Orientational order parameter studies in two symmetric dimeric liquid crystals – an optical study

The optical technique developed by [W. Kuczynski, B. Zywucki, and J. Malecki, Determination of orientational order parameter in various liquid-crystalline phases, Mol. Cryst. Liq. Cryst. 381 (2002), pp. 1–19; B.J. Zywucki and W. Kuczynski, IEEE transactions on optical phenomena – The orientational order in nematic liquid crystals from birefringence measurements, Dielectr. Electr. Insul. 8 (2001), pp. 512–515] is fabricated and used to determine the orientational order parameter in two dimeric liquid crystalline compounds nematic and SmA phases of α,ω-bis(4-alkylanilinebenzylidene-4′-oxy)alkane (m.OnO.m) homologous series. The compounds studied are 5.O8O.5 and 5.O10O.5 which exhibit nematic and SmA, and nematic phases, respectively. The orientational order parameter in both the phases of nematic and SmA phases of the compound one and the nematic phase of the compound two are obtained using the principle of Newton's rings which gives directly the birefringence, δn of the liquid crystal dimer. The merits of the technique used are presented over the conventional techniques for the determination of orientational order parameter. The results for the two compounds are compared with those values estimated from n _e, n _o and density using the two internal field models due to Vuks and Neugebauer applicable to nematic phase.     

Environmental pollution due to black carbon aerosols and its impacts in a tropical urban city

Black carbon (BC) has become the subject of interest in the recent years for a variety of reasons. BC aerosol may cause environmental as well as harmful health effects in densely inhabited regions. BC is a strong absorber of radiation in the visible and near-infrared part of the spectrum, where most of the solar energy is distributed. Black carbon is emitted into the atmosphere as a byproduct of all combustion processes, viz., vegetation burning, industrial effluents, motor vehicle exhausts, etc. In this paper, we present results from our measurements on BC aerosols, total aerosol mass concentration, and aerosol optical depth over an urban environment, namely Hyderabad during January-May, 2003. Diurnal variations of BC suggest that high BC concentrations are observed during 6:00-9:00 h and 19:00-23:00 h. Weekday variations of BC suggest that the day average BC concentrations increases gradually from Monday to Wednesday and gradually decreases from Thursday to Sunday. Fraction of BC to total mass concentration has been observed to be 7%. BC showed positive correlation with total mass concentration and aerosol optical depth at 500 nm. Radiative transfer calculations suggest that during January-May, diurnal averaged aerosol forcing at the surface was calculated to be −33 Wm⁻² and at the top of the atmosphere (TOA) it is to be +9 Wm⁻².     

Biogenic Synthesis of NiO Nanoparticles Using Areca catechu Leaf Extract and Their Antidiabetic and Cytotoxic Effects

Nanoworld is an attractive sphere with the potential to explore novel nanomaterials with valuable applications in medicinal science. Herein, we report an efficient and ecofriendly approach for the synthesis of Nickel oxide nanoparticles (NiO NPs) via a solution combustion method using Areca catechu leaf extract. As-prepared NiO NPs were characterized using various analytical tools such as powder X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and UV-Visible spectroscopy (UV-Vis). XRD analysis illustrates that synthesized NiO NPs are hexagonal structured crystallites with an average size of 5.46 nm and a hexagonal-shaped morphology with slight agglomeration. The morphology, size, and shape of the obtained material was further confirmed using SEM and TEM analysis. In addition, as-prepared NiO NPs have shown potential antidiabetic and anticancer properties. Our results suggest that the inhibition of α-amylase enzyme with IC 50 value 268.13 µg/mL may be one of the feasible ways through which the NiO NPs exert their hypoglycemic effect. Furthermore, cytotoxic activity performed using NiO NPs exhibited against human lung cancer cell line (A549) proved that the prepared NiO NPs have significant anticancer activity with 93.349 μg/mL at 50% inhibition concentration. The biological assay results revealed that NiO NPs exhibited significant cytotoxicity against human lung cancer cell line (A549) in a dose-dependent manner from 0–100 μg/mL, showing considerable cell viability. Further, the systematic approach deliberates the NiO NPs as a function of phenolic extracts of A. catechu with vast potential for many biological and biomedical applications.     

