342 research outputs found

    Effect of metabolic and antioxidant supplementation on sperm parameters in oligo-astheno-teratozoospermia, with and without varicocele: a double-blind placebo-controlled study

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    Since sperm require high energy levels to perform their specialised function, it is vital that essential nutrients are available for spermatozoa when they develop, capacitate and acquire motility. However, they are vulnerable to a lack of energy and excess amounts of reactive oxygen species, which can impair sperm function, lead to immotility, acrosomal reaction impairment, DNA fragmentation and cell death. This monocentric, randomised, double-blind, placebo-controlled trial investigated the effect of 6 months of supplementation with l-carnitine, acetyl-l-carnitine and other micronutrients on sperm quality in 104 subjects with oligo- and/or astheno- and/or teratozoospermia with or without varicocele. In 94 patients who completed the study, sperm concentration was significantly increased in supplemented patients compared to the placebo (p =.0186). Total sperm count also increased significantly (p =.0117) in the supplemented group as compared to the placebo group. Both, progressive and total motility were higher in supplemented patients (p =.0088 and p =.0120, respectively). Although pregnancy rate was not an endpoint of the study, of the 12 pregnancies that occurred during the follow-up, 10 were reported in the supplementation group. In general, all these changes were more evident in varicocele patients. In conclusion, supplementation with metabolic and antioxidant compounds could be efficacious when included in strategies to improve fertility

    Comparative Assessment of the Fracture Behaviour of API‐5L X65 and Micro‐alloyed Steels in E80 Simulated Fuel Ethanol Environment

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    Monotonic J‐integral tests were carried out on API‐5L X65 steel and micro‐alloyed steel (MAS) in E80 simulated fuel grade ethanol (SFGE) environment using three‐point bend specimens. A ramp rate of 10-04 mm/s was used for loading in each sequence so as to enhance stress corrosion cracking (SCC) influence if any. The influence of the SFGE environment on tearing resistance and fracture toughness of the steels was studied. Both steels exhibited decrease in fracture toughness in E80 in relation to air. The decrease in fracture toughness may be due to anodic dissolution at the crack tip. Ductile tearing resistance of the steels increased in E80 due to decline in toughness property. In comparison with X65 steel, MAS showed better fracture properties

    Surface and thermomechanical characterization of polyurethane networks based on poly(dimethylsiloxane) and hyperbranched polyester

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    Two series of polyurethane (PU) networks based on Boltorn® hyperbranched polyester (HBP) and hydroxyethoxy propyl terminated poly(dimethylsiloxane) (EO-PDMS) or hydroxy propyl terminated poly(dimethylsiloxane) (HPPDMS), were synthesized. The effect of the type of soft PDMS segment on the properties of PUs was investigated by Fourier transform infrared spectroscopy (FTIR), contact angle measurements, surface free energy determination, X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), atomic force microscopy (AFM), dynamic mechanical thermal analysis (DMTA) and differential scanning calorimetry (DSC). The surface characterization of PUs showed existence of slightly amphiphilic character and it revealed that PUs based on HP-PDMS have lower surface free energy, more hydrophobic surface and better waterproof performances than PUs based on EO-PDMS. PUs based on HPPDMS had higher crosslinking density than PUs based on EO-PDMS. DSC and DMTA results revealed that these newlysynthesized PUs exhibit the glass transition temperatures of the soft and hard segments. DMTA, SEM and AFM results confirmed existence of microphase separated morphology. The results obtained in this work indicate that PU networks based on HBP and PDMS have improved surface and thermomechanical properties

    Polyphenol Content and Antioxidant Activity of Sour Cherries From Serbia

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    The aim of this study was to evaluate the content of phenolics: the total phenols (TP), flavonoids (TF), anthocyanins (TA), as well as the total antioxidant\ud capacity (TAC) in three sour cherry cultivars (Prunus cerasus L.) introduced to the southeast Serbia climate conditions. Among the investigated sour cherries,\ud „Oblačinska“ cultivar contained the highest amounts of all groups of phenolics, followed by „Cigančica“ > „Marela“. A significant difference were observed in the phenolic content among different cultivars and growing seasons (p  0.05), and the phenolic compounds were significantly higher in the growing season 2009. The examined cultivars possess a high antioxidant capacity, and all phenolics of highy correlation with TAC. The following compounds were identified and quantified using HPLC-DAD: 4 anthocyanins, the most abundant of which was cyanidin-3-glucoside in “Marela” and “Oblačinska”, and cyanidin-3-glucosylrutinoside in „Cigančica“, and 4 hydroxycinnamic acids, the most abundant of which was neochlorogenic acid in all sour cherry cultivars. The growing and ripening process on the tree of sour cherry cv. „Oblačinska“ was evaluated also. The results showed significant increases in total phenols during the ripening, the total anthocyanins and total antioxidant capacity and 4 quantified anthocyanins, however the neochlorogenic acid decreased during the ripening. The study indicated that the growing and climate conditions in southeast Serbia are convenient for introducing sour cherry cultivars.\u

    Sage Extracts as Inhibitors of Steel Corrosion in 4% HCl

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    In this paper the research of corrosion protection of steel by processing corrosion environment using various concentrations of sage extracts (Salvia officinalis) (0.5 g/dm(3), 1 g/dm(3) and 1.5 g/dm(3)) in a 4% solution of HCl was carried out. Measurements were performed using gravimetric and electrochemical methods (Tafel extrapolation method and electrochemical impedance spectroscopy). The results have showed that sage is recommendable as a possible inhibitor in 4% solutions of HCl. The research also confirms that electrochemical impedance spectroscopy is a reliable method to use for rapid corrosion tests, since the results confirm the gravimetric measurements of corrosion indicators. Determination of corrosion rate and the degree of protection using Tafel diagrams calculated on the basis of corrosion current did not give reliable results. The results show that sage may be used as a "green inhibitor" for protection of steel in a shorter period of time. The degree of protection ranges up to 64.5% for steel 2; however, since sage is environmentally friendly, it is a suitable corrosion inhibitor for shorter periods of time

