•Vibration of fluid-conveying pipes is isolated by quasi-zero stiffness systems.•Nonlinear solution is obtained via Galerkin method and the finite difference.•The fluid flow can deteriorate the ...performance of vibration isolation.
Fluid-conveying pipes are always subjected to various excitations to cause unwanted vibrations. A quasi-zero stiffness system consisting of three linear springs is adopted as the nonlinear isolator to attenuate the transverse vibrations of fluid-conveying pipes induced by foundation excitations. A dynamic model of nonlinear forced vibration of the fluid-conveying pipe coupled with two nonlinear isolators is established for the nonlinear continuous system and validated by using two methods, Galerkin method and the finite difference method. The influence of the quasi-zero stiffness isolators on the vibration characteristics and vibration transmission of the pipe is investigated by analyzing the natural frequency, vibration mode, and nonlinear vibration response. The effects of flow speed of the fluid and the system parameters of the isolator are studied to evaluate the isolation performance. It is found that the quasi-zero stiffness isolator and fluid flow can shift several natural frequencies of vibration of the pipeline to the low-frequency region. When the linear stiffness of the vibration isolation is zero in the vertical direction, the first two modes of the bending vibration of the fluid-conveying pipe tend to become rigid mode. While achieving high-efficiency vibration isolation in the high-frequency region, the vibration in the low-frequency region is complicated. The flow speed of the fluid can deteriorate the performance of vibration isolation.
The planning of urban bus-only lane networks is an important measure to improve bus service and bus priority. To determine the effective arrangement of bus-only lanes, a bi-level programming model ...for urban bus lane layout is developed in this study that considers accessibility and budget constraints. The goal of the upper-level model is to minimize the total travel time, and the lower-level model is a capacity-constrained traffic assignment model that describes the passenger flow assignment on bus lines, in which the priority sequence of the transfer times is reflected in the passengers' route-choice behaviors. Using the proposed bi-level programming model, optimal bus lines are selected from a set of candidate bus lines; thus, the corresponding bus lane network on which the selected bus lines run is determined. The solution method using a genetic algorithm in the bi-level programming model is developed, and two numerical examples are investigated to demonstrate the efficacy of the proposed model.
The synergistic effect between photocatalytic and peroxymonosulfate (PMS) activation has been widely applied in the field of sewage treatment. In this work, we synthesized a ...two-dimensional/two-dimensional (2D/2D) CoAl-LDH/BiOBr Z-scheme photocatalyst via a simple method. Then, multiple detection results demonstrated that CoAl-LDH was successfully anchored onto BiOBr, as well as formed an intimate interaction. Moreover, the photocatalytic degradation performance of the catalysts/PMS/vis system had been explored under several conditions (e.g., different catalyst doses, PMS doses, anions and pollutants). The 8 wt% CoAl-LDH/BiOBr composite exhibited the highest degradation efficiency (96%) of ciprofloxacin (CIP). In addition, radicals quenching experiments and electron paramagnetic resonance (EPR) indicated that •O2ˉ and 1O2 were the primary radicals for CIP degradation. The photoelectrochemical measurement and photoluminescence (PL) confirmed that 8 wt% CoAl-LDH/BiOBr exhibited the highest separation and transfer rate of charge carriers. The liquid chromatography-mass spectrometer (LC-MS) analysis revealed that oxidation of the piperazine ring and defluorination were the main CIP degradation pathways. Density functional theory (DFT) calculation, including the laplacian bond order (LBO) and Fukui index, which was consistent with the results of LC-MS. This study explained the superiority of the synergistic effect between photocatalysis and PMS activation on the degradation of pollutants.
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•A novel 2D/2D CoAl-LDH/BiOBr Z-scheme photocatalyst is prepared.•The synergistic effect between photocatalytic and PMS activation.•The reactive sites of ciprofloxacin are firstly revealed by laplacian bond order and Fukui index according to DFT calculation.•The possible degradation pathways of ciprofloxacin and the toxicity of degraded intermediates are suggested.••O2ˉ and 1O2 are the main radicals for ciprofloxacin degradation.
Plant disease resistance genes (R genes) encode proteins that function to monitor signals indicating pathogenic infection, thus playing a critical role in the plant's defense system. Although many ...studies have been performed to explore the functional details of these important genes, their origin and evolutionary history remain unclear.
In this study, focusing on the largest group of R genes, the nucleotide-binding site–leucinerich repeat (NBS-LRR) genes, we conducted an extensive genome-wide survey of 38 representative model organisms and obtained insights into the evolutionary stage and timing of NBS-LRR genes.
Our data show that the two major domains, NBS and LRR, existed before the split of prokaryotes and eukaryotes but their fusion was observed only in land plant lineages. The Toll/interleukin-1 receptor (TIR) class of NBS-LRR genes probably had an earlier origin than its nonTIR counterpart. The similarities of the innate immune systems of plants and animals are likely to have been shaped by convergent evolution after their independent origins.
Our findings start to unravel the evolutionary history of these important genes from the perspective of comparative genomics and also highlight the important role of reorganizing pre-existing building blocks in generating evolutionary novelties.
