Oxygen permeation of various archetypes of oxygen membranes based on BSCF

Ba_0.5Sr_0.5Co_0.8Fe_0.2O_3‐δ tubes, capillaries, capillary modules, and asymmetric membranes were prepared and tested for oxygen permeation in a dead‐end vacuum operation mode at temperatures up to 850^°C. The capillary module was built up by reactive air brazing using seven capillaries and a supply tube. Two machined discs were used as an end cap and as a connector plate. The oxygen permeation behaves according to Wagner at small driving forces, but significant negative deviations were observed for asymmetric membranes and single capillaries at higher ones. This is caused by pressure drops at the vacuum side for single capillaries. The highest oxygen flux was revealed for the capillary module with 175.5 mL(STP)/min at a low‐vacuum pressure of 0.042 bar at 850^°C, but the asymmetric membrane showing a little bit higher flux at moderate vacuum pressures above 0.07 bar. © 2012 American Institute of Chemical Engineers AIChE J, 58: 3195–3202, 2012     

Industrie 4.0

Industry 4.0 – Challenges for constructions of vacuum systems Vacuum systems are finding their way into branches and belonging modern process chains which were hardly in contact with UHV technology in the past. Besides an automatic operation and a flawless processing of parts, vacuum systems and their peripheral devices have to feature options for data output and analysis for subsequent processing in e.g. MES to come up with Industry 4.0 requirements. Subcomponents in vacuum technology partly comply with these requirements in a insufficient way because of their unchanged demands over the last decades. This makes integration into an automatic system more difficult. Despite of that, Industry 4.0 compliant vacuum systems are already producible when there's access to high-level experiences in vacuum and automation technology. This is shown by the examples of residual gas analysis and cleanliness measurement systems and the vacuum bake out oven. A cooperation of vacuum system manufacturers and manufacturers of components is necessary in the future to be able to produce automated vacuum systems in a more efficient way.     

Zuverlässige Prozesse durch Vakuumkomponenten mit definierten Ausgasraten

Reliable processes by use of vacuum components with specified outgassing rates Contamination of vacuum components cannot be avoided in the manufacturing process. In order to significantly reduce particulate and organic impurities, a multi-stage cleaning process and proof of cleanliness are essential. In order to guarantee a reproducible quality of the cleanliness of vacuum components, uniform standards for defined outgassing rates are necessary. The development of Vacom Purity Classes serves the generally accessible specification of components and characterises their vacuum and cleanroom suitability. Vacom Vacuum Classes guarantee the suitability of vacuum components for use in UHV/XHV. In this article, the importance of cleaning of vacuum chambers and components is examined as well as the need to establish a uniform method for the quantitative measurement of the outgassing rate is highlighted. The systematic division into Vacom Purity and Vacuum Classes provides the basis for a cross-industry standard for the defined quality of vacuum processes.     

Heat-integrated reactor concepts for catalytic reforming and automotive exhaust purification

Optimal solutions in environmental catalysis require a well-coordinated development of catalysts and of process design. This contribution is devoted to energy integrated design concepts for fuel reforming and for automotive exhaust purification. The examples presented demonstrate the importance of an innovative process design for optimal utilization of existing catalysts and show the potential of future developments.

New concepts for steam reforming through the efficient coupling of the endothermic reforming reaction with an exothermic combustion reaction are discussed in the first part. These concepts have been implemented for methanol steam reforming in a counter-current reactor with distributed side feed of burner gas and for methane steam reforming in a modular reactor with a co-current reaction section for the endothermic and the combustion reaction and attached counter-current heat exchangers. Both applications employ the so-called folded sheet reactor design, which ensures an excellent heat transfer between the reforming and combustion channels and efficient heat recovery.

A similar design solution is introduced for the apparently different case of automotive exhaust purification. The proposed concept aims at decoupling exhaust after-treatment from engine control. Its main component is a counter-current heat exchanger with integrated purification stages for HC-oxidation, NO_X storage and reduction and soot filtering. A small catalytic burner at the hot end of the heat exchanger provides both heat and oxidizing or reducing agents on demand. A new soot filter design allows for safe soot filter regeneration.     

