Fading of Cotton Yarn Colored with C. I. Vat Blue I (Indigo Dye) via Ozone Application

In this experimental study, the possibility of obtaining of fading effect to indigo dyed denim yarns via ozonation process was searched. Therefore, a novel approach was attempted for fading the denim materials in the form of yarn before weaving or garment processes. The effect of the ozone gas on the CIELab values of indigo dyed yarn specimens was statistically investigated depending on some physical properties of the yarns and application parameters of ozone gas. In addition, the effect of ozone gas on the strength performance of the yarns was investigated. The results showed that different yarn and ozone application parameters affected the fading results. Besides, the ozonation process did not have a crucial negative effect on yarn strength.     

Mechanical properties and impact resistance of concrete composites with hybrid steel fibers

The aim of this study is to develop concrete composites that are resistant to armor-piercing projectiles for defense structures. Different reinforcement configurations have been tested, such as short steel fibers, long steel fibers, and steel mesh reinforcement. Three different concrete mix designs were prepared as “Ultra High Performance (UHPFRC), High Performance (HPFRC) and Conventional (CFRC) Fiber Reinforced Concrete”. The content of hybrid steel fibers was approximately 5% in the UHPFRC and HPFRC mixtures, while the steel fiber content was approximately 2.5% in the CFRC mixture. In addition, a plain state of each mixture was produced. Mechanical properties of concrete were determined in experimental studies. In addition to the fracture energy and impact strength, two important indicators of ballistic performance of concrete are examined, which are the penetration depth and damage area. The results of the study show that the depth of penetration in UHPFRC was around 35% less than that in HPFRC. It was determined that the mixtures of UHPFRC and HPFRC containing 5% by volume of hybrid steel fibers showed superior performance (smaller crater diameter and the less projectile penetration depth) against armor-piercing projectiles in ballistic tests and could be used in defense structures.     

Chemoselective reduction of α,β-unsaturated aldehydes and ketones over mesoporous B(O i Pr)3–MCM-41 catalyst via MPV reduction process: preparation, characterization and catalytic application

Boron alkoxide-containing ordered mesoporous silica material (B(O ⁱ Pr)₃–MCM-41) was prepared by the grafting method. The obtained B(O ⁱ Pr)₃@MCM-41 composite materials were fully characterized in details by PXRD, FT-IR-, ¹¹B-NMR-, ²⁹Si-NMR-, ¹³C-NMR-spectroscopies, scanning electron microscopy, EDX, transmission electron microscopy techniques, N₂ adsorption–desorption isotherms and Inductively coupled plasma-optical emission spectroscopy analyses, demonstrating the successful homogenous distribution of the B(O ⁱ Pr)₃ catalyst in the MCM-41 support. The as-prepared new materials were successfully applied in the chemoselective Meerwein–Ponndorf–Verley reduction of α,β-unsaturated carbonyl compounds. In the reduction of α,β-unsaturated aldehydes and ketones, which can not be reduced by usual catalysts, a very high selectivity, especially for the reduction of allylic aldehydes and ketones could be obtained. In most cases no side product formation could be observed. The catalyst was found to be encouraging as a heterogeneous catalyst as the yield was almost unchanged after up to six cycles. No leaching of the grafted boron tri-isopropoxide into the reaction mixture could be detected.     

Synthesis,electrochemistry, spectroelectrochemistry and electrocolorimetry of phthalocyanine–anthraquinone hybrids

The tetra substituted metallophthalocyanines 2 and 3, soluble in common organic solvents, bearing four 2-(9,10-dioxo-9,10-dihydro-anthracen-2-yl-methyl)-malonic acid diethyl ester functionalities were synthesized from the corresponding phthalodinitrile 1 and divalent metal salts at 170 °C in fused state. Reaction of with manganese (2+) acetate in n-pentanol led to the manganese (3+) phthalocyanine 4. Furthermore, the unsymmetrical copper phthalocyanine 5 containing one 2-(9,10-dioxo-9,10-dihydro-anthracen-2-yl-methyl)-malonic acid diethyl ester moiety was synthesized using a statistical approach. The new compounds were characterized by elemental analysis together with FT-IR, ¹H-NMR, ¹³C-NMR, and UV–vis spectroscopy and via mass spectrometric analysis. The electrochemical, in situ spectroelectrochemical, and in situ electrocolorimetric measurements represent that while MPcs give common ring-based and/or metal-based electron transfer processes, these processes were considerably affected with the redox processes of the AQ units attached to the phthalocyanine ring. At the same time attachments of the AQ units to the phthalocyanine rings improve the reversibility of the AQ units due to the electron donor–acceptor interaction between the AQ units and phthalocyanine ring. The AQ units also alter the color states of the phthalocyanines.     

Synthetic fuel production from tea waste: Characterisation of bio-oil and bio-char

The pyrolysis of tea waste was studied for determining the main characteristics and quantities of liquid and solid products. Particular investigated process variables were temperature (673-973 K), heating rate (5-700 K min⁻¹) and nitrogen gas flow rate (200-800 cm³ min⁻¹). The maximum oil and char yields are 30.4 (773 K) and 43.3% (673 K), respectively. The liquid and its aliphatic sub-fraction were characterized by elemental analysis, FT-IR, ¹H NMR, and GC/MS. The char was characterized with elemental analysis, SEM, BET, and FT-IR techniques. The aliphatic sub-fraction of the obtained bio-oil contains predominantly n-alkanes and alkenes, and branched hydrocarbons. According to the experimental results the liquid products can be used as liquid fuels, whereas the solid product seems to be not suitable for adsorption purposes, due to having low surface areas.     

