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991.
Comparison of HPLC and GLC methodologies for determination of glucosinolates using reference material 总被引:1,自引:0,他引:1
The reference material rapeseed of known glucosinolate composition, was analysed by HPLC and GLC and two commercially available
glucosinolates (glucotropaeolin and sinigrin) were used as internal standards. The HPLC method enabled determination of 11
different glucosinolates (as desulphoglucosinolates) that occur in the rapeseed. Only seven glucosinolates (as trimethylsilylated
desulphoglucosinolates) were separated by GLC. The latter method did not allow the determination of methylsulphinylalkyl glucosinolates
(glucoiberin, glucoraphanin and glucoallysin) and did not separate optical isomers of 2-hydroxy-3-butenyl glucosinolate (progoitrin
and epi-progoitrin). Statistical evaluation of data (t-test, F-test) revealed no significant differences between the tested methods at the 95% confidence level. The advantages and disadvantages
of both widely used chromatographic methods are discussed.
Received: 26 May 1997 / Revised version: 11 July 1997 相似文献
992.
Petr Kocna Thomas Mothes Viktor Krchnák Premysl Fric 《Zeitschrift für Lebensmitteluntersuchung und -Forschung A》1991,192(2):116-119
Summary The tendency to form a-turn in-gliadin was estimated using the B-cell determinant prediction program based on the Chou and Fasman probability of-turn formation. Six sequences possessing a high probability of-turn formation were found. A statistically high agreement was found between these six sequences and three areas in-gliadin with the occurrence of Pro-Ser-Gln-Gln sequence which has recently been considered responsible for toxicity in coeliac disease. By means of solid-phase synthesis seven peptides were obtained covering the above-mentioned regions. Their toxicity was tested using the fetal chick duodenum. The results support the suggestion that peptides containing the sequences Pro-Ser-Gln-Gln and Gln-Gln-Gln-Pro may be involved in the pathogenesis of coeliac disease.
Beziehung zwischen der Gliadin-Peptid-Struktur und ihr Einfluß auf den fetalen Kückendarm
Zusammenfassung Die Tendenz zur Bildung einer-Umwandlung im-Gliadin wurde bei Anwendung eines mathematischen Programms zur Vorhersage von B-Zelldeterminanten bestimmt, welches auf der Wahrscheinlichkeit der-Umwandlung nach Chou und Fasman basiert. Es wurden 6 Sequenzen gefunden, die eine hohe Wahrscheinlichkeit für die Bildung von-Umwandlungen aufwiesen. Zwischen diesen 6 Sequenzen und 3 Regionen im-Gliadin mit der Sequenz Pro-Ser-Gln-Gln, die kürzlich als verantwortlich für die Toxizität bei Cöliakie angesehen wurden, konnte eine statistisch gesicherte Beziehung gefunden werden. Mittels Festphasensynthese wurden 7 Peptide erhalten, die die oben genannten Regionen überdeckten. Ihre Toxizität wurde im fetalen Kückendarm getestet. Die Ergebnisse weisen darauf hin, daß Peptide, welche die Sequenz Pro-Ser-Gln-Gln und Gln-Gln-Gln-Pro enthalten, an der Pathogenese der Cöliakie beteiligt sein könnten.相似文献
993.
The Conceptual Design of a Radiant Chamber and Preliminary Optimization of a Process Tubular Furnace
Zdeněk Jegla 《传热工程》2013,34(6):50-57
The design procedure of a process tubular furnace (or fired heater) can generally be divided into three design stages: the preliminary design of furnace, a detailed thermal and hydraulic simulation of the furnace, and final design solution, and the mechanical solution of the furnace (stress analysis, drawings preparation, etc.). The first design stage (the preliminary design of the furnace and cost prediction) is usually connected with a proposal for the customer when only the basic process and furnace design data are usually known. In this design stage, it is appropriate for the furnace designer to not have much detail for a reliable design method. The procedure for the preliminary design of a radiant chamber is usually a main part of such a design method because the radiant chamber represents a basic and dominant part of the modern process tubular furnace. The conceptual (or preliminary) design of the radiant chamber makes up the main part of this process. The presented method is based on standard, time-tested design methods (e.g., the Lobo-Evans method and Belokon's method). It is shown how these standard global design methods can be (for common operating conditions) suitable, generalized, and simplified. It allows for the purpose of the conceptual radiant chamber design the arrangement of the basic heat transfer equation for the radiant chamber. The derived form of the heat transfer equation then allows one to obtain basic process and geometrical radiant chamber characteristics of the given furnace type (cylindrical, box, etc.) iteratively. A developed radiant chamber calculation connected with standard procedures for the design of the furnace convection parts and stack (together with cost predictions) is used, and the method for a quick preliminary evaluation of the influence of the main design and process furnace parameters (dimensions of radiant chamber and convection parts, average heat flux to radiant tubes, absorbed heat in radiant chamber and convection part of furnace, stack size, and fuel consumption) for the total costs was developed. It allows the optimization of the furnace from an investment, operating, or total cost point-of-view in the preliminary design stage of the furnace. The developed method can also be used for the effective solution of the furnace integration into the process. The application of the developed method is demonstrated through a case study—the optimum design of a furnace for a crude atmospheric distillation unit. 相似文献
994.
