90 research outputs found

    Tuning SERS Signal via Substrate Structuring: Valves of Different Diatom Species with Ultrathin Gold Coating

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    The discovered light modulation capabilities of diatom silicious valves make them an excellent toolkit for photonic devices and applications. In this work, a reproducible surface-enhanced Raman scattering (SERS) enhancement was achieved with hybrid substrates employing diatom silica valves coated with an ultrathin uniform gold film. Three structurally different hybrid substrates, based on the valves of three dissimilar diatom species, have been compared to elucidate the structural contribution to SERS enhancement. The comparative analysis of obtained results showed that substrates containing cylindrical Aulacoseira sp. valves achieved the highest enhancement, up to 14-fold. Numerical analysis based on the frequency domain finite element method was carried out to supplement the experimental results. Our results demonstrate that diatom valves of different shapes can enhance the SERS signal, offering a toolbox for SERS-based sensors, where the magnitude of the enhancement depends on valve geometry and ultrastructure

    Numerical analysis of the light modulation by the frustule of Gomphonema parvulum : the role of integrated optical components

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    Siliceous diatom frustules present a huge variety of shapes and nanometric pore patterns. A better understanding of the light modulation by these frustules is required to determine whether or not they might have photobiological roles besides their possible utilization as building blocks in photonic applications. In this study, we propose a novel approach for analyzing the near-field light modulation by small pennate diatom frustules, utilizing the frustule of Gomphonema parvulum as a model. Numerical analysis was carried out for the wave propagation across selected 2D cross-sections in a statistically representative 3D model for the valve based on the finite element frequency domain method. The influences of light wavelength (vacuum wavelengths from 300 to 800 nm) and refractive index changes, as well as structural parameters, on the light modulation were investigated and compared to theoretical predictions when possible. The results showed complex interference patterns resulting from the overlay of different optical phenomena, which can be explained by the presence of a few integrated optical components in the valve. Moreover, studies on the complete frustule in an aqueous medium allow the discussion of its possible photobiological relevance. Furthermore, our results may enable the simple screening of unstudied pennate frustules for photonic applications

    Primary study of the non-marine epilithic diatom communities of Malta and Gozo

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    Non-marine epilithic diatom communities of two major Maltese islands, Malta & Gozo, were investigated for the first time. Fourty four samples were collected from eleven stations, which represented different springs and spring-fed streams distributed over the two islands. Extraction of diatoms and preparation of clean slides for microscipic investigation was carried out. A total number of 51 taxa belonging to 23 genera were identified. The most represented genera were Nitzschia, Amphora, Surirella, Luticola & Navicula. The most represented species were Gomphonema parvulum, Hanztschia amphysioxy, Nitzschia palea & Amphora ovalis. Most of the identified taxa show moderate to strong association with pollution, and show potential as indicators for forensic science and environmental assessment.peer-reviewe

    Crocin mitigates carbon tetrachloride-induced liver toxicity in rats

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    AbstractObjectivesCarbon tetrachloride (CCl4) is one of the most dangerous hepatotoxic environmental pollutants thus this study aimed at investigating the potential preventive effect and mechanism of crocin against CCl4-induced hepatotoxicity.MethodsForty Male rats were allocated for two weeks treatment with; corn oil, CCl4 in corn oil, crocin (100mg/kg), or crocin plus CCl4. At time of euthanasia liver was removed, weighted and processed for histopathological evaluation and estimation of liver contents of active caspase3, lipid peroxidation (MDA) and reduced glutathione (GSH). We also evaluated antioxidant enzymes activities [superoxide dismutase (SOD), glutathione peroxidase (GSH-Px) and catalase (CAT)], phase I metabolizing enzyme [cytochrome P450 sub family 2E1 (CYP2E1)] an Phase II metabolizing enzyme, [glutathione-S-transferase (GST)] in liver tissue. Blood samples were used for evaluation of liver function tests and inflammatory cytokines [interleukin 6 (IL-6) and tumor necrosis factor alpha (TNF-α)].ResultsCCl4 induced significant (p < 0.001), increase in: relative liver weight to body weight, liver MDA content, liver active caspase-3 and plasma levels of IL-6 and TNF-α. In addition, CCl4 disturbed liver histology, liver metabolizing enzymes (CYP2E1 and GST), and liver function tests (aspartate aminotransferase, alanine aminotransferase, total bilirubin and alkaline phosphatase). CCl4 induced significant decrease in activities of SOD, CAT, GSH-Px and GSH content. Administration of crocin with CCl4 mitigated all CCl4-disturbed parameters and preserved liver histology close to normal.ConclusionCrocin ameliorated CCl4-induced liver injury via inhibition of inflammatory cytokines, caspase3 and oxidative stress along with modulation of liver metabolizing enzymes favoring elimination of CCl4 toxic metabolite