Mitochondria have emerged as key participants in and regulators of myocardial injury during ischemia and reperfusion. This review examines the sites of damage to cardiac mitochondria during ischemia ...and focuses on the impact of these defects. The concept that mitochondrial damage during ischemia leads to cardiac injury during reperfusion is addressed. The mechanisms that translate ischemic mitochondrial injury into cellular damage, during both ischemia and early reperfusion, are examined. Next, we discuss strategies that modulate and counteract these mechanisms of mitochondrial-driven injury. The new concept that mitochondria are not merely stochastic sites of oxidative and calcium-mediated injury but that they activate cellular responses of mitochondrial remodeling and cellular reactions that modulate the balance between cell death and recovery is reviewed, and the therapeutic implications of this concept are discussed.
Revisiting the Origin of Plant NBS-LRR Genes Shao, Zhu-Qing; Xue, Jia-Yu; Wang, Qiang ...
Trends in plant science,
January 2019, 2019-01-00, 20190101, Letnik:
24, Številka:
1
Journal Article
Recenzirano
The NBS-LRR genes are functionally responsible for plant resistance to alien pathogens. Here, we show that NBS-LRR genes originated in the common ancestor of the whole green lineage, and have rapidly ...diverged into three subclasses with different domain combinations (TNL, CNL, and RNL) before the split of green algae.
Nonlinear behaviors are investigated for a structure coupled with a nonlinear energy sink. The structure is linear and subject to a harmonic excitation, modeled as a forced single-degree-of-freedom ...oscillator. The nonlinear energy sink is modeled as an oscillator consisting of a mass,a nonlinear spring, and a linear damper. Based on the numerical solutions, global bifurcation diagrams are presented to reveal the coexistence of periodic and chaotic motions for varying nonlinear energy sink mass and stiffness. Chaos is numerically identified via phase trajectories, power spectra,and Poincaré maps. Amplitude-frequency response curves are predicted by the method of harmonic balance for periodic steady-state responses. Their stabilities are analyzed.The Hopf bifurcation and the saddle-node bifurcation are determined. The investigation demonstrates that a nonlinear energy sink may create dynamic complexity.
The discovery of the topological transition in twisted bilayer (tBL) materials has attracted considerable attention in nano‐optics. In the analogue of acoustics, however, no such topological ...transition has been found due to the inherent nondirectional scalar property of acoustic pressure. In this work, by using a theory‐based nonlocal anisotropic design, the in‐plane acoustic pressure is transformed into a spatially distributed vector field using twisted multilayer metasurfaces. So‐called “acoustic magic angle”‐related acoustic phenomena occur, such as nonlocal polariton hybridization and the topological Lifshitz transition. The dispersion becomes flat at the acoustic magic angle, enabling polarized excitations to propagate in a single direction. Moreover, the acoustic topological transition (from hyperbolic to elliptic dispersion) is experimentally observed for the first time as the twist angle continuously changes. This unique characteristic facilitates low‐loss tunable polariton hybridization at the subwavelength scale. A twisted trilayer acoustic metasurface is also experimentally demonstrated, and more possibilities for manipulating acoustic waves are found. These discoveries not only enrich the concepts of moiré physics and topological acoustics but also provide a complete framework of theory and methodologies for explaining the phenomena that are observed.
The topological transition in twisted bilayer materials has attracted considerable attention in nano‐optics. In the analogue of acoustics, however, no such topological transition has been found experimentally due to the inherent scalar property of sound pressure. In this work, by using a nonlocal design, the in‐plane acoustic pressure is transformed into a spatially distributed vector field using twisted multilayer metasurfaces.
Mitochondrial Metabolism in Aging Heart Lesnefsky, Edward J; Chen, Qun; Hoppel, Charles L
Circulation research,
05/2016, Letnik:
118, Številka:
10
Journal Article
Recenzirano
Odprti dostop
Altered mitochondrial metabolism is the underlying basis for the increased sensitivity in the aged heart to stress. The aged heart exhibits impaired metabolic flexibility, with a decreased capacity ...to oxidize fatty acids and enhanced dependence on glucose metabolism. Aging impairs mitochondrial oxidative phosphorylation, with a greater role played by the mitochondria located between the myofibrils, the interfibrillar mitochondria. With aging, there is a decrease in activity of complexes III and IV, which account for the decrease in respiration. Furthermore, aging decreases mitochondrial content among the myofibrils. The end result is that in the interfibrillar area, there is ≈50% decrease in mitochondrial function, affecting all substrates. The defective mitochondria persist in the aged heart, leading to enhanced oxidant production and oxidative injury and the activation of oxidant signaling for cell death. Aging defects in mitochondria represent new therapeutic targets, whether by manipulation of the mitochondrial proteome, modulation of electron transport, activation of biogenesis or mitophagy, or the regulation of mitochondrial fission and fusion. These mechanisms provide new ways to attenuate cardiac disease in elders by preemptive treatment of age-related defects, in contrast to the treatment of disease-induced dysfunction.
Cutaneous melanoma (CM) is a life-threatening form of skin cancer. Prognostic biomarkers can reliably stratify patients at initial melanoma diagnosis according to risk, and may inform clinical ...decisions. Here, we performed a retrospective, cohort-based study analyzing genome-wide DNA methylation of 461 patients with CM from the TCGA database. Cox regression analyses were conducted to establish a four-DNA methylation signature that was significantly associated with the overall survival (OS) of patients with CM, and that was validated in an independent cohort. Corresponding Kaplan-Meier analysis displayed a distinct separation in OS. The ROC analysis confirmed that the predictive signature performed well. Notably, this signature exhibited much higher predictive accuracy in comparison with known biomarkers. This signature was significantly correlated with immune checkpoint blockade (ICB) immunotherapy-related signatures, and may have potential as a guide for measures of responsiveness to ICB immunotherapy.
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