979 resultados para Scipio Aemilianus, P. C., Africauns Minor.


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Some novel macrocyclic (arylene ether sulfone) containing cardo groups and (arylene ether ketone sulfone) oligomers have been synthesized in high yields by a nucleophilic aromatic substitution reaction of 4,4'-difluorophenylsulfone with bisphenols in the presence of anhydrous potassium carbonate under a pseudo-high-dilution condition. Detailed structural characterization of these oligomers by matrix-assisted laser desorption/ionization-time of flight-mass spectrometry (MALDI-TOF-MS), fast atom bombardment mass spectrometry (f.a.b.-m.s.), nuclear magnetic resonance spectrometry (n.m.r.) and single-crystal X-ray structure analysis confirms their cyclic nature, and the composition of the oligomeric mixtures is provided by g.p.c. analysis. Ring polymerization of cyclic oligomers 3a to a high molecular weight polymer with M-w of 59.1 k was achieved by heating at 290 degrees C for 40 min in the presence of a nucleophilic initiator. (C) 1998 Elsevier Science Ltd. All rights reserved.

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为揭示渤海沉积物中氮的生物地球化学循环过程,本文应用自然粒度下的分级分离浸取方法首次对渤海沉积物中氮的形态进行了研究,获得了氮形态分布的地球化学特征;将沉积物氮中可转化和非转化部分定量区别开,并对可转化态中各形态氮对其循环贡献的大小进行了评估;结合底栖生物的分布初步探计了沉积物中氮与生物生产的关系及底栖生物对氮循环的影响。得到的主要结论包括:渤海沉积物中氮的形态分布特征及其控制因素。表层沉积物中IEF-N、CF-N、IMOF-N和OSF-N占TN的比例分别为3.67%,0.31%,0.42%和26.45%,OSF-N是可转化态氮的优势形态。IEF-N 中NH_4~+和NO_3~-具有不同的成岩机制:NH_2~+主要受OC、Es和粘土矿物性质影响,NO_3~-与水体分布密切相关。CF-N含量最小,主要受沉积环境pH值的影响。IMOF-N主要由NH_4~+在Fe~(3+)上的吸附形成,受沉积物的氧化还原环境控制。OSF-N除与物质来源有关外,受到粘土矿物性质及沉积物粒度的影响。Fe、Mn和Co对IEF-N和IMOF-N的成岩作用影响明显,Cu、Pb和Mo对OSF-N的分布产生影响,二者作用的机理不同。表层样中,约69.15%的氮经过早期成岩作用而埋藏,短期内不再参与循环。氮的埋藏通量与沉积物聚积速率呈显著正相关,同时受温度、Eh、OC、盐度、硫化物含量等因素影响。沉积物中C/N和N/P呈现异常的低值,前者主要是由于沉积物中保留了大量的无机氮,后者主要因为陆地排放大量磷入海以及磷的埋藏效率高于氮所致。柱状样中,IEF-N基本随深度减小,IMOF-N随深度有突变现象,OSF-N随深度的变化表明了矿化作用进行的程度。对沉积物中生源要素分解速率常数有:N>P>C>Si。表层沉积物中可转化态氮占总氮的比例高于深层沉积物。OC/ON随深度减小表明沉积物通过某种机制富集了有机氮。各形态氮在氮循环中作用及渤海氮循环收支。对渤海沉积物中可转化态氮的量进行了估算,IEF-N、CF-N、IMOF-N和OSF-N分别为3.657 * 10~8kg,2.794 * 10~7 kg,3.832 * 10~7kg和2.372平共处* 10~9kg;结合室内模拟的氮的界面交换通量,估算其完全释放所需的时间分别为2.15a,0.16a,0.225a和13.94a。各形态氮释放的顺序与其结合牢固程度一致,即IEF-N>CF-N >IMOF-N>OSF-N,其对界面交换的贡献大小则随时间尺度大小发生变化:随时间尺度增加,IEF-N、CF-N、IMOF-N的贡献逐渐减小,OSF-N的贡献逐渐增大,当时间尺度大到足以使四态氮完全释放时,其贡献的大小与各形态氮的量一致即OSF-N(84.6%)>IEF-N(13.0%)>IMOF-N(1.4%)>CF-N(1.0%)。非转化态氮占总氮的 69.15%,其中由于颗粒物包裹导致的“非转化态”氮为49%,说明粒度的影响非常重要。IEF-N和OSF-N主要存在于颗粒物质外层,是循环的主要参与者,CF-N和IMOF-N绝大部分在内层,对循环的贡献很小。水体中再循环的氮对初级生产力的贡献(74.4%)比沉积物中再循环氮的贡献 (26.1)大得多,二者对生态系统的作用不同,水体再生的营养盐通常在较长的时间尺度上维持初级生产力的平衡,而沉积物中的再生则在很短的时间内通过强烈的混合作用提高初级生产力。沉积物中氮与生物生产的关系及底栖生物对沉积物氮循环的影响。IEF-N和OSF-N的分布均与初级生产力以及浮游植物个体数量的分布具有一定的相似性。沉积物中的IEF-N的作用相当于一个氮营养盐的“储存库”对初级生产力产生影响,其作用机制类似于水体富营养化的正反馈机制。IEF-N能对赤潮的发生起加速作用。底栖生物的分布与氮形态分布具有正的相关性:莱洲湾内IEF-N和OSF-N的分布与该区域高生物量和高密度的大型底栖动物分布一致,说明在底栖生物活动活跃的区域营养盐的再生和流动是高效而迅速的。生物扰动能加速矿化作用的进行,使沉积物在一定深度范围内NH_4~+含量增加,大型底栖动物的灌溉作用使NO_3~-在深层仍有较高的分布。底栖生物的不同种群对营养盐变化的响应不同。

