomposites.

PubMed

Jia, Zhixin; Guo, Baochun; Jia, Demin

2014-02-01

The research advances in rubber/halloysite nanotubes (rubber/HNTs) nanocomposites are reviewed. HNTs are environmentally-friendly natural nanomaterials, which could be used to prepare the rubber-based nanocomposites with high performance and low cost. Unmodified HNTs could be adopted to prepare the rubber/HNTs composites with improved mechanical properties, however, the rubber/HNTs nanocomposites with fine morphology and excellent properties were chiefly prepared with various modifiers by in situ mixing method. A series of rubber/HNTs nanocomposites containing several rubbers (SBR, NR, xSBR, NBR, PU) and different modifiers (ENR, RH, Si69, SA, MAA, ILs) have been investigated. The results showed that all the rubber/HNTs nanocomposites achieved strong interfacial interaction via interfacial covalent bonds, hydrogen bonds or multiple interactions, realized significantly improved dispersion of HNTs at nanoscale and exhibited excellent mechanical performances and other properties.

Effects of Graphene Monolayer Coating on the Optical Performance of Remote Phosphors

NASA Astrophysics Data System (ADS)

Yazdan Mehr, M.; Volgbert, S.; van Driel, W. D.; Zhang, G. Q.

2017-10-01

A graphene monolayer has been successfully coated on one side of a bisphenol-A-polycarbonate (BPA-PC) plate, used as a substrate for remote phosphor applications in light-emitting diode (LED)-based products. Using a photoresist transferring method, graphene sheet has been coated on BPA-PC plates. The results show that this graphene monolayer significantly improves the lifetime and performance of LEDs mainly by protecting them against external degradation factors such as moisture and oxygen. Also, LED-based products composed of graphene-coated BPA-PC plates exhibit longer stability with comparatively less loss of luminous efficiency. This method has great potential to significantly improve the reliability of not only LED-based products but also many other microelectronics packaging and components, in which moisture and oxygen are the key causes of failures.

Fabrication and Characteristics of Al/PTFE Multilayers and Application in Micro-initiator

NASA Astrophysics Data System (ADS)

Zhang, Yuxin; Jiang, Hongchuan; Zhao, Xiaohui; Zhang, Wanli; Li, Yanrong

2017-12-01

In this paper, a micro-initiator was designed and fabricated by integrating Al/PTFE multilayers with a Cu film bridge. The regularity layer structure and interface composition of Al/PTFE multilayers was analysed by transmission electron microscope and X-ray photoelectron spectroscopy, respectively. The heat release reaction in Al/PTFE multilayers can be triggered with reaction temperature of 430 °C, and the overall heat of reaction is 3192 J/g. Al/PTFE multilayers with bilayer thickness of 200 nm was alternately deposited on a Cu film bridge to improve the electric explosion performances. Compared to Cu film bridge, the Al/PTFE/Cu integrated film bridge exhibits improved performances with longer explosion duration time, more violent explosion phenomenon and larger quantities of ejected product particles.

An Improved Method for Determination of Cyanide Content in Bitter Almond Oil.

PubMed

Chen, Jia; Liu, Lei; Li, Mengjun; Yu, Xiuzhu; Zhang, Rui

2018-01-01

An improved colorimetric method for determination of cyanide content in bitter almond oil was developed. The optimal determination parameters were as follows: volume ratio of hydrochloric acid to bitter almond oil (v/v), 1.5:1; holding time for hydrolysis, 120 min; and volume ratio of distillation solution to bitter almond oil (v/v), 8:1. Analytical results showed that the relative standard deviations (SDs) of determinations were less than 10%, which satisfies the test requirements. The results of high-performance liquid chromatography and measurements exhibited a significant correlation (R = 0.9888, SD = 0.2015). Therefore, the improved colorimetric method can be used to determine cyanide content in bitter almond oil.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Peifu; Shi, Penghui, E-mail: shipenghui@shiep.edu.cn; Hong, Yuanchen

Graphical abstract: The photocatalytic performance of Ag{sub 3}PO{sub 4} was highly improved by the in situ deposition of Ag{sub 3}PO{sub 4} particles on graphene-like MoS{sub 2} nanosheets. - Highlights: • A novel composite photocatalyst was synthesized by depositing Ag{sub 3}PO{sub 4} on the graphene-like MoS{sub 2} nanosheets. • Ag{sub 3}PO{sub 4}/MoS{sub 2} photocatalyst exhibited a high photocatalytic activity for RhB degradation. • Graphene-like MoS{sub 2} nanosheets. • MoS{sub 2} nanosheets play an important role in photocatalytic activity by serving as an effective acceptor of the photogenerated carriers. - Abstract: A facile method for the in situ deposition of Ag{sub 3}PO{submore » 4} on graphene-like MoS{sub 2} nanosheets was developed to improve the photocatalytic performance of Ag{sub 3}PO{sub 4} catalysts. The heterostructure of Ag{sub 3}PO{sub 4}/MoS{sub 2} composites was characterized by using X-ray diffraction spectra (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS). The prepared Ag{sub 3}PO{sub 4}/MoS{sub 2} photocatalyst exhibited a much higher photocatalytic activity than that of Ag{sub 3}PO{sub 4} for the degradation of Rhodamine B (RhB) under visible light irradiation (>400 nm). The improved photocatalytic activity of Ag{sub 3}PO{sub 4}/MoS{sub 2} is attributed to the efficient separation of photogenerated electron–hole pairs in the composite. This result provides a new perspective on the design of high-performance photocatalysts which is promising for energy applications.« less

Emotion self-regulation, psychophysiological coherence, and test anxiety: results from an experiment using electrophysiological measures.

PubMed

Bradley, Raymond Trevor; McCraty, Rollin; Atkinson, Mike; Tomasino, Dana; Daugherty, Alane; Arguelles, Lourdes

2010-12-01

This study investigated the effects of a novel, classroom-based emotion self-regulation program (TestEdge) on measures of test anxiety, socioemotional function, test performance, and heart rate variability (HRV) in high school students. The program teaches students how to self-generate a specific psychophysiological state--psychophysiological coherence--which has been shown to improve nervous system function, emotional stability, and cognitive performance. Implemented as part of a larger study investigating the population of tenth grade students in two California high schools (N = 980), the research reported here was conducted as a controlled pre- and post-intervention laboratory experiment, using electrophysiological measures, on a random stratified sample of students from the intervention and control schools (N = 136). The Stroop color-word conflict test was used as the experiment's stimulus to simulate the stress of taking a high-stakes test, while continuous HRV recordings were gathered. The post-intervention electrophysiological results showed a pattern of improvement across all HRV measures, indicating that students who received the intervention program had learned how to better manage their emotions and to self-activate the psychophysiological coherence state under stressful conditions. Moreover, students with high test anxiety exhibited increased HRV and heart rhythm coherence even during a resting baseline condition (without conscious use of the program's techniques), suggesting that they had internalized the benefits of the intervention. Consistent with these results, students exhibited reduced test anxiety and reduced negative affect after the intervention. Finally, there is suggestive evidence from a matched-pairs analysis that reduced test anxiety and increased psychophysiological coherence appear to be directly associated with improved test performance--a finding consistent with evidence from the larger study.

Fabrication of β-CoV3O8 nanorods embedded in graphene sheets and their application for electrochemical charge storage electrode

NASA Astrophysics Data System (ADS)

Jeong, Gyoung Hwa; Lee, Ilbok; Lee, Donghyun; Lee, Hea-Min; Baek, Seungmin; Kwon, O.-Pil; Kumta, Prashant N.; Yoon, Songhun; Kim, Sang-Wook

2018-05-01

The fabrication of β-CoV3O8 nanorods embedded in graphene sheets and their application as electrochemical charge storage electrodes is reported. From the surfactant treatment of raw graphite, graphene was directly prepared and its nanocomposite with β-CoV3O8 nanorods distributed between graphene layers (β-CoV3O8-G) was synthesized by a hydrothermal method. When applied as an anode in lithium-ion batteries, the β-CoV3O8-G anode exhibits greatly improved charge and discharge capacities of 790 and 627 mAh · g-1, respectively, with unexpectedly high initial efficiency of 82%. The observed discharge capacity reflected that at least 3.7 mol of Li+ is selectively accumulated within the β-CoV3O8 phase (LixCoV3O8, x > 3.7), indicative of significantly improved Li+ uptake when compared with aggregated β-CoV3O8 nanorods. Moreover, very distinct peak plateaus and greatly advanced cycling performance are observed, showing more improved Li+ storage within the β-CoV3O8 phase. As a supercapacitor electrode, moreover, our composite electrode exhibits very high peak pseudocapacitances of 2.71 F · cm-2 and 433.65 F · g-1 in the β-CoV3O8 phase with extremely stable cycling performance. This remarkably enhanced performance in the individual electrochemical charge storage electrodes is attributed to the novel phase formation of β-CoV3O8 and its optimized nanocomposite structure with graphene, which yield fast electrical conduction through graphene, easy accessibility of ions through the open multilayer nanosheet structure, and a relaxation space between the β-CoV3O8-G.

Synthesis and characterization of sulfur–carbon–vanadium pentoxide composites for improved electrochemical properties of lithium–sulfur batteries

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kong, Long; Handa, Yusuke; Taniguchi, Izumi, E-mail: taniguchi.i.aa@m.titech.ac.jp

2016-01-15

Highlights: • A wet ball milling was conducted to synthesis S–C–V{sub 2}O{sub 5} composite electrode. • V{sub 2}O{sub 5} additive led to further improve electrochemical performance of S-cathode. • S–C–V{sub 2}O{sub 5} composite electrode exhibited a first discharge capacity of 951 mAh g{sup −1}. • The electrode (60 wt.%—S, 30 wt.%—V{sub 2}O{sub 5}, 10 wt.%—C) showed best battery performance. - Abstract: Sulfur (S)–carbon (C)–vanadium pentoxide (V{sub 2}O{sub 5}) composites were prepared by wet ball milling, and their physical and electrochemical properties were evaluated. Firstly, the effect of the carbon content of S–C composite electrodes on their physical and electrochemical propertiesmore » was investigated. The S–C composite electrode with 60 wt.% S delivers a first discharge capacity of 1077 mAh g{sup −1}. However, its capacity markedly decreases to 606 mAh g{sup −1} after 10 cycles, which corresponds to a capacity fading rate of 47 mAh g{sup −1} per cycle. To improve the electrochemical performance of the S–C composite electrode, carbon was partially replaced by V{sub 2}O{sub 5}. The S–C–V{sub 2}O{sub 5} composite electrode with a composition of 60 wt.%—S, 30 wt.%—V{sub 2}O{sub 5} and 10 wt.%—C exhibits a lower capacity fading rate of 23 mAh g{sup −1} per cycle in the first 10 cycles and better capacity retention than the S–C composite electrode over 50 cycles.« less

Temporal lobe structures and facial emotion recognition in schizophrenia patients and nonpsychotic relatives.

PubMed

Goghari, Vina M; Macdonald, Angus W; Sponheim, Scott R

2011-11-01

Temporal lobe abnormalities and emotion recognition deficits are prominent features of schizophrenia and appear related to the diathesis of the disorder. This study investigated whether temporal lobe structural abnormalities were associated with facial emotion recognition deficits in schizophrenia and related to genetic liability for the disorder. Twenty-seven schizophrenia patients, 23 biological family members, and 36 controls participated. Several temporal lobe regions (fusiform, superior temporal, middle temporal, amygdala, and hippocampus) previously associated with face recognition in normative samples and found to be abnormal in schizophrenia were evaluated using volumetric analyses. Participants completed a facial emotion recognition task and an age recognition control task under time-limited and self-paced conditions. Temporal lobe volumes were tested for associations with task performance. Group status explained 23% of the variance in temporal lobe volume. Left fusiform gray matter volume was decreased by 11% in patients and 7% in relatives compared with controls. Schizophrenia patients additionally exhibited smaller hippocampal and middle temporal volumes. Patients were unable to improve facial emotion recognition performance with unlimited time to make a judgment but were able to improve age recognition performance. Patients additionally showed a relationship between reduced temporal lobe gray matter and poor facial emotion recognition. For the middle temporal lobe region, the relationship between greater volume and better task performance was specific to facial emotion recognition and not age recognition. Because schizophrenia patients exhibited a specific deficit in emotion recognition not attributable to a generalized impairment in face perception, impaired emotion recognition may serve as a target for interventions.

Ultrathin nickel hydroxide on carbon coated 3D-porous copper structures for high performance supercapacitors.

PubMed

Kang, Kyeong-Nam; Kim, Ik-Hee; Ramadoss, Ananthakumar; Kim, Sun-I; Yoon, Jong-Chul; Jang, Ji-Hyun

2018-01-03

An ultrathin nickel hydroxide layer electrodeposited on a carbon-coated three-dimensional porous copper structure (3D-C/Cu) is suggested as an additive and binder-free conductive electrode with short electron path distances, large electrochemical active sites, and improved structural stability, for high performance supercapacitors. The 3D-porous copper structure (3D-Cu) provides high electrical conductivity and facilitates electron transport between the Ni(OH) 2 active materials and the current collector of the Ni-plate. A carbon coating was applied to the 3D-Cu to prevent the oxidation of Cu, without degrading the electron transport behavior of the 3D-Cu. The 3D-Ni(OH) 2 /C/Cu exhibited a high specific capacitance of 1860 F g -1 at 1 A g -1 , and good cycling performance, with an 86.5% capacitance retention after 10 000 cycles. When tested in a two-electrode system, an asymmetric supercapacitor exhibited an energy density of 147.9 W h kg -1 and a power density of 37.0 kW kg -1 . These results open a new area of ultrahigh-performance supercapacitors, supported by 3D-Cu electrodes.

3D hierarchical assembly of ultrathin MnO2 nanoflakes on silicon nanowires for high performance micro-supercapacitors in Li- doped ionic liquid

PubMed Central

Dubal, Deepak P.; Aradilla, David; Bidan, Gérard; Gentile, Pascal; Schubert, Thomas J.S.; Wimberg, Jan; Sadki, Saïd; Gomez-Romero, Pedro

2015-01-01

Building of hierarchical core-shell hetero-structures is currently the subject of intensive research in the electrochemical field owing to its potential for making improved electrodes for high-performance micro-supercapacitors. Here we report a novel architecture design of hierarchical MnO2@silicon nanowires (MnO2@SiNWs) hetero-structures directly supported onto silicon wafer coupled with Li-ion doped 1-Methyl-1-propylpyrrolidinium bis(trifluromethylsulfonyl)imide (PMPyrrBTA) ionic liquids as electrolyte for micro-supercapacitors. A unique 3D mesoporous MnO2@SiNWs in Li-ion doped IL electrolyte can be cycled reversibly across a voltage of 2.2 V and exhibits a high areal capacitance of 13 mFcm−2. The high conductivity of the SiNWs arrays combined with the large surface area of ultrathin MnO2 nanoflakes are responsible for the remarkable performance of these MnO2@SiNWs hetero-structures which exhibit high energy density and excellent cycling stability. This combination of hybrid electrode and hybrid electrolyte opens up a novel avenue to design electrode materials for high-performance micro-supercapacitors. PMID:25985388

Nanostructure selenium compounds as pseudocapacitive electrodes for high-performance asymmetric supercapacitor.

PubMed

Ma, Guofu; Hua, Fengting; Sun, Kanjun; Fenga, Enke; Peng, Hui; Zhang, Zhiguo; Lei, Ziqiang

2018-01-01

The electrochemical performance of an energy conversion and storage device like the supercapacitor mainly depends on the microstructure and morphology of the electrodes. In this paper, to improve the capacitance performance of the supercapacitor, the all-pseudocapacitive electrodes of lamella-like Bi 18 SeO 29 /BiSe as the negative electrode and flower-like Co 0.85 Se nanosheets as the positive electrode are synthesized by using a facile low-temperature one-step hydrothermal method. The microstructures and morphology of the electrode materials are carefully characterized, and the capacitance performances are also tested. The Bi 18 SeO 29 /BiSe and Co 0.85 Se have high specific capacitance (471.3 F g -1 and 255 F g -1 at 0.5 A g -1 ), high conductivity, outstanding cycling stability, as well as good rate capability. The assembled asymmetric supercapacitor completely based on the pseudocapacitive electrodes exhibits outstanding cycling stability (about 93% capacitance retention after 5000 cycles). Moreover, the devices exhibit high energy density of 24.2 Wh kg -1 at a power density of 871.2 W kg -1 in the voltage window of 0-1.6 V with 2 M KOH solution.

Porous WO3/graphene/polyester textile electrode materials with enhanced electrochemical performance for flexible solid-state supercapacitors.

PubMed

Jin, Li-Na; Liu, Ping; Jin, Chun; Zhang, Jia-Nan; Bian, Shao-Wei

2018-01-15

In this work, a flexible and porous WO 3 /grapheme/polyester (WO 3 /G/PT) textile electrode was successfully prepared by in situ growing WO 3 on the fiber surface inside G/PT composite fabrics. The unique electrode structure facilitates to enhance the energy storage performance because the 3D conductive network constructed by the G/PT increase the electron transportation rate, nanotructured WO 3 exposed enhanced electrochemically active surface area and the hierarchically porous structure improved the electrolyte ion diffusion rate. The optimized WO 3 /G/PT textile electrode exhibited good electrochemical performance with a high areal capacitance of 308.2mFcm -2 at a scan rate of 2mVs -1 and excellent cycling stability. A flexible asymmetric supercapacitor (ASC) device was further fabricated by using the WO 3 /G/PT electrode and G/PT electrode, which exhibited a good specific capacitance of 167.6mFcm -3 and high energy density of 60μWhcm -3 at the power density of 2320 μWcm -3 . Copyright © 2017 Elsevier Inc. All rights reserved.

Organic Photovoltaic Devices Based on Oriented n-Type Molecular Films Deposited on Oriented Polythiophene Films.

PubMed

Mizokuro, Toshiko; Tanigaki, Nobutaka; Miyadera, Tetsuhiko; Shibata, Yousei; Koganezawa, Tomoyuki

2018-04-01

The molecular orientation of π-conjugated molecules has been reported to significantly affect the performance of organic photovoltaic devices (OPVs) based on molecular films. Hence, the control of molecular orientation is a key issue toward the improvement of OPV performance. In this research, oriented thin films of an n-type molecule, 3,4,9,10-Perylenetetracarboxylic Bisbenzimida-zole (PTCBI), were formed by deposition on in-plane oriented polythiophene (PT) films. Orientation of the PTCBI films was evaluated by polarized UV-vis spectroscopy and 2D-Grazing incidence X-ray diffraction. Results indicated that PTCBI molecules on PT film exhibit nearly edge-on and in-plane orientation (with molecular long axis along the substrate), whereas PTCBI molecules without PT film exhibit neither. OPVs composed of PTCBI molecular film with and without PT were fabricated and evaluated for correlation of orientation with performance. The OPVs composed of PTCBI film with PT showed higher power conversion efficiency (PCE) than that of film without PT. The experiment indicated that in-plane orientation of PTCBI molecules absorbs incident light more efficiently, leading to increase in PCE.

Epitaxy of Ferroelectric P(VDF-TrFE) Films via Removable PTFE Templates and Its Application in Semiconducting/Ferroelectric Blend Resistive Memory.

PubMed

Xia, Wei; Peter, Christian; Weng, Junhui; Zhang, Jian; Kliem, Herbert; Jiang, Yulong; Zhu, Guodong

2017-04-05

Ferroelectric polymer based devices exhibit great potentials in low-cost and flexible electronics. To meet the requirements of both low voltage operation and low energy consumption, thickness of ferroelectric polymer films is usually required to be less than, for example, 100 nm. However, decrease of film thickness is also accompanied by the degradation of both crystallinity and ferroelectricity and also the increase of current leakage, which surely degrades device performance. Here we report one epitaxy method based on removable poly(tetrafluoroethylene) (PTFE) templates for high-quality fabrication of ordered ferroelectric polymer thin films. Experimental results indicate that such epitaxially grown ferroelectric polymer films exhibit well improved crystallinity, reduced current leakage and good resistance to electrical breakdown, implying their applications in high-performance and low voltage operated ferroelectric devices. On the basis of this removable PTFE template method, we fabricated organic semiconducting/ferroelectric blend resistive films which presented record electrical performance with operation voltage as low as 5 V and ON/OFF ratio up to 10 5 .

Different Effect of the Additional Electron-Withdrawing Cyano Group in Different Conjugation Bridge: The Adjusted Molecular Energy Levels and Largely Improved Photovoltaic Performance.

PubMed

Li, Huiyang; Fang, Manman; Hou, Yingqin; Tang, Runli; Yang, Yizhou; Zhong, Cheng; Li, Qianqian; Li, Zhen

2016-05-18

Four organic sensitizers (LI-68-LI-71) bearing various conjugated bridges were designed and synthesized, in which the only difference between LI-68 and LI-69 (or LI-70 and LI-71) was the absence/presence of the CN group as the auxiliary electron acceptor. Interestingly, compared to the reference dye of LI-68, LI-69 bearing the additional CN group exhibited the bad performance with the decreased Jsc and Voc values. However, once one thiophene moiety near the anchor group was replaced by pyrrole with the electron-rich property, the resultant LI-71 exhibited a photoelectric conversion efficiency increase by about 3 folds from 2.75% (LI-69) to 7.95% (LI-71), displaying the synergistic effect of the two moieties (CN and pyrrole). Computational analysis disclosed that pyrrole as the auxiliary electron donor (D') in the conjugated bridge can compensate for the lower negative charge in the electron acceptor, which was caused by the CN group as the electron trap, leading to the more efficient electron injection and better photovoltaic performance.

Implications of Weak-Link Behavior on the Performance of Mo/Au Bilayer Transition-Edge Sensors

NASA Technical Reports Server (NTRS)

Smith, Stephen J.

2011-01-01

Understanding the physical properties of the superconducting-to-normal transition is fundamental for optimizing the design and performance of transition-edge sensors (TESs). Recent critical current measurements of Mol Au bilayer test structures show that they act as weak superconducting links, exhibiting oscillatory, Fraunhofer-like behavior with applied magnetic field. In this paper we investigate the implications of this behavior for TES X-ray detectors, under operational bias conditions. These devices include normal metal features used for absorber attachment and unexplained noise suppression, which result in modifications to the previously reported critical current behavior. We present measurements of the logarithmic resistance sensitivity with temperature, a, and current, b, as a function of applied magnetic field and bias point within the resistive transition. Results show that these important device parameters exhibit similar oscillatory behavior with applied magnetic field, which in turn affects the signal responsivity and noise, and hence the energy resolution. These results show the significance of the critical current in determining the performance of TESs and hold promise to improve future.

Electrochemical characterization of nanodimensional metal oxide materials

NASA Astrophysics Data System (ADS)

Tang, Paul Enle

Energy storage devices have become a bottleneck in performance improvements for portable electronics. This research seeks to answer basic science questions that may lead to the necessary improvements. First, this work demonstrates that insertion of multivalent ions into vanadium oxide greatly exceeds the storage capacity of materials presently used. Second, this work demonstrates that potassium ferrate exhibits a uniquely large pseudocapacitive effect. This effect can be used to great advantage when high power density and high energy density are required. Lastly, this work proposes a model of pseudocapacitance that has a greater descriptive power than that of previous models.

Leveraging organismal biology to forecast the effects of climate change.

PubMed

Buckley, Lauren B; Cannistra, Anthony F; John, Aji

2018-04-26

Despite the pressing need for accurate forecasts of ecological and evolutionary responses to environmental change, commonly used modelling approaches exhibit mixed performance because they omit many important aspects of how organisms respond to spatially and temporally variable environments. Integrating models based on organismal phenotypes at the physiological, performance and fitness levels can improve model performance. We summarize current limitations of environmental data and models and discuss potential remedies. The paper reviews emerging techniques for sensing environments at fine spatial and temporal scales, accounting for environmental extremes, and capturing how organisms experience the environment. Intertidal mussel data illustrate biologically important aspects of environmental variability. We then discuss key challenges in translating environmental conditions into organismal performance including accounting for the varied timescales of physiological processes, for responses to environmental fluctuations including the onset of stress and other thresholds, and for how environmental sensitivities vary across lifecycles. We call for the creation of phenotypic databases to parameterize forecasting models and advocate for improved sharing of model code and data for model testing. We conclude with challenges in organismal biology that must be solved to improve forecasts over the next decade.acclimation, biophysical models, ecological forecasting, extremes, microclimate, spatial and temporal variability.

Preparation of V-Doped LiFePO4/C as the Optimized Cathode Material for Lithium Ion Batteries.

PubMed

Sun, Pingping; Zhang, Haiyang; Shen, Kai; Fan, Qi; Xu, Qingyu

2015-04-01

LiFe1-x,Vx,PO4/C composites were synthesized by solid state reaction. The effect of carbon coating and V doping on the performance of LiFePO4 has been systematically investigated by X-ray diffraction (XRD), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), transmission electron microscope (TEM), charge/discharge and cyclic voltammetry (CV) measurement. The results show that carbon coating and proper amount of V incorporation do not significantly change the host crystal structure of LiFePO4, while the electrochemical performance of LiFePO4 can be significantly improved. Particularly, the LiFe0.96V0.04PO4/C exhibits the best performance with a specific discharge capacity of 105.5 mA h/g at 5.0 C, 90.3 mA h/g at 10 C and 66.7 mA h/g at 30 C with stable cycle performance, which is significantly improved compared with the pure LiFePO4/C. The cyclic voltammograms result reveals that V doping could decrease the resistance of LiFePO4/C composite electrode drastically and improve its reversibility.

The acceleration intermediate phase (NiS and Ni3S2) evolution by nanocrystallization in Li/NiS2 thermal batteries with high specific capacity

NASA Astrophysics Data System (ADS)

Jin, Chuanyu; Zhou, Lingping; Fu, Licai; Zhu, Jiajun; Li, Deyi; Yang, Wulin

2017-06-01

The intermediate phase of NiS2 is thought to be a bottleneck currently to improve the overall performance of Li/NiS2 thermal batteries because of its low conductivity and close formation enthalpy between NiS2 and the intermediate phase (NiS, Ni3S2, etc). For improving the discharge performances of Li/NiS2 thermal batteries, the nano NiS2 with an average size of 85 ± 5 nm is designated as a cathode material. The electrochemical measurements show that the specific capacity of nano NiS2 cathode is higher than micro NiS2. The nano NiS2 cathode exhibits excellent electrochemical performances with high specific capacities of 794 and 654 mAh g-1 at current density of 0.1 and 0.5 A cm-2 under a cut-off voltage of 0.5 V, respectively. These results show that the rapid intermediate phase evolution from the nanocrystallization can obviously enhance use efficiency of NiS2 and improve discharge performances of thermal batteries.

Physical performance of biodegradable films intended for antimicrobial food packaging.

PubMed

Marcos, Begonya; Aymerich, Teresa; Monfort, Josep M; Garriga, Margarita

2010-10-01

Antimicrobial films were prepared by including enterocins to alginate, polyvinyl alcohol (PVOH), and zein films. The physical performance of the films was assessed by measuring color, microstructure (SEM), water vapor permeability (WVP), and tensile properties. All studied biopolymers showed poor WVP and limited tensile properties. PVOH showed the best performance exhibiting the lowest WVP values, higher tensile properties, and flexibility among studied biopolymers. SEM of antimicrobial films showed increased presence of voids and pores as a consequence of enterocin addition. However, changes in microstructure did not disturb WVP of films. Moreover, enterocin-containing films showed slight improvement compared to control films. Addition of enterocins to PVOH films had a plasticizing effect, by reducing its tensile strength and increasing the strain at break. The presence of enterocins had an important effect on tensile properties of zein films by significantly reducing its brittleness. Addition of enterocins, thus, proved not to disturb the physical performance of studied biopolymers. Development of new antimicrobial biodegradable packaging materials may contribute to improving food safety while reducing environmental impact derived from packaging waste. Practical Application: Development of new antimicrobial biodegradable packaging materials may contribute to improving food safety while reducing environmental impact derived from packaging waste.

Improving motor performance without training: the effect of combining mirror visual feedback with transcranial direct current stimulation.

PubMed

von Rein, Erik; Hoff, Maike; Kaminski, Elisabeth; Sehm, Bernhard; Steele, Christopher J; Villringer, Arno; Ragert, Patrick

2015-04-01

Mirror visual feedback (MVF) during motor training has been shown to improve motor performance of the untrained hand. Here we thought to determine if MVF-induced performance improvements of the left hand can be augmented by upregulating plasticity in right primary motor cortex (M1) by means of anodal transcranial direct current stimulation (a-tDCS) while subjects trained with the right hand. Participants performed a ball-rotation task with either their left (untrained) or right (trained) hand on two consecutive days (days 1 and 2). During training with the right hand, MVF was provided concurrent with two tDCS conditions: group 1 received a-tDCS over right M1 (n = 10), whereas group 2 received sham tDCS (s-tDCS, n = 10). On day 2, performance was reevaluated under the same experimental conditions compared with day 1 but without tDCS. While baseline performance of the left hand (day 1) was not different between groups, a-tDCS exhibited stronger MVF-induced performance improvements compared with s-tDCS. Similar results were observed for day 2 (without tDCS application). A control experiment (n = 8) with a-tDCS over right M1 as outlined above but without MVF revealed that left hand improvement was significantly less pronounced than that induced by combined a-tDCS and MVF. Based on these results, we provide novel evidence that upregulating activity in the untrained M1 by means of a-tDCS is capable of augmenting MVF-induced performance improvements in young normal volunteers. Our findings suggest that concurrent MVF and tDCS might have synergistic and additive effects on motor performance of the untrained hand, a result of relevance for clinical approaches in neurorehabilitation and/or exercise science. Copyright © 2015 the American Physiological Society.

MnO2-GO double-shelled sulfur (S@MnO2@GO) as a cathode for Li-S batteries with improved rate capability and cyclic performance

NASA Astrophysics Data System (ADS)

Huang, Xingkang; Shi, Keying; Yang, Joseph; Mao, George; Chen, Junhong

2017-07-01

Sulfur cathodes have attracted much attention recently because of their high energy density and power density. However, sulfur possesses very poor electrical conductivity, and lithium polysulfides, resulting from the lithiation of sulfur, are prone to dissolving into electrolytes, which leads to the loss of active materials and poor cyclic performance of the sulfur cathodes. Here we report an MnO2-graphene oxide (GO) double-shelled sulfur (S@MnO2@GO) with improved rate capability and cyclic performance, in which we propose a new reaction using sulfur-reducing KMnO4 to produce MnO2 that covers the surface of the excess sulfur in situ. The resulting MnO2 with honeycomb-like morphology provides excellent voids for storing polysulfides. The outermost GO was assembled to block the open pores of MnO2, thereby minimizing the opportunity for polysulfides to leach into the electrolytes. The GO significantly improved the electrical conductivity of the sulfur cathode, and the S@MnO2@GO exhibited excellent rate capability and long cycle life.

Regulation of the discharge reservoir of negative electrodes in Ni-MH batteries by using Ni(OH) x (x = 2.10) and γ-CoOOH

NASA Astrophysics Data System (ADS)

Shangguan, Enbo; Chang, Zhaorong; Tang, Hongwei; Yuan, Xiao-Zi; Wang, Haijiang

In this paper, a novel strategy to regulate the discharge reservoir of negative electrodes in Ni-MH batteries is introduced by using Ni(OH) x (x = 2.10) and γ-CoOOH. The electrochemical measurements of these batteries demonstrate that the use of Ni(OH) x (x = 2.10) and γ-CoOOH can not only successfully regulate the discharge reservoir of negative electrodes in Ni-MH batteries to an adequate quantity, but also effectively improve the electrochemical performance of the batteries. Compared with normal batteries, the in-house prepared batteries with a lower discharge reservoir exhibit an enhanced discharge capacity, improved high-rate discharge ability, higher discharge potential plateau and superior cycle stability. The effect of Ni(OH) x (x = 2.10) and γ-CoOOH on the electrochemical performance of nickel electrode is also investigated by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The results suggest that the new method is simple and effective for cost reduction of Ni-MH batteries with improved electrochemical performance.

Feature engineering for MEDLINE citation categorization with MeSH.

PubMed

Jimeno Yepes, Antonio Jose; Plaza, Laura; Carrillo-de-Albornoz, Jorge; Mork, James G; Aronson, Alan R

2015-04-08

Research in biomedical text categorization has mostly used the bag-of-words representation. Other more sophisticated representations of text based on syntactic, semantic and argumentative properties have been less studied. In this paper, we evaluate the impact of different text representations of biomedical texts as features for reproducing the MeSH annotations of some of the most frequent MeSH headings. In addition to unigrams and bigrams, these features include noun phrases, citation meta-data, citation structure, and semantic annotation of the citations. Traditional features like unigrams and bigrams exhibit strong performance compared to other feature sets. Little or no improvement is obtained when using meta-data or citation structure. Noun phrases are too sparse and thus have lower performance compared to more traditional features. Conceptual annotation of the texts by MetaMap shows similar performance compared to unigrams, but adding concepts from the UMLS taxonomy does not improve the performance of using only mapped concepts. The combination of all the features performs largely better than any individual feature set considered. In addition, this combination improves the performance of a state-of-the-art MeSH indexer. Concerning the machine learning algorithms, we find that those that are more resilient to class imbalance largely obtain better performance. We conclude that even though traditional features such as unigrams and bigrams have strong performance compared to other features, it is possible to combine them to effectively improve the performance of the bag-of-words representation. We have also found that the combination of the learning algorithm and feature sets has an influence in the overall performance of the system. Moreover, using learning algorithms resilient to class imbalance largely improves performance. However, when using a large set of features, consideration needs to be taken with algorithms due to the risk of over-fitting. Specific combinations of learning algorithms and features for individual MeSH headings could further increase the performance of an indexing system.

The Grass Might Be Greener: Medical Marijuana Patients Exhibit Altered Brain Activity and Improved Executive Function after 3 Months of Treatment

PubMed Central

Gruber, Staci A.; Sagar, Kelly A.; Dahlgren, Mary K.; Gonenc, Atilla; Smith, Rosemary T.; Lambros, Ashley M.; Cabrera, Korine B.; Lukas, Scott E.

2018-01-01

The vast majority of states have enacted full or partial medical marijuana (MMJ) programs, causing the number of patients seeking certification for MMJ use to increase dramatically in recent years. Despite increased use of MMJ across the nation, no studies thus far have examined the specific impact of MMJ on cognitive function and related brain activation. In the present study, MMJ patients seeking treatment for a variety of documented medical conditions were assessed prior to initiating MMJ treatment and after 3 months of treatment as part of a larger longitudinal study. In order to examine the effect of MMJ treatment on task-related brain activation, MMJ patients completed the Multi-Source Interference Test (MSIT) while undergoing functional magnetic resonance imaging (fMRI). We also collected data regarding conventional medication use, clinical state, and health-related measures at each visit. Following 3 months of treatment, MMJ patients demonstrated improved task performance accompanied by changes in brain activation patterns within the cingulate cortex and frontal regions. Interestingly, after MMJ treatment, brain activation patterns appeared more similar to those exhibited by healthy controls from previous studies than at pre-treatment, suggestive of a potential normalization of brain function relative to baseline. These findings suggest that MMJ use may result in different effects relative to recreational marijuana (MJ) use, as recreational consumers have been shown to exhibit decrements in task performance accompanied by altered brain activation. Moreover, patients in the current study also reported improvements in clinical state and health-related measures as well as notable decreases in prescription medication use, particularly opioids and benzodiapezines after 3 months of treatment. Further research is needed to clarify the specific neurobiologic impact, clinical efficacy, and unique effects of MMJ for a range of indications and how it compares to recreational MJ use. PMID:29387010

The Grass Might Be Greener: Medical Marijuana Patients Exhibit Altered Brain Activity and Improved Executive Function after 3 Months of Treatment.

PubMed

Gruber, Staci A; Sagar, Kelly A; Dahlgren, Mary K; Gonenc, Atilla; Smith, Rosemary T; Lambros, Ashley M; Cabrera, Korine B; Lukas, Scott E

2017-01-01

The vast majority of states have enacted full or partial medical marijuana (MMJ) programs, causing the number of patients seeking certification for MMJ use to increase dramatically in recent years. Despite increased use of MMJ across the nation, no studies thus far have examined the specific impact of MMJ on cognitive function and related brain activation. In the present study, MMJ patients seeking treatment for a variety of documented medical conditions were assessed prior to initiating MMJ treatment and after 3 months of treatment as part of a larger longitudinal study. In order to examine the effect of MMJ treatment on task-related brain activation, MMJ patients completed the Multi-Source Interference Test (MSIT) while undergoing functional magnetic resonance imaging (fMRI). We also collected data regarding conventional medication use, clinical state, and health-related measures at each visit. Following 3 months of treatment, MMJ patients demonstrated improved task performance accompanied by changes in brain activation patterns within the cingulate cortex and frontal regions. Interestingly, after MMJ treatment, brain activation patterns appeared more similar to those exhibited by healthy controls from previous studies than at pre-treatment, suggestive of a potential normalization of brain function relative to baseline. These findings suggest that MMJ use may result in different effects relative to recreational marijuana (MJ) use, as recreational consumers have been shown to exhibit decrements in task performance accompanied by altered brain activation. Moreover, patients in the current study also reported improvements in clinical state and health-related measures as well as notable decreases in prescription medication use, particularly opioids and benzodiapezines after 3 months of treatment. Further research is needed to clarify the specific neurobiologic impact, clinical efficacy, and unique effects of MMJ for a range of indications and how it compares to recreational MJ use.

Crossed Wernicke's aphasia: a case report.

PubMed

Sheehy, Laurie M; Haines, Mary E

2004-04-01

Crossed aphasia is a phenomenon in which an individual sustains a lesion in the right hemisphere (typically non-language dominant), but who exhibits an aphasic syndrome. The authors present a case study of an individual with crossed aphasia (CA) in an attempt to provide anecdotal information for four questions posed by : (a). Is CA a reversal of the normal cerebral hemisphere pattern of language function? (b). Does the presence of aphasia following a right cerebral hemisphere lesion indicate that typical right hemisphere functions (e.g., visual perception) are intact? (c). How may the aphasia's presentation differ from typical left hemisphere aphasias? And (d). is the pattern of improvement following CA similar to that of typical left hemisphere aphasias? We longitudinally examined the communicative-cognitive performance of an adult man with crossed aphasia of the Wernicke's type following a cerebrovascular accident. A 21-week follow-up evaluation indicated improvements in his language functioning from our initial evaluation, but he continued to exhibit a classic, moderately severe Wernicke's aphasia.

Chitosan derivatives targeting lipid bilayers: Synthesis, biological activity and interaction with model membranes.

PubMed

Martins, Danubia Batista; Nasário, Fábio Domingues; Silva-Gonçalves, Laiz Costa; de Oliveira Tiera, Vera Aparecida; Arcisio-Miranda, Manoel; Tiera, Marcio José; Dos Santos Cabrera, Marcia Perez

2018-02-01

The antimicrobial activity of chitosan and derivatives to human and plant pathogens represents a high-valued prospective market. Presently, two low molecular weight derivatives, endowed with hydrophobic and cationic character at different ratios were synthesized and characterized. They exhibit antimicrobial activity and increased performance in relation to the intermediate and starting compounds. However, just the derivative with higher cationic character showed cytotoxicity towards human cervical carcinoma cells. Considering cell membranes as targets, the mode of action was investigated through the interaction with model lipid vesicles mimicking bacterial, tumoral and erythrocyte membranes. Intense lytic activity and binding are demonstrated for both derivatives in anionic bilayers. The less charged compound exhibits slightly improved selectivity towards bacterial model membranes, suggesting that balancing its hydrophobic/hydrophilic character may improve efficiency. Observing the aggregation of vesicles, we hypothesize that the "charge cluster mechanism", ascribed to some antimicrobial peptides, could be applied to these chitosan derivatives. Copyright © 2017 Elsevier Ltd. All rights reserved.

Development and Hover Testing of the Active Elevon Rotor

DTIC Science & Technology

2012-05-01

typically aimed at reducing vibration, improving rotor performance, and/or reducing blade -vortex interaction (BVI) or in-plane noise . These efforts...will become unstable, either through a 1-DOF (degree of freedom) flutter or some kind of aeroservoelastic coupling with the rotor blade and/or wake ... blade CAEAs did exhibit electrical arcing (audible noise ), even at oscillatory voltages below ±200 V. This arcing/ noise suggests a latent deficiency

Comparative Analysis of Cutting Efficiency and Surface Maintenance Between Different Types of Implant Drills: An In Vitro Study.

PubMed

Hochscheidt, Celso João; Shimizu, Roberto Hideo; Andrighetto, Augusto Ricardo; Pierezan, Rodrigo; Thomé, Geninho; Salatti, Rafael

2017-10-01

This study evaluated cutting efficiency (CE) and linear wear of dental implant drills after 450 standardized osteotomies on bovine ribs. Diamond-like carbon-coated steel drills (SG), acid-treated steel drills (EG), and ceramic drills (ZG) were divided into 6 subgroups according to the number of uses. A robot-controlled program performed systematic instrumentation, timing, axial loading, and managed feed rate. CE was recorded in a polyurethane resin blank and end wear (VBBmax) was analyzed under stereo microscopy. After osteotomies in beef ribs, CE for the Ø2.0-mm drill decreased 10.2% in SG and 10.9% in ZG; for the Ø3.0-mm drill, CE decreased 30.6% in SG, 8.5% in ZG, and improved in EG. The greatest wear occurred in Ø2.0-mm drills; ZG drills (Ø3.0 mm) exhibited only edge frittering, as confirmed on scanning electron microscopy. After 50 exposures to mechanical loads, steel and ceramic drills lost CE. Whereas cutting and thermal performance improved in experimental drills, the Ø2.0-mm drill exhibited the most signs of wear proportional to use. These findings suggest that, with the methodology employed, the life of these drills exceeds 50 osteotomies.

Multi-channel and porous SiO@N-doped C rods as anodes for high-performance lithium-ion batteries

NASA Astrophysics Data System (ADS)

Huang, Xiao; Li, Mingqi

2018-05-01

To improve the cycling stability and rate capability of SiO electrodes, multi-channel and porous SiO@N-doped C (mp-SiO@N-doped C) rods are fabricated by the combination of electrospinning and heat treatment with the assistance of poly(methyl methacrylate) (PMMA). During annealing, in-situ PMMA degradation and gasification lead to the formation of multi-channel structure and more pores. As anodes for lithium ion batteries, the mp-SiO@N-doped C rods exhibit excellent cycling stability. At a current density of 400 mA g-1, a discharge capacity of 806 mAh g-1 can be kept after 250 cycles, the retention of which is over than 100% versus the initial reversible capacity. Compared with the SiO@N-doped C rods synthesized without the help of PMMA, the mp-SiO@N-doped C rods exhibit more excellent rate capability. The excellent electrochemical performance is attributed to the special structure of the mp-SiO@N-doped C rods. In addition to the conductivity improved by carbon fibers, the multi-channel and porous structures not only make ions/electrons transfer and electrolyte diffusion easier, but also contribute to the structural stability of the electrodes.

Sildenafil has little influence on cardiovascular hemodynamics or 6-km time trial performance in trained men and women at simulated high altitude.

