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花生在生长及贮藏过程中因环境等因素影响极易感染黄曲霉和寄生曲霉,这两种霉的次生代谢产物——黄曲霉毒素具有强毒性和高致癌、致畸性。受污染花生中的黄曲霉毒素以B1、B2和G1、G2为代表,其检测方法目前主要有薄层色谱法（TLC）、高效液相色谱法（HPLC）和免疫化学方法等。对污染黄曲霉毒素的整粒花生的分选,目前仅是利用比色分选、图象识别等方法,依据外观差异剔除具有明显霉变特征的花生粒,尚无以黄曲霉毒素含量为检测指标的无损、在线和专用分选技术。为此,文中对污染黄曲霉毒素花生的无损在线检测技术研究提出了建议和设想。 相似文献
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应用微波辐照技术降解玉米粉中黄曲霉毒素B1(AFB1),采用免疫亲和柱净化-高效液相色谱-柱后衍生的方法测定玉米粉中AFB1的含量。试验考察了微波辐照功率、微波辐照时间以及AFB1初始含量对其降解效率的影响,并与传统加热法进行比较。结果表明：微波辐照主要利用非热效应对AFB1进行降解,当功率为250 W、时间为30 min时,AFB1降解率大于90%,残留量在国标和欧盟安全限量范围之内。微波辐照处理对玉米粉营养品质影响较小,且AFB1降解产物毒性明显降低,不会产生二次污染。 相似文献
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建立了乳粉中黄曲霉毒素M1残留的高效液相色谱-串联四极杆质谱联用测定方法。该方法经乙睛提取样品,以MGⅢ-C18柱(2.1×150mm,1.8μm)分离,流动相为乙睛和0.1%甲酸水(40∶60,V/V),电喷雾正离子MRM模式检测。该方法的检出限0.1μg/kg,线性范围0.4~20.0μg/L,加标回收率78.7%～95.1%,相对标准偏差为6.75%。 相似文献
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花生油在生产过程中极易受到黄曲霉毒素B1(Aflatoxin B1, AFB1)的污染。针对AFB1的传统检测方法操作繁琐、时效性差等问题,利用荧光光谱技术快速检测花生油中AFB1含量。首先通过三维荧光光谱确定最佳激发波长,使用K-means和自组织映射(Self organizing map, SOM)聚类算法对花生油中AFB1含量进行超标与否的定性鉴别,准确率均达95%以上;其次使用2种预处理算法和2种降维算法,选出竞争自适应重加权采样(Competitive adaptive reweighted sampling, CARS)为最佳的波长选择方法;随后将回声状态网络(Echo state network, ESN)用于AFB1的定量建模,同时与其他模型作比较,结果显示CARS-ESN模型获得了最佳AFB1含量预测效果;最后将麻雀搜索算法(Sparrow search algorithm, SSA)用于对ESN参数进行寻优,最终预测集决定系数达0.984,均方根误差达2.13μg/kg。结果表明了荧光光谱技术结合ESN预测花生油中AFB1含量的可行性,为在线检测食用油中真菌毒素含... 相似文献
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黄曲霉毒素对动物有剧烈的急性毒性和明显的慢性毒性。花生是最容易遭受黄曲霉菌感染的农作物之一,严重影响以花生为生产原材料的花生油品质。本文综合分析了花生油中黄曲霉毒素的污染途径和检测方法,并进一步探讨了它的去除方法。 相似文献
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通过建立赖氨酸表面修饰的胶体金体系,构建了一种检测霉变花生中黄曲霉毒素B_1(AFB_1)的方法。首先,用柠檬酸三钠还原法制备胶体金(Au NPs),然后在所制备的胶体金溶液中加入赖氨酸,制备了赖氨酸修饰的胶体金溶液(Lys-Au NPs)。利用紫外可见分光光度计和透射电镜对其进行表征,建立了Lys-AuNPs溶液在725 nm和525 nm处吸光度的比值(A_(725)/A_(525))与AFB_1质量浓度之间的相关关系。结果表明:AFB_1质量浓度在1～50 ng/mL范围内与A_(725)/A_(525)具有良好的线性关系,决定系数为0.996,检出限为0.2 ng/mL。花生样品中的加标回收率范围是85%～110%。通过高效液相色谱法(HPLC)对花生中AFB_1质量浓度进行验证,AFB_1质量浓度的预测值与真实值的均方根误差为0.865 1 ng/mL,相关系数为0.996 1。该方法具有快速简单、灵敏度高、操作简便等优点,可运用于霉变花生中AFB_1的快速检测。 相似文献
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黄曲霉菌产生的黄曲霉毒素 ,有强烈的致癌作用。因此 ,防止粮食、油料受到黄曲霉菌及其毒素的污染 ,尽量减少人们随同食物摄入黄曲霉毒素 ,是防止黄曲霉毒素危害人类健康的主要措施。一、黄曲霉毒素的一般特性黄曲霉毒素在水中溶解度较低 ,易溶于油及一些有机溶剂。黄曲霉毒素在一般烹调温度下很少受到破坏 ,只有在 2 80℃的高温下 ,才发生裂解。在高温、高湿条件下 ,本身有水分的花生、花生油、玉米、大米、棉籽等极易受到黄曲霉毒素污染。因此 ,高温、高湿及粮食本身的水分是易受黄曲霉菌污染的三大因素。二、黄曲霉菌污染的预防措施1 防… 相似文献
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建立了花生油中黄曲霉毒素B1的高效液相色谱-串联四极杆质谱联用测定方法。该方法经甲醇提取样品,以SB-C18柱（2.1×50mm,3.5μm）分离,流动相为0.1%甲酸水溶液和甲醇（梯度洗脱）,电喷雾正离子MRM模式检测。该方法的检出限0.2μg/kg,线性范围0.10～25.0μg/L,加标回收率85.8%～101.3%,相对标准偏差为5.70%。 相似文献
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为探究溶蚀条件下纳米SiO2混凝土微观特性和宏观性能的规律,采用2M NH4Cl溶液加速溶蚀试验,通过核磁共振技术、场发射扫描电镜和能谱分析研究孔隙特征、微观形貌及微结构的演变规律,同时采用灰熵法分析研究不同溶蚀龄期与不同NS掺量下混凝土的孔隙结构参数和孔隙半径分布对溶蚀损伤的影响规律,并在此基础上建立混凝土孔隙特征与抵抗溶蚀度的关系模型.在该试验中,水胶比为0.29,纳米SiO2掺量分别为0,1%,3%和6%.结果表明:纳米SiO2的掺入显著提高混凝土的抗压强度,在经过溶蚀循环后,<100 nm孔径占比对混凝土抗溶蚀度影响程度最大,灰熵关联度均大于0.999;相对于基准组,纳米SiO2混凝土溶蚀后有向外辐射的纤维状C-S-H生成,填充因溶蚀作用产生的裂隙,使其抗溶蚀性提高,延缓混凝土的劣化损伤;建立了混凝土抗溶蚀度与孔径占比为<100 nm,100~1000 nm和孔隙度的灰色模型,4组混凝土GM(1,4)模型预测值与试验值的平均绝对误差分别为8.18%,7.03%,7.83%和7.90%.该研究可为纳米SiO2混凝土在实际工程应用提供理论依据. 相似文献
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利用简单的水热法合成了锐钛矿型TiO2中空微球,对其结构和形貌进行了表征,并研究了TiO2中空微球的生长机制。以气体作为模板形成中空球体的制备方法,为制备其它中空材料提供了较好的方法。 相似文献
