Reduced sintering of mass-selected Au clusters on SiO2 by alloying with Ti: an aberration-corrected STEM and computational study.

Au nanoparticles represent the most remarkable example of a size effect in heterogeneous catalysis. However, a major issue hindering the use of Au nanoparticles in technological applications is their rapid sintering. We explore the potential of stabilizing Au nanoclusters on SiO2 by alloying them with a reactive metal, Ti. Mass-selected Au/Ti clusters (400 000 amu) and Au2057 clusters (405 229 amu) were produced with a magnetron sputtering, gas condensation cluster beam source in conjunction with a lateral time-of-flight mass filter, deposited onto a silica support and characterised by XPS and LEIS. The sintering dynamics of mass-selected Au and Au/Ti alloy nanoclusters were investigated in real space and real time with atomic resolution aberration-corrected HAADF-STEM imaging, supported by model DFT calculations. A strong anchoring effect was revealed in the case of the Au/Ti clusters, because of a much increased local interaction with the support (by a factor 5 in the simulations), which strongly inhibits sintering, especially when the clusters are more than ∼0.60 nm apart. Heating the clusters at 100 °C for 1 h in a mixture of O2 and CO, to simulate CO oxidation conditions, led to some segregation in the Au/Ti clusters, but in line with the model computational investigation, Au atoms were still present on the surface. Thus size-selected, deposited nanoalloy Au/Ti clusters appear to be promising candidates for sustainable gold-based nanocatalysis.

Operando XAS Study of the Surface Oxidation State on a Monolayer IrOx on RuOx and Ru Oxide Based Nanoparticles for Oxygen Evolution in Acidic Media.

Herein we present surface sensitive operando XAS L-edge measurements on IrOx/RuO2 thin films as well as mass-selected RuOx and Ru nanoparticles. We observed shifts of the white line XAS peak toward higher energies with applied electrochemical potential. Apart from the case of the metallic Ru nanoparticles, the observed potential dependencies were purely core-level shifts caused by a change in oxidation state, which indicates no structural changes. These findings can be explained by different binding energies of oxygenated species on the surface of IrOx and RuOx. Simulated XAS spectra show that the average Ir oxidation state change is strongly affected by the coverage of atomic O. The observed shifts in oxidation state suggest that the surface has a high coverage of O at potentials just below the potential where oxygen evolution is exergonic in free energy. This observation is consistent with the notion that the metal-oxygen bond is stronger than ideal.

Long-term clinical and experimental/surface analytical studies of carbon/carbon maxillofacial implants.

BACKGROUND: Over the past 30-40 years, various carbon implant materials have become more interesting, because they are well accepted by the biological environment. The traditional carbon-based polymers give rise to many complications. The polymer complication may be eliminated through carbon fibres bound by pyrocarbon (carbon/carbon). The aim of this study is to present the long-term clinical results of carbon/carbon implants, and the results of the scanning electron microscope and energy dispersive spectrometer investigation of an implant retrieved from the human body after 8 years. METHODS: Mandibular reconstruction (8-10 years ago) was performed with pure (99.99 %) carbon implants in 16 patients (10 malignant tumours, 4 large cystic lesions and 2 augmentative processes). The long-term effect of the human body on the carbon/carbon implant was investigated by comparing the structure, the surface morphology and the composition of an implant retrieved after 8 years to a sterilized, but not implanted one. RESULTS: Of the 16 patients, the implants had to be removed earlier in 5 patients because of the defect that arose on the oral mucosa above the carbon plates. During the long-term follow-up, plate fracture, loosening of the screws, infection or inflammations around the carbon/carbon implants were not observed. The thickness of the carbon fibres constituting the implants did not change during the 8-year period, the surface of the implant retrieved was covered with a thin surface layer not present on the unimplanted implant. The composition of this layer is identical to the composition of the underlying carbon fibres. Residual soft tissue penetrating the bulk material between the carbon fibre bunches was found on the retrieved implant indicating the importance of the surface morphology in tissue growth and adhering implants. CONCLUSIONS: The surface morphology and the structure were not changed after 8 years. The two main components of the implant retrieved from the human body are still carbon and oxygen, but the amount of oxygen is 3-4 times higher than on the surface of the reference implant, which can be attributed to the oxidative effect of the human body, consequently in the integration and biocompatibility of the implant. The clinical conclusion is that if the soft part cover is appropriate, the carbon implants are cosmetically and functionally more suitable than titanium plates.

