Organ distribution of Nano-WC particles after repeated intratracheal instillation into the lungs of SD rats and subsequent organ injury.

Nano-tungsten carbide (nano-WC) is widely used in composite materials due to its special physical and chemical properties. Owing to their small size, nano-WC nanoparticles easily enter organisms through the respiratory tract, which may cause health hazards. However, only a few studies have reported the toxicity of nano-WC. In this study, a 10 mg/kg nano-WC suspension and 0.9% normal saline were quantitatively perfused into the lungs of two groups of healthy male SD rats by tracheal instillation, and the in vivo pulmonary toxic effects were systematically evaluated. Additionally, as multiple organs and tissues are involved, systemic effects were observed throughout the body and mainly manifested as inflammatory damage. The concentrations of tungsten ions in various organs and alveolar lavage fluid were measured by ICP-MS, and the results showed that the lung was the target organ, as it had the highest concentration of ions. In addition, the abnormal increases in the tungsten ion concentrations in the liver and kidney may be closely related to the immune damage we observed. This study provides a theoretical basis and data support for the systematic evaluation of the health hazards of nano-WC and a reference for the safe use of nanomaterials.

The Synthesis and Polymer-Reinforced Mechanical Properties of SiO2 Aerogels: A Review.

Silica aerogels are considered as the distinguished materials of the future due to their extremely low thermal conductivity, low density, and high surface area. They are widely used in construction engineering, aeronautical domains, environmental protection, heat storage, etc. However, their fragile mechanical properties are the bottleneck restricting the engineering application of silica aerogels. This review briefly introduces the synthesis of silica aerogels, including the processes of sol-gel chemistry, aging, and drying. The effects of different silicon sources on the mechanical properties of silica aerogels are summarized. Moreover, the reaction mechanism of the three stages is also described. Then, five types of polymers that are commonly used to enhance the mechanical properties of silica aerogels are listed, and the current research progress is introduced. Finally, the outlook and prospects of the silica aerogels are proposed, and this paper further summarizes the methods of different polymers to enhance silica aerogels.

Experimental Study of the Thermal Decomposition Properties of Binary Imidazole Ionic Liquid Mixtures.

Ionic liquids (ILs) have a wide range of applications, owing to their negligible vapor pressure, high electrical conductivity, and low melting point. However, the thermal hazards of ILs and their mixtures are also non-negligible. In this study, the thermal hazards of various binary imidazolium ionic liquids (BIIL) mixtures were investigated. The effects of parent salt components and molar ratios on the thermal decomposition temperature (Td) and flashpoint temperature (Tf) are investigated. It is found that both Td and Tf increase as the proportion of highly thermally stable components in BIIL mixtures increases. Furthermore, the decomposition process of BIIL mixtures can be divided into two stages. For most molar ratios, the Tf of the BIIL mixtures is in the first stage of thermal decomposition. When the proportion of highly thermally stable components is relatively high, Tf is in the second stage of thermal decomposition. The flammability is attributed to the produced combustible gases during the thermal decomposition process. This work would be reasonably expected to provide some guidance for the safety design and application of IL mixtures for engineering.

Prediction and Construction of Energetic Materials Based on Machine Learning Methods.

Energetic materials (EMs) are the core materials of weapons and equipment. Achieving precise molecular design and efficient green synthesis of EMs has long been one of the primary concerns of researchers around the world. Traditionally, advanced materials were discovered through a trial-and-error processes, which required long research and development (R&D) cycles and high costs. In recent years, the machine learning (ML) method has matured into a tool that compliments and aids experimental studies for predicting and designing advanced EMs. This paper reviews the critical process of ML methods to discover and predict EMs, including data preparation, feature extraction, model construction, and model performance evaluation. The main ideas and basic steps of applying ML methods are analyzed and outlined. The state-of-the-art research about ML applications in property prediction and inverse material design of EMs is further summarized. Finally, the existing challenges and the strategies for coping with challenges in the further applications of the ML methods are proposed.

