用辐射甘蔗渣接枝法制备高吸水剂初探

利用60Coγ射线辐照引发甘蔗渣与丙烯酸钠的接枝聚合反应制备高吸水剂,研究丙烯酸与蔗渣的不同配比、辐照剂量等因素对辐射接枝聚合产物吸水率的影响。结果表明:辐射剂量为2.0kGy,丙烯酸与蔗渣的比例(V/W)为2∶1时,产物达到其最大的吸水倍数,吸自来水可达干重的220倍,吸去离子水可达干重的798倍。     

γ射线引发合成P(AA-co-AM)/FA新型农林保水剂的性能研究

为了合成绿色环保农林保水剂,解决农林保水剂功能单一的问题,以丙烯酸和丙烯酰胺为原料,富里酸为添加剂,通过~(60)Co-γ射线引发合成聚丙烯酸/丙烯酰胺/富里酸[P(AA-co-AM)/FA]高吸水性材料,探讨了辐照剂量、FA添加量对保水剂吸水倍率、吸盐倍率的影响,保水剂的反复吸水性能以及其对土壤水分的影响。结果表明,当保水剂中富里酸(FA)含量为15 wt%,辐照剂量为6 kGy时,吸水倍率和吸0.9%NaCl溶液倍率分别为437倍和61倍;30 min达到溶胀平衡,重复吸水10次后,保水剂溶胀倍率为199倍,下降54%;自制保水剂的施用明显增加了土壤含水量,促进了玉米生长。该方法提高了保水剂的吸水保水性能,克服了传统合成方法污染大、能耗高等问题,同时具有多功能性,合成的高吸水性材料适合制作农林保水剂,为植酸类保水剂合成工艺提供了参考。     

利用小麦秸秆制备的保水剂性能研究

[目的]以小麦秸秆纤维素接枝丙烯酸制备保水剂,并检测各因素对保水剂吸水性能的影响,探索制备保水剂的最佳反应条件,以期制备出成本低,降解性好,保水性高的新型保水剂。[方法]采用水溶液聚合法制备保水剂,并通过单因素试验和正交试验来确定最佳反应条件,对合成产物的吸液倍率、保水性能和表观形态进行测定与表征。[结果]温度为70℃,去离子水用量为160ml,2.0%N,N’-亚甲基双丙烯酰胺(MBAM)用量为9ml,引发剂(过硫酸钾:硫代硫酸钠=3∶1)与丙烯酸单体比为2.0%,丙烯酸中和度为70%,反应时间为1h,合成的保水剂具有较高的吸水或盐水倍率,1g保水剂吸0.9%NaCl溶液41.2g/g,吸去离子水430.9g/g。红外光谱分析和电镜扫描结果表明,保水剂胶体接枝聚合成功,胶体具有良好的表面形态。[结论]制备的保水剂吸液速率快、重复吸水效果较好。保水剂在氯化铁溶液中吸水倍率最高,达到113g/g。复合离子溶液中,在离子浓度为1g/L时吸水倍率最高达57g/g。     

微波辅助合成壳聚糖基高吸水性树脂

在水溶性引发剂过硫酸钾(KDS)的引发下,用微波辐照使丙烯酸在壳聚糖分子链上接枝聚合,并加入N,N’-亚甲基双丙烯酰胺进行适度交联,制备高吸水性树脂。利用FT-IR对产物结构进行定性表征,结果表明,丙烯酸在壳聚糖的分子链上发生了接枝聚合反应。研究了反应条件对产物吸液性能的影响,并通过正交试验对工艺条件进行优化。在最佳条件下合成产物的吸水倍率为815.0g/g,吸生理盐水倍率为72.2g/g,吸人工尿液倍率为67.5g/g。在微波作用下产物合成速率是传统方法的数十倍,吸液性能明显高于后者,且操作条件容易控制,后处理步骤明显简化,无污染,是一种高效的清洁生产工艺。     

