Yazar "Dogru, Mehmet" seçeneğine göre listele

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    Barrier height enhancement of metal/semiconductor contact by an enzyme biofilm interlayer
    (Taylor & Francis Ltd, 2013) Ocak, Yusuf Selim; Guven, Reyhan Gul; Tombak, Ahmet; Kilicoglu, Tahsin; Guven, Kemal; Dogru, Mehmet
    A metal/interlayer/semiconductor (Al/enzyme/p-Si) MIS device was fabricated using -amylase enzyme as a thin biofilm interlayer. It was observed that the device showed an excellent rectifying behavior and the barrier height value of 0.78eV for Al/-amylase/p-Si was meaningfully larger than the one of 0.58eV for conventional Al/p-Si metal/semiconductor (MS) contact. Enhancement of the interfacial potential barrier of Al/p-Si MS diode was realized using enzyme interlayer by influencing the space charge region of Si semiconductor. The electrical properties of the structure were executed by the help of current-voltage and capacitance-voltage measurements. The photovoltaic properties of the structure were executed under a solar simulator with AM1.5 global filter between 40 and 100mW/cm(2) illumination conditions. It was also reported that the -amylase enzyme produced from Bacillus licheniformis had a 3.65eV band gap value obtained from optical method.
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    Biosorption of Cd+2, Cu+2, and Ni+2 Ions by a Thermophilic Haloalkalitolerant Bacterial Strain (KG9) Immobilized on Amberlite XAD-4
    (Hard, 2015) Alkan, Huseyin; Gul-Guven, Reyhan; Guven, Kemal; Erdogan, Salt; Dogru, Mehmet
    A newly isolated thermophilic haloalkalitolerant bacterial strain (KG9) as immobilized cells on a solid support was presented as a new biosorbent for the enrichment of Cd(II), Cu(II), and Ni(II) prior to flame atomic absorption spectrometric analysis. The KG9 strain was identified as a close member of Bacillus licheniformis following complete sequencing of 16S rRNA. The optimum conditions such as pH, amount of adsorbent, eluent type and volume, flow rate of sample solution, volume of sample solution, and matrix interference effect on the retention of the metal ions were evaluated for the quantitative recovery of the analytes. The analyte ions were quantitatively recovered and desorbed at pH range of 6.0-7.0 and 5 mL of 0.5 mol.L-1 HCl. The loading capacities of adsorbents for Cd(II), Cu(II), and Nip were found to be 22.7, 61.1, and 33.4 mu mol.g(-1) respectively. The analytical detection limits for cadmium(II), copper(II), and nickel(II) were 0.42 mu g.L-1, 0.54 mu g.L-1, and 1.24 mu g.L-1. The proposed procedure was applied for the determination of metal ions in river water, drinking water, and mushrooms. The accuracy of the developed procedure was tested by analyzing NRCC-SLRS4 riverine water and SRM1570a spinach leaves as the certified reference materials.
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    Comparison of the Effect of Periodontal Therapy and Diode Decontamination and Periodontal Therapy Alone on the Amount of TNF-? in Systemically Healthy Chronic Periodontitis Patients A Non-Randomized Clinical Trial
    (Sci Printers & Publ Inc, 2020) Dogru, Arzum Guler; Toprak, Omer; Uner, Devrim Deniz; Izol, Bozan Serhat; Kaplan, Ibrahim; Dogru, Mehmet; Ipek, Fikret
    OBJECTIVE: To evaluate the outcome of initial periodontal therapy and additional diode laser decontamination therapy on clinical parameters and the amount of tumor necrosis factor alpha (TNF-alpha) in gingival crevicular fluid (GCF) in patients with chronic periodontitis. STUDY DESIGN: The study included 22 patients who were diagnosed with chronic periodontitis and who had at least 1 (>= 5 mm) periodontal pocket in the posterior region of each upper left hemi-arcade. The study was designed as a split-mouth study involving mechanical therapy on the right side and nonsurgical periodontal therapy plus diode laser decontamination therapy on the left side. RESULTS: A statistically significant decrease was observed in clinical parameters at 3 months when compared to the values at baseline in both treatment areas. The change in clinical parameters at 3 months after therapy was not significantly different between the groups (p>0.05). The comparison of GCF TNF-alpha levels at baseline and at 3 months in the 2 treatment areas identified significant changes in the TNF-alpha levels in the hemi-arcade treated with laser diode contamination therapy, whereas the changes in the hemi-arcade treated with nonsurgical periodontal therapy were not significant (p>0.05). A between-group comparison revealed no statistically significant difference at 3 months post-therapy, while the difference at 1 month was found to be statistically significant. CONCLUSION: The study found that laser therapy in addition to nonsurgical periodontal therapy has a positive effect on the clinical parameters and proinflammatory TNF-alpha levels in the early period but makes no contribution in the long term.
