Non-destructive compositional analysis of sol–gel synthesized lithium titanate (Li2TiO3) by particle induced gamma-ray emission and instrumental neutron activation analysis

Lithium titanate, one of the important tritium breeding materials in D–T based fusion reactor under ITER programme, was synthesized through sol–gel route. For chemical quality control of finished product, it was necessary to quantify the lithium and titanium contents. As this ceramic sample is difficult to dissolve, non-destructive analytical methods are preferred for compositional analysis. In the present work, two non-destructive nuclear analytical methods namely particle induced gamma-ray emission (PIGE) using proton beam and instrumental neutron activation analysis (INAA) using reactor neutrons were standardized for the determination of lithium and titanium concentrations, respectively and applied to eleven samples of lithium titanate. To the best of our knowledge, Li quantification in lithium titanate sample is being reported for the first time using PIGE. For quantifications of Li and Ti, 478 keV prompt gamma-ray from ⁷Li (p, p′γ) ⁷Li and 320 keV gamma-ray from ⁵⁰Ti (n,γ) ⁵¹Ti were measured, respectively, by high resolution gamma-ray spectrometry. The PIGE and INAA methods were validated using several synthetic samples containing lithium and titanium, respectively. Concentrations of lithium and titanium and Li/Ti mole ratios were evaluated and compared with the stoichiometric concentration of Li₂TiO₃.     

Synthesis and studies of some cholest-5-en-3-ol-(3β)[4-phenylpyridylazo]carbonate-containing supramolecular hydrogen-bonded mesogens

Mesogenic materials containing cholest-5-en-3-ol-(3β)[4-phenylpyridylazo]carbonate (CPPC) and 4-n-alkyloxybenzoic acids have been synthesized using hydrogen bonding as a mechanism for self-assembly. Phase diagrams of the binary mixtures of the hydrogen bond donor and acceptor were established using polarizing optical microscopy. The maximum isotropization point was observed for the 50 mol % composition confirming the formation of stable 1 : 1 complexes due to intermolecular hydrogen bonding. All the supramolecular assemblies built from 1 : 1 molar ratios of the hydrogen bond donor and acceptor moieties exhibit well defined smectic A (SmA) liquid crystal phases on heating and cooling cycles. The SmA phases exhibited by the complexes are not observed for the individual components. The azobenzene moiety of CPPC undergoes trans-cis-photoisomerization with a quantum yield of 0.1 and the activation energy for the thermal cis-trans-isomerization was estimated as 92 kJ mol-¹.     

A novel amino acid functionalized ionic liquid promoted one-pot solvent-free synthesis of 3,4-dihydropyrimidin-2-(1H)-thiones

An environmentally benign, cheap and reusable L-amino acid functionalized ionic liquid [L-AAIL]/AlCl₃ was found to be an effective catalyst for the synthesis of 3,4-dihydropyrimidine-2-(1H)-thione derivatives in good to excellent yield under solvent-free condition. Compared with the classical Biginelli reactions, this method consistently enjoys the advantages of mild reaction conditions, easy work-up, and short reaction time. These one-pot three-component Biginelli products could be separated easily from the catalyst–water system, and the catalyst could be reused at least five times without noticeably reducing catalytic activity.     

Experimental analysis on nano scale flash powder composition in fireworks manufacturing

The flash powder composition is used in the fireworks industry to manufacture the firecrackers which consist of potassium nitrate, aluminium and sulphur in 75 μm range. This study focuses on the synthesis of nano and micro flash powders with different trials of composition. The particle sizes of the nanochemicals are 142.8, 93.10 and 91.28 nm for KNO₃, Al and S, respectively. The nano flash powder is mixed with micron flash powder in different ratios to manufacture the crackers and thus the noise level for the crackers are found. Thermal analysis was conducted in differential thermal and thermo gravimetric analyser. Also, impact sensitivity and friction sensitivity of the nano flash powder are analysed. The nano flash powder shows low ignition temperature compared to micron and also has high mechanical sensitivity. Fire crackers which contains one gram of 100 % nano flash powder emits the threshold noise level of 125 dB(AI) in spite of 4 g of 10 % nano flash powder for the same composition.     

Rapid separation of acetophenone and its monohydroxy isomers by capillary electrophoresis

This work describes the development of a capillary electrophoresis(CE)method for the simultaneous separation of acetophenone(AP),2-hydroxyacetophenone(2-HAP),3-hydroxyacetophenone(3-HAP)and 4-hydroxyacetophenone(4-HAP)in synthetic mixtures using 10 mmol/L of sodium tetraborate buffer(pH 9.5).The aim of this work is to demonstrate the effectiveness of CE to separate AP and its monohydroxy isomers and to defne how the separations are affected by buffers,buffer pH,sample matrices and separation voltage.This method was successfully used for the trace level separation and determination of 2-HAP,3-HAP and 4-HAP in synthetic mixture and 4-HAP in spiked plasma samples.     

