Induced Mesophases in Binary Systems of Non-Mesogens Where One of the Component is 1,2,4 Trisubstituted Benzene Derivatives

Abstract

Exhibition of mixed mesophases in binary systems where both the components are non-mesogens by themselves offer a very interesting study. In the present work four binary systems were studied where one of the components is non-mesogenic 1,2,4-trisubstituted benzene derivative while the other components are rod shaped non-mesogens. Induction of mesophases is observed in all the binary systems studied. Few compositions on cooling remain in liquid crystalline phase at the ambient temperatures for about 48 hours.     

New mesogens with a fluoro-substituted bent core

Ferroelectric properties in liquid crystals are no longer restricted to materials with a chiral molecular structure; ferroelectricity has been observed in a smectic phase formed by bent achiral molecules. Accordingly, two homologous series possessing a central biphenyl methane core have been synthesized, the central core having two lateral fluoro substituents. Both the series have six-ring structures and exhibit smectic mesophases of high thermal stability. The flexible biphenyl methane core imparts a slight curve to the molecules, giving them a bent shape.     

Mechanical desorption of immobilized proteins using carbon dioxide aerosols for reusable biosensors

Reusability of a biosensor has recently received considerable attention, and it is closely related with the effective desorption of probe molecules. We present a novel mechanical desorption technique to reuse biosensors by using periodic jets of carbon dioxide (CO₂) aerosols (a mixture of solid and gaseous CO₂), and demonstrate its feasibility by removing physically adsorbed and covalently bonded fluorescent proteins i.e., Escherichia coli fluorescein isothiocyanate antibody and bovine serum albumin (E. coli FITC–Ab and FITC–BSA) from silicon chips. The proteins on the chip surfaces were measured by fluorescent images before and after applying the aerosols. The removal efficiency of the aerosol treatment was measured for various concentrations (1–20 μg mL⁻¹) of E. coli FITC–Ab and FITC–BSA with two different removal cycles (5 and 11 cycles; each cycle: 8 s). We observed high removal efficiencies (>93.5% for physically adsorbed Ab and >84.6% for covalently bonded Ab) at 11 cycle aerosol treatment. This CO₂ aerosol treatment did not undermine re-functionalization, which was confirmed by the fluorescent images of FITC–Abs for fresh and reused chips. Desorption of the immobilized layers was validated by Fourier transform infrared and X-ray photoelectron spectroscopic analyses. We also conducted an experiment on the regeneration of E. coli sensing chips using this aerosol treatment, and the chips were re-used 5 times successfully. This mechanical desorption technique is a highly effective and novel strategy for reusable biosensors.     

Inter-molecular physiochemical characterization for etodolac-hydroxypropyl-β-cyclodextrin polymeric systems in solid and liquid state

The purpose of this study was to explore the utility of hydroxypropyl-β-cyclodextrin (HP-β-CD) systems in forming inclusion complexes with the anti-rheumatic or anti-arthritic drug, etodolac (EDC), in order to overcome the limitation of its poor aqueous solubility. This inclusion system achieved high solubility for the hydrophobic molecule. The physical and chemical properties of each inclusion compound were investigated. Complexes of EDC with HP-β-CD were obtained using the kneading and co-evaporation techniques. Solid state characterization of the products was carried out using Fourier transform infrared spectroscopy (FT-IR), differential scanning calorimetry (DSC), powder X-ray diffraction (XRD) and Scanning electron microscopy (SEM). Studies in the solution state were performed using UV-Vis spectrophotometry and ¹H-NMR spectroscopy. Phase solubility profiles with HP-β-CD employed was found to be A_L type. Stability constants (K_c) from the phase solubility diagrams were calculated indicating the formation of 1:1 inclusion complex. Stability studies in the solid state and in liquid state were performed; the possible degradation by RP-HPLC was monitored. The dissolution studies revealed that EDC dissolution rate was improved by the formation of inclusion complexes.      