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    Cu2+-attached pumice particles embedded composite cryogels for protein purification
    (Taylor & Francis Ltd, 2017) Alkan, Hueseyin; Comert, Seyda Ceylan; Gurbuz, Fatma; Dogru, Mehmet; Odabasi, Mehmet
    In this study, chromatographic performance of Cu2+-attached pumice particles embedded to monolithic cryogels (Cu2+-APPsEMC) for human serum albumin (HSA) was investigated. Monolithic composite cryogels were prepared by means of polymerization of gel-forming precursors at sub-zero temperatures. The chemical composition of pumice and surface of composite cryogels were determined by X-ray fluorescence spectrometer and scanning electron microscopy, respectively. The highest adsorption capacity (549.5 mg/g pumice) of cryogels was achieved at phosphate buffer of pH 8.0 with initial HSA solution of 3 mg/ml. SDS-PAGE analysis was performed for the samples studied on human serum to determine HSA adsorption/desorption performance of cryogel qualitatively.
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    Dyeing of wool fibres with synthetic dyes and effect of proteolytic enzymes
    (Asian Journal Of Chemistry, 2007) Dogru, Mehmet; Aytekin, Cetin
    In spite of protein and protein fragments (casein, peptone. etc.) are used widespread as a Substrate for the proteolytic enzymes, the substrate prepared from dyes that adsorbed on appropriate material, such as wool and cotton are also used for enzymes activity determination. The object of this work is to develop the substrates which are easily and economically obtainable and also environmental safer, for the frequently used proteolytic enzymes such as subtilisin carlsberg, trypsin, chymotrypsin and protease type XV1 and if it is possible to prepare the specific substrate at least for one of this enzymes. For this aim, wool was dyed with synthetic dyes such as procion yellow, procion red and procion blue. The results indicate that the most appropriate complex was found to be wool-procion yellow and the most unappropriate complex was found to be wool-procion blue complex.
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    The Effects of Extraction and Non-Extraction Treatment on RME Applied Patients
    (Aves Press Ltd, 2010) Hamamci, Nihal; Akkurt, Atilim; Dogru, Mehmet; Veli, Ilknur; Hamamci, Orhan
    Aim: The aim of this study was to compare the dentoalveolar, skeletal and soft tissue effects of upper two premolar extraction or nonextraction treatments after Rapid Maxillary Expansion (RME). Subjects and Methods: The sample of this study consisted of pre and posttreatment lateral cephalometric radiographs of 21 patients characterized by narrow maxilla and treated with or without extraction following RME. In our study, RME applied patients were divided into two groups as extraction and nonextraction. After adequate expansion and retention period, two upper first premolars were extracted in extraction group and no teeth were extracted in nonextraction group. Thereafter, fixed orthodontic treatment was started in two groups. Results: At the end of treatment when extraction and nonextraction groups were compared, significant differences in A1 inclination to A-Po angle (p < 0.01), A1 to A-Po plane (p < 0.05) and B1 to A-Po plane distance (p < 0.05) representing the dentoalveolar incisor position were detected. Also statistically no significant differences were found between parameters related to lips or soft tissues. Our results do not support the idea that more retrusive profile occurs as a result of upper extraction treatment. Conclusions: In the light of these results, it is possible to say that there is no esthetic difference between the RME appliances patient treated by either upper premolar extraction or nonextraction treatment.