PubMed

Jacobs, Kevin A; Kressler, Jochen; Stoutenberg, Mark; Roos, Bernard A; Friedlander, Anne L

2011-01-01

Sildenafil improves maximal exercise capacity at high altitudes (∼4350-5800 m) by reducing pulmonary arterial pressure and enhancing oxygen delivery, but the effects on exercise performance at less severe altitudes are less clear. To determine the effects of sildenafil on cardiovascular hemodynamics (heart rate, stroke volume, and cardiac output), arterial oxygen saturation (SaO2), and 6-km time-trial performance of endurance-trained men and women at a simulated altitude of ∼3900 m. Twenty men and 15 women, endurance-trained, completed one experimental exercise trial (30 min at 55% of altitude-specific capacity +6-km time trial) at sea level (SL) and two trials at simulated high altitude (HA) while breathing hypoxic gas (12.8% FIo2) after ingestion of either placebo or 50 mg sildenafil in double-blind, randomized, and counterbalanced fashion. Maximal exercise capacity and SaO2 were significantly reduced at HA compared to SL (18%-23%), but sildenafil did not significantly improve cardiovascular hemodynamics or time-trial performance in either men or women compared to placebo and only improved SaO2 in women (4%). One male subject (5% of male subjects, 2.8% of all subjects) exhibited a meaningful 36-s improvement in time-trial performance with sildenafil compared to placebo. In this group of endurance trained men and women, sildenafil had very little influence on cardiovascular hemodynamics, SaO2, and 6-km time-trial performance at a simulated altitude of ∼3900 m. It appears that a very small percentage of endurance-trained men and women derive meaningful improvements in aerobic performance from sildenafil at a simulated altitude of ∼3900 m.

Sensorimotor Learning of Acupuncture Needle Manipulation Using Visual Feedback

PubMed Central

Jung, Won-Mo; Lim, Jinwoong; Lee, In-Seon; Park, Hi-Joon; Wallraven, Christian; Chae, Younbyoung

2015-01-01

Objective Humans can acquire a wide variety of motor skills using sensory feedback pertaining to discrepancies between intended and actual movements. Acupuncture needle manipulation involves sophisticated hand movements and represents a fundamental skill for acupuncturists. We investigated whether untrained students could improve their motor performance during acupuncture needle manipulation using visual feedback (VF). Methods Twenty-one untrained medical students were included, randomly divided into concurrent (n = 10) and post-trial (n = 11) VF groups. Both groups were trained in simple lift/thrusting techniques during session 1, and in complicated lift/thrusting techniques in session 2 (eight training trials per session). We compared the motion patterns and error magnitudes of pre- and post-training tests. Results During motion pattern analysis, both the concurrent and post-trial VF groups exhibited greater improvements in motion patterns during the complicated lifting/thrusting session. In the magnitude error analysis, both groups also exhibited reduced error magnitudes during the simple lifting/thrusting session. For the training period, the concurrent VF group exhibited reduced error magnitudes across all training trials, whereas the post-trial VF group was characterized by greater error magnitudes during initial trials, which gradually reduced during later trials. Conclusions Our findings suggest that novices can improve the sophisticated hand movements required for acupuncture needle manipulation using sensorimotor learning with VF. Use of two types of VF can be beneficial for untrained students in terms of learning how to manipulate acupuncture needles, using either automatic or cognitive processes. PMID:26406248

Clonidine improved laboratory-measured decision-making performance in abstinent heroin addicts.

PubMed

Zhang, Xiao-Li; Wang, Gui-Bin; Zhao, Li-Yan; Sun, Li-Li; Wang, Jun; Wu, Ping; Lu, Lin; Shi, Jie

2012-01-01

Impulsivity refers to a wide spectrum of actions characterized by quick and nonplanned reactions to external and internal stimuli, without taking into account the possible negative consequences for the individual or others, and decision-making is one of the biologically dissociated impulsive behaviors. Changes in impulsivity may be associated with norepinephrine. Various populations of drug addicts all performed impulsive decision making, which is a key risk factor in drug dependence and relapse. The present study investigated the effects of clonidine, which decreased norepinephrine release through presynaptic alpha-2 receptor activation, on the impaired decision-making performance in abstinent heroin addicts. Decision-making performance was assessed using the original version of Iowa Gambling Task (IGT). Both heroin addicts and normal controls were randomly assigned to three groups receiving clonidine, 0, 75 µg or 150 µg orally under double blind conditions. Psychiatric symptoms, including anxiety, depression and impulsivity, were rated on standardized scales. Heroin addicts reported higher scores on the Barratt Impulsiveness Scale and exhibited impaired decision-making on the IGT. A single high-dose of clonidine improved the decision-making performance in heroin addicts. Our results suggest clonidine may have a potential therapeutic role in heroin addicts by improving the impaired impulsive decision-making. The current findings have important implications for behavioral and pharmacological interventions targeting decision-making in heroin addiction.

Performance evaluation of a non-woven lithium ion battery separator prepared through a paper-making process

NASA Astrophysics Data System (ADS)

Huang, Xiaosong

2014-06-01

Porous separator functions to electrically insulate the negative and positive electrodes yet communicate lithium ions between the two electrodes when infiltrated with a liquid electrolyte. The separator must fulfill numerous requirements (e.g. permeability, wettability, and thermal stability) in order to optimize the abuse tolerance and electrochemical performance of a battery. Non-woven mat separators have advantages such as high porosity and heat resistance. However, their applications in lithium ion batteries are very limited as their inadequate pore structures could cause accelerated battery performance degradation and even internal short. This work features the development of thermally stable non-woven composite separators using a low cost paper-making process. The composite separators offer significantly improved thermal dimensional stability and exhibit superior wettability by the liquid electrolyte compared to a conventional polypropylene separator. The open porous structures of the non-woven composite separators also resulted in high effective ionic conductivities. The electrochemical performance of the composite separators was tested in coin cells. Stable cycle performances and improved rate capabilities have been observed for the coin cells with these composite separators.

Artificial semiconductor/insulator superlattice channel structure for high-performance oxide thin-film transistors

PubMed Central

Ahn, Cheol Hyoun; Senthil, Karuppanan; Cho, Hyung Koun; Lee, Sang Yeol

2013-01-01

High-performance thin-film transistors (TFTs) are the fundamental building blocks in realizing the potential applications of the next-generation displays. Atomically controlled superlattice structures are expected to induce advanced electric and optical performance due to two-dimensional electron gas system, resulting in high-electron mobility transistors. Here, we have utilized a semiconductor/insulator superlattice channel structure comprising of ZnO/Al2O3 layers to realize high-performance TFTs. The TFT with ZnO (5 nm)/Al2O3 (3.6 nm) superlattice channel structure exhibited high field effect mobility of 27.8 cm2/Vs, and threshold voltage shift of only < 0.5 V under positive/negative gate bias stress test during 2 hours. These properties showed extremely improved TFT performance, compared to ZnO TFTs. The enhanced field effect mobility and stability obtained for the superlattice TFT devices were explained on the basis of layer-by-layer growth mode, improved crystalline nature of the channel layers, and passivation effect of Al2O3 layers. PMID:24061388

Performance Enhancement of a Sulfur/Carbon Cathode by Polydopamine as an Efficient Shell for High-Performance Lithium-Sulfur Batteries.

PubMed

Zhang, Xuqing; Xie, Dong; Zhong, Yu; Wang, Donghuang; Wu, Jianbo; Wang, Xiuli; Xia, Xinhui; Gu, Changdong; Tu, Jiangping

2017-08-04

Lithium-sulfur batteries (LSBs) are considered to be among the most promising next-generation high-energy batteries. It is a consensus that improving the conductivity of sulfur cathodes and impeding the dissolution of lithium polysulfides are two key accesses to high-performance LSBs. Herein we report a sulfur/carbon black (S/C) cathode modified by self-polymerized polydopamine (pDA) with the assistance of polymerization treatment. The pDA acts as a novel and effective shell on the S/C cathode to stop the shuttle effect of polysulfides. By the synergistic effect of enhanced conductivity and multiple blocking effect for polysulfides, the S/C@pDA electrode exhibits improved electrochemical performances including large specific capacity (1135 mAh g -1 at 0.2 C), high rate capability (533 mAh g -1 at 5 C) and long cyclic life (965 mAh g -1 after 200 cycles). Our smart design strategy may promote the development of high-performance LSBs. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Understanding the Size-Dependent Sodium Storage Properties of Na2C6O6-Based Organic Electrodes for Sodium-Ion Batteries.

PubMed

Wang, Yaqun; Ding, Yu; Pan, Lijia; Shi, Ye; Yue, Zhuanghao; Shi, Yi; Yu, Guihua

2016-05-11

Organic electroactive materials represent a new generation of sustainable energy storage technology due to their unique features including environmental benignity, material sustainability, and highly tailorable properties. Here a carbonyl-based organic salt Na2C6O6, sodium rhodizonate (SR) dibasic, is systematically investigated for high-performance sodium-ion batteries. A combination of structural control, electrochemical analysis, and computational simulation show that rational morphological control can lead to significantly improved sodium storage performance. A facile antisolvent method was developed to synthesize microbulk, microrod, and nanorod structured SRs, which exhibit strong size-dependent sodium ion storage properties. The SR nanorod exhibited the best performance to deliver a reversible capacity of ∼190 mA h g(-1) at 0.1 C with over 90% retention after 100 cycles. At a high rate of 10 C, 50% of the capacity can be obtained due to enhanced reaction kinetics, and such high electrochemical activity maintains even at 80 °C. These results demonstrate a generic design route toward high-performance organic-based electrode materials for beyond Li-ion batteries. Using such a biomass-derived organic electrode material enables access to sustainable energy storage devices with low cost, high electrochemical performance and thermal stability.

Smart wearable Kevlar-based safeguarding electronic textile with excellent sensing performance.

PubMed

Wang, Sheng; Xuan, Shouhu; Liu, Mei; Bai, Linfeng; Zhang, Shuaishuai; Sang, Min; Jiang, Wanquan; Gong, Xinglong

2017-03-29

A novel S-ST/MWCNT/Kevlar-based wearable electronic textile (WET) with enhanced safeguarding performance and force sensing ability was fabricated. Stab resistance performance tests under quasi-static and dynamic conditions show that the maximum resistance force and penetration impact energy for the WET are 18 N and 11.76 J, which represent a 90% and 50% increment with respect to the neat Kevlar, respectively. Dynamic impact resistance tests show that the WET absorbs all the impact energy. The maximum resistance force of the WET is 1052 N, which represents an improvement of about 190% with respect to neat Kevlar. With the incorporation of multi-walled carbon nanotubes (MWCNTs), the WET can achieve a stable electrical conductivity of ∼10 -2 S m -1 , and the conductivity is highly sensitive to external mechanic forces. Notably, the sensing fabric also exhibits an outstanding ability to detect and analyze external forces. In addition, it can be fixed at any position of the human body and exhibits an ideal monitoring performance. Because of its flexibility, high sensitivity to various types of deformations and excellent safeguarding performance, the WET has a strong potential for wearable monitoring devices that simultaneously provide body protection and monitor the movements of the human body under various conditions.

Leveraging multi-layer imager detector design to improve low-dose performance for megavoltage cone-beam computed tomography

NASA Astrophysics Data System (ADS)

Hu, Yue-Houng; Rottmann, Joerg; Fueglistaller, Rony; Myronakis, Marios; Wang, Adam; Huber, Pascal; Shedlock, Daniel; Morf, Daniel; Baturin, Paul; Star-Lack, Josh; Berbeco, Ross

2018-02-01

While megavoltage cone-beam computed tomography (CBCT) using an electronic portal imaging device (EPID) provides many advantages over kilovoltage (kV) CBCT, clinical adoption is limited by its high doses. Multi-layer imager (MLI) EPIDs increase DQE(0) while maintaining high resolution. However, even well-designed, high-performance MLIs suffer from increased electronic noise from each readout, degrading low-dose image quality. To improve low-dose performance, shift-and-bin addition (ShiBA) imaging is proposed, leveraging the unique architecture of the MLI. ShiBA combines hardware readout-binning and super-resolution concepts, reducing electronic noise while maintaining native image sampling. The imaging performance of full-resolution (FR); standard, aligned binned (BIN); and ShiBA images in terms of noise power spectrum (NPS), electronic NPS, modulation transfer function (MTF), and the ideal observer signal-to-noise ratio (SNR)—the detectability index (d‧)—are compared. The FR 4-layer readout of the prototype MLI exhibits an electronic NPS magnitude 6-times higher than a state-of-the-art single layer (SLI) EPID. Although the MLI is built on the same readout platform as the SLI, with each layer exhibiting equivalent electronic noise, the multi-stage readout of the MLI results in electronic noise 50% higher than simple summation. Electronic noise is mitigated in both BIN and ShiBA imaging, reducing its total by ~12 times. ShiBA further reduces the NPS, effectively upsampling the image, resulting in a multiplication by a sinc2 function. Normalized NPS show that neither ShiBA nor BIN otherwise affects image noise. The LSF shows that ShiBA removes the pixilation artifact of BIN images and mitigates the effect of detector shift, but does not quantifiably improve the MTF. ShiBA provides a pre-sampled representation of the images, mitigating phase dependence. Hardware binning strategies lower the quantum noise floor, with 2  ×  2 implementation reducing the dose at which DQE(0) degrades by 10% from 0.01 MU to 0.004 MU, representing 20% improvement in d‧.

Rational Synthesis of Branched CoMoO4@CoNiO2 Core/Shell Nanowire Arrays for All-Solid-State Supercapacitors with Improved Performance.

PubMed

Ai, Yuanfei; Geng, Xuewen; Lou, Zheng; Wang, Zhiming M; Shen, Guozhen

2015-11-04

Effectively composite materials with optimized structures exhibited promising potential in continuing improving the electrochemical performances of supercapacitors in the past few years. Here, we proposed a rational design of branched CoMoO4@CoNiO2 core/shell nanowire arrays on Ni foam by two steps of hydrothermal processing. Owing to the high activity of the scaffold-like CoMoO4 nanowires and the well-defined CoNiO2 nanoneedles, the three-dimensional (3D) electrode architectures achieved remarkable electrochemical performances with high areal specific capacitance (5.31 F/cm(2) at 5 mA/cm(2)) and superior cycling stability(159% of the original specific capacitance, i.e., 95.7% of the maximum retained after 5000 cycles at 30 mA/cm(2)). The all-solid-state asymmetric supercapacitors composed of such electrode and activated carbon (AC) exhibited an areal specific capacitance of 1.54 F/cm(2) at 10 mA/cm(2) and a rate capability (59.75 Wh/kg at a 1464 W/kg) comparable with Li-ion batteries. It also showed an excellent cycling stability with no capacitance attenuation after 50000 cycles at 100 mA/cm(2). After rapid charging (1 s), such supercapacitors in series could lighten a red LED for a long time and drive a mini motor effectively, demonstrating advances in energy storage, scalable integrated applications, and promising commercial potential.

The sequence relay selection strategy based on stochastic dynamic programming

NASA Astrophysics Data System (ADS)

Zhu, Rui; Chen, Xihao; Huang, Yangchao

2017-07-01

Relay-assisted (RA) network with relay node selection is a kind of effective method to improve the channel capacity and convergence performance. However, most of the existing researches about the relay selection did not consider the statically channel state information and the selection cost. This shortage limited the performance and application of RA network in practical scenarios. In order to overcome this drawback, a sequence relay selection strategy (SRSS) was proposed. And the performance upper bound of SRSS was also analyzed in this paper. Furthermore, in order to make SRSS more practical, a novel threshold determination algorithm based on the stochastic dynamic program (SDP) was given to work with SRSS. Numerical results are also presented to exhibit the performance of SRSS with SDP.

Palladium-cobalt nanotube arrays supported on carbon fiber cloth as high-performance flexible electrocatalysts for ethanol oxidation.

PubMed

Wang, An-Liang; He, Xu-Jun; Lu, Xue-Feng; Xu, Han; Tong, Ye-Xiang; Li, Gao-Ren

2015-03-16

PdCo nanotube arrays (NTAs) supported on carbon fiber cloth (CFC) (PdCo NTAs/CFC) are presented as high-performance flexible electrocatalysts for ethanol oxidation. The fabricated flexible PdCo NTAs/CFC exhibits significantly improved electrocatalytic activity and durability compared with Pd NTAs/CFC and commercial Pd/C catalysts. Most importantly, the PdCo NTAs/CFC shows excellent flexibility and the high electrocatalytic performance remains almost constant under the different distorted states, such as normal, bending, and twisting states. This work shows the first example of Pd-based alloy NTAs supported on CFC as high-performance flexible electrocatalysts for ethanol oxidation. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Training children aged 5-10 years in manual compliance control to improve drawing and handwriting.

PubMed

Bingham, Geoffrey P; Snapp-Childs, Winona

2018-04-12

A large proportion of school-aged children exhibit poor drawing and handwriting. This prevalence limits the availability of therapy. We developed an automated method for training improved manual compliance control and relatedly, prospective control of a stylus. The approach included a difficult training task, while providing parametrically modifiable support that enables the children to perform successfully while developing good compliance control. The task was to use a stylus to push a bead along a 3D wire path. Support was provided by making the wire magnetically attractive to the stylus. Support was progressively reduced as 3D tracing performance improved. We report studies that (1) compared performance of Typically Developing (TD) children and children with Developmental Coordination Disorder (DCD), (2) tested training with active versus passive movement, (3) tested progressively reduced versus constant or no support during training, (4) tested children of different ages, (5) tested the transfer of training to a drawing task, (6) tested the specificity of training in respect to the size, shape and dimensionality of figures, and (7) investigated the relevance of the training task to the Beery VMI, an inventory used to diagnose DCD. The findings were as follows. (1) Pre-training performance of TD and DCD children was the same and good with high support but distinct and poor with low support. Support yielded good self-efficacy that motivated training. Post training performance with no support was improved and the same for TD and DCD children. (2) Actively controlled movements were required for improved performance. (3) Progressively reduced support was required for good performance during and after training. (4) Age differences in performance during pre-training were eliminated post-training. (5) Improvements transferred to drawing. (6) There was no evidence of specificity of training in transfer. (7) Disparate Beery scores were reflected in pre-training but not post-training performance. We conclude that the method improves manual compliance control, and more generally, prospective control of movements used in drawing performance. Copyright © 2018. Published by Elsevier B.V.

Thermocouples of tantalum and rhenium alloys for more stable vacuum-high temperature performance

NASA Technical Reports Server (NTRS)

Morris, J. F. (Inventor)

1977-01-01

Thermocouples of the present invention provide stability and performance reliability in systems involving high temperatures and vacuums by employing a bimetallic thermocouple sensor wherein each metal of the sensor is selected from a group of metals comprising tantalum and rhenium and alloys containing only those two metals. The tantalum, rhenium thermocouple sensor alloys provide bare metal thermocouple sensors having advantageous vapor pressure compatibilities and performance characteristics. The compatibility and physical characteristics of the thermocouple sensor alloys of the present invention result in improved emf, temperature properties and thermocouple hot junction performance. The thermocouples formed of the tantalum, rhenium alloys exhibit reliability and performance stability in systems involving high temperatures and vacuums and are adaptable to space propulsion and power systems and nuclear environments.

High performance hybrid silicon micropillar solar cell based on light trapping characteristics of Cu nanoparticles

NASA Astrophysics Data System (ADS)

Zhang, Yulong; Fan, Zhiqiang; Zhang, Weijia; Ma, Qiang; Jiang, Zhaoyi; Ma, Denghao

2018-05-01

High performance silicon combined structure (micropillar with Cu nanoparticles) solar cell has been synthesized from N-type silicon substrates based on the micropillar array. The combined structure solar cell exhibited higher short circuit current rather than the silicon miropillar solar cell, which the parameters of micropillar array are the same. Due to the Cu nanoparticles were decorated on the surface of silicon micropillar array, the photovoltaic properties of cells have been improved. In addition, the optimal efficiency of 11.5% was measured for the combined structure solar cell, which is better than the silicon micropillar cell.

Design and evaluation of experimental ceramic automobile thermal reactors

NASA Technical Reports Server (NTRS)

Stone, P. L.; Blankenship, C. P.

1974-01-01

The paper summarizes the results obtained in an exploratory evaluation of ceramics for automobile thermal reactors. Candidate ceramic materials were evaluated in several reactor designs using both engine dynamometer and vehicle road tests. Silicon carbide contained in a corrugated metal support structure exhibited the best performance, lasting 1100 hours in engine dynamometer tests and for more than 38,600 kilimeters (24,000 miles) in vehicle road tests. Although reactors containing glass-ceramic components did not perform as well as silicon carbide, the glass-ceramics still offer good potential for reactor use with improved reactor designs.

Design and evaluation of experimental ceramic automobile thermal reactors

NASA Technical Reports Server (NTRS)

Stone, P. L.; Blankenship, C. P.

1974-01-01

The results obtained in an exploratory evaluation of ceramics for automobile thermal reactors are summarized. Candidate ceramic materials were evaluated in several reactor designs by using both engine-dynamometer and vehicle road tests. Silicon carbide contained in a corrugated-metal support structure exhibited the best performance, lasting 1100 hr in engine-dynamometer tests and more than 38,600 km (24000 miles) in vehicle road tests. Although reactors containing glass-ceramic components did not perform as well as those containing silicon carbide, the glass-ceramics still offer good potential for reactor use with improved reactor designs.

Zerodur polishing process for high surface quality and high efficiency

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tesar, A.; Fuchs, B.

1992-08-01

Zerodur is a glass-ceramic composite importance in applications where temperature instabilities influence optical and mechanical performance, such as in earthbound and spaceborne telescope mirror substrates. Polished Zerodur surfaces of high quality have been required for laser gyro mirrors. Polished surface quality of substrates affects performance of high reflection coatings. Thus, the interest in improving Zerodur polished surface quality has become more general. Beyond eliminating subsurface damage, high quality surfaces are produced by reducing the amount of hydrated material redeposited on the surface during polishing. With the proper control of polishing parameters, such surfaces exhibit roughnesses of

Enhanced photoresponse in dye-sensitized solar cells via localized surface plasmon resonance through highly stable nickel nanoparticles

NASA Astrophysics Data System (ADS)

Rahman, Md. Mahbubur; Im, Sang Hyuk; Lee, Jae-Joon

2016-03-01

We demonstrated the localized surface plasmon resonance (LSPR) effect of Ni nanoparticles (NiNPs) on the performance of dye-sensitized solar cells (DSSCs). Our study revealed that NiNPs in a conventional I-/I3- electrolyte (NiNPs@I-/I3-) increased the net optical absorption of a N719 dye over a broad wavelength range by LSPR, and concurrently improved the power conversion efficiency (PCE) in DSSCs. At an optimized concentration of the NiNPs@I-/I3- electrolyte (1 mg mL-1), N719-sensitized DSSCs with a photoanode thickness of ca. 2, 5, and 10 μm, exhibited net PCEs of 2.32, 6.02, and 9.83%, respectively. These efficiencies were consistent with a net improvement of 43.2, 20.4, and 12.7%, respectively and were mainly attributed to a significant enhancement of the short circuit current density (Jsc) by the LSPR from the NiNPs. Similar effects were observed for cells sensitized by the N3, Ru505, and Z907 dyes. Furthermore, the NiNPs exhibited excellent resistance to corrosion from a conventional I-/I3- electrolyte over a period of 60 days.We demonstrated the localized surface plasmon resonance (LSPR) effect of Ni nanoparticles (NiNPs) on the performance of dye-sensitized solar cells (DSSCs). Our study revealed that NiNPs in a conventional I-/I3- electrolyte (NiNPs@I-/I3-) increased the net optical absorption of a N719 dye over a broad wavelength range by LSPR, and concurrently improved the power conversion efficiency (PCE) in DSSCs. At an optimized concentration of the NiNPs@I-/I3- electrolyte (1 mg mL-1), N719-sensitized DSSCs with a photoanode thickness of ca. 2, 5, and 10 μm, exhibited net PCEs of 2.32, 6.02, and 9.83%, respectively. These efficiencies were consistent with a net improvement of 43.2, 20.4, and 12.7%, respectively and were mainly attributed to a significant enhancement of the short circuit current density (Jsc) by the LSPR from the NiNPs. Similar effects were observed for cells sensitized by the N3, Ru505, and Z907 dyes. Furthermore, the NiNPs exhibited excellent resistance to corrosion from a conventional I-/I3- electrolyte over a period of 60 days. Electronic supplementary information (ESI) available: Details of the materials, optimization of the amount of NiNPs, and the stability of the devices. See DOI: 10.1039/c5nr08155f

Exploration of Piezoelectric Bimorph Deflection in Synthetic Jet Actuators

NASA Astrophysics Data System (ADS)

Housley, Kevin; Amitay, Michael

2017-11-01

The design of piezoelectric bimorphs for synthetic jet actuators could be improved by greater understanding of the deflection of the bimorphs; both their mode shapes and the resulting volume change inside the actuator. The velocity performance of synthetic jet actuators is dependent on this volume change and the associated internal pressure changes. Knowledge of these could aid in refining the geometry of the cavity to improve efficiency. Phase-locked jet velocities and maps of displacement of the surface of the bimorph were compared between actuators of varying diameter. Results from a bimorph of alternate stiffness were also compared. Bimorphs with higher stiffness exhibited a more desirable (0,1) mode shape, which produced a high volume change inside of the actuator cavity. Those with lower stiffness allowed for greater displacement of the surface, initially increasing the volume change, but exhibited higher mode shapes at certain frequency ranges. These higher node shapes sharply reduced the volume change and negatively impacted the velocity of the jet at those frequencies. Adjustments to the distribution of stiffness along the radius of the bimorph could prevent this and allow for improved deflection without the risk of reaching higher modes.

Carrier transport dynamics in Mn-doped CdSe quantum dot sensitized solar cells

NASA Astrophysics Data System (ADS)

Poudyal, Uma; Maloney, Francis S.; Sapkota, Keshab; Wang, Wenyong

2017-10-01

In this work quantum dot sensitized solar cells (QDSSCs) were fabricated with CdSe and Mn-doped CdSe quantum dots (QDs) using the SILAR method. QDSSCs based on Mn-doped CdSe QDs exhibited improved incident photon-to-electron conversion efficiency. Carrier transport dynamics in the QDSSCs were studied using the intensity modulated photocurrent/photovoltage spectroscopy technique, from which transport and recombination time constants could be derived. Compared to CdSe QDSSCs, Mn-CdSe QDSSCs exhibited shorter transport time constant, longer recombination time constant, longer diffusion length, and higher charge collection efficiency. These observations suggested that Mn doping in CdSe QDs could benefit the performance of solar cells based on such nanostructures.

In-situ synthesis of monodisperse micro-nanospherical LiFePO4/carbon cathode composites for lithium-ion batteries

NASA Astrophysics Data System (ADS)

Gong, Hao; Xue, Hairong; Wang, Tao; He, Jianping

2016-06-01

The LiFePO4 is recognized as the promising cathode material, due to its high specific capacity, excellent, structural stability and environmental benignity. However, it is blamed for the low tap density and poor rate performance when served as the cathode materials for a long time. Here, the microspheric LiFePO4/C composites are successfully synthesized through a one-step in-situ solvothermal method combined with carbothermic reduction. These LiFePO4/C microspheres are assembled by LiFePO4 nanoparticles (∼100 nm) and uniformly coated by the carbon, which show a narrow diameter distribution of 4 μm. As a cathode material for lithium ion batteries, the LiFePO4/C composites can deliver an initiate charge capacity of 155 mAh g-1 and retain 90% of initial capacity after 200 cycles at 0.1 C. When cycled at high current densities up to 20 C, it shows a discharge capacity of ∼60 mAh g-1, exhibiting superior rate performance. The significantly improved electrochemical performance of LiFePO4/C composites material can be attributed to its special micro-nano hierarchical structure. Microspheric LiFePO4/C composites exhibit a high tap density about 1.3 g cm-3. What's more, the well-coated carbon insures the high electrical conductivity and the nano-sized LiFePO4/C particles shorten lithium ion transport, thus exhibiting the high specific capacity, high cycling stability and good rate performance.

Effect of dietary coarsely ground corn on broiler live performance, gastrointestinal tract development, apparent ileal digestibility of energy and nitrogen, and digesta particle size distribution and retention time

PubMed Central

Xu, Y.; Stark, C. R.; Ferket, P. R.; Williams, C. M.; Pacheco, W. J.; Brake, J.

2015-01-01

Dietary structural material has been reported to improve broiler live performance and gastrointestinal tract (GIT) function. In this 50 d cage study, the effects of coarsely ground corn (CC) inclusion on broiler live performance, GIT development, apparent ileal digestibility (AID) of energy and nitrogen (N), and digesta particle size distribution and retention time were investigated. This study included 3 CC inclusions (0, 25, and 50% fine corn [FC] replaced by CC), with 6 replicate cages of 10 birds per treatment. The feed conversion ratio (FCR) at 35 and 42 d was improved (P < 0.01) as the dietary inclusion of CC increased without effect on feed intake. The 50% CC diet increased absolute and relative gizzard weight at 42 d of age as compared to diets with 0 and 25% CC (P < 0.01). Dietary CC increased absolute proventriculus weight at 28 d of age (P < 0.05). A numerically lower gizzard digesta pH (P < 0.08) was observed at 28 d but not 42 d of age, and there was no difference in proventriculus, jejunum, or ileum digesta pH at 28 or 42 d of age. The 25 and 50% CC treatments increased the digesta retention time at 30 and 45 d of age (P < 0.05 and P < 0.01, respectively). The 25 and 50% CC treatments improved AID of energy by 7.1 and 8.2%, respectively, when compared with the 0% CC treatment, and they improved AID of N by 12.2 and 12.4%, respectively (P < 0.01). The digesta particles in the jejunum exhibited a similar distribution, with a dgw (geometric mean diameter by mass) of 218, 204, and 181 μm when 0, 25, of 50% CC diets were consumed, respectively. In conclusion, birds fed pelleted and screened diets that contained 25 and 50% CC exhibited increased BW, improved FCR, and increased AID of energy and N, which was probably due to enhanced gizzard development and greater digesta retention time. PMID:25568134

Beliefs about willpower determine the impact of glucose on self-control.

PubMed

Job, Veronika; Walton, Gregory M; Bernecker, Katharina; Dweck, Carol S

2013-09-10

Past research found that the ingestion of glucose can enhance self-control. It has been widely assumed that basic physiological processes underlie this effect. We hypothesized that the effect of glucose also depends on people's theories about willpower. Three experiments, both measuring (experiment 1) and manipulating (experiments 2 and 3) theories about willpower, showed that, following a demanding task, only people who view willpower as limited and easily depleted (a limited resource theory) exhibited improved self-control after sugar consumption. In contrast, people who view willpower as plentiful (a nonlimited resource theory) showed no benefits from glucose--they exhibited high levels of self-control performance with or without sugar boosts. Additionally, creating beliefs about glucose ingestion (experiment 3) did not have the same effect as ingesting glucose for those with a limited resource theory. We suggest that the belief that willpower is limited sensitizes people to cues about their available resources including physiological cues, making them dependent on glucose boosts for high self-control performance.

Advanced Silicon-on-Insulator: Crystalline Silicon on Atomic Layer Deposited Beryllium Oxide.

PubMed

Min Lee, Seung; Hwan Yum, Jung; Larsen, Eric S; Chul Lee, Woo; Keun Kim, Seong; Bielawski, Christopher W; Oh, Jungwoo

2017-10-16

Silicon-on-insulator (SOI) technology improves the performance of devices by reducing parasitic capacitance. Devices based on SOI or silicon-on-sapphire technology are primarily used in high-performance radio frequency (RF) and radiation sensitive applications as well as for reducing the short channel effects in microelectronic devices. Despite their advantages, the high substrate cost and overheating problems associated with complexities in substrate fabrication as well as the low thermal conductivity of silicon oxide prevent broad applications of this technology. To overcome these challenges, we describe a new approach of using beryllium oxide (BeO). The use of atomic layer deposition (ALD) for producing this material results in lowering the SOI wafer production cost. Furthermore, the use of BeO exhibiting a high thermal conductivity might minimize the self-heating issues. We show that crystalline Si can be grown on ALD BeO and the resultant devices exhibit potential for use in advanced SOI technology applications.

High performance capacitive deionization using modified ZIF-8-derived, N-doped porous carbon with improved conductivity.

PubMed

Li, Yang; Kim, Jeonghun; Wang, Jie; Liu, Nei-Ling; Bando, Yoshio; Alshehri, Abdulmohsen Ali; Yamauchi, Yusuke; Hou, Chia-Hung; Wu, Kevin C-W

2018-06-05

Zeolitic imidazolate framework (ZIF) composite-derived carbon exhibiting large surface area and high micropore volume is demonstrated to be a promising electrode material for the capacitive deionization (CDI) application. However, some inherent serious issues (e.g., low electrical conductivity, narrow pore size, relatively low pore volume, etc.) are still observed for nitrogen-doped porous carbon particles, which restrict their CDI performance. To solve the above-mentioned problems, herein, we prepared gold-nanoparticle-embedded ZIF-8-derived nitrogen-doped carbon calcined at 800 °C (Au@NC800) and PEDOT doped-NC-800 (NC800-PEDOT). The newly generated NC800-PEDOT and Au@NC800 electrodes exhibited notably increased conductivity, and they also achieved high electrosorption capacities of 16.18 mg g-1 and 14.31 mg g-1, respectively, which were much higher than that of NC800 (8.36 mg g-1). Au@NC800 and NC800-PEDOT can be promisingly applicable as highly efficient CDI electrode materials.

Sputtered boron indium oxide thin-film transistors

NASA Astrophysics Data System (ADS)

Stewart, Kevin A.; Gouliouk, Vasily; Keszler, Douglas A.; Wager, John F.

2017-11-01

Boron indium oxide (BIO) is studied for thin-film transistor (TFT) channel layer applications. Sputtered BIO thin films exhibit an amorphous phase over a wide range of B2O3/In2O3 ratios and remain amorphous up to 500 °C. The band gap decreases linearly with decreasing boron content, whereas device performance generally improves with decreasing boron content. The best amorphous BIO TFT exhibits a field-effect mobility of 10 cm2 V-1 s-1, turn-on voltage of 2.5 V, and sub-threshold swing of 0.72 V/dec. Decreasing the boron content to 12.5% leads to a polycrystalline phase, but further increases the mobility up to 20-40 cm2 V-1 s-1. TCAD simulation results suggest that the reason for higher performance after increasing the anneal temperature from 200 to 400 °C is due to a lower defect density in the sub-bandgap region of the BIO channel layer.

Beliefs about willpower determine the impact of glucose on self-control

PubMed Central

Job, Veronika; Walton, Gregory M.; Bernecker, Katharina; Dweck, Carol S.

2013-01-01

Past research found that the ingestion of glucose can enhance self-control. It has been widely assumed that basic physiological processes underlie this effect. We hypothesized that the effect of glucose also depends on people’s theories about willpower. Three experiments, both measuring (experiment 1) and manipulating (experiments 2 and 3) theories about willpower, showed that, following a demanding task, only people who view willpower as limited and easily depleted (a limited resource theory) exhibited improved self-control after sugar consumption. In contrast, people who view willpower as plentiful (a nonlimited resource theory) showed no benefits from glucose—they exhibited high levels of self-control performance with or without sugar boosts. Additionally, creating beliefs about glucose ingestion (experiment 3) did not have the same effect as ingesting glucose for those with a limited resource theory. We suggest that the belief that willpower is limited sensitizes people to cues about their available resources including physiological cues, making them dependent on glucose boosts for high self-control performance. PMID:23959900

Carbon nanotubes-modified graphitic carbon nitride photocatalysts with synergistic effect of nickel(II) sulfide and molybdenum(II) disulfide co-catalysts for more efficient H2 evolution.

PubMed

Zhang, Yun-Xiao; Li, Kui; Yu, Yu-Xiang; Zhang, Wei-De

2018-09-15

This work reports effective photocatalysts which are composed of carbon nitride (CN), carbon nanotubes (CNTs), MoS 2 and NiS, for hydrogen evolution aiming at energy crises and environmental pollutions. The morphologies and optical properties of the photocatalysts were carefully characterized and their photocatalytic performance towards water reduction was studied afterwards. MoS 2 and NiS exhibit a significant synergistic effect working as co-catalysts. Compared to MoS 2 /CN nanohybrid, carbon nanotubes and NiS improved the absorption of visible light and the separation of charge carriers effectively. NiS-MoS 2 /CNTs/CN catalyst exhibits high performance for H 2 evolution and the optimized rate is 309.9 μmol·h -1 ·g -1 with no noble metals under visible light irradiation. The study demonstrates a non-noble metal photocatalyst system for effective generation of hydrogen with low cost. Copyright © 2018 Elsevier Inc. All rights reserved.

Adaptive strategies of remote systems operators exposed to perturbed camera-viewing conditions

NASA Technical Reports Server (NTRS)

Stuart, Mark A.; Manahan, Meera K.; Bierschwale, John M.; Sampaio, Carlos E.; Legendre, A. J.

1991-01-01

This report describes a preliminary investigation of the use of perturbed visual feedback during the performance of simulated space-based remote manipulation tasks. The primary objective of this NASA evaluation was to determine to what extent operators exhibit adaptive strategies which allow them to perform these specific types of remote manipulation tasks more efficiently while exposed to perturbed visual feedback. A secondary objective of this evaluation was to establish a set of preliminary guidelines for enhancing remote manipulation performance and reducing the adverse effects. These objectives were accomplished by studying the remote manipulator performance of test subjects exposed to various perturbed camera-viewing conditions while performing a simulated space-based remote manipulation task. Statistical analysis of performance and subjective data revealed that remote manipulation performance was adversely affected by the use of perturbed visual feedback and performance tended to improve with successive trials in most perturbed viewing conditions.

Sol-gel-processed yttrium-doped NiO as hole transport layer in inverted perovskite solar cells for enhanced performance

NASA Astrophysics Data System (ADS)

Hu, Zijun; Chen, Da; Yang, Pan; Yang, Lijun; Qin, Laishun; Huang, Yuexiang; Zhao, Xiaochong

2018-05-01

In this work, high-performance inverted planar perovskite solar cells (PSCs) using sol-gel processed Y-doped NiO thin films as hole transport layer (HTL) were demonstrated. Y-doped NiO thin films containing different Y doping concentrations were successfully prepared through a simple sol-gel process. The Y doping could significantly improve the electrical conductivity of NiO thin film, and the photovoltaic performance of Y-doped NiO HTL-based PSC devices outperformed that of the pristine NiO HTL-based device. Notably, the PSC using a 5%Y-NiO HTL exhibited the champion performance with an open-circuit voltage (Voc) of 1.00 V, a short circuit current density (Jsc) of 23.82 mA cm-2, a fill factor (FF) of 68% and a power conversion efficiency (PCE) of 16.31%, resulting in a 27.62% enhancement in PCE in comparison with the NiO device. The enhanced performance of the Y-doped NiO device could be attributed to the improved hole mobility, the high quality compact active layer morphology, the more efficient charge extraction from perovskite absorber as well as the lower recombination probability of charge carriers. Thus, this work provides a simple and effective approach to improve the electrical conductivity of p-type NiO thin films for use as a promising HTL in high performance PSCs.

Improved signal processing approaches in an offline simulation of a hybrid brain–computer interface

PubMed Central

Brunner, Clemens; Allison, Brendan Z.; Krusienski, Dean J.; Kaiser, Vera; Müller-Putz, Gernot R.; Pfurtscheller, Gert; Neuper, Christa

2012-01-01

In a conventional brain–computer interface (BCI) system, users perform mental tasks that yield specific patterns of brain activity. A pattern recognition system determines which brain activity pattern a user is producing and thereby infers the user’s mental task, allowing users to send messages or commands through brain activity alone. Unfortunately, despite extensive research to improve classification accuracy, BCIs almost always exhibit errors, which are sometimes so severe that effective communication is impossible. We recently introduced a new idea to improve accuracy, especially for users with poor performance. In an offline simulation of a “hybrid” BCI, subjects performed two mental tasks independently and then simultaneously. This hybrid BCI could use two different types of brain signals common in BCIs – event-related desynchronization (ERD) and steady-state evoked potentials (SSEPs). This study suggested that such a hybrid BCI is feasible. Here, we re-analyzed the data from our initial study. We explored eight different signal processing methods that aimed to improve classification and further assess both the causes and the extent of the benefits of the hybrid condition. Most analyses showed that the improved methods described here yielded a statistically significant improvement over our initial study. Some of these improvements could be relevant to conventional BCIs as well. Moreover, the number of illiterates could be reduced with the hybrid condition. Results are also discussed in terms of dual task interference and relevance to protocol design in hybrid BCIs. PMID:20153371

Resistance training with creatine monohydrate improves upper-body strength in patients with Parkinson disease: a randomized trial.

PubMed

Hass, Chris J; Collins, Mitchell A; Juncos, Jorge L

2007-01-01

Persons with Parkinson disease (PD) exhibit decreased muscular fitness including decreased muscle mass, muscle strength, bioenergetic capabilities and increased fatigability. This purpose of this investigation was to evaluate the therapeutic effects of resistance training with and without creatine supplementation in patients with mild to moderate PD. Twenty patients with idiopathic PD were randomized to receive creatine monohydrate supplementation plus resistance training (CRE) or placebo (lactose monohydrate) plus resistance training (PLA), using a double-blind procedure. Creatine and placebo supplementation consisted of 20 g/d for the first 5 days and 5 g/d thereafter. Both groups participated in progressive resistance training (24 sessions, 2 times per week, 1 set of 8-12 repetitions, 9 exercises). Participants performed 1-repetition maximum (1-RM) for chest press, leg extension, and biceps curl. Muscular endurance was evaluated for chest press and leg extension as the number of repetitions to failure using 60% of baseline 1-RM. Functional performance was evaluated as the time to perform 3 consecutive chair rises. Statistical analyses (ANOVA) revealed significant Group x Time interactions for chest press strength and biceps curl strength, and post hoc testing revealed that the improvement was significantly greater for CRE. Chair rise performance significantly improved only for CRE (12%, P=.03). Both PLA and CRE significantly improved 1-RM for leg extension (PLA: 16%; CRE: 18%). Muscular endurance improved significantly for both groups. These findings demonstrate that creatine supplementation can enhance the benefits of resistance training in patients with PD.

1D and 2D oxidized carbon nanomaterials on epoxy matrix: performance of composites over the same processing conditions

NASA Astrophysics Data System (ADS)

Ramos-Galicia, Lourdes; Martinez-Hernandez, Ana Laura; Fuentes-Ramirez, Rosalba; Velasco-Santos, Carlos

2017-11-01

Oxidized multi-walled carbon nanotubes and graphene oxide were evaluated as reinforcements of an epoxy resin. The composites were synthesized at concentrations of 0.1, 0.5, and 1.0 wt% under the same processing conditions. Nanocomposites with graphene oxide at 0.5 wt% present the highest mechanical properties, reaching up to ~180%, and ~760% of improvement in tensile strength and tensile toughness with respect to neat epoxy. Nevertheless, composites with oxidized nanotubes exhibit a tendency to improve mechanical properties as load increases. Storage moduli diminish due to cross-linking density reduction in all nanocomposites. Difference in thermal degradation are not observed in composites in comparison with matrix. Dimension play an important role in mechanical properties, because each nanoreinforcement has different performance with the concentration.

