Mercury storage in surface soils in a central Washington forest and estimated release during the 2001 Rex Creek Fire

Recent investigations indicate that wildfires provide a significant flux of mercury (Hg) from terrestrial ecosystems to the atmosphere. However, little is known about how geographic location, climate, stand age, and tree species affect Hg accumulation prior to burning and loss during burning. Soil cores collected in sites burned during the summer 2001 Rex Creek Fire in the eastern Cascade Mountains (Washington State, USA) and in adjacent unburned control sites indicate that Hg loss from soils during the Rex Creek Fire averaged 6.7 (+/-2.5) g Hg ha(-1). This soil profile-based estimate of Hg release is higher than a previous estimate for the same fire based on airborne measurements of Hg and CO concentrations in smoke. This study has implications for global estimates of Hg storage in forests and release to the atmosphere during wildfires.     

An Intelligent Fine-Tuned Forecasting Technique for Covid-19 Prediction Using Neuralprophet Model

COVID-19, being the virus of fear and anxiety, is one of the most recent and emergent of various respiratory disorders. It is similar to the MERS-COV and SARS-COV, the viruses that affected a large population of different countries in the year 2012 and 2002, respectively. Various standard models have been used for COVID-19 epidemic prediction but they suffered from low accuracy due to lesser data availability and a high level of uncertainty. The proposed approach used a machine learning-based time-series Facebook NeuralProphet model for prediction of the number of death as well as confirmed cases and compared it with Poisson Distribution, and Random Forest Model. The analysis upon dataset has been performed considering the time duration from January 1^st 2020 to16^th July 2021. The model has been developed to obtain the forecast values till September 2021. This study aimed to determine the pandemic prediction of COVID-19 in the second wave of coronavirus in India using the latest Time-Series model to observe and predict the coronavirus pandemic situation across the country. In India, the cases are rapidly increasing day-by-day since mid of Feb 2021. The prediction of death rate using the proposed model has a good ability to forecast the COVID-19 dataset essentially in the second wave. To empower the prediction for future validation, the proposed model works effectively.     

A new co-evolutionary decomposition-based algorithm for bi-level combinatorial optimization

Bi-Level Optimization Problems (BLOPs) are a class of challenging problems with two levels of optimization tasks. The main goal is to optimize the upper level problem which has another optimization problem as a constraint. The latter is called the lower level problem. In this way, the evaluation of each upper level solution requires finding an (near) optimal solution to the corresponding lower level problem, which is computationally very expensive. Many real world applications are bi-level by nature, ranging from logistics to software engineering. Further, proposed bi-level approaches have been restricted to solve linear BLOPs. This fact has attracted the evolutionary computation community to tackle such complex problems and many interesting works have recently been proposed. Unfortunately, most of these works are restricted to the continuous case. Motivated by this observation, we propose in this paper a new Co-evolutionary Decomposition Algorithm inspired from Chemical Reaction Optimization algorithm, called E-CODBA (Energy-based CODBA), to solve combinatorial bi-level problems. Our algorithm is based on our previous works within this research area. The main idea behind E-CODBA is to exploit co-evolution, decomposition, and energy laws to come up with good solution(s) within an acceptable execution time. The statistical analysis of the experimental results on the Bi-level Multi-Depot Vehicle Routing Problem (Bi-MDVRP) show the out-performance of our E-CODBA against four recently proposed works in terms of effectiveness and efficiency.     

Facile synthesis of doped ceria-based oxide by co-precipitation technique and performance evaluation in solid oxide fuel cell

Co-precipitated nanocrystalline gadolinium (Gd)-doped ceria (CeO₂) has been synthesized with varying mole ratios of Gd in CeO₂ from 0.1-0.8 with intricate maintenance of solution pH. Phase pure Gd-doped CeO₂ (CGO) is obtained after calcination at 750°C and depending on the mole % dopant concentration, the typical crystallite size is found to vary in the range 9-27 nm. Careful observation reveals that, calcined particle size decreases with the decrease in Gd content and an optimization of the particle size with exposed (111) [stable] and (100) plane [reactive] happens to occur for Ce_0.8Gd_0.2O_2−δ (CG_0.8). High resolution transmission electron micrograph of CG_0.8 reveals highly interpenetrating lattice planes corresponding to cubic fluorite structure. The effectivity of such CG_0.8 is further supported by its high electrical conductivity of 0.02 and 0.105 S/cm @ 600 and 700°C respectively. The bulk impedances exhibit ohmic (R₀) and interfacial (R_p) polarizations to be 146 and 29.96 Ω cm² at a temperature of 600 and 700°C with activation energies 0.36 and 0.8 eV respectively. The application of CG_0.8 is further established as an interlayer in nickel oxide-yittria stabilized zirconia (NiO-YSZ)/YSZ/CGO/La-Sr-Co-Fe-based single cell with a current density of 1.2 A/cm² @ 0.5 V and 700°C using hydrogen as the fuel and oxygen as the oxidant.     