Effect of mobile phase on resolution of the isomers and homologues of tocopherols on a triacontyl stationary phase

Reversed-phase liquid chromatographic (RPLC) separation of isomers and homologues of similar polarity is challenging. Tocopherol isomers and homologues are one such example. α, β, γ, and δ-tocopherols have been successfully separated by RPLC on triacontyl (C₃₀) stationary phase. System suitability was tested by using four mobile phases, and observed chromatographic separations of β and γ-tocopherols were compared. Comparison indicated that methanol–tert-butyl methyl ether (TBME) 95:5 (v/v) at a flow rate of 0.75 mL min^?1 was the best mobile phase. Detection systems were also evaluated on the basis of limit of quantification; it was concluded that fluorescence detection was best. The method was validated by analysis of two homologues and two isomers of tocopherol in sesame, maize, and soybean samples. MS coupled with an ESI interface in negative-ion mode [M ? H]^? was used for identification of individual components. It was concluded that addition of TBME to methanol was required to enhance the separation of β and γ-tocopherols, although methanol alone provided similar results. The applicability of the method to cereal, pulse, and oilseed samples was confirmed. The reproducibility of the procedure was good, with relative standard deviations in the range 1.7–3.9 %. Recovery of tocopherols added to sesame samples ranged from 91 to 99 %.

Rapid Quantification of Efavirenz in Human Plasma by Electrospray Ionization Tandem Mass Spectrometry

We report a rapid and sensitive method for detecting efavirenz in human plasma by electrospray ionization tandem mass spectrometry (ESI‐MS/MS). Detection of efavirenz in human plasma samples was confirmed by acquiring MS/MS of protonated efavirenz at m/z 316.5 to yield the characteristic fragment ions at m/z 298, 274, 272, 251, 246, 237, 232, 203 and 168, respectively. This approach provided good linearity for the quantification of efavirenz (R² = ～0.9989), with good precision (RSD >10%) and limit of detection (0.20 nM). This method can be widely applied for precise quantitative analysis of a variety of drugs in clinical samples.     

Development of Stereoselective Method for the Quantification of Stereoisomers and Geometrical Isomer of Pitavastatin Calcium by Enhanced Approach

A new, simple, selective, and robust normal-phase method for the accurate quantification of all the four stereoisomers and one geometrical isomer of pitavastatin calcium (PIT) in drug substances and drug products was developed. The method is capable of quantifying all the isomers in the presence of other related substances. Separation was achieved using immobilized amylose stationary phase (Chiralpak IA) with a mixture of n-heptane, 1-butanol, methanol, formic acid, and diethylamine. Multivariate analysis and statistical tools were used to develop this highly robust method in a short span of time. A central composite design was employed to study the main effects and interactions of the independent variables. The method exhibited consistent, high-quality recoveries [97.3 ± 1.7 to 99.3 ± 2.1 (mean ± RSD)] with a high precision for all the isomers. Linear regression analysis revealed an excellent correlation between peak responses and concentrations (r ² values of 0.9990–0.9998) for the isomers. The method is sensitive enough to quantify any isomers above 0.02 % and detect any isomer above 0.006 % in PIT. Forced degradation studies proved that the method is specific for isomers. m/z values were determined for the major degradants and their possible structures were proposed on the basis of the known reactivity.     

Synthesis and Characterization of Near‐Infrared Absorbing Water Soluble Squaraines and Study of their Photodynamic Effects in DLA Live Cells

Here, we report the synthesis, photophysical properties and photodynamic effects in DLA live cells of three water soluble squaraine dyes, viz. bisbenzothiazolium squaraine dyes SQMI and SQDI with iodine in one and both benzothiazolium units, respectively, and an unsymmetrical squaraine dye ASQI containing iodinated benzothiazolium and aniline substituents. The diiodinated SQDI showed an anomalous trend in both fluorescence and triplet quantum yields over the monoiodinated SQMI, with SQDI showing higher fluorescence and lower triplet quantum yields compared to SQMI. Nanosecond laser flash photolysis of SQDI and SQMI indicated the formation of triplet excited states with quantum yield of 0.19 and 0.26, respectively. On photoirradiation, both the SQDI and SQMI generate singlet oxygen and it was observed that both dyes undergoing oxidation reactions with the singlet oxygen generated. ASQI which exhibited a lower triplet quantum yield of 0.06 was, however, stable and did not react with the singlet oxygen generated. In vitro cytotoxicity studies of these dyes in DLA live cells were performed using Trypan blue dye exclusion method and it reflect an order of cytotoxicity of SQDI>SQMI>ASQI. Intracellular generation of the ROS was confirmed by dichlorofluorescein assay after the in vitro PDT.     

ZrCl4-Catalyzed C-O Bond to C-N Bond Formation: Synthesis of 1,2,3-Triazoles and Their Biological Evaluation

A simple and efficient protocol was developed for the synthesis of aryl azides directly from aryl carbinols using ZrCl₄ as a Lewis acid catalyst. The azides were converted to novel triazoles under click reaction conditions, which were evaluated for their antimicrobial activity against various strains.