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41.
C. Vidal-Valverde Marin Prodanov Isabel Sierra 《Zeitschrift für Lebensmitteluntersuchung und -Forschung A》1997,205(6):464-469
Lentils (Lens culinaris, var. vulgaris cultivar Magda-20) were naturally fermented for 96 h at different lentil flour concentrations (79, 150 and 221 g/l) and temperatures
(28, 35 and 42°C). During fermentation, samples were taken at 24-h intervals and the changes in thiamin (vitamin B1), riboflavin (vitamin B2) and total and available niacin (vitamin B3) were investigated. Preparation of the lentil flour suspension to be fermented (i.e. the process of mixing the flour and
sterilized tap water) caused an increase of the available niacin content in all batches, while changes in thiamin and riboflavin
content were related to the conditions in which the preparation of the suspensions was carried out. The whole natural fermentation
process (from the raw state to after 96 h of fermentation), either did not affect or produced a slight decrease in the thiamin
content of lentils. In contrast, riboflavin, available niacin and total niacin contents increased throughout the 96 h period,
which ended with a 35 – 82% increase of riboflavin, a 24 – 91% increase of available niacin and a 20 – 58% increase of total
niacin. The temperature during the fermentation procedure had significant effect on the levels of thiamin and riboflavin in
fermented lentils. To obtain lentil flours with an improved amount of riboflavin and available niacin with a minimum loss
of thiamin, the natural fermentation of lentils should be carried out for 96 h at 42°C and with a lentil flour concentration
of 221 g/l.
Received: 21 February 1997 相似文献
42.
Claudia Bernal Monica Mesa Ligia Sierra 《Materials science & engineering. C, Materials for biological applications》2012,32(6):1380-1385
Monomodal or bimodal porous silicas with large mesopores, constituted by particles or having a monolithic (block type) morphology, respectively, are synthesized using sodium silicate as siliceous species source, cetyltrimethylammonium bromide (CTAB) as pore template and ethyl acetate (EtAc) as pH modifier. The monomodal porosity is represented by 20–30 nm pores and the bimodal one by these pores and also macropores. These characteristics are modulated in function of the CTAB and EtAc concentrations as well as the pH and hydrothermal treatment. The role of these reagents upon the porosity is rationalized. The presence of high CTAB concentration and a rather low pH decreasing rate (function of EtAc concentration and hydrothermal treatment) are essential for having the already known bimodal mesoporous silicas (BMS). On the contrary a rather high pH decreasing rate promotes the formation of the new bimodal mesoporous–macroporous silicas (BMMS) synthesized in this work, where the EtAc also plays the role of emulsion forming agent. The hydrolytic stability of the synthesized silica under aqueous conditions, at different pH values, makes these silicas good candidates for application in different areas of catalysis, especially in the enzymatic one. 相似文献
43.
44.
Germán Sierra Gallego Joël Barrault Catherine Batiot-Dupeyrat Fanor Mondragón 《Catalysis Today》2010,149(3-4):365-371
LaNiO3 type perovskite was prepared by the “self-combustion” method and was used as catalyst precursor for the methane decomposition reaction at 600 and 700 °C. CH4 conversion reaches 80% at 700 °C and 65% at 600 °C using pure CH4. The yield of CNT and H2 were 2.2 gCNT g?1 h?1 and 8.2 L g?1 h?1 at 700 °C respectively after 4 h of reaction. When the reaction is prolonged to 22 h the catalytic activity decreases but the catalyst is still active, the production of hydrogen reaches 63.5 L (STP) per gram of catalyst and the production of MWCNT was equal to 17 g per gram of catalyst.Multi-wall carbon nanotubes were characterized by X-ray diffraction (XRD), surface area (BET), transmission electron microscopy (TEM), scanning electron microscopy (SEM), thermogravimetric analysis (TGA) and Raman spectroscopy. TEM micrographs showed that MWCNT longer than 20 μm were formed with inner diameters ranging from 5 to 16 nm and outer diameters up to about 40 nm.The results obtained here clearly show that the use of the perovskite LaNiO3 as catalytic precursor is very effective for the simultaneous production of carbon nanotubes and hydrogen. 相似文献
45.
