Turkish Journal of Chemistry最新文献

The chromium speciation procedure was optimized using magnetic polyaniline nanoparticles (Fe₃O₄@PANI NPs) solid-phase extraction coupled with microsampling injection-flame atomic absorption spectrometry (MIS-FAAS). Chromium speciation was successfully achieved by Fe₃O₄@PANI NPs at pH 8.0. The recoveries obtained for Cr(III) and Cr(VI) were above 95% and under 5%, respectively. Recoveries of over 95% for Cr(III) from 40.0 mL of the sample were obtained using 25 mg Fe₃O₄@PANI NPs and 500 μL of 0.2% (w/v) thiourea (TU) solution prepared in 2 mol L^-1 HCl as eluent. Total chromium as Cr(III) was extracted quantitatively after reducing the Cr(VI) to Cr(III). The linear range, detection limit, preconcentration factor, and precision of the optimized method for Cr(III) in aqueous solution were 2.5-94.0 μg L^-1, 0.335 μg L^-1, 80, and 3.07%, respectively. The validation of the method was controlled using SPS-WW2 Batch 114 wastewater and BCR-715 industrial wastewater as standard reference materials (SRMs) for environmental water, and the obtained results were in close agreement with the certified values.

In the current study, the impact of C-ratio, convective heat transfer coefficient, and free stream temperature on the maximal cell temperature and temperature uniformity was computationally and statistically examined. Results revealed that the free stream temperature was the main influential factor for the maximal cell temperature for both natural and forced convection conditions while the C-ratio was the most effective parameter for the temperature uniformity for both natural and forced convections. On the other hand, the contribution of the free stream temperature to the maximum battery temperature increased from 63% to 94% when the conditions were changed from natural convection to forced convection. Moreover, the contribution of the C-rate to the temperature uniformity decreased from 89% to 79% when the conditions were changed from natural convection to forced convection. The results obtained from this study are significant in terms of determining which factor should be given more importance under natural and forced convection conditions.

Pichia yeasts are capable of forming biofilms during vinegar production and causing spoilage in various beverages. In addition, there exists a significant likelihood of encountering yeast contamination which can prevent vinegar production. The present study investigates the detection and characterization of the Pichia manshurica (P. manshurica) biofilm on traditionally produced homemade apple vinegar. The unique characteristics of vinegar were analyzed with a focus on the constituent, known as the "mother of vinegar", whose composition is comprised of cellulosic biofilm and acetic acid bacteria, including Gluconobacter oxydans (G. oxydans) Briefly, P. manshurica was isolated from apple vinegar and characterized in terms of the effect of biofilm formation on the surface of the cellulosic film on vinegar production. Microbial identification of vinegar with/without contamination by P. manshurica was analyzed through MALDI-TOF mass spectrometry (MS), and biofilm was characterized by Fourier transform infrared spectroscopy (FT-IR), Scanning electron microscopy (SEM), and crystal violet staining. Accordingly, MS spectrum of isolates was identified as G. oxydans and P. manshurica with a ratio of 2.01 and 1.94, respectively. The FTIR analysis indicated that the peaks within the range of 1150-900 cm^-1 revealed a high content of polysaccharide in P. manchuria-contaminated biofilm, which is attributed to the stretching vibration of C-C and C-O bonds. The spectral region from 2921.51 to 2853.71 cm^-1 exhibited the characteristic of lipids in bacterial cell walls and membranes. SEM images of bacterial biofilms revealed a three-dimensional network composed of ultrafine fibers with a ribbon-like shape; however, the condensed reticulated structure was observed in contaminated biofilms. The presence of two microbial populations was detected regarding the morphological analysis. Crystal violet staining of contaminated-cellulosic biofilms visualized bacterial and yeast colonization. Concisely, this study emphasizes that the proliferation of Pichia during apple fermentation has the potential to adversely affect the quality of the homemade vinegar, due to its distinct biofilm characteristics.

New methods have been developed for the synthesis of the substituted quinolines and quinazolinones derivatives by utilizing N-(2-aminobenzoyl)benzotriazoles under mild reaction conditions. 3-Acyl-2-alkyl(aryl)-4-hydroxyquinolines were obtained in modarete yields by the reaction of N-(2-aminobenzoyl)benzotriazoles and diketones in the presence of tert-BuOK. 3-Acylamino-4(3H) quinazolinones were obtained in good yields via N-(2-aminobenzoyl)benzotriazoles, orthoester and hyrazides in one-pot.

Quaternized chitosan (HTCC) was synthesized and characterized to increase chitosan solubility. Then HTCC was electrospun with poly (vinyl alcohol) (PVA) and prepared natural bioactive agent (Calendula officinalis) extract was loaded onto fibers for wound scaffold applications. Morphological, structural, and mechanical characterization of the produced wound scaffolds was performed and their in vitro bioactive component release behavior was investigated. As a result, it was observed that the degree of quaternization of chitosan was 0.89, and synthesized HTCC was soluble in acidic, basic, alkaline media and could be electrospun with PVA in the presence of a natural bioactive agent. The presence of HTCC increased Young's modulus and the tensile strength of the PVA scaffolds, while the presence of bioactive extract caused a decrease in Young's modulus and an increase in tensile strength. Calendula officinalis is released in a controlled and slow manner from the scaffolds within approximately 55 h. The release behavior was consistent with the Higuchi kinetic model. In this study, the effect of PVA cooperator on HTCC nanofiber production in the presence of a bioactive component was investigated for the first time. HTCC and Calendula officinalis extract were also used together for the first time in the composition of a fiber scaffold. The mechanical properties and release kinetics of these scaffolds were also investigated for the first time. According to the results, it is thought that the wound scaffolds produced have the potential to be used as a new treatment tool, especially for chronic wounds.

