We previously reported that microscale Cu/Fe bimetal could be used for the dechlorination of hexachlorobenzene (HCB), a representative polychlorinated persistent organic pollutant (POPs). But slow ...reduction rate and rather incomplete dechlorination were reached. In this study, HCB dechlorination by nanoscale Fe and Cu/Fe was evaluated. It was found that HCB reduction by nanoscale Fe was rather slow, and the reduction was significantly increased by nanoscale Cu/Fe. Near complete reduction of HCB was obtained by nanoscale Cu/Fe for 48
h treatment. HCB was quickly dechlorinated to PeCB, TeCBs, TCBs and DCBs without selectivity via a stepwise process. The reduction rate and dechlorination extent were much higher compared with microscale Cu/Fe. Lowering pH during reduction showed slightly negative influence on HCB reduction by nanoscale Cu/Fe due to retarded co-precipitation. A catalytic hydrogenation process on Cu surface through iron oxide film was suggested for the increased HCB reduction by Cu coating on nanoscale Fe. This study proved that using a much cheaper bimetallic iron of nanoscale Cu/Fe than nanoscale Pd/Fe could also achieve the effective dechlorination of HCB.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
To study the effects of different types of aquatic products and gastrointestinal digestion on tropomyosin (TM), this article selects three crustaceans (Litopenaeus vannamei, Penaeus monodon and ...Eriocheir sisensis) and two shellfish (Venerupis philippinarum and Sinonovacula constricta) as the research object. Simulated gastric fluid (SGF) and intestinal fluid (SIF) were used to digest the boiled muscles of 5 kinds of aquatic products, the protein composition and immune activity of the subtracted products were analyzed by SDS-PAGE and ELISA. The results showed that all samples were digested faster in SIF, and intestinal was the main place where TM activity was lost. And shellfish (stomach: 86.5%~86.8%, intestine: 90.8%~92.2%) had a significantly better immune activity reduction effect than crustacean aquatic products (stomach: 64.7%~67.7%, intestine: 89.0%~91.5%). By electron microscopy, the myofibrils of crustaceans (156.4~185.8 μm) were significantly longer than that of shellfish (125.0~134.6 μm), and its wid
LoRaWAN is widely used in information monitoring under star topology. However, for linear topology applications, the LoRaWAN protocol requires the introduction of a large number of gateways, which ...will lead to information asymmetry, energy waste, and low network utilization. An energy-saving LoRa linear network system with adaptive transmission parameter is proposed. LoRa multihop technology is used for communication between nodes in the system, and narrowband Internet of Things module is used to the communicate with cloud platform. The adaptive transmission parameter mechanism is adopted in the system, which improves the adaptability of the linear network to changes in link channel conditions and reduces unnecessary energy consumption. At the same time, the flexibility and robustness of self-organizing networks are enhanced. In addition, optimized duty cycle strategies are employed to further reduce the operating power consumption. After LoRaSim simulation experiments, the results show that in the changing radio channel environment, the adaptive transmission parameter mechanism could achieve a dynamic balance between data extraction rate and energy consumption. After field tests, the results show that the system not only operates stably, but also could reduce the operating energy consumption of the LoRa linear network. The system proposed in this article is suitable for linear topological structure scenes such as river hydrological monitoring, oil pipeline monitoring, and long-distance railway monitoring.
The present study investigated the volatile compounds in nearly three-year shrimp sauces and the effects of different fermentation and storage time on the integral aroma characteristics. The 89 ...volatile compounds were identified by solid phase microextraction (SPME) and gas chromatography-mass spectrometry (GC-MS) analysis. Compared with the other two samples, the shrimp sauces which fermented and storage for 2 years has the highest umami amino acid content and the better flavor. The results of electronic nose (e-nose) and electronic tongue (e-tongue) detection to distinguish the aroma characteristics of different samples demonstrated good agreement with those obtained by GC-MS analysis. These results suggested that proper fermentation and storage time are critical to the flavor quality of shrimp sauces.
•Eighty-nine volatile compounds were detected in shrimp sauces.•Shrimp sauce fermented for 2 years has the highest umami amino acid content.•The flavor and overall quality of shrimp sauce fermented for 2 years was better.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
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•Anchovy sauce shows different taste profiles under different fermentation time.•Taste substances in anchovy sauce increased during early stage of fermentation.•Peptides and amino ...acids might contribute significantly to the taste of anchovy sauce.•A correlation model between protease activities with taste substances was established.
