250 research outputs found

    New Method for the Development of Plasmonic Metal-Semiconductor Interface Layer: Polymer Composites with Reduced Energy Band Gap

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    Silver nanoparticles within a host polymer of chitosan were synthesized by using in situ method. Ultraviolet-visible spectroscopy was then carried out for the prepared chitosan : silver triflate (CS : AgTf) samples, showing a surface plasmonic resonance (SPR) peak at 420 nm. To prepare polymer composites with reduced energy band gap, different amounts of alumina nanoparticles were incorporated into the CS : AgTf solution. In the present work, the results showed that the reduced silver nanoparticles and their adsorption on wide band gap alumina (Al2O3) particles are an excellent approach for the preparation of polymer composites with small optical band gaps. The optical dielectric loss parameter has been used to determine the band gap experimentally. The physics behind the optical dielectric loss were interpreted from the viewpoint of quantum mechanics. From the quantum-mechanics viewpoint, optical dielectric loss was also found to be a complex equation and required lengthy numerical computation. From the TEM investigation, the adsorption of silver nanoparticles on alumina has been observed. The optical micrograph images showed white spots (silver specks) with different sizes on the surface of the films. The second semicircle in impedance Cole-Cole plots was found and attributed to the silver particles

    Sex differences in cardiovascular morbidity associated with familial hypercholesterolaemia: A retrospective cohort study of the UK Simon Broome register linked to national hospital records

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    Background and aims: The UK Simon Broome (SB) familial hypercholesterolaemia (FH) register previously reported 3-fold higher standardised mortality ratio for cardiovascular disease (CVD) in women compared to men from 2009 to 2015. Here we examined sex differences in CVD morbidity in FH by national linkage of the SB register with Hospital Episode Statistics (HES). Methods: Of 3553 FH individuals in the SB register (aged 20–79 years at registration), 2988 (52.5% women) had linked HES records. Standardised Morbidity Ratios (SMbR) compared to an age and sex-matched UK general practice population were calculated [95% confidence intervals] for first CVD hospitalisation in HES (a composite of coronary heart disease (CHD), myocardial infarction (MI), stable or unstable angina, stroke, TIA, peripheral vascular disease (PVD), heart failure, coronary revascularisation interventions). Results: At registration, men had significantly (p < 0.001) higher prevalence of previous CHD (24.8% vs 17.6%), previous MI (13.2% vs 6.3%), and were commenced on lipid-lowering treatment at a younger age than women (37.5 years vs 42.3 years). The SMbR for composite CVD was 6.83 (6.33–7.37) in men and 7.55 (6.99–8.15) in women. In individuals aged 30–50 years, SMbR in women was 50% higher than in men (15.04 [12.98–17.42] vs 10.03 [9.01–11.17]). In individuals >50 years, SMbR was 33% higher in women than men (6.11 [5.57–6.70] vs 4.59 [4.08–5.15]). Conclusions: Excess CVD morbidity due to FH remains markedly elevated in women at all ages, but especially those aged 30–50 years. This highlights the need for earlier diagnosis and optimisation of lipid-lowering risk factor management for all FH patients, with particular attention to young women with FH

    Investigation of organic matter and biomarkers from Diepkloof Rock Shelter, South Africa: Insights into Middle Stone Age site usage and palaeoclimate

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    The file associated with this record is under embargo until 36 months after publication, in accordance with the publisher's self-archiving policy. The full text may be available through the publisher links provided above.Diepkloof Rock Shelter (DRS) represents a site of major interest for reconstructing early human behaviours during the Middle Stone Age (MSA). Rock shelters such as DRS also potentially preserve information concerning the environmental context for such behaviours. In this respect the organic matter composition of rock shelter sediments has rarely been investigated in detail, particularly at the molecular level. Here, we used pyrolysis-gas chromatography/mass spectrometry (py-GC/MS) to systematically assess the organic matter composition of bulk sediments within the MSA and Later Stone Age (LSA) sequence at DRS. From this we sought to gain insights into site usage, taphonomy and burning practices. Additionally, we analysed the chain length distribution of leaf-wax n-alkanes as well as their hydrogen and carbon isotopic compositions (δDwax and δ13Cwax) to investigate their potential as hydroclimate and vegetation indicators. This constitutes the first leaf-wax isotopic data in a terrestrial context of this antiquity in South Africa. Py-GC/MS shows a dichotomy between stratigraphic units (SUs) of high organic matter content, producing a range of pyrolysis products, including homologous series of long chain n-alkene/n-alkane doublets and alkyl-nitriles, and SUs of low organic matter content, dominated by aromatic, heterocyclic N and polycyclic aromatic hydrocarbon (PAH) pyrolysis products; typical molecular burning products. Several SUs of the Intermediate Howiesons Poort interval exhibit the latter composition, consistent with micromorphological evidence. δ13Cwax remains stable throughout the MSA, but leaf-wax n-alkane chain length and δDwax increase during the Late Howiesons Poort interval. Comparison with such patterns in modern plants in the region suggests this represents a shift towards the input of more arid-adapted vegetation into the shelter, driven either by aridification at the site locale or a change in selection practices. Our results suggest that these techniques have further potential in southern Africa and globally at sites where organic matter preservation is high.Peer-reviewedPost-prin

