RESUMO
Microplastics (MPs) and pesticides are two categories contaminants with proposed negative impacts to aqueous ecosystems, and adsorption of pesticides on MPs may result in their long-range transport and compound combination effects. Florpyrauxifen-benzyl, a novel pyridine-2-carboxylate auxin herbicide has been widely used to control weeds in paddy field, but the insights of which are extremely limited. Therefore, adsorption and desorption behaviors of florpyrauxifen-benzyl on polyvinyl chloride (PVC), polyethylene (PE) and disposable face masks (DFMs) in five water environment were investigated. The impacts of various environmental factors on adsorption capacity were evaluated, as well as adsorption mechanisms. The results revealed significant variations in adsorption capacity of florpyrauxifen-benzyl on three MPs, with approximately order of DFMs > PE > PVC. The discrepancy can be attributed to differences in structural and physicochemical properties, as evidenced by various characterization analysis. The kinetics and isotherm of florpyrauxifen-benzyl on three MPs were suitable for different models, wherein physical force predominantly governed adsorption process. Thermodynamic analysis revealed that both high and low temperatures weakened PE and DFMs adsorption, whereas temperature exhibited negligible impact on PVC adsorption. The adsorption capacity was significantly influenced by most environmental factors, particularly pH, cations and coexisting herbicide. This study provides valuable insights into the fate of florpyrauxifen-benzyl in presence of MPs, suggesting that PVC, PE and DFMs can serve as carriers of florpyrauxifen-benzyl in aquatic environment.
Assuntos
Herbicidas , Praguicidas , Poluentes Químicos da Água , Microplásticos/toxicidade , Microplásticos/química , Plásticos/química , Adsorção , Ecossistema , Água , Polietileno/química , Praguicidas/análise , Herbicidas/análise , Poluentes Químicos da Água/análiseRESUMO
Biomass from agriculture, forestry, and urban wastes is a potential renewable organic resource for energy generation. Many investigations have demonstrated that anaerobic fungi and methanogens could be co-cultured to degrade lignocellulose for methane generation. Thus, this study aimed to evaluate the effect of natural anaerobic fungi-methanogens co-culture on the methane production and lignocellulosic degradation of wastes from rice, corn and sugarcane. Hu sheep rumen digesta was used to develop a natural anaerobic fungi-methanogen co-culture. The substrates were rice straw (RS), rich husk (RH), corn stover (CS), corn cobs (CC), and sugarcane baggage (SB). Production of total gas and methane, metabolization rate of reducing sugar, glucose, and xylose, digestibility of hemicellulose and cellulose, activity of carboxymethylcellulase and xylanase, and concentrations of total acid and acetate were highest (P < 0.05) in CC, moderate (P < 0.05) in RS and CS, and lowest (P < 0.05) in SB and RH. The pH, lactate and ethanol were lowest (P < 0.05) in CC, moderate (P < 0.05) in RS and CS, and lowest (P < 0.05) SB and RH. Formate was lowest (P < 0.05) in CC, RS and CS, moderate (P < 0.05) in SB, and lowest (P < 0.05) in RH. Therefore, this study indicated that the potential of methane production and lignocellulosic degradation by natural anaerobic fungi-methanogens co-culture were highest in CC, moderate in RS and CS, and lowest in SB and RH.
Assuntos
Euryarchaeota , Lignina , Oryza , Saccharum , Animais , Ovinos , Zea mays , Anaerobiose , Técnicas de Cocultura , FungosRESUMO
Copper oxide nanoparticles (CuO NPs) and ciprofloxacin (CIP) have ecological risk to humans and ecosystems. Polyvinylchloride microplastics (PVC MPs), as a representative of microplastics, may often coexist with CuO NPs and CIP in wastewater treatment systems due to their widespread application. However, the co-impact of PVC MPs in wastewater systems contained with CuO NPs and CIP on nitrogen removal and ecological risk is not clear. In this work, PVC MPs co-impacts on the toxicity of CuO NPs and CIP to aerobic granular sludge (AGS) systems and potential mechanisms were investigated. 10 mg/L PVC MPs co-addition did not significantly affect the nitrogen removal, but it definitely changed the microbial community structure and enhanced the propagation and horizontal transfer of antibiotics resistance genes (ARGs). 100 mg/L PVC MPs co-addition resulted in a raise of CuO NP toxicity to the AGS system, but reduced the co-toxicity of CuO NPs and CIP and ARGs expression. The co-impacts with different PVC MPs concentration influenced Cu2+ concentrations, cell membrane integrity, extracellular polymeric substances (EPS) contents and microbial communities in AGS systems, and lead to a change of nitrogen removal.
