Effect of 1 wt.% yttrium addition on high-temperature sulfidation behavior of Fe-15Cr-4Al alloy

High-temperature sulfidation studies have been carried out on Fe-15Cr-4Al with and without 1% Y in the temperature range 700–1000°C in an H ₂-H₂ S environment over the sulfur pressure range of 10 ^–9–10^–3 atm. Two-layered and three-layered sulfide scales were observed in both alloys at low and high sulfur pressures, respectively. The pegging phenomenon, similar to that occurring in high-temperature oxidation, across the innermost layer and substrate was observed in the case of the yttrium-containing alloy. Yttrium was found to be associated with aluminum and chromium sulfides. The role of yttrium was more evident at low than at high sulfur pressures and was found to reduce the parabolic rate constants by a factor of about one-half to one-seventh, respectively.     

Hydrodynamic characteristics in a pilot-scale cold flow model for chemical looping combustion

Chemical Looping Combustion (CLC) in two interconnected fluidized beds, i.e., the air reactor and the fuel reactor has been recognized to be promising. As the CLC setup design is critical and sensitive to oxygen carrier (OC) materials, it is very much essential to investigate hydrodynamics in a specially fabricated cold model set up for the successful development and operational control of corresponding large-scale hot model. In this study, a pilot-scale cold flow model CLC system has been designed and tested. The riser and fuel reactor were operated at circulated fluidized bed and bubbling fluidized bed conditions, respectively and the control of solid circulation between two reactors was done by two loop seals operated in bubbling fluidized bed conditions. The effect of fluidization velocity in the riser on the voidage profiles, solid circulation rate, and pressure profiles were investigated using Indian ilmenite (150–212?µm) as OC. The stable operation of the system was established under various operational conditions. The results will be useful for the development of ilmenite based hot model CLC system. Moreover, the achievable variations of solid circulation rate in the present study in cold model setup will determine obtainable limit of extent of oxygen transport and thermal energy.     

Impact of annealing temperature on structural,optical, and Mössbauer properties of nanocrystalline NiFe2O4

In this paper, we have investigated the effect of annealing temperature on the structural, optical, and Mössbauer properties of nanocrystalline (NC) nickel ferrites (NFOs) synthesized by the sol–gel auto-combustion method. The NFOs were characterized by X-Ray diffraction (XRD), Raman spectroscopy, Diffusion reflectance spectroscopy (DRS), and Mössbauer spectroscopy techniques. The XRD results show that the average crystallite size increases from 27.5 to 54.3 nm when increasing the annealing temperature from 200 to 1000 °C. The Ultraviolet–Visible Diffuse Reflectance Spectroscopy (UV-DRS) measurement is used to find the optical band gap observed between 1.92 and 1.75 eV for NFOs annealed at 200 and 1000 °C, respectively. The Mössbauer study confirmed that the structure transforms from mixed spinel to inverse spinel structure when moving to higher annealing temperature.

     

Biomimetic synthesis of AgNPs from Penicillium chrysogenum strain FGCC/BLS1 by optimising physico‐cultural conditions and assessment of their antimicrobial potential

Biomimetic synthesis of metal nanoparticles (NPs) is safe and eco‐friendly; therefore, find diverse applications. Considering this, the soil fungi Penicillium chrysogenum strain Fungal germplasm collection centre/ BLS1 was isolated, characterized and explored to synthesize extracellular silver NPs (AgNPs) under optimised conditions. The synthesis of AgNPs was investigated using ultraviolet (UV)–visible spectroscopy, Fourier‐transform infra‐red spectroscopy (FTIR), transmission electron microscope (TEM) and dynamic light scattering (DLS) analysis. Process optimisation exhibited AgNPs synthesis within 8 h using 2 mM AgNO3 at pH 11 and temperature 70°C. TEM analysis revealed polydispersed ellipsoidal shaped AgNPs with average particle size 96.8 nm as measured by DLS. AgNPs showed negative zeta potential that confers surface stability in solution. FTIR spectra confirmed the presence of protein bound to AgNPs. Antibacterial activity against Escherichia coli, Klebsiella pneumoniae and Staphylococcus aureus by the AgNPs (100 ppm) was demonstrated by counting colony forming unit, disc diffusion, and growth kinetics assay. Additionally radial assay revealed antifungal activity of AgNPs (100 ppm) against phytopathogenic fungi Sclerotinia sclerotiorum Microbial type culture collection 8785. Furthermore, AgNPs (100 ppm) did not show any cytotoxic effects on human Red blood cells. Therefore, this novel fungal strain can be utilised for biofabrication of AgNPs under optimised conditions and have shown strong antimicrobial property.Inspec keywords: biomimetics, silver, nanoparticles, particle size, nanofabrication, nanomedicine, microorganisms, biomedical materials, antibacterial activity, light scattering, cellular biophysics, ultraviolet spectra, visible spectra, Fourier transform infrared spectra, transmission electron microscopy, pH, electrokinetic effects, proteins, molecular biophysics, biochemistry, reduction (chemical), biodiffusion, reaction kinetics, bloodOther keywords: biomimetic synthesis, physicocultural conditions, antimicrobial potential assessment, metal nanoparticles, soil fungi Penicillium chrysogenum strain FGCC/BLS1, extracellular silver NPs, ultraviolet‐visible spectroscopy, Fourier transform infrared spectroscopy, FTIR, transmission electron microscope, TEM, dynamic light scattering, process optimisation, Ag nitrate, pH, absorbance, polydispersed ellipsoidal shaped AgNPs, particle size, DLS, mycosynthesised AgNPs, negative zeta potential, surface stability, protein component, reducing agent, antibacterial activity, Escherichia coli, Klebsiella pneumoniae, Staphylococcus aureus, disc diffusion, colony forming unit counting, growth kinetics assay, radial assay, antifungal activity, phytopathogenic fungi Sclerotinia sclerotiorum MTCC 8785, RBC haemolysis assay, temperature 70 degC, Ag     

