| 1. |
- Cui, Peng, et al.
(författare)
-
Hypothalamic DNA methylation in rats with dihydrotestosterone-induced polycystic ovary syndrome: effects of low-frequency electro-acupuncture.
- 2018
-
Ingår i: Experimental physiology. - 1469-445X. ; 103:12, s. 1618-1632
-
Tidskriftsartikel (refereegranskat)abstract
- What is the central question of this study? What is the role of hypothalamic DNA methylation in the development of PCOS and the response to electro-acupuncture treatment. What is the main finding and its importance? Global DNA methylation and expression of DNA methyltransferases (Dnmts) were increased in PCOS-like rats, and electro-acupuncture decreased global DNA methylation and Dnmt3b expression. Pyrosequencing showed that the DNA methylation of some PCOS candidate genes was changed in the PCOS and PCOS+EA groups, suggesting that hypothalamic DNA methylation plays an important role in the development of PCOS and in mediating the effects of electro-acupuncture treatment.Polycystic ovary syndrome (PCOS) is a common reproductive and endocrine disease of unknown etiology. Recently, epigenetic studies focusing on DNA methylation in PCOS have received much attention, but the mechanisms are still unclear. In the present study, we used the 5a-dihydrotestosterone-induced PCOS-like rat model and treated the rats with electro-acupuncture (EA). Rats were randomly divided into four groups - controls, diet-induced obesity (DIO), PCOS, and PCOS+EA. We examined the reproductive, metabolic, and behavioral phenotypes, validated the effect of EA, and explored the role of hypothalamic DNA methylation by analyzing the methylation of global DNA and selected candidate genes. The PCOS rats presented with reproductive dysfunctions such as lack of regular estrus cyclicity, metabolic disorders such as increased body weight and insulin resistance, and depression and anxiety-like behaviors. EA improved the reproductive functions, decreased body weight, and improved experimental depressive behavior. Furthermore, global DNA methylation and the expression of DNA methyltransferases (Dnmts) were increased in PCOS rats compared to the control group, and EA decreased the global DNA methylation and the expression of Dnmt3b. In addition, pyrosequencing showed that the DNA methylation of certain CpG sites in targeted genes (Plcg1, Camk2b, Esr2, and Pgr) was increased in the PCOS group, but the DNA methylation of Camk2b and Ar was decreased after EA treatment. These results indicate that hypothalamic DNA methylation might be correlated with the development of PCOS and that EA has an effect on hypothalamic DNA methylation in PCOS rats. This article is protected by copyright. All rights reserved.
|
|
| 2. |
- Cui, Yanqing, et al.
(författare)
-
Optical diagnostics of misfire in partially premixed combustion under low load conditions
- 2022
-
Ingår i: Fuel. - : Elsevier BV. - 0016-2361. ; 329
-
Tidskriftsartikel (refereegranskat)abstract
- To clarify the misfire mechanism is important for stabilizing combustion in partially premixed combustion (PPC) under low load. Fuel-tracer planar laser-induced fluorescence (PLIF), formaldehyde PLIF, flame and OH* natural luminosity imaging were utilized to qualify the local equivalence ratio, low-temperature reaction and the high-temperature flame features in an optical engine. Results show that in high direct injection (DI) pressure (1000 bar), due to excessive premixing, the local equivalence ratio in the initial timing of the high temperature heat release (HTHR) is low. Although the auto-ignition flame kernels are formed in high DI pressure, they cannot stably develop, resulting in misfire during the flame development process. In late DI timing (-5 crank angle degree after top dead center, °CA ADTC), since the whole heat release process occurs in the expansion stroke, the in-cylinder temperature and pressure continue decreasing. Although the local equivalence ratio in some regions is high enough, the in-cylinder thermodynamic environment does not support the generation of more auto-ignition flame kernels, thus a small amount of auto-ignition flame kernels can only develop through flame propagation. In short, the misfire of PPC occurs in regions where the equivalence ratio is low or the in-cylinder thermodynamic environment does not further support flame development. Therefore, the trade-off relationship between equivalence ratio and temperature determines the formation of auto-ignition kernels. The local equivalence ratio and temperature distribution near the initial timing of HTHR is the key factor to ensure the subsequent stable combustion. Taking the ambient pressure of 18 bar as an example, the boundary condition where the autoignition kernels are most likely formed or the charge is most likely ignited by the nearby flame kernels is in the range of 0.53–0.62 for equivalence ratio and 740–757 K for temperature. The misfire region most likely appears when the equivalence ratio is lower than 0.49. It can be concluded that the misfire of PPC results from the synergistic effect of local equivalent ratio and temperature. The controlling parameters of injection pressure and injection timing are actually optimizing the suitable combinations of equivalence ratio and temperature to stabilize combustion.
|
|
| 3. |
- Liu, Haifeng, et al.
(författare)
-
Effects of Flame Temperature on PAHs and Soot Evolution in Partially Premixed and Diffusion Flames of a Diesel Surrogate
- 2019
-
Ingår i: Energy and Fuels. - : American Chemical Society (ACS). - 0887-0624 .- 1520-5029. ; 33:11, s. 11821-11829
-
Tidskriftsartikel (refereegranskat)abstract
- In this paper, polycyclic aromatic hydrocarbons (PAHs) and soot formation in rich partially premixed flames and nonpremixed flames were studied using a blend of n-heptane and toluene. The flames were diluted with Ar, N2, and CO2 to control the flame temperature. Laser-induced fluorescence, laser-induced incandescence, and two-color pyrometry were used to study the effects of flame temperature on the PAHs and soot evolution. Results show that temperature distributions are similar for different gas dilutions at low flow rates. However, the higherature area increases dramatically in size at high flow rates and it depends on diluents in the order Ar > N2 > CO2 with regard to flame temperature. With an increase in the flow rate of Ar, the higher growth rate of flame temperature and bigger region of higherature region can lead to a higher growth rate from small to large PAHs and higher soot volume fraction. However, for CO2 dilution, the increased flow rate results in the increase of formation of large PAHs, but soot formation is reduced due to the fact that lower flame temperature suppresses the soot formation. Therefore, it can be concluded that the evolution of PAHs and soot strongly depends on flame temperature.
|
|
