Observation of heavy spin-orbit excitons propagating in a nonmagnetic background: The case of (Ba,Sr)2YIrO6

We present a combined experimental and theoretical study of the elementary magnetic excitations in Ba2YIrO6 and Sr2YIrO6 - the two most intensively discussed candidates for a new type of magnetic instability caused by exciton condensation. For both materials, high-resolution resonant inelastic x-ray scattering (RIXS) at the Ir L3 edge reveals sharp excitations around 370 and 650 meV energy loss, which we identify as triplet and quintet spin-orbit excitons. While the momentum-dependent RIXS spectra reveal that both the triplet and the quintet propagate coherently within the nonmagnetic background of the singlet sites, these modes remain fully gapped. The Ir-Ir exchange interactions in both double perovskites are therefore not strong enough to overcome the magnetic gap and, hence, our results exclude an intrinsic magnetic instability due to a condensation of magnetic excitations for both Ba2YIrO6 and Sr2YIrO6

Leisure perceptions of adolescents [Ergenlerin boş zaman değerlendirme algisi]

Culture which individual belongs to do effect not only his life style but also his leisure perception, attitudes and behavior. This study focuses on 13 year old adolescent’s leisure perceptions, activities and their related feelings considering the gender differences. Data were gathered by survey instrument covering two parts including 3 open-ended questions which were asked to 371 children attending the seventh grade of three elementary schools of Ministry of Education in Izmir (Karşıyaka and Bornova). Descriptive analyze was used. Findings indicated that one-third of the adolescents described leisure “doing nothing and being idle”; half of the males spend time on internet, some females study for the tests; generally, few participated in sports and social activities. Considering the collectivist values dominating the Turkish society, initially starting with the parents, adolescents leisure awareness should be increased and guided by education. © 2012, Hacettepe University. All rights reserved

Examination of tarnish films formed during SCC of alpha-brass in ammoniacal solutions

The tarnish films formed on the sample surfaces during the stress corrosion cracking (SCC) of unannealed and annealed alpha brass (an alloy of 67%Cu-33%Zn) in ammoniacal solution were examined. The color and structure of the films varied depending on the solution pH, temperature and copper concentration of solution. Black tarnish film formed easily in the pH range where the fastest cracking was observed at all temperatures applied. Green tarnish film formation was noticed at higher pH values than the fastest cracking range. Longer failure times were observed in this case. Reddish brown powdery or flaky tarnish film formed at pH values lower than the fastest cracking range and no cracking occurred in this case. All fracture surfaces were yellow-red. The samples cracked faster in higher copper concentrations due to faster oxidation. The tarnish films were examined by SEM and analysed by EDS. Zinc depletion was observed on the sample surfaces in all colors of tarnish film

Microbial corrosion of galvanized steel by a freshwater strain of sulphate reducing bacteria (Desulfovibrio sp.)

Microbially influenced corrosion of galvanized steel was investigated exposing coupons (2.0 x 2.0 cm) to culture of sulphate reducing bacteria strain Desulfouibrio sp. The coupons were exposed to the SRB culture for 4, 8, 24, 72, 96, 168, 360 and 744 h along with a control set in uninoculated medium. The results from the present study suggest that SRB were responsible for the corrosion of the galvanized steel. The corrosion rate of galvanized steel was not be correlated with the number of sessile SRB cells. Also Desulfouibrio sp. had an ability to produce EPS (Extracellular Polimeric Substances) and biodegrade the carbohydrate, that is the predominant component of the EPS produced by them. When Desulfovibrio sp. cells were in logarithmic phase, the concentration of dissolved zinc in the bulk solution was very toxic for Desulfooibrio desulfuricans. (c) 2006 Elsevier Ltd. All rights reserved

Nickel fluoride as a surface activation agent for electroless nickel coating of anodized AA1050 aluminum alloy

European Corrosion Congress (EUROCORR) -- SEP 09-13, 2018 -- Krakow, POLANDIn this study, the use of nickel fluoride tetrahydrate (NiF2 center dot 4H(2)O) as a surface activator and sealant at the same time for the coating of electroless nickel-phosphorus (Ni-P) on anodized aluminum alloy AA1050 is proposed. The usage of the activator resulted in more efficient deposition of Ni-P, improved adhesion properties, and increased wear and friction behavior as opposed to non-activated conditions. Scanning electron microscopy (SEM) and confocal laser microscopy (CLM) analyses of ultramicrotome-cut cross sections of Ni-P coated specimens, surface-activated by NiF2 center dot 4H(2)O, revealed a more well-structured metal-coating interface as opposed to non-activated conditions.TUBITAK (The Scientific and Technological Research Council of Turkey)Turkiye Bilimsel ve Teknolojik Arastirma Kurumu (TUBITAK) [1059814140108, 114M063]; EPSRCEngineering & Physical Sciences Research Council (EPSRC) [EP/R001715/1]; Yildiz Technical UniversityYildiz Technical University [2014-07-02-DOP02]The authors are grateful for financial support from TUBITAK (The Scientific and Technological Research Council of Turkey) through the scholarship grant number 1059814140108 and the project no. 114M063. The authors are also grateful for EPSRC for financial support through LightForm program grant no. EP/R001715/1. M.K. and N.C. express their gratitude Yildiz Technical University for financial support through project no. 2014-07-02-DOP02. M.K. would like address special thanks to Dr. Savkliyildiz, Konya Technical University, for valuable discussion

Impact of commonly used Ag-Cu ion doses on Desulfovibrio sp.: growth and microbiologically induced corrosion against stainless steel

AbstractAg-Cu ions in cooling water may inhibit the activity of sulfate-reducing bacteria and therefore provide solutions to microbiologically induced corrosion (MIC) problems, mainly caused by Desulfovibrio sp. To investigate this, the MIC behavior of Desulfovibrio sp. on 316L stainless steel in terms of growth and extracellular polymeric substances (EPS) production was investigated in the presence of Ag-Cu ions. Laboratory-scale systems were set up with final concentrations of 0.13 ppm Ag and 0.3 ppm Cu ions, as they are the frequently used doses for cooling waters, and operated over 720 hours. The corrosion rate was evaluated by gravimetric assay, scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) analyses. The growth of Desulfovibrio sp. was assessed by bacterial counting and EPS production. Ag-Cu ions in the biofilm were assessed by inductively coupled plasma - optical emission spectrometry (ICP-OES) and EDS-elemental mapping analyses. It was concluded that the ion concentrations used caused an increase in EPS production, especially of protein. The corrosion rate of the metal by Desulfovibrio sp. in the presence of ions was detected as being 29 times higher than that in the sterile medium with the ions after 720 hours. The results suggested that Desulfovibrio sp. exhibited more corrosive behavior in the presence of non-toxic concentrations of Ag-Cu ions.</jats:p

A comparison of four different microleakage tests for assessment of leakage of root canal fillings

Objective. The purpose of this study was to compare four different microleakage tests (dye leakage, electrochemical test, bacterial test and fluid filtration) for evaluation of the coronal seal of teeth obturated using Thermafil or lateral condensation techniques