Impairing effect of fibrinogen on the mono-/bi-layer form of bovine lung surfactant

Lung surfactant (LS), a lipid–protein mixture responsible for alveolar stability, is inhibited by serum proteins leaked into the lungs in disease. Interaction of bovine lipid extract surfactant (BLES), a clinical replacement lung surfactant, with serum protein fibrinogen (Fbg) was studied employing various structural and biophysical techniques in adsorbed films and bulk bilayer dispersions. Surface tension area isotherms of the adsorbed films revealed the suppression of interfacial activity of BLES by Fbg (adsorption and surface tension reduction). Fbg, predominantly associated with the fluid phase of BLES films, resulted in the aggregation of the gel lipid domains as evidenced by atomic force microscopy. BLES bilayer dispersion showed phase transition from a diffused gel to liquid–crystalline phase in the temperature range 10–35 °C as studied by differential scanning calorimetry (DSC). Fbg resulted in the shift of peak to a higher transition temperature for the maximal heat flow (T _max) of BLES dispersions. Combined Raman and FTIR spectral studies of the BLES/Fbg dispersions revealed that Fbg altered the –CH₂–, –CH₃, and –PO₄ ^? vibrational modes of the phospholipids present in BLES, suggesting the condensing and dehydrating effect of the protein on surfactant. Studies suggest that Fbg, by directly interacting with the gel lipids in LS in bulk dispersions, alter the packing of the films formed at the interface, and can be used as a specific model for lung disease.     

Proline‐Tetrazole‐Catalyzed Enantioselective N‐Nitroso Aldol Reaction of Aldehydes with In Situ Generated Nitrosocarbonyl Compounds

A highly enantioselective method (up to 98 % ee) for the preparation of β‐amino alcohols was achieved by using the readily available proline‐tetrazole as the catalyst for the N‐nitroso aldol reaction of aldehydes with in situ generated nitrosocarbonyl compounds. The key to success of this reaction is the use of MnO₂ as an oxidant and catechol as a Brønsted acid additive.     

Epoxy-based oligomer containing dithia-aza-based naphthylazobenzene pendant: a chemosensor for Hg2+ and Cu2+ ions

A simple epoxy-based oligomer 1 containing naphthylazobenzene-appended dithia-aza moieties was prepared. In UV–vis measurements, the proposed oligomer showed the ion-sensing ability to Hg²⁺ and Cu²⁺ ions. The discrimination between two differently responding Hg²⁺ and Cu²⁺ ions was also realised from ‘ON–OFF’ type fluorescence responses of 1.     

A Water-Stable Ionic MOF for the Selective Capture of Toxic Oxoanions of SeVI and AsV and Crystallographic Insight into the Ion-Exchange Mechanism

Selectively capturing toxic oxoanions of selenium and arsenic is highly desired for the remediation of hazardous waste. Ionic metal–organic frameworks (iMOFs) especially cationic MOFs (iMOF-C) as ion-exchange materials, featuring aqueous phase stability, present a robust pathway for sequestration of the oxoanions owing to their ability to prevent leaching because of their ionic nature. On account of scarcity of water-stable cationic MOFs, the capture of oxoanions of selenium and arsenic has been a major challenge and has not been investigated using iMOFs. Herein, we demonstrate large scale synthesis of cationic MOF, viz. iMOF-1C that exhibits selective capture of oxoanions of Se^VI (SeO₄²⁻) and As^V (HAsO₄²⁻) in water with a maximum sorption capacity of 100 and 85 mg g⁻¹, respectively. This represents among the highest uptake capacities observed for selenate oxoanion in MOFs. Further, the ion-exchange mechanism was directly unveiled by single crystal analysis, which revealed variable modes of host–guest binding.     

Breathing of voltage dependent anion channel as revealed by the fractal property of its gating

The gating of voltage dependent anion channel (VDAC) depends on the movement of voltage sensors in the transmembrane region, but the actual mechanism is still not well understood. With a view to understand the phenomenon we have analyzed the current recordings of VDAC in lipid bilayer membrane (BLM) and found that the data show self-similarity and fractal characteristics. We look for the microscopic and molecular basis of fractal behavior of gating of VDAC. A model describing the oscillatory dynamics of voltage sensors of VDAC in the transmembrane region under applied potential has been proposed which gives rise to the aforesaid fractal behavior.     

Large eddy simulation of turbulent flows via domain decomposition techniques. Part 1: theory

The present paper discusses large eddy simulations of incompressible turbulent flows in complex geometries. Attention is focused on the application of the Schur complement method for the solution of the elliptic equations arising from the fractional step procedure and/or the semi‐implicit discretization of the momentum equations in velocity–pressure representation. Fast direct and iterative Poisson solvers are compared and their global efficiency evaluated both in serial and parallel architecture environments for model problems of physical relevance. Copyright © 2005 John Wiley & Sons, Ltd.     

Dielectric properties of water/lecithin/cyclohexane gels

Dielectric relaxation measurements in the frequency range 0.1–15 GHz have been carried out on water/lecithin/cyclohexane gels using a time domain reflectometry method (TDR). Dielectric dispersions describable in terms of a power law typical of percolated systems, but with exponents significantly different from those characterizing statically or dynamically percolated systems are observed. The dielectric dispersions, attributed to water and/or lecithin head group rotational motions, indicate that these motions are characterized by a wide spectrum of relaxation times.     

Semi-empirical MNDO study of the structure of some diorganotin (IV) glycylglycinates

The geometrical structures of some diorganotin glycylglycinates have been obtained using the MNDO semi-empirical method. A good agreement with the experimental diffractometric data was found.