Screening dependence of superconducting state parameters

Theoretical values of superconducting state parameters of a number of superconductors are presented here using linear potential with seven different forms of dielectric screening in order to exhibit the dielectric dependence of these parameters. Presently computed results on comparison with the available experimental data show that the R.P.A. screening provides the best explanation of the superconducting state in most of the metals. It has been observed that the use of a non-local pseudopotential is desirable in the case of complex metals like Al, Pb etc.     

Spectral shaping for non-Gaussian source spectra in optical coherence tomography

We present a digital spectral shaping technique to reduce the sidelobes (ringing) of the axial point-spread function in optical coherence tomography for non-Gaussian-shaped source spectra. The spectra of two superluminescent diodes were combined to generate a spectrum with significant modulation. Images of onion cells demonstrate the improved image quality in a turbid biological sample. A quantitative analysis of the accompanying penalty in signal-to-noise ratio is given.     

Eigenvalues of the adjacency matrix of tetrahedral graphs

A tetrahedral graph is defined to be a graphG, whose vertices are identified with the unordered triplets onn symbols, such that vertices are adjacent if and only if the corresponding triplets have two symbols in common. Ifn ₂ (x) denotes the number of verticesy, which are at distance 2 fromx andA(G) denotes the adjacency matrix ofG, thenG has the following properties: P₁) the number of vertices is . P₂)G is connected and regular. P₃)n ₂ (x) = 3/2(n–3)(n–4) for allx inG. P₄) the distinct eigenvalues ofA(G) are –3, 2n–9,n–7, 3(n–3). We show that, ifn > 16, then any graphG (with no loops and multiple edges) having the properties P₁)–P₄) must be a tetrahedral graph. An alternative characterization of tetrahedral graphs has been given by the authors in [1].This research was supported by the National Science Foundation Grant No. GP-5790, and the Army Research Office (Durham) Grant No. DA-ARO-D-31-12-G910. (Institute of Statistics Mimeo Series No. 571, March 1968.)     

Ascorbic acid as a mediator and template for assembling metallic nanoparticles

In this paper we report the results on the use of L-ascorbic acid (AA) in assembling metal nanoparticles (NPs) into three-dimensional fibrous structures. The degradation product of AA leads to the formation of fibrous structures, which has been used as a template for deposition of metal NPs such as Au, Pt, and Ag. We also report that AA can be used as the reducing agent in generating Au NPs. The spontaneous fiber formation and formation of Au NPs by AA have been coupled to generate fibers made up of composite of Au NPs and the polymer from the degradation products of AA. These fibers appear in the form of a fiber bundle with branched structures having overall dimensions on the order of several millimeters. They have typical widths of 1-4 microm with length of each segment of fiber bundle on the order of 40 microm. The composite fiber bundle has been found to be electrically conducting with surface resistivity on the order of 2.16x10(3) Omegacm. UV-vis spectroscopy, X-ray diffraction, transmission and scanning electron microscopic measurements were used to establish the formation of fibrous structures in the medium.     

On the steady laminar flow in a curved pipe of varying elliptic cross-section

The fully developed steady flow of a fluid through a curved tube with elliptic cross-section is studied, the cross-sectional area varying slowly with longitudinal distance. Using a perturbation scheme in terms of two small parameters (geometric parameter and curvature parameter), complete analytical solutions are obtained to the first order. The effects of constriction combined with constant curvature of the centre line are discussed. The phenomenon of secondary flow, shear stress and the increased impedance (due to the constriction) are calculated. The possibility of the application of the results to various engineering problems and physiological flows is indicated.     

Facile synthesis of (Z)- and (E)-3-allylidene-β-lactams via thermal β-elimination of trans-3-allyl-3-sulfinyl-β-lactams

A competent synthetic route for the synthesis of novel (Z)- and (E)-3-allylidene-β-lactams is described. The strategy involves oxidation of trans-3-allyl-3-phenylthio-β-lactams 1 using sodium metaperiodate (NaIO₄) to diastereomeric trans-3-allyl-3-phenylsulfinyl-β-lactams 2 and 3, which further undergo thermal β-elimination in refluxing carbon tetrachloride to furnish (Z)- and (E)-3-allylidene-β-lactams 5 and 6 in good to excellent yields. The molecular structure of 3b has been established with the help of single crystal X-ray analysis.