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Stability and Coexistence of a Diffusive Predator-Prey System with Nonmonotonic Functional Response and Fear Effect

Xiaozhou Feng, Hao Sun, Yangfan Xiao, Feng Xiao, Songbai Guo
2020 Complexity  
This paper investigates the diffusive predator-prey system with nonmonotonic functional response and fear effect. Firstly, we discussed the stability of the equilibrium solution for a corresponding ODE system. Secondly, we established a priori positive upper and lower bounds for the positive solutions of the PDE system. Thirdly, sufficient conditions for the local asymptotical stability of two positive equilibrium solutions of the system are given by using the method of eigenvalue spectrum
more » ... sis of linearization operator. Finally, the existence and nonexistence of nonconstant positive steady states of this reaction-diffusion system are established by the Leray–Schauder degree theory and Poincaré inequality.
doi:10.1155/2020/8899114 fatcat:pnmikals2fciraa7kd2wsx6dv4

Study on multi-axis sine vibration test control techniques

Hanping Qiu, Yaoqi Feng, Shichao Fan, Xiaozhou Du, Wenbing Zhang
2019 Vibroengineering PROCEDIA  
This paper describes several key aspects about multi-axis sine vibration test control techniques including the identification of the system frequency response function, synchronization of the input and output signals, the generation of the sinewave, the control algorithm, etc. A multi-axis sine vibration controller is developed based on these key techniques and the major framework of the controller is introduced. Finally, a dual axial experiment is carried out by the controller. The test
more » ... show the feasibility of the control algorithm and the good control strategy of the multi-axis sine vibration controller in which the key techniques are realized.
doi:10.21595/vp.2019.21011 fatcat:5kbzwiubzjdvrf7z5ztyikry5u

Current Research on Opioid Receptor Function

Yuan Feng, Xiaozhou He, Yilin Yang, Dongman Chao, Lawrence H. Lazarus, Ying Xia
2012 Current Drug Targets  
The use of opioid analgesics has a long history in clinical settings, although the comprehensive action of opioid receptors is still less understood. Nonetheless, recent studies have generated fresh insights into opioid receptor-mediated functions and their underlying mechanisms. Three major opioid receptors (μ-opioid receptor, MOR; δ-opioid receptor, DOR; and κ-opioid receptor, KOR) have been cloned in many species. Each opioid receptor is functionally sub-classified into several
more » ... l subtypes, although, specific gene corresponding each of these receptor subtypes is still unidentified as only a single gene has been isolated for each opioid receptor. In addition to pain modulation and addiction, opioid receptors are widely involved in various physiological and pathophysiological activities, including the regulation of membrane ionic homeostasis, cell proliferation, emotional response, epileptic seizures, immune function, feeding, obesity, respiratory and cardiovascular control as well as some neurodegenerative disorders. In some species, they play an essential role in hibernation. One of the most exciting findings of the past decade is the opioid-receptor, especially DOR, mediated neuroprotection and cardioprotection. The up-regulation of DOR expression and DOR activation increase the neuronal tolerance to hypoxic/ischemic stress. The DOR signal triggers (depending on stress duration and severity) different mechanisms at multiple levels to preserve neuronal survival, including the stabilization of homeostasis and increased pro-survival signaling (e.g., PKC-ERK-Bcl 2) and antioxidative capacity. In the heart, PKC and KATP channels are involved in the opioid receptormediated cardioprotection. The DOR-mediated neuroprotection and cardioprotection have the potential to significantly alter the clinical pharmacology in terms of prevention and treatment of life-threatening conditions like stroke and myocardial infarction. The main purpose of this article is to review the recent work done on opioids and their receptor functions. It shall provide an informative reference for better understanding the opioid system and further elucidation of the opioid receptor function from a physiological and pharmacological point of view.
doi:10.2174/138945012799201612 pmid:22204322 pmcid:PMC3371376 fatcat:4pdkrq6y5jetbfdyr6rc2p6qpu

