Insulin resistance is one of the earliest defects in the pathogenesis of type 2 diabetes. Over the past 50 years, elucidation of the insulin signalling network has provided important mechanistic ...insights into the abnormalities of glucose, lipid and protein metabolism that underlie insulin resistance. In classical target tissues (liver, muscle and adipose tissue), insulin binding to its receptor initiates a broad signalling cascade mediated by changes in phosphorylation, gene expression and vesicular trafficking that result in increased nutrient utilisation and storage, and suppression of catabolic processes. Insulin receptors are also expressed in non-classical targets, such as the brain and endothelial cells, where it helps regulate appetite, energy expenditure, reproductive hormones, mood/behaviour and vascular function. Recent progress in cell biology and unbiased molecular profiling by mass spectrometry and DNA/RNA-sequencing has provided a unique opportunity to dissect the determinants of insulin resistance in type 2 diabetes and the metabolic syndrome; best studied are extrinsic factors, such as circulating lipids, amino acids and other metabolites and exosomal microRNAs. More challenging has been defining the cell-intrinsic factors programmed by genetics and epigenetics that underlie insulin resistance. In this regard, studies using human induced pluripotent stem cells and tissues point to cell-autonomous alterations in signalling super-networks, involving changes in phosphorylation and gene expression both inside and outside the canonical insulin signalling pathway. Understanding how these multi-layered molecular networks modulate insulin action and metabolism in different tissues will open new avenues for therapy and prevention of type 2 diabetes and its associated pathologies.
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The lithium-ion battery of an electric vehicle (EV) is typically rated at either 400 or 800 V. When considering public parking infrastructures, EV wireless chargers must efficiently deliver electric ...power to both battery options. This can be normally achieved by regulating the output voltage through a dc-dc converter at the cost of higher onboard circuit complexity and lower overall efficiency. This article proposes a wireless charging system that maintains a high power transfer efficiency when charging EVs with either 400- or 800-V nominal battery voltage at the same power level. The control scheme is implemented at the power source side, and only passive semiconductor devices are employed on board the EV. The presented system, called voltage/current doubler (V/I-D), comprises two sets of series-compensated coupled coils, each of them connected to a dedicated H-bridge converter. The equivalent circuit has been analyzed while explaining the parameters' selection. The analytical power transfer efficiency has been compared to the one resulting from the conventional one-to-one coil system at 7.2 kW. For the same power level, the dc-to-dc efficiency of 97.11% and 97.52% have been measured at 400-V and 800-V voltage output, respectively. Finally, the functionality of the V/I-D converter has been proved at both the even and uneven misalignments of the two sets of coupled coils.
DC power distribution systems for data centers, industrial applications, and residential areas are expected to provide higher efficiency, higher reliability, and lower cost compared to ac systems and ...have been an important research topic in recent years. In these applications, an efficient power factor correction (PFC) rectifier, supplying the dc distribution bus from the conventional three-phase ac mains, is typically required. This paper analyzes the three-phase, buck-type, unity power factor SWISS Rectifier for the realization of an ultrahigh-efficiency PFC rectifier stage with a 400-V rms line-to-line ac input voltage and a 400-V dc output voltage. It is shown that the mains current total harmonic distortion of the rectifier can be improved significantly by interleaving two converter output stages. Furthermore, the dc output filter is implemented using a current-compensated integrated common-mode coupled inductor, which ensures equal current sharing between the interleaved half bridges and provides common-mode electromagnetic interference (EMI) filter inductance. Based on a theoretical analysis of the coupled inductor's magnetic properties, the necessary equations and the design procedure for selecting semiconductors, magnetic cores, the number of turns, and the EMI filter are discussed. Based on these results, an ultrahigh-efficient 8-kW 4-kW <inline-formula><tex-math notation="LaTeX">\cdot</tex-math></inline-formula>dm<inline-formula> <tex-math notation="LaTeX">^{-3}</tex-math></inline-formula> (66-W<inline-formula><tex-math notation="LaTeX">\cdot </tex-math></inline-formula>in<inline-formula><tex-math notation="LaTeX">^{-3}</tex-math></inline-formula>) laboratory-scale prototype converter using 1.2-kV SiC MOSFETs is designed. Measurements taken on the prototype confirm a full power efficiency of <inline-formula><tex-math notation="LaTeX">\text{{99.16}{\%}}</tex-math></inline-formula> and a peak efficiency of <inline-formula><tex-math notation="LaTeX">\text{{99.26}{\%,}}</tex-math></inline-formula> as well as the compliance to CISPR 11 Class B conducted emission limits.
