| 1. |
|
|
| 2. |
|
|
| 3. |
- Schmidt, Amand F., et al.
(författare)
-
Phenome-wide association analysis of LDL-cholesterol lowering genetic variants in PCSK9
- 2019
-
Ingår i: BMC Cardiovascular Disorders. - : BMC. - 1471-2261 .- 1471-2261. ; 19:1
-
Tidskriftsartikel (refereegranskat)abstract
- Background: We characterised the phenotypic consequence of genetic variation at the PCSK9 locus and compared findings with recent trials of pharmacological inhibitors of PCSK9. Methods: Published and individual participant level data (300,000+ participants) were combined to construct a weighted PCSK9 gene-centric score (GS). Seventeen randomized placebo controlled PCSK9 inhibitor trials were included, providing data on 79,578 participants. Results were scaled to a one mmol/L lower LDL-C concentration. Results: The PCSK9 GS (comprising 4 SNPs) associations with plasma lipid and apolipoprotein levels were consistent in direction with treatment effects. The GS odds ratio (OR) for myocardial infarction (MI) was 0.53 (95% CI 0.42; 0.68), compared to a PCSK9 inhibitor effect of 0.90 (95% CI 0.86; 0.93). For ischemic stroke ORs were 0.84 (95% CI 0.57; 1.22) for the GS, compared to 0.85 (95% CI 0.78; 0.93) in the drug trials. ORs with type 2 diabetes mellitus (T2DM) were 1.29 (95% CI 1.11; 1.50) for the GS, as compared to 1.00 (95% CI 0.96; 1.04) for incident T2DM in PCSK9 inhibitor trials. No genetic associations were observed for cancer, heart failure, atrial fibrillation, chronic obstructive pulmonary disease, or Alzheimer's disease - outcomes for which large-scale trial data were unavailable. Conclusions: Genetic variation at the PCSK9 locus recapitulates the effects of therapeutic inhibition of PCSK9 on major blood lipid fractions and MI. While indicating an increased risk of T2DM, no other possible safety concerns were shown; although precision was moderate.
|
|
| 4. |
- Ashuiev, Anton, et al.
(författare)
-
Geometry and electronic structure of Yb(iii)[CH(SiMe3)2]3 from EPR and solid-state NMR augmented by computations
- 2024
-
Ingår i: Physical Chemistry, Chemical Physics - PCCP. - 1463-9076 .- 1463-9084. ; 26:11, s. 8734-8747
-
Tidskriftsartikel (refereegranskat)abstract
- Characterization of paramagnetic compounds, in particular regarding the detailed conformation and electronic structure, remains a challenge, and – still today it often relies solely on the use of X-ray crystallography, thus limiting the access to electronic structure information. This is particularly true for lanthanide elements that are often associated with peculiar structural and electronic features in relation to their partially filled f-shell. Here, we develop a methodology based on the combined use of state-of-the-art magnetic resonance spectroscopies (EPR and solid-state NMR) and computational approaches as well as magnetic susceptibility measurements to determine the electronic structure and geometry of a paramagnetic Yb(III) alkyl complex, Yb(III)[CH(SiMe3)2]3, a prototypical example, which contains notable structural features according to X-ray crystallography. Each of these techniques revealed specific information about the geometry and electronic structure of the complex. Taken together, both EPR and NMR, augmented by quantum chemical calculations, provide a detailed and complementary understanding of such paramagnetic compounds. In particular, the EPR and NMR signatures point to the presence of three-centre–two-electron Yb-γ-Me-β-Si secondary metal–ligand interactions in this otherwise tri-coordinate metal complex, similarly to its diamagnetic Lu analogues. The electronic structure of Yb(III) can be described as a single 4f13 configuration, while an unusually large crystal-field splitting results in a thermally isolated ground Kramers doublet. Furthermore, the computational data indicate that the Yb–carbon bond contains some π-character, reminiscent of the so-called α-H agostic interaction.
|
|
| 5. |
|
|
| 6. |
- Padmanabhan, Sandosh, et al.
(författare)
-
Genome-Wide Association Study of Blood Pressure Extremes Identifies Variant near UMOD Associated with Hypertension
- 2010
-
Ingår i: PLoS Genetics. - : Public Library of Science (PLoS). - 1553-7404. ; 6:10
-
Tidskriftsartikel (refereegranskat)abstract
- Hypertension is a heritable and major contributor to the global burden of disease. The sum of rare and common genetic variants robustly identified so far explain only 1%-2% of the population variation in BP and hypertension. This suggests the existence of more undiscovered common variants. We conducted a genome-wide association study in 1,621 hypertensive cases and 1,699 controls and follow-up validation analyses in 19,845 cases and 16,541 controls using an extreme case-control design. We identified a locus on chromosome 16 in the 59 region of Uromodulin (UMOD; rs13333226, combined P value of 3.6x10(-11)). The minor G allele is associated with a lower risk of hypertension (OR [95% CI]: 0.87 [0.84-0.91]), reduced urinary uromodulin excretion, better renal function; and each copy of the G allele is associated with a 7.7% reduction in risk of CVD events after adjusting for age, sex, BMI, and smoking status (H.R. = 0.923, 95% CI 0.860-0.991; p = 0.027). In a subset of 13,446 individuals with estimated glomerular filtration rate (eGFR) measurements, we show that rs13333226 is independently associated with hypertension (unadjusted for eGFR: 0.89 [0.83-0.96], p = 0.004; after eGFR adjustment: 0.89 [0.83-0.96], p = 0.003). In clinical functional studies, we also consistently show the minor G allele is associated with lower urinary uromodulin excretion. The exclusive expression of uromodulin in the thick portion of the ascending limb of Henle suggests a putative role of this variant in hypertension through an effect on sodium homeostasis. The newly discovered UMOD locus for hypertension has the potential to give new insights into the role of uromodulin in BP regulation and to identify novel drugable targets for reducing cardiovascular risk.
|
|
| 7. |
- Schmidt, Amand F., et al.
