Decomposition Of Layers Research Articles

Thermal Decomposition Kinetics of Clinochlore at High Temperature and Its Implications

Abstract The dehydration kinetics of clinochlore were performed using a non-isothermal thermogravimetric analysis under a dynamic nitrogen atmosphere at ambient pressure. Clinochlore, with a grain size of 5–10 μm, was analyzed using heating rates of 2, 5, 10, 20, and 40 K/min at temperatures of up to 1260 K. Thermogravimetric data of clinochlore at different heating rates were modeled using the Kissinger method, Flynn-Wall-Ozawa method, and Coats-Redfern method. The dehydration of clinochlore is ascribed to the decomposition of brucite and talc layers. The dehydration temperature of the brucite layer is 730–920 K, which corresponds to a two-dimensional phase boundary model (R2) with an activation energy of 214.94 ± 7.79 kJ/mol and a pre-exponential factor of 12.52 ± 0.62 min−1. The dehydration temperature of the talc-like layer is 960–1140 K, which follows a two-dimensional diffusion model with an apparent activation energy of 419.49 ± 23.62 kJ/mol and a pre-exponential factor of 19.97 ± 1.76 min−1. Combined with the parameters obtained in this study, the fast dehydration of clinochlore can trigger earthquakes in the subduction zone.

Removing boron from the diamond wire saw silicon powder by MgF2-sintering synergized with Na2CO3-enhanced refining to prepare low-boron silicon

Recycling environmentally hazardous diamond wire saw silicon powder (DWSSP) to prepare low-boron silicon is crucial for environmental pollution and waste resources recycling. For reutilization, the decomposition of impurity-containing SiO2 layers and the removal of boron are the two main issues that need to be addressed. Therefore, the addition of MgF2 to DWSSP for sintering to damage the containing-impurities SiO2 layers and remove harmful boron was first studied. The results showed the SiO2 layer was effectively decomposed by reaction with MgF2 and the removal rate of harmful boron impurity was 86.9 % at 1300 °C for 120 min with 20 % MgF2 addition. Subsequently, the effect of Na2CO3 on the removal of boron impurity in the refining process was analyzed, finding that 10 % Na2CO3 addition enhanced the boron removal rate to 95.6 % at 1600 °C for 60 min with CaO/SiO2 ratio of 1.2. Finally, the removal mechanism of harmful B impurities via MgF2-sintering synergized with Na2CO3-enhanced refining was analyzed. This work provides a simple and feasible alternative for recycling DWSSP to prepare low-boron silicon as feedstock for solar-grade silicon preparation.

Processing of PtSe2 ultra-thin layers using Ar plasma

This paper contains a detailed analysis of the Ar plasma treatment dynamics of the PtSe2/Al2O3 system comprising ultrathin PtSe2 layers with a thickness of 1–3 monomolecular layers. The impact of the etching process on the physical properties of the ultrathin PtSe2 layers was analysed using Raman spectroscopy and atomic force microscopy techniques in time intervals up to the complete decomposition of the PtSe2 layers. The processing duration that allowed the complete removal of the PtSe2 layer was determined for the investigated systems. The results, in combination with the optimised photolithography, were used for the active PtSe2 channel formation in the 3 ML PtSe2-based transfer line measurement structure using electrodes consisting of Ni and Au layers (with thicknesses of 20 and 40 nm, respectively). The electrical properties of the fabricated system confirm the effectiveness of commercially available PtSe2/Al2O3 samples in the fabrication of simple electronic devices utilising planar architecture, i.e. micro- and nanosensors.

