PbFe1/2Nb1/2O3 ceramics as a base material for electromechanical transducers

PbFe1=2Nb1=2O3 (PFN) material of perovskite structure has been rising interest because it connects both ferroelectric and antiferromagnetic properties. The paper presents tests of PFN ceramics obtained as a result of sintering simple oxides. As comparison, the base composition of the ceramics and composition with lithium admixture was synthesized. Densi cation was carried out using two methods: conventional sintering and hot pressing. XRD patterns, SEM micrographs of fractures surfaces, dielectric and electromechanical properties were performed. Admixing of PFN ceramics with a little amount of lithium allowed obtaining ceramics with better set of parameters from the point of view of their practical usage. The method of densi cation by hot pressing additionally improves these properties

Multiferroic ceramics Pb(Fe1/2Nb1/2)O3 doped by Li

We present the results of obtaining and investigating multiferroic ceramics Pb(Fe1/2Nb1/2)O3 (PFN) and PFN doped by various amounts of Li (PFN:Li). Ceramics have been obtained from oxides by two-step synthesis. For obtained samples the X-ray diffraction patterns, microstructure, DC electric conductivity, the temperature dependencies of dielectric permittivity and dielectric losses, electromechanical properties and hysteresis loops have been investigated. Obtained results have shown that the introduction of Li decreases electric conductivity and improves dielectric and electromechanical parameters important for applications

Technology, physical properties and phase transitions in PMN-PT-PS ceramics

Solid solution of (1-y)[(1-x)Pb(Mg1/3Nb2/3)O3-xPbTiO3]-yPbSnO3 (PMN-PT-PS) investigated in this paper is based on (1-x)PMN-xPT (PMN-PT) where, with increasing x, the transition from relaxor to ferroelectric properties is observed depending on composition. PMN-PT ceramics with 0.25< x <0.4 has been obtained using sol-gel method and next mixed together with PS ceramics obtained from oxides. Final sintering of ceramic samples was pressureless. We present the results of microstructure and XRD investigations, dielectric permittivity and hysteresis loops measurements vs. temperature.[1] T.R. S h r o u t, Z.P. C h a n g, N. K i m, S. M a r k -g r a f, Dielectric behavior of single crystals near the (1-x)PbMg1/3Nb2/3O3-xPbTiO3 morphotropic phase boundary, Ferroelectr. Lett.Sect. 12, 63 (1990). [2] B. N o h e d a, D.E. C o x, G. S h i r a n e, J. G a o, Z.-G. Y e, Phase diagram of the ferroelectric relaxor (1-x)PbMg1/3Nb2/3O3-xPbTiO3, Phys. Rev. B, 66,0541041-0541049 (2002). [3] A.K. S i n g h, D. P a n d e y, Evidence for MB and MC phases in the morphotropic phase boundary region of (1-x)PbMg1/3Nb2/3O3-xPbTiO3: a Rietveld study, Phys.Rev. B, 67, 641021-6410212 (2003). [4] D. Z e k r i a, A.M. G l a z e r, Automatic determination of the morphotropic phase boundary in lead magnesium niobate titanate Pb(Mg1/3Nb2/3)(1 x)Tix O3 within a single crystal using birefringence imaging, J. Appl. Cryst.37, 143-149 (2004). [5] Z.-G. Y e, Y. B i n g, J. G a o et al., Development of ferroelectric order in relaxor (1-x)Pb(Mg1/3Nb2/3)O3–xPbTiO3 (0<x<0.15), Phys. Rev. B 67, 104104 (2003). [6] Z. J i w e i, S. B o, Z. L i a n g y i n g, Y. X i, Preparation and dielectric properties by sol-gel derived PMN-PT powder and ceramic, Materials Chemistry and Physics, 64, 1-4 (2000) [7] R. S k u l s k i, P. W a w r z a ł a, D. B o c h e n e k, K. Ć w i k i e l, Dielectric and electromechanical behaviors of PMN-PT ceramic samples, Journal of Intelligent Material Systems And Structures, 18, 1049-1056 (2007). [8] R. S k u l s k i, P. W a w r z a ł a, J. K o r z e k w a, M. S z y m o n i k, The electrical conductivity of PMN-PTceramics, Archives of Metallurgy and Materials, 54, 717-723 (2009) [9] X. Y h a n g, F. F a n g, Study of the structure and dielectric relaxation behavior of Pb(Mg1/3Nb2/3)O3–PbTiO3 ferroelectric ceramics J. Mater. Res. 14, 4581-4586 (1999)

