Effect of anionic surfactant sodium dodecyl sulfate on the reaction of hexacyanoferrate(III) oxidation of levothyroxine in aqueous medium: a kinetic and mechanistic approach

The effect of anionic surfactant sodium dodecyl sulfate (SDS) on the rate of oxidation of levothyroxine (LVT) by hexacyanoferrate(III) in alkaline medium has been investigated spectrophotometrically at different temperatures. The reaction follows a complex kinetics showing first order dependence of rate with respect to both alkali and LVT. The effect of SDS on the rate of reaction has been observed at the critical miceller concentration of the surfactant. indicating binding of the substrate with the surfactant micelle. The binding parameters have also been evaluated using the Menger and Portnoy model.     

Investigation of Micellar and Phase Separation Phenomenon of the Amphiphilic Drug Amitriptyline Hydrochloride with Cationic Hydrotropes

Micellization and phase separation of the amphiphilic drug amitriptyline hydrochloride (AMT) in the absence and presence of cationic hydrotropes (aniline hydrochloride, para-toluidine hydrochloride, and ortho-toluidine hydrochloride) have been investigated in the present study. The experimental critical micelle concentration (cmc) values are lower than cmc ^id values (cmc ^id is the cmc value at ideal mixing state), indicating attractive interactions between the two components (drug and hydrotrope) in mixed micelles. The bulk behaviors were investigated using the different theoretical models of Clint, Rubingh, Motomura, and Rodenas for comparison of the results of different binary combinations of the drug and hydrotropes. Synergistic interactions were confirmed in all binary combinations at all temperatures, which increase with increasing concentration of hydrotropes. Activity coefficients (f ₁ and f ₂) were found to be consistently less than unity indicating nonideality in the systems. At a fixed drug concentration (50 mmol·dm^?3) and pH (6.7), the hydrotropes showed a continuous increase in the cloud point. Thermodynamic parameters were also evaluated and discussed in detail.     

A green-nanocomposite film based on poly(vinyl alcohol)/ Eleusine coracana: structural,thermal, and morphological properties

Recently, polymer nanocomposites can offer to enhance the tremendous development of reinforcements and broaden their use in feasible applications. The polyvinyl alcohol (PVA) polymer based bio-nanocomposite film reinforced with different amount of Eleusine Coracana (EC) particles from 5 to 25?wt% were prepared by the solution cast. The bio-nanocomposite (PVA/EC) film was characterized by the X-ray diffraction (XRD), and Fourier transform infrared (FTIR). Thermo-gravimetric analysis (TGA) is used to estimate the thermal degradation of polymer bio-nanocomposites. From the Atomic Force Microscopy (AFM) analysis, the surface roughness of the (PVA/EC) film was analyzed.     

Acetone sensor based on solvothermally prepared ZnO doped with Co3O4 nanorods

This paper describes a reliable and sensitive method for sensing dissolved acetone using doped nanomaterials. Large-scale synthesis of ZnO nanorods (NRs) doped with Co₃O₄ was accomplished by a solvothermal method at low temperature. The doped NRs were characterized in terms of their morphological, structural, and optical properties by using field-emission scanning electron microscopy coupled with energy-dispersive system, UV-Vis., Fourier transform IR, X-ray diffraction, and Xray photoelectron spectroscopy. The calcinated (at 400 °C) doped NRs are shown to be an attractive semiconductor nanomaterial for detecting acetone in aqueous solution using silver electrodes. The sensor exhibits excellent sensitivity, stability and reproducibility. The calibration plot is linear over a large concentration range (66.8 μM to 0.133 mM), displays high sensitivity (~3.58 μA cm^?2 mM^?1) and a low detection limit (~14.7?±?0.2 μM; at SNR of 3).

A modified Cassie–Baxter relationship to explain contact angle hysteresis and anisotropy on non-wetting textured surfaces

The Cassie–Baxter model is widely used to predict the apparent contact angles obtained on composite (solid–liquid–air) superhydrophobic interfaces. However, the validity of this model has been repeatedly challenged by various research groups because of its inherent inability to predict contact angle hysteresis. In our recent work, we have developed robust omniphobic surfaces which repel a wide range of liquids. An interesting corollary of constructing such surfaces is that it becomes possible to directly image the solid–liquid–air triple-phase contact line on a composite interface, using an electron microscope with non-volatile organic liquids or curable polymers. Here, we fabricate a range of model superoleophobic surfaces with controlled surface topography in order to correlate the details of the local texture with the experimentally observed apparent contact angles. Based on these experiments, in conjunction with numerical simulations, we modify the classical Cassie–Baxter relation to include a local differential texture parameter which enables us to quantitatively predict the apparent advancing and receding contact angles, as well as contact angle hysteresis. This quantitative prediction also allows us to provide an a priori estimation of roll-off angles for a given textured substrate. Using this understanding we design model substrates that display extremely small or extremely large roll-off angles, as well as surfaces that demonstrate direction-dependent wettability, through a systematic control of surface topography and connectivity.     

"On water" sp3-sp2 cross-couplings between benzylic and alkenyl halides

Organic-solvent-free cross-couplings between benzylic and alkenyl halides have been developed. Various alkenyl halides can be efficiently benzylated by combining the precursor halides in the presence of Zn dust and a Pd catalyst at room temperature, in water as the only medium.     

A study on optical limiting properties of Eosin-Y and Eriochrome Black-T dye-doped poly (vinyl alcohol) composite film

A poly (vinyl alcohol) PVA/Eriochrome Black-T (EBT) dye, and PVA/Eosin-Y (EY) dye composite film was prepared using a solution casting process. The dye-doped composite polymer films were characterized by UV–vis spectroscopy. An optical band gap (E_g) of pure PVA reduced from 4.22?eV to 2.80?eV for PVA/EBT film and 2.14?eV for PVA/EY film respectively. This result indicates the occurrence of inter-molecular hydrogen bonding between the –OH functional group in PVA chains and sulfonate (EBT) and carboxyl group (EY) in dye molecules, respectively. Moreover, the experimental result of PVA/EBT and PVA/EY composite film showed the excellent properties of a large scale cut-off filter in the ultraviolet and visible range region.     

Direct measurement of acid-base interaction energy at solid interfaces

We have studied acid-base interactions at solid-liquid and solid-solid interfaces using interface-sensitive sum frequency generation (SFG) spectroscopy. The shift of the sapphire hydroxyl peak in contact with several polar and nonpolar liquids and polymers was used to determine the interaction energy. The trend in the interaction energies cannot be explained by measuring only water contact angles. Molecular rearrangements at the sapphire interface, to maximize the interaction of the acid-base groups, play a dominant role, and these effects are not accounted for in the current theoretical models. These results provide important insights into understanding adhesion, friction, and wetting on solid interfaces.     

Mercury selective membrane electrode based on dithio derivatized macrotricyclic compound

A novel dithio derivatized macrotricyclic compound (cryptand) has been synthesized using high dilution technique by condensation of diaminodibenzo18-crown-6 with 2, 2′dithiobenzoyl chloride. The compound was characterized by elemental analysis, ¹H NMR, ¹³C NMR and FAB-MS. PVC membrane electrode based on this macrotricyclic compound showed good selectivity for Hg²⁺ ion with a wide linear range of 1.0 × 10^?6 to 1.0 × 10^?1 M and a lower detection limit of 5.0 × 10^?6 M with a calibration slope of 30.2 mV decade^?1. The electrode response was stable in pH range 3–6. Electrode showed good selectivity for Hg²⁺ over other interfering metal ions. The electrode was then applied to direct determination of Hg²⁺ in water samples.