Cath-KP,a novel peptide derived from frog skin,prevents oxidative stress damage in a Parkinson’s disease model

Parkinson’s disease(PD)is a neurodegenerative condition that results in dyskinesia,with oxidative stress playing a pivotal role in its progression.Antioxidant peptides may thus present therapeutic potential for PD.In this study,a novel cathelicidin peptide(Cath-KP;GCSGRFCNLF NNRRPGRLTLIHRPGGDKRTSTGLIYV)was identified from the skin of the Asiatic painted frog(Kaloula pulchra).Structural analysis using circular dichroism and homology modeling revealed a uniqueαββconformation for Cath-KP.In vitro experiments,including free radical scavenging and ferric-reducing antioxidant analyses,confirmed its antioxidant properties.Using the 1-methyl-4-phenylpyridinium ion(MPP^(+))-induced dopamine cell line and 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine(MPTP)-induced PD mice,Cath-KP was found to penetrate cells and reach deep brain tissues,resulting in improved MPP^(+)-induced cell viability and reduced oxidative stress-induced damage by promoting antioxidant enzyme expression and alleviating mitochondrial and intracellular reactive oxygen species accumulation through Sirtuin-1(Sirt1)/Nuclear factor erythroid 2-related factor 2(Nrf2)pathway activation.Both focal adhesion kinase(FAK)and p38 were also identified as regulatory elements.In the MPTP-induced PD mice,Cath-KP administration increased the number of tyrosine hydroxylase(TH)-positive neurons,restored TH content,and ameliorated dyskinesia.To the best of our knowledge,this study is the first to report on a cathelicidin peptide demonstrating potent antioxidant and neuroprotective properties in a PD model by targeting oxidative stress.These findings expand the known functions of cathelicidins,and hold promise for the development of therapeutic agents for PD.

Pathogenesis of Parkinson＇s disease： oxidative stress, environmental impact factors and inflammatory processes

Current hypothesis of neuronal degeneration in Parkinson＇s disease （PD） have been proposed, including formation of free radicals and oxidative stress, mitochondrial dysfunction, excitotoxicity, trophic factor deficiency, inflammatory processes, genetic factors, environmental impact factors, toxic action of nitric oxide, apoptosis, and so on. This review mainly discussed oxidative stress, environmental impact factors, and inflammatory processes in PD.

边坡稳定性中BISHOP法的解析计算

针对简化Bishop法，采用精确积分代替有限条块的求和，获得了边坡安全系数的解析表达式．这样只需通过迭代求解一代数方程就可获得边坡的安全系数，避免了有限条分法中计算繁杂以及在试算时初值选取不当可能存在不收敛的缺点．此外，利用该解析算式可容易获得边坡的最危险圆弧滑裂面和最小安全系数．在同样的边坡条件下，简化Bishop法的安全系数一般比瑞典条分法高6％～7％．

Effect of stress on microstructures of creep-aged 2524 alloy

Microstructures of creep-aged 2524 （A1-4.3Cu-1.5Mg） aged at 170 ℃ with various stresses （0, 173 and 250 MPa） were studied on a creep machine. Ageing hardness curves under various stresses were plotted and the corresponding microstructures were characterized by transmission electron microscopy （TEM）. The results show that the value of peak hardness is increased, while the time to reach the peak hardness is reduced under an external stress. Meanwhile, the length of S（Al2CuMg） phase is shorter and the number density of S phases is larger in the creep-aged alloy. The predominant contribution to the peak hardness can be ascribed to the GPB zones with an elastic stress.

