Differential Scanning Calorimetry Thermogravimetric Analysis Research Articles

Preliminary Study on Characteristics of NC/HTPB-Based High-Energy Gun Propellants

This study mainly explored the characteristics of NC/HTPB-based high-energy gun propellants with RDX, CL-20 or TKX-50 by experimental method. Three series of test samples were prepared referring to the formulation of M1 single-base gun propellant (M1 SBP). The thermochemical characteristics, chemical stability, explosion heat, impact and friction sensitivities of prepared samples were determined by simultaneous differential scanning calorimetry–thermogravimetric analysis (STA DSC–TGA), vacuum stability tester (VST), bomb calorimeter (BC), BAM fallhammer and BAM friction tester, respectively, and compared with those of the reference sample M1. The experimental results indicated that the thermochemical characteristics of NC/HTPB-based high-energy gun propellants were similar to those of M1 SBP. The NC/HTPB-based high-energy gun propellants had good chemical stability and were superior to M1 SBP. The explosion heat of NC/HTPB-based high-energy gun propellants was close to and slightly larger than that of M1 SBP. In addition, the NC/HTPB-based high-energy gun propellants had lower impact and friction sensitivities than the M1 SBP. Therefore, the NC/HTPB-based high-energy gun propellants have the potential to replace the M1 SBP. The combustion performances of NC/HTPB-based high-energy gun propellants will be continuously studied and verified in the future.

Influence of sodium-based activators and water content on the fresh and hardened properties of metakaolin geopolymers

Several studies explore optimal molar oxide ratios for metakaolin geopolymer production. However, there is not a consensus on the optimal mix, and within similar range large differences in compressive strength are reported, and consequently in the overall performance. Hence, the present work selects a specific molar oxide ratio that leads to strengths above 30 MPa (SiO2/Al2O3 ratio of 3.19, a Na2O/Al2O3 of 1.00, and a water-to-solids ratio of 0.52), and investigates the individual effect of the sodium-based activators (NaOH and Na2SiO3) and the water content on fresh and hardened properties of metakaolin geopolymers. The tested properties include the rheology, setting time, mass loss, shrinkage, density and compressive strength. The test results show that an increase of water content (water-to-solids > 0.52) and increase of NaOH (Na2O/Al2O3 > 1.03) have the largest impact, showing a detrimental effect on both fresh and hardened properties. Moreover, the best results are obtained when using molar ratios of SiO2/Al2O3 at 3.14, Na2O/Al2O3 at 0.97 and a water-to-solids ratio of 0.51, which is within the range of optimum molar ratios from previous studies. The tests are further supplemented by Thermogravimetric analysis/Differential scanning calorimetry (TGA/DSC), scanning electron microscopy (SEM), and X-ray diffraction (XRD).

Characterization of a novel polysaccharide from red ginseng and its ameliorative effect on oxidative stress injury in myocardial ischemia

BackgroundRed ginseng (RG) was widely used as traditional Chinese medicine (TCM) or dietary supplement. However, few researches had been reported on the red ginseng polysaccharide (RGP).MethodsIn this study, a novel heteropolysaccharide named RGP1-1 was fractionated sequentially by DEAE-52 column and Sephadex G-100 gel column. The primary structure of RGP1-1, including glycosyl linkages, molecular weight, monosaccharide composition, morphology and physicochemical property were conducted by nuclear magnetic resonance (NMR), gas chromatography-mass spectrometer (GC–MS), atomic force microscope (AFM), scanning electron microscope (SEM), differential scanning calorimetry-thermogravimetric analysis (DSC-TG) and so on. The effect of RGP1-1 in preventing and treating myocardial ischemia was evaluated by an animal model isoprenaline (ISO) induced mice.ResultsRGP1-1, with a homogeneous molecular weight of 5655 Da, was composed of Glc and Gal in the ratio of 94.26:4.92. The methylation and NMR analysis indicated the backbone was composed of → 1)-Glcp-(4 → and → 1)-Galp-(4 →, branched partially at O-4 with α-D-Glcp-(1 → residue. Morphology and physicochemical property analysis revealed a triple-helical conformation, flaky and irregular spherical structure with molecule aggregations and stable thermal properties of RGP1-1. And it contained 6.82 mV zeta potential, 117.4 nm partical size and polymerization phenomenon. Furthermore, RGP1-1 possessed strong antioxidant activity in vitro and in vivo, RGP1-1 could decrease cardiomyocyte apoptosis and myocardium fibrosis of mice in histopathology and it could decrease significantly the serum levels of cardiac troponin (cTnI), aspartate aminotransferase (AST), lactate dehydrogenase (LDH), malondialdehyde (MDA). Western blot analysis showed that RGP1-1 can increase the expression of main protein Nuclear factor E2-related factor 2(Nrf2), NAD(P)H:quinone oxidoreductase 1 (NQO1), heme oxygenase-1(HO-1) and kelch-like ECH-associated protein1(keap1) in oxidative stress injure progress, and therefore regulate the pathway of Nrf2/HO-1.ConclusionThe above findings indicated that RGP1-1 had an improving effect on ISO-induced myocardial ischemia injury in mice, as novel natural antioxidant and heart-protecting drugs.

