MECHANISTIC STUDY OF HIGH FAT DIET-INDUCED CARDIOMYOPATHY

High-fat diet (HFD)-induced obesity is a risk factor contributing to cardiovascular disease. Excessive accumulation of fatty acids in the heart can cause cardiac dysfunction and heart failure and is referred to as lipotoxic cardiomyopathy. A number of pathological conditions can create this lipotoxic environment in the heart, such as obesity, insulin resistance, and diabetes mellitus. The deleterious effects of hyperlipidemia on the heart are well recognized. Many signaling pathways associated with cardiac lipotoxicity have been suggested. However, there is limited insight into the epigenetic signaling mechanism of the heart in response to excessive fatty acids preceding metabolic and vascular disorders, and the associated epigenetic mechanisms promote lipotoxic cardiomyopathy. Therefore, the main purpose of this study is to delineate the initial epigenetic signaling mechanism in response to lipid overload and define its contribution to lipotoxic cardiomyopathy. In our mouse model, we found that the animals that have been fed with high fat diet (60% kcal) for 2 weeks are predisposed to hemodynamic stress (transverse aortic constriction) with an increase of miR-23a and miR-23b expression levels. Also, these 2 miRs target on a histone lysine 36 methyltransferase called Setd2 and repress its expression, which might cause the cardiomyopathy predisposed phenotype. In vivo, we identified the above hypothesis by using Setd2 cardiac specific haploinsufficiency mice and Setd2 cardiac-specific transgenic mice. In conclusion, we observed that high fat diet caused heart predisposed to hypertrophy through upregulation of miR-23a and miR-23b, and repress Setd2

Preparation of Perovskite Films under Liquid Nitrogen Atmosphere for High Efficiency Perovskite Solar Cells

High quality perovskite film with high coverage and tight grain arrangement is critical for achieving high-efficiency and high-stability perovskite solar cells (PSCs). In this work, high quality perovskite films were successfully prepared by liquid nitrogen assisted method (LN method). Here, the vaporization of liquid nitrogen reduces the ambient temperature and absorb thermal energy from the substrate surface to accelerate the nucleation of perovskite. The results of scanning electron microscopy (SEM) shows that the perovskite films prepared by liquid nitrogen assisted method were dense and pinhole-free. The devices prepared by the LN method leads to a high-efficiency upto 16.53%, and the high efficiency device could maintain over 89% of the initial power conversion efficiency (PCE) even after 30 days storage in a desiccator at room temperature

Niobium Incorporation into CsPbI2Br for Stable and Efficient All-Inorganic Perovskite Solar Cells

All-inorganic perovskites are attracting increasing attention due to their superior thermal stability than that of the traditional CH3NH3PbI3, while their inferior phase stability in ambient conditions is still an unsolved issue. Here, for the first time, we report the incorporation of niobium (Nb5+) ions into the CsPbI2Br perovskite. Results indicate that Nb5+ can effectively stabilize the photoactive α-CsPbI2Br phase by the possible substitution of Pb2+. With 0.5% Nb doping, the carbon electrode-based all-inorganic perovskite solar cells achieved a high photoconversion efficiency value of 10.42%, 15% higher than that of the control device. The Nb5+ incorporation reduces the charge recombination in the perovskite, leading to a champion Voc value of 1.27 V and a negligible hysteresis effect. This work explicates the high compatibility of all-inorganic perovskite materials and unlocks the opportunities for the use of high-valence ions for perovskite property modification

Addition Effect of Pyreneammonium Iodide to Methylammonium Lead Halide Perovskite‐2D/3D Heterostructured Perovskite with Enhanced Stability

Despite the eminent performance of the organometallic halide perovskite solar cells (PSCs), the poor stability for humidity and ultraviolet irradiation is still major problem for the commercialization of PSCs. Herein, a novel functional organic compound 1‐(ammonium acetyl)pyrene is successfully introduced for preparing the 2D/3D heterostructured MAPbI3 perovskite. Because of the functional organic pyrene group with high humidity resistance and strong absorption in the ultraviolet region, the 2D/3D perovskite film shows notable stability with no degradation in ≈60% relative humidity after even six months and exhibits a high ultraviolet irradiation stability which keeps nearly no degradation after 1 h in the UV Ozone treatment. Planar PSCs are fabricated in the ≈60% relative humidity air outside glovebox. The champion efficiency of (PEY2PbI4)0.02MAPbI3 perovskite solar cells is 14.7% with nearly no hysteresis which is equal performance of 3D MAPbI3 devices (15.0%). This work presents a new direction for enhancing the solar cells\u27 performance and stability by incorporating a functional organic aromatic compound into the perovskite layer

Enhanced Crystallization by Methanol Additive in Antisolvent for Achieving High‐Quality MAPbI3 Perovskite Films in Humid Atmosphere