CARD15/NOD2, CD14 and Toll-like 4 Receptor Gene Polymorphisms in Saudi Patients with Crohn's Disease

Crohn's disease (CD) is a multifactorial disease with a genetic component and an observed association with genes related to the innate immune response. Polymorphisms in the CARD15/NOD2 gene, in addition to functional variants of the toll-like receptor-4 (TLR4) and CD14 genes, have been associated with the development of Crohn's disease. There is no information about the frequency of these polymorphisms in the Saudi population. We examined the frequency of the three major CARD15/NOD2 risk alleles (Leu1007fsinsC, Arg702Trp, and Gly908Arg) and the TLR4 (Thr399Il) polymorphism as well as a functional polymorphism in the promoter of the CD14-159C/T in 46 Saudi CD patients and 50 matched controls. Genotyping was performed by allele-specific PCR or by restriction fragment length polymorphism (PCR-RFLP) analysis. The mutant genotype frequencies of the Leu1007fsinsC, Arg702Trp and Gly908Arg in the patient group were 6.5, 21.7 and 6.5%, respectively, compared with frequencies of 0, 4 and 2%, respectively, in the control group. There were 15 patients who carried the mutant alleles for all three CARD15/NOD2 variants, Leu1007fsinsC, Arg702Trp and Gly908Arg, while none of the control candidates carried the three alleles. This genetic study provides evidence that the three major CARD15/NOD2 variant alleles and the CD14 -159C/T polymorphism are associated with Crohn's disease (CD) susceptibility in the Saudi population; however, there is no evidence that the TLR4 (Thr399Il) or CARD15/NOD2 polymorphisms can be considered risk factors for Crohn's disease.     

Effect of TiO2, LiF and Cr2O3 in the Crystallization of Cristobalite and Tridymite in Sintered Glass-Ceramics

Based on the poudretteite (K Na₂ B₃ Si₁₂ O₃₀) glass composition, six transparent glass frits were prepared. TiO₂, LiF and Cr₂O₃ were experimented on the base glass composition as nucleation catalysts. Only cristobalite and tridymite were developed through the sintering process of the glasses between 900 and 1100?°C. LiF enhances mainly tridymite with traces of cristobalite and in the opposite side the parent and both TiO₂ and Cr₂O₃ containing glasses catalyzed mainly cristobalite with traces of tridymite. The microstructure of the glass samples heat-treated at 1000?°C showed backbone-like, small rods, quadrant-, hexagonal crystals referred to the cristobalite and tridymite. The EDS microanalysis shows the presence of both alkalis, i.e. Na^?+? and K^?+?, in the cristobalite crystal structure while the residual glass contains K^?+?. The infrared spectroscopy indicates the band patterns of cristobalite and tridymite.     

Apparent kinetics of nonisothermal high temperature oxidative degradation of ethylene homopolymers: effects of residual catalyst surface chemistry and structure

The effects of two supported residual catalysts—one Ziegler-Natta and another metallocene—on the nonisothermal thermooxidative degradation of the resulting ethylene homopolymers were investigated using TGA experiments and kinetic modeling. The rigorous constitutive kinetic model (developed in this study), unlike the analytical Horowitz and Metzger model, fitted very well to the entire TGA curve, without distribution of activation energy E _a , for n (overall degradation order)?=?1 for both polymers. Neither n nor E _a varied as a function of fractional weight loss of the polymer. Hence, the proposed unified molecular level concept of surface chemistry and structure of the residual catalysts held all through the degradation process. The above feature of n and E _a also indicates the suitability of the model formulation and the effectiveness of the parameter-estimation algorithm. Random polymer chain scission, with the cleavage of the ?C?C? and the ?O?O? (hydroperoxide) bonds, prevailed. The types of residual catalyst surface chemistry and structure varied the bond cleavage process. The metallocene Zr residual catalyst caused more thermooxidative degradation in MetCat?HomoPE than what the Ti one did in Z-N?HomoPE. The rigorous constitutive model-predicted apparent kinetic energy E _a , and frequency factor Z also support this finding. The proposed degradation mechanism suggests that the Zr residual catalyst more (i) decreased the activation energy required to decompose the ?C?C? and the ?O?O? bonds, and (ii) eliminated β-hydrogen (by the carbonyl functionalities) from the polymer chains. These findings were attributed to the differences in surface chemistry and structure of the residual catalysts. Therefore, the current study presents a rigorous constitutive kinetic model that duly illustrates the influence of the characteristic surface chemistry and structure of the residual catalysts on the high temperature oxidative degradation of polyethylenes.     

Gamma Radiation Shielding and Mechanical Studies on Highly Dense Lithium Iron Borosilicate Glasses Modified by Zinc Oxide

Silicon - Five glass samples of a new zinc-iron lithiumborosilicate (LBSFZ) with the chemical formula 64.8B2O3–8.5SiO2–1.5Fe2O3 – (25.2 − x)Li2O - x ZnO...     

Use of N‐(N′‐arylamino)maleimides to improve the thermal properties of poly(vinyl chloride) through chemical modification and graft copolymerization

The reaction of poly(vinyl chloride) (PVC) with N‐(N′‐arylamino)maleimide derivatives was studied. The thermal stability of the modified polymer was improved markedly when compared with that of the unmodified polymer. The stability improvement was attributed to the replacement of the labile chlorine atoms by more stable organic groups. The modified polymer also showed a lower extent of discoloration when compared with that of unmodified PVC. In order to introduce a polymeric stabilizer into PVC, the dienophilic monomer was chemically grafted onto the polymeric chains. The mechanism of the chemical modification as well as that of the graft copolymerization are discussed. J. VINYL ADDIT. TECHNOL., 2008. © 2008 Society of Plastics Engineers.