963 resultados para 20 specimens, 150-250 µm
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研究了利用florisil柱净化玉米、水稻及糙米中黄曲霉毒素的最优化条件.两种粒度的florisil填充柱净化玉米均较理想,但粒度150~250μm的florisil对水稻及糙米的净化影响较大,建议选用较小粒度的florisil材料.大粒度的florisil能减小溶剂的流速,用不同的溶剂淋洗杂质,最佳流速有所不同,氯仿-正己烷(体积比1∶1)的最佳流速是1.55mL·min-1,而氯仿-甲醇(体积比9∶1)的最佳流速是0.68mL·min-1.
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筛选出了一组Vc二步发酵的新组合菌系(命名为B15-14),研究了环境因子对新菌系产酸的影响。结果显示:新组合菌系的最适底糖浓度为7%;温度为29~33℃,31℃为最适;适当增加通气量(20~30 mL装液量,250 mL三角瓶)有利于产酸;起始pH值范围为6.0~7.5;以B t菌做伴生菌时,发酵40 h就已达到终点,明显缩短了发酵时间。
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利用据历史文献中汉代以来的旱涝灾害记载重建的逐年旱涝等级,结合已重建的东部地区干湿指数序列,通过定义判别历史时期极端旱涝事件的标准,分华北、江淮和江南3个区域辨识了过去2000年的重大旱涝事件。结果表明,各个区域的重大旱、涝多发时段分别是:华北地区出现在100~150年、550~650年、1050~1100年与1850~1900年;江淮地区出现在250~450年与1600~1850年;江南出现在350~400年、1100~1200年与1900~1950年。整个东部地区则出现在100~150年、250~35
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观察了聚已内酯 (PCL) /玻璃纤维布和PCL/碳纤维布的机械性能的变化 ,通过对辐射交联的方法制备出了可生物降解聚合物涂覆纤维布复合材料。结果表明 ,γ辐射提高了复合材料的机械性能 ,这是由于所涂覆聚合物交联所产生的凝胶所致。在过冷态下通过γ射线照射 2 70kGy的PCL/玻璃纤维布复合材料的弯曲强度是未辐照样品的 1.5倍 ,弯曲模量提高到 1.35倍。通过酶降解试验和土埋法降解实验的研究 ,可以观察到降解导致了样品的失重。在酶降解试验中2 3h后 ,对于未交联材料涂覆的PCL完全降解掉 ,而交联样品中的PCL有 5 4%的失重发生。同样 ,在土埋法降解实验中 ,交联和未交联样品在一定的土埋时间后 ,也产生了样品的失重。未交联样品的失重率大于交联样品 ,这是由于交联样品所含有的交联网络结构阻碍它的降解。
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利用YJ-3000t和JL-3600t多顶砧压力机,以哀牢山造山带南部红河县大白能—乐育剖面上的天然块状斜长角闪岩为初始样品,在950℃、1.0~3.5GPa、恒温20~300h条件下进行了两个系列的斜长角闪岩块状样品脱水部分熔融实验:(1)保持温度T=950℃,加热时间t=100h不变,改变压力(1.0~3.5GPa)的实验;(2)保持温度T=950℃,压力p=3.0GPa不变,改变加热时间(20~300h)的实验。结果表明,1.0~3.5GPa、950℃、恒温100h的条件下,随压力升高,斜长角闪岩中依次生成了单斜辉石+石榴石+熔体的矿物组合(1.0~1.5GPa)和单斜辉石+石榴石+熔体+硬玉+SiO2矿物+蓝晶石(2.0~3.5GPa)的矿物组合。3.0GPa、950℃条件下,随加热时间增加,实验产物中依次生成了单斜辉石+石榴石+熔体+硬玉+SiO2矿物+蓝晶石的矿物组合(20~100h)和单斜辉石+石榴石+熔体的矿物组合(150~300h)。斜长角闪岩的原岩结构决定了实验产物中新生矿物和熔体的分布。依据实验产物的矿物组合和新生矿物的分布特征,讨论了950℃、1.0~3.5GPa、恒温(20~300h)条件下,斜长角闪岩部分熔融过程的结构变化、变质反应以及石榴石冠状体的成因。
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云南会泽铅锌矿床位于扬子板块西缘川-黔-滇铅锌银多金属成矿域的中南部,严格受断裂带的控制.长期以来,对于该矿的成矿流体来源存在着较大的争论.研究表明,矿石中脉石矿物方解石的C、O同位素组成相对均一,其δ^13C(PDB)为-2.1×10^-3~-3.5×10^-3极差-1.4×10^-3、均值-2.8×10^-3,δ^18O(SMOW)为16.7×10^-3~18.6×10^-3、极差1.9×10^-3、均值17.7×10^-3,不同矿体(不同标高)、不同产状以及相同矿体不同产状方解石的C、O同位素组成不具明显差别;除了纯液相包裹体(L)和富液相的气液两相包裹体(L+V)外,还存在含子晶的三相包裹体(S+L+V)和不混溶的CO2三相包裹体(VCO2+LCO2+LH2O),流体包裹体均一温度介于110~400℃之间,具有双峰现象;矿床的(^87Sr/^86Sr)0(0.713676-0.717012)不仅明显高于地幔(0.704±0.002)和峨嵋山玄武岩(0.703932~0.707818;85件样品)的(^87Sr/^86Sr)0,也相对高于矿区赋矿地层(C16)的(^87Sr/^86Sr)。(0.70868~0.70931;3件样品),但明显低于基底岩石的(^87sr/^86Sr)。(0.7243~0.7288;5件样品),且成矿过程中流体基本没有发生Sr同位素分馏现象.因此,成矿流体为均一流体,是不同性质流体的混合产物,具有多源性.而从气液两相包裹体盐度-均一温度图解可以看出,在300-400℃区间,包裹体盐度基本被孤立为两群:一群为5%~6%(w(NaCl)),另一群为12%~16%(w(NaCl)).而在100300℃特别是150-250℃区间,包裹体盐度则基本均匀分布在7%~23%(w(NaCl))之间.断裂带形成压力为(50~320)×10^5Pa,矿体上覆岩石压力为(574-640)×10%5Pa,矿床成矿压力为(145-754)×10^5Pa.流体在上升到断裂带后压力的剧降,导致了沸腾作用的发生.在混合作用和沸腾作用的双重影响下,受狭窄断裂带控制的成矿流体高度浓缩,金属矿物得以大规模地从流体中沉淀出来,形成品位极高的铅锌矿石.
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Dissertação para obtenção do Grau de Mestre em Engenharia Mecânica
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1891/12/20 (Numéro 150).
