Ab initio calculations of Co shielding in model complexes

Recent ab initio calculations of cobalt NMR shielding show that DFT-GIAO calculations using hybrid functionals are found to reproduce experimental values well. This method is used top calculate the vatriation of the cobalt NMR shielding tensor of square pyramidal nitrosyl complexres with respect to the CoNO geometry and to differing basal ligands. The isotropic shielding is shown to have a large negative derivative with respect to CoX distance where X is a ligating atom; the derivative with respect to NO distance is smaller but still significant. The zz component where z is along the CoN(NO) bond is more sensitive to the basal ligands but the other two principal components are sensitive to the CoNO geometry

First-principles study of the mixed oxide alpha-FeCrO3

We have investigated the electronic and magnetic properties of the mixed oxide alpha-FeCrO3 and compared it to the parent oxides alpha-Fe2O3 and alpha-Cr2O3. DFT B3LYP calculations with the non-local Hartree-Fock exchange contribution reduced from 20% to 10% were found to reproduce the band gaps of alpha-Fe2O3 and alpha-Cr2O3 remarkably well. Optimised cell constants also agreed very well with experimental values. Thus this method was used to study alpha-FeCrO3. alpha-FeCrO3 is predicted to be a charge-transfer insulator with O(2p) and Cr(3d) predominating in the upper edge of the valence band and Fe(3d) in the lower edge of the conduction band. The direct band gap of alpha-FeCrO3 is predicted to be close in value to that of alpha-Fe2O3. For ordered alpha-FeCrO3 the lowest energy is found for chromium ions occupying the sites related by the c glide plane. The antiferromagnetic ground state of this oxide is found to be that with magnetic ordering as in alpha-Fe2O3

Lipid Metabolism

Perilipin 2, also known as Adipose differentiation-relation protein or PLIN2, is a lipid droplet-binding protein present in almost every tissue. The absence of PLIN2 upregulates hepatic very low-density lipoprotein secretion, relieves hepatosteatosis, and improves whole body insulin resistance in mice. Despite of the importance in mediating lipid metabolism, the regulation of PLIN2 itself remains largely unknown. Previous reports have shown that X-box binding protein 1 (XBP1) is an important regulator of lipogenesis. XBP1 is a transcription factor that recognizes and binds to a consensus sequence, 5’-TGACGTGG-3’. Interestingly, when we looked through the promoter region of mouse Plin2 gene, we found that the consensus sequence is present in the Plin2 promoter. Therefore, we hypothesize that XBP1 might directly bind to Plin2 promoter and regulate the Plin2 expression. To test our hypothesis, we will perform the luciferase assay to examine whether the Plin2 promoter activity is regulated by XBP1. We first designed forward and reverse PCR primers, which include BglII and BamHI restriction enzyme sites respectively, to amplify the Plin2 promoter region (from -1100 to +40). We performed PCR and cloned the Plin2 promoter to a TA vector. The TA vector was then sequenced to exclude any point mutations. After sequencing, we sub cloned the Plin2 promoter into a vector containing a luciferase reporter. In the future, we will transfect 293T, a human embryonic kidney cell line, with the Plin2 promoter-luciferase vector we generated. We will compare the Plin2 promoter activity by measuring the luminescence in the presence or absence of XBP1

New insights on repellent recognition by <i>Anopheles gambiae</i> odorant-binding protein 1

It is generally recognized that insect odorant binding proteins (OBPs) mediate the solubilisation and transport of hydrophobic odorant molecules and contribute to the sensitivity of the insect olfactory system. However, the exact mechanism by which OBPs deliver odorants to olfactory receptors and their role, if any, as selectivity filters for specific odorants, are still a matter of debate. In the case of Anopheles gambiae recent studies indicate that ligand discrimination is effected through the formation of heterodimers such as AgamOBP1 and AgamOBP4 (odorant binding proteins 1 and 4 from Anopheles gambiae). Furthermore, AgamOBPs have been reported to be promiscuous in binding more than one ligand simultaneously and repellents such as DEET (N,N-diethyl-3-toluamide) and 6-MH (6-methyl-5-hepten-2-one) interact directly with mosquito OBPs and/or compete for the binding of attractive odorants thus disrupting OBP heterodimerisation. In this paper, we propose mechanisms of action of DEET and 6-MH. We also predict that ligand binding can occur in several locations of AgamOBP1 with partial occupancies and propose structural features appropriate for repellent pharmacophores

