Fabrication and characterization of porous tissue-mimicking optical phantoms as a tool for optical sensor validation.

This paper presents porous polydimethylsiloxane (PDMS) optical phantoms with tunable microstructural and optical properties to mimic porous biological tissues (e.g., fruit) during the design and optimization of novel optical setups. A well connected salt network formed using salt particles of various size distributions was used to obtain porous PDMS phantoms of different porous features including porosity, pore size distribution, pore number density and pore connectivity. These microstructural features are strongly related to the light scattering from the phantom where a higher reduced scattering coefficient ( µ s ' ) was observed from the porous PDMS phantom with a higher number of small pores compared to the optical phantom with a lower number of larger pores. The prepared phantoms were used to validate GASMAS (gas in scattering media absorption spectroscopy) H2 O and O2 sensors by quantifying the optical path length through the pores and the O2 concentration inside the pores.

Successful Management of a Life-threatening Endotracheal Bleed with Angiographic Stenting.

Several operative and postoperative complications have been reported after tracheostomy, including fatal hemorrhage from erosion of a major vessel. We present here a case of hemorrhage after a surgical tracheostomy. This case is being reported on account of the unusual etiology of the hemorrhage and associated high fatality rates. All concerned need to be aware of this complication and its emergency management. How to cite this article: Joseph MM, Benjamin R, Padmanabhan A, Bal D, Nair S. Successful Management of a Life-threatening Endotracheal Bleed with Angiographic Stenting. Indian J Crit Care Med 2020;24(3):210-211.

Trace metal distribution in the sediment cores of mangrove ecosystems along northern Kerala coast, south-west coast of India.

Core sediment samples were collected from five mangrove ecosystems along northern Kerala coast (Kunjimangalam: S1, Pazhayangadi: S2, Pappinissery: S3, Thalassery: S4, and Kadalundi: S5) to assess the status of heavy metal pollution. S1 recorded comparatively lower metal concentration at surface (except Pb) due to low organic content and sandy texture, while the reverse was true for S3. Higher metal contents were recorded at S5 (0-5 cm), which was attributed to its unique biogeochemical behavior. Enrichment factor and geoaccumulation index indicated moderate enrichment for Cd, and the pollution load index revealed progressive deterioration of sediment quality at S5 (0-5 cm). There was no harmful effect of trace metals on biological community (except Ni) according to Sediment Quality Guidelines. Major processes controlling trace metal accumulation in these systems are diagenetic processes, precipitation of heavy metals as sulfides, and the presence of Fe, Mn-oxy hydroxides, which act as adsorption sites for other metals.

Fractionation and bioavailability of phosphorus in a tropical estuary, Southwest India.

Phosphorus fractionation was employed to find the bioavailability of phosphorus and its seasonal variations in the Panangad region of Cochin estuary, the largest estuarine system in the southwest coast of India. Sequential extraction of the surficial sediments using chelating agents was taken as a tool for this. Phosphate in the water column showed seasonal variations, with high values during the monsoon months, suggesting external runoff. Sediment texture was found to be the main factor influencing the spatial distribution of the geochemical parameters in the study region. Similarly, total phosphorus also showed granulometric dependence and it ranged between 319.54 and 2,938.83 µg/g. Calcium-bound fraction was the main phosphorus pool in the estuary. Significant spatial variations were observed for all bioavailable fractions; iron-bound inorganic phosphorus (5.04-474.24 µg/g), calcium-bound inorganic phosphorus (11.16-826.09 µg/g), and acid-soluble organic phosphorus (22.22-365.86 µg/g). Among the non-bioavailable phosphorus, alkali-soluble organic fraction was the major one (51.92-1,002.45 µg/g). Residual organic phosphorus was comparatively smaller fraction (3.25-14.64% of total). The sandy and muddy stations showed distinct fractional composition and the speciation study could endorse the overall geochemical character. There could be buffering of phosphorus, suggested by the increase in the percentage of bioavailable fractions during the lean pre-monsoon period, counteracting the decreases in the external loads. Principal component analysis was employed to find the possible processes influencing the speciation of phosphorus in the study region.