Filtreler
Filtreler
Bulunan: 11 Adet 0.000 sn
Koleksiyon [20]
Tam Metin [2]
Yayın Türü [1]
Yazar [19]
Konu Başlıkları [20]
Yayıncı [7]
Yayın Dili [2]
Dergi Adı [11]
Araştırmacılar
Redox polymerization of N-isopropylacrylamide by using hydroxylated soya oil polymer

Allı, Abdulkadir | Şanal, Timur | Hazer, Baki

Article | 2015 | Turkish Journal of Chemistry39 ( 2 ) , pp.382 - 394

Abstract: Water soluble hydroxylated soya oil polymer was used in the redox polymerization of N-isopropylacrylamide (NIPAM) in order to obtain water-based hydroxylated-soya oil polymer-g-PNIPAM graft copolymer. For this purpose, soya oil was exposed to air under sunlight to obtain autoxidized soya oil polymer (PSy-ox). PSy-ox was allowed to react with diethanol amine to obtain hydroxylated soya oil polymer (hydroxylated-PSy). An ammonium persulfate with hydroxylated-PSy redox initiating system was used in the polymerization of NIPAM in order to obtain thermo-responsive hydroxylated-PSy-g-PNIPAM water-based graft copolymers. The graf . . .t copolymers were characterized using proton nuclear magnetic resonance, Fourier transform infrared~spectroscopy, gel permeation chromatography, thermal gravimetric analysis, and differential scanning calorimetry techniques. The effects of hydroxylated-PSy on the thermal response rate of PNIPAM and the percentage of transmittance in the water of graft copolymers were studied by means of observing UV transmittance behaviors in response to changing temperature. This showed the temperature-responsive property, and exhibited a volume phase transition from 22 °C to 29 °C, while that of PNIPAM was 32 °C. Abstract: Water soluble hydroxylated soya oil polymer was used in the redox polymerization of N-isopropylacrylamide (NIPAM) in order to obtain water-based hydroxylated-soya oil polymer-g-PNIPAM graft copolymer. For this purpose, soya oil was exposed to air under sunlight to obtain autoxidized soya oil polymer (PSy-ox). PSy-ox was allowed to react with diethanol amine to obtain hydroxylated soya oil polymer (hydroxylated-PSy). An ammonium persulfate with hydroxylated-PSy redox initiating system was used in the polymerization of NIPAM in order to obtain thermo-responsive hydroxylated-PSy-g-PNIPAM water-based graft copolymers. The graft copolymers were characterized using proton nuclear magnetic resonance, Fourier transform infrared~spectroscopy, gel permeation chromatography, thermal gravimetric analysis, and differential scanning calorimetry techniques. The effects of hydroxylated-PSy on the thermal response rate of PNIPAM and the percentage of transmittance in the water of graft copolymers were studied by means of observing UV transmittance behaviors in response to changing temperature. This showed the temperature-responsive property, and exhibited a volume phase transition from 22 °C to 29 °C, while that of PNIPAM was 32 °C Daha fazlası Daha az

Synthesis and characterization of stereoregular poly(N-ethylacrylamide) hydrogel by using Y(OTf)(3) Lewis acid

Biswas, Chandra Sekhar | Hazer, Baki

Article | 2015 | COLLOID AND POLYMER SCIENCE293 ( 1 ) , pp.143 - 152

Macroporous poly(N-ethylacrylamide) (PNEAM) hydrogels have been prepared in a methanol-water (1:1, v/v) mixture in the presence of 0, 0.05, 0.1, 0.15, and 0.2 M yttrium trifluoromethanesulfonate [Y(OTf)(3)] Lewis acid (LA) concentrations. SEM micrographs show that the resulted hydrogels are highly porous. Swelling ratios of all the hydrogels in water decrease with the increase in the temperature, and the hydrogels show lower critical solution temperature (LCST) volume phase transition at around 75 A degrees C. LCST of PNEAM homopolymers gradually increases with the increase in the isotacticity of the polymers. Moreover, the hydrogel . . .s show cononsolvency in different methanol-water mixtures at 50 A degrees C. Deswelling rate of the hydrogels prepared in the presence of LA is higher than the gel prepared in the absence of LA and this rate increases with increase in the LA concentration. The reswelling rate of the hydrogels also follows the same order, that is reswelling rate also increases with the increase in the LA loading in the gels. All these results are explained on the basis of the formation of the highly porous hydrogels with a higher isotactic PNEAM chain segment in a methanol-water mixture in the presence of LA Daha fazlası Daha az

Biodegradable poly(ε-caprolactone)-based graft copolymers via poly(linoleic acid): In vitro enzymatic evaluation