Graphene quantum dots-three-dimensional graphene composites for high-performance supercapacitors.

PubMed

Chen, Qing; Hu, Yue; Hu, Chuangang; Cheng, Huhu; Zhang, Zhipan; Shao, Huibo; Qu, Liangti

2014-09-28

Graphene quantum dots (GQDs) have been successfully deposited onto the three-dimensional graphene (3DG) by a benign electrochemical method and the ordered 3DG structure remains intact after the uniform deposition of GQDs. In addition, the capacitive properties of the as-formed GQD-3DG composites are evaluated in symmetrical supercapacitors. It is found that the supercapacitor fabricated from the GQD-3DG composite is highly stable and exhibits a high specific capacitance of 268 F g(-1), representing a more than 90% improvement over that of the supercapacitor made from pure 3DG electrodes (136 F g(-1)). Owing to the convenience of the current method, it can be further used in other well-defined electrode materials, such as carbon nanotubes, carbon aerogels and conjugated polymers to improve the performance of the supercapacitors.

Mosaic-shaped cathode for highly durable solid oxide fuel cell under thermal stress

NASA Astrophysics Data System (ADS)

Joo, Jong Hoon; Jeong, Jaewon; Kim, Se Young; Yoo, Chung-Yul; Jung, Doh Won; Park, Hee Jung; Kwak, Chan; Yu, Ji Haeng

2014-02-01

In this study, we propose a novel "mosaic structure" for a SOFC (solid oxide fuel cell) cathode with high thermal expansion to improve the stability against thermal stress. Self-organizing mosaic-shaped cathode has been successfully achieved by controlling the amount of binder in the dip-coating solution. The anode-supported cell with mosaic-shaped cathode shows itself to be highly durable performance for rapid thermal cycles, however, the performance of the cell with a non-mosaic cathode exhibits severe deterioration originated from the delamination at the cathode/electrolyte interface after 7 thermal cycles. The thermal stability of an SOFC cathode can be evidently improved by controlling the surface morphology. In view of the importance of the thermal expansion properties of the cathode, the effects of cathode morphology on the thermal stress stability are discussed.

Improved cache performance in Monte Carlo transport calculations using energy banding

NASA Astrophysics Data System (ADS)

Siegel, A.; Smith, K.; Felker, K.; Romano, P.; Forget, B.; Beckman, P.

2014-04-01

We present an energy banding algorithm for Monte Carlo (MC) neutral particle transport simulations which depend on large cross section lookup tables. In MC codes, read-only cross section data tables are accessed frequently, exhibit poor locality, and are typically too much large to fit in fast memory. Thus, performance is often limited by long latencies to RAM, or by off-node communication latencies when the data footprint is very large and must be decomposed on a distributed memory machine. The proposed energy banding algorithm allows maximal temporal reuse of data in band sizes that can flexibly accommodate different architectural features. The energy banding algorithm is general and has a number of benefits compared to the traditional approach. In the present analysis we explore its potential to achieve improvements in time-to-solution on modern cache-based architectures.

A strategy to improve the energy conversion efficiency and stability of quantum dot-sensitized solar cells using manganese-doped cadmium sulfide quantum dots.

PubMed

Gopi, Chandu V V M; Venkata-Haritha, M; Kim, Soo-Kyoung; Kim, Hee-Je

2015-01-14

This article describes the effect of manganese (Mn) doping in CdS to improve the photovoltaic performance of quantum dot sensitized solar cells (QDSSCs). The performances of the QDSSCs are examined in detail using a polysulfide electrolyte with a copper sulfide (CuS) counter electrode. Under the illumination of one sun (AM 1.5 G, 100 mW cm(-2)), 10 molar% Mn-doped CdS QDSSCs exhibit a power conversion efficiency (η) of 2.85%, which is higher than the value of 2.11% obtained with bare CdS. The improved photovoltaic performance is due to the impurities from Mn(2+) doping of CdS, which have an impact on the structure of the host material and decrease the surface roughness. The surface roughness and morphology of Mn-doped CdS nanoparticles can be characterised from atomic force microscopy images. Furthermore, the cell device based on the Mn-CdS electrode shows superior stability in the sulfide/polysulfide electrolyte in a working state for over 10 h, resulting in a highly reproducible performance, which is a serious challenge for the Mn-doped solar cell. Our finding provides an effective method for the fabrication of Mn-doped CdS QDs, which can pave the way to further improve the efficiency of future QDSSCs.

Incorporation of Aggrecan in Interpenetrating Network Hydrogels to Improve Cellular Performance for Cartilage Tissue Engineering

PubMed Central

Ingavle, Ganesh C.; Frei, Anthony W.; Gehrke, Stevin H.

2013-01-01

Interpenetrating network (IPN) hydrogels were recently introduced to the cartilage tissue engineering literature, with the approach of encapsulating cells in thermally gelling agarose that is then soaked in a poly(ethylene glycol) diacrylate (PEGDA) solution, which is then photopolymerized. These IPNs possess significantly enhanced mechanical performance desirable for cartilage regeneration, potentially allowing patients to return to weight-bearing activities quickly after surgical implantation. In an effort to improve cell viability and performance, inspiration was drawn from previous studies that have elicited positive chondrogenic responses to aggrecan, the proteoglycan largely responsible for the compressive stiffness of cartilage. Aggrecan was incorporated into the IPNs in conservative concentrations (40 μg/mL), and its effect was contrasted with the incorporation of chondroitin sulfate (CS), the primary glycosaminoglycan associated with aggrecan. Aggrecan was incorporated by physical entrapment within agarose and methacrylated CS was incorporated by copolymerization with PEGDA. The IPNs incorporating aggrecan or CS exhibited over 50% viability with encapsulated chondrocytes after 6 weeks. Both aggrecan and CS improved cell viability by 15.6% and 20%, respectively, relative to pure IPNs at 6 weeks culture time. In summary, we have introduced the novel approach of including a raw material from cartilage, namely aggrecan, to serve as a bioactive signal to cells encapsulated in IPN hydrogels for cartilage tissue engineering, which led to improved performance of encapsulated chondrocytes. PMID:23379843

Improved high-temperature resistant matrix resins

NASA Technical Reports Server (NTRS)

Green, H. E.; Chang, G. E.; Wright, W. F.; Ueda, K.; Orell, M. K.

1989-01-01

A study was performed with the objective of developing matrix resins that exhibit improved thermo-oxidative stability over state-of-the-art high temperature resins for use at temperatures up to 644 K (700 F) and air pressures up to 0.7 MPa (100 psia). The work was based upon a TRW discovered family of polyimides currently licensed to and marketed by Ethyl Corporation as EYMYD(R) resins. The approach investigated to provide improved thermo-oxidative properties was to use halogenated derivatives of the diamine, 2, 2-bis (4-(4-aminophenoxy)phenyl) hexafluoropropane (4-BDAF). Polyimide neat resins and Celion(R) 12,000 composites prepared from fluorine substituted 4-BDAF demonstrated unexpectedly lower glass transition temperatures (Tg) and thermo-oxidative stabilities than the baseline 4-BDAF/PMDA polymer.

Combination of Xylanase and Debranching Enzymes Specific to Wheat Arabinoxylan Improve the Growth Performance and Gut Health of Broilers.

PubMed

Lei, Zhao; Shao, Yuxin; Yin, Xiaonan; Yin, Dafei; Guo, Yuming; Yuan, Jianmin

2016-06-22

Arabinoxylan (AX) is the major antinutritional factor of wheat. This study evaluated the synergistic effects of xylanase and debranching enzymes (arabinofuranosidase [ABF] and feruloyl esterase [FAE]) on AX. During in vitro tests, the addition of ABF or FAE accelerated the hydrolysis of water-soluble AX (WE-AX) and water-insoluble AX (WU-AX) and produced more xylan oligosaccharides (XOS) than xylanase alone. XOS obtained from WE-AX stimulated greater proliferation of Lactobacillus brevis and Bacillus subtilis than did fructo-oligosaccharides (FOS) and glucose. During in vivo trials, xylanase increased the average daily growth (ADG), decreased the feed-conversion ratio (FCR), and reduced the digesta viscosity of jejunum and intestinal lesions of broilers fed a wheat-based diet on day 36. ABF or FAE additions further improved these effects. Broilers fed a combination of xylanase, ABF, and FAE exhibited the best growth. In conclusion, the synergistic effects among xylanase, ABF, and FAE increased AX degradation, which improve the growth performance and gut health of broilers.

Efficient hydrogen evolution in transition metal dichalcogenides via a simple one-step hydrazine reaction

PubMed Central

Cummins, Dustin R.; Martinez, Ulises; Sherehiy, Andriy; Kappera, Rajesh; Martinez-Garcia, Alejandro; Schulze, Roland K.; Jasinski, Jacek; Zhang, Jing; Gupta, Ram K.; Lou, Jun; Chhowalla, Manish; Sumanasekera, Gamini; Mohite, Aditya D.; Sunkara, Mahendra K.; Gupta, Gautam

2016-01-01

Hydrogen evolution reaction is catalysed efficiently with precious metals, such as platinum; however, transition metal dichalcogenides have recently emerged as a promising class of materials for electrocatalysis, but these materials still have low activity and durability when compared with precious metals. Here we report a simple one-step scalable approach, where MoOx/MoS2 core-shell nanowires and molybdenum disulfide sheets are exposed to dilute aqueous hydrazine at room temperature, which results in marked improvement in electrocatalytic performance. The nanowires exhibit ∼100 mV improvement in overpotential following exposure to dilute hydrazine, while also showing a 10-fold increase in current density and a significant change in Tafel slope. In situ electrical, gate-dependent measurements and spectroscopic investigations reveal that hydrazine acts as an electron dopant in molybdenum disulfide, increasing its conductivity, while also reducing the MoOx core in the core-shell nanowires, which leads to improved electrocatalytic performance. PMID:27282871

Metal segregation in hierarchically structured cathode materials for high-energy lithium batteries

DOE PAGES

Lin, Feng; Xin, Huolin L.; Nordlund, Dennis; ...

2016-01-11

Controlling surface and interfacial properties of battery materials is key to improving performance in rechargeable Li-ion devices. Surface reconstruction from a layered to a rock salt structure in metal oxide cathode materials is commonly observed and results in poor high-voltage cycling performance, impeding attempts to improve energy density. Hierarchically structured LiNi 0.4Mn 0.4Co 0.2O 2 (NMC-442) spherical powders, made by spray pyrolysis, exhibit local elemental distribution gradients that deviate from the global NMC-442 composition; specifically, they are Ni-rich and Mn-poor at particle surfaces. These materials demonstrate improved Coulombic efficiencies, discharge capacities, and high-voltage capacity retention in lithium half-cell configurations. Themore » subject powders show superior resistance against surface reconstruction due to the tailored surface chemistry, compared to conventional NMC-442 materials. This paves the way towards the development of a new generation of robust and stable high-energy NMC cathodes for Li-ion batteries.« less

Efficient hydrogen evolution in transition metal dichalcogenides via a simple one-step hydrazine reaction.

PubMed

Cummins, Dustin R; Martinez, Ulises; Sherehiy, Andriy; Kappera, Rajesh; Martinez-Garcia, Alejandro; Schulze, Roland K; Jasinski, Jacek; Zhang, Jing; Gupta, Ram K; Lou, Jun; Chhowalla, Manish; Sumanasekera, Gamini; Mohite, Aditya D; Sunkara, Mahendra K; Gupta, Gautam

2016-06-10

Hydrogen evolution reaction is catalysed efficiently with precious metals, such as platinum; however, transition metal dichalcogenides have recently emerged as a promising class of materials for electrocatalysis, but these materials still have low activity and durability when compared with precious metals. Here we report a simple one-step scalable approach, where MoOx/MoS2 core-shell nanowires and molybdenum disulfide sheets are exposed to dilute aqueous hydrazine at room temperature, which results in marked improvement in electrocatalytic performance. The nanowires exhibit ∼100 mV improvement in overpotential following exposure to dilute hydrazine, while also showing a 10-fold increase in current density and a significant change in Tafel slope. In situ electrical, gate-dependent measurements and spectroscopic investigations reveal that hydrazine acts as an electron dopant in molybdenum disulfide, increasing its conductivity, while also reducing the MoOx core in the core-shell nanowires, which leads to improved electrocatalytic performance.

Biofouling behavior and performance of forward osmosis membranes with bioinspired surface modification in osmotic membrane bioreactor.

PubMed

Li, Fang; Cheng, Qianxun; Tian, Qing; Yang, Bo; Chen, Qianyuan

2016-07-01

Forward osmosis (FO) has received considerable interest for water and energy related applications in recent years. Biofouling behavior and performance of cellulose triacetate (CTA) forward osmosis membranes with bioinspired surface modification via polydopamine (PD) coating and poly (ethylene glycol) (PEG) grafting (PD-g-PEG) in a submerged osmotic membrane bioreactor (OMBR) were investigated in this work. The modified membranes exhibited lower flux decline than the pristine one in OMBR, confirming that the bioinspired surface modification improved the antifouling ability of the CTA FO membrane. The result showed that the decline of membrane flux related to the increase of the salinity and MLSS concentration of the mixed liquid. It was concluded that the antifouling ability of modified membranes ascribed to the change of surface morphology in addition to the improvement of membrane hydrophilicity. The bioinspired surface modifications might improve the anti-adhesion for the biopolymers and biocake. Copyright © 2016 Elsevier Ltd. All rights reserved.

Efficient hydrogen evolution in transition metal dichalcogenides via a simple one-step hydrazine reaction

DOE PAGES

Cummins, Dustin R.; Martinez, Ulises; Sherehiy, Andriy; ...

2016-06-10

In this study, hydrogen evolution reaction is catalyzed efficiently with precious metals, such as platinum; however, transition metal dichalcogenides have recently emerged as a promising class of materials for electrocatalysis, but these materials still have low activity and durability when compared with precious metals. Here we report a simple one-step scalable approach, where MoO x/MoS 2 core-shell nanowires and molybdenum disulfide sheets are exposed to dilute aqueous hydrazine at room temperature, which results in marked improvement in electrocatalytic performance. The nanowires exhibit ~100 mV improvement in over potential following exposure to dilute hydrazine, while also showing a 10-fold increase inmore » current density and a significant change in Tafel slope. In situ electrical, gate-dependent measurements and spectroscopic investigations reveal that hydrazine acts as an electron dopant in molybdenum disulfide, increasing its conductivity, while also reducing the MoO x core in the core-shell nanowires, which leads to improved electrocatalytic performance.« less

Heterogeneous nanocrystals assembled TiO2/SnO2/C composite for improved lithium storage

NASA Astrophysics Data System (ADS)

Tian, Qinghua; Mao, Yuning; Zhang, Xuzhen; Yang, Li

2018-07-01

Using stable TiO2 and flexible carbon as double-functional structure protector of nanostructural SnO2 to fabricate TiO2/SnO2/C composites is widely considered as a favorable strategy for improving the lithium storage performance of SnO2 anodes. But, it is still a challenge to obtain a satisfying TiO2/SnO2/C composite. Herein, an interesting porous nanostructure of TiO2/SnO2/C nanosphere composite assembled by TiO2 and SnO2 nanocrystals with an outer carbon coating has been fabricated by a well-designed approach. Thanks to the perfectly combined action of porous spherical nanostructure, TiO2 and SnO2 nanocrystals and carbon coating, the as-prepared composite obtains excellent structure stability and improved electrochemcial properties. When used as a promising anode for lithium-ion batteres, it exhibits outstanding lithium storage performance, delivering a high capacity of 687.2 mAh g-1 after even 400 cycles.

Effect of sandblasting intensity on microstructures and properties of pure titanium micro-arc oxidation coatings in an optimized composite technique

NASA Astrophysics Data System (ADS)

Wang, Hong-Yuan; Zhu, Rui-Fu; Lu, Yu-Peng; Xiao, Gui-Yong; He, Kun; Yuan, Y. F.; Ma, Xiao-Ni; Li, Ying

2014-02-01

Sandblasting is one of the most effective methods to modify a metal surface and improve its properties for application. Micro-arc oxidation (MAO) could produce a ceramic coating on a dental implant, facilitating cellular differentiation and osseocomposite on it. This study aims to deposit bioceramic Ca- and P-containing coatings on sandblasted commercially pure titanium by an optimum composite technique to improve the bioactive performance. The effect of sandblasting intensity on microstructures and properties of the implant coatings is examined, and the modified surfaces are characterized in terms of their topography, phase, chemical composition, mechanical properties and hydroxyapatite (HA)-inducing ability. The results show that a moderate sandblasting micromachines the substrate in favorable combination of rough and residual stresses; its MAO coating deposits nano-hydroxyapatite after immersion in simulated body fluid (SBF) for 5 days exhibiting better bioactivity. The further improvement of the implant surface performance is attributed to an optimized composite technique.

International Infantry and Joint Services Small Arms Systems Symposium: Exhibition and Firing Demonstration

DTIC Science & Technology

2008-05-22

operation of weapon system) Phit Weapon System (e.g. dispersion) Most important influence ● Operator ● Distance to target together with ballistic...Suitable for a variety of weapons where ballistical correction to improve range performance and PHit /PKill is essential ● Prepare system for additional...status ● Prototypes have been delivered to FMV (Swedish Defence Materiel Administration) ● Demonstrated for NATO in Toledo 2007-02-15: > 65% PHit

Oxidatively stable fluorinated sulfone electrolytes for high voltage high energy lithium-ion batteries

DOE PAGES

Su, Chi -Cheung; He, Meinan; Redfern, Paul C.; ...

2017-03-16

New fluorinated sulfones were synthesized and evaluated in high voltage lithium-ion batteries using LiNi 0.5Mn 1.5O 4 (LNMO) cathode. Fluorinated sulfones with an α-trifluoromethyl group exhibit enhanced oxidation stability, reduced viscosity and superior separator wettability as compared to their non-fluorinated counterparts. Finally, the improved performance in high voltage cells makes it a promising high voltage electrolyte for 5-V lithium-ion chemistry.

7 CFR Exhibit G to Subpart A of... - Performance Bond

Code of Federal Regulations, 2012 CFR

2012-01-01

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7 CFR Exhibit G to Subpart A of... - Performance Bond

Code of Federal Regulations, 2010 CFR

2010-01-01

... 7 Agriculture 12 2010-01-01 2010-01-01 false Performance Bond G Exhibit G to Subpart A of Part.... 1924, Subpt. A, Exh. G Exhibit G to Subpart A of Part 1924—Performance Bond KNOW ALL PERSONS BY THESE... and faithful performance of the CONTRACT as so amended. The term “Amendment”, wherever used in this...

7 CFR Exhibit G to Subpart A of... - Performance Bond

Code of Federal Regulations, 2011 CFR

2011-01-01

... 7 Agriculture 12 2011-01-01 2011-01-01 false Performance Bond G Exhibit G to Subpart A of Part.... 1924, Subpt. A, Exh. G Exhibit G to Subpart A of Part 1924—Performance Bond KNOW ALL PERSONS BY THESE... and faithful performance of the CONTRACT as so amended. The term “Amendment”, wherever used in this...

7 CFR Exhibit G to Subpart A of... - Performance Bond

Code of Federal Regulations, 2014 CFR

2014-01-01

... 7 Agriculture 12 2014-01-01 2013-01-01 true Performance Bond G Exhibit G to Subpart A of Part 1924.... A, Exh. G Exhibit G to Subpart A of Part 1924—Performance Bond KNOW ALL PERSONS BY THESE PRESENTS... and faithful performance of the CONTRACT as so amended. The term “Amendment”, wherever used in this...

Interface-designed Membranes with Shape-controlled Patterns for High-performance Polymer Electrolyte Membrane Fuel Cells

PubMed Central

Jeon, Yukwon; Kim, Dong Jun; Koh, Jong Kwan; Ji, Yunseong; Kim, Jong Hak; Shul, Yong-Gun

2015-01-01

Polymer electrolyte membrane fuel cell is a promising zero-emission power generator for stationary/automotive applications. However, key issues, such as performance and costs, are still remained for an economical commercialization. Here, we fabricated a high-performance membrane electrode assembly (MEA) using an interfacial design based on well-arrayed micro-patterned membranes including circles, squares and hexagons with different sizes, which are produced by a facile elastomeric mold method. The best MEA performance is achieved using patterned Nafion membrane with a circle 2 μm in size, which exhibited a very high power density of 1906 mW/cm2 at 75 °C and Pt loading of 0.4 mg/cm2 with 73% improvement compared to the commercial membrane. The improved performance are attributed to the decreased MEA resistances and increased surface area for higher Pt utilization of over 80%. From these enhanced properties, it is possible to operate at lower Pt loading of 0.2 mg/cm2 with an outstanding performance of 1555 mW/cm2 and even at air/low humidity operations. PMID:26552839

Investigation of the mediating effects of IT governance-value delivery on service quality and ERP performance

NASA Astrophysics Data System (ADS)

Tsai, Wen-Hsien; Chou, Yu-Wei; Leu, Jun-Der; Chao Chen, Der; Tsaur, Tsen-Shu

2015-02-01

This study aimed to explore the mediating effects of IT governance (ITG)-value delivery in the relationships among the quality of vendor service, the quality of consultant services, ITG-value delivery and enterprise resource planning (ERP) performance. The sampling of this research was acquired from a questionnaire survey concerning ERP implementations in Taiwan. In this survey, 4366 questionnaires were sent to manufacturing and service companies listed in the TOP 5000: The Largest Corporations in Taiwan 2009. The results showed that an ERP system will exhibit a decreased error rate and improved performance if ERP system vendors and consultants provide good service quality. The results also demonstrated that significant relationships exist among the quality of vendor service, the quality of consultant services and value delivery. The contribution of this article is twofold. First, it found that value delivery provides an effective measure of ERP performance under an ITG framework. Second, it provides evidence of the partial mediating effects of value delivery between service quality and ERP performance. In other words, if enterprises want to improve ERP performance, they need to consider factors such as value delivery and the quality of a vendor/consultant's service.

Improving performances of suboptimal greedy iterative biclustering heuristics via localization.

PubMed

Erten, Cesim; Sözdinler, Melih

2010-10-15

Biclustering gene expression data is the problem of extracting submatrices of genes and conditions exhibiting significant correlation across both the rows and the columns of a data matrix of expression values. Even the simplest versions of the problem are computationally hard. Most of the proposed solutions therefore employ greedy iterative heuristics that locally optimize a suitably assigned scoring function. We provide a fast and simple pre-processing algorithm called localization that reorders the rows and columns of the input data matrix in such a way as to group correlated entries in small local neighborhoods within the matrix. The proposed localization algorithm takes its roots from effective use of graph-theoretical methods applied to problems exhibiting a similar structure to that of biclustering. In order to evaluate the effectivenesss of the localization pre-processing algorithm, we focus on three representative greedy iterative heuristic methods. We show how the localization pre-processing can be incorporated into each representative algorithm to improve biclustering performance. Furthermore, we propose a simple biclustering algorithm, Random Extraction After Localization (REAL) that randomly extracts submatrices from the localization pre-processed data matrix, eliminates those with low similarity scores, and provides the rest as correlated structures representing biclusters. We compare the proposed localization pre-processing with another pre-processing alternative, non-negative matrix factorization. We show that our fast and simple localization procedure provides similar or even better results than the computationally heavy matrix factorization pre-processing with regards to H-value tests. We next demonstrate that the performances of the three representative greedy iterative heuristic methods improve with localization pre-processing when biological correlations in the form of functional enrichment and PPI verification constitute the main performance criteria. The fact that the random extraction method based on localization REAL performs better than the representative greedy heuristic methods under same criteria also confirms the effectiveness of the suggested pre-processing method. Supplementary material including code implementations in LEDA C++ library, experimental data, and the results are available at http://code.google.com/p/biclustering/ cesim@khas.edu.tr; melihsozdinler@boun.edu.tr Supplementary data are available at Bioinformatics online.

The effect of restructuring student writing in the general chemistry laboratory on student understanding of chemistry and on students' approach to the laboratory course

NASA Astrophysics Data System (ADS)

Rudd, James Andrew, II

Many students encounter difficulties engaging with laboratory-based instruction, and reviews of research have indicated that the value of such instruction is not clearly evident. Traditional forms of writing associated with laboratory activities are commonly in a style used by professional scientists to communicate developed explanations. Students probably lack the interpretative skills of a professional, and writing in this style may not support students in learning how to develop scientific explanations. The Science Writing Heuristic (SWH) is an inquiry-based approach to laboratory instruction designed in part to promote student ability in developing such explanations. However, there is not a convincing body of evidence for the superiority of inquiry-based laboratory instruction in chemistry. In a series of studies, the performance of students using the SWH student template in place of the standard laboratory report format was compared to the performance of students using the standard format. The standard reports had Title, Purpose, Procedure, Data & Observations, Calculations & Graphs, and Discussion sections. The SWH reports had Beginning Questions & Ideas, Tests & Procedures, Observations, Claims, Evidence, and Reflection sections. The pilot study produced evidence that using the SWH improved the quality of laboratory reports, improved student performance on a laboratory exam, and improved student approach to laboratory work. A main study found that SWH students statistically exhibited a better understanding of physical equilibrium when written explanations and equations were analyzed on a lecture exam and performed descriptively better on a physical equilibrium practical exam task. In another main study, the activities covering the general equilibrium concept were restructured as an additional change, and it was found that SWH students exhibited a better understanding of chemical equilibrium as shown by statistically greater success in overcoming the common confusion of interpreting equilibrium as equal concentrations and by statistically better performance when explaining aspects of chemical equilibrium. Both main studies found that students and instructors spent less time on the SWH reports and that students preferred the SWH approach because it increased their level of mental engagement. The studies supported the conclusion that inquiry-based laboratory instruction benefits student learning and attitudes.

Role of multiple representations in physics problem solving

NASA Astrophysics Data System (ADS)

Maries, Alexandru

This thesis explores the role of multiple representations in introductory physics students' problem solving performance through several investigations. Representations can help students focus on the conceptual aspects of physics and play a major role in effective problem solving. Diagrammatic representations can play a particularly important role in the initial stages of conceptual analysis and planning of the problem solution. Findings suggest that students who draw productive diagrams are more successful problem solvers even if their approach is primarily mathematical. Furthermore, students provided with a diagram of the physical situation presented in a problem sometimes exhibited deteriorated performance. Think-aloud interviews suggest that this deteriorated performance is in part due to reduced conceptual planning time which caused students to jump to the implementation stage without fully understanding the problem and planning problem solution. Another study investigated two interventions aimed at improving introductory students' representational consistency between mathematical and graphical representations and revealed that excessive scaffolding can have a detrimental effect. The detrimental effect was partly due to increased cognitive load brought on by the additional steps and instructions. Moreover, students who exhibited representational consistency also showed improved problem solving performance. The final investigation is centered on a problem solving task designed to provide information about the pedagogical content knowledge (PCK) of graduate student teaching assistants (TAs). In particular, the TAs identified what they considered to be the most common difficulties of introductory physics students related to graphical representations of kinematics concepts as they occur in the Test of Understanding Graphs in Kinematics (TUG-K). As an extension, the Force Concept Inventory (FCI) was also used to assess this aspect of PCK related to knowledge of student difficulties of both physics instructors and TAs. We find that teaching an independent course and recent teaching experience do not correlate with improved PCK. In addition, the performance of American TAs, Chinese TAs and other foreign TAs in identifying common student difficulties both in the context of the TUG-K and in the context of the FCI is similar. Moreover, there were many common difficulties of introductory physics students that were not identified by many instructors and TAs.

Incorporation of Nicotine into Silicone Coatings for Marine Applications

NASA Astrophysics Data System (ADS)

Jaramillo, Sandy Tuyet

PDMS-based marine coatings presently used are limited by their inability to mitigate microfouling which limits their application to high speed vessels. PDMS coatings are favored when viable, due to their foul release properties of macrofouling organisms. Natural products have been investigated for antifouling properties for potential use in these marine antifouling coatings but few have incorporated natural products into coatings or coating systems. The purpose of the research was to establish the corrosion inhibiting properties of nicotine and to incorporate nicotine, a biodegradable and readily available natural product, into a PDMS coating to demonstrate the use of a natural product in a coating for marine applications. The corrosion inhibiting properties of nicotine was examined using potentiodynamic polarization scans, material characterization techniques such as scanning electron microscopy, energy dispersive spectroscopy and X-ray diffraction, quartz crystal microbalance and electrochemical impedance spectroscopy. Nicotine was determined to be an anodic corrosion inhibitor for mild steel immersed in simulated seawater with the ability to precipitate a protective calcium carbonate film. Electrochemical impedance spectroscopy was used to evaluate the performance of the developed nicotine incorporated coatings on mild steel immersed in simulated seawater over 21 days of immersion. The coatings with 2 wt.% of nicotine incorporated in the coating with a ratio of 1:30 of additional platinum catalyst to nicotine exhibited the best performance for intact coatings. This coating had the most favorable balance of the amount of nicotine and platinum catalyst of all the coatings evaluated. Overall, all nicotine incorporated coatings had a performance improvement when compared to the control PDMS coating. Of the nicotine incorporated coatings that were tested with an artificial pin-hole defect, the 2PDMS coating also exhibited the best performance with significant improvement in the pore and polarization resistance.

Regional Variation in Antenatal Corticosteroid Use: A Network-Level Quality Improvement Study

PubMed Central

Goldstein, B.A.; Tamaresis, J.; Kan, P.; Lee, H.C.

2015-01-01

BACKGROUND AND OBJECTIVES: Examination of regional care patterns in antenatal corticosteroid use (ACU) rates may be salient for the development of targeted interventions. Our objective was to assess network-level variation using California perinatal care regions as a proxy. We hypothesized that (1) significant variation in ACU exists within and between California perinatal care regions, and (2) lower performing regions exhibit greater NICU-level variability in ACU than higher performing regions. METHODS: We undertook cross-sectional analysis of 33 610 very low birth weight infants cared for at 120 hospitals in 11 California perinatal care regions from 2005 to 2011. We computed risk-adjusted median ACU rates and interquartile ranges (IQR) for each perinatal care region. The degree of variation was assessed using hierarchical multivariate regression analysis with NICU as a random effect and region as a fixed effect. RESULTS: From 2005 to 2011, mean ACU rates across California increased from 82% to 87.9%. Regional median (IQR) ACU rates ranged from 68.4% (24.3) to 92.9% (4.8). We found significant variation in ACU rates among regions (P < .0001). Compared with Level IV NICUs, care in a lower level of care was a strongly significant predictor of lower odds of receiving antenatal corticosteroids in a multilevel model (Level III, 0.65 [0.45–0.95]; Level II, 0.39 [0.24–0.64]; P < .001). Regions with lower performance in ACU exhibited greater variability in performance. CONCLUSIONS: We found significant variation in ACU rates among California perinatal regions. Regional quality improvement approaches may offer a new avenue to spread best practice. PMID:25601974

Improving TWSTFT short-term stability by network time transfer.

PubMed

Tseng, Wen-Hung; Lin, Shinn-Yan; Feng, Kai-Ming; Fujieda, M; Maeno, H

2010-01-01

Two-way satellite time and frequency transfer (TWSTFT) is one of the major techniques to compare the atomic time scales between timing laboratories. As more and more TWSTFT measurements have been performed, the large number of point-to-point 2-way time transfer links has grown to be a complex network. For future improvement of the TWSTFT performance, it is important to reduce measurement noise of the TWSTFT results. One method is using TWSTFT network time transfer. The Asia-Pacific network is an exceptional case of simultaneous TWSTFT measurements. Some indirect links through relay stations show better shortterm stabilities than the direct link because the measurement noise may be neutralized in a simultaneous measurement network. In this paper, the authors propose a feasible method to improve the short-term stability by combining the direct and indirect links in the network. Through the comparisons of time deviation (TDEV), the results of network time transfer exhibit clear improved short-term stabilities. For the links used to compare 2 hydrogen masers, the average gain of TDEV at averaging times of 1 h is 22%. As TWSTFT short-term stability can be improved by network time transfer, the network may allow a larger number of simultaneously transmitting stations.

The all-electric aircraft - A systems view and proposed NASA research Programs

NASA Technical Reports Server (NTRS)

Spitzer, C. R.

1984-01-01

It is expected that all-electric aircraft, whether military or commercial, will exhibit reduced weight, acquisition cost and fuel consumption, an expanded flight envelope and improved survivability and reliability, simpler maintenance, and reduced support equipment. Also noteworthy are dramatic improvements in mission adaptability, based on the degree to which control system performance relies on easily exchanged software. Flight-critical secondary power and control systems whose malfunction would mean loss of an aircraft pose failure detection and design methodology problems, however, that have only begun to be addressed. NASA-sponsored research activities concerned with these problems and prospective benefits are presently discussed.

Nonlinear Control of Large Disturbances in Magnetic Bearing Systems

NASA Technical Reports Server (NTRS)

Jiang, Yuhong; Zmood, R. B.

1996-01-01

In this paper, the nonlinear operation of magnetic bearing control methods is reviewed. For large disturbances, the effects of displacement constraints and power amplifier current and di/dt limits on bearing control system performance are analyzed. The operation of magnetic bearings exhibiting self-excited large scale oscillations have been studied both experimentally and by simulation. The simulation of the bearing system has been extended to include the effects of eddy currents in the actuators, so as to improve the accuracy of the simulation results. The results of these experiments and simulations are compared, and some useful conclusions are drawn for improving bearing system robustness.

Reliability improvements in tunable Pb1-xSnxSe diode lasers

NASA Technical Reports Server (NTRS)

Linden, K. J.; Butler, J. F.; Nill, K. W.; Reeder, R. E.

1980-01-01

Recent developments in the technology of Pb-salt diode lasers which have led to significant improvements in reliability and lifetime, and to improved operation at very long wavelengths are described. A combination of packaging and contacting-metallurgy improvements has led to diode lasers that are stable both in terms of temperature cycling and shelf-storage time. Lasers cycled over 500 times between 77 K and 300 K have exhibited no measurable changes in either electrical contact resistance or threshold current. Utilizing metallurgical contacting process, both lasers and experimental n-type and p-type bulk materials are shown to have electrical contact resistance values that are stable for shelf storage periods well in excess of one year. Problems and experiments which have led to devices with improved performance stability are discussed. Stable device configurations achieved for material compositions yielding lasers which operate continuously at wavelengths as long as 30.3 micrometers are described.

Evaluating the accuracy of SHAPE-directed RNA secondary structure predictions

PubMed Central

Sükösd, Zsuzsanna; Swenson, M. Shel; Kjems, Jørgen; Heitsch, Christine E.

2013-01-01

Recent advances in RNA structure determination include using data from high-throughput probing experiments to improve thermodynamic prediction accuracy. We evaluate the extent and nature of improvements in data-directed predictions for a diverse set of 16S/18S ribosomal sequences using a stochastic model of experimental SHAPE data. The average accuracy for 1000 data-directed predictions always improves over the original minimum free energy (MFE) structure. However, the amount of improvement varies with the sequence, exhibiting a correlation with MFE accuracy. Further analysis of this correlation shows that accurate MFE base pairs are typically preserved in a data-directed prediction, whereas inaccurate ones are not. Thus, the positive predictive value of common base pairs is consistently higher than the directed prediction accuracy. Finally, we confirm sequence dependencies in the directability of thermodynamic predictions and investigate the potential for greater accuracy improvements in the worst performing test sequence. PMID:23325843

Rational Design of Molecular Hole-Transporting Materials for Perovskite Solar Cells: Direct versus Inverted Device Configurations.

PubMed

Grisorio, Roberto; Iacobellis, Rosabianca; Listorti, Andrea; De Marco, Luisa; Cipolla, Maria Pia; Manca, Michele; Rizzo, Aurora; Abate, Antonio; Gigli, Giuseppe; Suranna, Gian Paolo

2017-07-26

Due to a still limited understanding of the reasons making 2,2',7,7'-tetrakis(N,N-di-p-methoxyphenylamine)-9,9'-spirobifluorene (Spiro-OMeTAD) the state-of-the-art hole-transporting material (HTM) for emerging photovoltaic applications, the molecular tailoring of organic components for perovskite solar cells (PSCs) lacks in solid design criteria. Charge delocalization in radical cationic states can undoubtedly be considered as one of the essential prerequisites for an HTM, but this aspect has been investigated to a relatively minor extent. In marked contrast with the 3-D structure of Spiro-OMeTAD, truxene-based HTMs Trux1 and Trux2 have been employed for the first time in PSCs fabricated with a direct (n-i-p) or inverted (p-i-n) architecture, exhibiting a peculiar behavior with respect to the referential HTM. Notwithstanding the efficient hole extraction from the perovskite layer exhibited by Trux1 and Trux2 in direct configuration devices, their photovoltaic performances were detrimentally affected by their poor hole transport. Conversely, an outstanding improvement of the photovoltaic performances in dopant-free inverted configuration devices compared to Spiro-OMeTAD was recorded, ascribable to the use of thinner HTM layers. The rationalization of the photovoltaic performances exhibited by different configuration devices discussed in this paper can provide new and unexpected prospects for engineering the interface between the active layer of perovskite-based solar cells and the hole transporters.

Performance Evaluation of the NEXT Ion Engine

NASA Technical Reports Server (NTRS)

Soulas, George C.; Domonkos, Matthew T.; Patterson, Michael J.

2003-01-01

The performance test results of three NEXT ion engines are presented. These ion engines exhibited peak specific impulse and thrust efficiency ranges of 4060 4090 s and 0.68 0.69, respectively, at the full power point of the NEXT throttle table. The performance of the ion engines satisfied all project requirements. Beam flatness parameters were significantly improved over the NSTAR ion engine, which is expected to improve accelerator grid service life. The results of engine inlet pressure and temperature measurements are also presented. Maximum main plenum, cathode, and neutralizer pressures were 12,000 Pa, 3110 Pa, and 8540 Pa, respectively, at the full power point of the NEXT throttle table. Main plenum and cathode inlet pressures required about 6 hours to increase to steady-state, while the neutralizer required only about 0.5 hour. Steady-state engine operating temperature ranges throughout the power throttling range examined were 179 303 C for the discharge chamber magnet rings and 132 213 C for the ion optics mounting ring.

High-Performance and Traditional Multicrystalline Silicon: Comparing Gettering Responses and Lifetime-Limiting Defects

DOE Office of Scientific and Technical Information (OSTI.GOV)

Castellanos, Sergio; Ekstrom, Kai E.; Autruffe, Antoine

2016-05-01

In recent years, high-performance multicrystalline silicon (HPMC-Si) has emerged as an attractive alternative to traditional ingot-based multicrystalline silicon (mc-Si), with a similar cost structure but improved cell performance. Herein, we evaluate the gettering response of traditional mc-Si and HPMC-Si. Microanalytical techniques demonstrate that HPMC-Si and mc-Si share similar lifetime-limiting defect types but have different relative concentrations and distributions. HPMC-Si shows a substantial lifetime improvement after P-gettering compared with mc-Si, chiefly because of lower area fraction of dislocation-rich clusters. In both materials, the dislocation clusters and grain boundaries were associated with relatively higher interstitial iron point-defect concentrations after diffusion, which ismore » suggestive of dissolving metal-impurity precipitates. The relatively fewer dislocation clusters in HPMC-Si are shown to exhibit similar characteristics to those found in mc-Si. Given similar governing principles, a proxy to determine relative recombination activity of dislocation clusters developed for mc-Si is successfully transferred to HPMC-Si.« less

Solution-processable alumina: PVP nanocomposite dielectric layer for high-performance organic thin-film transistors

NASA Astrophysics Data System (ADS)

Lin, Hui; Kong, Xiao; Li, Yiran; Kuang, Peng; Tao, Silu

2018-03-01

In this article, we have investigated the effect of nanocomposite gate dielectric layer built by alumina (Al2O3) and poly(4-vinyphenol) (PVP) with solution method which could enhance the dielectric capability and decrease the surface polarity. Then, we used modify layer to optimize the surface morphology of dielectric layer to further improve the insulation capability, and finally we fabricated the high-performance and low-voltage organic thin-film transistors by using this nanocomposite dielectric layer. The result shows that the devices with Al2O3:10%PVP dielectric layer with a modified layer exhibited a mobility of 0.49 cm2/Vs, I on/Ioff ratio of 7.8 × 104, threshold voltage of - 1.2 V, sub-threshold swing of 0.3 V/dec, and operating voltage as low as - 4 V. The improvement of devices performance was owing to the good insulation capability, appropriate capacitance of dielectric layer, and preferable interface contact, smaller crystalline size of active layer.

Adaptive learning and control for MIMO system based on adaptive dynamic programming.

PubMed

Fu, Jian; He, Haibo; Zhou, Xinmin

2011-07-01

Adaptive dynamic programming (ADP) is a promising research field for design of intelligent controllers, which can both learn on-the-fly and exhibit optimal behavior. Over the past decades, several generations of ADP design have been proposed in the literature, which have demonstrated many successful applications in various benchmarks and industrial applications. While many of the existing researches focus on multiple-inputs-single-output system with steepest descent search, in this paper we investigate a generalized multiple-input-multiple-output (GMIMO) ADP design for online learning and control, which is more applicable to a wide range of practical real-world applications. Furthermore, an improved weight-updating algorithm based on recursive Levenberg-Marquardt methods is presented and embodied in the GMIMO approach to improve its performance. Finally, we test the performance of this approach based on a practical complex system, namely, the learning and control of the tension and height of the looper system in a hot strip mill. Experimental results demonstrate that the proposed approach can achieve effective and robust performance.

Practice makes it better: A psychophysical study of visual perceptual learning and its transfer effects on aging.

PubMed

Li, Xuan; Allen, Philip A; Lien, Mei-Ching; Yamamoto, Naohide

2017-02-01

Previous studies on perceptual learning, acquiring a new skill through practice, appear to stimulate brain plasticity and enhance performance (Fiorentini & Berardi, 1981). The present study aimed to determine (a) whether perceptual learning can be used to compensate for age-related declines in perceptual abilities, and (b) whether the effect of perceptual learning can be transferred to untrained stimuli and subsequently improve capacity of visual working memory (VWM). We tested both healthy younger and older adults in a 3-day training session using an orientation discrimination task. A matching-to-sample psychophysical method was used to measure improvements in orientation discrimination thresholds and reaction times (RTs). Results showed that both younger and older adults improved discrimination thresholds and RTs with similar learning rates and magnitudes. Furthermore, older adults exhibited a generalization of improvements to 3 untrained orientations that were close to the training orientation and benefited more compared with younger adults from the perceptual learning as they transferred learning effects to the VWM performance. We conclude that through perceptual learning, older adults can partially counteract age-related perceptual declines, generalize the learning effect to other stimulus conditions, and further overcome the limitation of using VWM capacity to perform a perceptual task. (PsycINFO Database Record (c) 2017 APA, all rights reserved).

