Plastic plays an important role in our daily lives due to its versatility, light weight and low production cost. Plastics became essential in many sectors such as construction, medical, engineering ...applications, automotive, aerospace, etc. In addition, economic growth and development also increased our demand and dependency on plastics which leads to its accumulation in landfills imposing risk on human health, animals and cause environmental pollution problems such as ground water contamination, sanitary related issues, etc. Hence, a sustainable and an efficient plastic waste treatment is essential to avoid such issues. Pyrolysis is a thermo-chemical plastic waste treatment technique which can solve such pollution problems, as well as, recover valuable energy and products such as oil and gas. Pyrolysis of plastic solid waste (PSW) has gained importance due to having better advantages towards environmental pollution and reduction of carbon footprint of plastic products by minimizing the emissions of carbon monoxide and carbon dioxide compared to combustion and gasification. This paper presents the existing techniques of pyrolysis, the parameters which affect the products yield and selectivity and identify major research gaps in this technology. The influence of different catalysts on the process as well as review and comparative assessment of pyrolysis with other thermal and catalytic plastic treatment methods, is also presented.
•We review the technology of pyrolysis, detailing the main influencing factors.•Typical setups are detailed showcasing main engineering aspects and feedstock type.•Analytical/applied pyrolysis with a focus on catalytic performance is detailed.
The management of municipal solid waste (MSW) and the current status of world energy resources crisis are important problems. Gasification is a kind of waste-to- energy conversion scheme that offers ...the most attractive solution to both waste disposal and energy problems. In this study, the thermodynamic equilibrium model based on equilibrium constant for predicting the composition of producer gas in a downdraft waste gasifier was developed. To enhance the performance of the model, further modification was made by multiplying the equilibrium constants with coefficients. The modified model was validated with the data reported by different researchers. MSW in Thailand was then used to simulate and to study the effects of moisture content (MC) of the waste on the gasifier's performance. The results showed that the mole fraction of H
2 gradually increases; CO decreases; CH
4, which has a very low percentage in the producer gas increases; N
2 slightly decreases; and CO
2 increases with increasing MC. The reaction temperature, the calorific value, and the second law efficiency, decrease when MC increases.
The theory of the nuclear energy-density functional is used to provide a unified and thermodynamically consistent treatment of all regions of cold non-accreting neutron stars. In orderto assess the ...impact of our lack of complete knowledge of the density dependence of thesymmetry energy on the constitution and the global structure of neutron stars, we employfour different functionals. All of them were precision fitted to essentially all the nuclear massdata with the Hartree–Fock–Bogoliubov method and two different neutron-matter equationsof state based on realistic nuclear forces. For each functional, we calculate the composition,the pressure–density relation, and the chemical potentials throughout the star. We show thatuncertainties in the symmetry energy can significantly affect the theoretical results for thecomposition and global structure of neutron stars. To facilitate astrophysical applications, weconstruct analytic fits to our numerical results.
Spouted beds have been found in many applications, one of which is gasification. In this paper, the gasification processes of conventional and modified spouted bed gasifiers were considered. The ...conventional spouted bed is a central jet spouted bed, while the modified spouted beds are circular split spouted bed and spout-fluid bed. The Gibbs free energy minimization method was used to predict the composition of the producer gas. The major six components, CO, CO
2, CH
4, H
2O, H
2 and N
2, were determined in the mixture of the producer gas. The results showed that the carbon conversion in the gasification process plays an important role in the model. A modified model was developed by considering the carbon conversion in the constraint equations and in the energy balance calculation. The results from the modified model showed improvements. The higher heating values (HHV) were also calculated and compared with the ones from experiments. The agreements of the calculated and experimental values of HHV, especially in the case of the circular split spouted bed and the spout-fluid bed were observed.
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•Yttrium doped cobalt ferrite nanoparticles synthesized via citrate auto-ignition method.•Rietveld analyses indicate optimum values of microstructural parameters for 15 mol% doped ...sample.•Existence of spin canting and IPDI were confirmed via V.S.M. results.•Anisotropy and saturation magnetization decrease with doping as estimated from L.A. analysis.•Electrical conductivity for all the samples delineates V.R.H. process.
Tailoring of properties by changing morphology or by doping is very much required for the suitable application of any materials. Here we report the effect of yttrium doping on microstructure, magnetic and electrical properties of cobalt ferrite nanoparticles prepared through citrate auto-ignition method. Rietveld refinement analysis of X-ray diffraction pattern confirms the growth of pure and single phase cobalt ferrite nanoparticles which corroborates with transmission electron microscopy (TEM) study. Microstructural parameters, obtained from Rietveld analysis showed that oxygen vacancy is maximum and inter-ionic bond lengths and bond angles attain optimum values for 15 mol% yttrium doped sample. An observed value of saturation magnetization indicates the existence of spin canting phenomenon which was explained by Yafet-Kittel model. Magnetic parameters such as anisotropy constant, anisotropy field have been estimated using Law of Approach (L.A.) formalism. Existence of interparticle dipolar interaction (IPDI) in the system was established with the help of Mr/Ms ratio around room temperature. Maximum electrical conductivity has been observed for the 15 mol% doped sample as estimated from Mott’s 3-D V.R.H. model, which can be attributed to the optimum values of microstructural parameters at this composition.