Warming promotes the decomposition of oligotrophic bacterial-driven organic matter in paddy soil

The ongoing global warming is causing paddy soil to come under threat by hitherto unseen levels of carbon and nitrogen loss. The mechanism of soil organic matter (SOM) components and microbial metabolism responding to increased temperature is complicated; for example, the temperature sensitivity (Q10) of SOM decomposition in rice topsoil and subsoil remains poorly understood. In this study, 0–30 cm columns of undisturbed paddy soil were collected and incubated at 5, 15, or 25 °C for 117 days to investigate the effect of temperature on SOM decomposition and microbial characteristics in different soil layers. Results showed that Q10 of subsoil (15–30 cm) was more than twice that of topsoil (0–15 cm), indicating that SOM mineralisation in subsoil was facilitated more by temperature than that in topsoil. Warming promoted the decomposition of recalcitrant SOM and reduced the fluorescent intensity of dissolved organic matter. Increased temperature exerted no significant effect on microbial biomass, but it did enhance the relative abundance of oligotrophic bacteria and promote anabolism. Therefore, recalcitrant SOM decomposition driven by oligotrophic bacteria was more sensitive to warming than labile organic matter consumption mediated by copiotrophic bacteria. Our findings revealed the underlying mechanisms by which elevating temperature promoted SOM mineralisation, thereby emphasising the need to remain vigilant regarding the threat to carbon dynamics in deep soil poised by global climate changes.

Understanding the Surface Regeneration and Reactivity of Garnet Solid-State Electrolytes.

Garnet solid-electrolyte-based Li-metal batteries can be used in energy storage devices with high energy densities and thermal stability. However, the tendency of garnets to form lithium hydroxide and carbonate on the surface in an ambient atmosphere poses significant processing challenges. In this work, the decomposition of surface layers under various gas environments is studied by using two surface-sensitive techniques, near-ambient-pressure X-ray photoelectron spectroscopy and grazing incidence X-ray diffraction. It is found that heating to 500 °C under an oxygen atmosphere (of 1 mbar and above) leads to a clean garnet surface, whereas low oxygen partial pressures (i.e., in argon or vacuum) lead to additional graphitic carbon deposits. The clean surface of garnets reacts directly with moisture and carbon dioxide below 400 and 500 °C, respectively. This suggests that additional CO2 concentration controls are needed for the handling of garnets. By heating under O2 along with avoiding H2O and CO2, symmetric cells with less than 10 Ωcm2 interface resistance are prepared without the use of any interlayers; plating currents of >1 mA cm-2 without dendrite initiation are demonstrated.

Metal oxide charge transport layer targeting efficient and stable perovskite light-emitting diodes

The charge transport layer is a critical functional component in perovskite light emitting-didoes (PeLEDs). Metal oxide semiconductors (MOSs) are attractive charge transport materials owing to their advantages of robust stability, high carrier mobility, high transparency, as well as low cost. However, because of the complex mutual chemistry disturbance between the metal oxide and luminescent halide perovskites, there are severe charge quenching and even decomposition of the perovskite layers. Therefore, the advance of MOSs as charge transport layers in PeLEDs is still confined within selective cases. It is a prerequisite to gain depth insight into the interfacial contact between perovskites and MOSs from surface chemistry reactions and charge quenching before the realization of MOSs charge transport layers for constructing efficient and stable PeLEDs. In this review, we started with a brief introduction to perovskite materials and the development of PeLEDs. Then, we highlighted the importance of the interfacial contacts between perovskite and charge transport layers, followed by summarizing the progress of PeLEDs using MOSs as charge transport layers from the aspects of surface reaction, crystallization, quenching mechanism, charge injection, and operational stability. We also proposed possible research directions on engineering MOSs charge transport layers that would further improve the performance of PeLEDs.

Effects of phosphorus addition on leaf litter decomposition in two tropical tree plantations in Thailand

There is a widespread belief that organic matter decomposition in phosphorus (P)-poor tropical forests is limited by P shortage and stimulated by exogenous P addition. An incubation experiment was performed to test the effect of P addition on decomposition of litter layers taken from two tropical tree plantations. The result was compared with our earlier soil incubation experiment in the same region. Contrary to the traditional view, we found no significant effects of P addition on the litter layer decomposition, which was also in contrast with our previous soil incubation experiment that showed stimulatory effects of P addition on soil microbial respiration. The difference between our two experiments was attributed to the role of added P to release organic matter from the sorption sites on mineral soils, which made the adsorbed organic matter in soil accessible for microbes and easier to be decomposed. Overall, our incubation experiments did not support the P-limitation hypothesis: organic matter decomposition in P-poor tropical forests is limited by P shortage.