面心立方金属｛111｝<110>滑移和 ｛111｝<112>孪生平面 共生变形的Bishop—Hill分析

将 Ｂｉｓｈｏｐ－Ｈｉｌｌ最大功原理拓展于 ｆｃｃ金属｛１１１｝｛１１０｝滑移和｛１１１｝（１１２）孪生两种机制同时起作用的平面共生变形研究了不同临界剪切应力（ＣＲＳＳ）之比ε对各理想取向的屈服应力状态及相应活化系的影响．分析结果表明，当ε＞１／３（１／２）时，Ｃ，Ｇ和Ｒｃｕ ３种取向共同的活化系均为滑移系，不易孪生；其它５种取向共同的活化系均包括滑移系和孪生系，有孪生倾向．同时分析了取向空间里屈服强度各向异性及 Ｔａｙｌｏｒ因子 Ｍ的变化规律，发现当引入孪生机制时，随着ε的减小，与仅发生滑移变形的情况相比，其屈服强度各向异性越来越小；最强和最弱的Ｍ值同时也变得越来越小，但最大值变化幅度大于最小值。且最强Ｍ值的取向位置没有改变，均位于ＲＧ取向处．

简化Bishop法的剩余下滑推力计算方法研究

简化Bishop法是评价圆弧形滑动面滑坡稳定性的“严格”方法,计算方法简便、精确,已有相关学者研究了其严格性,但却没有与之相适应的滑坡剩余下滑推力解析法,给滑坡(边坡)的综合治理带来了一定困难。本文从简化Bishop法计算原理出发,考虑坡体自重、外力、水平地震力、滑动面处的孔隙水压力等,利用力多边形法则,得到了两类简化Bishop法剩余下滑推力分析模型,即:Ⅰ型(Ti≥0)和Ⅱ型(Ti<0);针对两类模型推导出了第i-1条块的下滑推力,然后,使Fi-1参与到第i条块的力多边形受力模型中,从上往下逐条块计算下滑推力,进而推导出条块i的剩余下滑推力解析计算公式。该解析法与传递系数法隐式解所计算的剩余下滑推力进行比较,总体上呈现出简化Bishop法剩余下滑推力高于传递系数法隐式解,两者的剩余下滑推力差值随着安全储备的增大而减小,且该解析法适用于安全储备要求较高的滑坡(边坡),该解析法为圆弧形滑动面滑坡(边坡)治理设计提供了一定的理论依据。

Influences of Na_2CO_3 Stress on Physiological Metabolisms of Different Alkali Tolerant Varieties of Stevia rebaudiana

[Objective] The research aimed to reveal physiological mechanisms of alkali tolerances of different Stevia rebaudiana varieties under alkali stress.[Method] By using matrix culture method,the influences of Na2CO3 on chlorophyll content,malondialdehyde（MDA）,superoxide dismutase（SOD）,peroxidase（POD） and Proline（Pro） content of leaves from different alkali tolerance varieties of S.rebaudiana [No.2 Shoutian（relative alkali tolerance variety） and No.4 Zhongshan（alkali sensitivity variety）] were studied.[Result] 1.2 g/L of Na2CO3 stress made that the chlorophyll contents of leaves from No.2 Shoutian and No.4 Zhongshan seedlings both decreased in different degrees.Moreover,MDA content of No.4 Zhongshan was higher than control during the whole stress period,and the largest increase amplitude was 43.2%.MDA content of No.2 Shoutian was lower than control in early and latter periods of stress,and increased the maximum on the 14th day of alkali stress,which was 24.4% higher than control.SOD activities of No.2 Shoutian and No.4 Zhongshan both showed a trend of first increasing and declining then in the alkali stress period,but the increasing extent of SOD activity in No.2 Shoutian was higher than that in No.4 Zhongshan.In latter period of Na2CO3 stress,SOD activity of No.2 Shoutian declined,but POD activity was higher than that of No.4 Zhongshan.It illustrated that POD had stronger scavenging capability of active oxygen.Pro contents of No.2 Shoutian and No.4 Zhongshan were higher than control in the stress period.It showed that the osmoregulation of Pro might not be key regulatory factor of alkali tolerance difference of the two S.rebaudiana varieties.[Conclusion] The research not only provided theoretical basis for further breeding new salt tolerance variety of S.rebaudiana,but also had important significance for improving utilized ratio of kaline soil and growing environment for mudflat in China.