Geographical discrimination of ethanol based on stable isotope ratio analysis coupled with statistical methods: The Chinese case study.

The demand for the effective traceability of hazardous chemicals is crucial for preventing and controlling chemical spills and other accidents involving hazardous chemicals. The aim of the study was to investigate the correlation between the geographical location of ethanol-producing industrial sites and the carbon, hydrogen, and oxygen stable isotope ratios of the Chinese-manufactured ethanol using statistical classification analysis to enable the traceability of the ethanol. The isotopic data of 54 ethanol samples obtained from 18 different ethanol manufacturing plants in China between 2019 and 2020. The results of the statistical analysis demonstrated that the δ18O values of the ethanol positively correlated with latitudes of the production plants but negatively correlated with the δ13C values of the ethanol. A small number of samples derived from sites that were geographically close to each other could not be visually distinguished by PCA and HCA. However, by applying and comparing the results of classification by LDA, K-NN and Ensemble, an optimal classification model was obtained. Upon application of these models, 96.3% of the ethanol samples were correctly classified based on their geographical origin, indicating that the combination of isotopic ratios and latitude data is practical and effective for measuring the traceability of ethanol.

Nano-SAR Modeling for Predicting the Cytotoxicity of Metal Oxide Nanoparticles to PaCa2.

Nowadays, the impact of engineered nanoparticles (NPs) on human health and environment has aroused widespread attention. It is essential to assess and predict the biological activity, toxicity, and physicochemical properties of NPs. Computation-based methods have been developed to be efficient alternatives for understanding the negative effects of nanoparticles on the environment and human health. Here, a classification-based structure-activity relationship model for nanoparticles (nano-SAR) was developed to predict the cellular uptake of 109 functionalized magneto-fluorescent nanoparticles to pancreatic cancer cells (PaCa2). The norm index descriptors were employed for describing the structure characteristics of the involved nanoparticles. The Random forest algorithm (RF), combining with the Recursive Feature Elimination (RFE) was employed to develop the nano-SAR model. The resulted model showed satisfactory statistical performance, with the accuracy (ACC) of the test set and the training set of 0.950 and 0.966, respectively, demonstrating that the model had satisfactory classification effect. The model was rigorously verified and further extensively compared with models in the literature. The proposed model could be reasonably expected to predict the cellular uptakes of nanoparticles and provide some guidance for the design and manufacture of safer nanomaterials.

Adenomatous polyposis coli as a predictor of environmental chemical-induced transgenerational effects related to male infertility.

Exposure to toxic environmental chemicals during pregnancy is a ubiquitous threat to health with potentially transgenerational consequences. However, the underlying mechanism of how transgenerational effects occur as part of environmental chemical exposure are not well understood. We investigated the potential molecular changes associated with dibutyl phthalate exposure that induced transgenerational effects, using a rat model. Through the analysis of the Gene Expression Omnibus database, we found some similar studies of environmental exposure induced transgenerational effects. Then, we analyzed one of the studies and our results to identify the adenomatous polyposis coli (APC) gene. This gene participated the most of the pathways and was upregulated in both studies. We used the miRWALK data set to predict the microRNAs which targeted the APC gene. We confirmed the miR-30 family were significantly downregulated in F3 testis tissues and targeted the APC gene. In conclusion, the miR-30 family/APC interaction is a potential mechanism for the transgenerational effects induced by the environmental chemical.

The Pneumotoxic Effect and Indium Ion Release Induced by Indium Tin Oxide Nanoparticles.