Perovskite solar cells have attracted considerable attention owing to their easy and low‐cost solution manufacturing process with high power conversion efficiency. However, the fabrication process is usually performed inside a glovebox to avoid moisture, as organometallic halide perovskites are easily dissolved in water. In this study, we propose a one‐step fabrication of high‐quality MAPbI3 perovskite films in around 50% relative humidity (RH) humid ambient air by using diethyl ether as an antisolvent and methanol as an additive into this antisolvent. Because of the presence of methanol, the water molecules can be efficiently removed from the gaps of the perovskite precursors and the perovskite film formation can be slightly controlled, leading to pinhole‐free and low roughness films. Concurrently, methanol can be used to tune the DMSO ratio in the intermediate perovskite phase to regulate perovskite formation. Planar solar cells fabricated by using this method exhibited the best efficiency of 16.4% with a reduced current density–voltage hysteresis. This efficiency value is approximately 160% higher than the devices fabrication by using only diethyl ether treatment. From the impedance measurement, it is also found that the recombination reaction is suppressed when the device is prepared with methanol additive in the antisolvent. This method presents a new path for controlling the growth and morphology of perovskite films in humid climates and laboratories with uncontrolled environments

Perovskite Solar Cells in Space: Evaluation of Perovskite Solar Cell Hole Transport Material in Space Environment

Majority of spacecrafts rely on solar power as the main source of energy. The search for a lightweight and cost-efficient energy source with high power conversion efficiency (PCE) led to the development of organic-inorganic metal halide Perovskite solar cells (PSCs). In this paper, the performance of PSCs with different hole-transport material (HTM) prepared for in-orbit demonstration mission onboard CubeSats are compared under simulated space environment such as thermal cycling stress, high-vacuum, UV radiation and vibration. Results show that even though organic and inorganic HTM display superior initial PCE, Carbon HTM PSCs trumps them in terms of stability and is more practical for use in space. The paper also discusses the satellite mission and developed hardware for the first demonstration of Perovskite solar cells on-board a satellite to gather in-orbit information on the performance of Perovskite solar cells in low-earth orbit and how the ground test results would be verified

Dependence of acetate based anti-solvent for high humidity fabrication of CH3NH3PbI3 perovskite devices in ambient atmosphere

High-efficiency perovskite solar cells (PSCs) need to be fabricated in the nitrogen-filled glovebox by the atmosphere-controlled crystallization process. However, the use of the glovebox process is of great concern for mass level production of PSCs. In this work, notable efficient CH3NH3PbI3 solar cells can be obtained in high humidity ambient atmosphere (60–70% relative humidity) by using acetate as the antisolvent, in which dependence of methyl, ethyl, propyl, and butyl acetate on the crystal growth mechanism is discussed. It is explored that acetate screens the sensitive perovskite intermediate phases from water molecules during perovskite film formation and annealing. It is revealed that relatively high vapor pressure and high water solubility of methyl acetate (MA) leads to the formation of highly dense and pinhole free perovskite films guiding to the best power conversion efficiency (PCE) of 16.3% with a reduced hysteresis. The devices prepared using MA showed remarkable shelf life stability of more than 80% for 360 h in ambient air condition, when compared to the devices fabricated using other antisolvents with low vapor pressure and low water solubility. Moreover, the PCE was still kept at 15.6% even though 2 vol % deionized water was added in the MA for preparing the perovskite layer

Rnd3/RhoE Modulates HIF1α/VEGF Signaling by Stabilizing HIF1α and Regulates Responsive Cardiac Angiogenesis

The insufficiency of compensatory angiogenesis in the heart of patients with hypertension contributes to heart failure transition. The hypoxia-inducible factor 1α-vascular endothelial growth factor (HIF1α-VEGF) signaling cascade controls responsive angiogenesis. One of the challenges in reprograming the insufficient angiogenesis is to achieve a sustainable tissue exposure to the proangiogenic factors, such as HIF1α stabilization. In this study, we identified Rnd3, a small Rho GTPase, as a proangiogenic factor participating in the regulation of the HIF1α-VEGF signaling cascade. Rnd3 physically interacted with and stabilized HIF1α, and consequently promoted VEGFA expression and endothelial cell tube formation. To demonstrate this proangiogenic role of Rnd3 in vivo, we generated Rnd3 knockout mice. Rnd3 haploinsufficient (Rnd3(+/-)) mice were viable, yet developed dilated cardiomyopathy with heart failure after transverse aortic constriction stress. The poststress Rnd3(+/-) hearts showed significantly impaired angiogenesis and decreased HIF1α and VEGFA expression. The angiogenesis defect and heart failure phenotype were partially rescued by cobalt chloride treatment, a HIF1α stabilizer, confirming a critical role of Rnd3 in stress-responsive angiogenesis. Furthermore, we generated Rnd3 transgenic mice and demonstrated that Rnd3 overexpression in heart had a cardioprotective effect through reserved cardiac function and preserved responsive angiogenesis after pressure overload. Finally, we assessed the expression levels of Rnd3 in the human heart and detected significant downregulation of Rnd3 in patients with end-stage heart failure. We concluded that Rnd3 acted as a novel proangiogenic factor involved in cardiac responsive angiogenesis through HIF1α-VEGFA signaling promotion. Rnd3 downregulation observed in patients with heart failure may explain the insufficient compensatory angiogenesis involved in the transition to heart failure