Papers by Ali Şamil Aytekin
Chitosan is a biopolymer composed of glucosamine and N-acetyl glucosamine. Solubility and viscosi... more Chitosan is a biopolymer composed of glucosamine and N-acetyl glucosamine. Solubility and viscosity pose problems in some applications. These problems can be overcome with unique modifications. In this study, firstly, chitosan was modified by caffeic acid and thioglycolic acid, separately. Then, growing effects of these modified polymers was observed in U937 cell line. Caffeic acid is a phenolic compound and its modifications act carcinogenic inhibitors in drugs. Thiolated chitosans are commonly being used for drugdelivery systems in various routes, because of enhancing mucoadhesiveness property. U937 cell line was used model cell for leukaemia. Modifications were achieved by 1 – 15 % binding range. Increasing binding ratios showed higher radical-scavenging activity and reducing cell growth, in compared to native chitosan. Caffeic acid modifications showed higher radical-scavenging activity than thiolated chitosans at the same concentrations. Caffeic acid and thioglycolic acid modif...
The theory of profinite groups has several times provided significant results for the theory of p... more The theory of profinite groups has several times provided significant results for the theory of presentations of finite groups. Profinite groups occur in problems relating to Number Theory, Commutative Algebra, Algebraic Geometry and Algebraic Topology. All of these results in this paper are adapted from Duflot's result for group case.
arXiv: Algebraic Topology, 2016
In this study we introduce the notions of semi-homotopy of semi-continuous maps and of semi-paths... more In this study we introduce the notions of semi-homotopy of semi-continuous maps and of semi-paths. We also construct a group structure, which will be called semi-fundamental group, using semi-loops and explore some properties of semi-homotopy and semi-fundamental groups.
Journal of the Institute of Science and Technology, 2020
The main purpose of this paper is to define the simplicial object in the category of Leibniz alge... more The main purpose of this paper is to define the simplicial object in the category of Leibniz algebras and to show the equivalence of the category of simplicial Leibniz algebras and the category of crossed modules on Leibniz algebras.
TURKISH JOURNAL OF MATHEMATICS, 2019
In this paper we give constructions of pullback, finite product, finite limit, coproduct, colimit... more In this paper we give constructions of pullback, finite product, finite limit, coproduct, colimit, pushout, etc. in a special full subcategory XMod/L of the category of Lie-Rinehart crossed modules.
N-Acetylglucosamine: Medical Importance of Chitin and Chitosan
Chitin Extraction From Prawn Processing Waste By Biological Methods
Presentation-BEC2013-AOAYTEKIN
In this paper we will examine the Pro-C completion process of a crossed square. For a crossed squ... more In this paper we will examine the Pro-C completion process of a crossed square. For a crossed square (L, M, N, P), we will determine the relation between the completion (L, M, N, P) and the completion of the individual pieces of the given structure.
Improved Bacterial Cellulose Production Using Newly Developed Medium
There is a huge demand for developing new technologies for alternative energy sources due to the ... more There is a huge demand for developing new technologies for alternative energy sources due to the elevated costs of petroleum and its by-products, depletion of nonrenewable fuel sources, and to eliminate the disadvantages of geopolitical location and environmental pollution caused by high levels of carbon dioxide release. Science is striving to meet this demand and as molecular biology techniques have progressed, genetic engineering tools have been presented as promising future solutions in the form of optimizing the fermentation process to increase the ethanol yield from different carbon sources such as starch. As Saccharomyces cerevisiaeis not naturally able to ferment starch, it can be genetically manipulated and modulated to improve the fuel production from starchy materials and the amount of cost that is required to produce ethanol would be decreased with these manipulations. General modifications in S. cerevisiaeinclude specific gene expressions to gain new properties or improv...