With the increasing industrial production and the broaden applications of indium tin oxide (ITO) materials, frequent exposure has posed great concerns for people, especially the workers in the indium related manufacturing plants. The exposed-workers have been reported to adverse effect and even die from the ITO-induced pulmonary disorders called "indium lung." In addition to the epidemiologic studies, the increasing animal studies also demonstrated the lung injuries induced by the acute or chronic respiratory exposure of ITO nanoparticles (ITO NPs). They could enter into the cells owing to the small particle size and induce oxidative stress, inflammatory responses, cytotoxicity or even genotoxicity. The indium ions released from the ITO particles via lysosomal acidification considered as the actual entity responsible for the toxicity of ITO NPs. To date, no effective therapies are available against ITO-induced pulmonary diseases, which calls for the full explorations of the pathological factors. Our present mini-review summarizes the current reports on ITO nanoparticles-induced pneumotoxic effect with focus on the indium ion release, which could help warrant the health risks of ITO and other ITO-based materials.

Prediction of the Auto-Ignition Temperatures of Binary Miscible Liquid Mixtures from Molecular Structures.

A quantitative structure-property relationship (QSPR) study is performed to predict the auto-ignition temperatures (AITs) of binary liquid mixtures based on their molecular structures. The Simplex Representation of Molecular Structure (SiRMS) methodology was employed to describe the structure characteristics of a series of 132 binary miscible liquid mixtures. The most rigorous "compounds out" strategy was employed to divide the dataset into the training set and test set. The genetic algorithm (GA) combined with multiple linear regression (MLR) was used to select the best subset of SiRMS descriptors, which significantly contributes to the AITs of binary liquid mixtures. The result is a multilinear model with six parameters. Various strategies were employed to validate the developed model, and the results showed that the model has satisfactory robustness and predictivity. Furthermore, the applicability domain (AD) of the model was defined. The developed model could be considered as a new way to reliably predict the AITs of existing or new binary miscible liquid mixtures, belonging to its AD.

Prediction of Lower Flammability Limits for Binary Hydrocarbon Gases by Quantitative Structure-A Property Relationship Approach.

The lower flammability limit (LFL) is one of the most important parameters for evaluating the fire and explosion hazards of flammable gases or vapors. This study proposed quantitative structure-property relationship (QSPR) models to predict the LFL of binary hydrocarbon gases from their molecular structures. Twelve different mixing rules were employed to derive mixture descriptors for describing the structures characteristics of a series of 181 binary hydrocarbon mixtures. Genetic algorithm (GA)-based multiple linear regression (MLR) was used to select the most statistically effective mixture descriptors on the LFL of binary hydrocarbon gases. A total of 12 multilinear models were obtained based on the different mathematical formulas. The best model, issued from the norm of the molar contribution formula, was achieved as a six-parameter model. The best model was then rigorously validated using multiple strategies and further extensively compared to the previously published model. The results demonstrated the robustness, validity, and satisfactory predictivity of the proposed model. The applicability domain (AD) of the model was defined as well. The proposed best model would be expected to present an alternative to predict the LFL values of existing or new binary hydrocarbon gases, and provide some guidance for prioritizing the design of safer blended gases with desired properties.

Construction of Super-Hydrophobic Lignocellulosic Nanofibrils Aerogels as Speedy Oil Absorbents.

Lignocellulosic nanofibrils (LCNF) aerogels have a three-dimensional structure, with large specific surface area, low density, which is promising to be developed into a new type of adsorbent with high absorption capacity. However, LCNF aerogels have the problem of simultaneous oil and water adsorption. This high hydrophilicity directly leads to low adsorption efficiency in oil-water systems. This paper suggests a facile and economical method for the synthesis of biocompatible CE-LCNF aerogels using LCNF and Castor oil triglycidyl ether (CE) was successfully established. The use of LCNF enabled aerogels to possess remarkably uniform pore size and structural integrity, while the introduction of hydrophobic silica produced stable superhydrophobicity for more than 50 days at room temperature. These aerogels presented desirable hydrophobicity (131.6°), excellent oil adsorption capacity (62.5 g/g) and excellent selective sorption property, making them ideal absorbents for oil spill cleaning. The effects of ratios of LCNF to CE composition, temperatures and oil viscosity on the oil adsorption performance of aerogels were estimated. The results displayed that the aerogels had the maximum adsorption capacity at 25 °C. The pseudo-secondary model had higher validity in oil adsorption kinetic theories compared to the pseudo-first-order model. The CE-LCNF aerogels were excellent super-absorbents for oil removal. Moreover, the LCNF was renewable and nontoxic, which has the potential to promote environmental applications.

