2,826 research outputs found
Urban regime theory in critical perspective : a comparative study of public-private partnerships in UK local governance.
SIGLEAvailable from British Library Document Supply Centre-DSC:DXN037027 / BLDSC - British Library Document Supply CentreGBUnited Kingdo
The changing landscape of membrane protein structural biology through developments in electron microscopy
Membrane proteins are ubiquitous in biology and are key targets for therapeutic development. Despite this, our structural understanding has lagged behind that of their soluble counterparts. This review provides an overview of this important field, focusing in particular on the recent resurgence of electron microscopy (EM) and the increasing role it has to play in the structural studies of membrane proteins, and illustrating this through several case studies. In addition we examine some of the challenges remaining in structural determination, and what steps are underway to enhance our knowledge of these enigmatic proteins
Synthesis and characterisation of halide, separated ion pair, and hydride cyclopentadienyl iron bis(diphenylphosphino)ethane derivatives
Treatment of anhydrous FeXâ (X = Cl, Br, I) with one equivalent of bis(diphenylphosphino)ethane (dppe) in refluxing THF afforded analytically pure white (X = Cl), light green (X = Br), and yellow (X = I) [FeXâ(dppe)]n (X = Cl, I; Br, II; I, III). Complexes IâIII are excellent synthons from which to prepare a range of cyclopentadienyl derivatives. Specifically, treatment of IâIII with alkali metal salts of Câ
Hâ
(Cp, series 1), Câ
Meâ
(Cp*, series 2), Câ
HâSiMeâ (Cpâ˛, series 3), Câ
Hâ(SiMeâ)â (Cpâ˛â˛, series 4), and Câ
Hâ(But)â (Cptt, series 5) afforded [Fe(Cpâ )(Cl)(dppe)] 1Clâ5Cl, [Fe(Cpâ )(Br)(dppe)] 1Brâ5Br, and [Fe(Cpâ )(I)(dppe)] 1Iâ5I (Cpâ = Cp, Cp*, Cpâ˛, Cpâ˛â˛, or Cptt). Dissolution of 1Iâ5I in acetonitrile, or treatment of 1Clâ5Cl with MeâSiI in acetonitrile (no halide exchange reactions were observed in other solvents) afforded the separated ion pair complexes [Fe(Cpâ )(NCMe)(dppe)][I] 1SIPâ5SIP. Attempts to reduce 1Clâ5Cl, 1Brâ5Br, and 1Iâ5I with a variety of reductants (Li-Cs, KCâ, Na/Hg) were unsuccessful. Treatment of 1Clâ5Cl with LiAlHâ gave the hydride derivatives [Fe(Cpâ )(H)(dppe)] 1Hâ5H. This report provides a systematic account of reliable methods of preparing these complexes which may find utility in molecular wire and metalâmetal bond chemistries. The complexes reported herein have been characterised by X-ray diffraction, NMR, IR, UV/Vis, and MĂśssbauer spectroscopies, cyclic voltammetry, density functional theory calculations, and elemental analyses, which have enabled us to elucidate the electronic structure of the complexes and probe the variation of iron redox properties as a function of varying the cyclopentadienyl or halide ligand
Spectroscopic profiling variations in extracellular vesicle biochemistry in a model of myogenesis.
