Negative Poisson’s ratio polyethylene matrix and 0.5BaCa0.8Zr0.2O3-0.5Ba0.7Ca0.3TiO3 based piezocomposite for sensing and energy harvesting applications

Abstract Finite element studies were conducted on 0.5Ba(Zr0.2 Ti0.8) O3–0.5(Ba0.7 Ca0.3)TiO3 (BCZT) piezoelectric particles embedded in polyethylene matrix to create a piezocomposite having a positive and negative Poisson's ratio of −0.32 and 0.2. Polyethylene with a positive Poisson's ratio is referred to as non-auxetic while those with negative Poisson's ratio are referred to as auxetic or inherently auxetic. The effective elastic and piezoelectric properties were calculated at volume fractions of (4%, 8% to 24%) to study their sensing and harvesting performance. This study compared lead-free auxetic 0–3 piezocomposite for sensing and energy harvesting with non-auxetic one. Inherently auxetic piezocomposites have been studied for their elastic and piezoelectric properties and improved mechanical coupling, but their sensing and energy harvesting capabilities and behavior patterns have not been explored in previous literatures. The effect of Poisson's ratio ranging between −0.9 to 0.4 on the sensing and energy harvesting performance of an inherently auxetic lead free piezocomposite composite with BCZT inclusions has also not been studied before, motivating the author to conduct the present study. Auxetic piezocomposite demonstrated an overall improvement in performance in terms of higher sensing voltage and harvested power. The study was repeated at a constant volume fraction of 24% for a range of Poisson's ratio varied between −0.9 to 0.4. Enhanced performance was observed at the extreme negative end of the Poisson's ratio spectrum. This paper demonstrates the potential improvements by exploiting auxetic matrices in future piezocomposite sensors and energy harvesters

Reducing the environmental impact of surgery on a global scale: systematic review and co-prioritization with healthcare workers in 132 countries

Abstract Background Healthcare cannot achieve net-zero carbon without addressing operating theatres. The aim of this study was to prioritize feasible interventions to reduce the environmental impact of operating theatres. Methods This study adopted a four-phase Delphi consensus co-prioritization methodology. In phase 1, a systematic review of published interventions and global consultation of perioperative healthcare professionals were used to longlist interventions. In phase 2, iterative thematic analysis consolidated comparable interventions into a shortlist. In phase 3, the shortlist was co-prioritized based on patient and clinician views on acceptability, feasibility, and safety. In phase 4, ranked lists of interventions were presented by their relevance to high-income countries and low–middle-income countries. Results In phase 1, 43 interventions were identified, which had low uptake in practice according to 3042 professionals globally. In phase 2, a shortlist of 15 intervention domains was generated. In phase 3, interventions were deemed acceptable for more than 90 per cent of patients except for reducing general anaesthesia (84 per cent) and re-sterilization of ‘single-use’ consumables (86 per cent). In phase 4, the top three shortlisted interventions for high-income countries were: introducing recycling; reducing use of anaesthetic gases; and appropriate clinical waste processing. In phase 4, the top three shortlisted interventions for low–middle-income countries were: introducing reusable surgical devices; reducing use of consumables; and reducing the use of general anaesthesia. Conclusion This is a step toward environmentally sustainable operating environments with actionable interventions applicable to both high– and low–middle–income countries

Mortality from gastrointestinal congenital anomalies at 264 hospitals in 74 low-income, middle-income, and high-income countries: a multicentre, international, prospective cohort study