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In this paper, we discuss the effect of elevated CO2 concentration, irrigation and nitrogenous fertilizer application on the growth and yield of spring wheat in semi-arid areas. A field experiment was conducted at the Dingxi Agricultural Experiment Station during 2000–2002. According to the experimental design, the CO2 concentration increased to 14.5, 40 and 54.5 μmol mol−1, respectively, by NH4HCO3 (involving CO2) application, direct application of CO2 gas and combination of fertilizer NH4HCO3 plus CO2 application, which are equal to CO2 concentration of the Earth's atmosphere in the next 5, 15 and 20 years. The fertilizer application was divided into three levels: application of NH3NO3 (250 kg h m−2), NH4HCO3 (500 kg h m−2) and no fertilizer. Irrigation was divided into two levels: with 90 mm irrigation in the growth period and without irrigation. They can be combined as eight treatments. Each treatment was replicated three times. The results showed that elevated CO2 concentration owing to CO2 application leads to remarkable increase in leaf area index (LAI) and shoot biomass, and also generates the higher value of leaf area duration (LAD) that can benefit the photosynthesis in the growth stage and yield increase in crop compared than the no CO2 application treatment. When CO2 concentration elevated by 14.5, 40 and 54.5 μmol mol−1 with irrigation and fertilization, correspondingly, the grain yield increased by 6.3, 13.1 and 19.8%, respectively, whereas without irrigation and fertilization, the grain yield increased by only 4.2% when CO2 concentration increased to 40 μmol mol−1. Meanwhile, irrigation and fertilization can result in larger and deeper root system and have significantly positive influences on higher value of root/shoot (R/S) and water use efficiency. The grain yields in irrigation, irrigation plus NH3NO3 application and irrigation plus application of NH4HCO3 treatments are 73.4, 148.0 and 163.6% higher than that of no-irrigated and no-fertilized treatment, suggesting that both irrigation and fertilizer application contribute to remarkable increase of crop yield. In all treatments, the highest water use efficiency (WUE, 7.24 kg h m−2 mm−1) and grain yield (3286 kg h m−2) consistently occurred in the treatment with 90 mm irrigation plus fertilizer NH4HCO3 and elevated CO2 concentration (54.5 μmol mol−1), suggesting that this combination has an integrated beneficial effect on improving WUE and grain yield of spring wheat. These results may offer help to maintain and increase the crop yields in semi-arid areas. 相似文献
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工业烟气中的CO2浓度较低,并且含有不同污染物,能否直接用作增施气肥存在一定的不确定性。为研究将工业烟气中CO2直接用于农业生产中增施气肥的可行性,对工业烟气排放后的烟气特性、CO2组成、污染特性进行了分析和评估。基于CFD数值模拟技术,对工业烟气在大棚内的CO2扩散特性进行了模拟分析。研究结果表明,工业烟气中含有不同的污染物成分可能会对大棚内的环境空气质量产生影响,需经过合理评估并采取适当措施后方可满足农业生产的要求。基于燃煤电厂排放的烟气特点,在CO2吸收速率为5×10?8 m3/s、烟气稀释倍数为100,控制进入大棚内的SO2、NO2、Hg、HF和PM等污染物浓度达到15 mg/m3、8 mg/m3、5 μg/m3、0.2 mg/m3和7.5 mg/m3时,可实现大棚内的污染物浓度达到环境空气质量标准的一级标准（GB 3095—2012）,并且CO2浓度满足植物生长的浓度要求。不同入口布置方式对大棚内的CO2浓度影响较大,采用两边和中间同时布点的方案可以较好实现CO2浓度在大棚内的均匀性要求。因此,工业烟气中的CO2直接用于农业生产具有可行性,但在实际应用中,应结合烟气中的CO2浓度、植物的吸收速率、CO2喷入位置、稀释倍数和污染物浓度进行综合评估,并应用于农业生产。 相似文献
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Estimating groundwater recharge in response to increased atmospheric CO2 concentration and climate change is critical for future management of agricultural water resources in arid or semi-arid regions. Based on climate projections from the Intergovernmental Panel on Climate Change, this study quantified groundwater recharge under irrigated agriculture in response to variations of atmospheric CO2 concentrations (550 and 970 ppm) and average daily temperature (+1.1 and +6.4 °C compared to current conditions). HYDRUS 1D, a model used to simulate water movement in unsaturated, partially saturated, or fully saturated porous media, was used to simulate the impact of climate change on vadose zone hydrologic processes and groundwater recharge for three