Search

Synaptic impairment and loss are an important pathological feature of Alzheimer's disease (AD). Memory is stored in neural networks through changes in synaptic activity, and synaptic dysfunction can cause cognitive dysfunction and memory loss. Cholecystokinin (CCK) is one of the major neuropeptides in the brain, and plays a role as a neurotransmitter and growth factor. The level of CCK in the cerebrospinal fluid is decreased in AD patients. In this study, a novel CCK analogue was synthesized on the basis of preserving the minimum bioactive fragment of endogenous CCK to investigate whether the novel CCK analogue could improve synaptic plasticity in the hippocampus of the APP/PS1 transgenic mouse model of AD and its possible molecular biological mechanism. Our study found that the CCK analogue could effectively improve spatial learning and memory, enhance synaptic plasticity in the hippocampus, normalize synapse numbers and morphology and the levels of key synaptic proteins, up-regulate the PI3K/Akt signaling pathway and normalize PKA, CREB, BDNF and TrkB receptor levels in APP/PS1 mice. The amyloid plaque load in the brain was reduced by CCK, too. The use of a CCKB receptor antagonist and targeted knockdown of the CCKB receptor (CCKBR) attenuated the neuroprotective effect of the CCK analogue. These results demonstrate that the neuroprotective effect of CCK analogue is achieved by activating the PI3K/Akt as well as the PKA/CREB-BDNF/TrkB signaling pathway that leads to protection of synapses and cognition. [ABSTRACT FROM AUTHOR]

The Mars Surface Composition Detector (MarSCoDe) is a remote sensing instrument mounted on the front deck of the Zhurong rover in China's Tianwen-1 mission. The MarSCoDe adopts Laser-Induced Breakdown Spectroscopy (LIBS), along with Short Wave Infrared Spectroscopy (SWIR) and a telescopic micro-imager, to perform in situ detection of the chemical composition of soils, rocks, and minerals on the Martian surface. Since the MarSCoDe LIBS system works in extraterrestrial environments, it is important to equip the system with a set of onboard calibration targets, which are used for assessing the real-time performance of the instrument under various environmental conditions and conducting instrumental response calibration. Twelve dedicated LIBS reference samples were embedded as the MarSCoDe calibration target (MCCT) set, which plays a critical role in LIBS calibration before conducting LIBS analysis. This paper elaborates on the selection, development, characterization and testing of the MCCT set. The underlying scientific reasons and technical requirements that determine the selection of MCCT samples are introduced. The development procedures and mechanical performance test of both the calibration samples and the assembly holder are presented. Then, a comparison of the MCCTs and the characterization and scientific testing are described. The LIBS spectra of the MCCTs collected in three different atmospheric scenarios, namely laboratory-simulated Martian, normal terrestrial, and in situ Martian atmosphere, were investigated. The laboratory results and in situ behaviour show that the MarSCoDe instrument and the MCCT set can soundly adapt to the Martian environment with sufficient performance, as indicated by the fact that the spectral lines of the main elements in the calibration targets can be well identified and distinguished, including Ti, Si, Al, Fe, Mg, P, Ca, Na, K, O, C, H, S, etc. The MCCT samples provide a good reference for analysing Martian surface material composition and formulating the transfer relationship between the LIBS spectra measured in different atmospheric environments. [ABSTRACT FROM AUTHOR]

The smart grid is playing a key role to enable smart cities and smart Internet of things. As an important part of the smart grid, the smart distribution network requires the intelligent terminal unit (ITU) to realize real-time electrical parameters acquisition and effective communication. The traditional ITU uses optical fiber or wireless mechanisms for data transmission among electrical equipment, other units, and master station, which is limited to deployment cost and ambient electromagnetic interference. Therefore, we propose a novel enhanced intelligent terminal unit (E-ITU) under the smart distribution network. First, we propose the E-ITU model that integrates free-space optical communication (FSO) and radio frequency (RF) for ITU to enhance the communication methods. Then, we propose the adaptive hybrid FSO/RF transmission mechanism for the E-ITU to improve the channel transmission performance. Finally, we evaluate our E-ITU performance, and the experiment results show that the E-ITU can effectively reduce system interrupts and improve the system transmission rate, which achieves high robust electrical parameters transmission under the smart distribution network. [ABSTRACT FROM AUTHOR]

The unified power quality conditioner (UPQC) integrated with the battery energy storage system not only mitigates the power quality problems on the grid side and load side but also supplies active power to the load or the grid. The wide voltage variation of the battery and the high efficiency of the whole system can be achieved with the hybrid connected configuration, i.e., the battery is connected simultaneously to the series and shunt converters of the UPQC directly and indirectly through the dc–dc converter. However, the control and modulation strategies are the major challenges for this configuration. This study proposes a control scheme based on asymmetrical sinusoidal pulse width modulation (SPWM) to realize high-efficiency active power delivery, thereby addressing the issue above. The mechanism of the modulation scheme to regulate active power is revealed, and the voltage variation of the battery is considered. The modified SPWM strategy features easy implementation and a low computation burden. The effectiveness of the system with the proposed control and modulation schemes is verified by both simulation and experimental results. [ABSTRACT FROM AUTHOR]