聚丙烯酸接枝碱木质素基铁肥的制备及其缓释性能

为提高铁元素的累积释放率,以丙烯酸单体接枝无定形高分子碱木质素制备了具有保水、缓释功能的聚丙烯酸接枝碱木质素基铁肥(简写,ALS-G-P(AA)铁肥)。考察了丙烯酸中和度、引发剂用量、交联剂用量、温度、碱木质素接枝率等因素对ALS-G-P(AA)铁肥吸水倍率的影响,研究了ALS-G-P(AA)铁肥在水中的Fe离子的缓释行为。结果表明:最佳制备条件为丙烯酸中和度60%、引发剂用量0.06g、交联剂用量0.03g、温度为60℃、碱木质素接枝率为25%;该产物铁质量分数为7.74mg/g,吸水倍率可达1017g/g。吸水饱和的ALS-G-P(AA)铁肥的肥效期为22d,其在水中铁元素累积溶出特征符合一元二次方程模型,铁元素释放曲线呈"S"形。该研究为高效施用铁肥和碱木质素在农业可降解缓/控释载体领域的应用提供了参考,并有望进一步拓展。     

~(60)Co γ射线辐照淀粉接枝丙烯酸制备高吸水树脂

利用60Coγ射线辐照引发淀粉接枝丙烯酸合成高吸水树脂,探讨糊化温度、丙烯酸中和度、辐照剂量、丙烯酸用量和交联剂用量等因素对吸水树脂吸水率的影响。正交试验结果表明,制备树脂较好的工艺条件为:淀粉3g,初始加入蒸馏水21ml,90℃下糊化15min,丙烯酸中和度80%,丙烯酸与淀粉的比例(V/W)为3:1,0.9%的N,N,-亚甲基双丙烯酰胺0.5ml,辐照处理3kGy,真空干燥温度60℃。在上述条件下制备的树脂可吸蒸馏水766ml/g,吸自来水278ml/g,吸0.9%NaCl水溶液64ml/g。     

纤维素-N-乙烯基吡咯烷酮辐射接枝共聚物的制备及其溶胀性研究

采用共辐射法制备了纤维素-N-乙烯基吡咯烷酮接枝共聚物Cell-g-NVP。考察了辐照剂量、去离子水用量和NVP/纤维素质量比对接枝率的影响。结果表明,在去离子水用量及NVP/纤维素质量比一定的情况下,接枝率随辐照剂量的增加而增加,并逐步达到平衡;在辐照剂量和NVP/纤维素质量比一定时,接枝率在去离子水用量为2ml时达到最大;在辐照剂量和去离子水用量一定时,接枝率随着NVP/纤维素质量比增加而增加,并逐步达到平衡;通过正交试验,得到制备接枝共聚物的最佳工艺条件为:辐照剂量8kGy,去离子水用量4ml,NVP/纤维素质量比4∶1,此时得到的接枝共聚物接枝率为354.8%。正交试验结果也表明NVP/纤维素质量比对接枝率影响最大,其次是辐照剂量。红外光谱表明接枝反应发生在NVP乙烯基部位,接枝共聚物保留了NVP的内酰胺结构;热重分析表明其热稳定性得到了增强;通过溶胀性研究表明接枝共聚物的溶胀性得到增强,且持水性较好。     

γ射线辐照与NaOH溶液协同预处理对玉米秸秆酶解产糖率及微观结构的影响

为提高玉米秸秆的酶解产糖量,研究γ射线辐照与NaOH溶液协同处理对玉米秸秆中酶解还原糖得率的影响。采用红外光谱(IR)、X射线衍射分析和扫描电镜(SEM)分析协同处理对玉米秸秆微观结构的影响。结果表明,较低剂量辐照对玉米秸秆酶解还原糖得率作用不明显,但可大幅降低后续碱浸泡所需的用量和时间。电镜扫描结果表明,经200kGy剂量辐照与碱协同预处理的样品,表面积增加最多。经200kGy辐照和2%NaOH溶液协同预处理的玉米秸秆,其酶解还原糖含量达到了48.34%,这为应用酶解玉米秸秆生产工业乙醇提供了理论依据。     

