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101.
Lipidic extracts of Spodoptera littoralis pheromone glands submitted to acid methanolysis using: (i) sulfuric acid/methanol/benzene (0.1∶4∶2, by vol) at 90°C for 1
h; (ii) 12 N HCl/methanol (1∶2; vol/vol) at 90°C for 1 h, or (iii) 14% BF3-MeOH at 90°C for 1 h did not reveal the presence of either 11- or 12-hydroxytetradecanoic acid in the extracts, as concluded
from the gas chromatography-mass spectrometry analyses. Under the above methanolysis conditions, a synthetic sample of methyl
(14, 14, 15-2H3) 12-hydroxytetradecanoate remained unaltered. These results may indicate that formation of (E)-11-tetradecenoic acid from tetradecanoic acid does not occur in the pheromone gland by dehydration of an intermediate hydroxyacid.
Acid methanolysis of a lipidic extract using BF3-MeOH led to the formation of a mixture of methoxy fatty acid methyl esters, identified by gas chromatography-mass spectrometry.
These methoxy derivatives should arise from BF3-catalyzed addition of methanol to the double bond of the natural monounsaturated fatty acyl derivatives present in the gland.
Thus, under the same conditions, a synthetic sample of methyl (Z)-11-tetradecenoate was partially transformed into methyl
11-methoxytetradecanoate and methyl 12-methoxytetradecanoate. This reaction might be a useful alternative procedure to obtain
methoxy derivatives of olefins, which are very helpful for the structural characterization of the parent alkenes. 相似文献
102.
Cerium oxide thin films obtained by cathodic electrodeposition on 2024 aluminium alloy have been studied. The coatings, obtained with electrochemical deposition, offer an effective corrosion protection and require a lower deposition time when compared to chemical conversion coatings. The coatings were obtained at room temperature by deposition from CeCl3/H2O2 aqueous solutions and the influence of several parameters (CeCl3 concentration, H2O2 concentration, deposition time, current intensity) on the corrosion resistance was studied. The composition, morphology and microstructure of the films have been characterized by SEM, XPS and AFM. The corrosion resistance was investigated through potentiodynamic tests in 3% NaCl solution. 相似文献
103.
We have applied the inductive learning of statistical decision trees and relaxation labeling to the Natural Language Processing (NLP) task of morphosyntactic disambiguation (Part Of Speech Tagging). The learning process is supervised and obtains a language model oriented to resolve POS ambiguities, consisting of a set of statistical decision trees expressing distribution of tags and words in some relevant contexts. The acquired decision trees have been directly used in a tagger that is both relatively simple and fast, and which has been tested and evaluated on the Wall Street Journal (WSJ) corpus with competitive accuracy. However, better results can be obtained by translating the trees into rules to feed a flexible relaxation labeling based tagger. In this direction we describe a tagger which is able to use information of any kind (n-grams, automatically acquired constraints, linguistically motivated manually written constraints, etc.), and in particular to incorporate the machine-learned decision trees. Simultaneously, we address the problem of tagging when only limited training material is available, which is crucial in any process of constructing, from scratch, an annotated corpus. We show that high levels of accuracy can be achieved with our system in this situation, and report some results obtained when using it to develop a 5.5 million words Spanish corpus from scratch. 相似文献
104.
The article discusses the use of positive and negative reasons when preferences about alternative options have to be considered. Besides explaining the intuitive and formal situations where such a bipolar reasoning is used, the article shows how it is possible to generalize the concordance/discordance principle in preference aggregation and apply it to the problem of aggregating preferences expressed under intervals. © 2008 Wiley Periodicals, Inc. 相似文献
105.
The effects of high hydrostatic pressure (HHP: 0, 400, and 600 MPa) and freezing temperature (-15° vs. -35°C) were evaluated on the quality and microbial inactivation of cured pork carpaccio. Samples treated with HHP resulted in lighter and yellower color, higher Chroma, shear force, scores for pink color, cooked and gel appearance, incidence of iridescence, lower scores for brightness and raw meat appearance and lower levels of lactic acid bacteria and psychrotrophs during shelf life compared with untreated samples (P<0.05). Treating carpaccio at -35°C resulted in a darker color and a more tender carpaccio with a higher rating for crumbliness and lower rating for fibrousness and chewiness compared with -15°C (P<0.05). While HHP is effective in microbial inactivation and shelf life extension of pork carpaccio, product quality may be decreased due to lower tenderness and poorer appearance. However, HHP in combination with low freezing temperature can be used successfully to deliver high quality pork carpaccio with extended shelf life to the ready-to-eat market. 相似文献
106.
