Decomposition Properties Research Articles

Porous nanosheets of TKX-50 by ice-templating strategy with excellent thermal decomposition and combustion properties

ABSTRACT Nanostructured energetic materials have attracted considerable research interests during the past decades because of their improved performances in thermal decomposition and combustion. In this work, a porous nanosheet structure of dihydroxylammonium 5, 5′-bistetrazole-1, 1′-diolate (TKX-50) has been fabricated by a facile ice templating strategy, which is based on the self-assembly of TKX-50 during rapid recrystallization. Thermal decomposition properties were determined by differential scanning calorimetry/thermogravimetry (DSC/TG) and TG-FTIR analyses. The laser-ignited and constant-volume combustions and mechanical sensitivity were conducted. As-prepared TKX-50 mainly presents porous nanosheets (NS-TKX-50) assembled by the secondary nanoparticles. NS-TKX-50 is typical of mesoporous materials with high specific surface area and pore volume. Compared with raw material, NS-TKX-50 exhibits lower thermal decomposition peak temperature and higher active energy. In thermal decomposition process, a great deal of gaseous products have been generated in a very narrow temperature range. These thermal decomposition features suggest a quick energy-release rate and high energy output. Contrary to incomplete combustion of raw material, NS-TKX-50 shows high-efficiency and self-sustaining laser-ignited combustion feature with a drastically decreased ignition threshold. And its pressurization rate and peak pressure are remarkably increased. Sensitivity results confirmed the visibly reduced impact and friction sensitivity of NS-TKX-50.

Oxidation properties and thermal hazard of pinane

Although pinane has a wide range of uses, there are no reports on the safety of pinane oxidation. The thermal oxidation properties of pinane were investigated through MCPVT. The primary oxidation products of pinane were separated and structurally characterised, and its decomposition properties were assessed by MCPVT and DSC. The results showed that pinane had an initial oxygen uptake temperature of 123.5 °C and exploded when the temperature rose to 132.7 °C. Pinane autoxidised at 110 °C for 9 h formed a high level of peroxide (81.18 mmol/kg) with an activation energy of 138.77 kJ/mol. The oxidation of pinane occurs mainly at the tertiary carbon atom attached to the methyl group, and the main peroxide produced is pinane hydroperoxide (PHP). PHP has an exothermic onset temperature (Tonset), a heat of decomposition (QDSC) and an activation energy of decomposition of 114.6 °C, 1878.0 J/g and 109.4 kJ/mol respectively, which should classify it as a hazardous substance. PHP has a lower activation energy than pinane and is the determining factor for the safety of the pinane oxidation reaction. The products of thermal runaway of pinane are relatively complex and consist mainly of 1-(2, 2-dimethyl-3-ethylcyclobutyl) ethanone, nopinone, 2, 3-pinanediol and pinonic acid.

Advanced Human Activity Recognition through Data Augmentation and Feature Concatenation of Micro-Doppler Signatures

Developing accurate classification models for radar-based Human Activity Recognition (HAR), capable of solving real-world problems, depends heavily on the amount of available data. In this paper, we propose a simple, effective, and generalizable data augmentation strategy along with preprocessing for micro-Doppler signatures to enhance recognition performance. By leveraging the decomposition properties of the Discrete Wavelet Transform (DWT), new samples are generated with distinct characteristics that do not overlap with those of the original samples. The micro-Doppler signatures are projected onto the DWT space for the decomposition process using the Haar wavelet. The returned decomposition components are used in different configurations to generate new data. Three new samples are obtained from a single spectrogram, which increases the amount of training data without creating duplicates. Next, the augmented samples are processed using the Sobel filter. This step allows each sample to be expanded into three representations, including the gradient in the x-direction (Dx), y-direction (Dy), and both x- and y-directions (Dxy). These representations are used as input for training a three-input convolutional neural network-long short-term memory support vector machine (CNN-LSTM-SVM) model. We have assessed the feasibility of our solution by evaluating it on three datasets containing micro-Doppler signatures of human activities, including Frequency Modulated Continuous Wave (FMCW) 77 GHz, FMCW 24 GHz, and Impulse Radio Ultra-Wide Band (IR-UWB) 10 GHz datasets. Several experiments have been carried out to evaluate the model's performance with the inclusion of additional samples. The model was trained from scratch only on the augmented samples and tested on the original samples. Our augmentation approach has been thoroughly evaluated using various metrics, including accuracy, precision, recall, and F1-score. The results demonstrate a substantial improvement in the recognition rate and effectively alleviate the overfitting effect. Accuracies of 96.47%, 94.27%, and 98.18% are obtained for the FMCW 77 GHz, FMCW 24 GHz, and IR- UWB 10 GHz datasets, respectively. The findings of the study demonstrate the utility of DWT to enrich micro-Doppler training samples to improve HAR performance. Furthermore, the processing step was found to be efficient in enhancing the classification accuracy, achieving 96.78%, 96.32%, and 100% for the FMCW 77 GHz, FMCW 24 GHz, and IR-UWB 10 GHz datasets, respectively.

