High energy barrier hydroxyl radical dissociation mechanism of a low shock sensitivity dihydroxylammonium 5,5'-bistetrazole-1,1'-diolate (TKX-50) explosive.

As a representative of the new generation of high-energy explosives, TKX-50 has attracted widespread attention due to its remarkably low sensitivity toward shock. However, the reported decomposition barriers of TKX-50 (∼37 kcal mol-1) are comparable to those of commonly used explosives. The mechanism of its low shock sensitivity remains unclear. In this study, using an ab initio molecular dynamics method combined with a multiscale shock simulation technique and transition state calculations (at the B2PLYP-D3/Def2TZVP level), we discovered an unconventional reaction pathway of TKX-50 under shock, and its rate-controlling step is the dissociation of the hydroxyl radical (OH) from the anion ring after proton transfer, followed by ring rupture and the production of H2O and N2. The barrier for this OH dissociation reaction is as high as 51.9 kcal mol-1. In contrast, under thermal stimuli, TKX-50 prefers to open rings directly after proton transfer without losing the OH. The corresponding barrier is 35.4 kcal mol-1, which is in good agreement with previous studies. The reason for the unconventional reaction pathway of TKX-50 under shock may be the suppression of anion ring opening in thermal decomposition by steric hindrance upon shock compression. In addition, the dominant N2 generation pathway under shock releases less energy than pyrolysis which further explains the low shock sensitivity of TKX-50. This study comprehensively elucidates the different reaction mechanisms of TKX-50 under thermal and shock conditions and proposes a crucial reaction pathway leading to its low shock sensitivity. These findings will contribute to the understanding and application of tetrazole anionic energetic salts.

Single-sEV profiling identifies the TACSTD2 + sEV subpopulation as a factor of tumor susceptibility in the elderly.

BACKGROUND: Aging is a very complex physiological phenomenon, and sEVs are involved in the regulation of this mechanism. Serum samples from healthy individuals under 30 and over 60 years of age were collected to analyze differences in sEVs proteomics. RESULTS: Based on PBA analysis, we found that sEVs from the serum of elderly individuals highly express TACSTD2 and identified a subpopulation marked by TACSTD2. Using ELISA, we verified the upregulation of TACSTD2 in serum from elderly human and aged mouse. In addition, we discovered that TACSTD2 was significantly increased in samples from tumor patients and had better diagnostic value than CEA. Specifically, 9 of the 13 tumor groups exhibited elevated TACSTD2, particularly for cervical cancer, colon cancer, esophageal carcinoma, liver cancer and thyroid carcinoma. Moreover, we found that serum sEVs from the elderly (especially those with high TACSTD2 levels) promoted tumor cell (SW480, HuCCT1 and HeLa) proliferation and migration. CONCLUSION: TACSTD2 was upregulated in the serum of elderly individuals and patients with tumors, and could serve as a dual biomarker for aging and tumors.

Identification of gastric signet ring cell carcinoma based on endoscopic images using few-shot learning.

BACKGROUND: Deep learning (DL) models perform poorly when there are limited gastric signet ring cell carcinoma (SRCC) samples. Few-shot learning (FSL) can address the small sample problem. METHODS: EfficientNetV2-S was first pretrained on ImageNet and then pretrained on esophageal endoscopic images (i.e., base classes: normal vs. early cancer vs. advanced cancer) using transfer learning. Second, images of gastric benign ulcers, adenocarcinoma and SRCC, i.e., novel classes (n = 50 per class), were included. Image features were extracted as vectors using the dual pretrained EfficientNetV2-S. Finally, a k-nearest neighbor classifier was used to identify SRCC. The above proposed 3-way 3-shot FSL framework was conducted in three rounds. RESULTS: Dual pretrained FSL performed better than single pretrained FSL, endoscopists and traditional EfficientNetV2-S models. Dual pretrained FSL obtained the highest accuracy (79.4%), sensitivity (68.8%), recall (68.8%), precision (69.3%) and F1-score (0.691), and the senior endoscopist achieved the highest specificity of 93.6% when identifying SRCC. The macro-AUC and F1-score for dual pretraining (0.763 and 0.703, respectively) were higher than those for single pretraining (0.656 and 0.537, respectively), along with endoscopists and traditional EfficientNetV2-S models. The 2-way 3-shot FSL also performed better. CONCLUSION: The proposed FSL framework showed practical performance in the differentiation of SRCC on endoscopic images, suggesting the potential of FSL in the computer-aided diagnosis for rare diseases.

