Distribution and accumulation of Cy5.5-labeled thermally cross-linked superparamagnetic iron oxide nanoparticles in the tissues of ICR mice

Free Cy5.5 dye and Cy5.5-labeled thermally cross-linked superparamagnetic iron oxide nanoparticles (TCL-SPION) have been routinely used for in vivo optical imaging. However, there is little information about the distribution and accumulation of free Cy5.5 dye and Cy5.5-labeled TCL-SPION in the tissues of mice. Free Cy5.5 dye (0.1 mg/kg body weight) and Cy5.5-labeled TCL-SPION (15 mg/kg body weight) were intravenously injected into the tail vein of ICR mice. The biodistribution and accumulation of the TCL-SPION and Cy5.5 were observed by ex vivo optical imaging and fluorescence signal generation at various time points over 28 days. Cy5.5 dye fluorescence in various organs was rapidly eliminated from 0.5 to 24 h post-injection. Fluorescence intensity of Cy5.5 dye in the liver, lung, kidney, and stomach was fairly strong at the early time points within 1 day post-injection. Cy5.5-labeled TCL-SPION had the highest fluorescence density in the lung at 0.5 h post-injection and decreased rapidly over time. Fluorescence density in liver and spleen was maintained over 28 days. These results suggest that TCL-SPION can be useful as a carrier of therapeutic reagents to treat diseases by persisting for long periods of time in the body.     

Intake and ruminal digestion determined using omasal and reticular digesta samples in cattle fed diets containing sugar cane in natura or ensiled sugar cane compared with maize silage

Sugar cane is widely used in an in natura forage in tropical countries, but the adoption of silage methods facilitates the preservation of its nutritional value and improves the logistics of its use. To explain differences in performance using alternative forages, it is important to conduct studies that evaluate the various digestion sites for the nutrients provided in diets. However, considering that the collection of omasal digesta is quite laborious and requires the use of a vacuum pump, reticular sampling has been suggested as a promising alternative. Thus, the objective of this study was to evaluate the intake and ruminal digestibility obtained from samples of digesta collected in the reticulum and omasum of cattle fed different diets. Five rumen-fistulated crossbred cattle with an average initial live weight of 336±16.6 kg were used, being distributed in a 5×5 Latin square design. Five diets were evaluated, which contained 60% forage and 40% concentrate on dry matter basis using different forages: maize silage (CS); sugar cane in natura (SCIN); sugar cane silage (SCS0%); sugar cane silage treated with 0.4% calcium oxide (SCS0.4%) or 0.8% calcium oxide (SCS0.8%) on wet basis. The percentage of crude protein (CP) in all of the forages was corrected to 11% based on dry matter (DM) using a mixture of urea/ammonium sulfate (9:1). Six collections of reticular and omasal digesta were obtained over three days at 12 h intervals. To calculate the flow of reticular and omasal nutrients, a double marker system was employed, using cobalt–EDTA and indigestible neutral detergent fiber (NDFi) as markers. The reticular and omasal digesta were similar (P>0.05) to estimate ruminal digestibility of DM, organic matter (OM), CP, neutral detergent fiber (NDF) and non-fiber carbohydrates (NFC). However, the ruminal digestibility of ether extract (EE) and the intestinal digestibility of CP and EE differed (P<0.05) between sampling sites. The results indicate that the omasal digesta is more suitable than the reticular digesta for measuring the ruminal digestion of diet components.     

第四纪红土发育土壤的氧化铁磁性矿物学研究(英文)

应用矿物磁测技术对发育于第四纪红土母质上土壤的磁化率（χ）,频率依变磁化率（χｆｄ）,饱和等温剩磁（ＳＩＲＭ）和矫顽力（ＢＣＫ）进行了研究．结果表明,土壤χ和ＳＩＲＭ的变幅分别为７×１０－８～４７５×１０－８ｍ３ｋｇ－１和８．６×１０－４～３３２．７×１０－４Ａｍ２ｋｇ－１,两者粗略地表明了土壤中亚铁磁性矿物的数量差异．土壤的χｆｄ在４．９％～２３．３％,χｆｄ以及χ和ＳＩＲＭ的粒径分布证明,土壤中的亚铁磁性矿物以次生的超顺磁性颗粒态存在．土壤的磁化和退磁参数则表明具有较高χ的土壤其磁性由亚铁磁性矿物决定,低χ的土壤则是不完整反铁磁性氧化铁的贡献．本研究表明,矿物磁测技术为研究土壤氧化铁的数量、起源和类型提供了一种简便、快速、非破坏性的方法．     