(författare)
-
PCSK9 genetic variants and risk of type 2 diabetes : a mendelian randomisation study
- 2017
-
Ingår i: The Lancet Diabetes and Endocrinology. - : ELSEVIER SCIENCE INC. - 2213-8587 .- 2213-8595. ; 5:2, s. 97-105
-
Tidskriftsartikel (refereegranskat)abstract
- Background Statin treatment and variants in the gene encoding HMG-CoA reductase are associated with reductions in both the concentration of LDL cholesterol and the risk of coronary heart disease, but also with modest hyperglycaemia, increased bodyweight, and modestly increased risk of type 2 diabetes, which in no way off sets their substantial benefi ts. We sought to investigate the associations of LDL cholesterol-lowering PCSK9 variants with type 2 diabetes and related biomarkers to gauge the likely eff ects of PCSK9 inhibitors on diabetes risk. Methods In this mendelian randomisation study, we used data from cohort studies, randomised controlled trials, case control studies, and genetic consortia to estimate associations of PCSK9 genetic variants with LDL cholesterol, fasting blood glucose, HbA 1c, fasting insulin, bodyweight, waist-to-hip ratio, BMI, and risk of type 2 diabetes, using a standardised analysis plan, meta-analyses, and weighted gene-centric scores. Findings Data were available for more than 550 000 individuals and 51 623 cases of type 2 diabetes. Combined analyses of four independent PCSK9 variants (rs11583680, rs11591147, rs2479409, and rs11206510) scaled to 1 mmol/L lower LDL cholesterol showed associations with increased fasting glucose (0.09 mmol/L, 95% CI 0.02 to 0.15), bodyweight (1.03 kg, 0.24 to 1.82), waist-to-hip ratio (0.006, 0.003 to 0.010), and an odds ratio for type diabetes of 1.29 (1.11 to 1.50). Based on the collected data, we did not identify associations with HbA 1c (0.03%, -0.01 to 0.08), fasting insulin (0.00%, -0.06 to 0.07), and BMI (0.11 kg/m(2), -0.09 to 0.30). Interpretation PCSK9 variants associated with lower LDL cholesterol were also associated with circulating higher fasting glucose concentration, bodyweight, and waist-to-hip ratio, and an increased risk of type 2 diabetes. In trials of PCSK9 inhibitor drugs, investigators should carefully assess these safety outcomes and quantify the risks and benefi ts of PCSK9 inhibitor treatment, as was previously done for statins.
|
|
| 8. |
- Stamou, Christina, et al.
(författare)
-
Indium(III) in the "Periodic Table" of Di(2-pyridyl) Ketone : An Unprecedented Transformation of the Ligand and Solid-State In-115 NMR Spectroscopy as a Valuable Structural Tool
- 2021
-
Ingår i: Inorganic Chemistry. - : American Chemical Society (ACS). - 0020-1669 .- 1520-510X. ; 60:7, s. 4829-4840
-
Tidskriftsartikel (refereegranskat)abstract
- Reactions of di(2-pyridyl) ketone, (py)(2)CO, with indium(III) halides in CH3NO2 have been studied, and a new transformation of the ligand has been revealed. In the presence of In-III, the C=O bond of (py)(2)CO is subjected to nucleophilic attack by the carbanion -:CH2NO2, yielding the dinuclear complexes [In2X4{(py)(2)C(CH2NO2)(O)}(2)] (X = Cl, 1; X = Br, 2; X = I, 3) in moderate to good yields. The alkoxo oxygens of the two eta(1):eta(2):eta(1)-(py)(2)C(CH2NO2)(O)- ligands doubly bridge the In-III centers and create a {In-2(mu(2)-OR)(2)}(4+) core. Two pyridyl nitrogens of different organic ligands and two terminal halogeno ions complete a distorted-octahedral stereochemistry around each In(III) ion. After maximum excitation at 360 or 380 nm, the solid chloro complex 1 emits blue light at 420 and 440 nm at room temperature, the emission being attributed to charge transfer within the coordinated organic ligand. Solid-state In-115 NMR spectra, in combination with DFT calculations, of 1-3 have been studied in detail at both 9.4 and 14.1 T magnetic fields. The nuclear quadrupolar and chemical shift parameters provide valuable findings concerning the electric field gradients and magnetic shielding at the nuclei of indium, respectively. The experimentally derived C-Q values are 40 +/- 3 MHz for 1, 46 +/- 5 MHz for 2, and 50 +/- 10 and 64 +/- 7 MHz for the two crystallographically independent InIII sites for 3, while the diso values fall in the range 130 +/- 30 to -290 +/- 60 ppm. The calculated C-Q and asymmetry parameter (eta(Q)) values are fully consistent with the experimental values for 1 and 2 and are in fairly good agreement for 3. The results have been analyzed and discussed in terms of the known (1, 3) and proposed (2) structural features of the complexes, demonstrating that In-115 NMR is an effective solid-state technique for the study of indium(III) complexes.
|
|
| 9. |
- von Seidlein, Lorenz, et al.
