Self-organisation properties of homomeric dipeptides derived from valine

Three optically active liquid crystal (LC) homomeric dipeptides, in particular, a pair of enantiomers and a diastereomer formed by joining two half-disc-like entities through a dipeptide spacer comprising L-L, D-D and L-D valine residues, have been synthesised and characterised. Hydrogen-bond-directed self-assembly of these non-discoid supramolecules results in the formation columnar (Col) LC phase. They form a stable organo gel in polar organic solvents through intermolecular hydrogen bond, and their scanning electronic microscopy (SEM) images reveal the presence of entangled network. The interaction of these homomeric dipeptides with nanaoparticles (silica species) has also been investigated by SEM images and UV-visible experiments.     

Influence of contact resistance and natural convection effects on non-dimensional effective thermal conductivity estimation of two-phase materials

In this article, the development of geometry dependent resistance model by considering contact resistance and natural convection effects are used to estimate the effective thermal conductivity of two-phase materials based on the unit cell approach. The algebraic equations have been derived based on isotherm approach for 2-D and 3-D spatially periodic medium. Comparison study has been made between developed models and experimental data. The result agrees well with experimental values.     

PEGylation of superparamagnetic iron oxide nanoparticle for drug delivery applications with decreased toxicity: an in vivo study

Journal of Nanoparticle Research - Superparamagnetic iron oxide nanoparticles (SPIONs) are evolving as a mainstay across various applications in the field of Science and Technology. SPIONs have...     

Numerical study on turbulent natural convection and radiation heat transfer of nanofluids in a differentially heated square enclosure

Journal of Thermal Analysis and Calorimetry - Due to the low performance observed during natural convection with fluids such as air and water, nanofluid research was carried out to analyse them for...     

Reviewing the use of chitosan and polydopamine for electrochemical sensing

Biopolymers possess highly favorable properties for electrochemical biosensing such as their inherent biocompatibility, inexpensive nature, and strong interfacial adhesion. In this mini-review, we will focus on chitosan and polydopamine, two of the most commonly used biopolymers, for electrochemical sensing applications. Chitosan is a polysaccharide that exhibits high chemical resistance, offers straightforward modification and cross-linking, and possesses antibacterial properties and mucoadhesion. Polydopamine has the benefit of universal adhesion, in addition to the ability to form self-assembled structures. We will demonstrate how the unique structural and electrochemical features of these biopolymers can be used in a range of electrochemical biosensing platforms.     

A study on the inclusion complexation of 3,4,5-trihydroxybenzoic acid with β-cyclodextrin at different pH

Effect of β-cyclodextrin (β-CD) on the absorption and fluorescence spectra of 3,4,5-trihydroxybenzoic acid (THB) have been studied buffer solutions of different pHs (pH ~1, pH ~7 and pH ~10). The study reveals that in all the above pHs THB forms 1:1 inclusion complex. The hydroxyl groups are present in the interior part of the β-CD cavity and carboxyl group is present in the hydrophilic part of the β-CD cavity. Dual luminescence is observed at pH ~1 and pH ~7 solutions which shows that intramolecular charge transfer present at these pH. The broad spectral maximum at pH ~10 indicates that intramolecular proton transfer is present in THB.     

A study on oriented relative clique number

An oriented graph is a directed graph with no directed cycle of length one or two. The relative clique number of an oriented graph is the cardinality of a largest subset $X$ of vertices such that each pair of vertices is either adjacent or connected by a directed 2-path. It is known that the oriented relative clique number of a planar graph is at most 80. Here we improve the upper bound to 32. We also prove an upper bound of 14 for oriented relative clique number of triangle-free planar graphs. Furthermore, we determine the exact values of oriented relative clique number for the families of outerplanar graphs with girth at least $g$ and planar graphs with girth at least $g+2$ for all $g\ge 3$. Moreover, we study the relation of oriented relative clique number with oriented chromatic number, oriented absolute clique number and maximum degree of a graph. We also show that oriented relative clique number of a connected subcubic graph is at most seven which weakly supports a conjecture by Sopena (JGT 1997).     

Development and validation of a high‐performance liquid chromatography method for the simultaneous determination of aspirin and folic acid from nano‐particulate systems

Attention has shifted from the treatment of colorectal cancer (CRC) to chemoprevention using aspirin and folic acid as agents capable of preventing the onset of colon cancer. However, no sensitive analytical method exists to simultaneously quantify the two drugs when released from polymer‐based nanoparticles. Thus, a rapid, highly sensitive method of high‐performance liquid chromatography analysis to simultaneously detect low quantities of aspirin (hydrolyzed to salicylic acid, the active moiety) and folic acid released from biodegradable polylactide‐co‐glycolide (PLGA) copolymer nanoparticles was developed. Analysis was done on a reversed‐phase C₁₈ column using a photodiode array detector at wavelengths of 233 nm (salicylic acid) and 277 nm (folic acid). The mobile phase consisted of acetonitrile–0.1% trifluoroacetic acid mixture programmed for a 30 min gradient elution analysis. In the range of 0.1–100 μg/mL, the assay showed good linearity for salicylic acid (R² = 0.9996) and folic acid (R² = 0.9998). The method demonstrated good reproducibility, intra‐ and inter‐day precision and accuracy (99.67, 100.1%) and low values of detection (0.03, 0.01 μg/mL) and quantitation (0.1 and 0.05 μg/mL) for salicylic acid and folic acid, respectively. The suitability of the method was demonstrated by simultaneously determining salicylic acid and folic acid released from PLGA nanoparticles. Copyright © 2009 John Wiley & Sons, Ltd.