BIO-INSPIRED OPTIMAL FIN SHAPE AND ANGLE FOR MAXIMUM SURFBOARD STABILITY

Wave surfing is a multi-billion dollar industry involving both maneuverability and speed, yet little research has been done regarding optimal fins shape for these competing qualities. The purpose of this master\u27s thesis was to focus on a single fin setup in order to identify a bio-inspired fin shape that maximized lateral stability while minimizing drag forces, in order to increase surfing maneuverability. The computational fluid dynamic models NX and laboratory experiments performed in a water channel, with lift and drag being directly measured, were used to compare nine fins based on dorsal fins of real fish. To properly compare, fluid conditions were comparable between the CFD and lab experiments. It was found that the Short-finned Pilot Whale at an angle of attack of 10° had the greatest lift-to-drag ratios. Flow patterns around fins at a low angle of attack were smooth with negligible flow separation, while at any angle of attack greater than 25°, flow separation-induced drag forces became excessive

Non‐canonical binding of the Chaetomium thermophilum PolD4 N‐terminal PIP motif to PCNA involves Q‐pocket and compact 2‐fork plug interactions but no 310 helix

Funding: Carnegie Trust for the Universities of Scotland (Grant Number(s): 70668). Chinese Scholarship Council.DNA polymerase δ (Pol δ) is a key enzyme for the maintenance of genome integrity in eukaryotic cells, acting in concert with the sliding clamp processivity factor PCNA (proliferating cell nuclear antigen). Three of the four subunits of human Pol δ interact directly with the PCNA homotrimer via a short, conserved protein sequence known as a PCNA interacting protein (PIP) motif. Here, we describe the identification of a PIP motif located towards the N-terminus of the PolD4 subunit of Pol δ (equivalent to human p12) from the thermophilic filamentous fungus Chaetomium thermophilum and present the X-ray crystal structure of the corresponding peptide bound to PCNA at 2.45 Å. Like human p12, the fungal PolD4 PIP motif displays non-canonical binding to PCNA. However, the structures of the human p12 and fungal PolD4 PIP motif peptides are quite distinct, with the fungal PolD4 PIP motif lacking the 310 helical segment that characterises most previously identified PIP motifs. Instead, the fungal PolD4 PIP motif binds PCNA via a conserved glutamine that inserts into the Q-pocket on the surface of PCNA and with conserved leucine and phenylalanine sidechains forming a compact 2-fork plug that inserts into the hydrophobic pocket on PCNA. Despite the unusual binding mode of the fungal PolD4, isothermal calorimetry (ITC) measurements show that its affinity for PCNA is similar to that of its human orthologue. These observations add to a growing body of information on how diverse proteins interact with PCNA and highlight how binding modes can vary significantly between orthologous PCNA partner proteins.Publisher PDFPeer reviewe

Canonical binding of Chaetomium thermophilum DNA polymerase δ/ζ subunit PolD3 and flap endonuclease Fen1 to PCNA

Funding: This work was funded by the Carnegie Trust for the Universities of Scotland through a Research Incentive Grant (grant reference 70668) and by the School of Biology, University of St Andrews. Article processing charges (APCs) and Open Access charges were covered by the University of St Andrews.The sliding clamp PCNA is a key player in eukaryotic genome replication and stability, acting as a platform onto which components of the DNA replication and repair machinery are assembled. Interactions with PCNA are frequently mediated via a short protein sequence motif known as the PCNA-interacting protein (PIP) motif. Here we describe the binding mode of a PIP motif peptide derived from C-terminus of the PolD3 protein from the thermophilic ascomycete fungus C. thermophilum, a subunit of both DNA polymerase δ (Pol δ) and the translesion DNA synthesis polymerase Pol ζ, characterised by isothermal titration calorimetry (ITC) and protein X-ray crystallography. In sharp contrast to the previously determined structure of a Chaetomium thermophilum PolD4 peptide bound to PCNA, binding of the PolD3 peptide is strictly canonical, with the peptide adopting the anticipated 310 helix structure, conserved Gln441 inserting into the so-called Q-pocket on PCNA, and Ile444 and Phe448 forming a two-fork plug that inserts into the hydrophobic surface pocket on PCNA. The binding affinity for the canonical PolD3 PIP-PCNA interaction determined by ITC is broadly similar to that previously determined for the non-canonical PolD4 PIP-PCNA interaction. In addition, we report the structure of a PIP peptide derived from the C. thermophilum Fen1 nuclease bound to PCNA. Like PolD3, Fen1 PIP peptide binding to PCNA is achieved by strictly canonical means. Taken together, these results add to an increasing body of information on how different proteins bind to PCNA, both within and across species.Publisher PDFPeer reviewe

