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31.
Hui Huang Bradi R. Lorenz Paula Horn Zelmanovitz Catherine B. Chan 《International journal of molecular sciences》2021,22(1)
Prediabetes is a high-risk condition for type 2 diabetes (T2D). Pancreatic β-cells adapt to impaired glucose regulation in prediabetes by increasing insulin secretion and β-cell mass expansion. In people with prediabetes, metformin has been shown to prevent prediabetes conversion to diabetes. However, emerging evidence indicates that metformin has negative effects on β-cell function and survival. Our previous study established the Nile rat (NR) as a model for prediabetes, recapitulating characteristics of human β-cell compensation in function and mass expansion. In this study, we investigated the action of metformin on β-cells in vivo and in vitro. A 7-week metformin treatment improved glucose tolerance by reducing hepatic glucose output and enhancing insulin secretion. Although high-dose metformin inhibited β-cell glucose-stimulated insulin secretion in vitro, stimulation of β-cell insulin secretion was preserved in metformin-treated NRs via an indirect mechanism. Moreover, β-cells in NRs receiving metformin exhibited increased endoplasmic reticulum (ER) chaperones and alleviated apoptotic unfold protein response (UPR) without changes in the expression of cell identity genes. Additionally, metformin did not suppress β-cell mass compensation or proliferation. Taken together, despite the conflicting role indicated by in vitro studies, administration of metformin does not exert a negative effect on β-cell function or cell mass and, instead, early metformin treatment may help protect β-cells from exhaustion and decompensation. 相似文献
32.
Parkinson’s disease (PD) is a neurodegenerative disorder that affects 1% of the population over the age of 60. Diabetes Mellitus (DM) is a metabolic disorder that affects approximately 25% of adults over the age of 60. Recent studies showed that DM increases the risk of developing PD. The link between DM and PD has been discussed in the literature in relation to different mechanisms including mitochondrial dysfunction, oxidative stress, and protein aggregation. In this paper, we review the common microRNA (miRNA) biomarkers of both diseases. miRNAs play an important role in cell differentiation, development, the regulation of the cell cycle, and apoptosis. They are also involved in the pathology of many diseases. miRNAs can mediate the insulin pathway and glucose absorption. miRNAs can also regulate PD-related genes. Therefore, exploring the common miRNA biomarkers of both PD and DM can shed a light on how these two diseases are correlated, and targeting miRNAs is a potential therapeutic opportunity for both diseases. 相似文献
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34.
《International Journal of Hydrogen Energy》2022,47(3):1954-1964
Recently, researchers have devoted more attention to supercapacitors (SCs) to integrate with batteries in energy storage systems (ESSs) for vehicle applications. In this study, we attempted to characterize the use of SCs in the ESS for a PEM fuel cell vehicle equipped with an alternator to maximize the performance of regenerative braking. We applied lithium-ion batteries (LIBs) and SCs as energy storage devices to examine their effect on ESS. Then we used a hysteresis brake to apply controllable braking force on the flywheel to form hybrid braking (HB) and made efforts to study its behavior to suggest a braking control strategy. We also ran the whole system over the rotational speed to cover the range of driving speed. At last, we sized the SCs for the most commonly used fuel cell electric vehicle (FCEV) in Korea, i.e., Hyundai NEXO, based on the results obtained from the above study by alternator efficiencies. 相似文献
35.
《International Journal of Hydrogen Energy》2022,47(3):1752-1764
Subsurface hydrogen (H2) storage in geological formations is of growing interest for decarbonization. However, there is a knowledge gap in understanding the multiphase flow involved in this process, which can have a significant impact on the recovery performance of H2. Therefore, a full-compositional modeling study was conducted to analyze potential issues and to understand the fundamental hydrodynamic mechanisms of H2 storage. We performed a range of 2D vertical simulations at the decametre scale with a very fine cell size (0.1 m) to observe the detailed flow behaviour of H2 with carbon dioxide (CO2) as cushion gas in various flow regimes. Issues such as viscous instability, capillary bypassing, gas trapping and gravity segregation are analysed here. To generalize our calculations, we have validated and applied the scaling theory in the context of subsurface H2 storage. Since this study is focused on the hydrodynamic behaviour, three dimensionless groups, including aspect factor, capillary/viscous ratio and gravity/viscous ratio were identified to correlate recovery performance between various scales in a fixed heterogeneous system. It was found that H2 could infiltrate the cushion gas in the proximity of the injectors, meaning that CO2 is not displaced away from the injectors in a piston-like fashion. As a result, the purity of the back produced H2 is much degraded, particularly in a viscous-dominated scenario. On the other hand, the injected H2 mostly accumulates at the top forming a highly restricted mixing zone with CO2 in the gravity-dominated case. The recovery performance is therefore much improved in this case. Although the gas distribution can be significantly altered by capillary forces leading to bypassed zones, the recovery performance of H2 is hardly influenced. This is because the back-produced H2 recovery is not dependent on the sweep efficiency of the gas. H2 can be back produced following the same paths which were formed during injection. 相似文献
36.
