Decomposition Steps Research Articles

Thermal decomposition mechanism of lithium methyl carbonate in solid electrolyte interphase layer of lithium-ion battery

To predict the early stages of thermal runaway and improve the safety of lithium-ion batteries, it is necessary to examine the elementary reaction steps for the thermal decomposition of individual solid electrolyte interphase (SEI) components. This study elucidates a detailed decomposition mechanism of lithium methyl carbonate (LMC) which is one of SEI components and accounts for the majority of SEI components formed in commercial electrolytes. The detailed reaction mechanism for the thermal decomposition of LMC is proposed based on the in-situ/ex-situ experiments and density functional theory calculations. LMC underwent six reactions before finally converting to Li2CO3 at 300 °C. To supplement the reliability of the proposed reaction mechanism, the actual gas composition measured using mass spectrometry (MS) are compared with the chain reactions of radicals generated through the thermal decomposition reactions, which is calculated using GRI-MECH 3.0, a gas-phase reaction mechanism. The methodology proposed in this study can be used both for analyzing the reaction mechanisms of different SEI components and their coupling effects with the electrolyte in the future. Understanding these reaction mechanism sets will help us to understand the degradation reactions of real complex SEI and the initial self-heating stage during thermal runaway.

Study of using cork powder as an adjuvant bio-flame retardant in acrylonitrile-butadiene-styrene flame retardant formulations

By having a challenging prospect of developing more environmentally friendly flame-retardant (FR) acrylonitrile-butadiene-styrene (ABS) formulations, an initial study related to the effect of combining ammonium polyphosphate (APP) with cork powder (C), a bio-waste of the cork industry on ABS-FR thermal stability and fire performance is proposed and discussed in the present work. ABS composites with a global filler weight content of 30 wt.% were prepared by using a melt-compounding process. Two different types of thermal decomposition behavior, assessed by means of thermogravimetric analysis (TGA), were observed for ABS/C/APP composites. For formulations with C/APP weight ratio < 1, the thermal decomposition of APP polyphosphate network was shifted to lower temperature. On the other hand, when C/APP ratio was ≥ 1, a new thermal decomposition (TD) step related to an earlier thermal decomposition of cork components was registered between 320 °C and 370 °C. Moreover, by means of Fourier-transform infrared spectroscopy (FTIR) analysis of the pyrolysis gasses, a broader temperature range of ammonia and water release was noticed when APP and C were simultaneously incorporated in ABS. In addition, a micro-scale combustion calorimeter (MCC) analysis revealed that replacing APP by cork led to a decrease of the heat release capacity (HRC) and an increase of the residue formation compared to when only APP was present in ABS composite. Furthermore, forced flaming fire characterization of ABS formulations, studied by means of cone calorimetry (CC), revealed that replacing 20 wt.% of APP by cork (ABS/20C/10APP) led to a similar fire performance to the ABS formulation with 30 wt.% of APP (ABS/30APP). A similar trend under horizontal UL-94 was observed, nevertheless, for the composite with cork in its composition no dripping was noticed. Additionally, by only replacing a 3 wt.% of APP (ABS/3C/27APP) by cork an optimum improvement in fire retardancy was achieved, with the highest efficiency in reducing the peak heat release rate (pHRR) of 21 % regarding ABS/30APP. These results have been related to the chemical interaction between APP and cork components in the condensed phase confirmed by the observance of a more intense P-O-C absorbance peak of the CC residue of ABS/3C/27APP, analyzed by means of FTIR. This composite also showed a more cohesive and expanded char layer, observed by scanning electron microscopy (SEM), which acted as a more efficient protective barrier, reducing heat and mass transfer phenomena during combustion which also led to the highest reduction in linear burning rate (LBR) under horizontal UL-94.