Technology and electrophysical properties of multiferroic PZT-PFT ceramics

We present the results of obtaining and investigating ceramic samples of solid solution (1-x)(PbZr0:53Ti 0:47O3)-x(PbFe0:5Ta 0:5O3) [i.e. (1-x)PZT-xPFT] with x =0.25, 0.35 and 0.45 obtained using conventional ceramic technology. These materials belong to class of materials known as multiferroics. Solid solutions PZT-PFT are the lowest-loss room-temperature multiferroics known, and as a result there are very interesting for magnetoelectric devices. Paper presents the results of termogravimetric investigations, EDS, XRD and main dielectric measurements. It has been stated that with increasing content of PFT decreases the mean diameter of grains and more wide distribution of grain diameters is observed. For x =0.25 sharp phase transition from ferroelectric phase to paraelectric one is observed and high values of dielectric permittivity. Composition PZT-PFT with x =0.45 has the lowest values of dielectric permittivity, and the transition is more diffused. The increase of x leads also to the shift of the temperature of maximum of dielectric permittivity towards lower temperatures. Samples with x =0.25 and x =0.35 exhibit very low values of dielectric losses up to about 100 C. Dielectric losses for samples with x =0.45 are higher. For obtained PZT-PFT samples we have investigated P–E hysteresis loops at room temperature for frequency 1 Hz. For composition x =0.25 it after application the field about 2.5 kV/mm polarization is equal approximately 28 C/cm2, while for x =0.35, and x =0.45 after application the field about 2.0 kV/mm the polarizations are equal about 25 C/cm2 and 20 C/cm2 respectively. Very low values of losses and high values of polarization lead to the conclusion that interesting material PZT-PFT for applications should be composition with x =0.25.[1] S.-W. C h e o n g, M. M o s t o v o y, Nat. Mat. 6, 13-20 (2007). [2] W. E e r e n s t e i n, N.D. M a t h u r, J.F. S c o t t, Nature 442, 759-765 (2006). [3] Z. S u r o w i a k, D. B o c h e n e k, Arch. Acoust. 33, 2, 243-260 (2008). [4] A.R. L e b e d i n s k a y a, M.F. K u p r i y a n o v, R. S k u l -s k i, Materials Science and Engineering B 83, 119-122 (2001). [5] R. K o l e s o v a, V. K o l e s o v, M. K u p r i y a n o v, R.S k u l s k i, Phase Transitions 68, 621-629 (1999). [6] D. B o c h e n e k, P. K r u k, R. S k u l s k i, P. W a w r z a ł a, J. Electroceram. 26, 8-13 (2011). [7] D.A. S a n c h e z, N. O r t e g a, A. K u m a r, R. R o q u e - M a l h e r b e, R. P o l a n c o, J.F. S c o t t, R.S. K a t i y a r, Aip Advances 1, 042169-1 – 042169-13 (2011). [8] N. L a m p i s, C. F r a n c h i n i, G. S a t t a, A. G e d -d o - L e h m a n n, S. M a s s i d d a, Phys. Rev. B 69, 064412-1 – 064412-12 (2004). [9] W.Z. Z h u, A. K h o l k i n, P.Q. M a n t a s, J.L. B a p t i s t a, J. Eur. Ceram. Soc. 20, 2029-2034 (2000). [10] L.I. S h v o r n e v a, Y.N. V e n e v t s e v, Sov. Phys. JETP 22, 722-724 (1965). [11] S. N o m u r a, H. T a k a b a y a s h i, T. N a k a g a w a, Jpn. J. Appl. Phys. 7, 600-604 (1968). [12] I. B r i x e l, J.P. R i v e r a, A. S t e i n e r, H. S c h m i d, Ferroelectrics 79, 201-204 (1988). [13] D.M. E v a n s, A. S c h i l l i n g, A. K u m a r, D. S a n c h e z, N. O r t e g a, M. A r r e d o n d o, R.S. K a t i -y a r, J.M. G r e g g, J.F. S c o t t, Nature Communications 26, 41534-1 – 41534-7 (2013)

Aspirin desensitization in patients with aspirin-induced and aspirin-tolerant asthma : a double-blind study

