几种有机物对紫色土镉的溶出效应与吸附-解吸行为影响的研究

研究了天然有机物胡敏酸和富里酸 ,螯合剂EDTA和DTPA和四种简单有机酸对紫色土镉的溶出效应和吸附解吸行为的影响。结果表明 ,供试八种有机物均能显著促进镉从紫色土中的溶出。作用大小顺序为 :EDTA≥DTPA >柠檬酸 >胡敏酸 >草酸 >富里酸 >酒石酸≥水杨酸。有机物对土壤镉溶出和迁移的影响是其对土壤镉吸附和解吸综合作用的结果。有机物显著降低了紫色土对镉的吸附 ,其作用大小顺序与其对镉的溶出能力的相对大小顺序一致 ,同时也改变了吸附镉的解吸特性。有机物影响下 ,紫色土镉的吸附动力学模型以双常数方程拟合最佳。而吸附等温曲线以Freundlich方程拟合最好 ,吸附常数n与有机物对土壤镉的溶出率之间存在良好的相关性。     

木糖结晶的热力学特性研究

[目的]研究木糖结晶的溶解度及介稳区。[方法]采用激光法试验考察了木糖在纯水、乙醇-水溶液中的溶解度以及木糖在水中的超溶解度,确定木糖水溶液的结晶介稳区。[结果]木糖在纯水和不同体积配比的乙醇-水溶液中的溶解度随着溶液体系温度降低而明显减小,结晶介稳区的宽度在低温范围内比高温阶段要宽。[结论]为利用农产品废弃物木糖结晶的生产操作提供了理论依据。     

丝素/明胶共混膜的结构与溶解性能的初探

将丝素溶液与明胶溶液按不同共混比在不同条件下进行混合,制备成丝素/明胶共混膜。用环境扫描电镜、红外光谱仪、差示扫描量热分析系统分别测定共混膜的结构与热性能,采用烘干质量法测定共混膜的溶胀率和溶解率。结果表明:丝素与明胶的共混性好,共混膜结构改变,热稳定性好;烘干时间对共混膜的溶胀率和溶解率影响不显著,不同浓度乙醇处理对溶胀率有极显著影响,不同共混比则对溶胀率和溶解率都有极显著影响。     

用热水解法制备不同分子质量丝胶粉的溶解性差异及其成因探讨

用沸水法和高温高压热水法提取丝胶溶液,分别在90℃热水中进行二次降解处理,获得具有不同分子质量分布范围的各种热水解丝胶溶液,经冷冻干燥制成丝胶粉。对各种丝胶粉的热水溶解性差异比较和成因探讨表明,热水二次降解能够提高丝胶的水溶性,降解处理时间越长,其水溶性越大;丝胶的分子质量大小能显著影响其溶解性,而丝胶的结晶结构含量对其溶解性的影响较小。研究结果有助于对不同溶解性丝胶的有效利用。     

桑树花叶型萎缩病病株叶片组织中类似类病毒小分子RNA的检测与分析

为了能有效检测桑树中的类似类病毒小分子RNA(mscRNA),给解明mscRNA与桑树花叶型萎缩病发生的关系提供依据,以来自不同蚕区和不同季节发病桑园中的桑树花叶型萎缩病病株叶片为材料,采用LiCl法和DEAE纤维素柱层析法分别提取病叶组织中的mscRNA,然后利用往返聚丙烯酰胺凝胶电泳(Return-PAGE)进行检测鉴定,并对mscRNA在2mol/LLiCl溶液中的溶解性及该检测方法的灵敏度进行分析。结果显示:采用LiCl法和DEAE纤维素柱层析法都可以有效地提取阳性材料中含有的mscRNA;在溶解及不溶于2mol/LLiCl的阳性材料RNA样品中均含有丰富的mscRNA,mscRNA在LiCl溶液中的溶解性与已知类病毒的溶解性有很大的差异;当提取的病桑叶片组织总RNA量为480ng时,通过Return-PAGE可以检测到mscRNA,当总RNA量≤96ng时,已检测不到其中含有的mscRNA;在36株发病植株的叶片总RNA样品中,有7个样品检测出含有mscRNA,检出率约19%,在一些病症明显的植株样品中未检测出mscRNA,而在一些病症较轻的植株样品中却检测出mscRNA。检测结果提示:mscRNA与桑树花叶型萎缩病症的表现没有表现出明显的关联。     

Preparation of regenerated cellulose fiber via carbonation. I. Carbonation and dissolution in an aqueous NaOH solution

