81. A microbiome and metabolomic signature of phases of cutaneous healing identified by profiling sequential acute wounds of human skin: An exploratory studyMohammed Ashrafi, Yun Xu, Howbeer Muhamadali, Iain R. White, Maxim Wilkinson, Mohamed Baguneid, Roy Goodacre, Ardeshir Bayat, 2020, izvirni znanstveni članek Opis: Profiling skin microbiome and metabolome has been utilised to gain further insight into wound healing processes. The aims of this multi-part temporal study in 11 volunteers were to analytically profile the dynamic wound tissue and headspace metabolome and sequence microbial communities in acute wound healing at days 0, 7, 14, 21 and 28, and to investigate their relationship to wound healing, using non-invasive quantitative devices. Metabolites were obtained using tissue extraction, sorbent and polydimethylsiloxane patches and analysed using GCMS. PCA of wound tissue metabolome clearly separated time points with 10 metabolites of 346 being involved in separation. Analysis of variance-simultaneous component analysis identified a statistical difference between the wound headspace metabolome, sites (P = 0.0024) and time points (P<0.0001), with 10 out of the 129 metabolites measured involved with this separation between sites and time points. A reciprocal relationship between Staphylococcus spp. and Propionibacterium spp. was observed at day 21 (P<0.05) with a statistical correlation between collagen and Propionibacterium (r = 0.417; P = 0.038) and Staphylococcus (r = -0.434; P = 0.03). Procrustes analysis showed a statistically significant similarity between wound headspace and tissue metabolome with non-invasive wound devices. This exploratory study demonstrates the temporal and dynamic nature of acute wound metabolome and microbiome presenting a novel class of biomarkers that correspond to wound healing, with further confirmatory studies now necessary.
Ključne besede: metabolomics, skin, volatile organic compounds, VOCs, wound healing
Objavljeno v RUNG: 03.03.2020; Ogledov: 3101; Prenosov: 0
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85. Elucidation of Donor:Acceptor Phase Separation in Nonfullerene Organic Solar Cells and Its Implications on Device Performance and Charge Carrier MobilitySebastian F. Hoefler, Georg Haberfehlner, Thomas Rath, Andreas Keilbach, Mathias Hobisch, Alexander Dixon, Egon Pavlica, Gvido Bratina, Gerald Kothleitner, Ferdinand Hofer, Gregor Trimmel, 2019, izvirni znanstveni članek Opis: In bulk-heterojunction solar cells, the device performance strongly depends on the donor and acceptor properties, the phase separation in the absorber layer, and the formation of a bicontinuous network. While this phase separation is well explored for polymer:fullerene solar cells, only little is known for polymer:nonfullerene acceptor solar cells. The main hurdle in this regard is often the chemical similarity of the conjugated polymer donor and the organic nonfullerene acceptor (NFA), which makes the analysis of the phase separation via atomic force microscopic (AFM) phase images or conventional transmission electron microscopy difficult. In this work, we use the donor polymer PTB7-Th and the small molecule acceptor O-IDTBR as the model system and visualized the phase separation in PTB7-Th:O-IDTBR bulk-heterojunctions with different donor:acceptor ratios via scanning transmission electron microscopy (STEM) high-angle annular dark-field (HAADF) images and electron energy loss spectroscopy (EELS) based elemental mapping, which resulted in a good contrast between the donor and the acceptor despite very low differences in the chemical composition. AFM as well as grazing-incidence wide-angle X-ray scattering (GIWAXS) investigations support the electron microscopic data. Furthermore, we elucidate the implications of the phase separation on the device performance as well as charge carrier mobilities in the bulk-heterojunction layers, and a high performance of the solar cells was found over a relatively broad range of polymer domain sizes. This can be related to the larger domain sizes of the acceptor phase with higher amounts of O-IDTBR in the blend, while the polymer donor phase still forms continuous pathways to the electrode, which keeps the hole mobility at a relatively constant level.
