ObjectiveTo evaluate the effectiveness of low-frequency TENS (LFT) and high-frequency
TENS (HFT) in post-episiotomy pain relief. MethodA randomized, controlled, double-blind clinical trial with placebo composed
of 33 puerperae with post-episiotomy pain. TENS was applied for 30 minutes
to groups: HFT(100 Hz; 100 µs), LFT (5 Hz; 100 µs), and
placebo (PT). Four electrodes were placed in parallel near the episiotomy
and four pain evaluations were performed with the numeric rating scale. The
first and the second evaluation took place before TENS application and
immediately after its removal and were done in the resting position and in
the activities of sitting and ambulating. The third and fourth evaluation
took place 30 and 60 minutes after TENS removal, only in the resting
position. Intragroup differences were verified using the Friedman and
Wilcoxon tests, and the intergroup analysis employed the Kruskal-Wallis
test. ResultsIn the intragroup analysis, there was no significant difference in the PT
during rest, sitting, and ambulation (P>0.05). In the HFT and LFT, a
significant difference was observed in all activities (P<0.001). In the
intergroup analysis, there was a significant difference in the resting
position in the HFT and LFT (P<0.001). In the sitting activity, a
significant difference was verified in the second evaluation in the HFT and
LFT (P<0.008). No significant difference was verified among the groups in
ambulation (P<0.20). ConclusionsLFT and HFT are an effective resource that may be included in the routine of
maternity wards.
The considerable decrease in temperature and time makes FLASH sintering a more sustainable alternative for materials processing. FLASH also becomes relevant if volatile elements are part of the material to be processed, as in alkali-based piezoelectrics like the promising lead-free K0.5Na0.5NbO3 (KNN). Due to the volatile nature of K and Na, KNN is difficult to process by conventional sintering. Although some studies have been undertaken, much remains to be understood to properly engineer the FLASH sintering process of KNN. In this work, the effect of FLASH temperature, TF, is studied as a function of the particle size and impurity content of KNN powders. Differences are demonstrated: while the particle size and impurity degree markedly influence TF, they do not significantly affect the densification and grain growth processes. The conductivity of KNN FLASH-sintered ceramics and KNN single crystals (SCs) is compared to elucidate the role of particles’ surface conduction. When particles’ surfaces are not present, as in the case of SCs, the FLASH process requires higher temperatures and conductivity values. These results have implications in understanding FLASH sintering towards a more sustainable processing of lead-free piezoelectrics.
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