Synthesis,micellization properties,and cytotoxicity trends of N-hydroxyethyl-3-alkyloxypyridinium surfactants

N-hydroxyethyl-3-alkyloxypyridinium amphiphiles have been synthesized and characterized by various spectroscopic techniques. Self-assembling properties of these amphiphiles have been studied by surface tension, conductivity, and fluorescence measurements. Basic micellization parameters like critical micelle concentration (cmc), surface tension at the cmc (γ _cmc), adsorption efficiency (pC₂₀), effectiveness of surface tension reduction (Π _cmc), maximum surface excess concentration (Γ _max) and minimum surface area/molecule (A _min), and Gibbs free energy of the micellization (ΔG⁰ _mic) have also been determined. The micellization of these 3-alkyloxypyridinium halides in aqueous phase have been found to be exothermic and entropy-driven as assessed by conductivity measurements at different temperatures. Thermal degradation of these surfactants has also been assessed by thermal gravimetric analysis under nitrogen atmosphere. Further, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay of these surfactants on C6 glioma cells show them to be less toxic than conventional cationic surfactants.     

Synthesis, characterization and photoluminescence properties of Ce3+-doped ZnO-nanophosphors

The present study involves the synthesis of Ce³⁺ doped ZnO nanophosphors by the zinc nitrate and cerium nitrate co-precipitation method. The synthesized nanophosphors were characterized with respect to their crystal structure, crystal morphology, particle size and photoluminescence (PL) properties using X-ray diffraction (XRD), scanning electron microscopy (SEM)/energy dispersive X-ray (EDX), transmission electron microscopy (TEM)/Energy-dispersive X-ray spectroscopy (EDS) and PL-spectroscopy respectively. XRD results revealed that ZnO nanophosphors are single phase and cubic type structures. Further, PL spectra of ZnO:Ce³⁺ nanophosphors showed green emission because of the charge transfer at single occupied oxygen vacancies with ZnO holes and red emission due to the cerium ion transitions. Intensity and fine structure of the Ce³⁺ luminescence and its temperature dependence are strongly influenced by the doping conditions. The formation of ZnO:Ce³⁺ nanophosphors was confirmed by Fourier transform infrared (FTIR) and XRD spectra.     

Temperature dependent selective synthesis of linear 2-bromo and 2-alkoxyfuro[2,3-b]quinolines: reaction of 3-(2,2-dibromovinyl-)quinolin-2(1H)-ones with alcoholic KOH

Base promoted and temperature dependent reactions of 3-(2,2-dibromovinyl)quinolin-2(1H)-ones have been described. At 50 °C, the cyclization reactions afforded 2-bromofuro[2,3-b]quinolines in good yields. However, at elevated temperature (80 °C) the domino reaction proceeded affording 2-alkoxyfuro[2,3-b]quinolines via cyclization and nucleophilic substitution reactions.     

Development of ion chromatography and capillary electrophoresis methods for the determination of Li in Li–Al alloy

Two methods were developed for determination Li content in Li–Al alloy by employing ion chromatography (IC) and capillary electrophoresis (CE) without any prior separation of Al matrix. In absence of suitable certified reference material the two methods were used to validate each other. Using a high capacity column and a weaker eluent methane sulphonic acid, it was possible to separate Li in IC without eluting strongly retained Al. The method showed good precision and sensitivity and was extended for analysis of routine samples. In the case of CE using imidazole as co-ion, Li was detected in CE by indirect detection. In view of no interference from Al, samples were analyzed without any matrix separation. The CE method was used successfully for sample analysis and results were compared with IC results.     

Incident investigation on thermal instability of an intermediate using adiabatic calorimeter

Thermal instability is a loss of thermal control which liberates high amount of energy and pressure. An incident took place during drying of an intermediate having amino alcohol functional group in agitated nutsche filter dryer at plant scale. During our investigation using advanced reactive system screening tool (ARSST), thermal decomposition was observed. Onset temperature of decomposition (T _o) is at 85 °C, adiabatic temperature rise due to decomposition (ΔT _ad) is 215 °C, maximum temperature attained due to decomposition (T _max) is 300 °C, maximum self-heat rate (dT/dt)_max is 6,215 °C min^?1, and maximum rate of pressure rise (dP/dt)_max is 1,442 psi min^?1 obtained from ARSST experiments. T _D24 value is 75 °C which was estimated experimentally. The correlations of these results were utilized to identify the root cause of this incident and necessary control measures were taken accordingly.     