Allı, Sema | Tığlı-Aydın, Rahime Seda | Allı, Abdülkadir | Hazer, Baki

Article | 2015 | JAOCS, Journal of the American Oil Chemists' Society92 ( 3 ) , pp.449 - 458

Well-defined graft copolymers based on poly(?-caprolactone) (PCL) via poly(linoleic acid) (PLina), are derived from soybean oil. Poly(linoleic acid)-g-poly(?-caprolactone) (PLina-g-PCL) and poly(linoleic acid)-g-poly(styrene)-g-poly(?-caprolactone) (PLina-g-PSt-g-PCL) were synthesized by ring-opening polymerization of ?-caprolactone initiated by PLina and one-pot synthesis of graft copolymers, and by ring-opening polymerization and free radical polymerization by using PLina, respectively. PLina-g-PCL, PLina-g-PSt-g-PCL3, and PLina-g-PSt-g-PCL4 copolymers containing 96.97, 75.04 and 80.34 mol% CL, respectively, have been investigated . . . regarding their enzymatic degradation properties in the presence of Pseudomonas lipase. In terms of weight loss, after 1 month, 51.5% of PLina-g-PCL, 18.8% of PLina-g-PSt-g-PCL3, and 38.4% of PLina-g-PSt-g-PCL4 were degraded, leaving remaining copolymers with molecular weights of 16,140, 83,220 and 70,600 Da, respectively. Introducing the PLina unit into the copolymers greatly decreased the degradation rate. The molar ratio of [CL]/[Lina] dramatically decreased, from 21.3 to 8.4, after 30 days of incubation. Moreover, reduced PCL content in PLina-g-PSt-g-PCL copolymers decreased the degradation rate, probably due to the PSt enrichment within the structure, which blocks lipase contact with PCL units. Thus, copolymerization of PCL with PLina and PSt units leads to a controllable degradation profile, which encourages the use of these polymers as promising biomaterials for tissue engineering applications. © AOCS 2015 Daha fazlası Daha az

A novel poly(propylene-co-imidazole) based biofuel cell: System optimization and operation for energy generation

Kılıç, Muhammet Samet | Korkut, Şeyda | Hazer, Baki

Article | 2015 | Materials Science and Engineering C47 , pp.165 - 171

This study describes the construction of an enzymatic fuel cell comprised of novel gold nanoparticles embedded poly(propylene-co-imidazole) coated anode and cathode. Working electrode fabrication steps and operational conditions for the fuel cell have been optimized to get enhanced power output. Electrical generation capacity of the optimized cell was tested by using the municipal wastewater sample. The enzymatic fuel cell system reached to maximum power density with 1 µg and 8 µg of polymer quantity and bilirubin oxidase on electrode surface, respectively. The maximum power output was calculated to be 5 µW cm- 2 at + 0.56 V (vs. Ag . . ./AgCl) in phosphate buffer (pH 7.4, 100 mM, 20 °C) by the addition of 15 mM of glucose as a fuel source. The optimized enzymatic fuel cell generated a power density of 0.46 µW cm- 2 for the municipal wastewater sample. Poly(propylene-co-imidazole) was easily used for a fuel cell system owing to its metallic nanoparticle content. The developed fuel cell will play a significant role for energy conversion by using glucose readily found in wastewater and in vivo mediums. © 2014 Elsevier B.V. All rights reserved Daha fazlası Daha az

Simple synthesis of amphiphilic poly(3-hydroxy alkanoate)s with pendant hydroxyl and carboxylic groups via thiol-ene photo click reactions

Hazer, Baki

Article | 2015 | Polymer Degradation and Stability119 , pp.159 - 166

Biodegradable polymers gained worldwide attention among researchers because of environmental and petroleum reserve limitation issues. In this manner, poly (3-hydroxyalkanoate)s, PHAs, are very useful materials from the point of this view. They can be easily obtained by using several bacteria from renewable substrate such as sugar, plant oils and as well as synthetic chemicals. The improvement of their mechanical properties and enhance hydrophilic character are still main challenge of the polymer scientists. Herein we report the thiol-ene photo click reactions of the unsaturated medium chain length PHAs produced by using Pseudomonas . . .oleovorans from 10-undecenoic acid, octanoic acid and/or soybean oily acids that are coded as poly(3-hydroxy undecenoate) (PHU), poly(3-hydroxy octanoate-co-undecenoate) (PHOU) and poly(3-hydroxy octanoate-co-soybean oil polymer) (PHOSy), respectively, in order to obtain their hydroxyl and carboxyl derivatives. The molecular weights of the modified PHAs obtained in this work were the same as those of the starting PHAs. Structural analysis of the PHA derivatives was performed by using 1H-, 13C, HMBC and HSQC NMR techniques. Melting and glass transitions of the hydroxyl and carboxyl derivatives of the microbial polyesters were found to be relatively higher than that of the starting unsaturated PHAs. © 2015 Elsevier Ltd. All rights reserved Daha fazlası Daha az