In the last years the amount of information being transmitted through communication networks has increased, and this has lead to an increased use of security protocols. The implementations of security protocols do not accurately follow the standards and this causes many malfunctions and security flaws. In this paper we will analyze the different approaches followed by the scientific community to evaluate security protocols' implementations, and will also analyze the special characteristics of security protocols, in order to deduce which are the key points for such an evaluation, how they can be evaluated and also if existing evaluation techniques can be used. 相似文献
46.
47.
A new class of pulsed EPR experiments, based on FID-detected hole-burning, is introduced. A transient spectral hole burnt into an inhomogeneously broadened EPR line by means of a selective microwave pulse is shifted or broadened by different types of perturbations and is subsequently recorded in a single experiment via an FID following a nonselective microwave pulse. The proposed approach often exceeds corresponding electron spin-echo experiments with respect to sensitivity and resolution. A number of applications of the FID-detected hole-burning technique are discussed and the predicted features of the new experiments are verified by model calculations and experiments. 相似文献
48.
Excessive erosion of the labyrinth seal of a 110 MW geothermal turbine has been investigated. This study used computational fluid dynamics (CFD) and aims to identify one cause of erosion and a possible solution for substantially reducing it. The predictions were based upon a numerical calculation using a CFD model of the labyrinth seal with a water/steam flow containing hard solid particles and solved with a commercial CFD code: Fluent V5.0. The results confirmed the existence of flow conditions that play a major role in the rotor labyrinth seal erosion. Afterwards, the flow path was simulated with changes of rotor labyrinth seal geometry, which are indeed feasible of being implemented. The results confirmed that it is possible to reduce the erosion process by approximately 80% by incorporating a steam flow deflector in the fourth stage diaphragm, which changes the steam flow direction in the inlet zone to the rotor labyrinth seal channel, resulting in a reduction in steam volumetric mass flow and hard particle velocity by about 44%. 相似文献
49.
50.
RI Griffiths CL Hyman SI McFarlane GR Saurina JE Anderson T O'Brien C Popper MM McGrath RJ Herbert MF Sierra 《Canadian Metallurgical Quarterly》1998,19(10):747-753
OBJECTIVE: To compare resource use by diagnostic outcome among hospital admissions during which tuberculosis (TB) was suspected. DESIGN: Retrospective study based on chart review and microbiology laboratory data. SETTING: The department of medicine in a municipal hospital serving central Brooklyn, New York. PARTICIPANTS: We identified all adult admissions in 1993 during which TB was suspected. We assigned each admission to one of four mutually exclusive groups defined by the results of microbiological tests (acid-fast bacilli [AFB] smear and culture): culture-positive and smear-positive (C+S+); culture-positive and smear-negative (C+S-); culture-negative and smear-positive (C-S+); or culture-negative and smear-negative (C-S-). Each admission was divided into two separate periods to which the utilization of medical resources was assigned: the diagnostic and the postdiagnostic periods, which were separated by the date of receipt of the first definitive culture report. RESULTS: Data on 519 admissions (93 C+S+; 57 C+S-; 30 C-S+; and 339 C-S-) were analyzed. Although C+S+ were more likely than other groups to have an admitting diagnosis of TB, approximately one quarter of the admissions without TB (C-S+, C-S-) were admitted with the principal diagnosis of TB. For the four groups, C+S+, C+S-, C-S+, and C-S-, the respective rates of TB isolation and anti-TB treatment, and median lengths of isolation were 98%, 87%, and 34 days; 74%, 74%, and 7 days; 83%, 83%, and 15 days; and 44%, 29%, and 0 days. During the diagnostic period, the rate and length of isolation were similar in the AFB-smear-positive groups (C+S+ and C-S+). We estimated that admissions without culture-proven TB (C-S+ and C-S-) accounted for 3,174 (36%) of the 8,712 days of TB isolation expended and for 65% of the 16,671 days of anti-TB treatment. The vast majority of this resource consumption (2,737 [86%] of 3,174 days of isolation) occurred during the diagnostic period before a definitive culture result was known. CONCLUSIONS: Our results suggest that prolonged diagnostic uncertainty and misclassification of cases due to false-positive and false-negative smears are associated with substantial medical-resource consumption. New diagnostic modalities that reduce the period of diagnostic uncertainty could reduce the utilization of resources later found to be unnecessary. 相似文献