Successional action of Bacteroidota and Firmicutes in decomposing straw polymers in a paddy soil

BackgroundDecomposition of plant biomass is vital for carbon cycling in terrestrial ecosystems. In waterlogged soils including paddy fields and natural wetlands, plant biomass degradation generates the largest natural source of global methane emission. However, the intricate process of plant biomass degradation by diverse soil microorganisms remains poorly characterized. Here we report a chemical and metagenomic investigation into the mechanism of straw decomposition in a paddy soil.ResultsThe chemical analysis of 16-day soil microcosm incubation revealed that straw decomposition could be divided into two stages based on the dynamics of methane, short chain fatty acids, dissolved organic carbon and monosaccharides. Metagenomic analysis revealed that the relative abundance of glucoside hydrolase (GH) encoding genes for cellulose decomposition increased rapidly during the initial stage (3–7 days), while genes involved in hemicellulose decomposition increased in the later stage (7–16 days). The increase of cellulose GH genes in initial stage was derived mainly from Firmicutes while Bacteroidota contributed mostly to the later stage increase of hemicellulose GH genes. Flagella assembly genes were prevalent in Firmicutes but scarce in Bacteroidota. Wood–Ljungdahl pathway (WLP) was present in Firmicutes but not detected in Bacteroidota. Overall, Bacteroidota contained the largest proportion of total GHs and the highest number of carbohydrate active enzymes gene clusters in our paddy soil metagenomes. The strong capacity of the Bacteroidota phylum to degrade straw polymers was specifically attributed to Bacteroidales and Chitinophagales orders, the latter has not been previously recognized.ConclusionsThis study revealed a collaborating sequential contribution of microbial taxa and functional genes in the decomposition of straw residues in a paddy soil. Firmicutes with the property of mobility, WLP and cellulose decomposition could be mostly involved in the initial breakdown of straw polymers, while Bacteroidota became abundant and possibly responsible for the decomposition of hemicellulosic polymers during the later stage.

Denoising complex background radar signals based on wavelet decomposition thresholding

Abstract The echo signals of the radar in complex backgrounds are often very unstable and thus require effective noise cancellation. In this paper, according to the characteristics of continuous wavelet variation and discrete wavelet variation, the decomposition effect of multi-resolution analysis and orthogonal Mallat algorithm on low-frequency and high-frequency non-smooth signals is studied, and the selection method of wavelet bases is explored. Then, the noise characteristics affecting the pulsed LIDAR system are analyzed, and the LIDAR pulse signal is simulated by MATLAB, while Gaussian white noise is introduced to obtain the noise-added echo signal, and then multiple wavelet threshold denoising methods are applied to denoise the echo signal. For the input signal-to-noise ratio of −10.57 dB, the output signal-to-noise ratios of db8, db9, db10, and bior3.5 wavelet bases under forced thresholding are −1.971, −2.178, −2.173, and −1.032, respectively. For different input signal-to-noise ratios, the average root mean square error of db8, db9, db10, and bior3.5 wavelet bases under default thresholding is 1.51. The denoising methods for radar signals using the properties of wavelet decomposition have obvious superiority compared to traditional filters, and the wavelet transforms threshold denoising methods have wide adaptability.

