198 research outputs found
Bubble expansion at strong coupling
The cosmological first-order phase transition (FOPT) can be of strong
dynamics but with its bubble wall velocity difficult to be determined due to
lack of detailed collision terms. Recent holographic numerical simulations of
strongly coupled theories with a FOPT prefer a relatively small wall velocity
linearly correlated with the phase pressure difference between false and true
vacua for a planar wall. In this Letter, we have analytically revealed the
non-relativistic limit of a planar/cylindrical/spherical wall expansion of a
bubble strongly interacting with the thermal plasma. The planar-wall result
reproduces the linear relation found previously in the holographic numerical
simulations. The results for cylindrical and spherical walls can be directly
tested in future numerical simulations. Once confirmed, the bubble wall
velocity for a strongly coupled FOPT can be expressed purely in terms of the
hydrodynamics without invoking the underlying microphysics.Comment: v1, 5 pages + 1 appendix, 2 figures; v2, 11 pages, 3 figures,
accepted for publication in Phys. Rev. D; v3, typos corrected, references
added, to match the published versio
Recent Advances in Heterogeneous Catalytic Hydrogenation of CO2 to Methane
With the accelerating industrialization, urbanization process, and continuously upgrading of consumption structures, the CO2 from combustion of coal, oil, natural gas, and other hydrocarbon fuels is unbelievably increased over the past decade. As an important carbon resource, CO2 gained more and more attention because of its converting properties to lower hydrocarbon, such as methane, methanol, and formic acid. Among them, CO2 methanation is considered to be an extremely efficient method due to its high CO2 conversion and CH4 selectivity. However, the CO2 methanation process requires high reaction temperatures (300–400°C), which limits the theoretical yield of methane. Thus, it is desirable to find a new strategy for the efficient conversion of CO2 to methane at relatively low reaction temperature, and the key issue is using the catalysts in the process. The advances in the noble metal catalysts, Ni-based catalysts, and Co-based catalysts, for catalytic hydrogenation CO2 to methane are reviewed in this paper, and the effects of the supports and the addition of second metal on CO2 methanation as well as the reaction mechanisms are focused
General bubble expansion at strong coupling
The strongly-coupled system like the quark-hadron transition (if it is of
first order) is becoming an active play-yard for the physics of cosmological
first-order phase transitions. However, the traditional field theoretic
approach to strongly-coupled first-order phase transitions is of great
challenge, driving recent efforts from holographic dual theories with explicit
numerical simulations. These holographic numerical simulations have revealed an
intriguing linear correlation between the phase pressure difference (pressure
difference away from the wall) to the non-relativistic terminal velocity of an
expanding planar wall, which has been reproduced analytically alongside both
cylindrical and spherical walls from perfect-fluid hydrodynamics in our
previous study but only for a bag equation of state. We have also found in our
previous study a universal quadratic correlation between the wall pressure
difference (pressure difference near the bubble wall) to the non-relativistic
terminal wall velocity regardless of wall geometries. In this paper, we will
generalize these analytic relations between the phase/wall pressure difference
and terminal wall velocity into a more realistic equation of state beyond the
simple bag model, providing the most general predictions so far for future
tests from holographic numerical simulations of strongly-coupled first-order
phase transitionsComment: 22 pages, 10 figure
Maternal and fetal/neonatal outcomes of pregnancies complicated by pulmonary hypertension: a retrospective study of 154 patients
Objectives: To determine the main clinical and demographic outcomes related to Pulmonary Hypertension (PH) and adverse obstetric and fetal/neonatal outcomes.
Methods: This study retrospectively analyzed the medical record data of 154 patients with PH who were admitted to the Third Affiliated Hospital of Guangzhou Medical University between January 2011 and December 2020.
