214 research outputs found
Experimental and numerical research of debonding defects detection in fiber metal laminates using low-power ultrasonic-induced thermography
No full textDebonding defects in fiber metal laminates (FMLs) pose a significant threat to structural reliability, necessitating efficient and non-destructive inspection methods. This study explores the use of low-power ultrasonic-induced thermography (LUIT) for rapid visualization of debonding defects in FMLs through combined experimental and numerical investigations. An inspection system was developed, incorporating bispectral analysis for the determination of optimized excitation frequencies, thereby enhancing the heat generated at defect locations to achieve improved detection performance. Infrared thermography was employed to monitor transient temperature evolution, and a contrast-based time-slice selection strategy was introduced to enhance defect visibility. Furthermore, a comprehensive numerical simulation framework integrating modal analysis, implicit dynamic simulation, and thermo-mechanical coupling was proposed to reveal the underlying heating mechanisms, focusing on frictional dissipation, viscoelastic damping, and plastic deformation. The combined results demonstrate the capability of LUIT to selectively heat debonding defects without damaging the material, with defect detectability strongly influenced by defect size, depth, and excitation timing. The findings demonstrate that LUIT offers a fast, safe, and non-destructive approach for reliable debonding defect detection in FML structures
Production, Characterization, and Antioxidant Activity of Fucoxanthin from the Marine Diatom Odontella aurita
No full textThe production, characterization, and antioxidant capacity of the carotenoid fucoxanthin from the marine diatom Odontella aurita were investigated. The results showed that low light and nitrogen-replete culture medium enhanced the biosynthesis of fucoxanthin. The maximum biomass concentration of 6.36 g L−1 and maximum fucoxanthin concentration of 18.47 mg g−1 were obtained in cultures grown in a bubble column photobioreactor (Ø 3.0 cm inner diameter), resulting in a fucoxanthin volumetric productivity of 7.96 mg L−1 day−1. A slight reduction in biomass production was observed in the scaling up of O. aurita culture in a flat plate photobioreactor, yet yielded a comparable fucoxanthin volumetric productivity. A rapid method was developed for extraction and purification of fucoxanthin. The purified fucoxanthin was identified as all-trans-fucoxanthin, which exhibited strong antioxidant properties, with the effective concentration for 50% scavenging (EC50) of 1,1-dihpenyl-2-picrylhydrazyl (DPPH) radical and 2,2′-Azino-bis(3-ethylbenzthiazoline-6-sulfonic acid (ABTS) radical being 0.14 and 0.03 mg mL−1, respectively. Our results suggested that O. aurita can be a natural source of fucoxanthin for human health and nutrition
Carrier-Based Modulated Model Predictive Control for Vienna Rectifiers
No full textThe implementation of traditional finite-control-set model predictive control (FCS-MPC) with variable switching frequency in voltage source rectifiers (VSRs) can make the system suffer from poor current harmonics performance. In fact, the resulting wide-spread voltage harmonic generated at the AC terminals makes the design of the typical multi-order AC filtering bulky and prone to control instabilities. This paper proposed a fixed frequency carrier-based modulated model predictive control (CB-MMPC) which is able to overcome these issues. This control strategy aims to improve the total harmonic distortion (THD) of the AC current waveform without introducing any additional weight factor in the cost function of the optimization routine, while maintaining the typical performance of fast current dynamic response of the FCS-MPC. Herein, the detailed implementation of the proposed CB-MMPC is given, while considering its application to the current feedback control loop of a three-phase three-level Vienna rectifier. Finally, PLECS based simulation results are used to verify the feasibility and the effectiveness of the proposed control strategy and to benchmark its performance to the classical FCS-MPC strategy and the conventional application of a current closed loop implementing a proportional-integral(PI)-controller.Accepted author manuscriptDC systems, Energy conversion & Storag
Model Predictive Control for the Reduction of DC-link Current Ripple in Two-level Three-phase Voltage Source Inverters
No full textIn the applications of three-phase two-level voltage source inverters (VSIs) relatively large energy storage capacitors are used to absorb the high DC-link current ripples mainly caused by the circulating reactive power, the switched AC phase current flowing to the DC-link, and other dynamic and/or asymmetric operating conditions. Especially for electrolytic capacitor technology the typically high current stress and consequent losses is known to limit the power electronics lifetime, thus the design and selection of this component is critical for the whole system. To alleviate this problem, a new model predictive control (MPC) cost function which enables DC-link capacitor current ripple reduction is proposed in this paper. Based on the DC-link current mathematical model and the available VSI switching states, the future DC current ripple can be predicted, and then the optimized space vectors that best tracks the sinusoidal output current and minimizes the DC-link current ripple are chosen. Compared with conventional DC-link capacitor current reduction methods, the proposed approach has the advantage to incorporate an outstanding fast current control dynamics as well as being of relatively simple implementation because there is no need to adjust the switching signals or space vectors in the modulation as function of operational conditions of the system. Simulation and experimental results are presented verifying the effectiveness of the proposed MPC method.Accepted author manuscriptDC systems, Energy conversion & Storag
Characterization of the Small RNA Transcriptomes of Androgen Dependent and Independent Prostate Cancer Cell Line by Deep Sequencing
