A nitric acid plant tissue digest method for use with inductively coupled plasma spectrometry

Abstract

A wet digestion method for plant tissue analysis for use with Inductively Coupled Plasma ‐ Atomic Emission Spectrometry has been developed. This procedure uses only nitric acid and eliminates the use of perchloric acid and subsequently eliminates the danger of HClO₄. explosions, and the problem of KClO₄ precipitation. Analysis of National Bureau of Standards plant materials ‐ orchard, tomato, and spinach leaves ‐ digested with nitric‐perchloric acid or nitric acid compared very well with the NBS certified values. The analytical results for eight other plant species were comparable for the two methods of digestion.

A summary of the recommended procedure for use with ICP is given below: 1. Weigh 0.5 to 1.0 g of plant tissue into a 50 ml Taylor tube.

2. Add 10 ml conc, nitric acid. Let stand overnight.

3. Heat samples at 125° C for 4 hours. Let cool.

4. Dilute to 12.5 ml with conc, nitric acid. Dilute to 50 ml with distilled water. Mix and let amorphous silica settle.

5. Aspirate directly into plasma for ICP analysis of P, K, Cu, Mg, Na, Fe, Zn, Ca, Mn.

     

小麦生理型与遗传型雄性不育相关基因锰超氧化物歧化酶(Mn-SOD)及果糖1,6-二磷酸醛缩酶(FBA)的表达分析

锰超氧化物歧化酶(Mn-SOD)是一种重要的抗氧化剂,果糖1,6-二磷酸醛缩酶(FBA)是叶绿体光合碳化阶段起重要调节作用的关键酶.本研究以小麦(Triticum aestivum L.)生理型与遗传型等基因雄性不育系及其对应育性正常的保持系为材料,选取花粉小孢子发育各时期的花药及三核期子房,对供试材料花药全蛋白表达差异研究的基础上,对雄性不育相关基因(Mn-SOD)及FBA进行核酸水平的实时荧光定量PCR分析,结果发现,与可育保持系相比,(1)生理型雄性不育系Mn-SOD基因在幼穗期、单核期和三核期表达量显著下调,而酶活力在幼穗期上调,在单核期下调;遗传型雄性不育系Mn-SOD基因在幼穗期和单核期表达量下调,酶活力在幼穗期上调,在二核期下调.(2)生理型雄性不育系和遗传型雄性不育系FBA基因表达量在幼穗期和单核期均下调,而对应同时期的FBA酶活力也下调,而遗传型不育系FBA基因在三核期表达量和FBA酶活力均上调.(3)Mn-SOD和FBA在遗传型雄性不育系三核期子房和花药中表达量均高于生理型雄性不育系和正常可育系,而在生理型雄性不育系花药中,Mn-SOD表达量明显低于对照可育系,在子房中其表达量略高于正常可育系.基因表达具有组织特异性,其蛋白表达较基因表达具有一定滞后性.Mn-SOD基因过量表达(单核至二核期),从而清除花药代谢紊乱产生的过多的活性氧,维持细胞正常功能;而花粉败育(生理型和遗传型雄性不育)导致花药失去活力,从而使花药叶绿体光合能力下降,FBA下调表达.研究结果提示,不同发育时期FBA及Mn-SOD酶活力变化与基因表达水平相一致,且这两个指标的变化直接或间接的影响了小麦花药的育性程度.     

Kriging方法在地下水风险评价中的改进与应用

地下水与地表水系统的交互影响在环境管理中的重要性日益凸显。其中,准确、快捷地估算水力渗透系数是科学管理的关键。但是,在环境规划与管理中,管理者所研究的尺度一般较大,在十几甚至几十平方千米的范围里面,传统的Kriging方法显得过于复杂,实用性大大降低。该研究在更加注重简单性与实用性原则的前提下,对Kriging方法进行了简化,并以此评价地下水的风险系数。      

人工降雨模型试验研究降雨入渗对滑坡类型之影响

台湾属海岛型气候,因而年雨量丰沛,降雨时间与空间的不均匀,对台湾大量的山坡地造成威胁。该研究系利用人工降雨系统,配合土壤模型试体探讨强降雨下滑坡破坏型态与坡体饱和度之关系,以对各种边坡稳定、边坡破坏获得更进一步的了解。研究结果得知边坡滑动主要发生在坡体趋近稳定饱和时,而坡面冲蚀则受土壤饱和度影响较小。土壤渗透率与降雨强度之关系亦影响着坡面破坏型态,降雨强度远大于土壤渗透系数时,其破坏型态以浅层滑动为主;降雨强度近似于土壤土壤渗透系数时,则主要为较深层滑动;若降雨强度小于土壤临界入渗率时,则主要为表面冲蚀破坏。     

Weed control and crop tolerance to propane flaming as influenced by the time of day