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Growth profiles of two isolates of Salmonella enteritidis phage type (PT) 4 inoculated into either the albumen of whole shell eggs or into separated albumen were found to be markedly affected by the size of the inoculum and the composition of the medium used to suspend the cells prior to inoculation. Using our model with an inoculum of two cells, multiplication of the Salmonella was not seen in 93% of eggs held at 20 degreesC for 8 days. In approximately 7% of eggs, however, growth occurred during the 8 days of storage. If the inoculum equaled or exceeded 25 cells per egg when eggs were subsequently stored at 20 degreesC, or 250 cells per egg when eggs were stored at 30 degreesC, high levels of growth of Salmonella in the egg occurred significantly more frequently than when the inoculum was two cells. High levels of growth were also seen more frequently if the inoculum was suspended in buffered peptone water or maximal recovery diluent rather than in phosphate buffered saline. Growth of Salmonella in separated albumen occurred very infrequently (1.1% of samples) at low inoculum levels and did not become significant until the inoculum was 250 cells or greater. Growth in the albumen was unaffected by the composition of the suspending medium. Provided that the inoculum was approximately 2 cells per egg and the bacteria were suspended in PBS, observed growth profiles of S. enteritidis inoculated into the albumen of whole eggs resembled those in naturally contaminated eggs. (C) 2001 Elsevier Science B.V. All rights reserved.
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Foram estudados os efeitos da suplementação de vitamina E (VE) e selênio (Se) sobre a imunidade de galinhas vacinadas contra Escherichia coli (EC) patogênica para suínos e com o vírus da encefalomielite aviária (VEA). Foram avaliados peso corporal (PC), peso de ovos (PO) e produção de anticorpos (AcP) em noventa poedeiras (H&N nick chick) com 49 semanas de idade alimentadas à vontade com dietas suplementadas com 0, 50, 150, 250 e 250 UI VE/kg + 0,3 ppm de Se. Às 51 semanas de idade, metade das galinhas foram vacinadas contra EC e todas as aves foram vacinadas contra VEA. Duas semanas após, receberam uma segunda dose da vacina contra EC. Amostras de sangue foram coletadas semanalmente e a quantidade de IgY foi determinada por ELISA, como densidade ótica (DO). As aves vacinadas apresentaram maior DO do que as aves não vacinadas (P≤0,05). As DO foram significativamente aumentadas (P≤0,05) quando as aves vacinadas foram alimentadas com 50 e 150 UI de VE/kg e comparadas com as DO das aves que receberam a dieta de 250 UI de VE + Se. Se não afetou AcP, PC e PO. A vacinação e a VE suplementada não afetaram PC. O PO não foi afetado pela vacinação, mas foi maior (P≤0,05) nas semanas 3, 5 e 7, quando as poedeiras receberam 250 UI VE/kg e comparados com aquelas que receberam 50, 150 e 0. A AcP contra VEA foi influenciada pela VE (P≤0,13). Cento e cinqüenta UI VE e 0 UI VE aumentaram IgY produzida, quando comparados a 250 UI. Também o Se aumentou AcP. Os resultados deste estudo sugerem que níveis médios de VE aumentam a produção de IgY por poedeiras vacinadas e Se adicionado ao mais alto nível de VE também possui efeito imunomodulador.
