Microstructured reactor as a pre-turbo catalytic converter

The idea of a structured catalytic converter placed immediately after engine exhaust valves, thus operating on high gas temperature and velocity, is explored. The assumption is that major part of the reactor operates in the entry region where Nusselt and Sherwood numbers are highly enhanced. In this work, flow resistances as well as heat and mass transfer coefficients were studied for gas velocities exceeding 50 m/s. Consequently, the transition range (between laminar and turbulent flows) was reached. The comparison with classic monolith has shown significant improvement in heat or mass transfer paid by slight increase in flow resistance

Funkcja endoprotezy onkologicznej w nawrotowym mięsaku kostno pochodnym dalszego końca kości udowej .

Endoprothesis is the commonly used method of segmental reconstruction after bone tumor resection around knee. To achieve stability after extensive removal of knee structures, hinged endoprostheses are usually being preferred as a limb salvage procedure. Despite advances in diagnostics and preoperative tumor chemotherapy and radiotherapy, as well as meticulous intraoperative preparation, local tumor recurrence is still possible. We analyzed 22 patients with osteosarcoma in distal femur who underwent the knee arthroplasty with modular replacement system between 2002 and 2007. Three of them (two females aged 33 and 44 and one male aged 29) developed local recurrence 7, 9 and 12 months after operation. All of them were offered the amputation or metastatectomy, as well as further chemotherapy, and all refused. Reasons for refusal included disseminated disease, uncertain prognosis of amputation treatment and still good functional outcome despite existing tumor around the prosthesis. Two of the above mentioned patients deceased from disseminated disease 7 and 11 months later, one patient is still being followed 10 months long. Clinical examinations have shown the effective and satisfactory prosthesis functions in reported patients during the whole observation period. We have concluded that limb salvage surgery with implantation of hinged knee endoprosthesis in tumors in distal femur provide satisfactory functional outcome even when local tumor recurrence is found.Endoproteza jest powszechnie używaną metodą segmentalnej rekonstrukcji po resekcji guzów kości w okolicy stawu kolanowego. Dla uzyskania stabilności po rozległym usunięciu struktur stawu kolanowego, protezy zawiasowe są zazwyczaj preferowane jako procedury oszczędzające kończynę. Pomimo zaawansowanej diagnostyki i przedoperacyjnej chemioterapii i radioterapii guza, jak również drobiazgowego śródoperacyjnego preparowania, miejscowa wznowa guza nadal jest możliwa. Przeanalizowaliśmy 22 pacjentów z mięsakiem kostnopochodnym dalszego końca kości udowej, którzy zostali poddani endoprotezoplastyce poresekcyjnej stawu kolanowego z użyciem modularnego systemu pomiędzy 2002r. a 2007r. U trzech z nich (dwie kobiety w wieku 33 i 44 lata i jeden mężczyzna w wieku 29 lat) rozwinęła się miejscowa wznowa 7, 9 i 12 miesięcy po operacji. Zaproponowano im amputację lub resekcję wznowy, jak również dalszą chemioterapię. Wszyscy odmówili. Przyczynami odmowy były: rozsiana choroba nowotworowa, niepewne rokowanie po amputacji i wciąż dobry czynnościowy wynik pomimo istniejącego guza wokół endoprotezy. Dwóch z tych pacjentów zmarło z powodu rozsianego procesu nowotworowego 7 i 11 miesięcy później, a trzeci chory był jeszcze obserwowany przez kolejnych 10 miesięcy. Kliniczna ocena pokazała wydolną i zadawalającą funkcję endoprotezy u opisywanych chorych podczas całego okresu obserwacji. Stwierdziliśmy, że operacje oszczędzające kończynę z wszczepieniem endoprotezy poresekcyjnej, zawiasowej stawu kolanowego w guzach dalszego końca kości udowej przynosi zadawalający wynik czynnościowy nawet kiedy występuje miejscowa wznowa guza

Fibre-optic delivery of time and frequency to VLBI station

The quality of Very Long Baseline Interferometry (VLBI) radio observations predominantly relies on precise and ultra-stable time and frequency (T&F) standards, usually hydrogen masers (HM), maintained locally at each VLBI station. Here, we present an operational solution in which the VLBI observations are routinely carried out without use of a local HM, but using remote synchronization via a stabilized, long-distance fibre-optic link. The T&F reference signals, traceable to international atomic timescale (TAI), are delivered to the VLBI station from a dedicated timekeeping laboratory. Moreover, we describe a proof-of-concept experiment where the VLBI station is synchronized to a remote strontium optical lattice clock during the observation.Comment: 8 pages, 8 figures, matches the version published in A&A, section Astronomical instrumentatio

Characterization of fluid flow and heat transfer of expanded metal meshes for catalytic processes

In this work, three raised expanded metal meshes (EMMs) differing in mesh size were tested experimentally with regard to their flow and transport properties. Empirical equations for the Nusselt number and Fanning friction factor were developed. Alongside the experiments, simple computational fluid dynamics (CFD) models were used to simulate the pressure drop and heat transfer coefficients within EMMs. Finally, the Performance Efficiency Criterion (PEC) was applied to compare EMMs with other reactor packings

Metal foams as novel catalyst support in environmental processes

Metal foams are considered as promising catalyst carriers due to their high porosity, large specific surface area, and satisfactory thermal and mechanical stability. The study presents heat transfer and pressure drop experiments performed for seven foams of different pore densities made from diverse metals. Mass transfer characteristics are derived using the Chilton–Colburn analogy. It was found that the foams display much more intense heat/mass transfer than a monolith, comparable to packed bed. Next, the foams’ efficiencies have been compared, using 1D reactor modeling, in catalytic reactions displaying either slower (selective catalytic reduction of NOx) or faster kinetics (catalytic methane combustion). For the slow kinetics, the influence of carrier specific surface area at which catalyst can be deposited (i.e., catalyst amount) was decisive to achieve high process conversion and short reactor. For this case, monolith appears as the best choice assuming it’s the lowest pressure drop. For the fast reaction, the mass transfer becomes the limiting parameter, thus solid foams are the best solution