    Five-year study assessing the clinical utility of anti-Müllerian hormone measurements in reproductive-age women with cancer

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    An important discussion point before chemotherapy is ovarian toxicity, a side-effect that profoundly affects young women with cancer. Their quality of life after successful treatment, including the ability to conceive, is a major concern. We asked whether serum anti-Müllerian hormone (AMH) measurements before chemotherapy for two most common malignancies are predictive of long-term changes in ovarian reserve? A prospective cohort study measured serum AMH in 66 young women with lymphoma and breast cancer, before and at 1 year and 5 years after chemotherapy, compared with 124 healthy volunteers of the same age range (18-43 years). Contemporaneously, patients reported their menses and live births during 5-year follow-up. After adjustment for age, serum AMH was 1.4 times higher (95% CI 1.1 to 1.9; P < 0.02) in healthy volunteers than in cancer patients before chemotherapy. A strong correlation was observed between baseline and 5-year AMH in the breast cancer group (P < 0.001, regression coefficient = 0.58, 95% CI 0.29 to 0.89). No significant association was found between presence of menses at 5 years and serum AMH at baseline (likelihood ratio test from logistics regression analysis). Reproductive-age women with malignancy have lower serum AMH than healthy controls even before starting chemotherapy. Pre-chemotherapy AMH was significantly associated with long-term ovarian function in women with breast cancer. At key time points, AMH measurements could be used as a reproductive health advisory tool for young women with cancer. Our results highlight the unsuitability of return of menstruation as a clinical indicator of ovarian reserve after chemotherapy. [Abstract copyright: Crown Copyright © 2019. Published by Elsevier Ltd. All rights reserved.

    Levothyroxine in Women with Thyroid Peroxidase Antibodies before Conception

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    BackgroundThyroid peroxidase antibodies are associated with an increased risk of miscarriage and preterm birth, even when thyroid function is normal. Small trials indicate that the use of levothyroxine could reduce the incidence of such adverse outcomes.MethodsWe conducted a double-blind, placebo-controlled trial to investigate whether levothyroxine treatment would increase live-birth rates among euthyroid women who had thyroid peroxidase antibodies and a history of miscarriage or infertility. A total of 19,585 women from 49 hospitals in the United Kingdom underwent testing for thyroid peroxidase antibodies and thyroid function. We randomly assigned 952 women to receive either 50 μg once daily of levothyroxine (476 women) or placebo (476 women) before conception through the end of pregnancy. The primary outcome was live birth after at least 34 weeks of gestation.ResultsThe follow-up rate for the primary outcome was 98.7% (940 of 952 women). A total of 266 of 470 women in the levothyroxine group (56.6%) and 274 of 470 women in the placebo group (58.3%) became pregnant. The live-birth rate was 37.4% (176 of 470 women) in the levothyroxine group and 37.9% (178 of 470 women) in the placebo group (relative risk, 0.97; 95% confidence interval [CI], 0.83 to 1.14, P=0.74; absolute difference, −0.4 percentage points; 95% CI, −6.6 to 5.8). There were no significant between-group differences in other pregnancy outcomes, including pregnancy loss or preterm birth, or in neonatal outcomes. Serious adverse events occurred in 5.9% of women in the levothyroxine group and 3.8% in the placebo group (P=0.14).ConclusionsThe use of levothyroxine in euthyroid women with thyroid peroxidase antibodies did not result in a higher rate of live births than placebo. (Funded by the United Kingdom National Institute for Health Research; TABLET Current Controlled Trials number, ISRCTN15948785.

    Live birth rates and perinatal outcomes when all embryos are frozen compared with conventional fresh and frozen embryo transfer: a cohort study of 337,148 in vitro fertilisation cycles

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    BACKGROUND: It is not known whether segmentation of an in vitro fertilisation (IVF) cycle, with freezing of all embryos prior to transfer, increases the chance of a live birth after all embryos are transferred. METHODS: In a prospective study of UK Human Fertilisation and Embryology Authority data, we investigated the impact of segmentation, compared with initial fresh embryo followed by frozen embryo transfers, on live birth rate and perinatal outcomes. We used generalised linear models to assess the effect of segmentation in the whole cohort, with additional analyses within women who had experienced both segmentation and non-segmentation. We compared rates of live birth, low birthweight (LB
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