931 resultados para C(1) and C(6): control (1 and 6 h 100% Oxygen saturation, normoxic)


Relevância:

100.00% 100.00%

Publicador:

Resumo:

围绕论文题目“电化学SPR生物传感器的研究及应用”,我们将SPR传感金膜同时用作电化学研究的界面,在自行组建的电化学SPR (EC-SPR)池中进行了相关的EC-SPR研究。 本论文研究工作的主要内容包括以下几个方面: 1. 发展了一种电化学薄化控制SPR金膜厚度,优化SPR信号的方法。这种方法主要是利用在较高电位下金与氯离子发生络合反应使SPR金膜表面的金部分溶解进入溶液从而达到薄化金基底的目的。通过调节溶液中氯离子的浓度和电化学扫描的次数,可以现场调控SPR基底的金膜厚度。我们用这种处理过的金膜进行了生物分子的吸附试验,结果证明了这种处理过的金膜适用于一般的SPR分析。 2. 采用湿化学镀膜法结合光刻法制备SPR金膜微阵列,拟将用于SPR成像分析。这种方法属于湿化学法制备SPR金膜微阵列,主要是在胶体金纳米粒子的自组装膜上刻蚀出金纳米粒子的微阵列,然后用湿化学法生长出合适的金微阵列。这种方法对制备条件要求比较简单,在制备纳米金微阵列的过程中腐蚀时间比较好控制,同时催化生长出新的金面。重复试验证实了这种方法能够制备出稳定的,尺寸可控的金微阵列,有望用于SPR成像系统研究生物分子相互作用。 3. 在SPR金膜表面利用电沉积法制备了超薄的壳聚糖薄膜,并将之应用于生物分子相互作用的研究。通过一步电沉积的方法制备了超薄的壳聚糖修饰的SPR金基片,并研究了几种常见蛋白与壳聚糖薄膜的非特异性作用,进一步用鼠IgG和抗鼠IgG作为一个典型的例子研究了壳聚糖修饰膜的生物相容性。试验表明壳聚糖修饰膜有好的生物相容性。 4. 首次提出利用生物催化沉积金属纳米粒子放大SPR信号测定小分子的方法。生物小分子抗坏血酸能够还原银离子,使其在金纳米表面沉积形成金属银原子。银原子的沉积将会极大地增强SPR信号,从而实现SPR光谱对小分子抗坏血酸浓度的放大测定。每次测定后,通过电化学剥脱Ag原子,SPR芯片的表面能够完全再生。同时,剥脱的银原子的量也能够被电化学测定,这也实现了抗坏血酸的间接电化学测定。 5. 结合电化学和SPR技术表征了DNA/Zr4+多层膜在金膜表面的生长过程,并研究了这种多层膜与细胞色素c的相互作用。SPR技术被用于测定 (DNA/ Zr4+)1双层中DNA单层的有效膜厚,及其表面覆盖率。利用红外反射光谱和X-射线光电子能谱表征这种多层膜的组成。通过EC-SPR方法,这种多层膜和细胞色素c的相互作用被进一步分析。结果表明这种多层膜不仅增强了细胞色素c的固定量,而且保持了细胞色素c的生物活性。 6. 利用EC-SPR技术测定了聚苯胺支撑的双层磷脂膜中的酶促反应。通过泡囊融合法在聚苯胺表面形成HRP掺杂的磷脂双层膜。这种磷脂双层膜能够很好的保存膜内的辣根过氧化酶(HRP)的活性,同时,这种膜允许质子的跨膜传输,能够提供聚苯胺和HRP在双氧水存在下反应所需的质子,实现酶促开关控制聚苯胺氧化还原态的变化,通过SPR检测这种聚苯胺膜的氧化还原态的变化,从而达到利用SPR测定酶底物小分子的目的。 7. 开展了适配子(aptamer)的EC-SPR研究。利用亚甲基兰为外在电化学探针分子,我们设计了一种简单的、可再生的电化学方法测定小分子腺苷。结果表明这种方法对腺苷的检测具有较高的灵敏性和选择性。这种设计思路有望进一步用于构建一个可再生的SPR传感器平台,用于研究适配子与蛋白质相互作用。

Relevância:

100.00% 100.00%

Publicador:

Resumo:

本论文以淀粉为研究对象,从高分子的基本理论出发,通过化学与物理的手段利用淀粉上的经基,调控了淀粉大分子链的聚集态结构,探索了将淀粉这种天然储能高分子变为实用的材料的可能性。采用化学交联的手段制备了交联淀粉膜。研究了淀粉交联后的老化过程和水在其中的结合状态。试验证明,交联键的引入使得淀粉的结晶和局部有序结构程度下降,让淀粉大分子的聚集态结构趋于均一化的同时,释放出大量的"自由轻基"。改变了淀粉膜的吸水能力和淀粉内部水分子的结合状态,综合交联与水分子的增塑作用,可以在一定程度上调控淀粉膜的力学性能。淀粉和生物降解大分子(PCL、PHBV)制备的IPN材料显著的提高了淀粉的耐水性能。通过实验证明DMSO/water配合体系作为一种高效、安全的组合溶剂对淀粉的醚化反应非常有效,取代度最高可达1.81。控制节基氯和淀粉重复单元的摩尔比、反应温度、DMSO/water组合溶剂的不同配比等可以制备出不同取代度的节基淀粉醚。经证实,淀粉的醚化反应主要发生在脱水葡萄糖环上的2位碳原子的经基上,其次发生在C-6、C-3碳原子的经基上。醚化后的淀粉即使很低的取代度(Ds:0.0546)时淀粉在x一射线衍射曲线上的结晶峰已经完全消失了。发现了稳定、高效的淀粉增塑剂FSDT。使用FSDT成功的对淀粉进行了塑化处理,而且塑化后的淀粉一年后仍保持优良的机械性能,特别是当FSDT的含量超过30%以后,淀粉从无法加工的脆性材料变成了类似弹性体的材料,在此基础对淀粉进行了化学交联,交联后样品的断裂伸长率有了更进一步的提升,达到470%。

Relevância:

100.00% 100.00%

Publicador:

Resumo:

