In recent years, two-dimensional (2D) Ruddlesden-Popper perovskites have emerged as promising candidates for environmentally stable solar cells, highly efficient light-emitting diodes, and resistive memory devices. The remarkable existence of self-assembled quantum well (QW) structures in solution-processed 2D perovskites offers a diverse range of optoelectronic properties, which remain largely unexplored. Here, we experimentally observe ultrafast relaxation of free carriers in 20 ps due to the quantum confinement of free carriers in a self-assembled QW structures that form excitons. Furthermore, hybridizing the 2D perovskites with metamaterials on a rigid and a flexible substrate enables modulation of terahertz fields at 50-GHz modulating speed, which is the fastest for a solution-processed semiconductor-based photonic device. Hence, an exciton-based ultrafast response of 2D perovskites opens up large avenues for a wide range of scalable dynamic photonic devices with potential applications in flexible photonics, ultrafast wavefront control, and short-range wireless terahertz communications.

The diversity of microbial species in a metagenomic study is commonly assessed using 16S rRNA gene sequencing. With the rapid developments in genome sequencing technologies, the focus has shifted towards the sequencing of hypervariable regions of 16S rRNA gene instead of full length gene sequencing. Therefore, 16S Classifier is developed using a machine learning method, Random Forest, for faster and accurate taxonomic classification of short hypervariable regions of 16S rRNA sequence. It displayed precision values of up to 0.91 on training datasets and the precision values of up to 0.98 on the test dataset. On real metagenomic datasets, it showed up to 99.7% accuracy at the phylum level and up to 99.0% accuracy at the genus level. 16S Classifier is available freely at http://metagenomics.iiserb.ac.in/16Sclassifier and http://metabiosys.iiserb.ac.in/16Sclassifier.

Focal choroidal excavation (FCE) is defined as an area of concavity in choroid detected on optical coherence tomography. These are mostly present in macular region without evidence of accompanying scleral ectasia or posterior staphyloma. Though initially considered to be congenital, increasing number of cases have been identified in association with other choroidal pathologies such as central serous choroidopathy, choroidal neovascularisation, polypoidal choroidal vasculopathy, choroiditis, choroidal tumours. In this review article, we aim to elaborate on the morphology, pathogenesis and differential diagnosis of FCE and specifically discuss the spectrum of diseases with known association along with the impact of their treatment on FCE

Initial presentation of microbial keratitis after DSAEK may involve either the host or the posterior lamellar disk alone. A microvitrectomy scissors through the side port may be used for biopsy of posterior lamellar disk in recalcitrant infection.