Two-stage AC-DC converters are considered as a prominent solution for DC-type electric vehicle (EV) chargers. However, this kind of architecture suffers from high switching losses with large heatsink ...and DC-link capacitor volume. To relieve this issue, this paper presents a new hybrid modulation for DC-type EV chargers, where a two-phase clamped discontinuous pulse-width-modulation (DPWM) in the front-end circuit is cooperated with the variable frequency triangular-current-mode (TCM) zero voltage switching (ZVS) or its simplified implementation, i.e., boundary-ZVS (B-ZVS) strategy, in the back-end circuit. The former can stop the switching actions in the front-end stage during two-thirds of the grid period, while the AC currents are at their highest values, which can yield to the best switching loss reduction and deliver high power factor operation. Besides, TCM-ZVS or B-ZVS modulations can achieve ZVS turn-on action for all semiconductors during all operating range in the DC-DC stage to further reduce the power losses on the semiconductors. With such characteristics, the proposed strategies can reduce the switching losses of the system to the best extent, and thus allow an enhancement of the system power density by improving the power conversion efficiency. The proposed strategy is described, analyzed, validated, and benchmarked in a 5 kW SMD SiC MOSFET-based two-stage AC-DC converter. A 99% power efficiency can be achieved with the solution implementing the TCM-ZVS strategy at an output voltage of 400 V and rated power.
Recent developments in the electricity sector encourage a high penetration of Renewable Energy Sources (RES). In addition, European policies are pushing for mass deployment of Electric Vehicles ...(EVs). Due to their non-controllable characteristics, these loads have brought new challenges in distribution networks, resulting in increased difficulty for Distribution System Operators (DSOs) to guarantee a safe and reliable operation of the grid. Battery Energy Storage Systems (BESSs) are promising solutions for mitigating the impact of the new loads and RES. In this paper, different aspects of the BESS's integration in distribution grids are reviewed. At first, the physical layer will be considered, focusing on the main battery technologies commercially available and on the power electronics converter. Secondly, the different functionalities that a grid-connected BESS can provide will be investigated, and then its sizing, location and control in distribution network will be discussed. In addition, an overview of actual BESSs installations is given. All in all, this paper aims at providing a comprehensive view of BESSs integration in distribution grids, highlighting the main focus, challenges, and research gaps for each one of these aspects.
Dietary sugars, fructose and glucose, promote hepatic de novo lipogenesis and modify the effects of a high-fat diet (HFD) on the development of insulin resistance. Here, we show that fructose and ...glucose supplementation of an HFD exert divergent effects on hepatic mitochondrial function and fatty acid oxidation. This is mediated via three different nodes of regulation, including differential effects on malonyl-CoA levels, effects on mitochondrial size/protein abundance, and acetylation of mitochondrial proteins. HFD- and HFD plus fructose-fed mice have decreased CTP1a activity, the rate-limiting enzyme of fatty acid oxidation, whereas knockdown of fructose metabolism increases CPT1a and its acylcarnitine products. Furthermore, fructose-supplemented HFD leads to increased acetylation of ACADL and CPT1a, which is associated with decreased fat metabolism. In summary, dietary fructose, but not glucose, supplementation of HFD impairs mitochondrial size, function, and protein acetylation, resulting in decreased fatty acid oxidation and development of metabolic dysregulation.
