5D non-symmetric gravity and geodesic confinement

This work focuses on an unexplored aspect of non-symmetric geometry where only the off-diagonal metric components along the extra dimension, in a 5-dimensional spacetime, are non-symmetric. We show that the energy densities of the stationary non-symmetric models are similar to that of brane models thereby mimicking the thick-brane scenario. We find that the massive test particles are confined near the location of the brane for both growing and decaying warp factors. This feature is unique to the non-symmetric nature of our model. We have also studied the dynamical models where standard 4D FLRW brane is embedded. Our analysis shows that the non-symmetric terms deconfine energy density at the early universe while automatically confine at late times.     

Optical behaviour of swift heavy ions irradiated poly(vinyl alcohol) films

Polyvinyl alcohol films were irradiated to 90 MeV O ⁶⁺ and 150 MeV Si ¹⁴⁺ ions at fluence ranging from 10¹⁰ to 10¹² ions/cm². The observed changes in optical energy gap of this polymer have been investigated and results are tried to be explained in terms of energy transferred by the incident ions. It has been noticed that the value of optical energy gap decreases with increasing energy loss during the ion–polymer interaction process.     

Comparison of the effect of anti-hyperlipidemic drugs from different groups on the phase profile of liposomal membrane–a fluorescence anisotropy study

The study compares the effect of incorporation of three different groups of anti-hyperlipidemic drugs, namely niacin, simvastatin, and fenofibrate on the phase profile of liposomal membranes of dipalmitoylphosphatidylcholine (DPPC). The fluorescence anisotropy studies, using 1,6-diphenyl-1,3,5-hexatriene as fluorescent probe, have shown that the lipophilic molecule fenofibrate changes phase behavior of DPPC liposomal membrane to a greater extent compared to the changes produced by amphiphilic simvastatin and hydrophilic niacin. This variation in effect can be attributed to the nature of the drug molecules and hence their location in different parts of the liposomal membrane. We have also calculated the changes in van’t Hoff enthalpy values in all these three cases and observed that these values decreased with increase in drug concentrations in the case of simvastatin but for fenofibrate and niacin the effect is completely the reverse. In order to get a better insight, the fraction of motionally restricted lipid molecules has been calculated.     

Role of non-lamellar-forming lipid in promotion of liposomal fusion

Membrane fusion is an important process in a wide range of cellular and sub-cellular activities. It is evident that during the intermediate stages of fusion some transitory non-bilayer configurations must appear within the lipid moiety. Using fluorescence techniques, we have studied here the process of aggregation and fusion of liposomes made of lipids, namely 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) and 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC). When mixed together, the complete fusion between these two liposomes took around 44 h as both DPPC and DMPC favour lamellar configuration. When the mixture was incubated at 42°C the fusion process was completed after 23 h. But, when 1,2-dipalmitoyl-sn-glycero-3-phosphoethanolamine (DPPE) was added in the liposomal matrix the time for fusion was reduced to 21 h for mixture without incubation and 17 h when the mixture was incubated. This indicates that DPPE having a tendency to assume non-lamellar conformation, promoted destabilisation of the lamellar conformation within the liposome which facilitated the fusion between two apposing bilayers.     

Synthesis,Structural Characterization,and Theoretical Studies of Silver(I) Complexes of Dihydrobis(2‐mercapto‐benzothiazolyl) Borate

The complexes [Ag{κ³‐S,S′,H‐H₂B(mbz)₂}(PR₃)]_x, ( 1 : x = 2, R = Ph; 2 : x = 1, R = Cy) (mbz = 2‐mercaptobenzothiazolyl) and amidine based dihydro(2‐mercaptobenzo‐thiazolyl) borates, [HN=C(Ph)–NH(R)–H₂B(mbz)] ( 3 : R = 2,6‐diisopropylphenyl and 4 : R = Ph) were synthesized and characterized by various spectroscopic methods and single‐crystal X‐ray crystallography. Complex [Ag{κ³‐S,S′,H‐H₂B(mbz)₂}(PPh₃)]₂ ( 1 ) has a dimeric structure in its crystalline state, in which central silver(I) atoms adopt a distorted trigonal bipyramid arrangement. In contrast, complex [Ag{κ³‐S,S′,H‐H₂B(mbz)₂}(PCy₃)] ( 2 ) has a monomeric structure in its crystalline state, in which the central silver(I) atoms adopt a distorted trigonal planar arrangement. Infrared spectroscopy was utilized as a tool for investigating the presence of M ··· H–B interactions. In addition, density functional theory (DFT) calculations were used to analyse the B–H ··· [M] bonding interaction in the metal borate complexes.     

