A discrete logistic steady-state equation with both positive and negative birth rate of population will be considered. By using sub- and upper-solution method, the existence of bounded positive ...solutions and the existence and uniqueness of positive solitons will be established. To this end, the Dirichlet eigenvalue problem with positive and negative coefficients is considered, and a general sub- and upper-solution theorem is also obtained.
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•Effects of thermal temperature on the shelf life of braised chicken were studied.•Thermal at 95 °C and 121 °C could prolong the shelf life of braised chicken.•Fresh odor of ...84 °C/95 °C-treated braised chicken was maintained during storage.•Clostridium and Bacillus were only very active in 84 °C-treated samples.•95 °C can be developed as one potential thermal temperature for braised chicken.
This work investigated the effects of different thermal temperatures (84 °C for 35 min, 95 °C for 30 min, and 121 °C for 20 min) on the shelf life and microbial diversity of Dezhou-braised chicken. During refrigerated storage at 4 °C, the increase rate of total viable counts, pH and TVB-N value, was lower in 95 °C-treated and 121 °C-sterilized groups, when compared with 84 °C-treated group. Electronic nose revealed that the fresh odor of Dezhou-braised chicken treated by 84 °C and 95 °C could be maintained during storage. Additionally, 95 °C contributed to the maintenance of good texture of chicken. High throughput sequencing showed that Bacillus and Clostridium were only very active in 84 °C-treated samples, but not in 95 °C-treated and 121 °C-sterilized samples. Taken together, 95 °C can be developed as one potential thermal treatment temperature for Dezhou-braised chicken, due to its positive effects on maintaining fresh odor and texture together with extending shelf life while also protecting food safety.
This study aimed to gain deeper insights into the microbiota composition and population dynamics, monitor the dominant bacterial populations and identify the specific spoilage microorganisms (SSOs) ...of vacuum-packed bacon during refrigerated storage using both culture-independent and dependent methods. High-throughout sequencing (HTS) showed that the microbial composition changed greatly with the prolongation of storage time. The diversity of microbiota was abundant at the initial stage then experienced a continuous decrease. Lactic acid bacteria (LAB) mainly Leuconostoc and Lactobacillus dominated the microbial population after seven days of storage. A total of 26 isolates were identified from different growth media using traditional cultivation isolation and identification method. Leuconostoc mesenteroides and Leuconostoc carnosum were the most prevalent species since day 15, while Lactobacillus sakei and Lactobacillus curvatus were only found on day 45, suggesting that they could be responsible for the spoilage of bacon. Serratia, Rahnella, Fusobacterium and Lactococcus underwent a dramatic increase at some point in individual batchs which may be considered as potential contributors to the spoilage.
•Both culture-dependent and culture-independent methods were applied.•Greater diversity were observed at the initial stage and then continuous decrease.•Leuconostocs and Lactobacillus takes absolute dominate after initial storage.•Leuconostocs mesenteroides, Leuconostocs carnosum, Lactobacillus sakei, Lactobacillus curvatus may be the SSOs.•The load of microorganisms are positively related to the storage time.
The BiOI/Bi2WO6/ACF composite photocatalysts with different loads were prepared by hydrothermal method, and the catalysts were characterized by XRD, SEM, TEM, BET, XPS, DRS and photocurrent ...responses. The photocatalytic activity of the samples was studied with the toluene as model pollutant. The results showed that 20%mol BiOI/Bi2WO6 was uniformly loaded on the activated carbon fiber (ACF), and Bi2WO6 (133) orthorhombic crystal face and BiOI (012) tetragonal crystal face can be observed on the catalyst surface. The specific surface area of 20% mol BiOI/Bi2WO6/ACF is 787 m2·g−1, which is much higher than that of Bi2WO6/ACF. BiOI and Bi2WO6 exist simultaneously in the BiOI/Bi2WO6 according to the results of XPS, which corresponds to the results of TEM characterization, indicating that the composites were successfully prepared, and the absorption band edge and intensity of Bi2WO6 was enhanced greatly by the compositing of BiOI. The toluene removal efficiency could arrive at 76.3% for the concentration of 500 mg/m3 with the 20%mol BiOI/Bi2WO6/ACF.
•A self-made photocatalytic reactor was designed.•20% mol BiOI/Bi2WO6 photocatalyst prepared by hydrothermal method was interlaced on ACF in clusters to form a dense film..•The lattice fringe spacing corresponded to the orthorhombic Bi2WO6 (133) and tetragonal BiOI (012) crystal face respectively.•The activity of 20% mol BiOI/Bi2WO6/ACF expressed the best performance and was higher than the monomer catalyst.