(författare)
-
The impact of targeted malaria elimination with mass drug administrations on falciparum malaria in Southeast Asia: A cluster randomised trial
- 2019
-
Ingår i: PLoS Medicine. - : PUBLIC LIBRARY SCIENCE. - 1549-1277 .- 1549-1676. ; 16:2
-
Tidskriftsartikel (refereegranskat)abstract
- Background The emergence and spread of multidrug-resistant Plasmodium falciparum in the Greater Mekong Subregion (GMS) threatens global malaria elimination efforts. Mass drug administration (MDA), the presumptive antimalarial treatment of an entire population to clear the subclinical parasite reservoir, is a strategy to accelerate malaria elimination. We report a cluster randomised trial to assess the effectiveness of dihydroartemisinin-piperaquine (DP) MDA in reducing falciparum malaria incidence and prevalence in 16 remote village populations in Myanmar, Vietnam, Cambodia, and the Lao Peoples Democratic Republic, where artemisinin resistance is prevalent. Methods and findings After establishing vector control and community-based case management and following intensive community engagement, we used restricted randomisation within village pairs to select 8 villages to receive early DP MDA and 8 villages as controls for 12 months, after which the control villages received deferred DP MDA. The MDA comprised 3 monthly rounds of 3 daily doses of DP and, except in Cambodia, a single low dose of primaquine. We conducted exhaustive cross-sectional surveys of the entire population of each village at quarterly intervals using ultrasensitive quantitative PCR to detect Plasmodium infections. The study was conducted between May 2013 and July 2017. The investigators randomised 16 villages that had a total of 8,445 residents at the start of the study. Of these 8,445 residents, 4,135 (49%) residents living in 8 villages, plus an additional 288 newcomers to the villages, were randomised to receive early MDA; 3,790 out of the 4,423 (86%) participated in at least 1 MDA round, and 2,520 out of the 4,423 (57%) participated in all 3 rounds. The primary outcome, P. falciparum prevalence by month 3 (M3), fell by 92% (from 5.1% [171/3,340] to 0.4% [12/2,828]) in early MDA villages and by 29% (from 7.2% [246/3,405] to 5.1% [155/3,057]) in control villages. Over the following 9 months, the P. falciparum prevalence increased to 3.3% (96/2,881) in early MDA villages and to 6.1% (128/2,101) in control villages (adjusted incidence rate ratio 0.41 [95% CI 0.20 to 0.84]; p = 0.015). Individual protection was proportional to the number of completed MDA rounds. Of 221 participants with subclinical P. falciparum infections who participated in MDA and could be followed up, 207 (94%) cleared their infections, including 9 of 10 with artemisinin-and piperaquine- resistant infections. The DP MDAs were well tolerated; 6 severe adverse events were detected during the follow-up period, but none was attributable to the intervention. Conclusions Added to community-based basic malaria control measures, 3 monthly rounds of DP MDA reduced the incidence and prevalence of falciparum malaria over a 1-year period in areas affected by artemisinin resistance. P. falciparum infections returned during the follow-up period as the remaining infections spread and malaria was reintroduced from surrounding areas. Limitations of this study include a relatively small sample of villages, heterogeneity between villages, and mobility of villagers that may have limited the impact of the intervention. These results suggest that, if used as part of a comprehensive, well-organised, and well-resourced elimination programme, DP MDA can be a useful additional tool to accelerate malaria elimination.
|
|
| 10. |
- Winterlich, Meghan, et al.
(författare)
-
A biocompatible ZnNa2-based metal-organic framework with high ibuprofen, nitric oxide and metal uptake capacity
- 2020
-
Ingår i: Materials Advances. - : Royal Society of Chemistry (RSC). - 2633-5409. ; 1:7, s. 2248-2260
-
Tidskriftsartikel (refereegranskat)abstract
- Metal organic frameworks (MOFs) have received significant attention in recent years in the areas of biomedical and environmental applications. Among them, mixed metal MOFs, although promising, are relatively few in number in comparison with their homometallic analogues. The employment of benzophenone-4,4'-dicarboxylic acid (bphdcH(2)) in mixed metal MOF chemistry provided access to a 3D MOF, [Na2Zn(bphdc)(2)(DMF)(2)](n) (NUIG1). NUIG1 displays a new topology and is a rare example of a mixed metal MOF based on 1D rod secondary building units. UV-vis, HPLC, TGA, XRPD, solid state NMR and computational studies indicated that NUIG1 exhibits an exceptionally high Ibuprofen (Ibu) and nitric oxide adsorption capacity. The MCF-7 cell line was used to assess the toxicity of NUIG1 and Ibu@NUIG1, revealing that both species are non-toxic (cell viability > 70%). NUIG1 exhibits good performance in the adsorption of metal ions (Co-II, Ni-II, Cu-II) from aqueous environments, as was demonstrated by UV-vis, EDX, ICP, SEM and direct and alternate current magnetic susceptibility studies. The colour and the magnetic properties of the M@NUIG1 species depend strongly on the kind and the amount of the encapsulated metal ion in the MOF pores.
|
|
| 11. |
- Aleksis, Rihards, et al.
(författare)
-
Artefact-free broadband 2D NMR for separation of quadrupolar and paramagnetic shift interactions
- 2019
-
Ingår i: Solid State Nuclear Magnetic Resonance. - : Elsevier BV. - 0926-2040 .- 1527-3326. ; 101, s. 51-62
-
Tidskriftsartikel (refereegranskat)abstract
- Two new two-dimensional, broadband, solid-state NMR experiments for separating and correlating the quadrupolar and shift interactions of spin I = 1 nuclei in paramagnetic systems are proposed. The new pulse sequences incorporate the short, high-power adiabatic pulses (SHAPs) into the shifting d-echo experiment of Walder et al. [J. Chem. Phys., 142, 014201 (2015)], in two different ways, giving double and quadruple adiabatic shifting d-echo sequences. These new experiments have the advantage over previous methods of both suppressing spectral artefacts due to pulse imperfections, and exhibiting a broader excitation bandwidth. Both experiments are analysed with theoretical calculations and simulations, and are applied experimentally to the H-2 NMR of deuterated CuCl2 center dot 2H(2)O, and two deuterated samples of the ion conductor oxyhydride BaTiO3-xHy prepared using two different methods. For the CuCl2 center dot 2H(2)O sample, both new methods obtain very high-quality spectra from which the parameters describing the shift and quadrupolar interaction tensors, and their relative orientation, were extracted. The two BaTiO3-xHy samples exhibited different local hydride environments with different tensor parameters. The H-2 spectra of these oxyhydrides exhibit inhomogeneous broadening of the H-2 shifts, and so whilst the quadrupolar interaction parameters were easily extracted, the measurement of the shift parameters was more complex. However, effective shift parameters were extracted, which combine the effects of both the paramagnetic shift tensor and the inhomogeneous broadening.
|
|
| 12. |
- Aleksis, Rihards, et al.
