443 research outputs found
Structural and electrical properties of ceramic Li-ion conductors based on LiAlTi(PO)-LiF
The work presents the investigations of Li1.3Al0.3Ti1.7(PO4)3-xLiF Li-ion
conducting ceramics with 0 < x < 0.3 by means of X-ray diffractometry (XRD),
7Li, 19F, 27Al and 31P Magic Angle Spinning Nuclear Magnetic Resonance (MAS
NMR) spectroscopy, thermogravimetry (TG), scanning electron microscopy (SEM),
impedance spectroscopy (IS) and density method. It has been shown that the
total ionic conductivity of both as-prepared and ceramic Li1.3Al0.3Ti1.7(PO4)3
is low due to a grain boundary phase exhibiting high electrical resistance.
This phase consists mainly of berlinite crystalline phase as well as some
amorphous phase containing Al3+ ions. The electrically resistant phases of the
grain boundary decompose during sintering with LiF additive. The processes
leading to microstructure changes and their effect on the ionic properties of
the materials are discussed in the frame of the brick layer model (BLM). The
highest total ionic conductivity at room temperature was measured for
LATP-0.1LiF ceramic sintered at 800{\deg}C and was equal to {\sigma}tot = 1.1 x
10-4 Scm-1
Impact of LiBSO glass additive on the structure and electrical properties of the LATP-based ceramics
The existing solid electrolytes for lithium ion batteries suffer from low
total ionic conductivity, which restricts its usefulness for the lithium-ion
battery technology. Among them, the NASICON-based materials, such as
Li1.3Al0.3Ti1.7(PO4)3 (LATP) exhibit low total ionic conductivity due to highly
resistant grain boundary phase. One of the possible approaches to efficiently
enhance their total ionic conductivity is the formation of a composite
material. Herein, the Li2.9B0.9S0.1O3.1 glass, called LBSO hereafter, was
chosen as an additive material to improve the ionic properties of the ceramic
Li1.3Al0.3Ti1.7(PO4)3 base material. The properties of this
Li1.3Al0.3Ti1.7(PO4)3-xLi2.9B0.9S0.1O3.1 (0 < x < 0.3) system have been studied
by means of high temperature X-ray diffractometry (HTXRD), 7Li, 11B, 27Al and
31P magic angle spinning nuclear magnetic resonance spectroscopy (MAS NMR),
thermogravimetry (TG), scanning electron microscopy (SEM), impedance
spectroscopy (IS) and density methods. We show here that the introduction of
the foreign LBSO phase enhances their electric properties. This study reveals
several interesting correlations between the apparent density, the
microstructure, the composition, the sintering temperature and the ionic
conductivity. Moreover, the electrical properties of the composites will be
discussed in the terms of the brick-layer model (BLM). The highest value of
{\sigma}tot = 1.5 x 10-4 Scm-1 has been obtained for LATP-0.1LBSO material
sintered at 800{\deg}C
Properties of LiMnBO3 glasses and nanostructured glass-ceramics
Polycrystalline LiMnBO3 is a promising cathode material for Li-ion batteries.
In this work, we investigated the thermal, structural and electrical properties
of glassy and nanocrystallized materials having the same chemical composition.
The original glass was obtained via a standard meltquenching method. SEM and
7Li solid-state NMR indicate that it contains a mixture of two distinct glassy
phases. The results suggest that the electrical conductivity of the glass is
dominated by the ionic one. The dc conductivity of initial glass was estimated
to be in the order of 10-18 S.cm-1 at room temperature. The thermal
nanocrystallization of the glass produces a nanostructured glass-ceramics
containing MnBO3 and LiMnBO3 phases. The electric conductivity of this
glass-ceramics is increased by 6 orders of magnitude, compared to the starting
material at room temperature. Compared to other manganese and borate containing
glasses reported in the literature, the conductivity of the nanostructured
glass ceramics is higher than that of the previously reported glassy materials.