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目前在尚不能测定天然海水中浮游植物营养盐含量及组分的情况下,通过室内培养,测定浮游植物细胞中营养盐含量及其组分,探讨天然海水中浮游植物营养盐结构特征。本论文通过对不同大小浮游植物主要优势种的C、N、PSi含量及组成的测定,结合现场调查海水营养盐、粒级叶绿素a数据及历史资料,探讨了不同水域、不同大小、不同季节浮游植物培养后营养盐结构的差异,主要结论如下: 胶州湾表层营养盐与叶绿素a浓度平面分布一致,呈现自西北、东北部向中、南部及湾外递减的趋势。与粒级叶绿素a季节变化相反,表层营养盐浓度春、秋季较高,冬、夏季较低。 自营养盐丰富的长江口水域取得的藻种,培养后细胞中除N含量接近外,C、PSi含量高于胶州湾,Si含量的差异尤为明显。胶州湾不同大小浮游植物细胞中C、N、PSi的含量一般随粒级的增大而增加,C、N、P细胞中所占比例亦是如此,但Si所占比例基本一致;粒级较小的中肋骨条藻更容易吸收Si,而粒级较大的旋链角毛藻和诺氏海链藻更容易吸收N和P与海水营养盐浓度类似,培养后浮游植物C、N、PSi的含量及干质量浓度亦表现出季节差异;冬季中肋骨条藻培养后细胞中C、N、PSi的含量较高,春季较低。室内培养浮游植物N/PC/N比值与颗粒物接近,Si/PSi/N比值小于颗粒物。培养后胶州湾浮游植物细胞高C、N含量,低PSi含量和高N/P(远高于16),低Si/P、Si/N比(远低于16,1),与海水和颗粒物中营养盐结构基本相似,说明Si可能是胶州湾浮游植物生长潜在的限制因子。