Assuntos
Microbiota , Nanopartículas , Humanos , Esgotos , Microplásticos , Antibacterianos , Plásticos , Eliminação de Resíduos Líquidos , Nitrogênio , Desnitrificação , Nanopartículas/química , Ciprofloxacina , Cloreto de Polivinila , Reatores BiológicosRESUMO
Low efficiency of anaerobic digestion and membrane fouling, treating landfill leachate, are big barriers in the application of anaerobic membrane bioreactor (AnMBR). Anaerobic digestion enhancement and membrane fouling mitigation of AnMBR with graphite addition, treating landfill leachate, were investigated in this study. The effect of graphite on organics removal, biogas production, methane content in biogas, membrane fouling, microbial responses and foulant compositions were analyzed. With the graphite addition, chemical oxygen demand (COD) removal of 78% was achieved for influent COD concentration of 3000 mg/l, which was significantly higher than the stage without graphite addition (65%) for influent COD concentration of 2000 mg/l. Similarly, methane content in biogas with graphite addition was 56%, while without graphite addition it was 46%. These digestion improvements were due to the promotion of organics degradation, facilitated by direct interspecies electron transfer (DIET) mechanism via graphite addition in AnMBR. The graphite addition prolonged membrane cleaning cycle from 13 days to 30 days. Protein content in loosely bound extracellular polymeric substance (LB-EPS) was the main fouling agent, which decreased with the graphite addition. The main mechanism behind membrane fouling mitigation was the protein content reduction in LB-EPS, which was biodegraded by Trichococcus being increased in relative abundance with the graphite addition. Furthermore, abundance of Denitratisoma decreased in anaerobic sludge and its accumulation reduced on membrane surface, subsequently membrane fouling was mitigated. Overall, graphite addition in AnMBR is a potential eco-innovative approach that efficiently removes pollutants from landfill leachate, enhances biogas quality and mitigates membrane fouling.
Assuntos
Grafite , Poluentes Químicos da Água , Anaerobiose , Biocombustíveis , Reatores Biológicos , Matriz Extracelular de Substâncias Poliméricas/metabolismo , Membranas Artificiais , Metano , Esgotos , Eliminação de Resíduos Líquidos , Águas ResiduáriasRESUMO
Banana is a major fruit crop throughout the world with abundant lignocellulose in the pseudostem and rachis residues for biofuel production. In this study, we collected a total of 11 pseudostems and rachis samples that were originally derived from different genetic types and ecological locations of banana crops and then examined largely varied edible carbohydrates (soluble sugars, starch) and lignocellulose compositions. By performing chemical (H2SO4, NaOH) and liquid hot water (LHW) pretreatments, we also found a remarkable variation in biomass enzymatic saccharification and bioethanol production among all banana samples examined. Consequently, this study identified a desirable banana (Refen1, subgroup Pisang Awak) crop containing large amounts of edible carbohydrates and completely digestible lignocellulose, which could be combined to achieve the highest bioethanol yields of 31-38% (% dry matter), compared with previously reported ones in other bioenergy crops. Chemical analysis further indicated that the cellulose CrI and lignin G-monomer should be two major recalcitrant factors affecting biomass enzymatic saccharification in banana pseudostems and rachis. Therefore, this study not only examined rich edible carbohydrates for food in the banana pseudostems but also detected digestible lignocellulose for bioethanol production in rachis tissue, providing a strategy applicable for genetic breeding and biomass processing in banana crops.