Interface reconfiguration of MnCO3/Mn3O4 heterostructure enhances the ozone decomposition in the entire humidity range

The catalytic efficiency of manganese-based catalysts in practical ozone decomposition applications is limited by challenging desorption of intermediate oxygen species and competitive adsorption of H2O molecules in humid environments. In this work, MnCO3/Mn3O4 composites with heterogeneous structures were synthesized through a facile one-step strategy. The obtained MnCO3/Mn3O4-1/2 catalyst exhibited high content of oxygen vacancies, fast electron mobility rate and obvious advantages in catalytic ozone decomposition performance at a space velocity of 600 L g−1 h−1 and 95% RH. In-situ DRIFT spectra indicated that the rate-determining steps for ozone decomposition of MnCO3 and Mn3O4 are the reaction of atomic oxygen with ozone to form O22- and desorption of O22-, respectively. MnCO3/Mn3O4 heterogeneous catalyst undergoes reconfiguration under ozone atmosphere, inducing discontinuous MnOx coatings on the MnCO3 surface, which form a potential difference with Mn3O4. MnCO3/Mn3O4 heterogeneous structure modulates the electronic state of active site, and the synergistic effect of MnCO3 and Mn3O4 improves catalytic performance.

Synthesis, crystal structure analysis, catalytic and biological activities of (H2en)3{V10O28}.6H2O. An improved refinement

The hybrid material, (H2en)3{V10O28}.6H2O (1), containing decavanadate units was synthesized by a wet chemistry method using ethylenediamine (en) as a structure-directing agent. It crystallizes in the monoclinic system, space group C2/c, with cell parameters (Å, °): a = 20.2028 (3), b = 17.0629 (3), c = 10.5541 (2), β= 104.2045 (16). The crystal structure forms a 3D framework of isolated [V10O28]6− monomers, ethylenediammonium cations, and H2O molecules linked through NH···O and OH···O hydrogen bonds. The Fourier transform infrared spectroscopy exhibits characteristic bands corresponding to decavanadate groups and organic molecules. The thermal decomposition steps of the hybrid compound show mainly the loss of the organic moieties and the water molecules. The decavanadate compound's catalytic activity was evaluated by oxidizing methylene blue (MB) with hydrogen peroxide. The biological activity of 1 yielded mediocre results.

A comparative exergoenvironmental assessment of thermochemical copper-chlorine cycles for sustainable hydrogen production

Hydrogen is one of the highly promising clean solutions to address the concerns of energy security in the future given the rapid rate of depletion of naturally occurring hydrocarbon sources. However, it is of immense importance that hydrogen is obtained through sources that ensure sustainability. Thermochemical water-splitting processes are among such routes of hydrogen production that are both sustainable and environmentally benign. Thus, this study focuses on assessing the copper-chlorine thermochemical cycles that are among the more promising cycles of the chlorine family in terms of efficiency and cost-effectiveness. Moreover, this study considers a comparative exergoenvironmental evaluation of the four variants of the copper-chlorine cycle that vary in the number and the nature of steps. A comparison in this regard is carried out between the various steps of each cycle in terms of the component-associated environmental impact rates and environmental impact rates of energy transfer as well as the overall environmental impacts of all cycles. In addition, a comparison of the global warming potential of hydrogen synthesized through utilizing various electricity sources is also performed. Based on our evaluations, hydrolysis and electrolysis are the common steps in the five-step cycle, the four-step cycle, and the three-step cycle configuration 1 yielding the highest component-associated environmental impact rates and environmental impact rates of energy transfer, respectively. Conversely, in the three-step cycle configuration 2, the electrolysis and thermal decomposition steps yield the highest corresponding values, respectively. In addition, the three-step cycle configuration 2 (4,869 mPts/h) and the five-step cycle (3,194 mPts/h) have the highest and the lowest component-associated environmental impact rates, respectively while the five-step (530,694 mPts/h) and the four-step (248,050 mPts/h) cycles result in the highest and the lowest environmental impact rates of energy transfer, respectively.

Thermal, X-ray spectroscopy, morphological, density functional theory and molecular modeling studies on yttrium(III), germanium(IV), tungsten(VI), and silicon penicillinate antibiotic complexes