Such improved conductivity stems from the facilitated electronic transport
along the grain boundaries
Integrating Agriculture and Ecosystems to Find Suitable Adaptations to Climate Change
Climate change is altering agricultural production and ecosystems around the world. Future projections indicate that additional change is expected in the coming decades, forcing individuals and communities to respond and adapt. Current research efforts typically examine climate change effects and possible adaptations but fail to integrate agriculture and ecosystems. This failure to jointly consider these systems and associated externalities may underestimate climate change impacts or cause adaptation implementation surprises, such as causing adaptation status of some groups or ecosystems to be worsened. This work describes and motivates reasons why ecosystems and agriculture adaptation require an integrated analytical approach. Synthesis of current literature and examples from Texas are used to explain concepts and current challenges. Texas is chosen because of its high agricultural output that is produced in close interrelationship with the surrounding semi-arid ecosystem. We conclude that future effect and adaptation analyses would be wise to jointly consider ecosystems and agriculture. Existing paradigms and useful methodology can be transplanted from the sustainable agriculture and ecosystem service literature to explore alternatives for climate adaptation and incentivization of private agriculturalists and consumers. Researchers are encouraged to adopt integrated modeling as a means to avoid implementation challenges and surprises when formulating and implementing adaptation
Dose-dependent effects of Allopurinol on human foreskin fibroblast cell and human umbilical vein endothelial cell under hypoxia
Allopurinol, an inhibitor of xanthine oxidase, has been used in clinical trials of patients with cardiovascular and chronic kidney disease. These are two pathologies with extensive links to hypoxia and activation of the transcription factor hypoxia inducible factor (HIF) family. Here we analysed the effects of allopurinol treatment in two different cellular models, and their response to hypoxia. We explored the dose-dependent effect of allopurinol on Human Foreskin Fibroblasts (HFF) and Human Umbilical Vein Endothelial Cells (HUVEC) under hypoxia and normoxia. Under normoxia and hypoxia, high dose allopurinol reduced the accumulation of HIF-1α protein in HFF and HUVEC cells. Allopurinol had only marginal effects on HIF-1α mRNA level in both cellular systems. Interestingly, allopurinol effects over the HIF system were independent of prolyl-hydroxylase activity. Finally, allopurinol treatment reduced angiogenesis traits in HUVEC cells in an in vitro model. Taken together these results indicate that high doses of allopurinol inhibits the HIF system and pro-angiogenic traits in cells
Production, characterization, and antigen specificity of recombinant 62-71-3, a candidate monoclonal antibody for rabies prophylaxis in humans
Rabies kills many people throughout the developing world every year. The murine monoclonal antibody (mAb) 62-71-3 was recently identified for its potential application in rabies postexposure prophylaxis (PEP). The purpose here was to establish a plant-based production system for a chimeric mouse-human version of mAb 62-71-3, to characterize the recombinant antibody and investigate at a molecular level its interaction with rabies virus glycoprotein. Chimeric 62-71-3 was successfully expressed in Nicotiana benthamiana. Glycosylation was analyzed by mass spectroscopy; functionality was confirmed by antigen ELISA, as well as rabies and pseudotype virus neutralization. Epitope characterization was performed using pseudotype virus expressing mutagenized rabies glycoproteins. Purified mAb demonstrated potent viral neutralization at 500 IU/mg. A critical role for antigenic site I of the glycoprotein, as well as for two specific amino acid residues (K226 and G229) within site I, was identified with regard to mAb 62-71-3 neutralization. Pseudotype viruses expressing glycoprotein from lyssaviruses known not to be neutralized by this antibody were the controls. The results provide the molecular rationale for developing 62-71-3 mAb for rabies PEP; they also establish the basis for developing an inexpensive plant-based antibody product to benefit low-income families in developing countries.—Both, L., van Dolleweerd, C., Wright, E., Banyard, A. C., Bulmer-Thomas, B., Selden, D., Altmann, F., Fooks, A. R., Ma, J. K.-C. Production, characterization, and antigen specificity of recombinant 62-71-3, a candidate monoclonal antibody for rabies prophylaxis in humans
Wearable Haptic Devices for Gait Re-education by Rhythmic Haptic Cueing