(författare)
-
Probing the electronic structure and hydride occupancy in barium titanium oxyhydride through DFT-assisted solid-state NMR
- 2022
-
Ingår i: Physical Chemistry, Chemical Physics - PCCP. - 1463-9076 .- 1463-9084. ; 24:46, s. 28164-28173
-
Tidskriftsartikel (refereegranskat)abstract
- Perovskite-type oxhydrides such as BaTiO3−xHy exhibit mixed hydride ion and electron conduction and are an attractive class of materials for developing energy storage devices. However, the underlying mechanism of electric conductivity and its relation to the composition of the material remains unclear. Here we report detailed insights into the hydride local environment, the electronic structure and hydride conduction dynamics of barium titanium oxyhydride. We demonstrate that DFT-assisted solid-state NMR is an excellent tool for differentiating between the different feasible electronic structures in these solids. Our results indicate that upon reduction of BaTiO3 the introduced electrons are delocalized among all Ti atoms forming a bandstate. Furthermore, each vacated anion site is reoccupied by at most a single hydride, or else remains vacant. This single occupied bandstate structure persists at different hydrogen concentrations (y = 0.13–0.31) and a wide range of temperatures (∼100–300 K).
|
|
| 13. |
- Carvalho, José P., et al.
(författare)
-
Frequency-swept adiabatic pulses for broadband solid-state MAS NMR
- 2021
-
Ingår i: Journal of magnetic resonance. - : Elsevier BV. - 1090-7807 .- 1096-0856. ; 324
-
Tidskriftsartikel (refereegranskat)abstract
- We present a complete description of frequency-swept adiabatic pulses applied to isolated spin-1/2 nuclei with a shift anisotropy in solid materials under magic-angle spinning. Our theoretical framework unifies the existing descriptions of adiabatic pulses in the high-power regime, where the radiofrequency (RF) amplitude is greater than twice the spinning frequency, and the low-power regime, where the RF power is less than the spinning frequency, and so links the short high-powered adiabatic pulse (SHAP) and single-sideband-selective adiabatic pulses (S3AP) schemes used in paramagnetic solid-state NMR. We also identify a hitherto unidentified third regime intermediate between the low- and high-power regimes, and separated from them by rotary resonance conditions. We show that the prevailing benchmark of inversion performance based on (super) adiabatic factors is only applicable in the high- and intermediate-power regimes, but fails to account both for the poor performance at rotary resonance, and the impressive inversion seen in the low-power regime. For low-power pulses, which are non-adiabatic according to this definition of (super) adiabaticity, the effective Floquet Hamiltonian in the jolting frame reveals “hidden” (super) adiabaticity. The theory is demonstrated using a combination of simulation and experiment, and is used to refine the practical recommendations for the experimentalist who wishes to use these pulses.
|
|
| 14. |
- Carvalho, José P., et al.
(författare)
-
Half-integer-spin quadrupolar nuclei in magic-angle spinning paramagnetic NMR : The case of NaMnO2
-
Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- A combination of solid-state NMR methods for the extraction of shift and quadrupolar parameters for half-integer nuclei in the structurally complex NaMnO2 Na-ion cathode material, under magic-angle spinning (MAS) is presented. We show that the integration of the Magic-Angle Turning experiment with Rotor-Assisted Population transfer can be used both to identify shifts and to extract a range of magnitudes for their quadrupolar coupling. We also demonstrate the applicability of the the two-dimensional one pulse (TOP) based double-sheared Satellite Transition Magic-Angle Spinning (TOP-STMAS) showing how it can yield a spectrum with separated shift and second-order quadrupolar anisotropies, which in turn can be used to analyse a quadrupolar lineshape free of bulk magnetic susceptibility induced shift dispersion and determine both isotropic shift and quadrupolar products. Combining all these experiments, the shift and quadrupolar parameters for all observed Na environments were extracted and yielded excellent agreement with the density functional theory (DFT) based models that were reported in previous literature. We expect these methods to open the door for new possibilities for solid-state NMR to probe half-integer quadrupolar nuclei in paramagnetic materials and other systems exhibiting large shift dispersion.
|
|
| 15. |
- Carvalho, José P., et al.
(författare)
-
Half-integer-spin quadrupolar nuclei in magic-angle spinning paramagnetic NMR : The case of NaMnO2
- 2022
-
Ingår i: Journal of magnetic resonance. - : Elsevier BV. - 1090-7807 .- 1096-0856. ; 340
-
Tidskriftsartikel (refereegranskat)abstract
- A combination of solid-state NMR methods for the extraction of 23Na shift and quadrupolar parameters in the as-synthesized, structurally complex NaMnO2 Na-ion cathode material, under magic-angle spinning (MAS) is presented. We show that the integration of the Magic-Angle Turning experiment with Rotor-Assisted Population transfer (RAPT) can be used both to identify shifts and to extract a range of magnitudes for their quadrupolar couplings. We also demonstrate the applicability of the two-dimensional one pulse (TOP) based double-sheared Satellite Transition Magic-Angle Spinning (TOP-STMAS) showing how it can yield a spectrum with separated shift and second-order quadrupolar anisotropies, which in turn can be used to analyze a quadrupolar lineshape free of anisotropic bulk magnetic susceptibility (ABMS) induced shift dispersion and determine both isotropic shift and quadrupolar products. Combining all these experiments, the shift and quadrupolar parameters for all observed Na environments were extracted and yielded excellent agreement with the density functional theory (DFT) based models that were reported in previous literature. We expect these methods to open the door for new possibilities for solid-state NMR to probe half-integer quadrupolar nuclei in paramagnetic materials and other systems exhibiting large shift dispersion.