This manuscript elucidates the thermal stability analysis of four distinct penicillinate complexes, comprising yttrium(III), germanium(IV), tungsten(VI), and silicon, over a temperature ranging from 25 to 800°C. Thermal data revealed the high thermal stability nature of the decomposition steps. According to the spectroscopic measurements, the chemical formula of penicillinate complexes were [Y(Pin)2].Cl.6H2O complex (1), [Ge(Pin)2].2Cl.2H2O complex (2), [W(Pin)2].4Cl complex (3), and [Si(Pin)2].2Cl.2H2O complex (4). The powder XRD pattern revealed crystalline to polycrystalline natures. The synthesized penicillinate complexes were subjected to theoretical calculations utilizing density functional theory (DFT) calculations, employing the lanL2DZ/6-311G++ level of theory. The optimized geometry of each penicillinate complex was discerned, and a comprehensive evaluation of various properties, including the HOMO→LUMO electronic energy gap, molecular electrostatic potential map, and additional physical parameters, was conducted and validated against experimental findings. Molecular docking tool was used to explore the anticancer activity of the synthesized penicillinate complexes in comparison with penicillin potassium drug (Pin). For the computational investigation, two kinases — CSF1R (PDB ID: 7MFC) and MEK2 (PDB ID: 1S9I) associated with breast cancer progression and estrogen-dependent breast cancer were utilized. This comprehensive analysis provides a deeper understanding of the synthesized penicillinate complexes and their potential applications. KEY WORDS: Penicillinate complexes, TGA-DrTGA, TEM, XRD, DFT/TD-DFT, Molecular docking Bull. Chem. Soc. Ethiop. 2024, 38(4), 973-988. DOI: https://dx.doi.org/10.4314/bcse.v38i4.13

A Eulerian Monte Carlo method for the numerical solution of the multivariate population balance equation

Statistical descriptions of particulate phases and granular media based on the notion of a property distribution are particularly advantageous for dense, many-particle dispersions since they support the direct evaluation of Eulerian property statistics, permit a kinematically simple treatment of particle collisions and feature a model complexity that is independent of the number of physical particles. On the minus side, the property distribution is governed by a high-dimensional population balance equation (PBE) whose moment reduction is accompanied by a challenging closure problem and engenders intricate dynamical nonlinearities. Circumventing both the curse of dimensionality and the moment closure problem, we present a Eulerian Monte Carlo (EMC) solution method that harnesses a representation of the property distribution in terms of an ensemble of property samples and is based on a statistical enforcement of the spatially and temporally discretized PBE. After application of a kinetic finite volume scheme, the PBE is subjected to a fractional steps decomposition that separates spatial transport from transport in property space. Conceptually, spatial transport is emulated by assembling the ensemble in one spatial grid cell from samples drawn from the ensembles in neighbouring cells at the previous time point. In this regard, we propose a two-level sampling scheme that is sensitive to large-scale features of the marginal velocity distribution and effectively reduces the instantaneous sampling error. The property transport step, by contrast, is based on the method of characteristics and involves the propagation of individual samples as property characteristics in time. While the sampling error afflicting the property statistics needs to be controlled using a top-level time or ensemble averaging, the EMC method remains well-conditioned for an arbitrary number of samples, is easy to implement and involves a computational expense that scales only linearly with the number of particle properties. Based on two benchmark examples, we analyze the spatial and statistical convergence properties of the EMC method and demonstrate its capacity to capture multiple crossings of particle trajectories. A third example involves the two-way coupled transport of size-polydispersed inertial particles in an inhomogeneous flow field.

New penta-Coordinated Cadmium(II) Complexes: Synthesis, Characterization, Thermal, Antimicrobial, Antioxidant and Cytotoxicity Properties.

In this paper, a new tridentate Schiff base ligand (L) with nitrogen donor atoms and its cadmium(II) complexes with the general formula of CdLX2 (X=Cl-, Br-, I-, SCN-, N3 -, NO3 -) have been synthesized and characterized by physical and spectral (FT/IR, UV-Vis, Mass, and 1H, 13C NMR spectroscopies) methods. Also nano-structured cadmium chloride and bromide complexes were synthesized by sonochemical method and then used to prepare nanostructured cadmium oxide confirmed by XRD and SEM techniques. Thermal behavior of the compounds was studied in the temperature range of 25 to 900 °C under N2 atmosphere at a heating rate of 20 °C/ min. Moreover, thermo-kinetic activation parameters of thermal decomposition steps were calculated according to the Coats-Redfern relationship. Antimicrobial activities of the synthesized compounds against two gram-positive and two gram-negative bacteria such as Bacillus subtilis, Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, and two fungi of Candida albicans and Aspergillus niger were investigated by well diffusion method. SEM technique was used to monitor the morphological changes of the bacteria treated with the compounds. The 2,2-Diphenyl-1-picrylhydrazyl(DPPH) and the ferric reducing antioxidant power (FRAP) methods were used to evaluate the antioxidant ability of the ligand and its cadmium(II) complexes. In final, the cytotoxicity properties of the ligand and some cadmium(II) complexes against PC3 cancer cells were evaluated by MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide) bioassay and nitric oxide (NO) level measurement. The morphological changes of prostate cancer (PC3) cells due to treatment with the ligand and its complexes confirmed their anticancer effectiveness.