Study on the thermal decomposition of an ionic liquid propellant [EMIm][BF4

Ionic liquids are regarded as promising propellants for green spacecraft propulsion. A well understanding of their fundamental properties is essential to accelerate the applications in practical propulsion. Therefore, the decomposition properties of an imidazole-based ionic liquid 1-ethyl-3-methyl imidazolium tetrafluoroborate ([EMIm][BF4]) were studied in this paper to help evaluate its chemical propulsion performance. Decomposition experiments were carried out with a high-temperature integrated thermal analyzer with heating rates of 5–20 °C/min. Results showed the decomposition process can be divided into four stages by three characteristic temperatures. The mass loss and heat absorption mainly occurred in the second and third stages. The activation energy of decomposition reactions was also obtained. Analyses indicated mechanisms in the first and second stages are multiple-step kinetics. But that of the third and fourth stages can be simplified as single-step kinetics.

The Quantum Yang–Mills Theory

In axiomatic quantum field theory, the postulate of the uniqueness of the vacuum (a pure vacuum state) is independent from the other axioms and equivalent to the cluster decomposition property. The latter, however, implies a Coulomb or Yukawa attenuation of the interactions at growing distances and hence cannot accommodate the confining properties of the strong interaction. Thesolution of the Yang–Mills quantum theory given previously uses an auxiliary field to incorporate Gauss’s law and demonstrates the existence of two separate vacua, the perturbative and the confining vacuum, therefore resulting in a mixed vacuum state, deriving confinement, as well as the related, expected properties of the strong interaction. The existence of multiple vacua is, in fact, expected by the axiomatic, algebraic quantum field theory, via the decomposition of the vacuum state to eigenspaces of the auxiliary field. The general vacuum state is a mixed quantum state, and the cluster decomposition property does not hold. Because of the energy density difference between the two vacua, the physics of the strong interactions does not admit a Lagrangian description. I clarify the above remarks related to the previous solution of the Yang–Mills interaction and conclude with some discussion a criticism of a related mathematical problem and some tentative comments regarding the spin-2 case.

Fermi isospectrality for discrete periodic Schrödinger operators

AbstractLet , where , , are pairwise coprime. Let be the discrete Schrödinger operator, where Δ is the discrete Laplacian on and the potential is Γ‐periodic. We prove three rigidity theorems for discrete periodic Schrödinger operators in any dimension : If at some energy level, Fermi varieties of two real‐valued Γ‐periodic potentials V and Y are the same (this feature is referred to as Fermi isospectrality of V and Y), and Y is a separable function, then V is separable; If two complex‐valued Γ‐periodic potentials V and Y are Fermi isospectral and both and are separable functions, then, up to a constant, lower dimensional decompositions and are Floquet isospectral, ; If a real‐valued Γ‐potential V and the zero potential are Fermi isospectral, then V is zero. In particular, all conclusions in (1), (2) and (3) hold if we replace the assumption “Fermi isospectrality” with a stronger assumption “Floquet isospectrality”.

Stochastic-offset-enhanced restricted slice excitation and 180° refocusing designs with spatially non-linear ΔB0 shim array fields.

Developing a general framework with a novel stochastic offset strategy for the design of optimized RF pulses and time-varying spatially non-linear ΔB0 shim array fields for restricted slice excitation and refocusing with refined magnetization profiles within the intervals of the fixed voxels. Our framework uses the decomposition property of the Bloch equations to enable joint design of RF-pulses and shim array fields for restricted slice excitation and refocusing with auto-differentiation optimization. Bloch simulations are performed independently on orthogonal basis vectors, Mx, My, and Mz, which enables designs for arbitrary initial magnetizations. Requirements for refocusing pulse designs are derived from the extended phase graph formalism obviating time-consuming sub-voxel isochromatic simulations to model the effects of crusher gradients. To refine resultant slice-profiles because of voxelwise optimization functions, we propose an algorithm that stochastically offsets spatial points at which loss is computed during optimization. We first applied our proposed design framework to standard slice-selective excitation and refocusing pulses in the absence of non-linear ΔB0 shim array fields and compared them against pulses designed with Shinnar-Le Roux algorithm. Next, we demonstrated our technique in a simulated setup of fetal brain imaging in pregnancy for restricted-slice excitation and refocusing of the fetal brain. Our proposed framework for optimizing RF pulse and time-varying spatially non-linear ΔB0 shim array fields achieve high fidelity restricted-slice excitation and refocusing for fetal MRI, which could enable zoomed fast-spin-echo-MRI and other applications.