    A pseudopotential study of electron-hole excitations in colloidal, free-standing InAs quantum dots

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    Excitonic spectra are calculated for free-standing, surface passivated InAs quantum dots using atomic pseudopotentials for the single-particle states and screened Coulomb interactions for the two-body terms. We present an analysis of the single particle states involved in each excitation in terms of their angular momenta and Bloch-wave parentage. We find that (i) in agreement with other pseudopotential studies of CdSe and InP quantum dots, but in contrast to k.p calculations, dot states wavefunction exhibit strong odd-even angular momentum envelope function mixing (e.g. ss with pp) and large valence-conduction coupling. (ii) While the pseudopotential approach produced very good agreement with experiment for free-standing, colloidal CdSe and InP dots, and for self-assembled (GaAs-embedded) InAs dots, here the predicted spectrum does {\em not} agree well with the measured (ensemble average over dot sizes) spectra. (1) Our calculated excitonic gap is larger than the PL measure one, and (2) while the spacing between the lowest excitons is reproduced, the spacings between higher excitons is not fit well. Discrepancy (1) could result from surface states emission. As for (2), agreement is improved when account is taken of the finite size distribution in the experimental data. (iii) We find that the single particle gap scales as R1.01R^{-1.01} (not R2R^{-2}), that the screened (unscreened) electron-hole Coulomb interaction scales as R1.79R^{-1.79} (R0.7R^{-0.7}), and that the eccitonic gap sclaes as R0.9R^{-0.9}. These scaling laws are different from those expected from simple models.Comment: 12 postscript figure

    Effect of metabolic and antioxidant supplementation on sperm parameters in oligo-astheno-teratozoospermia, with and without varicocele: a double-blind placebo-controlled study

    Get PDF
    Since sperm require high energy levels to perform their specialised function, it is vital that essential nutrients are available for spermatozoa when they develop, capacitate and acquire motility. However, they are vulnerable to a lack of energy and excess amounts of reactive oxygen species, which can impair sperm function, lead to immotility, acrosomal reaction impairment, DNA fragmentation and cell death. This monocentric, randomised, double-blind, placebo-controlled trial investigated the effect of 6 months of supplementation with l-carnitine, acetyl-l- carnitine and other micronutrients on sperm quality in 104 subjects with oligo-and/ or astheno-and/ or teratozoospermia with or without varicocele. In 94 patients who completed the study, sperm concentration was significantly increased in supplemented patients compared to the placebo (p = .0186). Total sperm count also increased significantly (p = .0117) in the supplemented group as compared to the placebo group. Both, progressive and total motility were higher in supplemented patients (p = .0088 and p = .0120, respectively). Although pregnancy rate was not an endpoint of the study, of the 12 pregnancies that occurred during the follow-up, 10 were reported in the supplementation group. In general, all these changes were more evident in varicocele patients. In conclusion, supplementation with metabolic and antioxidant compounds could be efficacious when included in strategies to improve fertility

    An accurate description of quantum size effects in InP nanocrystallites over a wide range of sizes

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    We obtain an effective parametrization of the bulk electronic structure of InP within the Tight Binding scheme. Using these parameters, we calculate the electronic structure of InP clusters with the size ranging upto 7.5 nm. The calculated variations in the electronic structure as a function of the cluster size is found to be in excellent agreement with experimental results over the entire range of sizes, establishing the effectiveness and transferability of the obtained parameter strengths.Comment: 9 pages, 3 figures, pdf file available at http://sscu.iisc.ernet.in/~sampan/publications.htm

    A multiplexed immunoassay system based upon reciprocating centrifugal microfluidics

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    A novel, centrifugal disk-based micro-total analysis system (mu TAS) for low cost and high throughput semi-automated immunoassay processing was developed. A key innovation in the disposable immunoassay disk design is in a fluidic structure that enables very efficient micro-mixing based on a reciprocating mechanism in which centrifugal acceleration acting upon a liquid element first generates and stores pneumatic energy that is then released by a reduction of the centrifugal acceleration, resulting in a reversal of direction of flow of the liquid. Through an alternating sequence of high and low centrifugal acceleration, the system reciprocates the flow of liquid within the disk to maximize incubation/hybridization efficiency between antibodies and antigen macromolecules during the incubation/hybridization stage of the assay. The described reciprocating mechanism results in a reduction in processing time and reagent consumption by one order of magnitude.open121

    Sage Extracts as Inhibitors of Steel Corrosion in 4% HCl

    Get PDF
    In this paper the research of corrosion protection of steel by processing corrosion environment using various concentrations of sage extracts (Salvia officinalis) (0.5 g/dm(3), 1 g/dm(3) and 1.5 g/dm(3)) in a 4% solution of HCl was carried out. Measurements were performed using gravimetric and electrochemical methods (Tafel extrapolation method and electrochemical impedance spectroscopy). The results have showed that sage is recommendable as a possible inhibitor in 4% solutions of HCl. The research also confirms that electrochemical impedance spectroscopy is a reliable method to use for rapid corrosion tests, since the results confirm the gravimetric measurements of corrosion indicators. Determination of corrosion rate and the degree of protection using Tafel diagrams calculated on the basis of corrosion current did not give reliable results. The results show that sage may be used as a "green inhibitor" for protection of steel in a shorter period of time. The degree of protection ranges up to 64.5% for steel 2; however, since sage is environmentally friendly, it is a suitable corrosion inhibitor for shorter periods of time
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