Evaluation of Influences of Changed Lower Cover Geometry on Kerosene-Air Interaction in a Scramjet Combustor.

The fuel in a scramjet combustor must be injected into a high-speed crossflow and mixed with supersonic air in a very short period of time in order for the scramjet jet to operate reliably. More generally, the supersonic air is produced by the lower cover, similar to a Laval type nozzle, of the scramjet combustor. However, significant variation in lower cover geometry is prone to produce unstable vortexes. The unstable vortexes are accompanied by nonuniform stress and strain and are detrimental to the lower cover, even to the combustor. Inspired by mechanical design, this study proposes to change lower cover geometry by decreasing its sizes and then evaluates effects of these changes on kerosene fuel-air interaction in the combustor. The evaluation is based on three-dimensional computational fluid dynamics with couple level set and volume of fluids, which characterizes the penetration height, span expansion area, shock wave angle, and Sauter mean diameter of kerosene jets for three different injection diameters (0.5, 1.0, and 1.5 mm). The simulated air-kerosene interactions reasonably agree with the past numerical findings at identical working conditions. This result demonstrates the effectiveness of the changed lower cover geometry for the scramjet combustor.

CFD-based pesticide selection for a nozzle used in a six-rotor UAV in hover mode for tea spraying.

BACKGROUND: A key challenge for unmanned aerial vehicle (UAV) spraying sometimes used in tea plantations is the downwash flow structure there stronger than in crops. In addition, the UAV spray is affected by the relationship between the nozzle design and the pesticide. However, there is little current research on this aspect. As a preliminary step this study focuses on the most appropriate pesticide for a designated nozzle in a six-rotor UAV according to the nozzle-pesticide relationship using a three-dimensional computational fluid dynamics model. This model considers the downwash flow structure effect and nozzle spray performance in hover. Nozzle FVP110-02, widely used in six-rotor UAVs, is used as a representative nozzle and bifenthrin and tea saponin water, commonly used in tea plantations, are used as the pesticides. RESULTS: The downwash flow structure of the six-rotor UAV in hover was conveniently controlled by the flight height and rotational speed, thereby causing the turbulence to be more stable. For nozzle FVP110-02, bifenthrin was more appropriate than tea saponin water at the same concentration, whilst bifenthrin and tea saponin water at a concentration of 1:1000 showed the best performance under identical working conditions. CONCLUSION: The numerical model developed here was shown to be effective for investigating the relationship between nozzle and pesticide. Our findings will help to not only improve UAV spraying for tea cultivation but also provide guidelines for pesticide selection in crops. Further work will address the comparison of the rigorous qualification of the numerical simulations with the measurements by the field test. © 2023 Society of Chemical Industry.

The structural, mechanical and electronic properties of Ti-Al-based compounds by first-principles calculations.

The first-principles calculations with density functional theory were performed to investigate the effects of transition metal elements (Mo, Cu, Fe, Ni and Nb) on the physical properties of the Ti-Al-based compounds. Our optimized crystal parameters are in good agreement with the previous theoretical and experimental values. The mechanical stability is verified by the independent elastic constants. The B/G and Poisson's ratio ν both show that Al6TiMo is brittle, while other compounds exhibit ductility. The values of compression anisotropy of the compounds are small, but the shear anisotropy of AlCu2Ti and AlNi2Ti is much more intense than that of other compounds. The anisotropy in elastic properties of AlFe2Ti and AlNbTi2 is smaller than that of the others. It can be seen that the capacity to compress along c-axis is smaller than that along a-axis and b-axis for AlNbTi2. For AlNbTi2, the anisotropy of the bulk modulus along a-axis relative to b-axis is more insignificant than that along c-axis relative to b-axis. The hardness and Debye temperature verify that AlFe2Ti has the greatest resistance to the plastic deformation and more intense inter-atomic bonding force, respectively. Band structures and DOS are used to investigate the electronic properties. The band structures without band gaps show that these ternary Ti-Al-based compounds are conductors. DOS shows the interactions between elements and gives the bond properties. Density of states and charge density both show the strong covalent properties of AlFe2Ti by the hybridization between Fe-3d and Ti-3d states.

Gene expression and methylation profiles show the involvement of POMC in primary hyperparathyroidsm.

Primary hyperparathyroidism (PHPT) is mainly caused by parathyroid adenoma, which produces excess parathyroid hormones. Its pathogenic mechanisms have not yet been fully understood. To investigate the mechanism in the pathogenesis of PHPT, the transcriptome and genome-wide DNA methylation profiles of parathyroid adenoma were analyzed. The candidate genes that may be involved in the PHPT were verified via qRT-PCR, immunohistochemistry, western blot, and methylation-specific PCR. A total of 1650 differentially expressed genes and 2373 differentially methylated regions were identified. After the integration of its transcriptome and DNA methylation data, IL6, SYP, GNA01, and pro-opiomelanocortin (POMC) were the candidate genes that demonstrated a similar pattern between their mRNA expression and DNA methylation status. Of the 4 candidate genes, POMC, a pro-peptide which is processed to a range of bioactive peptide products like ACTH, was further confirmed to be expressed at low levels at both the mRNA and protein levels, which may be due to POMC promoter hypermethylation. Hypermethylation of the POMC promoter may contribute to its low expression, which may be involved in the pathogenesis of PHPT.

