Studies on competitive adsorption characteristics of bisphenol A and 17α-ethinylestradiol on thermoplastic polyurethane by site energy distribution theory.

Compound pollution of microplastics and estrogens is a growing ecotoxicological problem in aquatic environments. The adsorption isothermal properties of bisphenol A (BPA) and 17α-ethinyl estradiol (EE2) on polyamide (TPU) in monosolute and bisolute systems were studied. Under the same adsorption concentration (1-4 mg L-1), EE2 had a greater adsorption capacity than BPA in the monsolute system. Compared to the energy distribution features of the adsorption sites of EE2 and BPA, the BPA adsorption sites were located in the higher energy area and were more evenly distributed than those of EE2, while the quantity of BPA adsorption sites was less than that of EE2. In the bisolute system, the average site energy, site energy inhomogeneity, and adsorption site numbers of BPA increased by 1.674, -17.166, and 16.793%, respectively. In comparison, the average site energy, site energy inhomogeneity, and adsorption sites numbers of EE2 increased by 2.267, 4.416, and 8.585%, respectively. The results showed that BPA and EE2 had a cooperative effect on the competitive adsorption of TPU. XPS analysis showed that BPA and EE2 had electron transfer on TPU, although the chemisorption effects and hydrogen bonds between BPA and TPU were more significant. Comparing the changes in the relative functional group content of TPU in monosolute and bisolute systems, BPA and EE2 were synergistically absorbed on TPU. This study can provide a theoretical reference for the study of competitive adsorption between coexisting organic pollutants.

Fabricating High-Thermal-Conductivity, High-Strength, and High-Toughness Polylactic Acid-Based Blend Composites via Constructing Multioriented Microstructures.

The massive accumulation of plastic waste has caused a serious negative impact on the human living environment. Replacing traditional petroleum-based polymers with biobased and biodegradable poly(l-lactic acid) (PLLA) is considered an effective way to solve this problem. However, it is still a great challenge to manufacture PLLA-based composites with high thermal conductivity and excellent mechanical properties via tailoring the microstructures of the blend composites. In the present work, a melt extrusion-stretching method is utilized to fabricate biodegradable PLLA/poly(butylene adipate-co-butylene terephthalate)/carbon nanofiber (PLLA/PBAT/CNF) blend composites. It is found that the incorporation of the extensional flow field induces the formation of multioriented microstructures in the composites, including the oriented PLLA molecular chains, elongated PBAT dispersed phase, and oriented CNFs, which synergistically improve the thermal conductivity and mechanical properties of the blend composites. At a CNF content of 10 wt %, the in-plane thermal conductivity, tensile strength, and elongation at break of the blend composite reach 1.53 Wm-1 K-1, 66.8 MPa, and 56.5%, respectively, which increased by 31.9, 73.5, and 874.1% compared with those of the conventionally hot-compressed sample (1.16 Wm-1 K-1, 38.5 MPa, and 5.8%, respectively). The main mechanism for the improved thermal conductivity is that the multioriented structure promotes the formation of a CNF thermal conductive network in the composites. The strengthening mechanism is attributed to the orientation of both PLLA molecular chains and CNFs in the stretching direction, restricting the movement of PLLA molecular segments around CNFs, and the toughening mechanism is due to the transformation of PLLA molecular chains from low-energy gt conformers to high-energy gg conformers induced by extensional flow field. More interestingly, after the extrusion-stretched samples are annealed, the oriented PLLA molecular chains form oriented crystal structures such as extended-chain lamellae, common "Shish-kebabs," and hybrid Shish-kebabs, which further enhance the thermal conductivity and heat resistance of the samples. This work reveals the effects of the orientation of the matrix molecular chains and crystallites on the thermal conductivity and mechanical properties of composites and provides a new way to prepare high-performance PLLA-based composites with high thermal conductivity, excellent mechanical properties, and high heat resistance.