Isolation, Expression Characteristics and Chromosomal Locations of Three cDNA Fragments Under Salt Stress in Rice

cDNA libraries were constructed from the leaves of a rice (Oryza sativa L.) salt tolerancevariety Tesan抋i 2 growing in solutions with 150 mmol/L NaCl for 3 h or without salt stress. Three salt-responsive cDNA clones, Ts1, Ts2 and Ts3 were isolated by differential screening. Northern blottinganalysis showed that the transcription levels of Ts1 and Ts2 increased within 3 h salt stress and kept onincreasing within 24 h, while the transcription level of Ts3 reached its peak within 3 h. Sequence analysisindicated that there were no homologies between the three cDNA clones and any known gene. The threecDNA clones were mapped using a doubled haploid (DH) population derived from an indica variety ZYQ8,which was a salt tolerance parent of Tesan抋i 2, with a japonica variety JX17. Ts1, Ts2 and Ts3 werelocated on chromosomes 1, 3 and 7, respectively. It was noted that Ts1, Ts2, and Ts3 were in or near theregions of major or minor salt tolerance quantitative trait loci (QTLs), which were mapped in the same DHpopulation in a parallel study.

Pathogenesis of Parkinson’s disease: oxidative stress, environmental impact factors and inflammatory processes

Current hypothesis of neuronal degeneration in Parkinson’s disease (PD) have been proposed, including formation of free radicals and oxidative stress, mitochondrial dysfunction, excitotoxicity, trophic factor deficiency, inflam- matory processes, genetic factors, environmental impact factors, toxic action of nitric oxide, apoptosis, and so on. This review mainly discussed oxidative stress, environmental impact factors, and inflammatory processes in PD.

基于断裂力学的腐蚀钢丝疲劳S-N曲线研究

高强冷拔钢丝因其优异的力学性能被广泛应用于缆索承重结构,服役过程中钢丝腐蚀与断裂威胁着结构安全。钢丝腐蚀后表面的蚀坑因应力集中效应易产生疲劳裂纹,因此腐蚀钢丝剩余疲劳寿命主要取决于裂纹的扩展阶段,且裂纹扩展受到腐蚀程度(初始损伤)的显著影响。精确表征腐蚀程度并准确评估服役期钢丝腐蚀后的剩余寿命,仍是亟待解决的维修难题。首先采用蚀坑最大深度表征钢丝腐蚀程度,以应力强度因子幅作为裂纹扩展驱动力指标,基于断裂力学的Paris公式建立受拉钢丝裂纹扩展理论模型,进而推导腐蚀钢丝的疲劳S-N曲线。大量既有的腐蚀钢丝疲劳试验结果与理论预测值的比较验证了所提理论模型及疲劳S-N曲线的合理性和有效性。含多个蚀坑的钢丝裂纹扩展有限元模拟表明,等效单裂纹适用于多腐蚀坑钢丝疲劳寿命的简化分析。参数分析表明,蚀坑深度和腐蚀环境是腐蚀钢丝疲劳强度的关键影响因素,而应力比和疲劳加载频率影响较小,所提出的S-N曲线在钢丝常规服役条件下适用于评估其剩余寿命,可得到合理的预测结果。基于断裂力学所提的理论方法和疲劳S-N曲线可为腐蚀钢丝的疲劳强度和寿命评估提供参考。

2022年四川芦山M_(S)6.1地震前应力状态研究

为研究2022年6月1日四川芦山M_(S)6.1地震的孕育和发生过程,采用CAP方法反演了2013年芦山M_(S)7.0主震及M_(S)≥5.0余震的震源机制解,并基于应力张量方差与b值时空分布特征,探讨了芦山M_(S)6.1地震的力学机制和震源区的应力状态。结果表明:2022年芦山M_(S)6.1地震震源机制表现出与2013年芦山M_(S)7.0主震和5级余震相似的逆冲型破裂特征,压应力轴方位与龙门山断裂带南段区域应力场一致。2013年芦山M_(S)7.0地震后震中及附近的应力张量方差和b值长期处于低值状态,2022年芦山M_(S)6.1地震前震中及附近出现了应力张量方差和b值的低值异常,表明芦山余震区处于较高的应力水平。分析认为:巴颜喀拉块体持续东向运动受到华南块体的阻挡,震中所在区域长期受挤压逆冲作用,从而使芦山余震区长期处于应力积累的状态,芦山M_(S)6.1地震也是在这种动力学背景下发生的。