Tissue plasminogen activator-based nanothrombolysis for ischemic stroke

Shan Liu, Xiaozhou Feng, Rong Jin, Guohong Li
2017 Expert Opinion on Drug Delivery  
Introduction-Thrombolysis with intravenous tissue plasminogen activator (tPA) is the only FDA approved treatment for patients with acute ischemic stroke, but its use is limited by narrow therapeutic window, selective efficacy, and hemorrhagic complication. In the past two decades, extensive efforts have been undertaken to extend its therapeutic time window and explore alternative thrombolytic agents, but both show little progress. Nanotechnology has emerged as a promising strategy to improve
more » ... efficacy and safety of tPA. Areas covered-We reviewed the biology, thrombolytic mechanism, and pleiotropic functions of tPA in the brain and discussed current applications of various nanocarriers intended for the delivery of tPA for treatment of ischemic stroke. Current challenges and potential further directions of t-PA-based nanothrombolysis in stroke therapy are also discussed. Expert opinion-Using nanocarriers to deliver tPA offers many advantages to enhance the efficacy and safety of tPA therapy. Further research is needed to characterize the physicochemical characteristics and in vivo behavior of tPA-loaded nanocarriers. Combination of tPA based nanothrombolysis and neuroprotection represents a promising treatment strategy for acute ischemic stroke. Theranostic nanocarriers co-delivered with tPA and imaging agents are also promising for future stroke management.
doi:10.1080/17425247.2018.1384464 pmid:28944694 pmcid:PMC5780255 fatcat:3lvouzhsdbce5jivj2dpdvjoye

Asymptotic Behavior Analysis of a Fractional-Order Tumor-Immune Interaction Model with Immunotherapy

Wenbin Yang, Xiaozhou Feng, Shuhui Liang, Xiaojuan Wang
2020 Complexity  
A fractional-order tumor-immune interaction model with immunotherapy is proposed and examined. The existence, uniqueness, and nonnegativity of the solutions are proved. The local and global asymptotic stability of some equilibrium points are investigated. In particular, we present the sufficient conditions for asymptotic stability of tumor-free equilibrium. Finally, numerical simulations are conducted to illustrate the analytical results. The results indicate that the fractional order has a
more » ... ilization effect, and it may help to control the tumor extinction.
doi:10.1155/2020/7062957 fatcat:mxd4joi3zzeargryj4vckza4pm

Hilbert space fragmentation produces a "fracton Casimir effect" [article]

Xiaozhou Feng, Brian Skinner
2021 arXiv   pre-print
ACKNOWLEDGMENTS The authors are grateful to Xiaoyu Feng, Andrey Gromov, Jason Iaconis, Adam Nahum, Rahul Nandkishore, and Shriya Pai for helpful discussions, and to Pablo Sala and Michael Knap for bringing  ... 
arXiv:2105.11465v1 fatcat:eqghg5lm2bbc7jf6amlfqahrvu

Large enhancement of thermopower at low magnetic field in compensated semimetals [article]

Xiaozhou Feng, Brian Skinner
2020 arXiv   pre-print
The thermoelectric properties of conductors with low electron density can be altered significantly by an applied magnetic field. For example, recent work has shown that Dirac/Weyl semimetals with a single pocket of carriers can exhibit a large enhancement of thermopower when subjected to a sufficiently large field that the system reaches the extreme quantum limit, in which only a single Landau level is occupied. Here we study the magnetothermoelectric properties of compensated semimetals, for
more » ... ich pockets of electron- and hole-type carriers coexist at the Fermi level. We show that, when the compensation is nearly complete, such systems exhibit a huge enhancement of thermopower starting at a much smaller magnetic field, such that ω_cτ > 1, and the stringent conditions associated with the extreme quantum limit are not necessary. We discuss our results in light of recent measurements on the compensated Weyl semimetal tantalum phosphide, in which an enormous magnetothermoelectric effect was observed. We also calculate the Nernst coefficient of compensated semimetals, and show that it exhibits a maximum value with increasing magnetic field that is much larger than in the single band case. In the dissipationless limit, where the Hall angle is large, the thermoelectric response can be described in terms of quantum Hall edge states, and we use this description to generalize previous results to the multi-band case.
arXiv:2010.07933v1 fatcat:3gxjlcvcbfeuxogtais35yfulq

Uniqueness and Multiplicity of a Prey-Predator Model with Predator Saturation and Competition

Xiaozhou Feng, Lifeng Li
2012 Journal of Applied Mathematics  
We investigate positive solutions of a prey-predator model with predator saturation and competition under homogeneous Dirichlet boundary conditions. First, the existence of positive solutions and some sufficient and necessary conditions is established by using the standard fixed point index theory in cones. Second, the changes of solution branches, multiplicity, uniqueness, and stability of positive solutions are obtained by virtue of bifurcation theory, perturbation theory of eigenvalues, and
more » ... he fixed point index theory. Finally, the exact number and type of positive solutions are proved whenkormconverges to infinity.
doi:10.1155/2012/627419 fatcat:jlogl4ko45eqnoyaan3gjmqj6i