In this paper, we consider the following Choquard equation (CH)−Δu+u=(Iα∗|u|p)|u|p−2u+V(x)|u|q−2uinRN,u∈H1(RN),where N≥3, α∈((N−4)+,N), p∈2,N+αN−2), ...q∈(2,2NN−2)∩(1+(p−1)(N−2)αN2,1+2N(N−α)+N2(p−1)(N−2)α) and Iα is the Riesz potential. Under some suitable decay assumptions but without any symmetry property on V(x), we prove that the problem has infinitely many solutions, whose energy can be arbitrarily large.
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•The changes of PLs molecular species during processing were identified by ESI-MS/MS.•The PLs profiles were characterized by a variety of polyunsaturated acyl chains.•Most of PLs ...molecular species content decreased during processing except for LPLs.•10 potential PL markers were screened by PLS-DA to distinguish the operating units.•Thermal degradation is a major cause of the significant decrease of PLs content.
Knowledge of the changes in the phospholipid molecular species during processing is helpful to understanding the complicated mechanisms of lipid degradation and transformation. The shotgun lipidomics strategy was utilized to analyze the phospholipid (PL) molecular species in raw Pekin duck and the subsequent dynamic changes that occur during the processing of water-boiled salted duck (WSD). Only 110 PL molecular species have been identified in raw duck meat, while a total of 119 PL molecular species were identified during processing, including 33 phosphatidylcholines, 22 phosphatidylethanolamines, 13 phosphatidylglycerols, 18 phosphatidylinositols and 33 phosphatidylserines. Most of the content of PL molecular species gradually decreased during processing, while the content of most of the lysophospholipids (LPLs) increased. After reaching a maximum, the LPLs were obviously reduced during the 3 d of dry-ripening. The results showed that processing techniques, such as dry-curing, dry-ripening and boiling, had a significant effect on the changes in the PLs in WSD. We further screened 10 PL molecular markers, which can be used to distinguish different operating units.
In this paper, we study the semiclassical states for the fractional Choquard equation
where
, N>2s,
,
and
,
is a continuous potential satisfying suitable assumptions and
is a small parameter. Using ...the mountain pass lemma and the Brezis-Lieb lemma, we prove the existence and asymptotic behavior of groundstates for
and the nonexistence of solution for the minimization problem
for
, where
Inspired by the result, we further consider the existence and asymptotic behavior of groundstates for the above equation under a nonlocal perturbation, that is, equation
with
.
Change detection is a fundamental problem in remote sensing image processing. Due to the great advantages in learning the knowledge representations and the complex relationship from large-scale ...datasets, deep learning has made great progress in change detection tasks in remote sensing community. However, most of the existing methods based on deep learning for change detection are implemented by learning differences of image pairs directly without paying considerations in influences of unstructured and temporal changes, or called nature changes, such as light and seasonal changes. In this paper, an end-to-end deep learning network for remote sensing image change detection is proposed, aiming to accurately detect the change of regions from a high-resolution image pair by learning prototype similarity, in which the metric learning is used and it is one of the meta-learning methods to learn change prototypes from support image pairs. The similarity between the query image pairs and the change prototypes can be measured by a learnable CNN metric. The experimental results based on the two public change detection datasets of high-resolution satellite images, CDD and BCDD, show that our proposed method performs better than other state-of-the-art change detection methods with an improvement of 3.5% and 0.4%, respectively.
To identify the microbial community and origin of the spoilage flora of bacon, the changes in microbial population numbers and community structure were followed along the processing line, using ...culture-independent and culture-dependent methods. 16S rRNA gene amplicon sequencing (16S-seq) analysis showed that community complexity and structure significantly differed at different processing stages. Some 428 bacterial groups were ascertained at genus level, and Acinetobacter, Pseudomonas, Psychrobacter, and Brochothrix were the predominant bacteria on raw meats. After curing specimens dominated by Psychrobacter, Weissella, Vibrio, Leuconostoc, Myroides, Acinetobacter, and Lactobacillus, a total of 33 species were identified by traditional microbiological analyses and direct sequence determination methods. Our results indicated that curing should be considered one of the primary factors during various processing steps, presumably contaminating the products directly or indirectly.
•Both traditional cultivation methods and high-throughput sequencing were applied.•The load of microorgansims on raw meat and curing were higher.•Psychrobacter, Weissella, Vibrio, Leuconostoc and Lactobacillus were the predominant species since curing.•Curing should be considered one of the primary factors during the various processing steps.
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