The addition of antimicrobial preservatives to pharmaceutical and cosmetic products is necessary to prevent microbial growth. However, the use of preservatives can also produce other undesirable effects. For several years, researchers have been investigating the use of alternative methods in safety assessment of cosmetic ingredients and formulations by means of variety methods. The aim of this study was to evaluate the erythrocyte toxicities of two commercial preservatives: imidazolidinyl urea and diazolidinyl urea. Relatively few studies about the cytotoxicity of these preservative are available. The determination of their cytotoxicity is an essential step to warrant their safe use. Erythrocyte toxicities were evaluated by assessment of the amount of hemoglobin released by red blood cells after their lysis. In this study, both imidazolidinyl urea and diazolidinyl urea showed cytotoxic activity against red blood cells. The imidazolidinyl urea induce a small release of hemoglobin after 120 min of incubation. But, the diazolidinyl urea induce a massive release of hemoglobin from the imidazolidinyl urea (a rate of 83% at concentrations of 6.25 mg/mL and 12.5 mg/mL). 相似文献
Constant neutral loss (CNL) and precursor ion (PI) scan have been widely used for the in vitro screening of glutathione conjugates derived from reactive metabolites, but these two methods are only applicable to triple quadrupole or hybrid triple quadrupole mass spectrometers. Additionally, the success of CNL and PI scanning largely depends on structure and CID fragmentation pathways of GSH conjugates. In the present study, a highly efficient methodology has been developed as an alternative approach for high-throughput screening and structural characterization of reactive metabolites using the linear ion trap mass spectrometer. In microsomal incubations, a mixture of glutathione [GSH, gamma-glutamyl-cystein-glycin] and the stable-isotope labeled compound [GSX, gamma-glutamyl-cystein-glycin-(13)C2-(15)N] was used to trap reactive metabolites, resulting in formation of both labeled and unlabeled conjugates at a given isotopic ratio. A mass difference of 3.0 Da between the natural and labeled GSH conjugate (mass tag) at a fixed isotopic ratio constitutes a unique mass pattern that can selectively trigger the data-dependent MS(2) scan of both isotopic partner ions, respectively. In order to eliminate the response bias of GSH adducts in the positive and negative mode, a polarity switch is executed between the mass tag-triggered data dependent MS(2) scan, and thus ESI- and ESI+ MS(2) spectra of both labeled and nonlabeled GSH conjugates are obtained in a single LC-MS run. Unambiguous identification of glutathione adducts was readily achieved with great confidence by MS(2) spectra of both labeled and unlabeled conjugates. Reliability of this method was vigorously validated using several model compounds that are known to form reactive metabolites. This approach is not based on the appearance of a particular product ion such as MH(+) - 129 and anion at m/z 272, whose formation can be structure-dependent and sensitive to the collision energy level; therefore, the present method can be suitable for unbiased screening of any reactive metabolites, regardless of their CID fragmentation pathways. Additionally, this methodology can potentially be applied to triple quadrupole or hybrid triple quadrupole mass spectrometers. 相似文献
Electrochemical oxidation of phenol in acidic aqueous solution was studied on a vitreous carbon electrode at different temperatures
in the range of 25–85 °C by cyclic voltammetry and chronoamperometry. The kinetic aspect of the phenol oxidation was investigated
as a function of its concentration and temperature. The electrode deactivation by formation of an adherent, compact, and insulating
polymeric film was examined by monitoring the decrease in the peak current of phenol oxidation during the course of successive
potential scans. Repeated potential scans in the region of water stability did not reactivate the electrode whatever the temperature
used. Chronoamperometric curves recorded at different potentials in the region of water decomposition shown that the electrochemical
activity of the electrode was partially restored even when performed at low temperature (25 °C). 相似文献
Nowadays, healthcare applications become among the most important services that help to improve the public safety through, for example, the prevention of the propagation of some epidemic diseases from patient to another or better from a location to another. Wireless Body Area Networks (WBANs) are considered among the major sources that enable the collection of such kind of data that shares in most cases the properties of big data and that needs to be stored and managed in an efficient manner. Regarding this need, Wireless Storage Area Networks (WSANs) have been considered among the alternatives to store generated health data. Even if these infrastructures enable the storage of huge volumes of data, there are some issues related to the efficient storage and processing of health data that still not resolved and that are of interest for the research communities. In this context, this paper proposes a cloud-based WSAN approach that enables the storage and the management of health data in an efficient manner by representing the collected data and their dependencies using Temporal Conceptual Graphs (TCGs). The validity of the generated graphs is verified by the proposed graph checker that enables the localization of semantic errors in such structure to prevent some threats to be realized for stored health data and to ensure the privacy of patients. The efficiency of the proposed approach is illustrated for different defined scenarios of diseases and their associated health data represented through generated TCGs. 相似文献
In this paper, we study the robustness of the proposed watermarking algorithm by Al-Nuaimy et al. (Digit Signal Process 21(6):764–779 2011) for audio signals which is based on singular value decomposition (SVD). It has been concluded that it is fundamentally flawed in its design, in that it falls to two ambiguity attacks where the extracted watermark is not the embedded one but determined by the reference watermark. In the first attack, when a watermarked audio signal is rewatermarked by an attacker’s watermark, this one can be easily extracted to claim ownership of the original audio signal. In the second attack, during the extracting process when an attacker uses the singular vectors of his watermark, he can extract the attacker’s watermark. Therefore, he can claim ownership of the watermarked audio signal. The experimental results prove that the proposed attacks create a false positive detection in watermark extraction. Therefore, Al-Nuaimy et al. algorithm cannot be used for security systems, data hiding and copyright protection.
A drastic degradation of the magnetic behaviour of low carbon or silicon steels occurs with weak plastic deformations, associated with strong second order internal stresses. A micromechanical modelling of plasticity is linked to a multiscale modelling of the magnetic behaviour. Experimental results and modelled data are compared. 相似文献