Wrapping of ellipsoidal nano-particles by fluid membranes

Membrane budding and wrapping of particles, such as viruses and nano-particles, play a key role in intracellular transport and have been studied for a variety of biological and soft matter systems. We study nano-particle wrapping by numerical minimization of bending, surface tension, and adhesion energies. We calculate deformation and adhesion energies as a function of membrane elastic parameters and adhesion strength to obtain wrapping diagrams. We predict unwrapped, partially-wrapped, and completely-wrapped states for prolate and oblate ellipsoids for various aspect ratios and particle sizes. In contrast to spherical particles, where partially-wrapped states exist only for finite surface tensions, partially-wrapped states for ellipsoids occur already for tensionless membranes. In addition, the partially-wrapped states are long-lived, because of an increased energy cost for wrapping of the highly-curved tips. Our results suggest a lower uptake rate of ellipsoidal particles by cells and thereby a higher virulence of tubular viruses compared with icosahedral viruses, as well as co-operative budding of ellipsoidal particles on membranes.Comment: 10 pages, 11 figure

Particles at Membranes and Interfaces

Soft surfaces experience morphological changes upon interaction with objects at various length scales. Two important classes of soft surfaces are membranes and interfaces. In presence of particles, through surface-mediated interactions soft surfaces exhibit diverse phenomena in nature. A fluid membrane which acts as a protective periphery enclosing cellular material can be described as a two dimensional mathematical surface characterized by `bending elasticity' and `membrane tension'. Similarly, interfaces at the boundary of two liquid phases or a liquid and a gas phase are characterized by their interface tension. Interestingly, a close interplay of the deformation energy of these soft surfaces and the geometry and form of the particles allows the particles to interact. Thus, the study of interactions of particles with membranes and interfaces forms the basis of this work. The mechanistic aspects of cellular entry via membrane wrapping for particles of various geometries are studied theoretically and numerically. Such systems are characterized by the membrane bending rigidity, the membrane tension, and the adhesion strength. The different wrapping states exhibited are ``non wrapped", ``partially wrapped" (with low and high wrapping fraction), and ``completely wrapped". There are two kinds of phase boundaries: a continuous binding transition and a discontinuous transition either between two partially-wrapped states or from a partially-wrapped to a completely wrapped state. The theoretical analysis predicts stable partially wrapped states for nonspherical particles. Nonspherical particles having flat sides can show preferential initial binding though the decisive factor for encapsulation is the ratio of the width to the length of the particles and the softness of its edges. Wrapping energy contributions of the erythrocyte membrane to the invasion energetics for a malarial merozoite that has an asymmetric ``egg-like'' shape is assessed. Furthermore cell adhesion to nanopatterned substrates is characterized to predict optimal shapes of 3D nanoelectrodes for efficient coupling to cells using deformation energy calculations. For a fluid interface dominated by an interfacial tension, self-assembly via capillary interactions for micron-sized nonspherical particles is reported. A nonspherical particle can induce interface distortion due to an undulating contact line creating excess interfacial area. Neighboring particles interact to minimize the excess area via long-range interface-mediated capillary forces. The particle-induced interface distortion due to single ellipsoidal or cuboidal particles are calculated. The near-field nature of the capillary interactions between a pair of particles in different relative orientations is characterized using power-law fits

Molecular markers assisted DNA polymorphism: Implications in mangrove research

Mangroves are defined as woody, evergreen group of plant community; grow on the swampy substrate at tropical and sub-tropical habitatsadjusted to high salinity, periodical tidal influence, strong winds, high temperatures, high precipitation and anaerobic soils. They possessunique morphological and physiological adaptive features to cope with these extreme conditions. Mangrove vegetation is the cradle of several marine fauna and provides first line of defense against devastating sea surges, typhoon, tsunami, etc. However, since industrial era, many of the mangrove members were affected by several environmental constrains and anthropogenic activities that raised the sea level, lowered sweet water influx from the adjacent rivers and encroachment for the new settlement formation, increasing salinity. Hence, mangrove restoration program is the front line topic of interest to the plant biologists across the tropical and subtropical world since it has a productive and protective role for the inhabitants. Sound knowledge of molecular characteristic of the individual taxa will be provide an advantage for this initiative.Recent advancement in molecular markers based on the PCR technique techniqueswill enhance the knowledge about genetic background of each individual taxon, ultimately leading to valid guided references towards the understanding the inherent nature of the plant itself and beneficial to proper restoration program

"The fruits of independence": Satyajit Ray, Indian nationhood and the spectre of empire

Challenging the longstanding consensus that Satyajit Ray's work is largely free of ideological concerns and notable only for its humanistic richness, this article shows with reference to representations of British colonialism and Indian nationhood that Ray's films and stories are marked deeply and consistently by a distinctively Bengali variety of liberalism. Drawn from an ongoing biographical project, it commences with an overview of the nationalist milieu in which Ray grew up and emphasizes the preoccupation with colonialism and nationalism that marked his earliest unfilmed scripts. It then shows with case studies of Kanchanjangha (1962), Charulata (1964), First Class Kamra (First-Class Compartment, 1981), Pratidwandi (The Adversary, 1970), Shatranj ke Khilari (The Chess Players, 1977), Agantuk (The Stranger, 1991) and Robertsoner Ruby (Robertson's Ruby, 1992) how Ray's mature work continued to combine a strongly anti-colonial viewpoint with a shifting perspective on Indian nationhood and an unequivocal commitment to cultural cosmopolitanism. Analysing how Ray articulated his ideological positions through the quintessentially liberal device of complexly staged debates that were apparently free, but in fact closed by the scenarist/director on ideologically specific notes, this article concludes that Ray's reputation as an all-forgiving, ‘everybody-has-his-reasons’ humanist is based on simplistic or even tendentious readings of his work

The emerging role of Artificial Intelligence in the fight against COVID-19

Copyright © 2020 European Association of Urology. Published by Elsevier B.V. All rights reserved.The coronavirus disease 2019 (COVID-19) pandemic has generated large volumes of clinical data that can be an invaluable resource towards answering a number of important questions for this and future pandemics. Artificial intelligence can have an important role in analysing such data to identify populations at higher risk of COVID-19–related urological pathologies and to suggest treatments that block viral entry into cells by interrupting the angiotensin-converting enzyme 2-transmembrane serine protease 2 (ACE2-TMPRSS2) pathway.Peer reviewe