684 research outputs found
Metal-organic frameworks-derived titanium dioxide-carbon nanocomposite for supercapacitor applications
The pyrolysis of metal-organic frameworks (MOFs) to derive porous nanocarbons and metal oxides has attracted scientific attention due to the advantageous properties of the final products (eg, high surface areas). In the present research, MIL-125 (MIL = Materials of Institute Lavoisier, a Ti-based MOF) has been subjected to a single-step pyrolysis treatment in argon atmosphere. The combination of uniformly linked titanium metal cluster and oxygen-enriched organic linker has acted as a template to yield a titanium dioxide (TiO2)-carbon nanocomposite. The TiO2 nanoparticles infused in carbon skeleton structure (TiO2/C) has been investigated as an electrode material for supercapacitor applications. TiO2/C electrodes have delivered an excellent electrochemical performance, for example, in terms of charging-discharging efficiency. Two equally weighed TiO2/C electrodes have been used to assemble a solid-state symmetrical supercapacitor (SC) device, containing a gel electrolyte (poly vinyl alcohol in 1 M H2SO4). The above device has delivered a high value of energy density (43.5 Wh/kg) and an excellent power output of 0.865 kW/kg. The symmetrical SC could retain almost 95% of its initial capacitance even after 2000 charging-discharging cycles. The electrochemical performance of the TiO2/C SC was better than most MOF-based SCs reported previously. Such performance is attributed to the synergistic combination of electrically conducting MOF-derived carbon and redox active TiO2 nanocrystals with a large specific surface area
Contrast enhancement behavior of hydrogen silsesquioxane in a salty developer
The authors investigated a contrast enhancement behavior of hydrogen silsesquioxane (HSQ) in a salty development system (NaOH/NaCl). Time-resolved analysis of contrast curves and line-grating patterns were carried out to investigate the unique properties of a salty development process. In NaOH developer without salt, the development process was saturated beyond a certain development time. On the other hand, the addition of salt enabled a continuous development, which was not observed in the pure NaOH development. The continuous thinning process enhances the contrast of HSQ in the salty developer, which allows a fast collapsing behavior in HSQ line-grating patterns. During development process, salt seems to have the role of modifying HSQ by breaking network bonds preferentially, leading to a continuous development rate
Penetration Pathways Induced by Low-Frequency Sonophoresis with Physical and Chemical Enhancers: Iron Oxide Nanoparticles versus Lanthanum Nitrates
Low-frequency sonophoresis (LFS) has been shown to disrupt the structure of stratum corneum (SC) lipid bilayers and enhance SC permeability. In this study, we examined the penetration pathway of lanthanum nitrate (LaNO3) tracer in viable epidermis after combined treatment of LFS and tape stripping (TS), as a physical enhancer, or oleic acid (OA) application, as a chemical enhancer, using transmission electron microscopy (TEM). As a positive control, we visualized the passive diffusion pathway of LaNO3 and iron oxide (Fe3O4) nanoparticles after the incision of hairless mouse skin. Next, we applied LFS immediately after TS or OA application and visualized the penetration pathway of LaNO3. Each treatment showed restricted penetration to the SC–stratum granulosum (SG) interface or upper SG layer. However, the additional application of LFS induced diffuse intracellular distribution of LaNO3 throughout the viable epidermis. Quantitative analysis also revealed that combined treatment significantly increases LaNO3 penetration into viable epidermis when compared with each treatment. Our ultrastructural findings show the synergistic effect of LFS and TS or OA application on transdermal drug delivery. We also found that this combined treatment enhances the penetration of LaNO3 through the viable epidermis through an intracellular pathway
The role of the Cucumber mosaic virus 2b protein in viral movement and symptom induction
The Cucumber mosaic virus (CMV) 2b protein is a counter-defense factor and symptom determinant. Conserved domains in the 2b protein sequence were mutated in the 2b gene of strain Fny-CMV. The effects of these mutations were assessed by infection of Nicotiana tabacum, N. benthamiana, and Arabidopsis thaliana (ecotype Col-0) with mutant viruses and by expression of mutant 2b transgenes in A. thaliana. We confirmed that two nuclear localization signals were required for symptom induction and found that the N-terminal domain was essential for symptom induction. The C-terminal domain and two serine residues within a putative phosphorylation domain modulated symptom severity. Further infection studies were conducted using Fny-CMVΔ2b, a mutant that cannot express the 2b protein and that induces no symptoms in N. tabacum, N. benthamiana, or A. thaliana ecotype Col-0. Surprisingly, in plants of A. thaliana ecotype C24, Fny-CMVΔ2b induced severe symptoms similar to those induced by the wild-type virus. However, C24 plants infected with the mutant virus recovered from disease while those infected with the wild-type virus did not. Expression of 2b transgenes from either Fny-CMV or from LS-CMV (a mild strain) in Col-0 plants enhanced systemic movement of Fny-CMVΔ2b and permitted symptom induction by Fny-CMVΔ2b. Taken together, the results indicate that the 2b protein itself is an important symptom determinant in certain hosts. However, they also suggest that the protein may somehow synergize symptom induction by other CMV-encoded factors
