Impact of exclosures on wood biomass production and fuelwood supply in northern Ethiopia

In the Ethiopian highlands, communal grazing lands are one of the major land uses, and are source of livelihood for the rural people. Free and uncontrolled grazing in the communal grazing lands is the dominant grazing system. The traditional uncontrolled and free grazing system has caused severe degradation of the grazing lands. As a result, communities have started to establish exclosures and support the restoration of degraded communal grazing lands. Studies have shown that exclosures are effective to restoring degraded communal grazing lands and improving ecosystem services. However, studies that investigate the changes in aboveground biomass following the establishment of exclosures and compare it with fuelwood demand of the beneficiaries in our study area is lacking. Therefore, our study aimed at:(1) quantifying yearly biomass accumulation in exclosures and compare it to fuelwood demand of households that manage the exclosures;(2) assessing household energy sources and their consumption levels. To monitor changes in biomass production with over time, replicated(n = 3) 5 and10 year-old exclosures were sampled. To investigate fuelwood sources and consumption patterns, household surveys, key informant interviews and focus group discussion were conducted. Our results demonstrated that total biomass production increased with exclosure age. In both exclosure, biomass production from Vachellia etbaica was significantly(p \ 0.05) greater than that from Euclea.racemosa. Average daily fuelwood consumption per person was(0.63 ± 0.2) kg day^-1. This means that the total biomass(27.5 Mg year^-1) obtained from 114.6 ha of exclosures covers only 9.4% of yearly fuelwood demand of the residents who manage the sampled exclosures. Nearly all respondents(95%) confirmed that they travel more than10 km day^-1 to gather fuelwood from surrounding degraded forest patches. We recommend plantings of fast growing native tree species within exclosures and around homesteads to provide a sustainable fuelwood supply and using improved stoves to address the problem of fuelwood shortage. District agricultural offices could provide seedlings of native plant species, while communities provide unpaid labour for planting and managing plantations.     

果蔬清洗废水中乐果农药扫频超声波降解工艺优化

采用平板扫频超声波技术进行果蔬清洗废水中乐果农药降解研究,研究了超声波频率、定/扫频模式、处理体积、处理时间以及频率组合对水溶液中低浓度农药乐果降解的影响,探讨超声处理的自由基作用机理.结果表明,平板扫频模式超声波对乐果的降解效果优于定频模式,双板对振的效果优于单板超声.超声波降解处理系统较好的工作参数为:频率68 kHz、功率80 W(对应的处理体积为8L)、扫频周期100 ms、频率组合68 kHz与68 kHz,初始质量浓度为3 mg/L的乐果溶液180 min降解率达到71％.利用超声波处理乐果溶液,存在因超声波超声的自由基引起降解的因素.     

醋糟厌氧发酵制氢的影响因素研究

以预处理后的牛粪为接种物,以醋糟为发酵底物进行厌氧发酵产氢试验,研究了底物预处理方法、发酵温度、底物浓度、初始pH值、微量金属元素添加量对产氢量的影响。结果表明,用体积分数0.7%的HCl静置处理24h为最佳预处理方法,且在最佳发酵条件(发酵温度35℃,底物浓度175g/L,初始pH值6.0)下,微量金属元素营养液添加量为2%时,产氢效果最好,累积产氢量为46.91mL/gTS。     

交替双频逆流超声辅助提取条斑紫菜蛋白和多糖

为了高值化利用条斑紫菜资源,该文采用交替双频逆流超声辅助提取技术生产条斑紫菜蛋白和多糖混合产品。研究了复合双频和交替双频2种超声模式对条斑紫菜蛋白和多糖提取效果的影响,采用中心组合设计响应面优化试验进行工艺优化。结果显示,交替双频超声模式显著优于复合双频超声模式。料液比、提取时间和温度均对提取效果影响显著。确定的交替双频逆流超声辅助提取的最优条件为:料液比14mg/mL、时间88min、温度41℃、pH值9.0、15和20kHz交替双频超声、超声交替工作时间3s、超声功率200W/L。在此最优条件下,条斑紫菜蛋白和多糖混合产品的生产能力最高,单位质量原料生产出的产品得率为(48.180.08)%,其中蛋白得率为(24.350.07)%,纯度为(45.610.33)%,多糖得率为(23.830.02)%,纯度为(44.640.37)%,比传统提取方法,得率提高了168%,时间缩短了64%;比单频逆流超声辅助提取方法,得率提高了50%,时间缩短了18%。从生产成本分析,交替双频逆流超声辅助提取方法具有明显技术优势和工业推广价值。     

条斑紫菜多糖超声提取及其对U937细胞生长抑制影响的研究

采用超声辅助提取技术进行条斑紫菜多糖的提取,并进行柱层析纯化。经正交试验确定的条斑紫菜粗多糖提取的最佳工艺条件为：15 g干紫菜粉加入2 L水,提取液循环转速为12 r/s,提取液温度为40℃,超声功率为800 W,超声处理时间/超声间隙为3 s/2 s和超声全程时间为2 h,对应的得率为26.29%。粗多糖分别经50%、60%、70%和80%乙醇分步醇沉,沉淀出四种不同级分的半纯品,用DEAE-52纤维素和Sephadex G-200将其中两种多糖半纯品纯化,分别得到5个和3个不同分子量的级分,分别考察了这两种紫菜多糖半纯品及各自分级产物对人血癌细胞U937细胞的体外生长抑制的抗肿瘤试验,结果前者及其分级产物对U937细胞生长有一定的抑制作用,后者及其分级产物则有一定的促进作用。     

