超临界CO2流体萃取杏仁油工艺研究

该研究以单因素试验和正交试验相结合的方法对苦杏仁脂肪油的超临界CO2萃取工艺进行了研究.确定了超临界CO2萃取杏仁油的最佳工艺为:萃取压力35 MPa、萃取温度50 ℃、CO2流量24 L/h、粒径60目、萃取时间2 h.各因素影响杏仁的得率的顺序为:粒径＞时间＞萃取压力＞CO2流量＞萃取温度.最佳工艺验证试验的杏仁油的得率为52.98%.本研究的结果为下一步综合、无毒、高效地开发利用苦杏仁奠定了基础.     

超临界CO2萃取万寿菊花中叶黄素的研究

采用超临界CO₂萃取技术,研究了从万寿菊花中萃取叶黄素的工艺条件。对影响超临界CO₂萃取叶黄素的各种因素,包括分离参数、原料含水率、粉碎粒径，超临界萃取温度、压力、流速、时间等因素进行了考察,得到较佳的萃取工艺条件为:原料含水率10.92％，粒径40目，萃取温度60℃，压力30 MPa，CO₂流速15 L/h，分离釜Ⅰ温度40℃，压力6 MPa，分离釜Ⅱ温度20℃，时间为6 h。     

超临界CO2连续浓缩鱼油EPA和DHA的研究

为了克服鱼油有效组分超临界CO₂间歇萃取方法的缺点，设计建造了超临界CO₂在内径14 mm、填料高1.8 m的填料塔中连续萃取浓缩鱼油有效组分的流程。根据单因素试验的结果，对工艺参数进行优化。设计了4因素3水平并考虑部分交互作用的正交试验方案，以综合指标进行评价，得到了优化工艺参数为：填料塔压为12.5 MPa；CO₂流量为5L/min；鱼油进料流量为0.8 mL/min；塔的温度分布为40～85℃。经方差分析得知，温度分布的影响对综合指标高度显著，鱼油进料流量对综合指标的影响显著，试验范围内的压力、CO₂流量、压力和温度分布交互作用、温度分布和CO₂流量交互作用以及压力和CO₂流量交互作用对综合指标没有显著影响。     

超声强化超临界CO2萃取人参皂苷的研究

为了探讨超声波对超临界CO₂萃取(SCE)的影响，考察了在不同萃取温度、萃取压力、萃取时间和流体流量下，有、无超声时超临界CO₂萃取人参皂苷的萃取率。试验结果发现，超声强化超临界CO₂萃取(USCE)的合适萃取温度比没加超声(SCE)时的低10℃；在各自合适的萃取压力下，USCE的皂苷萃取率是SCE的1.64倍；CO₂流体的流量大更有利于USCE。在SCE中，超声的加入能明显提高产物的萃取率和生产效率，降低生产能耗和节     

超临界CO2萃取大蒜精油及油树脂的研究

研究了大蒜精油及油树脂的超临界CO₂提取工艺，探讨了粒度，萃取及分离的温度、压力和时间对各萃取率的影响，建立了萃取温度、压力与各萃取率的数学模型。确定了超临界CO₂同时提取大蒜精油及油树脂的优化工艺条件。     

超临界CO2流体萃取技术提取核桃油的研究

以新鲜的核桃仁为原料，研究了在超临界状态下物料的粉碎度、萃取压力、萃取温度、萃取时间对核桃油萃取效果的影响。结果表明，超临界CO₂流体萃取核桃油的最佳工艺条件为粉碎度30目、萃取压强30 MPa、萃取温度45℃、萃取时间5 h，此条件下核桃油的萃取率可达93.98%。     

用超临界CO2脱除绿茶浓缩液中咖啡碱的工艺研究

对绿茶浓缩液中咖啡碱的超临界CO₂萃取工艺进行了研究，通过4因素正交试验探讨了浓缩液的浓度、操作压强、操作温度、萃取时间对咖啡碱脱除率的影响。结果表明，超临界CO₂萃取技术可以有效地脱除绿茶浓缩液中大部分的咖啡碱，在此基础上完成了用超临界CO₂脱除绿茶浓缩液中咖啡碱的连续作业试验，从而获得了加工脱咖啡碱绿茶浓缩液或速溶绿茶的新工艺。     

