Mn-Doped CaBi4Ti4O15/Pb(Zr,Ti)O3 Ultrasonic Transducers for Continuous Monitoring at Elevated Temperatures.

Continuous ultrasonic in-situ monitoring for industrial applications is difficult owing to the high operating temperatures in industrial fields. It is expected that ultrasonic transducers consisting of a CaBi4Ti4O15(CBT)/Pb(Zr,Ti)O3(PZT) sol-gel composite could be one solution for ultrasonic nondestructive testing (NDT) above 500 °C because no couplant is required and CBT has a high Curie temperature. To verify the high temperature durability, CBT/PZT sol-gel composite films were fabricated on titanium substrates by spray coating, and the CBT/PZT samples were tested in a furnace at various temperatures. Reflected echoes with a high signal-to-noise ratio were observed up to 600 °C. A thermal cycle test was conducted from room temperature to 600 °C, and no significant deterioration was found after the second thermal cycle. To investigate the long-term high-temperature durability, a CBT/PZT ultrasonic transducer was tested in the furnace at 600 °C for 36 h. Ultrasonic responses were recorded every 3 h, and the sensitivity and signal-to-noise ratio were stable throughout the experiment.

Lead-Free Piezoelectric Transducers.

Research activities on lead-free piezoelectric materials have been ongoing for over 20 years. Generally, the applicability of the main material families is less universal than that of lead-based compositions such as lead zirconate titanate, but in some cases, the corresponding applications have already been identified. Due to the extensive research, it is now possible to manufacture demonstrators and prototypes for different applications and the authors propose in this article to take stock of these advances. For this, we have chosen to first recall briefly the main new material systems using a simplistic "soft" and "hard" classification for approaching the various resonant transducer applications. Medical imaging applications that represent one of the most important fields are presented in a second step together with other low-power transducers. Then, a variety of applications are merged under the heading of high-power transducers. In addition, we mention two points that are important to consider when manufacturing at a larger scale. For the design of transducers, complete datasets must be available, especially if modeling tools are used. Finally, the commercialization of these lead-free materials imposes essential secondary requirements in terms of availability, reproducibility, sample size, and so on.

Encephalopathy, disseminated intravascular coagulation, and hemolytic-uremic syndrome after infection with enterohemorrhagic Escherichia coli O111.

An outbreak of enterohemorrhagic Escherichia coli (EHEC) occurred in Toyama and other prefectures in Japan during 2011. Some patients, including adults, showed complications such as encephalopathy, disseminated intravascular coagulation, and hemolytic-uremic syndrome, and the disease course was extremely aggressive. This report describes the clinical features of four patients infected with Escherichia coli (E. coli) O111 who developed very severe to fatal complications. The initial symptoms in all patients included abdominal pain, diarrhea, and bloody stools, and neurological abnormalities started to appear from 1 to 3 days after admission. Vomiting and pyrexia developed in three patients. Leukocyte counts, lactate dehydrogenase (LDH), and fibrin/fibrinogen degradation products were elevated, and thrombocytopenia was evident. Extremely elevated LDH and severe thrombocytopenia were characteristic at the time encephalopathy became apparent. All patients received oral fosfomycin, intravenous antibiotics, and anticoagulant therapy, three received gamma globulin, plasma exchange, and blood transfusion, and two received steroids and dialysis. Three patients required mechanical ventilation, and two adult patients died. E. coli O111 positive for Shiga toxin 2 was detected in stool culture in two patients, and serological tests for E. coli O111 were positive in the other two patients. In conclusion, EHEC O111 can cause severe illness in children and adults, and the prognosis becomes poorer as the severity of complications increases. Close monitoring including platelet counts and LDH are useful. Once these clinical parameters change, intensive treatment should be provided to prevent the development of severe complications.

Antibiotic treatment for bacterial meningitis caused by Listeria monocytogenes in a patient with multiple myeloma.

Multiple myeloma is a hematolymphoid malignancy, and patients with this disorder are frequently complicated by infection. An 80-year-old woman with multiple myeloma was complicated by bacterial meningitis, and was admitted to our hospital in August 2007. She initially received ceftriaxone, but culture of cerebrospinal fluid detected Listeria monocytogenes. Ampicillin was administered, but headache and pyrexia persisted for 2 weeks, and on cerebrospinal fluid examination, the proliferation of polymorphonuclear leukocytes had not resolved. After medication with meropenem was started, the clinical symptoms completely disappeared, and the abnormalities on cerebrospinal fluid examination resolved. The patient ultimately received meropenem for 27 days, resulting in a cure. In conclusion, meropenem is useful to treat bacterial meningitis caused by L. monocytogenes. This agent is indicated when ampicillin shows inadequate effect or if the patient has an allergy to ampicillin.

Phase-transition temperatures and piezoelectric properties of (Bi1/2Na1/2)TiO3-(Bi1/2Li1/2)TiO3-(Bi1/2K1/2)TiO3 lead-free ferroelectric ceramics.

