846 research outputs found
Synthetic turbulence generator for the wall-modeled LES lattice Boltzmann method
The synthetic turbulence generator (STG) lies at the interface of the
Reynolds averaged Navier-Stokes (RANS) simulation and large eddy simulation
(LES). This paper presents a STG for the multiple-relaxation-time(MRT) lattice
Boltzmann method(LBM) framework at high friction Reynolds numbers, with
consideration of near wall modeling. The Reichardt wall law, in combination
with a force-based method, is used to model the near wall field. The STG
wall-modeled(STG-WM) LES results are compared with turbulent channel flow
simulations at at different resolutions. The results
demonstrate good agreement with DNS, with the adaptation length of 6 to 8
boundary layer thickness. This method has a wide range of potentials for hybrid
RANS/LES-LBM related applications at high friction Reynolds numbers
Effect of Diet Supplemented With Rapeseed Meal or Hydrolysable Tannins on the Growth, Nutrition, and Intestinal Microbiota in Grass Carp (Ctenopharyngodon idellus)
Grass carp (Ctenopharyngodon idellus; n = 320) were received four different diets for 56 days. The experimental diets were: fishmeal (FM) containing 10% fishmeal (without rapeseed meal), and rapeseed meal (RM) containing 50% rapeseed meal (without fishmeal), and two semi-purified diets either without (T0) or with 1.25% (T1) supplemental hydrolysable tannin. The approximate content of tannin in the RM diet was 1.31%, which was close to that of T1, while the tannin content of FM was close to that of T0. The weight gain rate of grass carp of the RM group was significantly lower than that of the FM group, while the feeding conversion ratio and the feeding rate were significantly higher in the T1 group than in T0. The muscle lipid content was significantly lower in RM than in FM, while T1 was lower than T0. Intestinal activities of trypsin and α-amylase were significantly higher in T1 and RM groups compared with the other treatments. The hepatic activities of aspartate aminotransferase and alanine aminotransferase were lower in T1 and RM groups compared with the other treatments, while hepatic glycogen, and malonaldehyde were significantly higher in T1 and RM groups. In serum, the total protein and globulin contents were significantly higher in T1 and RM groups, while albumin was significantly lower in the RM group compared to the FM group. High-throughput sequencing showed that Proteobacteria, Firmicutes, and Actinobacteria were the dominant bacterial phyla among groups. The intestinal microbial diversity was higher in T1 and RM. Redundancy analysis showed that tannin, rapeseed meal, and intestinal trypsin activity were positively or negatively correlated with the relative abundance of several different intestinal microbiota at phylum and/or genus levels. The results indicated that 1.25% tannin could not be the main reason for the poor growth of grass carp of the RM group; however, the protein metabolism was disturbed, the absorption of carbohydrate was improved, and the accumulation of lipid had decreased. Furthermore, tannin and rapeseed meal supplementations modulated the intestinal microbiota, and may sequentially regulate the intestinal function by fermenting dietary nutrition, producing digestive enzymes, and modulating probiotics
Blasting vibration on deep shaft ingate rock damage and its control measures
Traditional control of ingate surrounding rock is partial to repair and optimization after failure of supporting structure, and only for specific structure of ingate is studied, without considering blasting vibration effect on damage of ingate surrounding rock, and lack of study on layout design of ingate surrounding chamber group. Based on the research status of deep vertical shaft ingate, this paper has carried on theoretical analysis and field testing for ingate surrounding rock damage affected by vibration load produced in process of excavation and blasting in mine roadway and chamber, getting the change law of ingate surrounding rock damage under blasting vibration, and new control measures about loaded constitution, delay blasting technology, set isolation hole, especially the rational layout of ingate surrounding chamber group are provided, combined with numerical simulation software to determine reasonable spacing of ingate surrounding chamber group in deep vertical shaft, and optimize construction sequence. Finally, research achievements are applied to engineering practice, the results of field deformation monitoring show that ingate in mine roadway and chamber can maintain good integrity under construction process
Revealing the mystery of the double charm tetraquark in collision
A novel approach is proposed to probe the nature of the double charm
