Search

In the present research the tool of broadband dielectric spectroscopy was utilized to characterize dielectric behavior of Bi6Fe2Ti3O18 (BFTO) Aurivillius-type multiferroic ceramics. Dielectric response of BFTO ceramics was studied in the frequency domain (Δν=0.1Hz – 10MHz) within the temperature range ΔT=-100°C – 200°C. The Kramers-Kronig data validation test was employed to validate the impedance data measurements and it was found that the measured impedance data exhibited good quality justifying further analysis. The residuals were found to be less than 1%, whereas the “chi-square” parameter was within the range χ2~10−7−10−5. Experimental data were analyzed using the circle fit of simple impedance arc plotted in the complex Z”-Z’ plane (Nyquist plot). The total ac conductivity of the grain boundaries was thus revealed and the activation energy of ac conductivity for the grain boundaries was calculated. It was found that activation energy of ac conductivity of grain boundaries changes from EA=0.20eV to EA=0.55eV while temperature rises from T=-100°C up to T=200°C. On the base of maxima of the impedance semicircles (ωmτm=1) the relaxation phenomena were characterized in terms of the temperature dependence of relaxation times and relevant activation energy was calculated (EA=0.55eV).

Aim of the present research was to apply a solid state reaction route to fabricate Aurivillius-type ceramics described with the formula Bi6Fe2Ti3O18 (BFTO) and reveal the influence of processing conditions on its crystal structure. Pressureless sintering in ambient air was employed and the sintering temperatures were 850 and 1080 °C. It was found that the fabricated BFTO ceramics were multiphase ones. They consisted of two Bim+1Fem-3Ti3O3m+3 phases, namely the phase with m=5 (i.e. the stoichiometric phase) and m=4 (i.e. the phase with a reduced number of layers in the slab). Detailed X-ray diffraction patterns analysis showed that both phases adopted the same orthorhombic structure described with Fmm2 (42) space group. The ratio of weight fractions of the constituent phases (m=5): (m=4) was ~30:70.

In the present research the tool of broadband dielectric spectroscopy was utilized to characterize dielectric behavior of Bi6Fe2Ti3O18 (BFTO) Aurivillius-type multiferroic ceramics. Dielectric response of BFTO ceramics was studied in the frequency domain (Δν=0.1Hz - 10MHz) within the temperature range ΔT=-100°C - 200°C. The Kramers-Kronig data validation test was employed to validate the impedance data measurements and it was found that the measured impedance data exhibited good quality justifying further analysis. The residuals were found to be less than 1%, whereas the "chi-square" parameter was within the range χ²~10-7-10-5. Experimental data were analyzed using the circle fit of simple impedance arc plotted in the complex Z"-Z' plane (Nyquist plot). The total ac conductivity of the grain boundaries was thus revealed and the activation energy of ac conductivity for the grain boundaries was calculated. It was found that activation energy of ac conductivity of grain boundaries changes from EA=0.20eV to EA=0.55eV while temperature rises from T=-100°C up to T=200°C. On the base of maxima of the impedance semicircles (ωmτm=1) the relaxation phenomena were characterized in terms of the temperature dependence of relaxation times and relevant activation energy was calculated (EA=0.55eV). [ABSTRACT FROM AUTHOR]

Objective: Stunting is a common cause of early child developmental delay; Guatemala has the fourth highest rate of stunting globally. The goal of this study was to examine the impact of an intensive community health worker-led complementary feeding intervention on early child development in Guatemala. We hypothesised that the intervention would improve child development over usual care., Design: A substudy from a larger individually randomised (1:1 allocation ratio), parallel-group superiority trial, with blinding of study staff collecting outcomes data., Setting: Rural, indigenous Maya communities in Guatemala., Participants: 210 stunted children (height-for-age z-score ≤-2.5) aged 6-24 months, previously randomised to usual care (106) or an intensive complementary feeding intervention (104). 84 in the intervention and 91 in the usual care arm agreed to participate., Interventions: Community health workers conducted monthly home visits for 6 months, providing usual care or individualised complementary feeding education., Main Outcome Measures: The primary outcomes were change in z-scores for the subscales of the Bayley Scales of Infant Development (BSID), Third Edition., Results: 100 individuals were included in the final analysis, 47 in the intervention and 53 in the usual care arm. No statistically significant differences in age-adjusted scores between the arms were observed for any subscale. However, improvements within-subjects in both arms were observed (median duration between measurements 189 days (IQR 182-189)). Mean change for subscales was 0.45 (95% CI 0.23 to 0.67) z-scores in the intervention, and 0.43 (95% CI 0.25 to 0.61) in the usual care arm., Conclusions: An intensive complementary feeding intervention did not significantly improve developmental outcomes more than usual care in stunted, indigenous Guatemalan children. However, both interventions had significant positive impacts on developmental outcomes., Trial Registration Number: NCT02509936., Stage: Results., Competing Interests: Competing interests: BM, MFW and PR are employees or volunteers at Wuqu’ Kawoq, Maya Health Alliance, the non-governmental organisation that provided logistical support for this study in Guatemala. SC, PR, ML, AG and MPG are doctoral students or employees of Universidad del Valle de Guatemala. The authors declare no other relationships or activities that could have influenced the submitted work.

In 20 patients with chronic form of hypersensitivity pneumonitis (HP) pulmonary function tests (FEV(1), FVC, DCO) and high resolution computed tomography (HRCT) scans were obtained. Extent of pathological changes, i.e. nodularity, lines, honeycombing but not ground-glass estimated by HRCT and expressed as a score correlated significantly with lung function abnormalities.