Use of polyacrylamide-grafted<Emphasis Type="Italic"> Plantago psyllium</Emphasis> mucilage as a flocculant for treatment of textile wastewater

The chemical modification of Plantago psyllium mucilage (Psy), an anionic polysaccharide, was done by grafting polyacrylamide (PAM) chains to prepare a graft-copolymer (Psy-g-PAM). It was synthesized in the presence of nitrogen using ceric ammonium nitrate–nitric acid redox initiator and characterized by IR spectroscopy, scanning electron microscopy and viscosity measurements. This grafted copolymer was tested for its flocculation efficiency in textile wastewater by the standard Jar test method. The effects of polymer concentration, pH and contact time on the percentage removal of solid wastes [total dissolved solids (TDS) and suspended solids (SS)] and color from textile effluent are reported. The optimum dose was found to be 1.6 mg l^–1, at which maximum solid removal (SS and TDS) was seen. The most suitable pH for TDS and color removal was neutral (7.0) and for SS removal alkaline pH (9.2) was found to be most suitable. The optimum treatment duration for solid waste removal was 5 h. The X-ray diffraction analysis of Psy-g-PAM and solid waste before and after treatment suggests the interaction of the solid waste and Psy-g-PAM copolymer.     

High temperature magnetic ordering in La2RuO5

Magnetic susceptibility, heat capacity and electrical resistivity measurements have been carried out on a new ruthenate, La₂RuO₅ (monoclinic, space group P2₁/c) which reveal that this compound is a magnetic semiconductor with a high magnetic ordering temperature of 170 K. The entropy associated with the magnetic transition is 8.3 J/mol K close to that expected for the low spin (S=1) state of Ru⁴⁺ ions. The low temperatures specific heat coefficient γ is found to be nearly zero consistent with the semiconducting nature of the compound. The magnetic ordering temperature of La₂RuO₅ is comparable to the highest known Curie temperature of another ruthenate, namely, metallic SrRuO₃, and in both these compounds the nominal charge state of Ru is 4+.     

Synthesis and electrochemical studies of charge-transfer complexes of thiazolidine-2,4-dione with σ and π acceptors

In the present work, we report the synthesis and characterization of novel charge-transfer complexes of thiazolidine-2,4-dione (TZD) with sigma acceptor (iodine) and pi acceptors (chloranil, dichlorodicyanoquinone, picric acid and duraquinone). We also evaluated their thermal and electrochemical properties and we conclude that these complexes are frequency dependent. Charge-transfer complex between thiazolidine-2,4-dione and iodine give best conductivity. In conclusion, complex with sigma acceptors are more conducting than with pi acceptors.     

Steady-state fluorescence investigations of aqueous binary mixtures of myristyl alcohol based bis-sulfosuccinate anionic gemini surfactant and effect of different conventional surfactants therein

The present research work is associated with the fluorescence investigations of binary aqueous mixed surfactants solutions of anionic bis-sulfosuccinate gemini surfactant (BSGSMA_1,8) and three different conventional surfactants—anionic viz. sodium dodecyl sulfate (SDS), cationic viz. cetyl trimethyl ammonium bromide (CTAB), and nonionic surfactant viz. Triton X 100. Steady-state fluorescence spectroscopy technique has been utilized to examine the micellization behavior of aqueous solution of pure myristyl alcohol-based BSGSMA_1,8 having flexible methylene chain [(CH₂)₈] as spacer group. Critical micelle concentration (CMC), aggregation number (N), and micropolarity of pure and mixed surfactants systems were explored during the investigations. The results revealed the best synergism behavior of prepared gemini BSGSMA_1,8 with SDS as compared to CTAB and Triton X 100. The maximum reduction in the value of pyrene intensity ratio (I₁/I₃) was observed for gemini and SDS mixed surfactant solution. On the other hand, the increased I₁/I₃ value of mixed gemini with Triton X 100 exhibited that mixed surfactant system of anionic gemini BSGSMA_1,8 with non-ionic Triton X 100 is not as compact as other mixed surfactant systems. Aggregation number increased and micropolarity decreased with increased concentration of gemini surfactants.     

