The investigation of the stability of ruthenium based photocatalysts using HPLC, NMR and UV visible techniques

In this thesis, the use of high performance liquid chromatography (HPLC) for the analysis, assessment and characterisation of photocatalytic behaviour. The Ru(II) compounds are coordinated at peripheral ligands to create at Ru(II) centre, while bridging ligands are used to connect the ruthenium centre to the Pt catalytic centres in order to create intramolecular systems. The properties of these platinum-containing compounds were compared with the mononuclear ruthenium precursor, without a platinum centre, in terms of photostability and catalytic activity. These intramolecular platinum containing compounds are aimed at create photocatalysts in combination with terminal halogen atoms (iodide or chloride). UV-vis absorption and 1H-NMR analysis were carried out to provide further detailed qualitative and structural information as a result of the photocatalytic experiments terminal, halogen atoms (iodide or chloride) and range of techniques where discussed, to provide further detailed and structural information. UV-vis absorption and 1H-NMR analysis were carried out to provide further detailed information about the possible chemical changes taking place after irradiation as a result of the photocatalytic experiments. In Chapter 1, a number of relevant topics are discussed and the studies presented in this thesis in order to explain our research targets and experimental techniques. In Chapter 2, the introduction to HPLC, analytical HPLC, HPLC setup, mobile phases and UV-Vis Spectroscopy used and 1H NMR spectroscopy are discussed and sample preparation for photoanalysis with TEA and without TEA were explained. In Chapter 3 stability towards visible light by the complexes [(bpy)2Ru(2,3dpp)]2+ (A-I), [(bpy)2Ru(2,3dpp)PtCl2] 2+ (A-II), and [(bpy)2Ru(2,3dpp)PtI2] 2+ (A-III) were carried out. Without TEA all three compounds the compounds are mostly photostable, but in the presence of TEA decomposition of the compounds is observed. In Chapter 4, for the compounds [(phen)2Ru(2,3dpp)]2+ (B-I), [(phen)2Ru(2,3dpp)PtCl2] 2+ (B-II), and [(phen)2Ru(2,3dpp)PtI2] 2+ (B-III), compounds B-I and B-II are photostable and B-III is partially photostable. In the presence of TEA, changes in the coordination of the bridging ligands are observed. In Chapter 5 compounds [(dceb)2Ru(2,3dpp)]2+ (C-I), [(dceb)2Ru(2,3dpp)PtCl2] 2+ (C-II), and [(dceb)2Ru(2,3dpp)PtI2] 2+ (C-III) are discussed. In the presence of irradiation, compounds C-I and C-III are photoreactive while that compound C-II is photostable. The stability of irradiation in the presence of TEA compounds C-I, C-II and CIII are degrading fast. In Chapter 6 a general overview of the work carried out is discussed

Hybrid active damping of LCL-filtered grid connected converter

A method for hybrid active damping in power converters connected to a weak grid using an LCL filter is proposed. It uses feedback of the grid current and capacitor voltage and is derived as an equivalent to the capacitor current feedback active damping method. A co-design procedure for the grid current controller with the proposed hybrid active damping method is presented. The robustness, system bandwidth and harmonic rejection are studied. The proposed method is applied to a single grid connected converter with variable grid inductance to investigate its ability to damp different system resonance frequencies and its effectiveness is verified via frequency domain analysis and time domain simulation

Grid impedance estimation for islanding detection and adaptive control of converters

The grid impedance is time varying due to the changing structure of the power system configuration and it can have a considerable influence on the control and stability of grid connected converters. This paper presents an online grid impedance estimation method using the output switching current ripple of a SVPWM based grid connected converter. The proposed impedance estimation method is derived from the discretised system model using two consecutive samples within the switching period. The estimated impedance is used for islanding detection and online current controller parameter adaptation. Theoretical analysis and MATLAB simulation results are presented to verify the proposed method. The effectiveness of the grid impedance estimator is validated using experimental results

Wide frequency range active damping of LCL-filtered grid connected converters

It can be challenging to guarantee the stability of grids with many converters with LCL filters connected due to the presence of multiple resonances within the system. This paper presents an active damping technique to mitigate multiple resonance effects and harmonics in power converters connected to weak grids. The proposed technique employs grid current and capacitor voltage feedback to achieve active damping for a wide range of multiple resonance frequencies. The effectiveness of the proposed wide frequency active damping and improved controller stability are demonstrated through frequency domain analysis and experimental results for single and parallel grid connected converters

TNF-α induces a pro-inflammatory phenotypic shift in monocytes through ACSL1 : Relevance to metabolic inflammation

Background/Aims: TNF-α-mediated pro-inflammatory phenotypic change in monocytes is known to be implicated in the pathogenesis of metabolic inflammation and insulin resistance. However, the mechanism by which TNF-α-induces inflammatory phenotypic shift in monocytes is poorly understood. Since long-chain acyl-CoA synthetase 1 (ACSL1) is associated with inflammatory monocytes/macrophages, we investigated the role of ACSL1 in the TNF-α-driven inflammatory phenotypic shift in the monocytes. Methods: Monocytes (Human monocytic THP-1 cells) were stimulated with TNF-α. Inflammatory phenotypic markers (CD16, CD11b, CD11c and HLA-DR) expression was determined with real time RT-PCR and flow cytometry. IL-1β and MCP-1 were determined by ELISA. Signaling pathways were identified by using ACSL1 inhibitor, ACSL1 siRNA and NF-κB reporter monocytic cells. Phosphorylation of NF-κB was analyzed by western blotting and flow cytometry. Results: Our data show that TNF-α induced significant increase in the expression of CD16, CD11b, CD11c and HLA-DR. Inhibition of ACSL1 activity in the cells with triacsin C significantly suppressed the expression of these inflammatory markers. Using ACSL-1 siRNA, we further demonstrate that TNF-α-induced inflammatory markers expression in monocytic cells requires ACSL1. In addition, IL-1b and MCP-1 production by TNF-α activated monocytic cells was significantly blocked by the inhibition of ACSL-1 activity. Interestingly, elevated NF-κB activity resulting from TNF-α stimulation was attenuated in ACSL1 deficient cells. Conclusion: Our findings provide an evidence that TNF-α-associated inflammatory polarization in monocytes is an ACSL1 dependent process, which indicates its central role in TNF-α-driven metabolic inflammation. © 2019 The Author(s).Peer reviewe

