Preparation and characterization of pristine and Sn doped copper gallium sulphide (CGS) thin films using spray pyrolysis technique

With thin film solar cell applications, chalcopyrite semiconductors present enormous potential for usage as an absorber layer. In today's electronics sector, wide band gap semiconductors have extreme demand for applications such as high-power, high-frequency, challenging devices that are resistant to high temperatures, optoelectronic devices, and short-wavelength light-emitting devices. The undoped and tin-doped CGS thin films are the subject of the current investigation. Pure and Tin (Sn) doped CGS thin films were produced on a glass substrate using a low-cost chemical spray pyrolysis technique in a nitrogen atmosphere. Spray pyrolysis is a flexible and efficient method for thin-film deposition. The process parameters, such as the nozzle distance, spray time, spray rate, and temperature, have a significant impact on the films' quality and characteristics. Fundamental characterization techniques, including XRD analysis, Micro Raman analysis, EDAX, UV-VIS-NIR spectroscopy, and Scanning Electron Microscopy (SEM), were used to examine the generated pristine and Sn-doped CGS thin films. The XRD patterns showed that the pristine and Sn-doped CGS thin films exhibit a tetragonal phase and there is a decrease in the crystallite size with increasing dopant concentration. SEM studies revealed that there is a change in the grain size and surface morphology of the film with increasing Sn doping concentration. The presence of copper (Cu), gallium (Ga), sulfur (S), and Sn was further confirmed by studying the EDAX spectrum. SEM results indicate that the surface morphology of the CGS films is modified by Sn doping. Further increasing the dopant percentage caused deformation and fragmentation of the sample. A comparison of the Raman spectra for pristine and Sn-doped CGS revealed that there is some substantial change in the layer composition after adding the dopant. Compared to the pristine CGS, the peak positions of CGS (1 wt %) and CGS (3 wt %) are not shifted but there is a significant change in the relative peak intensities and formation of an additional peak The Sn-doped CuGaS2 thin films had optical band gaps of 2.47 eV (0.0 wt% Sn-doped), 2.33 eV (1 wt% Sn-doped), and 2.58 eV (3 wt% Sn-doped). From this study, we can say that the 1 wt% Sn doped CGS sample is the best for solar cell application. The XRD results indicated that the Sn dopant addition in the CuGaS2 lattice site does not affect the symmetry of the material. Enhancement of absorption is done by the Sn dopant.

Validation of transcutaneous bilirubinometry during phototherapy for detection and monitoring of neonatal jaundice in a low-income setting

Background: Severe neonatal jaundice (SNJ) and the associated long-term health sequelae are a significant problem in low-income countries (LIC) where measurement of total serum bilirubin (TSB) is often unavailable. Transcutaneous bilirubinometry (TcB) provides the opportunity for non-invasive, point-of-care monitoring. Few studies have evaluated its agreement with TSB levels during phototherapy in LIC.Aim: To determine agreement between TcB and TSB during phototherapy in a Haitian newborn population and to establish whether TcB can be safely used to guide treatment during phototherapy when TSB is unavailable.Methods: A single-centre prospective study (February to May 2017) in Cap Haïtien, northern Haiti was undertaken. Newborns <7 days of age with clinically detected jaundice were eligible for inclusion. A TcB device (JM-103) was used to screen for newborn jaundice along with a parallel TSB. A strip of black tape was placed across the sternum during phototherapy and uncovered for subsequent TcB measurements. Decisions about phototherapy treatment were based upon UK National Institute of Clinical Excellence (NICE) threshold criteria. Paired TSB and TcB measurements were compared using Bland-Altman methods.Results: The final analysis included 70 parallel TSB/TcB measurements from 35 infants within the first 5 days of life. Nineteen (54.3%) were male and 12 (34.3%) were <35 weeks. Thirty-two (91.4%) were receiving phototherapy. There was good agreement between TSB and TcB. Compared with TSB, TcB tended to over-estimate bilirubin (mean difference 11.1 µmol/L, 95% CI -10.2-32.5 µmol/L). However, at higher bilirubin levels (>250 µmol/L), TcB tended to under-estimate bilirubin compared with TSB and the difference increased.Conclusion: In an LIC setting in which serum bilirubin testing is not commonly available, TcB demonstrates good agreement with TSB and can be safely used to guide jaundice treatment during phototherapy but can lead to over-treatment at lower bilirubin levels and are more inaccurate at higher levels. For TcB levels >250 µmol, confirmation with serum bilirubin should be performed, if available, to avoid under-estimation.Abbreviations: LIC: low income countries; LMIC: low and middle income countries; TcB: transcutaneous bilirubinometry; TSB: transcutaneous serum biliubin.