Velocity spectra and scale decomposition of adverse pressure gradient turbulent boundary layers considering history effects

Experiments at relatively large Reynolds number were conducted to better understand the influence of an adverse pressure gradient on the turbulence in two-dimensional boundary layer flows. One focus is on documenting the scale contributions to the Reynolds normal and shear stress profiles under the influence of a positive streamwise pressure gradient. Toward these aims, velocity spectra at friction Reynolds numbers (7100≤Reτ≤8600) are presented, analyzed, and compared to a zero pressure gradient case from the same facility at nominally matching Reynolds number. Distance-from-the-wall scaling is central to numerous theoretical and modeling considerations of the canonical flat plate flow. Consistently, the present spectral measurements reveal clear evidence for its preservation on the inertial sublayer under modest adverse pressure gradients. Increases are seen in the viscous-scaled premultiplied spectra in the outer region as the pressure gradient increases — commensurate with the increases observed in the outer peaks of the streamwise and wall-normal velocity variances, as well as the Reynolds shear stress. Effects of varying Reτ on the streamwise and wall-normal velocity variances and the Reynolds shear stress are studied by comparing the present data at varying Clauser pressure gradient parameter, β, with previous experiments having similarly varying β at significantly lower Reτ (≈1900). This allows to study the effects of changing Reynolds number at matched β. Cases at similar β and Reynolds number, but with varying flow history are also examined, wherein the same β value is arrived either by starting from a smaller or larger initial β. The effects of β>0 on the large and small scale motions are investigated by segregating the signal contributions according to a cut-off wavelength established in previous zero pressure gradient flows. Under a normalization that uses a hybrid velocity scale this analysis reveals similarity between the outer regions of the spectrally-decomposed variances and Reynolds shear stress. These analyses also reveal a more dramatic reduction in the near-wall large scale contribution to the Reynolds shear stress gradient in the β>0 flow when compared to the β=0 flow.

Reference architecture for digital twin-based predictive maintenance systems

ContextDigital Twin-based predictive maintenance systems are frequently integrated into complex systems. The success of the integration depends on the design of the system. A Reference Architecture can be used as a blueprint to design Application Architectures rapidly and consistently for various application domains, resulting in a reduced time-to-market. ObjectiveThe main objective of this study is to develop and evaluate a Reference Architecture designed using renowned software architecture methods. MethodA domain analysis was performed to gather and synthesize the literature on Digital Twin-based predictive maintenance systems, which we used to model the key features. We applied UML diagrams to design the reference architecture based on the feature model. We evaluated the reference architecture using three case studies. ResultsWe derived three views for Digital Twin-based predictive maintenance systems. For the user's view, we developed a context diagram. We developed a package diagram for the structural view, and we designed a layered view to show the system's decomposition in layers. We designed an Application Architecture for each case study based on the study's features using each Reference Architecture view. Additionally, we designed a deployment view to describe the hardware and software and its environment. ConclusionWe demonstrated that the methods of creating a Reference Architecture could be used in the Digital Twin-based predictive maintenance domain and showed how an Application Architecture could be designed in this context.