Microcrack Formation During Gas Metal Arc Welding of High-Strength Fine-Grained Structural Steel

The recent development of high-performance-modified spray arc processes in gas metal arc welding due to modern digital control technology and inverter power sources enables a focused spray arc,which results in higher penetration depths and welding speed.However,microcracks occurred in the weld metal while approaching the process limits of the modified spray arc,represented by a 20-mm double layer DV-groove butt-weld.These cracks were detected in structural steel exhibiting a yield strength level of up to 960 MPa and are neither dependent on the used weld power source nor a consequence of the modified spray arc process itself.The metallographic and fractographic investigations of the rather exceptional fracture surface lead to the classification of the microcracks as hot cracks.The effects of certain welding parameters on the crack probability are clarified using a statistical design of experiment.However,these microcracks do not impact the design specification for toughness in the Charpy V-notch test(absorbed energy at —40 ℃ for the present material is 30 J).     

Lipoxygenase Products in the Urine Correlate with Renal Function and Body Temperature but not with Acute Transplant Rejection

Acute transplant rejection is the leading cause of graft loss in the first months after kidney transplantation. Lipoxygenase products mediate pro- and anti-inflammatory actions and thus we aimed to correlate the histological reports of renal transplant biopsies with urinary lipoxygenase products concentrations to evaluate their role as a diagnostic marker. This study included a total of 34 kidney transplant recipients: 17 with an acute transplant rejection and 17 controls. LTE4, LTB4, 12-HETE and 15-HETE concentrations were measured by enzyme immunoassay. Urinary lipoxygenase product concentrations were not significantly changed during an acute allograft rejection. Nevertheless, LTB4 concentrations correlated significantly with the body temperature (P ≤ 0.05) 3 months after transplantation, and 12- and 15-HETE concentrations correlated significantly with renal function (P ≤ 0.05) 2 weeks after transplantation. In conclusion, our data show a correlation for LTB4 with the body temperature 3 months after transplantation and urinary 12- and 15-HETE concentrations correlate positively with elevated serum creatinine concentrations but do not predict acute allograft rejection.     

Adaptability of competitive electricity reforms a modular analysis

Among the competitive electricity reforms that have been implemented in Europe and the US for the last 18 years, none has “survived” over several years without major changes. Their changing nature raises the question of their adaptability. Two characteristics of reforms play a key role on their adaptation properties. Firstly, they are “modular” objects in the sense of [Baldwin, C., 2008. Where do transactions come from? Modularity, transactions, and the boundaries of firms. Industrial and Corporate Change 17 (1), 155–195]. Secondly, they are produced in an institutional process which leads to “incomplete” rules and designs [Pistor, K., Xu, C., 2003. Incomplete law. International Law and Politics 35, 931–1013]. We propose a typology of adaptations based on the framework proposed by [Williamson, O.E., 1991. Comparative economic organization: the analysis of discrete structural alternatives. Administrative Science Quarterly 36 (2), 269–296] for contracts: (1) in case of small disturbances, adaptations are realized quasi-automatically, by autonomous decisions of the institutions governing the implementation of reforms; (2) in case of middle-range disturbances, adaption is made by Coasian bargaining; (3) finally, in case of strong disturbances, or when bargaining is not feasible, the adaptation of reforms is in the hands of legislative and executive institutions [North, D.C., 2005. Le processus du développement économique. Editions d’Organisation]. These institutions can reform the reforms [Joskow, P.L., 2006. Introduction to electricity sector liberalization: lessons learned from cross-country studies. In: Sioshansi, F.P. (Ed.), Electricity Market Reform: An International Perspective. Elsevier, Amsterdam, pp. 1–32; Hogan, W.W., 2002. Electricity market restructuring: reforms of reforms. Journal of Regulatory Economics 21, 103–132]. The role of these types of adaptations in each electricity reform is a consequence of the allocation of rights to the regulator, to stakeholders and to legislative and executive institutions.