Poly(ADP-ribose) (PAR) polymerase-1 (PARP-1) acts as a DNA damage sensor. It recognizes DNA damage and facilitates DNA repair by recruiting DNA repair machinery to damage sites. Recent studies ...reported that PARP-1 also plays an important role in DNA replication by recognizing the unligated Okazaki fragments and controlling the speed of fork elongation. On the other hand, emerging evidence reveals that excessive activation of PARP-1 causes chromatin DNA fragmentation and triggers an intrinsic PARP-1-dependent cell death program designated parthanatos, which can be blocked by genetic deletion or pharmacological inhibition of PARP-1. Therefore, PARP-1 plays an essential role in maintaining genomic stability by either facilitating DNA repair/replication or triggering DNA fragmentation to kill cells. A group of structure-specific nucleases is crucial for executing DNA incision and fragmentation following PARP-1 activation. In this review, we will discuss how PARP-1 coordinates with its associated nucleases to maintain genomic integrity and control the decision of cell life and death.
Wireless power transfer (WPT) has attracted a lot of attention these years due to its convenience, safety, reliability, and weather proof features. First and foremost, the consistency of mutual model ...and T model of loosely coupled transformer (LCT) was deduced. The application scenarios of these two models were then concluded so as to choose suitable model in circuit analysis. Then, a new WPT compensation topology, which is referred to as LC /S compensation topology and consists of one inductor and two capacitors, is proposed. The constant-current-output (CCOut) characteristic of the newly proposed topology is analyzed in detail on the basis of the discussion about LC and CL resonant tank. The equivalent resistance of the rectifier, filter, and resistor circuit is also analyzed to simplify circuit analysis. Then, the current and voltage stress on each component and the system performance under imperfect resonant condition are studied with the help of MATLAB. The LCT is deliberately designed by the finite element analysis software ANSYS Maxwell as well because the coupling coefficient, primary, and secondary self-inductance have a significant impact on system efficiency, power level, and density. The LCT design approach employed in this paper can be extended to magnetic design of almost all WPT systems. Theoretical analyses are verified by both Pspice simulation and practical experiments. Practical output currents with transient loads show an excellent CCOut characteristic of LC/S compensation topology.
The soil freezing characteristic curve (SFCC) represents the constitutive relationship between sub‐zero temperature and unfrozen water content in soil. It governs the hydrologic and mechanical ...behaviors associated with freezing soil. Numerous studies have investigated the mechanisms of soil water freezing and attempted to predict SFCC using soil water characteristic curve (SWCC) and Clapeyron equation. However, limited attention has been given to the physical disparities between adsorbed and capillary water during freezing, including variations in pressures and water‐ice interfaces. In this study, we present a novel theoretical model for predicting SFCC. The model determines the freezing point by calculating the chemical potential of soil water and ice with their respective pressures, thus capturing the distinctions in freezing behaviors between adsorbed and capillary water. All model parameters possess clear physical interpretations, and the model solely relies on the SWCC as input. The validity of the proposed model was confirmed through experimental measurements involving the water phase diagram, SWCCs, and the corresponding SFCCs of sandy, silty, and clayey soils. The model exhibits strong capabilities in predicting SFCC regardless of the soil type and outperforms the conventional method in predicting the SFCC of soil with high adsorbed water content. Model analyses were performed to investigate the effects of individual pore size, soil type, and initial water content on the freezing process, revealing the distinct contributions of adsorption and capillarity in soil water freezing. This study elucidates the mechanisms underlying soil water freezing, offering a theoretical framework for the analysis and prediction of frozen soil behaviors.
