439 research outputs found
Intelligent Parameter Design-based Impedance Optimization of STATCOM to Mitigate Resonance in Wind Farms
Comparison of the calculated method to the driving voltage applied across the lay in single and double layers of piezoelectric material of active sound absorption
Piezoelectric material can be used as a main component of devices, such as transducers, energy exchangers and arresters. Due to its excellent mechanics and electric coupling performances, piezoelectric material can also be utilized in control system of sound and vibration. However, there have not been any publications outlining the basic equations of reflection or transmission coefficients of driving voltage applied across the layers (single or double) of piezoelectric material. In this paper, two methods – the theoretical method and the electro-acoustic analogy method – are used in order to compare the driving voltage applied across the single and the double layer of active sound surfaces of piezoelectric material. Computational results indicate that the proposed theoretical models are correct and applicable in practical implementations
Beneficial Metabolic Effects of 2′,3′,5′-tri-acetyl-N6- (3-Hydroxylaniline) Adenosine in the Liver and Plasma of Hyperlipidemic Hamsters
BACKGROUND: Pharmaceutical research of hyperlipidemia has been commonly pursued using traditional approaches. However, unbiased metabonomics attempts to explore the metabolic signature of hyperlipidemia in a high-throughput manner to understand pathophysiology of the disease process. METHODOLOGY/PRINCIPAL FINDINGS: As a new way, we performed (1)H NMR-based metabonomics to evaluate the beneficial effects of 2',3',5'-tri-acetyl-N(6)- (3-hydroxylaniline) adenosine (WS070117) on plasma and liver from hyperlipidemic Syrian golden hamsters. Both plasma and liver profiles provided a clearer distinction between the control and hyperlipidemic hamsters. Compared to control animals, hyperlipidemic hamsters showed a higher content of lipids (triglyceride and cholesterol), lactate and alanine together with a lower content of choline-containing compounds (e.g., phosphocholine, phosphatidylcholine, and glycerophosphocholine) and betaine. As a result, metabonomics-based findings such as the PCA and OPLS-DA plotting of metabolic state and analysis of potential biomarkers in plasma and liver correlated well to the assessment of biochemical assays, Oil Red O staining and in vivo ultrasonographic imaging suggesting that WS070117 was able to regulate lipid content and displayed more beneficial effects on plasma and liver than simvastatin. CONCLUSIONS/SIGNIFICANCE: This work demonstrates the promise of applying (1)H NMR metabonomics to evaluate the beneficial effects of WS070117 which may be a good drug candidate for hyperlipidemia
Cloud Control of Connected Vehicle under Bi-directional Time-varying delay: An Application of Predictor-observer Structured Controller
This article is devoted to addressing the cloud control of connected
vehicles, specifically focusing on analyzing the effect of bi-directional
communication-induced delays. To mitigate the adverse effects of such delays, a
novel predictor-observer structured controller is proposed which compensate for
both measurable output delays and unmeasurable, yet bounded, input delays
simultaneously. The study begins by novelly constructing an equivalent
delay-free inter-connected system model that incorporates the
Predictor-Observer controller, considering certain delay boundaries and model
uncertainties. Subsequently, a stability analysis is conducted to assess the
system's robustness under these conditions. Next, the connected vehicle lateral
control scenario is built which contain high-fidelity vehicle dynamic model.
The results demonstrate the controller's ability to accurately predict the
system states, even under time-varying bi-directional delays. Finally, the
proposed method is deployed in a real connected vehicle lateral control system.
