New steroid dimer, ethylene bridged bis-carbamate (3) was synthesized from cholic acid in few steps. Complexes of 3 with lanthanum(III) and calcium(II) nitrates were prepared in reaction of 3 and appropriate metal salts. They were characterized by spectral data (Infrared (IR), ultraviolet-visible (UV/Vis), nuclear magnetic resonance (NMR) spectroscopy and fast-atom bombardment (FAB), electrospray (ESI) and matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS)) and elemental analysis. The similarity in complexing behavior of steroidal dimer toward calcium and lanthanum ions was observed. 相似文献
High purity aluminum (Al) sheets were used to produce ordered nanoporous alumina templates by two step anodization technique using oxalic acid as electrolyte. Electrochemical polishing of Al sheets was performed in order to study the surface roughness influence on the pore roundness of the alumina templates. The templates were submitted to progressive reduction of anodizing voltage (electrochemical etching) to thin the Al2O3 barrier layer on the bottom of the pores, and to chemical etching to widen the diameter of the pores. The pore diameter and porosity increase linearly with the chemical etching time, while interpore distance, circularity, pore density and pore distribution do not change. Electropolished Al substrates produce nanoporous Al2O3 templates with more circular pores, and the Al2O3 barrier layer at the Al2O3/Al interfaces is completely removed after the electrochemical and chemical etching processes. 相似文献
The self-assembled formation of a one-dimensional lanthanum salicylaldimine coordination polymer was proved by the X-ray diffraction analysis of new lanthanum(III) nitrate complex containing N,N'-bis(salicylidene)-1,5-pentanediamine ligand (H2L). It was obtained in situ in a one-step, metal-templated condensation of salicylaldehyde with 1,5-pentanediamine (cadaverine, biogenic polyamine) and characterized by microanalysis and spectroscopic (IR, ESI-MS, UV-Vis, and 1H NMR) data. The [La(NO3)3(μ-H2L)2]∞ complex displayed 10-coordinate distorted bicapped dodecahedron geometry with unusual coordination pattern of undeprotonated salicylaldimines which acted as μ-bridging ditopic ligands using exclusively the oxygens as donor atoms with the nitrogen atoms not being involved in the coordination environment. 相似文献
Abstract The effect of pretreatment preceding convective drying and the mode of drying on reconstitution properties of dried onion was investigated. Soaking in water, dipping in starch solution and osmotic dewatering were used as pre‐drying treatments. Convective drying at 60, 70, and 80°C, infrared drying and convective drying assisted with microwaves were applied to remove water from raw onion. Rehydration was done in water at room temperature and in boiling water. In general amount of absorbed water and increase in mass during rehydration, both were higher for pretreated material than those observed with dried raw onion. The mode of drying seemed to affect the course of rehydration of dried onion, and to improve its reconstitution properties. However, this was observed at room temperature rehydration only. Pre‐drying treatment followed by convection drying affected much stronger reconstitution properties of dried onion than the mode of drying. 相似文献
The effect of a green tea marinade on the formation of heterocyclic aromatic amines (HAs) was examined in pan-fried beef cooked at 180–200 °C for 4 min each side. Different marinating times were assayed and unmarinated samples cooked in similar conditions provided reference HAs levels. A green tea marinade catechin rich was prepared taking 1 g of green tea and infusing with 125 ml of boiling tap water during 10 min. Four HAs were quantified in unmarinated and marinated meat samples during 1, 2, 4 and 6 h at 5 °C. Compared with the unmarinated samples, marinating in green tea resulted in a significant decrease (p < 0.05) of levels of PhIP and AαC. Person correlation indicated that the reduction of the levels of these HAs in meat marinated with the increase of marinating time was significant (respectively, r = −0.799, p < 0.0001; r = −0.631, p < 0.05). No reduction was observed for 4,8-DiMeIQx and MeIQx. 相似文献
The present study is aimed at quantifying the flame radiosity vertical profile and gas temperature in moderate to high intensity spreading fires in shrubland fuels. We report on the results from 11 experimental fires conducted over a range of fire rate of spread and frontal fire intensity varying respectively between 0.04–0.35 m s−1 and 468–14,973 kW m−1. Flame radiosity, or radiant emissive power, and gas temperatures were measured with narrow angle radiometers and fine wire thermocouples located at three different heights in the flames, 0.6, 1.1 and 1.6 m above ground. Measured peak radiosity within the visual flame region (reaction zone and free flame) varied between 41 and 176 kW m−2. Measurements within the intermittent flame region above the visually estimated average flame height varied between 10 and 30 kW m−2. The flame vertical radiometric profile was characterized by a uniform area within the reaction zone and lower free flame, and a decrease in radiosity with height as the measurements approach the flame tip. 相似文献
Recent efforts have focused on identifying multidisciplinary teams and detecting co-Authorship Networks based on exploring topic modeling to identify researchers’ expertise. Though promising, none of these efforts perform a real-life evaluation of the quality of the built topics. This paper proposes a Semantic Academic Profiler (SAP) framework that allows summarizing articles written by researchers to automatically build research profiles and perform online evaluations regarding these built profiles. SAP exploits and extends state-of-the-art Topic Modeling strategies based on Cluwords considering n-grams and introduces a new visual interface able to highlight the main topics related to articles, researchers and institutions. To evaluate SAP’s capability of summarizing the profile of such entities as well as its usefulness for supporting online assessments of the topics’ quality, we perform and contrast two types of evaluation, considering an extensive repository of Brazilian curricula vitae: (1) an offline evaluation, in which we exploit a traditional metric (NPMI) to measure the quality of several data representations strategies including (i) TFIDF, (ii) TFIDF with Bi-grams, (iii) Cluwords, and (iv) CluWords with Bi-grams; and (2) an online evaluation through an A/B test where researchers evaluate their own built profiles. We also perform an online assessment of SAP user interface through a usability test following the SUS methodology. Our experiments indicate that the CluWords with Bi-grams is the best solution and the SAP interface is very useful. We also observed essential differences in the online and offline assessments, indicating that using both together is very important for a comprehensive quality evaluation. Such type of study is scarce in the literature and our findings open space for new lines of investigation in the Topic Modeling area.