1,150 research outputs found
Scars in Dirac fermion systems: the influence of an Aharonov--Bohm flux
Time-reversal (-) symmetry is fundamental to many physical
processes. Typically, -breaking for microscopic processes requires
the presence of magnetic field. However, for 2D massless Dirac billiards,
-symmetry is broken automatically by the mass confinement, leading
to chiral quantum scars. In this paper, we investigate the mechanism of
-breaking by analyzing the local current of the scarring
eigenstates and their magnetic response to an Aharonov--Bohm flux. Our results
unveil the complete understanding of the subtle -breaking
phenomena from both the semiclassical formula of chiral scars and the
microscopic current and spin reflection at the boundaries, leading to a
controlling scheme to change the chirality of the relativistic quantum scars.
Our findings not only have significant implications on the transport behavior
and spin textures of the relativistic pseudoparticles, but also add basic
knowledge to relativistic quantum chaos.Comment: 37 pages, 11 figure
Responses of microbial abundance and enzyme activity in integrated vertical-flow constructed wetlands for domestic and secondary wastewater
Although micro-organisms play a significant role in pollutant removal in constructed wetlands, little is known on the effect of wastewater-quality properties on microbial characteristics. In this study, two groups of integrated vertical-flow constructed wetland microcosms were applied to treat synthetic domestic wastewater and synthetic secondary effluent. The effects of wastewater-quality properties on microbial features were assessed. Results showed that higher values of microbial indicators were observed in the systems with domestic wastewater and in down-flow cells. Redundancy analysis revealed that organic matter concentration and temperature were two critical determinants influencing the microbial features
Design And Fabrication of Condenser Microphone Using Wafer Transfer And Micro-electroplating Technique
A novel fabrication process, which uses wafer transfer and
micro-electroplating technique, has been proposed and tested. In this paper,
the effects of the diaphragm thickness and stress, the air-gap thickness, and
the area ratio of acoustic holes to backplate on the sensitivity of the
condenser microphone have been demonstrated since the performance of the
microphone depends on these parameters. The microphone diaphragm has been
designed with a diameter and thickness of 1.9 mm and 0.6 m, respectively,
an air-gap thickness of 10 m, and a 24% area ratio of acoustic holes to
backplate. To obtain a lower initial stress, the material used for the
diaphragm is polyimide. The measured sensitivities of the microphone at the
bias voltages of 24 V and 12 V are -45.3 and -50.2 dB/Pa (at 1 kHz),
respectively. The fabricated microphone shows a flat frequency response
extending to 20 kHz.Comment: Submitted on behalf of EDA Publishing Association
(http://irevues.inist.fr/handle/2042/16838
A Less Toxic Heparin Antagonist—Low Molecular Weight Protamine
A new thirteen amino acid peptide, named low molecular weight protamine (LMWP), was obtained through the enzymatic digestion of native protamine. Both in vitro and in vivo results showed that LMWP fully maintained the heparin neutralization function of protamine but had much lower immunogenicity and antigenicity. Unlike protamine, neither LMWP nor LMWP/heparin complexes caused significant blood platelet aggregation in rats. These results suggest that LMWP can be used as a substitute for protamine for developing a new generation of nontoxic heparin antagonists.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/45793/1/10541_2004_Article_462566.pd
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<p><b>(a)</b> Right-handed twofold helical chain in 1 linked by intermolecular C–H···π interactions (red dotted line); <b>(b)</b> 3D supramolecular architecture construcated by C–H···π, O–H···O and C–H···O interactions.</p
2-(4-Methylphenyl)-1-(phenylsulfonyl)propan-2-ol
The title compound, C16H18O3S, features a U-shape molecular structure with a dihedral angle between the terminal benzene rings of 20.8 (1)°. An intramolecular O—H⋯O hydrogen bond helps to stabilize the molecular structure. Intermolecular classical O—H⋯O and weak C—H⋯O hydrogen bonding is present in the crystal structure
Degradation of the Separase-cleaved Rec8, a Meiotic Cohesin Subunit, by the N-end Rule Pathway
The Ate1 arginyltransferase (R-transferase) is a component of the N-end rule pathway, which recognizes proteins containing N-terminal degradation signals called N-degrons, polyubiquitylates these proteins, and thereby causes their degradation by the proteasome. Ate1 arginylates N-terminal Asp, Glu, or (oxidized) Cys. The resulting N-terminal Arg is recognized by ubiquitin ligases of the N-end rule pathway. In the yeast Saccharomyces cerevisiae, the separase-mediated cleavage of the Scc1/Rad21/Mcd1 cohesin subunit generates a C-terminal fragment that bears N-terminal Arg and is destroyed by the N-end rule pathway without a requirement for arginylation. In contrast, the separase-mediated cleavage of Rec8, the mammalian meiotic cohesin subunit, yields a fragment bearing N-terminal Glu, a substrate of the Ate1 R-transferase. Here we constructed and used a germ cell-confined Ate1−/− mouse strain to analyze the separase-generated C-terminal fragment of Rec8. We show that this fragment is a short-lived N-end rule substrate, that its degradation requires N-terminal arginylation, and that male Ate1−/− mice are nearly infertile, due to massive apoptotic death of Ate1−/− spermatocytes during the metaphase of meiosis I. These effects of Ate1 ablation are inferred to be caused, at least in part, by the failure to destroy the C-terminal fragment of Rec8 in the absence of N-terminal arginylation
Gegen Qinlian Decoction Treats Diarrhea in Piglets by Modulating Gut Microbiota and Short-Chain Fatty Acids
Gut microbiota and its metabolites, short-chain fatty acids (SCFAs), play important roles in diarrheal diseases. Gegen Qinlian decoction (GQD), a Chinese herb formula, has been widely used to treat infectious diarrhea for centuries. However, little is known about the mechanism underlying its efficacy and whether it is mediated by gut microbiota and SCFAs. In this study, the composition of gut microbiota from bacterial diarrheal piglets was assessed using 16S rRNA analysis. The concentrations of fecal SCFAs were determined using a gas chromatography-mass spectrometer (GC-MS). The expression of mucosal pro-inflammatory cytokines in the colon was ascertained. Results showed that GQD reverses the reduction in the richness of gut microbiota, changes its structure, and significantly increases the relative abundances of SCFA-producing bacteria, including Akkermansia, Bacteroides, Clostridium, Ruminococcus, and Phascolarctobacterium. Moreover, GQD increased the levels of fecal SCFAs, including acetic acid, propionic acid, and butyric acid. GQD thus attenuates diarrhea in piglets. Further, our results suggest that the SCFAs could help to attenuate mucosal pro-inflammatory responses following GQD treatment by inhibiting histone deacetylase and the NF-κB pathway. We thus suggseted that gut microbiota play an important role during diarrhea treatment, an effect may be promoted by the GQD-induced structural changes of the gut microbial community and production of SCFAs. The increased levels of SCFAs probably provide further help to attenuate mucosal inflammation and diarrhea. In conclusion, our study might provide evidence that GQD treats diarrhea maybe involved in modulating gut microbiota and increasing SCFA levels
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