聚苯胺-氧化石墨烯复合材料的制备及其对染料的吸附性能

[目的]研究复合材料对染料的吸附性能。[方法]以改进Hummer法制备氧化石墨烯,通过动态界面聚合工艺制备聚苯胺-氧化石墨烯复合材料,并对模拟环境中不同污染性染料进行吸附性能研究。[结果]聚苯胺-氧化石墨烯能显著提高染料的吸附容量和吸附效率,当聚苯胺-氧化石墨烯的用量为1.2 g/L,溶液pH为4,吸附时间为50 min时,对铬黑T的吸附率可达94.04%。相同条件下,复合后的材料吸附性能提高了15%。3种不同染料中,对甲基橙的吸附效果最好。[结论]聚苯胺-氧化石墨烯可用作污水中染料的吸附剂。     

湖南省几种主要类型土壤反射光谱的剖面变化特性

通过野外采样和室内测定,研究了湖南省主要类型土壤反射光谱的剖面变化特性。结果表明,同一土壤剖面中不同土层的反射光谱曲线形态基本上是一致的;经统计分析得出,在每个自然土壤剖面中,各土层420nm处的的光谱反射率均与土壤游离氧化铁含量之间存在着线性负相关性,620-660nm波段的平均光谱反射率与土壤有机质含量呈幂函数负相关性。     

NO 介导的 Ca2＋信号在干旱胁迫下紫花苜蓿种子萌发及抗氧化酶中的传导作用研究

本试验以紫花苜蓿种子为试验材料,添加外源一氧化氮供体硝普钠(SNP)、CaCl_2及抑制剂亚甲基蓝(methylene blue,MB)和LaCl_3,对种子进行浸种处理,以研究NO介导的Ca~(2+)信号在干旱胁迫下紫花苜蓿种子萌发及抗氧化酶中的传导作用。结果表明,15%PEG胁迫下紫花苜蓿种子萌发受到明显抑制,当外源添加NO或Ca~(2+)处理后萌发指标均有上升,外施0.1mmol/L SNP或10mmol/L CaCl_2都能有效缓解PEG对紫花苜蓿种子的胁迫伤害。干旱胁迫下NO+Ca~(2+)共处理时效果最为显著,萌发率较SNP处理提高了8.96%,较CaCl_2处理提高了19.67%。共处理时比SNP、CaCl_2处理时提高了种子淀粉酶活性、淀粉含量、可溶性糖、可溶性蛋白及脯氨酸含量,降低了MDA含量和超氧阴离子产生速率,显著提高了SOD,POD,CAT活性。其中淀粉酶活性、淀粉含量、可溶性蛋白、可溶性糖、脯氨酸含量以及POD活性的变化中,均表现出:NO和Ca~(2+)共处理下各指标变化要慢于单一处理。当添加外源NO的同时添加Ca~(2+)通道抑制剂La~(3+),NO的促进效果受到抑制,而添加外源Ca~(2+)的同时添加NO抑制剂亚甲基蓝,Ca~(2+)的促进效果受到抑制,表明NO经由Ca~(2+)信号通路调控干旱胁迫下紫花苜蓿的信号传导。     

0.1%氧化苦参碱水剂防治菜青虫田间药效试验

由田间试验结果得知:0.1%氧化苦参碱水剂对菜青虫防效高, 防治持效期长.0.1%氧化苦参碱水剂80～200mL/hm2剂量施药3天后防效达94.36%～99.27%,施药7天后其防效仍达99.08%以上,与其他药剂相比效果明显,适宜施药剂量为150mL/hm2.施药后安全性调查表明,该药剂对作物无毒害,适合无公害蔬菜生产.     

