Precautions for seafood consumers: An updated review of toxicity, bioaccumulation, and rapid detection methods of marine biotoxins.

Seafood products are globally consumed, and there is an increasing demand for the quality and safety of these products among consumers. Some seafoods are easily contaminated by marine biotoxins in natural environments or cultured farming processes. When humans ingest different toxins accumulated in seafood, they may exhibit different poisoning symptoms. According to the investigations, marine toxins produced by harmful algal blooms and various other marine organisms mainly accumulate in the body organs such as liver and digestive tract of seafood animals. Several regions around the world have reported incidents of seafood poisoning by biotoxins, posing a threat to human health. Thus, most countries have legislated to specify the permissible levels of these biotoxins in seafood. Therefore, it is necessary for seafood producers and suppliers to conduct necessary testing of toxins in seafood before and after harvesting to prohibit excessive toxins containing seafood from entering the market, which therefore can reduce the occurrence of seafood poisoning incidents. In recent years, some technologies which can quickly, conveniently, and sensitively detect biological toxins in seafood, have been developed and validated, these technologies have the potential to help seafood producers, suppliers and regulatory authorities. This article reviews the seafood toxins sources and types, mechanism of action and bioaccumulation of marine toxins, as well as legislation and rapid detection technologies for biotoxins in seafood for official and fishermen supervision.

A Novel Multifunctional Crosslinking PVA/CMCS Hydrogel Containing Cyclic Peptide Actinomycin X2 and PA@Fe with Excellent Antibacterial and Commendable Mechanical Properties.

Bacterial infected environments and resulting bacterial infections have been threatening the human health globally. Due to increased bacterial resistance caused by improper and excessive use of antibiotics, antibacterial biomaterials are being developed as alternatives to antibiotics in some cases. Herein, an advanced multifunctional hydrogel with excellent antibacterial properties, enhanced mechanical properties, biocompatibility and self-healing performance, was designed through freezing-thawing method. This hydrogel network is composed of polyvinyl alcohol (PVA), carboxymethyl chitosan (CMCS), protocatechualdehyde (PA), ferric iron (Fe) and an antimicrobial cyclic peptide actinomycin X2 (Ac.X2). The double dynamic bonds among protocatechualdehyde (PA), ferric iron (Fe) and carboxymethyl chitosan containing coordinate bond (catechol-Fe) as well as dynamic Schiff base bonds and hydrogen bonds endowed the hydrogel with enhanced mechanical properties. Successful formation of hydrogel was confirmed through ATR-IR and XRD, and structural evaluation through SEM analysis, whereas mechanical properties were tested with electromechanical universal testing machine. The resulting PVA/CMCS/Ac.X2/PA@Fe (PCXPA) hydrogel has favorable biocompatibility and excellent broad-spectrum antimicrobial activity against both S. aureus (95.3 %) and E. coli (90.2 %) compared with free-soluble Ac.X2, which exhibited subpar performance against E. coli reported in our previous studies. This work provides a new insight on preparing multifunctional hydrogels containing antimicrobial peptides as antibacterial material.

Characteristics of denitrification in a vertical baffled bioreactor.

A vertical baffled bioreactor (VBBR) was employed for tertiary denitrification. Its features were designed to minimize the demand for externally supplied electron donor by minimizing net biomass synthesis and oxygen respiration. Over a two-year period, complete denitrification was realized routinely in the VBBR. The nitrate-removal rate was proportion to the influent COD/N ratio, with complete denitrification possible for COD/N ratios >3 gCOD/gN. Batch kinetic tests carried out at the end of years 1 and 2 documented that supplied electron donor was oxidized in the first 1-2 h, but nitrate and nitrite reductions occurred predominantly after 2 h and were driven by internally stored electron donor. Measurements confirmed that the VBBR minimized the demand of added electron donor: The observed yield was only 0.05 mgVSS/mgCOD, and the COD demand for O2 respiration was only 1-6.7% of the COD demand for N reductions. Biofilm samples taken from the upper and lower ports in cylinder of VBBR had similarly high alpha diversity and dominant genera, but the upper biofilm had a denitrification rate about 70% greater than the lower biofilm. The higher denitrification rate in the upper biofilm correlated its higher content of active biomass.