Effects of Coprinus comatus (chicken drumstick mushroom) on the quality characteristics of low nitrite-backfat Cantonese sausages

This study investigated the chemical composition, physicochemical properties, antioxidant activity and volatile compounds of low nitrite-backfat Cantonese sausages, and the antimicrobial effects, protein decomposition, lipid peroxidation and sensory properties were assessed during 7 d of refrigeration. Four independent replications of sausages were produced to compare groups: the Control and four groups with various levels of Coprinus comatus (CC) and backfat (BF) contents added (Sample 1: 50 g/kg CC and 150 g/kg BF; Sample 2: 100 g/kg CC and 100 g/kg BF; Sample 3: 150 g/kg CC and 50 g/kg BF and Sample 4: 200 g/kg CC). The results showed that the inclusion of CC improved (P < 0.05) the protein content (28.88–32.14%), ash content (2.51–3.56%), dietary fiber (0.87–1.65%), b* values (18.65–19.04), antioxidant activity (75–85% in DPPH and 20–25% in ABTS), and volatile compounds (up to 48 types), but reduced (P < 0.05) the cohesiveness (0.41–0.48), chewiness (86.8–47), hardness (5884-1558), and residual nitrite content (<6 mg/kg) of the sausage. There were no significant differences (P > 0.05) between the treatments in terms of moisture, water activity, pH, and springiness of the sausages. Sausages incorporated with C. comatus showed a decrease in microbiological counts, total volatile nitrogen, and thiobarbituric acid reactive substances during 7 d of refrigeration compared to the Control. Sausage formulation with 50% C. comatus and 50% back fat earned the best overall acceptability by considering the sensorial properties.

(Invited) Green Ammonia-Mediated CO2 Capture and Direct Electrochemical Reduction to Formate

Direct electrochemical conversion of CO2 capture solutions (instead of gaseous CO2) into valuable chemicals can circumvent the energy-intensive CO2 regeneration and pressurization steps. While commonly used CO2 capture agents include alkali and amine solutions, ammonia has been rarely investigated. In another aspect, mismanagement of reactive nitrogen (Nr) in waste has emerged as a major problem in water pollution to our ecosystems, causing severe eutrophication and health concerns. Sustainably recovering Nr [such as nitrate (NO3 −)-N] and converting it into green ammonia (NH3) could mitigate the environmental impacts of Nr and reduce the NH3 demand from the carbon-intensive Haber-Bosch process, as well as a possible CO2 capture agent due to its alkaline nature.In this talk, we will present our rencet research on integration of electrodialysis and electrocatalysis for ammonia synthesis from dilute waste Nr sources, and green ammonia-mediated CO2 capture (to ammonium bicarbonate, NH4HCO3) and subsequent reduction to ammonium formate (NH4HCO2) as a new approach to CO2 capture and utilization (CCU). We have demonstrated a record-high NO3 −-to-NH3 performance in a scalable, versatile, and cost-effective membrane-free alkaline electrolyzer (MFAEL): an unprecedented NH3 partial current density of 4.22 ± 0.25 A cm−2 with a faradaic efficiency of 84.5 ± 4.9%. We also discovered that an ammonium bicarbonate (NH4HCO3)-fed electrolyzer with an anion exchange membrane (AEM) outperforms the state-of-the-art KHCO3 electrolyzer with a bipolar membrane (BPM) owing to its favorable thermal decomposition property, which allows for a 3-fold increase in the in situ CO2 concentration, a maximum 23% increase in formate faradaic efficiency, and a 35% reduction in cell voltage by substituting BPM with the AEM. Our integrated process by combining NH4HCO3 electrolysis with CO2 capturing by on-site generated green ammonia from the electro-reduction of nitrate in MFAEL has shown a remarkable 99.8% utilization of CO2 capturing agent. Such a multi-purpose process may offer a sustainable route for the simultaneous removal of Nr wastes and streamlined CO2 capturing and upgrading to valuable chemicals.