Epigallocatechin gallate protects H9c2 cardiomyoblasts against hydrogen dioxides- induced apoptosis and telomere attrition.

Epigallocatechin gallate (EGCG), the major component of polyphenols in green tea, has recently attracted considerable attention for its cardioprotective effects. Telomere signalling plays a role in regulating cardiomyocyte apoptosis during cardiac dysfunction. The purpose of this study was to investigate the effects of EGCG on oxidative stress-induced apoptosis and telomere attrition in cardiomyocytes. H9c2 cells were incubated with EGCG, 50 and 100 mg/l, for 24 h. Apoptosis induced by 200 micromol/l hydrogen dioxide (H(2)O(2)) was analyzed by DAPI nuclear staining, electron microscopy, electrophoresis of DNA fragments and flow cytometry. When H9c2 cells were incubated with H(2)O(2) for 12-24 h, the intracellular and extracellular H(2)O(2) concentrations were not affected by the presence of EGCG. Chromatin condensation, DNA fragmentation and apoptotic body formation were observed in H(2)O(2)-induced injury. Flow cytometry analysis showed that the apoptotic rate increased remarkably. EGCG significantly inhibited H(2)O(2)-induced apoptotic morphological changes and apoptotic rate. When H9c2 cells were incubated with H(2)O(2), the telomere length shortened and the protein expression of telomere repeat-binding factor 2 (TRF(2)) decreased gradually, while the protein levels of p53 and p21 increased. EGCG significantly inhibited telomere attrition, TRF(2) loss and p53, p21 upregulation induced by H(2)O(2). These results suggested that EGCG might suppress oxidative stress-induced cardiomyocyte apoptosis through inhibiting telomere dependent apoptotic pathway.

EGCG inhibits proliferation of cardiac fibroblasts in rats with cardiac hypertrophy.

This study was carried out in order to investigate the effects of epigallocatechin gallate (EGCG) on myocardial fibrosis and cell proliferation in cardiac hypertrophy. Cardiac hypertrophy was established in rats by abdominal aortic constriction, and EGCG at doses of 25, 50 and 100 mg/kg was administered intragastrically for 6 weeks. The results showed that in the rats with cardiac hypertrophy, EGCG at 25 - 100 mg/kg dose-dependently reduced heart weight indices, decreased atrial natriuretic polypeptide and endothelin levels in plasma, but increased nitrite (the oxidative product of NO) levels in the serum and in the myocardium. EGCG also reduced the hydroxyproline concentration and decreased the proliferating cell nuclear antigen expression in the hypertrophic myocardium. EGCG remarkably inhibited pressure overload-induced c-myc increase in Western blot analysis. In cultured newborn rat cardiac fibroblasts, treatment with EGCG at 12.5 - 200 mg/L for 6 - 48 h decreased cell proliferation induced by serum. EGCG at 12.5 - 100 mg/L dose-dependently inhibited cell proliferation and DNA synthesis of fibroblasts induced by angiotensin II (Ang II) at 1 mumol/L. EGCG also significantly increased nitrite levels in culture medium, and up-regulated inducible nitric oxide synthase protein expression if compared with the Ang II group. The inhibitory effect of EGCG on cell proliferation induced by Ang II was partly blocked by pretreatment with N(omega)-nitro- L-arginine methyl ester hydrochloride. These results suggest that EGCG inhibits the proliferation of cardiac fibroblasts both in vivo and in vitro, thereby preventing myocardial fibrosis in cardiac hypertrophy. EGCG might exert its cardiac protective action through induction of NO production.

EGCG inhibits cardiomyocyte apoptosis in pressure overload-induced cardiac hypertrophy and protects cardiomyocytes from oxidative stress in rats.

AIM: To investigate the effects of epigallocatechin gallate (EGCG) on pressure overload and hydrogen peroxide (H2O2) induced cardiac myocyte apoptosis. METHODS: Cardiac hypertrophy was established in rats by abdominal aortic constriction. EGCG 25, 50 and 100 mg/kg were administered intragastrically (ig). Cultured newborn rat cardiomyocytes were preincubated with EGCG, and oxidative stress injury was induced by H2O2. RESULTS: In cardiac hypertrophy induced by AC in rats, relative to the model group, EGCG 25, 50 and 100 mg/kg ig for 6 weeks dose-dependently reduced systolic blood pressure (SBP) and heart weight indices, decreased malondialdehyde (MDA) content, and increased superoxide dismutase (SOD) and glutathione peroxidase (GSH-PX) activity, both in serum and in the myocardium. Also, treatment with EGCG 50 and 100 mg/kg markedly improved cardiac structure and inhibited fibrosis in HE and van Gieson (VG) stain, and reduced apoptotic myocytes in the hypertrophic myocardium detected by terminal transferase-mediated dUTP-biotin nick end-labeling (TUNEL) assay. In the Western blot analysis, EGCG significantly inhibited pressure overload-induced p53 increase and bcl-2 decrease. In H2O2-induced cardiomyocyte injury, when preincubated with myocytes for 6-48 h, EGCG 12.5-200 mg/L increased cell viability determined by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. EGCG also attenuated H2O2-induced lactate dehydrogenase (LDH) release and MDA formation. Meanwhile, EGCG 50 and 100 mg/L significantly inhibited the cardiomyocyte apoptotic rate in flow cytometry. CONCLUSION: EGCG inhibits cardiac myocyte apoptosis and oxidative stress in pressure overload induced cardiac hypertrophy. Also, EGCG prevented cardiomyocyte apoptosis from oxidative stress in vitro. The mechanism might be related to the inhibitory effects of EGCG on p53 induction and bcl-2 decrease.

