两种干燥方式对香椿粉品质特性的影响

以香椿为原料,研究真空冷冻干燥和喷雾干燥对香椿粉的物理特性、基本成分、抗氧化活性、风味物质和微观结构的影响。结果表明：真空冷冻干燥香椿粉的综合品质较好。在物理特性方面,真空冷冻干燥香椿粉的得率较高、色泽浓绿,复水性、吸油性好;而喷雾干燥香椿粉的溶解度高、堆积密度大。在基本成分方面,真空冷冻干燥香椿粉的蛋白质、皂苷、生物碱含量均高于喷雾干燥;而VC、黄酮、多糖含量在两种干燥方式的香椿粉中无显著性差异。在抗氧化活性方面,真空冷冻干燥香椿粉的DPPH自由基清除力和还原力均高于喷雾干燥。在风味物质方面,从真空冷冻干燥和喷雾干燥的香椿粉中分别鉴定出49和41种挥发性成分,且真空冷冻干燥香椿粉含有较高的特征风味物质2-巯基-3, 4-二甲基-2,3-二氢噻吩。扫描电镜观察微观结构发现真空冷冻干燥香椿粉呈现蜂窝状松散结构,而喷雾干燥香椿粉多呈现出干瘪的圆球体状。综合考虑,真空冷冻干燥是一种适合制备高品质香椿粉的干燥方式。     

退化高寒草地浅层土壤理化性质Meta分析

青藏高原生态地位显著,草地退化影响区域生态安全,针对退化高寒草地土壤理化性质的研究众多但结果存在较大异质性。通过检索纳入79篇与退化高寒草地土壤理化性质相关的文献,采用整合分析方法用于定量述评不同退化程度高寒草地浅层土壤主要理化性质的效应及变化规律。结果表明：高寒草甸0～10 cm、10～20 cm土层内随着退化加剧土壤容重、pH上升,土壤含水量、有机碳、全氮、全磷、全钾、速效氮、速效磷、速效钾下降;高寒草原0～10 cm、10～20 cm土层内随退化加剧,土壤容重上升,pH、含水量、有机碳、速效钾下降。总体反映出不同退化程度对高寒草地土壤主要理化性质产生较大负面影响,研究结果可为青藏高原高寒草地生态保护提供依据。     

不同采伐、集材方式对林地土壤理化性质影响的研究

选择５种不同集材方式的皆伐作业与采伐强度为３０％的择伐作业,进行土壤理化性质指标变化程度的比较。在考虑各种作业的集材量和集材道面积的情况下,经主成分分析得出不同采伐、集材方式对林地土壤理化性质的干扰程度。认为,以皆伐作业手扶拖拉机集材为最大,其次为皆伐作业土滑道集材,其余依次为皆伐作业半悬索道集材,皆伐作业手拉板车集材,皆伐作业全悬索道集材,最低为择伐作业人力集材。     

茂名南、北排土场生物修复中土壤性状变化的研究

广东茂名在油页岩生产过程中共产生废渣2.4×108t,堆放场占地面积8.1 km2,分别堆放在采矿场的南北两地,称为南、北排土场。通过对北排土场裸地、植林5年和南排土场植林16年、天然恢复20年的草地试验区的理化性质、土壤微生物数量及其生化活性进行对比分析,结果表明:北排裸地土壤含水差、贫瘠、酸性强;植林16年多的南排土壤理化性质、微生物、酶活性以及土壤呼吸都明显改善;但植林5年的北排土壤与裸地相差土壤性状变化不大。研究还发现,大叶相思树种对土壤改良的效果比桉树好;废渣场生物修复过程非常缓慢,必须辅以人工措施。     

Mineral Composition and Soil-Plant Relationships for Common Guava (Psidium guajava L.) and Yellow Strawberry Guava (Psidium cattleianum var. lucidum) Tree Parts and Fruits

The mineral compositions of the fruit and tree parts of common guava, Psidium guajava L., and strawberry guava, Psidium cattleianum var. lucidum, were determined. The study occurred during three seasons at six locations in Hawaii to assess guava as feed for livestock. Guava bark contained the greatest concentrations of calcium (Ca) and ash; leaves the greatest concentrations of magnesium (Mg), sulfur (S), sodium (Na), boron (B), and manganese (Mn); and the shoots had the greatest concentrations of nitrogen (N), phosphorus (P), and potassium (K). The leaves and the shoots had the greatest concentrations of copper (Cu) and iron (Fe). Between guava and waiwi, guava had greater concentrations of most minerals except for Na in all plant parts, and Mg and ash in the leaves. Guava leaves and shoots meet the macromineral requirements for various phases of sheep, goat, and beef cattle life cycles with the exception of P and Na. Guava shoots do not meet Mn requirements for lactating cows.     