Theoretical study of surface plasmon resonance sensors based on 2D bimetallic alloy grating

NASA Astrophysics Data System (ADS)

Dhibi, Abdelhak; Khemiri, Mehdi; Oumezzine, Mohamed

2016-11-01

A surface plasmon resonance (SPR) sensor based on 2D alloy grating with a high performance is proposed. The grating consists of homogeneous alloys of formula MxAg1-x, where M is gold, copper, platinum and palladium. Compared to the SPR sensors based a pure metal, the sensor based on angular interrogation with silver exhibits a sharper (i.e. larger depth-to-width ratio) reflectivity dip, which provides a big detection accuracy, whereas the sensor based on gold exhibits the broadest dips and the highest sensitivity. The detection accuracy of SPR sensor based a metal alloy is enhanced by the increase of silver composition. In addition, the composition of silver which is around 0.8 improves the sensitivity and the quality of SPR sensor of pure metal. Numerical simulations based on rigorous coupled wave analysis (RCWA) show that the sensor based on a metal alloy not only has a high sensitivity and a high detection accuracy, but also exhibits a good linearity and a good quality.

Thrust chamber material technology program

NASA Technical Reports Server (NTRS)

Andrus, J. S.; Bordeau, R. G.

1989-01-01

This report covers work performed at Pratt & Whitney on development of copper-based materials for long-life, reusable, regeneratively cooled rocket engine thrust chambers. The program approached the goal of enhanced cyclic life through the application of rapid solidification to alloy development, to introduce fine dispersions to strengthen and stabilize the alloys at elevated temperatures. After screening of alloy systems, copper-based alloys containing Cr, Co, Hf, Ag, Ti, and Zr were processed by rapid-solidification atomization in bulk quantities. Those bulk alloys showing the most promise were characterized by tensile testing, thermal conductivity testing, and elevated-temperature, low-cycle fatigue (LFC) testing. Characterization indicated that Cu- 1.1 percent Hf exhibited the greatest potential as an improved-life thrust chamber material, exhibiting LCF life about four times that of NASA-Z. Other alloys (Cu- 0.6 percent Zr, and Cu- 0.6 percent Zr- 1.0 percent Cr) exhibited promise for use in this application, but needed more development work to balance properties.

Self-compassion increases self-improvement motivation.

PubMed

Breines, Juliana G; Chen, Serena

2012-09-01

Can treating oneself with compassion after making a mistake increase self-improvement motivation? In four experiments, the authors examined the hypothesis that self-compassion motivates people to improve personal weaknesses, moral transgressions, and test performance. Participants in a self-compassion condition, compared to a self-esteem control condition and either no intervention or a positive distraction control condition, expressed greater incremental beliefs about a personal weakness (Experiment 1); reported greater motivation to make amends and avoid repeating a recent moral transgression (Experiment 2); spent more time studying for a difficult test following an initial failure (Experiment 3); exhibited a preference for upward social comparison after reflecting on a personal weakness (Experiment 4); and reported greater motivation to change the weakness (Experiment 4). These findings suggest that, somewhat paradoxically, taking an accepting approach to personal failure may make people more motivated to improve themselves.

The effect of aerobic exercise and starvation on growth performance and postprandial metabolic response in juvenile southern catfish (Silurus meridionalis).

PubMed

Li, Xiu-Ming; Liu, Li; Yuan, Jian-Ming; Xiao, Yuan-Yuan; Fu, Shi-Jian; Zhang, Yao-Guang

2016-03-01

To investigate the effects of aerobic exercise and starvation on growth performance, postprandial metabolic response and their interaction in a sedentary fish species, either satiation-fed or starved juvenile southern catfish (Silurus meridionalis) were exercised at 25 °C under three water velocities, i.e., nearly still water (control), 1 body length (bl) s(-1) and 2 bl s(-1), for eight weeks. Then, the feed intake (FI), food conversion efficiency (FCE), specific growth rate (SGR), morphological parameters, resting ṀO2 (ṀO2rest) and postprandial ṀO2 responses of the experimental fish were measured. Exercise at a low velocity (1 bl s(-1)) showed no effect on any growth performance parameter, whereas exercise at a high velocity (2 bl s(-1)) exhibited higher FI but similar SGR due to the extra energy expenditure from swimming and consequent decreased FCE. Starvation led to a significant body mass loss, whereas the effect intensified in both exercise groups. Exercise resulted in improved cardio-respiratory capacity, as indicated by increased gill and heart indexes, whereas it exhibited no effect on resting and postprandial metabolism in S. meridionalis. The starved fish displayed significantly larger heart, gill and digestive tract indexes compared with the feeding fish, suggesting selective maintenance of cardio-respiratory and digestive function in this fish species during starvation. However, starved fish still exhibited impaired digestive performance, as evidenced by the prolonged duration and low postprandial metabolic increase, and this effect was further exacerbated in both the 1 and 2 bl s(-1) exercise groups. These data suggest the following: (1) aerobic exercise produced no improvement in growth performance but may have led to the impairment of growth under insufficient food conditions; (2) the mass of different organs and tissues responded differently to aerobic exercise and starvation due to the different physiological roles they play; and (3) aerobic exercise had no effect on the postprandial metabolic response under a "normal feeding" situation, whereas it may have resulted in the impairment of the digestive capacity when food availability was low due to the competition of energy and oxygen under unfavorable conditions in juvenile S. meridionalis. Copyright © 2016 Elsevier Inc. All rights reserved.

Effect of temperature on the performances and in situ polarization analysis of zinc-nickel single flow batteries

NASA Astrophysics Data System (ADS)

Cheng, Yuanhui; Zhang, Huamin; Lai, Qinzhi; Li, Xianfeng; Zheng, Qiong; Xi, Xiaoli; Ding, Cong

2014-03-01

The recently proposed high power density zinc-nickel single flow batteries (ZNBs) exhibit great potential for larger scale energy storage. The urgent needs are in the research into temperature adaptability of ZNBs before practical utilization. Furthermore, making clear their polarization distribution is essential to direct the further improvement of battery performance. Here, we focus on the trends in the polarization distribution and effect of temperature on the performance of ZNBs. The result shows that ZNBs can operate in the temperature range from 0 °C to 40 °C with acceptable energy efficiency (53%-79.1%) at 80 mA cm-2. The temperature sensitivity of coulombic efficiency and energy efficiency are 0.65% °C-1 and 0.98% °C-1 at 0 °C-20 °C, respectively. The positive polarization is much larger than the negative polarization at all studied temperatures. The charge overpotential of the positive electrode is more sensitive to temperature. These results enable us to better evaluate the application prospect of ZNBs and point a clear struggling orientation to further improve the battery performance.

Contact engineering for efficient charge injection in organic transistors with low-cost metal electrodes

NASA Astrophysics Data System (ADS)

Panigrahi, D.; Kumar, S.; Dhar, A.

2017-10-01

Controlling charge injection at the metal-semiconductor interface is very crucial for organic electronic devices in general as it can significantly influence the overall device performance. Herein, we report a facile, yet efficient contact modification approach, to enhance the hole injection efficiency through the incorporation of a high vacuum deposited TPD [N,N'-Bis(3-methylphenyl)-N,N'-diphenylbenzidine] interlayer between the electrodes and the active semiconducting layer. The device performance parameters such as mobility and on/off ratio improved significantly after the inclusion of the TPD buffer layer, and more interestingly, the devices with cost effective Ag and Cu electrodes were able to exhibit a superior device performance than the typically used Au source-drain devices. We have also observed that this contact modification technique can be even more effective than commonly used metal oxide interface modifying layers. Our investigations demonstrate the efficacy of the TPD interlayer in effectively reducing the interfacial contact resistance through the modification of pentacene energy levels, which consequently results in the substantial improvement in the device performances.

Enhanced electrochemical performance of a ZnO-MnO composite as an anode material for lithium ion batteries.

PubMed

Song, Min Seob; Nahm, Sahn; Cho, Won Il; Lee, Chongmok

2015-09-28

A ZnO-MnO composite was synthesized using a simple solvothermal method combined with a high-temperature treatment. To observe the phase change during the heating process, in situ high-temperature XRD analysis was performed under vacuum conditions. The results indicated that ZnMn2O4 transformed into the ZnO-MnO composite phase starting from 500 °C and that this composite structure was retained until 700 °C. The electrochemical performances of the ZnO-MnO composite electrode were evaluated through galvanostatic discharge-charge tests and cyclic voltammetry analysis. Its initial coulombic efficiency was significantly improved to 68.3% compared to that of ZnMn2O4 at 54.7%. Furthermore, the ZnO-MnO composite exhibited improved cycling performance and enhanced rate capability compared with untreated ZnMn2O4. To clarify the discharge-charge mechanism of the ZnO-MnO composite electrode, the structural changes during the charge and discharge processes were also investigated using ex situ XRD and TEM.

Mental models of audit and feedback in primary care settings.

PubMed

Hysong, Sylvia J; Smitham, Kristen; SoRelle, Richard; Amspoker, Amber; Hughes, Ashley M; Haidet, Paul

2018-05-30

Audit and feedback has been shown to be instrumental in improving quality of care, particularly in outpatient settings. The mental model individuals and organizations hold regarding audit and feedback can moderate its effectiveness, yet this has received limited study in the quality improvement literature. In this study we sought to uncover patterns in mental models of current feedback practices within high- and low-performing healthcare facilities. We purposively sampled 16 geographically dispersed VA hospitals based on high and low performance on a set of chronic and preventive care measures. We interviewed up to 4 personnel from each location (n = 48) to determine the facility's receptivity to audit and feedback practices. Interview transcripts were analyzed via content and framework analysis to identify emergent themes. We found high variability in the mental models of audit and feedback, which we organized into positive and negative themes. We were unable to associate mental models of audit and feedback with clinical performance due to high variance in facility performance over time. Positive mental models exhibit perceived utility of audit and feedback practices in improving performance; whereas, negative mental models did not. Results speak to the variability of mental models of feedback, highlighting how facilities perceive current audit and feedback practices. Findings are consistent with prior research  in that variability in feedback mental models is associated with lower performance.; Future research should seek to empirically link mental models revealed in this paper to high and low levels of clinical performance.

Electrochemically conductive treatment of TiO2 nanotube arrays in AlCl3 aqueous solution for supercapacitors

NASA Astrophysics Data System (ADS)

Zhong, Wenjie; Sang, Shangbin; Liu, Yingying; Wu, Qiumei; Liu, Kaiyu; Liu, Hongtao

2015-10-01

Highly ordered TiO2 nanotube arrays (NTAs) with excellent stability and large specific surface area make them competitive using as supercapacitor materials. Improving the conductivity of TiO2 is of great concern for the construction of high-performance supercapacitors. In this work, we developed a novel approach to improve the performance of TiO2 materials, involving the fabrication of Al-doped TiO2 NTAs by a simple electrochemical cathodic polarization treatment in AlCl3 aqueous solution. The prepared Al-doped TiO2 NTAs exhibited excellent electrochemical performances, attributing to the remarkably improved electrical conductivity (i.e., from approx. 10 kΩ to 20 Ω). Further analysis showed that Al3+ ions rather than H+ protons doped into TiO2 lattice cause this high conductivity. A MnO2/Al-TiO2 composite was evaluated by cyclic voltammetry, and achieved the specific capacitance of 544 F g-1, and the Ragone plot of the sample showed a high power density but less reduction of energy density. These results indicate that the MnO2/Al-TiO2 NTAs sample could be served as a promising electrode material for high -performance supercapacitors.

Performance-Enhanced Activated Carbon Electrodes for Supercapacitors Combining Both Graphene-Modified Current Collectors and Graphene Conductive Additive.

PubMed

Wang, Rubing; Qian, Yuting; Li, Weiwei; Zhu, Shoupu; Liu, Fengkui; Guo, Yufen; Chen, Mingliang; Li, Qi; Liu, Liwei

2018-05-15

Graphene has been widely used in the active material, conductive agent, binder or current collector for supercapacitors, due to its large specific surface area, high conductivity, and electron mobility. However, works simultaneously employing graphene as conductive agent and current collector were rarely reported. Here, we report improved activated carbon (AC) electrodes (AC@G@NiF/G) simultaneously combining chemical vapor deposition (CVD) graphene-modified nickel foams (NiF/Gs) current collectors and high quality few-layer graphene conductive additive instead of carbon black (CB). The synergistic effect of NiF/Gs and graphene additive makes the performances of AC@G@NiF/G electrodes superior to those of electrodes with CB or with nickel foam current collectors. The performances of AC@G@NiF/G electrodes show that for the few-layer graphene addition exists an optimum value around 5 wt %, rather than a larger addition of graphene, works out better. A symmetric supercapacitor assembled by AC@G@NiF/G electrodes exhibits excellent cycling stability. We attribute improved performances to graphene-enhanced conductivity of electrode materials and NiF/Gs with 3D graphene conductive network and lower oxidation, largely improving the electrical contact between active materials and current collectors.

Heat transfer enhancement in a lithium-ion cell through improved material-level thermal transport

NASA Astrophysics Data System (ADS)

Vishwakarma, Vivek; Waghela, Chirag; Wei, Zi; Prasher, Ravi; Nagpure, Shrikant C.; Li, Jianlin; Liu, Fuqiang; Daniel, Claus; Jain, Ankur

2015-12-01

While Li-ion cells offer excellent electrochemical performance for several applications including electric vehicles, they also exhibit poor thermal transport characteristics, resulting in reduced performance, overheating and thermal runaway. Inadequate heat removal from Li-ion cells originates from poor thermal conductivity within the cell. This paper identifies the rate-limiting material-level process that dominates overall thermal conduction in a Li-ion cell. Results indicate that thermal characteristics of a Li-ion cell are largely dominated by heat transfer across the cathode-separator interface rather than heat transfer through the materials themselves. This interfacial thermal resistance contributes around 88% of total thermal resistance in the cell. Measured value of interfacial resistance is close to that obtained from theoretical models that account for weak adhesion and large acoustic mismatch between cathode and separator. Further, to address this problem, an amine-based chemical bridging of the interface is carried out. This is shown to result in in four-times lower interfacial thermal resistance without deterioration in electrochemical performance, thereby increasing effective thermal conductivity by three-fold. This improvement is expected to reduce peak temperature rise during operation by 60%. By identifying and addressing the material-level root cause of poor thermal transport in Li-ion cells, this work may contributes towards improved thermal performance of Li-ion cells.

Performance-Enhanced Activated Carbon Electrodes for Supercapacitors Combining Both Graphene-Modified Current Collectors and Graphene Conductive Additive

PubMed Central

Wang, Rubing; Qian, Yuting; Li, Weiwei; Zhu, Shoupu; Liu, Fengkui; Guo, Yufen; Chen, Mingliang; Li, Qi; Liu, Liwei

2018-01-01

Graphene has been widely used in the active material, conductive agent, binder or current collector for supercapacitors, due to its large specific surface area, high conductivity, and electron mobility. However, works simultaneously employing graphene as conductive agent and current collector were rarely reported. Here, we report improved activated carbon (AC) electrodes (AC@G@NiF/G) simultaneously combining chemical vapor deposition (CVD) graphene-modified nickel foams (NiF/Gs) current collectors and high quality few-layer graphene conductive additive instead of carbon black (CB). The synergistic effect of NiF/Gs and graphene additive makes the performances of AC@G@NiF/G electrodes superior to those of electrodes with CB or with nickel foam current collectors. The performances of AC@G@NiF/G electrodes show that for the few-layer graphene addition exists an optimum value around 5 wt %, rather than a larger addition of graphene, works out better. A symmetric supercapacitor assembled by AC@G@NiF/G electrodes exhibits excellent cycling stability. We attribute improved performances to graphene-enhanced conductivity of electrode materials and NiF/Gs with 3D graphene conductive network and lower oxidation, largely improving the electrical contact between active materials and current collectors. PMID:29762528

Assessment of simulated water balance from Noah, Noah-MP, CLM, and VIC over CONUS using the NLDAS test bed

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cai, Xitian; Yang, Zong-Liang; Xia, Youlong

2014-12-27

This study assesses the hydrologic performance of four land surface models (LSMs) for the conterminous United States using the North American Land Data Assimilation System (NLDAS) test bed. The four LSMs are the baseline community Noah LSM (Noah, version 2.8), the Variable Infiltration Capacity (VIC, version 4.0.5) model, the substantially augmented Noah LSM with multiparameterization options (hence Noah-MP), and the Community Land Model version 4 (CLM4). All four models are driven by the same NLDAS-2 atmospheric forcing. Modeled terrestrial water storage (TWS), streamflow, evapotranspiration (ET), and soil moisture are compared with each other and evaluated against the identical observations. Relativemore » to Noah, the other three models offer significant improvements in simulating TWS and streamflow and moderate improvements in simulating ET and soil moisture. Noah-MP provides the best performance in simulating soil moisture and is among the best in simulating TWS, CLM4 shows the best performance in simulating ET, and VIC ranks the highest in performing the streamflow simulations. Despite these improvements, CLM4, Noah-MP, and VIC exhibit deficiencies, such as the low variability of soil moisture in CLM4, the fast growth of spring ET in Noah-MP, and the constant overestimation of ET in VIC.« less

The sol-gel template synthesis of porous TiO2 for a high performance humidity sensor

NASA Astrophysics Data System (ADS)

Wang, Zhuyi; Shi, Liyi; Wu, Fengqing; Yuan, Shuai; Zhao, Yin; Zhang, Meihong

2011-07-01

This research develops a simple template assisted sol-gel process for preparing porous TiO2 for a high performance humidity sensor. Tetraethyl orthosilicate (TEOS) as a template was directly introduced into TiO2 sol formed by the hydrolysis and condensation of titanium alkoxide; the following calcination led to the formation of TiO2-SiO2 composite, and the selective removal of SiO2 by dilute HF solution led to the formation of porous structure in TiO2. The resulting porous TiO2-based sensor exhibits high sensitivity and linear response in the wide relative humidity (RH) range of 11%-95%, with an impedance variation of four orders of magnitude to humidity change. Moreover, it exhibits a rapid and highly reversible response characterized by a very small hysteresis of < 1% RH and a short response-recovery time (5 s for adsorption and 8 s for desorption), and a 30-day stability test also confirms its long-term stability. Compared with pure TiO2 prepared by the conventional sol-gel method, our product shows remarkably improved performance and good prospect for a high performance humidity sensor. The complex impedance spectra were used to elucidate its humidity sensing mechanism in detail.

Hierarchical structured Sm2O3 modified CuO nanoflowers as electrode materials for high performance supercapacitors

NASA Astrophysics Data System (ADS)

Zhang, Xiaojuan; He, Mingqian; He, Ping; Liu, Hongtao; Bai, Hongmei; Chen, Jingchao; He, Shaoying; Zhang, Xingquan; Dong, Faqing; Chen, Yang

2017-12-01

By a simple and cost effective chemical precipitation-hydrothermal method, novel hierarchical structured Sm2O3 modified CuO nanoflowers are prepared and investigated as electrode materials for supercapacitors. The physical properties of prepared materials are characterized by XRD, FE-SEM, EDX and FTIR techniques. Furthermore, electrochemical performances of prepared materials are investigated by cyclic voltammetry, galvanostatic charge/discharge and electrochemical impedance spectrum in 1.0 M KOH electrolyte. The resulting Sm2O3 modified CuO based electrodes exhibit obviously enhanced capacitive properties owing to the unique nanostructures and strong synergistic effects. It is worth noting that the optimized SC-3 based electrode exhibits the best electrochemical performances in all prepared electrodes, including higher specific capacitance (383.4 F g-1 at 0.5 A g-1) and good rate capability (393.2 F g-1 and 246.3 F g-1 at 0.3 A g-1 and 3.0 A g-1, respectively), as well as excellent cycling stability (84.6% capacitance retention after 2000 cycles at 1.0 A g-1). The present results show that Sm2O3 is used as a promising modifier to change the morphology and improve electrochemical performances of CuO materials.

Longitudinal changes in quantitative and qualitative indicators of word and story recall in young-old and old-old adults.

PubMed

Small, B J; Dixon, R A; Hultsch, D F; Hertzog, C

1999-03-01

The present study examined longitudinal changes in quantitative and qualitative measures of episodic memory. The sample, taken from the Victoria Longitudinal Study, consisted of 158 young-old adults (initially 55 to 70 years old) and 84 old-old adults (initially 71 to 86 years old) who were tested three times over six years. Average word and text recall, as well as five indicators of qualitative aspects of word recall (e.g., number of categories recalled) and one indicator of structure of text recall (i.e., levels of information) were used. For word recall, although both age groups exhibited negative longitudinal changes in quantitative performance, overall qualitative performance was generally stable. Two qualitative indicators (number of categories and intrusions) showed modest decline and one (organization at recall) showed improvement. Results for overall text recall showed significant performance increments for the young-old group, whereas the old-old group exhibited slight declines in overall performance. Analyses of qualitative measures showed stable structure of hierarchical recall, with the old-old being impaired at all levels of detail in the stories. Overall results suggest that some underlying structural characteristics of word and text recall may be maintained into late life even when significant overall decline is observed.

Nanostructure selenium compounds as pseudocapacitive electrodes for high-performance asymmetric supercapacitor

PubMed Central

Hua, Fengting; Sun, Kanjun; Fenga, Enke; Peng, Hui; Zhang, Zhiguo; Lei, Ziqiang

2018-01-01

The electrochemical performance of an energy conversion and storage device like the supercapacitor mainly depends on the microstructure and morphology of the electrodes. In this paper, to improve the capacitance performance of the supercapacitor, the all-pseudocapacitive electrodes of lamella-like Bi18SeO29/BiSe as the negative electrode and flower-like Co0.85Se nanosheets as the positive electrode are synthesized by using a facile low-temperature one-step hydrothermal method. The microstructures and morphology of the electrode materials are carefully characterized, and the capacitance performances are also tested. The Bi18SeO29/BiSe and Co0.85Se have high specific capacitance (471.3 F g–1 and 255 F g–1 at 0.5 A g–1), high conductivity, outstanding cycling stability, as well as good rate capability. The assembled asymmetric supercapacitor completely based on the pseudocapacitive electrodes exhibits outstanding cycling stability (about 93% capacitance retention after 5000 cycles). Moreover, the devices exhibit high energy density of 24.2 Wh kg–1 at a power density of 871.2 W kg–1 in the voltage window of 0–1.6 V with 2 M KOH solution. PMID:29410830

The Effect of the Duration of Basic Life Support Training on the Learners' Cardiopulmonary and Automated External Defibrillator Skills

PubMed Central

Kang, Ku Hyun; Song, Keun Jeong; Lee, Chang Hee

2016-01-01

Background. Basic life support (BLS) training with hands-on practice can improve performance during simulated cardiac arrest, although the optimal duration for BLS training is unknown. This study aimed to assess the effectiveness of various BLS training durations for acquiring cardiopulmonary resuscitation (CPR) and automated external defibrillator (AED) skills. Methods. We randomised 485 South Korean nonmedical college students into four levels of BLS training: level 1 (40 min), level 2 (80 min), level 3 (120 min), and level 4 (180 min). Before and after each level, the participants completed questionnaires regarding their willingness to perform CPR and use AEDs, and their psychomotor skills for CPR and AED use were assessed using a manikin with Skill-Reporter™ software. Results. There were no significant differences between levels 1 and 2, although levels 3 and 4 exhibited significant differences in the proportion of overall adequate chest compressions (p < 0.001) and average chest compression depth (p = 0.003). All levels exhibited a greater posttest willingness to perform CPR and use AEDs (all, p < 0.001). Conclusions. Brief BLS training provided a moderate level of skill for performing CPR and using AEDs. However, high-quality skills for CPR required longer and hands-on training, particularly hands-on training with AEDs. PMID:27529066

A review of human factors challenges of complex adaptive systems: discovering and understanding chaos in human performance.

PubMed

Karwowski, Waldemar

2012-12-01

In this paper, the author explores a need for a greater understanding of the true nature of human-system interactions from the perspective of the theory of complex adaptive systems, including the essence of complexity, emergent properties of system behavior, nonlinear systems dynamics, and deterministic chaos. Human performance, more often than not, constitutes complex adaptive phenomena with emergent properties that exhibit nonlinear dynamical (chaotic) behaviors. The complexity challenges in the design and management of contemporary work systems, including service systems, are explored. Examples of selected applications of the concepts of nonlinear dynamics to the study of human physical performance are provided. Understanding and applications of the concepts of theory of complex adaptive and dynamical systems should significantly improve the effectiveness of human-centered design efforts of a large system of systems. Performance of many contemporary work systems and environments may be sensitive to the initial conditions and may exhibit dynamic nonlinear properties and chaotic system behaviors. Human-centered design of emergent human-system interactions requires application of the theories of nonlinear dynamics and complex adaptive system. The success of future human-systems integration efforts requires the fusion of paradigms, knowledge, design principles, and methodologies of human factors and ergonomics with those of the science of complex adaptive systems as well as modern systems engineering.

Extrinsic pseudocapacitve Li-ion storage of SnS anode via lithiation-induced structural optimization on cycling

NASA Astrophysics Data System (ADS)

Lian, Qingwang; Zhou, Gang; Liu, Jiatu; Wu, Chen; Wei, Weifeng; Chen, Libao; Li, Chengchao

2017-10-01

Here, we report a new enhanced extrinsic pseudocapacitve Li-ion storage mechanism via lithiation-induced structural optimization strategy. The flower-like C@SnS and bulk SnS exhibit initial capacity decay and subsequent increase of capacity on cycling. After a long-term lithiation/delithiation process, flower-like C@SnS and bulk SnS exhibit improved rate performance and reversible capacity in comparison with those of initial state. Moreover, a high capacity of 530 mAh g-1 is still remained even after 1550 cycles at a high current density of 5.0 A g-1 for flower-like C@SnS after pre-lithiation of 350 cycles. According to the comprehensive analysis of structural evolution and electrochemical performance, it demonstrates that SnS electrodes experience crystal size reduction and further amorphization on cycling, which enhances the reversibility of conversion reaction for SnS, leading to increasing capacity. On the other hand, surface-dominated extrinsic pseudocapacitive contribution results in enhanced rate performance because electrodes expose a large fraction of Li+ sites on surface or near-surface region with structural optimization on cycling. This study reveals that extrinsic pseudocapacitance of SnS can be stimulated via lithiation-induced structural optimization, which gives rise to high-rate and long-lived performances.

Seismic Experimental Study on New-Type Composite Exterior Wallboard with Integrated Structural Function and Insulation

PubMed Central

Ma, Shaochun; Jiang, Nan

2015-01-01

In order to evaluate the seismic performance of new-type composite exterior wallboard, a total of six exterior and interior wallboards were incorporated in the experiment of seismic performance. Seismic performance such as the stress process, damage mode, hysteresis and skeleton curve, load-carrying and ductility coefficient, damping and energy dissipation, stiffness degradation as well as material strain of the exterior wallboards were analyzed with emphasis and compared with interior wallboards. Results of the experiment and analysis showed that both interior and exterior wallboards exhibited outstanding seismic performance. Due to the existence of insulation layer and externally bonded single gypsum board, the capacity of elastoplastic deformation and seismic energy dissipation of the exterior wallboards was improved and each seismic performance indicator of the exterior wallboards outperformed the interior wallboards.

Fitness change and subsequent academic performance in adolescents.

PubMed

Chen, Li-Jung; Fox, Kenneth R; Ku, Po-Wen; Taun, Chih-Yang

2013-09-01

This study examined the association between fitness change and subsequent academic performance in Taiwanese schoolchildren from 7th grade to 9th grade. The 7th graders from 1 junior high school district participated in this study (N = 669). Academic performance was extracted from school records at the end of each grade. Cardiovascular (CV) fitness, sit-and-reach flexibility, bent-leg curl-ups, and height and weight for calculating body mass index (BMI) were assessed at the start of each grade. The results showed that improvement in CV fitness, but not muscular endurance or flexibility, is significantly related to greater academic performance. A weak and nonsignificant academic-BMI relationship was seen. CV fitness exhibits stronger longitudinal associations with academic performance than other forms of fitness or BMI for adolescents. © 2013, American School Health Association.

Co(OH)2/RGO/NiO sandwich-structured nanotube arrays with special surface and synergistic effects as high-performance positive electrodes for asymmetric supercapacitors

NASA Astrophysics Data System (ADS)

Xu, Han; Zhang, Chi; Zhou, Wen; Li, Gao-Ren

2015-10-01

High power density, high energy density and excellent cycling stability are the main requirements for high-performance supercapacitors (SCs) that will be widely used for portable consumer electronics and hybrid electric vehicles. Here we investigate novel types of hybrid Co(OH)2/reduced graphene oxide (RGO)/NiO sandwich-structured nanotube arrays (SNTAs) as positive electrodes for asymmetric supercapacitors (ASCs). The synthesized Co(OH)2/RGO/NiO SNTAs exhibit a significantly improved specific capacity (~1470 F g-1 at 5 mV s-1) and excellent cycling stability with ~98% Csp retention after 10 000 cycles because of the fast transport and short diffusion paths for electroactive species, the high utilization rate of electrode materials, and special synergistic effects among Co(OH)2, RGO, and NiO. The high-performance ASCs are assembled using Co(OH)2/RGO/NiO SNTAs as positive electrodes and active carbon (AC) as negative electrodes, and they exhibit a high energy density (115 Wh kg-1), a high power density (27.5 kW kg-1) and an excellent cycling stability (less 5% Csp loss after 10 000 cycles). This study shows an important breakthrough in the design and fabrication of multi-walled hybrid nanotube arrays as positive electrodes for ASCs.High power density, high energy density and excellent cycling stability are the main requirements for high-performance supercapacitors (SCs) that will be widely used for portable consumer electronics and hybrid electric vehicles. Here we investigate novel types of hybrid Co(OH)2/reduced graphene oxide (RGO)/NiO sandwich-structured nanotube arrays (SNTAs) as positive electrodes for asymmetric supercapacitors (ASCs). The synthesized Co(OH)2/RGO/NiO SNTAs exhibit a significantly improved specific capacity (~1470 F g-1 at 5 mV s-1) and excellent cycling stability with ~98% Csp retention after 10 000 cycles because of the fast transport and short diffusion paths for electroactive species, the high utilization rate of electrode materials, and special synergistic effects among Co(OH)2, RGO, and NiO. The high-performance ASCs are assembled using Co(OH)2/RGO/NiO SNTAs as positive electrodes and active carbon (AC) as negative electrodes, and they exhibit a high energy density (115 Wh kg-1), a high power density (27.5 kW kg-1) and an excellent cycling stability (less 5% Csp loss after 10 000 cycles). This study shows an important breakthrough in the design and fabrication of multi-walled hybrid nanotube arrays as positive electrodes for ASCs. Electronic supplementary information (ESI) available: SEM images, XPS spectra, equivalent circuit, and CVs. See DOI: 10.1039/c5nr04449a

Evaluating Education and Science at the KSC Visitor Complex

NASA Technical Reports Server (NTRS)

Erickson, Lance K.

2002-01-01

As part of a two-year NASA-ASEE project, a preliminary evaluation and subsequent recommendations were developed to improve the education and science content of the Kennedy Space Center Visitor Complex exhibits. Recommendations for improvements in those exhibits were based on qualitative descriptions of the exhibits, on comparisons to similar exhibit collections, and on available evaluation processes. Because of the subjective nature of measuring content in a broad group of exhibits and displays, emphasis is placed on employing a survey format for a follow-on, more quantitative evaluation. The use of an external organization for this evaluation development is also recommended to reduce bias and increase validity.

Evaluating Education and Science at the KSC Visitor Complex

NASA Technical Reports Server (NTRS)

Erickson, Lance K.

2001-01-01

As part of a two-year NASA-ASEE project, a preliminary evaluation and subsequent recommendations were developed to improve the education and science content of the Kennedy Space Center Visitor Complex exhibits. Recommendations for improvements in those exhibits were based on qualitative descriptions of the exhibits, on comparisons to similar exhibit collections, and on available evaluation processes. Because of the subjective nature of measuring content in a broad group of exhibits and displays, emphasis is placed on employing a survey format for a follow-on, more quantitative evaluation. The use of an external organization for this evaluation development is also recommended to reduce bias and increase validity.

Effect of preparation methods on dispersion stability and electrochemical performance of graphene sheets

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chen, Li, E-mail: chenli1981@lut.cn; Li, Na; Zhang, Mingxia

Chemical exfoliation is one of the most important strategies for preparing graphene. The aggregation of graphene sheets severely prevents graphene from exhibiting excellent properties. However, there are no attempts to investigate the effect of preparation methods on the dispersity of graphene sheets. In this study, three chemical exfoliation methods, including Hummers method, modified Hummers method, and improved method, were used to prepare graphene sheets. The influence of preparation methods on the structure, dispersion stability in organic solvents, and electrochemical properties of graphene sheets were investigated. Fourier transform infrared microscopy, Raman spectra, transmission electron microscopy, and UV–vis spectrophotometry were employed tomore » analyze the structure of the as-prepared graphene sheets. The results showed that graphene prepared by improved method exhibits excellent dispersity and stability in organic solvents without any additional stabilizer or modifier, which is attributed to the completely exfoliation and regular structure. Moreover, cyclic voltammetric and electrochemical impedance spectroscopy measurements showed that graphene prepared by improved method exhibits superior electrochemical properties than that prepared by the other two methods. - Graphical abstract: Graphene oxides with different oxidation degree were obtained via three methods, and then graphene with different crystal structures were created by chemical reduction of exfoliated graphene oxides. - Highlights: • Graphene oxides with different oxidation degree were obtained via three oxidation methods. • The influence of oxidation methods on microstructure of graphene was investigated. • The effect of oxidation methods on dispersion stability of graphene was investigated. • The effect of oxidation methods on electrochemical properties of graphene was discussed.« less

Handwriting capacity in children newly diagnosed with Attention Deficit Hyperactivity Disorder.

PubMed

Brossard-Racine, Marie; Majnemer, Annette; Shevell, Michael; Snider, Laurie; Bélanger, Stacey Ageranioti

2011-01-01

Preliminary evidence suggests that children with Attention Deficit Hyperactivity Disorder (ADHD) may exhibit handwriting difficulties. However, the exact nature of these difficulties and the extent to which they may relate to motor or behavioural difficulties remains unclear. The aim of this study was to describe handwriting capacity in children newly diagnosed with ADHD and identify predictors of performance. Forty medication-naïve children with ADHD (mean age 8.1 years) were evaluated with the Evaluation Tool of Children's Handwriting-Manuscript, the Movement Assessment Battery for Children (M-ABC), the Developmental Test of Visual Motor Integration (VMI) and the Conner Global Index. An important subset (85.0%) exhibited manual dexterity difficulties. Handwriting performance was extremely variable in terms of speed and legibility. VMI was the most important predictor of legibility. Upper extremity coordination, as measured by the M-ABC ball skills subtest, was also a good predictor of word legibility. Poor handwriting legibility and slow writing speed were common in children newly diagnosed with ADHD and were associated with motor abilities. Future studies are needed to determine whether interventions, including stimulant medications, can improve handwriting performance and related motor functioning. Copyright © 2011 Elsevier Ltd. All rights reserved.

Highly efficient Zr doped-TiO2/glass fiber photocatalyst and its performance in formaldehyde removal under visible light.

PubMed

Huang, Chao; Ding, Yaping; Chen, Yingwen; Li, Peiwen; Zhu, Shemin; Shen, Shubao

2017-10-01

Zr-doped-TiO 2 loaded glass fiber (ZT/GF) composite photocatalysts with different Zr/Ti ratios were prepared with a sol-gel process. Zr 4+ can replace Ti 4+ in the TiO 2 lattice, which is conducive to forming the anatase phase and reducing the calcination temperature. The glass fiber carrier was responsible for better dispersion and loading of Zr-doped-TiO 2 particles, improving the applicability of the Zr-doped-TiO 2 . The ZT/GF photocatalysts were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), Fourier transform infrared spectroscopy (FT-IR), ultraviolet-visible spectroscopy (UV-vis) and Barrett-Joyner-Halenda (BJH). The performance of photocatalysts with different loading was evaluated in formaldehyde degradation under visible light at room temperature. ZT/GF0.2 exhibited the highest activity, with a formaldehyde removal rate as high as 95.14% being observed, which is better than that of the photocatalyst particles alone. The stability of the catalyst was also tested, and ZT/GF exhibited excellent catalytic performance with 94.38% removal efficiency, even after seven uses. Copyright © 2017. Published by Elsevier B.V.

Design of flexible polyphenylene proton-conducting membrane for next-generation fuel cells.

PubMed

Miyake, Junpei; Taki, Ryunosuke; Mochizuki, Takashi; Shimizu, Ryo; Akiyama, Ryo; Uchida, Makoto; Miyatake, Kenji

2017-10-01

Proton exchange membrane fuel cells (PEMFCs) are promising devices for clean power generation in automotive, stationary, and portable applications. Perfluorosulfonic acid (PFSA) ionomers (for example, Nafion) have been the benchmark PEMs; however, several problems, including high gas permeability, low thermal stability, high production cost, and environmental incompatibility, limit the widespread dissemination of PEMFCs. It is believed that fluorine-free PEMs can potentially address all of these issues; however, none of these membranes have simultaneously met the criteria for both high performance (for example, proton conductivity) and durability (for example, mechanical and chemical stability). We present a polyphenylene-based PEM (SPP-QP) that fulfills the required properties for fuel cell applications. The newly designed PEM exhibits very high proton conductivity, excellent membrane flexibility, low gas permeability, and extremely high stability, with negligible degradation even under accelerated degradation conditions, which has never been achieved with existing fluorine-free PEMs. The polyphenylene PEM also exhibits reasonably high fuel cell performance, with excellent durability under practical conditions. This new PEM extends the limits of existing fluorine-free proton-conductive materials and will help to realize the next generation of PEMFCs via cost reduction as well as the performance improvement compared to the present PFSA-based PEMFC systems.

Effects of speech in noise and dichotic listening intervention programs on central auditory processing disorders.

PubMed

Putter-Katz, Hanna; Adi-Bensaid, Limor; Feldman, Irit; Hildesheimer, Minka

2008-01-01

Twenty children with central auditory processing disorders [(C)APD] were subjected to a structured intervention program of listening skills in quiet and in noise. Their performance was compared to that of a control group of 10 children with (C)APD with no special treatment. Pretests were conducted in quiet and in degraded listening conditions (speech noise and competing speech). The (C)APD management approach was integrative and included top-down and bottom-up strategies. It focused on environmental modifications, remediation techniques, and compensatory strategies. Training was conducted with monosyllabic and polysyllabic words, sentences and phrases in quiet and in noise. Comparisons of pre- and post-management measures indicated increase in speech recognition performance in background noise and competing speech for the treatment group. This improvement was exhibited for both ears. A significant difference between ears was found with the left ear showing improvement in both the short and the long versions of competing sentence tests and the right ear performing better in the long competing sentences only following intervention. No changes were documented for the control group. These findings add to a growing body of literature suggesting that interactive auditory training can improve listening skills.

Understanding the Photovoltaic Performance of Perovskite-Spirobifluorene Solar Cells.

PubMed

Song, Zhen; Liu, Jiang; Wang, Gang; Zuo, Wentao; Liao, Cheng; Mei, Jun

2017-11-03

Lead halide perovskite solar cells with remarkable power conversion efficiency have attracted much attention in recent years. However, there still exist many problems with their use that are not completely understood, and further studies are needed. Herein, the hole-transport layer dependence of the photovoltaic performance of perovskite solar cells is investigated in detail. It is found that devices freshly prepared using pristine 2,2',7,7'-tetrakis-(N,N-di-p-methoxyphenylamine)-9,9'-spirobifluorene (spiro-OMeTAD) and Li-doped spiro-OMeTAD as hole-transport layers exhibit S-shaped current density-voltage curves with poor fill factors. The devices show progressively improved fill factors and efficiencies upon exposure to air, which is attributed to air-induced conductivity improvement in the spiro-OMeTAD layer. After introducing a cobalt salt dopant (FK209) into the spiro-OMeTAD layer, the corresponding devices show remarkable performance without the need of air exposure. These results confirm that the dopant not only increases the conductivity of spiro-OMeTAD layer, but also tunes the surface potential, which helps to improve charge transport and reduce the recombination loss. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Employing overlayers to improve the performance of Cu 2BaSnS 4 thin film based photoelectrochemical water reduction devices

DOE PAGES

Ge, Jie; Roland, Paul J.; Koirala, Prakash; ...

2017-01-19

Earth-abundant copper-barium-thiostannate Cu 2BaSnS 4 (CBTS)-based thin films have recently been reported to exhibit the optoelectronic and defect properties suitable as absorbers for photoelectrochemical (PEC) water splitting and the top cell of tandem photovoltaic solar cells. However, the photocurrents of CBTS-based PEC devices are still much lower than the theoretical value, partially due to ineffective charge collection at CBTS/water interface and instability of CBTS in electrolytes. Here, we report on overcoming these issues by employing overlayer engineering. We find that CdS/ZnO/TiO 2 overlayers can significant-ly improve the PEC performance, achieving saturated cathodic photocurrents up to 7.8 mA cm -2 atmore » the potential of -0.10 V versus reversible hydrogen electrode (RHE) in a neutral electrolyte solution, which is much higher than the best bare CBTS film attaining a photocurrent of 4.8 mA cm -2 at the potential of -0.2 V versus RHE. Finally, our results suggest a viable approach for improving the performance of CBTS-based PEC cells.« less

A Potential Spatial Working Memory Training Task to Improve Both Episodic Memory and Fluid Intelligence

PubMed Central

Rudebeck, Sarah R.; Bor, Daniel; Ormond, Angharad; O’Reilly, Jill X.; Lee, Andy C. H.

2012-01-01

One current challenge in cognitive training is to create a training regime that benefits multiple cognitive domains, including episodic memory, without relying on a large battery of tasks, which can be time-consuming and difficult to learn. By giving careful consideration to the neural correlates underlying episodic and working memory, we devised a computerized working memory training task in which neurologically healthy participants were required to monitor and detect repetitions in two streams of spatial information (spatial location and scene identity) presented simultaneously (i.e. a dual n-back paradigm). Participants’ episodic memory abilities were assessed before and after training using two object and scene recognition memory tasks incorporating memory confidence judgments. Furthermore, to determine the generalizability of the effects of training, we also assessed fluid intelligence using a matrix reasoning task. By examining the difference between pre- and post-training performance (i.e. gain scores), we found that the trainers, compared to non-trainers, exhibited a significant improvement in fluid intelligence after 20 days. Interestingly, pre-training fluid intelligence performance, but not training task improvement, was a significant predictor of post-training fluid intelligence improvement, with lower pre-training fluid intelligence associated with greater post-training gain. Crucially, trainers who improved the most on the training task also showed an improvement in recognition memory as captured by d-prime scores and estimates of recollection and familiarity memory. Training task improvement was a significant predictor of gains in recognition and familiarity memory performance, with greater training improvement leading to more marked gains. In contrast, lower pre-training recollection memory scores, and not training task improvement, led to greater recollection memory performance after training. Our findings demonstrate that practice on a single working memory task can potentially improve aspects of both episodic memory and fluid intelligence, and that an extensive training regime with multiple tasks may not be necessary. PMID:23209740

A potential spatial working memory training task to improve both episodic memory and fluid intelligence.