Bioavailable electron donors from ultrasound-treated biomass for stimulating denitrification.

Finding low-cost electron donors to drive denitrification is an important target for many municipal wastewater treatment plants (MWTPs). Excess sludge (biomass) potentially is a low-cost electron donor generated internally to the MWTP, but it has to be made more bioavailable. Aerobic and anoxic biomasses were treated with ultrasound, and their supernatants were used as electron donors for stimulating denitrification. The supernatant from ultrasound-treated anoxic biomass achieved 54% faster nitrate-N removal than did supernatant from the treated aerobic biomass, and the supernatant of untreated biomass was ineffective as an electron donor. UV illumination of the supernatants further enhanced the rates, with increments of 19% and 14%, respectively for the aerobic and anoxic supernatants. Sodium acetate at a range of initial concentrations was compared as a readily bioavailable electron donor to gauge the acceleration impact of the supernatants as equivalent bioavailable chemical oxygen demand (COD). The total chemical oxygen demand (TCOD) of the supernatant harvested from anoxic biomass without UV illumination was 76% bioavailable, while its bioavailable TCOD was 78% after UV illumination. For the supernatant from the aerobic biomass, the bioavailable fractions were, respectively, 56% and 58% without and with UV illumination. The greatest impact for converting excess biomass into a source of bioavailable electron donor to drive denitrification came from ultrasound treatment of the biomass, which disrupted the biomass to form particulate chemical oxygen demand (PCOD) that was bioavailable. PCOD was at least 51% bioavailable, and it contributed no less than 82% of the bioavailable COD.

Electrochemical performance of Cu6Sn5 alloy anode materials for lithium-ion batteries fabricated by controlled electrodeposition.

Combining electrodeposition and heat treatment is an effective method to successfully fabricate Cu6Sn5 alloy materials, in which the S2 alloy electrode is electrodeposited at 1.2 A dm-2 current density with uniform and compact morphology. The characterization results show that monoclinic η'-Cu6Sn5 and hexagonal η-Cu6Sn5 phases fabricated at the appropriate current density exhibit excellent electrochemical performance. The optimal Cu6Sn5 alloy anode material boasts not just a significantly high discharge specific capacity of 890.2 mA h g-1 with an initial coulombic efficiency (ICE) of 73.96%, but also achieves an adequate discharge specific capacity of 287.1 after 50 cycles at 100 mA h g-1. Moreover, the electrodeposited Cu6Sn5 alloy materials also possessed a lower transfer resistance of 42.45 Ω and an improved lithium-ion diffusion coefficient of 2.665 × 10-15 cm2 s-1 at the current density of 1.2 A dm-2. Therefore, preparing the Cu6Sn5 alloy thin-film electrode could be a cost-effective and straightforward method by electrodeposition from cyanide-free plating baths to develop anode components suitable for lithium-ion battery applications.

Preparation and properties of polyvinyl alcohol/chitosan-based hydrogel with dual pH/NH3 sensor for naked-eye monitoring of seafood freshness.

To address the issue of food spoilage causing health and economic loss, we developed a pH/NH3 dual sensitive hydrogel based on polyvinyl alcohol/chitosan (PVA/CS) containing chitosan-phenol red (CP). The CP was synthesized via Mannich reaction and immobilized it in PVA/CS hydrogel through freezing/thawing method to prepare the final PVA/CS/CP hydrogel. The synthesis of CP was confirmed by 1H NMR, FT-IR, XRD, UV-vis, and XPS. The characteristics of hydrogel were evaluated by FT-IR, XRD, SEM, mechanical properties, thermal stability, leaching, and color stability tests. The PVA/CS/CP hydrogel showed distinctly different color at various pH and NH3 vapor levels (yellow to purple). The hydrogel exhibited obvious color changes (ΔE = 46.95) in response to shrimp spoilage, stored at 4 °C. It showed positive and strong correlation between the ΔE values of the indicator hydrogel and total volatile basic nitrogen (TVB-N) as (R2 = 0.9573) and with pH as (R2 = 0.8686), respectively. These results clearly show that the PVA/CS/CP hydrogel could be applied for naked-eye real-time monitoring of seafood freshness in intelligent packaging.

