Fatigue damage in composite cylinders

In this study, optimal angle‐ply orientation of symmetric composite cylinders under fatigue loading is investigated. The fiber‐reinforced plastic cylinders were manufactured from E‐glass/epoxy. The layers were manufactured symmetrically in [±75°]₂, [±60°]₂, [±55°]₂, and [±45°]₂ orientations. Burst pressure of filament‐wound composite cylinders under alternating pure internal pressure was measured experimentally. Internal fatigue pressure testing method was applied to the composite cylinders in close‐ended condition. For this study, a PLC controlled hydraulic pressure testing machine has been employed. The static burst pressure values of specimens were measured; subsequently, fatigue test pressure was applied in 70, 60, and 50% stress levels of burst pressure for each orientation. Damage propagations of the composite cylinders on these stress levels were observed as whitening, leakage, and final failure for [±60°]₂, [±55°]₂, and orientations. When the damage propagation of [±75°]₂ angle‐ply cylinder was observed, whitening and leakage did not occur and final failure occurred suddenly. Stress‐cycle curves obtained from the tests are given in graphics. Experimental results reveal that variation in stress levels and the winding angles have considerable effects on final failure cycles, which is also presented graphically. The optimum winding angle for the composite pressure cylinders or vessels under internal fatigue pressure load was obtained as [±45°]₂ orientation. POLYM. COMPOS., 2010. © 2009 Society of Plastics Engineers     

Image enhancement via space-adaptive lifting scheme exploiting subband dependency

This paper proposes an image enhancement method based on space-adaptive, 2-D lifting scheme. In the space-adaptive update-first lifting scheme, the prediction stage is adapted to the signal structure point-by-point which results in a better signal representation and enhancement result. In this paper, a novel edge-sensitive adaptive prediction method is introduced in the 2-D lifting framework. The method adaptively chooses the best predictor among a set of predictors minimizing the prediction error. The proposed prediction method is sensitive to both even and odd indexed edge pixels in the 2-D lifting context. The bivariate shrinkage which assumes the dependence of the subband wavelet coefficients is used for subband image enhancement. As an objective quality measure, the peak signal-to-noise ratio test is applied to the results of the proposed image enhancement algorithm. Results of the proposed algorithm are compared with those of the VisuShrink, BayesShrink, and NorShrink. Experimental and objective quality test results prove the superior performance of the proposed image enhancement method.     

Compatibilization of Poly(2,6-dimethyl-l,4-phenylene oxide) and Poly(2,6-dichloro-l,4-phenylene oxide) with Sulfonated Polystyrene and its Na and Zn-neutralized Ionomers

Compatibility of acidic (H), Na, and Zn neutralized sulfonated polystyrene ionomer blends with Poly(2,6-dimethyl- 1,4-phenylene oxide) (PPO) and Poly(2,6-dichloro- 1,4-phenylene oxide) (PDCIPO) was investigated by Dilute Solution Viscometry (DSV) and Differential Scanning Calorimetry (DSC). The intrinsic viscosities of the blends, are measured in suitable solvents. The degree of compatibility of the blends is characterized by Δb parameter. According to the results, PPO is completely miscible, except for Na-neutralized 1.7 mol% sulfonated polystyrene (Na1.7SPS) which is completely immiscible with PPO and PDClPO. PDClPO is completely miscible with Zn-neutralized sulfonated polystyrene (Zn4.8SPS) and partially miscible with acid sulfonated polystyrene (4.8SPS). Received: 12 August 2001/Revised version: 21 January 2002/Accepted: 11 March 2003 Correspondence to Leyla Aras     

Expression and Characterization of a New Self-Sufficient P450 Monooxygenase (P450 AZC1) from Azorhizobium caulinodans

Oxyfunctionalization of non-activated carbon bonds by P450 monooxygenases has drawn great industrial attraction. Self-sufficient P450s containing catalytic heme and reductase domains in a single polypeptide chain offer many advantages since they do not require external electron transfer partners. Here, we report the first P450 enzyme identified and expressed from Azorhizobium caulinodans. Firstly, expression conditions of P450 AZC1 were optimized for enhanced expression in E.coli. The highest P450 content was obtained in E.coli Rosetta DE3 plysS when it was incubated in TB media supplemented with 0.75 mM IPTG, 0.5 mM ALA, and 0.75 mM FeCl₃ at 25 °C for 24 hours. Subsequently, the purified enzyme showed a broad substrate spectrum including fatty acids, linear and cyclic alkanes, aromatics, and pharmaceuticals. Finally, P450 AZC1 showed optimal activity at pH 6.0 and 40 °C and a broad pH and temperature profile, making it a promising candidate for industrial applications.     

