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Paweł Górnaś Vitalijs Radenkovs Iveta Pugajeva Arianne Soliven Paul W. Needs Paul A. Kroon 《International Journal of Food Properties》2016,19(8):1757-1764
The profiles of tocopherol (T) and tocotrienol (T3) homologues in 37 samples of seven different types of bran (rye, wheat, oat, spelt, buckwheat, rice, and corn), available on the Polish market, were studied. Tocochromanols were identified and quantified by reverse phase-high-performance liquid chromatograph/fluorescence detector and reverse phase-ultra performance liquid chromatography-electrospray ionization/mass spectrometry. Only rice bran contained all eight tocochromanol types. Corn bran lacked β-T3; rye, wheat, oat, and spelt bran lacked γ-T3 and δ-T3; and buckwheat bran lacked β-T3, γ-T3, and δ-T3. In buckwheat and corn bran tocopherols predominated (98 and 78%, respectively); whereas rye, wheat, oat, spelt, and rice bran were rich in tocotrienols (78, 76, 66, 87, and 66%, respectively). The average total tocochromanol contents in the oat, corn, spelt, buckwheat, wheat, rye, and rice bran were 5.5, 16.2, 15.8, 14.7, 12.8, 10.7, and 9.1 mg/100 g of dry weight, respectively. Tocochromanol concentrations in samples of the same type bran from different sources varied considerably. Better labeling of bran products to reflect this variation would assist with control of vitamin E daily dietary requirements. 相似文献
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Estefanija Bogdanova Irina Rozentale Iveta Pugajeva Emeka E. Emecheta Vadims Bartkevics 《Food Additives and Contaminants: Part B: Surveillance Communications》2018,11(2):126-137
This work reports data on the occurrence of nine mycotoxins and two food processing contaminants – acrylamide and furan – in a total of 100 beers produced in Latvia. Mycotoxins were detected by high-performance liquid chromatography (HPLC) coupled with time-of-flight mass spectrometry, acrylamide by HPLC coupled with quadrupole-Orbitrap mass spectrometry, and furan by headspace gas chromatography-mass spectrometry. The most frequently occurring mycotoxins were HT-2 and deoxynivalenol (DON), which were detected in 52% and 51% of the analysed samples. The highest content was observed for DON, reaching the maximum of 248 µg kg?1. Furan was ubiquitous, and 74% of the samples contained acrylamide. In terms of the estimated exposure, the biggest potential risk was identified for HT-2 representing more than 11% of tolerable weekly intake. The margin of exposure approach indicated the exposure to furan through beer as significant, this parameter being close to the critical limit. 相似文献
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Solutions of numerically ill-posed least squares problems for A∈Rm×n by Tikhonov regularization are considered. For D∈Rp×n, the Tikhonov regularized least squares functional is given by where matrix W is a weighting matrix and is given. Given a priori estimates on the covariance structure of errors in the measurement data , the weighting matrix may be taken as which is the inverse covariance matrix of the mean 0 normally distributed measurement errors in . If in addition is an estimate of the mean value of , and σ is a suitable statistically-chosen value, J evaluated at its minimizer approximately follows a χ2 distribution with degrees of freedom. Using the generalized singular value decomposition of the matrix pair , σ can then be found such that the resulting J follows this χ2 distribution. But the use of an algorithm which explicitly relies on the direct solution of the problem obtained using the generalized singular value decomposition is not practical for large-scale problems. Instead an approach using the Golub-Kahan iterative bidiagonalization of the regularized problem is presented. The original algorithm is extended for cases in which is not available, but instead a set of measurement data provides an estimate of the mean value of . The sensitivity of the Newton algorithm to the number of steps used in the Golub-Kahan iterative bidiagonalization, and the relation between the size of the projected subproblem and σ are discussed. Experiments presented contrast the efficiency and robustness with other standard methods for finding the regularization parameter for a set of test problems and for the restoration of a relatively large real seismic signal. An application for image deblurring also validates the approach for large-scale problems. It is concluded that the presented approach is robust for both small and large-scale discretely ill-posed least squares problems. 相似文献
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Kasyanov VA Hodde J Hiles MC Eisenberg C Eisenberg L De Castro LE Ozolanta I Murovska M Draughn RA Prestwich GD Markwald RR Mironov V 《Journal of materials science. Materials in medicine》2009,20(1):329-337
Centrifugal casting allows rapid biofabrication of tubular tissue constructs by suspending living cells in an in situ cross-linkable hydrogel. We hypothesize that introduction of laser-machined micropores into a decellularized natural scaffold will facilitate cell seeding by centrifugal casting and increase hydrogel retention, without compromising the biomechanical properties of the scaffold. Micropores with diameters of 50, 100, and 200 mum were machined at different linear densities in decellularized small intestine submucosa (SIS) planar sheets and tubular SIS scaffolds using an argon laser. The ultimate stress and ultimate strain values for SIS sheets with laser-machined micropores with diameter 50 mum and distance between holes as low as 714 mum were not significantly different from unmachined control SIS specimens. Centrifugal casting of GFP-labeled cells suspended in an in situ cross-linkable hyaluronan-based hydrogel resulted in scaffold recellularization with a high density of viable cells inside the laser-machined micropores. Perfusion tests demonstrated the retention of the cells encapsulated within the HA hydrogel in the microholes. Thus, an SIS scaffold with appropriately sized microholes can be loaded with hydrogel encapsulated cells by centrifugal casting to give a mechanically robust construct that retains the cell-seeded hydrogel, permitting rapid biofabrication of tubular tissue construct in a "bioreactor-free" fashion. 相似文献
