1. Weathering induced morphological modification on the thermal diffusivity of natural pyrrhotite : a thermal lens studyMohanachandran Nair Sindhu Swapna, Vijayakumar Gokul, Vimal Raj, R. Manu Raj, S. N. Kumar, Sankaranarayana Iyer Sankararaman, 2021, izvirni znanstveni članek Opis: Natural pyrrhotites have gained significant attention due to
their interesting electronic, antimicrobial, and chemical
properties. The present work attempts to explore the
morphology-induced modifications in the thermal
characteristics of natural pyrrhotite due to ageing. The
morphological, elemental, structure, optical, and thermal
characterisations help in understanding the effect of
ageing. The effects of five years of ageing of the sample
are (i) Field Emission Scanning Electron Microscopic
analysis reveals a morphological transformation from flakes
to agglomerated powder, (ii) elemental analyses suggest
the ageing induced compositional modification (iii) the
Tauc plot analysis shows a bandgap energy modification
from 1.46 eV to 1.92 eV, (iv) X-ray Diffraction (XRD), Fourier
Transform Infrared, and X-ray photoelectron spectroscopic
studies affirm the formation of oxy-hydroxides (v) the XRD
data indicates an increase of dislocation density, and (vi)
Photoluminescence study shows a deep violet emission
evidenced through the CIE plot. The study by the thermal
lens technique shows a lowering of thermal diffusivity
study by 23%, due to the morphological modifications,
adsorbed/chemisorbed hydroxyl groups, and the formation
of secondary compounds due to oxidation and weathering.
The phonon boundary scattering, weathering induced
smaller grain size, reduced phonon mean free path, and
point defects also account for the lowering of the thermal
diffusivity value and thereby influencing its properties.
Ključne besede: pyrrhotite, thermal diffusivity, thermal lens, ageing, morphology
Objavljeno v RUNG: 30.06.2022; Ogledov: 1906; Prenosov: 7
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2. Metabolic dysregulation in vitamin E and carnitine shuttle energy mechanisms associate with human frailtyNicholas Rattray, Drupad Trivedi, Yun Xu, Tarani Chandola, Caroline Johnson, Alan Marshall, Krisztina Mekli, Zahra Rattray, Gindo Tampubolon, Bram Vanhoutte, Iain R. White, Frederick Wu, Neil Pendleton, James Nazroo, Royston Goodacre, 2019, izvirni znanstveni članek Opis: Global ageing poses a substantial economic burden on health and social care costs. Enabling a greater proportion of older people to stay healthy for longer is key to the future sustainability of health, social and economic policy. Frailty and associated decrease in resilience plays a central role in poor health in later life. In this study, we present a population level assessment of the metabolic phenotype associated with frailty. Analysis of serum from 1191 older individuals (aged between 56 and 84 years old) and subsequent longitudinal validation (on 786 subjects) was carried out using liquid and gas chromatography-mass spectrometry metabolomics and stratified across a frailty index designed to quantitatively summarize vulnerability. Through multivariate regression and network modelling and mROC modeling we identified 12 significant metabolites (including three tocotrienols and six carnitines) that differentiate frail and non-frail phenotypes. Our study provides evidence that the dysregulation of carnitine shuttle and vitamin E pathways play a role in the risk of frailty.
Ključne besede: metabolomics, frailty, ageing, LC-MS, serum
Objavljeno v RUNG: 08.11.2019; Ogledov: 4134; Prenosov: 92
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3. Comparison of ex vivo and in vitro human fibroblast ageing models.Federica Boraldi, Giulia Annovi, Roberta Tiozzo, Pascal Sommer, Daniela Quaglino, 2010, izvirni znanstveni članek Opis: Several studies have analyzed modulation of gene expression during physiological ageing with interesting, but often contradictory results, depending on the model used. In the present report we compare age-related metabolic and synthetic parameters in human dermal fibroblasts (HDF) isolated from young and old subjects (ex vivo ageing model) and cultured from early up to late cumulative population doublings (CPD) (in vitro ageing model) in order to distinguish changes induced in vivo by the aged environment and maintained in vitro, from those associated with cell senescence and progressive CPD. Results demonstrate that fibroblasts from aged donors, already at early CPD, exhibit an impaired redox balance, highlighting the importance of this parameter during ageing, even in the presence of standard environmental conditions, which are considered optimal for cell growth. By contrast, several proteins, as those related to heat shock response, or involved in endoplasmic reticulum and membrane trafficking, appeared differentially expressed only during in vitro ageing, suggesting that, at high CPD, the whole cell machinery becomes permanently altered. Finally, given the importance of the elastic component for a long-lasting connective tissue structural and functional compliance, this study focuses also on elastin and fibulin-5 synthesis and deposition, demonstrating a close relationship between fibulin-5 and ageing.
Ključne besede: Ageing
Fibroblast
Connective tissue
Oxidative stress
Protein expression
Elastin
Objavljeno v RUNG: 23.08.2019; Ogledov: 4094; Prenosov: 0
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