Bioanalytical approaches for the detection, characterization, and risk assessment of micro/nanoplastics in agriculture and food systems.

This review discusses the most recent literature (mostly since 2019) on the presence and impact of microplastics (MPs, particle size of 1 µm to 5 mm) and nanoplastics (NPs, particle size of 1 to 1000 nm) throughout the agricultural and food supply chain, focusing on the methods and technologies for the detection and characterization of these materials at key entry points. Methods for the detection of M/NPs include electron and atomic force microscopy, vibrational spectroscopy (FTIR and Raman), hyperspectral (bright field and dark field) and fluorescence imaging, and pyrolysis-gas chromatography coupled to mass spectrometry. Microfluidic biosensors and risk assessment assays of MP/NP for in vitro, in vivo, and in silico models have also been used. Advantages and limitations of each method or approach in specific application scenarios are discussed to highlight the scientific and technological obstacles to be overcome in future research. Although progress in recent years has increased our understanding of the mechanisms and the extent to which MP/NP affects health and the environment, many challenges remain largely due to the lack of standardized and reliable detection and characterization methods. Most of the methods available today are low-throughput, which limits their practical application to food and agricultural samples. Development of rapid and high-throughput field-deployable methods for onsite screening of MP/NPs is therefore a high priority. Based on the current literature, we conclude that detecting the presence and understanding the impact of MP/NP throughout the agricultural and food supply chain require the development of novel deployable analytical methods and sensors, the combination of high-precision lab analysis with rapid onsite screening, and a data hub(s) that hosts and curates data for future analysis.

Colorimetric detection of 2-tert-butyl-1,4-benzoquinone in edible oils based on a chromogenic reaction with commercial chemicals.

2-tert-butyl-1,4-benzoquinone (TBBQ) is the major oxidative product of tert-butylhydroquinone which is a widely used antioxidant in edible oils. The biotoxicity of TBBQ is a risk to human health, that the rapid and accurate monitoring of TBBQ is needed. Herein, a specific chromogenic reaction between TBBQ and polyethyleneimine (PEI) could generate adducts with maximum absorption at 478 nm. Amine groups of PEI are prone to link with TBBQ through Michael addition to form colored adducts. A colorimetric method for detecting TBBQ in edible oils was developed based on the aforesaid chromogenic reaction. The linear range for TBBQ was from 3.0 to 100.0 µg g-1, having a limit of detection of 1.8 µg g-1. Recoveries results ranged from 88.4 % to 93.1 %, which had a good agreement with that of high-performance liquid chromatography. Our study provides a rapid and simple strategy for the sensitive detection of TBBQ using commercial chemicals.

Inhibition of starch digestion: The role of hydrophobic domain of both α-amylase and substrates.

The physicochemical mechanism of starch digestion is very complicated since it may be affected by the non-valence interactions of the amylase inhibitor with the substrate or the enzyme. The role of hydrophobic interaction in the process of starch digestion is not clear. In this study, pluronics (PLs) with different hydrophobicity were used as model amphiphilic compounds to study their inhibition on starch digestion using multi-spectroscopic methods. The results showed that the hydrophobic nature of PLs changed starch structure, but it had a greater effect on the structure of α-amylase by exposing more tryptophan residues and increasing α-helix and ß-sheet contents. Further investigation by using different chain-length fatty acids confirmed the results. The finding in this study is informative to design and fabricate α-amylase inhibitors for controlling starch digestion at the molecular level.

Achieving Ultrasmall Prussian Blue Nanoparticles as High-Performance Biomedical Agents with Multifunctions.