Study on the Combustion Characteristics of Mountain Forest Vegetation

Leaves from four common tree species in Chinese mountain forests, namely, Symplocos setchuensis Brand, Tarenna mollissima, Loropetalum chinense, and Castanopsis sclerophylla were studied to assess their ignitability. The microstructure of each sample was determined to investigate its effect on combustion performance. Differential thermogravimetric analysis–differential scanning calorimetry (DTA–DSC) was performed to characterize thermal decomposition processes and relate them to flammability and fire resistance. In addition, pyrolysis reaction kinetic models were built, and fitting results were obtained in order to estimate the ignitability of the different abovementioned tree types. In this paper, the activation energy of the lignin decomposition stage was used to determine the fire hazard and ignitability. Regression analysis and correlation tests of microstructural parameters were performed. The results indicated that Castanopsis sclerophylla possessed the greatest fire hazard, followed by Loropetalum chinense, Tarenna mollissima, and Symplocos setchuensis Brand. The results of this study can provide a practical basis for the selection of fire-resistant tree species and forest belts.

Greener Procedure of Dithizone Immobilization on Coal Bottom Ash for Heavy Metal Adsorbent: Synthesis Optimization and Characterization

In the present study, new greener approach of dithizone immobilization on coal bottom ash as a source of silica-alumina materials in alkaline (NaOH) solution has been developed to replace previously used method utilizing more toxic solvents such as toluene, carbon tetrachloride or chloroform. Some parameters influencing the effectiveness of dithizone immobilization including reaction time, concentration of NaOH solution as well as washing procedures were optimized. FTIR (Fourier Transform Infra-Red), XRD (X-Ray Diffraction) and DSC/TGA (Differential Scanning Calorimetry/Thermogravimetric Analysis) analysis were employed to characterize the obtained materials. The adsorbents also tested for the adsorption of Pb(II) ion. Results suggest the use of greener alkaline medium has doubled the effectiveness of dithizone immobilization on the surface of coal bottom ash and hence enhances the capacity and selectivity of adsorbent towards heavy metals.

The Use of Recycled PET for the Synthesis of New Mechanically Improved PVP Composite Nanofibers

Polyethylene terephthalate (PET) waste has become a major challenge for the conservation of the environment due to difficult degradation. For this reason, it is important to develop new recycling strategies for reusing this waste. In this work, the electrospinning technique was used to synthesize composite nanofibers of polyvinylpyrrolidone (PVP), recycling PET (RPET) that was obtained from the chemical recycling of postconsumer PET with glycolysis and styrene (ST) as a crosslinking agent. The polymer solutions were analyzed by viscosity and frequency sweeping, while the composite nanofibers were characterized by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis/differential scanning calorimetry (TGA/DSC), and nanoindentation to compare their properties. The PVP nanofibers presented an average diameter of 257 nm; the RPET/PVP and RPET/PVP/ST composite nanofibers had average diameters of 361 nm and 394 nm, respectively; and the modulus of elasticity and hardness of the RPET/PVP/ST composite nanofibers were 29 and 20 times larger, respectively, than those of the PVP nanofibers. With the synthesis of these composite nanofibers, a new approach to PET recycling is presented.

