13 research outputs found

    Electrosynthesis of Co-ZIF Using Bio-Derived Solvents: Electrochemical Evaluation of Synthesised MOFs as a Binder-Free Supercapacitor Electrode in Alkaline Electrolyte

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    Supercapacitors hold promise for energy storage due to their exceptional power density and fast charge/discharge cycles. However, their performance hinges on the electrode material. Zeolitic imidazolate frameworks (ZIFs) are attractive options due to their tailorable structure and high surface area. But traditional ZIF synthesis relies on toxic solvents derived from fossil fuels, hindering their envisioned environmental benefit. This study explores using bio-derived solvents for a greener and potentially superior approach. The researchers employed anodic electrodeposition to synthesise cobalt-based ZIFs (Co-ZIFs) as supercapacitor electrode materials. Two linkers (2-methylimidazole and benzimidazole) and two bio-derived solvents (CyreneTM and Îł-valerolactone (GVL)) were investigated. X-ray diffraction analysis revealed that bio-derived solvents enhanced the crystallinity of Co-ZIFs compared to traditional solvents. Notably, CyreneTM promoted better crystallinity for Co-bIM/Co-mIM structures. The Full Width at Half Maximum (FWHM) analysis suggests CyreneTM promotes Co-bIM/Co-mIM crystallinity (lower FWHM). Co-mIM in CyreneTM exhibits the best crystallinity (FWHM = 0.233) compared to other ZIF samples. Scanning electron microscopy confirmed these findings, showing larger and well-defined crystals for bio-derived solvent-synthesised ZIFs. The choice of solvent significantly impacted the final ZIF structure. While 2-methylimidazole consistently formed ZIF-67 regardless of the solvent, benzimidazole exhibited solvent-dependent behaviour. GVL yielded the highly porous Co-ZIF-12 structure, whereas DMF (N,N-dimethylformamide) and CyreneTM produced the less porous ZIF-9. This work reports the first-ever instance of ZIF-12 synthesis via an electrochemical method, highlighting the crucial interplay between solvent and precursor molecule in determining the final ZIF product. The synthesised binder-free Co-ZIF electrodes were evaluated for supercapacitor performance. The capacitance data revealed GVL as the most effective solvent, followed by DMF and then CyreneTM. This suggests GVL is the preferred choice for this reaction due to its superior performance. The ZIF-12-based electrode exhibits an impressive specific capacitance (Csp) of 44 F g⁻1, significantly higher than those achieved by ZIF-9-Cyrene (1.2 F g⁻1), ZIF-9-DMF (2.5 F g⁻1), ZIF-67-GVL (35 F g⁻1), ZIF-67-Cyrene (6 F g⁻1), and ZIF-67-DMF (16 F g⁻1) at 1 A g−1. This surpasses the Csp of all other ZIFs studied, including high-performing ZIF-67(GVL). ZIF-12(GVL) maintained superior Csp even at higher current densities, demonstrating exceptional rate capability. Among the bio-derived solvents, GVL outperformed CyreneTM. Notably, the Co-bIM in the GVL sample exhibited a ZIF-12-like structure, offering potential advantages due to its larger pores and potentially higher surface area compared to traditional ZIF-67 and ZIF-9 structures. This work presents a significant advancement in Co-ZIF synthesis. By utilising bio-derived solvents, it offers a more sustainable and potentially superior alternative. This paves the way for the eco-friendly production of Co-ZIFs with improved properties for supercapacitors, gas separation, catalysis, and other applications

    Two Candidate High-Redshift X-ray Jets Without Coincident Radio Jets

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    We report the detection of extended X-ray emission from two high-redshift radio quasars. These quasars, J1405+0415 at zz=3.208 and J1610+1811 at zz=3.118, were observed in a Chandra snapshot survey selected from a complete sample of the radio-brightest quasars in the overlap area of the VLA-FIRST radio survey and the Sloan Digital Sky Survey. The extended X-ray emission is located along the line connecting the core to a radio knot or hotspot, favoring the interpretation of X-ray jets. The inferred rest frame jet X-ray luminosities from 2--30 keV would be of order 1045^{45} erg~s−1^{-1} if emitted isotropically and without relativistic beaming. In the scenario of inverse Compton scattering of the cosmic microwave background (CMB), X-ray jets without a coincident radio counterpart may be common, and should be readily detectable to redshifts even beyond 3.2 due to the (1+zz)4^4 increase of the CMB energy density compensating for the (1+zz)−4^{-4} cosmological diminution of surface brightness. If these can be X-ray confirmed, they would be the second and third examples of quasar X-ray jets without detection of underlying continuous radio jets.Comment: 10 pages, 4 figures. Accepted for publication in The Astrophysical Journa

    Genome-Wide Association Study Identifies First Locus Associated with Susceptibility to Cerebral Venous Thrombosis