Complex Dynamics of Beddington–DeAngelis-Type Predator-Prey Model with Nonlinear Impulsive Control

Changtong Li, Xiaozhou Feng, Yuzhen Wang, Xiaomin Wang, Xinzhu Meng
2020 Complexity  
According to resource limitation, a more realistic pest management is that the impulsive control actions should be adjusted according to the densities of both pest and natural enemy in the field, which result in nonlinear impulsive control. Therefore, we have proposed a Beddington–DeAngelis interference predator-prey model concerning integrated pest management with both density-dependent pest and natural enemy population. We find that the pest-eradication periodic solution is globally stable if
more » ... the impulsive period is less than the critical value by Floquet theorem. The condition of permanent is established, and a stable positive periodic solution appears via a supercritical bifurcation by bifurcation theorem. Finally, in order to investigate the effects of those nonlinear control strategies on the successful pest control, the bifurcation diagrams showed that the model exists with very complex dynamics. Consequently, the resource limitation may result in pest outbreak in complex ways, which means that the pest control strategies should be carefully designed.
doi:10.1155/2020/8829235 fatcat:z3ci25yne5fvjndckq6lfyllqy

The tensor products of quantales

Shaohui Liang, Shengwei Han, Xiaozhou Feng
2012 2012 2nd International Conference on Applied Robotics for the Power Industry (CARPI)  
In this paper, the definition of bimorphism of unital quantales is given, Base on the tensor product of completed lattice, the concrete forms of the tensor product of unital quantales is obatined, and some properties of their are discussed.
doi:10.1109/carpi.2012.6356442 fatcat:72iblen65jcn5ki7mr3dq6xzvu

Constructing phase boundary in AgNbO3 antiferroelectrics: pathway simultaneously achieving high energy density and efficiency

Nengneng Luo, Kai Han, Matthew J. Cabral, Xiaozhou Liao, Shujun Zhang, Changzhong Liao, Guangzu Zhang, Xiyong Chen, Qin Feng, Jing-Feng Li, Yuezhou Wei
2020 Nature Communications  
Dielectric capacitors with high energy storage density (Wrec) and efficiency (η) are in great demand for high/pulsed power electronic systems, but the state-of-the-art lead-free dielectric materials are facing the challenge of increasing one parameter at the cost of the other. Herein, we report that high Wrec of 6.3 J cm-3 with η of 90% can be simultaneously achieved by constructing a room temperature M2–M3 phase boundary in (1-x)AgNbO3-xAgTaO3 solid solution system. The designed material
more » ... ts high energy storage stability over a wide temperature range of 20–150 °C and excellent cycling reliability up to 106 cycles. All these merits achieved in the studied solid solution are attributed to the unique relaxor antiferroelectric features relevant to the local structure heterogeneity and antiferroelectric ordering, being confirmed by scanning transmission electron microscopy and synchrotron X-ray diffraction. This work provides a good paradigm for developing new lead-free dielectrics for high-power energy storage applications.
doi:10.1038/s41467-020-18665-5 pmid:32973146 fatcat:d7qwhqnqtbfzrammlyckf22zge

Dynamic behavior analysis of a prey-predator model with ratio-dependent Monod-Haldane functional response

Xiaozhou Feng, Yi Song, Xiaomin An
2018 Open Mathematics  
This paper investigates the dynamic behavior analysis on the prey-predator model with ratio-dependent Monod-Haldane response function under the homogeneous Dirichlet boundary conditions, which is used to simulate a class of biological system. Firstly, the sufficient and necessary conditions on existence and non-existence of coexistence states of this model are discussed by comparison principle and fixed point index theory. Secondly, taking a as a main bifurcation parameter, the structure of
more » ... al bifurcation curve on positive solutions is established by using global bifurcation theorem and properties of principal eigenvalue. Finally, the stability of coexistence states is obtained by the eigenvalue perturbation theory; the multiplicity of coexistence states is investigated when a satisfies some condition by the fixed point index theory.
doi:10.1515/math-2018-0060 fatcat:2qbuz7fcgveizorqd2cn3rzhom

Comparison of tolerance of four bacterial nanocellulose-producing strains to lignocellulose-derived inhibitors

