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5,221
result(s) for
"Hu, Shan"
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Nontrivial bundles and defect operators in n-form gauge theories
A
bstract
In (
d
+ 1)-dimensional 1-form nonabelian gauge theories, we classify nontrivial 0-form bundles in
ℝ
d
, which yield configurations of
D
(
d
− 2
j
)-branes wrapping (
d
− 2
j
)-cycles
c
d
−2
j
in
Dd
-branes. We construct the related defect operators
U
(2
j
−1)
(
c
d
−2
j
), which are disorder operators carrying the
D
(
d
– 2
j
) charge. We compute the commutation relations between the defect operators and Chern-Simons operators on odd-dimensional closed manifolds, and derive the generalized Witten effect for
U
(2
j
−1)
(
c
d
−2
j
). When
c
d
−2
j
is not exact,
U
(2
j
−1)
(
c
d
−2
j
) and
U
(2
j
−1)
(–
c
d
−2
j
) can also combine into an electric (2
j
– 1)-form global symmetry operator, where the (2
j
– 1)-form is the Chern-Simons form. The dual magnetic (
d
– 2
j
)-form global symmetry is generated by the
D
(
d
– 2
j
) charge. We also study nontrivial 1-form bundles in (
d
+ 1)-dimensional 2-form nonabelian gauge theories, where the defect operators are
U
2
j
c
d
−
2
j
−
1
. With the field strength of the 1-form taken as the flat connection of the 2-form, we classify the topological sectors in 2-form theories.
Journal Article
Advances in mRNA Vaccines for Infectious Diseases
During the last two decades, there has been broad interest in RNA-based technologies for the development of prophylactic and therapeutic vaccines. Preclinical and clinical trials have shown that mRNA vaccines provide a safe and long-lasting immune response in animal models and humans. In this review, we summarize current research progress on mRNA vaccines, which have the potential to be quick-manufactured and to become powerful tools against infectious disease and we highlight the bright future of their design and applications.
Journal Article
Synergetic Effects of Isoprene and HOx on Biogenic New Particle Formation
New particle formation (NPF) has been observed at various locations, but NPF does not occur in isoprene‐dominant forests. Recent laboratory studies were conducted to understand the role of isoprene in biogenic NPF, and these studies show that isoprene can suppress biogenic NPF, with contradicting theories. To reconcile these discrepancies, we conducted flow tube experiments of biogenic nucleation under a wide range of isoprene over monoterpene carbon ratios (R) and oxidant conditions (OH vs. ozone). Our results show isoprene either suppresses or enhances biogenic NPF, depending on R and oxidation regimes, demonstrating the synergetic effects of isoprene and HOx (OH and HO2) on biogenic NPF. Whereas the suppression of NPF by isoprene is due to the product suppression effects of monoterpene dimers (C20), RO2 + HO2 termination reactions also play important roles in suppressing the dimer formation, another likely process to suppress NPF in the atmosphere. Plain Language Summary Isoprene, emitted mainly from broad‐leaf trees, is the most important volatile organic compound at the global scale. Yet, the role of isoprene in new particle formation (NPF) is still unclear and studies often show contradicting results. In this study, using the state‐of‐the art mass spectrometer analysis, we show how oxidation reactions of isoprene can suppress or enhance biogenic NPF under different oxidation conditions. We believe our results help to reconcile the discrepancies that exist in the previous biogenic NPF studies. Key Points Isoprene can suppress or enhance biogenic new particle formation (NPF) depending on the oxidation regime (OH vs. ozone oxidation) Biogenic NPF is affected by both biogenic volatile organic compounds (VOCs) composition and HOx conditions Previous laboratory studies showed seemingly contradicting theories because of the vastly different VOCs and HOx conditions
Journal Article
Doping-induced structural phase transition in cobalt diselenide enables enhanced hydrogen evolution catalysis
Transition metal dichalcogenide materials have been explored extensively as catalysts to negotiate the hydrogen evolution reaction, but they often run at a large excess thermodynamic cost. Although activating strategies, such as defects and composition engineering, have led to remarkable activity gains, there remains the requirement for better performance that aims for real device applications. We report here a phosphorus-doping-induced phase transition from cubic to orthorhombic phases in CoSe
2
. It has been found that the achieved orthorhombic CoSe
2
with appropriate phosphorus dopant (8 wt%) needs the lowest overpotential of 104 mV at 10 mA cm
−2
in 1 M KOH, with onset potential as small as −31 mV. This catalyst demonstrates negligible activity decay after 20 h of operation. The striking catalysis performance can be attributed to the favorable electronic structure and local coordination environment created by this doping-induced structural phase transition strategy.
Transition metal dichalcogenides represent an exciting class of earth-abundant hydrogen-from-water electrocatalysts, although low efficiencies limit commercialization. Here, authors present a doping strategy to induce a phase transition in cobalt selenide and boost H
2
-evolution performance.
Journal Article
Case report of pulmonary endometriosis and review of the literature
Pulmonary endometriosis is a rare form of thoracic endometriosis. We herein describe a 29-year-old woman with recurrent hemoptysis associated with her menstrual cycle. The patient had a 4-month history of catamenial hemoptysis without thoracic pain, respiratory embarrassment, cough, fever, night sweating, or loss of appetite. Chest computed tomography revealed exudation shadows in the right lower pulmonary lobe and small fiber lesions in the right middle lobe and left lung. Thoracoscopic wedge resection of the right lower pulmonary lobe was performed, and the pathological result was pulmonary endometriosis. No evidence of hemoptysis during menstruation was found following the operation.