Anchovy sauce shows different taste profiles under different fermentation time. The change rules of free amino acids was measured by amino acid analyzer, and other taste substances, such as nucleotides and organic acids in anchovy sauce under different fermentation time were also investigated. Moreover, the correlation between protease activity and taste substances in anchovy sauce fermentation was analyzed by orthogonal partial least squares. Throughout the fermentation process, the taste substances in anchovy sauce increased during early months and then decreased as time increased. The content of amino acid nitrogen, TCA-soluble peptides, 5′-nucleotides (AMP, GMP, IMP) and organic acids (lactic acid, succinic acid) in anchovy sauce increased by 26%, 33%, (45%, 35%, 68%) and (27%, 2%) respectively in comparison with 6 months fermentation. Total amino acid content reached its maximum after 18 months fermentation. Results of electronic tongue demonstrated that the umami of anchovy sauce after 12 months fermentation increased by 17% in comparison with 6 months fermentation. A model correlating changes in protease activity with taste formation suggested that protease activity impacted the content of Ala, Glu, Lys, Asp, Leu, TCA-soluble peptides and succinic acid. This study can provide empirical evidence to guide the efficient processing of anchovy sauce.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
To identify the key amino acids (AAs) affecting the allergenicity of hemocyanin (HC) allergens from Chinese mitten crabs, in this study, two epitopes, P1-SHFTGSKSNPEQR and P2-LSPGANTITR were employed ...and four potential key AAs (P1: F3 and N9 and P2: N6 and R10) were predicted. Mast cell and mouse models revealed that four mutants induced lower levels of immunoglobulin E (IgE) and Th2 type cytokines (15.47–49.89 %), proving that F3, N9, N6, and R10 were the key AAs of two epitopes. Mutants reduce allergic responses via the Th2 pathway. However, the roles of every key AA affecting allergenicity were different (P1-F3 > N9 and P2-N6 > R10). In addition, lower transport and higher efflux were observed in the mutants during transport absorption by Caco-2 cells. The allergenicity of HC was stronger when the transport absorption efficiency of epitopes and mutants was higher and their efflux was lower. Our study provides a novel method for revealing the allergenic molecular mechanisms of food allergens.
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•Four key AAs (F3, N9, N6, and R10) affecting allergenicity were identified.•Transport absorption and efflux of epitope significantly affect HC allergenicity.•Key AA mutation could reduce allergic response via Th2 pathway.•The role of every key AA affecting allergenicity of HC was different.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
A β-
d-glucosidase, with broad regiospecific activity and designated as G II, was purified to homogeneity from the acetone power of viscera of the China white jade snail (
Achatina fulica). G II ...consisted of two identical subunits (110
kDa) with a native molecular mass of 220
kDa. G II was stable over a wide pH range (4–10 at 30
°C for 24
h) and at a relatively high temperature (50
°C for 8
h). Moreover, it can cleave both β-(1
→
2)-glucosidic linkage at 3-C and β-(1
→
6)-glucosidic linkage at 20-C of ginsenosides and can hydrolyze ginsenosides Rb
1, Rb
2, Rb
3 and Rc into their active metabolites, compound K, compound Y, Mx, and Mc, respectively. The optimal activity against
p-nitrophenyl-β-
d-glucopyranoside (
pNPG) was at 50
°C and pH 5.0. Under the same condition, the
K
m for
pNPG was 0.224
mM with a
V
max of 0.203
mmol nitrophenol min
−1
mg
−1. Of the substrates tested, G II specifically hydrolyzed the β-
d-glucosides involving aryl-β-glucosides, alkyl-β-glucosides, and β-linked disaccharides (i.e. sophorose, gentiobiose, and cellobiose). These findings make the novel enzyme potentially useful in biotransformation processes as well as in the modification of multiple ginsenosides.
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•The molecular properties of Eriocheir sinensis HC were revealed for the first time.•Heat treatment induced an increase in β-sheet of HC and reduced its ...allergenicity.•Anti-digestibility of HC was different from allergen tropomyosin of crustaceans.•Five allergenic epitopes of HC were validated by murine sensitization model.
Hemocyanin in crustaceans is an allergen for humans. However, little information was available on its molecular, structural and allergenic properties. In this study, the purified natural protein was identified as Eriocheir sinensis HC by LC-MS/MS, which was allergenic because its reaction with the serum IgE of crustacean patients. Results of the molecular properties showed that, HC was resistant to trypsin digestion, but not a heat-stable protein. Boiling (55.05 ± 3.50 %) and steaming (66.84 ± 1.65 %) induced an increase in β-sheet and decreased allergenicity of HC. By comparing the amino acid sequences of eight crustaceans, HC was found to be highly conserved. Five epitopes of HC were identified and validated by murine sensitization model, and two of them (P3 and P10) were exactly as the predicted by six types of bioinformatics. Multiple bioinformatics analysis combining with murine sensitization model seemed to be effective way for identification of allergenic epitopes.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
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•A novel model, IR-CAM, was developed by infrared spectroscopic chemometrics.•TM could be identified within 10 min by shared and unique fingerprint peaks group.•Rapid species ...differentiation of TM at the Class/Family level was achieved by IR-CAM.•The IR-CAM was a new tool for identification and traceability of food allergens.
To solve the lack of rapid and accurate methods for allergen identification and traceability, an infrared spectroscopic chemometric analytical model (IR-CAM) was established by combining infrared spectroscopy with principal component and cluster analysis. By comparing the second derivative infrared (SD-IR) spectra of 5 proteins and 14 crustaceans and shellfish tropomyosin (TM), 8 shared peaks and unique fingerprint peaks in the amide III region were found for crabs, shrimps, and shellfish. Based on the unique fingerprint peaks coexisting with shared peaks, allergen TM in crustaceans and shellfish could be identified within 10 min (cf. ELISA ∼ 4 h). Concurrently, the species differentiation of TM at the Class/Family level was achieved based on IR-CAM. Validation by fermented aquatic products TM (n = 60) demonstrated that the developed IR-CAM could simultaneously identify and differentiate TM in crustaceans and shellfish accurately. It could be applied for allergen detection and traceability of aquatic products on an antibody-free basis.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