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A trial was carried out to evaluate efficacy of different herbicides and spray volumes when sprayed to ryegrass for chemical management and control of remaining seeds. The treatments were: three formulations of glyphosate at 1080 g ha(-1) (Original Round up, Round up Transorb, WG Round Up), paraquat + diuron at 300+500 and 150+250 g ha(-1) and glufosinate ammonium at 400 and 600 g ha(-1). All treatments were used in spray volumes of 200 and 400 l ha(-1). The effectiveness of the desiccation of ryegrass plants was assessed at 1, 3, 7, 14 and 21 days after application. At the last evaluation samples were collected for dry mass production analysis, and also panicles with seeds for germination test. Glyphosate in different formulations and volumes and glufosinate ammonium at 600 g ha(-1) when sprayed with into 400 l ha(-1) provided the best controls regarding ryegrass chemical management. Treatments with gliphosate (Roundup Original) and paraquat + diuron (300 +150 g ha(-1)) in volumes of 400 and 200 L ha(-1), respectively, were the ones that showed the lowest values of dry matter, differing from the control. All the ryegrass seeds were killed by treatments with herbicides (paraquat + diuron) at 500 + 250 g ha(-1) and glufosinate-ammonium at 600 g ha(-1) when used 200 l ha(-1).
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O nitrogênio é o elemento mais utilizado pela cultura do café e seu manejo é extremamente importante devido às perdas especialmente em épocas chuvosas. O trabalho foi desenvolvido em Argissolo Vermelho-Amarelo, na região de Sud Mennucci (SP), e teve como objetivo avaliar o efeito de diferentes doses e épocas de aplicação de nitrogênio sobre o teor de clorofila e de N nas folhas do cafeeiro, e calcular correlações com a produtividade. O delineamento experimental foi em blocos ao acaso com quatro repetições. Os tratamentos obedeceram o esquema fatorial 5 x 3, constituído pela combinação de cinco doses de N (0, 50, 150, 250 e 350 kg ha-1) aplicados na forma de uréia em três épocas de aplicação (aplicação única em dezembro; duas aplicações: parceladas em novembro e janeiro e três aplicações: parceladas em novembro, dezembro e janeiro). Avaliaram-se os teores de clorofila e nitrogênio das folhas durante a frutificação e a colheita. A concentração de clorofila correlacionou-se positivamente com o teor de nitrogênio nas folhas e a produção de grãos se ajustou a uma função quadrática com as doses de N aplicadas, na qual a dose 210 kg ha-1 promoveu a máxima produção; a estimativa do teor de clorofila foi promissora para detecção de possíveis deficiências de nitrogênio.
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
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The aim of this study was to evaluate the persistence of methacrylate-based cement residues on the dentin, after dentin surface cleaning with ethanol or acetone, with or without previous application of a dentin adhesive. Forty bovine crown fragments were obtained and the dentin surface was washed with 1.0 mL of 2.5% sodium hypochlorite (NaOCl), followed by 0.1 mL of 17% ethylenediaminetetraacetic acid application for 3 min, and final irrigation with 2.5% NaOCl. The specimens were air dried and resin-based cement was rubbed onto the dentine surface with a microbrush applicator. In 20 specimens, previously to cement, a dentin adhesive was applied in all surfaces. After 15 min, the surface was scrubbed with a cotton pellet and moistened with ethanol or acetone, compounding the following groups: G199.5% ethanol and G2acetone, without previous use of dentin adhesive; G399.5% ethanol and G4acetone, with previous use of dentin adhesive. The dentin surface was scrubbed until the cement residues could not be visually detected. Sections were then processed for scanning electron microscopy and evaluated at 500x magnification and scores were attributed to each image according to the area covered by residual sealer, and data were subjected to KruskalWallis at 5% significance. The lower residue presence was observed in G3 (P = 0.005). All surface presented cement residues when acetone was used as cleaning solution (P = 0.0005). The cleaning solutions were unable to completely remove the cement residues from both surfaces. The ethanol used after previous application of the dentin adhesive promoted the lower presence of residues.