Potential health risks of microplastic fibres release from disposable surgical masks: Impact of repeated wearing and handling.

Disposable surgical masks undeniably provide important personal protection in daily life, but the potential health risks by the release of microplastic fibres from masks should command greater attention. In this study, we conducted a microplastic fibre release simulation experiment by carrying masks in a pocket and reusing them, to reveal the number and morphological changes of microfibres released. Fourier transform infrared spectrometry, scanning electron microscopy, and optical microscopy were employed to analyse the physical and chemical characteristics of the mask fibres. The results indicated that the reuse of disposable masks led to a significant release of microplastic fibres, potentially leading to their migration into the respiratory system. Furthermore, the release of microplastic fibres increased with prolonged external friction, particularly when masks were stored in pockets. The large-scale release of microplastic fibres due to mask reuse raises concerns about potential health risks to the human respiratory system. The reuse of disposable masks should be also strictly avoided in daily life in the future. Furthermore, the current study also established a robust foundation for future research endeavours on health risks associated with microplastic fibres entering the respiratory system through improper mask usage.

Effects of polymerization types on plastics ingestion and biodegradation by Zophobas atratus larvae, and successions of both gut bacterial and fungal microbiomes.

Recent studies demonstrated that plastic degradation in Zophobas atratus superworms is related to the gut microbiota. To determine whether the biodegradation and gut-microbiota were influenced by ingested plastic polymerization types, foams of polypropylene (PP), polyurethane (PU) and ethylene vinyl acetate (EVA) were selected as representatives of polyolefins, polyester and copolymers, and the sole feedstock for superworms for 45 d. Both growth and survival rates of superworms were influenced by the type of plastic diet. Although the total consumptions of EVA- and PP-fed groups were similar at 29.03 ± 0.93 and 28.89 ± 1.14 mg/g-larva, which were both significantly higher than that of PU-fed groups (21.63 ± 2.18 mg/g-larva), the final survival rates of the EVA-fed group of 36.67 ± 10.41% exhibited significantly lower than that of the PP- and PU-fed groups of 76.67 ± 2.89% and 75.00 ± 7.07%, respectively, and even the starvation group of 51.67 ± 10.93%. The Illumina MiSeq results revealed similarities in the dominant gut bacterial communities between PU- and EVA-fed groups, with an increase in relative abundance of Lactococcus, but significant differences from the PP-fed groups, which had two predominant genera of unclassified Enterobacteriaceae and Enterococcus. Compared to bran-fed groups, changes in gut fungal communities were similar across all plastics-fed groups, with an increase in the dominant abundance of Rhodotorula. The abundance of Rhodotorula increased in the order of polyolefin, polyester, and copolymer. In summary, plastic ingestion, larval growth, and changes in gut bacterial and fungal community of superworms were all influenced by foam diets of different polymerization types, and especially influences on the gut microbiomes were different from each other.

Differences in ingestion and biodegradation of the melamine formaldehyde plastic by yellow mealworms Tenebrio molitor and superworms Zophobas atratus, and the prediction of functional gut microbes.

Plastics biodegradation by insect larvae is considered as a new strategy for plastic wastes treatment. To uncover the biodegradation of a more complex chemical polymer of melamine formaldehyde (MF) by insect larvae, two worm species of yellow mealworm Tenebrio molitor and superworm Zophobas atratus were fed on MF foam as sole diet for 45 days with sole bran diet as control. Although the MF foam consumption by yellow mealworms of 0.38 mg/d/g-larvae was almost 40% higher than that by superworms of 0.28 mg/d/g-larvae, a similar decrease of survival rates in both species were obtained at about 58%, indicating the adverse effects on their growth. Depolymerization and biodegradation of MF foam occurred in both larval guts, but was more extensive in yellow mealworms. MF foam sole diet influenced gut bacterial and fungal microbiomes of both larvae species, which were assessed by Illumina MiSeq on day 45. Compared to the bran-fed group, both gut bacterial and fungal communities significantly changed in MF-fed groups, but differed in the two larvae species. The results demonstrated a strong association between the distinctive gut microbiome and MF foam degradation, such as unclassified Enterobacteriaceae, Hyphopichia and Issatchenkia. However, sole MF foam diet negatively influenced worms, like lower survival rates and gut abnormalities. In summary, MF foam could be degraded by both yellow mealworms and superworms, albeit with adverse effects. Gut microbes were strongly associated to MF foam degradation, especially the gut fungi.

Mass GGBFS Concrete Mixed with Recycled Aggregates as Alkali-Active Substances: Workability, Temperature History and Strength.