Reaction mechanism and electronic properties of host-guest energetic material CL-20/HA under high pressure by quantum-based molecular dynamics simulations.

The novel host-guest material 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane (CL-20)/hydroxylamine (HA) improves the detonation energy of CL-20 explosives without compromising its safety. However, the reaction mechanism of CL-20/HA under high pressure is not yet fully understood for the complex host-guest structure. A multiscale shock simulation technique by quantum-based molecular dynamics was performed to investigate the reaction mechanism of CL-20/HA under shock with different velocities along different directions, focusing on charge transfer, electronic properties, reaction path and product evolution. The structural changes caused by both insertion of HA and charge overlap between CL-20 and HA are responsible for the electronic changes and gap decrease. Directional charge transfer was observed between CL-20 and HA molecular fragments during shock in all shock loading directions, causing the CL-20 molecular group to become electrically non-neutral. The C-N bond in the CL-20 cage then broke, leading to the release of nitro and nitrous oxide at high temperatures and pressures. The HA molecules or free H atoms from HA could bond with the O atom in the nitro group, leading to the N-O bond cleavage. Some free H atoms could act as an intermediary, connecting two CL-20 molecules and forming dimeric molecules briefly. Compared with the pure CL-20 system, HA can inhibit the reaction of CL-20 in the CL-20/HA system to some extent during the initial shock stage. A further understanding of the chemical reaction mechanism and energy release in dense host-guest materials can be advanced by focusing on the microscopic internal effects of the guest molecule on the host molecule reactions.

Patients' Knowledge About the Endoscopic UltrasoundGuided Fine Needle Aspiration of Pancreas Is Not Enough.

BACKGROUND: The aim of the study is to evaluate the extent to which patients acquired necessary knowledge about pancreatic endoscopic ultrasound-guided fine needle aspiration and assess what should be more focused on in the informed consent process. METHODS: Adult patients enrolled in this study had pancreatic lesions confirmed by regular imaging and planned to undergo the first pancreatic endoscopic ultrasound-guided fine needle aspiration. These patients were asked to complete a questionnaire, including indications, possible results, downstream events, the risk for false-negative and malignant lesions, and so on. Then we conducted a longterm follow-up of these patients to obtain the final results. RESULTS: Most people (94.25%) correctly recognized that the indication of pancreatic endoscopic ultrasound-guided fine needle aspiration was to exclude malignant lesions. Almost all patients knew that the results could be benign or malignant, while the number of people who were aware of non-diagnostic (22%), indeterminate (18%) outcomes, and the possibility of further testing (20%) after the endoscopic ultrasound-guided fine needle aspiration has decreased significantly. Finally, we got that the false-negative rate and percentages of malignancy were 17.81% and 83.91%, while 98% of participants did not recognize that there is a false-negative risk of endoscopic ultrasound-guided fine needle aspiration and more than 2/3 of participants did not know how much risk they might have for malignant lesions. CONCLUSIONS: A high proportion of patients who received endoscopic ultrasound-guided fine needle aspiration could identify the indication for this procedure but remained unaware of possible outcomes, downstream events, especially the risk for false-negative and malignant lesions. It is necessary to improve the quality of dialogue between clinicians and patients, and the information about the risk of false-negative and malignancy may need to be emphasized in the informed consent process.

Machine learning quantitatively characterizes the deformation and destruction of explosive molecules.

