The Hengduan Mountains (HDM) biodiversity hotspot exhibits exceptional alpine plant diversity. Here, we investigate factors driving intraspecific divergence within a HDM alpine species Salix ...brachista (Cushion willow), a common component of subnival assemblages. We produce a high-quality genome assembly for this species and characterize its genetic diversity, population structure and pattern of evolution by resequencing individuals collected across its distribution. We detect population divergence that has been shaped by a landscape of isolated sky island-like habitats displaying strong environmental heterogeneity across elevational gradients, combined with population size fluctuations that have occurred since approximately the late Miocene. These factors are likely important drivers of intraspecific divergence within Cushion willow and possibly other alpine plants with a similar distribution. Since intraspecific divergence is often the first step toward speciation, the same factors can be important contributors to the high alpine species diversity in the HDM.
•Interfacial boiling behavior of R134a under different conditions is analyzed.•Increase of energy coefficient and initial temperature and decrease of initial film thicknesses can accelerate ...boiling.•Only initial thicknesses of liquid film can alter the boiling mode of R134a.•Thermal resistance of vapor layer contributes the most to the total thermal resistance by 70.2 %.•Increasing the kinetic energy and reducing the potential energy of molecules can promote boiling.
Boiling heat transfer of low-boiling-point working fluid is one of the promising heat dissipation technologies commonly used in electronic equipment cooling. The study on interfacial heat transfer mechanism is of great significance to improve both heat removal capacity and heat dissipation efficiency. In this work, 1,1,1,2-tetrafluoroethane (R134a) was used as the working fluid, and the interfacial boiling behavior of R134a under different initial thicknesses of liquid film (δ0), solid-liquid interaction force and initial temperature (T0) was analyzed by molecular dynamics (MD) method. In the simulation, δ0 changes from 2.5 to 7.5 nm, the energy coefficient (α) characterizing solid-liquid interaction force changes from 0.25 to 4, T0 ranges from 180 to 200 K, and the temperature difference between the solid substrate and the liquid film is 220 K (i.e., the superheat for boiling). The results show that only δ0 could significantly alter the boiling mode of R134a.When δ0 = 2.5 nm, it shows thin film boiling, otherwise as δ0 gets thicker, it shifts into explosive boiling mode. Under the explosive boiling mode, the total thermal resistance (Rtot) consists of three parts, i.e., the solid interface thermal resistance (RW), thermal resistance of vapor layer (RV), and vapor-liquid interface thermal resistance above layer (RV-L). RV contributes the most to Rtot. However, during the thin film boiling, only RW contributes to Rtot. With the increase of δ0 and α, Rtot presents the similar trend, i.e., increasing first and decreasing afterwards. When δ0 = 7.5 nm and α is 1, Rtot reaches to the highest value of 3.49×10−8 K‧m2/W. For the influence of T0, it oppositely affects Rtot. Overall, the increase of α and T0 and the decrease of δ0 are all beneficial to accelerate the boiling of R134a.