This study provides the results of an experiment on the possibility of using high-volume ground granulated blast furnace slag (HVGGBFS)-based concrete as mass concrete. In addition to the control concrete, the total weight of the binder was 75% ground granulated blast furnace slag (GGBFS) and 25% ordinary Portland cement (OPC). For the aggregates, both natural and recycled aggregates were used. Three specimens with dimensions of 800 mm × 800 mm × 800 mm were prepared to simulate mass concrete. The workability, temperature aging and strength of the mass concrete were tested. The test results showed that utilizing HVGGBFS concrete as mass concrete can significantly reduce the heat of hydration due to the low heat of hydration of GGBFS, while the heat of hydration of GGBFS and recycled aggregate combination is 11.2% higher than normal concrete, with a slump that is 31.3% lower than that of plain concrete. The results also showed that the use of recycled aggregates in HVGGBFS concrete can significantly reduce workability. However, the compressive strength is higher than when natural aggregates are used due to the alkali activation effect caused by the recycled aggregates. The compressive strength at 7 and 28 days increased by 33.7% and 16.3%, respectively.

Ultrafine molybdenum oxycarbide nanodots encapsulated in N,P co-doped carbon nanofibers as an advanced anode material for lithium-ion batteries.

Molybdenum oxycarbide (MoOC) is a single-phase compound, which can serve as a potential anode for Li-ion batteries (LIBs) that integrates the merits of the high specific capacity of MoO2and high conductivity of Mo2C. Herein, a novel architecture with N,P co-doped C nanofibers and MoOC nanodots is constructed from a one-step phosphorization of MoOx/aniline organic-inorganic hybrid. Ultrafine MoOC nanodots are well confined by N,P co-doped C nanofibers, which ensures fast Li+/electron transfer and good stability of the structure under repeated charge/discharge processes. When this unique hybrid is employed as an anode material for LIBs, promising Li+storage properties are gained in terms of high specific capacity, superb rate and long-term cycling performance. The remarkable capacitive contribution facilitates the fast Li+uptake/release. This work may shed light on the development of well-defined Mo-based anodes for advanced LIBs.

First-principles study on equation of states and electronic structures of shock compressed Ar up to warm dense regime.

The equation of states (EOS) and electronic structures of argon with temperatures from 0.02 eV to 3 eV and densities from 0.5 g/cm(3) to 5.5 g/cm(3) are calculated using the pair potential and many-body potential molecular dynamics and the density functional theory (DFT) molecular dynamics with van der Waals (vdW) corrections. First-principles molecular dynamics is implemented above 2.0 g/cm(3). For the cases of low densities below 3 g/cm(3), we performed pair potential molecular dynamics in order to obtain the ionic configurations, which are used in density functional theory to calculate the EOS and electronic structures. We checked the validity of different methods at different densities and temperatures, showing their behaviors by comparing EOS. DFT without vdW correction works well above 1 eV and 3.5 g/cm(3). Below 1 eV and 2.0 g/cm(3), it overestimates the pressure apparently and results in incorrect behaviors of the internal energy. With vdW corrections, the semi-empirical force-field correction (DFT-D2) method gives consistent results in the whole density and temperature region, and the vdW density functional (vdW-DF2) method gives good results below 2.5 g/cm(3), but it overestimates the pressure at higher densities. The interactions among the atoms are overestimated by the pair potential above 1 eV, and a temperature dependent scaled pair potential can be used to correct the ionic configurations of the pair potential up to 3 eV. The comparisons between our calculations and the experimental multi-shock compression results show that the Hugoniot line of DFT-D2 and DFT tends to give larger pressure than the results of the self-consistent fluid variational theory, and the difference increases with the density. The electronic energy gap exists for all our cases up to 5.5 g/cm(3) and 1 eV. The effect of vdW interactions on the electronic structures are also discussed.

Analysis of bacterial diversity in two oil blocks from two low-permeability reservoirs with high salinities.

The community diversities of two oil reservoirs with low permeability of 1.81 × 10(-3) and 2.29 × 10(-3) µm(2) in Changqing, China, were investigated using a high throughput sequencing technique to analyze the influence of biostimulation with a nutrient activator on the bacterial communities. These two blocks differed significantly in salinity (average 17,500 vs 40,900 mg/L). A core simulation test was used to evaluate the effectiveness of indigenous microbial-enhanced oil recovery (MEOR). The results indicated that in the two high salinity oil reservoirs, one reservoir having relatively lower salinity level and a narrow salinity range had higher bacterial and phylogenetic diversity. The addition of the nutrient activator increased the diversity of the bacterial community structure and the diversity differences between the two blocks. The results of the core simulation test showed that the bacterial community in the reservoir with a salinity level of 17,500 mg/L did not show significant higher MEOR efficiency compared with the reservoir with 40,900 mg/L i.e. MEOR efficiency of 8.12% vs 6.56% (test p = 0.291 > 0.05). Therefore, salinity levels affected the bacterial diversities in the two low permeability oil blocks remarkably. But the influence of salinity for the MEOR recovery was slightly.