Co-pyrolysis of sewage sludge and sodium lignosulfonate: Kinetic study and methylene blue adsorption properties of the biochar

Co-pyrolysis of sewage sludge (SS) and lignin is a promising method to dispose of SS and obtain valuable biochar, however, the synergy effect has been rarely reported. In this paper, lignin of sodium lignosulfonate (SL) was blended with SS for co-pyrolysis. Thermogravimetric analyzer/differential scanning calorimetry (TGA/DSC) was used to investigate the reaction kinetics during co-pyrolysis. And the adsorption performance of co-pyrolysis biochar on methylene blue (MB) was determined. Results showed that the SS decomposition was promoted with SL addition. Kinetic analysis using the Coats-Redfern method indicated the reaction order model to be the primary pyrolysis kinetic mechanism. The synergistic effect of promotion was caused by catalytic metals, and inhibition was caused by ash and tar adhesion. The specific surface area of biochar was improved during co-pyrolysis from 62.53 to 243.22 m2 g−1, while SL ratio of 80% achieved the maximum specific surface area. Co-pyrolysis showed an inhibition effect on porosity formation when SL ratio was below 60%, while a promotion effect was found when SL ratio exceeded 60%. Co-pyrolysis elevated the MB adsorption capacity of SS-derived biochars from 12.48 to 154.06 mg g−1, and was indicated as a promising method for adsorbents production.

Synergetic effect of co-pyrolysis of sewage sludge and lignin on biochar production and adsorption of methylene blue

Much attention has been drawn to co-pyrolysis of sewage sludge (SS) and biomass, to obtain high-quality biochar by combining the favorable properties of both feedstocks. In our study, pyrolysis of SS, lignin and their mixtures (weight ratio of 50%) were carried out in a fixed bed reactor and thermogravimetric analyzer/differential scanning calorimetry (TGA/DSC). The synergy of feedstocks during co-pyrolysis at 400 ℃, 600 ℃ and 800 ℃ was investigated. The experiments were designed using response surface methodology (RSM) to investigate the influence of temperature, retention time and doping ratio on the biochar yields and their adsorption capacity of methylene blue (MB). From the TG results, decomposition of the mixture was promoted by the synergetic effect, and the reaction temperature was reduced from 741 ℃ to 688 ℃. DSC curves proved the synergetic reaction being endothermic around 750 ℃. The biochar yields varied between 0.46 and 0.75, while the MB adsorption capacity varied between 3.06 and 38.56 mg g−1. The MB adsorption capacity was improved by the synergy effect. The excellent MB adsorption property of biochar was attributed to abundant function groups produced at 400 ℃ (OH, CH, and C = O) and elevated specific surface areas at 800 ℃ (33.59 m2 g−1).

Co-pyrolysis biochar derived from sewage sludge and lignin: Synergetic effect and adsorption properties

Co-pyrolysis of sewage sludge (SS) and biomass is expected to improve the biochar quality. Lignin as a major component of biomass was selected for co-pyrolysis with SS. The characteristics and kinetics of co-pyrolysis were studied by thermogravimetric analyzer/differential scanning calorimetry (TGA/DSC) and Coats-Redfern method; the effects of pyrolysis temperature and mixing proportion on the biochar yield were investigated via muffle furnace experiment, and the porosity and methylene blue (MB) adsorption capacity of the obtained co-pyrolysis biochar were evaluated. The results showed that co-pyrolysis promoted the decomposition of mixture and reduced the reaction temperature. The reaction order model was the primary mechanism model for co-pyrolysis, and both promotion and inhibition effects were observed based on the obtained activation energy. At 400 ℃ and 600 ℃, the co-pyrolysis synergetic effect on biochar yield was weak, and synergy effect of inhibition on the porosity of biochar was caused by tar and ash adhesion. When temperature was elevated to 800 ℃, catalytic effect of alkali and alkaline earth metals (AAEMs) dominated the synergetic effect, promoted char decomposition, meanwhile, pores were dramatically developed. Co-pyrolysis of SS and lignin improved MB adsorption capacity of SS biochar from 14.04 mg g−1 to 180.36 mg g−1, indicating it to be a prospective method for waste to valuable biochar production.

Structural Characteristics of Insoluble Dietary Fiber from Okara with Different Particle Sizes and Their Prebiotic Effects in Rats Fed High-Fat Diet.

Dietary fiber, which is utilized to make functional meals, is an important component for promoting human health and managing calorie consumption. In this study, three different particle sizes of OIDF (Okara insoluble dietary fiber) were characterized. Their lipid-lowering effects and the impacts on gut microbiota were determined by OIDF intervention in high-fat diet rats. Scanning electron microscopy (SEM) results showed that the three particle sizes of OIDF have different morphologies. Fourier transform infrared spectroscopy (FT-IR) results showed that the three sources of IDF samples have similar active groups, but the thermogravimetric analysis/differential scanning calorimetry (TGA/DSC) and X-ray diffraction (XRD) showed that three different particle sizes of OIDF have different retention and crystallinity. Among the three OIDFs, OIDF-10 exhibited the stronger WSC, OHC, CAC, and SCAC. The results after the feeding showed that the OIDF of three particle sizes could improve the elevation of blood lipids and the disturbance of gut microbiota caused by the high-fat diet. Therefore, this study demonstrated the functional significance of the three particle sizes of OIDF and provided a reference for its application in functional food processing, aiming at maintaining healthy blood lipid and intestinal flora levels.

