Magnetic and dielectric properties of multiferroic Eu0.5Ba0.25Sr0.25TiO3 ceramics

Dielectric and magnetic properties of Eu0.5Ba0.25Sr0.25TiO3 are investigated between 10 K and 300 K in the frequency range from 10 Hz to 100 THz. A peak in permittivity revealed near 130 K and observed ferroelectric hysteresis loops prove the ferroelectric order below thistemperature. The peak in permittivity is given mainly by softening of the lowest frequency polar phonon (soft mode revealed in THz and IR spectra) that demonstrates displacive character of the phase transition. Room-temperature X-ray diffraction analysis reveals cubic structure, but the IR reflectivity spectra give evidence of a lower crystal structure, presumably tetragonal I4/mcm with tilted oxygen octahedra as it has been observed in EuTiO3. The magnetic measurements show that the antiferromagnetic order occurs below 1.8 K. Eu0.5Ba0.25Sr0.25TiO3 has three times lower coercive field than Eu0.5Ba0.5TiO3, therefore we propose this system for measurements of electric dipole moment of electron.Comment: Phase Transitions, in pres

Anatomical considerations and emerging strategies for reducing new onset conduction disturbances in percutaneous structural heart disease interventions

Transcatheter procedures offer an alternative to cardiac surgery in select patients with structural heart disease (SHD). Unfortunately, inadvertent disruption of electrical pathways and subsequent development of new onset conduction disturbances can occur in up to 5–70% of percutaneous interventions, result in pacemaker implantation, and confer a worse prognosis. The physical proximity between the conduction system (atrioventricular node, bundle of His, and bundle branches) and the site of percutaneous repair is increasingly recognized as a key factor influencing new onset conduction disturbance development in procedures located near the conduction system. This review covers the incidence, clinical significance, and mechanisms of new onset conduction disturbances and discusses current and emerging strategies to address this complication in these populations

A two-prong approach of beneficial reuse of alum sludge in engineered wetland : first experience from Ireland

Effective management of the industrial waste requires a sustainable approach that maximizes its value of reuse/recycle for other industrial demands and the environment needs. This paper aims in exploring the potential of the intended purposes in the newly developed dewatered aluminum-water treatment sludge (Al-WTS) based engineered wetland (EW) for wastewater treatment. Due to the low energy requirement and aesthetical appearance EW is seen as a ‘green’ wastewater treatment technique worldwide for a wide variety of wastewater treatment. The Al-WTS based EW developed at University College Dublin, Ireland, represents the latest initiative at using engineering ingenuity to further improve EWs performance. This paper summarizes the background of development and the results derived from different phases of the development of Al-WTS based EW.Other funderEnvironmental Protection AgencyDepartment of Agriculture, Fisheries and Foo

The influence of metakaolin substitution by slag in alkali-activated inorganic binders for civil engineering

V této studii byl zkoumán účinek náhrady metakaolínu mletou vysokopecní struskou v alkalickém geopolymerním pojivu z pohledu jejich reologických a mechanických vlastností. Bylo prokázáno, že přidávání strusky do pojiva může zlepšit mechanické vlastnosti konečných produktů. Naše zkoumání bylo zaměřeno na široký interval substituce metakaolinů v rozmezí od 100 do 40 objemových procent metakaolinu, kdy objem pevných látek v konečném pojivu zůstal konstantní. Připravená pojidla byla aktivována alkalickým roztokem křemičitanu draselného s křemičitanovým modulem 1,61. Analýzy velikosti částic byly prováděny pro stanovení distribuce velikosti částic. Reologické vlastnosti byly stanoveny v souladu s průtokovými vlastnostmi měřeními na Fordově výtokovém poháru a oscilačním měřením procesu vytvrzování. Pro zkoumání procesu vytvrzování byla v geometrii rovinných desek použita oscilační reometrie s malou amplitudou řízená deformací. Pro stanovení aplikačních mechanických vlastností byly pojiva plněna keramickým ostřivem v rozmezí zrnitosti 0-1 mm. Plnění bylo udržováno konstantních 275 objemových procent vzhledem k suchému pojivu. Mechanické vlastnosti byly zkoumány po 1, 7 a 28 dnech a mikrostruktura byla dokumentována rastrovací elektronovou mikroskopií. Výsledky ukazují, že přídavek strusky má příznivý účinek nejen na mechanické vlastnosti tvrzeného pojiva, ale také na tokové vlastnosti čerstvé geopolymerní pasty a následné kinetiky vytvrzení alkalicky aktivovaných pojiv.In this study the effect of metakaolin replacement by milled blast furnace slag in alkali-activated geopolymeric binder was investigated in accordance to their rheological and mechanical properties. It was demonstrated that slag addition into the metakaolin binder can improve mechanical properties of final products. Our investigation was focused on broad interval of metakaolin substitution in the range from 100 to 40 volume per cents of metakaolin so that the volume content of solids in final binder was maintained constant. Prepared binders were activated by alkaline solution of potassium silicate with silicate module of 1.61. The particle size analyses were performed for determination of particle size distribution. The rheological properties were determined in accordance to flow properties by measurements on Ford viscosity cup and by oscillatory measurements of hardening process. For the investigation of hardening process, the strain controlled small amplitude oscillatory rheometry was used in plane-plate geometry. For determination of applied mechanical properties were binders filled by ceramic grog in the granularity range 0-1 mm. The filling was maintained constant at 275 volume per cents in accordance to ratio of solids in dry binder. The mechanical properties were investigated after 1, 7 and 28 days and microstructure was documented by scanning electron microscopy. The results indicate that slag addition have beneficial effect not only on mechanical properties of hardened binder but also on flow properties of fresh geopolymer paste and subsequent hardening kinetics of alkali-activated binders