烤烟香气质与化学成分的相关和通径分析

对河南、湖南、津巴布韦和巴西不同产地的烤烟烟叶中的主要化学成分与香气质进行了相关和通径分析研究。结果表明：对香气质正面影响较大的因素有还原糖含量、氯离子含量和钾氯比;而负面影响的因素有糖碱比和烟碱含量,适当提高还原糖、氯离子含量和钾氯比及降低糖碱比和烟碱含量,有助于香气质的提高。     

Impervious surface thresholds for urban tree site selection

Impervious surfaces are a ubiquitous urban feature that increase temperature and tree drought stress and are a demonstrated indicator of Acer rubrum L. tree condition and insect pest abundance. We examined the relationship between A. rubrum condition, impervious surface cover, and Melanaspis tenebricosa (Comstock) abundance, a primary herbivore of urban A. rubrum, in eight cities across the southern distribution of A. rubrum. We predicted that the effects of warming, due to impervious surface, would be greater in warmer southern cities than in cooler northern cities. We found that impervious surface was a robust predictor of tree condition, but this effect was not significantly affected by background temperature. Melanaspis tenebricosa abundance was a function of impervious surface and background temperature, with greatest abundances occurring at mid latitudes. Based on these relationships, we developed impervious surface thresholds to inform site selection for A. rubrum throughout the southeastern USA. Planting criteria based on habitat characteristics should maximize urban tree longevity and services provided.     

湖北地区马铃薯播种机主要部件设计

根据湖北地区的种植农艺要求,对马铃著起垄播种机开沟器、排肥器、播种装置、开沟起垄装置等主要部件进行了参数选择和结构设计,对关键零部件进行了3D软件绘图设计工作.为样机制作提供了理论基础,以保证样机能顺利完成开沟、施肥、播种、覆土和镇压等工序.     

多糖水解酶处理烟叶的香气成分鉴定

以α-淀粉酶、纤维素酶和果胶酶组成的多糖水解酶处理烟叶,运用蒸馏萃取法提取烟叶中的香气成分,并结合气相色谱-质谱法(GC-MS)对香气成分进行了定性定量分析.结果表明,多糖水解酶处理的烟叶中水溶性糖含量提高4.29％;烟叶中的香气物质总量提高11.8％;整体口感得到改善,香气的质和量均得到提高,烟气细腻柔和,刺激性、杂气和余味残留有所降低.     

高效液相色谱法测定烟草中烟碱含量

[目的]建立一种高效液相色谱法测定烟草中烟碱的含量。[方法]色谱柱KromasiL C18(250.0 mm×4.6 mm,5.0μm),流动相为甲醇:0.02 mol/L磷酸氢二钠缓冲溶液(用磷酸调节pH 6.0)=70∶30;检测波长259 nm;流速1.0 mL/min;进样量20μL;柱温30℃。[结果]溶液浓度在27.568～165.408 mg/L时峰面积与烟碱浓度呈良好的线性关系,相关系数r为0.999 0,方法的检测限(s/n=3)为0.011 mg/L,平均回收率为97.9%,相对标准偏差(RSD)为1.1%(n=5)。[结论]该方法简便易行,结果准确,可作为烟草中烟碱含量的检测方法。     

卷烟主流烟气pH值的测定研究

［目的］研究卷烟主流烟气pH值测定的影响因素，建立卷烟主流烟气pH值的测定方法，为判断卷烟感官品质提供理论支撑。［方法］按照标准条件在吸烟机上抽吸20支卷烟并用剑桥滤片收集粒相物，转移至150 ml锥形瓶中用萃取剂萃取，并利用pH电位滴定仪测定其pH值。试验考查了不同萃取剂、萃取剂体积、萃取方式、萃取时间等因素对卷烟烟气pH值测定结果的影响。［结果］ 最终确定了以90 ml蒸馏水∶异丙醇=1∶1为萃取剂，振荡萃取30 min。利用该方法对10个国内外主导卷烟牌号样品的主流烟气的pH值进行了测定，结果表明：烤烟型卷烟主流烟气的pH值在6.008-6.212，而混合型卷烟主流烟气的pH值在6.246-6.585。［结论］ 该方法相对标准偏差为小于1％，操作简单、方便，适用于测定卷烟主流烟气pH值，结果令人满意。     

烟草N-TSNAs及其前体物在烟叶烘烤过程中含量的变化

研究表明,烟叶在烘烤过程中,硝酸盐、亚硝酸盐和烟草特有亚硝胺(N-TSNAs)含量在变黄阶段上升,定色阶段含量下降,干筋阶段基本保持平稳变化;烤后烟叶硝酸盐、亚硝酸盐和N-TSNAs含量高于鲜烟叶。膜脂过氧化产物丙二醛（MDA）的含量、相对电导度和伤害度在变黄阶段急剧增加,定色阶段和干筋阶段缓慢增加,直至烘烤结束。     

A rapid urban site index for assessing the quality of street tree planting sites

Urban trees experience site-induced stress and this leads to reduced growth and health. A site assessment tool would be useful for urban forest managers to better match species tolerances and site qualities, and to assess the efficacy of soil management actions. Toward this goal, a rapid urban site index (RUSI) model was created and tested for its ability to predict urban tree performance. The RUSI model is field-based assessment tool that scores 15 parameters in approximately five minutes. This research was conducted in eight cities throughout the Midwest and Northeast USA to test the efficacy of the RUSI model. The RUSI model accurately predicted urban tree health and growth metrics (P < 0.0001; R² 0.18–0.40). While the RUSI model did not accurately predict mean diameter growth, it was significantly correlated with recent diameter growth. Certain parameters in the RUSI model, such as estimated rooting area, soil structure and aggregate stability appeared to be more important than other parameters, such as growing degree days. Minimal improvements in the RUSI model were achieved by adding soil laboratory analyses. Field assessments in the RUSI model were significantly correlated with similar laboratory analyses. Other users may be able to use the RUSI model to assess urban tree planting sites (<5 min per site and no laboratory analyses fee), but training will be required to accurately utilize the model. Future work on the RUSI model will include developing training modules and testing across a wider geographic area with more urban tree species and urban sites.     

烤烟烟叶油分研究进展

介绍了油分的概念、档次、组成以及烤烟油分的分级标准;概述了烤烟油分与烟叶外观质量、理化特性以及烟气质量之间的关系;从烤烟品种、生态因素、栽培措施和烟叶烘烤等方面分析了影响烤烟烟叶油分的因素。     

湖北主产烟区烤烟化学成分的变异分析

以湖北烟区烤烟样品为材料,分析了不同等级、产地和品种间烤烟化学成分的含量状况.结果表明:①湖北烟区烤烟烟碱含量较高,总氮含量较低,糖碱比B2F偏低、C3F适宜、X2F偏高,钾氯比在不同等级均较适宜,石油醚提取物含量较低.②不同产地间烤烟化学成分含量存在广泛的变异,B2F的氯和石油醚提取物总量,C3F的还原糖、糖碱比、总氮、钾、氯、氮碱比和石油醚提取物,以及X2F的总氮、氯和氮碱比在不同产地间差异达显著水平.③不同品种间烤烟化学成分含量亦表现较大变异,B2F的氯离子含量,C3F的烟碱、总氮、石油醚提取物、还原糖、氯离子含量和糖碱比,以及X2F的氯离子、烟碱、总氮、石油醚提取物总量和糖碱比均在品种间存在显著差异.