Effect of Different Silane Coupling Agents on Properties of Waste Corrugated Paper Fiber/Polylactic Acid Composites.

The surface of plant fibers was modified by silane coupling agents to prepare plant fiber/polylactic acid (PLA) composites, which can improve the dispersion, adhesion, and compatibility between the plant fibers and the PLA matrix. In this work, three silane coupling agents (KH550, KH560, and KH570) with different molecular structures were used to modify the surface of waste corrugated paper fibers (WFs), and dichloromethane was used as the solvent to prepare the WF/PLA composites. The effects of different silane coupling agents on the microstructure, mechanical properties, thermal decomposition, and crystallization properties of the composites were studied. The mechanical properties of the composites treated with 4 wt% KH560 were the best. Silane coupling agents can slightly improve the melting temperature of the composites, and WFs can promote the crystallization of PLA. The modification of WFs by silane coupling agents can increase the decomposition temperature of the WF/PLA composites. The content and type of silane coupling agent directly affected the mechanical properties of the WF/PLA composites. The interfacial compatibility between the WFs and PLA can be improved by using a silane coupling agent, which can further enhance the mechanical properties of WF/PLA composites. This provides a research basis for the further improvement of the performance of plant fiber/PLA composites.

Floquet isospectrality for periodic graph operators

Let Γ=q1Z⊕q2Z⊕⋯⊕qdZ with arbitrary positive integers ql, l=1,2,⋯,d. Let Δdiscrete+V be the discrete Schrödinger operator on Zd, where Δdiscrete is the discrete Laplacian on Zd and the function V:Zd→C is Γ-periodic. We prove two rigidity theorems for discrete periodic Schrödinger operators:(1)If for real-valued Γ-periodic functions V and Y, the operators Δdiscrete+V and Δdiscrete+Y are Floquet isospectral and Y is separable, then V is separable.(2)If for complex-valued Γ-periodic functions V and Y, the operators Δdiscrete+V and Δdiscrete+Y are Floquet isospectral, and both V=⨁j=1rVj and Y=⨁j=1rYj are separable functions, then, up to a constant, lower dimensional decompositions Vj and Yj are Floquet isospectral, j=1,2,⋯,r. Our theorems extend the results of Kappeler. Our approach is developed from the author's recent work on Fermi isospectrality and can be applied to studying more general lattices.

Insights into the Reaction Kinetics of Hydrazine-Based Fuels: A Comprehensive Review of Theoretical and Experimental Methods

While researchers have extensively studied the initial decomposition mechanism of Monomethylhydrazine (MMH, CH3NHNH2) in the MMH/dinitrogen tetroxide (NTO) system, the investigation of Unsymmetrical Dimethylhydrazine (UDMH, (CH3)2NNH2) has been limited due to its high toxicity, corrosiveness, and deterioration rate. Hence, the effects of UDMH’s deterioration products on combustion performance and gas-phase combustion reaction mechanisms remain unclear. This comprehensive review examines the existing research on the reaction kinetics of the three widely used hydrazine-based self-ignition propellants: Hydrazine (HZ, N2H4): MMH: and UDMH, emphasizing the necessity for further investigation into the reaction kinetics and mechanisms of UDMH. It also discusses the implications of these findings for developing safer and more efficient rocket propulsion systems. Additionally, this review underscores the importance of utilizing computational chemistry theory to analyze hydrazine-based fuels’ combustion and decomposition properties, constructing detailed pyrolysis and combustion reaction mechanisms to optimize rocket engine fuel performance and environmental concerns.

