War in Ukraine and dialysis treatment: human suffering and organizational challenges

In January 2021, there were 9,648 patients in Ukraine on kidney replacement therapy, including 8,717 on extracorporeal therapies and 931 on peritoneal dialysis. On 24 February 2022, foreign troops entered the territory of Ukraine. Before the war, the Fresenius Medical Care dialysis network in Ukraine operated three medical centres. These medical centres provided haemodialysis therapy to 349 end stage kidney disease patients. In addition, Fresenius Medical Care Ukraine delivered medical supplies to almost all regions of Ukraine. Even though Fresenius Medical Care's share of end stage kidney disease patients on dialysis is small, a brief narrative account of the managerial challenges that Fresenius Medical Care Ukraine and the clinical directors of the Fresenius Medical Care centres had to face, as well as the suffering of the dialysis population, is a useful testimony of the burden imposed by war on these frail, high-risk patients dependent on a complex technology such as dialysis. The war in Ukraine is causing immense suffering for the dialysis population of this country and has called for heroic efforts from the dialysis personnel. The experience of a small dialysis network treating a minority of dialysis patients in Ukraine is described. Guaranteeing dialysis treatment has been and remains an enormous challenge in Ukraine and we are confident that the generosity and the courage of Ukrainian dialysis staff and international aid will help to mitigate this tragic suffering.

Direct k-space mapping of the electronic structure in an oxide-oxide interface

The interface between LaAlO(3) and SrTiO(3) hosts a two-dimensional electron system of itinerant carriers, although both oxides are band insulators. Interface ferromagnetism coexisting with superconductivity has been found and attributed to local moments. Experimentally, it has been established that Ti 3d electrons are confined to the interface. Using soft x-ray angle-resolved resonant photoelectron spectroscopy we have directly mapped the interface states in k space. Our data demonstrate a charge dichotomy. A mobile fraction contributes to Fermi surface sheets, whereas a localized portion at higher binding energies is tentatively attributed to electrons trapped by O vacancies in the SrTiO(3). While photovoltage effects in the polar LaAlO(3) layers cannot be excluded, the apparent absence of surface-related Fermi surface sheets could also be fully reconciled in a recently proposed electronic reconstruction picture where the built-in potential in the LaAlO(3) is compensated by surface O vacancies serving also as a charge reservoir.

[Species-specific detection of Proteus vulgaris and Proteus mirabilis by the polymerase chain reaction]

Sets of primers for the species-specific detection of P. mirabilis and P. vulgaris by the polymerase chain reaction (PCR) were developed. As targets for these primers beta-lactamase and 16S rRNA gene fragments were chosen on the basis of the multiple leveling of the sequences of the DNA of all known P. mirabilis and P. vulgaris isolates. For differential detection oligonucleotides were selected in such a way that primers, specific for P. vulgaris, contained the non-paired nucleotide for P. mirabilis isolate at the 3'-end, and all other nucleotides were complementary to the beta-lactamase gene fragment. Primers, specific for gene 16S rRNA of P. mirabilis, contained the non-paired nucleotide for P. vulgaris isolates at the 3'-end. Standard PCR was carried out for 6 P. mirabilis and P. vulgaris strains. The use of PCR species-specific primers to P. vulgaris DNA made it possible to amplify the DNA fragment of the expected length only for P. vulgaris isolates, while the result of PCR for P. mirabilis was negative. PCR with primers specific to P. mirabilis permitted the detection of amplicon sized 101 nucleotides pairs only for P. mirabilis strains. These primers were optimized so as to use them in the specific differentiation of closely related P. mirabilis and P. vulgaris species by multiplex PCR. Genus-specific primers permitted the detection of bacterial gyrB gene of the genus Proteus were developed also.

Critical behavior in an atomistic model for a bistable surface reaction: CO oxidation with rapid CO diffusion

We analyze critical behavior associated with the loss of bistability for an atomistic model for CO oxidation on surfaces in the limit of infinite diffusion of CO. The model includes infinite nearest-neighbor repulsions between adsorbed immobile O. We use a "hybrid" treatment incorporating a lattice-gas description of the O adlayer, but tracking just the number of adsorbed CO (which are randomly distributed on non-O sites). The critical exponents obtained from a finite-size-scaling analysis on LxL site surfaces with periodic boundary conditions show that the "hybrid" reaction model belongs to the mean-field universality class, despite strong spatial correlations in the O adlayer. We also quantify finite-size effects in the global bifurcation diagram, revealing a significant shift of the bistable region with decreasing system size. Our study elucidates fluctuation effects observed in experiments of CO oxidation on the nanoscale facets of metal-field emitter tips.

Catalytic CO oxidation on nanoscale Pt facets: effect of interfacet CO diffusion on bifurcation and fluctuation behavior

We present lattice-gas modeling of the steady-state behavior in CO oxidation on the facets of nanoscale metal clusters, with coupling via interfacet CO diffusion. The model incorporates the key aspects of the reaction process, such as rapid CO mobility within each facet and strong nearest-neighbor repulsion between adsorbed O. The former justifies our use of a "hybrid" simulation approach treating the CO coverage as a mean-field parameter. For an isolated facet, there is one bistable region where the system can exist in either a reactive state (with high oxygen coverage) or a (nearly CO-poisoned) inactive state. Diffusion between two facets is shown to induce complex multistability in the steady states of the system. The bifurcation diagram exhibits two regions with bistabilities due to the difference between adsorption properties of the facets. We explore the role of enhanced fluctuations in the proximity of a cusp bifurcation point associated with one facet in producing transitions between stable states on that facet, as well as their influence on fluctuations on the other facet. The results are expected to shed more light on the reaction kinetics for supported catalysts.