Determination of lead, copper, and iron in cosmetics, water, soil, and food using polyhydroxybutyrate-B-polydimethyl siloxane preconcentration and flame atomic absorption spectrometry

Ünsal, Yunus Emre | Soylak, Mustafa | Tüzen, Mustafa | Hazer, Baki

Article | 2015 | Analytical Letters48 ( 7 ) , pp.1163 - 1179

A separation and preconcentration method has been established based on solid phase extraction of Fe(III), Cu(II) and Pb(II) as their 2-(5-Bromo-2-pyridylazo)-5-diethylamino-phenol (5-Br-PADAP) chelates adsorbed on polyhydroxybutyrate-b-polydimethyl siloxane. Several analytical conditions including pH, amount of (5-Br-PADAP), eluent type and volume, sample volume, and flow rates were investigated. The effects of foreign ions on the recovery of the analytes were also studied. The detection limits for Cu(II), Fe(III), and Pb(II) were 1.9, 2.2, and 2.5 µg per liter, respectively. Enrichment factors for Cu(II), Fe(III), and Pb(II) were 1 . . .50, 200, and 80, respectively. The adsorption capacity of the polymer for Cu(II) and Pb(II) studied was 10.2 and 17.2 milligrams per gram respectively. Relative standard deviation was 4%. Standard Reference Material (SRM 1577B Bovine liver), International Atomic Energy Agency (IAEA 336 Lichen), and Certified Reference Waters for Trace Elements (TMDA 51.3 Fortified lake water) were used for the validation of the method. Optimized procedure was applied for the determination of analyte elements in various cosmetic products, hair brilliantine and gel, water, soil, and food samples from Turkey. © 2015, Copyright © Taylor & Francis Group, LLC Daha fazlası Daha az

The effect of anthelmintic triclabendazole on survival and development of Galleria mellonella (Lepidoptera: Pyralidae) L. reared on artificial diet.

Kılıç, Ali | Büyükgüzel, Kemal | Büyükgüzel, Ender

Article | 2015 | KAFKAS UNIVERSITESI VETERINER FAKULTESI DERGISI21 ( 6 ) , pp.841 - 847

The effect of triclabendazole, which is a benzimidazole anthelmintic, on the survival rate and developmental time in different stages of greater wax moth Galleria mellonella (L.) was investigated by rearing the larvae on the artificial diets. Triclabendazole was incorporated into diets at concentrations of 0.001, 0.01 or 0.1%. G. mellonella larvae was reared from first instar larvae to adult emergence on the artificial diets with different concentrations of triclabendazole. The survival rate in seventh instar (7th-instar) and adult stage were significantly lower at low concentrations of this anthelmintic agent (0.001 and 0.01 g per . . .100 g of diet) than the control, while there were no differences on pupation in comparison to control diet. However, the pupation and adult emergence were significantly lower at the highest dietary concentration of triclabendazole than control group but there were no differences on survival of 7th-instar larvae. The highest concentration of the anthelmintic agent (0.1 g/100 g diet) decreased pupation from 81.6 +/- 4.32% to 43.3 +/- 7.45%, adult emergence rate from 73.3 +/- 2.36 to 13.3 +/- 2.36. Triclabendazole at the highest concentration prolonged developmental time to 7th larval stage by 3.8 days reaching total 22.8 +/- 1.54 days. This diet containing 0.1% of triclabendazole significantly prolonged pupal developmental time from 24.6 +/- 1.24 days to 28.4 +/- 1.24 days, adult developmental time from 35.3 +/- 1.27 days to 42.0 +/- 1.62 days. This study is of importance in appreciation for usage of antihelmintic with different structure and mode of actions in the management of pest insects to reduce damage to environment and nontarget organisms Daha fazlası Daha az

Synthesis of pH- and thermo-responsive poly (ε-caprolactone-b-4-vinyl benzyl-g-dimethyl amino ethyl methacrylate) brush type graft copolymers via RAFT polymerization