Microstructure and magnetic properties of FeSiCr soft magnetic powder cores with a MgO insulating layer prepared by the sol-gel method

In this study, the electromagnetic properties of FeSiCr soft magnetic powder cores (SMPCs) were optimized by providing a novel insulation process. Magnesium acetate tetrahydrate and oxalic acid dihydrate were used as raw materials for the sol-gel method. The powder was then heat-treated at 700 °C so that it was evenly coated by an insulating layer. Thermogravimetric analysis-differential scanning calorimetry, X-ray diffraction, Fourier transform infrared spectroscopy, and energy dispersive spectroscopy were used to demonstrate that the layer heat-treated at 700 °C was the ideal MgO layer and was uniformly coated on the surface of the FeSiCr powder. Additionally, the potential reactions and growth mechanism of the MgO layer were analyzed. The effects of the magnesium acetate tetrahydrate content on the soft magnetic properties of the FeSiCr@MgO SMPCs were investigated. The optimal soft magnetic performance (Pcv = 248.48 mW/cm3, measured at 2500 kHz and 10 mT) was achieved at a magnesium acetate tetrahydrate content of 0.50 wt%, yielding a direct current-bias performance of up to 92.3% at 100 Oe. In addition, the FeSiCr@MgO SMPCs effectively improved the heat dissipation performance, which is necessary to avoid high-temperature damage, thereby enhancing their applicability in high-frequency and high-current environments.

Fabrication and characterization of lysine hydrochloride Cu(ii) complexes and their potential for bombing bacterial resistance

Abstract The emergence of drug-resistant bacteria and the lack of effective antimicrobial agents have posed a threat to public safety, so a new efficient strategy is needed to deal with the increasing severity of bacteria. Herein, a substitute antibacterial agent with high stability and biocompatibility was synthesized by incorporating lysine hydrochloride and copper sulfate pentahydrate following the liquid-phase synthesis method. The composition and structure of the Cu(ii) complex (Lys–Cu) were characterized by performing ultraviolet-visible spectrophotometry, Fourier-transform infrared spectroscopy, X-ray diffractometry (XRD), thermogravimetric analysis-differential scanning calorimetry, and single-crystal XRD. The crystal structure of Lys–Cu belongs to a monoclinic system, space group P21, with cell parameters of a = 5.14350(10), b = 16.8308(2), c = 11.4915(2) Å, Z = 2, and D = 1.548 g·cm−3. Bacteriostatic tests were carried out on Escherichia coli and Staphylococcus aureus. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) values of Lys–Cu against S. aureus were 0.3125 and 0.9250 mg·mL−1, respectively. The MIC and MBC values of Lys–Cu against bacterial strain E. coli were 0.4685 and 0.9250 mg·mL−1, respectively.

Microstructure, Thermal and Mechanical Properties of Refractory Linings Modified with Polymer Fibers

The reduction in the inherent brittleness of coatings applied on parts of ceramic shielding used for continuous steel casting (CSC) processes is highly desired, since it can significantly diminish losses occurring during post-application handling and mounting. One of such coatings, prepared mostly from fused silica, ludox, tabular alumina, chamotte, cenospheres, dextrine and aluminum powder, is known commercially as Thermacoat™. The present experiment is focused on the effect of the modification of its composition by rising the content of the cenospheres (max. 2.5 wt.%) or by introducing up to 1.5 wt.% of polymer Belmix™ fibers (~34 μm diameter/12 mm length) on the microstructure and mechanical properties. The maximum amount of introduced additions was limited by the accompanying loss of mass viscosity, which must allow for deposition through immersion. Next, the differential scanning calorimetry and differential thermogravimetric analysis techniques were employed to evaluate the extent of the weight change and heat response of the mass during the drying and annealing stages. The dried materials’ microstructure was investigated with light and scanning electron microscopy, while the chemical composition was studied by energy dispersive spectroscopy. Finally, a three-point flexural bending method was used to determine changes in the material mechanical properties. The performed experiments proved that the small addition (~1 wt.%) of polymer fibers is sufficient for the significant improvement of the Thermacoat™ green mechanical strength at ambient temperature, presenting a reproducible ultimate flexural strength of ~0.2 MPa.