Plain Language Summary
The freezing point of soil water is lower than that of free water, and the relationship between sub‐zero temperature and unfrozen water content is soil freezing characteristic curve (SFCC). The unfrozen water content is important for the physical processes in soil. Soil water content comprises adsorbed water and capillary water. They are retained in soil by different physical mechanisms, that is, adsorption and capillarity. As a result, they exhibit distinct freezing behaviors. However, the freezing of adsorbed water has been overlooked in many studies. This work established a theoretical SFCC model based on the chemical potential equilibrium between pore water and ice. The model can describe the freezing of adsorbed and capillary water and only requires the soil water characteristic curve (SWCC) as input. Experimental water phase diagram, SFCCs, and SWCCs validated this model. The model can predict the SFCC of various soils and is superior to the conventional method in predicting the SFCC of soils with high adsorbed water content. The clear physical mechanism in the model enables the analysis of the effects of pore sizes, soil types, and initial water content on unfrozen water content. This work provides a useful tool to predict frozen soil behaviors.
Key Points
A theoretical soil freezing characteristic curve (SFCC) model considering the physical disparities between adsorbed and capillary water is established
The model exhibits advantages in predicting the SFCC of soils with high adsorbed water content
The model can illustrate the effects of soil types and initial water contents on SFCC
A Review of LED Drivers and Related Technologies Yijie Wang; Alonso, J. Marcos; Xinbo Ruan
IEEE transactions on industrial electronics (1982),
2017-July, 2017-7-00, 20170701, Letnik:
64, Številka:
7
Journal Article
Recenzirano
Light-emitting diode (LEDs) have a promising prospect because of its outstanding advantages: 1) long lifetime, 2) environmentally friendly, 3) flexibility of color mixing, 4) high illumination ...efficiency, etc. Based on the electrical characteristics of LEDs, a constant current driver is needed to support the LED working performance. With the wide applications of LEDs, many new technologies are presented. In this paper, advantages and disadvantages of different LED drivers are discussed. A detailed technology review is presented which is good for researchers and engineers to make right choices in design and selection of LED drivers.
The maidenhairtree polysaccharides (MTPs) have important application prospects. So, the extraction, purification, structure, derivatization and biological activities of polysaccharides from leaves, ...fruits, and testae of maidenhairtree were disscussed. Polysaccharides were extracted by collaborative extraction methods such as ultrasound-assisted extraction and microwave-assisted extraction. The ultrasound-assisted extraction had higher content and higher efficiency. The structural characteristics and structure-activity relationship of maidenhairtree polysaccharides were studied in order to provide theoretical basis and technical support for the further development and utilization of maidenhairtree polysaccharides.
A CLCL resonant dc/dc converter has been proposed and analyzed in this paper for two-stage light-emitting diode (LED) drivers. The circuit performs zero-voltage-switching (ZVS) turn-on and ...quasi-zero-current-switching (ZCS) turn-off. Then, a two-stage system has been designed using a power factor correction circuit before the proposed converter. Optimum input impedance angle, dead time, and components parameters have been achieved after thoughtful design, thus obtaining good soft-switching performance and reduced voltage stress. A 100-W prototype has been realized and tested demonstrating its high feasibility and efficiency at full load and during dimming operations.
A 1 MHz half-bridge resonant dc/dc converter based on GaN FETs and planar magnetics is proposed in this paper, which improves the system efficiency and power density. The resonant network can achieve ...satisfactory soft-switching characteristics based on a small impedance angle, which greatly reduces the losses of switches and diodes. The losses characteristics during the turn-on and turn-off transitions are analyzed in detail. The calculation results show that the GaN FETs with low output capacitance and on resistance can achieve fast switching speed and low losses in high-frequency conditions. To reduce the profile and increase the power density of the system, planar magnetics are used in this paper. The response surface methodology (RSM) and modular layer model (MLM) are adopted to help design the planar inductor and transformer, respectively. Both of the methods offer clearer and more effective ways to design the planar magnetics. A 25-W prototype is built to verify the feasibility of the proposed high-frequency converter.