Modification of amino functionalized silica nanoparticles with L-proline and furanacrylic acid as novel composites for the efficient removal of methyl orange

The present study deals with the preparation of new composites in which L-proline (LP) and furnacrylic acid (FA) have been grafted on surface of amino functionalized silica nanoparticles (AFS). At first, AFS were prepared by sol-gel approach using tetraethoxysilane (TEOS) as silica source and aminopropyltriethoxysilane (APTES) as silica modifiers. Taking the advantage of amino group on AFS surface, LP and FA were easily grafted on silica surface to obtain LP grafted silica (AFS-LP) and FA grafted silica (AFS-FA) nanocomposites by post modification approach. As prepared composites were characterized by FTIR, SEM, XRD and TGA. The evidence of LP and FA on AFS was elucidated from the FTIR bands found at 1650–1698 cm−1 related to carbonyl group CO) of amide. Additionally, peaks observed at 2965 cm−1 (C-H stretching) of propyl groups and at 1050 cm−1 (Si-O-Si) indicated that the backbone of the material is preserved as silica. The micro images of SEM depicted that the AFS are spherical in shape and have more degree of monodispersivity whereas the SEM images of composites (AFS-LP and AFS-FA) have larger particle size and less degree of monodispersivity. Likewise, XRD peaks at 2θ (∼12°) revealed the mesoporosity of silica as well as hybrid silica and further depression in this peak in case of AFS-LP and AFS-FA depicted the existence of organic moieties on silica. TGA analysis depicted three decomposition steps (high weight loss) in case of AFS-LP and AFS-FA in contrast to two decomposition steps observed in case of AFS. The higher weight loss observed in the case of hybrid composites depicted the grafting of organic molecules on AFS. The prepared composites AFS-LP and AFS-FA were deployed to investigate their adsorption capacity to remove methyl orange (MO) from aqueous media. Experiments revealed that the composites have high adsorption capacity in acidic media (pH=2) with % removal of 85.05 % for AFS-LP and 81.70 % for AFS-FA. The experimental data was evaluated for adsorption isotherms and value of correlation factor (R2) was close to unity in case of Freundlich representing that the adsorption follows Freundlich isotherm. The data was also evaluated for kinetic models and higher values of R2 as well as closeness of experimental and calculated values of Qe predicted that adsorption of MO followed pseudo-second order kinetic model.

CVT grown CuSe single crystals: Unveiling photodetection advancements and thermoelectric promise

Over the past few decades, transition metal chalcogenides garnered global recognition for their noteworthy contributions to the modeling and engineering of electronic, optoelectronic, and thermoelectric devices to improve overall device performance. In the current investigation, the first ever growth of CuSe single crystals is achieved utilizing the chemical vapor transport technique with iodine serving as a transporting medium. The ascertainment of the hexagonal unit cell configuration in the grown CuSe crystals with the P63/mmc space group is substantiated via powder X-ray diffraction examination. The micro-surface characteristics exhibited planar facets outlined by layer boundaries, signifying crystal development through a mechanism reliant on layer growth. The direct optical bandgap of 1⋅64 eV for CuSe single crystals is unveiled by optical reflectance spectrum, demonstrating its aptitude for incorporation into photodetectors. The Raman spectrum manifested a prominent peak at 259 cm−1, aligning to Ag1 vibrational mode. The exploration of temperature-induced fluctuations in the power factor and figure of merit unveiled a progressive increase with rising temperatures. The optimal ZT parameter for the CuSe single crystals attains 0⋅058 at 523 K. The thermogravimetric patterns of CuSe single crystals exhibited singular step decomposition, exemplified by an average weight reduction of 25⋅49 % across the temperature spectrum from ambient to 813 K. The current−voltage (I–V) features of the fabricated CuSe single crystal photodetector are assessed under biasing voltage set at 20 mV at ambient temperature. Under a bias voltage of 20 mV and a polychromatic light intensity of 50 mW/cm2, the achieved responsivity is 4335⋅57 μA/W and a detectivity of 135 × 106 Jones. The photoresponse and thermoelectric examination of CuSe crystals alludes to their potential utility in innovative applications on the horizon.

