862 research outputs found
Extremal problems for disjoint graphs
For a simple graph , let and
be the set of graphs with the maximum number of edges and the set of graphs
with the maximum spectral radius in an -vertex graph without any copy of the
graph , respectively. Let be a graph with
. In this paper, we show that
for sufficiently large .
This generalizes a result of Wang, Kang and Xue [J. Comb. Theory, Ser. B,
159(2023) 20-41]. We also determine the extremal graphs of in term of the
extremal graphs of .Comment: 23 pages. arXiv admin note: text overlap with arXiv:2306.1674
Spectral extremal graphs for edge blow-up of star forests
The edge blow-up of a graph , denoted by , is obtained by
replacing each edge of with a clique of order , where the new vertices
of the cliques are all distinct. Yuan [J. Comb. Theory, Ser. B, 152 (2022)
379-398] determined the range of the Tur\'{a}n numbers for edge blow-up of all
bipartite graphs and the exact Tur\'{a}n numbers for edge blow-up of all
non-bipartite graphs. In this paper we prove that the graphs with the maximum
spectral radius in an -vertex graph without any copy of edge blow-up of star
forests are the extremal graphs for edge blow-up of star forests when is
sufficiently large.Comment: 22. arXiv admin note: text overlap with arXiv:2208.0655
Fuzzy logic damping controller for FACTS devices in interconnected power systems
Fuzzy controllers are designed for flexible AC transmission systems (FACTS) in interconnected power systems. Two typical FACTS devices, a static synchronous compensator (STATCOM) and a unified power flow controller (UPFC), are used as examples to show that FACTS devices with well-designed fuzzy controllers can significantly improve the dynamic behavior of interconnected power systems.published_or_final_versio
Oxygen molecule dissociation on carbon nanostructures with different types of nitrogen doping
Energy barrier of oxygen molecule dissociation on carbon nanotube or graphene
with different types of nitrogen doping is investigated using density
functional theory. The results show that the energy barriers can be reduced
efficiently by all types of nitrogen doping in both carbon nanotubes and
graphene. Graphite-like nitrogen and Stone-Wales defect nitrogen decrease the
energy barrier more efficiently than pyridine-like nitrogen, and a dissociation
barrier lower than 0.2 eV can be obtained. Higher nitrogen concentration
reduces the energy barrier much more efficiently for graphite-like nitrogen.
These observations are closely related to partial occupation of {\pi}* orbitals
and change of work functions. Our results thus provide useful insights into the
oxygen reduction reactions.Comment: Accepted by Nanoscal
Forskolin reduces fat accumulation in Nile tilapia (Oreochromis niloticus) through stimulating lipolysis and beta-oxidation
© 2018 Published by Elsevier Ltd. This manuscript version is made available under the CC-BY-NC-ND 4.0 license: http://creativecommons.org/licenses/by-nc-nd/4.0/
This author accepted manuscript is made available following 12 month embargo from date of publication (December 2018) in accordance with the publisher’s archiving policyHigh fat diets are commonly used in aquaculture to reduce feed cost in Nile tilapia, but impair its lipid homeostasis. This study evaluated the role of forskolin on reducing fat accumulation in Nile tilapia (Oreochromis niloticus) by using in vitro and in vivo experiments. The use of 50 μM forskolin in vitro increased free fatty acid and glycerol release, but decreased triglyceride in adipocytes and hepatocytes. The adipose triglyceride lipase (ATGL), protein kinase cAMP-dependent type I regulatory subunit alpha (PKAR I) and other genes related to β-oxidation (peroxisome proliferator activated receptor alpha, PPARα and carnitine O-palmitoyltransferase 1, CPT1) were significantly up-regulated. After feeding a high-fat diet for six weeks, O. niloticus were fed with 0 (control), 0.5 and 1.5 mg/kg forskolin for two weeks to determine whether forskolin could reduce fat accumulation in vivo. Fish fed the two levels of forskolin decreased significantly the hepatosomatic and mesenteric fat indices. The total lipid in the whole fish and liver together with the serum glycerol content were lower in fish fed on forskolin than in the control. The fish fed on forskolin diets exhibited smaller areas of lipid droplets in adipose and liver tissues. Lipolysis related genes (ATGL, hormone-sensitive lipase, HSL; monoacylglycerol lipase, MGL; and protein kinase cAMP-activated catalytic subunit, PKAC) and β-oxidation genes (PPARα; fatty acid binding protein 1, FABP1; and CPT1) in the adipose were up-regulated. Similarly, in the liver lipolysis genes such as ATGL and PKAR I and β-oxidation genes (PPARα, FABP1, CPT1 and acyl-CoA oxidase, ACO) showed an increasing trend with the increase of forskolin doses. This study indicates that forskolin can reduce fat accumulation in the adipose and liver by stimulating lipolysis and β-oxidation in O. niloticus
Multi-Band Exotic Superconductivity in the New Superconductor Bi4O4S3
Resistivity, Hall effect and magnetization have been investigated on the new
superconductor Bi4O4S3. A weak insulating behavior has been induced in the
normal state when the superconductivity is suppressed. Hall effect measurements
illustrate clearly a multiband feature dominated by electron charge carriers,
which is further supported by the magnetoresistance data. Interestingly, a kink
appears on the temperature dependence of resistivity at about 4 K at all high
magnetic fields when the bulk superconductivity is completely suppressed. This
kink can be well traced back to the upper critical field Hc2(T) in the low
field region, and is explained as the possible evidence of residual Cooper
pairs on the one dimensional chains.Comment: 5 pages, 5 figure
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