Investigation on the influence of AC electric filed and KCl on the structure and gel properties of Konjac glucomannan

The influence of alternating current (AC) electric field and KCl on the structure and gel properties of Konjac Glucomannan (KGM) were studied in this work by high-performance gel permeation chromatography (HPGPC), acid-base titration, solid-state nuclear magnetic resonance (NMR), X-ray diffraction (XRD), simultaneous differential scanning calorimetry/thermo gravimetric analyzer (DSC/TGA) and a rheometer. HPGPC showed KGM was degraded by AC electric field and Acid-base titration showed that under the action of AC electric field and KCl KGM removed part of acetyl groups, which were consistent with the analysis of NMR. XRD and temperature sweep measurements respectively showed that the electrotreatment time and KCl concentration had important effects on the gel formation and its three-dimensional network. Simultaneous DSC/TGA and temperature sweep measurements both demonstrated the gel had good thermal stability.

Synthesis and characterization of nitrogen-rich polybenzoxazines for energetic applications

In a vision to develop new synthetic routes for the preparation of energetic materials, two new energetic benzoxazine monomers were synthesized via a two-step Mannich reaction process involving the incorporation of nitrogen–nitrogen bonds and explosophore groups (NO2) into the monomer backbone. The molecular structures of the synthesized monomers were confirmed by 1H NMR, Fourier transform infrared and elemental analysis techniques. The curing behavior and the degradation phenomena were evaluated by differential scanning calorimetry-thermogravimetric analysis analyses. The two monomers showed two distinct exothermic peaks related to the polymerization and degradation phases. The energetic performances were evaluated by determining the heat of combustion and formation using a bomb calorimeter, in an oxygen atmosphere. The results indicated that the 2,4 dinitrophenylhydrazine–based benzoxazine has better energetic properties than the phenylsemicarbazide-based benzoxazine, and the two developed polymers showed comparable performances with nitrocellulose and glycid azide polymer. Overall, this study has demonstrated that the ease of synthesis of the benzoxazine resins via Mannich reaction can be further extended to the energetic field and further research is undergoing to fully unravel the potential of these exceptional materials.

Model-based compositional predictions for a differential scanning calorimetry/thermogravimetric analysis-mass spectrometry system used for heat of vaporization measurements

A Differential Scanning Calorimetry/Thermogravimetric Analysis (DSC/TGA) procedure for determination of Heat of Vaporization (HOV) of fuel and surrogate fuel mixtures has been previously utilized for evaluation of oxygenate impacts on spark ignition fuels. This analysis has been further leveraged with mass spectrometry (MS) to elucidate vapor phase compositional changes during evaporation. In this article we focus on a simple system of three compounds (ethanol, n-hexane, and n-octane) to provide a model-based understanding of the evaporation process under these experimental conditions. An Aspen Plus model was set up to provide liquid and vapor phase concentration predictions during mixture evaporation using the initial mixture composition, and measured temperature and mass loss profiles from DSC/TGA experiments. Agreements between the trends of the MS ion count profiles and model composition predictions provide a degree of validation of this modeling approach that can allow the interpretation and extrapolation of DSC/TGA measurements for more complex fuel mixtures.

Induction Heating of Magnetically Susceptible Nanoparticles for Enhanced Hydrogenation of Oleic Acid.

Radio frequency (RF) induction heating was compared to conventional thermal heating for the hydrogenation of oleic acid to stearic acid. The RF reaction demonstrated decreased coke accumulation and increased product selectivity at comparable temperatures over mesoporous Fe3O4 catalysts composed of 28–32 nm diameter nanoparticles. The Fe3O4 supports were decorated with Pd and Pt active sites and served as the local heat generators when subjected to an alternating magnetic field. For hydrogenation over Pd/Fe3O4, both heating methods gave similar liquid product selectivities, but thermogravimetric analysis–differential scanning calorimetry measurements showed no coke accumulation for the RF-heated catalyst versus 6.5 wt % for the conventionally heated catalyst. A different trend emerged when hydrogenation over Pt/Fe3O4 was performed. Compared to conventional heating, the RF increased the selectivity to stearic acid by an additional 15%. Based on these results, RF heating acting upon a magnetically susceptible nanoparticle catalyst would also be expected to positively impact systems with high coking rates, for example, nonoxidative dehydrogenations.