裸大麦中生育三烯酚的超临界CO2流体萃取工艺

采用四元二次通用旋转设计研究了裸大麦中生育三烯酚的超临界CO₂流体萃取工艺。结果表明：萃取温度对生育三烯酚提取率有显著影响，乙醇添加量和萃取时间对生育三烯酚提取率有极显著影响，而萃取压力对生育三烯酚提取率无显著影响，但萃取压力和乙醇添加量的交互项对生育三烯酚提取率有显著影响；在本实验条件下，生育三烯酚最佳超临界CO₂萃取条件为：萃取温度51.8 ℃、萃取压力34.7 MPa、乙醇添加量9%、萃取时间 120 min。     

柚子花芳香油超临界CO2萃取研究

介绍了新鲜柚子花中芳香性成分超临界CO₂萃取分离工艺和分析检测方法，重点探讨了压力、温度、时间对萃取率的影响。应用正交试验优化得出：影响萃取的主次因素依次为为萃取压力、萃取温度、萃取时间；较佳工艺参数为：压力18 MPa，温度50℃，时间90 min，流量25 L/min，得到超临界柚子花芳香油的萃取率高达2.7‰。应用气相色谱-质谱联用仪共鉴定出39个组分，占总芳香油的91.281%。通过对柚子花的深度加工研究，为开发高附加值的柚子花香精提供科学依据。     

乙醇溶剂与超临界CO2相结合提取高纯度卵黄磷脂的研究

采用乙醇溶剂首先提取蛋黄粉中的卵黄油，然后用超临界CO₂萃取方法脱除卵黄油中的中性脂肪，获得高纯度的卵黄磷脂。考察了工艺参数对提取效果的影响。试验表明：在乙醇溶剂提取卵黄油阶段，乙醇浓度是影响卵黄油提取率的最主要因素，温度是影响卵黄磷脂提取率的最主要因素；在超临界CO₂萃取阶段，磷脂的溶解度随萃取温度的升高而降低，中性脂质在55℃时溶解度最大。采用此工艺，卵黄磷脂得率为17.66%，纯度94.41%，且不含胆固醇。     

苦杏仁脱苦去毒的研究

通过单项比较筛选出混合酸盐法为最佳方法,采用L₈(4×2⁴)正交试验及对其结果进行直观和方差分析,确定出苦杏仁脱苦的影响因素依次为是否去皮、换药液次数、浸泡液温度、浸泡液用量、浸泡液种类;影响苦杏仁去毒的因素依次为浸泡液温度、换药液次数、浸泡液用量、是否去皮、浸泡液种类;但各因素的影响间均无显著差异。筛选出的混合酸盐法减少了换药液次数(即废水量),缩短了脱苦时间,保持了杏仁的色香味。最后对苦杏仁脱苦后的废水成功地进行了处理。     

杏仁油微胶囊制备工艺的优化

杏仁油中不饱和脂肪酸含量较高,为防止杏仁油的氧化,扩大杏仁油的用途,以麦芽糊精和牛乳分离蛋白为壁材,大豆卵磷脂为乳化剂,采用喷雾干燥法对超临界CO<,2>萃取的杏仁油进行了微胶囊化研究,采用响应面分析法研究了微胶囊的最佳配方,正交法确定了喷雾干燥的最佳工艺参数.结果表明:杏仁油微胶囊包埋最佳配方为杏仁油质量分数25%、牛乳分离蛋白质量分数25%、大豆卵磷脂质量分数2%和麦芽糊精质量分数48%,在20 MPa压力下均质处理;喷雾干燥适宜的工艺参数为进风温度180℃,出风温度80℃,进料温度50℃.在上述优化条件下可制得高质量高包埋率的杏仁油微胶囊产品,包埋率达94.7%.     

Absorption and transport of Na and Cl in rice cultivars differing in their tolerance to salinity: An examination of the effects of ammonium and potassium salts

The absorption and transport of Na and Cl from 0.1 mM and 10 mM ²²Na labelled NaCl or ³⁶Cl labelled KCl were examined in 15 days old seedlings of 3 cultivars of rice differing in their tolerance to salinity. Furthermore, the effects of 10, 100 and 1000 ppm (N)₂S on their uptake were studied. It was found that in general, the salt‐tolerant cultivars BR and PNL‐1 absorbed more Na and translocated a lesser proportion of it to the shoot, compared to the salt‐sensitive IR‐8, from 0.1 mM NaCl. The presence of (N)₂S reduced the uptake of Na in all the cultivars. It was also found that the presence of 100 ppm K, KN or NNreduced Na absorption from 0.1 mM NaCl significantly in all the cultivars, and the translocation to shoot in BR‐ Chloride transport from 0.1 mM NaCl was reduced by (N)₂S in all the cultivars. The 3 cultivars differed significantly in the rates of absorption and transport of Na and Cl. The results indicate that PNL‐1 which is a cross of IR‐8 X BR, has inherited the salt tolerance trait from BR. Lower rates of Na translocation to the shoot can be used as an index of salt tolerance in rice.     