Although explosives have been widely used in mines, road development, old building demolishing, and munition explosions; currently, how chemical bonds between atoms break and recombine, how the molecular structure is deformed and destroyed, how the reaction product molecules are formed, and the details for this rapid change process in explosive reactions are not yet fully understood, which limits the full use of explosive energy and safer use of explosives. This paper presents a quantitative model of molecular structure deformation using machine learning algorithms as well as a qualitative model of its relationship with molecular structure destruction, based on a molecular dynamics simulation and detailed analysis of the shock-loaded ε-CL-20, providing new perspectives for explosive community research. Specifically, the quantitative model of molecular structure deformation establishes the quantitative relationship between the molecular volume change and molecular position change, and between molecular distance change and molecular volume change using the machine learning algorithms such as Delaunay triangulation, clustering, and gradient descent. We find that the molecular spacing in explosives is strongly compressed after being shocked, and the peripheral structure can shrink inward, which is beneficial to keep the cage structure stable. When the peripheral structure is compressed to a certain extent, the cage structure volume begins to expand and is then destroyed. In addition, hydrogen atom transfer occurs within the explosive molecule. This study amplifies the structural changes and the chemical reaction process for explosive molecules after being strongly compressed by a shock wave, which can enrich the knowledge of the real detonation reaction process. The analysis method based on quantitative characterization using machine learning proposed in this study can also be used to analyze the microscopic reaction mechanism in other materials.

Recent Progress on Synthesis, Characterization, and Performance of Energetic Cocrystals: A Review.

In the niche area of energetic materials, a balance between energy and safety is extremely important. To address this "energy-safety contradiction", energetic cocrystals have been introduced. The investigation of the synthesis methods, characteristics, and efficacy of energetic cocrystals is of the utmost importance for optimizing their design and development. This review covers (i) various synthesis methods for energetic cocrystals; (ii) discusses their characteristics such as structural properties, detonation performance, sensitivity analysis, thermal properties, and morphology mapping, along with other properties such as oxygen balance, solubility, and fluorescence; and (iii) performance with respect to energy contents (detonation velocity and pressure) and sensitivity. This is followed by concluding remarks together with future perspectives.

Reaction mechanism of aluminum nanoparticles in explosives under high temperature and high pressure by shock loading.

Aluminum nanoparticles (ANPs) can greatly improve the power of explosives. However, the rapid reaction mechanism of ANPs under simultaneous high temperature and high pressure by shock loading is not fully understood. In this study, a detonation wave was generated by impact of an explosive supercell on the reflect wall, and the reflected wave was eliminated by changing the end-boundary velocity. In this way, the problem of long time simulation under extreme pressure was solved and reaction molecular dynamics simulations of ANPs in explosives under shock or detonation were then performed with the ReaxFF force field. The results showed that the ANP crystal structure first transformed under shock loading, and diffusion oxidation of the ANPs then occurred. The reaction rate of the ANPs under high-temperature and high-pressure conformed to an exponential function of the pressure and oxide-shell thickness. Finally, the ANPs were stretched and disintegrated with expansion of the detonation products, which further accelerated ANP oxidation. A thicker oxide shell and a wax covering on the ANPs limited diffusion of the O and N atoms into the ANPs, which slowed down the oxidation reaction of the ANPs. A wax covering also prevented direct contact of the ANPs with the explosive, weakening the effect of the ANPs on the reaction of the explosive. This work is of great importance to deeply understand the reaction mechanism and energy-release law of aluminized explosives.

CircLPAR3 Acts as an Oncogene in Oral Squamous Cell Carcinoma Through Regulating the miR-643/HMGB2 Network.