Zdeněk Jegla 《传热工程》2013,34(6):546-555
Tube coil arrangement dominantly influences the thermal-hydraulics characteristics of furnace and its economy. The presented method is based on standard long-used design methods (Lobo-Evans method, Belokon method). It is shown how these standard global design methods can be (for common-operating conditions) suitably generalized and simplified. It allows (for the purpose of optimum design of coil arrangement) to arrange the basic heat transfer equation for radiant chamber. In connection with investment cost relations for individual furnace subsystems (tube coil, burners, lining, etc.) and operating cost relations (fuel consumption, fluid pumping cost), the final objective function of total cost can be obtained. This objective function then allows finding the optimum coil arrangement from minimum total cost point of view. Moreover, the obtained results allow one to formulate some general recommendations suitable for furnace designers. The developed method can be used for the individual solution of a radiation-type of tubular furnaces and also for the first (preliminary) design stage usually connected with a proposal for the customer when only basic process and furnace design data are known. The developed method can be also used for the effective solution of the integration of radiation furnaces into processes. The application of the developed method is demonstrated through a case study—the optimum arrangement of coil in a gas plant regeneration furnace. 相似文献
995.
This editorial provides an overview of a special issue dedicated to the 11th Conference on Process Integration, Modeling, and Optimization for Energy Saving and Pollution Reduction—PRES 2008. Nine papers have been selected and peer-reviewed covering important subjects of heat transfer engineering. They focus on recent development of various features of heat transfer equipment design and optimization. This issue of Heat Transfer Engineering is the sixth special journal issue dedicated to selected papers from PRES conferences [1, 2, 3, 4, 5]. 相似文献
996.
Elif Büyük Öğüt 《Numerical Heat Transfer, Part A: Applications》2013,63(11):900-921
Analysis of heat and fluid flow transport due to natural convection and magnetohydrodynamic (MHD) flows in a square enclosure with a finite length heater has been performed using the differential quadrature (DQ) technique. The heater with constant heat flux is located on the bottom wall of the enclosure and isothermal boundary conditions are applied to the right vertical wall while the remaining walls are adiabatic. The effects of heater length (0.2 ≤ ? ≤ 0.8), heater location (0.1 ≤ c/L ≤ 0.9), and direction of magnetic force (0° ≤ φ ≤ 90°) for different values of Grashof (103 ≤ Gr ≤ 106) and Hartmann numbers (0 ≤ Ha ≤ 100) on the heat and fluid flow in the enclosure are studied. According to the results obtained, heat transfer reduces when increasing the Hartmann number. The rate of reduction is higher for high values of Grashof number. The heat transfer rate for the heater closer to the cold wall is considerably higher than the heaters far from the right wall. 相似文献
997.
This editorial provides an overview of a special issue dedicated to the 7th conference on Process Integration, Modeling and Optimization for Energy Saving and Pollution Reduction—PRES 2004. Eight papers have been selected and peer-reviewed covering various subjects of heat transfer engineering, focusing on the recent development of various features of heat transfer equipment design and optimization. This is the fourth special issue of Heat Transfer Engineering dedicated to selected contributions from PRES conferences [1, 2, 3]. 相似文献
998.
This study presents numerical analyses of transient temperature and thermally induced stress distributions in a stationary hollow steel disk partially heated by a moving uniform heat source from its outer surface under stagnant ambient conditions. The moving heat source applied on a certain angular segment of the processed surface rotates with a constant angular speed (ω). The peak levels of the temperature gradients and the thermal stress ratios at the heated segments do not rise very much after 2–3 cycles. When the value of ω is increased, the maximum effective thermal stress ratio can be decreased in a considerable amount. 相似文献
999.
Quang D Tran Wouter H Hendriks Antonius FB van der Poel 《Journal of the science of food and agriculture》2008,88(9):1487-1493
Extrusion cooking is commonly used to produce dry pet foods. As a process involving heat treatment, extrusion cooking can have both beneficial and detrimental effects on the nutritional quality of the product. Desirable effects of extrusion comprise increase in palatability, destruction of undesirable nutritionally active factors and improvement in digestibility and utilisation of proteins and starch. Undesirable effects of extrusion include reduction of protein quality due to e.g. the Maillard reaction, decrease in palatability and loss of heat‐labile vitamins. Effects of extrusion processing on the nutritional values of feeds for livestock have been well documented. Literature results concerning effects of extrusion on dry pet foods, however, are scarce. The present review discusses the results of studies investigating the impact of extrusion cooking on the nutritional quality of dry pet foods. Copyright © 2008 Society of Chemical Industry 相似文献
1000.
The hypothetical impact structure in the Saginaw Bay (Michigan, USA, Lake Huron) has been tested by the gravity data derived from the recent gravity field model EIGEN 6C4 (expanded to degree and order 2190, with ground resolution of ~9?km). The following gravity field aspects were used: the gravity disturbances/anomalies, second derivatives of the disturbing potential (Marussi tensor), two of three gravity invariants, their specific ratio (known as 2D factor), the strike angles, and the virtual deformations. These gravity aspects are sensitive in various ways to the underground density contrasts. For the Saginaw Bay area, we confirm that we do not see any typical impact crater in terms of gravity disturbance or the radial second order derivative, possibly because of the thick layer of the ice located at the place and time of the impact. But the “combed” strike angles (one type of the gravity aspects we use) disclose a trace of high pressure to the SE/S/SW of the Bay and may be due to an impacting body. Thus, we provide circumstantial evidence of the Younger Dryas impact hypothesis. 相似文献