Journal Article
Hydrologic evaluation of Multisatellite Precipitation Analysis standard precipitation products in basins beyond its inclined latitude band: A case study in Laohahe basin, China
Two standard Tropical Rainfall Measuring Mission (TRMM) Multisatellite Precipitation Analysis (TMPA) products, 3B42RT and 3B42V6, were quantitatively evaluated in the Laohahe basin, China, located within the TMPA product latitude band (50°NS) but beyond the inclined TRMM satellite latitude band (36°NS). In general, direct comparison of TMPA rainfall estimates to collocated rain gauges from 2000 to 2005 show that the spatial and temporal rainfall characteristics over the region are well captured by the 3B42V6 estimates. Except for a few months with underestimation, the 3B42RT estimates show unrealistic overestimation nearly year round, which needs to be resolved in future upgrades to the real‐time estimation algorithm. Both model‐parameter error analysis and hydrologic application suggest that the three‐layer Variable Infiltration Capacity (VIC‐3L) model cannot tolerate the nonphysical overestimation behavior of 3B42RT through the hydrologic integration processes, and as such the 3B42RT data have almost no hydrologic utility, even at the monthly scale. In contrast, the 3B42V6 data can produce much better hydrologic predictions with reduced error propagation from input to streamflow at both the daily and monthly scales. This study also found the error structures of both RT and V6 have a significant geo‐topography‐dependent distribution pattern, closely associated with latitude and elevation bands, suggesting current limitations with TRMM‐era algorithms at high latitudes and high elevations in general. Looking into the future Global Precipitation Measurement (GPM) era, the Geostationary Infrared (GEO‐IR) estimates still have a long‐term role in filling the inevitable gaps in microwave coverage, as well as in enabling sub‐hourly estimates at typical 4‐km grid scales. Thus, this study affirms the call for a real‐time systematic bias removal in future upgrades to the IR‐based RT algorithm using a simple scaling factor. This correction is based on MW‐based monthly rainfall climatologies applied to the combined monthly satellite‐gauge research products.
Journal Article
Importance of gas-particle partitioning of ammonia in haze formation in the rural agricultural environment
Ammonia in the atmosphere is essential for the formation of fine particles that impact air quality and climate. Despite extensive prior research to disentangle the relationship between ammonia and haze pollution, the role of ammonia in haze formation in high ammonia-emitting regions is still not well understood. Aiming to better understand secondary inorganic aerosol (sulfate, nitrate, ammonium – SNA) formation mechanisms under high-ammonia conditions, 1-year hourly measurement of water-soluble inorganic species (gas and particle) was conducted at a rural supersite in Shanghai. Exceedingly high levels of agricultural ammonia, constantly around 30 µg m−3, were observed. We find that gas-particle partitioning of ammonia (ε(NH4+)), as opposed to ammonia concentrations, plays a critical role in SNA formation during the haze period. From an assessment of the effects of various parameters, including temperature (T), aerosol water content (AWC), aerosol pH, and activity coefficient, it seems that AWC plays predominant regulating roles for ε(NH4+). We propose a self-amplifying feedback mechanism associated with ε(NH4+) for the formation of SNA, which is consistent with diurnal variations in ε(NH4+), AWC, and SNA. Our results imply that a reduction in ammonia emissions alone may not reduce SNA effectively, at least at rural agricultural sites in China.
Journal Article
Construction of eGFP-Tagged Senecavirus A for Facilitating Virus Neutralization Test and Antiviral Assay
Senecavirus A (SVA), also known as Seneca Valley virus, is an emerging virus that causes vesicular disease in pigs. This virus belongs to the genus Senecavirus in the family Picornaviridae. The SVA CH-LX-01-2016 was isolated from Guangdong Province of China in 2016. In this study, a recombinant SVA CH-LX-01-2016 was constructed using reverse genetics, and proven to be able to express efficiently an enhanced green fluorescent protein (eGFP) in vitro. This eGFP-tagged recombinant SVA (rSVA-eGFP) exhibited a high capacity for viral replication. Its fluorescence-tracked characteristics greatly facilitated both virus neutralization test (VNT) and antiviral assay. The rSVA-eGFP-based VNT was used to detect eight porcine serum samples, out of which four were determined to be neutralization titer-positive. Subsequently, two antiviral drugs, ribavirin and apigenin, were assayed for evaluating both effects against the rSVA-eGFP in vitro. The result showed that only the ribavirin exhibited an anti-SVA activity.
Journal Article
Multiple scenario simulation and optimization of an urban green infrastructure network based on complex network theory: a case study in Harbin City, China
BackgroundUrban green infrastructure (GI) networks play a significant role in ensuring regional ecological security; however, they are highly vulnerable to the influence of urban development, and the optimization of GI networks with better connectivity and resilience under different development scenarios has become a practical problem that urgently needs to be solved. Taking Harbin, a megacity in Northeast China, as the case study, we set five simulation scenarios by adjusting the economic growth rate and extracted the GI network in multiple scenarios by integrating the minimal cumulative resistance model and the gravity model. The low-degree-first (LDF) strategy of complex network theory was introduced to optimize the GI network, and the optimization effect was verified by robustness analysis.ResultsThe results showed that in the 5% economic growth scenario, the GI network structure was more complex, and the connectivity of the network was better, while in the other scenarios, the network structure gradually degraded with economic growth. After optimization by the LDF strategy, the average degree of the GI network in multiple scenarios increased from 2.368, 2.651, 2.189, 1.972, and 1.847 to 2.783, 3.125, 2.643, 2.414, and 2.322, respectively, and the GI network structure connectivity and resilience were significantly enhanced in all scenarios.ConclusionsEconomic growth did not necessarily lead to degradation of the GI network; there was still room for economic development in the study area, but it was limited under existing GI conditions, and the LDF strategy was an effective method to optimize the GI network. The research results provide a new perspective for the study of GI network protection with urban economic growth and serve as a methodological reference for urban GI network optimization.
Journal Article