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The effects of incubation time, temperature, initial pH, and dye concentration on the indigo carmine decolorization activity of Pseudomonas aeruginosa ATCC 10145 and some factors on the decolorization potential of crude laccase enzyme obtained from Funalia trogii ATCC 200800 were comparatively investigated. This bacterium showed effective decolorization activity at all agitation and temperature values. Indigo carmine was greatly decolorized by P. aeruginosa at all pH values except pH 10. A decrease in decolorization activity occurred with increasing dye concentration, but this bacterium effectively decolorized the dye within 24 h. The decolorization process was through microbial metabolism, not biosorption. No decolorization or laccase activity could be obtained by the cell-free intracellular extract or culture filtrate of this bacterium. On the other hand, crude laccase effectively decolorized indigo carmine under highly acidic conditions, especially at pH 3.0 as 57% in 300 seconds. This activity decreased progressively due to the increase in pH values. In a short incubation period and at high temperature values, the crude laccase enzyme removed the color of the dye at 50 °C (56%), 60 °C (45%), and 70 °C (38%). These data are important for improving methods for decolorization of textile dyes used at high temperatures in various industrial applications.

This study reports the preparation of poly(sodium-4-styrene sulfonate) (PSS) treated bentonite and clinoptilolite to prevent the agglomeration and sedimentation of these inorganic fillers during the preparation of hydrogel. For this purpose PSS treated fillers were prepared by using various techniques (dip and dry, hydrothermal, one-step ball milling and ultrasonication methods). The most suitable technique for preparing these PSS treated inorganic fillers (abbreviated as BP-dip and CP-dip) was the dip and dry method. BP-dip and CP-dip based polyvinyl alcohol/polyvinylpyrrolidone (PVA/PVP) composite hydrogels were prepared using the freeze/ thawing method after the addition of one of BP-dip and CP-dip inorganic fillers in various amounts. The swelling properties, stability behaviors and Rhodamine B (RhB) adsorption of the composite hydrogels were studied. It was found that the swelling degrees of CP-dip and BP-dip based composite hydrogels with 25 mg of filler were higher than that of all other samples. The kinetic mechanism of RhB adsorption process and the related characteristic kinetic parameters were investigated by Pseudo kinetic models. The adsorption kinetics results for RhB adsorption were found best fitted with pseudo-second-order kinetics model. The maximum RhB adsorption capacity was determined to be for PVA/PVP-CP-dip25, which was 3.3 times higher than that of the unfilled PVA/PVP hydrogel. © 2021 TUBITAK. All rights reserved. 2-s2.0-85117620063

The preparation of poly(vinyl alcohol) (PVA) hydrogels was succeeded via the freeze-thawing (F/T) method by varying the synthesis parameter conditions. The swelling capacity and long-term stability of the hydrogels were determined as a function of time at pH 2.1, 5.5 and 7.4 and found to be mainly affected by the synthesis parameter conditions. These studies showed that the swelling ratio generally increased with a low number of F/T cycles (2 and 3), high freezing temperature (- 5 and - 16 degrees C) and freeze-dried of drying type for all three pH mediums. The dried hydrogels at room temperature were found to be more stable hydrogels. In addition, the drug release studies of salicylic acid as a drug model were investigated at pH 7.4 and displayed controlled release for 120 h. The release kinetic studies obtained from drug release data demonstrated that the PVA hydrogel fits well into the Higuchi model. The release mechanism of PVA hydrogel was also determined as super case II type. WOS:000702600200001 2-s2.0-85116300994

