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31.
32.
用激光剥蚀电感耦合等离子体质谱研究小麦籽粒元素的共分布 总被引:4,自引:0,他引:4
增加粮食可食用部分微量营养元素的浓度, 需要更好地了解其在植株, 特别是籽粒内的运输和分布规律。激光剥蚀电感耦合等离子体质谱(laser ablation inductively coupled plasma mass spectrometry, LA-ICP-MS)是一种测定植物组织中元素空间分布的新技术。采用该技术对成熟小麦籽粒中锰(Mn)、铜(Cu)、锌(Zn)和磷(P)的空间分布及其关联程度定量研究。结果表明, 所测元素在籽粒不同部位的浓度分布差异很大。Cu、Zn和P浓度均以糊粉层最高, 胚乳最低, 胚居中, 浓度最大差异分别达15、42和33倍; Mn浓度则以胚最高, 胚乳最低, 糊粉层居中, 浓度最大差异达9倍。籽粒同一部位不同位置的元素浓度亦不相同, 外周胚乳(靠近糊粉层)的元素浓度大于内侧胚乳部位对应元素的浓度, 胚最外侧盾片部位的元素浓度大于胚中间位置的元素浓度, 且各元素趋势一致。比较分析发现, 麦粒不同部位元素的浓度变化存在明显的同步性, 籽粒中P浓度高的部位金属元素(Mn、Cu和Zn)浓度也高。这说明不同元素在向籽粒不同部位运输和积累过程中可能存在密切关联性。 相似文献
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C. W. Kan 《Fibers and Polymers》2008,9(2):166-170
In this paper, modifications of textile properties of polyester due to laser irradiation were studied. Properties included
fibre weight and diameter, tensile strength and elongation, yarn abrasion, bending, surface luster, wetting, air permeability
as well as crystallinity. Some properties were affected significantly while others were found unchanged. Besides, some properties
were positively affected and some were adversely changed. Generally speaking, laser irradiation could not affect the bulk
property of polymer due to its low penetration depth, and hence, the effect of the laser irradiation on the bulk and structural
properties was limited. However, the performance and comfort properties of the laser irradiated polyester could be largely
affected by laser irradiation as these properties could have been changed considerably if the surface was modified. 相似文献
35.
采用数值仿真的方法,研究了激光冲击强化对175A型柴油机曲轴疲劳寿命的影响,取得了数值仿真条件下曲轴过渡圆角处残余应力场的数据,数值仿真结果和实验结果的对比分析表明:数值仿真结果和实验结果较为接近,从而验证所采用的材料本构模型、冲击波峰值压力和冲击波作用时间是精确的.通过此类激光冲击强化仿真分析,可优化激光冲击的相关参数,使曲轴过渡圆角产生有利的残余应力场,从而为激光冲击强化曲轴提供优化的工艺参数. 相似文献
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Increased flour yield in hard wheat is associated with increased endosperm rheology index, calculated from strength and stiffness as measured by the SKCS. A study of the fractured endosperm of hard wheat varieties grouped according to similar rheology index values was performed using environmental scanning electron microscopy (ESEM). Differing microstructures and fracture patterns were observed between each group. Specifically, the group representing high rheology index had a greater concentration of small starch granules in prismatic cells. Samples of diverse wheat germplasm were grown at two sites and subjected to laboratory milling. Starch granule size distribution (SGSD) analysis using a laser diffraction method was undertaken on a subset of samples in triplicate representing a range in flour yield. The results supported an hypothesis for a significant influence of SGSD on flour yield of hard wheat varieties. In addition, a significant part (R2>0.40 (p<0.05) at two sites) of the association appeared to be under genetic control. Results indicate a more even gradation of distributions involving an increase in the sample volume % of small granule (types B and C) and decrease in type A granules. This was associated with increased rheology index values and higher flour yield. The ratio of type A:C starch granules accounted for up to 58% (p<0.05) of the variation in flour yield in the samples studied. Thus, rheological parameters measured using a rapid SKCS screening method can be linked to the genetic regulation of SGSD with implications for the improvement of commercial processing performance of hard wheat. 相似文献
38.
Tilman J. Schober Scott R. Bean Daniel L. Boyle Seok-Ho Park 《Journal of Cereal Science》2008,48(3):755-767
Gluten-free bread was prepared from commercial zein (20 g), maize starch (80 g), water (75 g), saccharose, NaCl and dry yeast by mixing above zein's glass transition temperature (Tg) at 40°C. Addition of hydroxypropyl methylcellulose (HPMC, 2 g) significantly improved quality, and the resulting bread resembled wheat bread having a regular, fine crumb grain, a round top and good aeration (specific volume 3.2 ml/g). In model studies, HPMC stabilized gas bubbles well. Additionally, laser scanning confocal microscopy (LSCM) revealed finer zein strands in the dough when HPMC was present, while dynamic oscillatory tests showed that HPMC rendered gluten-like hydrated zein above its Tg softer (i.e. |G*| was significantly lower). LSCM revealed that cooling below Tg alone did not destroy the zein strands; however, upon mechanical impact below Tg, they shattered into small pieces. When such dough was heated above Tg and then remixed, zein strands did not reform, and this dough lacked resistance in uniaxial extension tests. When within the breadmaking process, dough was cooled below Tg and subsequently reheated, breads had large void spaces under the crust. Likely, expanding gas bubbles broke zein strands below Tg resulting in structural weakness. 相似文献
39.
Detection of citrus canker in citrus plants using laser induced fluorescence spectroscopy 总被引:1,自引:0,他引:1
Citrus canker is a serious disease caused by Xanthomonas citri subsp. citri bacteria, which infects citrus plants (Citrus spp.) leading to a large economic loss in citrus production worldwide. In Brazil citrus canker control is done by an official
eradication campaign, therefore early detection of such disease is important to prevent greater economic losses. However,
detection is difficult and so far it has been done by visual inspection of each tree. Suspicious leaves from citrus plants
in the field are sent to the laboratory to confirm the infection by laboratory analysis, which is a time consuming. Our goal
was to develop a new optical technique to detect and diagnose citrus canker in citrus plants with a portable field spectrometer
unit. In this paper, we review two experiments on laser induced fluorescence spectroscopy (LIF) applied to detect citrus canker.
We also present new data to show that the length of time a leaf has been detached is an important variable in our studies.
Our results show that LIF has the potential to be applied to citrus plants. 相似文献
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