A novel process for making alkaline iron oxide nanoparticles by a solvo thermal approach

In the present work alkaline iron oxide nanoparticles are synthesized by a novel solvo thermal approach and characterized exhaustively by various complementary techniques. Field emission scanning electron microscopy (FESEM) studies reveal that the size of nanoparticles is in the range of 31.5 nm to 96.9 nm. Energy-dispersive X-ray spectroscopy spectral analysis reveals the presence of oxygen, carbon, iron, and sodium. The X-ray diffraction studies confirm the formation of tetragonal NaFeO₂ as the major phase along with orthorhombic NaFeO₂·H₂O and rhombohedral FeCO₃ (siderite) as the minor phases. Fourier transform infrared spectroscopy exhibits peaks due to the stretching and bending vibrations of O-H, C=O, CH₃-N, CH₃, C-H, C-N, and Fe-O groups. Differential scanning calorimetry (DSC) results display an endothermic peak at 100.85°C and a very small endothermic peak at 791.56°C with 819.73 mJ and 349.28 mJ energies respectively. These DSC peaks can be correlated with thermal gravimetric analysis (TGA) peaks representing 31.04% weight loss and 7.70% weight loss respectively in the sample at around 160°C and 980°C respectively.     

Synthesis of novel pyrimidine nucleoside analogues owning multiple bases/sugars and their glycosidase inhibitory activity

A series of novel nucleoside analogues having dual bases (pyrimidine and triazole) and sugars have been synthesized by CuAAC reaction of azido sugars with propynylated pyrimidines. These compounds were evaluated for their in vitro α-glucosidase inhibitory activity. In this series, compounds 4b, 4d, 8a, 8b, 8c, 8e, 8g, 8h, and 8i exhibited very good inhibition of α-glucosidase enzyme. Nucleoside analogues 8a, 4b, 8h, and 8c displayed 47.4%, 41.8%, 39.4%, and 34.6% inhibition, respectively, comparable to the standard drug acarbose (53.4%).     

Direct Synthesis of Hexagonal NaGdF4 Nanocrystals from a Single‐Source Precursor: Upconverting NaGdF4:Yb3+,Tm3+ and Its Composites with TiO2 for Near‐IR‐Driven Photocatalysis

A novel single‐source precursor NaGd(TFA)₄(diglyme) (TFA=trifluoroacetate) was synthesized, characterized thoroughly, and used to obtain the hexagonal phase of NaGdF₄ nanoparticles as an efficient matrix for lanthanide‐doped upconverting nanocrystals (NCs) that convert near‐infrared radiation into shorter‐wavelength UV/visible light. These NCs were then used to prepare well‐characterized TiO₂@NaGdF₄:Yb³⁺,Tm³⁺ nanocomposites to extend the absorption range of the TiO₂ photocatalyst from the UV to the IR region. While the visible/near IR part of the photoluminescent spectra remains almost unaffected by the presence of TiO₂, the UV part is strongly quenched due to the absorption of TiO₂ above its gap at approximately 380 nm by energy transfer or FRET. Preliminary results on the photocatalytic activity of the above obtained nanocomposites are presented.     

Polymers from Renewable Resources. Xiv. Interpenetrating Polymer Networks Derived from Castor Oil—Isophorone Diisocyanate-Polyacrylamide: Thermal,Scanning Electron Microscopy,and Xrd Studies

Abstract

A large number of castor oil based polyurethanes were prepared using various diisocyanates such as isophorone diisocyanate varying the NCO/OH ratio. All the polyurethanes were reacted with acrylamide and methacrylamide using ethylene glycol dimethacrylate as crosslinker and benzoyl peroxide as initiator. Thermogravimetric analysis of the polymers were followed using computer analysis method for assigning the kinetic mechanism. The degradation steps have been discussed in the light of kinetic parameters. The SEM of some of the IPNs has been studied and the morphology has been examined. The samples were subjected to wide angle X-ray diffraction analysis. Ruland and Vonk method was used to calculate the degree of crystallinity (X_cr).     

Ethylene-vinyl acetate (EVA)/polycaprolactone (PCL)–Fe3O4 composites

In this study, we investigate the effect of nano sized Fe₃O₄ nanoparticles on the mechanical and thermal properties of EVA/PCL–Fe₃O₄ composites. Composites were prepared using the melt mixing technique on a Rheomex mixer coupled to a single screw extruder. The fine dispersion of nano-Fe₃O₄ aggregates in the polymer matrices led to a significant improvement in the crystallinity, thermal and mechanical properties of EVA/PCL–Fe₃O₄ nanocomposites compared to that of native polymers due to improved interface bonding between the filler and the polymer matrix. Techniques such as scanning electron microscopy (SEM), differential scanning calorimetry (DSC), and Instron for mechanical properties were used to characterize nanocomposites samples. The results obtained from this investigation demonstrated that composite materials could be promising raw materials in industry.