The antibacterial sponges with high macroporosity, high interconnectivity and high biocompatibility is a significant concern for wound healing applications. In this work, novel Aloe vera (AV) based sponges were developed via subsequent lyophilization with further chemical crosslinking throughout the double network sponges. Single network was composed of gelatin-sodium alginate (G-SA) while the double network using gelatin-sodium alginate- sodium hyaluronate (G-SA-HA) was produced with the addition of hyaluronic acid solution into the gelatin-sodium alginate matrix. Lastly, Aloe vera as the bioactive agent was fabricated throughout the gelatin-sodium alginate-sodium hyaluronate matrix. The AV-based sponges demonstrated large pores with high interconnectivity. The swelling degree of the AV-based sponges were higher than that of G-SA and G-SA-HA sponges. The release of AV from the sponges reached an equilibrium value after 24 h showing a more controlled release at pH 5.5 than at pH 7.4. AV-based sponges showed antibacterial activity against Staphylococcus aureus, Enterococcus faecalis, Streptococcus pneumoniae and Bacillus cereus and displayed any cytotoxicity against Mesenchymal stem cells. Scientific Projects Coordination Unit of Hitit UniversityHitit University [MUH19001.18.001]; Hitit University Scientific and Tecnical Application and Research Center The financial support from the Scientific Projects Coordination Unit of Hitit University under the project number MUH19001.18.001 is gratefully acknowledged. The authors are also greateful to the support of Hitit University Scientific and Tecnical Application and Research Center. WOS:000608662700001 2-s2.0-85100181974

In this study, the effects of starting material types on graphene oxide (GO) are reported with the aim of developing graphene (GR) synthesis. The GOs were prepared from natural graphite (NG) powder and graphite nanoplate (GNp) based on the Hummers method. Two kinds of GR were successfully synthesized using GOs, which were prepared from NG and GNp in the presence of hydrazine and ammonia for 24 h at a 100 $^{\circ}$C reaction temperature. The synthesized GOs and GRs were characterized by X-ray diffraction (XRD) techniques, Fourier transform infrared, high-contrast transmission electron microscopy (HCTEM), dispersive Raman spectroscopic analyses, and elemental analyses. HCTEM analyses of GOs and GRs exhibited largely folded, convoluted, and entwined GO and GR structures. The XRD and Raman analyses showed that the number of layers of GO1, GO2, GR1, and GR2 were 9.27, 13.53, 4.11, and 5.26, respectively. On the other hand, GR1, prepared from NG powder, showed much higher quality (peak intensities (I$_{D}$/I$_{G})$ = 1.53, C/O = 3.64) than GR2, which was prepared from GNp (I$_{D}$/I$_{G\, }$= 1.64, C/O = 3.17). Thus, this study provides a way to produce higher quality GOs and GRs.

Commercially available multi-walled carbon nanotubes (MWCNTs), which are generally naturally intertwined, were cut by sudden, repeated exposure to oxidizing conditions in the air. This process has been proved to be an effective handle of producing open ended and medium level functionalization. Results showed that the typical closed graphite end caps for carbon nanotubes via functionalized with thermal stress (CNT-M) can be shorten long MWCNTs, while improving average graphite quality. These results were supported by the increase of Brunauer-Emmett-Teller (BET) surface area from 284.772 m(2)g(-1) to 463.890 m(2)g(-1). Copper oxide nanoparticles (CuO-PEGx) which were synthesized using polyethylene glycol (PEG) nonionic surfactants with different derivative (polyethylene glycol methyl ether methacrylate) and molecular weights (Mw: 200, 2000 and 5000), were encapsulated into CNT-Ms by simple wet impregnation technique. The filling capacity depended on the preparation conditions and particle size of CuO nanostructures. While other samples showed a multiple particle size distribution, only CNT-M-CuO-PEG950 sample indicated uniform particle size distribution with the smallest particles (3.6 nm) inside CNT-M channels. The BET surface areas of the nanocomposites (274.865-304.859 m(2)g(-1)) were lower than the surface area (463.890 m(2)g(-1)) of CNT-Ms while they were close and large to the surface area of MWCNTs (284.772 m(2)g(-1)). Hitit University Scientific Research Project, Turkey [MUH19002.18.002] This work was supported by the Hitit University Scientific Research Project, Turkey [grant numbers MUH19002.18.002] . WOS:000688435100001 2-s2.0-85100810341