374 research outputs found
Covariant Orbital-Spin Scheme for Any Spin based on Irreducible Tensor
In hadron spectrum physics, the partial wave analysis is a primary method
used to extract properties of hadronic resonances. The covariant orbital-spin
coupling scheme holds unique advantages over other partial wave methods due to
its Lorentz covariant form and determined orbital-spin quantum numbers. This
paper presents a general form of the covariant orbital-spin coupling scheme
based on the irreducible tensor of the homogeneous proper Lorentz group and its
little groups. A systematic procedure for constructing partial wave amplitude
in a Lorentz covariant way is provided, which can be applied to both massive
and massless particles. Specific examples are also included.Comment: 38 pages and 2 figure
SelfâSacrificial TemplateâDirected Synthesis of MetalâOrganic FrameworkâDerived Porous Carbon for EnergyâStorage Devices
Metalâorganic framework (MOF)âderived carbon materials exhibit large surface areas, but dominant micropore characteristics and uncontrollable dimensions. Herein, we propose a selfâsacrificial templateâdirected synthesis method to engineer the porous structure and dimensions of MOFâderived carbon materials. A porous zinc oxide (ZnO) nanosheet solid is selected as the selfâsacrificial template and twoâdimensional (2D) nanostructureâdirecting agent to prepare 2D ZIFâ8âderived carbon nanosheets (ZCNs). The asâprepared ZCN materials exhibit a large surface area with hierarchical porosity. These intriguing features render ZCN materials advanced electrode materials for electrochemical energyâstorage devices, demonstrating large ionâaccessible surface area and high ionâ/electronâtransport rates. This selfâsacrificial templateâdirected synthesis method offers new avenues for rational engineering of the porous structure and dimensions of MOFâderived porous carbon materials, thus exploiting their full potential for electrochemical energyâstorage devices.On the surface: A selfâsacrificial templateâdirected synthesis method is proposed to engineer the porosity and dimensions of MOFâderived carbon materials. By using a porous nanosheet solid as the selfâsacrificial template and twoâdimensional (2D) nanostructureâdirecting agent, 2D ZIFâ8âderived carbon nanosheets are prepared, which exhibit a large ionâaccessible surface area and rapid ion transport as the electrode materials for electrochemical energyâstorage devices.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/137193/1/celc201500536-sup-0001-misc_information.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/137193/2/celc201500536.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/137193/3/celc201500536_am.pd
Anti-Hepatitis B Virus Effect and Possible Mechanism of Action of 3,4-O-Dicaffeoylquinic Acid In Vitro and In Vivo
The anti-hepatitis B activity of 3,4-O-dicaffeoylquinic acid isolated from Laggera alata was studied using the D-galactosamine- (D-GalN-) induced hepatocyte damage model, HepG2.2.15 cells, and with HBV transgenic mice. In vitro results showed that 3,4-O-dicaffeoylquinic acid improved HL-7702 hepatocyte viability and markedly inhibited the production of HBsAg and HBeAg. At a concentration of 100âÎŒg/mL, its inhibitory rates on the expression levels of HBsAg and HBeAg were 89.96% and 81.01%, respectively. The content of hepatitis B virus covalently closed circular DNA (HBV cccDNA) in HepG2.2.15 cells was significantly decreased after the cells were treated with the test compound. In addition, 3,4-O-dicaffeoylquinic acid significantly increased the expression of heme oxygenase-1 (HO-1) in HepG2.2.15 cells. In vivo results indicated that the test compound at concentrations of 100âÎŒg/mL significantly inhibited HBsAg production and increased HO-1 expression in HBV transgenic mice. In conclusion, this study verifies the anti-hepatitis B activity of 3,4-O-dicaffeoylquinic acid. The upregulation of HO-1 may contribute to the anti-HBV effect of this compound by reducing the stability of the HBV core protein, which blocks the refill of nuclear HBV cccDNA. Furthermore, the hepatoprotective effect of this compound may be mediated through its antioxidative/anti-inflammatory properties and by the induction of HO-1 expression
Increase in neuroexcitability of unmyelinated C-type vagal ganglion neurons during initial postnatal development of visceral afferent reflex functions
BACKGROUND:
Baroreflex gain increase up closely to adult level during initial postnatal weeks, and any interruption within this period will increase the risk of cardiovascular problems in later of life span. We hypothesize that this short period after birth might be critical for postnatal development of vagal ganglion neurons (VGNs).