PubMed

Rudebeck, Sarah R; Bor, Daniel; Ormond, Angharad; O'Reilly, Jill X; Lee, Andy C H

2012-01-01

One current challenge in cognitive training is to create a training regime that benefits multiple cognitive domains, including episodic memory, without relying on a large battery of tasks, which can be time-consuming and difficult to learn. By giving careful consideration to the neural correlates underlying episodic and working memory, we devised a computerized working memory training task in which neurologically healthy participants were required to monitor and detect repetitions in two streams of spatial information (spatial location and scene identity) presented simultaneously (i.e. a dual n-back paradigm). Participants' episodic memory abilities were assessed before and after training using two object and scene recognition memory tasks incorporating memory confidence judgments. Furthermore, to determine the generalizability of the effects of training, we also assessed fluid intelligence using a matrix reasoning task. By examining the difference between pre- and post-training performance (i.e. gain scores), we found that the trainers, compared to non-trainers, exhibited a significant improvement in fluid intelligence after 20 days. Interestingly, pre-training fluid intelligence performance, but not training task improvement, was a significant predictor of post-training fluid intelligence improvement, with lower pre-training fluid intelligence associated with greater post-training gain. Crucially, trainers who improved the most on the training task also showed an improvement in recognition memory as captured by d-prime scores and estimates of recollection and familiarity memory. Training task improvement was a significant predictor of gains in recognition and familiarity memory performance, with greater training improvement leading to more marked gains. In contrast, lower pre-training recollection memory scores, and not training task improvement, led to greater recollection memory performance after training. Our findings demonstrate that practice on a single working memory task can potentially improve aspects of both episodic memory and fluid intelligence, and that an extensive training regime with multiple tasks may not be necessary.

Spatial Probability Dynamically Modulates Visual Target Detection in Chickens

PubMed Central

Sridharan, Devarajan; Ramamurthy, Deepa L.; Knudsen, Eric I.

2013-01-01

The natural world contains a rich and ever-changing landscape of sensory information. To survive, an organism must be able to flexibly and rapidly locate the most relevant sources of information at any time. Humans and non-human primates exploit regularities in the spatial distribution of relevant stimuli (targets) to improve detection at locations of high target probability. Is the ability to flexibly modify behavior based on visual experience unique to primates? Chickens (Gallus domesticus) were trained on a multiple alternative Go/NoGo task to detect a small, briefly-flashed dot (target) in each of the quadrants of the visual field. When targets were presented with equal probability (25%) in each quadrant, chickens exhibited a distinct advantage for detecting targets at lower, relative to upper, hemifield locations. Increasing the probability of presentation in the upper hemifield locations (to 80%) dramatically improved detection performance at these locations to be on par with lower hemifield performance. Finally, detection performance in the upper hemifield changed on a rapid timescale, improving with successive target detections, and declining with successive detections at the diagonally opposite location in the lower hemifield. These data indicate the action of a process that in chickens, as in primates, flexibly and dynamically modulates detection performance based on the spatial probabilities of sensory stimuli as well as on recent performance history. PMID:23734188

Ultrahigh PEMFC performance of a thin-film, dual-electrode assembly with tailored electrode morphology.

PubMed

Jung, Chi-Young; Kim, Tae-Hyun; Yi, Sung-Chul

2014-02-01

A dual-electrode membrane electrode assembly (MEA) for proton exchange membrane fuel cells with enhanced polarization under zero relative humidity (RH) is fabricated by introducing a phase-separated morphology in an agglomerated catalyst layer of Pt/C (platinum on carbon black) and Nafion. In the catalyst layer, a sufficient level of phase separation is achieved by dispersing the Pt catalyst and the Nafion dispersion in a mixed-solvent system (propane-1,2,3-triol/1-methyl-2-pyrrolidinone).The high polymer chain mobility results in improved water uptake and regular pore-size distribution with small pore diameters. The electrochemical performance of the dual-film electrode assembly with different levels of phase separation is compared to conventional electrode assemblies. As a result, good performance at 0 % RH is obtained because self-humidification is dramatically improved by attaching this dense and phase-separated catalytic overlayer onto the conventional catalyst layer. A MEA prepared using the thin-film, dual-layered electrode exhibits 39-fold increased RH stability and 28-fold improved start-up recovery time during the on-off operation relative to the conventional device. We demonstrate the successful operation of the dual-layered electrode comprised of discriminatively phase-separated agglomerates with an ultrahigh zero RH fuel-cell performance reaching over 95 % performance of a fully humidified MEA. Copyright © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Carbon-coated Li3 N nanofibers for advanced hydrogen storage.

PubMed

Xia, Guanglin; Li, Dan; Chen, Xiaowei; Tan, Yingbin; Tang, Ziwei; Guo, Zaiping; Liu, Huakun; Liu, Zongwen; Yu, Xuebin

2013-11-20

3D porous carbon-coated Li3 N nanofibers are successfully fabricated via the electrospinning technique. The as-prepared nanofibers exhibit a highly improved hydrogen-sorption performance in terms of both thermodynamics and kinetics. More interestingly, a stable regeneration can be achieved due to the unique structure of the nanofibers, over 10 cycles of H2 sorption at a temperature as low as 250 °C. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Medium scale carbon nanotube thin film integrated circuits on flexible plastic substrates

DOEpatents

Rogers, John A; Cao, Qing; Alam, Muhammad; Pimparkar, Ninad

2015-02-03

The present invention provides device components geometries and fabrication strategies for enhancing the electronic performance of electronic devices based on thin films of randomly oriented or partially aligned semiconducting nanotubes. In certain aspects, devices and methods of the present invention incorporate a patterned layer of randomly oriented or partially aligned carbon nanotubes, such as one or more interconnected SWNT networks, providing a semiconductor channel exhibiting improved electronic properties relative to conventional nanotubes-based electronic systems.

Transgenic tobacco plants with improved cyanobacterial Rubisco expression but no extra assembly factors grow at near wild-type rates if provided with elevated CO2

PubMed Central

Occhialini, Alessandro; Lin, Myat T.; Andralojc, P. John; Hanson, Maureen R.; Parry, Martin A. J.

2015-01-01

SUMMARY Introducing a carbon concentrating mechanism and a faster Rubisco from cyanobacteria into higher plant chloroplasts could improve photosynthetic performance by increasing the rate of CO2 fixation while decreasing losses caused by photorespiration. We previously demonstrated that tobacco plants will grow photoautotrophically using Synechococcus elongatus Rubisco, although the plants exhibited considerably slower growth than wild-type and required supplementary CO2. Because of concerns that vascular plant assembly factors might not be adequate for assembly of a cyanobacterial Rubisco, prior transgenic plants included the cyanobacterial chaperone RbcX or the carboxysomal protein CcmM35. Here we show that neither RbcX nor CcmM35 is needed for assembly of active cyanobacterial Rubisco. Furthermore, by altering the gene regulatory sequences on the Rubisco transgenes, cyanobacterial Rubisco expression was enhanced and the transgenic plants grew at near wild-type growth rates, though still requiring elevated CO2. We performed detailed kinetic characterization of the enzymes produced with and without the RbcX and CcmM35 cyanobacterial proteins. These transgenic plants exhibit photosynthetic characteristics that confirm the predicted benefits of non-native forms of Rubisco with higher carboxylation rate constants in vascular plants and the potential nitrogen use efficiency that may be gained provided that adequate CO2 can be concentrated near the enzyme. PMID:26662726

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tan, Guoqiang; Bao, Wurigumula; Yuan, Yifei

To spread lithium ion batteries into large-scale energy storage technologies, high ener-gy/power densities and long cycling life of carbon-based anodes must be achieved. This re-quires revolutionary design of the anode’s architectures that can facilitate the fast electronic and ionic transport, as well as accommodate the electrode structural instability. Here we re-port a thin-film electrode design and demonstrate its use in flexible, and large-area carbon-based anode assemblies. The fabrication of electrodes is realized by sputtering a graphite tar-get in the high-purity nitrogen atmosphere, then highly-defect nitrogen-doped carbon nano-fibers are deposited vertically onto copper substrates with a thin film configuration. The high-ly-defectmore » nitrogen-doping enhances the lithium storage and transport, the orientation grown mechanism improves the charge transfer, and the compact configuration makes the high tap density possible. As a result, the thin films exhibit high specific capacities of ~ 500 mAh g-1, namely a volume capacity of ~ 100 mAh cm-3. They also exhibit stable cycle performance (400 mAh g-1 after 200 cycles) and good rate capability (450 mAh g-1 at 1 A g-1 rate). This work opens up a new carbon-based anode design by using sputtering technology for effec-tively incorporating high content nitrogen into carbon matrices. Such electrode architecture significantly improves the electrochemical performance of carbon-based materials.« less

The treatment with pyridostigmine improves the cardiocirculatory function in rats with chronic heart failure.

PubMed

Sabino, João Paulo J; da Silva, Carlos Alberto Aguiar; de Melo, Rubens Fernando; Fazan, Rubens; Salgado, Helio C

2013-01-01

Sympathetic hyperactivity and its outcome in heart failure have been thoroughly investigated to determine the focus of pharmacologic approaches targeting the sympathetic nervous system in the treatment of this pathophysiological condition. On the other hand, therapeutic approaches aiming to protect the reduced cardiac parasympathetic function have not received much attention. The present study evaluated rats with chronic heart failure (six to seven weeks after coronary artery ligation) and the effects of an increased parasympathetic function by pyridostigmine (an acetylcholinesterase inhibitor) on the following aspects: arterial pressure (AP), heart rate (HR), baroreceptor and Bezold-Jarisch reflex, pulse interval (PI) and AP variability, cardiac sympathetic and parasympathetic tonus, intrinsic heart rate (i-HR) and cardiac function. Conscious rats with heart failure exhibited no change in HR, Bezold-Jarisch reflex, PI variability and cardiac sympathetic tonus. On the other hand, these animals presented hypotension and reduced baroreflex sensitivity, power in the low frequency (LF) band of the systolic AP spectrum, cardiac parasympathetic tonus and i-HR, while anesthetized rats exhibited reduced cardiac performance. Pyridostigmine prevented the attenuation of all the parameters examined, except basal AP and cardiac performance. In conclusion, the blockade of acetylcholinesterase with pyridostigmine was revealed to be an important pharmacological approach, which could be used to increase parasympathetic function and to improve a number of cardiocirculatory parameters in rats with heart failure. Copyright © 2012 Elsevier B.V. All rights reserved.

Toward High Performance 2D/2D Hybrid Photocatalyst by Electrostatic Assembly of Rationally Modified Carbon Nitride on Reduced Graphene Oxide

NASA Astrophysics Data System (ADS)

Chen, Jian; Xu, Xiaochan; Li, Tao; Pandiselvi, Kannusamy; Wang, Jingyu

2016-11-01

Efficient metal-free visible photocatalysts with high stability are highly desired for sufficient utilization of solar energy. In this work, the popular carbon nitride (CN) photocatalyst is rationally modified by acid exfoliation of molecular grafted CN, achieving improved visible-light utilization and charge carriers mobility. Moreover, the modification process tuned the surface electrical property of CN, which enabled it to be readily coupled with the oppositely charged graphene oxide during the following photo-assisted electrostatic assembly. Detailed characterizations indicate the formation of well-contacted 2D/2D heterostructure with strong interfacial interaction between the modified CN nanosheets (CNX-NSs) and reduced graphene oxide (RGO). The optimized hybrid (with a RGO ratio of 20%) exhibits the best photocatalytic performance toward MB degradation, which is almost 12.5 and 7.0 times of CN under full spectrum and visible-light irradiation, respectively. In addition, the hybrid exhibits high stability after five successive cycles with no obvious change in efficiency. Unlike pure CNX-NSs, the dye decomposition mostly depends on the H2O2 generation by a two-electron process due to the electron reservoir property of RGO. Thus the enhancement in photocatalytic activity could be ascribed to the improved light utilization and increased charge transfer ability across the interface of CNX-NSs/RGO heterostructure.

Free-Standing Hybrid Graphene Paper Encapsulating Nanostructures for High Cycle-Life Supercapacitors.

PubMed

Jiao, Xinyan; Hao, Qingli; Xia, Xifeng; Lei, Wu; Ouyang, Yu; Ye, Haitao; Mandler, Daniel

2018-03-09

The incorporation of spacers between graphene sheets has been investigated as an effective method to improve the electrochemical performance of graphene papers (GPs) for supercapacitors. Here, we report the design of free-standing GP@NiO and GP@Ni hybrid GPs in which NiO nanoclusters and Ni nanoparticles are encapsulated into graphene sheets through electrostatic assembly and subsequent vacuum filtration. The encapsulated NiO nanoclusters and Ni nanoparticles can mitigate the restacking of graphene sheets, providing sufficient spaces for high-speed ion diffusion and electron transport. In addition, the spacers strongly bind to graphene sheets, which can efficiently improve the electrochemical stability. Therefore, at a current density of 0.5 A g -1 , the GP@NiO and GP@Ni electrodes exhibit higher specific capacitances of 306.9 and 246.1 F g -1 than the GP electrode (185.7 F g -1 ). The GP@NiO and GP@Ni electrodes exhibit capacitance retention of 98.7 % and 95.6 % after 10000 cycles, demonstrating an outstanding cycling stability. Additionally, the GP@NiO∥GP@Ni delivers excellent cycling stability (93.7 % after 10 000 cycles) and high energy density. These free-standing encapsulated hybrid GPs have great potential as electrode for high-performance supercapacitors. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

CO2 Plasma-Treated TiO2 Film as an Effective Electron Transport Layer for High-Performance Planar Perovskite Solar Cells.

PubMed

Wang, Kang; Zhao, Wenjing; Liu, Jia; Niu, Jinzhi; Liu, Yucheng; Ren, Xiaodong; Feng, Jiangshan; Liu, Zhike; Sun, Jie; Wang, Dapeng; Liu, Shengzhong Frank

2017-10-04

Perovskite solar cells (PSCs) have received great attention because of their excellent photovoltaic properties especially for the comparable efficiency to silicon solar cells. The electron transport layer (ETL) is regarded as a crucial medium in transporting electrons and blocking holes for PSCs. In this study, CO 2 plasma generated by plasma-enhanced chemical vapor deposition (PECVD) was introduced to modify the TiO 2 ETL. The results indicated that the CO 2 plasma-treated compact TiO 2 layer exhibited better surface hydrophilicity, higher conductivity, and lower bulk defect state density in comparison with the pristine TiO 2 film. The quality of the stoichiometric TiO 2 structure was improved, and the concentration of oxygen-deficiency-induced defect sites was reduced significantly after CO 2 plasma treatment for 90 s. The PSCs with the TiO 2 film treated by CO 2 plasma for 90 s exhibited simultaneously improved short-circuit current (J SC ) and fill factor. As a result, the PSC-based TiO 2 ETL with CO 2 plasma treatment affords a power conversion efficiency of 15.39%, outperforming that based on pristine TiO 2 (13.54%). These results indicate that the plasma treatment by the PECVD method is an effective approach to modify the ETL for high-performance planar PSCs.

Evaluating the mechanisms of improved glucose homeostasis after bariatric surgery in Ossabaw miniature swine.

PubMed

Sham, Jonathan G; Simianu, Vlad V; Wright, Andrew S; Stewart, Skye D; Alloosh, Mouhamad; Sturek, Michael; Cummings, David E; Flum, David R

2014-01-01

Roux-en-Y gastric bypass (RYGB) is the most common bariatric operation; however, the mechanism underlying the profound weight-independent effects on glucose homeostasis remains unclear. Large animal models of naturally occurring insulin resistance (IR), which have been lacking, would provide opportunities to elucidate such mechanisms. Ossabaw miniature swine naturally exhibit many features that may be useful in evaluating the anti diabetic effects of bariatric surgery. Glucose homeostasis was studied in 53 Ossabaw swine. Thirty-two received an obesogenic diet and were randomized to RYGB, gastrojejunostomy (GJ), gastrojejunostomy with duodenal exclusion (GJD), or Sham operations. Intravenous glucose tolerance tests and standardized meal tolerance tests were performed prior to, 1, 2, and 8 weeks after surgery and at a single time-point for regular diet control pigs. High-calorie-fed Ossabaws weighed more and had greater IR than regular diet controls, though only 70% developed IR. All operations caused weight-loss-independent improvement in IR, though only in pigs with high baseline IR. Only RYGB induced weight loss and decreased IR in the majority of pigs, as well as increasing AUCinsulin/AUCglucose. Similar to humans, Ossabaw swine exhibit both obesity-dependent and obesity-independent IR. RYGB promoted weight loss, IR improvement, and increased AUCinsulin/AUCglucose, compared to the smaller changes following GJ and GJD, suggesting a combination of upper and lower gut mechanisms in improving glucose homeostasis.

7 CFR Exhibit E to Subpart N of... - Guide For Quarterly Performance Report

Code of Federal Regulations, 2011 CFR

2011-01-01

... 7 Agriculture 13 2011-01-01 2009-01-01 true Guide For Quarterly Performance Report E Exhibit E to Subpart N of Part 1944 Agriculture Regulations of the Department of Agriculture (Continued) RURAL HOUSING.... 1944, Subpt. N, Exh. E Exhibit E to Subpart N of Part 1944—Guide For Quarterly Performance Report...

7 CFR Exhibit G to Subpart A of... - Performance Bond

Code of Federal Regulations, 2013 CFR

2013-01-01

... 7 Agriculture 12 2013-01-01 2013-01-01 false Performance Bond G Exhibit G to Subpart A of Part 1924 Agriculture Regulations of the Department of Agriculture (Continued) RURAL HOUSING SERVICE, RURAL.... 1924, Subpt. A, Exh. G Exhibit G to Subpart A of Part 1924—Performance Bond KNOW ALL PERSONS BY THESE...

7 CFR Exhibit E to Subpart N of... - Guide For Quarterly Performance Report

Code of Federal Regulations, 2010 CFR

2010-01-01

... 7 Agriculture 13 2010-01-01 2009-01-01 true Guide For Quarterly Performance Report E Exhibit E to Subpart N of Part 1944 Agriculture Regulations of the Department of Agriculture (Continued) RURAL HOUSING.... 1944, Subpt. N, Exh. E Exhibit E to Subpart N of Part 1944—Guide For Quarterly Performance Report...

7 CFR Exhibit E to Subpart N of... - Guide For Quarterly Performance Report

Code of Federal Regulations, 2012 CFR

2012-01-01

... 7 Agriculture 13 2012-01-01 2012-01-01 false Guide For Quarterly Performance Report E Exhibit E to.... 1944, Subpt. N, Exh. E Exhibit E to Subpart N of Part 1944—Guide For Quarterly Performance Report...: (___% Rate) ___ This Quarter Total ___ B. Use of Program Funds: Budgeted Amount ___ Expended Thru Last...

7 CFR Exhibit E to Subpart N of... - Guide For Quarterly Performance Report

Code of Federal Regulations, 2013 CFR

2013-01-01

... 7 Agriculture 13 2013-01-01 2013-01-01 false Guide For Quarterly Performance Report E Exhibit E to.... 1944, Subpt. N, Exh. E Exhibit E to Subpart N of Part 1944—Guide For Quarterly Performance Report...: (___% Rate) ___ This Quarter Total ___ B. Use of Program Funds: Budgeted Amount ___ Expended Thru Last...

7 CFR Exhibit E to Subpart N of... - Guide For Quarterly Performance Report

Code of Federal Regulations, 2014 CFR

2014-01-01

... 7 Agriculture 13 2014-01-01 2013-01-01 true Guide For Quarterly Performance Report E Exhibit E to.... 1944, Subpt. N, Exh. E Exhibit E to Subpart N of Part 1944—Guide For Quarterly Performance Report...: (___% Rate) ___ This Quarter Total ___ B. Use of Program Funds: Budgeted Amount ___ Expended Thru Last...

Decrease of oxygen vacancy by Zn-doped for improving solar-blind photoelectric performance in β-Ga2O3 thin films

NASA Astrophysics Data System (ADS)

Guo, Daoyou; Qin, Xinyuan; Lv, Ming; Shi, Haoze; Su, Yuanli; Yao, Guosheng; Wang, Shunli; Li, Chaorong; Li, Peigang; Tang, Weihua

2017-11-01

Highly (201) oriented Zn-doped β-Ga2O3 thin films with different dopant concentrations were grown on (0001) sapphire substrates by radio frequency magnetron sputtering. With the increase of Zn dopant concentration, the crystal lattice expands, the energy band gap shrinks, and the oxygen vacancy concentration decreases. Both the metal semiconductor metal (MSM) structure photodetectors based on the pure and Zn-doped β-Ga2O3 thin films exhibit solar blind UV photoelectric property. Compared to the pure β-Ga2O3 photodetector, the Zn-doped one exhibits a lower dark current, a higher photo/dark current ratio, a faster photoresponse speed, which can be attributed to the decreases of oxygen vacancy concentration.[Figure not available: see fulltext.

Hydrothermally grown β-V₂O₅ electrode at 95°C.

PubMed

Vernardou, D; Apostolopoulou, M; Louloudakis, D; Katsarakis, N; Koudoumas, E

2014-06-15

The hydrothermal growth of crystalline β-V2O5 microstructures was performed on fluorine doped tin dioxide glass substrates using oxalic acid to adjust the pH of the solution for various deposition periods. It was observed that the sample grown for 48 h at pH 2 exhibited the best electrochemical response in terms of the highest specific charge and capacitance, being 772 C g(-1) and 386 F g(-1) respectively. The importance of achieving high crystalline quality samples and increased surface area toward the improvement of the electrochemical performance of β-V2O5 is highlighted. Copyright © 2014 Elsevier Inc. All rights reserved.

Charge-discharge characteristics of nickel/zinc battery with polymer hydrogel electrolyte

NASA Astrophysics Data System (ADS)

Iwakura, Chiaki; Murakami, Hiroki; Nohara, Shinji; Furukawa, Naoji; Inoue, Hiroshi

A new nickel/zinc (Ni/Zn) battery was assembled by using polymer hydrogel electrolyte prepared from cross-linked potassium poly(acrylate) and KOH aqueous solution, and its charge-discharge characteristics were investigated. The experimental Ni/Zn cell with the polymer hydrogel electrolyte exhibited well-defined charge-discharge curves and remarkably improved charge-discharge cycle performance, compared to that with a KOH aqueous solution. Moreover, it was found that dendritic growth hardly occurred on the zinc electrode surface during charge-discharge cycles in the polymer hydrogel electrolyte. These results indicate that the polymer hydrogel electrolyte can successfully be used in Ni/Zn batteries as an electrolyte with excellent performance.

Succession planning in hospitals and the association with organizational performance.

PubMed

Kim, Tae Hyun

2012-01-01

Effective succession planning is the heart of leadership development and an essential business strategy because it enhances the ability to achieve orderly transitions and maintain productivity levels. The results of this study are consistent with previous studies that exhibit a positive association of previous years' performance with internal succession planning. The key to successful succession planning lies in building a solid foundation of profitability. Having successors ready to fill key vacancies helps improve operational condition and the bottom line, and thus, gives a competitive edge in the market. Preparing successors for leadership may determine which organizations simply survive and which thrive and lead their markets down the road.

Flat dielectric metasurface lens array for three dimensional integral imaging

NASA Astrophysics Data System (ADS)

Zhang, Jianlei; Wang, Xiaorui; Yang, Yi; Yuan, Ying; Wu, Xiongxiong

2018-05-01

In conventional integral imaging, the singlet refractive lens array limits the imaging performance due to its prominent aberrations. Different from the refractive lens array relying on phase modulation via phase change accumulated along the optical paths, metasurfaces composed of nano-scatters can produce phase abrupt over the scale of wavelength. In this letter, we propose a novel lens array consisting of two neighboring flat dielectric metasurfaces for integral imaging system. The aspherical phase profiles of the metasurfaces are optimized to improve imaging performance. The simulation results show that our designed 5 × 5 metasurface-based lens array exhibits high image quality at designed wavelength 865 nm.

Supercapacitor

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Donghai; Yi, Ran; Chen, Shuru

Embodiments provide a hybrid supercapacitor exhibiting high energy and power densities enabled by a high-performance lithium-alloy anode coupled with a porous carbon cathode in an electrolyte containing lithium salt. Embodiments include a size reduced silicon oxide anode, a boron-doped silicon oxide anode, and/or a carbon coated silicon oxide anode, which may improve cycling stability and rate performance. Further embodiments include a hybrid supercapacitor system using a Li-active anode in an electrolyte including LiPF6 in a mixture of ethylene carbonate, diethyl carbonate, and dimethyl carbonate (EC:DEC:DMC, 2:1:2 by vol.) and 10 wt % fluoroethylene carbonate (FEC), which may reduce the self-dischargemore » rate.« less

Application of distributed optical fiber sensing technologies to the monitoring of leakage and abnormal disturbance of oil pipeline

NASA Astrophysics Data System (ADS)

Yang, Xiaojun; Zhu, Xiaofei; Deng, Chi; Li, Junyi; Liu, Cheng; Yu, Wenpeng; Luo, Hui

2017-10-01

To improve the level of management and monitoring of leakage and abnormal disturbance of long distance oil pipeline, the distributed optical fiber temperature and vibration sensing system is employed to test the feasibility for the healthy monitoring of a domestic oil pipeline. The simulating leakage and abnormal disturbance affairs of oil pipeline are performed in the experiment. It is demonstrated that the leakage and abnormal disturbance affairs of oil pipeline can be monitored and located accurately with the distributed optical fiber sensing system, which exhibits good performance in the sensitivity, reliability, operation and maintenance etc., and shows good market application prospect.

Wafer-scale solution-derived molecular gate dielectrics for low-voltage graphene electronics

NASA Astrophysics Data System (ADS)

Sangwan, Vinod K.; Jariwala, Deep; Everaerts, Ken; McMorrow, Julian J.; He, Jianting; Grayson, Matthew; Lauhon, Lincoln J.; Marks, Tobin J.; Hersam, Mark C.

2014-02-01

Graphene field-effect transistors are integrated with solution-processed multilayer hybrid organic-inorganic self-assembled nanodielectrics (SANDs). The resulting devices exhibit low-operating voltage (2 V), negligible hysteresis, current saturation with intrinsic gain >1.0 in vacuum (pressure < 2 × 10-5 Torr), and overall improved performance compared to control devices on conventional SiO2 gate dielectrics. Statistical analysis of the field-effect mobility and residual carrier concentration demonstrate high spatial uniformity of the dielectric interfacial properties and graphene transistor characteristics over full 3 in. wafers. This work thus establishes SANDs as an effective platform for large-area, high-performance graphene electronics.

High surface area TiO2/SBA-15 nanocomposites: Synthesis, microstructure and adsorption-enhanced photocatalysis

NASA Astrophysics Data System (ADS)

Wei, J. Q.; Chen, X. J.; Wang, P. F.; Han, Y. B.; Xu, J. C.; Hong, B.; Jin, H. X.; Jin, D. F.; Peng, X. L.; Li, J.; Yang, Y. T.; Ge, H. L.; Wang, X. Q.

2018-06-01

Mesoporous SBA-15 was used to anchor TiO2 nanoparticles into the mesopores to form high surface area TiO2/SBA-15 nanocomposites, and then the influence of mesoporous-structure on the photocatalytic performance was investigated. TiO2/SBA-15 nanocomposites possessed the high specific surface area and appropriate pore size, indicating the excellent adsorption performance. TiO2/SBA-15 nanocomposites exhibited the higher photocatalytic activity to degrade dyes (methylene blue: MB) than TiO2 (removing SBA-15), which should attributed to the excellent adsorption performance of the nanocomposites. MB was absorbed to form the higher concentration near TiO2/SBA-15 photocatalysts, and the photocatalytic degradation for MB was improved.

An Effective Cache Algorithm for Heterogeneous Storage Systems

PubMed Central

Li, Yong; Feng, Dan

2013-01-01

Modern storage environment is commonly composed of heterogeneous storage devices. However, traditional cache algorithms exhibit performance degradation in heterogeneous storage systems because they were not designed to work with the diverse performance characteristics. In this paper, we present a new cache algorithm called HCM for heterogeneous storage systems. The HCM algorithm partitions the cache among the disks and adopts an effective scheme to balance the work across the disks. Furthermore, it applies benefit-cost analysis to choose the best allocation of cache block to improve the performance. Conducting simulations with a variety of traces and a wide range of cache size, our experiments show that HCM significantly outperforms the existing state-of-the-art storage-aware cache algorithms. PMID:24453890

Enhancing performance and surface antifouling properties of polysulfone ultrafiltration membranes with salicylate-alumoxane nanoparticles

NASA Astrophysics Data System (ADS)

Mokhtari, Samaneh; Rahimpour, Ahmad; Shamsabadi, Ahmad Arabi; Habibzadeh, Setareh; Soroush, Masoud

2017-01-01

To improve the hydrophilicity and antifouling properties of polysulfone (PS) ultrafiltration membranes, we studied the use of salicylate-alumoxane (SA) nanoparticles as a novel hydrophilic additive. The effects of SA nanoparticles on the membrane characteristics and performance were investigated in terms of membrane structure, permeation flux, solute rejection, hydrophilicity, and antifouling ability. The new mixed-matrix membranes (MMMs) possess asymmetric structures. They have smaller finger-like pores and smoother surfaces than the neat PS membranes. The embedment of SA nanoparticles in the polymer matrix and the improvement of surface hydrophilicity were investigated. Ultrafiltration experiments indicated that the pure-water flux of the new MMMs initially increases with SA nanoparticles loading followed by a decrease at high loadings. Higher BSA solution flux was achieved for the MMMs compared to the neat PS membranes. Membranes with 1 wt.% SA nanoparticles exhibit the highest flux recovery ratio of 87% and the lowest irreversible fouling of 13%.

Hexagonal boron nitride intercalated multi-layer graphene: a possible ultimate solution to ultra-scaled interconnect technology

NASA Astrophysics Data System (ADS)

Li, Yong-Jun; Sun, Qing-Qing; Chen, Lin; Zhou, Peng; Wang, Peng-Fei; Ding, Shi-Jin; Zhang, David Wei

2012-03-01

We proposed intercalation of hexagonal boron nitride (hBN) in multilayer graphene to improve its performance in ultra-scaled interconnects for integrated circuit. The effect of intercalated hBN layer in bilayer graphene is investigated using non-equilibrium Green's functions. We find the hBN intercalated bilayer graphene exhibit enhanced transport properties compared with pristine bilayer ones, and the improvement is attributed to suppression of interlayer scattering and good planar bonding condition of inbetween hBN layer. Based on these results, we proposed a via structure that not only benefits from suppressed interlayer scattering between multilayer graphene, but also sustains the unique electrical properties of graphene when many graphene layers are stacking together. The ideal current density across the structure can be as high as 4.6×109 A/cm2 at 1V, which is very promising for the future high-performance interconnect.

Spectroscopic and Electrochemical Properties of Lithium-Rich LiFePO4 Cathode Synthesized by Solid-State Reaction

NASA Astrophysics Data System (ADS)

Rosaiah, P.; Hussain, O. M.; Zhu, Jinghui; Qiu, Yejun

2017-08-01

Lithium iron phosphate (Li x FePO4) is synthesized by a solid-state reaction method. The structural, electrical and electrochemical properties are studied in detail. It is found that the increment of lithium concentration (up to x = 1.05) does not affect the structure of LiFePO4 but improves its electrical conductivity as well as electrochemical performance. Surface morphological studies exhibited the formation of rod-like nanoparticles with small size. Electric and dielectric properties are also investigated over a frequency range of 1 Hz-1 MHz at different temperatures. The conductivity increased with increasing temperature, which follows the Arrhenius relation with the activation energy of about 0.31 eV. And the electrochemical tests found that the Li1.05FePO4 cathode possessed improved discharge capacity with better cycling performance.

Enhanced ethylene separation and plasticization resistance in polymer membranes incorporating metal-organic framework nanocrystals.

PubMed

Bachman, Jonathan E; Smith, Zachary P; Li, Tao; Xu, Ting; Long, Jeffrey R

2016-08-01

The implementation of membrane-based separations in the petrochemical industry has the potential to reduce energy consumption significantly relative to conventional separation processes. Achieving this goal, however, requires the development of new membrane materials with greater selectivity, permeability and stability than available at present. Here, we report composite materials consisting of nanocrystals of metal-organic frameworks dispersed within a high-performance polyimide, which can exhibit enhanced selectivity for ethylene over ethane, greater ethylene permeability and improved membrane stability. Our results suggest that framework-polymer interactions reduce chain mobility of the polymer while simultaneously boosting membrane separation performance. The increased stability, or plasticization resistance, is expected to improve membrane utility under real process conditions for petrochemical separations and natural gas purification. Furthermore, this approach can be broadly applied to numerous polymers that encounter aggressive environments, potentially making gas separations possible that were previously inaccessible to membranes.

Enhancing adsorption of U(VI) onto EDTA modified L. cylindrica using epichlorohydrin and ethylenediamine as a bridge

PubMed Central

Su, Shouzheng; Liu, Qi; Liu, Jingyuan; Zhang, Hongsen; Li, Rumin; Jing, Xiaoyan; Wang, Jun

2017-01-01

Benefiting from strong coordination ability and unique vascular structure, EDTA modified L. cylindrica opens up an alternative way for uranium recovery from seawater. However, limitations, such as poor adsorption capacity and slow adsorption rate due to low graft ratio of EDTA via one-step esterification block its practical application. Here, a strategy for increasing the graft ratio is proposed in order to improve the adsorption performance. The strategy initially involves immobilization of epichlorohydrin (EPI) onto L. cylindrica and then ethylenediamine (EDA) is introduced via facile ring-opening reaction. EPI and EDA serve as a bridge between L. cylindrica and EDTA. The graft ratio is promoted (15.01 to 21.44%) contributing to the smaller steric hindrance of EPI and EDA than EDTA and improvement in adsorption performance. In addition, the adsorbent prepared by the new strategy exhibits excellent adsorption properties in simulated seawater. PMID:28272435

Secondary-Phase Stochastics in Lithium-Ion Battery Electrodes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mistry, Aashutosh N.; Smith, Kandler; Mukherjee, Partha P.

Lithium-ion battery electrodes exhibit complex interplay among multiple electrochemically coupled transport processes, which rely on the underlying functionality and relative arrangement of different constituent phases. The electrochemically inactive solid phases (e.g., conductive additive and binder, referred to as the secondary phase), while beneficial for improved electronic conductivity and mechanical integrity, may partially block the electrochemically active sites and introduce additional transport resistances in the pore (electrolyte) phase. In this work, the role of mesoscale interactions and inherent stochasticity in porous electrodes is elucidated in the context of short-range (interface) and long-range (transport) characteristics. The electrode microstructure significantly affects kinetically andmore » transport-limiting scenarios and thereby the cell performance. The secondary-phase morphology is also found to strongly influence the microstructure-transport-kinetics interactions. Apropos, strategies have been proposed for performance improvement via electrode microstructural modifications.« less

Secondary-Phase Stochastics in Lithium-Ion Battery Electrodes

DOE PAGES

Mistry, Aashutosh N.; Smith, Kandler; Mukherjee, Partha P.

2018-01-12

Lithium-ion battery electrodes exhibit complex interplay among multiple electrochemically coupled transport processes, which rely on the underlying functionality and relative arrangement of different constituent phases. The electrochemically inactive solid phases (e.g., conductive additive and binder, referred to as the secondary phase), while beneficial for improved electronic conductivity and mechanical integrity, may partially block the electrochemically active sites and introduce additional transport resistances in the pore (electrolyte) phase. In this work, the role of mesoscale interactions and inherent stochasticity in porous electrodes is elucidated in the context of short-range (interface) and long-range (transport) characteristics. The electrode microstructure significantly affects kinetically andmore » transport-limiting scenarios and thereby the cell performance. The secondary-phase morphology is also found to strongly influence the microstructure-transport-kinetics interactions. Apropos, strategies have been proposed for performance improvement via electrode microstructural modifications.« less

Device simulation of GeSn/GeSiSn pocket n-type tunnel field-effect transistor for analog and RF applications

NASA Astrophysics Data System (ADS)

Wang, Suyuan; Zheng, Jun; Xue, Chunlai; Li, Chuanbo; Zuo, Yuhua; Cheng, Buwen; Wang, Qiming

2017-11-01

We present the device simulations of analog and radio frequency (RF) performances of four double-gate pocket n-type tunneling field-effect transistors (NTFETs). The direct current (DC), analog and RF performances of the Ge-homo, GeSn-homo, GeSn/Ge and GeSn/GeSiSn NTFETs, are compared. The GeSn NTFETs greatly improve the on-state current (ION) and average subthreshold slope (SS), when compared with the Ge NTFET. Moreover, the GeSn/GeSiSn NTFET has the largest intrinsic gain (Av), and exhibits a suppressed ambipolar behavior, improved cut-off frequency (fT), and gain bandwidth product (GBW), according to the analyzed analog and RF figures of merit (FOM). Therefore, it can be concluded that the GeSn/GeSiSn NTFET has great potential as a promising candidate for the realization of future generation low-power analog/RF applications.

NASTRAN implementation of an isoparametric doubly-curved quadrilateral shell element

NASA Technical Reports Server (NTRS)

Potvin, A. B.; Leick, R. D.

1978-01-01

A quadrilateral shell element, CQUAD4, was added to level 15.5 and subsequently to level 16.0 of NASTRAN. The element exhibited doubly curved surfaces and used biquadratic interpolation functions. Reduced integration techniques were used to improve the performance of the element in thin shell problems. The creation of several new bulk data items is discussed, along with a special module, GPNORM, to process SHLNORM bulk data cards. In addition to the theoretical basis for the element stiffness matrix, consistent mass and load matrices are presented. Several potential sources of degenerate behavior of the element were investigated. Guidelines for proper use of the element were suggested. Performance of the element on several widely published classical examples was demonstrated. The results showed a significant improvement over presently available NASTRAN shell elements for even the coarsest meshes. Potential applications to two classes of practical problems are discussed.

Peptide-based protein capture agents with high affinity, selectivity, and stability as antibody replacements in biodetection assays

NASA Astrophysics Data System (ADS)

Coppock, Matthew B.; Farrow, Blake; Warner, Candice; Finch, Amethist S.; Lai, Bert; Sarkes, Deborah A.; Heath, James R.; Stratis-Cullum, Dimitra

2014-05-01

Current biodetection assays that employ monoclonal antibodies as primary capture agents exhibit limited fieldability, shelf life, and performance due to batch-to-batch production variability and restricted thermal stability. In order to improve upon the detection of biological threats in fieldable assays and systems for the Army, we are investigating protein catalyzed capture (PCC) agents as drop-in replacements for the existing antibody technology through iterative in situ click chemistry. The PCC agent oligopeptides are developed against known protein epitopes and can be mass produced using robotic methods. In this work, a PCC agent under development will be discussed. The performance, including affinity, selectivity, and stability of the capture agent technology, is analyzed by immunoprecipitation, western blotting, and ELISA experiments. The oligopeptide demonstrates superb selectivity coupled with high affinity through multi-ligand design, and improved thermal, chemical, and biochemical stability due to non-natural amino acid PCC agent design.

Effect of flashlight guidance on manual ventilation performance in cardiopulmonary resuscitation: A randomized controlled simulation study.

PubMed

Kim, Ji Hoon; Beom, Jin Ho; You, Je Sung; Cho, Junho; Min, In Kyung; Chung, Hyun Soo

2018-01-01

Several auditory-based feedback devices have been developed to improve the quality of ventilation performance during cardiopulmonary resuscitation (CPR), but their effectiveness has not been proven in actual CPR situations. In the present study, we investigated the effectiveness of visual flashlight guidance in maintaining high-quality ventilation performance. We conducted a simulation-based, randomized, parallel trial including 121 senior medical students. All participants were randomized to perform ventilation during 2 minutes of CPR with or without flashlight guidance. For each participant, we measured mean ventilation rate as a primary outcome and ventilation volume, inspiration velocity, and ventilation interval as secondary outcomes using a computerized device system. Mean ventilation rate did not significantly differ between flashlight guidance and control groups (P = 0.159), but participants in the flashlight guidance group exhibited significantly less variation in ventilation rate than participants in the control group (P<0.001). Ventilation interval was also more regular among participants in the flashlight guidance group. Our results demonstrate that flashlight guidance is effective in maintaining a constant ventilation rate and interval. If confirmed by further studies in clinical practice, flashlight guidance could be expected to improve the quality of ventilation performed during CPR.

AMOLED (active matrix OLED) functionality and usable lifetime at temperature

NASA Astrophysics Data System (ADS)

Fellowes, David A.; Wood, Michael V.; Prache, Olivier; Jones, Susan

2005-05-01

Active Matrix Organic Light Emitting Diode (AMOLED) displays are known to exhibit high levels of performance, and these levels of performance have continually been improved over time with new materials and electronics design. eMagin Corporation developed a manually adjustable temperature compensation circuit with brightness control to allow for excellent performance over a wide temperature range. Night Vision and Electronic Sensors Directorate (US Army) tested the performance and survivability of a number of AMOLED displays in a temperature chamber over a range from -55°C to +85°C. Although device performance of AMOLEDs has always been its strong suit, the issue of usable display lifetimes for military applications continues to be an area of discussion and research. eMagin has made improvements in OLED materials and worked towards the development of a better understanding of usable lifetime for operation in a military system. NVESD ran luminance degradation tests of AMOLED panels at 50°C and at ambient to characterize the lifetime of AMOLED devices. The result is a better understanding of the applicability of AMOLEDs in military systems: where good fits are made, and where further development is needed.

Factors affecting student success in a first-year mathematics course: a South African experience

NASA Astrophysics Data System (ADS)

Kizito, Rita; Munyakazi, Justin; Basuayi, Clement

2016-01-01

In spite of sustained efforts tertiary institutions implement to try and improve student academic performance, the number of students succeeding in first-year mathematics courses remains disturbingly low. For most students, the gap between their mathematical capability and the competencies they are expected and need to develop to function effectively in these courses persists even after course instruction. In this study, an instrument for identifying and examining factors affecting student performance and success in a first-year Mathematics university course was developed and administered to 86 students. The overall Cronbach's Alpha coefficient for the questionnaire was found to be 0.916. Having identified variables from prior research known to affect student performance, factor analysis was used to identify variables exhibiting the greatest impact on student performance. The variables included prior academic knowledge, workload, student approaches to learning, assessment, student support teaching quality, methods and resources. From the analysis, students' perceptions of their workload emerged as the factor having the greatest impact on student's performance, followed by the matriculation examination score. The findings are discussed and strategies that can be used to improve teaching and contribute to student success in a first-year mathematics course in a South African context are presented.

Structural Design Strategies for Improved Small Overlap Crashworthiness Performance.

PubMed

Mueller, Becky C; Brethwaite, Andrew S; Zuby, David S; Nolan, Joseph M

2014-11-01

In 2012, the Insurance Institute for Highway Safety (IIHS) began a 64 km/h small overlap frontal crash test consumer information test program. Thirteen automakers already have redesigned models to improve test performance. One or more distinct strategies are evident in these redesigns: reinforcement of the occupant compartment, use of energy-absorbing fender structures, and the addition of engagement structures to induce vehicle lateral translation. Each strategy influences vehicle kinematics, posing additional challenges for the restraint systems. The objective of this two-part study was to examine how vehicles were modified to improve small overlap test performance and then to examine how these modifications affect dummy response and restraint system performance. Among eight models tested before and after design changes, occupant compartment intrusion reductions ranged from 6 cm to 45 cm, with the highest reductions observed in models with the largest number of modifications. All redesigns included additional occupant compartment reinforcement, one-third added structures to engage the barrier, and two modified a shotgun load path. Designs with engagement structures produced greater glance-off from the barrier and exhibited lower delta Vs but experienced more lateral outboard motion of the dummy. Designs with heavy reinforcement of the occupant compartment had higher vehicle accelerations and delta V. In three cases, these apparent trade-offs were not well addressed by concurrent changes in restraint systems and resulted in increased injury risk compared with the original tests. Among the 36 models tested after design changes, the extent of design changes correlated to structural performance. Half of the vehicles with the lowest intrusion levels incorporated aspects of all three design strategies. Vehicle kinematics and dummy and restraint system characteristics were similar to those observed in the before/after pairs. Different combinations of structural improvement strategies for improving small overlap test performance were found to be effective in reducing occupant compartment intrusion and improving dummy kinematics in the IIHS small overlap test with modest weight increase.