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本文对我国胶州湾养殖的主要滤食性贝类菲律宾蛤仔的生理生态学进行了系统研究,通过资料收集、现场调查、定点连续观测、现场模拟实验等综合性方法探讨了菲律宾蛤仔养殖对胶州湾生态环境的影响。主要系统调查了不同季节胶州湾自然沉积物中C、N和P变化;研究了菲律宾蛤仔生物沉积作用的周年变化;同时还研究了不同月份菲律宾蛤仔的耗氧率,排泄率的变化。结果如下: 1、综述了滤食性贝类通过滤食、生物沉积和呼吸排泄等作用对海区环境的影响,系统评述了埋栖性贝类生物沉积的测定方法及其生态效应。国际上已有不少研究专门报道了贝类在海区现场的生物沉积作用,而在我国,关于埋栖性贝类生物沉积特征的研究较少。 2、在胶州湾红岛附近养殖海区,从2003年10月到2004年7月以及2005年8月到2005年12月对菲律宾蛤仔生物沉积进行了现场测定。大、中和小规格菲律宾蛤仔生物沉积速率范围分别为121.6~1527.4mg/ind·d,49.5~902.1mg/ind·d,14.2~653.9mg/ind·d。海底自然沉积物OM分别为3.1%和5.7±1.1%。而大、中和小规格菲律宾蛤仔生物沉积物的OM分别为6.2±1.2%、5.9±1.3%和6.1±1.4%。大、中和小菲律宾蛤仔生物沉积物TP量分别为399±26ppm,372±16ppm,345±15ppm。大、中和小规格蛤子生物沉积物中的OP别为80±17ppm,92±12ppm和102±10ppm,明显高于对照沉积物的OP生物沉积物中的OP/TP明显高于对照沉积物,前者为23~25%,而后者仅为20%。菲律宾蛤仔生物沉积速率呈明显季节性变化,其与软体干重呈异速方程关系,a值的变化范围为0.85~4.50(平均为2.32)。菲律宾蛤仔贝肉的OC和ON含量分别为40.80±7.59%和的10.26±2.19%。贝壳的OM、TPOPOC和ON含量分别为3.28±0.47%、109.2±16.6ppm、64±22.9ppm、12.21±0.30%和0.19±0.05%。 3、不同规格菲律宾蛤仔的代谢率呈明显季节变化。7月份,单位个体菲律宾蛤仔耗氧率最高为1.72 g/ind•h;8月份,排氨率和排磷率达到最高,分别为2.44μmol/ind•h、0.58μmol/ind•h。菲律宾蛤仔的O:N在10.7~31.9范围内,O:N和N:P有明显的季节变化,8月份最大。 4、研究了本湾底质环境特征,测定了自然沉积物的OM、OC、ON、TPOP含量。胶州湾站位沉积物的有机质和C、N、P量季节变化不大,有机质含量大约为3.5%,OC和ON含量大约为0.7%和0.06%。TP量为285ppm左右,OP量大约为50ppm。养殖海区沉积物有机质和C、N、P含量明显高于非养殖海区沉积物含量,其C/N、C/OPOP/TP般也比非养殖海区站位高。 夏季,胶州湾菲律宾蛤仔养殖区(平均密度按600ind/m2计算)单位面积(m2)的生物沉积速率平均为176g/m2•d,对于整个海湾,将有1.2万吨的悬浮颗粒物通过贝类排粪作用沉积到海底。通过菲律宾蛤仔的呼吸作用,单位面积(m2)的耗氧量为6.67gO2/m2•d;同时从海底向水体释放大约为16.7μmolN /m2•d和3.3μmolP/m2•d的溶解态N和P对于整个海湾,菲律宾蛤仔将耗掉水体中的467T/d氧气,同时向水体中释放16.4T/d氨氮和7.2T/d无机磷。对于半封闭的胶州湾,大规模菲律宾蛤仔的滩涂养殖其产生的生物沉积物聚集于海底可能会对海区底部的物理化学和生物环境产生很大影响;而氧的消耗、氨和无机磷的排泄,会对水层中的物理化学环境和营养盐循环产生很大影响。从而由此推测,菲律宾蛤仔高密度大规模的养殖,在整个胶州湾水层-底栖系统耦合作用中可能起着很重要的作用。