METHODS:
To evaluate neuroexcitability evidenced by discharge profiles and coordinate changes, ion currents were collected from identified A- and C-type VGNs at different developmental stages using whole-cell patch clamping.
RESULTS:
C-type VGNs underwent significant age-dependent transition from single action potential (AP) to repetitive discharge. The coordinate changes between TTX-S and TTX-R Na(+) currents were also confirmed and well simulated by computer modeling. Although 4-AP or iberiotoxin age dependently increased firing frequency, AP duration was prolonged in an opposite fashion, which paralleled well with postnatal changes in 4-AP- and iberiotoxin-sensitive K(+) current activity, whereas less developmental changes were verified in A-types.
CONCLUSION:
These data demonstrate for the first time that the neuroexcitability of C-type VGNs increases significantly compared with A-types within initial postnatal weeks evidenced by AP discharge profiles and coordinate ion channel changes, which explain, at least in part, that initial postnatal weeks may be crucial for ontogenesis in visceral afferent reflex function
Recent advancements in applications of encapsulated phase change materials for solar energy systems: A state of the art review
In recent decades, solar energy systems have played an increasingly important role in human societies, including support of the supply of drinking water, hot water, and electricity in arid, semi-arid and remote communities. The most challenging aspects of solar energy systems are storing energy when it is available and using it when there is a high demand for energy without access to solar energy. Encapsulating phase change materials (PCMs) or nano enhanced PCMs can serve as thermal batteries for storing solar energy, whereby it is important to consider the energy characteristics of various encapsulation methods. This includes taking into account encapsulation materials, such as diameter, enthalpy, efficiency, and heat cycling times, in order to integrate them with solar energy systems. In the present paper, production process methods, characteristics and ingredients of encapsulation are reviewed, followed by evaluation of the effect of the composition of encapsulation PCMs on the performance of solar energy applications in in Middle East and North African countries, including photovoltaic/thermal, solar desalination, solar water heater, solar power plant, solar pond, solar thermochemical reactor, and others. Further, the effects of dispersing various nano powders in PCM (encapsulated nano-enhanced PCM) to increase the thermal properties of thermal batteries are reviewed. In addition, a summary of the economic analysis of thermal batteries and evaluating sustainable development goals of solar energy applications as integrated by encapsulated PCMs/nano-enhanced PCMs are conducted and discussed. We conclude by evaluating the trade-off, synergy, future perspectives, and recommendations of encapsulation PCM used in solar energy applications
Comparative Transcriptome Analysis Reveals the Biocontrol Mechanism of Bacillus velezensis F21 Against Fusarium Wilt on Watermelon
The watermelon (Citrullus lanatus) is one of the most important horticultural crops for fruit production worldwide. However, the production of watermelon is seriously restricted by one kind of soilborne disease, Fusarium wilt, which is caused by Fusarium oxysporum f. sp. niveum (Fon). In this study, we identified an efficient PGPR strain B. velezensis F21, which could be used in watermelon production for Fon control. The results of biocontrol mechanisms showed that B. velezensis F21 could suppress the growth and spore germination of Fon in vitro. Moreover, B. velezensis F21 could also enhance plant basal immunity to Fon by increasing the expression of plant defense related genes and activities of some defense enzymes, such as CAT, POD, and SOD. To elucidate the detailed mechanisms regulating B. velezensis F21 biocontrol of Fusarium wilt in watermelon, a comparative transcriptome analysis using watermelon plant roots treated with B. velezensis F21 or sterile water alone and in combination with Fon inoculation was conducted. The transcriptome sequencing results revealed almost one thousand ripening-related differentially expressed genes (DEGs) in the process of B. velezensis F21 triggering ISR (induced systemic resistance) to Fon. In addition, the Gene Ontology (GO) classification and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment indicated that numerous of transcription factors (TFs) and plant disease resistance genes were activated and validated by using quantitative real-time PCR (qRT-PCR), which showed significant differences in expression levels in the roots of watermelon with different treatments. In addition, genes involved in the MAPK signaling pathway and phytohormone signaling pathway were analyzed, and the results indicated that B. velezensis F21 could enhance plant disease resistance to Fon through the above related genes and phytohormone signal factors. Taken together, this study substantially expands transcriptome data resources and suggests a molecular framework for B. velezensis F21 inducing systemic resistance to Fon in watermelon. In addition, it also provides an effective strategy for the control of Fusarium wilt in watermelon
TMRT observations of 26 pulsars at 8.6 GHz
Integrated pulse profiles at 8.6~GHz obtained with the Shanghai Tian Ma Radio
Telescope (TMRT) are presented for a sample of 26 pulsars. Mean flux densities
and pulse width parameters of these pulsars are estimated. For eleven pulsars
these are the first high-frequency observations and for a further four, our
observations have a better signal-to-noise ratio than previous observations.