The malignant progression of oral squamous cell carcinoma (OSCC) has been confirmed to be mediated by a variety of factors, including circular RNA (circRNA). However, the role of circLPAR3 in OSCC development is still unclear. 70 paired OSCC tissues and normal control tissues were obtained from 70 OSCC patients. Quantitative real-time PCR was used to detect the expression of circLPAR3, microRNA (miR)-643, and high-mobility group box 2 (HMGB2). Cell proliferation, apoptosis, metastasis and stemness were assessed using cell counting kit 8 assay, colony-formation assay, flow cytometry, transwell assay and sphere formation assay. Marker protein expression and HMGB2 protein expression were determined by western blot analysis. The interaction between miR-643 and circLPAR3 or HMGB2 was confirmed by RNA pull-down assay, dual-luciferase reporter and RIP assay. The role of circLPAR3 in OSCC tumorigenesis was explored by constructing the xenograft models. Our data showed that circLPAR3 was highly expressed in OSCC tissues and cells. CircLPAR3 silencing suppressed OSCC cell proliferation, metastasis and stemness, while promoted apoptosis. On the mechanism, we discovered that circLPAR3 could sponge miR-643 to positive regulate HMGB2. MiR-643 overexpression had an inhibition effect on OSCC progression, and its inhibitor could reverse the negative regulation of circLPAR3 knockdown on OSCC progression. In addition, overexpressed HMGB2 also reversed the suppressive effect of circLPAR3 silencing on OSCC progression. Animal experiments results showed that downregulated circLPAR3 repressed OSCC tumorigenesis in vivo. Taken together, our data showed that circLPAR3 contributed to OSCC malignant progression through regulating the miR-643/HMGB2 axis.

[Improvement in compatibility of hot melt pressure-sensitive adhesive with cinnamon volatile oil and in vitro transdermal property by physical blending].

Hot melt pressure-sensitive adhesive(HMPSA) has broad application potential in the field of traditional Chinese medicine(TCM) plasters due to its high drug loading, weak skin irritation, satisfactory adhesion, etc. compared with rubber plasters.However, the structure of HMPSA is prone to suffer from the damage caused by volatile oils in TCM plasters. In view of this, a kind of HMPSA with a stable structure was prepared by physical blending of DINCH, polypropylene wax and liquid rubber(LIR) in the present study, which is denoted as DPL. The dosage of cinnamon volatile oil(CVO), the model drug, was selected with viscosity, softening point and cohesion as evaluation indexes. The interaction between DPL and HMPSA was investigated by Fourier transform infrared spectroscopy(FT-IR) and differential scanning calorimetry(DSC). The compatibility of HMPSA with CVO and its transdermal ability were studied by in vitro transdermal test, adhesion, scanning electron microscopy( SEM) and rheological evaluation. The results showed that 5% CVO began to damage the structure of HMPSA. The initial adhesion and holding adhesion of DPL-modified HMPSA(DPL-HMPSA) were not significantly changed compared with those of HMPSA, whereas the 180° peel strength was decreased. FI-IR unraveled that DPL formed the n-π conjugated system with styrene-isoprene-styrene block copolymer(SIS), and there was no significant difference in the glass transition temperature according to DSC results, which indicated the good compatibility of DPL with HMPSA. With 5% CVO loaded, the drug content of DPL-HMPSA was 1. 14 times higher than that of HMPSA, and the decrease rate of drug content in DPL-HMPSA was 16% lower than that in HMPSA after 3 months. SEM demonstrated that CVO did not cause obvious structural damage to DPL-HMPSA. Rheological evaluation revealed that the storage modulus and loss factor of DPL-HMPSA were higher than those of HMPSA, and the cohesion was also stronger. The percutaneous penetration rate of cinnamaldehyde in DPL-HMPSA was 2. 25 times that of HMPSA. In conclusion, DPL-HMPSA had more stable structure, better compatibility with CVO, and higher in vitro transdermal efficiency of cinnamaldehyde than before the modification. This study can provide reference for the mitigation of the matrix structure damage caused by volatile oil components in TCM plasters and the enhancement of the content and in vitro transdermal rate of drug.

TPGS assists the percutaneous administration of curcumin and glycyrrhetinic acid coloaded functionalized ethosomes for the synergistic treatment of psoriasis.