本论文由三章组成。第一章介绍了中药蜘蛛香的化学成分的研究成果,第二章为羧甲基魔芋葡苷聚糖-壳聚糖为细胞膜的天冬酰胺酶人工细胞的研究,第三章综述了人工细胞在生物医学领域的应用。 第一章报道了中药蜘蛛香(Valeriana wallichii)根部乙醇提取物的化学成分,采用正、反相硅胶层析等分离方法和MS、NMR等多种波谱手段,从中共分离鉴定出17个化合物,分别为缬草素(valtrate,1),valechlorine(2),homobadrinal(3),baldrinal(4),乙酰缬草素(acevaltrate 5),valeriotetrate C(6),valeriotetrate B(7),对羟基苯乙酮(4'-hydroxy-acetophenone 8),7-hydroxy valtrate(9),8-methylvalepotriate(10),1,5-dihydroxy-3,8-epoxyvalechlorine A(11),二氢缬草素(didrovaltrate 12),胡萝卜苷(13),橙皮苷 (hesperidin 14),prinsepiol-4-O-β-D-glucopyranoside(15),longiflorone(16),乙基糖苷(17)。其中化合物6、7、10、和11为新化合物,化合物9、15、16为首次从该植物中得到。新化合物11为含有氯原子的刚性骨架环烯醚萜,并且确定了其绝对构型。 第二章报道了以羧甲基魔芋葡苷聚糖(CKGM)和壳聚糖(CS)为膜的固定化L-天冬酰胺酶人工细胞研究成果。利用羧甲基魔芋葡苷聚糖和壳聚糖两种生物相容性很好的天然多糖之间的静电吸引力,在非常温和的条件下制备成具有半透过性膜的人工细胞,将治疗儿童急性成淋巴细胞性白血病(ALL)的药物L-天冬酰胺酶包裹在内。通过考察温度和pH对人工细胞的影响,结果表明以CKGM- CS为膜的L-天冬酰胺酶人工细胞对温度和pH的稳定性和耐受性均高于自由酶,说明CKGM-CS对酶具有保护作用,而且小分子底物和产物可以自由进出膜内外,而包裹在膜内的生物大分子则不能泄露出来。 第三章综述了微囊化人工细胞的研究进展。 This dissertation consists of three parts. In the first part, the chemical constituents from the root of Valeriana wallichii were reported. In the second part, preparation and characteristics of L-Asparaginase Artificial cell were reported. The third part is a review on progress of microcapsule artificial cell. The first chapter is about the isolation and identification of the chemical constituents from the root of V. wallichii. Seventeen compounds were isolated from the ethanol extract of roots of V. wallichii through repeated column chromatography on normal and reversed phase silica gel. By the spectroscopic and chemical evidence, their structures were elucidated as valtrate (1), valechlorine (2), homobadrinal (3), baldrinal (4), acevaltrate (5), valeriotetrate C (6), valeriotetrate B (7), 4'-hydroxy-acetophenone (8), 7-hydroxy valtrate (9), 8-methylvalepotriate (10), 1,5-dihydroxy-3,8-epoxyvalechlorine A (11), didrovaltrate (12), daucosterol (13), hesperidin (14), prinsepiol-4-O-β-D-glucopyranoside (15), longiflorone (16), and ethyl glucoside (17). Among them, 6, 7, 10, and 11 are new compounds. 15, 16 and 9 were isolated from this plant for the first time. The absolute configuration of compound 11, an unusual iridoid bearing a C-10 chlor-group and an oxo-bridge connecting C-3 and C-8 resulting in a rigid skeleton, was confirmed. The second chapter is about the semi-permeable microcapsule of carboxymethyl konjac glucomannan-chitosan for L-asparaginase immobilization. Carboxymethyl konjac glucomannan-chitosan (CKGM-CS) microcapsules, which have good biocompatibility, prepared under very mild conditions via polyelectrostatic complexation, were used for immobilize L-asparaginase-a kind of drug for acute lymphoblastic leukemia (ALL). The activity and stability under different temperature and pH of the enzyme loaded-microcapsules were studied. The results indicated the immobilized enzyme has better stability and activity contrasting to the native enzyme. The study illustrates that the L-asparaginase could be protected in CKGM-CS microcapsules, the substrate and product could pass through the system freely.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

本学位论文报道了西藏产三种藏族传统植物药材的化学成分研究。论文由四章组成,前三章是实验部分,分别报道了尼泊尔黄堇(Corydalis hendersonii Hemsl.)、藏波罗花(Incarvillea younghusbandii Sprague)和全缘叶绿绒蒿(Meconopsis interifolia Franch.)的化学成分研究结果。从这三种青藏高原药用植物中共分离鉴定出33 个化合物,其中1 个是新化合物。第四章概述了罂粟科紫堇属植物的化学和药理研究进展。 第一章为尼泊尔黄堇的化学成分研究。通过正、反相硅胶柱色谱等分离方法从药用植物尼泊尔黄堇的地上部分共分离纯化得到12 个化合物。运用MS、1H-NMR、13C-NMR、DEPT、HMBC、NOESY 等现代波谱学方法将它们的结构鉴定为:刺罂粟碱(1) , 普托品(2) , 新那亭(3) , 斯可任(4) , tetrahydrothalifendine (5) ,9-methyl-decumbenine C (6),tetrahydroberberrubine (7),隐品碱(8),α-别隐品碱(9),6,7-methylenedioxy-1(2H)-oxoisoquinolinone (10),6-丙酮基-5,6 -二氢血根碱(11)和β-谷甾醇(12)。其中化合物6 为新化合物,为首次发现的分子骨架上C-9 位连有甲基的苯肽异喹啉类型生物碱。另外,除化合物1 和2 外,其它9 个生物碱(3~11)均为首次从该种植物中分离得到。同时,我们还对对尼泊尔黄堇中的总生物碱进行了串联质谱分析。 第二章为藏波罗花的化学成分研究。从该药用植物的地上部分共分离得到16个化合物,通过理化常数和波谱数据鉴定为:异佛手柑内酯(1),6-甲氧基当归素(2),欧前胡素(3),花椒毒内酯(4),珊瑚菜素(5),水合氧化前胡素(6),rivulobirin A (7),齐墩果酸甲酯(8),咖啡酸甲酯(9),银桦酸(10),(D)-boschniakinic acid (11),对羟基苯甲酸(12) , tert-O-β-D-glucopyranosyl-(R)-heraclenol (13) , 5-methoxy-8-O-β-D-glucopyranosyloxypsoralen (14),前胡苷V(15)和苯乙醇-O-β-D-吡喃葡萄糖-(1→2)-O-β-D-吡喃葡萄糖苷(16)。所有以上化合物均为首次从该种植物中分离得到。另外我们还首次对藏波罗花挥发油的化学成分进行了气相色谱-质谱(GC-MS)联用分析,共鉴定出39 个挥发性成分。 第三章为全缘叶绿绒蒿化学成分的分离鉴定。从传统藏药材全缘叶绿绒蒿地上部分共分离纯化出8 个化合物。通过理化常数和波谱数据将他们的结构分别鉴定为:去甲血根碱(1),β-谷甾醇(2),3-羟基-齐墩果烷-12(13)-烯-30-酸(3),6-丙酮基-5,6-二氢血根碱(4),木犀草素(5),胡萝卜苷(6),quercetin 3-O-β-D-glucopyranosyl-(16)-β-D-glucopyranoside (7)和普托品(8)。其中化合物1,4 和7 为首次从该种药用植物中分离得到。 第四章为综述,总结和归纳了近年来罂粟科紫堇属植物的化学和药理研究进展。 This dissertation consists of four parts. The first, second and third parts report the studies on the chemical constituents from the medicinal plants of Corydalis hendersonii, Incarvillea younghusbandii and Meconopsis interifolia. The forth part reviews the progress of the studies on Corydalis species. The first chapter is about the isolations and identifications of alkalids from the aerial parts of C. hendersonii which is a traditional Tibetan medicine to treat febrifuge, high blood pressure and hepatitis. A new isoquinoline alkaloid, 9-methyl-decumbenine C (6), together with ten known alkaloids, stylopine (1), protopine (2), canadine (3), scoulerine (4), tetrahydrothalifendine (5), tetrahydroberberrubine (7), cryptopine (8), α-allocryptopine (9), 6,7-methylenedioxy-1(2H)-isoquinolinone (10) and 6-acetonyl-5,6-dihydrosanguinarine (11), and β-sitosterol (12) were isolated. Their structures were elucidated by spectroscopic methods. Furthermore, the total alkaloids were analyzed by ESI-MSn. The second chapter is about the isolations and identifications of chemical constituents from the aerial parts of I. younghusbandii. Sixteen compounds were isolated and purified by normal and reversed phase silica gel column chromatography. By spectral analysis, there structures were identified as isobergapten (1), sphondin (2), imperatorin (3), xanthotoxin (4), phellopterin (5), heraclenol (6), rivulobirin A (7), methyl oleanolate (8), methyl caffeate (9), grevillic acid (10), (D)-boschniakinic acid (11), 4-hydroxybenzoic acid (12), tert-O-β-D-glucopyranosyl-(R)-heraclenol (13), 5-methoxy-8-O-β-D-glucopyranosyloxypsoralen (14), decuroside Ⅴ(15), and phenylethyl-O-β-Dglucopyranosyl-(1→2)-β-D-glucopyranoside (16). All of these compounds were isolated from this plant for the first time.By the way, the chemical components of the essential oil from I. younghusbandii were analyzed by GC-MS for the first time. The third chapter is about the the isolations and identifications of the chemical constituents of M. interifolia. Eight compounds were isolated and identified as norsanguinarine (1), β-sitosterol (2), 3-hydroxyolean-12(13)-en-30-oic acid (3), 6-acetonyl-5,6-dihydrosanguinarine (4), luteolin (5), daucosterol (6), quercetin 3-O-β-D-glucopyranosyl-(16)-β-D-glucopyranoside (7) and protopine (8). The compounds 1, 4 and 7 were isolated from this herb for the first time. The last chapter is a review of the research progress of the studies on Corydalis species, which includes the chemical constituents in this genus and their pharmacology.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