1-Decanethiol, a new reagent for the odorless deprotection of aryl methyl ethers

1-Decanethiol has been found to be an excellent reagent for the deprotection of aryl methyl ethers. This newly developed protocol afforded the corresponding phenols in good to excellent yields. A clear advantage of 1-decanethiol over the more commonly used thiols is the easy extraction of both the deprotecting reagent and the reaction byproduct into the aqueous phase, which allows an essentially odorless work-up.     

The first examples of supramolecular discotic C3h tris(N-salicylideneamine)s featuring inter- and intra-molecular H-bonding: synthesis and characterization

Supramolecular liquid crystalline tris(N-salicylideneamine)s (TSANs) featuring both inter- and intra-molecular hydrogen bonding have been synthesized and characterized for the first time. These TSANs formed by condensing 3 equiv of 3,4,5-trialkoxybenzoylhydrazine with 1,3,5-triformylphloroglucinol exist as the single C_3h-symmetric keto-enamine product solely, unlike the previously reported TSANs. Their self-assembly into supramolecular fluid hexagonal columnar phase over a wide thermal range is evidenced with the aid of optical microscopic, calorimetric, and powder X-ray diffraction techniques.     

Effect of radiation dose on the properties of natural rubber nanocomposite

Effect of radiation dose and carbon nanotubes (CNT) on the mechanical properties of standard Malaysian rubber (SMR) was investigated in this study. SMR nanocomposites containing 1–7 phr CNT were prepared using the solvent casting method and the nanocomposites were radiated at doses of 50–200 kGy. The change in mechanical properties, especially, tensile strength (Ts), elongation at break (Eb), hardness and tensile modulus at 100% elongation (M₁₀₀) were studied as a function of radiation dose. The structure and morphology of reinforced natural rubber was investigated by FESEM, TEM and AFM in order to gain further evidence on the radiation-induced crosslinking. It was found that the Ts, M₁₀₀ and the hardness of the SMR/CNT nanocomposites significantly increased with radiation dose; the elongation at break exhibited an increase up to 100 kGy, and a downward trend thereafter. Results on gel fraction further confirmed the crosslinking of SMR/CNT nanocomposites upon radiation.     

On simplifying ‘incremental remap’–based transport schemes

The flux-form incremental remapping transport scheme introduced by Dukowicz and Baumgardner [1] converts the transport problem into a remapping problem. This involves identifying overlap areas between quadrilateral flux-areas and regular square grid cells which is non-trivial and leads to some algorithm complexity. In the simpler swept area approach (originally introduced by Hirt et al. [2]) the search for overlap areas is eliminated even if the flux-areas overlap several regular grid cells. The resulting simplified scheme leads to a much simpler and robust algorithm.     

Modulation transfer in Doppler broadened Λ system and its application to frequency offset locking

We investigate modulation transfer through pump induced atomic coherence in pump-probe spectroscopy of Doppler broadened medium of cesium atoms. The mechanism of modulation transfer is discussed for a three level Λ configuration under slow frequency modulation. Modulation transfer is demonstrated by performing frequency modulation spectroscopy (FMS) on a sub-natural linewidth (<2 MHz) electromagnetically induced transparency (EIT) signal. Here the pump laser is modulated by acousto-optic frequency modulation and the modulation is transferred to the probe laser through atomic coherence. Finally the probe laser is locked on the first derivative spectrum of EIT signal. Such atomic frequency offset locking system totally removes the necessity of direct modulation of laser frequency, so that the spectral resolution is limited only by the practical linewidth of the laser systems. Moreover it provides a novel way to eliminate the additional frequency and intensity noise associated with direct frequency dithering, which may limit the experimental resolution.