Abstract We present a self-consistent representation of the atmosphere and implement the interactions of light with the atmosphere using a photon Monte Carlo approach. We compile global climate ...distributions based on historical data, self-consistent vertical profiles of thermodynamic quantities, spatial models of cloud variation and cover, and global distributions of four kinds of aerosols. We then implement refraction, Rayleigh scattering, molecular interactions, and Tyndall–Mie scattering to all photons emitted from astronomical sources and various background components using physics first principles. This results in emergent image properties that include: differential astrometry and elliptical point spread functions (PSFs) predicted completely to the horizon, arcminute-scale spatial-dependent photometry variations at 20 mmag for short exposures, excess background spatial variations at 0.2% due to the atmosphere, and a PSF wing due to water droplets. We use a common atmosphere representation framework to self-consistently model all phenomena by simulating individual photons. We reproduce the well-known correlations in image characteristics: correlations in altitude with absolute photometry (overall transmission) and relative photometry (spectrally dependent transmission), anticorrelations of altitude with differential astrometry (nonideal astrometric patterns) and background levels, and an anticorrelation in absolute photometry with cloud depth. However, we also find further subtle correlations including an anticorrelation of temperature with background and differential astrometry, a correlation of temperature with absolute and relative photometry, an anticorrelation of absolute photometry with humidity, a correlation of humidity with lunar background, a significant correlation of PSF wing with cloud depth, an anticorrelation of background with cloud depth, and a correlation of lunar background with cloud depth.
Chromatin remodeling factors are becoming known as crucial facilitators of recruitment of repair proteins to sites of DNA damage. Multiple chromatin remodeling protein complexes are now known to be ...required for efficient double strand break repair. In a screen for microRNAs (miRNAs) that modulate the DNA damage response, we discovered that expression of the miR-99 family of miRNAs correlates with radiation sensitivity. These miRNAs were also transiently induced following radiation. The miRNAs target the SWI/SNF chromatin remodeling factor SNF2H/SMARCA5, a component of the ACF1 complex. We found that by reducing levels of SNF2H, miR-99a and miR-100 reduced BRCA1 localization to sites of DNA damage. Introduction of the miR-99 family of miRNAs into cells reduced the rate and overall efficiency of repair by both homologous recombination and non-homologous end joining. Finally, induction of the miR-99 family following radiation prevents an increase in SNF2H expression and reduces the recruitment of BRCA1 to the sites of DNA damage following a second dose of radiation, reducing the efficiency of repair after multiple rounds of radiation, as used in fractionated radiotherapy.
In the current work we investigate the room temperature tensile properties of a medium-Mn twinning- and transformation-induced plasticity (TWIP-TRIP) steel from quasi-static to low-dynamic strain ...rates (ε˙ = 10−4 s−1 to ε˙ = 102 s−1). The multi-phase microstructure consists of coarse-grained recovered α'-martensite (inherited from the cold-rolled microstructure), multiple morphologies of ultrafine-grained (UFG) austenite (equiaxed, rod-like and plate-like), and equiaxed UFG ferrite. The multi-phase material exhibits a positive strain-rate sensitivity for yield and ultimate tensile strengths. Thermal imaging and digital image correlation allow for in situ measurements of temperature and local strain in the gauge length during tensile testing, but Lüders bands and Portevin Le Chatelier bands are not observed. A finite-element model uses empirical evidence from electron backscatter diffraction (EBSD) and transmission electron microscopy (TEM), plus constitutive equations to dissect the microstructural influences of grain size, dislocation density and TWIP-TRIP driving forces on tensile properties. Calibration of tensile properties not only captures the strain rate sensitivity of the multi-phase TWIP-TRIP steel, but also provides opportunity for a complete parametric analysis by changing one variable at a time (phase fraction, grain size, strain-induced twin fraction and strain-induced ε-martensite fraction). An equivalent set of high-rate mechanical properties can be matched by changing either the austenite phase fraction or the ratio of twinning vs. transformation to ε-martensite. This experimental-computational framework enables the prediction of mechanical properties in multi-phase steels beyond the experimental regime by tuning variables that are relevant to the alloy design process.
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Abstract We propose a modified moment matching algorithm to avoid catastrophic failures for sources with a low signal to noise ratio. The proposed modifications include a method to eliminate ...nonphysical negative pixel values and a forced single iteration with an initial guess derived from coadd measurements when iterative methods are unstable. We correct for all biases in measurements introduced by the method. We find that the proposed modifications allow the algorithm to avoid catastrophic failures in nearly 100% of the cases, especially at low SNR. Additionally, with a reasonable guess from coadd measurements, the algorithm measures the flux, centroid, size, shape, and ellipticity with a bias statistically consistent with zero. We show that the proposed method allows us to measure sources 7 times fainter than traditional methods when applied to images obtained from WIYN-ODI. We also present a scheme to find uncertainties in measurements when using the new method to measure astronomical sources.
In this article, we probe the strain partitioning between the microstructural features present in a continuously cooled carbide-free bainitic steel together with damage nucleation and propagation. ...These features mainly comprise of phases (bainitic ferrite, martensite, and blocky/thin film austenite), interfaces between them, grain size and grain morphology. A micro Digital Image Correlation (μ-DIC) technique in scanning electron microscope is used to quantify the strain distribution between these microstructural features. The results show a strong strain partitioning between martensite, bainitic ferrite and retained austenite that provides weak links in the microstructure and creates conditions for the crack initiation and propagation during deformation. Blocky austenite islands accommodate maximum local strains in the global strain range of 0–2.3% and undergo strain-induced austenite to martensite transformation governing the local strain evolution in the microstructure. However, the local strains are minimum in martensite regions during entire in-situ deformation stage. Narrow bainitic ferrite channels in between martensitic islands and martensite-bainitic ferrite interfaces are recognised as primary damage sites with high strain accumulation of 30 ± 2% and 20 ± 3% respectively, at a global strain of 9%. The inclination of these interfaces with the tensile direction also affects the strain accumulation and damage.
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