Synthesis and characterization of NiFe2 O4 nanoparticles by tartaric acid assisted sol-gel auto-combustion method

Nickel ferrite nanoparticles were synthesized by modified sol-gel auto-combustion method. The final product obtained was annealed at 600 °C. The thermal, structural, morphological, vibrational, optical and magnetic properties were studied using TGA, XRD, SEM, FTIR, UV-DRS and VSM techniques, respectively. The thermo gravimetric analysis shows three step decomposition of residual nitrate and tartrate complexes with a total weight loss of 6.69% below 600 °C. Further, there was no significant weight loss above 600 °C. XRD confirmed the spinel cubic phase with Fd3m space group. The average crystallite size was 14 nm. An agglomerated random morphology with porous flake like microstructure was observed. The vibrational analysis confirmed the presence of Ni-O, Fe-O stretching vibrational modes in the wave number range 400-600 cm−1. Tetrahedral site (kTd) and octahedral site (kOh) force constant values were 2.20×105 and 1.31×105 dynes/cm, respectively. From UV-DRS spectra, the Kubelka-Munk function was used to calculate the optical band gap and it was 1.71 eV. The magnetic saturation, retentivity and coercive field values: Ms = 22.35 emu/gm, Mr = 5.20 emu/gm, Hc = 165 Gauss were obtained from VSM analysis. The calculated magnetic moment value was 1.115 μB. The law of approach to saturation was employed to analyze the VSM data in saturation region. The calculated magneto-crystalline anisotropy constant, K1 value was 0.857×105 erg/cc.

Facile synthesis of lanthanum carbonate octahydrate and lanthanum oxide nanoparticles by sonochemical method: systematic characterizations

Abstract This study could present the size and morphology of two synthesized nanoparticles (NPs) by observing their smallest possible dimensions. Lanthanum carbonate nanoparticles were synthesized by sonochemical method through the interaction of lanthanum acetate hydrate and sodium carbonate in an aqueous medium with a probe sonicator. After rigorous washing followed by drying, the La2(CO3)3·8H2O(S1) NPs were calcined at a temperature of 600 °C to obtain lanthanum oxide nanoparticles (S2). Both NPs were characterised through various instrumental techniques. PXRD study showed orthorhombic with space group of Pccn (56) and hexagonal phases with space group of P 3 ‾ m 1 $P\overline{3}m1$ (164) for S1 and S2 respectively whose morphology and elemental analysis were studied through FESEM and EDX. High resolution TEM image of La2(CO3)3·8H2O and La2O3 showed spherical shapes of the nanoparticles. Further study of XPS and FTIR conveyed detailed information of both nanoparticles whose TGA-DSC showed three step decomposition curves. The size and morphology of the synthesized nanoparticles have been found to have a distinct morphology and are found comparatively smaller in size than those observed in the earlier reported works (Table 1 Table 1: Comparative study of synthesized lanthanum carbonate and lanthanum oxide NPs with various techniques applied by other researchers. Sl. no. Name of NPs Methods Conditions Size of NP Reference 1 La2(CO3)3·8H2O Sonochemical method Time: 25 min XRD: Pccn (56) a = 8.9840 Å b = 9.5800 Å c = 17.0000 Å This work Temperature: 301 K Size: 24.102 nm Starting materials:(a) La(CH3COO)2: 0.050 M(b) Na2CO3:0.050 M TEM: Size: 4–30 nm La2(CO3)3 Reverse micelles Time: 1 h XRD: Size: nanoparticles absent [20] Temperature: 303 K Starting materials:(a) Triton X-100(b) Cyclohexane(c) n-butylalcohol(d) La(NO3)3(aq) e) NaCO3(aq) La2(CO3)3·8H2O Hydrothermal Time: 2–5 days XRD: Pccn a = 8.984 Å b = 9.580 Å c = 17.00 Å [21] Temperature: 773 K Size: nanoparticles absent Prepared by slow hydrolysis of La(CCl3COO)3 La2(CO3)3·1.4H2O Hydrothermal Time: 1 h 30 min Structure unknown [22] Temperature: 368 K Starting material:(a) La2O3 (b) HNO3 (c) Urea La2(CO3)3·1.7H2O Sonochemical Time: 30 min XRD: a = 8.990 Å c = 9.675 Å [23] Temperature: not specified Size: not specified (a) La(OAC)3 (b) Na2CO3 TEM: Size: 25–35 nm Concentration:(a) La(OAC)3: 0.051 M(b) Na2CO3: 0.251 M La2(CO3)3·5H2O Hydrothermal Time: XRD: Pbca a = 9.0167 Å b = 12.842 Å c = 9.6331 Å [24] Temperature: Size: not specified Starting materials:(a) La2O3 (b) HCl(c) Na2CO3 La2(CO3)3·3.4H2O Hydrothermal Time: 3–4 h XRD: P21212 a = 9.57 Å b = 12.65 Å c = 8.94 Å [25] Temperature: 298–308 K Size: not specified Starting materials:(a) LaCl3 (b) NH4HCO3 2 La2O3 Thermal decomposition Time: 2 h P3m1 a = 3.973 Å b = 3.9373 Å c = 6.129 Å [26] Temperature: 1073 K Size: 15 nm Starting material: La(OH)3 nanorods TEM: Size: 23 nm La2O3 Thermal decomposition Time: 2 h XRD: a = 11.347 Å [23] Temperature: 873 K Size: 30 nm Starting material:La2(CO3)3·1.7H2O TEM: Size: 30 nm La2O3 Thermal decomposition Time: not specified Not specified [27] Temperature: 1198 K Starting material:(a) La(NO3)3·9H2O(b) NH4HCO3 La2O3 Thermal decomposition Time: 4 h Not specified [28] Temperature: 1073 K Starting material: La(OH)3 La2O3 Thermal decomposition Time: 2 h P 3 ‾ m 1 $P\overline{3}m1$ a = 3.973 Å b = 3.9373 Å c = 6.129 Å This work Temperature: 873 K XRD: Size: 43.26 nm Starting material: La2(CO3)3·8H2O TEM: Size: 17–34 nm ).