淀粉接枝聚丙烯酸钠高吸水树脂的电子束法制备及结构表征

本文将电子束辐照技术和功能材料制备技术相结合,采用10 Me V电子束辐照法引发糊化的木薯淀粉与部分中和的丙烯酸单体进行接枝共聚反应,并采用N,N’-亚甲基双丙烯酰胺为交联剂,制备出一种淀粉接枝聚丙烯酸钠系高吸水树脂,并通过红外光谱(FTIR)和扫描电子显微镜(SEM)技术对木薯淀粉和共聚产物的官能团结构和表面形态进行验证。采用正交试验设计方法分析单体/淀粉比、辐照剂量、交联剂/单体比以及单体中和度对该反应接枝参数以及吸水性能的影响,4种因素的变化均可引起共聚产物的吸水能力变化,影响显著性次序为:单体中和度单体/淀粉比交联剂/单体比辐照剂量。获得最佳吸水性能的反应条件为:AA/St=3.5 g·g-1,MBA/AA=5 mmol·mol-1,辐照剂量D=6k Gy,中和度为70%,上述条件下获得共聚产物的吸水倍数为435 g·g-1。本文为采用电子束法制备高吸水材料提供了科学依据与技术支持。     

不同肥料对高吸水性树脂吸水倍率的影响及养分吸持研究

通过对高吸水性树脂在不同肥料溶液中吸水倍率和肥料养分吸持量的测定,研究了不同吸水倍率的聚丙烯酰胺型、聚丙烯酸盐型、淀粉接枝型高吸水性树脂与氮、磷、钾肥料的相互影响。结果表明:化学肥料能显著降低高吸水性树脂的吸水倍率,并随肥料浓度的增加,高吸水性树脂吸水倍率显著降低。但不同肥料品种对高吸水性树脂吸水倍率的影响程度不同:供试肥料对高吸水性树脂的影响程度依过磷酸钙、磷酸一铵、硫酸钾、氯化铵、硫酸铵、氯化钾、尿素顺序递减。高吸水性树脂在水中溶胀时,在吸收大量水的同时,也吸持溶解在水中的肥料分子或离子,吸持量的大小因高吸水性树脂和肥料种类而不同。肥料浓度达到一定值后,随着高吸水性树脂吸水倍率的降低,吸持量也随之降低。聚丙烯酰胺型和聚丙烯酸盐型的高吸水性树脂在肥料溶液中的稳定性较淀粉接枝型要强。     

低氮和干旱胁迫对富士和秦冠生长及氮素利用的影响

【目的】以富士（Fuji）、 秦冠（Qinguan）嫁接在平邑甜茶（Malus hupehensis Rehd.）上的当年生盆栽苗为试验材料,采用砂培方法,研究了缺氮胁迫和干旱对富士和秦冠生长情况、 光合参数、 植株各部位氮磷钾含量及氮素利用效率的影响,分析比较了低氮干旱条件下富士和秦冠生长及氮素利用的差异,以期为果树生产高效肥水利用提供理论指导。【方法】试验共设四个处理: 正常氮正常水（ZZ）、 低氮正常水（DZ）、 正常氮干旱（ZG）、 低氮干旱（DG）。氮素和水分均设置两个水平,分别为正常氮（6 mmol/L NO-3-N）、 低氮（0.3 mmol/LNO-3-N）、 正常供水（保持盆中砂子相对含水量为饱和含水量的80%~85%）、 干旱处理（保持盆中砂子相对含水量为饱和含水量的60%~65%）。【结果】富士和秦冠的生物量（茎和叶）、 株高茎粗等生长指标以及光合速率、 气孔导度、 蒸腾速率均为正常氮正常水（ZZ）＞低氮正常水（DZ）＞正常氮干旱（ZG）＞低氮干旱（DG）,并且相对应处理下秦冠的以上指标均高于富士;正常供水下,缺氮处理使富士、 秦冠的根冠比比正常氮处理均有所增加,富士提高了2.05%,秦冠提高了22.40%。富士和秦冠的氮、 磷、 钾含量均表现出正常氮正常水（ZZ）＞低氮正常水（DZ）＞正常氮干旱（ZG）＞低氮干旱（DG）; 氮、 钾元素含量在植株各部位的分布顺序依次是叶＞根＞茎,磷元素则是根＞叶＞茎;光合氮素利用效率（PNUE）和氮素利用效率表现为秦冠处理之间差异极显著,富士处理之间差异不显著;秦冠的PNUE和NUE明显高于富士,在低氮正常水（DZ）处理下,秦冠氮肥利用率比富士高42.07%,在低氮干旱（DG）处理下高64.14%;低氮胁迫下富士和秦冠的NUE显著提高,并且秦冠提高的幅度高于富士。【结论】施用氮肥能够显著提高富士与秦冠的干物质量,同等水肥条件下,秦冠生长优于富士;水分亏缺会减少叶片对氮的吸收,干旱条件下适度增施氮肥,可提高果树的抗旱能力;低氮干旱胁迫下秦冠的生长指标、 光合指标及氮素利用效率指标均优于富士,表现出较强的抗低氮干旱胁迫的能力。     