Ključne besede: nanomorphology bulk-heterojunction scanning transmission electron microscopy organic photovoltaics charge carrier mobility
Objavljeno v RUNG: 15.01.2020; Ogledov: 3057; Prenosov: 85
 Celotno besedilo (6,22 MB) |
86. The role of charge transfer at reduced graphene oxide/organic semiconductor interface on the charge transport propertiesGvido Bratina, Egon Pavlica, 2019, izvirni znanstveni članek Opis: The effect of 1-pyrenesulfonicacid sodium salt (1-PSA), tetracyanoethylene (TCNE) and tetrafluoro- tetracyanoquinodimethane (F4-TCNQ) on charge transport properties of reduced graphene oxide (RGO) is examined by measuring the transfer characteristics of field-effect transistors and co-planar time-of-flight photocurrent technique. Evidence of p-type doping and a reduction of mobility of electrons in RGO upon deposition of these materials is observed. Time-resolved photocurrent measurements show a reduction in elec- tron mobility even at submonolayer coverage of these materials. The variation of transit time with different coverages reveals that electron mobility decreases with increasing the surface coverage of 1-PSA, TCNE and F4- TCNQ to a certain extent, while at higher coverage the electron mobility is slightly recovered. All three molecules show the same trend in charge carrier mobility variation with coverage, but with different magnitude. Among all three molecules, 1-PSA acts as weak electron acceptor compared to TCNE and F4-TCNQ. The additional fluorine moieties in F4-TCNQ provides excellent electron withdrawing capability compared to TCNE. The experimental results are consistent with the density functional theory calculations.
Ključne besede: organic semiconductors, reduced graphene oxide, time-resolved photocurrent measurements, organic thin film transistors
Objavljeno v RUNG: 28.10.2019; Ogledov: 3655; Prenosov: 1
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87. Uranium bearing dissolved organic matter in the porewaters of uranium contaminated lake sedimentsBreda Novotnik, Wei Chen, R. Douglas Evans, 2018, izvirni znanstveni članek Opis: Uranium (U) mobility in the environment strongly depends on its oxidation state and the presence of complexing
agents such as inorganic carbon, phosphates, and dissolved organic matter (DOM). Despite the importance of
DOM in U mobility, the exact mechanism is still poorly understood. Therefore, the aim of our investigation was
to characterise sediment porewater DOM in two lakes in Ontario, Canada (Bow and Bentley Lakes) that were
historically contaminated with U and propose possible composition of UO2-bearing DOM. Depth profiles of U
concentrations in porewaters and total sediment digests reveal U levels of up to 1.3 mg L−1 in porewater and up
to 0.8 mg−1 g in sediment. Depth profiles of U did not correlate with Fe, Mn, SO4
2−, or Eh profiles. Therefore,
porewater DOM was analysed and taken into consideration as the primary source of U mobility. Porewater DOM
in each sediment section (1 cm sections, 20 cm core length) was analysed by high-resolution electrospray ionisation
mass spectrometry. PCA analyses of porewater DOM mass spectra showed grouping and clear separation
of DOM in sediment sections with elevated U concentrations in comparison to sections with background U
concentrations. Several criteria were set to characterise UO2-bearing DOM and more than 70 different molecules
were found. The vast majority of these UO2-DOM compounds fell in the category of carboxyl-containing aliphatic
molecules (H/C between 0.85 and 1.2 and O/C≤0.4) and had a mean value of m/z about 720.
Ključne besede: Uranium
Lake sediments
Porewater
Disolved organic matter
High resolution mass spectrometry
Objavljeno v RUNG: 09.10.2019; Ogledov: 3256; Prenosov: 0
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88. Real-time multi-marker measurement of organic compounds in human breath: Towards fingerprinting breathIain R. White, Kerry A Willis, Christopher Whyte, Rebecca Cordell, Robert S Blake, Andrew J Wardlaw, 2013, izvirni znanstveni članek Opis: The prospects for exploiting proton transfer reaction-time of flight-mass spectrometry (PTR-ToF-MS) in medical diagnostics are illustrated through a series of case studies. Measurements of acetone levels in the breath of 68 healthy people are presented along with a longitudinal study of a single person over a period of 1 month. The median acetone concentration across the population was 484 ppbV with a geometric standard deviation (GSD) of 1.6, whilst the average GSD during the single subject longtitudinal study was 1.5. An additional case study is presented which highlights the potential of PTR-ToF-MS in pharmacokinetic studies, based upon the analysis of online breath samples of a person following the consumption of ethanol. PTR-ToF-MS comes into its own when information across a wide mass range is required, particularly when such information must be gathered in a short time during a breathing cycle. To illustrate this property, multicomponent breath analysis in a small study of cystic fibrosis patients is detailed, which provides tentative evidence that online PTR-ToF-MS analysis of tidal breath can distinguish between active infection and non-infected patients.
