壳寡糖诱导转反义mapk基因烟草的TMV抗性和PAL活性研究

壳寡糖具有诱导植物对病原物防御反应的作用,而PAL活性的升高通常被认为是发生抗性反应的标志之一.本文以mapk基因受到反义抑制的转基因枯斑三生烟草为试材,比较了壳寡糖诱导后转基因型和野生型烟草的PAL活性变化及对TMV抗性的变化.由实验结果初步推测,在壳寡糖诱导的植物抗性信号通路中,mapk可能为PAL的一个重要的上游基因,同时mapk在烟草抗TMV信号转导中亦为一个重要组分.图4表2参13     

Why do plants ‘talk’?

Summary Plant defence can be induced by herbivory. This is true for both direct and indirect plant defence. Induced direct defence has been the most studied of the two. However, in most cases induced direct defence does not appear to be a water-tight defence option. In contrast, induced indirect defence through the production of herbivore-induced carnivore attractants can be a decisive factor in the extermination of herbivore populations. In this paper the main characteristics of induced attraction of carnivores by plants are reviewed. This includes the similarities and dissimilarities among tritrophic systems. There are two main patterns of induced carnivore attraction. (1) Through the emission of the same bouquet as that emitted by mechanically damaged plants, but in larger quantities and for a longer period of time after damage. (2) Through emission of large amounts of new volatiles that are synthesizedde novo in response to herbivore feeding andnot in response to mechanical wounding.Herbivore populations may be decimated by carnivores. Therefore it should be realized that herbivoreinduced carnivore attractants are essential in an important step in carnivore foraging,i.e. long-distance herbivore location. Once herbivores have started feeding on a plant and direct defence is not effective, induced indirect defence may be decisive for plant survival. Therefore, it is concluded that indirect defence is an essential aspect of induced plant defence directed at herbivorous arthropods.     

大气飘尘中苯并[a]芘的激光诱导荧光法测定

以激光诱导荧光法测定大气飘尘中的苯并[a]芘。方法的检测限为0.01μg·l~(-1),降低了常规荧光法的检测限。综合溶剂提取、柱色层及纸色层分离技术,测定了上海市某些地区大气飘尘样品中苯并[a]芘的含量。     

Town-scale microbial sewer community and H2S emissions response to common chemical and biological dosing treatments

Controlling hydrogen sulfide (H₂S) odors and emissions using a single, effective treatment across a town-scale sewer network is a challenge faced by many water utilities. Implementation of a sewer diversion provided the opportunity to compare the effectiveness of magnesium hydroxide (Mg(OH)₂) and two biological dosing compounds (Bioproducts A and B), with different modes of action (MOA), in a field-test across a large sewer network. Mg(OH)₂ increases sewer pH allowing suppression of H₂S release into the sewer environment while Bioproduct A acts to disrupt microbial communication through quorum sensing (QS), reducing biofilm integrity. Bioproduct B reduces H₂S odors by scouring the sewer of fats, oils and grease (FOGs), which provide adhesion points for the microbial biofilm. Results revealed that only Mg(OH)₂ altered the microbial community structure and reduced H₂S emissions in a live sewer system, whilst Bioproducts A and B did not reduce H₂S emissions or have an observable effect on the composition of the microbial community at the dosed site. Study results recommend in situ testing of dosing treatments before implementation across an operational system.     

模拟高低空交变环境下30CrMnSiNi2A钢力学性能研究

目的研究30CrMnSiNi2A钢制腔体的力学性能影响及演化规律。方法借助高低温低气压试验和中性盐雾试验交替进行,模拟高低空交替变化的腐蚀环境。通过比较静力拉伸试验和疲劳试验的结果,进一步揭示预腐蚀对静力拉伸性能和疲劳性能的影响。结果经过预腐蚀处理,30CrMnSiNi2A钢制腔体的力学抗拉强度下降了0.73%,规定塑延伸强度上升了0.04%,断后伸长率下降了0.95%。疲劳寿命数据与对数疲劳寿命数据均符合正态分布,未发生明显变化。结论高低空交变环境下,腔体内部会发生一定程度的腐蚀,但由于腐蚀程度较小,对30CrMnSiNi2A钢力学性能影响不大。     

