Harmonic Analysis and Suppression of High-frequency Welding Devices

This paper analyzes the structure and line current waveform of 3-phase AC voltage regulation circuit. As an application of 3-phase AC voltage regulation circuit, a high-frequency welding device's simulation model and harmonic analysis of line current are presented. Results of simulation are compared to field measurements. The two are in a good agreement, so this simulation model is correct. Two single-tuning filters and one second-order HPF are designed according to the device's harmonic condition. Simulation results of the circuit with filters indicate decrease of the harmonics in current of power supply, and the waveform is close to sinusoidal wave, which prove correctness of the solution to harmonics pollution.     

生物柴油作为汽车新能源的特点

近年来,随着人们对有限石油资源的认识,意识到应减少对其作为主要能源的依赖,在全球范围内加快了对可再生能源的研究。生物柴油是很具潜力的汽车可再生替代燃料。它是一种可再生、环保的替代能源,它可以在未做任何改动的柴油机上燃用。本文通过对生物柴油作为汽车燃料特点的分析,指出生物柴油作为一种新型燃料,是目前柴油的较好替代品．认为生物柴油作为汽车新能源具有很好的实用意义和很大的发展潜力。     

Cadmium Enhances Generation of Hydrogen Peroxide and Amplifies Activities of Catalase, Peroxidases and Superoxide Dismutase in Maize

Maize (Zea mays L. cv. 777) plants grown in hydroponic culture were treated with 50 μm CdSO₄. Growth and metabolic parameters indicative of oxidative stress and antioxidant responses were studied in leaves of plants treated with Cd. Apart from increasing lipid peroxidation and H₂O₂ accumulation, supply of Cd suppressed growth, fresh and dry mass of plants and decreased the concentrations of chloroplastic pigments. The activities of catalase (CAT; EC 1.11.1.6), peroxidase (POD; EC 1.11.1.7), ascorbate peroxidase (APX; EC 1.11.1.11) and superoxide dismutase (SOD; EC 1.15.1.1) were increased in plants supplied 50 μm Cd. Localization of activities of isoforms of these enzymes (POD, APX and SOD) on native gels also revealed increase in the intensities of pre‐existing bands. Stimulated activities of CAT, POD, APX and SOD in maize plants supplied excess Cd do not appear to have relieved plants from excessive generation of reactive oxygen species (ROS). It is, therefore, concluded that supply of 50 μm Cd induces oxidative stress by increasing production of ROS despite increased antioxidant protection in maize plants.     

桦褐孔菌提取物降血脂研究

采用高脂高胆固醇诱导SD大鼠高脂血症实验模型,分析桦褐孔菌醇提物（IOE）对大鼠体重、脏器及饲喂IOE后大鼠血脂水平和动脉硬化指数。结果表明：IOE可以显著降低高脂血症大鼠血清中甘油三酯、总胆固醇的含量;IOE可以显著提高高脂血症大鼠血清中的高密度脂蛋白胆固醇的水平,降低低密度脂蛋白胆固醇的水平;IOE可以提高高脂血症大鼠的ApoA水平,降低ApoB水平;饲喂IOE后,可明显改善大鼠血脂代谢,对阻止动脉硬化的形成和恶化具有重要作用。     

丁酸梭菌对肉鸡腿肌脂肪代谢的影响

本试验旨在研究丁酸梭菌对肉鸡腿肌脂肪代谢的影响。试验选用1日龄爱拔益加肉公鸡192只,随机分为2个组,每个组6个重复,每个重复16只鸡。对照组饲喂基础饲粮,试验组饲喂在基础饲粮中添加1×10~9CFU/kg丁酸梭菌的饲粮,试验期为42 d。结果表明,与对照组相比:1)饲粮中添加丁酸梭菌显著增加了21日龄肉鸡腿肌肌内脂肪含量(P0.05),但对42日龄肉鸡腿肌肌内脂肪含量无显著影响(P0.05)。2)饲粮中添加丁酸梭菌显著降低了21日龄肉鸡腿肌激素敏感脂肪酶活性(P0.05),显著提高了21日龄肉鸡腿肌脂蛋白脂酶活性(P0.05),且有增加42日龄肉鸡腿肌脂蛋白脂酶活性的趋势(0.05P0.10)。3)饲粮中添加丁酸梭菌显著降低了21日龄肉鸡血清中游离三碘甲状腺原氨酸含量(P0.05)。4)饲粮中添加丁酸梭菌显著降低了21日龄肉鸡腿肌脂肪甘油三酯脂肪酶mRNA表达量(P0.05)。由此可见,饲粮中添加丁酸梭菌可通过改变21日龄肉鸡腿肌脂肪代谢相关酶活性和基因表达来增加肉鸡腿肌肌内脂肪含量。     