|
|
| 16. |
- Carvalho, José P., 1993-
(författare)
-
Probing Paramagnetic Systems by Solid-State NMR Spectroscopy
- 2022
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Paramagnetic systems have a wide range of applications ranging from energy storage or conversion to catalytic processes, metalloproteins and light-emitting materials. Over the recent years nuclear magnetic resonance (NMR) spectroscopy has become an established tool for studying the structural and electronic properties of these systems, largely because it can provide a link between the structure and the bulk properties. This progress was only possible due to improved probe technology and better radiofrequency irradiation schemes, since the hyperfine interaction between nuclei and the unpaired electrons generally hampers both the acquisition and interpretation of the spectra and, therefore, techniques that are standard for diamagnetic systems often perform poorly when applied to paramagnetic systems.The aim of the present thesis is to continue the development of solid-state paramagnetic NMR and address some of the remaining limitations and bottlenecks in the acquisition and spectral interpretation. One specific area for which great improvements have been seen is the development of new broadband excitation and inversion sequences for systems under Magic-Angle Spinning (MAS) which employ adiabatic pulses. In this work, we provide a more rigorous understanding of the adiabatic pulses in solid-state MAS NMR applicable to both the design of new and improved pulse schemes, and their application in studies of an increased variety of systems, whilst avoiding potential implementation pitfalls.We also demonstrate how a thorough understanding of the hyperfine interaction combined with quantum chemistry calculations can link bulk magnetic properties and magnetic resonance signatures both in solid-state NMR and Electron Paramagnetic Resonance (EPR), thus providing an accurate description of the geometry and electronic configuration of an organoytterbium complex with applications in heterogeneous catalysis.Lastly, we explore the development of methods suitable for quadrupolar nuclei (spin I>1/2) in paramagnetic systems which have, so far, lagged behind their spin 1/2 counterparts. We focus more specifically on half-integer quadrupoles for which we propose a new method of processing Multiple-Quantum and Satellite-Transition MAS spectra which permits the separation of shift and quadrupolar interactions into orthogonal dimensions and evaluate the performance and limitations of the state-of-the-art methods for extraction of both quadrupolar and shift anisotropy tensor parameters on structurally complex systems.We anticipate that the work developed throughout this thesis can help extend the fields of application of solid-state paramagnetic NMR.
|
|
| 17. |
- Carvalho, José P., et al.
(författare)
-
Separation of quadrupolar and paramagnetic shift interactions with TOP-STMAS/MQMAS in solid-state lighting phosphors
- 2020
-
Ingår i: Magnetic Resonance in Chemistry. - : Wiley. - 0749-1581 .- 1097-458X. ; 58:11, s. 1055-1070
-
Tidskriftsartikel (refereegranskat)abstract
- A new approach for processing satellite-transition magic-angle spinning(STMAS) and multiple-quantum magic-angle spinning (MQMAS) data, basedon the two-dimensional one-pulse (TOP) method, which separates thesecond-rank quadrupolar anisotropy and paramagnetic shift interactions viaa double shearing transformation, is described. This method is particularlyrelevant in paramagnetic systems, where substantial inhomogeneous broadeningmay broaden the lineshapes. Furthermore, it possesses an advantage overthe conventional processing of MQMAS and STMAS spectra because it overcomesthe limitation on the spectral width in the indirect dimension imposedby rotor synchronization of the sampling interval. This method was appliedexperimentally to the 27Al solid-state nuclear magnetic resonance of a seriesof yttrium aluminum garnets (YAGs) doped with different lanthanide ions,from which the quadrupolar parameters of paramagnetically shifted and bulkunshifted sites were extracted. These parameters were then compared withdensity functional theory calculations, which permitted a better understandingof the local structure of Ln substituent ions in the YAG lattice.
|
|
| 18. |
|
|
| 19. |
|
|
| 20. |
- Etman, Ahmed S., et al.
(författare)
-
Insights into the Exfoliation Process of V2O5· nH2O Nanosheet Formation Using Real-Time 51V NMR
- 2019
-
Ingår i: ACS Omega. - : American Chemical Society (ACS). - 2470-1343. ; 4:6, s. 10899-10905
-
Tidskriftsartikel (refereegranskat)abstract
- Copyright © 2019 American Chemical Society. Nanostructured hydrated vanadium oxides (V2O5·nH2O) are actively being researched for applications in energy storage, catalysis, and gas sensors. Recently, a one-step exfoliation technique for fabricating V2O5·nH2O nanosheets in aqueous media was reported; however, the underlying mechanism of exfoliation has been challenging to study. Herein, we followed the synthesis of V2O5·nH2O nanosheets from the V2O5 and VO2 precursors in real time using solution- and solid-state 51V NMR. Solution-state 51V NMR showed that the aqueous solution contained mostly the decavanadate anion [H2V10O28]4- and the hydrated dioxovanadate cation [VO2·4H2O]+, and during the exfoliation process, decavanadate was formed, while the amount of [VO2·4H2O]+ remained constant. The conversion of the solid precursor V2O5, which was monitored with solid-state 51V NMR, was initiated when VO2 was in its monoclinic forms. The dried V2O5·nH2O nanosheets were weakly paramagnetic because of a minor content of isolated V4+. Its solid-state 51V signal was less than 20% of V2O5 and arose from diamagnetic V4+ or V5+.This study demonstrates the use of real-time NMR techniques as a powerful analysis tool for the exfoliation of bulk materials into nanosheets. A deeper understanding of this process will pave the way to tailor these important materials. ©
|
|
| 21. |
|
|
| 22. |
|
|
| 23. |
- Georgouvelas, Dimitrios, et al.