In the literature, there are studies on medical applications using different nanofiber production methods with natural polymers. However, each system has different fiber-forming capabilities. For this reason, in this study, we investigated the production of nanofibers from a biodegradable natural polymer, gelatin, using four separate nanofiber production methods, namely electrospinning (ES), electroblowing (EB), solution blowing (SB), and centrifugal spinning (CS). Our aim was to determine the most suitable fibrous web structure for medical applications and contribute to science in this respect. It was observed that the thinnest fibers (386 nm) and the heaviest mats (15.975 g m^-2) were produced by the SB method as a result of using 10 wt.% gelatin solution with a total of 10 mL. With the ES and EB methods, tighter fabric structures were obtained than with the others due to the presence of electric fields. In the CS method, more and bead-free fibers were produced due to the increase in viscosity with a 12.5 wt.% gelatin solution. Moreover, with the concentration of 12.5 wt.%, the fiber diameters of SB and CS samples increased about 2-fold.

Technological devices are mostly manufactured by conductive and semiconductive materials. As advancement in the last decades, carbon nanomaterials have been explored in electrical/electronic technology due to their unique performances for manufacturing developing, and prudential miniaturized and flexible electrical/electronic devices. In the era of sustainable and clean carbon technology; renewable, alternative, biodegradable, and eco-friendly new carbon resources are required. Biomass could be the answer to offer inspiring carbon allotropes from nature to be suitable for developing electrical/electronic devices. In this article, deriving of the technological carbonaceous material from biomass, studies although they are very limited in the literature on obtaining the electrical conductive ones and the progress as electrical conductive renewable material are presented.

A weak acidic complex ester (CE) in solid form was prepared by a condensation reaction between very weak boric acid (BA: H₃BO₃) and (D)-mannitol (MA: C₆H₁₄O₆) by the molar ratio of BA/MA = 2. A boron carbide (B₄C) precursor was obtained from heating of the CE at 400 °C for 4 h. The precursor was pyrolyzed under argon flow in the interval of 1300-1550 °C for 4 h and at 1400 °C for 1-4 h, respectively. The materials were examined using several techniques such as X-ray diffraction analysis, thermal analysis, scanning electron microscopy, particle size distribution, and nitrogen adsorption/desorption. The optimum pyrolysis temperature and duration were 1400 °C and 4 h, respectively. The most crystalline B₄C particles were distributed between 1 and 100 μm with a mean particle size of 20 μm. The specific surface area and specific pore volume were 13.5 m² g^-1 and 0.09 cm³ g^-1, respectively. The size of the pores was between 2 and 36 nm with a mean size of 14 nm.

In this study, a new method for synthesizing diepoxides is proposed. Tetrahydroindene 1 was brominated with NBS in the presence of LiClO₄ and acetic acid, resulting in the formation of dibromodiacetate derivatives 2 and 3. Treatment of compounds 2 and 3 with NaOH in methanol produced a mixture of diepoxides 4 and 5. Additionally, direct bromination of tetrahydro-1H-indene yielded tetrabromo octahydroindene isomers 6 and 7. The structures of the compounds were characterized using spectroscopic techniques such as ¹H NMR, ¹³C NMR, APT, COSY, and XRD. The new method provides an easy and selective route to access epoxides for the synthesis of various chemicals. This study also highlights the selective formation of endo-exo and exo-exo orientations of the obtained diepoxides, distinguishing it from previous studies. The stability and properties of the stereoisomers were investigated using computational methods, revealing the most stable configurations. Reactive sites in the molecules were identified using contour diagrams and molecular electrostatic potential maps. The anticancer properties of the compounds were evaluated in silico, comparing them to 5-fluorouracil (5-FU) against several cancer cell lines. The compounds exhibited the most effective anticancer activity against MCF-7 cells, with the order of anticancer activities generally determined as 2 > 7 > 3 > 6 > 5 > 4 > 5-FU.

In this study, β-2-heteroaryl substituted (N-methyl 2-pyrrolyl, 2-thiophenyl, 2-furyl) α,β-unsaturated ketones were reacted with two α-diazo carbonyl compounds that had different characteristics (dimethyl diazo malonate and 1-diazo-1-phenyl-propane-2-one) in the presence of both copper and rhodium catalysts. In the case of reactions with N-methyl 2-pyrrolyl α,β-unsaturated ketones, the major product was the insertion derivative. However, in the reactions of 2-thiophenyl and 2-furyl α,β-unsaturated ketones with dimethyl diazomalonate (acceptor-acceptor disubstituted), only dihydrofuran products were formed over carbonyl ylides. When 2-thiophenyl and 2-furyl α,β-unsaturated ketones were reacted with 1-diazo-1-phenyl-propane-2-one (donor-acceptor disubstituted), 1-phenylpropane-1,2-dione was obtained under our reaction conditions.