Adsorption of Co2+ and Cr3+ in Industrial Wastewater by Magnesium Silicate Nanomaterials.

In this paper, two flower-like magnesium silicate nanomaterials were prepared. These and another two commercial magnesium silicate materials were characterized using a scanning electron microscope, the N2 adsorption-desorption method, and other methods. The structure-activity relationship between the adsorption performance of these four magnesium silicate materials and their specific surface area, pore size distribution, and pore structure was compared. The results showed that the 3-FMS modified by sodium dodecyl sulfonate (SDS) had the largest specific surface area and pore size, the best adsorption performance, and the largest experimental equilibrium adsorption capacity (qe,exp) for Co2+, reaching 190.01 mg/g, and Cr3+, reaching 208.89 mg/g. The adsorption behavior of the four materials for Co2+ and Cr3+ both fitted the pseudo-second-order kinetic model and Langmuir adsorption model, indicating that chemical monolayer uniform adsorption was the dominant adsorption process. Among them, the theoretical adsorption capacity (qm) of 3-FMS was the highest, reaching 207.62 mg/g for Co2+ and 230.85 mg/g for Cr3+. Through further research, it was found that the four materials mainly removed Co2+ and Cr3+ through electrostatic adsorption, surface metal ions (Mg2+), and acidic groups (-OH and -SO3H) exchanging with ions in solution. The adsorption performance of two self-made flower-like magnesium silicate materials for Co2+ and Cr3+ was superior to that of two commercial magnesium silicates.

Experimental study on the methane explosion suppression by ultra-fine water mist containing bacteria under degradation for five times.

In a semi-closed visualization pipeline, this experiment studied the inhibitory effect of ultra-fine pure water mist, ultra-fine water mist containing inorganic salt and ultra-fine water mist containing bacteria-inorganic salt on 9.8% methane explosion under five different quality of spray volume. Combined with the methane explosion suppression experiment, the ability of methane-oxidizing bacteria to degrade 9.8% of methane was studied in a simulated pipeline. Experiments showed that the addition of inorganic salt and the degradation of methane-oxidizing bacteria could improve the suppression explosion effect of ultra-fine water mist, and the suppression explosion effect was related to the volume of water mist. Under the same ultra-fine water mist condition, with the increase of the volume of water mist, the explosion suppression effect was improved. Compared with pure methane, pure water ultra-fine water mist, and inorganic salt ultra-fine water mist, the maximum explosion overpressure and flame propagation speed under the condition of bacteria-inorganic salt ultra-fine water mist were significantly reduced. Compared with the explosion of pure methane, due to the degradation of methane by methane-oxidizing bacteria, when the degradation time was 10 h, and the volume of ultra-fine water mist containing bacteria-inorganic salt was 12.5 mL, the maximum explosion overpressure dropped significantly from 0.663 to 0.343 MPa, a decrease of 48.27%. The appearance time of the maximum explosion overpressure was delayed from 208.8 to 222.6 ms. The peak flame velocity was 4 m s-1, which was 83.3% lower than that of 9.8% pure methane explosion. This study will contribute to the development of efficient ultrafine water mist synergistic inhibitors for the prevention of methane explosion disasters.

Modified approaches to prepare nano-magnesium silicates with hierarchical pore structure and their performance towards adsorption of Cd2.