Assuntos
Biocombustíveis , Biomassa , Temperatura Alta , Lignina/química , Musa/química , Água , HidróliseRESUMO
In this study, rumen content was used to obtain three enrichments of anaerobic fungi and methanogens (F + M enrichment), bacteria and methanogens (B + M enrichment), and whole rumen content (WRC enrichment), to evaluate their respective ability to degrade lignocellulose and produce methane. Among the treatments, F + M enrichment elicited the strongest lignocellulose degradation and methane production ability with both rice straw and wheat straw as substrates. Quantitative real-time PCR analysis and diversity analyses of methanogens in the three enrichment treatments demonstrated that F + M had larger number of 16S rRNA gene copies of methanogens and higher relative abundance of Methanobrevibacter, the predominant methanogen found in all enrichments. Caecomyces was the main anaerobic fungal genus for co-culturing to provide substrates for methanogens in this enrichment. Importantly, the F + M enrichment was stable and could be maintained with transfers supplied every 3 days, confirming its potential utility in anaerobic digestion for lignocellulose degradation and methane production.
Assuntos
Anaerobiose/fisiologia , Bactérias/metabolismo , Fungos/fisiologia , Lignina/metabolismo , Metano/metabolismo , Animais , Euryarchaeota/metabolismo , Fermentação , Fungos/genética , RNA Ribossômico 16S , Rúmen/microbiologia , TriticumRESUMO
Programming and controlling molecular recognition in aqueous solutions is increasingly common, but creating supramolecular sensors that detect analytes in biologically relevant solutions remains a nontrivial task. We report here a parallel synthesis-driven approach to create a family of self-assembling dimeric sensors that we call DimerDyes and its use for the rapid identification of salt-tolerant sensors for illicit drugs. We developed an efficient method that involves parallel synthesis and screening in crude form without the need to purify each potential sensor. Structurally diverse "hit" DimerDyes were resynthesized and purified and were each shown to assemble into homodimers in water in the programmed way. DimerDyes provided a "turn-on" fluorescence detection of multiple illicit drugs at low micromolar concentrations in water and in saliva. The combination of multiple agents into a sensor array was successfully able to detect and discriminate between closely related drugs and metabolites in multiple important drug families.
Assuntos
Corantes Fluorescentes/química , Corantes Fluorescentes/síntese química , Drogas Ilícitas/análise , Saliva/química , Técnicas de Química Sintética , Dimerização , Humanos , Drogas Ilícitas/química , Espectrometria de FluorescênciaRESUMO
Anaerobic fungi (phylum Neocallimastigomycota), an early branching family of fungi, are commonly encountered in the digestive tract of mammalian herbivores. To date, isolates from ten described genera have been reported, and several novel taxonomic groupings are detected using culture-independent molecular methods. Anaerobic fungi are recognized as playing key roles in the decomposition of lignocellulose (up to 50% of the ingested and untreated lignocellulose), with their physical penetration and extracellular enzymatical secretion of an unbiased diverse repertoire of cell-wall-degrading enzymes. The secreted cell-wall-degrading enzymes of anaerobic fungi include both free enzymes and extracellular multi-enzyme complexes called cellulosomes, both of which have potential as fiber degraders in industries. In addition, anaerobic fungi can provide large amounts of substrates such as hydrogen, formate, and acetate for their co-cultured methanogens. Consequently, large amounts of methane can be produced. And thus, it is promising to use the co-culture of anaerobic fungi and methanogens in the biogas process to intensify the biogas yield owing to the efficient and robust degradation of recalcitrant biomass by anaerobic fungi and improved methane production from co-cultures of anaerobic fungi and methanogens.
Assuntos
Biodegradação Ambiental , Biotecnologia , Fermentação , Fungos/metabolismo , Metano/metabolismo , Neocallimastigomycota/metabolismo , Ácido Acético/metabolismo , Anaerobiose/fisiologia , Biocombustíveis , Biomassa , Celulase/genética , Celulase/metabolismo , Celulossomas/enzimologia , Técnicas de Cocultura , Fibra de Algodão , Euryarchaeota/metabolismo , Formiatos/metabolismo , Fungos/classificação , Fungos/enzimologia , Fungos/genética , Hidrogênio/metabolismo , Lignina/metabolismo , Neocallimastigomycota/classificação , Neocallimastigomycota/enzimologia , Neocallimastigomycota/genética , Polissacarídeos/metabolismo , Especificidade por SubstratoRESUMO
Oil-water separation has recently become an important subject due to the increasing incidence of oil spills. Materials with underwater superoleophobic properties have aroused considerable interest due to their cost-effectiveness, environmental friendliness and anti-fouling properties. This paper presents a robust salt-tolerant superoleophobic aerogel inspired by seaweed used without any further chemical modification for oil-seawater separation. The green aerogel is prepared by freeze-drying of sodium alginate (SA)-nanofibrillated cellulose (NFC) using Ca2+ ions as the crosslinking agent. The three-dimensional (3D) interconnected network structure of the developed aerogel ensures its high mechanical strength and good flexibility. The natural hydrophilicity of the polysaccharides contained in the aerogel ensures its excellent underwater superoleophobicity, antifouling and salt-tolerance properties. More impressively, the as-prepared aerogel can even keep its underwater superoleophobicity and high hydrophilicity after being immersed in seawater for 30 days, indicating its good stability in marine environments. Furthermore, the aerogel could separate oil-seawater mixtures with a high separation efficiency (of up to 99.65%) and good reusability (at least 40 cycles). The facile and green fabrication process combined with the excellent separation performance and good reusability makes it possible to develop engineering materials for oil-water separation in marine environments.