tetraquark through the measurement of production asymmetry between
and in collisions. When comparing two
theoretical pictures, the compact tetraquark and molecular pictures, we find
that the compact tetraquark picture exhibits a significantly larger production
asymmetry and an order of magnitude lower total cross section compared to the
molecular picture, enabling the unambiguous determination of the tetraquark's
internal structure. Additionally, distinctive differences in the transverse
momentum () and rapidity () distributions of
and cross sections emerge, particularly at
and . The difference
between particles and antiparticles in a large rapidity region is attributed to
the behavior of the residual diquarks within the proton. Our work extends
to the exploration of other double heavy tetraquark candidates, offering a
versatile approach to advance our understanding of exotic hadronic states in
particle physics.Comment: 6 pages, 3 figure
Superior surface modification layer of poly(styrene) on SiO gate insulator in rubrene single crystal field-effect transistor
We conduct comparative research on the density of states of electron- and
hole- carrier trap levels (DTR(E)), dispersing inside the energy gap of a
rubrene single crystal in a field effect transistor (FET) struction with Ca and
Au hetero-electrodes for an ambipolar carrier injection mode, by using
polymeric protection-layer materials on a Si substrate. Three different types
of polymeric materials, poly(methyl-methacrylate) (PMMA), poly(styrene) (PS)
and poly(chloro-styrene) (PCS) are employed. From the temperature (T)-dependent
source-drain current and gate voltage (ISD-VG) transfer characteristics, the
values of DTR(E) are evaluated. PS exhibits the most efficiently-balanced
ambipolar carrier transport, which is superior to PMMA that is most typically
used as the standard protection layer on a SiO/doped-Si substrate.
Discussions are made in the framework of a carrier multiple trap and release
(CMTR) model.Comment: 9 pages, 5figure
NDRG2 suppresses the proliferation of clear cell renal cell carcinoma cell A-498
<p>Abstract</p> <p>Background</p> <p>Recently, the anti-tumor activity of N-myc downstream-regulated gene 2 (NDRG2) was shown decreased expression in clear cell renal cell carcinoma (CCRCC), but the role of the down-expression of NDRG2 has not been described.</p> <p>Methods</p> <p>The NDRG2 recombinant adenovirus plasmid was constructed. The proliferation rate and NDRG2 expression of cell infected with recombinant plasmid were mesured by MTT, Flow cytometry analysis and western blot.</p> <p>Results</p> <p>The CCRCC cell A-498 re-expressed NDRG2 when infected by NDRG2 recombinant adenovirus and significantly decreased the proliferation rate. Fluorescence activated cell sorter analysis showed that 25.00% of cells expressed NDRG2 were in S-phase compared to 40.67% of control cells, whereas 62.08% of cells expressed NDRG2 were in G1-phase compared to 54.39% of control cells (<it>P </it>< 0.05). In addition, there were much more apoptotic cells in NDRG2-expressing cells than in the controls (<it>P </it>< 0.05). Moreover, upregulation of NDRG2 protein was associated with a reduction in cyclin D1, cyclin E, whereas cyclinD2, cyclinD3 and cdk2 were not affected examined by western blot. Furthermore, we found that p53 could upregulate NDRG2 expression in A-498 cell.</p> <p>Conclusions</p> <p>We found that NDRG2 can inhibit the proliferation of the renal carcinoma cells and induce arrest at G1 phase. p53 can up-regulate the expression of NDRG2. Our results showed that NDRG2 may function as a tumor suppressor in CCRCC.</p
Disorder induced multifractal superconductivity in monolayer niobium dichalcogenides
The interplay between disorder and superconductivity is a subtle and
fascinating phenomenon in quantum many body physics. The conventional
superconductors are insensitive to dilute nonmagnetic impurities, known as the
Anderson's theorem. Destruction of superconductivity and even
superconductor-insulator transitions occur in the regime of strong disorder.
Hence disorder-enhanced superconductivity is rare and has only been observed in
some alloys or granular states. Because of the entanglement of various effects,
the mechanism of enhancement is still under debate. Here we report
well-controlled disorder effect in the recently discovered monolayer NbSe
superconductor. The superconducting transition temperatures of NbSe
monolayers are substantially increased by disorder. Realistic theoretical
modeling shows that the unusual enhancement possibly arises from the
multifractality of electron wave functions. This work provides the first
experimental evidence of the multifractal superconducting state
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