A series of flower-like magnesium silicate samples with hierarchical pore were prepared by the solvothermal method under template-free conditions using sodium dodecyl sulfate as the modifier and ethanol-water as the solvent. These samples were characterized by various methods and were evaluated for the adsorption of heavy metal Cd2+. The results showed that the adding modifier did not change the crystal structure of the magnesium silicate samples. In the range of 2~80 nm, they still showed hierarchical pore distribution mainly composed of mesopores and macropores, which facilitates the rapid transport of adsorbent within the pore channel. Therefore, the adsorption of Cd2+ was greatly accelerated. Meanwhile, the larger specific surface area (as high as 553 m2/g) of these samples significantly increased the theoretical maximum adsorption amount of Cd2+ up to 295.3 mg/g due to more available adsorption sites. The adsorption dynamic behavior of the samples on Cd2+ was in accordance with the pseudo-second-order adsorption model, and their thermodynamic behavior follows the Langmuir adsorption model. The adsorption mechanism of the sample was proposed as electrostatic adsorption and exchange of metal ions and acidic groups on its surface with ions in solution. The obtained magnesium silicate materials are expected to remove heavy metals from wastewater.

The Cytotoxicity of Tungsten Ions Derived from Nanoparticles Correlates with Pulmonary Toxicity.

Tungsten carbide nanoparticles (nano-WC) are prevalent in composite materials, and are attributed to their physical and chemical properties. Due to their small size, nano-WC particles can readily infiltrate biological organisms via the respiratory tract, thereby posing potential health hazards. Despite this, the studies addressing the cytotoxicity of nano-WC remain notably limited. To this purpose, the BEAS-2B and U937 cells were cultured in the presence of nano-WC. The significant cytotoxicity of nano-WC suspension was evaluated using a cellular LDH assay. To investigate the cytotoxic impact of tungsten ions (W6+) on cells, the ion chelator (EDTA-2Na) was used to adsorb W6+ from nano-WC suspension. Subsequent to this treatment, the modified nano-WC suspension was subjected to flow cytometry analysis to evaluate the rates of cellular apoptosis. According to the results, a decrease in W6+ could mitigate the cellular damage and enhance cell viability, which indicated that W6+ indeed exerted a significant cytotoxic influence on the cells. Overall, the present study provides valuable insight into the toxicological mechanisms underlying the exposure of lung cells to nano-WC, thereby reducing the environmental toxicant risk to human health.

Study on the effect of nanoparticles combined with silicone surfactant and cationic surfactant on foam and fire extinguishing performance.

Aqueous film-forming foam (AFFF) in firefighting foam can effectively extinguish oil fire. However, AFFF will be phased out due to the presence of persistent organic pollutants such as perfluorooctane sulfonates. It is necessary to explore environment-friendly foam extinguishing agent. Silicone surfactant is a kind of environmentally friendly surfactants with high surface activity, which can be used as a substitute for fluorocarbon surfactant. In this study, silicone surfactant and cationic surfactant were combined to adsorb nanosilica particles to form a multiphase system. The foaming property and foam stability of the multiphase system were tested by stirring method. The foam suppression effect on fuel vapor, fire extinguishing, and burn-back performance was tested by self-designed foam suppression device and foam generating device of porous glass with recyclable liquid supply. The experimental results show that foam stability is enhanced and the foaming property is slightly decreased after the addition of nanoparticles. When the component of three-phase foam reaches the optimum, its suppression effect on fuel vapor is better than that of two-phase foam. The results of fire extinguishing and burn-back performance test showed that the fire extinguishing effect of three-phase foam was slightly worse than that of AFFF, but it has extremely strong burn-back performance.

Effects of passenger blockage on smoke flow properties in subway station fires.

This study investigates the effects of the passenger blockage on the smoke flow properties in the subway station fires. A series of numerical simulations was conducted in a full-scale subway station model under different smoke exhaust volumes (24-96 m3/s) and passenger blockage scenarios. The parameter uncertainty and the model uncertainty were fully analyzed. Results demonstrate that the optimal smoke exhaust volume is 96 m3/s when there is no passenger blockage. When the passenger blockage exists, its effects on the smoke exhaust efficiency, the smoke layer height, and the temperature profile beneath the ceiling are significant. The optimal smoke exhaust volume can only guarantee the passenger's safe evacuation in the blockage scenarios with the low passenger blockage level. For the high passenger blockage level, some measures should be taken to reduce the harm to the passengers near the fire source.