Soil nitrogen and denitrification potential as affected by land use and stand age following agricultural abandonment in a headwater catchment

Changes in vegetation and soil properties because of agricultural abandonment may affect soil nitrogen (N) and associated processes. We investigated soil N (total N: TN, inorganic N: NH₄–N and NO₃–N) and denitrification potential in cropland, pine plantations and abandoned agricultural land along a secondary succession sequence (grassland→shrubland→secondary forest) in a headwater catchment in the Qinling Mountains, northwest China. The results show that the soil denitrification potential differed significantly among the five land‐use types with the highest potential in the secondary forest, followed by grassland, shrubland, cropland and plantations. The denitrification potential of the 20‐ to 40‐cm layer was significantly lower compared with the topsoil (0–20 cm) across all land‐use types. TN, soil organic matter (SOM) and NH₄–N increased significantly with stand age, whereas there was an opposite trend in soil pH. However, the denitrification potential did not relate to stand age in a linear manner. We conclude that changes in soil TN, SOM and pH during vegetation succession following agricultural abandonment are critical controls on the denitrification potential.     

不同因素对赤霞珠果实理化性质及果皮花色苷含量的影响

【目的】探究不同因素对葡萄果实理化性质及果皮中花色苷含量的影响,为改善葡萄原料品质及酿酒工艺中花色苷的浸提提供理论依据。【方法】以酿酒葡萄赤霞珠果实为原料,以未处理葡萄果粒为对照,测定温度(20,30,40℃)、pH(2.2,3.0,4.0,5.0,6.0,7.0,8.0)及脱水处理(用质量分数5%的食盐溶液分别脱水0.5,1,1.5,2,3,4,6,9,12h)对果实可溶性固形物、总酸和pH等理化性质指标及果皮花色苷(可浸提花色苷、不可浸提花色苷、总花色苷)含量的影响。【结果】(1)与对照相比,20~30℃处理48h可使葡萄果实的可溶性固形物含量增加4.12~6.52°Brix,总酸质量浓度下降0.81~1.86g/L,pH升高0.22~0.68;20~30℃处理36h果皮中的花色苷含量均较高。(2)脱水处理12h可使葡萄果实的可溶性固形物含量比对照提高14.5%,总酸质量浓度比对照提高2.76%,pH比对照降低3.64%;但果皮中可浸提花色苷含量较对照降低7.4%,不可浸提花色苷含量较对照降低2.45%,总花色苷含量较对照降低8.47%。(3)随着缓冲液pH的升高,果实可溶性固形物含量先上升后降低;不同pH处理对果实pH及总酸质量浓度影响总体较小。用pH为2.2~4.0溶液处理后,果皮可浸提花色苷和总花色苷含量均高于对照,不可浸提花色苷含量基本保持不变;用pH 5.0~8.0溶液处理后,果皮总花色苷、可浸提花色苷和不可浸提花色苷含量均呈下降趋势。【结论】20~30℃处理36h可以改善葡萄果实理化性质及提高果皮中的花色苷浸提量;脱水处理能改善果实理化性质;适当酸性溶液处理葡萄,有利于可浸提花色苷的提取。     

Influence of clay content and acidity of soil on development of the earthworm <Emphasis Type="Italic">Lumbricus rubellus</Emphasis> and its population level consequences

In this paper we report on the influence of clay content and acidity of soil on growth and reproduction of the epigeic earthworm species Lumbricus rubellus (Hoffm.), which is common in most temperate soils and abundant in grasslands. Growth, cocoon production and survival of L. rubellus were tested in 12 Dutch soils which differed in soil properties. A matrix model was used to assess the population-level consequences of changes in growth and reproduction. Soil acidity had a strong negative effect on earthworm survival, and the maturation weight decreased with clay content. Individual weight gain in L. rubellus decreased with both acidity and clay content. The acidity of soils had a larger influence on population growth rate than the clay content. The acidity of the soil also changed the population composition towards younger age classes, whereas in soils rich in clay, the population composition did not change. The average individual weight of L. rubellus in clayey soils, however, was lower compared with that in soils low in clay, a result that agrees with literature data.     

烘丝温度和时间对生丝机械性能的影响

从刚落下的丝片上摇取小绞丝,分别在25—180℃和30、60、90min下进行干热处理后,测定其机械性能。结果表明:在90—100℃、30—60分钟时,生丝的强伸力、初始模量以及抱合等机械性能都较好,烘丝温度太高,时间太长都会对生丝机械性能产生不良的影响。     

苯酚-三聚氰胺-尿素-甲醛树脂复配硼化物改性杉木的阻燃性能

采用不同固体质量分数的苯酚-三聚氰胺-尿素-甲醛(PMUF)树脂和硼酸、硼砂阻燃剂对人工林杉木进行浸渍处理,并对改性材的阻燃性能进行评价。结果表明:与素材相比,硼化物改性材的氧指数提高,热释放速率和总热释放量均大幅降低;随着树脂固体质量分数的增加,树脂改性材的氧指数呈现先升高后略下降的趋势,点燃时间延长,第一热释放速率峰值逐渐减小并且第二热释放速率峰值出现时间延迟,但总热释放量上升;复配改性材的氧指数均达到55%以上,阻燃性比树脂改性材进一步提高,热释放速率和总热释放量降低明显,残炭量增加,热稳定性提高。