(författare)
-
Residual Lignin and Zwitterionic Polymer Grafts on Cellulose Nanocrystals for Antifouling and Antibacterial Applications
- 2020
-
Ingår i: ACS APPLIED POLYMER MATERIALS. - : American Chemical Society (ACS). - 2637-6105. ; 2:8, s. 3060-3071
-
Tidskriftsartikel (refereegranskat)abstract
- Hybrid materials from nanocellulose, lignin, and surface- grafted zwitterionic poly(sulfobetaine methacrylate) (PSBMA) chains are prepared to attain antifouling bio-based nanomaterials with enhanced antibacterial performance. The grafting of PSBMA from both cellulose and lignocellulose nanocrystals (CNC and LCNC, respectively) is attempted; however, the materials' analysis with FTIR, XPS, and solid-state C-13 NMR reveals that the grafting on LCNC is negligible. Antifouling and antibacterial performances of CNC and LCNC, as well as PSBMA-grafted CNC, are evaluated by using quartz crystal microbalance with dissipation monitoring, confocal microscopy, and the agar diffusion method using bovine serum albumin and E. coli ACTT 8937 as protein model and bacterial model, respectively. The results demonstrate that the grafting of CNC with PSBMA improves the antifouling and antibacterial activity of the material compared to pristine CNC and LCNC.
|
|
| 24. |
- Kohlhauer, M., et al.
(författare)
-
Protection against cardiac ischemia-reperfusion injury by hypothermia and by inhibition of succinate accumulation and oxidation is additive
- 2019
-
Ingår i: Basic Research in Cardiology. - : Springer Science and Business Media LLC. - 0300-8428 .- 1435-1803. ; 114:3
-
Tidskriftsartikel (refereegranskat)abstract
- Hypothermia induced at the onset of ischemia is a potent experimental cardioprotective strategy for myocardial infarction. The aim of our study was to determine whether the beneficial effects of hypothermia may be due to decreasing mitochondria-mediated mechanisms of damage that contribute to the pathophysiology of ischemia/reperfusion injury. New Zealand male rabbits were submitted to 30min of myocardial ischemia with hypothermia (32 degrees C) induced by total liquid ventilation (TLV). Hypothermia was applied during ischemia alone (TLV group), during ischemia and reperfusion (TLV-IR group) and normothermia (Control group). In all the cases, ischemia was performed by surgical ligation of the left anterior descending coronary artery and was followed by 3h of reperfusion before assessment of infarct size. In a parallel study, male C57BL6/J mice underwent 30min myocardial ischemia followed by reperfusion under either normothermia (37 degrees C) or conventionally induced hypothermia (32 degrees C). In both the models, the levels of the citric acid cycle intermediate succinate, mitochondrial complex I activity were assessed at various times. The benefit of hypothermia during ischemia on infarct size was compared to inhibition of succinate accumulation and oxidation by the complex II inhibitor malonate, applied as the pro-drug dimethyl malonate under either normothermic or hypothermic conditions. Hypothermia during ischemia was cardioprotective, even when followed by normothermic reperfusion. Hypothermia during ischemia only, or during both, ischemia and reperfusion, significantly reduced infarct size (2.8 +/- 0.6%, 24.2 +/- 3.0% and 49.6 +/- 2.6% of the area at risk, for TLV-IR, TLV and Control groups, respectively). The significant reduction of infarct size by hypothermia was neither associated with a decrease in ischemic myocardial succinate accumulation, nor with a change in its rate of oxidation at reperfusion. Similarly, dimethyl malonate infusion and hypothermia during ischemia additively reduced infarct size (4.8 +/- 2.2% of risk zone) as compared to either strategy alone. Hypothermic cardioprotection is neither dependent on the inhibition of succinate accumulation during ischemia, nor of its rapid oxidation at reperfusion. The additive effect of hypothermia and dimethyl malonate on infarct size shows that they are protective by distinct mechanisms and also suggests that combining these different therapeutic approaches could further protect against ischemia/reperfusion injury during acute myocardial infarction.
|
|
| 25. |
|
|
| 26. |
|
|
| 27. |
- Mondal, Arobendo, et al.
(författare)
-
Large-Scale Computation of Nuclear Magnetic Resonance Shifts for Paramagnetic Solids Using CP2K
- 2018
-
Ingår i: Journal of Chemical Theory and Computation. - : American Chemical Society (ACS). - 1549-9618 .- 1549-9626. ; 14:1, s. 377-394
-
Tidskriftsartikel (refereegranskat)abstract
- Large-scale computations of nuclear magnetic resonance (NMR) shifts for extended paramagnetic solids (pNMR) are reported using the highly efficient Gaussian-augmented plane-wave implementation of the CP2K code. Combining hyperfine couplings obtained with hybrid functionals with g-tensors and orbital shieldings computed using gradient-corrected functionals, contact, pseudocontact, and orbital-shift contributions to pNMR shifts are accessible. Due to the efficient and highly parallel performance of CP2K, a wide variety of materials with large unit cells can be studied with extended Gaussian basis sets. Validation of various approaches for the different contributions to pNMR shifts is done first for molecules in a large supercell in comparison with typical quantum-chemical codes. This is then extended to a detailed study of g-tensors for extended solid transition-metal fluorides and for a series of complex lithium vanadium phosphates. Finally, lithium pNMR shifts are computed for Li3V2(PO4)(3), for which detailed experimental data are available. This has allowed an in-depth study of different approaches (e.g., full periodic versus incremental cluster computations of g-tensors and different functionals and basis sets for hyperfine computations) as well as a thorough analysis of the different contributions to the pNMR shifts. This study paves the way for a more-widespread computational treatment of NMR shifts for paramagnetic materials.
|
|
| 28. |
- Papawassiliou, Wassilios, et al.