Insights into the adsorption and decomposition mechanisms of tar typical model compounds (benzene, toluene and phenol) on Ni(111) surface by DFT calculations

Studying the adsorption and decomposition of tar-typical model compounds on nickel surfaces is necessary to guide catalyst design. This study investigates the adsorption and decomposition mechanisms of three typical tar model compounds (benzene-benzene ring without branched chain, toluene-benzene ring with methyl group and phenol-benzene ring with hydroxyl group) on the Ni(111) surface using density functional theory calculations. The results showed that the most stable adsorption site was Bridge0 for benzene and Bridge0-F for toluene and phenol. The adsorption energies were −0.89 eV, −0.76 eV and −0.71 eV, respectively. During decomposition, benzene will first be dehydrogenated (energy barrier of 1.57 eV) and the benzene ring will be opened after the removal of the first H atom (2.10 eV). The rate-limiting step in benzene decomposition is the first dehydrogenation step (1.57 eV). Toluene decomposes like phenol by dehydrogenating functional groups before breaking the benzene ring. The rate-limiting step in the decomposition of toluene is the ring opening of the benzene ring (1.67 eV). The dehydrogenation of the benzene ring is the rate-limiting step in the decomposition of phenol (1.74 eV). This occurs after the removal of the hydrogen atom from the hydroxyl group.

Thermal behaviors and Decomposition Mechanism of PNIMMO with CL-20

To investigate the thermal decomposition mechanism between Poly(3-nitratomethyl-3- methyloxetane) (PNIMMO) and 2, 4, 6, 8, 10, 12-Hexanitrohexaazaisowurtzitane (CL-20), the thermal decomposition of PNIMMO, CL-20 and PNIMMO+CL-20 mixture under different conditions was studied using differential scanning calorimetry (DSC), thermogravimetric-differential scanning calorimetry-mass spectra-fourier transform infrared spectrometer (TG-DSC-MS/FTIR) and in-situ FTIR experiments. As a result, the exothermic peak temperature of the PNIMMO+CL-20 mixture shifts to lower values under both closed and open circumstances compared to CL-20. Different kinetic parameters and models were obtained for the three decomposition steps in the mixture. The first step follows the random chain scission model (L2) at α<0.5, and the phase boundary controlled reaction model (R3) at α>0.5. The second/third step is between the random chain scission model (L2) and the first-order reaction model (F1) at α<0.5, and conforms to the first-order reaction model (F1) at α>0.5. Thus, the decomposition of PNIMMO controls the initial speed, while the removal of the nitro group in CL-20 controls the later step. Combined with the analysis of gas products and condensed phase, PNIMMO speeds up the N—NO2 bond breaking in CL-20 but doesn’t alter its initial breakdown route.