Sirtuin (Yeast Silent Information RegulatorsⅡ, Sir2) was first discovered in the 1970s. Because of its function by removing acetylated groups from histones in the presence of nicotinamide adenine ...dinucleotide (NAD+), waves of research have assessed the potential of Sirtuin as a therapeutic target. The Sirtuin family, which is widely distributed throughout the nature, has been divided into seven human isoforms (Sirt1-Sirt7). They are thought to be closely related to some aging diseases such as cardiovascular disorders, neurodegeneration, and tumors. Herein, we present a comprehensive review of the structure, function and modulators of Sirtuins, which is expected to be beneficial to relevant studies.
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•The roles of Sirtuins are thoroughly discussed.•The functions of Sirtuins are outlined.•An overview for the modulators of Sirtuins is introduced in detail.
Brain ischemia and reperfusion (I/R) is one of the most severe clinical manifestations of ischemic stroke, placing a significant burden on both individuals and society. The only FDA-approved clinical ...treatment for ischemic stroke is tissue plasminogen activator (t-PA), which rapidly restores cerebral blood flow but can have severe side effects. The complex pathological process of brain I/R has been well-established in the past few years, including energy metabolism disorders, cellular acidosis, doubling of the synthesis or release of excitotoxic amino acids, intracellular calcium homeostasis, free radical production, and activation of apoptotic genes. Recently, accumulating evidence has shown that NO may be strongly related to brain I/R and involved in complex pathological processes. This review focuses on the role of endogenous NO in pathological processes in brain I/R, including neuronal cell death and blood brain barrier disruption, to explore how NO impacts specific signaling cascades and contributes to brain I/R injury. Moreover, NO can rapidly react with superoxide to produce peroxynitrite, which may also mediate brain I/R injury, which is discussed here. Finally, we reveal several therapeutic approaches strongly associated with NO and discuss their potential as a clinical treatment for ischemic stroke.
Narrow-band blue light emitting of Bi3+ activated phosphor has been realized in garnet-type Sr3Lu2Ge3O12.
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•A novel garnet-type phosphor of Sr3Lu2Ge3O12: Bi3+ has been ...synthesized.•Sr3Lu2Ge3O12: Bi3+ can emit bright narrow-band blue light with FWHM ≈ 40 nm.•Sr3Lu2Ge3O12: Bi3+ shows significant cathodoluminescence properties.•Sr3Lu2Ge3O12: Bi3+ performs good color stability under poor working condition.
Investigating highly efficient narrow-band emission phosphors that have strong excitation bands in the near-ultraviolet (NUV) region is the main goal of the present light-emitting diode (LED) research, especially for Bi3+-activated phosphors. The naked 6s and 6p electrons of Bi3+ are sensitive to the microenvironment, thus leading to broad emission bands, while most Bi3+-activated phosphors suffer from low absorption of NUV-LED chips. Here, we report on a narrow-band blue-emitting garnet-type phosphor of Sr3Lu2Ge3O12: Bi3+ that is available for NUV-LED chips; its full width of the half maximum (FWHM) is limited to 40 nm, which is comparative to rare earth-activated phosphors, such as commercial blue phosphor BaMgAl10O17: Eu2+ (FWHM ≈ 52 nm), and this phenomenon is extremely rare among most Bi3+-activated phosphors. The internal quantum efficiency (IQE) of Sr3Lu2Ge3O12: Bi3+ can reach 57%. Moreover, it is interesting to find that Sr3Lu2Ge3O12: Bi3+ also exhibits exalting cathodoluminescence properties and its narrow-band emission produces brilliant images with high color saturation. The significant luminescent properties of trivalent bismuth are ascribed to the compact and highly symmetrical crystal structure of Sr3Lu2Ge3O12; thus, the discussion of the structure-property relations for Bi3+-activated Sr3Lu2Ge3O12 is the most anticipated part of this work. The results pave the way for the design of better Bi3+-activated phosphors for use as white light emitting diodes (WLEDs) and field emission displays (FEDs).
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