typical crop sites (alfalfa, almonds and tomatoes) in the San Joaquin watershed in California. Plant growth with the consideration of elevated atmospheric CO2 concentration was simulated using the heat unit theory. A modified version of the Penman-Monteith equation was used to account for the effects of elevated atmospheric CO2 concentration. Irrigation amount and timing was based on crop potential evapotranspiration. The results of this study suggest that increases in atmospheric CO2 and average daily temperature may have significant effects on groundwater recharge. Increasing temperature caused a temporal shift in plant growth patterns and redistributed evapotranspiration and irrigation water use earlier in the growing season resulting in a decrease in groundwater recharge under alfalfa and almonds and an increase under tomatoes. Elevating atmospheric CO2 concentrations generally decreased groundwater recharge for all crops due to decreased evapotranspiration resulting in decreased irrigation water use. Increasing average daily temperature by 1.1 and 6.4 °C and atmospheric CO2 concentration to 550 and 970 ppm led to a decrease in cumulative groundwater recharge for most scenarios. Overall, the results indicate that groundwater recharge may be very sensitive to potential future climate changes. 相似文献
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An EC-based irrigation strategy was tested in two greenhouse soilless cucumber crops grown under the autumn-winter conditions of the Mediterranean area. One of the crops was subjected to CO2 enrichment using a dynamic control strategy, while the other one was not enriched. Fresh yield of the CO2-enriched crop was 19% higher than of the non-enriched one, while crop water uptake was not significantly different between the two treatments, implying that the corresponding increase in water use efficiency, calculated on the basis of crop water uptake, was through increased growth and yield, not through reduction in water uptake and transpiration. The overall water use efficiency, based on the amount of applied water, was found to be about 40% higher in the CO2-enriched greenhouse due to the combined effect of (i) the greater biomass production for the same amount of transpired water and (ii) the lower leaching fraction in the enriched crop compared with the reference one. The latter effect could be ascribed to the higher mineral acquisition of the enriched crop. It is concluded that CO2 enrichment combined to an EC-based irrigation scheduling lead to synergistic beneficial effects on the overall water use efficiency of soilless greenhouse cropping systems and to a drastic reduction of the leaching fraction. 相似文献
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In the assessment of plant response to the climate changes, the effects of CO2 increase in the atmosphere and the subsequent rise of temperatures must be taken into account for their effects on crop physiology. In Mediterranean areas, a decrease of water availability and a more frequent occurrence of drought periods are expected. The objective of this study was to assess the impact of elevated CO2 concentration and high temperature on reference evapotranspiration (ETo) and crop evapotranspiration (ETc) in the Mediterranean areas. The Penman-Monteith equation was used to simulate the future changes of reference evapotranspiration (ETo) by the recalibration of the canopy resistance parameter. Besides, crop coefficients (Kc) were adjusted according to the future climate trend. Then the modified empirical model (ETc = ETo × Kc) was applied providing an effective quantification of the climate change impact on water use