Quantum molecular dynamics study on the structures and dc conductivity of warm dense silane.

The ionic and electronic structures of warm dense silane at the densities of 1.795, 2.260, 3.382, and 3.844 g/cm(3) have been studied with temperatures from 1000 K to 3 eV using quantum molecular dynamics simulations. At all densities, the structures are melted above 1000 K. The matter states are characterized as polymeric from 1000 to 4000 K and become dense plasma states with further increasing temperature to 1 eV. At two lower densities of 1.795 and 2.260 g/cm(3), silane first dissociates and then becomes the polymeric state via a chain state from the initial crystalline structure. At higher densities, however, no dissociation stage was found. These findings can help us understand how the warm dense matter forms. A rise is found for the direct current electric conductivity at T ∼ 1000 K, indicating the nonmetal-to-metal transition. The conductivity decreases slightly with the increase of temperature, which is due to the more disordered structures at higher temperatures.

Nuclear quantum dynamics in dense hydrogen.

Nuclear dynamics in dense hydrogen, which is determined by the key physics of large-angle scattering or many-body collisions between particles, is crucial for the dynamics of planet's evolution and hydrodynamical processes in inertial confinement confusion. Here, using improved ab initio path-integral molecular dynamics simulations, we investigated the nuclear quantum dynamics regarding transport behaviors of dense hydrogen up to the temperatures of 1 eV. With the inclusion of nuclear quantum effects (NQEs), the ionic diffusions are largely higher than the classical treatment by the magnitude from 20% to 146% as the temperature is decreased from 1 eV to 0.3 eV at 10 g/cm(3), meanwhile, electrical and thermal conductivities are significantly lowered. In particular, the ionic diffusion is found much larger than that without NQEs even when both the ionic distributions are the same at 1 eV. The significant quantum delocalization of ions introduces remarkably different scattering cross section between protons compared with classical particle treatments, which explains the large difference of transport properties induced by NQEs. The Stokes-Einstein relation, Wiedemann-Franz law, and isotope effects are re-examined, showing different behaviors in nuclear quantum dynamics.

Effect of polarization purity of cylindrical vector beam on tightly focused spot.

The tightly focused spots of cylindrical vectors (CVs) are dependent on polarization composition. We experimentally demonstrate the effect of polarization purity (PP) of the CV beam on the tightly focused spot quantitatively, which should be strictly controlled for the effective applications of the CV beam. The focal spots measured by a knife-edge scanning method showed that the azimuthally polarized (AP) component increases the transverse field and the size of the focal spots, while the radially polarized component results in a nonzero intensity distribution at the center of the focus even in a high PP AP beam.

Quantum simulation of thermally-driven phase transition and oxygen K-edge x-ray absorption of high-pressure ice.

The structure and phase transition of high-pressure ice are of long-standing interest and challenge, and there is still a huge gap between theoretical and experimental understanding. The quantum nature of protons such as delocalization, quantum tunneling and zero-point motion is crucial to the comprehension of the properties of high-pressure ice. Here we investigated the temperature-induced phase transition and oxygen K-edge x-ray absorption spectra of ice VII, VIII and X using ab initio path-integral molecular dynamics simulations. The tremendous difference between experiments and the previous theoretical predictions is closed for the phase diagram of ice below 300 K at pressures up to 110 GPa. Proton tunneling assists the proton-ordered ice VIII to transform into proton-disordered ice VII where only thermal activated proton-transfer cannot occur. The oxygen K edge with its shift is sensitive to the order-disorder transition, and therefore can be applied to diagnose the dynamics of ice structures.

[Study on the mechanism of energy transfer between acridine orange and rhodamine 6G in micelles of dodecyl benzene sodium sulfonate].

Applying Förster theory, the energy transfer between acridine orange (AO) and rhodamine 6G (R6G) was investigtaed. It was found that in the solution of dodecyl benzene sulfonic acid sodium (DBS), effective energy transfer can occur between AC and rhodamine 6G even when the concentration of the dyes is very low. The mechanism of energy transfer between AO and rhodamine 6G was studied. When the energy transfer occurs, the fluorescence of AO is quenched, the type of quenching is static. Based on the mechanism of Förster energy transference, the thermodynamic parameters, enthalpy change (deltaH) and entropy change (deltaS), were calculated according to Van't Hoff equation, which indicates the acting force between AO and R6G. The transfer efficiency of energy and the distance between AO and R6G were found. It is indicated that the course of action is single static quenching.