Galaxy destruction and diffuse light in clusters

Deep images of the Centaurus and Coma clusters reveal two spectacular arcs of diffuse light that stretch for over 100 kpc, yet are just a few kpc wide. At a surface brightness of m_b \sim 27-28th arcsec^-2, the Centaurus arc is the most striking example known of structure in the diffuse light component of a rich galaxy cluster. We use numerical simulations to show that the Centaurus feature can be reproduced by the tidal debris of a spiral galaxy that has been tidally disrupted by the gravitational potential of NGC 4709. The surface brightness and narrow dimensions of the diffuse light suggest that the disk was co-rotating with its orbital path past pericentre. Features this prominent in clusters will be relatively rare, although at fainter surface brightness levels the diffuse light will reveal a wealth of structure. Deeper imaging surveys may be able to trace this feature for several times its presently observed extent and somewhere along the tidal debris, a fraction of the original stellar component of the disk will remain bound, but transformed into a faint spheroidal galaxy. It should be possible to confirm the galactic origin of the Centaurus arc by observing planetary nebulae along its length with redshifts close to that of NGC 4709.Comment: Replaced with version accepted by MNRAS (Dec. 1999): Added missing reference (to pg. 4 & reference list). Section 3 shortened; removed three figures. Now 8 pages long, with 8 figures. Low resolution images included, high resolution version available at http://star-www.dur.ac.uk:80/~calcaneo/cenarc.htm

Elementary Pre-Service Teachers’ Reflections on Integrated Science/Engineering Design Lessons: Attending, Analyzing, and Responding to Students’ Thinking

The Next Generation Science Standards (NGSS) and recent efforts in STEM education have highlighted a multi-disciplinary vision of teachers’ integrating science education and engineering design problem-solving for student learning and critical thinking development. However, elementary pre-service teachers (PSTs) typically are unfamiliar with engineering design. Since research is limited on elementary PSTs’ ability to notice student thinking for engineering problem-solving, the purpose of this exploratory study was to identify patterns in PSTs’ written reflections from their fourth-grade practicum teaching experience with an integrated science/engineering STEM unit. We adapted Barnhart and van Es’s (2015) teacher noticing coding scheme to examine PSTs’ level of focus (low, basic, or strong) in their professional noticing (attending, analyzing, and responding) of students’ thinking and engineering disciplinary core ideas. The results indicated that PSTs’ reflections focused more on attending to students’ engineering ideas than on analyzing and responding to students’ thinking. For NGSS engineering disciplinary core ideas, the PSTs reflected the least on defining and delimiting the engineering problem, focusing more on students’ idea generation to solve the problem and students’ thinking to optimize their design with less emphasis on evaluating design ideas. These findings suggest possible areas of emphasis for teacher educators to prepare elementary PSTs in developing their ability to attend to, analyze, and respond to students’ engineering thinking when integrating engineering design with science education

Elementary Pre-Service Teachers’ Reflections on Integrated Science/Engineering Design Lessons: Attending, Analyzing, and Responding to Students’ Thinking

The Next Generation Science Standards (NGSS) and recent efforts in STEM education have highlighted a multi-disciplinary vision of teachers’ integrating science education and engineering design problem-solving for student learning and critical thinking development. However, elementary pre-service teachers (PSTs) typically are unfamiliar with engineering design. Since research is limited on elementary PSTs’ ability to notice student thinking for engineering problem-solving, the purpose of this exploratory study was to identify patterns in PSTs’ written reflections from their fourth-grade practicum teaching experience with an integrated science/engineering STEM unit. We adapted Barnhart and van Es’s (2015) teacher noticing coding scheme to examine PSTs’ level of focus (low, basic, or strong) in their professional noticing (attending, analyzing, and responding) of students’ thinking and engineering disciplinary core ideas. The results indicated that PSTs’ reflections focused more on attending to students’ engineering ideas than on analyzing and responding to students’ thinking. For NGSS engineering disciplinary core ideas, the PSTs reflected the least on defining and delimiting the engineering problem, focusing more on students’ idea generation to solve the problem and students’ thinking to optimize their design with less emphasis on evaluating design ideas. These findings suggest possible areas of emphasis for teacher educators to prepare elementary PSTs in developing their ability to attend to, analyze, and respond to students’ engineering thinking when integrating engineering design with science education