Surface analytical studies of maxillofacial implants: influence of the preoperational treatment and the human body on the surface properties of retrieved implants.

In the present work, surface analytical investigation of unimplanted as well as retrieved pyrolytic carbon-covered carbon/carbon composite implants and Ti osteosynthesis plates is reported. The Ti plates were covered by a 200-nm-thick, anodically and thermally formed TiO2 layer. Our results suggest that although the oxide layer on the Ti miniplates remained stable during the time spent in the human body, there is still material transport between the implant and the human body. In case of the carbon/carbon composite implants, damage of the carbon fibers constituting the material was found on one side of the sterile implant and attributed to the manufacturing process. The NaCl crystals originally present on the surface of the sterile material disappeared during the time spent in the human body. As a result of the interaction with the human body, a new surface layer (mainly constituted of carbon) appeared on the implant. The results indicate that both the time spent in the human organism and the preparation of the implants before operation can have detectable effects on the investigated surface properties. Surface analytical investigations could therefore provide information not only about the biocompatibility of these materials but also about the effect of their treatment before operation.

SEM and EDS investigation of a pyrolytic carbon covered C/C composite maxillofacial implant retrieved from the human body after 8 years.

The long term effect of the human body on a pyrolytic carbon covered C/C composite maxillofacial implant (CarBulat(Tm)) was investigated by comparing the structure, the surface morphology and composition of an implant retrieved after 8 years to a sterilized, but not implanted one. Although the thickness of the carbon fibres constituting the implants did not change during the 8 year period, the surface of the implant retrieved was covered with a thin surface layer not present on the unimplanted implant. The composition of this layer is identical to the composition of the underlying carbon fibres. Calcium can only be detected on the surface as a trace element implying that the new layer is not formed by bone tissue. Residual soft tissue penetrating the bulk material between the carbon fibre bunches was found on the retrieved implant indicating the importance of the surface morphology in tissue growth and adhering to implants.

[Carbon/carbon implants in oral and maxillofacial surgery--Part 2]. / Karbon/karbon implantátumok az arc- és állcsontsebészetben--2. rész.

In their previous report, the authors presented observations regarding the long-term application of carbon/carbon implants. After evaluating the good functional and aesthetic results, the effect of the human body on the structure and morphology of the implants was investigated with state of the art methods. An implant retrieved from the body after eight years was compared to implants which were sterilized but not implanted (reference). Carbon and oxygen were the main components of both implants, however, as a result of the interaction with the human body the amount of oxygen increased 3-4 times and phosphorus, sulphur, calcium and iron were detectable as trace elements on the surface. The width of the carbon fibres (5-7 µm) building up the implants was not changed during the interaction with the human body. The surface of the implant retrieved from the human body was covered with a 15-17 µm thick layer, not present on the reference implant, having a similar composition to that of the carbon fibres (high amount of calcium that is typical to bone tissue was not detected). According to these results, the structure and the morphology of the implants were not altered notably by the human body.

[Prevalence of childhood asthma in Baranya County, Hungary, between 2003 and 2006]. / A gyermekkori asztma prevalenciájának alakulása Baranya megyében 2003 és 2006 között.