大气臭氧的损耗导致了地球表面具有生物学效应的紫外线-B(UV-B)辐射增强。同时,大气成分变化中除了UV-B辐射增强外,氮沉降是一个新近出现而又令人担忧的环境问题,其来源和分布正在迅速扩展到全球范围,并不断向陆地和水生生态系统沉降。本试验在四川省境内的中国科学院茂县生态站内进行,以云山、冷杉、色木槭和红椋子幼苗为模式植物,从生长形态、光合作用、抗氧化能力和矿质营养等方面研究了青藏高原东缘4种树苗对全球变化-增强UV-B辐射和氮供应(氮沉降)的响应。该试验为室外盆栽试验,包括四个处理:(1)大气UV-B辐射+无额外的氮供应(C);(2)大气UV-B辐射+额外的氮供应(N);(3)增强UV-B辐射+无额外的氮供应(UV-B);(4)增强UV-B辐射+额外的氮供应(UV-B+N)。其目的:一方面有助于丰富我国对全球变化及区域响应研究的全面认识,进一步完善在全球气候变化条件下臭氧层削减和氮沉降对陆地生态系统影响的内容;另一方面,在一定程度上有助于我们更好的理解在全球变化下森林更新的早期过程。具体结果如下: 增强的UV-B辐射在生长形态、光合、抗氧化能力、活性氧和矿质营养方面对4种幼苗都有显著的影响。UV-B辐射增强对幼苗的影响不仅与物种有关,而且,还与氮营养水平相关。总体表现为,高的UV-B辐射导致了色木槭和红椋子幼苗叶片的皱缩和卷曲,并降低了色木槭幼苗的叶片数和叶重,在额外的氮供应下,云杉、冷杉和红椋子的叶重也显著地降低了;色木槭和红椋子幼苗叶片的解剖结构受到了增强的UV-B辐射的影响,增强的UV-B辐射显著地降低了色木槭叶片的栅栏组织厚度,提高了红椋子叶片的厚度;增强的UV-B辐射显著地降低了4种幼苗的单株总生物量、植物地下部分的生长、总叶绿素含量 [Chl (a + b)]、净光合速率和最大量子产量(Fv/Fm),提高了4种幼苗叶片的膜脂过氧化(MDA含量),改变了植物体不同器官中的矿质元素含量;增强的UV-B辐射提高了冷杉、色木槭和红椋子叶片中的过氧化氢含量(H2O2)、超氧负离子(O2-)生成速率,在额外的氮供应下,云杉叶片中的活性氧含量也显著地提高了;在无额外的氮供应条件下,增强的UV-B辐射显著地提高了4种幼苗叶片中的UV-B吸收物质、脯氨酸含量和抗氧化酶的活性(SOD、POD、CAT、GR和APX)。在额外的氮供应条件下,UV-B辐射的增强却显著地降低了冷杉叶片中脯氨酸含量和红椋子叶片中UV-B吸收物质含量,但是,在4种幼苗叶片中,5种抗氧化酶的活性对UV-B辐射的增强没有明显的规律性,增强的UV-B辐射显著地提高了云杉叶片中的POD、SOD和GR的活性,提高了冷杉叶片中的POD和GR活性,提高了色木槭叶片中的POD、SOD和CAT活性和红椋子幼苗叶片中的POD和SOD活性。从这些结果可知,植物在遭受高的UV-B辐射导致的过氧化胁迫时,植物体内形成了一定的保护机制,但是,这种保护不能抵抗高的UV-B辐射对植物的伤害。 额外的氮供应在生长形态、光合、抗氧化能力、活性氧和矿质营养方面对4种幼苗都有一定的影响,不同幼苗对额外的氮供应响应不同,并且受到UV-B辐射水平的影响。在当地现有的UV-B辐射水平下,额外的氮供应显著地提高了幼苗的单株总生物量、植物地下部分的生长、Chl (a + b)、净光合速率(红椋子除外)、UV-B吸收物质(冷杉除外)、脯氨酸含量(红椋子除外)和部分抗氧化酶的活性,降低了H2O2的含量、O2-的生成速率和MDA含量(红椋子除外),改变了植物体内部分矿质元素含量,显著地提高了云杉和冷杉叶片中的Fv/Fm。这些指标总体表明,在当地现有大气UV-B辐射水平下,额外的氮供应对植物的生长和发育是有利的。在增强的UV-B辐射水平下,4种幼苗的生长形态和光合大部分指标都没有受到额外氮供应的影响,额外的氮供应提高了红椋子幼苗的单株总生物量和Chl (a + b)含量,提高了冷杉和色木槭叶片中的活性氧含量和MDA含量,却降低了红椋子叶片中的活性氧含量;额外的氮供应也提高了云杉、色木槭和红椋子叶片中UV-B吸收物质和脯氨酸含量,降低了冷杉叶片中UV-B吸收物质和脯氨酸含量;在抗氧化酶活性方面,额外的氮供应降低了云杉、冷杉叶片中5种抗氧化酶的活性和红椋子叶片中POD和GR的活性,提高了色木槭叶片中的POD和SOD的活性;4种幼苗植物体内的矿质元素含量对额外的氮供应没有显著的规律性。从这些结果可知,在高的UV-B辐射下,额外的氮供应提高了云杉、冷杉和色木槭幼苗对高的UV-B辐射的敏感性,然而,额外的氮供应却促进了红椋子幼苗的生长,原因可能是,在高的UV-B辐射下,额外的氮供应增加了红椋子叶片的厚度、叶重和叶片数,降低了叶片中活性氧含量的结果。表明在高的UV-B辐射水平下,额外的氮供应降低了红椋子幼苗对高的UV-B辐射的敏感性。 在全球变化的趋势下,UV-B辐射增强和氮沉降可能同时存在,我们的研究表明,与大气UV-B辐射+无额外的氮供应处理相比,增强UV-B辐射+额外的氮供应处理显著地降低了幼苗的单株总生物量(红椋子除外)、Chl (a + b)、净光合速率、Fv/Fm(冷杉除外)和MDA含量(红椋子除外),提高了活性氧含量 (云杉除外)、UV-B紫外吸收物质含量(冷杉除外)、脯氨酸含量和部分抗氧化酶的活性,改变了植物体不同器官中的矿质元素含量。结果表明,在当地现有条件下,全球变化(UV-B辐射增强和氮沉降)对云杉、冷杉和色木槭幼苗的生长是不利,尽管植物体内一些抗氧化性指标提高了,然而,却对红椋子幼苗的单株总生物量的累积没有显著的影响。 The depletion of the ozone led to the increase of ultraviolet-B (UV-B) with biological effects in the earth’s surface. At the same time, except for enhanced UV-B radiation, nitrogen deposition was an anxious environmental problem at present, rapidly expanding to the global scope and continuously depositing to land and aquatic ecosystem. The experiment was conducted in Maoxian Ecological Station of Chinese Academy of Sciences, Sichuan province, China. Picea asperata, Abies faxoniana, Acer mono Maxim and Swida hemsleyi (Schneid. et Wanger.) Sojak seedlings were selected as model plants to assess the effects of enhanced UV-B radiation and supplemental nitrogen supply on growth, morphological, photosynthesis, antioxidant and mineral nutrient traits of 4 species seedlings in east Qinghai-Tibetan Plateau. The experiment was potted outdoor, including 4 treatments: (1) ambient UV-B without supplemental nitrogen (control, C); (2) ambient UV-B with supplemental nitrogen (N); (3) enhanced UV-B without supplemental nitrogen (UV-B); (4) enhanced UV-B with supplemental nitrogen (UV-B+N). One hand, it was helpful for enriching our country to comprehensive understanding of the researches in the global change and the region response, further perfecting the effects of the depleted ozone layer and nitrogen deposition on land ecosystem under the global change; the other hand, it was favorable for us to better understanding of the early process of forest renews under the global change. The results were as follows: Enhanced UV-B radiation had significant effects on 4 species seedlings in growth, morphological, photosynthesis, antioxidant and mineral nutrient traits of 4 species seedlings. The effects of enhanced UV-B on plants were not only related with species, but also related with nitrogen nutrient level. Generally, the increase of UV-B radiation led to the shrinkage and curl of leaves in Acer mono Maxim and Swida hemsleyi (Schneid. et Wanger.) Sojak seedlings, and reduced the number of leaf and leaf weight of Acer mono Maxim seedlings, under supplemental nitrogen supply, leaf weight of Picea asperata, Abies faxoniana and Swida hemsleyi (Schneid. et Wanger.) Sojak seedlings significantly also reduced; the anatomical features of leaf in Acer mono Maxim and Swida hemsleyi (Schneid. et Wanger.) Sojak seedlings affected by enhanced UV-B radiation, the increase of UV-B radiation markedly reduced the palisade tissue thickness of Acer mono Maxim leaf and enhanced the leaf thickness of Swida hemsleyi (Schneid. et Wanger.) Sojak seedlings; the enhanced UV-B radiation significantly reduced total biomass per plant of 4 species seedlings, the growth of the underground parts, Chl (a + b), net photosynthetic rate and maximum potential quantum yield of photosynthesis (Fv/Fm), and increased the degree of lipid peroxidation (MDA content) and changed the content of mineral elements in different parts of plants; the enhanced UV-B radiation also increased the rate of superoxide radical (O2-) production and hydrogen peroxide (H2O2) content in leaves of Abies faxoniana, Acer mono Maxim, Swida hemsleyi (Schneid. et Wanger.) Sojak seedlings, under