Cellulose carbonate was prepared by the reaction of cellulose pulp and CO₂ with treatment reagents, such as aqueous ZnCl₂ (20–40 wt%) solution, acetone or ethyl acetate, at −5–0°C and 30–40 bar (CO₂) for 2 hr. Among the treatment reagents, ethyl acetate was the most effective. Cellulose carbonate was dissolved in 10% sodium hydroxide solution containing zinc oxide up to 3 wt% at −5–0°C. Intrinsic viscosities of raw cellulose and cellulose carbonate were measured with an Ubbelohde viscometer using 0.5 M cupriethylenediamine hydroxide (cuen) as a solvent at 20°C according to ASTM D1795 method. The molecular weight of cellulose was rarely changed by carbonation. Solubility of cellulose carbonate was tested by optical microscopic observation, UV absorbance and viscosity measurement. Phase diagram of cellulose carbonate was obtained by combining the results of solubility evaluation. Maximum concentration of cellulose carbonate for soluble zone was increased with increasing zinc oxide content. Cellulose carbonate solution in good soluble zone was transparent and showed the lowest absorbance and the highest viscosity. The cellulose carbonate and its solution were stable in refrigerator (−5°C and atmospheric pressure).     

Effect of fermentation on sorghum protein fractions and in vitro protein digestibility

Changes in pH, titratable acidity, total soluble solids and proteins ofDabar sorghum (Sorghum bicolor (Linn) Moench.) during naturalfermentation at 37 ^°C for up to 36 h were monitored. The pH ofthe fermenting material decreased sharply with a concomitant increase in the titratable acidity. Total soluble solids increased with progressivefermentation time. The crude protein and non-protein nitrogen slightlyincreased during the last stages of fermentation. The in vitroprotein digestibility markedly increased as a result of fermentation.The globulin plus albumin fractions increased significantly (p 0.05)during the first 8 h of fermentation. Kaffirin fraction decreasedduring the first 8 h of fermentation but increased sharply as fermentationprogressed. Cross-linked kaffirins fluctuated during the fermentationprocess. Glutelin like protein, which was the minor fraction, trueglutelins, the second most abundant fraction, together with non-extractableproteins fluctuated during the fermentation process.     

Effect of cooking on cowpea protein fractions

Nine cowpea cultivars obtained from Wad Medani Research Station were used in this study. The variation in protein fraction was: albumins 4.0–12.0, globulins 65.6–79.7, prolamins 1.4–2.2, G₁-glutelins 0.9–3.0, G₂-glutelins 1.4–2.9. G₃-glutenins 9.1–14.0 and insoluble protein 0.5–3.0%. Two cowpea cultivars, H8-14 and CB-46, selected for their high albumin content, were cooked in 150 ml of boiling distilled water under reflux for 45 minutes. The protein fractions in the cooked seeds were determined. Results indicated that albumin and globulin fractions decreased significantly (p0.05) for both cultivars after cooking. This decrease was accompanied by a significant increase in G₃-glutelin fractions.     

Synthesis and characterization of copolyester sizing agents

The effect of main chain structure of anion-containing copolyesters on the properties of copolyester sizing agents was investigated. The copolyesters were prepared by conventional two step polymerization technique from DMT, DMI, DMS, EG, and DEG. The copolyesters synthesized were characterized by atomic absorption spectroscopy,¹H-NMR Spectroscopy, GC, FTIR Spectroscopy, and DSC. The solubility decreased as the DMT content increased. The copolyesters having DMT:DMI=1:1 showed the minimum viscosity. The effect of EG content on the solution stability was not clear and the samples having high DMI content showed better solution stability. The water resistance was best when only DMI and EG were used, while it was worst when DMT:DMI was 1:0.     

全反射X-射线荧光法分析茶叶中的矿质元素

用全反射X -射线荧光法 (TXRF)分析了江西婺绿和宁红茶的矿质元素含量。结果表明 ,所测茶叶中P、S、K、Ca的含量在 2 4 70～ 30 70 0 μg/g ;Mn、Fe在 2 0 6～ 10 70 μg/g ;Ti、Ni、Cu、Zn、Rb、Sr、Ba在 5 5～ 12 2 μg/g ;Pb含量均小于 4 0 μg/g (干基 )。宁红还表现出 ,品质越好 ,P、Ni、Zn含量越高 ,而K、Ca、Mn、Sr、Ba含量则相反。茶汤中K、Rb、Ni的浸出率为 30 5%～ 86 4% ;P、S、Mn、Cu、Zn、Sr为 11 6 %～ 4 2 4% ;Ca为 7 2 %～ 12 6 % ;Fe为 1 1% -2 6 %。茶汤中Ti、Ba、Pb的含量均低于TXRF法的检测限。宁红茶汤还表现出 ,品质越好 ,K、Ca、Mn、Zn、Rb、Sr的浸出率越高。但红茶汤中的K、Zn、Rb、Ni浸出率明显低于绿茶