Room-temperature catalytically reactive ammonium dinitramide–H2O2 monopropellant for microsatellites

Room-temperature catalytically reactive ammonium dinitramide (ADN)-based green monopropellants are interesting for space applications, particularly for microthruster applications. In this study, a blend of ADN and 90-wt% hydrogen peroxide monopropellant was developed and its catalytic reactivity was investigated at different temperatures. An optimal ADN–hydrogen peroxide monopropellant (AHMP) was fabricated at a weight ratio of 40:60 wt:wt (ADN:90-wt% H2O2). The theoretical vacuum specific impulse of AHMP was 206 s, 20% higher than the specific impulse (172 s) of 90-wt% hydrogen peroxide. The thermal properties of AHMP were evaluated using thermogravimetric analysis–differential scanning calorimetry, which revealed that thermal behavior of AHMP containing ADN and 90-wt% hydrogen peroxide was similar to their pure compound. The storability of AHMP was estimated using Fourier-transform infrared spectroscopy and nuclear magnetic resonance spectroscopy. Notably, AHMP could be stored at low temperatures (2–3 °C) for 4 months and at room temperature (20–23 °C) for 1.4 months without chemical changes. Furthermore, drop test and microthruster test were performed to determine the reactivity of AHMP with a catalyst (Pt/La/Al2O3). The response time of the catalyst on the decomposition of AHMP was approximately 104.6, 24.8, and 7.0 ms at 23, 60, and 120 °C, respectively. This study on the AHMP green monopropellant paves the way for further studies on improved ADN–hydrogen-peroxide-based monopropellants for microthruster applications.

Synergistically improved thermal stability and electromagnetic interference shielding effectiveness (EMI SE) of in-situ synthesized polyaniline/sulphur doped reduced graphene oxide (PANI/S-RGO) nanocomposites

Polyaniline (PANI) and its composite with sulphur doped reduced graphene oxide (S-RGO) have been successively synthesized via in-situ chemical oxidative polymerization of aniline in presence of 10 wt. % S-RGO nanosheets. Physico-chemical analyses of the synthesized nanomaterial was performed with various characterization techniques such as X-Ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscopy (SEM), Energy Dispersive X-Ray Spectroscopy (EDS), Atomic Force Microscopy (AFM) and Thermogravimetric analysis/Differential Scanning Calorimetry (TGA/DSC). The results interpreted from the various characterizations confirm the doping of RGO with sulphur as well as strong interaction of PANI nanofibers and S-RGO nanosheets. TG/DSC curves confirm the enhanced thermal stability of polyaniline/sulphur doped reduced graphene oxide (PANI/S-RGO) nanocomposites with heat resistance index (THRI) of 155.2 °C in comparision to pure PANI (THRI= 145.3 °C) at a filler loading of 10 wt. %. TGA validates that thermal stability of PANI/S-RGO nanocomposite improves by 6–7 °C than pure PANI in terms of weight loss percentage at a temperature of 1117 °C. However DSC analysis confirms that PANI/S-RGO retains its structural integrity and conformity to temperatures as high as 900 °C beyond which the polymer composite starts to degrade. The electromagnetic interference shielding effectiveness (EMI SE) of PANI and PANI/S-RGO nanocomposites were measured via open-ended coaxial probe set-up connected to a Vector Network Analyser (VNA) at a broadband frequency range of 1–20 GHz (1000–20000 MHz). For EMI SE measurements the various nanomaterials were incorporated into paraffin wax and made into composite pellets of thickness 5 mm by solution casting technique. The dielectric properties, electrical conductivity and EMI SE were all greatly enhanced for the PANI/S-RGO/Paraffin composite pellets. The as synthesized PANI/S-RGO/Paraffin composite pellets exhibited highest EMI SE of −22.5 dB (>99%) as compared to −15.89 dB of PANI/Paraffin composite pellets. The prepared composite pellets revealed an absorption dominant mechanism of shielding with highest SEA of −14.6 dB for PANI/S-RGO/Paraffin composite pellets.

Dissolution and Bio-compatibility of ZnO Doped Bioactive Glasses after In Vitro Experiment

This work presents the study of 60SiO2-(36-x)CaO-4P2O5-xZnO (x=1, 3, 5 mol.%) glasses synthesized by a modified sol-gel method based on a hydrothermal reaction. The thermal morphology of the glass systems was evaluated by the Thermogravimetric analysis-differential scanning calorimetry (TG-DSC) method. The in vitro assay for dissolution was evaluated by the Inductively coupled plasma-optical emission spectroscopy (ICP-OES) method. Biocompatibility testing was performed with L-929 fibroblast cells. The results show that the ZnO-doped glass systems show good bioactivity and biocompatibility.