Current and paleo sources of organic material within fluvial features of the meandering Ruda River, Poland

This study aimed to identify differences in organic matter (OM) composition and origin in the main depositional subenvironments within the floodplain of a meandering river in a temperate climate zone. The study analysed organic-rich sediments found within different facies (side bars, natural levees, crevasse splays, palaeochannels, flood basins, and alluvial fans). Quantitative macrofossil analysis of the OM present in proximal floodplain sediments pointed to a dominance of amorphous OM (AOM), the average proportion of which comprised up to 60% of the total OM. During floods, the most significant phenomenon is the deposition of wood and leaf debris; however, these debris are subject to rapid decomposition in sandy layers and, as a result, do not contribute much to the total OM composition. Root and epidermis remain accumulated in situ and, with an average share of more than 10% of the total OM, are an important part of the more fine-grained alluvial layers. The other components were no more than bioindicators. The proximal floodplain is characterised by sponge spicules in the alluvia and mycelia in the epipedons. In addition, diatom remains are often recorded in the flood layers. The average AOM content in the OM found within the distal floodplain was approximately 40%, although a significantly higher proportion of this component was recorded in flood basin sediments. The accumulation of rhizodermis, epidermis, wood, and periderm (with shares ranging from 5% to 22% of the total OM) plays an important role. Less common components that are of indicative value within the distal zone include the remains of mosses, Cladocera, and sporomorphs. OM within the distal floodplain has high preservation potential, and the sediments in this zone are crucial for carbon sequestration processes in river valleys.

Effect of pycnogenol on ethanol-related oxidative retinal injury: an experimental study.

We aimed at determining the protective effects of Pycnogenol on ethanol-induced retinotoxicity in an experimental model. 30 male Wistar albino rats were randomly divided into three groups: an untreated healthy control (HC group), a group in which only ethanol was daily administered for six weeks (EtOH group), and a group in which ethanol + 40 mg/kg Pycnogenol was daily administered orally for six weeks (PEtOH group). The same volume (0.5 ml) of distilled water as solvent was applied in the same manner to the rats in the HC and EtOH groups. With the rats in the PEtOH and EtOH groups, 32% ethanol at a dose of 5 g/kg was administered by oral gavage one hour after the application of pycnogenol or distilled water. At the end of the experimental period, tissue samples were obtained for biochemical examination of malondialdehyde (MDA) and total glutathione (tGSH) levels, and afterwards, the eyes were removed for histopathological examination. Histopathological evaluations in the EtOH group showed significant destruction of retinal tissue with marked edema, decomposition and degeneration in layers, polymorphonuclear cell infiltration, dilatation and congestion in blood vessels. However, it was observed that MDA values increased and tGSH values decreased in the EtOH group. In the PEtOH group, MDA values decreased and GSH values increased. Again, degenerative changes were considerably less in this group. In the light of biochemical markers and histopathological evaluations, it was observed that ethanol exposure caused a significant degeneration in the retinal tissue. It was found that Pycnogenol administration significantly reduced the destructive effects seen histopathologically. Biochemical results also coincided with other findings. It was concluded that ethanol-induced rethytosis can be prevented to a large extent by Pycnogenol administration.

In situ spectral reflectance analysis of the early stages of GaN thermal decomposition

The decomposition of GaN layers have been in situ monitored by a spectral reflectance system. A particular interest is given to the early stages of GaN decomposition. The analysis of the spectral reflectance behavior shows a rapid reflectance increase, which is associated with the formation of gallium metallic layer. After that, reflectance oscillates and damps with the processing time indicating the decomposition of the GaN layer. The transfer matrix formalism and the effective refractive index concept have been combined to understand the experimental recorded reflectance responses during GaN decomposition under H2 flux at high temperature. We have developed an effective refractive index formula taking into account the coexistence of gallium and GaN materials for fitting experimental results. This assumption has been validated as a good tool for the interpretation of the reflectance variations. Our results are confirmed and analyzed based on scanning electron microscopic (SEM) observations and photoluminescence measurements.