Occupational allergy to fruit flies (Drosophila melanogaster) in laboratory workers

OBJECTIVES: Drosophila melanogaster (the 'fruit fly') is commonly used in genetic research, but there is only one report of IgE-associated allergy in exposed workers. 4 newly identified cases prompted us to examine the extent of this problem in a university laboratory. Our aim in this study is to determine the prevalence and determinants of sensitisation to fruit flies in a population of exposed workers. METHODS: In a cross-sectional study, we surveyed 286 employees working in a department carrying out research involving D. melanogaster. Sensitisation was assessed by specific IgE measurement in serum and examined in relation to symptoms and to estimated exposure to fruit flies. RESULTS: The overall prevalence of specific sensitisation was 6% with a clear relationship to increasing frequency/intensity of exposure (p trend<0.001). Work-related eye/nose, chest or skin symptoms were reported by substantial proportions of participants but for most of these there was no evidence of specific sensitisation to fruit fly. The overall prevalence of any work-related symptoms and sensitisation was 2.4%, rising to 7.1% in those working in high exposure groups. CONCLUSIONS: We were able to demonstrate, for the first time, a clear exposure-response relationship between fruit fly exposure and specific sensitisation. Facilities housing fruit flies should carefully consider methods to reduce exposure levels in the workplace

Bis(μ-dithieno[3,2-b:2′,3′-d]thio­phene-2,6-dicarboxyl­ato-κ2 O 2:O 6)bis­[bis­(1,10-phenanthroline-κ2 N,N′)cobalt(II)] dimethyl­formamide disolvate

The asymmetric unit of the title compound, [Co2(C10H2O4S3)2(C12H8N2)4]·2C3H7NO, contains one half of the formula unit, with the rest generated by inversion. The cobalt ion sits in a slightly distorted octa­hedral environment and is ligated to four N atoms of two 1,10-phenanthroline molecules and to two O atoms of two dithieno[3,2-b:2′,3′-d]thio­phene-2,6-dicarb­oxy­l­ate anions. The anions act as bridges between the CoII centers

Observation of the nonlinear Hall effect under time reversal symmetric conditions

The electrical Hall effect is the production of a transverse voltage under an out-of-plane magnetic field. Historically, studies of the Hall effect have led to major breakthroughs including the discoveries of Berry curvature and the topological Chern invariants. In magnets, the internal magnetization allows Hall conductivity in the absence of external magnetic field. This anomalous Hall effect (AHE) has become an important tool to study quantum magnets. In nonmagnetic materials without external magnetic fields, the electrical Hall effect is rarely explored because of the constraint by time-reversal symmetry. However, strictly speaking, only the Hall effect in the linear response regime, i.e., the Hall voltage linearly proportional to the external electric field, identically vanishes due to time-reversal symmetry. The Hall effect in the nonlinear response regime, on the other hand, may not be subject to such symmetry constraints. Here, we report the observation of the nonlinear Hall effect (NLHE) in the electrical transport of the nonmagnetic 2D quantum material, bilayer WTe2. Specifically, flowing an electrical current in bilayer WTe2 leads to a nonlinear Hall voltage in the absence of magnetic field. The NLHE exhibits unusual properties sharply distinct from the AHE in metals: The NLHE shows a quadratic I-V characteristic; It strongly dominates the nonlinear longitudinal response, leading to a Hall angle of about 90 degree. We further show that the NLHE directly measures the "dipole moment" of the Berry curvature, which arises from layer-polarized Dirac fermions in bilayer WTe2. Our results demonstrate a new Hall effect and provide a powerful methodology to detect Berry curvature in a wide range of nonmagnetic quantum materials in an energy-resolved way