Inhibition effect of NH4H2PO4 on explosion flame propagation of aluminum alloy dust cloud

To investigate the inhibitory effect of NH4H2PO4 on the flame propagation of aluminum alloy dust clouds, experiments were conducted in cylindrical vertical ducts. High-speed cameras were employed to capture the explosion flames of aluminum alloy dust clouds under the coupled effect of NH4H2PO4 with different concentrations and particle sizes. The flame propagation behavior of NH4H2PO4/aluminum alloy dust was analyzed, and mathematical models were developed to describe the maximum distance and maximum velocity of NH4H2PO4 inhibition on the flame propagation of aluminum alloy dust clouds. Additionally, the inhibition characteristics of NH4H2PO4 on aluminum alloy dust explosions were studied in a 20 L spherical explosion container, and the thermal decomposition properties of NH4H2PO4 and aluminum alloy particles were investigated using a simultaneous thermal analyzer. Furthermore, the inhibition process of NH4H2PO4 on aluminum alloy dust was explored. The results demonstrate that the concentration of NH4H2PO4 has a greater impact on the inhibition effect on aluminum alloy dust, while the particle size has a smaller influence. Generally, as the concentration of NH4H2PO4 increases, the flame propagation distance and flame development rate decrease, leading to an enhanced inhibitory effect. The addition of NH4H2PO4 slows down the peak pressure of aluminum alloy dust explosions, resulting in a longer duration and smaller peak values of the “double-peak” pressure structure. When the particle size of NH4H2PO4 decreases and the concentration increases, the possibility of the “double-peak” structure decreases, forming a single-peak structure with lower peak values and pressure rise rates. The decomposition temperature of NH4H2PO4 precedes the combustion temperature of aluminum alloy particles. NH4H2PO4 absorbs thermal energy from the reaction system, exerting an inhibitory effect on aluminum alloy dust. The research findings provide valuable references for optimizing explosion suppression parameters and improving powder explosion suppression techniques.

PLS for designed experiments

In many emerging new areas of research, for example in -omics sciences, complex data sets are generated implementing well-designed experiments with the aim to study the effects of factors on responses measured by high-through analytical platforms. The data sets are multivariate in their nature and require suitable data analysis techniques to be investigated. Partial Least Squares (PLS) regression has been developed and successfully applied to solve multivariate regression problems where data are correlated, redundant and noisy, but it is not able to take explicitly into account the experimental design used to generate the data. In this study, we adapt PLS to model data generated by crossed factorial designs. A new method based on constrained PLS2 regression and a type III sums of squares-like approach based on PLS2 are developed to treat orthogonal and non-orthogonal designs, respectively. Post-transformation and Procrustes analysis are applied to discover the 'latent’ structure useful to investigate the relationships between factors and responses. The mathematical properties of the data decomposition, the inference process to assess the reliability of the model and some basic tools for model interpretation are presented and discussed. One simulated and two experimental data sets, one generated implementing an orthogonal design and one obtained by a non-orthogonal design, are investigated to show how the methodology works in practice.

Morphological, physical, chemical, and thermal decomposition properties of air-heat-treated balsa fruit fibers at different temperatures

Morphological, physical, chemical, and thermal decomposition properties of air-heat-treated balsa fruit fibers at different temperatures

The dynamics of rank-maximal and popular matchings

Given a bipartite graph, where the two sets of vertices are applicants and posts and ranks on the edges represent preferences of applicants over posts, a rank-maximal matching is one in which the maximum number of applicants is matched to their rank one posts and subject to this condition, the maximum number of applicants is matched to their rank two posts, and so on. We study the dynamic version of the problem in which a new applicant or post may be added to the graph and we would like to maintain a rank-maximal matching. We show that after the arrival of one vertex, we are always able to update the existing rank-maximal matching in O(min⁡(c′n,n2)+m) time, where n denotes the number of applicants, m the number of edges and c′ the maximum rank of an edge in an optimal solution. The time bound can be considered optimal under the circumstances, as improving it would imply a better running time for the rank-maximal matching problem. Additionally, we update the matching using a minimal number of changes (replacements). All cases of: a deletion of a vertex from the graph, an addition or a deletion of a new edge or even of a change of rank of a given edge can be reduced to the problem of handling the addition of a vertex. As a by-product, we also get an analogous O(m) result for the dynamic version of the (one-sided) popular matching problem.Our results are based on the novel use of the properties of the Edmonds-Gallai decomposition. The presented ideas may find applications in other (dynamic) matching problems, not only related to matching with preferences.