Results: According to the severity of elevated Pulmonary Artery Systolic Pressure (PASP), 82 women (53.2%) were included in the mild PH group, 34 (22.1%) were included in the moderate PH group, and 38 (24.7%) were included in the severe PH group. There were significant differences in the incidence of heart failure, premature delivery, Very-Low-Birth-Weight (VLBW) infants, and Small-for-Gestational-Age (SGA) infants among the three PH groups (p < 0.05). Five (3.2%) women died within 7-days after delivery, 7 (4.5%) fetuses died in utero, and 3 (1.9%) neonates died. The authors found that PASP was an independent risk factor for maternal mortality. After adjustment for age, gestational weeks, systolic blood pressure, Body Mass Index (BMI), mode of delivery, and anesthesia, the risk of maternal mortality in the severe PH group was 20.21 times higher than that in the mild-moderate PH group (OR = 21.21 [95% CI 1.7∼264.17]), p < 0.05. All 131 (85.1%) patients were followed up for 12 months postpartum.
Conclusions: The authors found that the risk of maternal mortality in the severe PH group was significantly higher than that in the mild-moderate group, highlighting the importance of pulmonary artery pressure screening before pregnancy, early advice on contraception, and multidisciplinary care
Knockout of Nr2e3 prevents rod photoreceptor differentiation and leads to selective L-/M-cone photoreceptor degeneration in zebrafish
CERKL gene knockout disturbs photoreceptor outer segment phagocytosis and causes rod-cone dystrophy in zebrafish
Effects of S. cerevisiae strains on the sensory characteristics and flavor profile of kiwi wine based on E-tongue, GC-IMS and 1H-NMR
The fermentation of kiwifruit into kiwi wine (KW) can represent a strategy to reduce the economic losses linked
to fruits imperfections, spoilage, over production and seasonality. In the study, Pujiang kiwifruit, a China National
Geographical Indication Product, was used as raw material to produce KW fermented by four commercial
S. cerevisiae strains, namely Drop Acid Yeast, DV10, SY and RW. The sensory characteristics and flavor profile of
KW were assessed by means of sensory evaluation, E-tongue, GC-IMS and 1H-NMR. KW fermented by RW strain
obtained the higher sensory evaluation score. E-tongue could clearly distinguish the taste differences of KW
fermented by distinct S. cerevisiae strains. A total of 128 molecules were characterized by GC-IMS and 1H-NMR,
indicating that the combinations of multiple technologies could provide a comprehensive flavor profile of KW.
The main flavor compounds in KW pertained to the classes of esters and alcohols. Several pathways were found
to be differently altered by the fermentation with the different yeast strains, namely butanoate metabolism,
glycerolipid metabolism, alanine, aspartate and glutamate metabolism, arginine biosynthesis, arginine and
proline metabolism. The present study will facilitate screening suitable S. cerevisiae strains for KW production
and provide a theoretical basis for large-scale production of KW
Strategies for Managing Soil Nitrogen to Prevent Nitrate-N Leaching in Intensive Agriculture System
CERKL regulates autophagy via the NAD-dependent deacetylase SIRT1
<p>Macroautophagy/autophagy is an important intracellular mechanism for the maintenance of cellular homeostasis. Here we show that the <i>CERKL</i> (ceramide kinase like) gene, a retinal degeneration (RD) pathogenic gene, plays a critical role in regulating autophagy by stabilizing SIRT1. <i>In vitro</i> and <i>in vivo</i>, suppressing CERKL results in impaired autophagy. SIRT1 is one of the main regulators of acetylation/deacetylation in autophagy. In CERKL-depleted retinas and cells, SIRT1 is downregulated. ATG5 and ATG7, 2 essential components of autophagy, show a higher degree of acetylation in CERKL-depleted cells. Overexpression of SIRT1 rescues autophagy in CERKL-depleted cells, whereas CERKL loses its function of regulating autophagy in SIRT1-depleted cells, and overexpression of CERKL upregulates SIRT1. Finally, we show that CERKL directly interacts with SIRT1, and may regulate its phosphorylation at Ser27 to stabilize SIRT1. These results show that CERKL is an important regulator of autophagy and it plays this role by stabilizing the deacetylase SIRT1.</p
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