supplemental nitrogen supply, the reactive oxygen species in leaves of Picea asperata seedlings also significantly increased by enhanced UV-B radiation; under without supplemental nitrogen supply, enhanced UV-B radiation evidently induced an increase in UV-B absorbing compounds, proline content and the activities of antioxidant enzymes (SOD, POD, CAT, GR and APX) of leaves in 4 species seedlings. Under supplemental nitrogen supply, enhanced UV-B radiation induced a decrease in proline content of leaves in Abies faxoniana seedlings and UV-B absorbing compounds of leaves in Swida hemsleyi (Schneid. et Wanger.) Sojak seedlings, but, there were no obvious rules in the activities of five antioxidant enzymes of 4 species seedling leaves to enhanced UV-B radiation, enhanced UV-B radiation significantly increased the activities of POD, SOD and GR in Picea asperata leaves, the activities of POD and GR in Abies faxoniana leaves and the activities of POD, SOD and CAT in Acer mono Maxim leaves. The results indicated that some protective mechanism was formed when plants were exposed to enhanced UV-B radiation, but the protection could not counteract the harm of high UV-B radiation on plants. Supplemental nitrogen supply had some effects on 4 species seedlings in growth, morphological, photosynthesis, antioxidant and mineral nutrient traits. The response of 4 species seedlings was different to supplemental nitrogen supply, and was affected by UV-B levels. Under local ambient UV-B radiation, supplemental nitrogen supply significantly increased the total biomass per plant, the growth of underground parts, Chl (a + b), net photosynthetic rate (except for Acer mono Maxim seedlings), UV-B absorbing compounds (except for Abies faxoniana seedlings), proline content (except for Swida hemsleyi (Schneid. et Wanger.) Sojak seedlings) and the activities of some antioxidant enzymes, and reduced H2O2 content, the rate of O2- production and MDA content (except for Swida hemsleyi (Schneid. et Wanger.) Sojak seedlings) and changed the content of mineral elemental in different parts; supplemental nitrogen supply also evidently increased Fv/Fm in Picea asperata and Abies faxoniana seedlings. These results indicated that supplemental nitrogen supply was favorable for the growth of plants under local ambient UV-B radiation. Under enhanced UV-B radiation, mostly parameters in growth and morphology of 4 species seedlings were not affected by supplemental nitrogen supply. Supplemental nitrogen supply increased the total biomass per plant and Chl (a + b) of Swida hemsleyi (Schneid. et Wanger.) Sojak seedling, increased the reactive oxygen species and MDA content in Abies faxoniana and Acer mono Maxim leaves, and reduced the reactive oxygen species in Swida hemsleyi (Schneid. et Wanger.) Sojak leaves; supplemental nitrogen supply also increased UV-B absorbing compounds and proline content in Picea asperata, Acer mono Maxim and Swida hemsleyi (Schneid. et Wanger.) Sojak leaves, decreased UV-B absorbing compounds and proline content in Abies faxoniana leaves; in the activities of antioxidant enzymes, supplemental nitrogen supply significantly reduced the activities of antioxidant enzymes in Picea asperata and Abies faxoniana leaves and the activities of POD and GR in Swida hemsleyi (Schneid. et Wanger.) Sojak leaves, and increased the activities of POD and SOD in Acer mono Maxim leaves; the content of mineral elements in 4 species seedlings was no significantly rule to supplemental nitrogen supply. We knew from the results, under enhanced UV-B radiation, supplemental nitrogen supply made Picea asperata, Acer faxoniana and Acer mono Maxim seedlings more sensitivity to enhanced UV-B radiation, however, accelerated the growth of Swida hemsleyi (Schneid. et Wanger.) Sojak seedlings. The reason was probably that supplemental nitrogen supply increased the leaf thickness, leaf weight and leaf number, reduced the reactive oxygen content of leaf in Swida hemsleyi (Schneid. et Wanger.) Sojak seedlings grown under high UV-B radiation. This showed that supplemental nitrogen supply reduced the sensitivity of Swida hemsleyi (Schneid. et Wanger.) Sojak seedlings to high UV-B radiation. Under the tendency of the global change, enhanced UV-B radiation and nitrogen deposition may probably coexist. The results showed, compared with the treatment of ambient UV-B radiation without supplemental nitrogen supply, the treatment of enhanced UV-B radiation with supplemental nitrogen supply significantly reduced the total biomass per plants (except for Swida hemsleyi (Schneid. et Wanger.) Sojak seedlings), Chl (a + b), net photosynthetic rate, Fv/Fm and MDA content (except for Swida hemsleyi (Schneid. et Wanger.) Sojak seedlings), and increased reactive oxygen content (except for Picea asperata seedlings), UV-B absorbing compounds (except for Abies faxoniana seedlings), proline content and part antioxidant enzymes, and changed the content of mineral elements of different parts. The results indicated that the global change (enhanced UV-B and nitrogen deposition) were not favorable for the growth of plants under local ambient UV-B radiation and nitrogen nutrient level,, though increased some antioxidant indexes, however, the treatment of enhanced UV-B with supplement nitrogen supply did not significantly affect on the biomass accumulation of Swida hemsleyi (Schneid. et Wanger.) Sojak seedlings.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