[Experimental study on treatment of allergic asthma guinea pigs with different fractions of Modified Zhisousan].

OBJECTIVE: To study the effects of different fractions of Modified Zhisousan (MZ, MZC, MZS) on the contents of nitric oxide (NO), endothelin-1 (ET-1) and eosinophilia (EOS) in the allergic asthma guinea pigs and observe the pathology changes of lung tissue. METHODS: The number of EOS in the blood and bronchialveolar lavage fluid (BALF) was counted by Wright staining. The contents of ET-1 and No in serum and BALF were analyzed by RIA and nitric acid reductase method. The guinea pig lungs were observed under the optical and electron microscope. RESULTS: The number of EOS and the contents of ET-1 and NO in model group were higher than those in control group (P < 0.01). The pathological changes of lung were obvious. The number of EOS and the contents of ET-1 and NO were descended remarkably (P < 0.05 or P < 0.01) and the pathological changes in the lung tissue were lightened obviously in MZ and MZC groups, but MZS group had no such effects. CONCLUSION: MZC is the effective part of MZ and the anti-asthmatic mechanisms ware related to its significant reduction in contents of ET-1, NO, EOS and the damage of lung tissue possibly.

Effect of Astragalus complanatus flavonoid on anti-liver fibrosis in rats.

AIM: To observe the anti-liver fibrosis effect of Astragalus complanatus flavonoids (ACF) in rats. METHODS: The liver fibrosis model in rats was established by injecting interperitoneally 0.2 mL/100 g 0.5% dimethylnitrosamine, thrice a week. Meanwhile, the rats were administered ACF (30, 60, 120 mg/kg) or colchicine (0.1 mg/kg) once a day for 1 mo. Serum N-propeptide of type I procollagen (PINP) and type III procollagen (PIIINP) were measured using ELISA. Malondialdehyde (MDA) and superoxide dismutase (SOD) in hepatic tissue were evaluated. Matrix metal protease-1 (MMP-1) mRNA expression was assayed by RT-PCR and the protein expression of tissue inhibitor of metal protease-1 (TIMP-1) was analyzed by immunohistochemistry. RESULTS: In the ACF groups, SOD activity increased and MDA content decreased in comparison to the liver fibrosis model group. The serum PINP and PIIINP contents in ACF-2 and -3 group decreased compared to those in model group. In ACF-2 and -3 group, the expression of MMP-1 mRNA increased significantly and the protein expression of TIMP-1 decreased compared to that in model group. CONCLUSION: The antifibrotic mechanisms of ACF are associated with its influence on lipid peroxidation and collagen synthesis and degradation.

Effects of xiaoyu tablet on endothelin-1, nitric oxide, and apoptotic cells of atherosclerotic vessel wall in rabbits.

AIM: To investigate the mechanism of xiaoyu tablet on reduction of smooth muscle cells (SMC) in atherosclerotic vessel wall. METHODS: The atherosclerotic model was performed in male New Zealand rabbits that were given high fat diet and abrasion of the abdominal aorta endothelial cells. The rabbits were then administered with xiaoyu tablet 0.16-0.32 g x kg(-1) x d(-1) for 16 weeks. Changes in morphology, endothelin (ET)-1, nitric oxide (NO), and apoptotic cells of atherosclerotic vessel wall were determined by the microscopy, radioimmunoassay, colorimetric method, the techniques of DNA in situ end labeling, and image pattern analysis, respectively. RESULTS: After 16 weeks of xiaoyu tablet treatment, intimal thickness and SMC in atherosclerotic vessel wall were diminished, ET-1 was decreased by 8.2 %-42.6 %, NO was increased by 7.5 %-54.2 %, and labeled apoptotic nuclei were markedly decreased, the area and integral optical density of positive granule were (846+/-308) microm2 and 3425+/-1374 in atherosclerotic group and (225+/-60) microm2 and 1445+/-606 in xiaoyu tablet 0.32 g/kg group, respectively. CONCLUSION: Xiaoyu tablet not only inhibited proliferation of SMC through reducing ET-1 in atherosclerotic vessel wall, but also induced apoptosis of SMC by increasing NO in vessel wall.