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  • MDPI AG  (5)
  • Cheng, Hai  (5)
  • 1
    In: Quaternary, MDPI AG, Vol. 3, No. 1 ( 2020-03-19), p. 8-
    Abstract: We would like to thank Gebregiorgis et al [...]
    Type of Medium: Online Resource
    ISSN: 2571-550X
    Language: English
    Publisher: MDPI AG
    Publication Date: 2020
    detail.hit.zdb_id: 2934608-3
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  • 2
    In: Foods, MDPI AG, Vol. 12, No. 4 ( 2023-02-17), p. 862-
    Abstract: Robust and sensitive ultrahigh-performance liquid chromatography–tandem mass spectrometry (UPLC–MS/MS) combined with the quick, easy, cheap, effective, rugged, and safe (QuEChERS) method was applied for the detection of seven Alternaria toxins (ATs) in tuberous crops. The influence of tuber conditions (fresh, germinated, and moldy) during storage on the concentration of the seven ATs is also investigated. ATs were extracted with acetonitrile under acidic conditions and purified with a C18 adsorbent. ATs were scanned with electrospray ionization (positive/negative ion) dynamic switching and detected in MRM mode. Calibration curve analysis results reveal good linear relationships in all toxin concentration ranges (R2 〉 0.99). The limit of detection and limit of quantification were 0.25–0.70 and 0.83–2.31 μg/kg, respectively. The average recoveries of the seven ATs were 83.2–104% with intra-/inter-day precision at 3.52–6.55% and 4.02–7.26%, respectively. The developed method provided adequate selectivity, sensitivity, and precision in detecting the seven ATs at trace levels, and dispensed with standard addition or matrix-matched calibration to compensate for matrix effects. ATs in the fresh, germinated, and moldy samples of tuberous crops in storage (taro, potato, sweet potato, yam, cassava) were analyzed with this method, and the concentrations were 2.01–14.51 μg/kg and significantly increased with storage duration. ALS was detected in most samples, whereas no quantities of ALT and ATX-I were detected. AME was often detected in combination with AOH in sweet potatoes. TeA and Ten were mostly detected in taro, potato, and yam. The established method could be used for the simultaneous detection and quantification of multicomponent toxins in elaborate matrices.
    Type of Medium: Online Resource
    ISSN: 2304-8158
    Language: English
    Publisher: MDPI AG
    Publication Date: 2023
    detail.hit.zdb_id: 2704223-6
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  • 3
    In: Minerals, MDPI AG, Vol. 10, No. 1 ( 2020-01-17), p. 74-
    Abstract: Four saline lakes in the northeast of Qaidam Basin were selected to explore the distribution characteristics and influencing factors of uranium isotopes in lake waters with high evaporation background. The 238U concentration and the activity ratios of 234U/238U ([234U/238U]AR) showed that there was no significant change in the same lake, but there was a certain degree of difference in the distribution between different lakes. We found that aqueous 238U concentration within a certain range increased with an increase in TDS (total dissolved solid) and salinity, as was also the case with pH. As in natural waters, the pH affects the speciation of 238U, but TDS and salinity affect the adsorption process of aqueous 238U. Further, the replenishment of water will also affect the uranium isotope concentration for lakes, but it is not the main influencing factor for saline lakes. Therefore, we suggest that pH is the dominant factor affecting changes in aqueous 238U concentration of the sampled saline lakes. The [234U/238U] AR in these saline lakes are closely related to the input water and the associated water–rock interactions involving sediments, atmosphere dust, and organic material, etc. during the evolution stage, metamorphous degree, and hydrochemistry of the saline lakes. Lake water samples collected in the maximum and minimum discharge water period, were used to evaluate the seasonal distribution characteristics of aqueous 238U, and we found that 238U concentration did not show an evident change with the seasons in these saline lakes. If the 238U concentration and [234U/238U] AR can remain consistent during a period of time, then the sediment ages and/or sedimentation rates could be determined by lake sediment and/or biogenic carbonate in future, thus allowing for the accurate reconstruction of the paleoclimate and paleoenvironment.
    Type of Medium: Online Resource
    ISSN: 2075-163X
    Language: English
    Publisher: MDPI AG
    Publication Date: 2020
    detail.hit.zdb_id: 2655947-X
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  • 4
    Online Resource
    Online Resource
    MDPI AG ; 2019
    In:  Entropy Vol. 21, No. 10 ( 2019-09-30), p. 960-
    In: Entropy, MDPI AG, Vol. 21, No. 10 ( 2019-09-30), p. 960-
    Abstract: In recent years, a chaotic system is considered as an important pseudo-random source to pseudo-random number generators (PRNGs). This paper proposes a PRNG based on a modified logistic chaotic system. This chaotic system with fixed system parameters is convergent and its chaotic behavior is analyzed and proved. In order to improve the complexity and randomness of modified PRNGs, the chaotic system parameter denoted by floating point numbers generated by the chaotic system is confused and rearranged to increase its key space and reduce the possibility of an exhaustive attack. It is hard to speculate on the pseudo-random number by chaotic behavior because there is no statistical characteristics and infer the pseudo-random number generated by chaotic behavior. The system parameters of the next chaotic system are related to the chaotic values generated by the previous ones, which makes the PRNG generate enough results. By confusing and rearranging the output sequence, the system parameters of the previous time cannot be gotten from the next time which ensures the security. The analysis shows that the pseudo-random sequence generated by this method has perfect randomness, cryptographic properties and can pass the statistical tests.
    Type of Medium: Online Resource
    ISSN: 1099-4300
    Language: English
    Publisher: MDPI AG
    Publication Date: 2019
    detail.hit.zdb_id: 2014734-X
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  • 5
    In: Foods, MDPI AG, Vol. 9, No. 3 ( 2020-03-09), p. 312-
    Abstract: Exploring the spoilage mechanism of Spanish mackerel is important to reduce the waste of Spanish mackerel and extend its shelf life. Cold chain logistics are commonly used to maintain the high quality and prolong the shelf life of aquatic products in circulation and storage. We assessed the sensory (body surface, odor, fish gills, fish elasticity, eyes, and overall assessment), chemical (total volatile base nitrogen (TVB-N), pH and 2-thiobarbituric acid (TBA)), and microbial characteristics (total viable counts (TVCs) and lactic acid bacteria) of Spanish mackerel combined with high-throughput sequencing at frequent intervals to determine their freshness and specific spoilage organisms (SSOs) during 0 °C cold chain logistics. Results showed that TVB-N, TBA, and TVCs correlated well (R2 〉 0.90) with the sensory scores with prolonged circulation and storage time. The SSOs of Spanish mackerel were Proteobacteria in phylum and Pseudomonas in genus. The shelf life of mackerel under the 0 °C ice-stored cold chain system was approximately seven days, which is roughly three days longer compared with the traditional low-temperature storage method. These findings indicated that the freshness evaluation of Spanish mackerel in cold-chain circulation could be achieved by selecting appropriate chemical, microbial, and sensory indices. The study contributes to extend the shelf life of cold-chain Spanish mackerel by inhibiting the growth of dominant bacteria and provides a basis for the development of methods and tools to predict the shelf life of Spanish mackerel.
    Type of Medium: Online Resource
    ISSN: 2304-8158
    Language: English
    Publisher: MDPI AG
    Publication Date: 2020
    detail.hit.zdb_id: 2704223-6
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