Preparation and study of the flame retardant properties of C60/PMMA microspheres.

In this paper, highly flame retardant C60/PMMA composites were prepared using an in situ polymerization method by introducing fullerene (C60) into polymethyl methacrylate (PMMA) to improve its combustion characteristics. The apparent morphologies of PMMA and C60/PMMA microspheres were observed by scanning electron microscopy (SEM), and the structure was characterized by infrared spectroscopy (FT-IR). The thermal stability and flame retardancy were characterized using a synchronous thermal analyzer, a cone calorimeter and an oxygen index tester. The results show that the maximum initial decomposition temperature of C60/PMMA-2 (prepared using C60 with a concentration of 2 mg mL-1) is 234.89 °C, which is about 59.89 °C higher than that of PMMA, and the thermal stability is the best. The limiting oxygen index of the C60/PMMA-2 composite is 21.8, which is 28.2% higher than that of pure PMMA. In addition, the peak heat release rate (PHRR) of C60/PMMA is reduced by 630.4 kW m-2 when compared with pure PMMA, which means that the flame retardant property is improved. Meanwhile, the mechanical properties of the PMMA are also improved by adding C60.

Thermodynamic properties, decomposition kinetics of 2-(5-amino-2H-tetrazol-1-yl)-4-amine-3,5-dinitropyridine.

A novel energetic material 2-(5-amino-2H-tetrazol-1-yl)-4-amine-3,5-dinitropyridine (ATDP) was synthesized and characterized by 1H NMR, 13C NMR, mass spectroscopy, and elemental analysis. The research by differential scanning calorimetry (DSC) shows that ATDP decomposed about 290 °C. The calculating results of kinetic parameters using Ozawa method, Kissinger method, and Starink method were quite consistent. Self-accelerated decomposition temperature (TSADT), thermal ignition temperature (TTIT), and critical temperature of thermal explosion (Tb) were 272.55 °C, 121.71 °C, and 137.67 °C, respectively. Geometric optimization, heat of formation, detonation velocity (D), detonation pressure (P), bond dissociation energy (BDE), and electrostatic potential (ESP) were explored using Gaussian 16. The results show that ATDP has a much larger ΔHf,gas value than HMX(272.6 kJ mol-1). The D and P are predicted with the value of 7.50 km s-1 and 24.47 GPa, respectively. The relatively high BDE value (270.77 kJ mol-1) indicates that ATDP has moderate thermal stability.

Preparation and Study on the Flame-Retardant Properties of CNTs/PMMA Microspheres.

In this paper, carbon nanotubes (CNTs)/poly(methyl methacrylate) (PMMA) composites with excellent thermal stability and flame retardancy were prepared by in situ polymerization. The morphology, structure, transmittance, thermal stability, flame retardancy, and mechanical properties of the materials were characterized with scanning electron microscopy (SEM), thermogravimetric analysis (TGA), cone calorimetry, etc. According to the results, the initial decomposition temperature of CNTs/PMMA prepared using carbon nanotubes with a concentration of 2 mg/mL increases from 175 to 187 °C when compared with pure PMMA, and the weight loss ratio decreases significantly at the same time. In addition, the maximum limiting oxygen index (LOI) value of CNTs/PMMA composites is 22.17, which is 26.9% higher than that of PMMA. SEM images of residues after LOI tests demonstrate that when CNTs/PMMA is heated, a dense and stable interconnected network structure (i.e., carbon layer) is formed, which can effectively inhibit the combustion of pyrolysis products, prevent the transfer of heat and combustible gas, and finally interrupt the combustion of composite materials. However, a 25% decrease in the transmittance of CNTs/PMMA composites is observed in the Ultraviolet-visible (UV-vis) spectra. Although the addition of CNTs reduces the transparency of PMMA, its tensile and impact strength are all improved, which illustrates that CNT is a competitive flame retardant for PMMA.