Pasture Vegetation Elemental Analysis by Laser-Induced Breakdown Spectroscopy

Laser-induced breakdown spectroscopy (LIBS) is a new technique for the analysis of plant material. This study investigates the application of LIBS to pasture-based plant samples. The LIBS measurements were obtained from pelletized pasture samples (100 samples) that had been also analyzed by inductively coupled plasma–optical emission spectroscopy (ICP-OES) following microwave digestion for calibration and comparison purposes. Comparisons for elements sodium (Na), potassium (K), magnesium (Mg), calcium (Ca), manganese (Mn), iron (Fe), copper (Cu), zinc (Zn), boron (B), phosphorus (P), and sulfur (S) showed that LIBS could be used for almost all the standard profile total elements with concentrations down to low mg/kg levels (observed error of Na: 0.024 percent, K: 0.18 percent, Mg: 0.016 percent, Ca: 0.073 percent, P: 0.017 percent, Mn: 31 mg/kg, Fe: 150 mg/kg, Zn: 6.6 mg/kg, and B: 1.1 mg/kg). Elemental analysis at less than mg/kg levels was not possible using LIBS. The elements S and Cu were particularly difficult to analyze with reliability using LIBS at the concentration levels found in the plant samples. Replacing microwave digestion and subsequent ICP analysis with a direct analysis of dried plant samples using LIBS has the potential to improve the productivity and reduce the cost of testing.     

Faculty positions:Center for Agricultural Resources Research,Chinese Academy of Sciences

正The Center for Agricultural Resources Research(CARR),the Institute of Genetics and Developmental Biology(IGDB),Chinese Academy of Sciences,invites applicants for several research group leader positions.CARR is one of the research organizations in Chinese Academy of Sciences(CAS).We seek nominations and applications from individuals who have expertise and a record of accomplishment in research areas related to ecology,agro-hydrology,     

Biodiversity and ecogeography of wild Lactuca spp. in some European countries

Staff members of the Department of Botany of Palacký University in Olomouc and Gene Bank Department – Workplace Olomouc, Research Institute of Crop Production in Prague, Czech Republic, conducted an expedition in seven European countries (Austria, Czech Republic, France, Germany, Italy, the Netherlands, Switzerland) in August/September 1999 to collect wild Lactuca spp. germplasm and study its geographic distribution, ecology and biodiversity. During the mission, more than 600 locations were visited resulting in the collection of 602 seed samples (accessions) of wild Lactuca species and 13 seed samples of related genera (Chondrilla and Mycelis). Lactuca serriola f. serriola, L. serriola f. integrifolia, L. saligna and L. viminea subsp. chondrilliflora were prevalent in southern Europe (Italy, France), however, only L. serriola was common in central and western Europe (Austria, Czech Republic, Germany, Netherlands, Switzerland). The greatest diversity of Lactuca species was found in France, where also the most seed samples (165) were collected. The most characteristic habitats with a high density of Lactuca spp. populations were observed along roads and highways, grassy ditches, ruderal communities, and dust-heaps. Natural infections by powdery mildew (Erysiphe cichoracearum) and downy mildew (Bremia lactucae) on some wild Lactuca spp. were observed. Recent observations concerning the geographic distribution, population structure, habitats, and natural occurrence of diseases of Lactuca spp. are discussed. This assemblage of genetic resources of Lactuca spp. can serve as the basis of future studies of species diversification, spatial population structure, plant microevolution, domestication processes, and genetic variability of host-parasite interactions.     

