A novel controllable capacitor commutation based superconducting hybrid direct current breaker.

Featuring low power loss and high reliability, voltage source converter medium voltage direct current (VSC-MVDC) systems have been widely employed for grid-tied renewable energy applications. To maintain high operational safety, circuit breakers are needed to isolate faulted powerlines by comprehensively considering response speed and installation cost. Research efforts have been put to realizing DC fault isolation by coordinating resistive type superconducting fault current limiter (R-SFCL) and integrated-gate-commutated-thyristor (IGCT) based hybrid DC circuit breaker. In this paper, a controllable current commutation based superconducting DC circuit breaker (CCCB-SDCCB) is proposed. By integrating R-SFCL with IGCT based hybrid DC circuit breakers, the current interrupting capacity can be greatly enlarged with the advantage of low cost and fast speed, and hence the overall cost for suppress large fault currents can be greatly reduced for MVDC systems. In addition, a new current injection circuit branch using H-bridge structure is designed to recycle the residual capacitor voltage from the previous fault stage to trigger the IGCTs without the capacitor pre-charging process. Simulation results show that the fault current can be successfully suppressed from 24.2 to 2.1 kA and fully interrupted within 4.11 ms by the proposed CCCB-SDCCB.

NQO1 regulates expression and alternative splicing of apoptotic genes associated with Alzheimer's disease in PC12 cells.

PURPOSE: Alzheimer's disease (AD) is a neurodegenerative disorder characterized by progressive memory loss and cognitive dysfunction. Quinone oxidoreductase 1 (NQO1) is an antioxidant enzyme that plays an important role in controlling cellular redox state, whose expression is altered in the brain tissues of AD patients. In addition to its traditional antioxidant effects, NQO1 also acts as a multifunctional RNA-binding protein involved in posttranscriptional regulation. Whether the RNA-binding activity of NQO1 influences AD pathology has not been investigated yet. METHODS: The RNA-binding functions of NQO1 in rat pheochromocytoma (PC12) cells were investigated using siRNA knockdown followed by total RNA sequencing. Reverse transcription quantitative polymerase chain reaction was performed to explore the impact of NQO1 on the transcription and alternative splicing of apoptotic genes. RESULTS: NQO1 knockdown led to a significant increase in cellular apoptosis. Genes involved in certain apoptosis pathways, such as positive regulation of apoptotic processes and mitogen-activated protein kinase signaling, were under global transcriptional and alternative splicing regulation. NQO1 regulated the transcription of apoptotic genes Cryab, Lgmn, Ngf, Apoe, Brd7, and Stat3, as well as the alternative splicing of apoptotic genes BIN1, Picalm, and Fyn. CONCLUSION: Our findings suggest that NQO1 participates in the pathology of AD by regulating the expression and alternative splicing of the genes involved in apoptosis. These results extend our understanding of NQO1 in apoptotic pathways at the posttranscriptional level in AD.

Ti-Mn hydrogen storage alloys: from properties to applications.

Efficient and safe storage of hydrogen is an important link in the process of hydrogen energy utilization. Hydrogen storage with hydrogen storage materials as the medium has the characteristics of high volumetric hydrogen storage density and good safety. Among many hydrogen storage materials, only rare earth-based and titanium-based hydrogen storage alloys have been applied thus far. In this work, current state-of-the-art research and applications of Ti-Mn hydrogen storage alloys are reviewed. Firstly, the hydrogen storage properties and regulation methods of binary to multicomponent Ti-Mn alloys are introduced. Then, the applications of Ti-Mn alloys in hydrogen storage, hydrogen compression and catalysis are discussed. Finally, the future research and development of Ti-Mn hydrogen storage alloys is proposed.

Recent advance of metal borohydrides for hydrogen storage.

Hydrogen energy is an excellent carrier for connecting various renewable energy sources and has many advantages. However, hydrogen is flammable and explosive, and its density is low and easy to escape, which brings inconvenience to the storage and transportation of hydrogen. Therefore, hydrogen storage technology has become one of the key steps in the application of hydrogen energy. Solid-state hydrogen storage method has a very high volumetric hydrogen density compared to the traditional compressed hydrogen method. The main issue of solid-state hydrogen storage method is the development of advanced hydrogen storage materials. Metal borohydrides have very high hydrogen density and have received much attention over the past two decades. However, high hydrogen sorption temperature, slow kinetics, and poor reversibility still severely restrict its practical applications. This paper mainly discusses the research progress and problems to be solved of metal borohydride hydrogen storage materials for solid-state hydrogen storage.

Vibration Energy Harvesting from the Subwavelength Interface State of a Topological Metamaterial Beam.

Topological metamaterial has been a research hotpot in both physics and engineering due to its unique ability of wave manipulation. The topological interface state, which can efficiently and robustly centralize the elastic wave energy, is promising to attain high-performance energy harvesting. Since most of environmental vibration energy is in low frequency range, the interface state is required to be designed at subwavelength range. To this end, this paper developed a topological metamaterial beam with local resonators and studied its energy-harvesting performance. First, the unit cell of this topological metamaterial beam consists of a host beam with two pairs of parasitic beams with tip mass. Then, the band structure and topological features are determined. It is revealed that by tuning the distance between these two pairs of parasitic beams, band inversion where topological features inverse can be obtained. Then, two sub-chains, their design based on two topologically distinct unit cells, are assembled together with a piezoelectric transducer placed at the conjunction, yielding the locally resonant, topological, metamaterial, beam-based piezoelectric energy harvester. After that, its transmittance property and output power were obtained by using the frequency domain analysis of COMSOL Multiphysics. It is clear that the subwavelength interface state is obtained at the band-folding bandgap. Meanwhile, in the interface state, elastic wave energy is successfully centralized at the conjunction. From the response distribution, it is found that the maximum response takes place on the parasitic beam rather than the host beam. Therefore, the piezoelectric transducer is recommended to be placed on the parasitic beam rather than host beam. Finally, the robustness of the topological interface state and its potential advantages on energy harvesting were studied by introducing a local defect. It is clear that in the interface state, the maximum response is always located at the conjunction regardless of the defect degree and location. In other words, the piezoelectric transducer placed at the conjunction can maintain a stable and high-efficiency output power in the interface state, which makes the whole system very reliable in practical implementation.