Creating a high-quality wool-oriented Turkish merino herd and investigation of mechanical and dyeability properties of fabrics produced from Turkish merino in comparison with Australian merino

Today, the need for quality wool suitable for worsted fabric production in the world is mainly met by Australian merino wool. In Turkey, which has a significant sheep population, in addition to domestic breeds, approximately 10% of the total sheep population (around four million head) is composed of merino cross breeds. However, the fleece quality is far from meeting Australian merino wool standards. Therefore, the aim of this study is to ensure a merino herd with high-quality wool in Turkey. For this aim, by carrying out field studies in the Thrace region of Turkey where Turkish Merino sheep are widely bred, sheep with fleece that can meet the demands of the worsted industry were determined. As a result of field studies in which thousands of sheep were examined, it was determined that 43 female and 10 male sheep had fleece that would meet these standards. Then the breeders of the sheep, which had quality fleece, were persuaded and these sheep were purchased, and “Turkey's wool-oriented Turkish (Karacabey) Merino Herd” consisting of 30 sheep and three rams was formed in the farm of Tekirdağ Namık Kemal University. In the second part of this study, a 100% wool fabric produced by using Australian merino was taken as a reference and it was aimed to produce the same fabric from Turkish merino wool. For this aim, the wool-oriented Turkish Merino herd, which was bred at the university farm for 1 year, was shorn in May 2022. Then, Turkish and Australian merino wools were first converted into worsted yarn and then into woven fabric. The results of mechanical (tensile strength, pilling, abrasion resistance, felting shrinkage, Hofmann dimensional change, bending stiffness) and dyeability (dye-uptake, CIE L*a*b* and colour yield (K/S) values; washing, rubbing and light fastness values) properties of fabrics produced from Turkish and Australian merino wool is presented.     

Determination of the quality and purity characteristics of olive oils obtained from different regions of Turkey,depending on climatic changes

Virgin olive oils (VOOs) obtained from olives grown in different regions of Turkey under changing climatic conditions sometimes show different sensory and chemical properties. This study was planned to determine whether these deviations are due to climatic changes or not. For this purpose, five different olive varieties (Ayvalık, Memecik, Gemlik, Nizip Yağlık, Kilis Yağlık) of commercial importance were harvested from the provinces/districts (four different region) where cultivation is intense during the 2017/2018–2020/2021 harvest years. Every year, olive samples were collected from 3 orchards from 13 provinces/districts. One hundred and fifty-six samples were subjected to the purity, quality and sensory analysis. Basic climatic values (average, minimum and maximum temperature, humidity and precipitation) were examined for four consecutive years. All of the examined olive oil samples were determined within the legal limits in terms of fatty acid composition and fatty acid ethyl ester values. However, delta-7-stigmastenol value from the sterol composition was found to be above 0.5% in some samples in all the years studied (total 21 samples). Delta-7-stigmastenol values of olive oil samples varied between 0.16% and 1.14%. Multiple linear regression analysis was applied using a genetic algorithm-based inverse least squares method to determine whether there is a relationship between climate data and delta-7-stigmastenol values. According to this result, it has been determined that the delta-7-stigmastenol value is high when the annual average relative humidity is low and the annual average temperature is high. There is an urgent need to make forward-looking plans due to climate change.     

Effect of ZnO type and concentration on the mophology,thermal, and mechanical properties of poly(ether ester)/ZnO composites

Poly(ether ester) (PEE) copolymers were synthesized in a two‐stage process involving transesterification and polycondensation. The synthesized copolymer and the zinc oxide (ZnO) were used in composite preparation by melt compounding. The influence of ZnO type and concentration on the morphology, thermal and mechanical properties of the composites were studied. DSC and XRD analyses indicated that crystallinity of composites was slightly reduced with ZnO content. Homogeneous dispersion of fillers in the polymer matrix was observed through morphological analyses. While in general tensile strength and elongation at break values of the composites decreased with increasing ZnO content, elastic modulus values increased with the addition of ZnO. Moreover, ZnO particles were modified with poly(N‐vinyl pyrrolidone) and a slight improvement in mechanical properties was observed, respectively over the composites containing unmodified particles. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013