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The polymerization of Ethyl methacrylate has been carried out via, the conventional bulk polymerization techniques. The polymerization of ethyl methacrylate was easily done by conventional method. The polymer is used in various applications such as an oil additive, in paper, coating, adhesive, textiles, drug delivery and biomedical fields. Conventional bulk polymerization method has been used for the synthesis of poly (ethyl methacrylate), as highly pure polymer is obtained by this method. The effect of change of temperature during the bulk polymerization of ethyl methacrylate has not been reported in detail to the best of our knowledge. In this paper, we have studied the effect of temperature on bulk polymerization of ethyl methacrylate under free radical conditions.

Fresh-water comes from the rain which finally goes into the ocean via rivers. The human beings store this water and use it in a variety of purposes such as drinking, washing, irrigation and in industries etc., Wastewater is generated after the utilization of pure water in domestic, industrial, agricultural, municipal and other activities. The growing population and urbanization are the principal reason of continuous increase in wastewater generation. Wastewater contains a number of contaminants like organic materials, biological components and toxic inorganic compounds which cause adverse effect on the human health. Many inorganic chemicals are conventionally used as coagulant for the treatment of wastewater. Theses coagulants have the ability to change the physico-chemical properties of the treated water. In this review paper, we have described the used of naturally-occurring polymers as coagulants in wastewater treatment. These coagulants have more potential for coagulation and are also eco-friendly and biodegradable in nature; moreover, these coagulants do not adversely affect the human health and do not induce change in the physico-chemical properties of treated water.

The current study investigates the comparative study of similar pulsed Nd:YAG laser welding of 304L and 904L stainless steel. In the present study both austenitic stainless steel (304L) and super austenitic stainless steel (904L) are laser welded at 5 mm/s scanning speed, 25 Hz pulse frequency and 0.75 mm laser spot diameter. The ultimate tensile strength of both laser welded specimens were equal to the respective parent metals. The percent of ductility is more in 304L than 904L laser welded specimen comparatively. The weld bead shape of the two welded specimens are V shaped for 304L and H shaped for 904L at the same laser process parameters due to difference in thermophysical properties of the two materials.

In this study, a composite mesoporous silica material MCM-41 (Mobil composite matter) is impregnated with monoethanolamine (MEA) as primary linear amine, benzylamine (BZA) as primary cyclic amine and N-(2-aminoethyl) ethanolamine (AEEA) as secondary diamine and the effects of amine loading, amine type, CO2 partial pressure and adsorption temperatures on the CO2 adsorption are investigated. The CO2 adsorption performances of MCM-41 and amine impregnated MCM-41 samples are studied up to 1 bar of CO2 partial pressure and the temperature range of 25–60 °C. The amine loadings (% impregnation) are optimized for maximum CO2 uptake. The materials are characterised using N2 adsorption/desorption isotherm, Fourier Transform Infrared (FT-IR) Spectroscopy, Thermogravimetric (TGA) and Elemental (CHNS) analysis. The materials have shown good structural and thermal stability. The MCM-41-40%AEEA, MCM-41-40%BZA and MCM-41-50%MEA samples are exhibited the CO2 adsorption capacity of 2.34 mmol/g (102.98 mg/g), 0.908 mmol/g (39.96 mg/g) and 1.47 mmol/g (64.69 mg/g) respectively. The CO2 uptake of MCM-41-40%AEEA is 3.5 times higher than that of in MCM-41 (0.68 mmol/g) and it is also the highest reported value as di-amine impregnated MCM-41. The results indicated that the adsorption capacities of the materials (MCM-41 and MCM-41-40%AEEA) are decreased with an increase of adsorption temperature in the range of 25–60 °C. The Freundlich, Langmuir, Sips and Toth isotherm models are used to correlate and predict experimental CO2 adsorption data. The Sips and Toth isotherm models are found to be better fitted with the experimental data. The isosteric heat of adsorption of MCM-41 and MCM-41-40%AEEA samples are also calculated from Van’t Hoff plot using iSorbHP-win instrumental analysis software in the experimental temperature range.