板栗脂质转运蛋白基因的克隆及表达

利用RACE技术从板栗短雄花序突变体中扩增得到660bp的板栗脂质转运蛋白(lipid transfer protein,LTP)cDNA片段。该cDNA编码118个氨基酸,具有8个位置保守的半胱氨酸(C)残基及26个氨基酸的信号肽,它与棉花、草莓脂质转运蛋白氨基酸序列相似性为63%,基因序列已提交数据库(GenBank),其登录号分别为FJ490676(基因)和ACL01093(蛋白)。荧光定量分析表明板栗短雄花序突变体较正常雄花序的脂质转运蛋白表达量更高。将板栗脂质转运蛋白基因插入到硫氧还蛋白融合表达载体pET32a(+)中,构建了板栗的原核表达载体pET-LTP,在大肠杆菌菌株Rosetta-gamiTM2(DE3)中,IPTG诱导5h大量表达约为30ku的融合蛋白,通过Ni2+-chelating sepharose fast flow柱纯化的融合蛋白具有抑制板栗镰刀菌属病原真菌孢子萌发的功能。     

Response of Rice Seedlings to Copper Toxicity and Acidity

Metal toxicity and soil acidity affect plant growth. A hydroponic experiment was conducted to simulate effects of pH and copper concentration [Cu] on early growth and biomass production of high-yielding rice seedlings (Oryza sativa L. cv. ‘NIAB 6’). The rice seedlings were allowed to grow in Yoshida nutrient solution with 1 (control), 8, 16, and 32 μM Cu at buffered pH levels of 4.5, 5.0, and 5.5, respectively. Shoot and root growth, leaf chlorophyll content, and root lipid peroxidation and K⁺ leakage of 15-day-old rice seedlings were determined. Results show that [Cu] had significant adverse effects on rice seedlings. Shoot height and root length were reduced by 18%–60% and 7%–69%, respectively, compared with the control, and shoot and root weight decreased by 26%–56%, and 25%, respectively, in response to progressive increases in [Cu]. Similarly, leaf chlorophyll content decreased by 150%–245% compared with the control treatment. Rice seedling roots suffered from significant increases in lipid peroxidation followed by K⁺ leakage (> 8–23 times) in response to increasing [Cu]. Averaged across [Cu], seedling growth and biomass were greater at pH 5.5 than at other pH treatments. In some instances, increasing pH minimized the adverse effects of Cu at low concentrations on rice seedlings.     

Repeated annual drought has minor long‐term influence on δ13C and alkane composition of plant and soil in model grassland and heathland ecosystems

As a result of global climate change the incidence of drought conditions in Europe is predicted to increase in the future, which also influences plant resistance. Lipids are important plant constituents that protect plants against drought stress and contribute to the intermediate stable carbon (C) pool in soil. However, the extent to which drought influences lipid cycling in the plant–soil system is unknown and, therefore, it remains questionable how the ecosystem recovers after drought. We focused on plant and soil samples from two different plant communities (temperate grassland and heathland) that had been exposed to 5 years of 4.5–6.0 weeks repeated annual drought. They were sampled one year after the last drought to check the recovery of the plant–soil system. Samples were analyzed for their bulk C, stable C and nitrogen (N) isotope (δ¹³C, δ¹⁵N) and lipid composition. Contrary to our expectation, no strong influence of five years of repeated annual drought was observed for above‐ground biomass, roots and soils in the model ecosystems with respect to elemental (C and N concentrations, C : N ratio) bulk isotope (δ¹³C, δ¹⁵N) composition and the total extractable lipid concentration. Thus, plants did not sustain a significant change in their C and lipid concentration as well as their composition after five years of repeated annual drought. This might be related to the comparatively short drought period related to the overall growth season and provides evidence for recovery of the C and lipid dynamics in temperate grassland and heathland model ecosystems exposed to annual drought.     

穿心莲全长转录组测序及特性分析

为从转录水平上解析穿心莲体内主要进行的生物进程及其分子机制,选取生长60天的福建漳州生产用穿心莲苗为材料,利用超长单分子测序技术测得其根、茎和倒三叶的全长转录组初始序列信息.对初始序列进行筛选、去冗余、校正、功能注释和基因结构分析.结果 显示,穿心莲基因的功能主要富集于代谢途径、次生代谢产物合成途径及抗生素合成途径.b...     

瘦素与肥胖并发症关系的研究进展

目的研究瘦素 (LEP) 对猪原代脂肪细胞脂滴相关基因FITM2、PLIN1和PLIN2 mRNA表达的影响。方法采用不同质量浓度的LEP (0、50、100和150 ng/mL) 处理15日龄三元杂交猪 (DLY) 皮下原代脂肪细胞48 h,试剂盒测定细胞中甘油三酯 (TAG)含量,qPCR检测脂滴相关基因mRNA表达水平。结果与0 ng/mL LEP相比,100 ng/mL LEP可显著增加猪原代脂肪细胞TAG含量以及FITM2和PLIN2 mRNA表达水平 (P<0.05),显著下调PLIN1 mRNA表达水平 (P<0.05);与50和100 ng/mL LEP相比,150 ng/mL LEP可显著降低脂肪细胞TAG含量 (P<0.05),显著上调PLIN1和PLIN2 mRNA表达水平 (P<0.05)。结论LEP可促进猪原代脂肪细胞FITM2和PLIN2 mRNA表达,可促进或抑制PLIN1 mRNA表达,但LEP对脂滴相关基因表达的促进或抑制存在质量浓度差异性。