Combined therapy with anti-inflammatory drugs is preferred for the topical treatment of psoriasis, but the codelivery of drugs is restricted due to the lack of a suitable delivery system. Ethosomes with excellenttransdermal propertiesare perfect as carriers for hyperplastic skin. Therefore, glycyrrhetinic acid-D-α-tocopherol acid polyethylene glycol succinate (GA-TPGS) was synthesized, which prevented the inflammation and lipid peroxidation damage, thus effectively stabilizing the psoriasis. Then GA-TPGS was surface-modified on the curcumin (Cur) loaded ethosomes to construct curcumin-loaded GA-TPGS-modified multifunctional ethosomes (Cur@GA-TPGS-ES), exerting synergistic treatment for psoriasis. Using an interleukin-6-induced cell model, we found that Cur@GA-TPGS-ES displayed desirable suppression of inflammation response and oxidative stress damage. Compared with the ethanol solution, the percutaneous penetration rates of Cur and GA in Cur@GA-TPGS-ES were superior. In vivo microdialysis revealed similar results, suggesting an increase of transcutaneous absorption in Cur@GA-TPGS-ES. Fluorescence staining revealed that the cellular uptake and skin distribution were distinctly enhanced with the delivery by Cur@GA-TPGS-ES. After topical administration to imiquimod-induced psoriatic mice, the Cur@GA-TPGS-ES group showed powerful treatment from inflammatory infiltration inhibition of Cur, glucocorticoid-like effects of GA and anti-lipid peroxidation of TPGS. Overall, GA-TPGS mediated ethosomes possess more advantageous transdermal properties and synergistic antipsoriatic efficacy.

Mechanism of the improvement of the energy of host-guest explosives by incorporation of small guest molecules: HNO3 and H2O2 promoted C-N bond cleavage of the ring of ICM-102.

Host-guest materials exhibit great potential applications as an insensitive high-energy-density explosive and low characteristic signal solid propellant. To investigate the mechanism of the improvement of the energy of host-guest explosives by guest molecules, ReaxFF-lg reactive molecular dynamics simulations were performed to calculate the thermal decomposition reactions of the host-guest explosives systems ICM-102/HNO3, ICM-102/H2O2, and pure ICM-102 under different constant high temperatures and different heating rates. Incorporation of guest molecules significantly increased the energy level of the host-guest system. However, the initial reaction path of the ICM-102 molecule was not changed by the guest molecules. The guest molecules did not initially participate in the host molecule reaction. After a period of time, the H2O2 and HNO3 guest molecules promoted cleavage of the C-N bond of the ICM-102 ring. Stronger oxidation and higher oxygen content resulted in the guest molecules more obviously accelerating destruction of the ICM-102 ring structure. The guest molecules accelerated the initial endothermic reaction of ICM-102, but they played a more important role in the intermediate exothermic reaction stage: incorporation of guest molecules (HNO3 and H2O2) greatly improved the heat release and exothermic reaction rate. Although the energies of the host-guest systems were clearly improved by incorporation of guest molecules, the guest molecules had little effect on the thermal stabilities of the systems.

Recent Developments in the Principles, Modification and Application Prospects of Functionalized Ethosomes for Topical Delivery.

Transdermal drug delivery helps to circumvent the first-pass effect of drugs and to avoid drug-induced gastrointestinal tract irritation, compared with oral administration. With the extensive application of ethosomes in transdermal delivery, the shortages of them have been noticed continuously. Due to the high concentration of volatile ethanol in ethosomes, there are problems of drug leakage, system instability, and ethosome-induced skin irritation. Thus, there is a growing interest in the development of new generations of ethosomal systems. Functionalized ethosomes have the advantages of increased stability, improved transdermal performances, an extended prolonged drug release profile and site-specific delivery, due to their functional materials. To comprehensively understand this novel carrier, this review summarizes the properties of functionalized ethosomes, their mechanism through the skin and their modifications with different materials, validating their potential as promising transdermal drug delivery carriers. Although functionalized ethosomes have presented a greater role for enhanced topical delivery, challenges regarding their design and future perspectives are also discussed.

A quantum-based molecular dynamics study of the ICM-102/HNO3 host-guest reaction at high temperatures.

