华北平原农田裂缝对硝态氮淋溶的影响

土壤干缩开裂是常见的自然现象。目前关于土壤干缩开裂的研究主要集中于裂缝的最终形态特征,并且以室内试验为主。本研究通过室外大田试验,结合动态计算机图像分析及水氮运移模拟软件WHCNS,研究土壤干缩开裂的动力学过程、特征及其对农田水氮运移的影响。利用原位熔化石蜡浇筑得到了裂缝三维结构形态,借助三维激光扫描仪量化裂缝的几何特征,发现每平米裂缝平均长度为4.58m,裂缝上表面平均宽度为5.72 mm,平均深度为9.06 cm。基于三维扫描仪提取得到的裂缝几何参数,通过WHCNS仿真模拟,发现相较于无裂隙情况,裂隙的存在分别增加了传统施肥和优化施肥情况下97.40%和256.43%的硝态氮淋失量;与优化施肥模式相比,传统施肥模式更容易造成硝态氮的淋失风险。在模拟灌溉模式对硝态氮淋洗情况的影响时,其差异不明显;强降雨的设置同样增加了硝态氮的淋失风险,导致硝态氮的年均淋洗量增加83.61%。裂缝的存在严重影响农田作物对肥料的吸收和利用,通过优化施肥量、更改灌溉模式以及避免强降雨前施肥都可以减少肥料的损失。     

海洋真菌Aspergillus sp. SCS-KFD03的化学成分分析

为了研究海洋真菌Aspergillus sp.SCS-KFD03次级代谢产物的活性成分,采用硅胶柱色谱、Sephadex LH-20凝胶柱色谱和高效液相色谱等技术从其发酵液中分离得到7个化合物,运用各种波谱方法鉴定为3β,5α-dihydroxy-(22E,24R)-ergosta-7,22-dien-6-one(1);3β,4α-dihydroxy-26-methoxyergosta-7,24(28)-dien-6-one(2);麦角甾醇(22E,24R)-ergosta-5,7,22-trien-3β-ol(3);leporin B(4);astellolide G(5);astellolide B(6)和astellolide A(7),并测定化合物的抗氧化活性、乙酰胆碱酯酶和α-糖苷酶抑制活性。结果表明:化合物2,3,5和6具有一定的抗氧化活性,化合物2具有较弱的乙酰胆碱酯酶抑制活性,化合物4具有强于阳性药阿卡波糖的α-糖苷酶抑制活性。     

Impact of Deficit Irrigation on Maize Physical and Chemical Properties and Ethanol Yield

The objective of this research was to study the effect of irrigation levels (five levels from 102 to 457 mm of water) on the physical and chemical properties and ethanol fermentation performance of maize. Twenty maize samples with two crop rotation systems, grain sorghum–maize and maize–maize, were harvested in 2011 and evaluated at the Kansas State University Southwest Research‐Extension Center near Garden City, Kansas, under a semiarid climate. Results showed that maize kernel weight, density, and breakage susceptibility decreased as irrigation level decreased. Starch contents of maize samples grown under a low irrigation level were approximately 3.0% lower than those under a high irrigation level. Protein contents ranged from 9.24 to 11.30% and increased as irrigation level decreased. Maize flour thermal and rheological properties were analyzed by differential scanning calorimetry and the Micro Visco‐Amylo‐Graph‐U device. Starch gelatinization temperature increased significantly as irrigation level decreased, whereas starch pasting viscosity decreased as irrigation level decreased. Free amino nitrogen (FAN) was significantly affected by irrigation level: it increased as irrigation decreased. Ethanol fermentation efficiency ranged from 90.96 to 92.48% and was positively correlated with FAN during the first 32 h of fermentation (r² = 0.645). Deficit irrigation had a negative impact on ethanol yield. The maize with lower irrigation yielded about 4.0% less ethanol (44.14 mL/100 g of maize) than maize with high irrigation (45.92 mL/100 g of maize). Residual starch contents in the distillers dried grains with solubles were in a range of 0.80–1.02%. In conclusion, deficit irrigation had a significant effect on physical properties, chemical composition, ethanol yield, and fermentation efficiency of maize.     