    Coronary heart disease mortality in treated familial hypercholesterolaemia: Update of the UK Simon Broome FH register

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    BACKGROUND AND AIMS: Patients with familial hypercholesterolaemia (FH) have an elevated risk of coronary heart disease (CHD). Here we compare changes in CHD mortality in patients with heterozygous (FH) pre 1992, before lipid-lowering therapy with statins was used routinely, and in the periods 1992–2008 and 2008–2016. METHODS: 1903 Definite (DFH) and 1650 Possible (PFH) patients (51% women) aged 20–79 years, recruited from 21 lipid clinics in the United Kingdom and followed prospectively between 1980 and 2016 for 67,060 person-years. The CHD standardised mortality ratio (SMR) compared to the population in England and Wales was calculated (with 95% Confidence intervals). RESULTS: There were 585 deaths, including 252 from CHD. Overall, the observed 2.4-fold excess coronary mortality for treated DFH post-1991 was significantly higher than the 1.78 excess for PFH (35% 95% CI 3%–76%). In patients with DFH and established coronary disease, there was a significant excess coronary mortality in all time periods, but in men it was reduced from a 4.83-fold excess (2.32–8.89) pre-1992 to 4.66 (3.46–6.14) in 1992–2008 and 2.51 (1.01–5.17) post-2008, while in women the corresponding values were 7.23 (2.65–15.73), 4.42 (2.70–6.82) and 6.34 (2.06–14.81). Primary prevention in men with DFH resulted in a progressive reduction in coronary mortality over the three time-periods, with no excess mortality evident post-2008 (0.89 (0.29–2.08)), although in women the excess persisted (post-2008 3.65 (1.75–6.72)). CONCLUSIONS: The results confirm the benefit of statin treatment in reducing CHD mortality, but suggest that FH patients with pre-existing CHD and women with FH may not be treated adequately

    Hypercholesterolaemia - practical information for non-specialists

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    Hypercholesterolaemia is amongst the most common conditions encountered in the medical profession. It remains one of the key modifiable cardiovascular risk factors and there have been recent advances in the risk stratification methods and treatment options available. In this review, we provide a background into hypercholesterolaemia for non-specialists and consider the merits of the different risk assessment tools available. We also provide detailed considerations as to: i) when to start treatment, ii) what targets to aim for and iii) the role of low density lipoprotein cholesterol

    Coronary heart disease mortality in severe vs. non-severe familial hypercholesterolaemia in the Simon Broome Register

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    Background and aims: The International Atherosclerosis Society (IAS) has proposed that patients with “severe” FH (SFH) would warrant early and more aggressive cholesterol-lowering treatment such as with PCSK9 inhibitors. SFH is diagnosed if LDL-cholesterol (LDLC) > 10 mmol/L, or LDLC > 8.0 mmol/L plus one high-risk feature, or LDLC > 5 mmol/L plus two high-risk features. Here we compare CHD mortality in SFH and non-SFH (NSFH) patients in the UK prospective Simon Broome Register since 1991, when statin use became routine. Methods: 2929 definite or possible PFH patients (51% women) aged 20–79 years were recruited from 21 UK lipid clinics and followed prospectively between 1992 and 2016. The excess CHD standardised mortality ratio (SMR) compared to the England and Wales population was calculated (with 95% confidence intervals). Results: 1982 (67.7%) patients met the SFH definition. Compared to the non-SFH, significantly (p < 0.001) more SFH patients had diagnosed CHD at baseline (24.6% vs. 17.5%), were current smokers (21.9% vs 10.2%) and had a BMI > 30 kg/m2 (14.9% vs. 7.8%). The SMR for CHD mortality was significantly (p = 0.007) higher for SFH (220 (184–261) (34,134 person years, 129 deaths observed, vs. 59 expected) compared to NSFH of 144 (98–203) (15,432 person years, 32 observed vs. 22 expected). After adjustment for traditional risk factors, the Hazard Ratio for CHD mortality in SFH vs. NSFH was 1.22 (0.80–1.87) p = 0.36, indicating that the excess risk was largely accounted for by these factors. Conclusions: CHD mortality remains elevated in treated FH, especially for SFH, emphasising the importance of optimal lipid-lowering and management of other risk factors

    Characterisation of patients with familial chylomicronaemia syndrome (FCS) and multifactorial chylomicronaemia syndrome (MCS): establishment of an FCS clinical diagnostic score

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    Data presented in this article are supplementary material to our article entitled "Identification and diagnosis of patients with familial chylomicronaemia syndrome (FCS): expert panel recom mendations and proposal of an "FCS Score" (Moulin et al., 2018, in press). The data describe the genotypes of patients with familial chylomicronaemia syndrome (FCS) and multifactorial chylomicro naemia syndrome (MCS), from the validation and replication cohorts
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