title: Synthesis, crystal structure, computational analysis and biological properties of 1-(4-chlorobenzoyl)-3-[2-(2-{2-[3-(4-chlorobenzoyl)-thioureido]-ethoxy}ethoxy)ethyl]-thiourea and its Ni(II) and Cu(II) complexes

authors: Oyeka, Ebube Evaristus

subjects: thiourea

abstract: A new dianionic ligand, 1-(4-chlorobenzoyl)-3-[2-(2-{2-[3-(4-chlorobenzoyl)-thioureido]-ethoxy}ethoxy)ethyl]-thiourea(CBEDEA), and its Ni(II) and Cu(II) complexes have been synthesized. X-ray single crystal analysis of CBEDEA shows that the molecule crystallized in the triclinic crystal system, space group P-1, with two molecules per unit cell. The studied compounds were further characterized by FT-IR, UV-VIS,¹H NMR and mass spectroscopy. The metal complexes were isolated as four coordinated ML(M: Ni(II), Cu(II), L:CBEDEA) molecules. Computational studies on CBEDEA gave electrostatic potential energy isovalues which showed that there is a higher probability of metal coordination around the carbonyl and thione groups. Results of non-covalent interaction studies revealed the presence of significant amount of hydrogen bonding and other weak non-covalent interactions in the molecule. Docking calculations on CBEDEA and its Ni(II) and Cu(II) metal complexes revealed that they have affinity for beta-lactamase, a protein implicated in antibiotic drug-resistant mechanism. Complexation with the metal ion shrank the size of the molecule and enabled the metal complexes to fit more appropriately within the binding groove of the protein resulting in the improved affinity over CBEDEA ligand. Target-ligand binding interactions resulted from hydrophobicity and possibility of hydrogen bonding of the molecules. In vitro screening of the compounds against 17 bacteria and 4 yeasts confirmed their antimicrobial potency against more susceptible Gram-positive bacteria. Results of this study suggest that the metal complexes could be developed into novel antimicrobial compounds.

text: Synthesis, crystal structure, computational analysis and biological properties of 1-(4-chlorobenzoyl)-3-[2-(2-{2-[3-(4-chlorobenzoyl)-thioureido]-ethoxy}ethoxy)ethyl]-thiourea and its Ni(II) and Cu(II) complexes A new dianionic ligand, 1-(4-chlorobenzoyl)-3-[2-(2-{2-[3-(4-chlorobenzoyl)-thioureido]-ethoxy}ethoxy)ethyl]-thiourea(CBEDEA), and its Ni(II) and Cu(II) complexes have been synthesized. X-ray single crystal analysis of CBEDEA shows that the molecule crystallized in the triclinic crystal system, space group P-1, with two molecules per unit cell. The studied compounds were further characterized by FT-IR, UV-VIS,¹H NMR and mass spectroscopy. The metal complexes were isolated as four coordinated ML(M: Ni(II), Cu(II), L:CBEDEA) molecules. Computational studies on CBEDEA gave electrostatic potential energy isovalues which showed that there is a higher probability of metal coordination around the carbonyl and thione groups. Results of non-covalent interaction studies revealed the presence of significant amount of hydrogen bonding and other weak non-covalent interactions in the molecule. Docking calculations on CBEDEA and its Ni(II) and Cu(II) metal complexes revealed that they have affinity for beta-lactamase, a protein implicated in antibiotic drug-resistant mechanism. Complexation with the metal ion shrank the size of the molecule and enabled the metal complexes to fit more appropriately within the binding groove of the protein resulting in the improved affinity over CBEDEA ligand. Target-ligand binding interactions resulted from hydrophobicity and possibility of hydrogen bonding of the molecules. In vitro screening of the compounds against 17 bacteria and 4 yeasts confirmed their antimicrobial potency against more susceptible Gram-positive bacteria. Results of this study suggest that the metal complexes could be developed into novel antimicrobial compounds.

year: 2018

title: Ensembles of nested dichotomies with multiple subset evaluation

authors: Leathart, Tim

subjects: computer science

abstract: A system of nested dichotomies (NDs) is a method of decomposing a multiclass problem into a collection of binary problems. Such a system recursively applies binary splits to divide the set of classes into two subsets, and trains a binary classifier for each split. Many methods have been proposed to perform this split, each with various advantages and disadvantages. In this paper, we present a simple, general method for improving the predictive performance of NDs produced by any subset selection techniques that employ randomness to construct the subsets. We provide a theoretical expectation for performance improvements, as well as empirical results showing that our method improves the root mean squared error of NDs, regardless of whether they are employed as an individual model or in an ensemble setting.

text: Ensembles of nested dichotomies with multiple subset evaluation A system of nested dichotomies (NDs) is a method of decomposing a multiclass problem into a collection of binary problems. Such a system recursively applies binary splits to divide the set of classes into two subsets, and trains a binary classifier for each split. Many methods have been proposed to perform this split, each with various advantages and disadvantages. In this paper, we present a simple, general method for improving the predictive performance of NDs produced by any subset selection techniques that employ randomness to construct the subsets. We provide a theoretical expectation for performance improvements, as well as empirical results showing that our method improves the root mean squared error of NDs, regardless of whether they are employed as an individual model or in an ensemble setting.

year: 2019

title: The teaching and learning of te reo Māori in a higher education context: Intensive fast track immersion versus gradual progressive language exposure

authors: Nock, Sophie

subjects: grading of students

abstract: I report here on a comparison of the course grades of Bachelors degree students who are following two different pathways towards a major in te reo Māori - a traditional pathway in which language courses at different levels are spread over three or four years, and an intensive, fast-track, language immersion pathway in which courses in te reo Māori are concentrated into the first year of the degree programme. My findings are that, overall, in terms of course grades at level three, students following the intensive, fast-track, language-immersion pathway out-perform other students in te reo Māori course assessments. Thus, so far as course grades are concerned, many students appear to benefit from the fast track pathway. Whether course grades can be related to proficiency achievements and whether immediate gains are reflected in long-term gains is something that remains to be investigated.

text: The teaching and learning of te reo Māori in a higher education context: Intensive fast track immersion versus gradual progressive language exposure I report here on a comparison of the course grades of Bachelors degree students who are following two different pathways towards a major in te reo Māori - a traditional pathway in which language courses at different levels are spread over three or four years, and an intensive, fast-track, language immersion pathway in which courses in te reo Māori are concentrated into the first year of the degree programme. My findings are that, overall, in terms of course grades at level three, students following the intensive, fast-track, language-immersion pathway out-perform other students in te reo Māori course assessments. Thus, so far as course grades are concerned, many students appear to benefit from the fast track pathway. Whether course grades can be related to proficiency achievements and whether immediate gains are reflected in long-term gains is something that remains to be investigated.

year: 2006