新疆‘叶尔羌’扁桃果实不同生育期叶片氮磷钾光谱特性研究

【目的】通过分析果实不同生育期叶片光谱反射率对N、 P、 K的响应,探寻采用叶片光谱指数诊断N、 P、 K敏感时期,为新疆莎车‘叶尔羌’扁桃简便快捷的非破坏性营养诊断提供最佳时间窗。【方法】采用“3414”肥料效应试验,利用Unispec-SC光谱仪测定莎车‘叶尔羌’扁桃在不同N、 P、 K施肥水平下果实座果期、 膨大期、 硬核期、 成熟期叶片的光谱反射率。【结果】‘叶尔羌’扁桃果实不同生育期叶片光谱反射率波动取决于波长,在可见光波段变异最小。光谱反射率总体上呈现硬核期＞座果期＞膨大期＞成熟期。在不同N、 P、 K施肥水平下,‘叶尔羌’扁桃果实不同生育期光谱指数(ND705)之间均存在显著差异(P＜0.05)或者极显著差异(P＜0.01)。叶尔羌扁桃果实座果期、 膨大期、 硬核期、 成熟期叶片氮素的敏感波段分别为815~894 nm,375~398 nm,608~616 nm,429~437 nm; 磷素的敏感波段为766~802 nm,1023~1063 nm,708~713 nm,1130 nm; 座果期、 膨大期、 成熟期叶片钾素的敏感波段分别为815~894 nm,345~368 nm,475~491 nm。【结论】果实成熟期与硬核期是N、 P、 K叶片光谱营养诊断的敏感时期。叶尔羌扁桃果实座果期、 膨大期、 硬核期、 成熟期叶片N素的敏感波段分别为815~894 nm,375~398 nm,608~616 nm,429~437 nm; P素的敏感波段为766~802 nm,1023~1063 nm,708~713 nm,1130 nm; 座果期、 膨大期、 成熟期叶片钾素的敏感波段分别为815~894 nm,345~368 nm,475~491 nm。     

An examination of the total analysis of major elements in soil samples

Recently conventional chemical analyses were mostly replaced by instrumental analysis. Although results from both methods were examined in details after the samples had been solubilized or extracted by appropriate techniques, the solubilization method was considerably altered so as to be convenient for the following analysis. In atomic absorption spectrophotometry (AAS), for example, fusion technique was mostly inadequate because of the higher salts concentration in the obtained solution. The use of H₂SO₄ must also be avoided in acid digestion for SO₄ ^2- precipitates with Sr²⁺ or La³⁺ which must be added to eliminate interferences in the succeeding procedure. Therefore, it is essential to consider the whole scheme including sample treatments to evaluate the suitability of instrumental analysis. In this experiment, the suitability of the methods which have been employed in our laboratory was examined by analyzing 9 rock standards.     

Soil erosion and runoff response to plant‐cover strips on semiarid slopes (SE Spain)

Over a four‐year period (1997–2000), soil loss and surface‐runoff patterns were monitored in hillside erosion plots with almond trees under different plant‐cover strips (thyme, barley and lentils) on the south flank of the Sierra Nevada (Lanjaron) in south‐eastern Spain. The erosion plots (580 m a.s.l.), located on a 35 per cent slope, were 144 m² (24 m×6 m) in area. The plant‐cover strips, 3 m wide, ran across the slope. The most effective plant cover proved to be thyme, reducing soil loss by 97 per cent and runoff by 91 per cent, compared to bare soil. Barley reduced soil loss by 87 per cent and runoff by 59 per cent, compared to bare soil, while these percentages were 58 per cent and 18 per cent for lentils. Thyme proved 77 per cent more effective than barley and 93 per cent more effective than lentils in reducing soil loss; thyme was also 79 per cent more effective than barley and 90 per cent more than lentil in blocking runoff. The present study demonstrates the effectiveness of plant‐cover strips in controlling soil erosion and runoff on sloping agricultural land. Copyright © 2005 John Wiley & Sons, Ltd.     