Prussian blue nanoparticles (PBNPs), which belong to the iron-based metal-organic frameworks, are important biomedical agents. Reducing the size of PBNPs can bring improved functional properties, but unfortunately, has been a long-standing challenge. Herein, sub-5 nm ultrasmall PBNPs (USPBNPs) were successfully synthesized by using ethanol/water mixture as the solvent and polyvinyl pyrrolidone (PVP) as the surface capping agent. Adjusting the ethanol/water ratio is not only able to control the nucleation time and size of PBNPs but also tune the conformation of PVP molecules so as to prevent interparticle attachment and enlargement. At an ethanol/water ratio of 3:1, highly stable USPBNPs with a size of ∼3.4 nm were synthesized. Due to their large specific surface area, they demonstrated high peroxidase-like and catalase-like activities, which outperform PBNPs synthesized by a conventional method. In addition, they also showed a high longitudinal relaxation rate (r1) of 1.3 mM-1 S-1, suggesting their potential to be used as T1 MRI agent.

Simulating and predicting the flux change of reverse osmosis membranes over time during wastewater reclamation caused by organic fouling.

During the operation of the RO system, it's significant to predict the flux change over time. Previous research conducted detailed exploration on the dynamics of RO membrane fouling, and provided a solid database for modelling. In this study, a modified intermediate blocking model with two parameters was proposed to describe the flux change of RO membranes under a huge variety of conditions. Raw data reported by over 20 research groups from 11 different countries was used to validate the feasibility of this model. It proved applicable to describe the flux change of RO membranes fouled by pure organic matter or mixture and tertiary treated wastewater. In order to reveal the relationship between model parameters and foulant concentrations, RO membrane fouling behaviors of typical foulants (sodium alginate (SA), bovine serum albumin (BSA) and mixture) were further investigated. We found that the change of model parameters with SA concentrations was in accordance with Langmuir adsorption isotherm model. Therefore, the model parameters could be calculated by SA concentrations under certain optional conditions, and then the flux change could be predicted by this model. In this way, a novel time-course model was established, which could predict the flux change of RO membranes over time only with SA concentrations. Besides, the synergic effect between SA and BSA on RO membrane fouling was directly quantified.

A portable visual detection method based on a target-responsive DNA hydrogel and color change of gold nanorods.

A new method based on a functional DNA crosslinked hydrogel as a target-responsive unit and gold nanorods (AuNRs) as a multicolor signal readout circuit was developed for the sensitive and visual detection of different targets. The color variation of the AuNR solution was correlated with the concentration of the target. This system can be extended to detect various targets by designing the corresponding target-responsive DNA hydrogels.

[Inhibitory effect of diacerein on osteoclastic bone destruction and its possible mechanism of action].

AIM: To study the inhibitory action of diacerein on the formation of osteoclasts (OCLs) and their activity in bone resorption as well as the relationship between this action and the expression of osteoprotegerin (OPG) and receptor activator of NF-kappaB ligand (RANKL) in MC3T3-E1 cells. METHODS: A coculture system constituted with MC3T3-E1 cells and bone marrow cells for osteoclasts formation was established in vitro. TRAP-positive and multinucleated cells with three or more nuclei in each cell were counted as osteoclasts and the number of pits formed on the dentine slices was determined to judge the activity of osteoclasts. Western blotting, RT-PCR and flow cytometer were used to detect the expression of OPG and RANKL in MC3T3-E1 cells. RESULTS: Diacerein significantly inhibited the formation and function of the cultured osteoclasts stimulated by IL-1beta. sRANKL could reverse the effect of diacerein. Diacerein inhibited protein and mRNA expression of RANKL but enhanced those of OPG in MC3T3-E1 cells. CONCLUSION: Diacerein may inhibit osteoclastic bone destruction through the inhibition of RANKL expression and the increase of OPG expression in MC3T3-E1 cells.

A fluorescent thermometer operating in aggregation-induced emission mechanism: probing thermal transitions of PNIPAM in water.

Poly(N-isopropylacrylamide) was labelled using a fluorogen with an aggregation-induced emission feature by direct polymerization; the label served as a fluorogenic probe that reveals fine details in the thermal transitions in the aqueous solution of the polymer; the working mode was readily tuned between non-monotonic and monotonic by changing the labelling degree of the polymer.