(författare)
-
Crystal and electronic facet analysis of ultrafine Ni2P particles by solid-state NMR nanocrystallography
- 2021
-
Ingår i: Nature Communications. - : Springer Science and Business Media LLC. - 2041-1723. ; 12:1
-
Tidskriftsartikel (refereegranskat)abstract
- Structural and morphological control of crystalline nanoparticles is crucial in the field of heterogeneous catalysis and the development of reaction specific catalysts. To achieve this, colloidal chemistry methods are combined with ab initio calculations in order to define the reaction parameters, which drive chemical reactions to the desired crystal nucleation and growth path. Key in this procedure is the experimental verification of the predicted crystal facets and their corresponding electronic structure, which in case of nanostructured materials becomes extremely difficult. Here, by employing P-31 solid-state nuclear magnetic resonance aided by advanced density functional theory calculations to obtain and assign the Knight shifts, we succeed in determining the crystal and electronic structure of the terminating surfaces of ultrafine Ni2P nanoparticles at atomic scale resolution. Our work highlights the potential of ssNMR nanocrystallography as a unique tool in the emerging field of facet-engineered nanocatalysts. Structural and morphological control of crystalline nanoparticles is crucial in heterogeneous catalysis. Applying DFT-assisted solid-state NMR spectroscopy, we determine the surface crystal and electronic structure of Ni2P nanoparticles, unveiling NMR nanocrystallography as an emerging tool in facet-engineered nanocatalysts.
|
|
| 29. |
- Papawassiliou, Wassilios, 1991-, et al.
(författare)
-
Detection of Weyl fermions and the metal to Weyl-semimetal phase transition in WTe2via broadband high resolution NMR
- 2022
-
Ingår i: Physical Review Research. - 2643-1564. ; 4:3
-
Tidskriftsartikel (refereegranskat)abstract
- Weyl fermions (WFs) in the type-II Weyl semimetal (WSM) WTe2 are difficult to resolve experimentally because the Weyl bands disperse in an extremely narrow region of the (E−k) space. Here, by using DFT-assisted high-resolution 125Te solid-state nuclear magnetic resonance (ssNMR) in the temperature range 50–700 K, we succeeded in detecting low energy WF excitations and monitoring their evolution with temperature. Remarkably, WFs are observed to emerge at T∼120 K, while at lower temperatures WTe2 behaves as a trivial metal. This intriguing phenomenon is induced by the rapid raise of the Fermi level upon heating, which crosses the Weyl bands only for T>120 K. The abrupt change of the NMR parameters at this temperature is signature of a topological Lifshitz transition instead of a cursive energy-bands crossing.
|
|
| 30. |
- Papawassiliou, Wassilios, 1991-, et al.
(författare)
-
Emergent Weyl Fermions and the Metal to Weyl-Semimetal phase transition in WTe2,via broadband High Resolution NMR
-
Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Weyl Fermions (WFs) in the type-II Weyl Semimetal (WSM) WTe2 are difficult to resolve experimentally because the Weyl bands disperse in an extremely narrow region of the (E-k) space. Here, by using DFT-assisted high-resolution 125Te solid-state NMR (ssNMR) in the temperature range 50K - 700K, we succeeded in detecting low energy WF excitations and monitor their evolution with temperature. Remarkably, WFs appear to emerge at T∼120K; at lower temperatures WTe2 behaves as a metal. This intriguing metal-to-WSM phase transition is shown to be induced by the rapid raise of the Fermi level with temperature, crossing solely the electron and hole pockets in the low-T metallic phase, while crossing the Weyl bands near the nodal points - a prerequisite for the emergence of WFs - only for T>120K.
|
|
| 31. |
- Pell, Andrew J., et al.
(författare)
-
Paramagnetic NMR in solution and the solid state
- 2019
-
Ingår i: Progress in nuclear magnetic resonance spectroscopy. - : Elsevier BV. - 0079-6565 .- 1873-3301. ; 111, s. 1-271
-
Forskningsöversikt (refereegranskat)abstract
- The field of paramagnetic NMR has expanded considerably in recent years. This review addresses both the theoretical description of paramagnetic NMR, and the way in which it is currently practised. We provide a review of the theory of the NMR parameters of systems in both solution and the solid state. Here we unify the different languages used by the NMR, EPR, quantum chemistry/DFT, and magnetism communities to provide a comprehensive and coherent theoretical description. We cover the theory of the paramagnetic shift and shift anisotropy in solution both in the traditional formalism in terms of the magnetic susceptibility tensor, and using a more modern formalism employing the relevant EPR parameters, such as are used in first-principles calculations. In addition we examine the theory first in the simple non-relativistic picture, and then in the presence of spin-orbit coupling. These ideas are then extended to a description of the paramagnetic shift in periodic solids, where it is necessary to include the bulk magnetic properties, such as magnetic ordering at low temperatures. The description of the paramagnetic shift is completed by describing the current understanding of such shifts due to lanthanide and actinide ions. We then examine the paramagnetic relaxation enhancement, using a simple model employing a phenomenological picture of the electronic relaxation, and again using a more complex state-of-the-art theory which incorporates electronic relaxation explicitly. An additional important consideration in the solid state is the impact of bulk magnetic susceptibility effects on the form of the spectrum, where we include some ideas from the field of classical electrodynamics. We then continue by describing in detail the solution and solid-state NMR methods that have been deployed in the study of paramagnetic systems in chemistry, biology, and the materials sciences. Finally we describe a number of case studies in paramagnetic NMR that have been specifically chosen to highlight how the theory in part one, and the methods in part two, can be used in practice. The systems chosen include small organometallic complexes in solution, solid battery electrode materials, metalloproteins in both solution and the solid state, systems containing lanthanide ions, and multi-component materials used in pharmaceutical controlled-release formulations that have been doped with paramagnetic species to measure the component domain sizes.
|
|
| 32. |
- Pnevmatikatos, Dionisios N., et al.