A PEGylated water-soluble fluorescent and colorimetric probe for carbon monoxide detection.

A CO probe with PEGylation is synthesized, achieving the detection of CO in pure water solution with high intensity color change and fluorescence enhancement. Importantly, this probe with high affinity to paper strips and low toxicity to living cells is successfully used for sensing CO in air and in living cells.

Ring-Strain-Enabled Catalytic Asymmetric Umpolung C-O Bond-Forming Reactions of 1,2-Oxazetidines for the Synthesis of Functionalized Chiral Ethers.

An unprecedented catalytic asymmetric umpolung C-O bond-forming reaction of N-nosyl 1,2-oxazetidines with ß-keto esters has been achieved in the presence of a chiral phase-transfer catalyst, allowing access to a range of highly functionalized chiral ethers bearing quaternary and no adjacent stereogenic centers with high yields, excellent enantioselectivities, and diastereoselectivities (up to 97% ee and 20:1 dr). These versatile products could be flexibly transformed into biologically important chiral fused and spiro morpholines in two steps.

Effect of Lifestyle Changes after Percutaneous Coronary Intervention on Revascularization.

OBJECTIVE: Whether optimal cardiovascular health metrics may reduce the risk of cardiovascular events in secondary prevention is uncertain. The study was conducted to evaluate the influence of lifestyle changes on clinical outcomes among the subjects underwent percutaneous coronary intervention (PCI). METHODS: The study group consists of 17,099 consecutive PCI patients. We recorded data on subject lifestyle behavior changes after their procedure. Patients were categorized as ideal, intermediate, or poor CV health according to a modified Life's Simple 7 score (on body mass, smoking, physical activity, diet, cholesterol, blood pressure, and glucose). Multivariable COX regression was used to evaluate the association between CV health and revascularization event. We also tested the impact of cumulative cardiovascular health score on reoccurrence of cardiovascular event. RESULTS: During a 3-year median follow-up, 1,583 revascularization events were identified. The observed revascularization rate was 8.0%, 9.3%, and 10.6% in the group of patients with optimal (a modified Life's Simple 7 score of 11-14), average (score = 9 or 10), or inadequate (less or equal than 8) CV health, respectively. After multivariable analysis, the adjusted hazard ratios were 0.83 (95% CI: 0.73-0.94) and 0.89 (95% CI: 0.79-0.99) for patients with optimal and average lifestyle changes comparing with the inadequate tertile (P for trend = 0.003). In addition, each unit increase in above metrics was associated with a decrease risk of revascularization (HR, 0.96; 95% confidence interval, 0.93-0.98; P for trend = 0.003). In addition, each unit increase in above metrics was associated with a decrease risk of revascularization (HR, 0.96; 95% confidence interval, 0.93-0.98. CONCLUSION: Ideal CV health related to lower incidence of cardiovascular events, even after the percutaneous coronary intervention. Revascularization can be reduced by lifestyle changes. The cardiovascular health metrics could be extrapolated to secondary prevention and need for further validation.

[The effect of atorvastatin on the expression of CD55, CD59 in patients with hyperlipidemia].

OBJECTIVE: To study the expressions of CD55 and CD59 in patients with hyperlipidemia and the effects of atorvastatin on it, and to identify the possible influential factors. METHODS: We selected 67 patients with hyperlipidemia, and 24 healthy people matched in terms of age, sex and body weight as control. The expressions of CD55 and CD59 on white blood cells were detected by flow cytometry, and their relationships to blood lipids, complement activation indexes (C(5a), sC(5b-9)), inflammatory factors (high sensitivity C-reactive protein (hsCRP), TNF-alpha, IL-6 were analyzed. 24 patients with hyperlipidemia were treated with atorvastatin for 8-12 weeks and the expressions of CD55 and CD59 were measured before and after atorvastatin therapy. RESULTS: The mean fluorescence intensity (MFI) of CD55 lymphocytes and monocytes were decreased in patients with hyperlipidemia compared with control (2.07 +/- 0.28 vs 2.29 +/- 0.44 and 3.45 +/- 1.02 vs 4.33 +/- 2.32, P < 0.01 and P < 0.05, respectively). CD55 positive lymphocyte MFI was negatively correlated with waist circumference, waist-hip ratio, hsCRP and C(5a). C(5a) was negatively correlated with the MFIs of CD55 positive lymphocytes, monocytes, granulocytes, and positively with TG and diastolic blood pressure. After atorvastatin therapy, the MFIs of CD59 positive lymphocytes, monocytes and granulocytes increased (4.34 +/- 1.16 vs 3.69 +/- 0.76, 4.52 +/- 1.36 vs 3.91 +/- 0.89, 5.67 +/- 1.72 vs 4.56 +/- 1.03, P < 0.05, < 0.05 and < 0.01 respectively), which were not correlated with changes of blood lipids. CONCLUSIONS: The expression of CD55 is down-regulated in hyperlipidemia, which might be influenced by obesity, abdominal distribution of adipose tissue and inflammatory status of hyperlipidemia, but not by blood lipids. The expression of CD55 is related with complement activation; The expression of CD59 is up-regulated after atorvastatin treatment independently of blood lipids.