车轮多边形磨耗参数对地铁车辆动力学性能影响分析

针对车轮多边形磨耗不同状态下对车辆动力学影响展开研究,建立轮轨柔性某地铁B型车辆刚柔耦合动力学模型,计算车轮多边形阶数和谐波幅值变化对轮轨垂向力、轮轨振动、运行平稳性等车辆动力学性能的影响。结果表明:阶数和谐波幅值在速度增大时轮轨垂向力逐渐增大;阶数14阶、18阶是轮对和轴箱振动加速度随谐波幅值变化产生振动的主要诱因;动力学指标中轮重减载率在18阶、0.04 mm时对其影响最大;车轮多边形使钢轨垂向动位移和振动加速度增大,谐波幅值对钢轨振动特性更有影响。建议考虑制造轮轨柔性,18阶、0.04 mm时对轮轨璇修打磨,以提高动力学性能和行车安全性。

蔬菜染色再生纸制作的科普实验

本科普实验基于再生纸的制作方法和蔬菜天然色素知识,设计了具有科学性、趣味性和简单易行特点的蔬菜染色再生纸制作实验。此外,本实验还创造性地将蔬菜染色纸和染色纸浆创作成充满趣味性的纸浆画、杯垫、折纸等手工作品。希望能借此科普实验让大众了解再生纸制作的化学原理和天然色素的提取方法,并加强对化学可持续发展理念的实践。

Optimization Design and Performance Analysis of Vehicle Powertrain Mounting System

The design strategies for powertrain mounting systems play an important role in the reduction of vehicular vibration and noise. As stiffness and damping elements connecting the transmission system and vehicle body, the rubber mount exhibits better vibration isolation performance than the rigid connection. This paper presents a complete design process of the mounting system, including the vibration decoupling, vibration simulation analysis, topology optimization, and experimental verification. Based on the 6?degrees?of?freedom vibration coupling model of the powertrain mounting system, an optimization algorithm is used to extract the best design parameters of each mount, thus rendering the mounting system fully decoupled and the natural frequency well configured, and the optimal parameters are used to design the mounting system. Subsequently, vibration simulation analysis is applied to the mounting system, considering both transmission and road excitations. According to the results of finite element analysis, the topological structure of the metal frame of the front mount is optimized to improve the strength and dynamic characteristics of the mounting system. Finally, the vibration bench test is used to verify the availability of the optimization design with the analysis of acceleration response and vibration transmissibility of the mounting system. The results show that the vibration isolation performance of the mounting system can be improved effectively using the vibration optimal decoupling method, and the structural modification of the metal frame can well promote the dynamic characteristics of the mounting system.

The Effects of Dietary Restriction and Aging on in Vivo and in Vitro Binding of Aflatoxin B_1 to Cellular DNA

Laboratory animals maintained on a reduced calorie but nutritionally adequate diet have extended life spans and lowered incidences of spontaneous and chemically induced cancers compared to ad libitum- fed counterparts. Many of the effects of dietary restriction on laboratory animals have been suggested to be related to a deceleration of the aging process. The inhibition of age-related changes in xenobiotic metabolizing enzyme activities by dietary restriction has previously been reported. Alterations of these enzyme activities may cause changes in metabolic activation of carcinogens and, therefore, carcinogen-DNA binding. DNA-repair capability has also been reported to be enhanced in diet-restricted rats. Using AFB1 as a model carcinogen, we have studied in vivo and in vitro hepatic AFB1 -DNA binding, demonstrating that dietary restriction (60% of ad libitum consumption) may decrease the metabolic activation of AFB1, and subsequently reduce AFB 1-DNA binding. Our preliminary results obtained from the AFB 1-DNA binding experiments in isolated hepatocytes suggest that the observed age-dependent reduction in AFB 1-DNA binding which may be attributed to a loss of metabolic activating capability was delayed in the diet-restricted rats.

