Analysis of the photoelastic effect in ionic crystals

An analysis of the photoelastic effect in ionic crystals has been presented within the framework of Clausius-Mossotti theory of the dielectric constant. The values of the strain derivative of the electronic dielectric constant have been calculated in alkali halides and MgO crystals by taking into account the variation of electronic polarizabilities with compressive stress. The results obtained are found closer to the experimental values. The photoelastic behaviour of MgO crystal is predicted to be of opposite nature to that of alkali halides, in conformity with the experimental observations.     

High-resolution infrared spectrum and rovibrational analysis of the ν3 fundamental of diazirine,H213CN2

The high-resolution infrared spectrum of ¹³C-diazirine was recorded using a high-information Fourier transform spectrometer with a resolution of 0.0054 cm^?1. The rovibrational structure of the ν₃ fundamental at 1458.1884 cm^?1, which is an A-type parallel band (¹³CH₂ deformation) was assigned and analyzed with extensive use of modern methods of spectrum simulation. The rovibrational assignment and the molecular constants determined for the excited vibrational level of this band are given.     

A comparative study of the properties of the liquid crystalline compounds 5O.5 and 5O.6 in solid, solution and thin film forms by laser Raman spectroscopy

Raman spectroscopic studies of the liquid crystalline compounds 5O.5 and 5O.6 revealed that the two aromatic rings in the core are in different environments with distorted electron cloud distributions, and the behaviour of each of these rings is independent of the other. Increased chain length results in the development of strain on the molecules. During the SmF-SmB phase transition there is a slight transfer of charge, along with an increase in the freedom of the individual molecules. Our experiments also reveal that the molecules are strained in the crystalline state and adopt some preferred orientations in free-standing films. There is also a tendency towards the elongation of the molecules along the C N linkage in solution for 5O.6. Raman spectra of 5O.6 in free-standing films have shown dramatic changes compared with the spectra recorded in the bulk.     

Author index to volume 43

The effect of an ultrasonic field on the stability of the amorphous alloy Fe₇₈Si₉B₁₁C₂ has been stu spectroscopy. It is found that the response of the alloy to the ultrasonic field depends upon the temperature at which it is exposed to ultrasonics. While at room temperature ultrasonic have no detectable effect on the stability of the alloy, at elevated temperature it markedly enhances the crystallization process. The possible cause of the observed effect has been discussed.     

The C1Πu-X1Σg+ fluorescence of Li2 excited by ultraviolet lines of an argon ion laser

The fluorescence spectra of ⁷Li₂ and ⁶Li₂ excited by an argon ion (3511 Å) laser are analyzed. No fluorescence was observed for 3514- or 3638-Å excitation or for ⁶Li⁷Li. For the C¹Π_u-X¹Σ_g⁺ electronic transition, the spectrum of ⁷Li₂ shows R and P doublets for 0 ≤ v″ ≤ 6 and that of ⁶Li₂ consists of Q lines for 0 ≤ v″ ≤ 11. Through the assignments of these lines (a) Hsu's (Ph.D. thesis, Fordham University, 1974, unpublished) molecular constants for C state have been verified, (b) the reliability of C- and X-state constants for ⁶Li₂ derived from those of ⁷Li₂ through mass-reduced scaling has been verified, and (c) the transition moment for the C-X transition of Li₂ has been shown by comparison of the observed and calculated intensities to be roughly independent of internuclear distance in the region near R_e for the C state.     

Insecticidal Evaluation and [4+2] Aza‐Diels‐Alder Synthesis of 3,7‐Diaryl‐6,7‐dihydro‐5H‐6‐substituted Thiazolo[3,2‐a]pyrimidin‐5‐ones Under Coupled Ultrasonic Irradiation and PTC

A series of 3,7‐diaryl‐6,7‐dihydro‐5H‐6‐substituted‐thiazolo[3,2‐a]pyrimidin‐5‐ones ( 3a , 3b , 3c , 3d , 3e , 3f , 3g , 3h , 3i , 3j ) were synthesized by the [4+2] cycloaddition reaction of 2‐arylideneamino‐4‐arylthiazoles (2a–j) with in situ generated monosubstituted ketenes under PTC conditions coupled with ultrasonication in good to excellent yields. All the synthesized compounds were characterized on the basis of their spectral (IR, PMR, and Mass) and analytical data. The synthesized compounds were also screened for their insecticidal activity against Helicoverpa armigera and some of them showed promising activity.     

Removal of unsaturated aliphatic carboxylic acid from aqueous effluent using quaternary amine

Maleic acid, present in the effluent from organic intermediate producing industries, is an industrially important raw material. Its use in manufacture of alkyd and polyester resins, surface coatings, lubricant additives, plasticizers, co-polymers and agricultural chemicals, makes it necessary to explore for best possible techniques to recover it from aqueous solutions. The present work investigates the recovery of maleic acid from aqueous solution at ambient temperature. N–Methyl–n, n–dioctyloctan–1–ammonium chloride, (commercially known as Aliquat 336) is used as an extractant with three different diluents, belonging to different chemical classes: an aromatic hydrocarbon, a ketone, and an acetate. The chemical extraction results are reported in the terms of distribution coefficient, degree of extraction, and loading ratios. The results were modeled by mass action equilibria model as well as differential evolution technique. Differential evolution algorithm has been prepared. The model and experimental observations were compared and fairly good agreement was observed.     

Biological potential of pyrimidine derivatives in a new era

Pyrimidine and its derivatives play a wide role in drug discovery processes and have considerable chemical significance and biological activities. Pyrimidines are the building blocks of many natural compounds such as vitamins, liposacharides, and antibiotics. Pyrimidine is used as parent substance for the synthesis of a wide variety of heterocyclic compounds and raw material for drug synthesis and is also crucial in the theoretical development of heterocyclic chemistry and in organic synthesis. Pyrimidine derivatives are vital in several biological activities, i.e. antihypertensive, anticancer, antimicrobial, anti-inflammatory, and antioxidant activity. This creates interest among researchers who have synthesized a variety of pyrimidine derivatives.