Şanal, Timur | Oruç, Olgu | Öztürk, Temel | Hazer, Baki

Article | 2015 | JOURNAL OF POLYMER RESEARCH22 ( 2 ) , pp.841 - 847

A novel pH-and thermo-responsive poly (epsilon-caprolactone-b-4-vinyl benzyl-g-2-(dimethyl amino ethyl) methacrylate), poly (CL-b-VB-g-DMAEMA), brush type copolymer has been described. In this study, a reversible addition-fragmentation chain transfer (RAFT) agent, 1,2-propanediol- 3-ethyl xanthogenate, was obtained through the reaction of 3-chloro-1,2-propanediol with potassium salt of ethyl xanthogenate. Poly (CL-b-VB) block copolymer was synthesized in one-pot polymerization of e-caprolactone (CL) and 4-vinyl benzyl chloride (VB) using a new dual macro-RAFT agent. In the second step of the work, chloride side groups of poly-VB in . . .poly (CL-b-VB) block copolymer were reacted with potassium salt of ethyl xanthogenate to obtain another novel macro-RAFT agent, poly (CL-b-VB)-g-xanthate (PCL-PVB-Xa). Controlled free radical living polymerization of 2-(dimethylaminoethyl) methacrylate (DMAEMA) was initiated with this PCL-VB-Xa macro-RAFT agent to obtain new poly (CL-b-VB-g-DMAEMA) comb type pH-and thermo-responsive heterograft copolymer. The homopolymer was soluble in water at pH=10-11 and not soluble at pH=12.5. A pH-sensitive feature of the brush type graft copolymer was observed between pH9.4 and 11.5 in view of their swelling/solution properties depending on the acrylic polymer inclusion. The LCST values of the multiblock brush type copolymers were found to be as low as 42.8 degrees C, while that of PDMAEMA homopolymer was 46.6 degrees C. The characterization of the products was achieved using gel-permeation chromatography (GPC), thermal, and spectrometric analysis techniques. pH- and thermo-responsiveness of the copolymers were verified by surface tension and zeta potential measurements Daha fazlası Daha az

Effect of the composition of methanol-water mixtures on tacticity of poly(N-ethylacrylamide) gel

Biswas, Chandra Sekhar | Sulu, Elvan | Hazer, Baki

Article | 2015 | Journal of Applied Polymer Science132 ( 12 ) , pp.841 - 847

Two series of macroporous poly(N-ethylacrylamide) (PNEAM) gels are synthesized in different composition of methanol-water mixtures (xm=0, 0.06, 0.13, 0.21, 0.31, and 0.43; where xm=mole fraction of methanol) in presence as well as in the absence of 0.1M Y(OTf)3 Lewis acid as additive. The gels synthesized in the absence of Lewis acid are atactic and in the presence of the same are isotactic. Synthesis of the corresponding linear PNEAM homopolymers shows that, the isotacticity (meso dyad, %) of the resulted polymers increases for the gels prepared in the presence of Lewis acid (LA) and remains constant for the gel prepared in the abs . . .ence of LA, respectively, with the increase in the concentration of the synthesis solvent methanol. SEM micrographs reveal that, the hydrogels synthesized in the presence of LA are more porous than the gels prepared in the absence of LA. Swelling ratio of all the hydrogels decreases with the increase in the temperature and LA gels show higher swelling ratio values than non LA gels (NLA). Deswelling rate of the hydrogels prepared in methanol-water mixture in presence of LA is faster than the hydrogels prepared in absence of LA. Moreover, reswelling rate increases with increase in the isotacticity of the PNEAM segment in the gel. All these results have been explained on the basis of the formation of highly porous hydrogels with higher isotactic PNEAM chain segment in the presence of LA in methanol-water mixtures. © 2014 Wiley Periodicals, Inc Daha fazlası Daha az

The effects of xanthotoxin on the biology and biochemistry of galleria mellonella L. (lepidoptera: Pyralidae)

Erdem, Meltem | Büyükgüzel, Ender

Article | 2015 | Archives of Insect Biochemistry and Physiology89 ( 4 ) , pp.193 - 203

The effects of a dietary plant allelochemical, xanthotoxin (XA), on survivorship, development, male and female adult longevity, fecundity, and hatchability of the greater wax moth Galleria mellonella L. were investigated. Oxidative stress indicators, the lipid peroxidation product, malondialdehyde (MDA), and protein oxidation products, protein carbonyl (PCO) contents, and activities of a detoxification enzyme glutathione S-transferase (GST) activity were determined in wax moth adults. The insect was reared from first-instar larvae on an artificial diets containing XA at 0.001, 0.005, or 0.1% to adult stage in laboratory conditions. . . .Relative to the controls, the diets containing XA concentrations led to decreased survivorship in seventh instar, pupal, and adult stages. Compared to control diet (77.7%), the highest dietary XA concentration decreased survivorship to adulthood to 11.0%. The highest XA concentration (0.1%) reduced female longevity from 10.4 to 5.7 days and decreased egg numbers from 95.0 to 33.5 and hatchability from 82.7 to 35.6%. The lowest XA concentration (0.001%) led to about a sixfold increase in MDA content. XA at high concentrations (0.005 and 0.1%) increased MDA (by threefold) and protein carbonyl (by twofold) contents decreased GST activity. The highest dietary XA concentration decreased GST activity from 0.28 ± 0.025 to 0.16 ± 0.005 µmol/mg protein/min. We infer from these findings that XA-induced oxidative stress led to decreased biological fitness. © 2015 Wiley Periodicals, Inc Daha fazlası Daha az