Computational and experimental investigation on mechanical behavior of zirconia toughened alumina and nickel powder reinforced EN31 based composite material

In the present investigation, EN31 steel alloy based composite material has been developed using zirconia toughened alumina as primary reinforcement material and Ni powder as secondary reinforcement material. The weight percent of zirconia toughened alumina varied from 1.25 % to 10 %. While Ni powder weight percent has been kept uniform (2.5 %). The microstructure of the composite material developed showed uniform distribution of reinforcement particles. Results showed that wettability of zirconia toughened alumina particles improved by adding the nickel particles in EN31 steel alloy. Tensile strength and hardness after the heat treatment were found to be 899 MPa and 120.12 BHN respectively for EN31/6.25 wt.% zirconia toughened alumina/2.5 wt.% nickel composite material. Results showed that tensile strength and hardness of EN31 steel alloy improved about 46.17 % and 100.20 % respectively after adding 6.25 % zirconia toughened alumina and 2.5 % nickel powder. However, ductility reduced by adding the zirconia toughened alumina and nickel powder in EN31 steel alloy. The Finite element analysis has also been carried out to predict the deformation and damage behavior of investigated material during tensile test process. In addition, Brinell hardness test process finite element analysis model is also developed. The finite element analysis results are in good agreement with experimental results with 5 % of percentage difference.     

Determination of stretch zone width using fem

The study addresses numerical determination of stretch zone width and its critical value. The proposed method is based on the highly deformed stretch zone that is defined as stretch zone width, expected to be better than the half of the crack tip opening distance which inturn determined using 45° line method. The investigation essentially comprises a number of finite element analyses of compact tension test, using tensile test data. The proposed methodology also provides insight into the mechanism involved in the creation of stretch zone.     

Proposed Model for Radio Wave Attenuation due to Rain (RWAR)

Radio wave attenuation is primarily caused by the absorption of a radio signals by some atmospheric phenomenon like rain, snow or ice, clouds, dust etc. These losses are more prevalent in the frequency ranges above 10 GHz. Attenuation caused by rain is not only limited to satellite up-link and down-link but it can also affect the point-to-point terrestrial microwave links above 10 GHz. This paper briefly discussed about the work done by researchers at different parts of the world regarding the attenuation caused by the rain for higher frequencies. It then proposes a mathematical model for prediction of radio wave attenuation due to rain. The implementation results of proposed model were also compared with the ITU-R model.

     

Doping Dependent In‐Plane and Cross‐Plane Thermoelectric Performance of Thin n‐Type Polymer P(NDI2OD‐T2) Films

Thermoelectric generators pose a promising approach in renewable energies as they can convert waste heat into electricity. In order to build high efficiency devices, suitable thermoelectric materials, both n‐ and p‐type, are needed. Here, the n‐type high‐mobility polymer poly[N,N′‐bis(2‐octyldodecyl)naphthalene‐1,4,5,8‐bis(dicarboximide)‐2,6‐diyl]‐alt‐5,5′‐(2,2′‐bithiophene) (P(NDI2OD‐T2)) is focused upon. Via solution doping with 4‐(1,3‐dimethyl‐2,3‐dihydro‐1H‐benzoimidazol‐2‐yl)‐N,N‐diphenylaniline (N‐DPBI), a maximum power factor of (1.84 ± 0.13) µW K^?2 m^?1 is achieved in an in‐plane geometry for 5 wt% dopant concentration. Additionally, UV–vis spectroscopy and grazing‐incidence wide‐angle X‐ray scattering are applied to elucidate the mechanisms of the doping process and to explain the discrepancy in thermoelectric performance depending on the charge carriers being either transported in‐plane or cross‐plane. Morphological changes are found such that the crystallites, built‐up by extended polymer chains interacting via lamellar and π–π stacking, re‐arrange from face‐ to edge‐on orientation upon doping. At high doping concentrations, dopant molecules disturb the crystallinity of the polymer, hindering charge transport and leading to a decreased power factor at high dopant concentrations. These observations explain why an intermediate doping concentration of N‐DPBI leads to an optimized thermoelectric performance of P(NDI2OD‐T2) in an in‐plane geometry as compared to the cross‐plane case.     

LTE channel throughput assessment and comparison under different terrain

In evolved UMTS terrestrial radio access network, long‐term evolution is known as the fourth‐generation mobile network with a leading radio performance metric as a throughput and signal‐to‐noise ratio (SNR) that affect the radio links. In this paper, we analytically describe the different long‐term evolution propagation model and measure and compare the throughput and SNR on different Doppler frequencies. To validate the performance of channel, we implement network on 3 standard models, viz, as pedestrian (EPA), vehicular (EVA), and typical urban (ETU) at different Doppler frequency (5, 70, 300, and 750 Hz), and different value of SNR (10, 13, 16, and 19 dB) on downlink channel and measured the channel throughput rate. We conclude that a performance of the channel for high SNR values severely affected by the high value of the Doppler frequency while for the channels at low SNR values is a negligible effect with high Doppler frequency.