乌什 M_(S)7.1地震序列及应力降特征研究

研究乌什M_(S)7.1地震序列时间和空间变化以及震源参数特征,结果表明地震余震主要分布在主震北东和南西两侧,展布与迈丹断裂的走向基本吻合。目前序列b值为0.67,h值为1.3,p值为1.28。震源机制解为逆冲型,应力降处于低值水平,序列衰减基本正常。此次地震为主震—余震型,最大余震为M_(S)5.8地震。

Effects of Temperature and Pressure on Stress Corrosion Cracking Behavior of 310S Stainless Steel in Chloride Solution

310S is an austenitic stainless steel for high temperature applications, having strong resistance of oxidation, hydrogen embrittlement and corrosion. Stress corrosion cracking（SCC） is the main corrosion failure mode for 310S stainless steel. Past researched about SCC of 310S primarily focus on the corrosion mechanism and influence of temperature and corrosive media, but few studies concern the combined influence of temperature, pressure and chloride. on SCC of 310S stainless steel, prepared samples are investigated via For a better understanding of temperature and pressure＇s effects slow strain rate tensile test（SSRT） in different temperature and pressure in NACE A solution. The result shows that the SCC sensibility indexes of 310S stainless steel increase with the rise of temperature and reach maximum at 10MPa and 160~C, increasing by 22.3% compared with that at 10 MPa and 80 ℃. Instead, the sensibility decreases with the pressure up. Besides, the fractures begin to transform from the ductile fracture to the brittle fracture with the increase of temperature. 310S stainless steel has an obvious tendency of stress corrosion at 10MPa and 160℃ and the fracture surface exists cleavage steps, river patterns and some local secondary cracks, having obvious brittle fracture characteristics. The SCC cracks initiate from inclusions and tiny pits in the matrix and propagate into the matrix along the cross section gradually until rupture. In particular, the oxygen and chloride play an important role on the SCC of 310S stainless steel in NACE A solution. The chloride damages passivating film, causing pitting corrosion, concentrating in the cracks and accelerated SSC ultimately. The research reveals the combined influence of temperature, pressure and chloride on the SCC of 310S, which can be a guide to the application of 310S stainless steel in super-heater tube.

Kaempferol attenuates cognitive deficit via regulating oxidative stress and neuroinflammation in an ovariectomized rat model of sporadic dementia

Alzheimer＇s disease（AD） is associated with oxidative stress, and ultimately results in cognitive deficit. Despite existing literature on the pathophysiology of AD, there is currently no cure for AD. The present study investigated the effects of kaempferol（Kmp） isolated from the extract of Mespilus germanica L.（medlar） leaves on cognitive impairment, hippocampal antioxidants, apoptosis, lipid peroxidation and neuro-inflammation markers in ovariectomized（OVX） rat models of sporadic AD. Kaempferol, as the main flavonoid of medlar extract has been previously known for anti-oxidative, anti-inflammatory and anti-neurotoxic effects. Thirty-two female Wistar rats were ovariectomized, and randomly divided into four groups： sham, OVX ＋ saline, OVX ＋ streptozotocin（STZ） ＋ saline, OVX ＋ STZ ＋ Kmp. Animals received intracerebroventricular injection of STZ（3 mg/kg, twice with one day interval） to establish models of sporadic AD. Intraperitoneal injection of Kmp（10 mg/kg） for 21 days was performed in the OVX ＋ STZ ＋ Kmp group. Spatial learning and memory of rats were evaluated using a Morris water maze. Finally, brain homogenates were used for biochemical analysis by enzyme-linked immunosorbent assay. The results showed a significant improvement in spatial learning and memory as evidenced by shortened escape latency and searching distance in Morris water maze in the OVX ＋ STZ ＋ Kmp group compared with the OVX ＋ STZ group. Kmp also exhibited significant elevations in brain levels of antioxidant enzymes of superoxide dismutase and glutathione, while reduction in tumor necrosis factor-α and malondialdehyde. Our results demonstrate that Kmp is capable of alleviating STZ-induced memory impairment in OVX rats, probably by elevating endogenous hippocampal antioxidants of superoxide dismutase and glutathione, and reducing neuroinflammation. This study suggests that Kmp may be a potential neuroprotective agent against cognitive deficit in AD.

