Study of static and dynamic performances of miniature Savonius-type wind energy harvesters

Non-polluting and renewable wind energy harnessed by means of large-scale wind turbines has been well-studied and applied. However, the development of miniature wind energy harvesters is left behind due to little attention and effort. In this work, a miniature air-driven Savonius-type energy harvester is three-dimensionally designed. The energy harvester is 3D printed and experimentally tested. Experimental results prove the energy harvester to be associated with a cut-in Reynolds number of 5.95×105 and the maximum overall energy conversion efficiency of 5.16% approximately. To better understand the static and dynamic performances of the designed energy harvester, three-dimensional numerical study is conducted to simulate the experiment. Based on both experimental and numerical results, means to enhance energy harvester's static and dynamic performance are proposed and validated. It is shown that with improved designs, the cut-in Reynolds number can be reduced to 4.33×105 and the overall energy conversion efficiency can be increased to approximately 6.59%.MOE (Min. of Education, S’pore)Published versio

Large-Scale Qualitative and Quantitative Assessment of Dityrosine Crosslinking Omics in Response to Endogenous and Exogenous Hydrogen Peroxide in <i>Escherichia coli</i>

Excessive hydrogen peroxide causes oxidative stress in cells. The oxidation of two tyrosine residues in proteins can generate o,o′-dityrosine, a putative biomarker for protein oxidation, which plays critical roles in a variety of organisms. Thus far, few studies have investigated dityrosine crosslinking under endogenous or exogenous oxidative conditions at the proteome level, and its physiological function remains largely unknown. In this study, to investigate qualitative and quantitative dityrosine crosslinking, two mutant Escherichia coli strains and one mutant strain supplemented with H2O2 were used as models for endogenous and exogenous oxidative stress, respectively. By integrating high-resolution liquid chromatography—mass spectrometry and bioinformatic analysis, we created the largest dityrosine crosslinking dataset in E. coli to date, identifying 71 dityrosine crosslinks and 410 dityrosine loop links on 352 proteins. The dityrosine-linked proteins are mainly involved in taurine and hypotaurine metabolism, citrate cycle, glyoxylate, dicarboxylate metabolism, carbon metabolism, etc., suggesting that dityrosine crosslinking may play a critical role in regulating the metabolic pathways in response to oxidative stress. In conclusion, we have reported the most comprehensive dityrosine crosslinking in E. coli for the first time, which is of great significance in revealing its function in oxidative stress

Nonlinear dynamic measurement of self-sustained thermoacoustic oscillations in a swirling combustor with a heat exchanger

Energy transfer from heat to sound is unwanted in many propulsion systems, including gas turbines and rocket motors. However, it is favorable in some practical applications, such as thermoacoustic heat engines or cooling systems. The present work considers an experimental investigation of self-sustained thermoacoustic oscillations in a swirling combustor. Both subcritical and supercritical Hopf bifurcations are found to occur in this swirling combustor. In the presence of the subcritical bifurcation, a small change in the equivalent ratio leads to a sudden/hard jump from steady state to large amplitude limit cycle oscillations. The experimental study sheds lights on the heat-to-sound conversion process. In addition to increase the heat-to-sound energy conversion, an innovative water-involved heat exchanger is designed and experimentally implemented on the swirling combustor. By doing this, self-excited thermoacoustic oscillations are found to be intensified. The present work opens up a new applicable way to amplify thermoacoustic oscillations in swirling combustion systems.MOE (Min. of Education, S’pore)Published versio

PS1 Affects the Pathology of Alzheimer’s Disease by Regulating BACE1 Distribution in the ER and BACE1 Maturation in the Golgi Apparatus

Neuritic plaques are one of the major pathological hallmarks of Alzheimer’s disease. They are formed by the aggregation of extracellular amyloid-β protein (Aβ), which is derived from the sequential cleavage of amyloid-β precursor protein (APP) by β- and γ-secretase. BACE1 is the main β-secretase in the pathogenic process of Alzheimer’s disease, which is believed to be a rate-limiting step of Aβ production. Presenilin 1 (PS1) is the active center of the γ-secretase that participates in the APP hydrolysis process. Mutations in the PS1 gene (PSEN1) are the most common cause of early onset familial Alzheimer’s disease (FAD). The PSEN1 mutations can alter the activity of γ-secretase on the cleavage of APP. Previous studies have shown that PSEN1 mutations increase the expression and activity of BACE1 and that BACE1 expression and activity are elevated in the brains of PSEN1 mutant knock-in mice, compared with wild-type mice, as well as in the cerebral cortex of FAD patients carrying PSEN1 mutations, compared with sporadic AD patients and controls. Here, we used a Psen1 knockout cell line and a PS1 inhibitor to show that PS1 affects the expression of BACE1 in vitro. Furthermore, we used sucrose gradient fractionation combined with western blotting to analyze the distribution of BACE1, combined with a time-lapse technique to show that PS1 upregulates the distribution and trafficking of BACE1 in the endoplasmic reticulum, Golgi, and endosomes. More importantly, we found that the PSEN1 mutant S170F increases the distribution of BACE1 in the endoplasmic reticulum and changes the ratio of mature BACE1 in the trans-Golgi network. The effect of PSEN1 mutations on BACE1 may contribute to determining the phenotype of early onset FAD

Deep Membrane Proteome Profiling of Rat Hippocampus in Simulated Complex Space Environment by SWATH

