Experimental and theoretical modeling of Fe , Co , Cu , Mn based electrocatalysts for oxygen reduction

Abstract Experience gained during efforts towards optimization of noble metal free electrocatalysts for oxygen reduction is simultaneously used to understand the chemical and morphological necessities for inducing efficient multielectron transfer catalysis. The analysis of many preparative experimental steps between the moderately performing metal porphyrines and the highly efficient transition metal and sulfur containing pyrolised catalyst material contributes to the following model of the catalyst 1. The metals function enclosed in nitrogen or graphitic environment where they are shielded against oxidation. 2. The metals can be exchanged but are not identical in their efficiency. 3. Higher efficiency is only achieved, when the function of a binary reaction center is warranted. 4. The carbonization of the environment is critical and provides intercalated metal centers and attached metal complexes in graphite environment for interaction with the nitrogen chelated partner center in the simultaneously obtained graphene layers. Experimental support for these models from EXAFS, RAMAN, Mössbauer and X ray spectroscopy is given and a parallel is drawn with the cytochrome oxidase oxygen reduction catalysis, which is proposed to proceed according to roughly the same mechanism. A special effort is made to discuss strategies for shielding and protecting catalytically active abundant transition metals against chemical reaction with oxygen or hydrogen peroxide

Correlation between mass and volume of collected blood with positivity of blood cultures

Background The collection of blood cultures is an extremely important method in the management of patients with suspected infection. Microbiology laboratories should monitor blood culture collection. Methods Over an 8-month period we developed a prospective, observational study in an adult Intensive Care Unit (ICU). We correlated the mass contained in the blood vials with blood culture positivity and we also verified the relationship between the mass of blood and blood volume collected for the diagnosis of bloodstream infection (BSI), as well as we explored factors predicting positive blood cultures. Results We evaluated 345 patients with sepsis, severe sepsis or septic shock for whom blood culture bottles were collected for the diagnosis of BSI. Of the 55 patients with BSI, 40.0 % had peripheral blood culture collection only. BSIs were classified as nosocomial in 34.5 %. In the multivariate model, the blood culture mass (in grams) remained a significant predictor of positivity, with an odds ratio 1.01 (i.e., for each additional 1 mL of blood collected there was a 1 % increase in positivity; 95 % CI 1.01–1.02, p = 0.001; Nagelkerke R Square [R2] = 0.192). For blood volume collected, the adjusted odds ratio was estimated at 1.02 (95 % CI: 1.01–1.03, p \u3c 0.001; R2 = 0.199). For each set of collected blood cultures beyond one set, the adjusted odds ratio was estimated to be 1.27 (95 % CI: 1.14–1.41, p \u3c 0.001; R2 = 0.221). Conclusions Our study was a quality improvement project that showed that microbiology laboratories can use the weight of blood culture bottles to determine if appropriate volume has been collected to improve the diagnosis of BSI

Comment on the article by the Schweizerisches Komitee für Stratigraphie (SJG, Vol 102/2) What is in a stratigraphical name?

The two newly defined lithostratigraphic units - the Rohrbachstein and Plaine-Morte Beds - within the recently reinstated Grünten Member (former "Upper Orbitolina Beds") embody characteristic lithostratigraphic units, which are well distinguishable in the field. They furthermore bear significant paleoceanographic information in that they document the final drowning episode of the Schrattenkalk carbonate platform (Rohrbachstein Bed) and overlap with oceanic anoxic event 1a ("Selli event": Plaine-Morte Bed). Their use is in line with a long-standing tradition to name individual phosphate- and glauconite-containing marker beds and is fully justified with respect to the Swiss guidelines of stratigraphical nomenclature (Remane et al. 2005

Ameloblastic fibroma: a rare case appearing as a mixed radiographic image

Ameloblastic fibroma (AF) is a benign tumor of mixed odontogenic origin, which affects predominantly young individuals. AF appearing as a mixed radiographic image is very rare. This report describes a case of AF in a 12- year-old male identified during a routine radiographic exam for orthodontic treatment planning. The panoramic radiography revealed a well-defined multilocular mixed image located in the mandible between the roots of the left mandibular second premolar and first molar. The lesion was excised under local anesthesia. Histopathological analysis revealed islands of epithelial cells and columnar peripheral cells showing a nucleus in inverted polarization, interspersed with spindle-shaped cells and abundant extracellular matrix deposition. No atypia was observed. The diagnosis of AF was established. No tumor recurred up to 30 months after treatment. Although rare, AF should be also considered in the differential diagnosis of mixed radiographic images of the jaws in young patients

Research of functional properties of nitride ion-plasma coatings

This paper considers the influence of ion-plasma coatings with the use of nitrogen (N), zirconium nitride (ZrN), titanium-aluminum nitride (Ti,Al)N and titanium nitride and zirconium nitride by-layer (TiN+ZrN - eight layers) on the properties of steel 65X13. The main functional properties of the coatings are determined: microhardness, nanohardness, Young's modulus and corrosion resistance. It is shown that all the types of coatings allow increasing the physical and mechanical characteristics of instrument steel 65X13. Hardness and wear-resistance, depending on the type of the deposited coating, increase from 1, 5 to 4 times, corrosion resistance increases by tens times

Studies with the Golgi method in central gangliogliomas and dysplastic gangliocytoma of the cerebellum (Lhermitte-Duclos disease)

The rapid Golgi method, combined with current optical and electronmicroscopica1 techniques, was used in three central gangliogliomas and in one dysplastic gangliocytoma of the cerebellum to study the morphology of ganglionic cells. Gangliogliomas were composed of bipolar, fusiform and radiate cells with dense core and clear vesicles in the perikaryon and cellular processes, the number of each cellular type varying from one case to another. These features, together with the fact that isodendritic neurons are considered to be phylogenetically old neurons, suggest that these tumours are composed of 'primitive' neurons that are not homogeneous with regard to their morphology. In contrast, ganglionic cells in dysplastic gangliocytoma are huge cells with long, stereotyped neurites that establish unique asymmetric contacts with neighbouring perikarya and neurites by means of claw-shaped processes covered with synaptic buttons. These morphological characteristics are different from those of any other neuron of the CNS