The effect of water on the selective catalytic reduction (SCR) of nitric oxide with ammonia over alumina supported with 2–15 wt.-% manganese oxide was investigated in the temperature range 385–600 K, with the emphasis on the low side of this temperature window. Studies on the effect of 1–5 vol.-% water vapour on the SCR reaction rate and selectivity were combined with TPD experiments to reveal the influence of water on the adsorption of the single SCR reactants. It turned out that the activity decrease due to water addition can be divided into a reversible inhibition and an irreversible deactivation. Inhibition is caused by molecular adsorption of water. TPD studies showed that water can adsorb competitively with both ammonia and nitric oxide. Additional kinetic experiments revealed that adsorbed ammonia is present in excess on the catalyst surface, even in the presence of water. Reduced nitric oxide adsorption is responsible for the observed reversible decrease in the reaction rate; the fractional reaction order changes from 0.79 in the absence of water to 1.07 in its presence. Deactivation is probably due to the dissociative adsorption of water, resulting in the formation of additional surface hydroxyls. As the amount of surface hydroxyls formed is limited to a saturation level, the deactivating effect on the catalyst is limited too. The additional hydroxyls condense and desorb in the temperature range 525–775 K, resulting in a lower degree of deactivation at higher temperature. A high temperature treatment at 775 K results in a complete regeneration. The amount of surface hydroxyls formed per unit surface area decreases at increasing MnOx-loading. The selectivity to the production of nitrogen is enhanced significantly by the presence of gas phase water. 相似文献
The philosophy behind quality, environmental, and safety (QES) management systems is a concept that has been accepted by various contractors. Furthermore, a process has been developed insuring that the output produced conforms to customer satisfaction without violating any environmental, health, and safety rules and regulations. An effective QES program not only assures a quality product but also reduces costs, and enhances productivity. It is a top down process, i.e., top management together with line management and other employees develop the program and motivate all personnel to accept the process. Important functions to take under consideration are (1) explain and clarify the quality, environmental, and safety performance expected; (2) involve employees in decision-making and problem solving; (3) describe the consequences of poor quality and unsafe/unhealthy work conditions; (4) establish QES goals and provide feedback on performance; (5) provide a self-monitoring system; and (6) recognize and reinforce good performance and develop a reward system. This paper presents a discussion of the development of a portion of a QES management system which has been employed by a medium to large size construction company. In particular, Items 1–4, listed above, are described in detail. 相似文献
In humans, low-grade B-cell mucosa-associated lymphoid tissue (MALT) lymphomas of the stomach regress when Helicobacter pylori infection is cured by antimicrobial therapy. Using an animal model of human gastric MALT lymphoma, we observed the effects of Helicobacter felis eradication and the relationship between infection and disease progression. Antimicrobial therapy was given to one-half of the BALB/c mice infected with H. felis for 20 months. Groups of antibiotic-treated and untreated mice were killed 2, 3, and 4 months after antimicrobial therapy (ie, 22, 23, and 24 months after infection). The numbers of mice with MALT decreased after H. felis eradication with no lymphoid follicles seen 4 months after treatment. MALT lymphoma was present in a total of 23% (11/48) of antibiotic-treated infected mice compared with 75% (27/36) in untreated infected mice. These lymphomas were further graded into low-, intermediate-, and high-grade lymphoma. In the untreated mice, lymphoma development was more advanced with 36% low-grade (13/36), 39% intermediate-grade (14/36), and 6% high-grade (large B-cell) lymphoma (2/36) whereas in the treated mice the incidence was 21% (10/48), 6% (3/48), and 0% (0/48), respectively. These observations suggest that antigenic stimulation by H. felis sustained growth and progression of low-grade MALT lymphoma and that primary high-grade gastric lymphomas can evolve from the transformation of these tumors. Eradication of the organism caused low-grade tumors to regress, with inhibition or slowing down of lymphoma development toward high-grade lymphoma. The H. felis mouse model of gastric MALT lymphoma presents an opportunity to address the issues arising from antimicrobial treatment of these tumors in humans. 相似文献
Summary The purpose of this study was to find experimental conditions for the complete solubility of collagen-free muscle proteins (CFMP) using acetone powder of Guelders ring sausage. Preliminary experiments were carried out to choose the best procedure for preparing the acetone dry powder. Two different methods of acetone extraction of minced sausage were compared. The acetone dry mass (ADM) method using continuous extraction in a Soxhlet [2] apparatus gave better results than the acetone powder (ACP) method, which used a blender [1]. The ADM method was used for further investigations. ADM was extracted with two types of sodium dodecyl sulphate (SDS), containing solvents A and B. Solvent A contains a Tris-boric acid buffer (pH 8.2) with 1.5% (m/v) SDS and 0.05% (m/v) dithioerythreitol [3]. Solvent B is a borate-chloric acid buffer (pH 9.0) with 2.0% (m/v) SDS and 1.0% (m/v) mercapto-ethanol [2]. Both solvents showed a linear relationship between the quantities of CFMP in ADM and the dissolved CFMP. The linear relationships were found between quantities of 10.0 and 30.0 mg (solution A) and of 5.0 and 30.0 mg ADM (solution B) per ml solvent. The solubility of CFMP was better in solvent B than in solution A. Completely dissolved CFMP from ADM was only obtained in the case of 5.0 mg ADM in 1.0 ml solution B. These conditions will be used in liquid chromatography experiments, the results of which will be reported later.