钢板弹簧断裂失效行为研究

目的研究汽车钢板弹簧断裂失效的原因。方法通过化学成分分析、硬度测试、断口形貌分析、金相组织分析等手段研究汽车钢板弹簧的失效行为。结果由于表面脱碳层过深,使得表面疲劳强度及耐蚀性降低,同时因长时间腐蚀作用在表面产生腐蚀坑及腐蚀裂纹,并且在循环外力作用下,腐蚀缺陷处产生应力集中,早期裂纹萌生于表面腐蚀缺陷处并扩展,最终导致腐蚀疲劳断裂。结论通过控制热处理条件、增加加工余量并去除脱碳层、表面喷丸处理等措施,钢板弹簧表面耐蚀及抗疲劳性能大幅提高,可有效避免脱碳引起的腐蚀疲劳断裂。     

某型飞机起落架舱上蒙皮振动测量与分析

目的研究起落架舱上蒙皮裂纹原因。方法通过建立起落架舱有限元模型,进行固有频率特性计算,同时空测故障区域蒙皮的振动加速度以及动应力,对起落架舱蒙皮的振动情况进行分析。结果起落架舱三角区故障区域振动量级大于非故障区域,起落架舱三角区振动功率谱密度最大值的频率区间在200~500 Hz的中频频段,起落架舱三角区结构振动的幅值与飞机的法向过载Ny密切相关,静载大概是动载的100倍。结论飞机机动过载产生的静载远大于振动产生的动载,起落架舱三角区故障区域以静载为主,是造成裂纹的主要原因。     

基于支持向量机的管制疲劳检测模型研究

管制疲劳是影响民航安全的重大隐患,准确检测疲劳状态是进行疲劳预警、降低疲劳风险的关键。提出应用支持向量机模型融合多生理参数和眼动指标进行管制疲劳检测,通过MP150多导生理记录仪与眼动仪,采集模拟管制试验中正常与剥夺睡眠状态下被试的试验数据,同时记录其Karolinska疲劳等级和操作绩效。结果表明,RR间期、LF/HF、快慢波比值、PERCLOS和扫视速度均与管制疲劳呈较强相关,利用支持向量机融合五项指标构建管制疲劳检测模型,对于五级疲劳度的识别准确率为78. 1%,判断正常组与剥夺睡眠组的准确率为94. 2%。     

A pre/post evaluation of fatigue,stress and vigilance amongst commercially licensed truck drivers performing a prolonged driving task

Purpose. The main purpose of this research study was to evaluate changes in fatigue, stress and vigilance amongst commercially licensed truck drivers involved in a prolonged driving task. The secondary purpose was to determine whether a new ergonomic seat could help reduce both physical and cognitive fatigue during a prolonged driving task. Two different truck seats were evaluated: an industrial standard seat and a new truck seat prototype. Methods. Twenty male truck drivers were recruited to attend two testing sessions, on two separate days, with each session randomized for seat design. During each session, participants performed two 10-min simulated driving tasks. Between simulated sessions, participants drove a long-haul truck for 90 min. Fatigue and stress were quantified using a series of questionnaires whereas vigilance was measured using a standardized computer test. Results. Seat interactions had a significant effect on fatigue patterns. Conclusion. The new ergonomic seat design holds potential in improving road safety and vehicle accidents due to fatigue-related accidents.     

高温环境下薄壁结构声疲劳失效验证技术研究

目的针对高温环境下薄壁结构声疲劳失效问题,研究分析薄壁结构在高温环境下的声疲劳失效特征,验证薄壁结构热声响应计算方法与疲劳寿命预估模型的有效性。方法较系统地阐述高温环境下薄壁结构声疲劳失效试验验证技术,重点总结热声疲劳试验环境建立与加载、高温环境下噪声测试、高温环境下动态响应测试和疲劳破坏寿命测试方法,并通过具体案例说明工程中试验验证方法的有效性。结果试验件在仿真计算与试验中的破坏位置一致,响应频率吻合较好,应力水平一致,疲劳寿命量级相当。结论薄壁结构热声响应计算方法与疲劳寿命预估模型的有效性高。