Summary Background Congenital anomalies are the fifth leading cause of mortality in children younger than 5 years globally. Many gastrointestinal congenital anomalies are fatal without timely access to neonatal surgical care, but few studies have been done on these conditions in low-income and middle-income countries (LMICs). We compared outcomes of the seven most common gastrointestinal congenital anomalies in low-income, middle-income, and high-income countries globally, and identified factors associated with mortality. Methods We did a multicentre, international prospective cohort study of patients younger than 16 years, presenting to hospital for the first time with oesophageal atresia, congenital diaphragmatic hernia, intestinal atresia, gastroschisis, exomphalos, anorectal malformation, and Hirschsprung’s disease. Recruitment was of consecutive patients for a minimum of 1 month between October, 2018, and April, 2019. We collected data on patient demographics, clinical status, interventions, and outcomes using the REDCap platform. Patients were followed up for 30 days after primary intervention, or 30 days after admission if they did not receive an intervention. The primary outcome was all-cause, in-hospital mortality for all conditions combined and each condition individually, stratified by country income status. We did a complete case analysis. Findings We included 3849 patients with 3975 study conditions (560 with oesophageal atresia, 448 with congenital diaphragmatic hernia, 681 with intestinal atresia, 453 with gastroschisis, 325 with exomphalos, 991 with anorectal malformation, and 517 with Hirschsprung’s disease) from 264 hospitals (89 in high-income countries, 166 in middleincome countries, and nine in low-income countries) in 74 countries. Of the 3849 patients, 2231 (58·0%) were male. Median gestational age at birth was 38 weeks (IQR 36–39) and median bodyweight at presentation was 2·8 kg (2·3–3·3). Mortality among all patients was 37 (39·8%) of 93 in low-income countries, 583 (20·4%) of 2860 in middle-income countries, and 50 (5·6%) of 896 in high-income countries (p<0·0001 between all country income groups). Gastroschisis had the greatest difference in mortality between country income strata (nine [90·0%] of ten in lowincome countries, 97 [31·9%] of 304 in middle-income countries, and two [1·4%] of 139 in high-income countries; p≤0·0001 between all country income groups). Factors significantly associated with higher mortality for all patients combined included country income status (low-income vs high-income countries, risk ratio 2·78 [95% CI 1·88–4·11], p<0·0001; middle-income vs high-income countries, 2·11 [1·59–2·79], p<0·0001), sepsis at presentation (1·20 [1·04–1·40], p=0·016), higher American Society of Anesthesiologists (ASA) score at primary intervention (ASA 4–5 vs ASA 1–2, 1·82 [1·40–2·35], p<0·0001; ASA 3 vs ASA 1–2, 1·58, [1·30–1·92], p<0·0001]), surgical safety checklist not used (1·39 [1·02–1·90], p=0·035), and ventilation or parenteral nutrition unavailable when needed (ventilation 1·96, [1·41–2·71], p=0·0001; parenteral nutrition 1·35, [1·05–1·74], p=0·018). Administration of parenteral nutrition (0·61, [0·47–0·79], p=0·0002) and use of a peripherally inserted central catheter (0·65 [0·50–0·86], p=0·0024) or percutaneous central line (0·69 [0·48–1·00], p=0·049) were associated with lower mortality. Interpretation Unacceptable differences in mortality exist for gastrointestinal congenital anomalies between lowincome, middle-income, and high-income countries. Improving access to quality neonatal surgical care in LMICs will be vital to achieve Sustainable Development Goal 3.2 of ending preventable deaths in neonates and children younger than 5 years by 2030

GPS based total electron content (TEC) anomalies and their association with large magnitude earthquakes occurred around Indian region

131-135In this paper, the effect of earthquakes on total electron content (TEC) data at Agra (geographic latitude 27.2°N, longitude 78°E), India has been examined. This study has been carried out for a period of 30 months from 01 January 2009 to 30 June 2011 and a dual frequency GPS receiver system is used for recording TEC data. To investigate the seismic effects on TEC, an epicentral distance of 2000 km from the observing station has been selected. This region includes 22 cases of earthquakes during the period of study with large magnitudes (M ≥  5.5). Different statistical procedures are used to observe the anomalies in TEC data. The results show that TEC fluctuated in the form of enhancements and depletion and maximum precursors are found 5-10 days prior to these earthquakes. The solar and geomagnetic activities during the cases of earthquakes have also been studied and data on disturbed days are omitted to separate out the seismic effects. Hence, the observed TEC anomalies may be due to the occurrences of large magnitude earthquakes around Indian region. The E×B drift due to the electric field generation during earthquake preparation process and ground wave oscillations may possibly be the significant contributors of these anomalies in TEC data

Diurnal and seasonal variation of GPS-TEC during a low solar activity period as observed at a low latitude station Agra

26-36Employing a dual frequency GPS receiver at a low latitude station Agra (geographic lat 27.120N, long 78.890E, dip 41.10), India (located just outside the equatorial anomaly crest), the measurement of ionospheric total electron content (TEC) has been carried out since 24 June 2006. Three years of data for a low solar activity period during 01 August 2006 - 31 July 2009 has been analysed. The temporal, seasonal and solar activity dependence of GPS-TEC data has been studied for the ionospheric region around Agra. The results show that the mean TEC varies from a minimum at 0500 hrs LT (LT=UT+5.5 hrs) to a peak value at about 1400 hrs LT and then decreases. The lowest values of TEC have been observed in winter whereas highest values have been observed in equinox and summer. The variation of the data has been compared with the variation of three solar indices, i.e. EUV flux, 10.7 cm solar radio flux (F10.7), and sunspot numbers (SSN) during the period of analysis. It is found that all the solar indices show high correlation with day maximum TEC (TECmax) in the summer than in equinox and low correlation is shown in winter season. It is also found that the data show high correlation with F10.7 in the two seasons of summer and equinox while the same is found with EUV flux in winter. The correlation of TECmax and SSN is found to be low as compared to those of F10.7 and EUV flux in all seasons. The GPS-TEC data obtained at Agra station for the year 2009 has also been compared with global ionospheric maps (GIMs) of TEC and a very good correlation is found between the two. Further, GIMs of TEC have been analysed for five different latitudes along the common meridian of 800E longitude. The present study has been carried out for three months of the year 2009 in each season. The role of equatorial ionization anomaly (EIA) crest is clearly visible on TEC data. These results are significant for Agra station which is a new location in the low latitude sector of Indian region

Magnetospherically reflected (MR) whistlers observed in DEMETER satellite and on the ground observation of normal whistlers at low latitudes