Assuntos
Géis/química , Óleos/química , Água/química , Alginatos/química , Cálcio/química , Celulose/química , Liofilização , Ácido Glucurônico/química , Ácidos Hexurônicos/química , Interações Hidrofóbicas e Hidrofílicas , Microscopia Eletrônica de Varredura , Nanoestruturas/química , Óleos/isolamento & purificaçãoRESUMO
Quick scarless healing remains a key issue for diabetic wounds. Here, a stretchable elastomeric hydrogel dressing composed of hydroxyethylcellulose (HEC), silk nano fiber-magnesium ion complex (Mg2+-SNF) and glycerol (Gly) was developed to optimize mechanical niche, anti-inflammatory and angiogenic behavior simultaneously. The composite hydrogel dressing exhibited skin-like elasticity (175.1 ± 23.9 %) and modulus (156.7 ± 2.5 KPa) while Mg2+-SNF complex endowed the dressing with angiogenesis, both favoring quick scarless skin regeneration. In vitro cell studies revealed that the hydrogel dressing stimulated fibroblast proliferation, endothelial cell migration and vessel-like tube formation, and also induced anti-inflammatory behavior of macrophages. In vivo results revealed accelerated healing of diabetic wounds. The improved granulation ingrowth and collagen deposition suggested high quality repair. Both thinner epidermal layer and low collagen I/III ratio of the regenerated skin confirmed scarless tissue formation. This bioactive hydrogel dressing has promising potential to address the multifaceted challenges of diabetic wound management.
Assuntos
Glicerol , Magnésio , Cicatrização , Cicatrização/efeitos dos fármacos , Animais , Glicerol/química , Glicerol/farmacologia , Magnésio/química , Magnésio/farmacologia , Camundongos , Seda/química , Hidrogéis/química , Hidrogéis/farmacologia , Materiais Biomiméticos/química , Materiais Biomiméticos/farmacologia , Diabetes Mellitus Experimental/tratamento farmacológico , Bandagens , Humanos , Ratos , Nanofibras/química , Proliferação de Células/efeitos dos fármacos , Neovascularização Fisiológica/efeitos dos fármacos , Masculino , Células Endoteliais da Veia Umbilical Humana , Celulose/química , Celulose/farmacologia , Celulose/análogos & derivadosRESUMO
Two protocols involving batch cultures were used to investigate the bioaugmentation of methane production by Pecoramyces ruminantium, and Methanobrevibacter thaueri. Protocol I examined the effect of altering the proportion of the microbial constituents in inoculum on alfalfa stalk fermentations and showed a 25 % improvement in dry matter loss in cultures where the inoculum contained just 30 % of co-culture and 70 % of fungal monoculture. Protocol II involved consecutive cultures and alternating inoculations. This protocol resulted in 17-22 mL/g DM methane production with co-cultures a 30 % increase in methane relative to the fungal monoculture. Both protocols indicate that the co-culture rapidly dominated and was more resilient than the monoculture. Synergistic interaction between fungus and methanogen, promoted more efficient lignocellulose degradation and higher methane yield. This study highlighted the potential of microbial co-cultures for enhancing methane production from lignocellulosic biomass, offering a promising bioaugmentation strategy for improving biogas yields and waste valorization.