土壤是人类赖以生存的自然环境和农业生产的重要资源,世界面临的粮食、资源和环境问题与土壤密切相关,目前危害土壤的主要因素是干旱和重金属污染。杨树具有适应性强、生长快和丰产等特性,本论文以青杨组杨树为模式植物,采用植物生态、生理及生物化学等方法,研究杨树对土壤干旱和锰胁迫的生态生理反应以及种群间差异,研究成果可为我国干旱半干旱地区营造人工林、防止沙漠化提供理论依据,也为恢复与重建重金属污染地区退化生态系统提供科学指导。主要研究结果如下: 1. 青海杨不同种群对干旱胁迫的响应差异 干旱胁迫显著降低了两个青海杨种群(干旱种群和湿润种群)生物量积累,包括株高、基径、干物质积累等,通过植物结构的调整,有更多的生物量向根部分配。干旱胁迫还显著降低了叶绿素和类胡萝卜素含量,增加了游离脯氨酸和总氨基酸含量。另一方面,干旱胁迫诱导了活性氧的积累,作为第二信使,激活了抗氧化系统,包括抗坏血酸(ASA)含量和酶系统如超氧化物歧化酶(SOD),愈创木酚过氧化物酶(GPX),抗坏血酸过氧化物酶(APX)和谷胱甘肽还原酶(GR)。这样,杨树既有避旱机制又有耐旱机制,使其在干旱胁迫下有相当程度的可塑性。与湿润种群相比,干旱种群杨树有更多的生物量分配到根部,积累了更多的游离脯氨酸和总氨基酸来进行渗透调节,并且有更有效的抗氧化系统,包括更高含量的ASA 和更高活性的APX 和GR,这些使得干旱种群杨树比湿润种群杨树对干旱有更好的耐性。 2. 喷施硝普钠(SNP)对青海杨阿坝种群干旱胁迫耐性的影响 干旱胁迫显著的降低了青海杨阿坝种群的生长和生物量积累以及叶片相对含水量,还诱导了脯氨酸的合成以进行渗透调节。干旱胁迫下过氧化氢(H2O2)显著累积从而造成对膜脂和蛋白的伤害,使得丙二醛和蛋白羰基含量升高。干旱胁迫下喷施SNP可以减轻干旱胁迫造成的伤害,包括增加叶片的相对含水量,增加脯氨酸和总氨基酸的积累,并激活抗氧化酶系统如SOD,GPX和APX,从而减少丙二醛(MDA)和蛋白羰基(C=O)的积累,但是在水分良好情况下SNP的效果不显著。 3. 青杨不同种群对锰胁迫的生长与形态响应差异 在同一锰浓度下,干旱种群的耐性指数都要高于湿润种群,这表明青杨对干旱和高锰胁迫具有交叉耐性。两个种群的株高,生物量和叶绿素含量都随锰浓度的升高而逐渐下降。就累积浓度而言,0 和0.1 mM 锰胁迫下,干旱种群积累的锰浓度要高于湿润种群,而在高浓度锰胁迫下(0.5 和1 mM),湿润种群要高于干旱种群。在0,0.1 和0.5 mM下,锰大多积累在根中,叶片次之,茎中最少。而在1 mM,锰更多的积累在叶片中。就累积总量而言,在各个锰浓度胁迫下,根,茎和叶相比,两个种群青杨都是叶片累积的锰总量要高于根和茎。两个种群间比较,对照中没有显著区别,0.1 mM 锰胁迫下,湿润种群根中累积的锰要高于干旱种群,而在地上部中,干旱种群要高于湿润种群。而0.5 和1 mM 锰胁迫下,根、叶、茎+叶、根+茎+叶中,锰累积总量都是湿润种群高于干旱种群。锰胁迫下,青杨叶片数和叶面积包括总叶面积和平均叶面积都显著降低。叶片横切面的光学显微观察结果表明未经锰胁迫的栅栏组织的细胞饱满,海绵组织发达、清晰;胁迫后杨树叶片栅栏组织细胞出现不同程度的皱缩,海绵组织几乎不可见,此外还发现输导组织在胁迫下密度变小和分生组织严重割裂等现象。 4. 青杨不同种群对锰胁迫的生理与生化响应差异 青杨两个种群脱落酸(ABA)含量在锰胁迫下都显著增加,干旱种群的增幅更大。三种多胺含量在锰胁迫下显示了不同的响应趋势:腐胺在两个种群的各个锰处理下都增加,亚精胺只在干旱种群中显著增加,而精胺除了干旱种群在1 mM 下有所增加外,在锰胁迫下变化很小。谷胱甘肽含量随锰浓度升高而增加,在0.5 mM 锰时达到最高值,1mM 时有所下降。植物络合素(PCs)含量与非蛋白巯基(NP-SH)趋势相似,随锰浓度的升高而增加,且干旱种群中含量要高于湿润种群。锰处理还引起氧化胁迫,表现为过氧化氢和丙二醛含量增加。SOD 活性在湿润种群中,在0 到0.5 mM 锰胁迫下活性升高,但在1 mM 锰胁迫时,其活性有所下降。而在干旱种群中,SOD 活性变化较小,并始终维持在一个较高的水平。APX 活性在两个种群中都随锰浓度的升高而增加,干旱种群活性要高于湿润种群。锰胁迫还显著增加了酚类物质的含量,同时GPX 和多酚氧化酶(PPO)活性也随锰浓度的升高而增加。干旱种群的酚类含量和GPX 与PPO 活性都要高于湿润种群。锰胁迫还改变了氨基酸的含量和构成,根据锰胁迫下浓度变化的不同,可以将游离氨基酸分为三组:第一组包括,谷氨酸,丙氨酸和天门冬氨酸,这一组氨基酸含量在锰胁迫下有所下降。第二组包括缬氨酸,亮氨酸和苏氨酸含量在锰胁迫下基本不变化或变化很小。剩下的氨基酸为第三组,这组氨基酸含量在锰胁迫下显著增加,而根据增加的幅度又可以将它们分为两个亚组,丝氨酸,酪氨酸,苯丙氨酸,组氨酸和脯氨酸,在1 mM 下的含量是对照的4 倍以上。异亮氨酸,赖氨酸,精氨酸和甘氨酸含量在1 mM 下是对照含量的2 倍以下。同时,同一锰浓度下,干旱种群比湿润种群积累的氨基酸含量要高。 Soil is the indispensable environment for human survival and important resource foragriculture development. Food and environmental problems facing the world are all closelyrelated to soil and nowadays it is threatened by many factors, among which drought stress andheavy metal pollution are the most serious ones. Poplars (Populus spp.) are importantcomponents of ecosystem and suitable as a source of fuel, fiber and lumber due to their fastgrowth. In this study, different populations of Section Tacamahaca spach were used as modelplants to investigate the adaptability to drought stress and manganese toxicity and differencesbetween populations from dry and wet climate regions. Our results can provide theoreticalevidence for the afforestation and prevention of desertification in the arid and semi-arid areas,and also can supply scientific direction for the reconstruction and rehalibitation of ecosystemscontaminated by heavy metals. The results are as follows: 1. Differences in ecophysiological responses to drought stress in two contrastingpopulations of Populus przewalskii Drought stress not only significantly affected dry mass accumulation and allocation, butalso significantly decreased chlorophyll pigment contents and accumulated free proline andtotal amino acids. On the other hand, drought also significantly increased the levels ofabscisic acid and reactive oxygen species, as secondary messengers, to induce the entire set ofantioxidative systems including the increase of reduced ascorbic acid content and the activities of superoxide dismutase, guaiacol peroxidase, ascorbate peroxidase and glutathioneredutase. Thus the combination of drought avoidance and tolerance mechanisms conferredpoplar a high degree of plasticity in response to drought stress. Compared with the wetclimate population, the dry climate population showed lower dry matter accumulation andallocated more biomass to root systems, and accumulated more free proline and total aminoacids for osmotic adjustment. The dry climate population also showed more efficientantioxidant systems with higher content of ascorbic acid and higher activities of ascorbateperoxidase and glutathione redutase than the wet climate population. All these made the dryclimate population superior in adaptation to drought stress than the wet climate population. 