The natural mummy of prince Cangrande, Lord of Verona, Italy (1291–1329 AD) was studied. Two samples were taken: rib bone and muscle. These samples were cleaved with trypsin and analysed by liquid chromatographic methods coupled to mass spectrometry (Q-TOF, ion-trap). Special attention was devoted to nonenzymatic protein modification––the deamidation of asparagine and glutamine. A huge amount of collagen was determined in the tissues of the mummy (covering over 80 % of the sequence)––collagen type I was identified in the rib bone and collagen types I and III in the muscle. A high overall percentage of asparaginyl and glutaminyl residues were deamidated (up to 92 %). In agreement with the literature we can suppose that the deamidation of really old samples (at least 100-years-old) is mainly dependent on the burial conditions and/or thermal age and cannot serve as a precise “molecular clock”.
Resveratrol (RSV) (3,4′,5 trihydroxystilbene) is a natural non-flavonoid polyphenol widely present in the Mediterranean diet. In particular, RSV is found in grapes, peanuts, berries, and red wine. Many beneficial effects of this molecule on human health have been reported. In fact, it improves some clinical aspects of various diseases, such as obesity, tumors, hypertension, Alzheimer’s disease, stroke, cardiovascular diseases, and diabetes mellitus. However, little is known about the relationship between this compound and male fertility and the few available results are often controversial. Therefore, this review evaluated the effects of RSV on human male fertility and the mechanisms through which this polyphenol could act on human spermatozoa. 相似文献
Freestanding natural polymeric films with homogeneous dispersion of gold nanoparticles (Au NPs) are obtained via in situ reduction of gold(III) chloride trihydrate by sodium alginate (SA) biopolymer matrix, during water evaporation without the use of additional reducing agents. The size and size distribution of the prepared Au NPs can be tuned by changing the concentration of the precursor and/or the procedure of the films’ preparation. The nanocomposite films after preparation are stable in ambient conditions and can be used without the need of further processing, or can be redissolved in water. In the case of water dissolution, the aqueous solutions are irradiated with UV laser pulses turning the previously formed Au NPs into smaller ones with narrow size distributions through photofragmentation. This technique is proposed as a green way of synthesizing Au NPs of tunable size in aqueous solution of alginate, or incorporated in alginate freestanding polymeric films, that due to their biocompatibility can be used as passive labels or active sensors in biomedical applications. 相似文献
In the present work the concrete affected by alkali–silica reaction (ASR) is represented as a two-phase material made of a solid skeleton and a wet expanding gel, which exerts a pressure capable of severely damaging the concrete surrounding the reactive sites. Both the effects of temperature and humidity conditions on the kinetic of the chemical reaction and on the final value of the consequent expansion are included in the proposed model. The mechanical degradation induced by the ASR is described by a phenomenological isotropic damage model. The constitutive model, implemented in a finite element code, is used for the analyses of structures made of reactive concrete in the presence of temperature and moisture gradients. Firstly the temperature and humidity fields are obtained through uncoupled heat and moisture transport analyses and then the chemo-mechanical analysis is performed starting from the values of temperature and humidity preliminary calculated. 相似文献
A method to evaluate molecular weight distribution (MWD) from dynamic moduli is presented here. It relies on the least-square
fitting of the dynamic data to a model whose parameters depend on the MWD. In particular, the analytical solution for the relaxation modulus previously obtained from the double reptation model, with the Tuminello step relaxation function
and the Generalized Exponential Function (GEX) describing the MWD (Nobile and Cocchini 2000), has been used. A Finite Element
Approximation (FEA) has been applied to calculate dynamic moduli from the relaxation modulus as a function of MWD. The sensitiveness
of the GEX-double reptation dynamic moduli on the model parameters has also been investigated and the results show that large
changes of the Mw/Mn ratio weakly affect the dynamic moduli, while small changes of the Mz/Mw ratio significantly deform the dynamic moduli curves. The use of rheological data to obtain MWD, by the model used in this
paper, will, therefore, be able to give rather well defined Mz/Mw ratios, while more uncertainty will be presented in the Mw/Mn results. The so-called GEX-rheological model for the dynamic moduli was applied to fit the experimental data of different
polymers in order to obtain the best-fit parameters of the MWD of these polymers, without the need for the inversion of the double reptation integral equation. The stability of the results has been confirmed through the evaluation of the
90% confidence intervals for the first molecular weight averages. Finally, concerning the Mw and Mz values, the predictions obtained from the dynamic moduli measurements differ by less than 10% from those obtained from GPC
measurements while, as expected, more uncertainty is present in the Mn predictions.
Received: 6 February 2000 Accepted: 22 August 2000 相似文献