Numerical Simulation of Hydrate Decomposition during the Drilling Process of the Hydrate Reservoir in the Northern South China Sea

The process of drilling in natural gas hydrate reservoirs in sea areas involves problems such as hydrate decomposition and wellbore instability. To study the response behaviors of a reservoir during the drilling process, a two-dimensional numerical model of drilling fluid invading a hydrate reservoir in a cylindrical coordinate system was established to simulate the processes of heat and mass transfer, gas–liquid two-phase flow, and hydrate formation and decomposition in the hydrate reservoir during the drilling process. Based on the hydrate reservoir at station W17, Shenhu area of the South China Sea, the physical property response of the hydrate reservoir under different drilling fluid temperatures and salinity values was studied. The simulation results showed that during the drilling process, the temperature and pressure of the reservoir respond rapidly in a large area, further promoting the hydrate decomposition in the reservoir around the wellbore and leading to secondary hydrate formation. Moreover, a high hydrate saturation zone appears near the decomposed hydrate area in the layer without free gas, which corresponds to the low water saturation and high salinity zone. The hydrate decomposition area in the layer with free gas is larger than that without free gas. The increase in the drilling fluid temperature significantly enhances the hydrate decomposition in both layers of the reservoir. The hydrate decomposition near the wellbore under the high drilling fluid temperature will cause a sharp increase in the pressure in the reservoir, leading to the flow of pore fluid into the wellbore. The increase in drilling fluid salinity has little effect on the range of the hydrate decomposition in the reservoir but significantly increases the salinity of the pore water in the layer with free gas. As the drilling fluid temperature increases, the possibility of the gas invasion from the reservoir into the wellbore will be greatly increased at the early stage.

Diffusion induced decomposition of cementite layers during gas nitriding of 4140 steel: thermodynamical and kinetical aspects

In this paper, some new aspects of the decomposition of cementite layers by diffusion of nitrogen during gas nitriding are investigated. Therefore, AISI4140 steel samples were heat-treated to harden by heating up to 1113 K for 120 min, followed by quenching in agitated mineral oil. Then samples were tempered at 863 K for 60 min. Nitriding was carried out for 1400 up to 21000 min. Samples were characterized by optical microscope, scanning electron microscope, x-ray diffractometer, and HSC thermodynamical software. Results showed that the rate of diffusion was higher in the early stages of nitriding. Due to nitrogen of diffusion, some nitrides are formed in grain boundaries and act as diffusion barriers. In this case, the diffusion mechanism from grain boundary diffusion changes to the volume diffusion or a combination of both mechanisms. Meanwhile, diffusion of nitrogen, in addition to the ferrite layers and grain boundaries, is also performed into the cementite layers. Although these layers are not the preferred areas of diffusion, volume diffusion of nitrogen through cementite layers leads to decomposition of them and turning them into iron nitrides and carbo-nitrides. Results show that almost 42 percent of cementite layers decomposed by nitrogen diffusion.

Models and Methods for Improving Performance of Wireless Computer Networks Based on the Decomposition of Lower Layers of the OSI Reference Model

The paper discusses models and methods for improving the performance of wireless computer networks built based on the decomposition of the lower levels of the OSI reference model. A method to improve the performance of networks is suggested, which functionally combines the physical and network layers, which improves its efficiency in marginal reception areas almost twice. A model of the block diagram of a device for improving data transmission quality in marginal reception areas or those with insufficient noise immunity is developed based on the so-called communication quality status monitoring, as well as a model of the block diagram of a wireless adaptive capacity reallocation router based on dynamic channels capacity reallocation, which allows adequately reallocating IS resources depending on traffic and user priority. Keywords— Bluetooth, FIFO discipline, IEEE 802.11, OSI/ISO reference model, wireless computer networks.

New insights into degradation of Fe–N–C catalyst layers: ionomer decomposition

A new degradation mechanism of ionomer decomposition in catalyst layers was directly monitored by 19F NMR spectrum analysis.