2. Effect of exogenous applied SNP on drought tolerance in Populus przewalskii Drought stress significantly increased hydrogen peroxide content and caused oxidativestress to lipids and proteins assessed by the increase in malondialdehyde and total carbonylcontents, respectively. The cuttings of P. przewalskii accumulated proline and other aminoacids for osmotic adjustment to lower water potential, and activated the antioxidant enzymes such as superoxide dismutase, guaiacol peroxidase and ascorbate peroxidase to maintain thebalance of generation and quenching of reactive oxygen species. Moreover, exogenous SNPapplication significantly heightened the growth performance of P. przewalskii cuttings underdrought treatment by promotion of proline accumulation and activation of antioxidant enzymeactivities, while under well-watered treatment the effect of SNP application was very little. 3. Morphological responses to manganese toxicity in the two contrasting populations ofPopulus cathayana High concentration of manganese caused significant decrease in shoot height andbiomass accumulation. The tolerance index of the dry climate population was significantlyhigher than that of the wet climate population, suggesting the superior Mn tolerance in theformer and the existence of cross-tolerance of drought stress and high Mn toxicity. Injuries tothe leaf anatomical features were also found as the reduced thickness in palisade and spongyparenchyma, the decreased density in the conducting tissue and the collapse and split in themeristematic tissue in the central vein. As for the Mn concentrations in the plant tissues, under0, 0.1 and 0.5 mM, most of the Mn accumulated in the roots, then leaves, and stem the least, while under 1 mM, most of the Mn accumulated in the leaves. As far as the total amounts ofMn extraction are concerned, the leaf extracted more Mn than the root and stem in the twopopulations under various Mn concentrations. There is no difference between the twopopulations under control. Under 0.1 mM, the wet climate population extracted higher Mn inthe root than the dry climate population, while in the shoot, the dry climate populationextracted much more Mn. Under 0.5 and 1 mM, the wet climate population translocated moreMn both in the root and the shoot than the dry climate population. 4. Physiological and biochemical responses to manganese toxicity in the two contrastingpopulations of Populus cathayana Mn treatment resulted in oxidative stress indicated by the oxidation to lipids, proteinsand DNA. A regulated network of defence strategies was employed for the chelation,detoxification and tolerance of Mn including the enhanced synthesis of ABA and polyamines,the accumulation of free amino acids, especially His and Pro, and the activation of theenzymes superoxide dismutase and guaiacol peroxidase. Contents of non-protein thiol,reduced glutathione, phytochelatins and phenolics compounds and activities of superoxide dismutase, guaiacol peroxidase and polyphenol oxidase also increased significantly forantioxidant or chelation functions. The wet climate population not only accumulated lessabscisic acid, free amino acids, phytochelatins and phenolics compounds, but also exhibitedlower activities of superoxide dismutase, guaiacol peroxidase and polyphenol oxidase thusresulting in more serious oxidative damage and more curtained growth.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