Fàbrega E Manteca X Font J Gispert M Carrión D Velarde A Ruiz-de-la-Torre JL Diestre A 《Meat science》2004,66(4):47-787
Barrows (n=164) and gilts (n=249) from crosses of a Pietrain homozygous halothane recessive (Pi nn) and two Pietrain homozygous dominant (Pi NN-a and Pi NN-b) sire lines with Landrace×Large White NN sows, were used to study the effect of terminal sire and pre-slaughter treatment on meat quality and animal welfare. The pigs from each of the two farms where they were finished were delivered to the abattoir in two batches differing in the pre-slaughter conditions. A total of 90 pigs (54 NN and 36 Nn) were assigned to a long pre-slaughter treatment (6 h transport and 14.5 h lairage) and 89 (57 NN and 33 Nn) to a short pre-slaughter treatment (4.5 h transport and 2.5 h lairage) in Farm 1, and 118 (65 NN and 53 Nn) to the long (7 h transport and 14 h lairage) and 114 (66 NN and 48 Nn) to the short pre-slaughter treatment (1.5 h transport and 2 h lairage) in Farm 2. In Farm 1, heart rate of 3 NN and 3 Nn gilts was recorded throughout loading and transport and blood samples from 5 NN and 5 Nn were collected before loading and after transport to measure cortisol, creatine phosphokinase (CPK) and lactate dehydrogenase (LDH). Carcasses were classified and commercial cutting was carried out. At 24 h, meat quality was assessed on the Longissimus thoracis muscle by measuring electrical conductivity (PQM), colour (Minolta CR 200 and Japanese scale), pHu and drip losses. Halothane carriers showed a higher mean heart rate and higher increase in CPK levels (P<0.05) after transport in the short pre-slaughter treatment than halothane free pigs. No effect was observed in cortisol or LDH values. Pi NN-a sired pigs had a higher live and carcass weight (P<0.001) and loin depth (P<0.05), but lower killing out percentage (P<0.01) and leg yield (P<0.01) compared with the progeny of the other two terminal sires. Gilts were leaner (P<0.001), had a higher killing out percentage (P<0.001) and higher yields of primal cuts (P<0.001) compared with barrows. Pi nn sired pigs had poorer meat quality (higher PQM values in both farms, P<0.01) than Pi NN-a sired pigs. Long pre-slaughter treatment resulted in darker meat (P<0.01) in both farms and in higher pHu (P<0.001) in Farm 1 than short pre-slaughter treatment. Conversely, pigs subjected to the short pre-slaughter treatment showed higher PQM values (P<0.01) in Farm 1 and higher PSE percentage (P<0.05) in both farms compared to the ones subjected to the long pre-slaughter treatment. These results suggest that Pietrain halothane free sire lines could produce similar results on carcass quality to halothane carriers, without compromising meat quality and welfare. 相似文献
107.
Rivia D. A. Amaral Benedito C. Benedetti Montserrat Pujolà Isabel Achaerandio Mara L. B. Bachelli 《Food and Bioprocess Technology》2016,9(10):1794-1801
The effect of ultrasound (US) (40 kHz, 200 W, 3 min), blanching (85 °C, 3.5 min), and the combination of both methods was evaluated on the quality of vacuum-packaged potato strips stored at 3 ± 1 °C for up to 10 days. For this study, two cultivars of potatoes were assessed. For blanched Agata samples, the lightness (L*) decreased over 12 % (p < 0.05). Moreover, their hue increased up to 100, obtaining lesser yellow potato strips. In contrast, US did not affect the hue values. The losses of firmness of blanched potato strips were notable (35 % for Agata and 51 % for Agria), whereas US did not change this property (p < 0.05). Nevertheless, no significant differences were found in the total starch content at 10 days. Agata and Agria showed different metabolic behaviors of sucrose in the refrigerated storage. Therefore, Agria cultivar retained better color after frying. These results suggest that US had less impact on color and improve the firmness in vacuum-packaged potato strips with no added chemicals. 相似文献
108.
Factors influencing the soil-air partitioning and the strength of soils as a secondary source of polychlorinated biphenyls to the atmosphere 总被引:2,自引:0,他引:2
Cabrerizo A Dachs J Moeckel C Ojeda MJ Caballero G Barceló D Jones KC 《Environmental science & technology》2011,45(11):4785-4792
Soils are a major reservoir of persistent organic pollutants, and soil-air partitioning and exchange are key processes controlling the atmospheric concentrations and regional fate of pollutants. Here, we report and discuss the concentrations of polychlorinated biphenyls (PCBs) in soils, their measured fugacities in soil, the soil-air partition coefficients (K(SA)) and soil-air fugacity gradients in rural background areas of N-NE Spain and N-NW England. Four sampling campaigns were carried out to assess seasonal and daily variability and differences between sampling sites. K(SA) values were significantly dependent on soil temperature and soil organic matter quantity, and to a minor extent organic matter type. All the PCB congeners in the soil are close to equilibrium with the atmosphere at rural Ebro sites, but soil fugacities tend to be higher than ambient air fugacities in early and late summer, consistent with the influence of temperature on soil-air partitioning. Therefore, during warm periods, soils increment their strength as secondary sources to the atmosphere. The mixture of PCBs found in the atmosphere is clearly strongly influenced by the mixture of PCBs which escape from soil, with significant correlations between them (R(2) ranging between 0.35 and 0.74 and p-level <0.001 for the Ebro sampling sites). Conversely, the close-to-equilibrium to net sink status of rural UK sites, suggest a close coupling of air and soil concentrations, but it is not possible to elucidate the importance of these soils as secondary sources yet, and presumably there are still significant primary sources to the regional/global environment. 相似文献
109.
110.
Valente P Forastiere F Bacosi A Cattani G Di Carlo S Ferri M Figà-Talamanca I Marconi A Paoletti L Perucci C Zuccaro P 《Tobacco control》2007,16(5):312-317