Xiaozhou Zou, Guochao Wu, Stefan Stagge, Lin Chen, Leif J. Jönsson, Feng F. Hong
2017 Microbial Cell Factories  
Through pretreatment and enzymatic saccharification lignocellulosic biomass has great potential as a low-cost feedstock for production of bacterial nanocellulose (BNC), a high value-added microbial product, but inhibitors formed during pretreatment remain challenging. In this study, the tolerance to lignocellulose-derived inhibitors of three new BNC-producing strains were compared to that of Komagataeibacter xylinus ATCC 23770. Inhibitors studied included furan aldehydes (furfural and
more » ... ethylfurfural) and phenolic compounds (coniferyl aldehyde and vanillin). The performance of the four strains in the presence and absence of the inhibitors was assessed using static cultures, and their capability to convert inhibitors by oxidation and reduction was analyzed. Results: Although two of the new strains were more sensitive than ATCC 23770 to furan aldehydes, one of the new strains showed superior resistance to both furan aldehydes and phenols, and also displayed high volumetric BNC yield (up to 14.78 ± 0.43 g/L) and high BNC yield on consumed sugar (0.59 ± 0.02 g/g). The inhibitors were oxidized and/or reduced by the strains to be less toxic. The four strains exhibited strong similarities with regard to predominant bioconversion products from the inhibitors, but displayed different capacity to convert the inhibitors, which may be related to the differences in inhibitor tolerance. Conclusions: This investigation provides information on different performance of four BNC-producing strains in the presence of lignocellulose-derived inhibitors. The results will be of benefit to the selection of more suitable strains for utilization of lignocellulosics in the process of BNC-production.
doi:10.1186/s12934-017-0846-y pmid:29268745 pmcid:PMC5738851 fatcat:fzpl3r37jjd4pn2kgdpr35d4ni

Global Bifurcation Structure of a Predator-Prey System with a Spatial Degeneracy and B-D Functional Response

Xiaozhou Feng, Changtong Li, Hao Sun, Yuzhen Wang, Abdel-Haleem Abdel-Aty
2021 Complexity  
In this paper, we investigate a predator-prey system with Beddington–DeAngelis (B-D) functional response in a spatially degenerate heterogeneous environment. First, for the case of the weak growth rate on the prey ( λ 1 Ω < a < λ 1 Ω 0 ), a priori estimates on any positive steady-state solutions are established by the comparison principle; two local bifurcation solution branches depending on the bifurcation parameter are obtained by local bifurcation theory. Moreover, the demonstrated two local
more » ... bifurcation solution branches can be extended to a bounded global bifurcation curve by the global bifurcation theory. Second, for the case of the strong growth rate on the prey ( a > λ 1 Ω 0 ), a priori estimates on any positive steady-state solutions are obtained by applying reduction to absurdity and the set of positive steady-state solutions forms an unbounded global bifurcation curve by the global bifurcation theory. In the end, discussions on the difference of the solution properties between the traditional predator-prey system and the predator-prey system with a spatial degeneracy and B-D functional response are addressed.
doi:10.1155/2021/9970255 fatcat:44i3v4xvrjgl3ktisztms7xuo4

The antitumor activity and preliminary modeling on the potential mechanism of action of human peroxiredoxin-5

Juanjuan Liu, Xiaozhou Feng, Yuanyuan Jin, Zhengyang Sun, Haoyi Meng, Zhifei Zhang, Laixing Hu, Zhaoyong Yang
2017 OncoTarget  
Goat peroxiredoxin-5 (gPRDX5) was verified as a good anti-cancer bioactive peptide (ACBP) against different tumor cell lines. Considering the immunogenicity between species for further therapeutic application, it is necessary to similarly investigate the antitumor activity of human peroxiredoxin-5 (hPRDX5) with 89% similarity in sequence to gPRDX5. In order to evaluate its antitumor activity, the potential anti-neoplastic effect of hPRDX5 on a mouse model was observed directly. The results of
more » ... s in vivo antitumor activity suggested that hPRDX5 could resist immunosuppression by promoting lymphocyte proliferation and up-regulating the levels of serum cytokines. Meanwhile, PD-L1 was speculated as one of the targets of hPRDX5 to inhibit tumor by enhancing the immune activity according to a preliminary molecular docking study on the interactions between hPRDX5 and PD-L1. The modeling provides a basis for structural modification on hPRDX5/PD-L1 for further biological and biochemical study on the pathway blocking mechanism of hPRDX5. In this work, the results demonstrate that hPRDX5 displays efficient antitumor and immunoregulatory properties in the colon cancer C26/BALB/c and melanoma B16/C57Bl/6 mice tumor models, and suggest the potential of developing peptides from hPRDX5 as low molecular weight drug candidates for corresponding cancer immunotherapy.
doi:10.18632/oncotarget.16089 pmid:28423711 pmcid:PMC5432328 fatcat:5dcnct3kxrc2xopeqnuxznwrru
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