我国酸性硫酸盐土壤中铁锰形态转化及迁移

酸性硫酸盐土壤酸性很强，有机质含量高，造成了这种土壤所特有的铁锰淋洗、转化和迁移规律。研究结果表明：在酸性硫酸盐土壤中全铁含量较低，一般在３５－５０ｇ／ｋｇ（以Ｆｅ２Ｏ３计），全锰含量也低，一般在０．２５－０．５５ｇ／ｋｇ（以ＭｎＯ计），一般滩涂中全铁大于６０ｇ／ｋｇ，全锰大于１ｇ／ｋｇ。酸性硫酸盐土壤中，铁的游离度较小，一般在３７－７０％，铁的活化度较大，一般在８－２０％，而滩涂中铁的游离度一般     

Denitrification potential in a grassland subsoil: effect of carbon substrates

We examined the potential of a subsoil to denitrify nitrate under optimal anaerobic conditions in a laboratory-based incubation when supplied with a range of C substrates of increasing recalcitrance. Both topsoil and its associated subsoil were supplied with nitrate and either glucose, starch or cellulose. Microbial respiration and the evolution of N₂O and N₂ were measured. The subsoil supported low amounts of microbial activity and responded only to the glucose treatment; with less than one-fifth of the N₂O production measured in the top soil. Overall, our findings demonstrated that the denitrification potential of this particular subsoil is relatively low and that only simple carbohydrates could be utilised readily by the resident microorganisms.     

CO2, CH4 and N2O fluxes of upland black spruce (Picea mariana) forest soils after forest fires of different intensity in interior Alaska

Abstract

Forest fires can change the greenhouse gase (GHG) flux of borea forest soils. We measured carbon dioxide (CO₂), methane (CH₄) and nitrous oxide (N₂O) fluxes with different burn histories in black spruce (Picea mariana) stands in interior Alaska. The control forest (CF) burned in 1920; partially burned (PB) in 1999; and severely burned (SB1 and SB2) in 2004. The thickness of the organic layer was 22 ± 6 cm at CF, 28 ± 10 cm at PB, 12 ± 6 cm at SB1 and 4 ± 2 cm at SB2. The mean soil temperature during CO₂ flux measurement was 8.9 ± 3.1, 6.4 ± 2.1, 5.9 ± 3.4 and 5.0 ± 2.4°C at SB2, SB1, PB and CF, respectively, and differed significantly among the sites (P < 0.01). The mean CO₂ flux was highest at PB (128 ± 85 mg CO₂-C m^?2 h^?1) and lowest at SB1 (47 ± 19 mg CO₂-C m^?2 h^?1) (P < 0.01), and within each site it was positively correlated with soil temperature (P < 0.01). The CO₂ flux at SB2 was lower than that at CF when the soil temperature was high. We attributed the low CO₂ flux at SB1 and SB2 to low root respiration and organic matter decomposition rates due to the 2004 fire. The CH₄ uptake rate was highest at SB1 [–91 ± 21 μg CH₄-C m^?2 h^?1] (P < 0.01) and positively correlated with soil temperature (P < 0.01) but not soil moisture. The CH₄ uptake rate increased with increasing soil temperature because methanotroph activity increased. The N₂O flux was highest [3.6 ± 4.7 μg N₂O-N m^?2 h^?1] at PB (P < 0.01). Our findings suggest that the soil temperature and moisture are important factors of GHG dynamics in forest soils with different fire history.     

Effect of Substrate Reutilization on Yield and Properties of Melon and Tomato Crops

Certain ecologically-friendly substrates have recently been shown to be perfectly viable alternatives to other more traditional ones such as rockwool, perlite, or some hydroponic systems. However, in order to be competitive for vegetable production in the Mediterranean region, substrates must be used for at least one year. The present study assessed random samples of two commercial substrates, almond shell and compost from greenhouse vegetable residue. The substrates were evaluated as growing media for long-term soilless production. Three experiments were conducted to evaluate the effects of reusing these substrates, comparing them with rockwool in terms of yield and fruit quality characteristics of melon and tomato. The physical, physico-chemical, and chemical properties studied differed significantly on reutilizing these materials. However, these differences did not prove to be limiting factors when fertigation parameters applied were adjusted according to substrate properties. The results suggest that compost and commercial almond shells seem to be acceptable growing media after at least 265 and 530 days of reutilization, respectively.