Oxidative stress, mitochondrial damage and neurodegenerative diseases

Oxidative stress and mitochondrial damage have been implicated in the pathogenesis of several neurodegenerative diseases, including Alzheimer’s disease, Parkinson’s disease and amyotrophic lateral sclerosis. Oxidative stress is characterized by the overproduction of reactive oxygen species, which can induce mitochondrial DNA mutations, damage the mitochondrial respiratory chain, alter membrane permeability, and influence Ca2＋ homeostasis and mitochondrial defense systems. All these changes are implicated in the development of these neurodegenerative diseases, mediating or amplifying neuronal dysfunction and triggering neurodegeneration. This paper summarizes the contribution of oxidative stress and mitochondrial damage to the onset of neurodegenerative diseases and discusses strategies to modify mitochondrial dysfunction that may be attractive therapeutic interventions for the treatment of various neurodegenerative diseases.

Design and Analysis of Tapered Stress Joint for Top Tensioned Riser System

Stress Joint （SJ） plays a key role in the Top Tensioned Riser （TTR） system for deep water engineering. A preliminary design method of tapered SJ is proposed in the paper, which could help designers obtain accurate design data. After a further sensitive analysis is carried out, the related parameters choice and control methods are recommended in the engineering practice. By taking the extreme environment conditions into consideration, the effects of bending stress reduction and curve control are analyzed, and the 3-D FE models are established by ABQOUS for numerical evaluation to verify the correctness of design results. At last, dynamic analysis and fatigue analysis, based on actual project, are carried out with designed stress joint. The analysis results prove the feasibility and guidance of this method in the practical engineering applications.

Fructus Broussonetae extract improves cognitive function and endoplasmic reticulum stress in Alzheimer's disease models

This study investigated the effects and possible targets of Fructus Broussonetiae extract, a traditional Chinese medicinal herb, on a model of Alzheimer＇s disease induced by beta-amyloid peptide 25 35 and D-galactose. The results revealed that intragastric administration of Fructus Broussonetiae significantly increased the expression of immunoglobulin-binding protein, a key factor in the endoplasmic reticulum stress-signaling pathway in rat hippocampus. In contrast, the treatment significantly decreased expression levels of PKR-like endoplasmic reticulum kinase and C/EBP homologous protein, and substantially improved learning, memory and spatial recognition dysfunction in rats. This evidence indicates that Fructus Broussonetiae extract improves spatial learning and memory abilities in rats by affecting the regulation of hippocampal endoplasmic reticulum stress and activation of the apoptosis pathway.

Grape Seed Proanthocyanidin Extract Ameliorates Streptozotocin-induced Cognitive and Synaptic Plasticity Deficits by Inhibiting Oxidative Stress and Preserving AKT and ERK Activities