of irrigated crops grown in Mediterranean areas. In the studied area, water use assessment was carried out for the period from 1961 to 2006 (measured data) and for a period from 2071 until 2100 (simulated data), showing a future climatic scenario. Water and irrigation use of crops will change as a function of climate changes, thermal needs of single crops and time of the year when they grow. Climate simulation model foresees the tendency for a significant increase of temperatures and a decrease of total year rainfall with a change of their distribution. The temperature increase and the concomitant expected rainfall decrease lead to a rise of year potential water deficit. About the autumn-spring crops, as wheat, a further increase of water deficit, is not expected. On the contrary, for spring-summer crops as tomato, a significant increase of water deficit and thus of irrigation need, is foreseen. Actually, for crops growing in that period of the year, the substantial rise of evapotranspiration demand cannot be compensated by crop cycle reduction and partial stomatal closure. 相似文献
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20PY2掺气喷头是以20PY2摇臂喷头结构为基础,引入气液两相流理论得到的一种喷头.以20PY2掺气喷头为研究对象,研究其低压下的喷灌效果,并对比摇臂喷头的喷灌效果.试验评价指标:平均喷灌强度、蒸发漂移量、喷灌均匀系数及分布均匀系数;变量:工作压力和组合间距.试验结果表明:与摇臂喷头相比,掺气喷头的射程变化不大,但掺气喷头的平均喷灌强度随工作压力递增,随着组合间距递减;低压下,掺气喷头在风速为1 m/s时的蒸发漂移量约为5%,其组合喷灌的最佳工作压力和组合间距分别为300 kPa和1.1R.掺气喷头喷灌强度峰值与谷值的阶梯性较好,同等数量测点的喷灌强度峰值区间和谷值区间平均值趋向于平均喷灌强度,峰值区间和谷值区间喷灌强度在灌溉总强度中的占比分别低于和高于摇臂喷头.因此,喷灌效果优于摇臂喷头. 相似文献
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Winter wheat (Triticum aestivum L. cv. Kenong9204) was grown in open top chambers with either ambient or elevated CO2 concentrations (358 ± 19 μmol mol−1 or 712 ± 22 μmol mol−1, respectively) in well-watered or drought conditions. Although elevated CO2 did not significantly affect the height of the plants at harvest, it significantly increased the aboveground biomass by 10.1% and the root/shoot ratio by 16.0%. Elevated CO2 also significantly increased the grain yield (GY) by 6.7% when well-watered and by 10.4% when drought stressed. Specifically, in the well-watered condition, this increase was due to a greater number of ears (8.7% more) and kernels (8.6). In the drought condition, it was only due to a greater number of spikes (17.1% more). In addition, elevated CO2 also significantly increased the water use efficiency (WUE) of the plants by 9.9% when well-watered and by 13.8% under drought conditions, even though the evapotranspiration (ET) of the plants did not change significantly. Elevated CO2 also significantly increased the root length in the top half of the soil profile by 35.4% when well-watered and by 44.7% under drought conditions. Finally, elevated CO2 significantly increased the root water uptake by 52.9% when well-watered and by 10.1% under drought conditions. These results suggest that (1) future increases in atmospheric CO2 concentration may have a significant effect on wheat production in arid and semiarid areas where wheat cultivation requires upland cropping or deficit irrigation; (2) wheat cultivars can be developed to have more tillers and kernels through selective breeding and field management; and (3) fertilizer and water management in topsoil will become increasingly important as atmospheric CO2 concentration rises. 相似文献
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维生素B1、维生素B2营养米的挤压强化法制备与品质分析 总被引：2，自引：0，他引：2
利用挤压强化技术制备维生素B1、维生素B2营养米,高效液相色谱结果表明维生素B1、维生素B2的保留率分别为62.8%、81.0%。挤压制备的营养米理化特性与原料相比发生较大变化,其中糊化度、水溶性碳水化合物质量分数分别由8.86%、0.58%增加至86.21%、2.98%,而表观密度则由0.91 g/cm3下降至0.80 g/cm3;扫描电镜结果显示强化营养米的表面呈微孔状,但较光滑平整。利用TA-XT2i型物性测定仪分析强化营养米、杂交籼米(原料)和优质粳米,发现营养米的食用品质接近优质粳米。 相似文献