Synthesis of novel Iron(III) chelators based on triaza macrocycle backbone and 1-hydroxy-2(H)-pyridin-2-one coordinating groups and their evaluation as antimicrobial agents

AbstractSeveral novel chelators based on 1-hydroxy-2(1H)-pyridinone coordinating groups decorating a triaza macrocyclic backbone scaffold were synthesised as potential powerful Fe3+ chelators capable of competing with bacterial siderophores. In particular, a novel chloromethyl derivative of 1-hydroxy-2(1H)-pyridinone exploiting a novel protective group for this family of coordinating groups was developed. These are the first examples of hexadentate chelators based on 1-hydroxy-2(1H)-pyridinone to be shown to have a biostatic activity against a range of pathogenic bacteria. Their efficacy as biostatic agents was assessed revealing that minor variations in the structure of the chelator can affect efficacy profoundly. The minimal inhibitory concentrations of our best tested novel chelators approach or are comparable to those for 1,4,7-tris(3-hydroxy-6-methyl-2-pyridylmethyl)-1,4,7-triazacyclononane, the best Fe3+ chelator known to date. The retarding effect these chelators have on microbial growth suggests that they could have a potential application as a co-active alongside antibiotics in the fight against infections

Combustion synthesis of ceramic and metal-matrix composites

Combustion synthesis or self-propagating high temperature synthesis (SHS) is effected by heating a reactant mixture, to above the ignition temperature (Tig) whereupon an exothermic reaction is initiated which produces a maximum or combustion temperature, Tc. These SHS reactions are being used to produce ceramics, intermetallics, and composite materials. One of the major limitations of this process is that relatively high levels of porosity, e.g., 50 percent, remain in the product. Conducting these SHS reactions under adiabatic conditions, the maximum temperature is the adiabatic temperature, Tad, and delta H (Tad) = 0, Tad = Tc. If the reactants or products go through a phase change, the latent heat of transformation needs to be taken into account

Caring, male African Americans, and mathematics teaching and learning

In this paper, the authors report on a qualitative study that explored the influence a “successful” African American male mathematics teacher had on three African American male high school students’ perceptions of teacher care. This critical ethnography study was guided by an intersection of an eclectic array of theoretical traditions, including care theory, critical race theory, and culturally relevant pedagogy. The study employed ethnographic methods during data collection; data analysis identified six overarching themes that the participants used to describe teacher care. Findings suggest that teachers should reconsider the ways they care for African American male students and that a caring teacher–student relationship has a positive influence on African American male students’ descriptions and perceptions of teacher care

Prestação de Contas dos Recursos: Fazer Cumprir as Responsabilidades do Estado de Fornecer Recursos Adequados e Equitativos para ser Efetivamente Usados para Brindar a Todos os Alunos uma Educação de Qualidade

Darling-Hammond, Wilhoit, and Pittenger (2014) addressed the need for states to align their accountability systems with new college- and career-ready learning standards. The authors recommended a new accountability paradigm that focuses on 1) meaningful learning, enabled by 2) professionally skilled and committed educators, and supported by 3) adequate and appropriate resources. This paper explicates the provision of adequate and appropriate resources, the third of these three pillars of a comprehensive approach to accountability. Adequate resources, effectively used, are prerequisites to building the capacity of schools to deliver the two other pillars, professionally skilled and committed educators and meaningful learning. Also, the effective use of public school funding is an oft-ignored but crucial step toward ensuring equal educational opportunity for all students.En el número del el 18 de agosto 2014  esta publicación, los autores Linda Darling-Hammond, Gene Wilhoit, y Linda Pittenger abordaron la necesidad de que los estados alineen sus sistemas de responsabilidad educativa con un nuevo paradigma que prepare a los estudiantes para que sean exitosos en la universidad y carreras profesionaes. Los autores recomendaron un nuevo paradigma de la rendición de cuentas que se centrase en 1) el aprendizaje significativo, habilitado por 2) educadores profesionalmente cualificados y comprometidos, y con el apoyo de 3) los recursos adecuados y apropiados (Darling-Hammond, Wilhoit, y Pittenger, 2014). En este trabajo se explicita la provisión de los recursos adecuados y apropiados, el tercero de estos tres pilares de un enfoque integral para la rendición de cuentas. Recursos suficientes que se usen con eficacia, son requisitos previos para viabilizar la capacidad de las escuelas para sustentar los otros dos pilares, educadores profesionalmente cualificados y comprometidos y lso aprendizajes significativos. Además, la financiación efectiva de la de escuelas públicas es un paso a menudo ignorado, pero crucial para garantizar la igualdad de oportunidades educativas para todos los estudiantes.No número de 18 agosto de 2014 desta publicação, os autores Linda Darling-Hammond, Gene Wilhoit, e Linda Pittenger abordaram a necessidade de que os Estados alinhem seus sistemas de ensino com um novo paradigma de responsabilidade educacional que prepare os alunos para ser bem sucedidos nos estudos universitários e as carreiras profesionais. Os autores recomendam um novo paradigma de responsabilidade educativa baseados em 1) a aprendizagem significativa, ativado por 2) educadores profissionalmente qualificados e comprometidos, e com o apoio de 3) recursos adequados e apropriados (Darling-Hammond, Wilhoit, e Pittenger, 2014). Neste trabalho, o fornecimento de recursos adequados e apropriados são explícitas, o terceiro dos três pilares de uma abordagem abrangente para a prestação de contas. Recursos suficientes utilizados de forma eficaz, são pré-requisitos para viabilizar a capacidade das escolas para sustentar os outros dois pilares, educadores profissionalmente qualificados e comprometidos e aprendizagem significativa. Além disso, o financiamento eficaz das escolas públicas é um passo muitas vezes esquecido, mas crucial para garantir a igualdade de oportunidades educacionais para todos os alunos