The effect of rainfall on spatio‐temporal variability in cropping systems and duration of crop cover in the Northern Ethiopian Highlands

In the Northern Ethiopian Highlands, ca. 33% of the land is cropland, which is mainly cultivated by smallholders who based on indigenous knowledge plan their cropping system on the basis of spatio‐temporal variability in rainfall. To understand the relationships between rainfall variability and cropping systems, a field campaign was undertaken in the rainy season of 2009 when 118 farmers were interviewed at different locations with different environmental characteristics. Five cropping systems were identified, each having a distinct cropping season length and crop association. Cropping systems with shorter cropping seasons were generally on the valleysides, whereas longer cycles occurred in the valley bottoms. The length of cropping season also increased from north–northeast to south–southwest. Crop associations within cropping systems also varied with altitude. Cropping systems changed in response to variation in annual rainfall. This resulted in shifts of cropping systems at catchment and regional scales, with cropping systems having longer cropping seasons where there was greater annual precipitation. The results were scaled up to the whole region by modelling the spatial distribution of cropping systems at a 8 × 8 km² resolution over the period 1996–2009. The results indicate that indigenous knowledge is important when assessing the impact of climatic variability on agricultural production and that large inter‐annual variability in the duration of crop cover in Northern Ethiopia might be an important, although generally overlooked, explanatory factor for explaining previous land degradation cycles.     

Meaning in Architecture and Landscape Architecture: Enhancement of Contemporary Design Practices Based on the Review of Postmodernism and Surrealism Aesthetic Philosophies

The study explored surrealist aesthetic philosophies in relation with referential postmodern architecture,and landscape architecture,to communicate meaning with the audience.These philosophies provide lessons about the potential of the built environment to address the emotional and psychological needs of the public,that is,to address the vital social,ecological,and functional needs of modern society.According to this,the purpose of the study was two-fold.The first is to analyze the visual techniques and forms that are used in referential postmodern architecture and landscape architecture in relation with surrealist aesthetic philosophies,to communicate meaning with the audience.Second is to demonstrate the relevance of these visual theories,to enhance contemporary design practices.The study emphasized the potential of art forms that provide meaning to address the physiological and spiritual needs of the society.Hence,it re-established landscape architecture as an art form capable of enriching human psychological and spiritual well-being,which is opposed to the conservative utilitarian natures of the field.     

荷叶活性物质提取工艺与抗氧化活性研究

对荷叶活性物质提取工艺与抗氧化活性进行了研究.结果表明,荷叶抗氧化活性物质最佳提取工艺为提取时间50 min、提取温度80℃、乙醇体积分数60%和料液比1:20;采用生物活性追踪法研究发现,在极性依次增大的正己烷、乙酸乙酯、正丁醇和水相4个极性萃取组分中,乙酸乙酯萃取组分抗氧化活性(总还原力、FRAP法抗氧化能力和DPPH自由基清除能力)最强并具有显著性差异(P<0.001或P<0.01);通过验证试验发现该组分抗氧化能力(OD593和DPPH自由基清除率)均显著高于阳性对照BHT和GBE(P<0.05).     

采用MECC在线堆积同步检测茶叶中七种残留农药

为解决茶叶中的痕量农药残留的快速检测问题,建立了一种基于胶束毛细管电泳在线堆积技术的茶叶中7种拟除虫菊酯类农药痕量残留的一次进样同步检测方法.通过参数优化,得到最优的柱上在线堆积浓缩操作工艺:以15%异丙醇、20%乙腈、60 mmol/L十二烷基硫酸钠(SDS)和50 mmol/L tris的混合物为背景缓冲溶液(BGS).茶叶的浸提液经过固相萃取净化吹干后,用1 mmol.L SDS溶解溶液残渣.进样100 s后施加反向电压,进行农药反向在线堆积,当电流恢复至正常分离时的95%时改变电压方向,进行正常分离.经过在线堆积浓缩,7种拟除虫菊酯类农药痕量残留堆积因子均高于17,回收率在82%以上,检测下限分别达到:功夫菊酯0.05 mg/kg、联苯菊酯0.05 mg/kg、百树菊酯0.05 mg/kg、高效氯氰菊酯0.05 mg/kg、溴氰菊酯0.2 mg/kg、二氯菊酯0.05 mg/kg、氰戊菊酯0.05 mg/kg,满足了2006年欧盟茶叶中拟除虫菊酯类农药残留的最低标准.     

酶法制备大米抗氧化肽的蛋白酶筛选

通过酶法制备进行大米抗氧化肽蛋白酶的筛选。以大米蛋白为原料、酶解液对DPPH自由基清除率为指标,从风味蛋白酶、中性蛋白酶、胰蛋白酶、复合蛋白酶、碱性蛋白酶、木瓜蛋白酶和胃蛋白酶等7种蛋白酶中,筛选出中性蛋白酶为最佳用酶。通过试验得出最佳的酶解反应条件为：底物质量浓度1.0 g/(100mL)、加酶量8%、pH值6.0、温度60℃、酶解时间30min。酶解液稀释15倍对DPPH自由基的清除率为89.45%,酶解液清除