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排序方式: 共有1047条查询结果,搜索用时 359 毫秒
81.
M. B. J. G. Freitas E. M. Garcia V. G. Celante 《Journal of Applied Electrochemistry》2009,39(5):601-607
In this work, cobalt from spent Li-ion batteries of cellular phones was recycled using electrochemical techniques. The efficiency,
structure and morphology of deposits were influenced by the pH solution and charge density. Maximum efficiency is obtained
for pH = 5.40 for all charge densities analyzed. The presence of the cobalt hcp phase for both pH solutions (5.40 and 2.70)
and charge density conditions (10.0 and 50.0 C cm−2) used in the electrodeposition process was detected by X-ray diffraction. The growth of the cobalt deposit is favored in
the crystallographic direction [002] for pH = 5.40 and in the direction [110] for pH = 2.70 when the charge density is 10.0 C cm−2. The [100] and [101] crystallographic directions of hcp phase were detected by X-ray diffractogram for both pH conditions
when the charge density was increased to 50.0 C cm−2. The potentiodynamic dissolution of the cobalt depends on its structural composition. 相似文献
82.
Carlos Sousa Nuno Mateus Artur M.S. Silva Ana M. González-Paramás Celestino Santos-Buelga Victor de Freitas 《Food chemistry》2007,102(4):1344-1351
A new pigment, resulting from the reaction between malvidin 3-glucoside and catechin in the presence of vanillin, was detected in a model solution. This newly formed anthocyanin-aryl-flavanol adduct was structurally characterized by 1D and 2D NMR and mass spectrometry, and its chromatic characteristics were studied by UV–Vis techniques. The new pigment was shown to have a wavelength of maximum absorption in the visible region (λmax) of 549 nm, conferring on it a purple colour, and a molar extinction coefficient value (ε) of 12,247 l · mol−1 · cm−1. 相似文献
83.
L. A. P. Freitas O. M. Dogan C. J. Lim J. R. Grace B. Luo 《Chemical Engineering Communications》2000,181(1):243-258
Tests were carried out with rectangular spouted bed columns of different thickness, i.e., front-to-back dimension, while holding the column width and air-entry slot width constant, to investigate the effects on spoul stability and bed hydrodynamics. For the three sizes of glass beads and one size of polyethylene beads examined, increasing the column thickness led to three-dimensional effects, such as formation of multiple spouts, and affected such hydrodynamics variables as the minimum spouting velocity, maximum spoutable bed depth and maximum pressure drop. 相似文献
84.
The ability of grape seed procyanidins to inhibit α-amylase activity was studied using a colorimetric method. This ability was found to be related with the average degree of polymerisation of the tested procyanidins. These interactions were further evaluated by fluorescence quenching, dynamic light scattering (DLS) and nephelometry, in order to understand the mechanisms by which they occur. A relationship between aggregate formation and enzymatic inhibition was observed. The interaction between procyanidins and enzyme involves a specific interaction as inferred from the calculated apparent bimolecular quenching constant in the fluorescence assays. Further experiments involved the determination of the effect of carbohydrates on the enzymatic inhibition observed. It was shown that pectin and arabic gum inhibited the formation of insoluble aggregates but were unable to restore fluorescence and activity to the enzyme. This suggests that these carbohydrates resulted in a decrease in turbidity due to the formation of a ternary complex with protein/polyphenol. 相似文献
85.
Ana Faria Diogo Pestana Rosário Monteiro Joana Oliveira Victor de Freitas Isabel Azevedo Conceição Calhau Nuno Mateus 《Food chemistry》2008
The aim of the present study was to investigate the influence of an anthocyanin extract (extract I), and two other derivative extracts (extracts II and III), which are being developed aiming to be further applied in the food industry, on intestinal uptake of organic cations. For this purpose, the effect of these compounds on 3H-MPP+ uptake was evaluated in Caco-2 cells (an enterocyte-like cell line derived from a human colonic adenocarcinoma). 相似文献
86.
87.
Analysis and behavior of steel storage drive-in racks 总被引:1,自引:0,他引:1
This work presents a general analysis of drive-in racks, evaluating the influence of each of their components on global stability. In this study, a full-scale test of a drive-in system was carried out. Finite element models were also developed to evaluate global structural stability and component influence on system behavior. The experimental and numerical results show that the connections and base plates have the most significant influence on the system's behavior. This influence is analyzed, an equation that predicts base plate resistance is then proposed, and its results are compared with experimental and numerical results. 相似文献
88.
<正>交异性钢桥面板改造的问题在于既有钢板与第二个钢板的粘结,以降低应力和增加正交异性钢板的使用寿命。通过试验和分析,对梁的弯曲性能进行参数研究。试验考虑不同厚度、温度和跨度的影响。从试验结果可见,应力降低与温度无关。最小化第二块钢板的厚度及最大化粘结层厚度,可降低重量,增加组合结构的刚度,这是最有效的解决方法。组合梁的弹性性能和屈服荷载取决于钢板的性能,温度的影响不显著。然而,粘结层的受剪最终导致梁的破坏,而粘结层的性能受温度的影响较大。 相似文献
89.
Frank S
S Rogerson Zelia Azevedo Nlia Fortunato Victor A
P de Freitas 《Journal of the science of food and agriculture》2002,82(11):1287-1292
1,3‐Dimethoxybenzene was identified by GC–O, GC–MS and Kovats indices (polar Supelcowax, 1709; non‐polar Rtx‐5MS, 1158) as a new volatile component of port wine. Sensory evaluation described this compound as having a sweet medicinal odour with hazelnut, resinous and woody notes. Respective threshold limits in model wine and port wine were 21 and 47 µg l?1. Quantitative analysis by GC–MS, using a selected characteristic ion (m/z 138), indicated that young port wines from the 1998 vintage contained up to 3 µg l?1 whereas ports from the 1999 vintage contained up to 20 µg l?1. © 2002 Society of Chemical Industry 相似文献
90.
Nuno Mateus Joana Oliveira João Pissarra Ana M. González-Paramás Julian C. Rivas-Gonzalo Celestino Santos-Buelga Artur M.S. Silva Victor de Freitas 《Food chemistry》2006
A new pyranoanthocyanin–vinylphenol pigment was detected in an aged Port red wine. The UV–Vis spectrum of this pigment was found to have a λmax of 538 nm that is bathochromically shifted from that of original anthocyanins, exhibiting a more purple hue in acidic solution. This newly formed pigment was synthesized in model solution through the reaction between malvidin 3-O-glucoside–pyruvic acid adduct and vinylphenol and its structure was assigned by NMR and mass spectrometry. This pigment is reported herein for the first time. 相似文献