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    Objective Cerebral venous thrombosis (CVT) is an uncommon form of stroke affecting mostly young individuals. Although genetic factors are thought to play a role in this cerebrovascular condition, its genetic etiology is not well understood. Methods A genome-wide association study was performed to identify genetic variants influencing susceptibility to CVT. A 2-stage genome-wide study was undertaken in 882 Europeans diagnosed with CVT and 1,205 ethnicity-matched control subjects divided into discovery and independent replication datasets. Results In the overall case-control cohort, we identified highly significant associations with 37 single nucleotide polymorphisms (SNPs) within the 9q34.2 region. The strongest association was with rs8176645 (combined p = 9.15 x 10(-24); odds ratio [OR] = 2.01, 95% confidence interval [CI] = 1.76-2.31). The discovery set findings were validated across an independent European cohort. Genetic risk score for this 9q34.2 region increases CVT risk by a pooled estimate OR = 2.65 (95% CI = 2.21-3.20, p = 2.00 x 10(-16)). SNPs within this region were in strong linkage disequilibrium (LD) with coding regions of the ABO gene. The ABO blood group was determined using allele combination of SNPs rs8176746 and rs8176645. Blood groups A, B, or AB, were at 2.85 times (95% CI = 2.32-3.52, p = 2.00 x 10(-16)) increased risk of CVT compared with individuals with blood group O. Interpretation We present the first chromosomal region to robustly associate with a genetic susceptibility to CVT. This region more than doubles the likelihood of CVT, a risk greater than any previously identified thrombophilia genetic risk marker. That the identified variant is in strong LD with the coding region of the ABO gene with differences in blood group prevalence provides important new insights into the pathophysiology of CVT. ANN NEUROL 2021Peer reviewe

    Genetic variants influencing elevated myeloperoxidase levels increase risk of stroke

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    Primary intracerebral haemorrhage and lacunar ischaemic stroke are acute manifestations of progressive cerebral microvascular disease. Current paradigms suggest atherosclerosis is a chronic, dynamic, inflammatory condition precipitated in response to endothelial injury from various environmental challenges. Myeloperoxidase plays a central role in initiation and progression of vascular inflammation, but prior studies linking myeloperoxidase with stroke risk have been inconclusive. We hypothesized that genetic determinants of myeloperoxidase levels influence the development of vascular instability, leading to increased primary intracerebral haemorrhage and lacunar stroke risk. We used a discovery cohort of 1409 primary intracerebral haemorrhage cases and 1624 controls from three studies, an extension cohort of 12 577 ischaemic stroke cases and 25 643 controls from NINDSSiGN, and a validation cohort of 10 307 ischaemic stroke cases and 29 326 controls from METASTROKE Consortium with genome-wide genotyping to test this hypothesis. A genetic risk score reflecting elevated myeloperoxidase levels was constructed from 15 common single nucleotide polymorphisms identified from prior genome-wide studies of circulating myeloperoxidase levels (P55 - 10 6). This genetic risk score was used as the independent variable in multivariable regression models for association with primary intracerebral haemorrhage and ischaemic stroke subtypes. We used fixed effects meta-analyses to pool estimates across studies. We also used Cox regression models in a prospective cohort of 174 primary intracerebral haemorrhage survivors for association with intracerebral haemorrhage recurrence. We present effects of myeloperoxidase elevating single nucleotide polymorphisms on stroke risk per risk allele, corresponding to a one allele increase in the myeloperoxidase increasing genetic risk score. Genetic determinants of elevated circulating myeloperoxidase levels were associated with both primary intracerebral haemorrhage risk (odds ratio, 1.07, P = 0.04) and recurrent intracerebral haemorrhage risk (hazards ratio, 1.45, P = 0.006). In analysis of ischaemic stroke subtypes, the myeloperoxidase increasing genetic risk score was strongly associated with lacunar subtype only (odds ratio, 1.05, P = 0.0012). These results, demonstrating that common genetic variants that increase myeloperoxidase levels increase risk of primary intracerebral haemorrhage and lacunar stroke, directly implicate the myeloperoxidase pathway in the pathogenesis of cerebral small vessel disease. Because genetic variants are not influenced by environmental exposures, these results provide new support for a causal rather than bystander role for myeloperoxidase in the progression of cerebrovascular disease. Furthermore, these results support a rationale for chronic inflammation as a potential modifiable stroke risk mechanism, and suggest that immune-targeted therapies could be useful for treatment and prevention of cerebrovascular disease