Background: Numerous open trials have demonstrated the beneficial clinical effects of aspirin desensitization (AD) in patients with aspirin-induced asthma (AIA). These beneficial effects might be attributable to aspirin’s potent antiinflammatory properties, but that supposition requires further corroboration. Objective: We sought to compare the clinical and biochemical responses to chronic oral AD in 20 patients with AIA and 14 patients with aspirin-tolerant asthma (ATA). All of the patients had chronic rhinosinusitis and nasal polyposis, and these responses were investigated in a pilot, double-blind, placebocontrolled study. Methods: Twelve patients with AIA and 6 patients with ATA were randomly assigned to receive 624 mg of aspirin, and 8 patients with AIA and 8 patients with ATA received placebo. Both aspirin and placebo were administered once daily for 6 months. Nasal symptoms, Sino-Nasal Outcome Test (SNOT20) scores, peak nasal inspiratory flows, Asthma Control Questionnaire scores, spirometric parameters, peak expiratory flows, blood eosinophilia, and corticosteroid doses were assessed on a monthly basis. Levels of urinary leukotriene E4 and the stable plasma prostaglandin (PG) D2 metabolite 9a,11b-PGF2 were evaluated at baseline and after 1, 3, 5, and 6 months. Results: Only the patients with AIA subjected to AD reported improvements in smell and reductions in sneezing and nasal blockade. The SNOT20 and Asthma Control Questionnaire scores of these patients decreased, and their peak nasal inspiratory flows increased. The dosages of inhaled corticosteroids were reduced. There were no changes in leukotriene E4 or 9a,11b-PGF2 levels after AD. Conclusion: The clinically beneficial effects of AD on nasal and bronchial symptoms occurred only in the patients with AIA

Anomalous origin of culprit coronary arteries in acute coronary syndromes

Background: The aim of the study was to describe a series of acute coronary syndrome (ACS) patients in whom anomalous origin of culprit coronary artery (AOCCA) was diagnosed. Percutaneous coronary interventions (PCI) in AOCCA are performed very infrequently. Methods: Electronic databases from three high-volume tertiary cardiac centers were retrospectively searched for the presence of AOCCA in ACS. Results: Different types of AOCCA in ACS were identified in 20 patients. The most frequent AOCCA was left circumflex coronary artery (LCx) originating from right coronary artery (RCA) or directly from the right coronary sinus (RCS), n = 13, followed by high/atypical RCA, n = 3, left coronary artery (LCA) originating from RCS (n = 3) with either RCA-AOCCA (n = 1) or left anterior descending coronary artery (LAD)-AOCCA (n = 1) or RCA originating from left sinus of Valsalva, (n = 1), LAD originating from RCA (n = 1). In 1 ST-segment elevation myocardial infarction (STEMI)-patient RCA-AOCCA cannulation was unsuccessful, in 1 non-STEMI-patient AOCCA was missed, 1 ACS- -patient was treated surgically and 1 ACS-patient was treated conservatively (both patients with non- STEMI). In the remaining patients PCI was successfully performed. Conclusions: The most frequently encountered AOCCA is LCx branching-off from RCA. AOCCA may either be difficult to cannulate and PCI aborted even in STEMI, or missed, especially when the intermediate branch from LCA is mimicking proper LCx

Advanced ankylosing spondylitis diagnosed after infection of the digestive tract — case report

Inflammatory spondyloarthrophaties (SpA) are a group of diseases with a close aetiology and clinical course. Infections , especially bacterial, of the digestive tract are possible causes of SpA. Infectious pathogens may penetrate the mucous membrane of the gastrointestinal tract, of the urogenital tracts, respiratory tract and induce the reactive arthritis or exacerbate the previously diagnosed, chronic SpA. Dysbiosis also plays an important role in the pathogenesis of SpA. In the report, authors presented a case of a patient with a long-time backbone pain, in whom Yersinia enterocolitica infection of the digestive tract preceded the peripheral arthritis and inflammatory pain of the spine. The radiological images showed the characteristic changes of the advanced ankylosing spondylitis

Small vessel coronary artery disease: How small can we go with myocardial revascularization?

The issue of small coronary artery atherosclerosis represents an intriguing aspect of coronary artery disease, which is related with higher rates of peri- and post-procedural complications and impaired long-term outcome. This problem is further complicated by the unclear definition of small coronary vessel. Recent randomized controlled trials have provided new data on possible novel interventional treatment of small coronary vessels with drug-coated balloons instead of traditional new-generation drug-eluting stent implantation. Also, the conservative management represents a therapeutic option in light of the results of the recent ISCHEMIA trial. The current article provides an overview of the most appropriate definition, interventional management, and prognosis of small coronary artery atherosclerosis