The new Schiff bases derived from pyromellitic dianhydride were synthesized by several steps reaction . A symmetrical diamic acide [I ]a-c were synthesized by the reaction of pyromellitic dianhydride with some aromatic amines (containing electron withdrawing , repulling groups ) in dry acetone. In the second step the diacids were converted to their corresponding diimide [II ]a-c using acetic anhydride and sodium acetate system as a dehydrating agent, via the intra molecular cyclization steps of amic acids. The third step was to synthesize the hydrazone derivatives from the reaction of diimides , with 80 % hydrazine hydrate at (50-60)CËš . These hydrazone derivatives were allowed to react with several aromatic aldehydes to form new Schiff bases via step four at a temperature near by (50)CËš . All the novel compounds and their structures have been ascertained by their melting points , mixed melting points , C .H . N analysis , FTIR spectroscopy and HNMR for some of them .
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Background: 37% phosphoric acid (PA) is the traditional enamel etching technique prior to bracket adhesion, yet it has been implicated in numerous enamel injuries. The purpose of the current study was to create a calcium phosphate (CaP) etching paste in a simplified capsule formula that can underpin clinically adequate bracket bond strength without jeopardizing the integrity of enamel upon the debracketing procedure. Materials and Methods: micro-sized hydroxyapatite (HA) powder was mixed with 40% PA solution to prepare experimental acidic CaP paste. Sixty human premolars were assigned into two groups of 30 each. Enamel conditioning was accomplished using 37% PA-gel for control group and CaP paste for e
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FH Ghanim, Journal of Global Pharma Technology, 2018
Synthesis, Characterization And Biological Evaluation of Schiff Base And Ligand Metal Complexes of Some Drug Substances
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A new tridentate ligand has been synthesized derived from phenyl(pyridin-3-yl)methanone. Three coordinated metal complexes were prepared by complexation of the new ligand with Cu(II), Ni(II) and Zn(II) metal salts. The new Schiff base “benzyl -2-[phenyl(pyridin-3-yl)methylidene]hydrazinecarbodithioate” and the new metal complexes were characterized using various physico-chemical and spectroscopic techniques. From the analysis results, the expected structure to the metal complexes are octahedral in geometry for Cu(II) complex, square planner for Ni(II) and tetrahedral for Zn(II) complex. The new compounds are expected to show strong bioactivity against bacteria and cancer cells.
This article focuses on identity construction and social structures within the Sāmoan community as represented in Sia Figiel’s novel Where We Once Belonged. I argue that however the post/colonial Sāmoan identity is hybridized, the essence of the individual is still connected to Fa’a Sāmoa-the Sāmoan traditions and ways. However rapid are the colonial vicissitudes, the Sāmoan literature and lifestyle are developed to be a resistance platform. This resistance platform is dedicated not only to expose the colonial impact but also to assist the social and political reconstruction of post/colonial Samoa. To this end, this article studies identity construction, and the challenges that women face within Sāmoan social structures.