Bioinspired, heterogeneous amino acid complexes for benign oxidation catalysis

Metalloenzymes catalyse the most fundamental reactions in organic chemistryfrom oxidation of hydrocarbons to complex C-C bond forming reactions with exceptionalselectivity. Mimicking the active site of a metalloenzyme by immobilising well-definedamino acids containing catalytically active transition metal centres based on transitionmetalson a robust inorganic framework, affords powerful catalysts that can be utilised inoxidation reactions. Porous aluminosilicates, mesoporous silicas and polymers offersuitable supports for single-site bio-derived catalysts. Dispersion of catalytically activecenters within porous solids with high surface area improves site-isolation which is essential incatalytic processes. These materials can be created from a range of methodologies and thedifferent strategies used for immobilisation can greatly affect the nature of the activecatalyst. The routes by which these catalysts are immobilised have given the potential toderivatize inorganic porous hosts and organic polymer structures with amino acids forcomplexation to metal centres. These bio-derivatized frameworks offer advantages overthe homogeneous counterparts in terms of easy separation, recover and recyclability and cancarry out selective oxidation reactions with great effectiveness.Herein, heterogenous bioinspired complexes of two amino acids; proline andvaline with a series of transition metals (Fe, Cu) were synthesised and immobilised withinzeolite cages, mesoporous silica MCM-41 and polystyrene. The preparation methodsallowed the synthesis of materials with varying loadings of immobilized active sites. The structuralinformation obtained by spectral and elemental analysis suggested tetrahedral geometry for ironcomplexes and distorted square planar geometry for copper complexes. Both amino acidscoordinated to metal ions through the nitrogen atom of amino group and oxygen atom ofcarboxylate group via dissociation of the acidic proton as bidentate N,O-donors.The resulting biomimetic complexes were employed as catalysts for oxidation ofcyclohexane, cyclohexene, benzyl alcohol and dimethyl sulfide, using molecular dioxygen (O2),tert-butyl hydroperoxide (TBHP) and acetylperoxyborate (APB) as oxidants. The observed trendsin catalytic activity showed that the metal loading and separation of the active sites played key rolein the selective oxidation reactions. By decreasing the loading of metal active centres, their spatialseparation increased which strongly enhanced the activity of catalysts. The decrease in metalactive site content resulted in significant increase in TON and TOF. The product selectivity wasdependent on the nature of oxidant, hydrophobicity/hydrophilicity of the support, loading of metalactive centres and the metal/substrate ratio

The Case For Culturally Affirming Systems Of Education: Exploring How Professional Development Impacts Culturally Relevant And Critical Literacy Teaching Practices

This case study based on a qualitative paradigm utilized grounded theory to analyze teacher interviews, focus groups and elite interviews focused on culturally relevant and critical literacy practices. This case study focuses on a small group of teachers and facilitators in a large urban school district in Minnesota. This dissertation focused on the impact of culturally relevant and critical literacy professional development on teachers\u27 mindsets and practices. The theoretical concepts that emerged from this case study are the importance of culturally affirming systems. The data collected from this project support the need for creating culturally affirming classrooms, diverse literature, and the opportunity for student voices to be heard. During and after professional development, teachers must have the opportunity for application, reflection, and time to dialogue with peers

Shortcomings of the Big Bounce derivation in Loop Quantum Cosmology

We give a prescription to define in Loop Quantum Gravity the electric field operator related to the scale factor of an homogeneous and isotropic cosmological space-time. This procedure allows to link the fundamental theory with its cosmological implementation. In view of the conjugate relation existing between holonomies and fluxes, the edge length and the area of surfaces in the fiducial metric satisfy a duality condition. As a consequence, the area operator has a discrete spectrum also in Loop Quantum Cosmology. This feature makes the super-Hamiltonian regularization an open issue of the whole formulation.Comment: 4 pages, accepted for publication in Phys. Rev. D as a Rapid Communicatio

Implementation of sunshine duration sensor

Peer Reviewe

Embryonic Origins of the Hematopoietic System: Hierarchies and Heterogeneity

The hierarchical framework of the adult blood system as we know it from current medical and hematology textbooks, displays a linear branching network of dividing and differentiated cells essential for the growth and maintenance of the healthy organism. This view of the hierarchy has evolved over the last 75 years. An amazing increase in cellular complexity has been realized; however, innovative single-cell technologies continue to uncover essential cell types and functions in animal models and the human blood system. The most potent cell of the hematopoietic hierarchy is the hematopoietic stem cell. Stem cells for adult tissues are the long-lived self-renewing cellular component, which ensure that differentiated tissue-specific cells are maintained and replaced through the entire adult lifespan. Although much blood research is focused on hematopoietic tissue homeostasis, replacement and regeneration during adult life, embryological studies have widened and enriched our understanding of additional developmental hierarchies and interacting cells of this life-sustaining tissue. Here, we review the current state of knowledge of the hierarchical organization and the vast heterogeneity of the hematopoietic system from embryonic to adult stages

Bianchi I model in terms of nonstandard loop quantum cosmology: Quantum dynamics

We analyze the quantum Bianchi I model in the setting of the nonstandard loop quantum cosmology. Elementary observables are used to quantize the volume operator. The spectrum of the volume operator is bounded from below and discrete. The discreteness may imply a foamy structure of spacetime at semiclassical level. The results are described in terms of a free parameter specifying loop geometry to be determined in astro-cosmo observations. An evolution of the quantum model is generated by the so-called true Hamiltonian, which enables an introduction of a time parameter valued in the set of all real numbers.Comment: 18 pages, version accepted for publication by Class. Quant. Gra

Effective dynamics of the closed loop quantum cosmology

In this paper we study dynamics of the closed FRW model with holonomy corrections coming from loop quantum cosmology. We consider models with a scalar field and cosmological constant. In case of the models with cosmological constant and free scalar field, dynamics reduce to 2D system and analysis of solutions simplify. If only free scalar field is included then universe undergoes non-singular oscillations. For the model with cosmological constant, different behaviours are obtained depending on the value of $\Lambda$. If the value of $\Lambda$ is sufficiently small, bouncing solutions with asymptotic de Sitter stages are obtained. However if the value of $\Lambda$ exceeds critical value $\Lambda_{\text{c}} =\frac{\sqrt{3}m^2_{\text{Pl}}}{2\pi\gamma^3} \simeq 21 m^2_{\text{Pl}}$ then solutions become oscillatory. Subsequently we study models with a massive scalar field. We find that this model possess generic inflationary attractors. In particular field, initially situated in the bottom of the potential, is driven up during the phase of quantum bounce. This subsequently leads to the phase of inflation. Finally we find that, comparing with the flat case, effects of curvature do not change qualitatively dynamics close to the phase of bounce. Possible effects of inverse volume corrections are also briefly discussed.Comment: 18 pages, 11 figure