Functionalization of halloysite nanotubes with polyethyleneimine and various ionic liquid forms with antimicrobial activity

Halloysite nanotube (HNT), a natural clay, was modified with branched polyethyleneimine (PEI) to form PEI-HNT using epichlorohydrin (ECH) as coupling agent, then protonated with HCl to obtain H-PEI-HNTs providing [NH₃]⁺[Cl]⁻ functionality for potential antimicrobial properties. Upon PEI modification, zeta potential value of HNTs was increased to +37.3 mV from −34.5 mV and to +41.1 mV for H-PEI-HNTs. Only 1.87 wt % H-element in HNT was increased to 3.03 wt % upon PEI modification along with newly generated elements of N and C at 2.99 and 9.93 wt %, respectively. Moreover, ionic liquid (IL) forms of HNTs with [NH₃]⁺[N(CN)₂]⁻, [NH₃]⁺[PF₆]⁻ and [NH₃]⁺[BF₄]⁻ functionality were generated via anion exchange of H-PEI-HNTs with sodium dicyanamide (SDC), ammonium hexafluorophosphate (AHFP), and sodium tetrafluoroborate (STFB). The antimicrobial properties of the modified, protonated, and IL forms of HNTs were determined via macro dilution, diffusion and agar screening tests against Escherichia coli ATCC 8739, Pseudomonas aeruginosa ATCC 10145, Bacillus subtilis ATCC 6633, Staphylococcus aureus ATCC 6538 strains, and Candida albicans ATCC 10231 strains. It was found that H-PEI-HNTs possesses potent antimicrobial effect compared with the other forms of HNTs with 2–4 mg mL⁻¹ MIC and 8–16 mg mL⁻¹ MBC values via the macro dilution method. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48352.     

Controllable hydrogen generation by use smart hydrogel reactor containing Ru nano catalyst and magnetic iron nanoparticles

In this study, p(AMPS) hydrogels are synthesized from 2-acrylamido-2-methyl-1-propansulfonic acid (AMPS) via a photo polymerization technique. The hydrogels are used as template for metal nanoparticles and magnetic ferrite nanoparticles, and also as a catalysis vessel in the generation of hydrogen from the hydrolysis of NaBH₄. Approximately 5 nm Ru (0) and 20-30 nm magnetic ferrite particles are generated in situ inside this p(AMPS) hydrogel network and then used as a catalysis medium in hydrogen production by hydrolysis of sodium boron hydride in a basic medium. With an applied external magnetic field, the hydrogel reactor, containing Ru and ferrite magnetic particles, can be removed from the catalysis medium; providing on-demand generation of hydrogen. The effect of various parameters such as the initial concentration of NaBH₄, the amount of catalyst and temperature on the hydrolysis reaction is evaluated. The activation energy for hydrogen production by Ru (0) nanoparticles is found to be 27.5 kJ mol⁻¹; while the activation enthalpy is 30.4 kJ mol⁻¹. The hydrogen generation rate in presence of 5 wt% NaOH and 50 mg p(AMPS)-Ru catalyst is 8.2 L H₂ min⁻¹ g Ru.     

The on demand generation of hydrogen from Co-Ni bimetallic nano catalyst prepared by dual use of hydrogel: As template and as reactor

We report the preparation of metal nanoparticles in various formulations inside p(2-acrylamido-2-methyl-1-propansulfonic acid; p(AMPS)) hydrogels and their utilization as a catalyst in hydrolysis of NaBH₄. The swollen, flexible p(AMPS) network was used for metal ion loading and reduction in situ for the preparation of Co:Ni nanoparticles as bimetallic clusters in various formulation, and Co and Ni bimetallic catalysts as Co + Co, Co + Ni, Ni + Co and Ni + Ni. In addition to utilization of hydrogels as support materials, the p(AMPS)-metal nanoparticle system was used as catalyst to generate hydrogen in the hydrolysis of NaBH₄ with very high yield. Various parameters for the hydrolysis reaction were determined and the activation parameters were calculated. For the first time, inclusion of ferrite magnetic particles to control hydrogen generation on demand by using an externally applied magnetic field to remove the hydrogel-catalyst system from the hydrolysis medium is reported.     

STRUCTURE PARAMETRE CORRELATIONS ON ALKALI-ALCOHOL TREATED LIGNITE

Abstract

The solubility of the Tuncbilek Lignite is increased up to 100%, on daf. basis, after KOH-Benz-hydrol treatment. Meanwhile its oxygen, sulphur and ash contents are decreased considerably. It has been shown that the solubility, H/C and S/C ratios, as well as the sulphur content of the coal are well correlated with the hydrogen transferred from benzhydrol, whereas the oxygen content does not. The oxygen content correlate with the ash content. A reductive elimination mechanism is suggested for the removal of the hetero-atoms, which also causes the degradation and the increase of the solubility of the coal.     