For one (PSR J0742-2822) the 8.6~GHz profiles differs from previously observed
profiles. A comparison of 19 profiles with those at other frequencies shows
that in nine cases the separation between the outmost leading and trailing
components decreases with frequency, roughly in agreement with
radius-to-frequency mapping, whereas in the other ten the separation is nearly
constant. Different spectral indices of profile components lead to the
variation of integrated pulse profile shapes with frequency. In seven pulsars
with multi-component profiles, the spectral indices of the central components
are steeper than those of the outer components. For the 12 pulsars with
multi-component profiles in the high-frequency sample, we estimate the core
width using gaussian fitting and discuss the width-period relationship.Comment: 33 pages, 49 figures, 5 Tables; accepted by Ap
A superconducting nanowire photon number resolving four-quadrant detector-based Gigabit deep-space laser communication receiver prototype
Deep space explorations require transferring huge amounts of data quickly
from very distant targets. Laser communication is a promising technology that
can offer a data rate of magnitude faster than conventional microwave
communication due to the fundamentally narrow divergence of light. This study
demonstrated a photon-sensitive receiver prototype with over Gigabit data rate,
immunity to strong background photon noise, and simultaneous tracking ability.
The advantages are inherited from a joint-optimized superconducting nanowire
single-photon detector (SNSPD) array, designed into a four-quadrant structure
with each quadrant capable of resolving six photons. Installed in a free-space
coupled and low-vibration cryostat, the system detection efficiency reached
72.7%, the detector efficiency was 97.5%, and the total photon counting rate
was 1.6 Gcps. Additionally, communication performance was tested for pulse
position modulation (PPM) format. A series of signal processing methods were
introduced to maximize the performance of the forward error correction (FEC)
code. Consequently, the receiver exhibits a faster data rate and better
sensitivity by about twofold (1.76 photons/bit at 800 Mbps and 3.40 photons/bit
at 1.2 Gbps) compared to previously reported results (3.18 photon/bit at 622
Mbps for the Lunar Laser Communication Demonstration). Furthermore,
communications in strong background noise and with simultaneous tracking
ability were demonstrated aimed at the challenges of daylight operation and
accurate tracking of dim beacon light in deep space scenarios
HIV-1 Transmission among Injecting Drug Users is Principally Derived from Local Circulating Strains in Guangxi, China
OBJECTIVE: The mode of human immunodeficiency virus (HIV) transmission
METHODS: We performed a molecular epidemiological investigation of infections across Guangxi from 2009 to 2019. Phylogenetic and Bayesian time-geographic analyses of HIV-1 sequences were performed to confirm the characteristics of transmission between IDUs in combination with epidemiological data.
RESULTS: Among the 535 subjects, CRF08_BC (57.4%), CRF01_AE (28.4%), and CRF07_BC (10.7%) were the top 3 HIV strains; 72.6% of infections were linked to other provinces in the transmission network; 93.6% of sequence-transmitted strains were locally endemic, with the rest coming from other provinces, predominantly Guangdong and Yunnan; 92.1% of the HIV transmission among people who inject drugs tended to be transmitted between HIV-positive IDUs.
CONCLUSION: HIV recombinants were high diversity, and circulating local strains were the transmission sources among IDUs in Guangxi. However, there were still cases of IDUs linked to other provinces. Coverage of traditional prevention strategies should be expanded, and inter-provincial collaboration between Guangxi, Yunnan, and Guangdong provinces should be strengthened
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