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对虾养殖业的可持续发展面临着种质退化、病害严重和养殖环境恶化等问题的严重挑战。养殖环境恶化造成的环境胁迫,不但影响对虾的生长性状,而且导致对虾的抵抗力下降,更容易引发病害的发生。养殖环境恶化已经严重影响了对虾养殖业的健康可持续发展。本论文针对环境恶化造成的环境胁迫对对虾影响的分子机理进行了研究。 克隆了中国明对虾对环境胁迫应答的重要伴侣蛋白基因,包括钙网蛋白(FcCRT)、葡萄糖调节蛋白78 (FcGrp78)、热休克蛋白70(FcHsp70)和热休克蛋白90(FcHsp90)的全长cDNA,研究了这些基因的组织表达特征,并对这些基因在不同胁迫条件下的转录表达特征进行了分析。 钙网蛋白是一种多功能的内质网钙结合蛋白,负责蛋白折叠和糖蛋白修饰。本论文首次在中国明对虾报道了钙网蛋白FcCRT基因的全长cDNA序列,编码406个氨基酸,具有保守的N-,P-和C-功能域,以及信号肽和保守的HDEL内质网回收标签。FcCRT基因与其它物种的钙网蛋白具有高度的相似性,系统进化分析表明,FcCRT在亲缘关系上更接近昆虫的钙网蛋白。Northern blot和原位杂交结果显示,FcCRT基因在中国明对虾各组织中均有表达,且在卵巢中发育早起的卵母细胞中表达量最高,说明FcCRT很可能参与了卵母细胞的成熟。FcCRT基因在不同胁迫条件下,其转录表达均呈现明显的变化。在WSSV感染实验中,中国明对虾肝胰脏和淋巴器官中FcCRT转录表达均明显上调;热休克、重金属处理均可引起FcCRT基因转录表达的变化,但不同重金属处理引起FcCRT转录表达变化的模式不同。铜离子处理6小时,会引起FcCRT基因的下调表达,但在12小时之后出现明显上调;镉离子处理12小时后引起FcCRT基因的下调表达,但在24小时又出现明显的上调表达。 葡萄糖调节蛋白78(GRP78)是内质网重要的伴侣蛋白。中国明对虾的Grp78基因(FcGrp78)的cDNA全长为2325bp编码665个氨基酸。FcGrp78具有三个Hsp70蛋白家族标签,并含有KDEL内质网回收标签。FcGrp78基因与中国明对虾已有的Hsc70和Hsp70具有高度相似性。Northern blot杂交结果显示FcGrp78基因在中国明对虾各组织中均有表达。FcGrp78基因在WSSV感染的中国明对虾肝胰脏中呈上调表达,在血细胞中下调表达,说明FcGrp78可能与对虾的免疫应答有关。热休克处理会诱导FcGrp78基因转录的上调。不同重金属离子胁迫引起的FcGrp78转录表达有所不同:铜离子处理可以诱导FcGrp78基因在处理后24小时的上调表达;镉离子的处理导致FcGrp78基因处理后12小时的下调以及处理后24小时的上调表达变化。短期低氧胁迫则抑制对虾FcGrp78基因的转录表达。 本论文报道的中国明对虾FcHsp90基因 cDNA全长2552bp编码726个氨基酸,具有保守的N端功能域、中间功能域和C端功能域,具有五个保守的Hsp90蛋白家族标签,序列上与其他物种Hsp90相似性高。Real-time RT-PCR结果显示FcHsp90基因在发育的卵巢中表达量较高,说明Hsp90可能参与了对虾卵母细胞成熟过程中的蛋白合成和卵黄蛋白原的分泌。WSSV感染引起中国明对虾肝胰脏的FcHsp90的转录表达明显上调,说明FcHsp90很可能与对虾的免疫相关。热休克处理诱导FcHsp90基因转录表达的迅速上调。铜离子处理也可诱导FcHsp90基因转录的上调表达,而镉离子处理首先引起FcHsp90基因的下调表达,24小时后开始上调。低氧胁迫也会抑制FcHsp90基因在对虾体内的转录表达。 诱导型FcHsp70基因cDNA全长2511bp编码629个氨基酸,具有三个保守的Hsp70蛋白家族标签和C末端EEVD序列。与其他物种的Hsp70蛋白具有高度的相似性。FcHsp70基因转录表达对于热休克处理和铜离子的处理非常敏感:热休克处理2小时后FcHsp70基因的转录水平是对照组的80倍;铜离子处理12小时FcHsp70基因转录表达达到对照组的15倍。而镉离子处理后没有诱导FcHsp70显著的上调表达。 以上研究结果为阐明对虾对环境胁迫应答的机制奠定了重要基础,并可为抗逆对虾的培育提供依据。

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The concentration of suspended particulate matter (SPM), sedimentation flux, and various forms of phosphorus and silica in turbidity maximum zone (TMZ) in the Changjiang (Yangtze) estuary was studied. Based on the budget of P and Si, their mass balances in the TMZ were calculated. Results show that the variation in concentration of dissolved inorganic silicon (DISi) was mainly controlled by seawater dilution, while that of dissolved inorganic phosphor-us (DIP) was considerably affected by the buffering of suspended matter and sediment. Our experiments showed that the sedimentation fluxes of SPM and particulate inorganic phosphorus (PIP), total particulate phosphorus (TPP), particulate inorganic silicon (PISi), and biological silicon (BSi) in the TMZ were 238.4 g m(-2) d(-1) and 28.3, 43.1, 79.0, 63.0 mg m(-2) d(-1), respectively. In addition, a simple method to estimate the ratio of resuspension of sediment in the TMZ was established, with which the rate in surface and bottom waters of the TMZ accounted for 55.7 and 66.1% of the total SPM, respectively, indicating that the sediment resuspension in the TMZ influenced significantly the mass balances of P and Si. Particulate adsorbed P (60.8%) and 35.5% of total particulate P discharged from the river were filtered and then deposited in the TMZ. The input flux of PIP from the river mouth was 55.9% of that of DIP, being important as biologically available P, while that of PISi was only 3.5% of DISi, showing that particulate adsorbed Si was much less important than particulate adsorbed P. (c) 2008 Elsevier Ltd. All rights reserved.

