Search

High-entropy pyrochlore iridates A2Ir2O7 with multiple trivalent A cations were synthesized. The parent ternary A2Ir2O7 displays a variety of electronic phases depending on the size of A cations; Pr2Ir2O7 with a large A cation shows semimetallic behavior down to low temperatures, whereas A2Ir2O7 with smaller A cations, such as Nd2Ir2O7 and Eu2Ir2O7, displays a (semi)metal to magnetic insulator transition as a function of temperature. By further reducing the A cation size, smaller than Y3+, A2Ir2O7 becomes a Mott insulator, and long-range magnetic order takes place below room temperature. The metal–insulator transition and magnetic ordering turned out to be robust against strong disorder induced by the mixing of more than five A-cations in the high-entropy A2Ir2O7. The transition temperatures were found to scale with the average ionic radius of multiple A-cations. In contrast, high-entropy A2Ir2O7 including Bi3+ exhibits metallic behavior down to 2 K, which is likely associated with the presence of oxygen vacancies as in the parent Bi2Ir2O7. Although these indicate that the overall electronic structure of A2Ir2O7 remains intact in the presence of high-entropy configuration at the A-site, the transport properties suggest that fine details of the band structure may be modulated by local distortion. Strong disorder at the A-site of complex oxides may be exploited as a tool to control electronic properties. [ABSTRACT FROM AUTHOR]

Examines polyolefin-organoclay nanocomposites containing a synthetic tetrasilisic fluoromica. Preparation of the nanocomposites from metallocene-catalyzed and conventional Ziegler-Natta-catalyzed linear low-density polyethylenes; Effects of maleic-anhydride grafted compatibilizer; Crystallization; Dynamic mechanical thermal analysis.

A pilot study was conducted to determine whether 3-monthly groin ultrasonography could eliminate groin dissection after a negative bilateral groin ultrasound in three groups of patients: (i) Those with a unifocal stage 1B squamous cell carcinoma of up to 20 mm in diameter. (ii) Those with an ipsilateral squamous cell carcinoma of any size which extended to within 1 cm either side of the midline. These patients underwent ipsilateral inguinofemoral lymphadenectomy and ultrasonic surveillance of the contralateral groin. (iii) Patients with multifocal invasive lesions with the largest individual focus 20 mm or less in diameter. Three additional patients were added because they either refused groin dissection or were considered unfit for surgery. All ultrasonically positive nodes were confirmed histologically. Thirty-two patients were entered, and no patients were lost to follow-up. Forty-three groins were followed. With a median follow-up of 37 months, three positive nodes (9.4%) were detected. One patient died of her recurrence (3.1%), and 39 groins (90.7%) were preserved. The overall sensitivity of ultrasonic surveillance was 100% (95% CI: 44-100%), with a specificity of 97% (95% CI: 83-99%) and a negative predictive value of 100% (95% CI: 88-100%). This pilot justifies a larger study on serial ultrasonography in lieu of groin dissection in selected patients with vulvar cancer.

Purpose: To examine the relationship between age and ovarian perifollicular blood flow (PFBF) in women undergoing IVF., Methods: Serial transvaginal power Doppler ultrasound (PDU) scans to assess ovarian PFBF were performed prospectively throughout the follicular phase of ovarian stimulation in women undergoing IVF. The ultrasound assessment days were categorized according to day of hCG trigger., Results: A total of 1050 ovarian follicles from 34 women undergoing one IVF treatment cycle were used for data analysis. The median age of the women was 38.5 years, ranging from 28 years to 44 years. There was a significant negative correlation between age and ovarian PFBF on the day of hCG trigger or trigger day minus 1, but not beforehand during the follicular phase., Conclusions: There was a significant negative correlation between age and ovarian PFBF in women undergoing IVF which was only observed very late in the follicular phase of ovarian stimulation.

Objective: To evaluate whether ovarian perifollicular blood flow (PFBF) varies by ultrasound among women with polycystic and normal ovaries undergoing in vitro fertilization (IVF)., Design: Prospective observational cohort study of women undergoing IVF treatment., Setting: Department of reproductive medicine at a university teaching hospital., Patient(s): Thirty four women with regular spontaneous ovulatory menstrual cycles undergoing IVF divided into two groups according to findings on a baseline transvaginal ultrasound scan: group 1 consisted of 20 women with ultrasound-evident normal ovaries (USNO group), and group 2 consisted of 14 women with ultrasound-evident polycystic ovaries (USPCO group)., Intervention(s): Serial transvaginal power Doppler ultrasound assessments throughout the follicular phase of ovarian stimulation., Main Outcome Measure(s): Ovarian PFBF and ovarian stromal artery pulsatility index., Result(s): Women with USPCO had a significantly lower ovarian stromal artery pulsatility index at the time of the first ultrasound assessment before starting the FSH injections compared with USNO women. However, there was no difference in ovarian PFBF between women with USPCO and USNO during the follicular phase of ovarian stimulation for IVF., Conclusion(s): There is no difference in ovarian follicular vascularity between women with polycystic and normal ovaries during ovarian stimulation at IVF treatment.