An 8-week feeding trial was conducted to investigate the effects of dietary n-3 highly unsaturated fatty acid (n-3HUFA) on growth performance, antioxidant capacity, fatty acid profiles, hematological ...characteristics and expression of some lipid related genes of juvenile black seabream (Acanthopagrus schlegelii) (initial weight 3.77±0.00g). Five isonitrogenous and isolipidic experimental diets were formulated with graded levels of n-3 HUFA (0.23, 0.87, 1.29, 1.75 and 2.53% of dry weight, DHA/EPA ratio approximately at 1.0). The results revealed that fish fed the diet containing 1.75% n-3 HUFA had higher weight gain (WG) and specific growth rate (SGR) than those fed the control diet. Fish fed diets containing 1.29% and 1.75% n-3 HUFA had higher feed efficiency (FE) than those fed the other diets. Hepatic and muscular fatty acid profiles reflected that of diets. The content of malondialdehyde (MDA) increased both in the serum and liver of fish fed high n-3 HUFA level diets, and the highest hepatic activity of glutathione peroxidase (GSH-PX) was recorded in fish fed the diet containing 1.29% n-3 HUFA. The expression of accα, g6pd, fas, srebp-1, lpl, atgl, hsl, elovl5 and fads2 was down-regulated in fish fed the diets with high n-3 HUFA levels. However, the expression levels of 6pgd and pparα significantly increased when the dietary contents of n-3 HUFA increased from 0.23% to 1.29% and then decreased when dietary n-3 HUFA levels increased from 1.75% to 2.53%. The highest expression of cpt1a was found in fish fed the diet containing 1.75% n-3 HUFA. The content of cholesterol (CHOL) in serum increased along with n-3 HUFA level. Over all, this study indicated that fish fed moderate dietary n-3 HUFA (1.34–1.80% n-3 HUFA) could enhance growth, feed utilization and antioxidant capacity. Different dietary levels of n-3 HUFA could strongly affect expression levels of some lipid metabolism relevant genes of the juvenile black seabream. This may contribute to our understanding of the mechanisms related to lipid metabolism (anabolism and catabolism) effects of different dietary levels of n-3 HUFA.
•Growth performance was significantly influenced by the dietary n-3 HUFA levels.•Dietary n-3 HUFA levels significantly influenced the antioxidant capacity of juvenile black seabream.•The lipid related genes were all significantly regulated by the different dietary n-3 HUFA levels.•The dietary n-3 HUFA requirement of juvenile black seabream is recommended ranging from 1.34% to 1.80% dry weight.
Oxidative stress is an important pathogenic factor in ulcerative colitis (UC) and colitis-associated colorectal cancer (CAC), further impairing the entire colon. Intestinal epithelial cells (IECs) ...are crucial components of innate immunity and play an important role in maintaining intestinal barrier function. Recent studies have indicated that microRNA-222-3p (miR-222-3p) is increased in colon of UC and colorectal cancer (CRC) patients, and miR-222-3p is a crucial regulator of oxidative stress. However, whether miR-222-3p influences IEC oxidative stress in UC and CAC remains unknown. This study investigated the effect of miR-222-3p on the regulation of IEC oxidative stress in UC and CAC. An
inflammation model was established in NCM460 colonic cells, mouse UC and CAC models were established
, and IECs were isolated. The biological role and mechanism of miR-222-3p-mediated oxidative stress in UC and CAC were determined. We demonstrated that miR-222-3p expression was notably increased in dextran sulfate sodium (DSS)-induced NCM460 cells and IECs from UC and CAC mice.
, these results showed that the downregulation of miR-222-3p reduced oxidative stress, caspase-3 activity, IL-1β and TNF-α in DSS-induced NCM460 cells. We further identified BRG1 as the target gene of miR-222-3p, and downregulating miR-222-3p alleviated DSS-induced oxidative injury
promoting BRG1-mediated activation Nrf2/HO-1 signaling in NCM460 cells. The
results demonstrated that inhibiting miR-222-3p in IECs significantly relieved oxidative stress and inflammation in the damaged colons of UC and CAC mice, as evidenced by decreases in ROS, MDA, IL-1β and TNF-α levels and increases in GSH-Px levels. Our study further demonstrated that inhibiting miR-222-3p in IECs attenuated oxidative damage by targeting BRG1 to activate the Nrf2/HO-1 signaling. In summary, inhibiting miR-222-3p in IECs attenuates oxidative stress by targeting BRG1 to activate the Nrf2/HO-1 signaling, thereby reducing colonic inflammation and tumorigenesis.
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•Caffeic acid reduces lipid accumulation in HFD-fed mice.•Caffeic acid supplementation affects biochemical markers of HFD-fed mice.•Caffeic acid regulates lipogenesis-related protein ...expression in HFD-fed mice.•Caffeic acid alleviates endotoxemia and the proinflammatory response in HFD-fed mice.•Caffeic acid attenuates gut microbiota dysbiosis in HFD-fed mice.