Time of day has been observed to affect flaming efficacy. The basis for the differential plant response is not well understood; however, daily variation in leaf relative water content (RWC) is thought to contribute to the response. Leaf RWC is the ratio of the amount of water in the leaf tissue compared to when fully turgid. To determine the influence of leaf RWC in plant response to propane flaming, greenhouse experiments were conducted during April and repeated in September of 2009. Two crops [4-leaf maize (Zea mays) and second trifoliate soybean (Glycine max)] and two weed species [5-leaf velvetleaf (Abutilon theophrasti) and 6-leaf green foxtail (Setaria viridis)] were flamed with four propane doses of 0, 29, 43 and 87 kg ha⁻¹ at 0, 4, 8 and 12 h after sunrise-HAS. Leaf RWC was measured before treatment application. Flaming treatment was conducted utilizing a hand flamer with one VT 2-23 C vapor phase burner positioned 20 cm above soil surface and angled horizontally at 30°. The propane pressure was 120 kPa and the application speeds were 1.6, 3.2 and 4.8 km h⁻¹. The plant responses evaluated were plant injury and fresh weight at 7 days after treatment (DAT). All plant species were more susceptible to flaming during the afternoon when they had lower leaf RWC at 8 HAS; however, the response of these plants did not differ with the plants flamed at 12 HAS. Green foxtail flamed at 87 kg ha⁻¹ at 0, 8 and 12 HAS had injury of 62, 76 and 82%, respectively. The same response was observed in velvetleaf which had 80% injury when flamed with 87 kg ha⁻¹ at 0 HAS and 93% injury when flamed at 12 HAS with the same propane dose at 7 DAT. Similar trends occurred for maize and soybean suggesting that leaf RWC could be one of the factors affecting plant response to flaming. Practical implication is that flaming operation should be conducted in the afternoon in order to improve efficacy of weed control and reduce propane consumption rate.     

Does crumb morphology affect water migration and crispness retention in crispy breads?

Crispness of bread is rapidly lost because of water migration inside the crumb towards the crust. How crumb properties determine this process independent of crust properties has not been examined before. Therefore, the aim of this study was to analyze and explain the influence of crumb morphology on the overall crispness retention. Crispness retention was determined by analyzing the acoustic emission of breads differing in either crust or crumb morphology. When crumb morphology is coarse with a lower number of large connections between the air cells, the effective diffusion coefficient is reduced. This effective diffusion coefficient of crumb, which equals approximately half the value of air, was estimated using X-ray micro-computer tomography images of crumb pieces. If the crumb has a lower effective diffusion coefficient, bread with similar crust properties has significantly longer crispness retention. Despite this, our data show that variations in properties of crust, which has 30 times higher permeability than crumb, have a larger impact on crispness retention than variations in properties of crumb.     

某水电站坝址区水文地质条件与水动力场研究

裂隙岩体渗流作为一个重要的科学研究和工程应用问题,近几十年来得到了国内外学者广泛的关注和持续的研究。裂隙岩体研究的难点和热点是渗透系数的求取和渗流模型的选取。以某水电站工程为例,采用压水试验法确定了坝址区岩体的渗透系数,应用等效连续介质数值模拟方法对坝址区地下水渗流场进行了模拟计算。     

饲料中添加抗菌肽对红姑鱼幼鱼生长性能及血清激素水平的影响

【目的】评价抗菌肽(Antimicrobial peptides,AMPs)对红姑鱼(Sciaenops ocellatus)幼鱼生长性能和血清激素水平的影响。【方法】在基础饲料中添加不同剂量的抗菌肽(0,0.1,0.3和0.5g/kg)作为试验饲料(即A0,A100,A300和A500组),饲喂平均体质量为(1.57±0.17)g/尾的红姑鱼8周,测定各组红姑鱼生长性能、血清激素(GH、T3、T4和IGF-I)水平,A0和A300组红姑鱼停饲后不同时间点的血清激素水平及肌肉和肝脏中IGF-I mRNA表达丰度。【结果】A300和A500组红姑鱼增重率、饲料效率和蛋白效率都显著高于A0组(P0.05),A100、A300和A500组的蛋白沉积率和成活率显著高于A0组(P0.05)。A300和A500组含肉率和鱼体粗蛋白含量显著高于A0组(P0.05),对形体指标和体组成的其他指标均无显著影响(P0.05)。养殖4,6,8周抗菌肽对血清中GH水平无显著影响(P0.05);A300和A500组血清T3、T4和IGF-I含量显著高于A0组(P0.05)。停饲后72h内持续取样发现,A300组的血清IGF-I在停饲后2h时达峰值,且在2和4h时血清IGF-I含量显著高于A0组(P0.05)。A300组的IGF-I mRNA在肝脏和肌肉中的表达量在4h时达峰值(P0.05)。【结论】饲料中添加抗菌肽0.3g/kg可促进红姑鱼的生长,提高饲料效率,增加含肉率。抗菌肽与血清GH的分泌无显著相关性,但可提高血清IGF-I水平及IGF-I mRNA在肌肉和肝脏中的表达量。     

植物根系细胞抑制镉转运过程的研究进展

镉是我国重金属污染土壤中最常见的元素,在酸性土壤中,镉能在水稻和蔬菜等作物根系中大量富集,并转运到地上部,其中可食部分的镉含量直接影响食品的质量安全。植物根系的细胞壁、细胞膜和细胞器对镉具有识别能力,能通过沉淀作用、络合作用和区域化作用等,把大量的镉固定在根系内,抑制其向地上部转运,从而保证地上部各种生理活动的正常进行。本文综述了植物根系细胞各组分的控镉原理,为发掘优异的种质资源和基因资源提供参考。     

微波预处理对巨尾桉木材渗透性的影响

采用微波辐照预处理巨尾桉木材,然后将试材相同条件下进行吸水试验和饱水干燥试验,测定试材的吸水增重率（WAR）和干燥失重率（WLR）,以增重率和失重率来评价试材的渗透性。并研究了试材的静曲强度和弹性模量。结果表明,微波预处理试材的吸水增重率和干燥失重率均大于未处理材,即预微波处理可以使巨尾桉木材的渗透性得到改善,相同条件下,经微波预处理的试材水分吸入和散失快于未处理材。但微波处理时间对增重率和失重率影响不明显,这可能与选择的微波功率较低和试材的变异性有关。微波处理对试材的静曲强度和弹性模量影响不大。