This paper describes a new modulation concept for the uni- and bidirectional SWISS rectifier, which mitigates ac input current distortions at the mains voltage sector boundaries. An analytical model ...is derived and compared to simulations, which allows an estimation of the distortion's magnitude from design parameters, showing that these distortions increase the input current total harmonic distortion (THD) significantly. A modification of the original circuit topology is proposed, which decouples the operation of SWISS Rectifier's active third-harmonic current injection network and its dc-dc converter switches. An algorithm is presented which allows the calculation of a temporary pulse width modulation for the SWISS Rectifier's current injection network to mitigating the distortions. The concept is verified for both power flow directions and for operation with unsymmetrical and distorted mains voltages by measurement results taken on a bidirectional 7.5-kW SWISS Rectifier prototype. An ac input current THD of 1.3% results for symmetric sinusoidal mains voltages and 1.4% and 1.6% for operation with distorted and unsymmetrical mains voltages.
Active power decoupling circuits are used in bidirectional single-phase grid-connected systems to enhance the circuit lifetime by creating an alternative path for the typical dc-side power pulsating ...ripple. Therefore, this reduces the requirement of smoothing dc capacitors allowing compact designs even with the implementation of long life metalized film technology. However, with the necessary addition of auxiliary components, extra power losses in the added switching devices and passive components will be introduced, which will inevitably reduce the system power conversion efficiency. To relieve this issue, a new discontinuous pulsewidth modulation (PWM) strategy with minimum switching losses is proposed in this article. This method detects the converter current and reference voltages synchronously to determine the optimum clamped duration of each circuit phase-leg. With such a characteristic, the proposed strategy can realize the minimum switching losses at any instant, thus improving the power conversion efficiency and potentially the power density of the converter. The proposed modulation method is described, analyzed, validated, and compared with different PWM methods on a 2-kVA bidirectional single-phase ac-dc converter with active power decoupling circuit.
Bisphenol-A (BPA) is one of the most widespread endocrine disrupting chemicals (EDC) used as the base compound in the manufacture of polycarbonate plastics. Although evidence points to consider ...exposure to BPA as a risk factor for insulin resistance, its actions on whole body metabolism and on insulin-sensitive tissues are still unclear. The aim of the present work was to study the effects of low doses of BPA in insulin-sensitive peripheral tissues and whole body metabolism in adult mice. Adult mice were treated with subcutaneous injection of 100 µg/kg BPA or vehicle for 8 days. Whole body energy homeostasis was assessed with in vivo indirect calorimetry. Insulin signaling assays were conducted by western blot analysis. Mice treated with BPA were insulin resistant and had increased glucose-stimulated insulin release. BPA-treated mice had decreased food intake, lower body temperature and locomotor activity compared to control. In skeletal muscle, insulin-stimulated tyrosine phosphorylation of the insulin receptor β subunit was impaired in BPA-treated mice. This impairment was associated with a reduced insulin-stimulated Akt phosphorylation in the Thr(308) residue. Both skeletal muscle and liver displayed an upregulation of IRS-1 protein by BPA. The mitogen-activated protein kinase (MAPK) signaling pathway was also impaired in the skeletal muscle from BPA-treated mice. In the liver, BPA effects were of lesser intensity with decreased insulin-stimulated tyrosine phosphorylation of the insulin receptor β subunit.In conclusion, short-term treatment with low doses of BPA slows down whole body energy metabolism and disrupts insulin signaling in peripheral tissues. Thus, our findings support the notion that BPA can be considered a risk factor for the development of type 2 diabetes.
Three-legs active power decoupling (APD) converters are widely studied in the single-phase grid-connected systems to enhance the circuit lifetime by creating an alternative path for the typical ...existing dc-side power pulsating ripple. Therefore, this reduces the requirement of smoothing dc capacitors allowing compact designs even with the implementation of long life metalized film technology. In this article, to allow enhancement of the system power density by improving power conversion efficiency and thus reducing the requirement of thermal management of the semiconductors, a carrier-based generalized discontinuous PWM strategy is proposed. This method detects the converter ac currents and ac reference voltages to determine the optimum clamped duration in each one of the three bridge-legs, which will minimize the converter overall switching losses. The proposed modulation method is analyzed and validated on a PLECS simulation and a 2 kVA single-phase three-legs APD converter.
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