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In standard BP-networks, hidden neuron outputs are usually spread over the whole interval (0,1). In this paper, we propose an efficient framework to enforce a transparent internal knowledge representation in BP-networks during training. We want the formed internal representations to differ as much as possible for different outputs. At the same time, the hidden neuron outputs will be forced to group around three possible values, namely 1, 0 and 0.5. We will call such an internal representation unambiguous and condensed. The performance of BP-networks with enforced internal representations will be examined in a case study devoted to semantic image classification. 相似文献
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Soini HA Bruce KE Klouckova I Brereton RG Penn DJ Novotny MV 《Analytical chemistry》2006,78(20):7161-7168
This report describes a rolling stir bar sampling procedure for volatile organic compounds (VOCs) present on various biological surfaces. In combination with thermal desorption/gas chromatography/mass spectrometry, this analytical technique was initially tested for quantitative profiling of human skin VOCs. It is also applicable to additional hydrophobic surfaces such as agricultural products, plant materials, and bird feathers. Use of embedded internal standards provides highly reproducible and quantitative results for a wide variety of sampled trace components. The samples of collected human skin VOCs and standards were found stable under cool storage conditions for at least 14 days, making this approach suitable for field biological and agricultural studies. Additionally, this methodology appears to have potential for forensic and toxicological investigations, as suggested through the analyses of VOC profiles of the human thumb prints recovered from a nonbiological smooth surface. 相似文献
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Marie Stiborová Věra ?erná Michaela Moserová Iveta Mrízová Volker M. Arlt Eva Frei 《International journal of molecular sciences》2015,16(1):284-306
Ellipticine is a DNA-damaging agent acting as a prodrug whose pharmacological efficiencies and genotoxic side effects are dictated by activation with cytochrome P450 (CYP). Over the last decade we have gained extensive experience in using pure enzymes and various animal models that helped to identify CYPs metabolizing ellipticine. In this review we focus on comparison between the in vitro and in vivo studies and show a necessity of both approaches to obtain valid information on CYP enzymes contributing to ellipticine metabolism. Discrepancies were found between the CYP enzymes activating ellipticine to 13-hydroxy- and 12-hydroxyellipticine generating covalent DNA adducts and those detoxifying this drug to 9-hydroxy- and 7-hydroellipticine in vitro and in vivo. In vivo, formation of ellipticine-DNA adducts is dependent not only on expression levels of CYP3A, catalyzing ellipticine activation in vitro, but also on those of CYP1A that oxidize ellipticine in vitro mainly to the detoxification products. The finding showing that cytochrome b5 alters the ratio of ellipticine metabolites generated by CYP1A1/2 and 3A4 explained this paradox. Whereas the detoxification of ellipticine by CYP1A and 3A is either decreased or not changed by cytochrome b5, activation leading to ellipticine-DNA adducts increased considerably. We show that (I) the pharmacological effects of ellipticine mediated by covalent ellipticine-derived DNA adducts are dictated by expression levels of CYP1A, 3A and cytochrome b5, and its own potency to induce these enzymes in tumor tissues, (II) animal models, where levels of CYPs are either knocked out or induced are appropriate to identify CYPs metabolizing ellipticine in vivo, and (III) extrapolation from in vitro data to the situation in vivo is not always possible, confirming the need for these animal models. 相似文献
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Paweł Górnaś Iveta Pugajeva Dalija Segliņa 《European Food Research and Technology》2014,239(3):519-524
Tocochromanol composition was analysed in the seeds of nine various fruits: apple (Malus domestica Borkh.), red currant (Ribes rubrum L.), gooseberry (Ribes uva-crispa L.), grape (Vitis vinifera L.), pomegranate (Punica granatum L.), Japanese quince (Chaenomeles japonica (Thunb.) Lindl. ex Spach), sea buckthorn (Hippophae rhamnoides L.), watermelon (Citrullus lanatus (Thunb.) Matsum. & Nakai) and canary melon (Cucumis melo L.), recovered from by-products of fruit industry. The concentration range of subsequent tocopherols (Ts) and tocotrienols (T3s) was as follows: 1.29–29.30, 0.00–11.68, 0.42–95.11, 0.00–7.66, 0.03–5.03, 0.00–0.18 and 0.00–6.68 mg/100 g of seed dry weight for α-T, β-T, γ-T, δ-T, α-T3, β-T3 and γ-T3, respectively. The δ-T3 was not detected in any of the tested seeds. All tocochromanols were successfully separated by rapid RP-HPLC/FLD method and confirmed by the RP-UPLC-ESI/MS3 technique. 相似文献
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