Assuntos
Técnicas de Cocultura , Lignina , Medicago sativa , Metano , Methanobrevibacter , Metano/metabolismo , Lignina/metabolismo , Medicago sativa/metabolismo , Methanobrevibacter/metabolismo , Fermentação , Biodegradação AmbientalRESUMO
A plug-flow fixed-bed reactor (PFBR) with zeolite/tourmaline-modified polyurethane (ZTP) carriers (PFBRZTP) was constructed to realize mainstream deammonification for real domestic sewage treatment. The PFBRZTP and PFBR were operated for 111 days treating aerobically pretreated sewage in parallel. A higher nitrogen removal rate of 0.12 kg N·(m3·d)-1 was achieved in PFBRZTP despite lowering the temperature (16.8-19.7 °C) and fluctuating water quality. Meanwhile, it was indicated that anaerobic ammonium oxidation dominated (64.0 ± 13.2%) in PFBRZTP, by nitrogen removal pathway analysis and high anaerobic ammonium-oxidizing bacteria (AnAOB) activity (2.89 mg N·(g VSS·h)-1). And, the lower protein/polysaccharides (PS) ratio further indicated a better biofilm structure in PFBRZTP owing to a higher abundance of microorganisms relevant to PS and cryoprotective EPS secretion. Furthermore, partial denitrification was an important nitrite supply process in PFBRZTP based on low AOB activity/AnAOB activity ratio, higher Thauera abundance and a remarkably positive correlation between Thauera abundance and AnAOB activity.
Assuntos
Compostos de Amônio , Zeolitas , Esgotos/microbiologia , Poliuretanos , Temperatura , Reatores Biológicos/microbiologia , Nitrogênio , Oxirredução , DesnitrificaçãoRESUMO
Microplastics (MPs) are emerging pollutants that interact extensively with dissolved organic matter (DOM) and this influences the environmental behavior of MPs in aqueous ecosystems. However, the effect of DOM on the photodegradation of MPs in aqueous systems is still unclear. The photodegradation characteristics of polystyrene microplastics (PS-MPs) in an aqueous system in the presence of humic acid (HA, a signature compound of DOM) under ultraviolet light conditions were investigated in this study through Fourier transform infrared spectroscopy coupled with two-dimensional correlation analysis, electron paramagnetic resonance, and gas chromatography-mass spectrometry (GC/MS). HA was found to promote higher levels of reactive oxygen species (0.631 mM of âªOH), which accelerated the photodegradation of PS-MPs, with a higher degree of weight loss (4.3%), higher level of oxygen-containing functional groups, and lower average particle size (89.5 µm). Likewise, GC/MS analysis showed that HA contributed to a higher content of oxygen-containing compounds (42.62%) in the photodegradation of PS-MPs. Moreover, the intermediates and final degradation products of PS-MPs with HA were significantly different in the absence of HA during 40 days of irradiation. These results provide an insight into the co-existing compounds on the degradation and migration processes of MP and also support further research toward the remediation of MPs pollution in aqueous ecosystems.
Assuntos
Microplásticos , Poluentes Químicos da Água , Poliestirenos/química , Plásticos , Raios Ultravioleta , Substâncias Húmicas/análise , Ecossistema , Matéria Orgânica Dissolvida , Poluentes Químicos da Água/análise , Oxigênio/análiseRESUMO
Oral environment deterioration results from a lack of self-cleaning ability in patients with cognitive dysfunction but is also a risk factor for cognitive dysfunction. Adverse oral conditions can be alleviated and improved through a self-management and medical examination. In this review, the epidemiological evidence of previous studies is integrated to highlight the relationship between periodontitis, tooth loss, oral flora, oral dysfunction and cognitive dysfunction, emphasizing the importance of oral health for cognition. The results show that poor oral condition is associated with cognitive impairment. Although many previous studies have been conducted, there is a lack of higher-level research evidence, different judgment criteria, and conflicting research results. There is a bidirectional relationship between oral health and cognitive dysfunction. A comprehensive analysis of the relationship between oral health and cognitive dysfunction that explores the relationship and takes measures to prevent cognitive dysfunction and control the progression of such diseases is warranted in the future.