INTRODUCTION: The prevalence of bronchial asthma, allergic rhinitis and atopic dermatitis (AD) in children has constantly and significantly increased worldwide in the past decades. Recent publications, however, reported a moderate decrease or levelling off in this parameter. The authors estimated the prevalence of bronchial asthma and asthmatic complaints among schoolchildren in Baranya county in the years 2003 and 2006 in order to register the possible changes. MATERIALS AND METHODS: Both surveys were carried out by means of identical questionnaires which were consistent with the ISAAC Phase III. protocol. The data were collected in 16 primary schools (6 in a city, 10 in small settlements and villages) in February 2006. Finally 2404 questionnaires (1124 boys, 1280 girls) in two age groups, among 6-7 and 13-14-year-old children were processed and compared to the data derived from the survey done in 2003. RESULTS: The prevalence of the "wheezing-ever" and "physician diagnosed asthma" did not change during the observation period (2006: 20.2% and 6.7%; 2003: 19.8% and 8.2%) but there was a significant increase in the frequency of "wheezing in the last 12 months" (2006: 9.6%; 2003: 6.8%). As expected, significantly higher prevalence rates were detected among boys and in the 6-7-year-old age group than among girls and in the 13-14-year-old age group in both surveys. There was no significant difference in the two surveys in the prevalence of bronchial asthma and asthmatic signs between children from a city and from small settlements. CONCLUSION: During the observation period of three years there was a significant increase "wheezing in the last 12 months", but the prevalence of "wheezing-ever" as well as the "physician-diagnosed asthma" remained unchanged.

Novel keratin 14 gene mutations in patients from Hungary with epidermolysis bullosa simplex.

Mutations in genes keratin 5 (KRT5) and 14 (KRT14) encoding the basal type keratin intermediate filaments have been identified in epidermolysis bullosa simplex (EBS) families and are likely to cause skin fragility. Three novel keratin 14 mutations in cases from the Hungarian Epidermolysis Bullosa Centre are reported. In a 7-year-old boy with Dowling-Meara type EBS (DM-EBS), who had severe skin symptoms with extended herpetiform blisters, a novel amino acid substitution N123K in keratin 14 had been detected. A 26-year-old woman with mild DM-EBS with prominent palmoplantar hyperkeratosis and without active blister formation had a novel R125G mutation in keratin 14. In a 6-year-old girl, with Weber-Cockayne type EBS (WC-EBS) with palmoplantar blisters and moderate mental retardation, a novel V133L substitution was detected. Her pedigree showed autosomal dominant mode of inheritance; in the two other families, only the index patients were affected. The N123K and R125G mutations causing DM-EBS phenotypes are located within the helix initiation motif of the rod domain, whereas the very close V133L mutation underlying the WC-EBS phenotype is outside of this region. These novel amino acid substitutions provide further information for genotype-phenotype correlation in KRT14 mutations, and demonstrate the first molecular genetic data in EBS patients from Hungary.

[Prevalence of atopic dermatitis in school children of Baranya county]. / Atópiás dermatitis elófordulási gyakorisága Baranya megyei iskolás gyermekek körében.

INTRODUCTION: The prevalence of atopic dermatitis (AD) in children has significantly increased worldwide in the past decades. Although it is well known that the number of AD patients has also been growing in Hungary no prevalence studies on a given population have been performed so far. METHODS: The present research investigated the prevalence of AD in school children by means of questionnaires. The data of 1454 (771 girls, 683 boys) children aged 6-14 years in a big city (Pécs, Hungary) and three small settlements (Bóly, Magyarbóly, Villány; Hungary) were analyzed. RESULTS: Applying the standard point values of the Schultz-Larsen questionnaire the prevalence of AD accounted for 15.1%; it was higher in the big city (16.5%) and lower in the small settlements (13.7%). In girls the prevalence of AD (15.9%) was greater than in boys (14%); this difference was more remarkable in the big city (18.2% vs. 14.8%). The first symptoms of AD appeared before the age of two in 58.8% and it was significantly higher in the big city (63.5%) as in the small settlements (52.6%). Among the 221 AD patients there were 38 patients (17.1%) with asthma and 93 (42.1%) with allergic rhinitis. The AD family (parents, brothers and sisters, great parents) proved to be positive in 72.8%. CONCLUSIONS: The results indicate the high prevalence rate of AD in school children in Baranya County, Hungary reaching or nearly approaching the significantly high values registered in the welfare countries.