No full textGiven the important roles of miRNA in post-transcriptional regulation and its implications for cancer, characterization of miRNA facilitates us to uncover molecular mechanisms underlying the progression of androgen-independent prostate cancer (PCa). The emergence of next-generation sequencing technologies has dramatically changed the speed of all aspects of sequencing in a rapid and cost-effective fashion, which can permit an unbiased, quantitive and in-depth investigation of small RNA transcriptome. In this study, we used high-throughput Illumina sequencing to comprehensively represent the full complement of individual small RNA and to characterize miRNA expression profiles in both the androgen dependent and independent Pca cell line. At least 83 miRNAs are significantly differentially expressed, of which 41 are up-regulated and 42 are down-regulated, indicating these miRNAs may be involved in the transition of LNCaP to an androgen-independent phenotype. In addition, we have identified 43 novel miRNAs from the androgen dependent and independent PCa library and 3 of them are specific to the androgen-independent PCa. Function annotation of target genes indicated that most of these differentially expressed miRNAs tend to target genes involved in signal transduction and cell communication, epically the MAPK signaling pathway. The small RNA transcriptomes obtained in this study provide considerable insights into a better understanding of the expression and function of small RNAs in the development of androgen-independent prostate cancer
Prognostic value of TIGAR and LC3B protein expression in nasopharyngeal carcinoma
No full textMin Wei,* Jinxia Peng,* Peng Wu, Ping Chen, Hongru Yang, Yongxia Cui, Linglin Yang Department of Oncology, The Affiliated Hospital of Southwest Medical University, Luzhou 646000, People’s Republic of China *These authors contributed equally to this work Purpose: Autophagy, the process responsible for degrading cytoplasmic organelles to sustain cellular metabolism, has been associated with cancer initiation and progression. As TP53-induced glycolysis and apoptosis regulator (TIGAR) is among the important genes that can regulate autophagy, we aimed to investigate the correlation between the expression levels of TIGAR and the autophagy-related protein microtubule-associated protein 1 light chain 3 (LC3B), as well as their association with clinical outcomes, in nasopharyngeal carcinoma (NPC) patients.Methods: We detected the expressions of TIGAR and LC3B in 182 NPC tissue samples via immunohistochemical staining.Results: A significant correlation between TIGAR and LC3B expressions was identified (P=0.045). Moreover, survival analysis showed that TIGAR– or LC3B+ expression was associated with improved overall survival, local regional failure-free survival, distant failure-free survival, and failure-free survival rates, compared with TIGAR+ or LC3B– expression, respectively. Meanwhile, when combining TIGAR with LC3B expression in terms of prognostic value, patients with TIGAR+/LC3B– expression were significantly disadvantaged with regard to overall survival, local regional failure-free survival , distant failure-free survival, and failure-free survival compared with other groups based on the log-rank test and Cox regression analyses (all P<0.05).Conclusion: TIGAR and LC3B may be novel biomarkers for predicting the prognosis of NPC patients and could be utilized as potential targets for future therapeutics aimed at treating NPC patients. Keywords: nasopharyngeal carcinoma, TIGAR, LC3B, autophagy, prognosi
Olaparib nanoparticles potentiated radiosensitization effects on lung cancer
No full textMin Wu,1,* Jing Liu,1,* ChuanFei Hu,1 Dong Li,1 Juan Yang,1 ZhouXue Wu,1 LingLin Yang,1 Yue Chen,2 ShaoZhi Fu,1 JingBo Wu1 1Department of Oncology, The Affiliated Hospital of Southwest Medical University, Luzhou 646000, China; 2Department of Nuclear Medicine, The Affiliated Hospital of Southwest Medical University, Luzhou 646000, China *These authors contributed equally to this work Background: Poly (ADP-ribose) polymerase (PARP) is a key enzyme in the repair process of DNA strand breaks (DSBs). Olaparib (Ola) is a PARP inhibitor that is involved in arresting PARP release from radiotherapy (RT)-induced damaged DNA to potentiate the effect of RT. Although the underlying mechanisms for the radiosensitization effects of Ola are well understood in vitro, the radiosensitization effects in vivo are still unclear. Moreover, poor water solubility and severe toxicity are two major impediments for the clinical success of Ola.Materials and methods: Here, we developed olaparib nanoparticles (Ola-NPs) and investigated their radiosensitization mechanisms and toxicity using human non-small-cell lung cancer xenograft models in mice.Results: The prepared Ola-NPs showed a mean size of 31.96±1.54 nm and a lower polydispersity index of about 0.126±0.014. In addition, the sensitization enhancement ratio of Ola-NPs (3.81) was much higher than that of free Ola (1.66). The combination of Ola-NPs and RT (Ola-NPs + RT) significantly inhibited tumor growth and prolonged survival in mice. The mechanism of enhanced antitumor efficacy might be related to the inhibition of DSB repair and the promotion of cell apoptosis in vivo. No additional toxicity caused by Ola-NPs was observed.Conclusion: This study demonstrated the principle of using Ola-NPs as a potent radiosensitizer to improve the therapeutic effect of RT relative to free Ola (P<0.05 in all cases). Keywords: lung cancer, nanoparticles, olaparib, radiosensitizatio
Large signal stability analysis of DAB converter using Moving Discretized Control Set- Model Predictive Control
No full textDual Active Bridge is often considered in many DC/DC converter applications where high efficiency, input/output voltage ratio and power level are required. Recently a predictive control technique, named Moving Discretized Control Set - Model Predictive Control has been introduced, in order to achieve faster dynamics and stable operation throughout the power and terminal voltage ranges, considering global control parameters. However, even if this technique provides flexible multi-objective control, its large signal stability remains in questions. In this paper, the large signal stability of a Dual Active Bridge converter operating in single phase shift with Moving Discretized Control Set - Model Predictive Control is analyzed, considering a phase-portrait based approach. The obtained results show insights into factors that stabilize or destabilize the converter operation. The proposed methodology is validated through both simulation and experimental testing
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