Increasing Area and Decreasing Depth: Climate Change Influence on Snow Variations in the Qilian Mountains

The Qilian Mountains serve as a critical water source for the Yellow River and various inland rivers, playing a pivotal role in regulating the regional climate. Given their significance as one of the foremost water resources in the area, the spatial and temporal dynamics of the snow are crucial for understanding potential impacts on regional hydrology and ecology. This study examines the characteristics of spatial and temporal variations in snow-covered extent (SCE), snow depth (SD), snow-covered days (SCD), snow onset date (SOD), and snow end date (SED) within the Qilian Mountains region. We investigate the hydrological and ecological implications utilizing snow area and phenology data, alongside SD data. The findings indicate that: (1) the distribution of snow across the Qilian Mountains mainly splits between the central and western areas, with the central region showing deeper snow than both the eastern and western parts; (2) the area covered by snow in the Qilian Mountains is growing, but the depth of the snow is on a decline, especially in the central area; (3) in terms of snow phenology, most of the region is witnessing an earlier start of SOD, a longer SCD, and an earlier SED. An overall increase in precipitation is identified as the key factor behind the expanded SCE in the Qilian Mountains, while rising temperatures are pinpointed as the primary cause for the reduction in SD. As global climate change intensifies, the observed alterations in the snow of the Qilian Mountains present emerging challenges for regional water security and ecological equilibrium

Erythropoietin Receptor Signaling Mitigates Renal Dysfunction-Associated Heart Failure by Mechanisms Unrelated to Relief of Anemia

ObjectivesWe examined the effect of asialoerythropoietin (asialoEPO), a nonerythrogenic derivative of erythropoietin (EPO), on renal dysfunction-associated heart failure.BackgroundAlthough EPO is known to exert beneficial effects on cardiac function, the clinical benefits in patients with chronic kidney disease are controversial. It remains to be addressed whether previously reported outcomes were the result of relief of the anemia, adverse effects of EPO, or direct cardiovascular effects.MethodsMice underwent 5/6 nephrectomy to cause renal dysfunction. Eight weeks later, when renal dysfunction was established, anemia and cardiac dysfunction and remodeling were apparent. Mice were then assigned to receive saline (control), recombinant human erythropoietin (rhEPO) at 5,000 IU (714 pmol)/kg, or asialoEPO at 714 pmol/kg, twice/week for 4 weeks.ResultsAlthough only rhEPO relieved the nephrectomy-induced anemia, both rhEPO and asialoEPO significantly and similarly mitigated left ventricular dilation and dysfunction. The hearts of rhEPO- or asialoEPO-treated mice showed less hypertrophy, reflecting decreases in cardiomyocyte hypertrophy and degenerative subcellular changes, as well as significant attenuation of fibrosis, leukocyte infiltration, and oxidative deoxyribonucleic acid damage. These phenotypes were accompanied by restored expression of GATA-4, sarcomeric proteins, and vascular endothelial growth factor and decreased inflammatory cytokines and lipid peroxidation. Finally, myocardial activation was observed of extracellular signal-regulated protein kinase and signal transducer and activator of transcription pathways in the treated mice.ConclusionsEPO receptor signaling exerts direct cardioprotection in an animal model of renal dysfunction-associated heart failure, probably by mitigating degenerative, pro-fibrosis, inflammatory, and oxidative processes but not through relief of anemia

Bubble dynamics and forced convection boiling heat transfer with low velocity.

The velocity potentials of a sphere moving and/or growing in an inviscid liquid near a wall have been constructed. The dynamic force associated with the various motions of the sphere are obtained. For the case of a sphere touching a plane while moving parallel to it, the force coefficient is found to be 0.577771 which is more than 10% larger than the earlier estimate of 0.51435 by Miloh. Exact solutions of the dynamic force and the kinetic energy are obtained for a bubble growing on a wall. Analyses are also given for the unbalanced molecular momentum force on a vapor bubble due to the nonuniform evaporation/condensation around the liquid-vapor interface. Forced convection nucleate boiling experiments with two levels of subcooling and velocity (7.4 and 12.9\sp\circC; 1.7 and 4.3 cm/s) at three surface orientations (vertical, horizontal up and horizontal down) are conducted with R-113 using both semi-transparent thin gold film and gold-coated copper flat heaters. The test conditions were accurately controlled throughout the experiments with an uncertainty of $\pm$1% in velocity, $\pm$0.172 kPa in pressure (corresponding to $\pm$0.06\sp\circC in saturation temperature), and $\pm$0.06\sp\circC in temperature. Experimental results show that in the range of velocity and subcooling tested, bubble departures are dominated by buoyancy; for both copper and quartz heaters subcooling and velocity have no appreciable effect on the heat transfer from the horizontal up surface; copper heaters generally have lower surface superheat than the thin gold film heaters at a given level of heat flux; for copper heaters, the horizontal up surface has lower surface superheat than vertical surface; for the gold film heaters, heat transfer on vertical surfaces is enhanced by increasing the subcooling, is insensitive to increasing velocity when the subcooling is low, and is degraded when the subcooling is high; for both types of heaters, the horizontal downward facing surface has a very low level of heat flux compared to the horizontal up and vertical surface for the same surface superheat.Ph.D.Applied SciencesMechanical engineeringMechanicsUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/129136/2/9332120.pd

Phosphodiesterase 5a Inhibition with Adenoviral Short Hairpin RNA Benefits Infarcted Heart Partially through Activation of Akt Signaling Pathway and Reduction of Inflammatory Cytokines.

Treatment with short hairpin RNA (shRNA) interference therapy targeting phosphodiesterase 5a after myocardial infarction (MI) has been shown to mitigate post-MI heart failure. We investigated the mechanisms that underpin the beneficial effects of PDE5a inhibition through shRNA on post-MI heart failure.An adenoviral vector with an shRNA sequence inserted was adopted for the inhibition of phosphodiesterase 5a (Ad-shPDE5a) in vivo and in vitro. Myocardial infarction (MI) was induced in male C57BL/6J mice by left coronary artery ligation, and immediately after that, the Ad-shPDE5a was injected intramyocardially around the MI region and border areas.Four weeks post-MI, the Ad-shPDE5a-treated mice showed significant mitigation of the left ventricular (LV) dilatation and dysfunction compared to control mice. Infarction size and fibrosis were also significantly reduced in Ad-shPDE5a-treated mice. Additionally, Ad-shPDE5a treatment decreased the MI-induced inflammatory cytokines interleukin (IL)-1β, IL-6, tumor necrosis factor-α, and transforming growth factor-β1, which was confirmed in vitro in Ad-shPDE5a transfected myofibroblasts cultured under oxygen glucose deprivation. Finally, Ad-shPDE5a treatment was found to activate the myocardial Akt signaling pathway in both in vivo and in vitro experiments.These findings indicate that PDE5a inhibition by Ad-shPDE5a via the Akt signal pathway could be of significant value in the design of future therapeutics for post-MI heart failure