7 research outputs found
Toroidal Vortices in Resistive Magnetohydrodynamic Equilibria
Resistive steady states in toroidal magnetohydrodynamics (MHD), where Ohm's
law must be taken into account, differ considerably from ideal ones. Only for
special (and probably unphysical) resistivity profiles can the Lorentz force,
in the static force-balance equation, be expressed as the gradient of a scalar
and thus cancel the gradient of a scalar pressure. In general, the Lorentz
force has a curl directed so as to generate toroidal vorticity. Here, we
calculate, for a collisional, highly viscous magnetofluid, the flows that are
required for an axisymmetric toroidal steady state, assuming uniform scalar
resistivity and viscosity. The flows originate from paired toroidal vortices
(in what might be called a ``double smoke ring'' configuration), and are
thought likely to be ubiquitous in the interior of toroidally driven
magnetofluids of this type. The existence of such vortices is conjectured to
characterize magnetofluids beyond the high-viscosity limit in which they are
readily calculable.Comment: 17 pages, 4 figure
Fabrication of Bis-Quaternary Ammonium Salt as an Efficient Bactericidal Weapon Against Escherichia coli and Staphylococcus aureus
Combating
bacterial pathogens has become a global concern, especially
the emergence of drug-resistant bacteria have made conventional antibiotics
lose their efficiency. This grim situation suggests the necessity
to explore novel antibacterial agents with favorable safety and strong
antibacterial activity. Here, we took the advantage of quaternary
ammonium compounds and synthesized a long-chain high-molecular organic
bis-quaternary ammonium salt (BQAS) with a broad-spectrum bactericidal
activity through a facile one-pot reaction. The bactericidal effect
of BQAS was evaluated by two bacterial human pathogens: Escherichia coli (Gram-negative) and Staphylococcus aureus (Gram-positive), which are
the major cause of diarrheal infections in children and adults. Our
experimental results indicate that the bactericidal activity of BQAS
is linked to the strong contact between the positively charged quaternary
ammonium groups and the bacterial cells, thus leading to a temporary
and locally high concentration of reactive oxygen species, which subsequently
triggers oxidative stress and membrane damage in the bacteria. This
mechanism was further confirmed by several assays, such as the membrane
permeabilization assay, fluorescent-based cell live/dead test, scanning
electron microscopy, transmission electron microscopy, together with
the lactate dehydrogenase release assay, which all indicated that
BQAS induced damage to the cytoplasmic membrane and the leakage of
intracellular fluid containing essential molecules. The excellent
bactericidal activity of BQAS suggests its great application potential
as a promising candidate against the rapid emergence of drug-resistant
bacterial pathogens
DataSheet_1_Genome-wide characterization of the SHORT INTER-NODES/STYLISH and Shi-Related Sequence family in Gossypium hirsutum and functional identification of GhSRS21 under salt stress.pdf
Saline stress is a significant factor that caused crop growth inhibition and yield decline. SHORT INTERNODES/STYLISH (SHI/STY) and SHI-RELATED SEQUENCE (SRS) transcription factors are specific to plants and share a conserved RING-like zinc-finger domain (CX2CX7CX4CX2C2X6C). However, the functions of SHI/STY and SRS genes in cotton responses to salt stress remain unclear. In this study, 26 GhSRSs were identified in Gossypium hirsutum, which further divided into three subgroups. Phylogenetic analysis of 88 SRSs from8 plant species revealed independent evolutionary pattern in some of SRSs derived from monocots. Conserved domain and subcellular location predication of GhSRSs suggested all of them only contained the conserved RING-like zinc-finger domain (DUF702) domain and belonged to nucleus-localized transcription factors except for the GhSRS22. Furthermore, synteny analysis showed structural variation on chromosomes during the process of cotton polyploidization. Subsequently, expression patterns of GhSRS family members in response to salt and drought stress were analyzed in G. hirsutum and identified a salt stress-inducible gene GhSRS21. The GhSRS21 was proved to localize in the nuclear and silencing it in G. hirsutum increased the cotton resistance to salt using the virus-induced gene silencing (VIGS) system. Finally, our transcriptomic data revealed that GhSRS21 negatively controlled cotton salt tolerance by regulating the balance between ROS production and scavenging. These results will increase our understanding of the SRS gene family in cotton and provide the candidate resistant gene for cotton breeding.</p
Mitigating intensity of urban heat island by better understanding on urban morphology and anthropogenic heat dispersion
10.1016/j.buildenv.2020.106876BUILDING AND ENVIRONMENT17