Antihelmintik triklabendazolun yapay besin ile beslenen Galleria mellonella (Lepidoptera: Pyralidae) larvalarının yaşama ve gelişimine etkisi

Kılıç, Ali | Büyükgüzel, Kemal | Büyükgüzel, Ender

Article | 2015 | Kafkas Üniversitesi Veteriner Fakültesi Dergisi21 ( 6 ) , pp.841 - 847

Benzimidazol grubu bir antihelmintik olan triklabendazolun yapay besin kullanılarak Büyük bal mumu güvesi Galleria mellonella (L.) larvalarının ergin evreye kadar farklı gelişme evrelerinde yaşama oranına ve gelişme süresine etkisi incelendi. Triklabendazol yapay besine %0.001, 0.01 ve 0.1 oranlarında ilave edilerek birinci evre larvaları besinlerde ergin oluncaya kadar yetiştirildi. Antihelmintik maddenin düşük konsantrasyonlarında (0.001 ve 0.01 g/100 g besin), son evre larva oranı (7. evre) ve ergin olma oranı kontrole göre önemli derecede düşük bulunurken, pupa olma oranı bakımından kontrol ile arasında istatistiksel farklılık o . . .luşmadı. Bunun tersine, denenen antihelmintik maddenin en yüksek besinsel konsantrasyonunda, pupa evresine ve ergin evreye ulaşma oranı kontrol grubundan önemli derecede düşük tespit edilirken 7. evreye ulaşan larva oranı bakımından kontrol ile arasında farklılık görülmedi. Triklabendazolun en yüksek konsantrasyonu (0.1 g/100 g besin) pupa olma oranını %81.6±4.32'den %43.3±7.45'e, ergin olma oranını %73.3±2.36'dan %13.3±2.36'ya düşürdü. En yüksek antihelmintik konsantrasyonu 7. evreye ulaşma süresini yaklaşık 3.8 gün uzatarak 22.8±1.54 güne ulaştırdı. Triklabendazolun %0.1 oranını içeren besin kontrol besinindeki 24.6±1.24 gün olan pupa olma süresini 28.4±1.24 güne, 35.3±1.27 gün olan ergin olma süresini 42.0±1.62 güne önemli derecede uzattı. Bu çalışma farklı kimyasal yapı ve etki mekanizmasına sahip antihelmintiklerin zararlı böceklerin mücadelesinde hedef olmayan canlılara ve çevreye karşı en az zararla kullanılabilirliğinin araştırılması açısından önemlidir The effect of triclabendazole, which is a benzimidazole anthelmintic, on the survival rate and developmental time in different stages of greater wax moth Galleria mellonella (L.) was investigated by rearing the larvae on the artificial diets. Triclabendazole was incorporated into diets at concentrations of 0.001, 0.01 or 0.1%. G. mellonella larvae was reared from first instar larvae to adult emergence on the artificial diets with different concentrations of triclabendazole. The survival rate in seventh instar (7th-instar) and adult stage were significantly lower at low concentrations of this anthelmintic agent (0.001 and 0.01 g per 100 g of diet) than the control, while there were no differences on pupation in comparison to control diet. However, the pupation and adult emergence were significantly lower at the highest dietary concentration of triclabendazole than control group but there were no differences on survival of 7th-instar larvae. The highest concentration of the anthelmintic agent (0.1 g/100 g diet) decreased pupation from 81.6±4.32% to 43.3±7.45%, adult emergence rate from 73.3±2.36 to 13.3±2.36. Triclabendazole at the highest concentration prolonged developmental time to 7th larval stage by 3.8 days reaching total 22.8±1.54 days. This diet containing 0.1% of triclabendazole significantly prolonged pupal developmental time from 24.6±1.24 days to 28.4±1.24 days, adult developmental time from 35.3±1.27 days to 42.0±1.62 days. This study is of importance in appreciation for usage of antihelmintic with different structure and mode of actions in the management of pest insects to reduce damage to environment and nontarget organism Daha fazlası Daha az


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