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A capillary electrophoresis (CE) method has been developed for the determination of six bioactive flavonoids that are commonly found in health foods: hesperidin, hyperin, isorhamnetin, kaempferol, quercetin and rutin. The effects of several parameters, such as pH, buffer concentration, separation voltage and UV detector wavelength, were investigated to find the optimal conditions. Using a HbBCh-NaiB-iO? buffer (pH 9.2), the analytes can be separated within 8 min. The relative standard deviations of migration times in eight injections were between 0.77% and 0.93%, and those of the peak areas ranged from 3.8% to 8.6%. A high reproducibility and excellent linearity was observed over two orders of magnitude, with detection limits (S/N = 3) ranging from 0.34ug ml to 2.9ug ml for all the six analytes. Recoveries ranged from 80.4 % to 113.9 %. The new method is simple, reproducible and sensitive. No solid phase extraction for sample pretreatment is necessary. Analysis results are accurate in application to bee pollens.

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Visando ao desenvolvimento sustentável da cadeia produtiva da carne brasileira, sistemas de identificação, gerenciamento e rastreamento dos rebanhos vêm sendo desenvolvidos pela Embrapa Gado de Corte com a finalidade de oferecer aos produtores e mercado consumidor ferramentas que garantam a certificação do produto final.

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2009

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2009

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Introdução; Características do gênero Listeria; Listeriose; Patogenicidade e genes de virulência de L. monocytogenes; Métodos de subtipagem de L. monocytogenes; Ocorrência de L. monocytogenes em queijos e indústrias de laticínios; Surtos de listeriose associados ao consumo de leite e produtos lácteos; Considerações finais.

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O sistema de avaliação de impacto social da inovação tecnológica agropecuária (Ambitec- Social) consiste de um conjunto de planilhas eletrônicas que integram quatorze indicadores da contribuição de uma dada inovação tecnológica agropecuária para o bem estar social, no âmbito de um estabelecimento rural. Quatro aspectos essenciais de avaliação são considerados: i. Emprego, ii. Renda, iii. Saúde, e iv. Gestão e Administração. Os indicadores são construídos em matrizes de ponderação nas quais dados obtidos em campo, de acordo com o conhecimento do produtor/administrador do estabelecimento, são automaticamente transformados em índices de impacto expressos graficamente. Os resultados da avaliação permitem, ao produtor/administrador, averiguar quais impactos da tecnologia podem estar desconformes com seus objetivos de bem estar social; ao tomador de decisões a indicação de medidas de fomento ou controle da adoção da tecnologia, segundo planos de desenvolvimento local sustentável e finalmente, proporcionam uma unidade de medida objetiva de impacto, auxiliando na qualificação, seleção e transferência de tecnologias agropecuárias.

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O sistema de avaliação de impacto ambiental da inovação tecnológica agropecuária (AMBITEC-AGRO) apresentado neste trabalho compe-se de quatro aspectos de caracterização do impacto ambiental, expressos por oito indicadores e trinta e seis componentes, todos integrados em matrizes de ponderação formuladas em planilhas eletrônicas automatizadas. Cada componente é avaliado a campo em uma entrevista/vistoria aplicada pelo usuário do sistema a um conjunto de produtores/responsáveis pela atividade à qual aplica-se a inovação tecnológica. O produtor expressa seu conhecimento sobre o coeficiente de alteração do componente devido à influência da tecnologia avaliada sobre a atividade. Este coeficiente de alteração é então ponderado segundo a escala da ocorrência e o peso do componente para formação do indicador de impacto ambiental e os resultados das avaliações dos indicadores são expressos graficamente nas planilhas. Finalmente, os resultados dos indicadores são ponderados pelo peso dos indicadores para composição do índice de impacto ambiental (Índice I.A.) da inovação tecnológica agropecuária.