Towards 5D Grand Unification without SUSY Flavor Problem
We consider the renormalization group approach to the SUSY flavor problem in
the supersymmetric SU(5) model with one extra dimension. In higher dimensional
SUSY gauge theories, it has been recently shown that power corrections due to
the Kaluza-Klein states of gauge fields run the soft masses generated at the
orbifold fixed point to flavor conserving values in the infra-red limit. In
models with GUT breaking at the brane where the GUT scale can be larger than
the compactification scale, we show that the addition of a bulk Higgs
multiplet, which is necessary for the successful unification, is compatible
with the flavor universality achieved at the compactification scale.Comment: JHEP style file of 35 pages with 3 figures, Version to appear in JHE
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GABA-modulating bacteria of the human gut microbiota.
The gut microbiota affects many important host functions, including the immune response and the nervous system1. However, while substantial progress has been made in growing diverse microorganisms of the microbiota2, 23-65% of species residing in the human gut remain uncultured3,4, which is an obstacle for understanding their biological roles. A likely reason for this unculturability is the absence in artificial media of key growth factors that are provided by neighbouring bacteria in situ5,6. In the present study, we used co-culture to isolate KLE1738, which required the presence of Bacteroides fragilis to grow. Bioassay-driven purification of B. fragilis supernatant led to the isolation of the growth factor, which, surprisingly, is the major inhibitory neurotransmitter GABA (γ-aminobutyric acid). GABA was the only tested nutrient that supported the growth of KLE1738, and a genome analysis supported a GABA-dependent metabolism mechanism. Using growth of KLE1738 as an indicator, we isolated a variety of GABA-producing bacteria, and found that Bacteroides ssp. produced large quantities of GABA. Genome-based metabolic modelling of the human gut microbiota revealed multiple genera with the predicted capability to produce or consume GABA. A transcriptome analysis of human stool samples from healthy individuals showed that GABA-producing pathways are actively expressed by Bacteroides, Parabacteroides and Escherichia species. By coupling 16S ribosmal RNA sequencing with functional magentic resonance imaging in patients with major depressive disorder, a disease associated with an altered GABA-mediated response, we found that the relative abundance levels of faecal Bacteroides are negatively correlated with brain signatures associated with depression
A phenomenological description on an incoherent Fermi liquid near optimal doping in high T_{c} cuprates
Marginal Fermi-liquid physics near optimal doping in high T_{c} cuprates has
been explained within two competing scenarios such as the spin-fluctuation
theory based on an itinerant picture and the slave-particle approach based on a
localized picture. In this study we propose an alternative scenario for the
anomalous transport within the context of the slave-particle approach. Although
the marginal Fermi-liquid phenomenology was interpreted previously within
deconfinement of the compact gauge theory, referred to as the strange metal
phase, we start from confinement, introducing the Polyakov-loop parameter into
an SU(2) gauge theory formulation of the t-J model. The Polyakov-loop parameter
gives rise to incoherent electrons through the confinement of spinons and
holons, which result from huge imaginary parts of self-energy corrections for
spinons and holons. This confinement scenario serves a novel mechanism for the
marginal Fermi-liquid transport in the respect that the scattering source has
nothing to do with symmetry breaking. Furthermore, the incoherent Fermi-liquid
state evolves into the Fermi liquid phase through crossover instead of an
artificial second-order transition as temperature is lowered, where the
crossover phenomenon does not result from the Anderson-Higgs mechanism but
originate from an energy scale in the holon sector. We fit an experimental data
for the electrical resistivity around the optimal doping and find a reasonable
match between our theory and the experiment.Comment: 15 pages. 5 figure. Title has been changed. Final version publishec
in J. Phys.: Condens. Matter 23 (2011) 49570
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