The contradiction between energy and safety of explosives is better balanced by the host-guest inclusion strategy. Understanding the reaction mechanism of the host-guest explosive is necessary. To deeply analyze the role of the small guest molecules in the host-guest system, a quantum-based molecular dynamics method was used to calculate the initial decomposition reaction of the new host-guest explosive ICM-102/HNO3 against the pure ICM-102 at several high temperatures. The incorporation of HNO3 had no significant influence on the initial decomposition step of ICM-102. Conversely, the earliest intramolecular hydrogen transfer reaction is delayed partly because the H and O atoms of HNO3 connect with the O and H atoms of ICM-102, respectively. As the reaction proceeds, guest molecules get heavily involved in the reaction and increase the reaction rate. The generation rate and quantity of the small oxidizing molecules in the final product were increased significantly in the ICM-102/HNO3 system. These mechanisms revealed that HNO3 molecules inhibit the early stages of the initial decomposition of ICM-102 to some extent, and play an important role in accelerating the decomposition subsequently.

Chemical reactions of a CL-20 crystal under heat and shock determined by ReaxFF reactive molecular dynamics simulations.

Studying the chemical reactions of hexanitrohexaazaisowurtzitane (CL-20) under heat and shock is helpful to understand its sensitivity and shock initiation mechanism. In this work, several molecular dynamics simulations were performed under three different conditions: high temperature, high temperature and pressure, and shock. The formation and breakage of chemical bonds, changes of bond lengths, and initial reactions were analysed. It was found that the main small-molecule product of CL-20 during initial decomposition under the three different conditions was always NO2, but the generation pathways were different. At high temperatures, NO2 was generated by the direct cleavage of N-NO2 bonds. In contrast, high pressure and shock promoted the transfer of O atoms to N atoms connected to NO2, leading to the breakage of N-NO2 bonds. Almost all NO2 originated from the transfer of O atoms under the shock conditions.

Influence of Ambidextrous Learning on Eco-Innovation Performance of Startups: Moderating Effect of Top Management's Environmental Awareness.

Ecological innovation is an inevitable trend for firms to enhance competitiveness and sustainably operate in the context of green economy. The previous literature has rarely discussed the influence of ambidextrous learning on the eco-innovation performance of startups and ignored the moderating effect of top management's environmental awareness from the perspective of microscopic psychology. We have conducted a questionnaire survey on 212 firms established within 4 years in the Pearl River Delta of China, using the structure mode and the PROCESS by Hayes (2013) to analyze the influence of ambidextrous learning, such as exploratory learning and exploitative learning, by startups on eco-innovation performance and verify the moderating effect of top management's environmental awareness. The results show that exploratory learning and exploitative learning have a positive and significant influence on eco-innovation performance, indicating that the organizational learning of startups is conducive to improving eco-innovation performance; under the moderating effect of top management's environmental awareness, the influence of exploratory learning and exploitative learning on eco-innovation performance may differ. The results also show that in the process of organizing ambidextrous learning, startups should help raise the environmental awareness of top management to improve the eco-innovation performance, thus providing guidance for startups to carry out eco-innovation activities and for local governments to make decisions on green economy.

Thermal stability mechanism via energy absorption by chemical bonds bending and stretching in free space and the interlayer reaction of layered molecular structure explosives.

Layered molecular structure explosives have the characteristic of great thermal stability. Understanding the mechanism of thermal stability and the reactions of layered molecular structure explosives can provide new ideas for the design of thermally stable explosives. In a molecular dynamics simulation of thermal decomposition of the layered molecular structure explosive 2,4,6-triamino-5-nitropyrimidine-1,3-dioxide, we find that the layered molecular structure provides free space for chemical bond deflection and expansion so that the external energy absorbed by chemical bonds on nonbenzene rings can be converted into angle bending energy and bond-stretching energy, which makes chemical bonds difficult to break and increases the thermal stability of the explosives. In the layered molecular structure explosive reactions, hydrogen-oxygen-bonded interlayer dimerizations and hydrogen interlayer transfer reactions are dominant.