97-104The DEMETER (Detection of Electromagnetic Emissions Transmitted from Earthquake Regions) satellite data have been analysed for a period of three and half months from 01 September to 16 December 2010 in search of whistlers and VLF emissions and their ground observations at low latitudes. The quick look data show intense sporadic bursts mostly in the Instrument Champ Electrique (ICE) channel of the satellite. These bursts are analysed using MATLAB software for the nighttime passes of upgoing orbits in the latitude range 20°-50°. The analysis shows records of large number of first component of magnetospherically reflected (MR) whistlers, mostly when the satellite is in low latitude ionosphere. These whistlers, together with normal whistlers observed in the satellite, are not observed on the ground as revealed by simultaneous ground observations at low latitude station Agra. This confirms them to be non-ducted whistlers which are reflected and observed in the ionosphere and magnetosphere. These MR whistlers are suggested to be the major source of slot formation between the two radiation belts

Ionospheric effect of earthquakes as determined from ground based TEC measurement and satellite data

63-70Total electron content (TEC) measurements have been carried out at Agra (geographic lattitude 27°N, longitude 78°E), India using a dual frequency GPS receiver since 24 June 2006. Similarly, DEMETER satellite data of electron density and VLF/ULF electromagnetic emission data are available since its launch on 29 June 2004. The effect of earthquake on GPS-TEC and electron density (Ne) data, obtained from DEMETER satellite, has been investigated in the present paper. GPS-TEC and Ne data for seven months, during 01 December 2006-30 June 2007, has been investigated. Two large magnitude earthquakes occurred during this period: one on 08 January 2007 (M=6.0, depth=16 km) and other on 05 May 2007 (M=6.2, depth=09 km) at a distance of 1587 and 887 km, respectively from the observation station at Agra. The results show anomalous enhancements in TEC and Ne 1-4 days before and 1-2 days after the occurrence of these earthquakes. The calculated percentage deviations of TEC and Ne from their monthly mean values are found to vary between 40 and 80% during anomalous enhancements. The observed effect is interpreted in terms of generation of electric fields between the ionosphere and quasi-neutral ion clusters which are formed at troposphere heights by radon gas emanation from seismic region and followed by triggering of these clusters by green house gases. The electric fields so generated penetrate the ionosphere and bring out structural and dynamical changes in ionospheric parameters

Piezocatalytic activity of CaO–Bi2O3–B2O3 glass-ceramics under ultrasonic vibrations

Transparent glass-ceramics of CaO–Bi2O3–B2O3 (CBBO) were fabricated using the conventional melt quench technique. X-ray diffraction and Raman spectroscopy were employed to confirm the phase of the prepared samples. Differential scanning calorimetry (DSC) was used to verify that the material was, indeed, glassy. The CBBO glass samples were subjected to heat treatment at 540 °C for 30 min and 1 h based on their crystallization temperature obtained from DSC analysis. This study focused on the piezocatalytic behavior of CBBO glass-ceramic samples. Piezocatalysis experiments were conducted on the fabricated glass-ceramic samples, and it was discovered that the samples heat-treated for 30 min (HT30m) at 540 °C showed maximum dye degradation of 61% under 240 min of ultrasonication. Experiments were repeated multiple times to confirm their reliability. Additionally, a phytotoxicity assessment was performed on the degraded dye using vigna radiata seeds. The antibacterial properties of the CBBO glass-ceramic samples were also investigated via piezocatalysis. It was discovered that the HT30m CBBO glass-ceramic sample removes 98% of Escherichia coli and 99% of Staphylococcus aureus bacteria within 120 min of ultrasonication

Incidence of electrocardiographic changes indicating myocardial ischemia during cesarean sections under spinal anesthesia

Objective: Electrocardiographic (ECG) changes and chest symptoms suggestive of myocardial ischemia have been reported in healthy women during cesarean section under regional anesthesia. This study aimed to determine the incidence of ECG changes and find any relation between the changes and subjective chest symptoms, hemodynamic variables, oxytocin, and ephedrine administration. Materials and Methods: ECG changes were recorded in 237 term parturients during elective cesarean section done under spinal anesthesia. ST-T depression of ≥1 mm and elevation of ≥2 mm for at least 1-min were considered as significant. Timing of hypotension, bradycardia, tachycardia, ECG changes, and chest symptoms were recorded. Pearson correlation coefficient was used to determine the association between ST changes and subjective chest symptoms, hemodynamic variables, oxytocin, or ephedrine administration. Results: Of 237 patients, 71 (30%) had significant ST-T depression, and 83 (35%) complained of chest symptoms (pressure, squeezing, pain, or dyspnea). Of 71, 42 had chest symptoms. Chest symptoms were also experienced by 30 (18%) patients where no change in ECG was seen (166/237). The changes were more commonly noted at delivery or 3-10 min after oxytocin administration. No correlation was found between ECG changes and chest symptoms, hemodynamic variables, and ephedrine, but there was moderate positive relation with oxytocin. Conclusion: Chest symptoms and ECG changes consistent with myocardial ischemia were observed in about 1/3 healthy parturients during cesarean section. An association between oxytocin and ECG changes was found in half of the patients. The symptoms were short lived and required no treatment