This research explores the development and evaluation of wearable haptic devices for gait sensing and rhythmic haptic cueing in the context of gait re-education for people with neurological and neurodegenerative conditions. Many people with long-term neurological and neurodegenerative conditions such as Stroke, Brain Injury, Multiple Sclerosis or Parkinson’s disease suffer from impaired walking gait pattern. Gait improvement can lead to better fluidity in walking, improved health outcomes, greater independence, and enhanced quality of life. Existing lab-based studies with wearable devices have shown that rhythmic haptic cueing can cause immediate improvements to gait features such as temporal symmetry, stride length, and walking speed. However, current wearable systems are unsuitable for self-managed use for in-the-wild applications with people having such conditions. This work aims to investigate the research question of how wearable haptic devices can help in long-term gait re-education using rhythmic haptic cueing. A longitudinal pilot study has been conducted with a brain trauma survivor, providing rhythmic haptic cueing using a wearable haptic device as a therapeutic intervention for a two-week period. Preliminary results comparing pre and post-intervention gait measurements have shown improvements in walking speed, temporal asymmetry, and stride length. The pilot study has raised an array of issues that require further study. This work aims to develop and evaluate prototype systems through an iterative design process to make possible the self-managed use of such devices in-the-wild. These systems will directly provide therapeutic intervention for gait re-education, offer enhanced information for therapists, remotely monitor dosage adherence and inform treatment and prognoses over the long-term. This research will evaluate the use of technology from the perspective of multiple stakeholders, including clinicians, carers and patients. This work has the potential to impact clinical practice nationwide and worldwide in neuro-physiotherapy
The Effects of Alfven Waves and Radiation Pressure in Dust Winds of Late-type Stars
In the present study, we analyze the effects of a flux of Alfven waves acting
together with radiation pressure on grains as an acceleration mechanism of the
wind of late-type stars. In the wind model we simulate the presence of grains
through a strong damping of the waves, we used a non-isothermal profile for
temperature, coherent with grain formation theories. We examine the changes in
the velocity profile of the wind and we show that if the grains are created in
the region 1.1 < r/r_0 < 2.0 their presence will affect the mass loss and
terminal velocity. The model is applied to a K5 supergiant star and for
Betelgeuse (alpha Ori).Comment: 6 pages, 3 figures, accepted in ApJ (Sep, 2002
Global Geometric Affinity for Revealing High Fidelity Protein Interaction Network
Protein-protein interaction (PPI) network analysis presents an essential role in understanding the functional relationship among proteins in a living biological system. Despite the success of current approaches for understanding the PPI network, the large fraction of missing and spurious PPIs and a low coverage of complete PPI network are the sources of major concern. In this paper, based on the diffusion process, we propose a new concept of global geometric affinity and an accompanying computational scheme to filter the uncertain PPIs, namely, reduce the spurious PPIs and recover the missing PPIs in the network. The main concept defines a diffusion process in which all proteins simultaneously participate to define a similarity metric (global geometric affinity (GGA)) to robustly reflect the internal connectivity among proteins. The robustness of the GGA is attributed to propagating the local connectivity to a global representation of similarity among proteins in a diffusion process. The propagation process is extremely fast as only simple matrix products are required in this computation process and thus our method is geared toward applications in high-throughput PPI networks. Furthermore, we proposed two new approaches that determine the optimal geometric scale of the PPI network and the optimal threshold for assigning the PPI from the GGA matrix. Our approach is tested with three protein-protein interaction networks and performs well with significant random noises of deletions and insertions in true PPIs. Our approach has the potential to benefit biological experiments, to better characterize network data sets, and to drive new discoveries
Recent Advances in Graph Partitioning
We survey recent trends in practical algorithms for balanced graph
partitioning together with applications and future research directions
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