Search

This study proposes an improved microcombustor with a rectangular rib to improve the temperature level of the combustor wall. Moreover, the OH mass fraction, temperature distribution, and outer wall temperature of the original and improved combustors of premixed hydrogen/air flames are numerically investigated under various inlet velocities and equivalence ratios. Results show that the improved microcombustor enhances heat transfer between the mixture and wall because its recirculation zone is larger than that of the original, thereby resulting in high wall temperature. Conversely, thermal resistance in the horizontal direction increases with upstream and downstream step lengths. Consequently, the outer wall temperature decreases with step length in the improved combustor. A high equivalence ratio (e.g., 0.6) may result in the destruction of the combustor because the wall temperature has exceeded the acceptable temperature of wall material quartz. Therefore, the improved microcombustor is recommended for micro-thermo-photovoltaic systems.

Objective: This study aims to investigate the possible cause of a prenatal case of hemivertebrae with a 7q terminal deletion. Case Report: This case describes a fetus with hemivertebrae in thoracic vertebrae as the sole antenatal sonographic finding. Genetic testing was performed in order to find more information after the abnormal ultrasound finding. The array-based comparative genomic hybridization results showed that the fetus had approximately 6.4 Mb deletion of 7q36. We discussed the two genes (SHH and HLXB9) that may be associated with hemivertebrae in the deletion region and reviewed several literatures about 7q36 deletion. Conclusion: Our results suggest that the phenotype of hemivertebra in our case may be related to the deletion of 7q36.

DNA methylation plays a crucial role in environmental adaptations. Here, using whole-genome bisulfite sequencing, we generated comprehensive genome-wide DNA methylation profiles for the high-altitude Yunnan snub-nosed monkey (Rhinopithecus bieti) and the closely related golden snub-nosed monkey (R. roxellana). Our findings indicated a slight increase in overall DNA methylation levels in golden snub-nosed monkeys compared to Yunnan snub-nosed monkeys, suggesting a higher prevalence of hypermethylated genomic regions in the former. Comparative genomic methylation analysis demonstrated that genes associated with differentially methylated regions were involved in membrane fusion, vesicular formation and trafficking, hemoglobin function, cell cycle regulation, and neuronal differentiation. These results suggest that the high-altitude-related epigenetic modifications are extensive, involving a complete adaptation process from the inhibition of single Ca2+ channel proteins to multiple proteins collaboratively enhancing vesicular function or inhibiting cell differentiation and proliferation. Functional assays demonstrated that overexpression or down-regulation of candidate genes, such as SNX10, TIMELESS, and CACYBP, influenced cell viability under stress conditions. Overall, this research suggests that comparing DNA methylation across closely related species can identify novel candidate genomic regions and genes associated with local adaptations, thereby deepening our understanding of the mechanisms underlying environmental adaptations. [ABSTRACT FROM AUTHOR]

The timing of mammalian diversification in relation to the Cretaceous-Paleogene (KPg) mass extinction continues to be a subject of substantial debate. Previous studies have either focused on limited taxonomic samples with available whole-genome data or relied on short sequence alignments coupled with extensive species samples. In the present study, we improved an existing dataset from the landmark study of Meredith et al. (2011) by filling in missing fragments and further generated another dataset containing 120 taxa and 98 exonic markers. Using these two datasets, we then constructed phylogenies for extant mammalian families, providing improved resolution of many conflicting relationships. Moreover, the timetrees generated, which were calibrated using appropriate molecular clock models and multiple fossil records, indicated that the interordinal diversification of placental mammals initiated before the Late Cretaceous period. Additionally, intraordinal diversification of both extant placental and marsupial lineages accelerated after the KPg boundary, supporting the hypothesis that the availability of numerous vacant ecological niches subsequent to the mass extinction event facilitated rapid diversification. Thus, our results support a scenario of placental radiation characterized by both basal cladogenesis and active interordinal divergences spanning from the Late Cretaceous into the Paleogene. [ABSTRACT FROM AUTHOR]