夏玉米农田N2O排放影响因素的模拟分析

【目的】全球46%~52%的N2O来自农田土壤,农田土壤N2O排放的研究具有重要的环境和经济意义。量化各影响因素对夏玉米农田N2O排放的影响,可为合理减少施肥产生的N2O排放提供依据。【方法】于2012和2013年连续两年进行了夏玉米裂区田间试验。试验主区为作物处理,副区为氮肥处理(0、 150、 300、 450 kg/hm2)。采用暗箱静态法-气相色谱法测定了不同处理N2O的排放通量,比较了不同温度和降雨量条件下不同处理的N2O排放量,计算了气温、 降雨量、 氮肥管理和夏玉米吸收对夏玉米农田N2O排放的影响。【结果】温度及降雨量的变化明显影响N2O的排放。2012年和2013年气温和降雨量对夏玉米生长期间N2O总排放量的影响分别为-0.24和-0.07。随着施氮量的增加,施氮对N2O排放的影响率呈线性增加(R2 = 0.923),施氮量0、 150、 300和450 kg/hm2,对玉米田N2O排放的影响分别为0、 0.38、 1.63、 3.54。夏玉米生长吸收对N2O排放量的平均影响因子为-0.33,年际间差异不显著(P = 0.07)。在苗期、 穗期、 花粒期,夏玉米生长吸收的影响因子分别为-0.57、 -0.29和-0.13,不同生育期的影响因子差异显著(P = 0.0015)。不同施氮量下,气候条件对夏玉米农田N2O排放影响率差异不显著(P 0.05); 不同气温和降雨量,夏玉米生长吸收对N2O排放的影响在同一施氮量下差异不显著(P 0.05),且均随施氮量的增加而减小。【结论】通过量化分析,气候条件对N2O排放的影响与气温和降雨量密切相关,温度升高影响增大,反之则减小,降雨后排放显著增大。施氮对N2O排放的影响随施氮量增加线性增加。夏玉米生长吸收降低了N2O排放,且在不同生育时期的影响差异显著。综合各影响因子,低氮量条件下(≦150 kg/hm2),气候因素和玉米生长对N2O排放的影响较大,高氮量下(≧300 kg/hm2),氮肥的施用是影响N2O排放的主要因子。     

高温胁迫下一氧化氮和脱落酸的信号功能研究

[目的]研究高温胁迫下ABA和NO的信号功能及相互作用关系。[方法]以2种不同耐热性的芦苇愈伤组织为材料,用不同浓度ABA、SNP、fluridone、L-NNA、cPTIO预处理24 h后,将材料置于45℃高温胁迫2 h,研究2种芦苇的相对生长量、相对电导率、丙二醛含量以及NOS活性、内源ABA、NO含量的变化。[结果]外源ABA和NO处理可以明显地降低高温胁迫在2种芦苇中所引起的相对电导率和MDA含量的增加,显著地缓解氧化损伤,减轻生长受抑的程度。Fluridone、L-NNA和cPTIO处理对沼泽芦苇没有明显影响,但是可以明显促进沙丘芦苇的相对电导率和MDA含量的增加。高温胁迫可以诱导沙丘芦苇愈伤组织ABA和NO含量的显著增加,NOS活性也显著升高,但对沼泽芦苇没有明显影响。在沙丘芦苇中,外源ABA处理能够提高NOS活性,促进NO的释放;Fluridone处理则抑制高温胁迫下NOS活性的升高,并抑制NO释放量的增加,而SNP以及NO的清除剂cPTIO和NOS抑制剂L-NNA对ABA含量均无明显影响。[结论]ABA在高温胁迫下的抗性作用可能是通过NO实现的。     

Effects of trampling of a wet dairy pasture soil on soil porosity and on mitigation of nitrous oxide emissions by a nitrification inhibitor,dicyandiamide

Urine patches in dairy pastures are major sources of nitrous oxide (N₂O). Wet winters result in compaction damage to pastures because of animal trampling. The nitrification inhibitor, dicyandiamide (DCD), is effective at reducing N₂O emissions from urine patches. Here, we assessed the extent of damage to the physical quality of the soil by trampling and whether this influenced the ability of DCD to mitigate N₂O emissions. A field experiment was conducted where a sandy loam soil was trampled by a mechanical hoof just before urine and DCD application. Trampling reduced air permeability and pore continuity, but this had no effect on bulk density. Urine appeared to have contributed to pore collapse and blockage. Trampling increased average cumulative N₂O emissions from 1.74 to 4.66% of urine‐N applied. This effect was attributed to increased water‐filled pore space, aggregate destruction and suppression of grass growth. DCD was highly effective in reducing N₂O emissions, with the N₂O emission factor of the urine‐N being decreased by 58–63%. Trampling did not significantly affect the effectiveness of DCD in reducing N₂O emissions.