    Age of onset of cerebral venous thrombosis: the BEAST study

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    Background: Cerebral venous thrombosis (CVT) is an uncommon cause of stroke in young adults. We aimed to determine the impact of age, gender and risk factors (including sex-specific) on CVT onset. Methods: We used data from the BEAST (Biorepository to Establish the Aetiology of Sinovenous Thrombosis), a multicentre multinational prospective observational study on CVT. Composite factors analysis (CFA) was performed to determine the impact on the age of CVT onset in males and females. Results: A total of 1309 CVT patients (75.3% females) aged â©Ÿ18 years were recruited. The overall median (IQR-interquartile range) age for males and females was 46 (35–58) years and 37 (28–47) years (p < 0.001), respectively. However, the presence of antibiotic-requiring sepsis (p = 0.03, 95% CI 27–47 years) among males and gender-specific risk factors like pregnancy (p < 0.001, 95% CI 29–34 years), puerperium (p < 0.001, 95% CI 26–34 years) and oral contraceptive use (p < 0.001, 95% CI 33–36 years) were significantly associated with earlier onset of CVT among females. CFA demonstrated a significantly earlier onset of CVT in females, ~12 years younger, in those with multiple (â©Ÿ1) compared to ‘0’ risk factors (p < 0.001, 95% CI 32–35 years). Conclusions: Women suffer CVT 9 years earlier in comparison to men. Female patients with multiple (â©Ÿ1) risk factors suffer CVT ~12 years earlier compared to those with no identifiable risk factors

    Genome-Wide Association Study Identifies First Locus Associated with Susceptibility to Cerebral Venous Thrombosis

    No full text
    Objective: Cerebral venous thrombosis (CVT) is an uncommon form of stroke affecting mostly young individuals. Although genetic factors are thought to play a role in this cerebrovascular condition, its genetic etiology is not well understood. Methods: A genome-wide association study was performed to identify genetic variants influencing susceptibility to CVT. A 2-stage genome-wide study was undertaken in 882 Europeans diagnosed with CVT and 1,205 ethnicity-matched control subjects divided into discovery and independent replication datasets. Results: In the overall case–control cohort, we identified highly significant associations with 37 single nucleotide polymorphisms (SNPs) within the 9q34.2 region. The strongest association was with rs8176645 (combined p = 9.15 × 10 −24; odds ratio [OR] = 2.01, 95% confidence interval [CI] = 1.76–2.31). The discovery set findings were validated across an independent European cohort. Genetic risk score for this 9q34.2 region increases CVT risk by a pooled estimate OR = 2.65 (95% CI = 2.21–3.20, p = 2.00 × 10 −16). SNPs within this region were in strong linkage disequilibrium (LD) with coding regions of the ABO gene. The ABO blood group was determined using allele combination of SNPs rs8176746 and rs8176645. Blood groups A, B, or AB, were at 2.85 times (95% CI = 2.32–3.52, p = 2.00 × 10 −16) increased risk of CVT compared with individuals with blood group O. Interpretation: We present the first chromosomal region to robustly associate with a genetic susceptibility to CVT. This region more than doubles the likelihood of CVT, a risk greater than any previously identified thrombophilia genetic risk marker. That the identified variant is in strong LD with the coding region of the ABO gene with differences in blood group prevalence provides important new insights into the pathophysiology of CVT. ANN NEUROL 2021;90:777–788

    Genome-Wide Association Study Identifies First Locus Associated with Susceptibility to Cerebral Venous Thrombosis

    No full text
    Objective Cerebral venous thrombosis (CVT) is an uncommon form of stroke affecting mostly young individuals. Although genetic factors are thought to play a role in this cerebrovascular condition, its genetic etiology is not well understood. Methods A genome-wide association study was performed to identify genetic variants influencing susceptibility to CVT. A 2-stage genome-wide study was undertaken in 882 Europeans diagnosed with CVT and 1,205 ethnicity-matched control subjects divided into discovery and independent replication datasets. Results In the overall case-control cohort, we identified highly significant associations with 37 single nucleotide polymorphisms (SNPs) within the 9q34.2 region. The strongest association was with rs8176645 (combined p = 9.15 x 10(-24); odds ratio [OR] = 2.01, 95% confidence interval [CI] = 1.76-2.31). The discovery set findings were validated across an independent European cohort. Genetic risk score for this 9q34.2 region increases CVT risk by a pooled estimate OR = 2.65 (95% CI = 2.21-3.20, p = 2.00 x 10(-16)). SNPs within this region were in strong linkage disequilibrium (LD) with coding regions of the ABO gene. The ABO blood group was determined using allele combination of SNPs rs8176746 and rs8176645. Blood groups A, B, or AB, were at 2.85 times (95% CI = 2.32-3.52, p = 2.00 x 10(-16)) increased risk of CVT compared with individuals with blood group O. Interpretation We present the first chromosomal region to robustly associate with a genetic susceptibility to CVT. This region more than doubles the likelihood of CVT, a risk greater than any previously identified thrombophilia genetic risk marker. That the identified variant is in strong LD with the coding region of the ABO gene with differences in blood group prevalence provides important new insights into the pathophysiology of CVT. ANN NEUROL 202
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