Mars Surface Composition Detector (MarSCoDe) is a scientific payload onboard the Mars rover of China's Tianwen-1 mission. With the capability of 1.6∼7 m remote detection and analysis, MarSCoDe instrument suite consists of a two dimensional pointing mirror and an optical head outside the rover cabin, a Laser Induced Breakdown Spectroscopy (LIBS) spectrometer and a Short Wave Infrared (SWIR) spectrometer collectively covering 240∼2400 nm and a master controller unit inside the rover body, calibration target sets, optical fibers and power cables connecting the internal and external units. Combining the techniques of active LIBS, passive SWIR and micro-imaging, MarSCoDe provides functions including elemental composition discrimination and quantitative determination, classification of rock and soil characteristics, sample texture imaging and characterization of plasma-excited area. This paper introduces MarSCoDe mainly in terms of scientific objectives, design requirements, assembly and implementation, spectral and radiation calibration, and performance verification. The LIBS laser irradiance on the target can soundly exceed 10 MW/mm2, and the performance of the LIBS module operated at different temperatures has been tested. The field of view of the SWIR spectrometer is 36.5 mrad. The micro-imager can extract the central pixel area of 320 × 320 and 1024 × 1024, and the former is binned into 64 × 64. The 2D pointing mirror has a wide forward detection range and a narrow backward calibration range, with the pointing pitch accuracy better than 0.133°. [ABSTRACT FROM AUTHOR]

The accumulation of iron-dependent lipid peroxides is one of the important causes of NAFLD. The purpose of this study is to explore the effect of dehydroabietic acid (DA) on ferroptosis in nonalcoholic fatty liver disease (NAFLD) mice and its possible mechanisms. DA improved NAFLD and reduced triglycerides (TG), total cholesterol (TC), and lipid peroxidation level and inhibited ferroptosis in the liver of HFD-induced mice. DA binds with Keap1 to form 3 stable hydrogen bonds at VAL512 and LEU557 and increased nuclear factor erythroid 2-related factor 2 (Nrf2)-antioxidant response elemen (ARE) luciferase activity. DA promoted the expression downstream of Nrf2 such as heme oxygenase-1 (HO-1), glutathione (GSH) and its peroxidase 4 (GPX4), so as to eliminate the accumulation of reactive oxygen species (ROS) and reduce lipid peroxides malondialdehyde (MDA) in the liver. DA inhibited ferroptosis and increased the expression of key genes such as ferroptosis suppressor protein 1 (FSP1) in vitro and vivo. In all, DA may bind with Keap1, activate Nrf2-ARE, induce its target gene expression, inhibit ROS accumulation and lipid peroxidation, and reduce HFD-induced NAFLD. [ABSTRACT FROM AUTHOR]

Ischemic stroke is one of the leading causes of death and long-term disability worldwide. As an important class of pervasive genes involved in many pathophysiological processes of ischemic stroke, non-coding RNAs (ncRNAs) have received attention in the past decades. ncRNAs are a class of functional RNAs that regulate gene expression in a post-transcriptional manner, and including microRNAs, long non-coding RNAs, and circular RNAs. Several studies have deciphered that ncRNAs have a key role in the ischemic stroke-induced neuroinflammation and cell death via different molecules and pathways. Thus, ncRNAs show great promise as novel molecular targets in ischemic stroke. In this article, we provide an updated review of the current state of our knowledge about the roles of different types of ncRNAs in neuroinflammation and cell death following ischemic stroke, which may facilitate the translation of ncRNAs research into clinical practice to improve the clinical outcome of stroke therapy. [ABSTRACT FROM AUTHOR]

Myeloid-derived suppressor cells (MDSCs) are a group of heterogeneous cells derived from immature myeloid cells (IMCs). MDSCs are known to play important roles in tumor immune evasion. While we know that there are a large number of circulating and tumor-infiltrating MDSCs existing in gastric cancer (GC) patients, the phenotypic characteristics and arginase 1 (ARG1) expression levels of these MDSCs remain very unclear. In our study, flow cytometric analysis of circulating MDSCs from 20 gastric adenocarcinoma (GAC) patients found that ≥80% ARG1-expressing MDSCs were mainly early-stage MDSCs (HLA-DR−CD33+CD14−CD15−MDSCs). In addition, our investigation showed that tumor-infiltrating MDSCs from 6 GAC patients consisted of >35% ARG1-expressing naïve MDSCs (HLA-DR−CD33−CD11b−CD14−CD15−MDSCs), >15% early-stage MDSCs and >40% monocytic MDSCs (HLA-DR−CD14+MDSCs). This preliminary study describes the phenotypic characteristics and ARG1 expression levels of MDSCs from GAC patients and shows that circulating and tumor-infiltrating ARG1-expressing cells were mainly immature and monocytic MDSCs, which provides information to better understand the mechanisms that allow gastric cancer cells to evade the immune system. [ABSTRACT FROM AUTHOR]

Adopting effective strategies to eliminate the shrinkage porosity at the final stage of steel solidification is one of the most attractive research subjects for metallurgists. Despite the progress in understanding the thermoelectric magnetic convection (TEMC) in the solidification process, utilization of TEMC for modifying the solidification feeding of steel has been ignored. The effects of TEMC on the shrinkage porosity at the final stage of solidification of GCr18Mo steel were investigated under an axial static magnetic field (ASMF). The morphology and porosity of GCr18Mo steel were investigated quantitatively by X-ray microtomography. We found that the amount of porosity first decreases and then increases with increasing intensity of the ASMF. Meanwhile, the shape of the porosity changed from tortuous to elliptic under the ASMF. On the basis of both the experimental and simulated results, the decrease in porosity is attributed to an adequate development of the TEMC leading to sufficient feeding. This study sheds light on an alternative technique for eliminating the shrinkage porosity at the final stage of steel solidification in industrial applications. [ABSTRACT FROM AUTHOR]