A compact tri-band power divider based on triple-mode resonator is proposed in this paper. This tri-mode resonator comprises a conventional half-wavelength resonator, a short stub and an open stub. The interdigital coupled-lines are introduced at the input and the output to improve the performance of this power divider. The proposed tri-band power divider working at 1.57 GHz, 2.45 GHz, 3.50 GHz is simulated and fabricated, and good agreement between the simulated results and the measured results are observed. [ABSTRACT FROM AUTHOR]

We aimed to clarify the different angiogenesis effects of mini-tyrosyl-tRNA synthetase (TyrRS)/minitryptophanyl-tRNA synthetase (TrpRS) in rodent primates with acute myocardial infarction, by delivering small interfering RNAs (siRNAs) systemically in a liposomal formulation. Left coronary artery ligation was used to establish the model of acute myocardial infarction in rats; mini-TyrRS/mini-TrpRS-specific siRNAs were encapsulated in stable nucleic acid lipid particles (SNALP), and administered by intravenous injection to rats. Rats were divided into four experiment groups: sham operated group (no left anterior descending artery [LAD] occlusion); negative control group (LAD occlusion + saline injection); mock transfection group (LAD occlusion + mock transfected injection); experiment group (LAD occlusion + mini-TyrRS/mini-TrpRS-specific siRNAs injection). Silencing efficiency was assayed by Western blotting. To determine whether mini-TyrRS/mini-TrpRS affected the angiogenesis activity of rats with myocardial infarction, we measured the myocardial infarction size by TTC staining, and the capillary density using immunohistochemistry staining, to investigate the expression of factor VIII. The myocardial infarction size and the capillary density of mini-TyrRS-siRNA group were respectively 18.89% and 8.64/0.1 mm2 1 month after ligation, while in the mini-TrpRS-siRNA group these values were 7.33% and 17.32/0.1 mm2, significantly different compared with the mock transfection group (14.19%; 13.56/0.1 mm2) and negative control group (14.28%; 13.89/0.1 mm2), P < 0.05. There were no significant changes between the mock transfection group and the negative control group, P > 0.05. These results indicated that angiogenesis is either stimulated by mini-TyrRS or inhibited by mini-TrpRS in rat models with acute myocardial infarction. [ABSTRACT FROM AUTHOR]

Hypoxia-inducible factor (HIF)-1α and-2α have diverse actions on the myocardium, but the importance of direct effects on cardiac myocytes is unclear. To define their regional accumulation and association with cardiomyocyte cell cycle change after myocardial infarction (MI), a rat MI model was established by occluding the coronary arteries. To further prove a causative relationship between HIF and cell cycle regulation, cultured cardiomyocytes were transfected with adenoviral vectors carrying HIF-1α and HIF-2α. Two weeks after MI, both HIF-1α and HIF-2α mRNA were moderately increased in the infarcted left ventricle and noninfarcted left ventricle; HIF-2α amplification was also detected in areas of the interventricular septum and the right ventricle. In concordance with the changes in mRNA levels, immunohistochemistry signals of HIF-1α and HIF-2α were characterized by different regional distributions. In the myocardium adjacent to the infarcted tissue, a significant correlation between HIF-1α or HIF-2α and Ki-67 labeling index was observed ( P < 0.001). Immunohistochemical double staining showed that HIF positive cardiomyocytes underwent DNA synthesis. Cardiomyocytes treated with HIF-1α or -2α expressed Ki-67, phosphohistone H3, and bromodeoxyuridine effectively in vitro. In conclusion, HIF-1α and HIF-2α had a distinct spatial expression pattern in a rat model of ischemic heart disease. Both HIF subunits might be potent stimuli for cardiomyocytes to re-enter the cell cycle and initiate DNA synthesis. [ABSTRACT FROM AUTHOR]

Magnetic properties and magnetization processes of Co nanowire arrays with various packing densities are investigated by means of object-oriented micromagnetic framework (OOMMF) software package with finite difference micromagnetic simulations. The packing density of nanowires is changed with the diameter, number of nanowires and center-to-center spacing between the wires. The magnetization reversal mechanism and squareness of the hysteresis loops of the nanowire arrays are very sensitive to the packing density of nanowires. Clear steps and plateaux on the demagnetization are visible, which turns out that dipolar interactions among the wires have a significant influence on switching field. [ABSTRACT FROM AUTHOR]