Assuntos
Disfunção Cognitiva , Perda de Dente , Humanos , Disfunção Cognitiva/epidemiologia , Disfunção Cognitiva/etiologia , Cognição , Perda de Dente/complicações , Saúde Bucal , Fatores de RiscoRESUMO
Zeolite-modified polyurethane (ZP) carriers and zeolite/tourmaline-modified polyurethane (ZTP) carriers were proposed to enhance mainstream deammonification. The system with ZTP carriers was rapidly established in 28 days with a nitrogen removal rate (NRR) of 0.150 kg N·(m3·d)-1. Moreover, the facilitative effect of tourmaline was suggested by the highest humic acid peak intensity and more balanced potential activity. Besides, SEM-EDS analysis revealed carrier characteristic improvement was achieved in both novel carriers while maintaining an excellent spatial structure. Moreover, the microbial analysis suggested that both modified carriers support the substrate supply to anaerobic ammonium oxidizing bacteria (AnAOB) by enhancing dissimilatory nitrate reduction to ammonium and partial denitrification under nitrate accumulation conditions. Nevertheless, the ZTP system had a greater advantage over maintaining the original AnAOB (Candidatus Jettenia) and ammonium oxidizing bacteria (Nitrosomonas) abundance. Overall, this study provides ZTP carriers with great potential for facilitating the establishment of mainstream deammonification at full-scale WWTPs.
Assuntos
Compostos de Amônio , Microbiota , Zeolitas , Nitrogênio , Desnitrificação , Reatores Biológicos/microbiologia , Nitratos , Poliuretanos , Temperatura , Compostos de Amônio/química , Oxirredução , Esgotos/microbiologia , Águas ResiduáriasRESUMO
Self-healing biomass-based conductive hydrogels are applied as flexible strain sensors for wearable devices and human movement monitoring. Cellulose is the most abundant biomass-based materials and exhibits excellent toughness, dispersion and degradability. In this paper, nanocellulose crystals (NCCs) prepared from sisal, used as reinforcing fillers were coated with tannic acid (TA) to prepare inexpensive bio-nanocomposite hydrogels that also included polyvinyl alcohol, okra polysaccharide (OP), and borax. These hydrogels exhibit excellent self-healing and mechanical properties with the maximum elongation, toughness, and self-healing efficiency (9 min) of 1426.2 %, 264.4 kJ/m3, and 62.1 %, respectively. A fabricated hydrogel strain sensor was successfully used to detect and monitor various human movements such as wrist bending, elbow bending, and slight changes in facial expression. In addition, this sensor possessed excellent durability and good working stability after repeated circulation. The nanocomposite hydrogel synthesized in this work utilized natural polysaccharide to manufacture flexible functional materials with good application prospects in the field of flexible sensors.
Assuntos
Hidrogéis , Dispositivos Eletrônicos Vestíveis , Humanos , Hidrogéis/química , Celulose , Condutividade Elétrica , Movimento (Física) , ÍonsRESUMO
Information on the distribution and interaction of microplastics (MPs) and humic acids (HAs) in river sediment has not been fully explored. This study assessed the distribution and interaction of MPs with HAs at different depths in river sediments. The results delineated that the average abundance of MPs in the 0-10 cm layer (190 ± 20 items/kg) was significantly lower than that in the 11-20 cm and 21-30 cm layers (211 ± 10 items/kg and 238 ± 18 items/kg, respectively). Likewise, the large MP particles mainly existed in the 0-10 cm layer (31.53%-37.87%), while small MP particles were found in the 21-30 cm layers (73.23%-100%). Moreover, HAs in MPs showed a transformation from low molecular weight to high molecular weight with an increase in depth from 0-10 cm to 21-30 cm, which may contribute to the distribution of MPs in the river sediments. These results provide new insight into the migration of MP pollution in river sediments, but further research needs to assess the interaction of MP with HA for mitigating MP pollution in river sediment.
