An efficient technique for finding the eigenvalues of fourth-order Sturm–Liouville problems

In this paper, we will develop a numerical technique for finding the eigenvalues of fourth-order non-singular Sturm–Liouville problems. We used the variational iteration methods as a basis for this technique. Numerical results and conclusions will be presented. Comparison results with others will be presented.     

trans-2,4,4,6,8,8-Hexamorpholino-2,6-bis­(n-propyl­amino)cyclo-2λ5,4λ5,6λ5,8λ5-tetraphosph­aza­tetraene

The title compound, C₃₀H₆₄N₁₂O₆P₄, consists of a centrosymmetric chair-shaped cyclic tetrameric phosphazene ring with six bulky morpholino and two n-propyl­amino side groups. The two n-propyl­amino side groups are in trans positions. The bulky substituents mainly determine the eight-membered-ring conformation. The endocyclic N—P—N angles around the P atoms having different substituents are not the same as the P—N—P angles of the macrocyclic ring.     

Investigation of the Thermal Properties of Alkali Metal Thorium Phosphates and Their Application for the Sorption of Uranyl Ion from Acidic Medium

Thermo physical properties of potassium, rubidium and cesium thorium phosphate compounds were investigated. All compounds were synthesized by conventional solid state method. Formation of orthorhombic AMThP₃O₁₀, tetragonal AM₂Th(PO₄)₂ and monoclinic AMTh₂(PO₄)₃; [AM=K, Rb and Cs] was confirmed using Powder X-ray diffraction (XRD) technique. Structural study of CsThP₃O₁₀ was carried out for the first time from Rietveld refinement of XRD data. Thermal stability of all compounds was established using Thermogravimetric analysis (TGA) technique. When heated at 1673 K for 30 h in air, all the compounds decompose to ThO₂. High temperature X-ray diffraction (HT-XRD) data of the compounds, synthesized during present study, were collected in an inert atmosphere from ambient to 973 K and their thermal expansion coefficients were calculated. These compounds show positive thermal expansion up to 973 K. Molar heat capacities for all phosphates were measured between 300–863 K using Differential Scanning Calorimeter. Alkali metal thorium phosphates, AMThP₃O₁₀ and AMTh₂(PO₄)₃, showed efficient uptake of uranyl ion from aqueous acidic medium predominantly following Langmuir isotherm and Webber Morris intra particle diffusion kinetics.     

Cinnamoylacetanilides and Their Metal Chelates

A new series of β-ketoanilides, in which the keto group attached to an olefinic linkage, have been synthesized by the reaction of acetoacetanilide with p-substituted benzaldehydes (4-methoxybenzaldehyde, 4-ethoxybenzaldehyde, 4-dimethylaminobenzaldehyde and 4-nitrobenzaldehyde) under specified conditions. The existence of these β-ketoanilides predominantly in the intramolecularly hydrogen bonded enol forms has been well demonstrated from their IR, ¹H NMR and mass spectral data. Details on the formation of [ML₂] complexes of these compounds with Ni(II), Cu(II) and Zn(II) and their nature of bonding were discussed on the basis of analytical, IR, ¹H NMR and mass spectral data.     

TRANSFER OF PYRIMIDINE DIMERS DURING BACTERIAL CONJUGATION

When male strains of Escherichia coli are irradiated with 254 nm ultraviolet (UV) light and mated with suitable females, DNA is transferred at almost the normal frequency (Howard-Flanders et al. , 1968). Cole (1971) observed that an episome damaged by UV irradiation of the male parent could be transferred to a recipient and restored to activity by administering photoreactivating light. He therefore deduced that UV lesions are transferred to the recipients during bacterial conjugation. The object of this Research Note is to report experiments providing direct evidence of the transfer of pyrimidine dimers -the main lesions of UV irradiation.     

Rapid Synthesis of Fused N‐Heterocycles by Transition‐Metal‐Free Electrophilic Amination of Arene C?H Bonds

We disclose an efficient and operationally simple protocol for the preparation of fused N‐heterocycles starting from readily available 2‐nitrobiaryls and PhMgBr under mild conditions. More than two dozen N‐heterocycles, including two bioactive natural products, have been synthesized using this method. A stepwise electrophilic aromatic cyclization mechanism was proposed by DFT calculations.     

Preparation of SrBi2Ta2O9 from Metal Alkoxides

SrBi₂Ta₂O₉ (SBT) has potential application in FERAM. Some problems in the sol-gel processing of SBT, such as the solubility of metal alkoxides, chemical modification with a chelating reagent and crystallization behavior of the gels, are investigated.The starting solutions were prepared with Sr(OC₄H₉)₂, Bi(OC₃H₇)₃, and Ta(OC₂H₅)₅. Ethoxyethanol and acetylacetone (ACAC) were used as solvent and chelating reagent, respectively. Ta- and Bi-alkoxide are chemically modified with ACAC, but Sr-alkoxide was not. The SBT solution was stabilized with ACAC for ca. 3 months. After hydrolysis of the SBT solution with the addition of ACAC, a monolithic and transparent gel was obtained at room temperature in 100 days. The X-ray diffraction peaks of SBT and very weak peaks of SrTa₂O₆ (ST) and SrBi₂O₄ (SB) were found after calcination at 700°C for both of the gels obtained with and without addition of ACAC. In contrast, the stronger peaks of ST and SB were observed for the powder mixture of SrCO₃, Bi₂O₃, and Ta₂O₅ after calcination at 800°C. These results show the better homogeneity of the gels.     

Design and characterization of Bodipy derivatives for bulk heterojunction solar cells

Two electron rich Bodipy dyes with strong absorptivities in the visible region were designed and synthesized as potential electron donors in bulk heterojunction photovoltaic constructs. Overall efficiency is above 1%, with impressive responsiveness at both UV and near-IR ends of the visible spectrum. Computational studies reveal an unexpected effect of meso-substituents on the electron transfer efficiency.