RGO modified Ni doped FeOOH for enhanced electrochemical and photoelectrochemical water oxidation

NASA Astrophysics Data System (ADS)

Zhang, Xiaofan; Zhang, Bingyan; Liu, Shuangshuang; Kang, Hongwei; Kong, Weiqian; Zhang, Shouren; Shen, Yan; Yang, Baocheng

2018-04-01

Ni,Fe-based (oxy)hydroxides have been one of the most active catalysts for the oxygen evolution reaction. In this article, reduced graphene oxide supported Ni doped FeOOH (RGO/Ni:FeOOH) was prepared for electrochemical and photoelectrochemical (PEC) water oxidation. The RGO/Ni:FeOOH exhibited a lower over-potential (260 mV at 10 mA cm-2) and smaller Tafel slope (32.3 mV dec-1) than that of the FeOOH and Ni:FeOOH. Such significant enhancement is attributed to Ni doping and RGO, which reduce the over-potential, improve the conductivity and enlarge surface areas. Besides, RGO/Ni:FeOOH decorated the TiO2 nanorods (NRs) was also fabricated for photoelectrochemical (PEC) water oxidation, which exhibited a higher photocurrent density and lower onset potential than that of TiO2 NRs the bare under illumination due to the synergistic effect of RGO and Ni:FeOOH. These results demonstrate the RGO/Ni:FeOOH has great promising as a co-catalyst to improve the PEC performance.

Engineering enhanced cellobiohydrolase activity

DOE Office of Scientific and Technical Information (OSTI.GOV)

Taylor, Larry E.; Knott, Brandon C.; Baker, John O.

Glycoside Hydrolase Family 7 cellobiohydrolases (GH7 CBHs) catalyze cellulose depolymerization in cellulolytic eukaryotes, making them key discovery and engineering targets. However, there remains a lack of robust structure–activity relationships for these industrially important cellulases. Here, we compare CBHs from Trichoderma reesei (TrCel7A) and Penicillium funiculosum (PfCel7A), which exhibit a multi-modular architecture consisting of catalytic domain (CD), carbohydrate-binding module, and linker. We show that PfCel7A exhibits 60% greater performance on biomass than TrCel7A. To understand the contribution of each domain to this improvement, we measure enzymatic activity for a library of CBH chimeras with swapped subdomains, demonstrating that the enhancement ismore » mainly caused by PfCel7A CD. We solve the crystal structure of PfCel7A CD and use this information to create a second library of TrCel7A CD mutants, identifying a TrCel7A double mutant with near-equivalent activity to wild-type PfCel7A. Overall, these results reveal CBH regions that enable targeted activity improvements.« less

Novel Water Soluble Chitosan Derivatives with 1,2,3-Triazolium and Their Free Radical-Scavenging Activity

PubMed Central

Li, Qing; Sun, Xueqi; Gu, Guodong

2018-01-01

Chitosan is an abundant and renewable polysaccharide, which exhibits attractive bioactivities and natural properties. Improvement such as chemical modification of chitosan is often performed for its potential of providing high bioactivity and good water solubility. A new class of chitosan derivatives possessing 1,2,3-triazolium charged units by associating “click reaction” with efficient 1,2,3-triazole quaternization were designed and synthesized. Their free radical-scavenging activity against three free radicals was tested. The inhibitory property and water solubility of the synthesized chitosan derivatives exhibited a remarkable improvement over chitosan. It is hypothesized that triazole or triazolium groups enable the synthesized chitosan to possess obviously better radical-scavenging activity. Moreover, the scavenging activity against superoxide radical of chitosan derivatives with triazolium (IC50 < 0.01 mg mL−1) was more efficient than that of derivatives with triazole and Vitamin C. In the 1,1-diphenyl-2-picrylhydrazyl (DPPH) and hydroxyl radical-scavenging assay, the same pattern were observed, which should be related to the triazolium grafted at the periphery of molecular chains. PMID:29597269

Novel Water Soluble Chitosan Derivatives with 1,2,3-Triazolium and Their Free Radical-Scavenging Activity.

PubMed

Li, Qing; Sun, Xueqi; Gu, Guodong; Guo, Zhanyong

2018-03-28

Chitosan is an abundant and renewable polysaccharide, which exhibits attractive bioactivities and natural properties. Improvement such as chemical modification of chitosan is often performed for its potential of providing high bioactivity and good water solubility. A new class of chitosan derivatives possessing 1,2,3-triazolium charged units by associating "click reaction" with efficient 1,2,3-triazole quaternization were designed and synthesized. Their free radical-scavenging activity against three free radicals was tested. The inhibitory property and water solubility of the synthesized chitosan derivatives exhibited a remarkable improvement over chitosan. It is hypothesized that triazole or triazolium groups enable the synthesized chitosan to possess obviously better radical-scavenging activity. Moreover, the scavenging activity against superoxide radical of chitosan derivatives with triazolium (IC 50 < 0.01 mg mL -1 ) was more efficient than that of derivatives with triazole and Vitamin C. In the 1,1-diphenyl-2-picrylhydrazyl (DPPH) and hydroxyl radical-scavenging assay, the same pattern were observed, which should be related to the triazolium grafted at the periphery of molecular chains.

Engineering enhanced cellobiohydrolase activity

DOE PAGES

Taylor, Larry E.; Knott, Brandon C.; Baker, John O.; ...

2018-03-22

Glycoside Hydrolase Family 7 cellobiohydrolases (GH7 CBHs) catalyze cellulose depolymerization in cellulolytic eukaryotes, making them key discovery and engineering targets. However, there remains a lack of robust structure–activity relationships for these industrially important cellulases. Here, we compare CBHs from Trichoderma reesei (TrCel7A) and Penicillium funiculosum (PfCel7A), which exhibit a multi-modular architecture consisting of catalytic domain (CD), carbohydrate-binding module, and linker. We show that PfCel7A exhibits 60% greater performance on biomass than TrCel7A. To understand the contribution of each domain to this improvement, we measure enzymatic activity for a library of CBH chimeras with swapped subdomains, demonstrating that the enhancement ismore » mainly caused by PfCel7A CD. We solve the crystal structure of PfCel7A CD and use this information to create a second library of TrCel7A CD mutants, identifying a TrCel7A double mutant with near-equivalent activity to wild-type PfCel7A. Overall, these results reveal CBH regions that enable targeted activity improvements.« less

Methanolic extract of Piper nigrum fruits improves memory impairment by decreasing brain oxidative stress in amyloid beta(1-42) rat model of Alzheimer's disease.

PubMed

Hritcu, Lucian; Noumedem, Jaurès A; Cioanca, Oana; Hancianu, Monica; Kuete, Victor; Mihasan, Marius

2014-04-01

The present study analyzed the possible memory-enhancing and antioxidant proprieties of the methanolic extract of Piper nigrum L. fruits (50 and 100 mg/kg, orally, for 21 days) in amyloid beta(1-42) rat model of Alzheimer's disease. The memory-enhancing effects of the plant extract were studied by means of in vivo (Y-maze and radial arm-maze tasks) approaches. Also, the antioxidant activity in the hippocampus was assessed using superoxide dismutase-, catalase-, glutathione peroxidase-specific activities and the total content of reduced glutathione, malondialdehyde, and protein carbonyl levels. The amyloid beta(1-42)-treated rats exhibited the following: decrease of spontaneous alternations percentage within Y-maze task and increase of working memory and reference memory errors within radial arm-maze task. Administration of the plant extract significantly improved memory performance and exhibited antioxidant potential. Our results suggest that the plant extract ameliorates amyloid beta(1-42)-induced spatial memory impairment by attenuation of the oxidative stress in the rat hippocampus.

Improved Mechanical Compatibility and Cytocompatibility of Ta/Ti Double-Layered Composite Coating

NASA Astrophysics Data System (ADS)

Ding, Ding; Xie, Youtao; Li, Kai; Huang, Liping; Zheng, Xuebin

2017-08-01

In order to improve the mechanical compatibility and cytocompatibility of titanium implants, a composite coating with double layers composed of tantalum and titanium was designed and prepared using plasma spraying technology. In the composite coating, the upper tantalum layer provides a good biocompatibility, and the sublayer of titanium with a porous structure ensures the low elastic modulus. Results show that the fabricated composite coating exhibits a relatively low elastic modulus of 26.7 GPa, which is close to the elastic modulus of human cortical bone. In vitro cytocompatibility evaluation of the composite coating shows that the human bone marrow stromal cells exhibit enhanced adhesion and spreading performance on the double-layered composite coating in comparison with the single-layered titanium coating. In order to eliminate the misgivings of chemical stability of the composite coating in clinical application, electrochemical corrosion of the coating was examined. The results obtained revealed a very weak galvanic corrosion between the tantalum and titanium in the composite coating, which would ensure the safety of the coating in vivo.

Highly flexible cross-linked cellulose nanofibril sponge-like aerogels with improved mechanical property and enhanced flame retardancy.

PubMed

Guo, Limin; Chen, Zhilin; Lyu, Shaoyi; Fu, Feng; Wang, Siqun

2018-01-01

Cellulose nanofibril (CNF) aerogel is highly flammable and its mechanical strength is very soft, which is unfavourable due to safety concerns and impractical when used as the thermal insulation material. In this work, we used N-methylol dimethylphosphonopropionamide (MDPA) and 1,2,3,4-butanetetracarboxylic acid (BTCA) as co-additives and then prepared lightweight flame resistant CNF sponge-like aerogels via an eco-friendly freeze-drying and post cross-linking method. The CNF/BTCA/MDPA aerogel exhibited a better flame retardant performance, outstanding self-extinguishing behaviour and significantly increased char residue (by as much as 268%) compared with the neat CNF aerogel. Meanwhile, the resilience of the aerogel samples improved significantly as the flexibility decreased slightly. Furthermore, the aerogel samples still exhibited excellent thermal insulating properties with thermal conductivity as low as 0.03258W/(m k). The combination of these characteristics makes the CNF-based aerogel a promising insulation candidate for thermal protective equipment (e.g., fire-protection clothing or advanced spacesuit elements) in the future. Copyright © 2017 Elsevier Ltd. All rights reserved.

Highlighting the Importance of Surface Grafting in Combination with a Layer-by-Layer Approach for Fabricating Advanced 3D Poly(l-lactide) Microsphere Scaffolds

PubMed Central

2016-01-01

A combined surface treatment (i.e., surface grafting and a layer-by-layer (LbL) approach) is presented to create advanced biomaterials, i.e., 3D poly(l-lactide) (PLLA) microsphere scaffolds, at room temperature. The grafted surface plays a crucial role in assembling polyelectrolyte multilayers (PEMs) onto the surface of the microspheres, thus improving the physicochemical properties of the 3D microsphere scaffolds. The grafted surface of the PLLA microspheres demonstrates much better PEM adsorption, improved surface coverage at low pH, and smoother surfaces at high pH compared with those of nongrafted surfaces of PLLA microspheres during the assembly of PEMs. They induce more swelling than nongrafted surfaces after the assembly of the PEMs and exhibit blue emission after functionalization of the microsphere surface with a fluorescent dye molecule. The 3D scaffolds functionalized with and without nanosheets not only exhibit good mechanical performance similar to the compressive modulus of cancellous bone but also exhibit the porosity required for cancellous bone regeneration. The magnetic nanoparticle-functionalized 3D scaffolds result in an electrical conductivity in the high range of semiconducting materials (i.e., 1–250 S cm–1). Thus, these 3D microsphere scaffolds fabricated by surface grafting and the LbL approach are promising candidates for bone tissue engineering. PMID:29503506

Improved electrochemical performances of binder-free CoMoO4 nanoplate arrays@Ni foam electrode using redox additive electrolyte

NASA Astrophysics Data System (ADS)

Veerasubramani, Ganesh Kumar; Krishnamoorthy, Karthikeyan; Kim, Sang Jae

2016-02-01

Herein, we are successfully prepared cobalt molybdate (CoMoO4) grown on nickel foam as a binder free electrode by hydrothermal approach for supercapacitors and improved their electrochemical performances using potassium ferricyanide (K3Fe(CN)6) as redox additive. The formation of CoMoO4 on Ni foam with high crystallinity is confirmed using XRD, Raman, and XPS measurements. The nanoplate arrays (NPAs) of CoMoO4 are uniformly grown on Ni foam which is confirmed by FE-SEM analysis. The prepared binder-free CoMoO4 NPAs achieved maximum areal capacity of 227 μAh cm-2 with KOH electrolyte at 2.5 mA cm-2. This achieved areal capacity is further improved about three times using the addition of K3Fe(CN)6 as redox additive. The increased electrochemical performances of CoMoO4 NPAs on Ni foam electrode via redox additive are discussed in detail and the mechanism has been explored. Moreover, the assembled CoMoO4 NPAs on Ni foam//activated carbon asymmetric supercapacitor device with an extended operating voltage window of 1.5 V exhibits an excellent performances such as high energy density and cyclic stability. The overall performances of binder-free CoMoO4 NPAs on Ni foam with redox additives suggesting their potential use as positive electrode material for high performance supercapacitors.

Intercomparison of the community multiscale air quality model and CALGRID using process analysis.

PubMed

O'Neill, Susan M; Lamb, Brian K

2005-08-01

This study was designed to examine the similarities and differences between two advanced photochemical air quality modeling systems: EPA Models-3/CMAQ and CALGRID/CALMET. Both modeling systems were applied to an ozone episode that occurred along the I-5 urban corridor in western Washington and Oregon during July 11-14, 1996. Both models employed the same modeling domain and used the same detailed gridded emission inventory. The CMAQ model was run using both the CB-IV and RADM2 chemical mechanisms, while CALGRID was used with the SAPRC-97 chemical mechanism. Outputfrom the Mesoscale Meteorological Model (MM5) employed with observational nudging was used in both models. The two modeling systems, representing three chemical mechanisms and two sets of meteorological inputs, were evaluated in terms of statistical performance measures for both 1- and 8-h average observed ozone concentrations. The results showed that the different versions of the systems were more similar than different, and all versions performed well in the Portland region and downwind of Seattle but performed poorly in the more rural region north of Seattle. Improving the meteorological input into the CALGRID/CALMET system with planetary boundary layer (PBL) parameters from the Models-3/CMAQ meteorology preprocessor (MCIP) improved the performance of the CALGRID/CALMET system. The 8-h ensemble case was often the best performer of all the cases indicating that the models perform better over longer analysis periods. The 1-h ensemble case, derived from all runs, was not necessarily an improvement over the five individual cases, but the standard deviation about the mean provided a measure of overall modeling uncertainty. Process analysis was applied to examine the contribution of the individual processes to the species conservation equation. The process analysis results indicated that the two modeling systems arrive at similar solutions by very different means. Transport rates are faster and exhibit greater fluctuations in the CMAQ cases than in the CALGRID cases, which lead to different placement of the urban ozone plumes. The CALGRID cases, which rely on the SAPRC97 chemical mechanism, exhibited a greater diurnal production/loss cycle of ozone concentrations per hour compared to either the RADM2 or CBIV chemical mechanisms in the CMAQ cases. These results demonstrate the need for specialized process field measurements to confirm whether we are modeling ozone with valid processes.

Can a virtual reality surgical simulation training provide a self-driven and mentor-free skills learning? Investigation of the practical influence of the performance metrics from the virtual reality robotic surgery simulator on the skill learning and associated cognitive workloads.

PubMed

Lee, Gyusung I; Lee, Mija R

2018-01-01

While it is often claimed that virtual reality (VR) training system can offer self-directed and mentor-free skill learning using the system's performance metrics (PM), no studies have yet provided evidence-based confirmation. This experimental study investigated what extent to which trainees achieved their self-learning with a current VR simulator and whether additional mentoring improved skill learning, skill transfer and cognitive workloads in robotic surgery simulation training. Thirty-two surgical trainees were randomly assigned to either the Control-Group (CG) or Experiment-Group (EG). While the CG participants reviewed the PM at their discretion, the EG participants had explanations about PM and instructions on how to improve scores. Each subject completed a 5-week training using four simulation tasks. Pre- and post-training data were collected using both a simulator and robot. Peri-training data were collected after each session. Skill learning, time spent on PM (TPM), and cognitive workloads were compared between groups. After the simulation training, CG showed substantially lower simulation task scores (82.9 ± 6.0) compared with EG (93.2 ± 4.8). Both groups demonstrated improved physical model tasks performance with the actual robot, but the EG had a greater improvement in two tasks. The EG exhibited lower global mental workload/distress, higher engagement, and a better understanding regarding using PM to improve performance. The EG's TPM was initially long but substantially shortened as the group became familiar with PM. Our study demonstrated that the current VR simulator offered limited self-skill learning and additional mentoring still played an important role in improving the robotic surgery simulation training.

An Advanced TALSPEAK Concept for Separating Minor Actinides. Part 1. Process Optimization and Flowsheet Development

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lumetta, Gregg J.; Levitskaia, Tatiana G.; Wilden, Andreas

A system is being developed to separate trivalent actinides from lanthanide fission product elements that uses 2-ethylhexylphosphonic acid mono-2-ethylhexyl ester to extract the lanthanide ions into an organic phase, while the actinide ions are held in the citrate-buffered aqueous phase by complexation to N-(2-hydroxyethyl)ethylenediamine-N,N',N'-triacetic acid (HEDTA). Earlier investigations of this system using a 2-cm centrifugal contactor revealed that the relatively slow extraction of Sm3+, Eu3+, and Gd3+ resulted in low separation factors from Am3+. In the work reported here, adjustments to the aqueous phase chemistry were made to improve the extraction rates. The results suggest that increasing the concentration ofmore » the citric acid buffer from 0.2 to 0.6 mol/L, and lowering the pH from 3.1 to 2.6, significantly improved lanthanide extraction rates resulting in an actinide/lanthanide separation system suitable for deployment in centrifugal contactors. Experiments performed to evaluate whether the lanthanide extraction rates can be improved by replacing aqueous HEDTA with nitrilotriacetic acid (NTA) exhibited promising results. However, NTA exhibited an unsatisfactorily high distribution value for Am3+ under the extraction conditions examined.« less

Soft but Powerful Artificial Muscles Based on 3D Graphene-CNT-Ni Heteronanostructures.

PubMed

Kim, Jaehwan; Bae, Seok-Hu; Kotal, Moumita; Stalbaum, Tyler; Kim, Kwang J; Oh, Il-Kwon

2017-08-01

Bioinspired soft ionic actuators, which exhibit large strain and high durability under low input voltages, are regarded as prospective candidates for future soft electronics. However, due to the intrinsic drawback of weak blocking force, the feasible applications of soft ionic actuators are limited until now. An electroactive artificial muscle electro-chemomechanically reinforced with 3D graphene-carbon nanotube-nickel heteronanostructures (G-CNT-Ni) to improve blocking force and bending deformation of the ionic actuators is demonstrated. The G-CNT-Ni heteronanostructure, which provides an electrically conductive 3D network and sufficient contact area with mobile ions in the polymer electrolyte, is embedded as a nanofiller in both ionic polymer and conductive electrodes of the ionic actuators. An ionic exchangeable composite membrane consisting of Nafion, G-CNT-Ni and ionic liquid (IL) shows improved tensile modulus and strength of up to 166% and 98%, respectively, and increased ionic conductivity of 0.254 S m -1 . The ionic actuator exhibits enhanced actuation performances including three times larger bending deformation, 2.37 times higher blocking force, and 4 h durability. The electroactive artificial muscle electro-chemomechanically reinforced with 3D G-CNT-Ni heteronanostructures offers improvements over current soft ionic actuator technologies and can advance the practical engineering applications. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Cholinesterase Inhibitors Improve Both Memory and Complex Learning in Aged Beagle Dogs

PubMed Central

Araujo, Joseph A.; Greig, Nigel H.; Ingram, Donald K.; Sandin, Johan; de Rivera, Christina; Milgram, Norton W.

2016-01-01

Similar to patients with Alzheimer’s disease (AD), dogs exhibit age-dependent cognitive decline, amyloid-β (Aβ) pathology, and evidence of cholinergic hypofunction. The present study sought to further investigate the role of cholinergic hypofunction in the canine model by examining the effect of the cholinesterase inhibitors phenserine and donepezil on performance of two tasks, a delayed non-matching-to-position task (DNMP) designed to assess working memory, and an oddity discrimination learning task designed to assess complex learning, in aged dogs. Phenserine (0.5 mg/kg; PO) significantly improved performance on the DNMP at the longest delay compared to wash-out and partially attenuated scopolamine-induced deficits (15 μg/kg; SC). Phenserine also improved learning on a difficult version of an oddity discrimination task compared to placebo, but had no effect on an easier version. We also examined the effects of three doses of donepezil (0.75, 1.5, and 6 mg/kg; PO) on performance of the DNMP. Similar to the results with phenserine, 1.5 mg/kg of donepezil improved performance at the longest delay compared to baseline and wash-out, indicative of memory enhancement. These results further extend the findings of cholinergic hypofunction in aged dogs and provide pharmacological validation of the canine model with a cholinesterase inhibitor approved for use in AD. Collectively, these studies support utilizing the aged dog in future screening of therapeutics for AD, as well as for investigating the links among cholinergic function, Aβ pathology, and cognitive decline. PMID:21593569

High-Performance High-Loading Lithium-Sulfur Batteries by Low Temperature Atomic Layer Deposition of Aluminum Oxide on Nanophase S Cathodes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Meng, Xiangbo; Liu, Yuzi; Cao, Yanqiang

2017-05-18

This study examines the effects of nanophase S and surface coatings via atomic layer deposition (ALD) on high-loading sulfur cathodes for developing high-performance and high-energy lithium-sulfur (Li-S) batteries. It is first verified that ball milling is an effective and facile route for nanoengineering microsized S powders and the resultant nanoscale S particles exhibit better performance. Using these ball milled nanoscale S cathodes, it is found that ALD Al2O3 performed at 50 degrees C yields deposits that evolve with ALD cycles from dispersed nanoparticles, to porous, connected films, and finally to dense and continuous films. Moreover, this low temperature ALD processmore » suppresses S loss by sublimation. The ALD Al2O3 greatly improves sulfur cathode sustainable capacity and Coulombic efficiency. This study postulates two different mechanisms underlying the effects of ALD Al2O3 surface coatings depending on their morphology. ALD Al2O3 nanoparticles dispersed on the sulfur surface mainly function to adsorb polysulfides, thereby inhibiting S shuttling and improving sustainable capacity and Coulombic efficiency. By contrast, ALD Al2O3 films behave as a physical barrier to prevent polysulfides from contacting the liquid electrolyte and dissolving. The dispersed Al2O3 nanoparticles improve both sustainable capacity and Coulombic efficiency while the closed Al2O3 films improve Coulombic efficiency while decreasing the capacity« less

Fabrication of β-CoV3O8 nanorods embedded in graphene sheets and their application for electrochemical charge storage electrode.

PubMed

Jeong, Gyoung Hwa; Lee, Ilbok; Lee, Donghyun; Lee, Hea-Min; Baek, Seungmin; Kwon, O-Pil; Kumta, Prashant N; Yoon, Songhun; Kim, Sang-Wook

2018-05-11

The fabrication of β-CoV 3 O 8 nanorods embedded in graphene sheets and their application as electrochemical charge storage electrodes is reported. From the surfactant treatment of raw graphite, graphene was directly prepared and its nanocomposite with β-CoV 3 O 8 nanorods distributed between graphene layers (β-CoV 3 O 8 -G) was synthesized by a hydrothermal method. When applied as an anode in lithium-ion batteries, the β-CoV 3 O 8 -G anode exhibits greatly improved charge and discharge capacities of 790 and 627 mAh · g -1 , respectively, with unexpectedly high initial efficiency of 82%. The observed discharge capacity reflected that at least 3.7 mol of Li + is selectively accumulated within the β-CoV 3 O 8 phase (Li x CoV 3 O 8 , x > 3.7), indicative of significantly improved Li + uptake when compared with aggregated β-CoV 3 O 8 nanorods. Moreover, very distinct peak plateaus and greatly advanced cycling performance are observed, showing more improved Li + storage within the β-CoV 3 O 8 phase. As a supercapacitor electrode, moreover, our composite electrode exhibits very high peak pseudocapacitances of 2.71 F · cm -2 and 433.65 F · g -1 in the β-CoV 3 O 8 phase with extremely stable cycling performance. This remarkably enhanced performance in the individual electrochemical charge storage electrodes is attributed to the novel phase formation of β-CoV 3 O 8 and its optimized nanocomposite structure with graphene, which yield fast electrical conduction through graphene, easy accessibility of ions through the open multilayer nanosheet structure, and a relaxation space between the β-CoV 3 O 8 -G.

Tracking the quality of care for sick children using lot quality assurance sampling: targeting improvements of health services in Jigawa, Nigeria.

PubMed

Oladele, Edward Adekola; Ormond, Louise; Adeyemi, Olusegun; Patrick, David; Okoh, Festus; Oresanya, Olusola Bukola; Valadez, Joseph J

2012-01-01

In Nigeria, 30% of child deaths are due to malaria. The National Malaria Control Program of Nigeria (NMCP) during 2009 initiated a program to improve the quality of paediatric malaria services delivered in health facilities (HF). This study reports a rapid approach used to assess the existing quality of services in Jigawa state at decentralised levels of the health system. NMCP selected Lot Quality Assurance Sampling (LQAS) to identify the variation in HF service quality among Senatorial Districts (SD). LQAS was selected because it was affordable and could be used by local health workers (HW) in a population-based survey. NMCP applied a 2-stage LQAS using a structured Rapid Health Facility Assessment (R-HFA) tool to identify high and low performing SD for specified indicators. LQAS identified variations in HF performance (n = 21) and enabled resources to be targeted to address priorities. All SD exhibited deficient essential services, supplies and equipment. Only 9.7% of HF had Artemisinin-based Combination Therapies and other first-line treatments for childhood illnesses. No SD and few HF exhibited adequate HW performance for the assessment, treatment or counselling of sick children. Using the IMCI algorithm, 17.5% of HW assessed the child's vaccination status, 46.8% assessed nutritional status, and 65.1% assessed children for dehydration. Only 5.1% of HW treatments were appropriate for the assessment. Exit interviews revealed that 5.1% of caregivers knew their children's illness, and only 19.9% could accurately describe how to administer the prescribed drug. This R-HFA, using LQAS principles, is a rapid, simple tool for assessing malaria services and can be used at scale. It identified technical deficiencies that could be corrected by improved continuing medical education, targeted supervision, and recurrent R-HFA assessments of the quality of services.

Tracking the Quality of Care for Sick Children Using Lot Quality Assurance Sampling: Targeting Improvements of Health Services in Jigawa, Nigeria

PubMed Central

Oladele, Edward Adekola; Ormond, Louise; Adeyemi, Olusegun; Patrick, David; Okoh, Festus; Oresanya, Olusola Bukola; Valadez, Joseph J.

2012-01-01

Background In Nigeria, 30% of child deaths are due to malaria. The National Malaria Control Program of Nigeria (NMCP) during 2009 initiated a program to improve the quality of paediatric malaria services delivered in health facilities (HF). This study reports a rapid approach used to assess the existing quality of services in Jigawa state at decentralised levels of the health system. Methods NMCP selected Lot Quality Assurance Sampling (LQAS) to identify the variation in HF service quality among Senatorial Districts (SD). LQAS was selected because it was affordable and could be used by local health workers (HW) in a population-based survey. NMCP applied a 2-stage LQAS using a structured Rapid Health Facility Assessment (R-HFA) tool to identify high and low performing SD for specified indicators. Findings LQAS identified variations in HF performance (n = 21) and enabled resources to be targeted to address priorities. All SD exhibited deficient essential services, supplies and equipment. Only 9.7% of HF had Artemisinin-based Combination Therapies and other first-line treatments for childhood illnesses. No SD and few HF exhibited adequate HW performance for the assessment, treatment or counselling of sick children. Using the IMCI algorithm, 17.5% of HW assessed the child’s vaccination status, 46.8% assessed nutritional status, and 65.1% assessed children for dehydration. Only 5.1% of HW treatments were appropriate for the assessment. Exit interviews revealed that 5.1% of caregivers knew their children’s illness, and only 19.9% could accurately describe how to administer the prescribed drug. Conclusion This R-HFA, using LQAS principles, is a rapid, simple tool for assessing malaria services and can be used at scale. It identified technical deficiencies that could be corrected by improved continuing medical education, targeted supervision, and recurrent R-HFA assessments of the quality of services. PMID:23028519

Improving Dielectric Properties of PVDF Composites by Employing Surface Modified Strong Polarized BaTiO₃ Particles Derived by Molten Salt Method.

PubMed

Fu, Jing; Hou, Yudong; Zheng, Mupeng; Wei, Qiaoyi; Zhu, Mankang; Yan, Hui

2015-11-11

BaTiO3/polyvinylidene fluoride (BT/PVDF) is the extensive reported composite material for application in modern electric devices. However, there still exists some obstacles prohibiting the further improvement of dielectric performance, such as poor interfacial compatibility and low dielectric constant. Therefore, in depth study of the size dependent polarization and surface modification of BT particle is of technological importance in developing high performance BT/PVDF composites. Here, a facile molten-salt synthetic method has been applied to prepare different grain sized BT particles through tailoring the calcination temperature. The size dependent spontaneous polarizationof BT particle was thoroughly investigated by theoretical calculation based on powder X-ray diffraction Rietveld refinement data. The results revealed that 600 nm sized BT particles possess the strong polarization, ascribing to the ferroelectric size effect. Furthermore, the surface of optimal BT particles has been modified by water-soluble polyvinylprrolidone (PVP) agent, and the coated particles exhibited fine core-shell structure and homogeneous dispersion in the PVDF matrix. The dielectric constant of the resulted composites increased significantly, especially, the prepared composite with 40 vol % BT loading exhibited the largest dielectric constant (65, 25 °C, 1 kHz) compared with the literature values of BT/PVDF at the same concentration of filler. Moreover, the energy storage density of the composites with tailored structure was largely enhanced at the low electric field, showing promising application as dielectric material in energy storage device. Our work suggested that introduction of strong polarized ferroelectric particles with optimal size and construction of core-shell structured coated fillers by PVP in the PVDF matrix are efficacious in improving dielectric performance of composites. The demonstrated approach can also be applied to the design and preparation of other polymers-based nanocomposites filled with ferroelectric particles to achieve desirable dielectric properties.

Process-level improvements in CMIP5 models and their impact on tropical variability, the Southern Ocean, and monsoons

NASA Astrophysics Data System (ADS)

Lauer, Axel; Jones, Colin; Eyring, Veronika; Evaldsson, Martin; Hagemann, Stefan; Mäkelä, Jarmo; Martin, Gill; Roehrig, Romain; Wang, Shiyu

2018-01-01

The performance of updated versions of the four earth system models (ESMs) CNRM, EC-Earth, HadGEM, and MPI-ESM is assessed in comparison to their predecessor versions used in Phase 5 of the Coupled Model Intercomparison Project. The Earth System Model Evaluation Tool (ESMValTool) is applied to evaluate selected climate phenomena in the models against observations. This is the first systematic application of the ESMValTool to assess and document the progress made during an extensive model development and improvement project. This study focuses on the South Asian monsoon (SAM) and the West African monsoon (WAM), the coupled equatorial climate, and Southern Ocean clouds and radiation, which are known to exhibit systematic biases in present-day ESMs. The analysis shows that the tropical precipitation in three out of four models is clearly improved. Two of three updated coupled models show an improved representation of tropical sea surface temperatures with one coupled model not exhibiting a double Intertropical Convergence Zone (ITCZ). Simulated cloud amounts and cloud-radiation interactions are improved over the Southern Ocean. Improvements are also seen in the simulation of the SAM and WAM, although systematic biases remain in regional details and the timing of monsoon rainfall. Analysis of simulations with EC-Earth at different horizontal resolutions from T159 up to T1279 shows that the synoptic-scale variability in precipitation over the SAM and WAM regions improves with higher model resolution. The results suggest that the reasonably good agreement of modeled and observed mean WAM and SAM rainfall in lower-resolution models may be a result of unrealistic intensity distributions.

The effects of JWB1-84-1 on memory-related task performance by amyloid Abeta transgenic mice and by young and aged monkeys.

PubMed

Sood, Ajay; Warren Beach, J; Webster, Scott J; Terry, Alvin V; Buccafusco, Jerry J

2007-10-01

JWB1-84-1 is one of 50 tertiary amine analogs of choline synthesized with expectation that they would be high potency compounds for cytoprotection. As one of the more potent analogs in this regard, JWB1-84-1, a piperazine derivative, was selected for testing as a cognition-enhancing agent. The compound was evaluated for efficacy in Alzheimer's disease transgenic mice (B6C3-Tg(APPswe, PSEN1dE9)85Dbo/J). A separate cohort of mice (AD Tg) were first subjected to a behavioral test battery in which the transgenic strain was compared with the wild-type strain. AD Tg mice were shown to exhibit specific deficits in the acquisition of a working memory (5-trial/session radial arm water maze, RAWM) task at a time when the animals exhibited maximal cerebral amyloid burden. JWB1-84-1 produced a dose-dependent decrease in the number of errors made by well trained AD-Tg mice the RAWM task that was maximal after the 20 microg/kg dose. Aged macaques (20-32 y) were trained to proficiency in their performance of a computer-assisted delayed matching-to-sample task. Vehicle (normal saline) or JWB1-84-1 (5-150 microg/kg, i.m.) was administered 10 min before the initiating of testing. On average, JWB1-84-1 treatment significantly improved task accuracy after all but the lowest dose. The maximal degree of improvement was attained after animals received the 100 microg/kg dose. The drug's effects were restricted primarily to Medium and Long delay trials - the most difficult portions of the task, which were improved by up to 18% above control. In young macaques JWB1-84-1 treatment also significantly reversed the decrements in task accuracy associated with the random presentation of a task distractor. Thus JWB1-84-1exhibits the potential for treating the cognitive symptoms associated with neurodegenerative diseases and attention deficit disorders. Its cytoprotective action might also work to slow the progression of Alzheimer's disease.

Meta-analysis of the effects of microclimate cooling systems on human performance under thermal stressful environments: potential applications to occupational workers.

PubMed

Chan, Albert P C; Song, Wenfang; Yang, Yang

2015-01-01

This study aims to determine the appropriate microclimate cooling systems (MCSs) to reduce heat stress and improve human performance of occupational workers and their practicality in the occupational field. Meta-analysis was employed to summarize, analyze, and compare the effects of various MCSs on human performance with corresponding physiological and psychological responses, thereby providing solid suggestions for selecting suitable MCSs for occupational workers. Wearing MCSs significantly attenuated the increases in core temperature (-0.34 °C/h) and sweating rate (-0.30 L/h), and significantly improved human performance (+29.9%, effect size [EFS] = 1.1) compared with no cooling condition (CON). Cold air-cooled garments (ACG-Cs; +106.2%, EFS = 2.32) exhibited greater effects on improving human performance among various microclimate cooling garments (MCGs), followed by liquid cooling garments (LCGs; +68.1%, EFS = 1.86) and hybrid cooling garment combining air and liquid cooling (HBCG-AL; +59.1%, EFS=3.38), natural air-cooled garments (ACG-Ns; +39.9%, EFS = 1.12), and phase change material cooling garments (PCMCGs; +19.5%, EFS = 1.2). Performance improvement was observed to be positively and linearly correlated to the differences of core temperature increase rate (r = 0.65, p < 0.01) and sweating rate (r = 0.80, p < 0.001) between MCSs and CON. Considering their application in industrial settings, ACG-Cs, LCGs, and HBCG-AL are practical for work, in which workers do not move frequently, whereas ACG-Ns and PCMCGs are more applicable for the majority of occupational workers. Further enhancement of the cooling efficiency of these two cooling strategies should be initiated. Copyright © 2015 Elsevier Ltd. All rights reserved.

Performance gains by using heated natural-gas fuel in an annular turbojet combustor

NASA Technical Reports Server (NTRS)

Marchionna, N. R.

1973-01-01

A full-scale annular turbojet combustor was tested with natural gas fuel heated from ambient temperature to 800 K (980 F). In all tests, heating the fuel improved combustion efficiency. Two sets of gaseous fuel nozzles were tested. Combustion instabilities occurred with one set of nozzles at two conditions: one where the efficiency approached 100 percent with the heated fuel; the other where the efficiency was very poor with the unheated fuel. The second set of nozzles exhibited no combustion instability. Altitude relight tests with the second set showed that relight was improved and was achievable at essentially the same condition as blowout when the fuel temperature was 800 K (980 F).

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, Lingda; Hayes, Ari; Song, Shuaiwen

Modern GPUs employ cache to improve memory system efficiency. However, large amount of cache space is underutilized due to irregular memory accesses and poor spatial locality which exhibited commonly in GPU applications. Our experiments show that using smaller cache lines could improve cache space utilization, but it also frequently suffers from significant performance loss by introducing large amount of extra cache requests. In this work, we propose a novel cache design named tag-split cache (TSC) that enables fine-grained cache storage to address the problem of cache space underutilization while keeping memory request number unchanged. TSC divides tag into two partsmore » to reduce storage overhead, and it supports multiple cache line replacement in one cycle.« less

Summary of International Exhibition and Congress (3rd): BIOTECHNICA 󈨛 Hannover Held in Hannover (Germany, F.R.) on 22-24 September 1987

DTIC Science & Technology

1988-01-21

nucleic acids which occur in DNA and seem to play an e Improved theoretical analysis of the important role in determining gene reg’- fntra- and...developed two retroviral vectors, based on the murine new peptide-based animal vaccines which myeloproliferative sarcoma virus (MPSV), are currertly...Structure tides are part of a precursor molecule elucidation is performed by gas-phase composed of 126 amino acids. From a pre- amino acid sequence analysis

Development of a large inert gas ion thruster

NASA Technical Reports Server (NTRS)

Steiner, G.

1982-01-01

A 30 cm inert gas electrostatic ion thruster has been developed, exhibiting excellent performance. In the development, the effective anode area was reduced by altering the magnetic field geometry to improve plasma containment, consistent with operational stability. The propellant introduction scheme has the effect of 'folding' the discharge chamber without the increased wall loss penalty associated with a longer chamber. These features contribute to a low discharge cost (eV/ion) versus mass utilization characteristic which remains relatively flat even to high mass utilizations.

Graphene-based battery electrodes having continuous flow paths

DOEpatents

Zhang, Jiguang; Xiao, Jie; Liu, Jun; Xu, Wu; Li, Xiaolin; Wang, Deyu

2014-05-24

Some batteries can exhibit greatly improved performance by utilizing electrodes having randomly arranged graphene nanosheets forming a network of channels defining continuous flow paths through the electrode. The network of channels can provide a diffusion pathway for the liquid electrolyte and/or for reactant gases. Metal-air batteries can benefit from such electrodes. In particular Li-air batteries show extremely high capacities, wherein the network of channels allow oxygen to diffuse through the electrode and mesopores in the electrode can store discharge products.

Iron-based alloys with corrosion resistance to oxygen-sulfur mixed gases

DOEpatents

Natesan, K.

1992-11-17

An iron-based alloy with improved performance with exposure to oxygen-sulfur mixed gases with the alloy containing about 9--30 wt. % Cr and a small amount of Nb and/or Zr implanted on the surface of the alloy to diffuse a depth into the surface portion, with the alloy exhibiting corrosion resistance to the corrosive gases without bulk addition of Nb and/or Zr and without heat treatment at temperatures of 1000--1100 C. 7 figs.

Iron-based alloys with corrosion resistance to oxygen-sulfur mixed gases

DOEpatents

Natesan, Krishnamurti

1992-01-01

An iron-based alloy with improved performance with exposure to oxygen-sulfur mixed gases with the alloy containing about 9-30 wt. % Cr and a small amount of Nb and/or Zr implanted on the surface of the alloy to diffuse a depth into the surface portion, with the alloy exhibiting corrosion resistance to the corrosive gases without bulk addition of Nb and/or Zr and without heat treatment at temperatures of 1000.degree.-1100.degree. C.

Carbon nanotube-incorporated collagen hydrogels improve cell alignment and the performance of cardiac constructs

PubMed Central

Sun, Hongyu; Zhou, Jing; Huang, Zhu; Qu, Linlin; Lin, Ning; Liang, Chengxiao; Dai, Ruiwu; Tang, Lijun; Tian, Fuzhou

2017-01-01

Carbon nanotubes (CNTs) provide an essential 2-D microenvironment for cardiomyocyte growth and function. However, it remains to be elucidated whether CNT nanostructures can promote cell–cell integrity and facilitate the formation of functional tissues in 3-D hydrogels. Here, single-walled CNTs were incorporated into collagen hydrogels to fabricate (CNT/Col) hydrogels, which improved mechanical and electrical properties. The incorporation of CNTs (up to 1 wt%) exhibited no toxicity to cardiomyocytes and enhanced cell adhesion and elongation. Through the use of immunohistochemical staining, transmission electron microscopy, and intracellular calcium-transient measurement, the incorporation of CNTs was found to improve cell alignment and assembly remarkably, which led to the formation of engineered cardiac tissues with stronger contraction potential. Importantly, cardiac tissues based on CNT/Col hydrogels were noted to have better functionality. Collectively, the incorporation of CNTs into the Col hydrogels improved cell alignment and the performance of cardiac constructs. Our study suggests that CNT/Col hydrogels offer a promising tissue scaffold for cardiac constructs, and might serve as injectable biomaterials to deliver cell or drug molecules for cardiac regeneration following myocardial infarction in the near future. PMID:28450785

Evaluation and comparison of an adaptive method technique for improved performance of linear Fresnel secondary designs

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hack, Madeline; Zhu, Guangdong; Wendelin, Timothy J.

As a line-focus concentrating solar power (CSP) technology, linear Fresnel collectors have the potential to become a low-cost solution for electricity production and a variety of thermal energy applications. However, this technology often suffers from relatively low performance. A secondary reflector is a key component used to improve optical performance of a linear Fresnel collector. The shape of a secondary reflector is particularly critical in determining solar power captured by the absorber tube(s), and thus, the collector's optical performance. However, to the authors' knowledge, no well-established process existed to derive the optimal secondary shape prior to the development of amore » new adaptive method to optimize the secondary reflector shape. The new adaptive method does not assume any pre-defined analytical form; rather, it constitutes an optimum shape through an adaptive process by maximizing the energy collection onto the absorber tube. In this paper, the adaptive method is compared with popular secondary-reflector designs with respect to a collector's optical performance under various scenarios. For the first time, a comprehensive, in-depth comparison was conducted on all popular secondary designs for CSP applications. In conclusion, it is shown that the adaptive design exhibits the best optical performance.« less

Evaluation and comparison of an adaptive method technique for improved performance of linear Fresnel secondary designs

DOE PAGES

Hack, Madeline; Zhu, Guangdong; Wendelin, Timothy J.