Tribological behavior and vibration effect on the friction coefficient and temperature of glass fiber composite

The extents of contact coefficient are diverse for various material sets relying upon typical load and sliding speed. In the present research, grating coefficients and wear of glass fiber (GF) composite circles sliding against aluminum stick under vibration are explored and the outcomes were contrasted with a similar condition which is not in under vibration. So as to play out the tests, a stick on circle mechanical assembly is utilized. Tests are completed when aluminum stick slides on glass fiber (GF) plates of various organizations, for example, polyamide 6 (PA6), 20% GF and 15% GF. Examinations are led at ordinary load 2.5, 3.75 and 5N, sliding speed 0.5, 0.75 and 1 m/s. Varieties of erosion coefficient with the length of rubbing at diverse typical loads and sliding speeds are explored under vibration (vertical vibration). As a rule, contact coefficient expanded for a specific length of rubbing yet after that it stay steady for whatever remains of the test time. The trial result uncovers that contact coefficient diminished with the expansion in ordinary load for all the tried plates at steady speed and spring solidness. Then again, it is additionally found that grating coefficient diminished with the expansion in sliding speed however wear rate increments. Besides, both the friction coefficient and wear rate expanded with the expansion in spring firmness at consistent typical load and sliding speed for all sliding pairs. The contact coefficient is observed to be to some degree littler under vibration contrasted with that of vibration less condition.

Wide frequency range active damping of LCL-filtered grid connected converters

It can be challenging to guarantee the stability of grids with many converters with LCL filters connected due to the presence of multiple resonances within the system. This paper presents an active damping technique to mitigate multiple resonance effects and harmonics in power converters connected to weak grids. The proposed technique employs grid current and capacitor voltage feedback to achieve active damping for a wide range of multiple resonance frequencies. The effectiveness of the proposed wide frequency active damping and improved controller stability are demonstrated through frequency domain analysis and experimental results for single and parallel grid connected converters

Analysis and design of defected ground structure for EMC improvement in mixed-signal transceiver modules

In this research, the return path discontinuity (RPD), located under the power amplifier (PA) substrate, of X-band transceiver module (Base), mounted on a four-layer printed circuit board (PCB), is investigated to improve the signal integrity by reducing the difference in the reference potential. This study is performed by initially employing the wirebond method, through the assessment of both numbers and sizes of bondwires by advanced design system (ADS). Six bondwires of 25 µm are added, producing an improvement of 6.82 dB for the reflection coefficient and 1.19 dB for the isolation and insertion loss. For further improvement, spiral shape defected ground structure (DGS) is implemented in the inner ground layer (layer 2) without using bond wires. The DGS simulation results illustrate an improvement of 3 dB for S11 and 0.6 dB for S12. To improve the electromagnetic compatibility (EMC), the authors propose combination and integration of both wirebond and DGS methods, called wirebond–DGS method, which results in an improvement of 11.86 dB for S11, 1.34 dB for S12 and S21, and 12.03 dB for S22. Finally, the wirebond–DGS RF module was fabricated and the measurement results exhibit an improvement of 8.07 dB for S11 and 9.39 dB for S22 in comparison with the fabricated Base module. In addition, 0.53 dB improvement for both S12 and S21 is also achieved

Genomic–transcriptomic evolution in lung cancer and metastasis

Intratumour heterogeneity (ITH) fuels lung cancer evolution, which leads to immune evasion and resistance to therapy1. Here, using paired whole-exome and RNA sequencing data, we investigate intratumour transcriptomic diversity in 354 non-small cell lung cancer tumours from 347 out of the first 421 patients prospectively recruited into the TRACERx study2,3. Analyses of 947 tumour regions, representing both primary and metastatic disease, alongside 96 tumour-adjacent normal tissue samples implicate the transcriptome as a major source of phenotypic variation. Gene expression levels and ITH relate to patterns of positive and negative selection during tumour evolution. We observe frequent copy number-independent allele-specific expression that is linked to epigenomic dysfunction. Allele-specific expression can also result in genomic–transcriptomic parallel evolution, which converges on cancer gene disruption. We extract signatures of RNA single-base substitutions and link their aetiology to the activity of the RNA-editing enzymes ADAR and APOBEC3A, thereby revealing otherwise undetected ongoing APOBEC activity in tumours. Characterizing the transcriptomes of primary–metastatic tumour pairs, we combine multiple machine-learning approaches that leverage genomic and transcriptomic variables to link metastasis-seeding potential to the evolutionary context of mutations and increased proliferation within primary tumour regions. These results highlight the interplay between the genome and transcriptome in influencing ITH, lung cancer evolution and metastasis