Despite the development and great progress in the field of space biology, the astronauts are still facing many challenges in space. The space environment in which astronauts stay includes microgravity, noise, circadian rhythms disorder, and confinement, which has deep effect both on the physiology and psychology of astronauts. It was reported that long-term flight could cause the astronauts’ anxiety and depression. However, the underlying mechanism is not yet fully understood. Therefore, in the present study, the rat tail suspension model with noise, circadian rhythms, and confinement was employed to simulate complex space environment. We found that the rats exhibited the depressive-like behavior by the sucrose preference, forced swimming, and open-field tests. The membrane proteome of the rat hippocampus was investigated by “SWATH quantitation” technology both in control and simulated complex space environment (SCSE) groups. Out of 4520 quantified proteins, 244 differentially expressed membrane proteins were obtained between the SCSE and control rats, which were functionally enriched in a series of biological processes, such as translation, protein phosphorylation, brain development, endocytosis, nervous system development, axonogenesis, and vesicle-mediated transport. We found a reduction level of neurexin-2, the light, medium, heavy polypeptide of neurofilament, rab 18, synaptogyrin 1, and syntaxin-1A and an increase level of neuroligin-1, munc18, snapin, synaptotagmin XII, complexin-1, etc., which may play a key part in the development of depression. Furthermore, GSK-3β protein was upregulated in mass spectrometry, which was further validated by western blotting. The results of the study do the favor in designing the effective countermeasures for the astronauts in the future long-term spaceflight

Levo-Tetrahydroberberrubine Produces Anxiolytic-Like Effects in Mice through the 5-HT1A Receptor.

Tetrahydroprotoberberines (THPBs) are isoquinoline alkaloids isolated from the Chinese herb Corydalis yanhusuo. In the present study, we performed competitive binding assays to examine the binding of l-THBr to neurotransmitter receptors known to be involved in sedation, hypnosis and anxiety. Our results show that l-THBr does not interact with GABAergic receptors but has binding affinities for dopamine and serotonin receptors. In addition, cAMP and [35S]GTPγS assays were used to determine the agonist or antagonist properties of l-THBr at dopamine (D1, D2) or serotonin (5-HT) receptors. Our results show that l-THBr displays D1 and D2 antagonist and 5-HT1A agonist properties. Moreover, l-THBr-treated rodents exhibit anxiolytic-like effects in the light/dark box and elevated plus-maze tests, and the anxiolytic effect of l-THBr can be reduced by WAY-100635, a selective 5-HT1A receptor antagonist. Our results suggest that l-THBr may produce potent anxiolytic-like effects mainly through serotonin receptors

hVMAT2: A Target of Individualized Medication for Parkinson's Disease

Vesicular monoamine transporter 2 (VMAT2) is responsible for sequestering cytosolically toxic dopamine into intracellular secretory vesicles. Animal genetic studies have suggested that reduced VMAT2 activity contributes to the genetic etiology of Parkinson's disease (PD), but this role has not been established in humans. Based on human genetic association and meta-analysis, we first confirm the human VMAT2 (hVMAT2 or SLC18A2) promoter as a risk factor for PD in both family and unrelated US white people: marker rs363324 at -11.5 kb in the hVMAT2 promoter is reproducibly associated with PD in a cohort of nuclear families (p = 0.04506 in early-onset PD) and 3 unrelated US white people (meta-analysis p = 0.01879). In SH-SY5Y cells, low activity-associated hVMAT2 promoter confers high methylpiperidinopyrazole iodide cytotoxicity, which is likely attributed to functional polymorphisms bound by nuclear proteins. Interestingly, treatments with the dopamine neuron-protecting agent puerarin upregulates the promoter activity in a haplotype- and cell line-dependent manner. These pharmacogenetic findings suggest that hVMAT2 could be a risk factor and imply it as a target of genetic medications for PD

Anti-tumour activity of zinc ionophore pyrithione in human ovarian cancer cells through inhibition of proliferation and migration and promotion of lysosome-mitochondrial apoptosis

AbstractZinc pyrithione (ZPT) is widely used as an antimicrobial. Zinc is a necessary trace element of the human whose homeostasis associated with several cancers. However, the anticancer effect of increased Zinc in ovarian cancer is still unclear. This study focussed on the anti-tumour effects of ZPT combined with Zinc in SKOV3 and SKOV3/DDP cells. The cell viability, apoptosis, migration, and invasion assays were detected by CCK-8, flow cytometry, wound healing and transwell assay, respectively. The distribution of Zinc in cells was monitored by staining of Zinc fluorescent dye and lysosome tracker. The changes in lysosomal membrane stability were reflected by acridine orange fluorescence and cathepsin D reposition. Expression of the proteins about invasion and apoptosis was evaluated by western blot. The results indicated that ZPT combined with Zinc could notably reduce cell viability, inhibit migration and invasion in SKOV3 and SKOV3/DDP cells. Besides, ZPT performed as a Zinc carrier targeted lysosomes, caused the increase of its membrane permeability and the release of cathepsin D accompanied by mitochondrial apoptosis in SKOV3/DDP cells. In conclusion, our work suggests that ZPT combined with Zinc could inhibit proliferation, migration, invasion, and promote apoptosis by trigger the lysosome-mitochondrial apoptosis pathway in ovarian carcinoma