2017-09-13

As a line-focus concentrating solar power (CSP) technology, linear Fresnel collectors have the potential to become a low-cost solution for electricity production and a variety of thermal energy applications. However, this technology often suffers from relatively low performance. A secondary reflector is a key component used to improve optical performance of a linear Fresnel collector. The shape of a secondary reflector is particularly critical in determining solar power captured by the absorber tube(s), and thus, the collector's optical performance. However, to the authors' knowledge, no well-established process existed to derive the optimal secondary shape prior to the development of amore » new adaptive method to optimize the secondary reflector shape. The new adaptive method does not assume any pre-defined analytical form; rather, it constitutes an optimum shape through an adaptive process by maximizing the energy collection onto the absorber tube. In this paper, the adaptive method is compared with popular secondary-reflector designs with respect to a collector's optical performance under various scenarios. For the first time, a comprehensive, in-depth comparison was conducted on all popular secondary designs for CSP applications. In conclusion, it is shown that the adaptive design exhibits the best optical performance.« less

High performance Sb2S3/carbon composite with tailored artificial interface as an anode material for sodium ion batteries

NASA Astrophysics Data System (ADS)

Choi, Jeong-Hee; Ha, Chung-Wan; Choi, Hae-Young; Shin, Heon-Cheol; Lee, Sang-Min

2017-11-01

The electrochemical comparison between Sb2S3 and its composite with carbon (Sb2S3/C) involved by sodium ion carrier are explained by enhanced kinetics, particularly with respect to improved interfacial conductivity by surface modulation by carbon. Sb2S3 and Sb2S3/C are synthesized by a high energy mechanical milling process. The successful synthesis of these materials is confirmed with X-ray diffraction (XRD), scanning electron microscopy, and transmission electron microscopy (TEM). As an anode material for sodium ion batteries, Sb2S3 exhibits an initial sodiation/desodiation capacity of 1,021/523 mAh g-1 whereas the Sb2S3/C composite exhibits a higher reversible capacity (642 mAh g-1). Furthermore, the cycle performance and rate capability of the Sb2S3/C composite are estimated to be much better than those of Sb and Sb2S3. Electrochemical impedance spectroscopy analysis shows that the Sb2S3/C composite exhibited charge transfer resistance and surface film resistance much lower than Sb2S3. X-ray photoelectron spectroscopy analyses of both electrodes demonstrate that NaF layer on Sb2S3/C composite electrode leads to the better electrochemical performances. In order to clarify the electrochemical reaction mechanism, ex-situ XRD based on differential capacity plots and ex-situ HR-TEM analyses of the Sb2S3/C composite electrode are carried out and its reaction mechanism was established.

Phase-Engineered Type-II Multimetal-Selenide Heterostructures toward Low-Power Consumption, Flexible, Transparent, and Wide-Spectrum Photoresponse Photodetectors.

PubMed

Chen, Yu-Ze; Wang, Sheng-Wen; Su, Teng-Yu; Lee, Shao-Hsin; Chen, Chia-Wei; Yang, Chen-Hua; Wang, Kuangye; Kuo, Hao-Chung; Chueh, Yu-Lun

2018-05-01

Phase-engineered type-II metal-selenide heterostructures are demonstrated by directly selenizing indium-tin oxide to form multimetal selenides in a single step. The utilization of a plasma system to assist the selenization facilitates a low-temperature process, which results in large-area films with high uniformity. Compared to single-metal-selenide-based photodetectors, the multimetal-selenide photodetectors exhibit obviously improved performance, which can be attributed to the Schottky contact at the interface for tuning the carrier transport, as well as the type-II heterostructure that is beneficial for the separation of the electron-hole pairs. The multimetal-selenide photodetectors exhibit a response to light over a broad spectrum from UV to visible light with a high responsivity of 0.8 A W -1 and an on/off current ratio of up to 10 2 . Interestingly, all-transparent photodetectors are successfully produced in this work. Moreover, the possibility of fabricating devices on flexible substrates is also demonstrated with sustainable performance, high strain tolerance, and high durability during bending tests. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

An efficient method to prepare magnetic hydroxyapatite-functionalized multi-walled carbon nanotubes nanocomposite for bone defects.

PubMed

Afroze, J D; Abden, M J; Islam, M A

2018-05-01

Hydroxyapatite-functionalized multi-walled carbon nanotube (HA-fMWCNT) magnetic nanocomposite was successfully prepared using a novel slurry-compounding method. The prepared HA-fMWCNT nanocomposite with the addition of small amount (0.5 wt%) of fMWCNT exhibited much greater improvement in mechanical properties due to strong interfacial adhesion between acid-treated MWCNTs fillers and HA matrix, thus efficient stress transfer to nanotubes from the matrix. The nanocomposite exhibited excellent haemocompatibility. Fractographic analysis was performed in order to understand the fracture behavior and toughening mechanisms. The fracture mechanisms and micro-deformation were examined by studying the microstructure of arrested crack tips using field emission scanning electron microscopy (FESEM). The origination and formation of micro-cracks are the dominant fracture mechanisms and micro-deformation in the HA-fMWCNTs nanocomposite. The developed new method enables to the fabrication of magnetic HA-fMWCNTs nanocomposite with superior mechanical performance may be potential for application as high load-bearing bone implants in the biomedical field. Copyright © 2018 Elsevier B.V. All rights reserved.

Perovskite-nitrogen-doped carbon nanotube composite as bifunctional catalysts for rechargeable lithium-air batteries.

PubMed

Park, Hey Woong; Lee, Dong Un; Park, Moon Gyu; Ahmed, Raihan; Seo, Min Ho; Nazar, Linda F; Chen, Zhongwei

2015-03-01

Developing an effective bifunctional catalyst is a significant issue, as rechargeable metal-air batteries are very attractive for future energy systems. In this study, a facile one-pot process is introduced to prepare an advanced bifunctional catalyst (op-LN) incorporating nitrogen-doped carbon nanotubes (NCNTs) into perovskite La0.5 Sr0.5 Co0.8 Fe0.2 O3 nanoparticles (LSCF-NPs). Confirmed by half-cell testing, op-LN exhibits synergistic effects of LSCF-NP and NCNT with excellent bifunctionality for both the oxygen reduction reaction and the oxygen evolution reaction. Furthermore, op-LN exhibits comparable performances in these reactions to Pt/C and Ir/C, respectively, which highlights its potential for use as a commercially viable bifunctional catalyst. Moreover, the results obtained by testing op-LN in a practical Li-air battery demonstrate improved and complementary charge/discharge performance compared to those of LSCF-NP and NCNT, and this confirms that simply prepared op-LN is a promising candidate as a highly effective bifunctional catalyst for rechargeable metal-air batteries. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

High performance asymmetric supercapacitor based on molybdenum disulphide/graphene foam and activated carbon from expanded graphite.

PubMed

Masikhwa, Tshifhiwa M; Madito, Moshawe J; Bello, Abdulhakeem; Dangbegnon, Julien K; Manyala, Ncholu

2017-02-15

Molybdenum disulphide which has a graphene-like single layer structure has excellent mechanical and electrical properties and unique morphology, which might be used with graphene foam as composite in supercapacitor applications. In this work, Molybdenum disulphide (MoS 2 )/graphene foam (GF) composites with different graphene foam loading were synthesized by the hydrothermal process to improve on specific capacitance of the composites. Asymmetric supercapacitor device was fabricated using the best performing MoS 2 /GF composite and activated carbon derived from expanded graphite (AEG) as positive and negative electrodes, respectively, in 6M KOH electrolyte. The asymmetric MoS 2 /GF//AEG device exhibited a maximum specific capacitance of 59Fg -1 at a current density of 1Ag -1 with maximum energy and power densities of 16Whkg -1 and 758Wkg -1 , respectively. The supercapacitor also exhibited a good cyclic stability with 95% capacitance retention over 2000 constant charge-discharge cycles. The results obtained demonstrate the potential of MoS 2 /GF//AEG as a promising material for electrochemical energy storage application. Copyright © 2016 Elsevier Inc. All rights reserved.

Fabrication and electrical properties of low temperature-processed thin-film-transistors with chemical-bath deposited ZnO layer.

PubMed

Ahn, Joo-Seob; Kwon, Ji-Hye; Yang, Heesun

2013-06-01

ZnO film was grown on ZnO quantum dot seed layer-coated substrate by a low-temperature chemical bath deposition, where sodium citrate serves as a complexing agent for Zn2+ ion. The ZnO film deposited under the optimal condition exhibited a highly uniform surface morphology with a thickness of approimately 30 nm. For the fabrication of thin-film-transistor with a bottom-gate structure, ZnO film was chemically deposited on the transparent substrate of a seed layer-coated SiN(x)/ITO (indium tin oxide)/glass. As-deposited ZnO channel was baked at low temperatures of 60-200 degrees C to investigate the effect of baking temperature on electrical performances. Compared to the device with 60 degrees C-baked ZnO channel, the TFT performances of one with 200 degrees C-baked channel were substantially improved, exhibiting an on-off current ratio of 3.6 x 10(6) and a saturated field-effect mobility of 0.27 cm2/V x s.

Long-Term Soft Denture Lining Materials

PubMed Central

Chladek, Grzegorz; Żmudzki, Jarosław; Kasperski, Jacek

2014-01-01

Long-term soft denture lining (LTSDL) materials are used to alleviate the trauma associated with wearing complete dentures. Despite their established clinical efficacy, the use of LTSDLs has been limited due to the unfavorable effects of the oral environment on some of their mechanical and performance characteristics. The unresolved issue of LTSDL colonization by Candida albicans is particularly problematic. Silicone-based LTSDL (SLTSDL) materials, which are characterized by more stable hardness, sorption and solubility than acrylic-based LTSDLs (ALTSDLs), are currently the most commonly used LTSDLs. However, SLTSDLs are more prone to debonding from the denture base. Moreover, due to their limitations, the available methods for determining bond strength do not fully reflect the actual stability of these materials under clinical conditions. SLTSDL materials exhibit favorable viscoelastic properties compared with ALTSDLs. Furthermore, all of the lining materials exhibit an aging solution-specific tendency toward discoloration, and the available cleansers are not fully effective and can alter the mechanical properties of LTSDLs. Future studies are needed to improve the microbiological resistance of LTSDLs, as well as some of their performance characteristics. PMID:28788163

Citicoline Treatment Improves Measures of Impulsivity and Task Performance in Chronic Marijuana Smokers: A Pilot BOLD fMRI Study

PubMed Central

Gruber, Staci A.; Sagar, Kelly A.; Dahlgren, Mary Kathryn; Gonenç, Atilla; Conn, Nina A.; Winer, Jeffrey P.; Penetar, David; Lukas, Scott E.

2015-01-01

Objective Citicoline is an endogenous nucleotide that has historically been used to treat stroke, traumatic brain injury, and cognitive dysfunction. Research has also shown that citicoline treatment is associated with improved cognitive performance in substance-abusing populations. We hypothesized that marijuana (MJ) smokers who received citicoline would demonstrate improvement in cognitive performance as well as increased neural efficiency during tasks of cognitive control relative to those who received placebo. Method The current study tested this hypothesis by examining the effects of citicoline in treatment-seeking chronic MJ smokers. In an 8-week double-blind, placebo-controlled study, 19 MJ smokers were randomly assigned via a double-blind procedure to the citicoline (8 Males, 2 Females) or placebo group (9 Males, 0 Females). All participants completed fMRI scanning at baseline and after 8 weeks of treatment during two cognitive measures of inhibitory processing, the Multi Source Interference Test (MSIT) and Stroop Color Word Test, and also completed the Barratt Impulsiveness Scale (BIS-11), a self-report measure of impulsivity. Results Following the 8 week trial, MJ smokers treated with citicoline demonstrated significantly lower levels of behavioral impulsivity, improved task accuracy on both the MSIT and Stroop tasks, and exhibited significantly different patterns of brain activation relative to baseline levels and relative to those who received placebo. Conclusions Findings suggest that citicoline may facilitate the treatment of MJ use disorders by improving the cognitive skills necessary to fully engage in comprehensive treatment programs. PMID:26658924

Coaxial CoMoO4 nanowire arrays with chemically integrated conductive coating for high-performance flexible all-solid-state asymmetric supercapacitors

NASA Astrophysics Data System (ADS)

Chen, Yaping; Liu, Borui; Liu, Qi; Wang, Jun; Li, Zhanshuang; Jing, Xiaoyan; Liu, Lianhe

2015-09-01

Flexible all-solid-state supercapacitors have offered promising applications as novel energy storage devices based on their merits, such as small size, low cost, light weight and high wearability for high-performance portable electronics. However, one major challenge to make flexible all-solid-state supercapacitors depends on the improvement of electrode materials with higher electrical conductivity properties and longer cycling stability. In this article, we put forward a simple strategy to in situ synthesize 1D CoMoO4 nanowires (NWs), using highly conductive CC and an electrically conductive PPy wrapping layer on CoMoO4 NW arrays for high performance electrode materials. The results show that the CoMoO4/PPy hybrid NW electrode exhibits a high areal specific capacitance of ca. 1.34 F cm-2 at a current density of 2 mA cm-2, which is remarkably better than the corresponding values for a pure CoMoO4 NW electrode of 0.7 F cm-2. An excellent cycling performance of nanocomposites of up to 95.2% (ca. 1.12 F cm-2) is achieved after 2000 cycles compared to pristine CoMoO4 NWs. In addition, we fabricate flexible all-solid-state ASC which can be cycled reversibly in the voltage range of 0-1.7 V, and exhibits a maximum energy density of 104.7 W h kg-1 (3.522 mW h cm-3), demonstrating great potential for practical applications in flexible energy storage electronics.Flexible all-solid-state supercapacitors have offered promising applications as novel energy storage devices based on their merits, such as small size, low cost, light weight and high wearability for high-performance portable electronics. However, one major challenge to make flexible all-solid-state supercapacitors depends on the improvement of electrode materials with higher electrical conductivity properties and longer cycling stability. In this article, we put forward a simple strategy to in situ synthesize 1D CoMoO4 nanowires (NWs), using highly conductive CC and an electrically conductive PPy wrapping layer on CoMoO4 NW arrays for high performance electrode materials. The results show that the CoMoO4/PPy hybrid NW electrode exhibits a high areal specific capacitance of ca. 1.34 F cm-2 at a current density of 2 mA cm-2, which is remarkably better than the corresponding values for a pure CoMoO4 NW electrode of 0.7 F cm-2. An excellent cycling performance of nanocomposites of up to 95.2% (ca. 1.12 F cm-2) is achieved after 2000 cycles compared to pristine CoMoO4 NWs. In addition, we fabricate flexible all-solid-state ASC which can be cycled reversibly in the voltage range of 0-1.7 V, and exhibits a maximum energy density of 104.7 W h kg-1 (3.522 mW h cm-3), demonstrating great potential for practical applications in flexible energy storage electronics. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr02961a

76 FR 4987 - Culturally Significant Objects Imported for Exhibition Determinations: “Bali: Art, Ritual...

Federal Register 2010, 2011, 2012, 2013, 2014

2011-01-27

... DEPARTMENT OF STATE [Public Notice: 7311] Culturally Significant Objects Imported for Exhibition Determinations: ``Bali: Art, Ritual, Performance'' SUMMARY: Notice is hereby given of the following... objects to be included in the exhibition ``Bali: Art, Ritual, Performance,'' imported from abroad for...

5-HT2A receptor antagonists improve motor impairments in the MPTP mouse model of Parkinson's disease.

PubMed

Ferguson, Marcus C; Nayyar, Tultul; Deutch, Ariel Y; Ansah, Twum A

2010-01-01

Clinical observations have suggested that ritanserin, a 5-HT(2A/C) receptor antagonist may reduce motor deficits in persons with Parkinson's Disease (PD). To better understand the potential antiparkinsonian actions of ritanserin, we compared the effects of ritanserin with the selective 5-HT(2A) receptor antagonist M100907 and the selective 5-HT(2C) receptor antagonist SB 206553 on motor impairments in mice treated with 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP). MPTP-treated mice exhibited decreased performance on the beam-walking apparatus. These motor deficits were reversed by acute treatment with L-3,4-dihydroxyphenylalanine (levodopa). Both the mixed 5-HT(2A/C) antagonist ritanserin and the selective 5-HT(2A) antagonist M100907 improved motor performance on the beam-walking apparatus. In contrast, SB 206553 was ineffective in improving the motor deficits in MPTP-treated mice. These data suggest that 5-HT(2A) receptor antagonists may represent a novel approach to ameliorate motor symptoms of Parkinson's disease. Published by Elsevier Ltd.

5-HT2A receptor antagonists improve motor impairments in the MPTP mouse model of Parkinson's disease

PubMed Central

Ferguson, Marcus C.; Nayyar, Tultul; Deutch, Ariel Y.; Ansah, Twum A.

2010-01-01

Clinical observations have suggested that ritanserin, a 5-HT2A/C receptor antagonist may reduce motor deficits in persons with Parkinson's Disease (PD). To better understand the potential antiparkinsonian actions of ritanserin, we compared the effects of ritanserin with the selective 5-HT2A receptor antagonist M100907 and the selective 5-HT2C receptor antagonist SB 206553 on motor impairments in mice treated with 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP). MPTP-treated mice exhibited decreased performance on the beam-walking apparatus. These motor deficits were reversed by acute treatment with L-3,4-dihydroxyphenylalanine (levodopa). Both the mixed 5-HT2A/C antagonist ritanserin and the selective 5-HT2A antagonist M100907 improved motor performance on the beam-walking apparatus. In contrast, SB 206553 was ineffective in improving the motor deficits in MPTP-treated mice. These data suggest that 5-HT2A receptor antagonists may represent a novel approach to ameliorate motor symptoms of Parkinson's disease. PMID:20361986

Computerized trainings in four groups of struggling readers: Specific effects on word reading and comprehension.

PubMed

Potocki, Anna; Magnan, Annie; Ecalle, Jean

2015-01-01

Four groups of poor readers were identified among a population of students with learning disabilities attending a special class in secondary school: normal readers; specific poor decoders; specific poor comprehenders, and general poor readers (deficits in both decoding and comprehension). These students were then trained with a software program designed to encourage either their word decoding skills or their text comprehension skills. After 5 weeks of training, we observed that the students experiencing word reading deficits and trained with the decoding software improved primarily in the reading fluency task while those exhibiting comprehension deficits and trained with the comprehension software showed improved performance in listening and reading comprehension. But interestingly, the latter software also led to improved performance on the word recognition task. This result suggests that, for these students, training interventions focused at the text level and its comprehension might be more beneficial for reading in general (i.e., for the two components of reading) than word-level decoding trainings. Copyright © 2015 Elsevier Ltd. All rights reserved.

[Pay for performance (P4P). Long-term effects and perspectives].

PubMed

Schrappe, M; Gültekin, N

2011-02-01

After 10 years of experience and research, a wide array of results on evaluation and long-term effects of pay for performance (P4P) programs have been published. These data do not only give insight into most of the problems of implementation, but also into aspects which, in part, may attenuate the high expectations at the beginning of the discussion. P4P programs exhibit a ceiling effect, some improvements are reversed after incentives are cancelled, and improvements show opportunity costs as absent improvements for indicators, which are not object to financial incentives (in some cases for the same disease). These observations can be explained by the hypothesis that P4P programs have characteristics of fee-for-service reimbursement, if symmetric information is available for insurance and provider. P4P programs are local instruments. While integration of healthcare is considered as an important issue, they should be combined with programs and incentives which foster further vertical and horizontal integration. For Germany, further research in the implementation and effects of P4P programs is necessary.

Improvement of the Thermal and Optical Performances of Protective Polydimethylsiloxane Space Coatings with Cellulose Nanocrystal Additives.

PubMed

Planes, Mikael; Brand, Jérémie; Lewandowski, Simon; Remaury, Stéphanie; Solé, Stéphane; Le Coz, Cédric; Carlotti, Stéphane; Sèbe, Gilles

2016-10-07

This work investigates the possibility of using cellulose nanocrystals (CNCs) as biobased nanoadditives in protective polydimethylsiloxane (PDMS) space coatings, to improve the thermal and optical performances of the material. CNCs produced from wood pulp were functionalized in different conditions with the objective to improve their dispersibility in the PDMS matrix, increase their thermal stability and provide photoactive functions. Polysiloxane, cinnamate, chloroacetate and trifluoroacetate moieties were accordingly anchored at the CNCs surface by silylation, using two different approaches, or acylation with different functional vinyl esters. The modified CNCs were thoroughly characterized by FT-IR spectroscopy, solid-state NMR spectroscopy and thermogravimetric analysis, before being incorporated into a PDMS space coating formulation in low concentration (0.5 to 4 wt %). The cross-linked PDMS films were subsequently investigated with regards to their mechanical behavior, thermal stability and optical properties after photoaging. Results revealed that the CNC additives could significantly improve the thermal stability of the PDMS coating, up to 140 °C, depending on the treatment and CNC concentration, without affecting the mechanical properties and transparency of the material. In addition, the PDMS films loaded with as low as 1 wt % halogenated nanoparticles, exhibited an improved UV-stability after irradiation in geostationary conditions.

Resistance Training Reduces Force Tremor and Improves Manual Dexterity in Older Individuals With Essential Tremor.

PubMed

Kavanagh, Justin J; Wedderburn-Bisshop, Jacob; Keogh, Justin W L

2016-01-01

Although symptoms of Essential Tremor (ET) are typically controlled with medication, it is of interest to explore additional therapies to assist with functionality. The purpose of this study was to determine if a generalized upper limb resistance training (RT) program improves manual dexterity and reduces force tremor in older individuals with ET. Ten Essential Tremor and 9 controls were recruited into a dual group, pretest-posttest intervention study. Participants performed 6 weeks of upper-limb RT, and battery of manual dexterity and isometric force tremor assessments were performed before and after the RT to determine the benefits of the program. The six-week, high-load, RT program produced strength increases in each limb for the ET and healthy older group. These changes in strength aligned with improvements in manual dexterity and tremor-most notably for the ET group. The least affected limb and the most affected limb exhibited similar improvements in functional assessments of manual dexterity, whereas reductions in force tremor amplitude following the RT program were restricted to the most affected limb of the ET group. These findings suggest that generalized upper limb RT program has the potential to improve aspects of manual dexterity and reduce force tremor in older ET patients.

Boosting pitch encoding with audiovisual interactions in congenital amusia.

PubMed

Albouy, Philippe; Lévêque, Yohana; Hyde, Krista L; Bouchet, Patrick; Tillmann, Barbara; Caclin, Anne

2015-01-01

The combination of information across senses can enhance perception, as revealed for example by decreased reaction times or improved stimulus detection. Interestingly, these facilitatory effects have been shown to be maximal when responses to unisensory modalities are weak. The present study investigated whether audiovisual facilitation can be observed in congenital amusia, a music-specific disorder primarily ascribed to impairments of pitch processing. Amusic individuals and their matched controls performed two tasks. In Task 1, they were required to detect auditory, visual, or audiovisual stimuli as rapidly as possible. In Task 2, they were required to detect as accurately and as rapidly as possible a pitch change within an otherwise monotonic 5-tone sequence that was presented either only auditorily (A condition), or simultaneously with a temporally congruent, but otherwise uninformative visual stimulus (AV condition). Results of Task 1 showed that amusics exhibit typical auditory and visual detection, and typical audiovisual integration capacities: both amusics and controls exhibited shorter response times for audiovisual stimuli than for either auditory stimuli or visual stimuli. Results of Task 2 revealed that both groups benefited from simultaneous uninformative visual stimuli to detect pitch changes: accuracy was higher and response times shorter in the AV condition than in the A condition. The audiovisual improvements of response times were observed for different pitch interval sizes depending on the group. These results suggest that both typical listeners and amusic individuals can benefit from multisensory integration to improve their pitch processing abilities and that this benefit varies as a function of task difficulty. These findings constitute the first step towards the perspective to exploit multisensory paradigms to reduce pitch-related deficits in congenital amusia, notably by suggesting that audiovisual paradigms are effective in an appropriate range of unimodal performance. Copyright © 2014 Elsevier Ltd. All rights reserved.

Study of electrode pattern design for a CZT-based PET detector.

PubMed

Gu, Y; Levin, C S

2014-06-07

We are developing a 1 mm resolution small animal positron emission tomography (PET) system using 3D positioning cadmium zinc telluride photon detectors comprising 40 mm × 40 mm × 5 mm crystals metalized with a cross-strip electrode pattern with a 1 mm anode strip pitch. We optimized the electrode pattern design for intrinsic sensitivity and spatial, energy and time resolution performance using a test detector comprising cathode and steering electrode strips of varying dimensions. The study found 3 and 5 mm width cathode strips locate charge-shared photon interactions near cathode strip boundaries with equal precision. 3 mm width cathode strips exhibited large time resolution variability as a function of photon interaction location between the anode and cathode planes (~26 to ~127.5 ns full width at half maximum (FWHM) for 0.5 mm and 4.2 mm depths, respectively). 5 mm width cathode strips by contrast exhibited more stable time resolution for the same interaction locations (~34 to ~83 ns FWHM), provided more linear spatial positioning in the direction orthogonal to the electrode planes, and as much as 68.4% improvement in photon sensitivity over the 3 mm wide cathode strips. The results were understood by analyzing the cathode strips' weighting functions, which indicated a stronger 'small pixel' effect in the 3 mm wide cathode strips. Photon sensitivity and anode energy resolution were seen to improve with decreasing steering electrode bias from 0 to -80 V w.r.t. the anode potential. A slight improvement in energy resolution was seen for wider steering electrode strips (400 versus 100 µm) for charge-shared photon interactions. Although this study successfully focused on electrode pattern features for PET performance, the results are generally applicable to semiconductor photon detectors employing cross-trip electrode patterns.

Study of electrode pattern design for a CZT-based PET detector

PubMed Central

Gu, Y; Levin, C S

2014-01-01

We are developing a 1 mm resolution small animal positron emission tomography (PET) system using 3-D positioning Cadmium Zinc Telluride (CZT) photon detectors comprising 40 mm × 40 mm × 5 mm crystals metalized with a cross-strip electrode pattern with a 1 mm anode strip pitch. We optimized the electrode pattern design for intrinsic sensitivity and spatial, energy and time resolution performance using a test detector comprising cathode and steering electrode strips of varying dimensions. The study found 3 mm and 5 mm width cathode strips locate charge-shared photon interactions near cathode strip boundaries with equal precision. 3 mm width cathode strips exhibited large time resolution variability as a function of photon interaction location between the anode and cathode planes (~26 ns to ~127.5 ns FWHM for 0.5 mm and 4.2 mm depths, respectively). 5 mm width cathode strips by contrast exhibited more stable time resolution for the same interaction locations (~34 ns to ~83 ns FWHM), provided more linear spatial positioning in the direction orthogonal to the electrode planes, and as much as 68.4% improvement in photon sensitivity over the 3 mm wide cathode strips. The results were understood by analyzing the cathode strips’ weighting functions, which indicated a stronger “small pixel” effect in the 3 mm wide cathode strips. Photon sensitivity and anode energy resolution were seen to improve with decreasing steering electrode bias from 0 V to −80 V w.r.t the anode potential. A slight improvement in energy resolution was seen for wider steering electrode strips (400 μm vs. 100 μm) for charge-shared photon interactions. Although this study successfully focused on electrode pattern features for PET performance, the results are generally applicable to semiconductor photon detectors employing cross-trip electrode patterns. PMID:24786208

PROJECT KAIZEN. Review of the Oversight by Congress of DoD Acquisition Programs with the Aim of Continuous Improvement

DTIC Science & Technology

1994-06-01

legitimate firms from being competitive in a global market and selling to DoD. CONCLUSION While there are some improvements in the way DoD purchases...and a final report . RDT&E BUDGET EXHIBITS DRAFT RDT&E BUDGET EXHIBITS HANDBOOK PREPARATION/REVIEW GUIDELINES Craig A . Farr Dennis L. Ryan, CAPT, USN... A -1 Chapter 5. Financial Management Regulation LIST OF FIGURES Figure 1I- RDT&E Exhibits Timeline

Pressure effects on structural, electronic, elastic and lattice dynamical properties of XSi2 (X = Cr, Mo, W) from first principles

NASA Astrophysics Data System (ADS)

Zhu, Haiyan; Shi, Liwei; Li, Shuaiqi; Zhang, Shaobo; Xia, Wangsuo

2018-04-01

First-principles calculations have been performed to study the structure, elastic and lattice dynamical properties of C40 XSi2 (X=Cr, Mo, W) under hydrostatic pressure. The obtained structural parameters are in line with existing experimental and theoretical data. The evolutions of fundamental bandgap energies, elastic moduli, IR absorption spectra with pressure have been investigated in detail. Our results indicate that the energy gaps of XSi2 (X=Cr, Mo, W) show different trends as the pressure increases. Larger BH/GH ratio and Poisson’s ratio are achieved with pressure, suggesting an improved ductility for XSi2 (X=Cr, Mo, W). Moreover, a large elastic anisotropy under pressure is exhibited in Young’s anisotropic factors. The infrared-active phonon frequencies exhibit substantial blueshifts under pressure.

Enhanced planar perovskite solar cell efficiency and stability using a perovskite/PCBM heterojunction formed in one step.

PubMed

Zhou, Long; Chang, Jingjing; Liu, Ziye; Sun, Xu; Lin, Zhenhua; Chen, Dazheng; Zhang, Chunfu; Zhang, Jincheng; Hao, Yue

2018-02-08

Perovskite/PCBM heterojunctions are efficient for fabricating perovskite solar cells with high performance and long-term stability. In this study, an efficient perovskite/PCBM heterojunction was formed via conventional sequential deposition and one-step formation processes. Compared with conventional deposition, the one-step process was more facile, and produced a perovskite thin film of substantially improved quality due to fullerene passivation. Moreover, the resulting perovskite/PCBM heterojunction exhibited more efficient carrier transfer and extraction, and reduced carrier recombination. The perovskite solar cell device based on one-step perovskite/PCBM heterojunction formation exhibited a higher maximum PCE of 17.8% compared with that from the conventional method (13.7%). The device also showed exceptional stability, retaining 83% of initial PCE after 60 days of storage under ambient conditions.

Design of Compact Flower Shape Dual Notched-Band Monopole Antenna for Extended UWB Wireless Applications

NASA Astrophysics Data System (ADS)

Sharma, Manish; Awasthi, Y. K.; Singh, Himanshu; Kumar, Raj; Kumari, Sarita

2016-11-01

In this letter, a compact monopole antenna for ultra wideband (UWB) applications is proposed with small size of 18×20=360 mm2. Antenna consist of a flower shape radiating patch with a pair of C-shaped slots which offer two notch bands for WiMAX (3.04-3.68 GHz) & WLAN (4.73-5.76 GHz) and two rectangular shaped slots in the ground plane which provides a wide measured usable fractional extended bandwidth of 163 % (2.83-14.0 GHz) with improved VSWR. Moreover, it is also convenient for other wireless application as close range radar, 8-12 GHz in X-band. Measured radiation patterns exhibits nearly omnidirectional in H-plane and dipole like pattern in E-plane across the bandwidth and furthermore exhibits good time domain performance.

Heat transfer enhancement in a lithium-ion cell through improved material-level thermal transport

DOE Office of Scientific and Technical Information (OSTI.GOV)

Vishwakarma, Vivek; Waghela, Chirag; Wei, Zi

2016-09-25

We report that while Li-ion cells offer excellent electrochemical performance for several applications including electric vehicles, they also exhibit poor thermal transport characteristics, resulting in reduced performance, overheating and thermal runaway. Inadequate heat removal from Li-ion cells originates from poor thermal conductivity within the cell. This paper identifies the rate-limiting material-level process that dominates overall thermal conduction in a Li-ion cell. Results indicate that thermal characteristics of a Li-ion cell are largely dominated by heat transfer across the cathode-separator interface rather than heat transfer through the materials themselves. This interfacial thermal resistance contributes around 88% of total thermal resistance inmore » the cell. Measured value of interfacial resistance is close to that obtained from theoretical models that account for weak adhesion and large acoustic mismatch between cathode and separator. Further, to address this problem, an amine-based chemical bridging of the interface is carried out. This is shown to result in in four-times lower interfacial thermal resistance without deterioration in electrochemical performance, thereby increasing effective thermal conductivity by three-fold. This improvement is expected to reduce peak temperature rise during operation by 60%. Finally, by identifying and addressing the material-level root cause of poor thermal transport in Li-ion cells, this work may contribute towards improved thermal performance of Li-ion cells.« less

Ginkobiloba extract improves working memory performance in middle-aged women: role of asymmetry of prefrontal cortex activity during a working memory task.

PubMed

Sakatani, Kaoru; Tanida, Masahiro; Hirao, Naoyasu; Takemura, Naohiro

2014-01-01

In order to clarify the mechanism through which extract of Ginkgo biloba leaves (EGb) improves cognitive function, we examined the effects of EGb on cerebral blood oxygenation in the prefrontal cortex (PFC) and on performance during a working memory task, using near-infrared spectrometry (NIRS). First, we evaluated differences in behavioral performance of the Sternberg working memory test (ST) and in the activation pattern of the PFC during ST between 15 young and 19 middle-aged healthy women. Then, we examined the effect of EGb (120 mg/day for 6 weeks) on ST performance and PFC activation pattern in the middle-aged group. The middle-aged group exhibited a longer reaction time (RT) in ST than the young group and showed a different PFC activation pattern during ST, i.e., the middle-aged group showed bilateral activation while the young group showed right-dominant activation. In the middle-aged group, administration of EGb for 6 weeks shortened the RT of ST and changed the PFC activation pattern to right-dominant, like that in the young group. The results indicate the PFC plays a role in the physiological cognitive function-enhancing effect of EGb. EGb might improve working memory function in middle-aged individuals by counteracting the occurrence of aging-related hemispheric asymmetry reduction.

Controllable one-pot synthesis of a nest-like Bi2WO6/BiVO4 composite with enhanced photocatalytic antifouling performance under visible light irradiation.

PubMed

Ju, Peng; Wang, Yi; Sun, Yan; Zhang, Dun

2016-03-21

In this study, a novel visible-light-sensitive Bi2WO6/BiVO4 composite photocatalyst was controllably synthesized through a facile one-pot hydrothermal method. The Bi2WO6/BiVO4 composite exhibited a perfect nest-like hierarchical microsphere structure, which was constructed by the self-assembly of nanoplates with the assistance of polyvinylpyrrolidone (PVP). The growth mechanism of the Bi2WO6/BiVO4 composite and the effect of its structure on its photocatalytic performance was investigated and proposed. Experimental results showed that the Bi2WO6/BiVO4 composites displayed enhanced photocatalytic antifouling activities under visible light irradiation compared to pure Bi2WO6 and BiVO4. Bi2WO6/BiVO4-1 exhibited the best photocatalytic antifouling performance, and almost all (99.99%) Pseudomonas aeruginosa (P. aeruginosa), Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) bacteria were killed within 30 min. Moreover, the Bi2WO6/BiVO4-1 composite exhibited excellent stability and reusability in the cycled experiments. The photocatalytic antifouling mechanism was proposed based on the active species trapping experiments, revealing that the photo-induced holes (h(+)) and hydroxyl radicals (˙OH) could attack the cell wall and cytoplasmic membrane directly and lead to the death of bacteria. The obviously enhanced photocatalytic activity of the Bi2WO6/BiVO4-1 composite could be mainly attributed to the formation of heterojunctions, accelerating the separation of photo-induced electrons and holes. Furthermore, the large BET surface area combined with the wide photoabsorption region further improved the photocatalytic performance of the Bi2WO6/BiVO4-1 composite. This study provides a new strategy to develop novel composite photocatalysts with enhanced photocatalytic performance for marine antifouling and water purification.

Complete Au@ZnO core-shell nanoparticles with enhanced plasmonic absorption enabling significantly improved photocatalysis

NASA Astrophysics Data System (ADS)

Sun, Yiqiang; Sun, Yugang; Zhang, Tao; Chen, Guozhu; Zhang, Fengshou; Liu, Dilong; Cai, Weiping; Li, Yue; Yang, Xianfeng; Li, Cuncheng

2016-05-01

Nanostructured ZnO exhibits high chemical stability and unique optical properties, representing a promising candidate among photocatalysts in the field of environmental remediation and solar energy conversion. However, ZnO only absorbs the UV light, which accounts for less than 5% of total solar irradiation, significantly limiting its applications. In this article, we report a facile and efficient approach to overcome the poor wettability between ZnO and Au by carefully modulating the surface charge density on Au nanoparticles (NPs), enabling rapid synthesis of Au@ZnO core-shell NPs at room temperature. The resulting Au@ZnO core-shell NPs exhibit a significantly enhanced plasmonic absorption in the visible range due to the Au NP cores. They also show a significantly improved photocatalytic performance in comparison with their single-component counterparts, i.e., the Au NPs and ZnO NPs. Moreover, the high catalytic activity of the as-synthesized Au@ZnO core-shell NPs can be maintained even after many cycles of photocatalytic reaction. Our results shed light on the fact that the Au@ZnO core-shell NPs represent a promising class of candidates for applications in plasmonics, surface-enhanced spectroscopy, light harvest devices, solar energy conversion, and degradation of organic pollutants.Nanostructured ZnO exhibits high chemical stability and unique optical properties, representing a promising candidate among photocatalysts in the field of environmental remediation and solar energy conversion. However, ZnO only absorbs the UV light, which accounts for less than 5% of total solar irradiation, significantly limiting its applications. In this article, we report a facile and efficient approach to overcome the poor wettability between ZnO and Au by carefully modulating the surface charge density on Au nanoparticles (NPs), enabling rapid synthesis of Au@ZnO core-shell NPs at room temperature. The resulting Au@ZnO core-shell NPs exhibit a significantly enhanced plasmonic absorption in the visible range due to the Au NP cores. They also show a significantly improved photocatalytic performance in comparison with their single-component counterparts, i.e., the Au NPs and ZnO NPs. Moreover, the high catalytic activity of the as-synthesized Au@ZnO core-shell NPs can be maintained even after many cycles of photocatalytic reaction. Our results shed light on the fact that the Au@ZnO core-shell NPs represent a promising class of candidates for applications in plasmonics, surface-enhanced spectroscopy, light harvest devices, solar energy conversion, and degradation of organic pollutants. Electronic supplementary information (ESI) available. See DOI: 10.1039/c6nr00933f

Mode Matching for Optical Antennas

NASA Astrophysics Data System (ADS)

Feichtner, Thorsten; Christiansen, Silke; Hecht, Bert

2017-11-01

The emission rate of a point dipole can be strongly increased in the presence of a well-designed optical antenna. Yet, optical antenna design is largely based on radio-frequency rules, ignoring, e.g., Ohmic losses and non-negligible field penetration in metals at optical frequencies. Here, we combine reciprocity and Poynting's theorem to derive a set of optical-frequency antenna design rules for benchmarking and optimizing the performance of optical antennas driven by single quantum emitters. Based on these findings a novel plasmonic cavity antenna design is presented exhibiting a considerably improved performance compared to a reference two-wire antenna. Our work will be useful for the design of high-performance optical antennas and nanoresonators for diverse applications ranging from quantum optics to antenna-enhanced single-emitter spectroscopy and sensing.

Improved electrochemical performance of Li1.2Mn0.54Ni0.13Co0.13O2 cathode material synthesized by citric acid assisted sol-gel method for lithium ion batteries

NASA Astrophysics Data System (ADS)

Li, Shiyou; Liang, Youwei; Lei, Dan; Xie, Yingchun; Ai, Ling; Xie, Jing

2018-03-01

A citric acid assisted sol-gel method is employed for synthesizing Li1.2Mn0.54Ni0.13Co0.13O2 used as a cathode material in lithium-ion batteries. Powder X-ray diffraction (XRD) and scanning electron microscopy (SEM) characterizations prove that materials have a typical a-NaFeO2 structure with primary nano-sized particles. Electrochemical performances have been investigated by charge-discharge test and results show that the synthesized product exhibits excellent electrochemical performance with a high initial discharge capacity of 253.5 mAh g-1 at 0.1 C and a preferable capacity retention of 84.8% after 50 cycles.

Solvent control of the morphology of the hole transport layer for high-performance perovskite solar cells

NASA Astrophysics Data System (ADS)

Xie, Xiaoyin; Liu, Guanchen; Chen, Li; Li, Shuangcui; Liu, Zhihai

2017-11-01

We investigated the effect of the morphology of 2,2‧,7,7‧-tetrakis-(N,N-di-p-methoxyphenylamine)-9,9‧-spirobifluorene (spiro-OMeTAD) prepared using chlorobenzene (CB) and 1,2-dichlorobenzene (DCB) on the performance of perovskite solar cells (PSCs). We find that a more uniform and smoother spiro-OMeTAD layer was obtained using DCB than CB. The PSCs prepared using DCB exhibited a higher power conversion efficiency (PCE = 16.2%) than those obtained using CB (PCE = 14.5%). The hysteresis was reduced from 4.8% to 0.6%, with improved stability. The highest PCE of PSCs prepared using DCB was 16.6%, indicating that the use of DCB for spiro-OMeTAD processing enables the fabrication of high-performance PSCs.

Analysis of improved dc and ac performances of an InGaP/GaAs heterojunction bipolar transistor with a graded Al xGa 1- xAs layer at emitter/base heterojunction

NASA Astrophysics Data System (ADS)

Cheng, Shiou-Ying

2004-07-01

An InGaP/GaAs heterojunction bipolar transistor (HBT) with a continuous conduction-band structure is demonstrated and theoretically investigated. This device exhibited good performance including lower turn-on voltage, lower offset voltage and smaller collector current saturation voltage. The novel aspect of device structure design is the adoption of the compositionally linear-graded AlGaAs layer between the InGaP-emitter and GaAs-base layers. Therefore, the device studied shows better dc and ac performances than a conventional device. Consequently, this causes the substantial benefit for practical analog and digital applications especially for lower operation voltage, lower power consumption commercial and military products.

Pseudocapacitive Behaviors of Li2FeTiO4/C Hybrid Porous Nanotubes for Novel Lithium-Ion Battery Anodes with Superior Performances.

PubMed

Tang, Yakun; Liu, Lang; Zhao, Hongyang; Zhang, Yue; Kong, Ling Bing; Gao, Shasha; Li, Xiaohui; Wang, Lei; Jia, Dianzeng

2018-06-20

Hybrid nanotubes of cation disordered rock salt structured Li 2 FeTiO 4 nanoparticles embedded in porous CNTs were developed. Such unique hybrids with continuous 3D electron transportation paths and isolated small particles have been shown to be an ideal architecture that brought out enhanced electrochemical performances. Meanwhile, they exhibited improved extrinsic capacitive characteristics. In addition, we demonstrate a successful example to use cathode active material as anode for lithium-ion batteries (LIBs). More importantly, our hybrids had much superior electrochemical performances than most of the reported Li 4 Ti 5 O 12 -based nanocomposites. Therefore, it is concluded that Li 2 FeTiO 4 can be a prospective anode material for LIBs.

