| 791. |
- Naumova, Maria A., et al.
(author)
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Exploring the light-induced dynamics in solvated metallogrid complexes with femtosecond pulses across the electromagnetic spectrum
- 2020
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In: The Journal of chemical physics. - : AIP Publishing. - 0021-9606 .- 1089-7690. ; 152:21
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Journal article (peer-reviewed)abstract
- Oligonuclear complexes of d4-d7 transition metal ion centers that undergo spin-switching have long been developed for their practical role in molecular electronics. Recently, they also have appeared as promising photochemical reactants demonstrating improved stability. However, the lack of knowledge about their photophysical properties in the solution phase compared to mononuclear complexes is currently hampering their inclusion into advanced light-driven reactions. In the present study, the ultrafast photoinduced dynamics in a solvated [2 × 2] iron(II) metallogrid complex are characterized by combining measurements with transient optical-infrared absorption and x-ray emission spectroscopy on the femtosecond time scale. The analysis is supported by density functional theory calculations. The photocycle can be described in terms of intra-site transitions, where the FeII centers in the low-spin state are independently photoexcited. The Franck-Condon state decays via the formation of a vibrationally hot high-spin (HS) state that displays coherent behavior within a few picoseconds and thermalizes within tens of picoseconds to yield a metastable HS state living for several hundreds of nanoseconds. Systematic comparison with the closely related mononuclear complex [Fe(terpy)2]2+ reveals that nuclearity has a profound impact on the photoinduced dynamics. More generally, this work provides guidelines for expanding the integration of oligonuclear complexes into new photoconversion schemes that may be triggered by ultrafast spin-switching.
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| 792. |
- Naumova, Maria A., et al.
(author)
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Revealing Hot and Long-Lived Metastable Spin States in the Photoinduced Switching of Solvated Metallogrid Complexes with Femtosecond Optical and X-ray Spectroscopies
- 2020
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In: The Journal of Physical Chemistry Letters. - : American Chemical Society (ACS). - 1948-7185. ; 11:6, s. 2133-2141
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Journal article (peer-reviewed)abstract
- An atomistic understanding of the photoinduced spin-state switching (PSS) within polynuclear systems of d4-d7 transition metal ion complexes is required for their rational integration into light-driven reactions of chemical and biological interest. However, in contrast to mononuclear systems, the multidimensional dynamics of the PSS in solvated molecular arrays have not yet been elucidated due to the expected complications associated with the connectivity between the metal centers and the strong interactions with the surroundings. In this work, the PSS in a solvated triiron(II) metallogrid complex is characterized using transient optical absorption and X-ray emission spectroscopies on the femtosecond time scale. The complementary measurements reveal the photoinduced creation of energy-rich (hot) and long-lived quintet states, whose dynamics differ critically from their mononuclear congeners. This finding opens major prospects for developing novel schemes in solution-phase spin chemistry that are driven by the dynamic PSS process in compact oligometallic arrays.
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| 793. |
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| 794. |
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| 795. |
- Ng, G. K. L., et al.
(author)
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Porosity formation and gas bubble retention in laser metal deposition
- 2009
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In: Applied Physics A. - : Springer Science and Business Media LLC. - 0947-8396 .- 1432-0630. ; 97:3, s. 641-649
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Journal article (peer-reviewed)abstract
- One of the inherent problems associated with laser metal deposition using gas-assisted powder transfer is the formation of porosity, which can be detrimental to the mechanical properties of the bulk material. In this work, a comprehensive investigation of porosity is carried out using gas atomised Inconel 718 powder. In the analysis, a clear distinction is made between two types of porosity; namely lack of fusion and gas porosity. The results show that the two types of porosity are attributed by different factors. The gas porosity, which is more difficult to eliminate than the lack of fusion, can be as high as 0.7%. The study shows that the gas porosity is dependent on the process parameters and the melt pool dynamics. The flotation of entrapped gas bubbles was analysed, showing that in a stationary melt pool the gas would be retained by Marangoni-driven flow. The overall Marangoni-driven flow of the melt pool is in the order of five times higher than the flotation effect, and this is the reason why the melt pool geometry would tend to dominate the flow direction of the gas bubbles. Through optimisation, the gas porosity can be reduced to 0.037%. © 2009 Springer-Verlag.
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| 796. |
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| 797. |
- Nogal, Ana, et al.