森林土壤有效磷测定过程中3种脱色剂的效果比较

为选出森林土壤有效磷测定过程中最优的脱色剂,比较了无磷活性炭粉、分子量为1200万的聚丙烯酰胺以及DM301大孔树脂3种材料对5种森林土壤碳酸氢钠(pH=8.5)浸提液中的有机质进行吸附分离的效果,采用直接比色法测定了浸提液中腐殖酸的浓度.并比较了这3种材料自身的含磷量、对可溶性有机质(腐殖酸溶液)的吸附能力以及对浸提液中磷吸附性的差异.结果 表明,聚丙烯酰胺对配制的腐殖酸溶液吸附效果最佳,滤液呈无色透明状,而无磷活性炭对土壤浸提液的有机质去除效果最好,大孔树脂吸附效果最差.因此,在森林土壤有效磷的测定过程中,无磷活性炭是最佳的选择.     

紫外分光光度法测定生鲜乳中动物水解蛋白L-羟脯氨酸含量

采用紫外分光光度法测定生鲜乳中动物水解蛋白L-羟脯氨酸含量,结果表明,L-羟脯氨酸在0.00～1.11μg/ml范围内具有良好的线性关系(r=0.999 0,)在100～300μg/ml范围内平均回收率为98.7%,RSD=6.3%,因此,该法可用于生鲜乳中动物水解蛋白的鉴定,即L-羟脯氨酸的测定。     

氧化性杀菌剂对鲜切马蹄护色和杀菌效果的研究

采用不同浓度和pH值的NaClO和ClO2对鲜切马蹄进行处理,通过测定色泽和细菌总数来评价处理效果。研究结果表明,ClO2对鲜切马蹄的护色效果好于NaClO;不同浓度和pH值的ClO2对马蹄的处理效果也不一样,浓度为35 mg/kg、pH值6.0条件下整体作用效果较好;NaClO浓度为100 mg/kg、pH值6.0对马蹄的整体作用效果较好。     

岩土覆被格局对西南喀斯特坡地产流产沙的影响

为研究不同岩土格局对喀斯特坡地水土流失/漏失的影响,利用人工模拟降雨试验,以裸坡为对照组,研究镶嵌格局、横坡格局、顺坡格局3种岩土覆被格局下的坡面产流产沙特征。结果表明：(1)顺坡格局的地表产流量最多,分别较镶嵌格局、横坡格局与裸坡的地表产流量增加88.6%,67.1%,576.1%,同时顺坡格局的地下产流量最少,分别较镶嵌格局、横坡格局与裸坡减少37.5%,36.1%,39.2%。(2)地表产沙量顺坡格局>镶嵌格局>横坡格局>裸坡,地下产沙量镶嵌格局>横坡格局>顺坡格局>裸坡。3种岩土格局的地表产沙量较裸坡均有明显增加,但地下产沙量相对增加较少。(3)岩土格局可改变地表径流泥沙关系,地表累积径流量与地表累积产沙量呈幂函数关系,镶嵌格局明显改变地表径流泥沙关系,使坡面地表侵蚀量显著提升。研究结果可进一步深化对喀斯特坡地降雨侵蚀规律的认识,为喀斯特地区的石漠化治理提供参考依据。     

