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

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

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

Conductance spectra of (Nb, Pb, In)/NbP -- superconductor/Weyl semimetal junctions

The possibility of inducing superconductivity in type-I Weyl semimetal through coupling its surface to a superconductor was investigated. A single crystal of NbP, grown by chemical vapor transport method, was carefully characterized by XRD, EDX, SEM, ARPES techniques and by electron transport measurements. The mobility spectrum of the carriers was determined. For the studies of interface transmission, the (001) surface of the crystal was covered by several hundred nm thick metallic layers of either Pb, or Nb, or In. DC current-voltage characteristics and AC differential conductance through the interfaces as a function of the DC bias were investigated. When the metals become superconducting, all three types of junctions show conductance increase, pointing out the Andreev reflection as a prevalent contribution to the subgap conductance. In the case of Pb-NbP and Nb-NbP junctions, the effect is satisfactorily described by modified Blonder-Tinkham-Klapwijk model. The absolute value of the conductance is much smaller than that for the bulk crystal, indicating that the transmission occurs through only a small part of the contact area. An opposite situation occurs in In-NbP junction, where the conductance at the peak reaches the bulk value indicating that almost whole contact area is transmitting and, additionally, a superconducting proximity phase is formed in the material. We interpret this as a result of indium diffusion into NbP, where the metal atoms penetrate the surface barrier and form very transparent superconductor-Weyl semimetal contact inside. However, further diffusion occurring already at room temperature leads to degradation of the effect, so it is observed only in the pristine structures. Despite of this, our observation directly demonstrates possibility of inducing superconductivity in a type-I Weyl semimetal.Comment: Accepted for Phys. Rev. B. 13 pages, 12 figures. Second version with major revisions. The title was changed. One author R. Jakiela added. New inset to Fig. 8(A). New fits in Fig. 8 (B) and Fig. 10 (B). Added figures 12 (C)-(E). Added Fig. 12 (F) with SIMS data. Rewritten chapters III-C-2 and III-C-3. Reference no. 38 removed, 11 new references: 9, 21, 22, 40-44, 46-49 were adde

A comparison between monolithic and wire gauze structured catalytic reactors for CH₄ and CO removal from biogas-fuelled engine exhaust

The application of the wire gauzes as the catalytic supports can provide a number of advantages in biogas exhaust abatement. In this paper, a model of wire gauze structured reactor for biogas exhaust removal is proposed and model based calculations are performed to compare the wire gauze catalytic reactor with the classic monolith. The modelling bases on kinetic data experimentally obtained in a small-scale tubular reactor for cobalt and palladium (as reference) oxide catalysts doped with promoters (Ce, Pd). The heat and mass transfer characteristics of the wire gauze reactor are taken from the former studies by the authors. The simulations show that for assumed reactor parameters, a combination of the promoted cobalt oxide catalyst and the wire gauze support can give high conversion of methane and carbon monoxide

Precision Predictions for (Un)Stable W+W- Pair Production At and Beyond LEP2 Energies Beyond LEP2 Energies

We present precision calculations of the processes e+e- -> 4-fermions in which the double resonant W+W- intermediate state occurs. Referring to this latter intermediate state as the 'signal process', we show that, by using the YFS Monte Carlo event generators YFSWW3-1.14 and KORALW1.42 in an appropriate combination, we achieve a physical precision on the signal process, as isolated with LEP2 MC Workshop cuts, below 0.5 per cent. We stress the full gauge invariance of our calculations and we compare our results with those of other authors where appropriate. In particular, sample Monte Carlo data are explicitly illustrated and compared with the results of the program RacoonWW of Dittmaier {\it et al.}. In this way, we show that the total (physical plus technical) precision tag for the WW signal process cross section is 0.4 per cent for 200 GeV, for example. Results are also given for 500 GeV with an eye toward the LC.Comment: 19 pages, 2 figs;corrected Tab. 3;improved refs.,figs.,text;improved refs.,text;improved tex