《International Journal of Hydrogen Energy》2022,47(14):8883-8891
A series of novel branched sulfonated polyimide (bSPI-x) membranes with 8% branched degree are developed for application in vanadium redox flow battery (VRFB). The sulfonation degrees of bSPI-x membranes are precisely regulated for obtaining excellent comprehensive performance. Among all bSPI-x membranes, the bSPI-50 membrane shows strong vanadium permeability resistance, which is as 8 times as that of commercial Nafion 212 membrane. At the same time, the bSPI-50 membrane has remarkable proton selectivity, which is four times as high as that of Nafion 212 membrane. The bSPI-50 membrane possesses slower self-discharge speed than Nafion 212 membrane. Furthermore, the bSPI-50 membrane achieves stable VRFB efficiencies during 200-time charge-discharge cycles at 120–180 mA cm?2. Simultaneously, the bSPI-50 membrane exhibits excellent capacity retention compared with Nafion 212 membrane. All results imply that the bSPI-50 membrane possesses good application prospect as a promising alternative separator of VRFB. 相似文献
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38.
利用水力空化过程产生局部的高温、高压、高射流以及强大的剪切力等极端化学物理条件改质处理沙特重质原油,试验结果表明:沙特重质原油经过水力空化改质后粘度由13.61降低至7.22mm2/s,残碳由7.16%降低至6.48%,实沸点蒸馏后减压渣油降低1个百分点。进一步采用APPI FT-IR MS、XRD、FT-IR、SEM和粒度分布等技术研究了水力空化改质对沙重原油分子组成,沥青质团聚体微晶结构、沥青质胶束粒径分布、沥青质官能团、沥青质形貌等方面的影响,从分子角度阐述空化改质重油的机理。研究结果表明:水力空化改质后沙重原油分子量分布、芳烃类化合物缔合作用变小;沥青质对低DBE化合物吸附性能降低;沥青质团聚体微晶结构更加松散;沥青质胶束粒度分布降低;沥青质分子相互团聚作用力减弱。进一步考察了水力空化改质前后减压渣油延迟焦化性能,改质处理后焦炭产率降低1.85个百分点,液体收率和气体产率分别增加1.52和0.33个百分点,水力空化改质对沥青质性质、结构特点的改善能够有效的提高其加工性能。 相似文献
39.
40.
《International Journal of Hydrogen Energy》2022,47(37):16335-16346
Oxygen blocking the porous transport layer (PTL) increases the mass transport loss, and then limits the high current density condition of proton exchange membrane electrolysis cells (PEMEC). In this paper, a two-dimensional transient mathematical model of anode two-phase flow in PEMEC is established by the fluid volume method (VOF) method. The transport mechanism of oxygen in porous layer is analyzed in details. The effects of liquid water flow velocity, porosity, fiber diameter and contact angle on oxygen pressure and saturation are studied. The results show that the oxygen bubble transport in the porous layer is mainly affected by capillary pressure and follows the transport mechanism of ‘pressurization breakthrough depressurization’. The oxygen bubble goes through three stages of growth, migration and separation in the channel, and then be carried out of the electrolysis cell by liquid water. When oxygen breaks through the porous layer and enters the flow channel, there is a phenomenon that the branch flow is merged into the main stream, and the last limiting throat affects the maximum pressure and oxygen saturation during stable condition. In addition, increasing the liquid water velocity is helpful to bubble separation; changing the porosity and fiber diameter directly affects the width of pore throat and the correlative capillary pressure; increasing porosity, reducing fiber diameter and contact angle can promote oxygen breakthrough and reduce the stable saturation of oxygen. 相似文献