This paper present that the system can acquire the remote temperature measurement data of 40 monitoring points,through the RS-232 serial port and the Intranet.System s hardware is consist of TI s MSP430F149 mixed-signal processor and UA7000A network module.Using digital temperature sensor DS18B20,the structure is simple and easy to expand,the sensors directly send out the temperature data.MSP430F149 has the advantage of ultra-low-power and high degree of integration.Using msp430F149,the multi-branch multi-p...中文文摘:文章论述了通过RS-232串口和Intranet网络,来实现对远端的40个温度测量点的监控。系统硬件由TI公司的MSP430F149混合信号处理器和UA7000A网络模块构成。传感器采用数字式温度传感器DS18B20,它将直接得到温度的数字量,结构简单,易于扩展。MSP430F149处理器具有超低功耗和高度集成等优点,利用它构建的多分支多通道温度测量系统功能强大,结构简单,可靠性高,抗干扰能力强。系统客户端软件采用Microsoft Visual C++6.0设计。本监控系统能够很好地完成对4个分支共40个温度测量点的远程实时监控。

Relevância:

100.00% 100.00%

Publicador:

Resumo:

目的 重离子和高剂量率6 0 Coγ射线照射离体人血建立染色体畸变的剂量 效应曲线 ;比较重离子1 2 C照射与6 0 Coγ射线照射诱发染色体畸变的相对生物效能。方法 重离子1 2 C和6 0 Coγ射线照射离体人血 ,吸收剂量率为 3Gy min ,吸收剂量为 1 0~ 8 0Gy。主要记录染色体型畸变的非稳定性畸变 ,对双着丝粒体和着丝粒环做曲线拟合 ,并检验回归系数的显著性和曲线的拟合度。结果 重离子1 2 C和6 0 Coγ射线照射离体血诱发的染色体畸变 (双 +环 ) ,在 0~ 8Gy范围内 ,呈良好的剂量 效应关系。1 2 C离子诱发染色体畸变的RBE值是不恒定的 ,它随吸收剂量增加而减少 ,在 0 3~ 8 0Gy范围内 ,RBE值 (Dγ Dc)从 2 6 2到 1 0 0 ,平均 1 5 8。结论 1 2 C离子对6 0 Coγ射线照射诱发染色体畸变 ,在照射剂量较低时 ,有较高的生物效应。

Relevância:

100.00% 100.00%

Publicador:

Resumo:

重离子束治癌是当今放射治疗中最科学、最先进、最有效的方法,是有代表性的高技术。目前仅有美、日、德实现了该技术,并已取得常规疗法难以实现的疗效。我国近年来开展了“重离子束治癌技术的基础研究”,其中,放射生物学及机理研究是重要内容。本论文从细胞、DNA分子、以及动物个体的三个不同层次上分别研究了重离子束治癌相关的生物学问题。在细胞研究方面。采用HeLa、B 16两种细胞分别研究了X一射线和重离子在水介质中入射的深度与相应细胞的存活率(1一失活率),结果表明:X一射线对细胞的损伤随深度而逐渐衰减(或细胞存活随深度逐渐增加),而重离子对细胞的损伤则为Bragg曲线(或细胞存活为倒Bragg曲线)。研究了25MeV/u ~(40)Ar~(14+)辐照人肝癌细胞SMMC一7721的微核及存活的动态变化,结果表明: 单次照射与分次照射的微核率随时间的变化规律在96h内没有明显区别,受照(单次、分次) 肝癌细胞的存活数随时间表现出衰减趋势,微核率与细胞存活数关系的动态变化为负相关性。研究了6MV X-射线和125.5keV/μm的重离子辐照B 1 6、V79细胞的2Gy存活率(SF2),结果表明:B16和V79细胞的存活率(P<0.01)依赖于不同的辐射性质(X-射线、~(12)C离子),其X-射线与~(12)C离子辐射这两种细胞的存活率之比分别为5.4和1.43,即~(12)C离子辐射增强了X-射线抗性细胞系的敏感性,从而显示了重离子治疗癌症的优势。研究了125.5keV/um的碳离子辐照小鼠黑色素瘤B16、人的宫颈癌HeLa、中国仓鼠肺V79、人的肝癌SMMC-7721四种细胞的相对生物学效率(RBE),得.到了RBE依赖于细胞种类的关系、RBE随细胞存活水平的升高而增加的关系、以及当LET≥125.5keV/μm时,RBE随着LET的增大而变小的关系。在DNA分子研究方面。研究了125.5keV/μm~(12)C~(6+)辐照小鼠黑色素瘤B 16、中国仓鼠肺V79、人的宫颈癌HeLa、人的肝癌SMMC一7721细胞的灵敏度(由D50表示)、DNA双链断裂(DSB)和DNA双链断裂片段分布,结果表明:细胞敏感性与DNA双链断裂之间没有一致的关系,提出了细胞辐射敏感性的一种可能的分子机理,即DNA序列敏感性位点协同DNA双链断裂互补性机理。由此解释了四种细胞系的不同敏感性问题。在动物个体研究方面。研究了57.28MeV/u氧离子50Gy一次性局部照射对B16黑色素瘤小鼠肿瘤生长的抑制作用,并观测了受照小鼠的死亡情况,结果表明:照射B16黑色素瘤后第10天观察,肿瘤生长延迟为6天、肿瘤抑制率为66%,耐受剂量小于50Gy。研究了50MeV/u ~(12)C~(6+)离子辐照对小鼠移植性肿瘤S180的抑制作用、控制率、治愈率和病理组织学变化,结果表明:各剂量组对S180肉瘤的抑制作用均大于90%,高剂量组抑瘤作用明显强于低、中剂量组(P12)C~(6+)离子束照射正常昆明种小鼠右后肢的耐受剂量和致死剂量,结果表明:小鼠耐受剂量小于1Gy, 绝对致死或超致死剂量≥30Gy。观测了63MeV/u ~(12)C~(6+)离子束局部辐照小猪的皮肤损伤及整体猪白细胞计数和体重增长的情况,得到了辐照猪的耐受剂量为27.06Gy。

