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Cor triatriatum dexter (CTD) is a rare congenital cardiac anomaly with a diverse presentation in every age group. We report a case of CTD in a 36-year-old female who presented with palpitations due to giant right atrium (RA), which we managed successfully with surgical excision of the membrane and RA reduction.

Bombyx mori silk fibroin (B. mori SF) is a prospective and promising biomaterial being investigated by the scientific research fraternity around the world for its biomedical applications such as tissue engineered grafts. This consideration of silk fibroin as biomaterial is possible given its suitable mechanical and biological properties. Mechanical properties and behavior of a biopolymer or biomaterial are greatly affected by the chemical environment surrounding it. To assess the suitability of B. mori SF for application as tissue scaffold and graft, it is vitally essential to understand the influence of saline environment (such as provided by extracellular fluids in the physiological conditions and during pre and post-treatments of the fiber or scaffold) on its mechanical behavior and molecular mechanics. Current study investigates the tensile mechanical behavior of B. mori SF under varying saline environments (0 to 4.5 M) using molecular dynamics (MD) simulations. Elastic modulus values of 7 to 20 GPa and peak stress values of 350 to 750 MPa are computed for the two models for 0 to 4.5 M saline environments. Examining the obtained results show that peptide salt interactions are primarily contributing to the enhanced mechanical response of B. mori SF nanostructure. In addition, formation of ionic bridges between the salt ions present in saline environment and peptide strands, facilitating the enhanced mechanical response, are also observed. Ultimately, it is envisioned that the molecular deformation mechanisms and mechanistic understanding extracted from current study can be informative towards future investigation of silk-based biomaterials.

Bombyx mori silk fibroin (B. mori SF) is emerging as a promising biomaterial for its application in biomedical field such as hard and soft tissue engineered grafts considering it is a load-bearing polymer with biocompatible and biodegradable characteristics. B. mori SF being a biopolymer is made up of amino acids (residues) comprising crystalline and amorphous domains at nanoscale. In general, mechanical behavior of a biomaterial is actively governed by its chemical environment. Extent of water present in silk can significantly affect its mechanical behavior and alter structural functions at the molecular level. Hence, it is essential to understand the mechanical behavior and molecular deformation mechanics of B. mori SF at the building block level under varying hydration conditions. In current investigation, tensile mechanical behavior of two characteristic computational models of B. mori SF, along the fiber axis, under varying hydration levels (0 to 70 wt%) has been studied using molecular dynamics simulations. Elastic modulus values in the range of 7 to 11 GPa and 8 to 13 GPa were obtained for the two models for varying hydration levels. Analyses reveal that the hydrophobic effect has a dominating role at lower hydration levels resulting in an enhanced interaction between protein chains. This results in mechanical strengthening of B. mori SF nanostructure. However, at higher hydration levels, the osmotic pressure plays a dominating role, resulting into screening of interatomic interaction between protein chains thus giving a weakening effect. Overall, this work contributes toward developing an understanding of mechanistic interactions between different protein phases (amorphous and crystalline regions) and water in hydrated B. mori SF nanostructure, which is useful for explorations in silk-based biomaterials.

Anomalous origin of the left coronary artery (LCA) from the right pulmonary artery (ALCARPA) is an extremely rare subset of an already rare entity, anomalous origin of the LCA from the pulmonary artery. Whenever it is diagnosed preoperatively, one should be extremely vigilant about the potential intramural course of the descending part of the LCA in the aorta. Preoperative imaging frequently fails to delineate this intramural course. We report our experience with one such case where we had accidentally injured the LCA during dissection from the right pulmonary artery. Although it was successfully managed, it reinforces our aforementioned point concerning the importance of vigilance in seeking to identify intramurality as a component of this anomaly of coronary artery origin.

Truncus arteriosus (TA) or common arterial trunk is a congenital cardiac anomaly having high association with arch anomalies such as right aortic arch or aortic arch interruption. However, TA with double aortic arch (DAA) is a rare occurrence. We report a case of TA with DAA where the diagnosis of DAA was missed initially.

Bombyx mori silk fibroin (B. mori SF) is a promising biopolymer for use in biomedical applications such as tissue engineered grafts and as a load bearing biopolymer with biocompatible and bioresorbable properties. B. mori SF is a hierarchical bio- macro-molecule made up of amino acid (residue) chains consisting of a crystalline phase and an amorphous phase arranged in a specific order. Understanding about the mechanical behavior of B. mori SF at multiple length scales is of importance when developing tissue grafts, which requires a deeper understanding of the mechanics of its nanostructure. Four phenomenological models of B. mori SF nanostructures were developed, based on crystalline and amorphous phase connectivity. Tensile loading based mechanical behavior analysis of these models were performed using molecular dynamics (MD) simulations and compared with existing results from literature for selection of best performing model. Elastic modulus of ~7.4GPa and tensile strength of ~340 MPa were obtained for this model. Analysis of results reveals that deformation mechanisms in B. mori SF at nanoscale are a combination of tensile and shear deformations, wherein, the tensile deformation of amorphous region results into excessive extension of B. mori SF, whereas, shear deformation of crystalline region results into a high tensile strength. Overall, this work is instrumental in development of a right computational nanoscale model of SF nanostructure and provides deeper insights into the mechanistic interactions and mechanisms between amorphous and crystalline regions of B. mori SF, which would be useful for further studies of silk based biomaterials.

In this chapter, we review the elastomeric composites with different types of one dimensional nanofillers e.g. nanotubes, nanorods and nanofibers. Various elastomers and nanofillers have been considered along with the preparation methods of the composites. The dispersion level and surface morphologies have been reported having various fillers and how do they vary with the chemical modifications on the filler along with the effect of dispersing agent. The improvement in thermal and mechanical properties including dynamic mechanical properties of elastomers has been discussed in presence of one-dimensional nanofillers. Viscoelasticity has been reviewed for elastomeric systems and, especially, how the non-linearity appears in presence of one-dimensional filler. Rheological properties including curing kinetics, storage and loss modulus, and complex viscosities as a function of frequency of the nanocomposites have been discussed in detail. Dynamic mechanical studies related to various elastomer nanocomposites with various one dimensional fillers have been reported with possible explanations. The influence of the nature of fillers with their chemical modifications of one-dimensional filler on the viscoelasticity has also been assessed.