Comparative tests with a conventional linear feedback controller showcase
significantly improved control performance under dominant bi-directional delay
conditions, affirming the superiority of the proposed method against the delay
Regulation of Oxidized Base Repair in Human Chromatin by Posttranslational Modification
Base excision repair (BER) is the major pathway for the repair of oxidized bases and apurinic/apyrimidinic (abasic; AP) sites produced by reaction with reactive oxygen/nitrogen species (ROS/RNS). These metabolites are generated spontaneously by endogenous cellular processes and also by environmental agents. Because most of these lesions are promutagenic, linked to diverse disease-associated somatic mutations, as well as heritable single nucleotide polymorphisms (SNPs) in the normal human population, their prompt repair is warranted. Impairment of repair leading to mutation, a hallmark of cancer, underscores the essentiality of BER for maintaining genome integrity in humans and other mammals. In mammals, repair of oxidized bases and other BER substrates is initiated by DNA glycosylases (DGs), which excise the damaged bases and cleave the DNA strands at the resulting AP sites, followed by sequential end processing, gap-filling DNA synthesis, and ligation. In vitro BER performed with naked DNA substrates has been extensively studied, which delineates its basic mechanistic steps and subpathways. However, recent interest is directed to unraveling BER in cell chromatin, including its regulation via posttranslational modifications (PTMs), which occurs possibly in concert with nucleosome remodeling. Emerging reports on various PTMs of BER enzymes indicate that the PTMs, while dispensable for the enzymatic activity, regulate overall repair by modulating interactions with other repair proteins and chromatin factors, assembly of BER complexes, as well as turnover of the proteins, and may ultimately dictate the cellular phenotype. Here, we discuss recent advances in the BER field by reviewing the PTMs and how they regulate BER in chromatin
Molecular Dynamics Simulation Reveals Correlated Inter-Lobe Motion in Protein Lysine Methyltransferase SMYD2
SMYD proteins are an exciting field of study as they are linked to many types of cancer- related pathways. Cardiac and skeletal muscle development and function also depend on SMYD proteins opening a possible avenue for cardiac-related treatment. Previous crystal structure studies have revealed that this special class of protein lysine methyltransferases have a bilobal structure, and an open–closed motion may regulate substrate specificity. Here we use the molecular dynamics simulation to investigate the still-poorly-understood SMYD2 dynamics. Cross-correlation analysis reveals that SMYD2 exhibits a negative cor- related inter-lobe motion. Principle component analysis suggests that this correlated dynamic is contributed to by a twisting motion of the C-lobe with respect to the N-lobe and a clamshell-like motion between the lobes. Dynamical network analysis defines possible allo- steric paths for the correlated dynamics. There are nine communities in the dynamical net- work with six in the N-lobe and three in the C-lobe, and the communication between the lobes is mediated by a lobe-bridging β hairpin. This study provides insight into the dynam- ical nature of SMYD2 and could facilitate better understanding of SMYD2 substrate specificity
Spatial Representativeness of PM_(2.5) Concentrations Obtained Using Reduced Number of Network Stations
Haze has been a focused air pollution phenomenon in China, and its characterization is highly desired. Aerosol properties obtained from a single station are frequently used to represent the haze condition over a large domain, such as tens of kilometers, which could result in high uncertainties due to their spatial variation. Using a high resolution network observation over an urban city in North China from November 2015 to February 2016, this study examines the spatial representativeness of ground station observations of particulate matter with diameters less than 2.5 μm (PM_(2.5)). We developed a new method to determine the representative area of PM_(2.5) measurements from limited stations. The key idea is to determine the PM_(2.5) spatial representative area using its spatial variability and temporal correlation. We also determine stations with large representative area using two grid networks with different resolutions. Based on the high spatial resolution measurements, the representative area of PM_(2.5) at one station can be determined from the grids with high correlations and small differences of PM_(2.5). The representative area for a single station in the study period ranges from 0.25 to 16.25 km^2, but is less than 3 km^2 for more than half of the stations. The representative area varies with locations, and observation at 10 optimal stations would have a good representativeness of those obtained from 169 stations for the four-month time scale studied. Both evaluations with an empirical orthogonal function (EOF) analysis and with independent dataset corroborate the validity of the results found in this study