Large Eddy Simulation and Dynamic Mode Decomposition of Turbulent Mixing Layers

Turbulent mixing layers are canonical flow in nature and engineering, and deserve comprehensive studies under various conditions using different methods. In this paper, turbulent mixing layers are investigated using large eddy simulation and dynamic mode decomposition. The accuracy of the computations is verified and validated. Standard dynamic mode decomposition is utilized to flow decomposition, reconstruction and prediction. It was found that the dominant-mode selection criterion based on mode amplitude is more suitable for turbulent mixing layer flow compared with the other three criteria based on singular value, modal energy and integral modal amplitude, respectively. For the mixing layer with random disturbance, the standard dynamic mode decomposition method could accurately reconstruct and predict the region before instability happens, but is not qualified in the regions after that, which implies that improved dynamic mode decomposition methods need to be utilized or developed for the future dynamic mode decomposition of turbulent mixing layers.

Soil burial reduces decomposition and offsets erosion-induced soil carbon losses in the Indian Himalaya.

The extent to which soil erosion is a net source or sink of carbon globally remains unresolved but has the potential to play a key role in determining the magnitude of CO2 emissions from land-use change in rapidly eroding landscapes. The effects of soil erosion on carbon storage in low-input agricultural systems, in acknowledged global soil erosion hotspots in developing countries, are especially poorly understood. Working in one such hotspot, the Indian Himalaya, we measured and modelled field-scale soil budgets, to quantify erosion-induced changes in soil carbon storage. In addition, we used long-term (1-year) incubations of separate and mixed soil horizons to better understand the mechanisms controlling erosion-induced changes in soil carbon cycling. We demonstrate that high rates of soil erosion did not promote a net carbon loss to the atmosphere at the field scale. Furthermore, our experiments showed that rates of decomposition in the organic matter-rich subsoil layers in depositional areas were lower per unit of soil carbon than from other landscape positions; however, these rates could be increased by mixing with topsoils. The results indicate that, the burial of soil carbon, and separation from fresh carbon inputs, led to reduced rates of decomposition offsetting potential carbon losses during soil erosion and transport within the cultivated fields. We conclude that the high rates of erosion experienced in these Himalayan soils do not, in isolation, drive substantial emissions of organic carbon, and there is the potential to promote carbon storage through sustainable agricultural practice.

Optical characterization by photoreflectance of GaN after its partial thermal decomposition

In the current study, we investigated the partial decomposition of GaN layers grown on SiN-treated sapphire substrate in an atmospheric pressure metal organic vapor phase epitaxy (AP-MOVPE) vertical reactor under N2 ambient at 1200 °C. Under these experimental conditions, we studied the decomposition of different coalescence degrees GaN layers and the early thermal decomposition stages of GaN films. By the help of the scanning electron microscope (SEM), the surface morphology of the decomposed GaN epilayers was examined. We demonstrated that the thermal decomposition leads to an irregular etching process, which was carried out step by step. The optical properties of the decomposed films were then studied by using the photoreflectance (PR) technique at room temperature and at 11 K. We determined a logarithmic relation between the built-in electric field in the surface of GaN layers and the stress value. A model is also proposed to extract the stress value from PR spectra. It should be noted also that by using the thermal decomposition process, the stress inside GaN layers can be reduced by a factor of 6.

Application of Tensor Train Decomposition in S2VT Model for Sign Language Recognition

Sign language recognition is a conversion of sign language into text or speech, bridging the communication between the hearing and society. Recently, sequence-to-sequence video to text (S2VT) models has been employed in the field of sign language recognition as an effective method. However, more than 20 million parameters trained in S2VT models will result in a huge consumption in memory and computational resources, making it hard to be applied in mobile devices. In order to overcome this issue, we proposed to employ tensor-train decomposition in S2VT models to reduce the parameters. First, the impact of parameters of tensor-train factorization on the model performance was investigated systematically. After that, we applied tensor-train decomposition in different layers of a S2VT model to establish 6 tensor-train S2VT models for Chinese sign language recognition. The experimental results demonstrated that when the fully-connected layer and the first LSTM layer in S2VT was represented with tensor-train format, the model could obtain the best performance, remaining high accuracy and reducing parameters and memory significantly. The proposed tensor-train S2VT models can also be applied in other sequence-to-sequence problems to improve the performance.