65 resultados para EXAFS XANES Cu(I) Cu(II) soluzioni
Resumo:
Several biochemical responses were measured in silver crucian carp (Carassius auratus gibelio) after exposure to sediments obtained from contaminated Ya-Er Lake, No, 1 pond, and an unpolluted reference site, Honglian Lake. After 1 week of exposure, a significant induction of the phase I biotransformation enzyme (ethoxylresorufin-o-deethylase, EROD) was found (83-fold of control), whereas the phase II biotransformation enzyme (glutathione S-transferase, GST) exhibited a slight, but significant induction (1,4-fold of control) after 4 weeks of exposure. The level of cellular glutathione in the liver was also slightly elevated after 4 weeks of exposure. The delayed response of GST to the contaminants indicates that the phase I and phase II biotransformation enzymes are regulated differently in fish. The results suggest that EROD is a sensitive bioindicator to assess the toxicity of dioxin-contamined sediment in the laboratory, (C) 1998 Academic Press.
Resumo:
The photoluminescence (PL) of In0.55Al0.45As/Al0.5Ga0.5As self-assembled quantum dots has been measured at 15 and 80 K under hydrostatic pressure. The lateral size of the dots ranges from 7 to 62 nm. The emissions from the dots with 26, 52 and 62 nm size have a blue shift under pressure, indicating that these quantum dots have the normal type-I structure with lowest conduction band at the Gamma -valley. However, the PL peak of dots with 7 nm diameter moves to lower energy with increasing pressure. It is a typical character for the X-related transition. Then these small dots have a type-II structure with the X-valley as the lowest conduction level. An envelope-function calculation confirms that the Gamma -like exciton transition energy will rise above the X-like transition energy in the In0.55Al0.45As/Al0.5Ga0.5As structure if the dot size is small enough.
Resumo:
We investigate the electronic structures of the inhomogeneous quantum dots within the framework of the effective mass theory. The results show that the energies of electron and hole states depend sensitively on the relative magnitude 77 of the core radius to the capped quantum dot radius. The spatial distribution of the electrons and holes vary significantly when the ratio eta changes. A quantum-confinement-driven type-II-type-I transition is found in GaAs/AlxGa1-xAs-capped quantum dot structures. The phase diagram is obtained for different capped quantum dot radii. The ground-state exciton binding energy shows a highly nonlinear dependence on the innner structures of inhomogeneous quantum dots, which originates from the redistribution of the electron and hole wave functions.
Resumo:
用蓖麻油与TDI反应生成端异氰酸酯基预聚物,再与HEA反应,生成端乙烯基预聚物,以不同比例的MMA与端乙烯基预聚物共聚交联,得到一组组成和交联密度各不相同的ABCP样品;为了分别观察组成和交联密度对材料性能的影响,在交联共聚过程中,以二乙烯基苯作交联点调节剂 ,得到固定组成,交联密度变化和固定交联密度组成变化的两组样品;此外,在固化过程中加入不同含量的丙烯酸(<10%),得到另一组样品,以观察氢键对该体系的影响。反应过程中用化学分析、NMR、IR及平衡溶胀等方法测定反应程度、分子量及交联网的交联密度;同时用动态粘弹谱仪和介电损耗仪测定样品的动态力学性能,转变与松弛及相容性;用材料试验机测试样品的力学性能;通过透射电子显微镜观察材料的形态结构。结果表明:copu/PMMA ABCP是个半相容体系,随硬段含量的增加和交联密度的减小相容性变差。形态结构呈不规则形状,相区尺寸由几A变至几百A,材料的力学性能和阻尼性能明显优子构成它们的均聚物。材料的阻尼值主要受交联密度的影响,玻璃化转变温度则主要受组成控制。氢键对该体系的形态结构有明显影响,丙烯酸含量为7.5%时相容性最差,5%和10%时最好。以双阳昌10号井原油为研究对象选用EVA作原料,以马来酸酐接枝改性,合成ET-6降凝剂。采取在热处理中加入降凝剂的综合处理方法,考察了降凝剂合成的最佳反应条件和降凝剂用量及热处理温度对原油结晶状态及流动性的影响。结果表明,热处理中加入ET-6降凝剂可使蜡的结晶形态发生明显变化,降凝剂用量仅100-500 ppm即可使双阳原油的凝固点由原来的30-31 ℃降至7-9 ℃,原油的低温流动性大为改观。
Resumo:
The photoluminescence (PL) of In0.55Al0.45As/Al0.5Ga0.5As self-assembled quantum dots has been measured at 15 and 80 K under hydrostatic pressure. The lateral size of the dots ranges from 7 to 62 nm. The emissions from the dots with 26, 52 and 62 nm size have a blue shift under pressure, indicating that these quantum dots have the normal type-I structure with lowest conduction band at the Gamma -valley. However, the PL peak of dots with 7 nm diameter moves to lower energy with increasing pressure. It is a typical character for the X-related transition. Then these small dots have a type-II structure with the X-valley as the lowest conduction level. An envelope-function calculation confirms that the Gamma -like exciton transition energy will rise above the X-like transition energy in the In0.55Al0.45As/Al0.5Ga0.5As structure if the dot size is small enough.
Resumo:
本文利用单向SDS-PAGE方法对十八株Frankia菌的全细胞可溶性蛋白进行了图谱分析。Frankia菌蛋白图谱不受菌令的影响。不同交叉接种组的Frankia菌具有不同的蛋白图谱,同一交叉接种组内的菌株也有所羞。十八株菌分为三大类七个亚类,第I类包括赤场、杨梅香蕨木和美洲茶内生菌;第II类包括木麻黄内生菌,第III类包括胡颓子和沙棘内生菌。利用同功酶图谱的差异性对Frankia菌进行分类识别是一种非常有效的方法,不同的Frankia菌株具有不同的同功酶(过氧化物酶和酯酶)图谱。根据图谱之间的相似性,可以将二十株Frankia菌分成三组;即赤杨组,木麻黄组和胡颓子组,这与其它分类结果基本符合,只是细枝木麻黄菌株CcO1的过氧化物酶图谱与其它菌株完全不同。从同种根瘤中分离的内生菌具有不同的同功酶图谱,进一步证实了遗传结构不完全相同的菌株可以同时共生于同种根瘤内,同时根据二种同功酶的电泳分布率,说明了Frankia菌株遗传信息的广泛分布性。
Resumo:
In the mixed-metal complex catena-poly[bis[diaquasilver(I)] [bis[aquacopper(II)]-mu(3)-pyridine-2,5-dicarboxylato-2': 1: 1'kappa N-5,O-2: O-5: O-5, O-5'-mu-pyridine-2,5-dicarboxylato-2: 1 kappa(4) N, O-2: O-5, O-5'-disilver(I)-mu(3)-pyridine-2,5-dicarboxylato-1: 1': 2 '' kappa(5) O-5, O-5': O-5: N, O-2-mu pyridine-2,5-dicarboxylato-1': 20 ''kappa(4) O-5, O-5': N, O-2] hexahydrate], {[Ag(H2O)(2)][AgCu(C7H3NO4)(2)(H2O)] center dot 3H(2)O}(n), a square-pyramidal Cu-II center is coordinated by two N atoms and two O atoms from two pyridine-2,5-dicarboxylate (2,5-pydc) ligands and a water molecule, forming a [Cu(2,5-pydc)(2)-( H2O)](2-) metalloligand. One Ag I center is coordinated by five O atoms from three 2,5-pydc ligands and, as a result, the [Cu(2,5-pydc)(2)(H2O)](2-) metalloligands act as linkers in a unique mu(3)-mode connecting Ag-I centers into a one-dimensional anionic double chain along the [101] direction.