Hopf bifurcation of a tumor immune model with time delay

In this paper, a tumor immune model with time delay is studied. First, the stability of nonnegative equilibria is analyzed. Then the time delay τ is selected as a bifurcation parameter and the existence of Hopf bifurcation is proved. Finally, by using the canonical method and the central manifold theory, the criteria for judging the direction and stability of Hopf bifurcation are given.     

Mass spectrometry-based chemical mapping and profiling toward molecular understanding of diseases in precision medicine

Precision medicine has been strongly promoted in recent years. It is used in clinical management for classifying diseases at the molecular level and for selecting the most appropriate drugs or treatments to maximize efficacy and minimize adverse effects. In precision medicine, an in-depth molecular understanding of diseases is of great importance. Therefore, in the last few years, much attention has been given to translating data generated at the molecular level into clinically relevant information. However, current developments in this field lack orderly implementation. For example, high-quality chemical research is not well integrated into clinical practice, especially in the early phase, leading to a lack of understanding in the clinic of the chemistry underlying diseases. In recent years, mass spectrometry (MS) has enabled significant innovations and advances in chemical research. As reported, this technique has shown promise in chemical mapping and profiling for answering “what”, “where”, “how many” and “whose” chemicals underlie the clinical phenotypes, which are assessed by biochemical profiling, MS imaging, molecular targeting and probing, biomarker grading disease classification, etc. These features can potentially enhance the precision of disease diagnosis, monitoring and treatment and thus further transform medicine. For instance, comprehensive MS-based biochemical profiling of ovarian tumors was performed, and the results revealed a number of molecular insights into the pathways and processes that drive ovarian cancer biology and the ways that these pathways are altered in correspondence with clinical phenotypes. Another study demonstrated that quantitative biomarker mapping can be predictive of responses to immunotherapy and of survival in the supposedly homogeneous group of breast cancer patients, allowing for stratification of patients. In this context, our article attempts to provide an overview of MS-based chemical mapping and profiling, and a perspective on their clinical utility to improve the molecular understanding of diseases for advancing precision medicine.

An overview of MS-based chemical mapping and profiling, indicating its contributions to the molecular understanding of diseases in precision medicine by answering "what", "where", "how many" and "whose” chemicals underlying clinical phenotypes.     

N-Butyrylated Hyaluronic Acid Achieves Anti-Inflammatory Effects In Vitro and in Adjuvant-Induced Immune Activation in Rats

Previously synthesized N-butyrylated hyaluronic acid (BHA) provides anti-inflammatory effects in rat models of acute gouty arthritis and hyperuricemia. However, the mechanism of action remains to be elucidated. Herein, the anti-inflammatory and antioxidative activities of BHA and the targeted signaling pathways were explored with LPS-induced RAW264.7 and an adjuvant-induced inflammation in a rat model. Results indicated that BHA inhibited the generation of pro-inflammatory cytokines TNFα, IL-1β and IL-6, reduced ROS production and down-regulated JAK1-STAT1/3 signaling pathways in LPS-induced RAW264.7. In vivo, BHA alleviated paw and joint swelling, decreased inflammatory cell infiltration in paw tissues, suppressed gene expressions of p38 and p65, down-regulated the NF-κB and MAPK signaling pathways and reduced protein levels of TNFα, IL-1β and IL-6 in joint tissues of arthritis rats. This study demonstrated the pivotal role of BHA in anti-inflammation and anti-oxidation, suggesting the potential clinical value of BHA in the prevention of inflammatory arthritis and is worthy for development as a new pharmacological treatment.     

高频感应等离子体流动模型与微型电推进器流场特性分析

微型射频离子推力器具有结构简单、 工作寿命长、 推力动态范围大、 性能调节响应灵敏等特点,是国际微电推进领域的研究热点之一.射频离子推力器电离室内的感性耦合放电等离子体特性和推力器的性能密切相关.为此,文章建立了低气压、小尺寸微型射频离子推力器电离室内感性耦合等离子体流体模型,开展了电磁场、流场、化学反应浓度场的多物理...     

结构方程模型应用陷阱分析

结构方程模型近几年在我国心理学、管理学应用研究领域得到越来越多的应用,但部分应用者因其对其基本原理理解不够透彻导致误用或错用这种重要统计手段。本文通过结合实证研究实例对一些常见应用错误(问题)的分析揭示结构方程模型的原理,以期帮助应用者避免应用陷阱、提高实证研究水平。     

射频辅助N掺杂ZnO薄膜的生长及其光电特性

在MOCVD设备中采用改进的射频辅助生长装置,通过裂解N2及N-Al共掺杂的方法进行ZnO的p型掺杂研究。通过二次离子质谱(SIMS)、X射线衍射(XRD)、原子力显微镜(AFM)、光致发光(PL)谱等方法分析了薄膜中N杂质的浓度,以及射频功率与晶体质量、表面形貌以及光学特性之间的关系,并与Al掺杂和N掺杂的ZnO薄膜进行对比。实验结果表明,N掺杂的浓度高达1020cm-3;N-Al共掺杂极大地增加了ZnO的成核速率,其主要原因是N离化所起的作用;N-Al共掺的ZnO薄膜显示出p型性质,而N掺杂的ZnO薄膜由于N原子处于非激活状态而呈现高阻,这说明N-Al共掺杂对ZnO中N原子的活化起到一定作用。     

ZnO薄膜的椭偏和DLTS特性

用射频磁控溅射在硅衬底上淀积氧化锌薄膜,并对样品分别作氮气、空气、氧气等不同条件下退火处理。为研究退火气氛对ZnO/Si薄膜中缺陷以及折射率的影响,由深能级瞬态谱(DLTS)以及椭偏测量方法进行了检测。椭偏测量结果表明相对原始生长的样品,在氮气和空气退火使ZnO薄膜折射率下降,但氧气中退火使折射率升高。我们对折射率的这种变化机理进行了解释。DLTS测量得到一个与Zni**相关的深能级中心E1存在,氧气气氛退火可以消除E1能级。在氮气退火情况下Zn*i*的存在对抑制VO引起的薄膜折射率下降有利。     

自呼吸式DMFC电堆构建与电池性能研究

本文报道了一种能驱动风扇工作的自呼吸式DMFC小型电堆,电堆主要南燃料储罐、膜电极(MEA)、集流体等组成.文中针对影响该电池性能的主要参数,如电堆的活化过程、甲醇浓度等因素进行了研究.同时,本文还对电堆的恒电流放电时的电流曲线特点以及阴极水的生成规律进行了初步考察和探讨.     

模具钢表面激光毛化工艺的试验研究

以模具工业45^#钢摩擦学设计及性能要求为基础,分析了激光毛化模具钢表面形貌的形成机理及其关键的影响因素。采用灯泵浦Nd：YAG脉冲激光器在试样表面进行激光毛化工艺试验,获得了合理的激光毛化参数范围：激光峰值功率0．8～1．6kW,离焦量-1．4～-0．4mm、＋0．4～4-1．4mm,辅助气体压力〉0．2MPa,脉宽1．8ms。采用功率增益和氧气保护,可加工出预先设定的微火山口状毛化形貌。微凹坑形貌的成功获得对于提高拉伸模具的摩擦磨损性能,进一步掌握激光毛化参数与材料的作用规律,提供了有效的数据参考。     

地表层的本质对于地震勘测的几种影响

一.概论用物理学的原理来计算实际问题,常常要将实际的情况先简单化或理想化,然后纔能得到有用的结果。物理探矿就是一个例子。解释地震记录时,最普通而又最简单的方法,是先假设有关的地层都是均匀、连续而又带有完全弹性的固体。