Ključne besede: Volatile Organic Compounds, breath, proton transfer reaction mass spectrometry, Cystic Fibrosis
Objavljeno v RUNG: 22.07.2019; Ogledov: 3382; Prenosov: 0
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89. Increased sensitivity in proton transfer reaction mass spectrometry by incorporation of a radio frequency ion funnelShane Barber, Robert S Blake, Iain R. White, Paul S Monks, Fraser Reich, Stephen Mullock, Andrew M Ellis, 2012, izvirni znanstveni članek Opis: A drift tube capable of simultaneously functioning as an ion funnel is demonstrated in proton transfer reaction mass spectrometry (PTR-MS) for the first time. The ion funnel enables a much higher proportion of ions to exit the drift tube and enter the mass spectrometer than would otherwise be the case. An increase in the detection sensitivity for volatile organic compounds of between 1 and 2 orders of magnitude is delivered, as demonstrated using several compounds. Other aspects of analytical performance explored in this study include the effective E/N (ratio of electric field to number density of the gas) and dynamic range over which the drift tube is operated. The dual-purpose drift tube/ion funnel can be coupled to various types of mass spectrometers to increase the detection sensitivity and may therefore offer considerable benefits in PTR-MS work.
Ključne besede: Analytical performance, Detection sensitivity, Drift tube, Dynamic range, Ion funnels, Proton-transfer reaction mass spectrometry, Volatile organic compounds
Objavljeno v RUNG: 18.07.2019; Ogledov: 2939; Prenosov: 0
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90. Development of an adaptable headspace sampling method for metabolic profiling of the fungal volatomeWaqar M Ahmed, Pavlos Geranios, Iain R. White, Oluwasola Lawal, Tamara M Nijsen, Michael J Bromley, Royston Goodacre, Nicholas D Read, Stephen J. Fowler, 2018, izvirni znanstveni članek Opis: Pulmonary aspergillosis can cause serious complications in people with a suppressed immune system. Volatile metabolites emitted by Aspergillus spp. have shown promise for early detection of pathogenicity. However, volatile profiles require further research, as effective headspace analysis methods are required for extended chemical coverage of the volatome; in terms of both very volatile and semi-volatile compounds. In this study, we describe a novel adaptable sampling method in which fungal headspace samples can be sampled continuously throughout a defined time period using both active (pumped) and passive (diffusive) methods, with the capability for samples to be stored for later off-line analysis. For this method we utilise thermal desorption-gas chromatography-mass spectrometry to generate volatile metabolic profiles using Aspergillus fumigatus as the model organism. Several known fungal-specific volatiles associated with secondary metabolite biosynthesis (including α-pinene, camphene, limonene, and several sesquiterpenes) were identified. A comparison between the wild-type A. fumigatus with a phosphopantetheinyl transferase null mutant strain (ΔpptA) that is compromised in secondary metabolite synthesis, revealed reduced production of sesquiterpenes. We also showed the lack of terpene compounds production during the early growth phase, whilst pyrazines were identified in both early and late growth phases. We have demonstrated that the fungal volatome is dynamic and it is therefore critically necessary to sample the headspace across several time periods using a combination of active and passive sampling techniques to analyse and understand this dynamism.
Ključne besede: Volatile Organic Compounds, Fungi, Mycelial growth
Objavljeno v RUNG: 18.07.2019; Ogledov: 2973; Prenosov: 0
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