喀斯特峰丛洼地坡地橘园与梯田橘园土壤水分变化特征

为探明喀斯特坡地改为梯田后土壤水分的变化特征,以典型喀斯特坡地橘园和梯田橘园为研究对象,对不同深度土层(0—70 cm)土壤含水量进行1年 (376天)的连续监测。结果表明:(1)梯田橘园平均土壤含水量(32.64%)与坡地橘园(33.05%)差异很小,梯田橘园表层(0—10 cm)土壤含水量(43.35%)显著高于坡地橘园(34.24%),两者土壤水分均呈现旱季变化相对平缓、雨季波动较为剧烈的变化规律,梯田橘园表层土壤含水量与下层有明显差异,而坡地橘园各土层土壤含水量差异较小。(2)不同雨量的降雨事件中,梯田橘园各土层含水量总体增长幅度较坡地橘园大;停雨后24 h内,梯田橘园表层土壤含水量的衰退速度较坡地橘园慢,但停雨后1周内,梯田橘园各土层含水量衰退速度总体较坡地橘园快。(3)梯田橘园与坡地橘园的平均相对可利用水分分别为0.37与0.38,与非喀斯特地区相比,梯田在喀斯特峰丛洼地的保水效果相对不明显。研究结果可为定量评价喀斯特地区坡改梯措施的保水效益提供一定的科学依据。     

Expression of Survivin,Bcl‐2 and Bax Proteins in the Domestic Cat (Felis catus) Endometrium During the Oestrus Cycle

Apoptosis has been shown to be an important regulator of endometrium function. To clarify the regulation of apoptosis in the cat endometrium during the normal oestrus cycle, the expressions of the apoptosis‐related proteins (Bcl‐2 and Bax) and their correlation to the inhibitor of apoptosis protein Survivin were analysed using immunohistochemistry. The TUNEL technique (TdT‐mediated dUTP nick end labelling) was also used to detect DNA fragmentation characteristic of apoptotic cells. The results demonstrated that TUNEL labelling is not effective for the detection of apoptosis in cat endometrium. Survivin was expressed in the luminal and glandular epithelial cells of cat endometrium during all phases of the oestrus cycle. Survivin was localized in both the cytoplasm and nuclei of superficial and deep uterine gland cells during the luteal phase, while only cytoplasmic staining was observed during the follicular and anoestrus phases. Bax immunoreactivity in the cytoplasm of luminal and glandular epithelial cells as well as the smooth muscle cells of blood vessels was weak in the anoestrus phase. Compared with anoestrus, the intensity of Bax immunostaining was moderate in the follicular phase and increased dramatically in the luteal phase. Bcl‐2 immunostaining in the cytoplasm of luminal and glandular epithelial cells was moderate in the anoestrus phase. During the early follicular phase, cytoplasmic Bcl‐2 immunostaining was detected mostly in glandular epithelial cells. In the mid‐follicular phase, in glands, the amount of Bcl‐2 protein increased progressively from the superficial to the deep layer. In contrast, the expression of Bcl‐2 decreased in the secretory phase, being very low or absent in the mid‐ and late luteal phases. The overall results suggest that Survivin, Bax and Bcl‐2 proteins may cooperatively contribute to cell apoptosis and cell proliferation in the cat uterus during the oestrus cycle.     

The Prenatal Development and Histochemistry of the Ileal Mucins in the Bovine Fetuses

Few studies exist regarding the distribution of intestinal mucins in fetuses of mammalians such as cattle and sheep. In this study, we aimed to describe the changes in the mucin production by ileal epithelium of bovine fetuses during their prenatal development. The goblet cells showed heterogeneity in mucins and the apical cytoplasm of the enterocytes demonstrated Periodic acid Schiff‐positive reaction which declined gradually towards the birth. Moreover, the number of the goblet cells containing acidic and mixed mucins augmented, whereas those containing neutral mucins decreased with advancing gestational age. After sixth month of gestation, with the initiation of the ileal Peyer patches and follicle‐associated epithelium development, a gradual increase in the number of goblet cells containing sulfomucins was also noticed towards the birth. The presence of different mucins in the ileum of bovine fetuses throughout prenatal development might play a role in the protection of the intestinal mucosa against urinary waste products in swallowed amniotic fluid and bile. Furthermore, mucins can also contribute for the formation of meconium in intra‐uterine life and building of strong intestinal barrier with predominating sulfomucins, protecting the intestine against potential pathogens and digestive enzymes after birth.