Direct Amplitude Control for Voice Coil Motor on High Frequency Reciprocating Rig

High-frequency reciprocating rig (HFRR) that utilizes direct drive voice coil motor (VCM) is designed to perform pin-on-flat tribotest such as assessing the lubricity of fuel. In this article, we propose direct amplitude control to maintain the amplitude of high-frequency reciprocating motion of VCM on HFRR subjects to frictional load. First, the mathematical model of HFRR is developed, which takes the effect of frictional load into consideration. Subsequently, direct amplitude control is proposed, which takes the error of amplitude rather than position error as performance index. It consists of an amplitude regulator and an offset compensator. Analysis and simulations of the proposed control method are presented as well. Finally, the proposed control method is deployed to a digital signal processor on an HFRR prototype experimental platform. The experiment results indicate a significant improvement of the performance of VCM-based HFRR in terms of amplitude accuracy in high-frequency band compared with that given by traditional PI control. The results also suggest the instability of PR control in this case

Hypolipidemic effect of aqueous leaf extract of carmona microphylla G Don

Purpose: To investigate the hypolipidemic effects of the aqueous leaf extract of Carmona microphylla (Lam.) G. Don. (CAE) in vitro and in vivo.Methods: The lipid-lowering effect of CAE was investigated in oleic acid (OA)-induced steatosis in HepG2 liver cells, as well as in high-fat diet (HFD)- and triton WR-1339 (TRI)-induced hyperlipidemic mice. The levels of intracellular, serum and/or hepatic total cholesterol (TC); triglyceride (TG); low density lipoprotein-cholesterol (LDL-c); high density lipoprotein-cholesterol (HDL-c); hepatic superoxide dismutase (SOD) activity and malondialdehyde (MDA) were determined by oil-red O staining and appropriate kits.Results: Treatment with CAE inhibited lipid accumulation in HepG2 cells and reduced the elevated levels of serum TC, TG and LDL-c as well as hepatic TC and TG in hyperlipidemic mice induced by HFD. CAE administration also significantly decreased arteriosclerosis index (AI) and LDL-c/HDL-c ratio, but improved oxidative status as revealed by increased hepatic SOD activity and decreased MDA level. The lipid ameliorating and antioxidative effects of CAE (600 mg/kg) were comparable to those of the standard lipid-lowering drug, sivastatin (5 mg/kg).Conclusion: These results suggest that C. microphylla aqueous extract (CAE) protects against hyperlipidemia induced by HFD in mice and may find therapeutic application in hyperlipidemic patients.Keywords: Carmona microphylla, Hyperlipidemia, Atherosclerosis, Oxidative stress, Sivastatin, Lipidlowerin

Restored glial glutamate transporter EAAT2 function as a potential therapeutic approach for Alzheimer’s disease

Glutamatergic systems play a critical role in cognitive functions and are known to be defective in Alzheimer’s disease (AD) patients. Previous literature has indicated that glial glutamate transporter EAAT2 plays an essential role in cognitive functions and that loss of EAAT2 protein is a common phenomenon observed in AD patients and animal models. In the current study, we investigated whether restored EAAT2 protein and function could benefit cognitive functions and pathology in APPSw,Ind mice, an animal model of AD. A transgenic mouse approach via crossing EAAT2 transgenic mice with APPSw,Ind. mice and a pharmacological approach using a novel EAAT2 translational activator, LDN/OSU-0212320, were conducted. Findings from both approaches demonstrated that restored EAAT2 protein function significantly improved cognitive functions, restored synaptic integrity, and reduced amyloid plaques. Importantly, the observed benefits were sustained one month after compound treatment cessation, suggesting that EAAT2 is a potential disease modifier with therapeutic potential for AD

Small-molecule activator of glutamate transporter EAAT2 translation provides neuroprotection

Glial glutamate transporter EAAT2 plays a major role in glutamate clearance in synaptic clefts. Several lines of evidence indicate that strategies designed to increase EAAT2 expression have potential for preventing excitotoxicity, which contributes to neuronal injury and death in neurodegenerative diseases. We previously discovered several classes of compounds that can increase EAAT2 expression through translational activation. Here, we present efficacy studies of the compound LDN/OSU-0212320, which is a pyridazine derivative from one of our lead series. In a murine model, LDN/OSU-0212320 had good potency, adequate pharmacokinetic properties, no observed toxicity at the doses examined, and low side effect/toxicity potential. Additionally, LDN/OSU-0212320 protected cultured neurons from glutamate-mediated excitotoxic injury and death via EAAT2 activation. Importantly, LDN/OSU-0212320 markedly delayed motor function decline and extended lifespan in an animal model of amyotrophic lateral sclerosis (ALS). We also found that LDN/OSU-0212320 substantially reduced mortality, neuronal death, and spontaneous recurrent seizures in a pilocarpine-induced temporal lobe epilepsy model. Moreover, our study demonstrated that LDN/OSU-0212320 treatment results in activation of PKC and subsequent Y-box–binding protein 1 (YB-1) activation, which regulates activation of EAAT2 translation. Our data indicate that the use of small molecules to enhance EAAT2 translation may be a therapeutic strategy for the treatment of neurodegenerative diseases

K-Means Clustering Algorithm Based on Chaotic Adaptive Artificial Bee Colony

K-Means Clustering is a popular technique in data analysis and data mining. To remedy the defects of relying on the initialization and converging towards the local minimum in the K-Means Clustering (KMC) algorithm, a chaotic adaptive artificial bee colony algorithm (CAABC) clustering algorithm is presented to optimally partition objects into K clusters in this study. This algorithm adopts the max–min distance product method for initialization. In addition, a new fitness function is adapted to the KMC algorithm. This paper also reports that the iteration abides by the adaptive search strategy, and Fuch chaotic disturbance is added to avoid converging on local optimum. The step length decreases linearly during the iteration. In order to overcome the shortcomings of the classic ABC algorithm, the simulated annealing criterion is introduced to the CAABC. Finally, the confluent algorithm is compared with other stochastic heuristic algorithms on the 20 standard test functions and 11 datasets. The results demonstrate that improvements in CAABA-K-means have an advantage on speed and accuracy of convergence over some conventional algorithms for solving clustering problems

Precipitation overrides warming in mediating soil nitrogen pools in an alpine grassland ecosystem on the Tibetan Plateau

Soils in the alpine grassland store a large amount of nitrogen (N) due to slow decomposition. However, the decomposition could be affected by climate change, which has profound impacts on soil N cycling. We investigated the changes of soil total N and five labile N stocks in the topsoil, the subsoil and the entire soil profile in response to three years of experimental warming and altered precipitation in a Tibetan alpine grassland. We found that warming significantly increased soil nitrate N stock and decreased microbial biomass N (MBN) stock. Increased precipitation reduced nitrate N, dissolved organic N and amino acid N stocks, but increased MBN stock in the topsoil. No change in soil total N was detected under warming and altered precipitation regimes. Redundancy analysis further revealed that soil moisture (26.3%) overrode soil temperature (10.4%) in explaining the variations of soil N stocks across the treatments. Our results suggest that precipitation exerted stronger influence than warming on soil N pools in this mesic and high-elevation grassland ecosystem. This indicates that the projected rise in future precipitation may lead to a significant loss of dissolved soil N pools by stimulating the biogeochemical processes in this alpine grassland.National Program on Key Basic Research Project of the Ministry of Science and Technology of the People's Republic of China [2014CB954003, 2014CB954004]SCI(E)[email protected]; [email protected]