Therapeutic effect of minimally invasive intracranial hematoma evacuation in the treatment of hypertensive cerebral hemorrhage and TCD evaluation

Objective:To explore the therapeutic effect of minimally invasive intracranial hematoma evacuation in the treatment of hypertensive cerebral hemorrhage and the value of dynamic TCD monitoring in predicting the neurological function recovery.Methods: A total of 70 patients with hypertensive cerebral hemorrhage who were admitted in our hospital were included in the study and divided into the minimally invasive group and conservative group with 35 cases in each group according to different treatment protocols. The patients in the two groups were given drug conservative treatments. On this basis, the patients in the minimally invasive group were given urokinase in combined with minimally invasive hematoma puncture with YL-1 type needle. TCD was performed before treatment, 1 d, 5 d, 10 d, and 21 d after treatment. The hematoma and edema volume was calculated. NIHSS was used to evaluate the neurological function recovery.Results: Vs, Vd, and Vm after treatment in the minimally invasive group were significantly elevated, while PI was significantly reduced. Vs, Vd, and Vm after treatment in the conservative group were reduced first and elevated later, while PI was elevated first and reduced later, and reached the lowest/peak 10d after treatment. Vs, Vd, and Vm 5 d, 10 d, and 21 d after treatment in the minimally invasive group were significantly higher than those in the conservative group, while PI was significantly lower than that in the conservative group. The hematoma and edema volume after treatment in the two groups was significantly reduced. The hematoma and edema volume at each timing point was significantly lower than that in the conservative group. NIHSS score after treatment in the minimally invasive group was significantly reduced. NIHSS score in the conservative group was elevated first and reduced later, reached the peak 10d after treatment, and at each timing point was higher than that in the minimally invasive group.Conclusions:The early minimally invasive operation can significantly improve the hematoma adjacent blood flow volume in patients with hypertensive cerebral hemorrhage, and contribute to the neurological function recovery. TCD not only can be applied in the dynamic monitoring of cerebral blood flow volume in patients with hypertensive cerebral hemorrhage, but also has a certain value in evaluating the prognosis of neurological function.

Phase separation in cGAS-STING signaling

Biomolecular condensates formed by phase separation are widespread and play critical roles in many physiological and pathological processes.cGAS-STING signaling functions to detect aberrant DNA signals to initiate anti-infection defense and antitumor immunity.At the same time,cGAS-STING signaling must be carefully regulated to maintain immune homeostasis.Interestingly,exciting recent studies have reported that biomolecular phase separation exists and plays important roles in different steps of cGAS-STING signaling,including cGAS condensates,STING condensates,and IRF3 condensates.In addition,several intracellular and extracellular factors have been proposed to modulate the condensates in cGAS-STING signaling.These studies reveal novel activation and regulation mechanisms of cGAS-STING signaling and provide new opportunities for drug discovery.Here,we summarize recent advances in the phase separation of cGAS-STING signaling and the development of potential drugs targeting these innate immune condensates.

E）NA sensor cGAS-mediated immune recognition

The host takes use of pattern recognition receptors （PRRs） to defend against pathogen invasion or cellular damage. Among microorganism-associated molecular patterns detected by host PRRs, nucleic acids derived from bacteria or viruses are tightly supervised, providing a fundamental mechanism of host defense. Pathogenic DNAs are supposed to be detected by DNA sensors that induce the activation of NFKB or TBKI-IRF3 pathway. DNA sensor cGAS is widely expressed in innate immune cells and is a key sensor of invading DNAs in several cell types, cGAS binds to DNA, followed by a conformational change that allows the synthesis of cyclic guanosine monophosphate-adenosine monophosphate （cGAMP） from adenosine triphosphate and guanosine triphos- phate, cGAMP is a strong activator of STING that can activate IRF3 and subsequent type I interferon produc- tion. Here we describe recent progresses in DNA sensors especially cGAS in the innate immune responses against pathogenic DNAs.