171 resultados para uf
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Contiene: Guía didáctica y Cuaderno de trabajo
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A study of galacto-oligosaccharides (GOS) synthesis from lactose with beta-galactosidase from Kluyveromyces lactis (Maxilact(R) L2000) was carried out. The synthesis was performed using various initial lactose concentrations ranging from 220 to 400 mg/mL and enzyme concentrations ranging from 3 to 9 U/mL, and was investigated at 40degreesC and pH 7, in a stirred-tank reactor. In the experimental range examined, the results showed the amount of GOS formed depended on lactose concentration but not on enzyme concentration. Galactose was a competitive inhibitor, while glucose was a non-competitive inhibitor. In a further study, a laboratory-scale reactor system, fitted with a 10-kDa NMWCO composite regenerated cellulose membrane, was used in a continuous process. The reactor was operated in cross-flow mode. The effect of operating pressures on flux and productivity was investigated by applying different transmembrane pressures to the system. The continuous process showed better production performance compared to the batch synthesis with the same lactose and enzyme concentrations at 40degreesC, pH 7. Comparison of product structures from batch and continuous processes, analyzed by HPAEPAD and methylation analysis, showed similarities but differed from the structures found in a commercial GOS product (Vivinal(R)GOS). (C) 2004 Wiley Periodicals, Inc.
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B. subtilis under certain types of media and fermentation conditions can produce surfactin, a biosurfactant which belongs to the lipopeptide class. Surfactin has exceptional surfactant activity, and exhibits some interesting biological characteristics such as antibacterial activity, antitumoral activity against ascites carcinoma cells, and a hypocholesterolemic activity that inhibits cAMP phosphodiesterase, as well as having anti-HIV properties. A cost effective recovery and purification of surfactin from fermentation broth using a two-step ultrafiltration (UF) process has been developed in order to reduce the cost of surfactin production. In this study, competitive adsorption of surfactin and proteins at the air-water interface was studied using surface pressure measurements. Small volumes of bovine serum albumin (BSA) and β-casein solutions were added to the air-water interface on a Langmuir trough and allowed to stabilise before the addition of surfactin to the subphase. Contrasting interfacial behaviour of proteins was observed with β-casein showing faster initial adsorption compared to BSA. On introduction of surfactin both proteins were displaced but a longer time were taken to displace β-casein. Overall the results showed surfactin were highly surface-active by forming a β-sheet structure at the air-water interface after reaching its critical micelle concentration (CMC) and were effective in removing both protein films, which can be explained following the orogenic mechanism. Results showed that the two-step UF process was effective to achieve high purity and fully functional surfactin.
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Thermosetting resins are very important in the production of MDF panels. They act as an adhesive in the process of compacting and consolidating the fiberboard. Thermoset resins commonly used in this process are based resin urea formaldehyde (UF) and melamine formaldehyde (MF). The first has a higher demand due to its low cost and good performance in meeting the specifications and standards. The second has a high cost compared to MF resin, but adds greater value to the MDF panel, because it gives greater moisture resistance. The process of manufacture of MDF boards was briefly presented in this study to facilitate the understanding of the work. Samples of thermosetting resins (UF and MF) were subjected to physical-chemical seeking to relate these results to the technological performance presented by their respective samples of MDF boards. Two other samples of MDF panels were subjected to physical and mechanical tests. Results were analyzed and related to the award of their respective thermoset resin. Instruments like Dahmos Trend Manager ® and Grecon Dax 5000 and TG - DSC analysis were used in this study to assist in the analysis of the results. It was observed that the results of the analysis of thermosetting resins were within the specified. Such resins do not directly influence the technological tests provided by the MDF panels, but it has been found that the process variables such as humidity and fiber production rate interfere with the performance of the resin accelerating the reaction and therefore their influence on the physical-mechanical properties of the panels MDF. Samples of MDF panels with UF and MF met all the specifications required by the Brazilian standard with regard to the technological quality. The increased demand for UF resin market is justified by the service specifications...
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Welsch (Projektbearbeiter): Politische Satire: Aufdeckung eines Komplotts, den Berlinern die "revolutionären Grillen" durch Kappung der Weißbierzufuhr auszutreiben. "Lange kann es nicht dauern, so verfliegt in dem letzten Rülpse der letzte revolutionäre Gedanke, ... denn das [fehlende Bier] ist schlimmer als Aushungern und Bombardiren."
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Welsch (Projektbearbeiter): Appell an die Mannschaftsdienstgrade in der Preußischen Armee: Ziel des Volkes ist es mitnichten, die Fürsten davonzujagen. Das Volk hat seit den Befreiungskriegen schrittweise Mündigkeit erlangt und wird sich " ... nich mehr wie'n dummer Junge schuhriejeln laaßen". Warnung vor reaktionären Offizieren: " ... zeigt, deß Ihr Söhne des Volks, ... deß Ihr brave Preußsche Soldaten un keene jedungene Dodtschläger nich seid!"
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Welsch (Projektbearbeiter): Strafpredigt an das Gardekorps. Hintergrund: tätliche Angriffe von Soldaten des Gardekorps gegen Mitglieder des Potsdamer Politischen Klubs (wahrscheinlich 25. September 1848)
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Welsch (Projektbearbeiter): Satirische Kommentierung der Rolle der Berliner Bürgerwehr in Form einer Strafpredigt der Madame Bullrich an ihren Gatten Ludewig: Aufgabe der Berliner Bürgerwehr kann es nicht sein, sich dem üblichen militärischen Drill zu unterziehen. Warnung vor offenbaren Bestrebungen, die Bürgerwehr zum Instrument der Reaktion umzufunktionieren
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Welsch (Projektbearbeiter): Bekanntmachung der Versöhnung Aujust Buddelmeyers (Adalbert Cohnfelds) mit Otto Graf Schlippenbach, der zwar den Fehler hat, "deß er Jraf is", dessen Bemühungen zur Lösung der sozialen Frage ihn jedoch zum faktischen Verbündeten der Demokraten machen
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Welsch (Projektbearbeiter): Die erst im März errungene Freiheit wird Schritt für Schritt eingeengt und ausgehöhlt. Hintergrund: mit der Bürgerwehr zuvor nicht abgestimmter Einmarsch von Truppenteilen nach Berlin zur Unterstützung der im Juli gegründeten Konstabler-Schutzmannschaft
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Welsch (Projektbearbeiter): Satire auf den Werdegang der sehr weitgehenden und radikalen Forderungen der Berliner Volksredner, der immer nach demselben Muster abläuft: die Forderungen werden auf einer Volksversammlung vom Redner formuliert und von der Versammlung gutgeheißen. Darauf wird eine Deputation gebildet, die die fraglichen Forderungen der Nationalversammlung als Petition übergibt. Nach dem Empfang der Deputation durch die Nationalversammlung macht sich der Abgeordnete D'Ester die Petition zu eigen und übergibt sie dem Präsidenten, der sie in die Kommissionen verweist. Die Kommissionen wiederum beraten darüber und erstatten am nächsten Tag Bericht. "Un so war et, un so is et, un so wird et bleiben." Geschildert vor dem Hintergrund der Niederschlagung der Wiener Revolution am Beispiel einer - fiktiven - Rede von Adolph Friedrich Karbe
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Welsch (Projektbearbeiter): Zustimmende Kommentierung der Demonstration vom 5. Oktober 1848 gegen das Bürgerwehrgesetz; vorgetragen in einem Ton gespielter Entrüstung