Extracellular vesicles (EVs) hold value as accessible biomarkers for understanding cellular differentiation and related pathologies. Herein, EV biomarkers in models of skeletal muscle dormancy and differentiation have been comparatively profiled using Raman spectroscopy (RS). Significant variations in the biochemical fingerprint of EVs were detected, with an elevation in peaks associated with lipid and protein signatures during early myogenic differentiation (day 2). Principal component analysis revealed a clear separation between the spectra of EVs derived from myogenic and senescent cell types, with non-overlapping interquartile ranges and population median. Observations aligned with nanoparticle tracking data, highlighting a significant early reduction in EV concentration in senescent myoblast cultures as well as notable variations in EV morphology and diameter. As differentiation progressed physical and biochemical differences in the properties of EVs became less pronounced. This study demonstrates the applicability of RS as a high-resolution analytical method for profiling biochemical changes in EVs during early myogenesis
Geomorphology of Ulu Peninsula, James Ross Island, Antarctica
This study presents a 1:25,000 geomorphological map of the northern sector of Ulu Peninsula, James Ross Island, Antarctic Peninsula. The map covers an area of c. 250â
km2, and documents the landforms and surficial sediments of one of the largest ice-free areas in Antarctica, based on remote sensing and field-based mapping. The large-scale landscape features are determined by the underlying Cretaceous sedimentary and Neogene volcanic geology, which has been sculpted by overlying ice masses during glacial periods. Paraglacial and periglacial features are superimposed upon remnant glacial features, reflecting the post-glacial evolution of the landscape. The study area can be broadly separated into three geomorphological sectors, according to the dominant contemporary Earth-surface processes; specifically, a glacierised southern sector, a paraglacial-dominated eastern sector, and a periglacial-dominated central/northern sector. This map provides a basis for further interdisciplinary research, and insight into the potential future landscape evolution of other parts of the Antarctic Peninsula as the climate warms
Slow magnetic relaxation in Fe(ii) m-terphenyl complexes
Two-coordinate transition metal complexes are exciting candidates for single-molecule magnets (SMMs) because their highly axial coordination environments lead to sizeable magnetic anisotropy. We report a series of five structurally related two-coordinate Fe(II) m-terphenyl complexes (4-R-2,6-Xyl2C6H2)2Fe [R = tBu (1), SiMe3 (2), H (3), Cl (4), CF3 (5)] where, by changing the functionalisation of the para-substituent (R), we alter their magnetic function. All five complexes are field-induced single-molecule magnets, with relaxation rates that are well-described by a combination of direct and Raman mechanisms. By using more electron donating R groups we were able to slow the rate of magnetic relaxation. Our ab initio calculations predict a large crystal field splitting (>850 cmâ1) and sizeable zero-field splitting parameters (ca. â60 cmâ1, |E| < 0.2 cmâ1) for 1â5. These favourable magnetic properties suggest that m-terphenyl ligands have untapped potential as chemically versatile ligands able to impose highly axial crystal fields
From cook to chef: Facilitating the transition from recipe-driven to open-ended research-based undergraduate chemistry lab activities
This paper describes the development of mini-research projects in the third year practical chemistry course at the University of Nottingham for the MSci(Hons) Chemistry degree. The aim of these developments is to bridge the gap between ârecipe-styleâ experiments in the first and second year courses and research projects undertaken in the fourth year or in industry. There is much evidence that, having been given this opportunity to plan and design their own experiment, students exhibit higher-order cognitive skills, which can lead to a more valuable learning experience
Risk algorithm using serial biomarker measurements doubles the number of screen-detected cancers compared with a single-threshold rule in the United Kingdom collaborative trial of ovarian cancer screening
PURPOSE: Cancer screening strategies have commonly adopted single-biomarker thresholds to identify abnormality. We investigated the impact of serial biomarker change interpreted through a risk algorithm on cancer detection rates.
PATIENTS AND METHODS: In the United Kingdom Collaborative Trial of Ovarian Cancer Screening, 46,237 women, age 50 years or older underwent incidence screening by using the multimodal strategy (MMS) in which annual serum cancer antigen 125 (CA-125) was interpreted with the risk of ovarian cancer algorithm (ROCA). Women were triaged by the ROCA: normal risk, returned to annual screening; intermediate risk, repeat CA-125; and elevated risk, repeat CA-125 and transvaginal ultrasound. Women with persistently increased risk were clinically evaluated. All participants were followed through national cancer and/or death registries. Performance characteristics of a single-threshold rule and the ROCA were compared by using receiver operating characteristic curves.
RESULTS: After 296,911 women-years of annual incidence screening, 640 women underwent surgery. Of those, 133 had primary invasive epithelial ovarian or tubal cancers (iEOCs). In all, 22 interval iEOCs occurred within 1 year of screening, of which one was detected by ROCA but was managed conservatively after clinical assessment. The sensitivity and specificity of MMS for detection of iEOCs were 85.8% (95% CI, 79.3% to 90.9%) and 99.8% (95% CI, 99.8% to 99.8%), respectively, with 4.8 surgeries per iEOC. ROCA alone detected 87.1% (135 of 155) of the iEOCs. Using fixed CA-125 cutoffs at the last annual screen of more than 35, more than 30, and more than 22 U/mL would have identified 41.3% (64 of 155), 48.4% (75 of 155), and 66.5% (103 of 155), respectively. The area under the curve for ROCA (0.915) was significantly (P = .0027) higher than that for a single-threshold rule (0.869).
CONCLUSION: Screening by using ROCA doubled the number of screen-detected iEOCs compared with a fixed cutoff. In the context of cancer screening, reliance on predefined single-threshold rules may result in biomarkers of value being discarded
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