Macroinvertebrates in North American tallgrass prairie soils: effects of fire, mowing, and fertilization on density and biomass

The responses of tallgrass prairie plant communities and ecosystem processes to fire and grazing are well characterized. However, responses of invertebrate consumer groups, and particularly soil-dwelling organisms, to these disturbances are not well known. At Konza Prairie Biological Station, we sampled soil macroinvertebrates in 1994 and 1999 as part of a long-term experiment designed to examine the effects and interactions of annual fire, mowing, and fertilization (N and P) on prairie soil communities and processes. For nearly all taxa, in both years, responses were characterized by significant treatment interactions, but some general patterns were evident. Introduced European earthworms (Aporrectodea spp. and Octolasion spp.) were most abundant in plots where fire was excluded, and the proportion of the total earthworm community consisting of introduced earthworms was greater in unburned, unmowed, and fertilized plots. Nymphs of two Cicada genera were collected (Cicadetta spp. and Tibicen spp.). Cicadetta nymphs were more abundant in burned plots, but mowing reduced their abundance. Tibicen nymphs were collected almost exclusively from unburned plots. Treatment effects on herbivorous beetle larvae (Scarabaeidae, Elateridae, and Curculionidae) were variable, but nutrient additions (N or P) usually resulted in greater densities, whereas mowing usually resulted in lower densities. Our results suggest that departures from historical disturbance regimes (i.e. frequent fire and grazing) may render soils more susceptible to increased numbers of European earthworms, and that interactions between fire, aboveground biomass removal, and vegetation responses affect the structure and composition of invertebrate communities in tallgrass prairie soils.     

Properties of anaerobically digested and composted municipal solid waste assessed by linking soil mesofauna dynamics and nitrogen modelling

We have studied the effect of anaerobically digested (ADMSW) and composted municipal solid waste (CMSW) on mineralization and foodweb dynamics to verify the hypothesis that ADMSW would immobilize N right after addition to soil in contrast to addition with CMSW. Another hypothesis was that the mesofauna (enchytraeids and microarthropods) would stimulate N release from the decomposer community. We measured excretion of -N and urea-N from the mesofauna and hypothesized that enchytraeids would release urea. ADMSW and CMSW were amended to pots with sandy loam and barley. The pots were divided into treatments with or without mesofauna. Mesofauna, plant N and biomass, soil N and ergosterol (fungal biomass) were measured over a 113-day period of four equidistant samplings. Soil respiration, N mineralization and N release by the mesofauna were modelled from concurrent studies. ADMSW- and CMSW-treated soils initially (<20 days) immobilized N. The amendments did not increase plant growth substantially, and this was probably due to N-limitation in the early stages of plant growth. Enchytraeid abundance was about three times higher in ADMSW- than CMSW-treated soils, indicating that ADMSW contained more labile compounds, bacteria, and microfauna. The mesofauna did not affect N-content, but the cumulated -N excreted by the mesofauna was estimated to be substantial and about one-fifth of total plant N in ADMSW. An explanation for this discrepancy might be that in the absence of the mesofauna, other members of the detrivore and microbivore community performed the mesofauna’s function. Neither enchytraeids nor microarthropods excreted urea.     