Hirshfeld Surface Analysis and Crystal Structure of [2-Bromo-4-(4-Fluoro-Benzoyl)-Phenoxy]-Acetic Acid Ethyl Ester

The title compound C₁₇H₁₄BrFO₄ was synthesized using 3-Bromo-4-hydroxy-phenyl-(4-fluoro-phenyl)-methanone, ethyl chloroacetate, and anhydrous potassium carbonate. Its structure was established using elemental analysis, NMR, and single crystal X-ray diffraction techniques. The compound crystallizes in orthorhombic crystal system and space group Pbca. The cell parameters are a = 10.1444(13) Å, b = 8.2781(10) Å, c = 38.423(5) Å, Z = 8, V = 3226.6(7) ų. The dihedral angle between two least squares planes of two phenyl rings bridged by keto carbonyl group is ?28.2(5)°. The molecule exhibits intermolecular interactions of the type C?H…F and C?H…O. The intercontacts in the crystal structure are studied using Hirshfeld surface analysis.     

Soliton in discrete and continuum alpha helical proteins with higher-order excitations

We consider discrete and continuum models of alpha helical proteins with different orders of molecular excitations and interactions. In both the cases integrable models were identified for specific choice of parameters and the elementary excitations expressed in terms of solitons. Also, equivalent integrable Heisenberg spin systems were obtained.     

A slope modification method for shallow water equations

A slope modification method is proposed for non-oscillatory schemes based on the Lax-Friedrich solver. The modified scheme is proved to be total-variation-diminishing (TVD) and second-order accurate. Application of the scheme to the shallow water equations produces sharp profiles for shocks and achieves high accuracy in the smooth regions of the solution.     

Electrophoretic analysis and purification of fluorescent single-walled carbon nanotube fragments

Arc-synthesized single-walled carbon nanotubes have been purified through preparative electrophoresis in agarose gel and glass bead matrixes. Two major impurities were isolated: fluorescent carbon and short tubular carbon. Analysis of these two classes of impurities was done. The methods described may be readily extended to the separation of other water-soluble nanoparticles. The separated fluorescent carbon and short tubule carbon species promise to be interesting nanomaterials in their own right.     

Formulation development and evaluation of metronidazole magnetic nanosuspension as a magnetic-targeted and polymeric-controlled drug delivery system

A nanosuspension of magnetically tagged metronidazole was developed by the solvent displacement method coupled with ultrasonication and was evaluated for its physicochemical properties. The drug release from metronidazole magnetic nanosuspension at pH 1.2 and 7.0 shows maximum correlation coefficient for zero order and Higuchi model, respectively. The anthelmintic activity of the formulated metronidazole magnetic nanosuspension was evaluated on Indian earthworms (Pheretima poi). Metronidazole magnetic nanosuspension at a dose of 10 and 50 mg/ml shortened by 31% and 34%, respectively, the mean time to death of the earthworms when compared against a non-magnetic metronidazole suspension. Thus, the developed metronidazole magnetic nanosuspension showed potent, controlled and targeted drug action and might be a good therapeutic avenue in combating infectious GI disorders.     

A mild, one-pot synthesis of 3-cyano-4-benzopyrones from 2-hydroxyacetophenones

A simple one-pot synthesis of 3-cyano-4-benzopyrones directly from 2-hydroxyacetophenones using mild conditions is reported herein.     

An efficient and green protocol for the preparation of cycloalkanols: a practical synthesis of venlafaxine

The condensation of arylacetonitriles with cyclic ketones using aqueous NaOH or KOH under phase transfer catalysis gives almost quantitative yields of cycloalkanols. This protocol is utilized for a practical synthesis of the antidepression drug, venlafaxine 1.