Progressive memory loss and cognitive impairment are the main clinical manifestations of Alzheimer’s disease(AD).Currently,there is no effective drug available for the treatment of AD.Previous studies have demonstrated that the cognitive impairment of AD is associated with oxidative stress and the inhibition of AKT and ERK phosphorylation.Grape seed proanthocyanidin extract(GSPE)has been shown to have strong antioxidant effect and can protect the nervous system from oxidative stress damage.This study aimed to investigate the protective effect of GSPE on the cognitive and synaptic impairments of AD using a sporadic AD rat model induced by intracerebroventricular(ICV)injection of streptozotocin(STZ)(ICV-STZ).Rats were treated with GSPE(50,100,or 200 mg/kg every day)by intragastrical(ig.)administration for continuous 7 weeks,and ICV-STZ(3 mg/kg)was performed on the first day and third day of week 5.Learning and memory abilities were assessed by the Morris water maze(MWM)test at week 8.After behavioral test,hippocampal long-term potentiation(LTP)was recorded,and the levels of malondialdehyde(MDA),superoxide dismutases(SOD),glutathione(GSH)and the protein expression of AKT and ERK were measured in the hippocampus and cerebral cortex of rats.Our study revealed that ICV-STZ significantly impaired the working learning ability and hippocampal LTP of rats,significantly increased the levels of MDA,and decreased the activity of SOD and GSH in the hippocampus and cerebral cortex.In contrast,GSPE treatment prevented the impairment of cognitive function and hippocampal LTP induced by ICV-STZ,decreased the level of MDA,and increased the level of SOD and GSH.Furthermore,Western blot results showed that GSPE treatment could prevent the loss of AKT and ERK activities in the hippocampus and cerebral cortex induced by ICV-STZ.Our findings demonstrate that GSPE treatment could ameliorate the impairment of cognitive ability and hippocampal synaptic plasticity in a rat model of sporadic AD by inhibiting oxidative stress and preserving AKT and ERK activities.Therefore,GSPE may be an effective agent for the treatment of cognitive deficits associated with sporadic AD.

Process Analysis of In-situ Strain during the M_s8.0 Wenchuan Earthquake—Data from the Stress Monitoring Station at Shandan

There were huge life and property losses during the Ms8.0 Wenchuan earthquake on May 12, 2008. Strain fluctuation curves were completely recorded at stress observatory stations in the Qinghai-Tibet plateau and its surroundings in the process of the earthquake. This paper introduces the geological background of the Wenchuan earthquake and the profile of in-situ stress monitoring stations. In particular, data of 174 earthquakes （Ms4.0-Ms8.5） were processed and analyzed with various methods, which were recorded at the Shandan station from August 2007 to December 2008. The results were compared with other seismic data, and further analyses were done for the recoded strain seismic waves, co-seismic strain stepovers, pre-earthquake strain valleys, Earth＇s free oscillations before and after the earthquake and their physical implications. During the Wenchuan earthquake, the strainmeter recorded a huge extensional strain of 70 seconds, which shows that the Wenchuan earthquake is a rupture process predominated by thrusting. Significant precursory strain anomalies were detected 48 hours, 30 hours, 8 hours and 37 minutes before the earthquake. The anomalies are very high and their forms are very similar to that of the main shock. Similar anomalies can also be found in strain curves of other shocks greater than Ms7.0, indicating that such anomalies are prevalent before a great earthquake. In this paper, it is shown that medium aftershocks （Ms5.5- 6.0） can also cause Earth＇s free oscillations. Study of free oscillations is of great significance to understand the internal structure of the Earth and focal mechanisms of earthquakes and to recognize slow shocks, thus providing a scientific basis for the prevention and treatment of geological disasters and the prediction of future earthquakes.

Effects of bottom shear stresses on the wave-induced dynamic response in a porous seabed:PORO-WSSI (shear) model

When ocean waves propagate over the sea floor,dynamic wave pressures and bottom shear stresses exert on the surface of seabed.The bottom shear stresses provide a horizontal loading in the wave-seabed interaction system,while dynamic wave pressures provide a vertical loading in the system.However,the bottom shear stresses have been ignored in most previous studies in the past.In this study,the effects of the bottom shear stresses on the dynamic response in a seabed of finite thickness under wave loading will be examined,based on Biot＇s dynamic poro-elastic theory.In the model,an ＂u-p＂ approximation will be adopted instead of quasi-static model that have been used in most previous studies.Numerical results indicate that the bottom shear stresses has certain influences on the wave-induced seabed dynamic response.Furthermore,wave and soil characteristics have considerable influences on the relative difference of seabed response between the previous model（without shear stresses） and the present model（with shear stresses）.As shown in the parametric study,the relative differences between two models could up to 10% of p0,depending on the amplitude of bottom shear stresses.