(författare)
-
FASTER: Facilitating Analysis and Synthesis Technologies for Effective Reconfiguration
- 2015
-
Ingår i: Microprocessors and Microsystems. - : Elsevier BV. - 0141-9331. ; 39:4-5, s. 321-338
-
Tidskriftsartikel (refereegranskat)abstract
- The FASTER (Facilitating Analysis and Synthesis Technologies for Effective Reconfiguration) EU FP7 project, aims to ease the design and implementation of dynamically changing hardware systems. Our motivation stems from the promise reconfigurable systems hold for achieving high performance and extending product functionality and lifetime via the addition of new features that operate at hardware speed. However, designing a changing hardware system is both challenging and time-consuming. FASTER facilitates the use of reconfigurable technology by providing a complete methodology enabling designers to easily specify, analyze, implement and verify applications on platforms with general-purpose processors and acceleration modules implemented in the latest reconfigurable technology. Our tool-chain supports both coarse- and fine-grain FPGA reconfiguration, while during execution a flexible run-time system manages the reconfigurable resources. We target three applications from different domains. We explore the way each application benefits from reconfiguration, and then we asses them and the FASTER tools, in terms of performance, area consumption and accuracy of analysis.
|
|
| 33. |
- Sanders, Kevin J., et al.
(författare)
-
Broadband MAS NMR spectroscopy in the low-power limit
- 2018
-
Ingår i: Chemical Physics Letters. - : Elsevier BV. - 0009-2614 .- 1873-4448. ; 697, s. 29-37
-
Tidskriftsartikel (refereegranskat)abstract
- We investigate the performance of broadband adiabatic inversion pulses in the high-power (short high-powered adiabatic pulse, SHAP) and low-power (single-sideband-selective adiabatic pulse, S(3)AP) RF regimes on a spin system subjected to large anisotropic interactions. We show by combined experimental results and spin dynamics simulations that when the magic-angle spinning rate exceeds 100 kHz S(3)APs begin outperforming SHAPs. This is especially true for low-gamma nuclei, such as Li-6 in paramagnetic Li-ion battery materials. Finally, we show how S3APs can be improved by combining multiple waveforms sweeping over multiple sidebands simultaneously, in order to produce inverted sideband profiles free from intensity biasing.
|
|
| 34. |
- Seymour, Ieuan D., et al.
(författare)
-
Characterizing Oxygen Local Environments in Paramagnetic Battery Materials via O-17 NMR and DFT Calculations
- 2016
-
Ingår i: Journal of the American Chemical Society. - : American Chemical Society (ACS). - 0002-7863 .- 1520-5126. ; 138:30, s. 9405-9408
-
Tidskriftsartikel (refereegranskat)abstract
- Experimental techniques that probe the local environment around O in paramagnetic Li-ion cathode materials are essential in order to understand the complex phase transformations and O redox processes that can occur during electrochemical delithiation. While Li NMR is a well-established technique for studying the local environment of Li ions in paramagnetic battery materials, the use of O-17 NMR in the same materials has not yet been reported. In this work, we present a combined O-17 NMR and hybrid density functional theory study of the local O environments in Li2MnO3, a model compound for layered Li-ion batteries. After a simple O-17 enrichment procedure, we observed five resonances with large O-17 shifts ascribed to the Fermi contact interaction with directly bonded Mn4+ ions. The five peaks were separated into two groups with shifts at 1600 to 1950 ppm and 2100 to 2450 ppm, which, -with the aid of first principles calculations, were assigned to the O-17 shifts of environments similar to the 4i and 8j sites in pristine Li2MnO3, respectively. The multiple O environments in each region were ascribed to the presence of stacking faults within the Li2MnO3 structure. From the ratio of the intensities of the different O-17 environments, the percentage of stacking faults was found to be ca. 10%. The methodology for studying (17)Oshifts in paramagnetic solids described in this work will be useful for studying the local environments of O in a range of technologically interesting transition metal oxides.
|
|
| 35. |
- Strawbridge, Rona J., et al.
(författare)
-
The overlap of genetic susceptibility to schizophrenia and cardiometabolic disease can be used to identify metabolically different groups of individuals
- 2021
-
Ingår i: Scientific Reports. - : Springer Nature. - 2045-2322. ; 11:1
-
Tidskriftsartikel (refereegranskat)abstract
- Understanding why individuals with severe mental illness (Schizophrenia, Bipolar Disorder and Major Depressive Disorder) have increased risk of cardiometabolic disease (including obesity, type 2 diabetes and cardiovascular disease), and identifying those at highest risk of cardiometabolic disease are important priority areas for researchers. For individuals with European ancestry we explored whether genetic variation could identify sub-groups with different metabolic profiles. Loci associated with schizophrenia, bipolar disorder and major depressive disorder from previous genome-wide association studies and loci that were also implicated in cardiometabolic processes and diseases were selected. In the IMPROVE study (a high cardiovascular risk sample) and UK Biobank (general population sample) multidimensional scaling was applied to genetic variants implicated in both psychiatric and cardiometabolic disorders. Visual inspection of the resulting plots used to identify distinct clusters. Differences between these clusters were assessed using chi-squared and Kruskall-Wallis tests. In IMPROVE, genetic loci associated with both schizophrenia and cardiometabolic disease (but not bipolar disorder or major depressive disorder) identified three groups of individuals with distinct metabolic profiles. This grouping was replicated within UK Biobank, with somewhat less distinction between metabolic profiles. This work focused on individuals of European ancestry and is unlikely
|
|
| 36. |
|
|
| 37. |
|
|