Research on the Identification Mechanism of Coal Gangue Based on the Differences of Mineral Components.

For coal and gangue, intelligent sorting processes for separation, the use of coal and gangue mineral components with different fundamental differences, and the study of different properties of minerals and coal with different scales and density regarding the gray value change law are presented. The results show that the gray value of single minerals and mixed minerals gradually decreases with the increase of their thickness and density. The greater the density of minerals, the smaller the gray value at the same thickness, and the same rule applies to different coal ranks. Via regression analysis methods, the values of the regression equation parameter a of pure minerals for graphite, quartz, kaolinite, and montmorillonite are 59.25, 65.69, 61.61, and 58.02 in the high-energy region, respectively. In the low-energy region, they are 174.95, 177.31, 186.95, and 161.81. For the regression equation parameter of mixed minerals in the form of two mixed minerals (graphite and quartz, kaolinite, or montmorillonite) and three kinds of mineral mixing (graphite-kaolinite and quartz; graphite-montmorillonite and quartz; graphite-kaolinite and montmorillonite), the gray values are 151.12, 156.00, 153.13,152.43, 152.98, and 151.98 in the high-energy region, respectively; in the low-energy region, they are 193.34, 201.34, 192.93, 191.26, 194.68, and 193.08. The phenomenon for the gray range of two kinds of single minerals locates in the range of mixed minerals that was formed from a single mineral observed after the regression equation of mixed mineral was verified by a single mineral, which agrees with the X-ray recognition pattern. In the end, as the density of coking coal, fat coal, and gas coal increases, the gray value decreases, which was in agreement with single- and mixed-mineral analyses.

Human cathelicidin LL-37 exerts amelioration effects against EHEC O157:H7 infection regarding inflammation, enteric dysbacteriosis, and impairment of gut barrier function.

Enterohaemorrhagic Escherichia coli (EHEC) O157:H7 infection impairs intestinal barrier function, causing intestinal inflammation and enteric dysbacteriosis. The human cathelicidin LL-37 can regulate excessive inflammatory responses, barrier function, and balance the intestinal microbial community; however, little is known about its effects on inflammation, intestinal barrier function, and microbiota disorders in EHEC O157:H7-infected mice. In this study, we investigated the protective effect of LL-37 against EHEC O157:H7 infection and elucidated the underlying mechanism using a mouse model. LL-37 treatment was found to inhibit body weight loss, restore edema and destruction of the intestinal villi, and significantly reduce epithelial apoptosis (P < 0.05) in EHEC O157:H7-infected mice. Furthermore, inflammatory infiltration of macrophages and neutrophils into the jejunum and colon was significantly decreased (P < 0.05). LL-37 significantly downregulated the production of pro-inflammatory cytokines (IL-1ß, IL-6, and TNF-α) (P < 0.05) and upregulated the anti-inflammatory cytokine (IL-10) during EHEC O157:H7 infection. LL-37 increased the expression of tight junction proteins (ZO-1, ZO-2, claudin-1, and occludin), which are associated with intestinal barrier function, and had a positive effect on EHEC O157:H7-induced microbial disorders, particularly in terms of the inflammation-related microbiota. LL-37 also significantly decreased the E. coli load in the liver and spleen (P < 0.01) and restored the structure of the liver and kidney. Taken together, LL-37 conferred protection in a EHEC O157:H7-induced mouse model by reducing intestinal inflammation, enhancing intestinal barrier function, and restoring the balance of the intestinal microbiota, which indicates the therapeutic potential of LL-37 against pathogen infection.