Caffeic acid (CA) is derived from many plants and may have the ability to reduce hepatic lipid accumulation. The gut microbiota produces lipopolysaccharides and further influences hepatic lipid metabolism, and thus plays an important role in the development of nonalcoholic fatty liver disease (NAFLD). However, whether the beneficial effects of CA are associated with the gut microbiota remains unclear. The present study aimed to investigate the benefits of experimental treatment with CA on the gut microbiota and metabolic functions in a mouse model of NAFLD. In this study, C57BL/6J mice received a high-fat diet (HFD) for 8 weeks and were then fed a HFD supplemented with or without CA for another 8 weeks. HFD induced obesity and increased accumulation of intrahepatic lipids, serum biochemical parameters and gene expression related to lipid metabolism. Microbiota composition was determined via 16S rRNA sequencing, and analysis revealed that HFD led to dysbiosis, accompanied by endotoxemia and low-grade inflammation. CA reverted the imbalance in the gut microbiota and related lipopolysaccharide-mediated inflammation, thus inhibiting deregulation of lipid metabolism-related gene expression. Our results support the possibility that CA can be used as a therapeutic approach for obesity-associated NAFLD via its anti-inflammatory and prebiotic integrative response.
•Flow boiling of R141b and its acoustic features are simulated and analysed.•Boiling acoustics are determined by flow pattern, wall superheat and flowrate.•Boiling acoustic characteristics with flow ...pattern variation are discussed.•Wavy flow is characterized by low-frequency, but plug flow and slug flow are not.•Flow boiling regimes could be identified by acoustic emission.
Helically coiled steam generators have advantages of strong heat transfer capacity, compact structure, and low thermal stress, and are widely used in many engineering fields. However, the heat transfer performance is still limited by the critical heat flux, beyond which boiling deterioration is an important cause of safety accidents. Both engineering and experimental studies have found that complex noises could be frequently generated during the occurrence of boiling crisis. In this paper, the acoustic characteristics of both subcooled and saturated flow boiling in a helical tube were numerically investigated, by using the volume of fluid scheme and acoustic model. The distribution of the vapor-liquid phase, flow pattern transition, and acoustic frequency band characteristics during boiling were analyzed under different wall temperatures (varied superheat), inlet subcooling, and flowrates. It’s found that the flow pattern under low mass flowrate was plug flow, slug flow, and wavy flow. All the three flow patterns have unique boiling acoustic features. The plug flow, consisted by a large number of small bubbles, shows the distinct high-frequency band characteristics of the boiling acoustics. The wavy flow, which is composed mainly by large bubbles, exhibits a significant low-frequency band characteristics of the boiling acoustics.
•A 2-D high-efficiency micro-mixer was designed by inducing shear- & extension-induced elastic instabilities.•The mixing enhancement by elastic instabilities was the first time realized by DNSs.•The ...irregularly motions by flexibility of polymers is mainly responsible the superior mixing.•The biocompatible working fluids makes the efficient mixing potential for bioengineering and chemical engineering.
Efficient mixing is one of the keen interest of many bioengineering and chemical engineering processes. In this work, we designed an efficient micro-mixer with viscoelastic fluid which can induce both strong shear and strong extension by being embedded several rhombic blocks to destabilize the viscoelastic fluid flow and can be also easily integrated. Experimental visualization and direct numerical simulation (DNS) of mixing process were conducted to evaluate the mixing performance. By adding green fluorescent particles into the fluids, apparent mixing enhancement was observed for viscoelastic fluid flow when the flow rate exceeded a threshold. The efficient micro mixing progress also shows great potential for bioengineering application with the biocompatible working fluids. Through DNS, we discussed the flow patterns and the role of polymers playing in viscoelastic fluid flow to respectively figure out the underlying mechanism of efficient mixing and the occurrence of unstable flow motions. The results show that when the elasticity is strong enough, the viscoelastic fluid flow is irregularly twisting and swinging in the channel, and as a result enhances the mixing by increasing the intersecting frequency of fluids of different concentrations. Moreover, owing to the special designed geometry, the polymers act as the energy supplier of unstable flow motions, which keeps the fluctuations from decaying towards the laminar regime.
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