Effect of drying methods on the discoloration of three major domestic softwood species in Korea

1 Introduction Three major softwood species in Korea are Japanese pine (Pinus densiflora), Korean pine (Pinus koraiensis) and larch (Larix leptolepis) which have been used for traditional buildings and furniture for a long period of time. They are easily discolored due to drying and UV irradiation. It has been observed that the discoloration varies with different drying methods and the extent of UV irradiation (Mottonen and Luostarinen, 2001; Kang, 2003). To prevent beech from discolorat…     

苋菜,油菜和芹菜矿物元素含量的研究

本文用ICPS-1000Ⅱ型等离子光谱仪,分别测定了苋菜、油菜、芹菜中的钾、钠、钙、镁、磷、铜、铁、锌、锰、锶十种元素的含量,标准曲线浓度与强度的相关系数(r=0.999)。在几种蔬菜中苋菜铁的含量高,苋菜5个品种中棠东红最高,而且锌、铜、钙、镁等也比较高。测定的7种油菜中,徐州苔菜锌铜比、锰铜比及锌铜锰总量高于其它品种。     

原子吸收法测定苦瓜中铁、铜、锌的含量

研究采用火焰原子吸收—分光光度计法同时测定苦瓜中铁、铜、锌含量的方法。进行样品预处理方法筛选和酸度条件试验,结果表明:干法灰化较湿法简便,被测元素无损失;酸介质及其加入量对被测元素稍有影响;检测方法精确度高、操作简便、实用性强,为进一步开发科学的测定方法提供了依据。     

微波法提取广西凌云特产新鲜川木瓜总酚的优化工艺

[目的]探讨微波法提取广西凌云特产新鲜川木瓜(皱皮木瓜)总酚的最优工艺.[方法]以没食子酸为对照品,用紫外-可见分光光度法,测定广西凌云特产川木瓜总酚含量.采用正交试验纤维素酶辅助提取的方法,考察提取溶剂浓度、微波功率、提取时间、提取次数、料液比等因素对广西凌云特产川木瓜总酚提取率的影响.[结果]以乙醇浓度80％,微波输出功率中高火,微波处理时间90s,提取2次,料液比1∶3 g/ml5个因素水平为最佳提取条件,此条件下凌云特产川木瓜总酚的提取率为0.0443％.[结论]此方法操作简便,重复性、稳定性良好,准确可靠,可为广西凌云特产川木瓜的质量控制及开发利用提供一定的方法和依据.     

分光光度计法测定饲料中总磷的不确定度评定

根据GB/T 6437—2002饲料中总磷的测定分光光度法中分光光度法测定饲料中总磷含量的测量不确定度进行评定。根据JJF1059—1999测量不确定度评定和表示的要求,分析了该测量过程的测量不确定度来源,建立数学模型,对测量不确定度的各个分量进行计算,最后合成求出标准不确定度和扩展不确定度。该法测定饲料中总磷含量为0.700 1%时,其扩展不确定度为0.006 6%。不确定度最主要的来源是标准溶液的制备和标准曲线的绘制。     

产类黄酮链霉菌的紫外线诱变选育

诱变选育高产类黄酮链霉菌菌株,采用不同强度的紫外线对出发菌株链霉菌HNS2-2单孢子悬液诱变处理。以出发菌株作为对照,分光光度法测定诱变菌株发酵产物黄酮类物质含量为评价指标,进行反复筛选。在20 W紫外灯、辐射距离30 cm、照射20 s条件下,获得高产菌株251,其黄酮类物质产量达41.87μg/mL,比出发菌株提高15.52%,且连续7次传代稳定性能稳定。通过紫外诱变选育的方法,能提高出发菌株黄酮类物质产量。     

Dichromate Digestion–Spectrophotometric Procedure for Determination of Soil Microbial Biomass Carbon in Association with Fumigation–Extraction

A dichromate digestion and spectrophotometric procedure is proposed for estimating soil microbial biomass carbon (C) in association with fumigation–extraction. The recommended procedure uses a volume (1.6 ml) of 0.5 M potassium sulfate (K₂SO₄) soil extracts and oxidant solution (dichromate–sulfuric acid, 2.4 mL), mixed with a volume (4 mL) for digestion at 140 °C for 30 min. The digested solution is then directly read for absorbance at 350 nm using a spectrophotometer, and the C in the digested soil extracts is measured against glucose standards. The K_EC (indicating the extractable part of microbial biomass C after fumigation) value is estimated as 0.33 for the proposed method. There are good correlations between soil microbial biomass C measured by the proposed method, the dichromate digestion titration, and oven oxidation by total organic C (TOC) analytical method. This method is a simple, rapid, and economical procedure associated with fumigation–extraction for biomass C analysis.     

白藜芦醇浸提及纯化过程在线检测方法研究

[目的]比较并筛选出适用于白藜芦醇在线检测的方法。[方法]通过试验对比了高效液相色谱(HPLC)和紫外分光光度(UV)法测定花生根白藜芦醇的异同。[结果]从线性相关性看,R(UV)=0.999 6,R(HPLC)=0.999 8,2种方法都有良好的线性度,都适用于花生根白藜芦醇的检测;从精密度[RSD(HPLC)=1.87%,RSD(UV)=2.52%]和回收率[HPLC 98.8%～101.2%,RSD为1.25%;UV法97.8%～103.5%,RSD为2.25%]看,HPLC法优于紫外分光光度法;从平均测得结果看,紫外分光光度法测得白藜芦醇含量为0.699 1%、RSD=2.52%(n=4),HPLC法测得白藜芦醇含量为0.690 4%,RSD=1.87%(n=4),2种方法结果相近。[结论]本着在线监测和仪器的普适性,紫外分光光度法更有优势,更适用于花生根白藜芦醇的检测。     

大豆根瘤促生剂对费氏中华根瘤菌产结瘤因子影响

以费氏中华根瘤菌(Sinorhizobium fredii)为研究对象,利用紫外分光光度计对大豆根瘤促生剂的作用进行了初步研究。结果表明:大豆根瘤促生剂可以使费氏中华根瘤菌的对数期提前,稳定期延长;同时,该根瘤促生剂可以诱导费氏中华根瘤菌产生结瘤因子;在根瘤促生剂存在的条件下,使用实验室培养的黄豆芽配制的培养基可以促进结瘤因子的产生;最佳的结瘤因子诱导剂为全豆芽研磨液+大豆根瘤促生剂,诱导剂的最佳用量为1.0%,最佳诱导温度为30℃。