Faculty positions: Center for Agricultural Resources Research,Chinese Academy of Sciences

正The Center for Agricultural Resources Research(CARR),the Institute of Genetics and Developmental Biology(IGDB),Chinese Academy of Sciences,invites applicants for several research group leader positions.CARR is one of the research organizations in Chinese Academy of Sciences(CAS).We seek nominations and applications from individuals who have expertise and a record of accomplishment in research areas related to ecology,agro-hydrology,     

Faculty positions: Center for Agricultural Resources Research,Chinese Academy of Sciences

正The Center for Agricultural Resources Research(CARR),the Institute of Genetics and Developmental Biology(IGDB),Chinese Academy of Sciences,invites applicants for several research group leader positions.CARR is one of the research organizations in Chinese Academy of Sciences(CAS).We seek nominations and applications from individuals who have expertise and a record of accomplishment in research areas related to ecology,agro-hydrology,     

Variation in quality parameters between and within 14 Nordic tree fruit and berry species

Abstract

A 3-year study was carried out to investigate quality parameters in 14 tree fruit and berry species grown in southern Norway. The species were blueberry, apple, aronia, sour cherry, sweet cherry, red raspberry, strawberry, blackcurrant, gooseberry, red currant and elderberry, harvested along with wild bilberry, cloudberry and lingonberry. Significant differences between species were identified for all quality parameters. The coefficient of variation between species was lowest for pH (12.5%), dry matter (18.9%) and soluble solids (25.3%), followed by titratable acids (59.3%), total phenolics (83.8%), antioxidant capacity FRAP (85.7%) and antiradical power by the DPPH-assay (97.8%), total monomeric anthocyanins (132%) and ascorbic acid (137%). Average coefficient of variation within species were lower and ranged from 4 (pH) to 62% (ascorbic acid). Only the FRAP values were significantly affected by harvesting year with lower levels in 2004 than in 2005 and 2006. There were significant interactions between species and harvesting year for dry matter, soluble solids, pH, ascorbic acid and FRAP. The results indicate generic ranges in composition within species independent upon growing location and climate, and the composition of the tree fruits and berries is not likely to deviate from these ranges. It is concluded that desirable composition of tree fruits and berries and their products should primarily be achieved by selection among species rather than searching fors broadened variation within individual species.     

Potassium Fixation and Release Characteristics in Rhizosphere and Nonrhizosphere Soils for a Rapeseed–Rice Cropping Sequence

Potassium (K) fixation and release in soil are important factors in the long-term sustainability of a cropping system. Changes in K concentration and characteristics of K fixation and release in rhizosphere and nonrhizosphere soils in the rapeseed (Brassica napus L.)–rice (Oryza sativa L.) rotation were investigated using a rhizobox system. The concentrations of different forms of K in both rhizosphere and nonrhizosphere soils decreased with plants compared to without plants, regardless of K fertilizer application. Potassium uptake by crops mainly came from the rhizosphere soil. In the treatment without K fertilizer (–K), the main form of K supplied by the soil to the crops was 1.0 mol L^?1 nitric acid (HNO₃) nonextractable K, followed by nonexchangeable K, and then exchangeable K. In the treatment with K fertilizer (+K), the main K forms supplied by the soil to the crops were exchangeable K and nonexchangeable K. The amount and rate of K fixation after one cycle of the rapeseed–rice rotation was greater in rhizosphere soil than in nonrhizosphere soil. The amount and rate of K fixation of soil in the +K treatment were significantly less than in the –K treatment. The cumulative amounts of K released with 1.0 mol L^?1 ammonium acetate (NH₄OAc) and 1.0 mol L^?1 HNO₃ extraction increased with the increasing numbers of extractions, but the K-releasing power of soil by successive extraction decreased gradually and finally became almost constant. The release of K was less in rhizosphere soil than in nonrhizosphere soil. The release of K in the +K treatment was similar to that in the –K treatment in rhizosphere soil, but the K release in nonrhizosphere soil was greater with the +K than the –K treatment. Overall, the information obtained in this study will be helpful in formulating more precise K fertilizer recommendations for certain soils.