Single walled carbon nanotube-metal oxide nanocomposites for reversible and reproducible storage of hydrogen

Composite material consisting of single walled carbon nanotubes (SWCNTs) and metal oxide nanoparticles has been prepared and their hydrogen storage performance is evaluated. Metal oxides such as tin oxide (SnO2), tungsten trioxide (WO3), and titanium dioxide (TiO2) are chosen as the composite constituents. The composites have been prepared by means of ultrasonication. Then, the composite samples are deposited on alumina substrates and at 100 °C in a Sieverts-like hydrogenation setup. Characterization techniques such as transmission electron microscopy (TEM), Raman spectroscopy, scanning electron microscopy (SEM), powder X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, energy dispersive spectroscopy (EDS), CHN elemental analysis, and thermogravimetric (TG) measurements are used to analyze the samples at various stages of experiments. Hydrogen storage capacity of the composites namely, SWCNT-SnO2, SWCNT-WO3, and SWCNT-TiO2 are found to be 1.1, 0.9, and 1.3 wt %, respectively. Hydrogenated composite samples are stable at room temperature and desorption of hydrogen is found to be 100% reversible. Desorption temperature ranges and binding energy ranges of hydrogen have been measured from the desorption studies. The hydrogenation, dehydrogenation temperature, and binding energy of hydrogen fall in the recommended range of a suitable hydrogen storage medium applicable for fuel cell applications. Reproducibility and deterioration level of the composite samples have also been examined.

Novel surgical technique for insertion of pleuroperitoneal shunts for bilateral chylous effusions in Ex preterm infant at term corrected age

Neonatal chylothorax is a relatively uncommon condition. Here we describe the case of an extremely preterm infant with bilateral chylous effusions which were resistant to conventional medical management and were ultimately managed with the insertion of pleuroperitoneal shunts using a novel surgical technique. Subsequently the infant recovered and the shunts could be removed. We report this case to highlight that such shunts can be inserted even in tiny preterm infants with minimally invasive techniques, and be extremely successful in managing chylothorax, pending spontaneous recovery.

Using the Lomb periodogram for non-contact estimation of respiration rates

We describe a contact-less method for measurement of respiration rate during sleep using a 5.8GHz radio-frequency bio-motion sensor. The sensor operates by sensing phase shifts in reflected radio waves from the torso caused by respiratory movements and other bodily movements such as twitches, positional changes etc. These non-respiratory motion artefacts can obscure reliable estimation of breathinig rates if conventional spectral analysis is used. This paper reports on the accuracy of the respiration rate estimates obtained via algorithmic approaches using Lomb-periodogram based analysis (which can deal with missing or corrupted data), as compared to conventional spectral analysis. Gold-standard respiration rates are derived by expert scoring of respiration rates measured through polysomnography (PSG) from sensors (Respiratory Inductance Plethysmography (RIP) belts) in contact with the subject in an accredited sleep laboratory. Specifically, respiration rates for 15-minute segments chosen from 10 subjects free of Sleep-Disorded Breathing (AHI〈5) were selected for analysis in this paper. Comparison to the expert annotation indicates strong agreement, with the Lomb-periodogram respiration rates with the average error between the measurements being less than 0.4 breaths/min and a standard deviation of 0.3 breaths/minute. Moreover, we showed that the proposed algorithm could track respiration rate over the complete night's recordings for those 10 subjects. We conclude that the non-contact biomotion sensor may provide a promising approach to continuous respiration rate monitoring of reasonable accuracy.

Detection of cardiac activity using a 5.8 GHz radio frequency sensor

A 5.8-GHz ISM-Band radio-frequency sensor has been developed for non-contact measurement of respiration and heart rate from stationary and semi-stationary subjects at a distance of 0.5 to 1.5 meters. We report on the accuracy of the heart rate measurements obtained using two algorithmic approaches, as compared to a reference heart rate obtained using a pulse oximeter. Simultaneous Photoplethysmograph (PPG) and non-contact sensor recordings were recorded over fifteen minute periods for ten healthy subjects (8M/2F, ages 29.6 + or - 5.6 yrs) One algorithm is based on automated detection of individual peaks associated with each cardiac cycle; a second algorithm extracts a heart rate over a 60-second period using spectral analysis. Peaks were also extracted manually for comparison with the automated method. The peak-detection methods were less accurate than the spectral methods, but suggest the possibility of acquiring beat by beat data; the spectral algorithms measured heart rate to within + or -10% for the ten subjects chosen. Non-contact measurement of heart rate will be useful in chronic disease monitoring for conditions such as heart failure and cardiovascular disease.

Neonatal intrahepatocellular lipid

There is increasing evidence that preterm birth is a risk factor for the development of adiposity associated disease, although the pathophysiological basis is unclear. We have previously shown that preterm infants have increased internal abdominal (visceral) adiposity by term. In adults increased internal adiposity is associated with elevated intrahepatocellular lipid (IHCL). We measured IHCL using (1)H NMR spectroscopy in 26 infants (eight healthy preterm-at-term and 18 term-born) and compared values with a reference group of 32 adults. There was no significant difference between adult and term-born IHCL content. In preterm-at-term infants IHCL was significantly elevated when compared with term-born infants and with adults (IHCL CH2/water median (interquartile range): preterm 1.69 (1.04-3.53), term 0.21 (0-0.54) and adult 0.55 (0.08-1.57).