(author)
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Genetic and gut microbiome determinants of SCFA circulating and fecal levels, postprandial responses and links to chronic and acute inflammation
- 2023
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In: Gut microbes. - 1949-0976. ; 15:1
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Journal article (peer-reviewed)abstract
- Short-chain fatty acids (SCFA) are involved in immune system and inflammatory responses. We comprehensively assessed the host genetic and gut microbial contribution to a panel of eight serum and stool SCFAs in two cohorts (TwinsUK, n = 2507; ZOE PREDICT-1, n = 328), examined their postprandial changes and explored their links with chronic and acute inflammatory responses in healthy individuals and trauma patients. We report low concordance between circulating and fecal SCFAs, significant postprandial changes in most circulating SCFAs, and a heritable genetic component (average h2 : serum = 14%(SD = 14%); stool = 12%(SD = 6%)). Furthermore, we find that gut microbiome can accurately predict their fecal levels (AUC>0.71) while presenting weaker associations with serum. Finally, we report different correlation patterns with inflammatory markers depending on the type of inflammatory response (chronic or acute trauma). Our results illustrate the breadth of the physiological relevance of SCFAs on human inflammatory and metabolic responses highlighting the need for a deeper understanding of this important class of molecules.
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| 798. |
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| 799. |
- O'Mara, TA, et al.
(author)
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Identification of nine new susceptibility loci for endometrial cancer
- 2018
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In: Nature communications. - : Springer Science and Business Media LLC. - 2041-1723. ; 9:1, s. 3166-
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Journal article (peer-reviewed)abstract
- Endometrial cancer is the most commonly diagnosed cancer of the female reproductive tract in developed countries. Through genome-wide association studies (GWAS), we have previously identified eight risk loci for endometrial cancer. Here, we present an expanded meta-analysis of 12,906 endometrial cancer cases and 108,979 controls (including new genotype data for 5624 cases) and identify nine novel genome-wide significant loci, including a locus on 12q24.12 previously identified by meta-GWAS of endometrial and colorectal cancer. At five loci, expression quantitative trait locus (eQTL) analyses identify candidate causal genes; risk alleles at two of these loci associate with decreased expression of genes, which encode negative regulators of oncogenic signal transduction proteins (SH2B3 (12q24.12) and NF1 (17q11.2)). In summary, this study has doubled the number of known endometrial cancer risk loci and revealed candidate causal genes for future study.
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| 800. |
- Ooi, BNS, et al.
(author)
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The genetic interplay between body mass index, breast size and breast cancer risk: a Mendelian randomization analysis
- 2019
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In: International journal of epidemiology. - : Oxford University Press (OUP). - 1464-3685 .- 0300-5771. ; 48:3, s. 781-794
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Journal article (peer-reviewed)abstract
- BackgroundEvidence linking breast size to breast cancer risk has been inconsistent, and its interpretation is often hampered by confounding factors such as body mass index (BMI). Here, we used linkage disequilibrium score regression and two-sample Mendelian randomization (MR) to examine the genetic associations between BMI, breast size and breast cancer risk.MethodsSummary-level genotype data from 23andMe, Inc (breast size, n = 33 790), the Breast Cancer Association Consortium (breast cancer risk, n = 228 951) and the Genetic Investigation of ANthropometric Traits (BMI, n = 183 507) were used for our analyses. In assessing causal relationships, four complementary MR techniques [inverse variance weighted (IVW), weighted median, weighted mode and MR-Egger regression] were used to test the robustness of the results.ResultsThe genetic correlation (rg) estimated between BMI and breast size was high (rg = 0.50, P = 3.89x10−43). All MR methods provided consistent evidence that higher genetically predicted BMI was associated with larger breast size [odds ratio (ORIVW): 2.06 (1.80–2.35), P = 1.38x10−26] and lower overall breast cancer risk [ORIVW: 0.81 (0.74–0.89), P = 9.44x10−6]. No evidence of a relationship between genetically predicted breast size and breast cancer risk was found except when using the weighted median and weighted mode methods, and only with oestrogen receptor (ER)-negative risk. There was no evidence of reverse causality in any of the analyses conducted (P > 0.050).ConclusionOur findings indicate a potential positive causal association between BMI and breast size and a potential negative causal association between BMI and breast cancer risk. We found no clear evidence for a direct relationship between breast size and breast cancer risk.
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