Applied Biochemistry and Biotechnology, 2014
Saccharomyces cerevisiae, industrial yeast isolate, has been of great interest in recent years fo... more Saccharomyces cerevisiae, industrial yeast isolate, has been of great interest in recent years for fuel ethanol production. The ethanol yield and productivity depend on many inhibitory factors during the fermentation process such as temperature, ethanol, compounds released as the result of pretreatment procedures, and osmotic stress. An ideal strain should be able to grow under different stress conditions occurred at different fermentation steps. Development of tolerant yeast strains can be achieved by reprogramming pathways supporting the ethanol metabolism by regulating the energy balance and detoxicification processes. Complex gene interactions should be solved for an in-depth comprehension of the yeast stress tolerance mechanism. Genetic engineering as a powerful biotechnological tool is required to design new strategies for increasing the ethanol fermentation performance. Upregulation of stress tolerance genes by recombinant DNA technology can be a useful approach to overcome inhibitory situations. This review presents the application of several genetic engineering strategies to increase ethanol yield under different stress conditions including inhibitor tolerance, ethanol tolerance, thermotolerance, and osmotolerance.
Biochemical Engineering Journal, 2014
Bacterial cellulose (BC) has unique properties, such as high crystallinity, a high degree of poly... more Bacterial cellulose (BC) has unique properties, such as high crystallinity, a high degree of polymerisation, high tensile strength and high purity, compared with native cellulose. In this study, a previously determined BC production medium was improved in static culture, and the production cost was evaluated and compared with molasses and with other defined media, such as Hestrin-Schramm, Zhou, Yamanaka and Park, using Gluconacetobacter xylinus. In addition to this analysis, because the surface area/volume ratio is an important parameter in static culture, different surface area/volume ratios were analysed in the range of 0.2-1.46. The defined medium (M1A05P5) and culture type contained glucose (10 g/L), yeast extract (10 g/L), peptone (7 g/L), acetic acid (1.5 ml/L), and ethanol (5 ml/L), and the pH was adjusted to 5.0 in static culture. The highest productivity was observed in the M1A05P5 medium that was 5-fold higher than either molasses or Park's medium. Although the molasses medium was proposed as a cost-effective medium, the production price of BC was the lowest in the M1A05P5 medium. Therefore, the newly developed medium and strategy were highly promising candidates for the industrial-scale production of BC.
Journal of Biotechnology, 2008
Journal of Bioscience and Bioengineering, 2011
In this study, the antioxidant activities of different molecular weights (M w) and grafting ratio... more In this study, the antioxidant activities of different molecular weights (M w) and grafting ratios of chitosan-caffeic acid derivatives were investigated. The grafting process was achieved using 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride (EDAC) as covalent connector under different conditions such as molecular-weight of chitosan, molar ratio of chitosan and caffeic acid, reaction temperature, pH, and reaction time. The half-inhibition concentrations (IC 50) of products were calculated by reduction of the 1,1-diphenyl picryl hydrazyl in the radical-scavenging assay and reduction of the Fe 3+ / ferricyanide complex to the ferrous form in reducing power assay. The EDAC showed maximum activity at 3-h, pH 5.0 and room temperature conditions, except high-molecular-weight chitosan in pH 2.0. The products were water-soluble in all pH and showed lower viscosity than native chitosan. The highest grafting ratio of caffeic acid was observed at 15% in lowmolecular-weight chitosan. After 5% grafting of caffeic acid into chitosan, the grafting efficiency was increased by decreasing molecular-weight of chitosan at the same conditions. Caffeic acid has main role in the antioxidant activity of products. The maximum IC 50 of radical-scavenging activity (0.064 mg/ml) was observed at the highest caffeic acid containing derivative. Water-soluble chitosan and caffeic acid derivatives were obtained by this study without activity loss.
Semi-Complete Crossed Modules of Lie Algebras
Journal of Algebra and Its Applications, 2012
We investigate some sufficient and necessary conditions for (semi)-completeness of crossed module... more We investigate some sufficient and necessary conditions for (semi)-completeness of crossed modules in Lie algebras and we establish its relationships with the holomorphy of a crossed module. When we consider Lie algebras as crossed modules, then we recover the corresponding classical results for complete Lie algebras.
Gezgin Satıcı Probleminin İkili Kodlanmış Genetik Algoritmalarla Çözümünde Yeni Bir Yaklaşım
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Papers by Ali Şamil Aytekin