Herein a one-step, easy, cheap and eco-friendly Solvothermal synthesis method has been used to synthesize monodisperse, uniform and ultrasmall chromium oxide (Cr2O3) nanocrystals (NCs). Transmission electron microscope (TEM) image of as-prepared Cr2O3 NCs shows the spherical shape with a uniform size of ∼4.5 nm. The oxidation state of chromium ion has confirmed by absorption as well as electron paramagnetic resonance (EPR) spectroscopy. Magnetic properties of as-synthesized NCs show low-temperature antiferromagnetic (AFM) exchange with Currie-Weiss (C-W) temperature ϴ = −160 K. Further, nearest neighbour exchange coupling constant JNN has found to be −16 K (Here K is Boltzmann constant) for Cr2O3 NCs by considering the nearest neighbours (Z) is 4.

In this paper, authors report a facile synthesis of reduced graphene oxide-ZnO (rGO-ZnO) nanocomposite via the solvothermal method for excellent electromagnetic interference (EMI) shielding application. Various characterization tools such as Transmission Electron Microscope (TEM), X-ray diffractometer (XRD) and Raman spectroscope have been employed to understand the morphology and crystal structure of rGO-ZnO nanocomposite, which clearly reveals ZnO nanoparticles (with average size ∼25 nm) to get dispersed well over the surface of rGO. These ZnO nanoparticles, assembled over the top of rGO sheets, form an rGO-ZnO heterostructure with enhanced polarization centers. ZnO nanostructures not only prevent rGO nanosheets to agglomerate but also to contribute significantly in improved scattering, dielectric loss, and impedance matching properties of heterostructure nanocomposite. EMI shielding properties of rGO-ZnO nanocomposites have been evaluated in X-band frequency range (8–12 GHz) and indicate clearly that rGO-ZnO (SET ∼ 38 dB) nanocomposite exhibits an excellent shielding property as compared to its constituent components (SET ∼ 22 dB for rGO and ∼4 dB for ZnO nanoparticles, respectively). Variation of real and imaginary parts of permittivity and permeability provides the idea of attenuating rGO-ZnO nanocomposite. Moreover, it's dielectric and magnetic loss parameters demonstrate the impedance matching characteristics of the rGO-ZnO nanocomposite.

Unmanned Aerial Vehicle (UAV) networks can provide wireless coverage to users when cellular infrastructure is unavailable. Each UAV covers a circular area, called a hotspot cell, and serves the users in it. Natural disasters can cause unpredictable mobility of users, randomly overloading some cells, called hot zones, for different time intervals. Along with an efficient initial deployment, this paper presents a two-fold approach to handle hot zones. First, the loads in overlapped sections are redistributed to neighbors. Second, a distributed algorithm is run that dynamically repositions the least number of UAVs to serve the maximum possible users. Additionally, to balance the user demand and supply of wireless coverage, adjacent UAVs are allowed to swap their positions. Simulation results show improvement in the network performance using the parameters: packet delivery ratio, data served per unit of depleted energy, service discontinuity time, and the total amount of data served.

Providing wireless coverage to users using Unmanned Aerial Vehicles (UAVs) encounters two major challenges: deployment and channel allocation. To this end, solutions to both issues are proposed in this paper. An overloaded UAV attempts to acquire more channels by performing channel bonding/aggregation followed by requesting its chosen peers to move closer for load sharing. The proposed channel reallocation schemes minimize interference caused by channel reassignments, or change in network topology. The simulation results show that when employing these schemes, more data is served with reduced discontinuous service time and efficient usage of limited battery power.