Relevância:

100.00% 100.00%

Publicador:

Resumo:

本文研究维生素C二步发酵接种种液状态与发酵转化的关系,指明接种种液浓度为6.5×109个/ml,二菌数量之比为0.3,种液酸量为7mg/ml时.可获得较好的发酵转化效率。

Relevância:

100.00% 100.00%

Publicador:

Resumo:

To find the pathologic cause of the children's dental fluorosis in southwestern China, diet structure before the age of 6 and prevalence rate of dental fluorosis (DF) of 405 children were investigated, and the fluorine and arsenic content of several materials were determined. The prevalence rate of DF of children living on roasted corn before the age of 6 is 100% with nearly 95% having the mild to severe DF; while that of children living on non-roasted corn or rice is less than 5% with all having very mild DF. The average fluorine and arsenic concentration are 20.26 mg/kg and 0.249 mg/kg in roasted corn, which are about 16 times and 35 times more than in non-roasted corn, respectively. The average fluorine concentration is 78 mg/kg in coal, 1116 mg/kg in binder clay and 313 mg/kg in briquette (coal mixed with clay). The average arsenic concentration of coal is 5.83 mg/kg, the binder clay is 20.94 mg/kg, with 8.52 mg/kg in the briquette. Living on roasted corn and chili is the main pathologic cause of endemic fluorosis in southwestern China. The main source of fluorine and arsenic pollution of roasted corn and chill is the briquette of coal and binder clay. (C) 2010 Elsevier B.V. All rights reserved.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

The separation of ethyl acetate and ethanol (EtOH) is important but difficult due to their close boiling points and formation of an azeotropic mixture. The separation of the azeotropic mixture of ethyl acetate and EtOH using the hydrophilic ionic liquids (ILs) 1-alkyl-3-methylimidazolium chloride (alkyl = butyl, hexyl, and octyl) ([C(n)mim]Cl, n = 4, 6, 8) and 1-allyl-3-methylimidazolium chloride and bromide ([Amim]Cl and [Amim]Br) has been investigated. Triangle phase diagrams of five ILs with ethyl acetate and EtOH were constructed, and the biphasic regions were found as follows: [Amim]Cl > [Amim]Br > [C(4)mim]Cl > [C(6)mim]Cl > [C(8)mim]Cl. The mechanisms of the ILs including cation, anion, and polarity effect were discussed.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

A rapid and simple analytical method was developed for the simultaneous and quantitative determination and separation of hydrophilic imidazolium ionic liquids (ILs) (1-butyl-3-methylimidazolium chloride, [C(4)mim]Cl; 1-hexyl-3-methylimidazolium chloride, [C(6)mim]Cl; 1-octyl-3-methylimidazolium chloride, [C(8)mim]Cl; 1-allyl-3-methylimidazolium chloride, [Amim]Cl; or 1-allyl-3-methylimidazolium bromide, [Amim]Br) with miscible ethyl acetate and EtOH and their mixtures using reverse phase liquid chromatography coupled with refractive index detection (RPLC-RI). The influence of 60 to 100% (volume percentage) methanol in the mobile phase on the IL systems ([C(4)mim]Cl, [C(6)mim]Cl, [C(8)mim]Cl, [Amim]Br, or [Amim]Cl)-ethyl acetate-EtOH was investigated.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

A series of (alpha-diimine)nickel(II) complexes [ArN = C(Nap)C = NAr]NiBr2 (Nap = 1,8-naphthdiyl, Ar = 2,6-Me2C6H3, 3a; Ar = 2,4,6-Me3C6H2 3b; Ar = 2,6-Me-2-4-tBuC(6)H(2), 3c; Ar 2,6-Me-2-4-BrC6H2, 3d; Ar = 2,6-Me-2-4-ClC6H2, 3e; Ar 2,6-iPr(2)C(6)H(3), 3f; Ar = 2,4,6-iPr(3)C(6)H(2), 3g; Ar = 2,6-iPr-4-BrC6H2, 3h) have been synthesized, characterized, and investigated as precatalysts for ethylene polymerization in the presence of modified methylaluminoxane (MMAO).

Relevância:

100.00% 100.00%

Publicador:

Resumo:

A series of novel vanadium(III) complexes hearing heteroatoill-containing group-substituted salicylaldiminato ligands [RN=CH(ArO)]VCl2(THF)(2) (Ar = C6H4, R = C3H2NS, 2a; C7H4NS, 2c; C7H5N2, 2d; Ar = C(6)H(2)tBu(2) (2,4), R = C3H2NS, 2b) have been synthesized and characterized. Structure of complex 2c was further confirmed by X-ray crystallographic analysis. The complexes were investigated as the catalysts for ethylene polymerization in the presence of Et2AlCl. Complexes 2a-d exhibited high catalytic activities (up to 22.8 kg polyethylene/mmolv h bar), and affording polymer with unimodal molecular weight distributions at 25-70 degrees C in the first 5-min polymerization, whereas produced bimodal molecular weight distribution polymers at 70 degrees C when polymerization time prolonged to 30 min. The catalyst structure plays an important role in controlling the molecular weight and molecular weight distribution of the resultant polymers produced in 30 min polymerization. In addition, ethylene/hexene copolymerizations with catalysts 2a-d were also explored in the presence of Et2AlCl, which leads to the high molecular weight and unimodal distributions copolymers with high comonomer incorporation.