Electrokinetics with blood

Microfluidics based lab‐on‐a‐chip technology holds tremendous promises towards point‐of‐care diagnosis of diseases as well as for developing engineered devices aimed towards replicating the intrinsic functionalities of human bodies as mediated by blood vessel mimicking circulatory networks. While the analysis of transport of blood including its unique cellular constituents has remained to be the focus of many reported studies, a progressive interest on understanding the interplay between electric field and blood flow dynamics has paved a new way towards further developments from scientific engineering as well as clinical viewpoint. Here, we briefly outline the interconnection between electrokinetics and blood flow through micro‐capillaries, in an effort to address several challenging propositions in a wide variety of applications encompassing biophysical transport to medical diagnostics. We first present the fundamentals of interaction of electric field with cellular components. In conjunction with the unique rheological features of blood, we show that this interaction may turn out to be compelling for the use of electric fields for transporting blood samples through microfluidic conduits. We discuss the perspectives of both direct current and alternating current electrokinetics in the context of blood flow. In addition, we provide a brief outline of the concerned theoretical developments. We also bring out the relevant biophysical perspectives and focus on applications such as blood plasma separation and separation of circulatory tumor cells. Finally, we attempt to provide a futuristic outlook and envisage the potential of combining electrokinetics with blood microcirculation towards developing futuristic biomimetic microdevices that can replicate a novel control mechanism over micro‐circulatory transport in the entire connective network of human bodies. This may effectively pave the way towards the realization of a next‐generation medical simulation device, significantly advanced from what is available under the ambit of the state of art technology in the field.     

Order parameter description of electrochemical-hydrodynamic interactions in nanochannels

A novel phase-field model is developed for the quantitative modeling of the complex electrochemical-hydrodynamic interactions in narrow fluidic confinements. Through an order parameter variation, this model captures the underlying excluded volume effects, solvation interactions, and preferential polarizabilities in a self-consistent fashion, without resorting to computationally prohibitive molecular dynamics simulations. Agreement with molecular dynamics predictions is found to be quantitative.     

Ga2O3 and GaN nanocrystalline film: reverse micelle assisted solvothermal synthesis and characterization

Gallium oxide (beta-Ga2O3) nanoparticles were successfully deposited on quartz glass substrates using sodium bis(2-ethylhexyl) sulfosuccinate (AOT)/n-hexane/ethylene glycol monomethyl ether (EGME) reverse micelle-mediated solvothermal process with different omega values. The mean diameter of Ga2O3 particles was approximately 2-3 nm and found to be approximately independent of omega values of the reverse micelles. However, when the Ga2O3 nanocrystalline films were nitrided at 900 degrees C under flowing NH3 atmosphere for 1 h, the mean diameter of the resulted gallium nitride (wurtzite-GaN) nanoparticles varied from 3-9 nm. Both nanocrystalline films of Ga2O3 and GaN were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), Fourier transform infrared (FTIR) spectroscopy, UV-vis spectroscopy and photoluminescence in order to study their chemical and physical properties explicitly.     

Molecular aspects on the interaction of phenosafranine to deoxyribonucleic acid: Model for intercalative drug-DNA binding

The mode, mechanism and energetics of interaction of phenosafranine, the planar, cationic and rigid phenazium dye to calf thymus DNA was investigated from absorption, fluorescence, circular dichroism, isothermal titration calorimetry, thermal melting, and viscosity. The study revealed non-cooperative binding of the dye to DNA with an affinity in the range (3.81-4.22) × 10⁵ M⁻¹ as observed from diverse techniques and obeying neighbor exclusion principle. The stoichiometry of binding was characterized to be one phenosafranine molecule per two base pairs. The binding was characterized by strong stabilization of DNA against thermal strand separation, large intrinsic circular dichroic changes of DNA by itself and the generation of induced circular dichroism for the optically inactive phenosafranine molecules. Hydrodynamic and fluorescence quenching studies revealed strong evidence that the phenosafranine molecules are intercalated between every alternate base pairs of calf thymus DNA. Isothermal titration calorimetry studies suggested that the binding was exothermic and favoured by both negative enthalpy and positive entropy changes. This study for the first time presents the complete molecular aspects and energetics of phenosafranine complexation to DNA as model for intercalative drug-DNA interaction.     

A General Strategy Toward pH-Resistant Phenolic Fluorophores for High-Fidelity Sensing and Bioimaging Applications

Aryl alcohol-type or phenolic fluorophores offer diverse opportunities for developing bioimaging agents and fluorescence probes. Due to the inherently acidic hydroxyl functionality, phenolic fluorophores provide pH-dependent emission signals. Therefore, except for developing pH probes, the pH-dependent nature of phenolic fluorophores should be considered in bioimaging applications but has been neglected. Here we show that a simple structural remedy converts conventional phenolic fluorophores into pH-resistant derivatives, which also offer “medium-resistant” emission properties. The structural modification involves a single-step introduction of a hydrogen-bonding acceptor such as morpholine nearby the phenolic hydroxyl group, which also leads to emission bathochromic shift, increased Stokes shift, enhanced photo-stability and stronger emission for several dyes. The strategy greatly expands the current fluorophores’ repertoire for reliable bioimaging applications, as demonstrated here with ratiometric imaging of cells and tissues.