Quantitative Aspekte zweier Verfahren für das Auflösen kollagenfreier Muskelproteine aus acetontrockenen Pulvern der Gelderschen Rauchwurst
Zusammenfassung Der Zweck dieser Untersuchungen ist, die experimentellen Bedingungen für die vollstän-dige Löslichkeit des kollagenfreien Muskelproteins (CFMP) aus dem Acetonpulver der Gelderschen Rauchwurst zu finden. Durch Vorversuche wurde die beste Arbeitsweise für das Zubereiten des Acetonpulvers gewählt. Zwei verschiedene Extraktionsverfahren mit zerkleinertem Wurstmaterial wurden miteinander verglichen. Die Methode mit der Acetontrockenmasse (ADM) mittels kontinuierlicher Extraktion [2] führte zu besseren Ergebnissen als die Methode mit Acetonpulver (ACP), wozu ein Mischgerät [1] verwendet wurde. Die ADM-Methode wurde für weitere Untersuchungen angewendet. ADM wurde mit zwei verschiedenen Extraktionslösungen von Natrium-Dodecylsulfat (SDS) (A und B) extrahiert. Lösung A enthalt einen Tris-Borsäure Puffer (pH 8,2) mit SDS (1,5%) und Dithioerithritol (0,05%) [3]. Die Lösung B enthält einen Borat-Salzsäure Puffer (pH 9,0) mit SDS (2,0%) und Mercapto-Ethanol (1,0%) [2]. Beide Extraktionslösungen zeigen ein lineares Verhalten zwischen den Mengen vom CFMP in ADM und in aufgelöstem CFMP. Diese Linearität wurde von 10,030,0 mg ADM (Lösungsmittel A) und von 5,030,0 mg ADM (Lösungsmittel B) gefunden. Die Lös-lichkeit in Lösung B ist gegeniiber Lösung A besser. Ein vollständig gelöstes CFMP aus ADM wurde nur bei der Extraktion von 5,0 mg ADM in 1,0 ml der Losung B erhalten. Diese Bedingung soll in unseren künftigen flüssigchromatographischen Experimenten verwendet werden.
Supported by a grant from the Hoofdinspectie Levensmiddelen of the Ministry of Welzijn, Volksgezondheid en Cultuur 相似文献
The relative reactivities of the lower alkanes in hydrogenolysis on a Pt/Al2O3 catalyst depend on the H2 pressure used, as do those of a Ru/Al2O3 catalyst, pretreated in various ways, for propane hydrogenolysis. Apparent activation energies also vary with H2 pressure. No single rate measurement adequately represents catalytic activity, which is properly defined as the rateconstant for the slow step. 相似文献
This work addresses the reduction of NOx by H2 under O2-rich conditions using Al2O3/SiO2-supported Pt catalysts with different loads of WOx promotor. The samples were thoroughly characterised by N2 physisorption, temperature-programmed desorption of CO, scanning electron microscopy, X-ray diffraction, laser raman spectroscopy, X-ray photoelectron spectroscopy and diffuse reflectance infrared fourier transform spectroscopy with probe molecule CO. The catalytic studies of the samples without WOx showed pronounced NOx conversion below 200 °C, whereas highest efficiency was related to small Pt particles. The introduction of WOx provided increasing deNOx activity as well as N2 selectivity. This promoting effect was referred to an additional reaction path at the Pt-WOx/Al2O3/SiO2 interface, whereas an electronic activation of Pt by strong metal support interaction was excluded.
The Accreditation Board for Engineering and Technology (ABET) has adopted a revised set of criteria for accrediting engineering programs. Nevertheless, as in the past, civil engineering departments will be required to demonstrate proficiency in specific subject areas which are included in the ABET program criteria. This paper investigates how civil engineering students at Lamar University improved their understanding of various subject areas required by ABET and listed in the Program Criteria for Civil and Similarly Named Engineering Programs and the General Criteria (professional component) by being involved with cooperative, part-time, and summer work experiences. In particular, the findings suggest that both undergraduate and graduate students believe that three areas have been greatly enhanced with engineering work. They include structural engineering, project management/scheduling and estimating, and teamwork. In addition, undergraduates perceive that their understanding of health and safety issues and ethical considerations has also increased. In contrast, graduate students believe that their knowledge of hydraulics, hydrology, and water resources, constructability, and economic factors has been enhanced by civil engineering work experiences. 相似文献
We propose a novel process for the production of a DAG‐rich acylglycerol mixture derived from milk fat. This product has potentially interesting nutritional properties, derived from both its high content of DAG and of short‐chain fatty acids (FAs). The proposed process consists of three steps: lipase‐catalysed partial ethanolysis of milk fat, extraction of the by‐product fatty acid ethyl esters (FAEEs) using supercritical carbon dioxide (SC‐CO2) and isomerization of DAG to increase the proportion of 1,3‐DAG. The experimental investigation of the process steps was done using milk fat and trilaurin. Several lipases were tested for maximizing the percentage of DAG in the acylglycerol mixture produced by ethanolysis. The selectivity of the chosen lipase was such that the produced AG mixture was enriched in short‐chain FAs in relation to the original milk fat. FAEEs were completely extracted from the ethanolysis mixture by SC‐CO2. In the final process step, we explored the reaction conditions for facilitating acyl migration in the DAG mixture, so that the equilibrium proportion of 1,3‐DAG (~64%) was attained. Our results set the basis for the development of a simple process for the production of a DAG‐rich milk fat analogue. 相似文献