Essential oil composition and antibacterial activity of the grapefruit (Citrus Paradisi. L) peel essential oils obtained by solvent‐free microwave extraction: comparison with hydrodistillation

The chemical composition of the essential oil (EO) obtained by solvent‐free microwave extraction (SFME) and hydrodistillation (HD) from the peel of grapefruit (Citrus Paradisi. L) was analysed by gas chromatography/mass spectrometry (GC/MS). Totally, twenty‐five components were identified in the EO. Limonene was observed as dominant (91.5–88.6%) for two extraction methods, SFME and HD, respectively. β‐Pinene (0.8–1.2%), linalool (1.1–0.7%), α‐terpinene (0.7–1.0%) and the other minor components were also detected. Disc diffusion method was applied to determine the antibacterial properties of the EO. The results showed that the EO of grapefruit peel had a wide spectrum of antimicrobial activities against Staphylococcus aureus, Enterococcus faecalis, Staphylococcus epidermidis, Escherichia coli, Salmonella typhimurium, Serratia marcescens and Proteus vulgaris, with their inhibition zones ranging from 11 to 53 mm.     

The effect of gold clusters on the autoxidation of poly(3-hydroxy 10-undecenoate-co-3-hydroxy octanoate) and tissue response evaluation

We describe the synthesis and characterization of gold clusters embedded into poly (3-hydroxy octanoate-co-3-hydroxy-10-undecenoate) (PHOU), and evaluated the tissue response of the material upon implantation onto muscle tissue (rat). For this aim, PHOU was obtained by Pseudomonas oleovorans from octanoic acid (OA) and 10-undecenoic acid (UA) with a weight ratio of 50:50. The unsaturated co-polyester film in which HAuCl₄ was dispersed was exposed to air at room temperature to produce gold clusters embedded into cross-linked PHOU. The cross-linking kinetics of the gold catalyzed PHOU autoxidation was followed by sol-gel analysis. In vivo tissue reactions of the cross-linked PHOU embedded gold clusters were evaluated by subcutaneous implantation in rats. The rats appeared to be healthy throughout the implantation period. No symptom such as necrosis, abscess or tumor genesis was observed in the vicinity of the implants. Retrieved materials varied in their physical appearance after 6 weeks of implantation. AFM and SEM micrographs of the PHOU containing gold clusters were also taken.     

A new rapid spectrophotometric method to determine the rosmarinic acid level in plant extracts

A novel spectrophotometric method to determine the amount of rosmarinic acid in unpurified methanol extracts of the plants was developed. Rosmarinic acid is a naturally occurring bioactive compound in plants as an ester of caffeic acid with 3,4-dihydroxyphenyl lactic acid. The developed method was based on the complexation of rosmarinic acid with Zr⁴⁺ ions, giving a maximum absorbance at 362 nm. The absorptivity coefficient at this wavelength was found to be ε₃₆₂ = 2.66 × 10⁴ L mol⁻¹ cm⁻¹. In fact, this method is also specified giving two more absorption bands in UV region at 299.5 and 263.5 nm besides 362 nm. In addition, the accuracy and sensitivity of the new developed method are compared with the direct UV and rosmarinic acid–Fe²⁺ complex spectrophotometric methods by using methanol extracts of 11 Salvia species. As a conclusion, the present method is faster, cheaper, and more selective than the conventional methods for rosmarinic acid.     

Methane OSR over Pt-Ni/δ-Al2O3: Performance and power law type kinetics

Methane oxidative steam reforming (OSR) performance of two bimetallic Pt-Ni/δ-Al₂O₃ catalysts, having Pt:Ni loadings, 0.2:10 and 0.3:10, were tested first. In the tests, residence time (W/F), carbon-to-oxygen (C/O₂) feed ratio, and temperature were used as the experimental parameters. Increase in temperature resulted in direct and indirect - through enhanced TOX yielding higher energy - increase in SR rate. As Pt:Ni metal loading ratio did not lead to significant changes in activity, the preliminary kinetic tests to determine merely kinetically controlled region were conducted over 0.2Pt-10Ni catalyst. Considering the outcomes of the preliminary tests, the kinetic experiments were performed for practical reaction conditions extending up to 20% methane conversion with feed ratio intervals of 4.0 < C/O₂ < 7.34 and 2.03 < S/C < 3.08 at two different residence time (W/F) values to obtain a power-law type rate equation. Reaction orders were estimated as 0.81, 1.60 and 0.44 for methane, oxygen and steam, respectively, by using multivariable non-linear optimization function of MATLAB?. The apparent activation energy of methane OSR was calculated as 24.61 kJ mol^?1 and pre-exponential factor as 0.110 μmol mgcat^?1 s^?1 kPa^?2.85 for the 375–450 °C temperature interval. The same analysis performed for a narrower temperature range, 375–425 °C, gave k₀ and E_A values as 0.251 μmol mgcat^?1 s^?1 kPa^?2.85 and 29.17 kJ mol^?1, respectively, confirming the high sensitivity of OSR pathway to temperature.