Determination of optimal hierarchical fuzzy controller parameters according to loading condition with ANN

This paper represents an artificial neural network (ANN) backpropagation algorithm is used to choose best coefficients of hierarchical fuzzy power system stabilizer (HFPSS). PSS is used for stability enhancement of a single machine infinite bus (SMIB) power system. ANN algorithm is used to predict load condition of the power system. And according to the predicted load condition ANN determinates choosing optimal parameters of the hierarchical fuzzy controller (HFC) to achieve better performance. Simulation results are compared with conventional PSS (CPSS) to show the effectiveness of the proposed controller. Also quantitative criterias of measuring performance is computed for 16 loading conditions.     

Characterization of poly(N‐(hydroxymethyl)methacrylamide‐ATU) hydrogels synthesized by γ radiation

Poly(N‐(hydroxymethyl)methacrylamide‐1‐allyl‐2‐thiourea), (poly(NHMMA‐ATU)) hydrogels were synthesized by γ radiation, using ⁶⁰Co γ source at different radiation doses, to change the porosity and crosslinking density of the hydrogels. The percent of 1‐allyl‐2‐thiourea (ATU) in the monomer mixture before the irradiation was varied between 2.5% and 10.0%, to increase the content of ATU, which was involved in some different applications in the hydrogels. Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), elemental analysis, and the swelling experiments were used to characterize the poly(NHMMA‐ATU) hydrogels synthesized in this study. Characterization results of hydrogels showed that crosslinking density of the hydrogels was increased by the increasing radiation dose and ATU content in the irradiated mixture. Swellability of these hydrogels was found to be high enough to allow the metal ions and biomolecules getting inside the hydrogels to interact with all active groups on/in the hydrogels in the adsorption applications. Equilibrium swelling ratio of the hydrogels at pH 0.5 is at least half of the equilibrium swelling ratio of the hydrogels at pH 7.0. Oscillatory swelling behavior of poly(NHMMA‐ATU) hydrogels between pH 0.5 and pH 7.0 showed that the hydrogels are quite stable at different pH conditions. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 99: 1657–1664, 2006     

Flower pollination–feedforward neural network for load flow forecasting in smart distribution grid

Neural Computing and Applications - Nature-inspired population-based metaheuristic flower pollination algorithm is proposed in solving load flow forecasting problem in smart distribution grid...     

Longitudinal vibration of carbon nanotubes with elastically restrained ends using doublet mechanics

Free axial vibration analysis of axially restrained carbon nanotubes (CNTs) is studied within the framework of doublet mechanics theory. Fourier sine series are utilized for describing the axial deflection of the carbon nanotube. An eigenvalue approximation is constructed for vibrational modes with the aid of Stokes’ transformation to deformable axial springs. This unclassified approximation bridges the gap between the deformable and rigid boundary conditions. The comparison studies are carried out to verify the efficiency and accuracy of the proposed analytical model by assigning proper values to elastic spring coefficients. The results indicate that the axial springs and small scale parameter of carbon nanotube have considerable effects on the axial vibration behavior of NTs. Similarly, the dependencies of the vibration frequencies on material scale parameter and axial restraints are significant. Similar higher order effects are predicted for other nano or micro structures, all of that confirmed the smaller is stiffer phenomenon.

     

Field performance measurements of a heat pump desiccant unit in heating and humidification mode

In this study, a novel self-regenerating electric vapor compression heat pump desiccant (HPD) unit operated in the heating and humidification mode during the winter season is introduced. The HPD unit was installed in an office suite for the field test. The performance of the HPD unit and the provided indoor conditions were measured over a wide range of operating conditions. The target indoor humidity ratio was set to 4.4 g/kg, which is the minimum required indoor humidity ratio for a comfortable indoor environment indicated in the ASHRAE winter thermal comfort zone. The seasonal comparison revealed that even though 77.7% of all outdoor humidity ratio data was lower than 4.4 g/kg, 78.2% and 85.8% of all the indoor humidity ratio data of each room were found to be higher than 4.4 g/kg. In addition, due to the significant sensible capacity of the HPD unit, the indoor temperatures could be maintained within 20-25 °C. These results prove that the HPD unit not only properly humidifies the indoors without using any additional water source, like the conventional humidifier, but also helps to keep the indoor temperature at the desired temperature levels.     

STRUCTURE PARAMETRE CORRELATIONS ON ALKALI-ALCOHOL TREATED LIGNITE

The solubility of the Tuncbilek Lignite is increased up to 100%, on daf. basis, after KOH-Benz-hydrol treatment. Meanwhile its oxygen, sulphur and ash contents are decreased considerably. It has been shown that the solubility, H/C and S/C ratios, as well as the sulphur content of the coal are well correlated with the hydrogen transferred from benzhydrol, whereas the oxygen content does not. The oxygen content correlate with the ash content. A reductive elimination mechanism is suggested for the removal of the hetero-atoms, which also causes the degradation and the increase of the solubility of the coal.