Spectral-domain optical coherence phase microscopy for quantitative phase-contrast imaging

We describe a novel microscopy technique for quantitative phase-contrast imaging of a transparent specimen. The technique is based on depth-resolved phase information provided by common path spectral-domain optical coherence tomography and can measure minute phase variations caused by changes in refractive index and thickness inside the specimen. We demonstrate subnanometer level path-length sensitivity and present images obtained on reflection from a known phase object and human epithelial cheek cells.     

A novel microwave-mediated one-pot synthesis of indolizines via a three-component reaction

[reaction: see text] The microwave-mediated three-component reaction of acyl bromide, pyridine, and acetylene is catalyzed by basic alumina to give corresponding indolizines in excellent yields in a one-pot reaction.     

Amberlyst A21: A reusable solid catalyst for green synthesis of pyran annulated heterocycles at room temperature

Amberlyst A21, a neutral ion-exchange resin and a solid base, can catalyze the three-component reaction of aldehyde and malononitrile with various active methylene compounds at room temperature to synthesize a range of pharmaceutically important pyran annulated heterocycles. Use of the solid base could generate a highly green protocol by eliminating chromatographic purification that involves hazardous organic solvents, and facilitate easy recovery and reusability of the catalyst.     

Some new proofs of modular relations for the Göllnitz-Gordon functions

In this paper, we find new proofs of modular relations for the Göllnitz-Gordon functions established earlier by S.-S. Huang and S.-L. Chen. We use Schröter’s formulas and some simple theta-function identities of Ramanujan to establish the relations. We also find some new modular relations of the same nature.     

Banana pulp extract mediated synthesis of Cu2O nanoparticles: An efficient heterogeneous catalyst for the ipso-hydroxylation of arylboronic acids

A green and facile novel procedure has been developed for the synthesis of Cu₂O nanoparticles within a very short reaction time using banana pulp extract as a reducing agent. The synthesized nanoparticles are well characterized by SEM (Scanning Electron Microscope), TEM (Transmission Electron Microscope) and powder XRD (X-ray Diffraction) methods. An environmental benign and highly efficient protocol for the ipso-hydroxylation of aryl and hetero arylboronic acids using bio-fabricated Cu₂O nanoparticles as a catalyst and aqueous H₂O₂ as an oxidant has also been developed. The main advantages of this protocol are the base free reaction condition, reusable and heterogeneous catalytic system, and short reaction time with excellent yields.     

Theoretical studies of some sulphonamides as corrosion inhibitors for mild steel in acidic medium

Density functional theory (DFT) at the B3LYP/6‐31G (d,p) and BP86/CEP‐31G* basis set levels and ab initio calculations using the RHF/6‐31G (d,p) methods were performed on four sulfonamides (namely sulfaacetamide (SAM), sulfapyridine (SPY), sulfamerazine (SMR), and sulfathiazole (STI)) used as corrosion inhibitors for mild steel in acidic medium to determine the relationship between molecular structure and their inhibition efficiencies (%IE). The order of inhibition efficiency obtained was SMR > SPY > STI > SAM which corresponded with the order of most of the calculated quantum chemical parameters namely E_HOMO (highest occupied molecular orbital energy), E_LUMO (lowest unoccupied molecular orbital energy), the energy gap (ΔE), the Mulliken charges on the C, O, N, S atoms, hardness (η), softness (S), polarizability (α), dipole moment (μ), total energy change (ΔE_T), electrophilicity (ω), electron affinity (A), ionization potential (I), the absolute electronegativity (χ), and the fraction of electrons transferred (ΔN). Quantitative structure activity relationship (QSAR) approach has been used and a correlation of the composite index of some of the quantum chemical parameters was performed to characterize the inhibition performance of the sulfonamides studied. The results showed that the %IE of the sulfonamides was closely related to some of the quantum chemical parameters but with varying degrees/order. The calculated %IE of the sulfonamides studied was found to be close to their experimental corrosion inhibition efficiencies. The experimental data obtained fits the Langmuir adsorption isotherm. The negative sign of the E_HOMO values and other thermodynamic parameters obtained indicates that the data obtained supports physical adsorption mechanism. © 2009 Wiley Periodicals, Inc. Int J Quantum Chem, 2010     

Extreme nonlinear optical enhancement in chalcogenide glass fibers with deep-subwavelength metallic nanowires

A nanostructured chalcogenide-metal optical fiber is proposed. This hybrid nanofiber is embedded with a periodic array of triangular-shaped deep-subwavelength metallic nanowires set up in a bowtie configuration. Our simulations show that the proposed nanostructured fiber supports a guided plasmonic mode enabling both subwavelength field confinement and extreme nonlinear light-matter interactions, much larger than a bare chalcogenide nanowire of comparable diameter. This is all achieved with less than 3% by volume of metal content.     

Mesoporous silica and chitosan based pH-sensitive smart nanoparticles for tumor targeted drug delivery

This study investigated inclusion formation and the physicochemical properties of naringin/cyclodextrin through a combined computational and experimental approach. Molecular dynamics simulations were applied to investigate the thermodynamics and geometry of naringin/cyclodextrin cavity docking. The complexes were investigated by UV, FT-IR, DSC, XRD, SEM, 2D-NOSEY and ¹H-NMR analyses. Clearly visible protons belonging to naringin and chemical shift displacements of the H3 and H5 protons in cyclodextrin were anticipated in the formation of an inclusion complex. Naringin solubility increased linearly with increasing cyclodextrin concentration (displaying an A_L profile). The simulations indicated that the phenyl group of naringin was located deep within the cyclodextrin cavity, while the glycoside group of naringin was on the plane of the wider rim of cyclodextrin. The simulation and molecular modeling results indicate that (2-hydroxypropyl)-β-cyclodextrin (HP-β-CD) provided the more stable inclusion complex. This result was also in good concordance with the stability constants that had been determined by the phase solubility method. The consistency of the computational and experimental results indicates their reliability.     

Transversity of quarks in a nucleon

The transversity distribution of quarks in a nucleon is one of the three fundamental distributions, that characterize nucleon's properties in hard scattering processes at leading twist (twist 2). It measures the distribution of quark transverse spin in a nucleon polarized transverse to its (infinite) momentum. It is a chiral-odd twist-two distribution function — gluons do not couple to it. Quarks in a nucleon/hadron are relativistically bound and transversity is a measure of the relativistic nature of bound quarks in a nucleon. In this work, we review some important aspects of this less familiar distribution function which has not been measured experimentally so far.