Decomposition and Energy-Enhancement Mechanism of the Energetic Binder Glycidyl Azide Polymer at Explosive Detonation Temperatures.

Replacing existing inert binders with energetic ones in composite explosives is a novel way to improve the explosive performance, on the proviso that energetic binders are capable of releasing chemical energy rapidly in the detonation environment. Known to be a promising candidate, the reaction mechanism of glycidyl azide polymer (GAP) at typical detonation temperatures higher than 3000 K has been theoretically studied in this work at the atomistic level. By analyzing and tracking the cleavage of characteristic chemical bonds, it was found that at the detonation temperature, GAP was able to release a large amount of energy and small molecule products at a speed comparable to commonly used explosives in the early reaction stage, which was mainly attributed to the decomposition of azide groups into N2 and the main chain breakage into small fragments. Moreover, N2 generation was found to be accelerated by H atom transfer at an earlier reaction step. The dissociation energy of the main chain was lowered with structure deformation so as to facilitate the fragmentation of the GAP chain. Based on this analytical study of reaction kinetics, GAP was found to have higher reactivity at the detonation temperature than at lower temperatures. The small molecules' yield rate is of the same order of magnitude as an explosive detonation reaction, indicating that GAP has the potential to improve the performance of composite explosives. Our study reveals the chemical decomposition mechanism of a typical energetic binder, which would aid in the future design and synthesis of energetic binders so as to achieve both sensitivity-reducing and energy-enhancing performance goals simultaneously.

Study of the effect mechanism of municipal solid waste gasification conditions on the production of H2 and CO using modelling technique.

The municipal solid waste (MSW) gasification process was numerically studied in the work. The effect mechanisms of particle size, temperature and gasification atmosphere on the production of H2 and CO were investigated in detail. The results demonstrated that the total volume fraction of H2 and CO dropped from 51.7% to 49.7% with particle size increasing from 20 < d < 30 mm to 80 < d < 100 mm under steam atmosphere. With the temperature increasing from 600 °C to 1000 °C, the total volume fraction of H2 and CO was raised from 56.1% to 65.8% under steam atmosphere. Five different gasifying agents: 100%CO2, 21%O2/79%N2, 21%O2/79%H2O, 21%CO2/79%H2O, 21%O2/79%CO2 were simulated, and the total volume fraction of H2 and CO was 51.87%, 19.1%, 56.13%, 48.36% and 42.98%, respectively. In the gasification conditions considered in this work, H + H2O⇔OH + H2 (R84) played a key role in the yield of H2, and the yield of CO was significantly affected by H + CO2⇔OH + CO (R99) and H + CH2CO⇔CH3+CO (R81).

Effect of density on the thermal decomposition mechanism of ε-CL-20: a ReaxFF reactive molecular dynamics simulation study.

The explosive detonation reaction occurs when explosives are compressed by different shock strengths, and the degree of compression affects the chemical reaction of the detonation process. The thermal decomposition mechanism of explosives under different compression densities has thus attracted significant research interest, and a better understanding of this mechanism would be helpful for determining the mechanism of the detonation reaction of explosives. In this study, a ε-CL-20 supercell was constructed, and the thermal decomposition was calculated at different compression densities and temperatures using molecular dynamics simulations based on the ReaxFF-lg reactive force field. We analyzed the effect of density on the main elementary reaction, which consists of the initial reaction and the formation of final products. In addition, we studied the effect of density on the generation of clusters and the reaction kinetics of the thermal decomposition. The results indicate that the initial reaction pathway of the CL-20 molecule is the cleavage of the N-NO2 bond at different densities and that the frequency of N-NO2 bond breakage decreases at high density. As the density increases, clusters easily form and are resistant to decomposition at the later stage of thermal decomposition, which eventually leads to a decrease in the number of final products. Increasing the initial density of CL-20 significantly increases the reaction rate of the initial decomposition but hardly changes the activation energy of the decomposition.