Assuntos
Microplásticos , Poluentes Químicos da Água , Monitoramento Ambiental/métodos , Sedimentos Geológicos , Substâncias Húmicas , Plásticos , Rios , Poluentes Químicos da Água/análiseRESUMO
Nanoplastics can be ingested by organisms and penetrate biological barriers to affect multiple physiological functions. However, few studies have focused on the effects of nanoplastics on the mammalian immune system. We evaluated the effects and underlying mechanism of nanoplastics of varying particle sizes and surface charges on murine splenic lymphocytes. We found that nanoplastics penetrated into splenic lymphocytes and that nanoplastics of a diameter of 50 nm were absorbed more efficiently by the cells. The nanoplastics decreased cell viability, induce cell apoptosis, up-regulated apoptosis-related protein expression, elicited the production of reactive oxygen species, altered mitochondrial membrane potential, and impaired mitochondrial function. Positively charged nanoplastics exerted the strongest toxicity. Negatively charged and uncharged nanoplastics caused oxidative stress and mitochondrial structural damage in lymphocytes, while positively charged nanoplastics induced endogenous apoptosis directly. Moreover, nanoplastics inhibited the expression of activated T cell markers on the T cell surface, while inhibiting the differentiation of CD8+ T cells and the expression of helper T cell cytokines. In terms of the mechanism, a series of key signaling molecules in the pathways of T cell activation and function were markedly down-regulated after exposure to nanoplastics.
Assuntos
Microplásticos , Poliestirenos , Animais , Linfócitos T CD8-Positivos , Camundongos , Tamanho da Partícula , Espécies Reativas de OxigênioRESUMO
To enhance the advantage of a long-term stability and low-toxicity active packaging system, two biodegradable covalent immobilized antibacterial packaging films were developed and applied to fresh beef preservation in this study. A polylactic acid (PLA) film was prepared by the extrusion-casting method. The surface of the PLA film was modified with plasma treatment to generate carboxylic acid groups, and then antibacterial agent nisin or ε-poly lysine (ε-PL) was covalently attached to the modified film surface. Physical, chemical, and antimicrobial properties of films were then characterized. Scanning electron microscopy and water contact angle images confirmed that nisin or ε-PL was successfully grafted onto the film surface. The values of protein loading on the nisin-g-PLA film and ε-PL-g-PLA film were 5.34 ± 0.26 and 3.04 ± 0.25 µg of protein/cm2 on the surface. Microbial analysis indicated that the grafted films effectively inhibit the growth of bacteria. Finally, the effects of the nisin-g-PLA film or ε-PL-g-PLA film on physicochemical changes and microbiological counts of fresh beef during cold storage at 4 °C were investigated. The total viable count of the control sample exceeded 7 logarithms of the number of colony forming units per gram (log CFU/g) after 11 days of cold storage (7.01 ± 0.14 log CFU/g) versus 15 days for the ε-PL-g-PLA film (7.37 ± 0.06 log CFU/g) and the nisin-g-PLA film (6.83 ± 0.10 log CFU/g). The results showed that covalent immobilized antibacterial packaging films had positive impacts on the shelf life and quality of fresh beef. Therefore, a covalent immobilized antibacterial packaging system could be a novel preservative method for foods.
Assuntos
Antibacterianos/química , Conservação de Alimentos/métodos , Carne/microbiologia , Nisina/química , Poliésteres/química , Polilisina/química , Animais , Antibacterianos/farmacologia , Bactérias/efeitos dos fármacos , Bactérias/crescimento & desenvolvimento , Plásticos Biodegradáveis/química , Plásticos Biodegradáveis/farmacologia , Bovinos , Embalagem de Alimentos/instrumentação , Conservação de Alimentos/instrumentação , Carne/análise , Nisina/farmacologia , Polilisina/farmacologiaRESUMO
The aim of this study was to investigate the effects of steam explosion on lignocellulose digestibility of, and methane production from corn stover by a co-culture of anaerobic fungus and methanogen. The cumulative methane production at 72â¯h of incubation from the steam-exploded corn stover was 32.2⯱â¯1.74â¯mL, which not significantly different (Pâ¯>â¯0.05) from that of the untreated corn stover (37.1⯱â¯1.09â¯mL). However, steam explosion decreased the hemicellulose contents of corn stover by 28.0⯱â¯0.39% and increased the neutral detergent solute by 23.5⯱â¯0.25%. While this treatment did not affect the dry matter digestibility (64.1⯱â¯0.26%, and 64.1⯱â¯0.28%, respectively). In conclusion, the co-culture of anaerobic fungus and methanogen can degrade the crude fibrous portion of corn stover without any pretreatments. It possesses promising biotechnological prospects for conversion of crop residue based straw resources to obtain biofuel in the form of methane.