Toward Direct Regeneration of Spent Lithium-Ion Batteries: A Next-Generation Recycling Method.

The popularity of portable electronic devices and electric vehicles has led to the drastically increasing consumption of lithium-ion batteries recently, raising concerns about the disposal and recycling of spent lithium-ion batteries. However, the recycling rate of lithium-ion batteries worldwide at present is extremely low. Many factors limit the promotion of the battery recycling rate: outdated recycling technology is the most critical one. Existing metallurgy-based recycling methods rely on continuous decomposition and extraction steps with high-temperature roasting/acid leaching processes and many chemical reagents. These methods are tedious with worse economic feasibility, and the recycling products are mostly alloys or salts, which can only be used as precursors. To simplify the process and improve the economic benefits, novel recycling methods are in urgent demand, and direct recycling/regeneration is therefore proposed as a next-generation method. Herein, a comprehensive review of the origin, current status, and prospect of direct recycling methods is provided. We have systematically analyzed current recycling methods and summarized their limitations, pointing out the necessity of developing direct recycling methods. A detailed analysis for discussions of the advantages, limitations, and obstacles is conducted. Guidance for future direct recycling methods toward large-scale industrialization as well as green and efficient recycling systems is also provided.

Enhanced N2O decomposition on Rh/ZrO2 catalysts through the promotional effect of palladium

Supported rhodium oxide (RhOx) catalysts have emerged as highly promising for effectively catalytic decomposition of N2O, hence contributing to the mitigation of greenhouse gas emission and combating global warming. Supported RhOx catalysts outperform catalysts employing zeolites and composite metal oxides even under challenging conditions involving O2, H2O, and CO2. This study explores the augmentation of Rh/ZrO2 (RhOx supported on monoclinic ZrO2) catalyst efficiency through the addition of palladium (Pd) to yield RhPd/ZrO2. The augmented catalyst demonstrates notable improvements in N2O decomposition under both N2O-only and more realistic conditions (N2O + O2 + H2O + CO2). Various techniques, including high-angle annular dark-field scanning transmission electron microscopy and X-ray absorption spectroscopy, were employed to investigate the structural characteristics of Rh and Pd species on ZrO2. Kinetic studies further delved into the promotional effect, revealing that the introduction of Pd enhanced the catalytic activity of RhOx catalysts by augmenting their thermal reduction capability. This enhancement proved beneficial in facilitating the efficient progression of the rate-determining step for N2O catalytic decomposition, namely the thermal reduction of the catalyst to produce gaseous O2, particularly at low temperatures. These results highlight the potential of Pd-mediated improvements in Rh/ZrO2 catalysts for sustainable and efficient N2O decomposition.

Time-shifted expression of acetoclastic and methylotrophic methanogenesis by a single Methanosarcina genomospecies predominates the methanogen dynamics in Philippine rice field soil

BackgroundThe final step in the anaerobic decomposition of biopolymers is methanogenesis. Rice field soils are a major anthropogenic source of methane, with straw commonly used as a fertilizer in rice farming. Here, we aimed to decipher the structural and functional responses of the methanogenic community to rice straw addition during an extended anoxic incubation (120 days) of Philippine paddy soil. The research combined process measurements, quantitative real-time PCR and RT-PCR of particular biomarkers (16S rRNA, mcrA), and meta-omics (environmental genomics and transcriptomics).ResultsThe analysis methods collectively revealed two major bacterial and methanogenic activity phases: early (days 7 to 21) and late (days 28 to 60) community responses, separated by a significant transient decline in microbial gene and transcript abundances and CH4 production rate. The two methanogenic activity phases corresponded to the greatest rRNA and mRNA abundances of the Methanosarcinaceae but differed in the methanogenic pathways expressed. While three genetically distinct Methanosarcina populations contributed to acetoclastic methanogenesis during the early activity phase, the late activity phase was defined by methylotrophic methanogenesis performed by a single Methanosarcina genomospecies. Closely related to Methanosarcina sp. MSH10X1, mapping of environmental transcripts onto metagenome-assembled genomes (MAGs) and population-specific reference genomes revealed this genomospecies as the key player in acetoclastic and methylotrophic methanogenesis. The anaerobic food web was driven by a complex bacterial community, with Geobacteraceae and Peptococcaceae being putative candidates for a functional interplay with Methanosarcina. Members of the Methanocellaceae were the key players in hydrogenotrophic methanogenesis, while the acetoclastic activity of Methanotrichaceae members was detectable only during the very late community response.ConclusionsThe predominant but time-shifted expression of acetoclastic and methylotrophic methanogenesis by a single Methanosarcina genomospecies represents a novel finding that expands our hitherto knowledge of the methanogenic pathways being highly expressed in paddy soils.7k5euw-hvBknz_jds4sXXfVideo