The phase-transition temperatures and piezoelectric properties of x(Bi(1/2)Na(1/2))TiO3-y(Bi(1/2)Li(1/2))TiO3-z(Bi(1/2)K(1/2))TiO3 [x + y + z = 1] (abbreviated as BNLKT100(y)-100(z)) ceramics were investigated. These ceramics were prepared using a conventional ceramic fabrication process. The phase-transition temperatures such as depolarization temperatures T(d), rhombohedraltetragonal phase transition temperature T(R-T), and dielectric-maximum temperature T(m) were determined using electrical measurements such as dielectric and piezoelectric properties. The X-ray powder diffraction patterns of BNLKT100(y)-100(z)) show the morphotropic phase boundary (MPB) between rhombohedral and tetragonal at approximately z = 0.20, and the piezoelectric properties show the maximum at the MPB. The electromechanical coupling factor k(33), piezoelectric constant d(33) and T(d) of BNLKT4-20 and BNLKT8-20 were 0.603, 176 pC/N, and 171 degrees C, and 0.590, 190 pC/N, and 115 degrees C, respectively. In addition, the relationship between d33 and Td of tetragonal side and rhombohedral side for BNLKT4-100z and BNLKT8-100z were presented. Considering both high Td and high d(33), the tetragonal side of BNLKT4-100z is thought to be the superior composition. The d(33) and T(d) of BNLKT4-28 were 135 pC/N and 218 degrees C, respectively. Moreover, this study revealed that the variation of T(d) is related to the variation of lattice distortion such as rhombohedrality 90-alpha and tetragonality c/a.

Piezoelectric properties in (K0.5Bi0.5)TiO3-(Na0.5Bi0.5)TiO3-BaTiO3 lead-free ceramics.

Lead-free piezoelectric ceramics with compositions around the morphotropic phase boundary (MPB) x(Na0.5Bi0.5)TiO3-y(K0.5Bi0.5)TiO3-zBaTiO3 [x + y + z = 1; y:z = 2:1] were synthesized using conventional, solid-state processing. Dielectric maximum temperatures of 280 degrees C and 262 degrees C were found for tetragonal 0.79(Na0.5Bi0.5)TiO3-0.14(K0.5Bi0.5)TiO3-0.07BaTiO3 (BNBK79) and MPB composition 0.88(Na0.5Bi0.5)TiO3-0.08(K0.5Bi0.5)TiO3-0.04BaTiO3 (BNBK88), with depolarization temperatures of 224 degrees C and 162 degrees C, respectively. Piezoelectric coefficients d33 were found to be 135 pC/N and 170 pC/N for BNBK79 and BNBK88, and the piezoelectric d31 was determined to be -37 pC/N and -51 pC/N, demonstrating strong anisotropy. Coercive field values were found to be 37 kV/cm and 29 kV/cm for BNBK79 and BNBK88, respectively. The remanent polarization of BNBK88 (approximately 40 microC/cm2) was larger than that of BNBK79 (approximately 29 microC/cm2). The piezoelectric, electromechanical, and high-field strain behaviors also were studied as a function of temperature and discussed.

Phase transition temperatures and piezoelectric properties of (Bi(1/2)Na(1/2))TiO3- and (Bi(1/2)K(1/2))TiO3-based bismuth perovskite lead-free ferroelectric ceramics.

The phase transition temperatures and the dielectric, ferroelectric, and piezoelectric properties of bismuth perovskite lead-free ferroelectric ceramics such as (Bi(1/2)Na(1/2))TiO3 (BNT)- and (Bi(1/2)Na(1/2))TiO3 (BKT)-based solid solutions have been reviewed. According to the results obtained by our group, these ceramics can be considered as superior lead-free piezoelectric materials for reducing environmental damage. Perovskite-type ceramics appear to be suitable for actuator and high-power applications that require a large piezoelectric constant d33 and a high Curie temperature TC or a high depolarization temperature Td (> 200 degrees C). In this paper, we summarize the relationship between phase transition temperatures and piezoelectric properties. In the case of the BNT-based solid solutions, the highest piezoelectric properties were obtained at the morphotropic phase boundary (MPB) between rhombohedral and tetragonal phases. However, d33 and Td were shown to have a tradeoff relationship. Considering the high Td and high d33, the tetragonal side of the MPB composition is suitable for piezoelectric actuator application. Meanwhile, the Qm values on the rhombohedral side of the MPB composition were better than those on the tetragonal side, and excellent high-power characteristics were obtained for Mn-doped BNT-(Bi(1/2)Na(1/2))TiO3-BKT ternary systems with rhombohedral symmetry. BKT ceramics were prepared by the hot-pressing (HP) method, and their ferroelectric and piezoelectric properties were clarified. BKT ceramics doped with a small amount of Bi have a relatively high remanent polarization of Pr = 27.6 microC/cm2 and high piezoelectric properties (k33 = 0.40 and d33 = 101 pC/N). In addition, it was clarified that BKT ceramics have a high Td of approximately 300 degrees C. The solid solution (1-x)BKT-xBaTiO3 (BKT-BT100x) exhibited a high Td of approximately 300 degrees C at x > 0.4.