Haplotype analysis of common variants in the BRCA1 gene and risk of sporadic breast cancer

INTRODUCTION: Truncation mutations in the BRCA1 gene cause a substantial increase in risk of breast cancer. However, these mutations are rare in the general population and account for little of the overall incidence of sporadic breast cancer. METHOD: We used whole-gene resequencing data to select haplotype tagging single nucleotide polymorphisms, and examined the association between common haplotypes of BRCA1 and breast cancer in a nested case-control study in the Nurses' Health Study (1323 cases and 1910 controls). RESULTS: One haplotype was associated with a slight increase in risk (odds ratio 1.18, 95% confidence interval 1.02–1.37). A significant interaction (P = 0.05) was seen between this haplotype, positive family history of breast cancer, and breast cancer risk. Although not statistically significant, similar interactions were observed with age at diagnosis and with menopausal status at diagnosis; risk tended to be higher among younger, pre-menopausal women. CONCLUSIONS: We have described a haplotype in the BRCA1 gene that was associated with an approximately 20% increase in risk of sporadic breast cancer in the general population. However, the functional variant(s) responsible for the association are unclear

A polymorphism in the 3' untranslated region of the gene encoding prostaglandin endoperoxide synthase 2 is not associated with an increase in breast cancer risk: a nested case-control study

INTRODUCTION: Prostaglandins are integral components in the cellular response to inflammation, promoting cellular proliferation and angiogenesis. The enzyme responsible for the conversion of arachidonic acid to prostaglandins in response to inflammation is prostaglandin endoperoxide synthase 2/cyclo-oxygenase 2 (PTGS2/COX2). Polymorphisms in the PTGS2 gene have been associated with various diseases, including inflammatory bowel disease and cancer of the lung, colorectum, and breast. METHODS: We genotyped the five most common polymorphisms (rs20417, rs5277, rs20432, rs5275, and rs4648298) in the Nurses' Health Study (1,270 cases, 1,762 controls) to test the hypothesis that polymorphisms in PTGS2 are associated with breast cancer risk, using logistic regression analyses. The Nurses' Health Study 2 (317 cases, 634 controls) and Harvard Women's Health Study (702 cases, 703 controls) were used to further examine putative associations. RESULTS: The rs5275 polymorphism in the 3' untranslated region of the PTGS2 gene was associated with a decrease in breast cancer risk. We therefore genotyped this single-nucleotide polymorphism in the Nurses' Health Study 2 and Harvard Women's Health Study. Similar results were observed in these subsequent analyses, with no statistically significant heterogeneity in risk estimates between studies. In pooled analyses, women homozygous for the T allele at rs5275 had a 20% lower risk of breast cancer than those homozygous for the C allele (odds ratio 0.80, 95% confidence interval 0.66 to 0.97). CONCLUSION: Although this polymorphism may be associated with a decrease in breast cancer risk among Caucasian women, we provide strong evidence that it is not associated with an increased risk of breast cancer

Minimum cost - minimum time : a paper on the management and effectiveness of construction projects under International development programmes

"Part II of a final report to the International Development Research Center on completion of a Research Associate Grant, 1974-75

Ground operation of robotics on Space Station Freedom

This paper reflects work carried out on Ground Operated Telerobotics (GOT) in 1992 to refine further the ideas, procedures, and technologies needed to test the procedures in a high latency environment, and to integrate GOT into Space Station Freedom operations. Space Station Freedom (SSF) will be in operation for 30 years, and will depend on robots to carry out a significant part of the assembly, maintenance, and utilization workload. Current plans call for on-orbit robotics to be operated by on-board crew members. This approach implies that on-orbit robotics operations use up considerable crew time, and that these operations cannot be carried out when SSF is unmanned. GOT will allow robotic operations to be operated from the ground, with on-orbit crew interventions only when absolutely required. The paper reviews how GOT would be implemented, how GOT operations would be planned and supported, and reviews GOT issues, critical success factors, and benefits