Insights into oxidant matching with green gas generator 5-aminotetrazole from aspects of thermal decomposition behavior, kinetics and combustion mechanism

The green gas generator 5-aminotetrazole (5-AT) is widely applied as an energetic material due to its exceptional characteristics. To investigate the impact of oxidants on the decomposition performance of 5-AT, we prepared three samples using three different oxidants (Sr(NO3)2, KNO3, and KClO4) along with 5-AT under the principle of zero oxygen balance. Then, thermal behavior of the three samples was examined using TG-DTA and TG-FTIR, and their activation energies for each reaction stage were calculated using iso-conversional methods. Results show that the decomposition of these samples occurs in multiple reaction stages and all oxidants, particularly KNO3, facilitate the thermal decomposition of 5-AT. Furthermore, the detailed decomposition mechanism of 5-AT with oxidants was speculated, including that there are two simultaneous ring-opening paths in the first thermal decomposition step of each 5-AT isomer. Eventually, this research can give a meaningful instruction to the formulation design of gas-generation propellant with fewer restrictions in their application.

Synthetic Simulation of Spatially‐Correlated Streamflows: Weighted‐Modified Fractional Gaussian Noise

AbstractStochastic methods have been typically used for the design and operations of hydraulic infrastructure. They allow decision makers to evaluate existing or new infrastructure under different possible scenarios, giving them the flexibility and tools needed in decision making. In this paper, we present a novel stochastic streamflow simulation approach able to replicate both temporal and spatial dependencies from the original data in a multi‐site basin context. The proposed model is a multi‐site extension of the modified Fractional Gaussian Noise (mFGN) model which is well‐known to be efficient to maintain periodic correlation for several time lags, but presents shortcomings in preserving the spatial correlation. Our method, called Weighted‐mFGN (WmFGN), incorporates spatial dependency into streamflows simulated with mFGN by relying on the Cholesky decomposition of the spatial correlation matrix of the historical streamflow records. As the order in which the decomposition steps are performed (temporal then spatial, or vice‐versa) affects the performance in terms of preserving the temporal and spatial correlation, our method searches for an optimal convex combination of the resulting correlation matrices. The result is a Pareto‐curve that indicates the optimal weights of the convex combination depending on the importance given by the user to spatial and temporal correlations. The model is applied to a number of river basins in Chile, where the results show that the WmFGN approach maintains the qualities of the single‐site mFGN, while significantly improving spatial correlation.

SSANet: normal-mode interference spectrum extraction via SSA algorithm-unrolled neural network

In ocean acoustic fields, extracting the normal-mode interference spectrum (NMIS) from the received sound intensity spectrum (SIS) plays an important role in waveguide-invariant estimation and underwater source ranging. However, the received SIS often has a low signal-to-noise ratio (SNR) owing to ocean ambient noise and the limitations of the received equipment. This can lead to significant performance degradation for the traditional methods of extracting NMIS at low SNR conditions. To address this issue, a new deep neural network model called SSANet is proposed to obtain NMIS based on unrolling the traditional singular spectrum analysis (SSA) algorithm. First, the steps of embedding and singular value decomposition (SVD) in SSA is achieved by the convolutional network. Second, the grouping step of the SSA is simulated using the matrix multiply weight layer, ReLU layer, point multiply weight layer and matrix multiply weight layer. Third, the diagonal averaging step was implemented using a fully connected network. Simulation results in canonical ocean waveguide environments demonstrate that SSANet outperforms other traditional methods such as Fourier transform (FT), multiple signal classification (MUSIC), and SSA in terms of root mean square error, mean absolute error, and extraction performance.