Linz-Donawitz(LD) slag Geopolymer(LDSGP), a porous aluminosillicate geopolymeric adsorbent, has been synthesized from steel plant LD slag for efficient removal of Zinc(II) ions from wastewater, thus presenting a solution for converting industrial waste to adsorbent for wastewater treatment. The colloid paste of raw LD slag and the alkaline activator (10 M NaOH + sodium silicate (1:1 w/w)) has been cured for 3 days at low temperature to geopolymerize the calcium oxide rich LD slag. The BET surface area of LDSGP adsorbent (30.84 m2/g) has improved considerably compared to raw LDS (4.85 m2/g) and the FESEM and HRTEM images reveal the presence of micropetal and cauliflower like structures at outer surface of the adsorbent particles. The mesoporous nature of LDSGP adsorbent can be understood by analyzing N2 adsorption-desorption and pore size distribution plot. The PXRD pattern of LDSGP adsorbent powder confirms the presence of Ca2SiO4 and Ca3SiO5 in the geopolymeric matrix. Langmuir isotherm model correlates the batch adsorption data of Zn2+ ions onto LDSGP particles at 298 K, 308 K and 318 K. The maximum Zn2+ ions adsorption capacity of LDSGP is 86 mg/g at 318 K. The adsorption kinetic data is correlated with pseudo-second-order model indicating chemisorption of Zn2+ ions onto LD slag geopolymeric powder adsorbent.

This paper presents the study of microstructure and mechanical properties of pulsed Nd:YAG laser welding st37 carbon steel. In this work carbon steel st37 is laser welded in butt joint configuration at welding speed of 5mm/s, pulse frequency of 25Hz, pulse width of 5ms and spot size of 0.75mm, resulting the ultimate tensile strength of the welded specimen equal to the base metal. The effect of recrystallization has also been noticed in the welded joint as the fine grains were present in HAZ and coarse grains were found in the fusion zone. The ductile failure of the welded joint was observed under tensile loading. The microhadness of the fusion zone was 192HV which was more compared to HAZ and base metal due to the presence of few martensite.

Herein, we report synthesis of a novel ZnO/Geopolymer nanocomposite photocatalyst with highly efficient photocatalytic properties under visible-light irradiation. It has been synthesized by facile hydrothermal method which includes incorporation of ZnO nano-spheres uniformly, onto mesoporous geopolymeric base material. LD (Linz-Donawitz) slag, a steel industry waste, has been geopolymerised for preparing this mesoporous support material, named as LD slag based geopolymer (LDSGP). The physical, optical and electrochemical properties of the ZnO/Geopolymer (ZnO/LDSGP) photocatalyst have been analyzed using standard characterization methods. ZnO/LDSGP nanocomposite has nano-spherial morphological structures with high crystallinity, having visible light sensitivity, with photo-current density as 0.45 mA/cm2. The optical band gap reduces from 3.37 (commercial ZnO) to 2.95 eV (ZnO/LDSGP). The photocatalytic properties of ZnO/LDSGP have been evaluated for degradation congo red (CR) by correlating with first-order reaction kinetics. A probable CR photo-degradation mechanism by ZnO/LDSGP, has been proposed.

Herein, femtosecond photoluminescence up-conversion (u-PL) spectroscopy has been carried out to elucidate charge carrier relaxation dynamics of the hole in 2 nm copper doped CdS (Cu:CdS) QDs. The hole capturing time at the Cu defect state from the valance band edge of the CdS host appeared significantly faster (437 fs) compared to pure CdS QDs (670 fs). This faster hole capturing in Cu:CdS QDs can compete with Auger-type cooling, and consequently, we can expect slower electron cooling in this system.

In this work, enthalpy of carbon dioxide (CO2) absorption in aqueous hexamethylenediamine (HMDA) and its blend with N-methyldiethanolamine (MDEA) is measured using an automated reaction calorimeter in the temperature range of (30–60) °C. Concentrations of aqueous HMDA solution studied are (10, 20, 30) mass% and that for mixed amine system are (5% HMDA + 25% MDEA), (10% HMDA + 20% MDEA) and (15% HMDA + 15% MDEA). The heat capacity of the unloaded aqueous amine solvents is also measured in the same range of temperature and concentration. The experimental enthalpy of absorption data is presented as a function of CO2 loading (mol CO2 per mol total amine) and temperature. A combined model for the prediction of CO2 absorption enthalpy in aqueous HMDA and (HMDA + MDEA) solvent systems is presented using artificial neural network (ANN) tool. A multi-layer feed-forward network is developed using Levenberg-Marquardt back propagation algorithm. Average absolute deviation between experimental and ANN model predicted data is found to be 0.38%.