Effect of nitrogen application on enhancing high-temperature stress tolerance of tomato plants during the flowering and fruiting stage
This study was conducted to investigate the effects of nitrogen application on growth, photosynthetic performance, nitrogen metabolism activities, and fruit quality of tomato plants under high-temperature (HT) stress. Three levels of daily minimum/daily maximum temperature were adopted during the flowering and fruiting stage, namely control (CK; 18°C/28°C), sub-high temperature (SHT; 25°C/35°C), and high-temperature (HT; 30°C/40°C) stress. The levels of nitrogen (urea, 46% N) were set as 0 (N1), 125 (N2), 187.5 (N3), 250 (N4), and 312.5 (N5) kg hm2, respectively, and the duration lasted for 5 days (short-term). HT stress inhibited the growth, yield, and fruit quality of tomato plants. Interestingly, short-term SHT stress improved growth and yield via higher photosynthetic efficiency and nitrogen metabolism whereas fruit quality was reduced. Appropriate nitrogen application can enhance the high-temperature stress tolerance of tomato plants. The maximum net photosynthetic rate (PNmax), stomatal conductance (gs), stomatal limit value (LS), water-use efficiency (WUE), nitrate reductase (NR), glutamine synthetase (GS), soluble protein, and free amino acids were the highest in N3, N3, and N2, respectively, for CK, SHT, and HT stress, whereas carbon dioxide concentration (Ci), was the lowest. In addition, maximum SPAD value, plant morphology, yield, Vitamin C, soluble sugar, lycopene, and soluble solids occurred at N3-N4, N3-N4, and N2-N3, respectively, for CK, SHT, and HT stress. Based on the principal component analysis and comprehensive evaluation, we found that the optimum nitrogen application for tomato growth, yield, and fruit quality was 230.23 kg hm2 (N3-N4), 230.02 kg hm2 (N3-N4), and 115.32 kg hm2 (N2), respectively, at CK, SHT, and HT stress. Results revealed that the high yield and good fruit quality of tomato plants at high temperatures can be maintained by higher photosynthesis, nitrogen efficiency, and nutrients with moderate nitrogen
Optimization of Ionic Liquid Based Simultaneous Ultrasonic- and Microwave-Assisted Extraction of Rutin and Quercetin from Leaves of Velvetleaf ( Abutilon theophrasti
An ionic liquids based simultaneous ultrasonic and microwave assisted extraction (ILs-UMAE) method has been proposed for the extraction of rutin (RU), quercetin (QU), from velvetleaf leaves. The influential parameters of the ILs-UMAE were optimized by the single factor and the central composite design (CCD) experiments. A 2.00 M 1-butyl-3-methylimidazolium bromide ([C4mim]Br) was used as the experimental ionic liquid, extraction temperature 60°C, extraction time 12 min, liquid-solid ratio 32 mL/g, microwave power of 534 W, and a fixed ultrasonic power of 50 W. Compared to conventional heating reflux extraction (HRE), the RU and QU extraction yields obtained by ILs-UMAE were, respectively, 5.49 mg/g and 0.27 mg/g, which increased, respectively, 2.01-fold and 2.34-fold with the recoveries that were in the range of 97.62–102.36% for RU and 97.33–102.21% for QU with RSDs lower than 3.2% under the optimized UMAE conditions. In addition, the shorter extraction time was used in ILs-UMAE, compared with HRE. Therefore, ILs-UMAE was a rapid and an efficient method for the extraction of RU and QU from the leaves of velvetleaf
Comparison of the calculated method to the driving voltage applied across the lay in single and double layers of piezoelectric material of active sound absorption
Piezoelectric material can be used as a main component of devices, such as transducers, energy exchangers and arresters. Due to its excellent mechanics and electric coupling performances, piezoelectric material can also be utilized in control system of sound and vibration. However, there have not been any publications outlining the basic equations of reflection or transmission coefficients of driving voltage applied across the layers (single or double) of piezoelectric material. In this paper, two methods – the theoretical method and the electro-acoustic analogy method – are used in order to compare the driving voltage applied across the single and the double layer of active sound surfaces of piezoelectric material. Computational results indicate that the proposed theoretical models are correct and applicable in practical implementations
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