The enhancement of heterobimetallic MOFs on the pyrolysis and laser ignition of FOX-7

The hydrothermal approach had been used to synthesize two new heterobimetallic Metal Organic Frameworks (MOFs), Ba4Pb4(CH3CO2)8[(CH6CO2)4Pb](CH3CO2)4 (PbBa-MOF) and Ba2Ni(CO2H)6(OH2)4 (NiBa-MOF), their structure and surface topography were then examined with XRD and SEM. By using the TG-DSC and TG-FTIR-MS methods, the pyrolytic decomposition properties of MOFs and their catalytic activities on the 1,1-diamino-2,2-dintroethene (FOX-7) pyrolysis were investigated. The PbBa-MOF has a single thermal decomposition process with a high thermal decomposition temperature, while NiBa-MOF has a three-stage thermal decomposition process initiated from a lower temperature. Furthermore, the thermolysis peak temperature of the FOX-7/PbBa-MOF and FOX-7/NiBa-MOF mixture has a great decrease by 24.2 °C and 27.4 °C compared with the FOX-7. However, the low pyrolysis peak temperature and the pyrolysis activation energy (Ea) are almost unchanged. The selective high temperature catalytic effect of the MOFs on FOX-7 results from the activation of -NH2 in the high temperature pyrolytic decomposition of FOX-7 by the metallic ions of the MOFs. This thermal catalytic property indicates that MOFs can promote the pyrolytic decomposition of FOX-7 while ensuring the safety requirements for the compatibility of energetic mixtures in the preparation of propellants. The relationship between the features of pyrolytic decomposition and laser ignition was finally covered and defined. The two MOFs decreased the minimum ignition energy and ignition delay time of the FOX-7. Novel MOFs combustion catalyst may strengthen ignition and combustion features of the high-energy and low-sensitivity solid propellants containing FOX-7.

The complex role of air pollution on the association between greenness and respiratory mortality: Insight from a large cohort, 2009–2020

BackgroundAlthough emerging studies have illuminated the protective association between greenness and respiratory mortality, efforts to quantify the potentially complex role of air pollution in the causal pathway are still limited. We aimed to examine the potential roles of air pollution in the causal pathway between greenness and respiratory mortality in China. MethodsWe used data from a community-based prospective cohort of 654,115 participants in southern China (Jan 2009–Dec 2020). We evaluated the greenness exposure as a three-year moving average Normalized Difference Vegetation Index (NDVI) within the 500 m buffer around the residence. Cox proportional hazards model was applied to estimate the association between greenness and respiratory mortality. Causal mediation analysis combined with a four-way dimensional decomposition method was utilized to simultaneously quantify the interaction and mediation role of air pollution including PM2.5, PM10, or NO2 on the greenness-respiratory mortality relationship. FindingsWe observed 6954 respiratory deaths during 12 years of follow-up. Increasing NDVI level from the lowest to the highest quartile is associated with a 19 % (95%CI: 13–25 %) reduction in the respiratory mortality risk. For the total protective effect, the proportion attributable to the overall negative interaction between greenness and air pollution (PM2.5, PM10, or NO2) was 2.2 % (1.7–3.2 %), 3.5 % (0.4–3.7 %), or 25.0 % (22.8–27.1 %), respectively. Simultaneously, we estimated 25.5 % (20.1–32.0 %), 49.5 % (32.5–71.9 %), or 1.0 % (0.8–1.2 %) of the total protective association was mediated through a reduction in PM2.5, PM10, or NO2, respectively. InterpretationIncreased greenness exposure mitigated respiratory mortality through both the antagonistic interaction and mediation pathway of air pollution (PM2.5, PM10, or NO2).