PIN architecture for ultrasensitive organic thin film photoconductors.

PubMed

Jin, Zhiwen; Wang, Jizheng

2014-06-17

Organic thin film photoconductors (OTFPs) are expected to have wide applications in the field of optical communications, artificial vision and biomedical sensing due to their great advantages of high flexibility and low-cost large-area fabrication. However, their performances are not satisfactory at present: the value of responsivity (R), the parameter that measures the sensitivity of a photoconductor to light, is below 1 AW(-1). We believe such poor performance is resulted from an intrinsic self-limited effect of present bare blend based device structure. Here we designed a PIN architecture for OTFPs, the PIN device exhibits a significantly improved high R value of 96.5 AW(-1). The PIN architecture and the performance the PIN device shows here should represent an important step in the development of OTFPs.

PIN architecture for ultrasensitive organic thin film photoconductors

PubMed Central

Jin, Zhiwen; Wang, Jizheng

2014-01-01

Organic thin film photoconductors (OTFPs) are expected to have wide applications in the field of optical communications, artificial vision and biomedical sensing due to their great advantages of high flexibility and low-cost large-area fabrication. However, their performances are not satisfactory at present: the value of responsivity (R), the parameter that measures the sensitivity of a photoconductor to light, is below 1 AW−1. We believe such poor performance is resulted from an intrinsic self-limited effect of present bare blend based device structure. Here we designed a PIN architecture for OTFPs, the PIN device exhibits a significantly improved high R value of 96.5 AW−1. The PIN architecture and the performance the PIN device shows here should represent an important step in the development of OTFPs. PMID:24936952

Ultrasound-assisted oxidative desulfurization process of liquid fuel by phosphotungstic acid encapsulated in a interpenetrating amine-functionalized Zn(II)-based MOF as catalyst.

PubMed

Afzalinia, Ahmad; Mirzaie, Abbas; Nikseresht, Ahmad; Musabeygi, Tahereh

2017-01-01

In this work, ultrasound-assisted oxidative desulfurization (UAOD) of liquid fuels performed with a novel heterogeneous highly dispersed Keggin-type phosphotungstic acid (H 3 PW 12 O 40 , PTA) catalyst that encapsulated into an amino-functionalized MOF (TMU-17-NH 2 ). The prepared composite exhibits high catalytic activity and reusability in oxidative desulfurization of model fuel. Ultrasound-assisted oxidative desulfurization (UAOD) is a new way to performed oxidation reaction of sulfur-contain compounds rapidly, economically, environment-friendly and safely, under mild conditions. Ultrasound waves can be apply as an efficient tool to decrease the reaction time and improves oxidative desulfurization system performance. PTA@TMU-17-NH 2 could be completely performed desulfurization of the model oil by 20mg of catalyst, O/S molar ratio of 1:1 in presence of MeCN as extraction solvent. The obtained results indicated that the conversions of DBT to DBTO 2 achieve 98% after 15min in ambient temperature. In this work, we prepared TMU-17-NH 2 and PTA/TMU-17-NH 2 composite by ultrasound irradiation for first time and employed in UAOD process. Prepared catalyst exhibit an excellent reusability without PTA leaching and loss of activity. Copyright © 2016 The Authors. Published by Elsevier B.V. All rights reserved.

Electrostatic spray deposition of porous Fe 2O 3 thin films as anode material with improved electrochemical performance for lithium-ion batteries

NASA Astrophysics Data System (ADS)

Wang, L.; Xu, H. W.; Chen, P. C.; Zhang, D. W.; Ding, C. X.; Chen, C. H.

Iron oxide materials are attractive anode materials for lithium-ion batteries for their high capacity and low cost compared with graphite and most of other transition metal oxides. Porous carbon-free α-Fe 2O 3 films with two types of pore size distribution were prepared by electrostatic spray deposition, and they were characterized by X-ray diffraction, scanning electron microscopy and X-ray absorption near-edge spectroscopy. The 200 °C-deposited thin film exhibits a high reversible capacity of up to 1080 mAh g -1, while the initial capacity loss is at a remarkable low level (19.8%). Besides, the energy efficiency and energy specific average potential (E av) of the Fe 2O 3 films during charge/discharge process were also investigated. The results indicate that the porous α-Fe 2O 3 films have significantly higher energy density than Li 4Ti 5O 12 while it has a similar E av of about 1.5 V. Due to the porous structure that can buffer the volume changes during lithium intercalation/de-intercalation, the films exhibit stable cycling performance. As a potential anode material for high performance lithium-ion batteries that can be applied on electric vehicle and energy storage, rate capability and electrochemical performance under high-low temperatures were also investigated.

OPTIMIZATION OF MUD HAMMER DRILLING PERFORMANCE - A PROGRAM TO BENCHMARK THE VIABILITY OF ADVANCED MUD HAMMER DRILLING

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gordon Tibbitts; Arnis Judzis

2001-10-01

This document details the progress to date on the OPTIMIZATION OF MUD HAMMER DRILLING PERFORMANCE -- A PROGRAM TO BENCHMARK THE VIABILITY OF ADVANCED MUD HAMMER DRILLING contract for the quarter starting July 2001 through September 2001. Accomplishments to date include the following: TerraTek highlighted DOE's National Energy Technology Laboratory effort on Mud Hammer Optimization at the recent Annual Conference and Exhibition for the Society of Petroleum Engineers. The original exhibit scheduled by NETL was canceled due to events surrounding the September tragedies in the US. TerraTek has completed analysis of drilling performance (rates of penetration, hydraulics, etc.) for themore » Phase One testing which was completed at the beginning of July. TerraTek jointly with the Industry Advisory Board for this project and DOE/NETL conducted a lessons learned meeting to transfer technology vital for the next series of performance tests. Both hammer suppliers benefited from the testing program and are committed to pursue equipment improvements and ''optimization'' in accordance with the scope of work. An abstract for a proposed publication by the society of Petroleum Engineers/International Association of Drilling Contractors jointly sponsored Drilling Conference was accepted as an alternate paper. Technology transfer is encouraged by the DOE in this program, thus plans are underway to prepare the paper for this prestigious venue.« less

Ultrahigh photo-responsivity and detectivity in multilayer InSe nanosheets phototransistors with broadband response

DOE PAGES

Feng, Wei; Wu, Jing-Bin; Li, Xiaoli; ...

2015-05-20

In this paper, we demonstrate the strategies and principles for the performance improvement of layered semiconductor based photodetectors using multilayer indium selenide (InSe) as the model material. It is discovered that multiple reflection interference at the interfaces in the phototransistor device leads to a thickness-dependent photo-response, which provides a guideline to improve the performance of layered semiconductor based phototransistors. The responsivity and detectivity of InSe nanosheet phototransistor can be adjustable using applied gate voltage. Our InSe nanosheet phototransistor exhibits ultrahigh responsivity and detectivity. An ultrahigh external photo-responsivity of ~10 4 A W -1 can be achieved from broad spectra rangingmore » from UV to near infrared wavelength using our InSe nanosheet photodetectors. The detectivity of multilayer InSe devices is ~10 12 to 10 13 Jones, which surpasses that of the currently exploited InGaAs photodetectors (10 11 to 10 12 Jones). Finally, this research shows that multilayer InSe nanosheets are promising materials for high performance photodetectors.« less

Watching novice action degrades expert motor performance: Causation between action production and outcome prediction of observed actions by humans

PubMed Central

Ikegami, Tsuyoshi; Ganesh, Gowrishankar

2014-01-01

Our social skills are critically determined by our ability to understand and appropriately respond to actions performed by others. However despite its obvious importance, the mechanisms enabling action understanding in humans have remained largely unclear. A popular but controversial belief is that parts of the motor system contribute to our ability to understand observed actions. Here, using a novel behavioral paradigm, we investigated this belief by examining a causal relation between action production, and a component of action understanding - outcome prediction, the ability of a person to predict the outcome of observed actions. We asked dart experts to watch novice dart throwers and predict the outcome of their throws. We modulated the feedbacks provided to them, caused a specific improvement in the expert's ability to predict watched actions while controlling the other experimental factors, and exhibited that a change (improvement) in their outcome prediction ability results in a progressive and proportional deterioration in the expert's own darts performance. This causal relationship supports involvement of the motor system in outcome prediction by humans of actions observed in others. PMID:25384755

Defect-enhanced performance of a 3D graphene anode in a lithium-ion battery

NASA Astrophysics Data System (ADS)

Guo, Hongchen; Long, Deng; Zheng, Zongmin; Chen, Xinyi; Ng, Alan M. C.; Lu, Miao

2017-12-01

Morphological defects were generated in an undoped 3D graphene structure via the involvement of a ZnO and Mg(OH)2 intermediate nanostructure layer placed between two layers of vapor-deposited graphene. Once the intermediate layer was etched, the 3D graphene lost support and shrank; during this process many morphological defects were formed. The electrochemical performance of the derived defective graphene utilized as the anode of a lithium (Li)-ion battery was significantly improved from ˜382 mAh g-1 to ˜2204 mAh g-1 at 0.5 A g-1 compared to normal 3D graphene. The derived defective graphene exhibited an initial capacity of 1009 mAh g-1 and retention of 83% at 4 A g-1 for 500 cycles, and ˜330 mAh g-1 at a high rate of 20 A g-1. Complicated defects such as wrinkles, pores, and particles formed during the etching of the intermediate layer, were considered to contribute to the improvement of the electrochemical performance.

Exploration of permeability and antifouling performance on modified cellulose acetate ultrafiltration membrane with cellulose nanocrystals.

PubMed

Lv, Jinling; Zhang, Guoquan; Zhang, Hanmin; Yang, Fenglin

2017-10-15

Cellulose nanocrystals (CNCs) were introduced into cellulose diacetate (CDA) matrix via immerged phase-inversion process, aiming to improve the filtration and antifouling performance of CNCs/CDA blending membrane. The effects of CNCs on membrane morphologies, hydrophilicity, permeability and antifouling property were investigated. Results showed that the incorporation of CNCs into CDA membrane could effectively enhance the permeability and antifouling property of CNCs/CDA blending membrane by optimizing membrane microstructure and improving membrane hydrophilicity. A high pure water flux of 173.8L/m 2 h was achieved for the CNCs/CDA blending membrane at 200KPa, which is 24 times that of the CDA membrane (7.2L/m 2 h). The bovine serum albumin (BSA) adsorption amount of the CNCs/CDA blending membrane decreased about 48% compared to that of the CDA membrane. Additionally, the CNCs/CDA blending membrane exhibited better antifouling performance with the flux recovery ratio (FRR) of 89.5% after three fouling cycles, compared to 59.7% for the CDA membrane. Copyright © 2017 Elsevier Ltd. All rights reserved.

Optical coherence tomography angiography offers comprehensive evaluation of skin optical clearing in vivo by quantifying optical properties and blood flow imaging simultaneously

NASA Astrophysics Data System (ADS)

Guo, Li; Shi, Rui; Zhang, Chao; Zhu, Dan; Ding, Zhihua; Li, Peng

2016-08-01

Tissue optical clearing (TOC) is helpful for reducing scattering and enhancing the penetration depth of light, and shows promising potential in optimizing optical imaging performances. A mixture of fructose with PEG-400 and thiazone (FPT) is used as an optical clearing agent in mouse dorsal skin and evaluated with OCT angiography (Angio-OCT) by quantifying optical properties and blood flow imaging simultaneously. It is observed that FPT leads to an improved imaging performance for the deeper tissues. The imaging performance improvement is most likely caused by the FPT-induced dehydration of skin, and the reduction of scattering coefficient (more than ˜40.5%) and refractive-index mismatching (more than ˜25.3%) in the superficial (epidermal, dermal, and hypodermal) layers. A high correlation (up to ˜90%) between the relative changes in refractive-index mismatching and Angio-OCT signal strength is measured. The optical clearing rate is ˜5.83×10-5 cm/s. In addition, Angio-OCT demonstrates enhanced performance in imaging cutaneous hemodynamics with satisfactory spatiotemporal resolution and contrast when combined with TOC, which exhibits a powerful practical application in studying microcirculation.

The effect of surface modification of glass fiber on the performance of poly(lactic acid) composites: Graphene oxide vs. silane coupling agents

NASA Astrophysics Data System (ADS)

Jing, Mengfan; Che, Junjin; Xu, Shuman; Liu, Zhenwei; Fu, Qiang

2018-03-01

In this work, a comparison study was carried out to investigate the efficacy of glass fiber (GF) in reinforcing poly(lactic acid) (PLA) by using traditional silane coupling agents (GF-S) and novel graphene oxide (GF-GO) as surface modifiers. The crystallization behavior of the PLA matrix was investigated by differential scanning calorimetry. The mechanical performances and the thermomechanical properties of the composites were evaluated by uniaxial tensile testing and dynamic mechanical analysis, respectively. For neat GF without any treatment, the poor interfacial adhesion and the sharp shortening of the GF length result in the relatively poor mechanical performances of PLA/GF composites. However, the incorporation of GF-S significantly improves the mechanical strength and keeps relatively good toughness of the composites, while GF-GO exhibits excellent nucleation ability for PLA and could moderately increase the modulus of the composites. The thermomechanical properties of the composites are improved markedly resulting from the crystallinity increase. The different surface modification of glass fiber influences the crystallinity of matrix, the interfacial interaction and the length of fiber, which altogether affect the mechanical performances of the prepared PLA/GF composites.

Superior supercapacitors based on nitrogen and sulfur co-doped hierarchical porous carbon: Excellent rate capability and cycle stability

NASA Astrophysics Data System (ADS)

Zhang, Deyi; Han, Mei; Wang, Bing; Li, Yubing; Lei, Longyan; Wang, Kunjie; Wang, Yi; Zhang, Liang; Feng, Huixia

2017-08-01

Vastly improving the charge storage capability of supercapacitors without sacrificing their high power density and cycle performance would bring bright application prospect. Herein, we report a nitrogen and sulfur co-doped hierarchical porous carbon (NSHPC) with very superior capacitance performance fabricated by KOH activation of nitrogen and sulfur co-doped ordered mesoporous carbon (NSOMC). A high electrochemical double-layer (EDL) capacitance of 351 F g-1 was observed for the reported NSHPC electrodes, and the capacitance remains at 288 F g-1 even under a large current density of 20 A g-1. Besides the high specific capacitance and outstanding rate capability, symmetrical supercapacitor cell based on the NSHPC electrodes also exhibits an excellent cycling performance with 95.61% capacitance retention after 5000 times charge/discharge cycles. The large surface area caused by KOH activation (2056 m2 g-1) and high utilized surface area owing to the ideal micro/mesopores ratio (2.88), large micropores diameter (1.38 nm) and short opened micropores structure as well as the enhanced surface wettability induced by N and S heteroatoms doping and improved conductivity induced by KOH activation was found to be responsible for the very superior capacitance performance.

A Case Study on a Combination NDVI Forecasting Model Based on the Entropy Weight Method

DOE Office of Scientific and Technical Information (OSTI.GOV)

Huang, Shengzhi; Ming, Bo; Huang, Qiang

It is critically meaningful to accurately predict NDVI (Normalized Difference Vegetation Index), which helps guide regional ecological remediation and environmental managements. In this study, a combination forecasting model (CFM) was proposed to improve the performance of NDVI predictions in the Yellow River Basin (YRB) based on three individual forecasting models, i.e., the Multiple Linear Regression (MLR), Artificial Neural Network (ANN), and Support Vector Machine (SVM) models. The entropy weight method was employed to determine the weight coefficient for each individual model depending on its predictive performance. Results showed that: (1) ANN exhibits the highest fitting capability among the four orecastingmore » models in the calibration period, whilst its generalization ability becomes weak in the validation period; MLR has a poor performance in both calibration and validation periods; the predicted results of CFM in the calibration period have the highest stability; (2) CFM generally outperforms all individual models in the validation period, and can improve the reliability and stability of predicted results through combining the strengths while reducing the weaknesses of individual models; (3) the performances of all forecasting models are better in dense vegetation areas than in sparse vegetation areas.« less

Optimization of the Performance of Segmented Scintillators for Radiotherapy Imaging through Novel Binning Techniques

PubMed Central

El-Mohri, Youcef; Antonuk, Larry E.; Choroszucha, Richard B.; Zhao, Qihua; Jiang, Hao; Liu, Langechuan

2014-01-01

Thick, segmented crystalline scintillators have shown increasing promise as replacement x-ray converters for the phosphor screens currently used in active matrix flat-panel imagers (AMFPIs) in radiotherapy, by virtue of providing over an order of magnitude improvement in the DQE. However, element-to-element misalignment in current segmented scintillator prototypes creates a challenge for optimal registration with underlying AMFPI arrays, resulting in degradation of spatial resolution. To overcome this challenge, a methodology involving the use of a relatively high resolution AMFPI array in combination with novel binning techniques is presented. The array, which has a pixel pitch of 0.127 mm, was coupled to prototype segmented scintillators based on BGO, LYSO and CsI:Tl materials, each having a nominal element-to-element pitch of 1.016 mm and thickness of ~1 cm. The AMFPI systems incorporating these prototypes were characterized at a radiotherapy energy of 6 MV in terms of MTF, NPS, DQE, and reconstructed images of a resolution phantom acquired using a cone-beam CT geometry. For each prototype, the application of 8×8 pixel binning to achieve a sampling pitch of 1.016 mm was optimized through use of an alignment metric which minimized misregistration and thereby improved spatial resolution. In addition, the application of alternative binning techniques that exclude the collection of signal near septal walls resulted in further significant improvement in spatial resolution for the BGO and LYSO prototypes, though not for the CsI:Tl prototype due to the large amount of optical cross-talk resulting from significant light spread between scintillator elements in that device. The efficacy of these techniques for improving spatial resolution appears to be enhanced for scintillator materials that exhibit mechanical hardness, high density and high refractive index, such as BGO. Moreover, materials that exhibit these properties as well as offer significantly higher light output than BGO, such as CdWO4, should provide the additional benefit of preserving DQE performance. PMID:24487347

Performance of Bulk Heterojunction Photovoltaic Devices Prepared by Airbrush Spray Deposition

DOE Office of Scientific and Technical Information (OSTI.GOV)

Green, R.; Morfa, A.; Ferguson, A. J.

2008-01-01

We have used airbrush spray deposition to fabricate organic photovoltaic devices with an active layer composed of a blend of poly(3-hexylthiophene) and [6,6]-phenyl-C{sub 61} butyric acid methyl ester. Working devices were prepared in ambient conditions from a variety of common organic solvents; active layers prepared from chlorobenzene exhibit improved homogeneity, resulting in narrower distributions of the relevant device parameters. Further studies on devices prepared from chlorobenzene showed that annealing at 120 C for 10 min resulted in optimum performance, and that an active layer thickness of 150 nm resulted in a maximum efficiency of 2.35% under AM1.5 illumination at 1more » sun.« less

Films of Carbon Nanomaterials for Transparent Conductors

PubMed Central

Ho, Xinning; Wei, Jun

2013-01-01

The demand for transparent conductors is expected to grow rapidly as electronic devices, such as touch screens, displays, solid state lighting and photovoltaics become ubiquitous in our lives. Doped metal oxides, especially indium tin oxide, are the commonly used materials for transparent conductors. As there are some drawbacks to this class of materials, exploration of alternative materials has been conducted. There is an interest in films of carbon nanomaterials such as, carbon nanotubes and graphene as they exhibit outstanding properties. This article reviews the synthesis and assembly of these films and their post-treatment. These processes determine the film performance and understanding of this platform will be useful for future work to improve the film performance. PMID:28809267

Enhanced photovoltaic performances of graphene/Si solar cells by insertion of a MoS₂ thin film.

PubMed

Tsuboi, Yuka; Wang, Feijiu; Kozawa, Daichi; Funahashi, Kazuma; Mouri, Shinichiro; Miyauchi, Yuhei; Takenobu, Taishi; Matsuda, Kazunari

2015-09-14

Transition-metal dichalcogenides exhibit great potential as active materials in optoelectronic devices because of their characteristic band structure. Here, we demonstrated that the photovoltaic performances of graphene/Si Schottky junction solar cells were significantly improved by inserting a chemical vapor deposition (CVD)-grown, large MoS2 thin-film layer. This layer functions as an effective electron-blocking/hole-transporting layer. We also demonstrated that the photovoltaic properties are enhanced with the increasing number of graphene layers and the decreasing thickness of the MoS2 layer. A high photovoltaic conversion efficiency of 11.1% was achieved with the optimized trilayer-graphene/MoS2/n-Si solar cell.

Electroluminescence of ordered ZnO nanorod array/p-GaN light-emitting diodes with graphene current spreading layer

PubMed Central

2014-01-01

Ordered ZnO nanorod array/p-GaN heterojunction light-emitting diodes (LEDs) have been fabricated by introducing graphene as the current spreading layer, which exhibit improved electroluminescence performance by comparison to the LED using a conventional structure (indium-tin-oxide as the current spreading layer). In addition, by adjusting the diameter of ZnO nanorod array in use, the light emission of the ZnO nanorod array/p-GaN heterojunction LEDs was enhanced further. This work has great potential applications in solid-state lighting, high performance optoelectronic devices, and so on. PACS 78.60.Fi; 85.60.Jb; 78.67.Lt; 81.10.Dn PMID:25489284

Electroluminescence of ordered ZnO nanorod array/p-GaN light-emitting diodes with graphene current spreading layer.

PubMed

Dong, Jing-Jing; Hao, Hui-Ying; Xing, Jie; Fan, Zhen-Jun; Zhang, Zi-Li

2014-01-01

Ordered ZnO nanorod array/p-GaN heterojunction light-emitting diodes (LEDs) have been fabricated by introducing graphene as the current spreading layer, which exhibit improved electroluminescence performance by comparison to the LED using a conventional structure (indium-tin-oxide as the current spreading layer). In addition, by adjusting the diameter of ZnO nanorod array in use, the light emission of the ZnO nanorod array/p-GaN heterojunction LEDs was enhanced further. This work has great potential applications in solid-state lighting, high performance optoelectronic devices, and so on. 78.60.Fi; 85.60.Jb; 78.67.Lt; 81.10.Dn.

An all-solid-state lithium/polyaniline rechargeable cell

NASA Astrophysics Data System (ADS)

Li, Changzhi; Peng, Xinsheng; Zhang, Borong; Wang, Baochen

1992-07-01

The performance of an all-solid-state cell having a lithium negative electrode, a modified polyethylene oxide (PEO)-epoxy resin (ER) electrolyte, and a polyaniline (PAn) positive electrode has been studied using cyclic voltammetry, charge/discharge cycling, and polarization curves at various temperatures. The redox reaction of the PAn electrode at the PAn/modified PEO-ER interface exhibits good reversibility. At 50-80 C, the Li/PEO-ER-LiClO4/PAn cell shows more than 40 charge/discharge cycles, 90 percent charge/discharge efficiency, and 54 W h kg discharge energy density (on PAn weight basis) at 50 micro-A between 2 and 4 V. The polarization performance of the battery improves steadily with increase in temperature.

Measuring pregnancy planning: An assessment of the London Measure of Unplanned Pregnancy among urban, south Indian women

PubMed Central

Rocca, Corinne H.; Krishnan, Suneeta; Barrett, Geraldine; Wilson, Mark

2010-01-01

We evaluated the psychometric properties of the London Measure of Unplanned Pregnancy among Indian women using classical methods and Item Response Modeling. The scale exhibited good internal consistency and internal structure, with overall scores correlating well with each item’s response categories. Items performed similarly for pregnant and non-pregnant women, and scores decreased with increasing parity, providing evidence for validity. Analyses also detected limitations, including infrequent selection of middle response categories and some evidence of differential item functioning by parity. We conclude that the LMUP represents an improvement over existing measures but recommend steps for enhancing scale performance for this cultural context. PMID:21170147

Why credit risk markets are predestined for exhibiting log-periodic power law structures

NASA Astrophysics Data System (ADS)

Wosnitza, Jan Henrik; Leker, Jens

2014-01-01

Recent research has established the existence of log-periodic power law (LPPL) patterns in financial institutions’ credit default swap (CDS) spreads. The main purpose of this paper is to clarify why credit risk markets are predestined for exhibiting LPPL structures. To this end, the credit risk prediction of two variants of logistic regression, i.e. polynomial logistic regression (PLR) and kernel logistic regression (KLR), are firstly compared to the standard logistic regression (SLR). In doing so, the question whether the performances of rating systems based on balance sheet ratios can be improved by nonlinear transformations of the explanatory variables is resolved. Building on the result that nonlinear balance sheet ratio transformations hardly improve the SLR’s predictive power in our case, we secondly compare the classification performance of a multivariate SLR to the discriminative powers of probabilities of default derived from three different capital market data, namely bonds, CDSs, and stocks. Benefiting from the prompt inclusion of relevant information, the capital market data in general and CDSs in particular increasingly outperform the SLR while approaching the time of the credit event. Due to the higher classification performances, it seems plausible for creditors to align their investment decisions with capital market-based default indicators, i.e., to imitate the aggregate opinion of the market participants. Since imitation is considered to be the source of LPPL structures in financial time series, it is highly plausible to scan CDS spread developments for LPPL patterns. By establishing LPPL patterns in governmental CDS spread trajectories of some European crisis countries, the LPPL’s application to credit risk markets is extended. This novel piece of evidence further strengthens the claim that credit risk markets are adequate breeding grounds for LPPL patterns.

In Vivo Neural Recording and Electrochemical Performance of Microelectrode Arrays Modified by Rough-Surfaced AuPt Alloy Nanoparticles with Nanoporosity

PubMed Central

Zhao, Zongya; Gong, Ruxue; Zheng, Liang; Wang, Jue

2016-01-01

In order to reduce the impedance and improve in vivo neural recording performance of our developed Michigan type silicon electrodes, rough-surfaced AuPt alloy nanoparticles with nanoporosity were deposited on gold microelectrode sites through electro-co-deposition of Au-Pt-Cu alloy nanoparticles, followed by chemical dealloying Cu. The AuPt alloy nanoparticles modified gold microelectrode sites were characterized by scanning electron microscopy (SEM), electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV) and in vivo neural recording experiment. The SEM images showed that the prepared AuPt alloy nanoparticles exhibited cauliflower-like shapes and possessed very rough surfaces with many different sizes of pores. Average impedance of rough-surfaced AuPt alloy nanoparticles modified sites was 0.23 MΩ at 1 kHz, which was only 4.7% of that of bare gold microelectrode sites (4.9 MΩ), and corresponding in vitro background noise in the range of 1 Hz to 7500 Hz decreased to 7.5 μVrms from 34.1 μVrms at bare gold microelectrode sites. Spontaneous spike signal recording was used to evaluate in vivo neural recording performance of modified microelectrode sites, and results showed that rough-surfaced AuPt alloy nanoparticles modified microelectrode sites exhibited higher average spike signal-to-noise ratio (SNR) of 4.8 in lateral globus pallidus (GPe) due to lower background noise compared to control microelectrodes. Electro-co-deposition of Au-Pt-Cu alloy nanoparticles combined with chemical dealloying Cu was a convenient way for increasing the effective surface area of microelectrode sites, which could reduce electrode impedance and improve the quality of in vivo spike signal recording. PMID:27827893

Improvement of gas-adsorption performances of Ag-functionalized monolayer MoS2 surfaces: A first-principles study

NASA Astrophysics Data System (ADS)

Song, Jian; Lou, Huan

2018-05-01

Investigations of the adsorptions of representative gases (NO2, NH3, H2S, SO2, CO, and HCHO) on different Ag-functionalized monolayer MoS2 surfaces were performed by first principles methods. The adsorption configurations, adsorption energies, electronic structure properties, and charge transfer were calculated, and the results show that the adsorption activities to gases of monolayer MoS2 are dramatically enhanced by the Ag-modification. The Ag-modified perfect MoS2 (Ag-P) and MoS2 with S-vacancy (Ag-Vs) substrates exhibit a more superior adsorption activity to NO2 than other gases, which is consistent with the experimental reports. The charge transfer processes of different molecules adsorbed on different surfaces exhibit various characteristics, with potential benefits to gas selectivity. For instance, the NO2 and SO2 obtain more electrons from both Ag-P and Ag-Vs substrates but the NH3 and H2S donate more electrons to materials than others. In addition, the CO and HCHO possess totally opposite charge transfer directs on both substrates, respectively. The BS and PDOS calculations show that semiconductor types of gas/Ag-MoS2 systems are more determined by the metal-functionalization of material, and the directs and numbers of charge transfer process between gases and adsorbents can cause the increase or decline of material resistance theoretically, which is helpful to gas detection and distinction. The further analysis indicates suitable co-operation between the gain-lost electron ability of gas and metallicity of featuring metal might adjust the resistivity of complex and contribute to new thought for metal-functionalization. Our works provide new valuable ideas and theoretical foundation for the potential improvement of MoS2-based gas sensor performances, such as sensitivity and selectivity.

SUMMA and Model Mimicry: Understanding Differences Among Land Models

NASA Astrophysics Data System (ADS)

Nijssen, B.; Nearing, G. S.; Ou, G.; Clark, M. P.

2016-12-01

Model inter-comparison and model ensemble experiments suffer from an inability to explain the mechanisms behind differences in model outcomes. We can clearly demonstrate that the models are different, but we cannot necessarily identify the reasons why, because most models exhibit myriad differences in process representations, model parameterizations, model parameters and numerical solution methods. This inability to identify the reasons for differences in model performance hampers our understanding and limits model improvement, because we cannot easily identify the most promising paths forward. We have developed the Structure for Unifying Multiple Modeling Alternatives (SUMMA) to allow for controlled experimentation with model construction, numerical techniques, and parameter values and therefore isolate differences in model outcomes to specific choices during the model development process. In developing SUMMA, we recognized that hydrologic models can be thought of as individual instantiations of a master modeling template that is based on a common set of conservation equations for energy and water. Given this perspective, SUMMA provides a unified approach to hydrologic modeling that integrates different modeling methods into a consistent structure with the ability to instantiate alternative hydrologic models at runtime. Here we employ SUMMA to revisit a previous multi-model experiment and demonstrate its use for understanding differences in model performance. Specifically, we implement SUMMA to mimic the spread of behaviors exhibited by the land models that participated in the Protocol for the Analysis of Land Surface Models (PALS) Land Surface Model Benchmarking Evaluation Project (PLUMBER) and draw conclusions about the relative performance of specific model parameterizations for water and energy fluxes through the soil-vegetation continuum. SUMMA's ability to mimic the spread of model ensembles and the behavior of individual models can be an important tool in focusing model development and improvement efforts.

Poster exhibitions at conferences: are we doing it properly?

PubMed

Beamish, Andrew J; Ansell, James; Foster, Jessica J; Foster, Kathryn A; Egan, Richard J

2015-01-01

Literature exploring the educational value and quality of conference poster presentation is scarce. The aim of this study was to identify and describe the variation in poster exhibitions across a spectrum of conferences attended by trainees. Prospective observational assessment of conference posters was carried out across 7 variables at 4 conferences attended by surgical trainees in 2012. Posters were compared by individual variables and according to overall poster score combining all 7 variables examined. The number of authors listed was also compared. Random samples of consecutively numbered posters were examined at the exhibitions of 4 conferences, which included a UK national medical education conference (Association for the Study of Medical Education), a UK international surgical conference (Association of Surgeons of Great Britain and Ireland), a European oncology conference (European Society of Surgical Oncology), and a North American joint medical and surgical conference (Digestive Diseases Week). Significant variation existed between conferences in posters and their presentation. The proportion of presenters failing to display their posters ranged from 3% to 26% (p < 0.0001). Adherence to size guidelines varied from 89% to 100% (p = 0.002). The inclusion of references ranged from 19% to 82% (p < 0.0001). The presence of a presenting author during the allocated session varied widely from 21% to 86% (p < 0.0001). No significant variation was observed in the proportion of posters that were formatted using aims, methods, results, and conclusion sections (81%-93%; p = 0.513) or in the proportion of posters that were identified as difficult to read (24%-28%; p = 0.919). Association for the Study of Medical Education outperformed each of the other exhibitions overall (p < 0.0001). Posters with greater than the median of 4 authors performed significantly better across all areas (p < 0.0001-0.042) except presenter attendance (p = 0.480). Poster exhibitions varied widely, with room for improvement at all 4 conferences. Lessons can be learned by all conferences from each other to improve presenter engagement with and the educational value of poster exhibitions. Copyright © 2014 Association of Program Directors in Surgery. Published by Elsevier Inc. All rights reserved.

Drugs and the Brain: Learning the impact of methamphetamine abuse on the brain through a virtual brain exhibit in the museum

NASA Astrophysics Data System (ADS)

Cheng, Meng-Tzu; Annetta, Leonard; Folta, Elizabeth; Holmes, Shawn Y.

2011-01-01

Drugs and the Brain: A Serious Game, a prototype museum exhibit, was designed to employ virtual models of the brain into a video game format. It was done to create a fun and engaging way of conveying knowledge and concepts about neuroscience, as well as the impact of methamphetamine abuse on the brain. The purpose of this study is to evaluate this prototype exhibit that promises to educate participants from various age, ethnicity, and gender backgrounds, and to establish a stronger concept of drug abuse prevention among children. A quantitative methodology using the pre- and post-experimental designs was conducted on 175 museum visitors. A series of two-sample paired t-tests and subsequent ANOVAs were performed to examine the difference between pre- and post-tests and to determine if there was a difference in the results in age, gender, ethnicity, and race. Results showed that both the understanding and attitudes of the participants toward the impact of methamphetamine abuse on the brain improved significantly (p < 0.01).

Effect of end-group cross-linking on transport properties of sulfonated poly(phenylene sulfide nitrile)s for proton exchange membranes

NASA Astrophysics Data System (ADS)

Kang, Na Rae; Lee, So Young; Shin, Dong Won; Hwang, Doo Sung; Lee, Kang Hyuck; Cho, Doo Hee; Kim, Ji Hoon; Lee, Young Moo

2016-03-01

A series of end-group cross-linked membranes (Az-XESPSN) were prepared by click reaction to investigate the effects of cross-linking on the morphology and proton transport properties of proton exchange membranes. The morphological transformations resulting from thermal annealing and cross-linking were observed by means of atomic force microscopy (AFM) and transmission electron microscopy (TEM). Compared to the non-cross-linked ESPSN membranes, the Az-XESPSN membranes exhibited lower water uptake and improved mechanical and chemical stabilities. In addition, the Az-XESPSN membranes exhibited higher proton conductivities (0.018-0.028 S cm-1) compared to those of the ESPSN membranes (0.0044-0.0053 S cm-1) and Nafion 212 (0.0061 S cm-1), particularly in conditions of elevated temperature (120 °C) and low relative humidity (35%). Such enhancements can be attributed to a synergistic effect of well-defined hydrophilic ionic clusters and triazole groups that function as proton carriers under anhydrous conditions. Furthermore, the Az-XESPSN membranes exhibited significantly enhanced single cell performance and long-term stability compared to those of ESPSN membranes.

Development of Advanced 9Cr Ferritic-Martensitic Steels and Austenitic Stainless Steels for Sodium-Cooled Fast Reactor

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sham, Sam; Tan, Lizhen; Yamamoto, Yukinori

2013-01-01

Ferritic-martensitic (FM) steel Grade 92, with or without thermomechanical treatment (TMT), and austenitic stainless steels HT-UPS (high-temperature ultrafine precipitate strengthening) and NF709 were selected as potential candidate structural materials in the U.S. Sodium-cooled Fast Reactor (SFR) program. The objective is to develop advanced steels with improved properties as compared with reference materials such as Grade 91 and Type 316H steels that are currently in nuclear design codes. Composition modification and/or processing optimization (e.g., TMT and cold-work) were performed to improve properties such as resistance to thermal aging, creep, creep-fatigue, fracture, and sodium corrosion. Testings to characterize these properties for themore » advanced steels were conducted by the Idaho National Laboratory, the Argonne National Laboratory and the Oak Ridge National Laboratory under the U.S. SFR program. This paper focuses on the resistance to thermal aging and creep of the advanced steels. The advanced steels exhibited up to two orders of magnitude increase in creep life compared to the reference materials. Preliminary results on the weldment performance of the advanced steels are also presented. The superior performance of the advanced steels would improve reactor design flexibility, safety margins and economics.« less

Comparison of parameter-adapted segmentation methods for fluorescence micrographs.

PubMed

Held, Christian; Palmisano, Ralf; Häberle, Lothar; Hensel, Michael; Wittenberg, Thomas

2011-11-01

Interpreting images from fluorescence microscopy is often a time-consuming task with poor reproducibility. Various image processing routines that can help investigators evaluate the images are therefore useful. The critical aspect for a reliable automatic image analysis system is a robust segmentation algorithm that can perform accurate segmentation for different cell types. In this study, several image segmentation methods were therefore compared and evaluated in order to identify the most appropriate segmentation schemes that are usable with little new parameterization and robustly with different types of fluorescence-stained cells for various biological and biomedical tasks. The study investigated, compared, and enhanced four different methods for segmentation of cultured epithelial cells. The maximum-intensity linking (MIL) method, an improved MIL, a watershed method, and an improved watershed method based on morphological reconstruction were used. Three manually annotated datasets consisting of 261, 817, and 1,333 HeLa or L929 cells were used to compare the different algorithms. The comparisons and evaluations showed that the segmentation performance of methods based on the watershed transform was significantly superior to the performance of the MIL method. The results also indicate that using morphological opening by reconstruction can improve the segmentation of cells stained with a marker that exhibits the dotted surface of cells. Copyright © 2011 International Society for Advancement of Cytometry.

High Intensity Interval Training Improves Physical Performance and Frailty in Aged Mice.

PubMed

Seldeen, Kenneth Ladd; Lasky, Ginger; Leiker, Merced Marie; Pang, Manhui; Personius, Kirkwood Ely; Troen, Bruce Robert

2018-03-14

Sarcopenia and frailty are highly prevalent in older individuals, increasing the risk of disability and loss of independence. High intensity interval training (HIIT) may provide a robust intervention for both sarcopenia and frailty by achieving both strength and endurance benefits with lower time commitments than other exercise regimens. To better understand the impacts of HIIT during aging, we compared 24-month-old C57BL/6J sedentary mice with those that were administered 10-minute uphill treadmill HIIT sessions three times per week over 16 weeks. Baseline and end point assessments included body composition, physical performance, and frailty based on criteria from the Fried physical frailty scale. HIIT-trained mice demonstrated dramatic improvement in grip strength (HIIT 10.9% vs -3.9% in sedentary mice), treadmill endurance (32.6% vs -2.0%), and gait speed (107.0% vs 39.0%). Muscles from HIIT mice also exhibited greater mass, larger fiber size, and an increase in mitochondrial biomass. Furthermore, HIIT exercise led to a dramatic reduction in frailty scores in five of six mice that were frail or prefrail at baseline, with four ultimately becoming nonfrail. The uphill treadmill HIIT exercise sessions were well tolerated by aged mice and led to performance gains, improvement in underlying muscle physiology, and reduction in frailty.

Opening the band gap of graphene through silicon doping for the improved performance of graphene/GaAs heterojunction solar cells.

PubMed

Zhang, S J; Lin, S S; Li, X Q; Liu, X Y; Wu, H A; Xu, W L; Wang, P; Wu, Z Q; Zhong, H K; Xu, Z J

2016-01-07

Graphene has attracted increasing interest due to its remarkable properties. However, the zero band gap of monolayered graphene limits it's further electronic and optoelectronic applications. Herein, we have synthesized monolayered silicon-doped graphene (SiG) with large surface area using a chemical vapor deposition method. Raman and X-ray photoelectron spectroscopy measurements demonstrate that the silicon atoms are doped into graphene lattice at a doping level of 2.7-4.5 at%. Electrical measurements based on a field effect transistor indicate that the band gap of graphene has been opened via silicon doping without a clear degradation in carrier mobility, and the work function of SiG, deduced from ultraviolet photoelectron spectroscopy, was 0.13-0.25 eV larger than that of graphene. Moreover, when compared with the graphene/GaAs heterostructure, SiG/GaAs exhibits an enhanced performance. The performance of 3.4% silicon doped SiG/GaAs solar cell has been improved by 33.7% on average, which was attributed to the increased barrier height and improved interface quality. Our results suggest that silicon doping can effectively engineer the band gap of monolayered graphene and SiG has great potential in optoelectronic device applications.

Ionic Liquid Confined in Mesoporous Polymer Membrane with Improved Stability for CO2/N2 Separation

PubMed Central

Tan, Ming; Lu, Jingting; Zhang, Yang; Jiang, Heqing

2017-01-01

Supported ionic liquid membranes (SILMs) have a promising prospect of application in flue gas separation, owing to its high permeability and selectivity of CO2. However, existing SILMs have the disadvantage of poor stability due to the loss of ionic liquid from the large pores of the macroporous support. In this study, a novel SILM with high stability was developed by confining ionic liquid in a mesoporous polymer membrane. First, a mesoporous polymer membrane derived from a soluble, low-molecular-weight phenolic resin precursor was deposited on a porous Al2O3 support, and then 1-ethyl-3-methylimidazolium tetrafluoroborate ([emim][BF4]) was immobilized inside mesopores of phenolic resin, forming the SILM under vacuum. Effects of trans-membrane pressure difference on the SILM separation performance were investigated by measuring the permeances of CO2 and N2. The SILM exhibits a high ideal CO2/N2 selectivity of 40, and an actual selectivity of approximately 25 in a mixed gas (50% CO2 and 50% N2) at a trans-membrane pressure difference of 2.5 bar. Compared to [emim][BF4] supported by polyethersulfone membrane with a pore size of around 0.45 μm, the [emim][BF4] confined in a mesoporous polymer membrane exhibits an improved stability, and its separation performance remained stable for 40 h under a trans-membrane pressure difference of 1.5 bar in a mixed gas before the measurement was intentionally stopped. PMID:28961187

Large Scale Application of Vibration Sensors for Fan Monitoring at Commercial Layer Hen Houses

PubMed Central

Chen, Yan; Ni, Ji-Qin; Diehl, Claude A.; Heber, Albert J.; Bogan, Bill W.; Chai, Li-Long

2010-01-01

Continuously monitoring the operation of each individual fan can significantly improve the measurement quality of aerial pollutant emissions from animal buildings that have a large number of fans. To monitor the fan operation by detecting the fan vibration is a relatively new technique. A low-cost electronic vibration sensor was developed and commercialized. However, its large scale application has not yet been evaluated. This paper presents long-term performance results of this vibration sensor at two large commercial layer houses. Vibration sensors were installed on 164 fans of 130 cm diameter to continuously monitor the fan on/off status for two years. The performance of the vibration sensors was compared with fan rotational speed (FRS) sensors. The vibration sensors exhibited quick response and high sensitivity to fan operations and therefore satisfied the general requirements of air quality research. The study proved that detecting fan vibration was an effective method to monitor the on/off status of a large number of single-speed fans. The vibration sensor itself was $2 more expensive than a magnetic proximity FRS sensor but the overall cost including installation and data acquisition hardware was $77 less expensive than the FRS sensor. A total of nine vibration sensors failed during the study and the failure rate was related to the batches of product. A few sensors also exhibited unsteady sensitivity. As a new product, the quality of the sensor should be improved to make it more reliable and acceptable. PMID:22163544