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Background Acquired subglottic stenosis (SGS) most commonly results from prolonged endotracheal intubation and is a diagnostic challenge in the intubated child. At present, no imaging modality allows for in vivo characterization of subglottic microanatomy to identify early signs of acquired SGS while the child remains intubated. Fourier domain optical coherence tomography (FD-OCT) is a minimally invasive, light-based imaging modality which provides high resolution, three dimensional (3D) cross-sectional images of biological tissue. We used long-range FD-OCT to image the subglottis in intubated pediatric patients undergoing minor head and neck surgical procedures in the operating room. Methods A long-range FD-OCT system and rotary optical probes (1.2 mm and 0.7 mm outer diameters) were constructed. Forty-six pediatric patients (ages 2–16 years) undergoing minor upper airway surgery (e.g., tonsillectomy and adenoidectomy) were selected for intraoperative, trans-endotracheal tube FD-OCT of the subglottis. Images were analyzed for anatomical landmarks and subepithelial histology. Volumetric image sets were rendered into virtual 3D airway models in Mimics software. Results FD-OCT was performed on 46 patients (ages 2–16 years) with no complications. Gross airway contour was visible on all 46 data sets. Twenty (43%) high-quality data sets clearly demonstrated airway anatomy (e.g., tracheal rings, cricoid and vocal folds) and layered microanatomy of the mucosa (e.g., epithelium, basement membrane and lamina propria). The remaining 26 data sets were discarded due to artifact, high signal-to-noise ratio or missing data. 3D airway models were allowed for user-controlled manipulation and multiplanar airway slicing (e.g., sagittal, coronal) for visualization of OCT data at multiple anatomic levels simultaneously. Conclusions Long-range FD-OCT produces high-resolution, 3D volumetric images of the pediatric subglottis. This technology offers a safe and practical means for in vivo evaluation of lower airway microanatomy in intubated pediatric patients. Ultimately, FD-OCT may be applied to serial monitoring of the neonatal subglottis in long-term intubated infants at risk for acquired SGS. [ABSTRACT FROM AUTHOR]

Owing to high power conversion efficiency and low-cost, methyl-ammonium lead-based halide (viz. CH 3 NH 3 PbI 3) Perovskites have been emerging as the innovative candidate in the development of optoelectronic devices. However, the toxic lead in these materials is a major hurdle in its commercialization. Thus, there is an urgent need to replace lead with an appropriate element. Ethyl-ammonium based lead-free hybrid halide perovskites may be an alternative photovoltaic (PV) absorber material with appropriate band gap, high stability and non-toxic properties. Herein, we have investigated structural, electronic, optical, thermoelectric and thermodynamic properties of ethyl-ammonium germanium iodide (CH 3 CH 2 NH 3 GeI 3 or EAGeI 3) by full-potential augmented plane wave (FP-LAPW) method as implemented in the WIEN2k code within the density functional theory (DFT). In this paper, we have found that EAGeI 3 has direct band gap of 1.3 eV and high absorption coefficient greater than 104 cm−1 indicating its suitability as PV absorber material. We have also calculated thermoelectric coefficients as a function of carrier concentration, chemical potential and temperature. The thermodynamic calculations have been done within the quasi-harmonic approximation. As EAGeI 3 has been studied first time for PV applications, the present study may open a new vista for more exhaustive experimental and theoretical investigations in search of non-toxic and eco-friendly PV materials. • Physical properties of ethylammonium germanium iodide (CH 3 CH 2 NH 3 GeI 3). • EAGeI 3 is a direct band gap semiconductor. • Thermoelectric coefficients as a function of carrier concentration. • Thermodynamic properties have been done within the quasi-harmonic approximation. [ABSTRACT FROM AUTHOR]

Hybrid halide Perovskites have been emerging as the innovative candidate in the development of optoelectronic devices. Ethyl-ammonium based hybrid halide perovskites have been admirable compounds regarding low band gap, high stability and non-toxic properties instead of methyl-ammonium based hybrid halide perovskites. Herein, we have investigated structural, electronic, optical and thermoelectric (TE) properties of ethyl-ammonium tin iodide (CH 3 CH 2 NH 3 SnI 3) by full-potential linearized augmented plane wave plus local orbital (FP-LAPW + lo) method as implemented in the WIEN2k code within the density functional theory (DFT). The PBE-GGA, PBE- sol -GGA and TB- mBJ -GGA exchange-correlation potentials have been used to calculate the density of states and band structure of ethyl ammonium tin iodide (EASnI 3) and found that it is a direct band gap semiconductor. We have calculated optical parameters such as dielectric function, absorption coefficient, refractive index, extinction coefficient, Eloss, optical reflectivity and optical conductivity for photon energies in the range 0–25 eV. We have also calculated transport coefficients (Seebeck coefficient, the figure of merit, power factor, electrical conductivity, thermal conductivity) as a function of carrier concentration, chemical potential and temperature. Most of the investigated parameters are being reported for the first time. The present study establishes that ethyl-ammonium tin iodide (EASnI 3) offers high absorption coefficient, high Seebeck coefficient, etc. This makes it a prospective material for cost effective photovoltaic device applications to overcome environmental instabilities. • Physical properties of ethyl-ammonium tin iodide (CH 3 CH 2 NH 3 SnI 3). • EASnI 3 is a direct band gap semiconductor. • Thermoelectric coefficients as a function of carrier concentration. • Thermal properties have been done within the quasi-harmonic approximation. [ABSTRACT FROM AUTHOR]

Background/Objectives While upper airway obstruction is a common problem in the pediatric population, the first-line treatment, adenotonsillectomy, fails in up to 20% of patients. The decision to proceed to surgery is often made without quantitative anatomic guidance. We evaluated the use of a novel technique, long-range optical coherence tomography (LR-OCT), to image the upper airway of children under general anesthesia immediately before and after tonsillectomy and/or adenoidectomy. We investigated the feasibility of LR-OCT to identify both normal anatomy and sites of airway narrowing and to quantitatively compare airway lumen size in the oropharyngeal and nasopharyngeal regions pre- and post-operatively. Methods 46 children were imaged intraoperatively with a custom-designed LR-OCT system, both before and after adenotonsillectomy. These axial LR-OCT images were both rendered into 3D airway models for qualitative analysis and manually segmented for quantitative comparison of cross-sectional area. Results LR-OCT images demonstrated normal anatomic structures (base of tongue, epiglottis) as well as regions of airway narrowing. Volumetric rendering of pre- and post-operative images clearly showed regions of airway collapse and post-surgical improvement in airway patency. Quantitative analysis of cross-sectional images showed an average change of 70.52 mm 2 (standard deviation 47.87 mm 2 ) in the oropharynx after tonsillectomy and 105.58 mm 2 (standard deviation 60.62 mm 2 ) in the nasopharynx after adenoidectomy. Conclusions LR-OCT is an emerging technology that rapidly generates 3D images of the pediatric upper airway in a feasible manner. This is the first step toward development of an office-based system to image awake pediatric subjects and thus better identify loci of airway obstruction prior to surgery. [ABSTRACT FROM AUTHOR]