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    Effects of Various Inhibitors on ?-galactosidase Purified from the Thermoacidophilic Alicyclobacillus acidocaldarius Subsp Rittmannii Isolated from Antarctica
    (Korean Soc Biotechnology & Bioengineering, 2011) Guven, Reyhan Gul; Kaplan, Alevcan; Guven, Kemal; Matpan, Fatma; Dogru, Mehmet
    beta-Galactosidase purified from the thermoacidophilic Alicyclobacillus acidocaldarius subsp. rittmannii isolated from Antarctica is a member of the GH42 family. The enzyme was not effected by various concentrations of its reaction product glucose, but was greatly inhibited by the other reaction product galactose using both substrates, ONPG and lactose. Linewever-Burk plot analysis derived from both ONPG and lactose hydrolysis results showed that galactose is a mixed-type inhibitor of the purified beta-galactosidase. The enzyme was slightly activated by Mg(2+) (13% at 20 mM), while inhibited at higher concentrations of Ca(+2) (33% at 10 mM), Zn(+2) (86% at 8 mM) and Cu(+2) (87% at 4 mM). The enzyme activity was not significantly altered by the metal ion chelators EDTA and 1,10-phenanthroline up to 20 mM, indicating that this enzyme is not a metalloenzyme. 2-Mercaptoethanol and DTT were found to enhance beta-galactosidase activity, while p-chloromercuribenzoic acid (PCMB) completely inhibited enzymatic activity (97% at 1 mM; 99.7% at 2 mM), indicating at least one essential Cys residue modified by the reagents in the active site of beta-galactosidase. Iodoacetamide and N-ethylmaleimide had little effect on the beta-galactosidase. Phenylmethylsulfonyl fluoride (PMSF) inhibited the enzyme strongly (19.8% at 1 mM; 71.9% at 10 mM), also showing the participation of serine for enzyme activity.
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    Equilibrium and thermodynamic studies on biosorption of Pb(II) onto Candida albicans biomass
    (Elsevier Science Bv, 2009) Baysal, Zuebeyde; Cinar, Ercan; Bulut, Yasemin; Alkan, Hueseyin; Dogru, Mehmet
    Biosorption of Pb(II) ions from aqueous solutions was studied in a batch system by using Candida albicans. The optimum conditions of biosorption were determined by investigating the initial metal ion concentration, contact time, temperature, biosorbent dose and pH. The extent of metal ion removed increased with increasing contact time, initial metal ion concentration and temperature. Biosorption equilibrium time was observed in 30 min. The Freundlich and Langmuir adsorption models were used for the mathematical description of biosorption equilibrium and isotherm constants were also evaluated. The maximum biosorption capacity of Pb(II) on C. albicans was determined as 828.50 +/- 1.05, 831.26 +/- 1.30 and 833.33 +/- 1.12 mg g(-1), respectively, at different temperatures (25, 35 and 45 degrees C). Biosorption showed pseudo second-order rate kinetics at different initial concentration of Pb(II) and different temperatures. The activation energy of the biosorption (E-a) was estimated as 59.04 kJ mol(-1) from Arrhenius equation. Using the equilibrium constant value obtained at different temperatures, the thermodynamic properties of the biosorption (Delta G degrees, Delta H degrees and Delta S degrees) were also determined. The results showed that biosorption of Pb(II) ions on C. albicans were endothermic and spontaneous. The optimum initial pH for Pb(II) was determined as pH 5.0. FTIR spectral analysis of Pb(II) adsorbed and unadsorbed C. albicans biomass was also discussed. (C) 2008 Elsevier B.V. All rights reserved.
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    Examination of extremely low frequency electromagnetic fields on orthodontic tooth movement in rats
    (Taylor & Francis Ltd, 2014) Dogru, Mehmet; Akpolat, Veysi; Dogru, Arzum Guler; Karadede, Beyza; Akkurt, Atilim; Karadede, M. Irfan
    The purpose of this study was to evaluate whether 50 Hz extremely low frequency electromagnetic fields (ELF-EMFs) affect the amount of orthodontic tooth movement in rats. The experiments were performed on 18 male Sprague-Dawley rats. The rats were randomly divided into three groups (n = 6): cage-control (Cg-Cnt) group (n = 6); sinusoidal electromagnetic field (SEMF) group (n = 6); and pulsed electromagnetic field (PEMF) group (n = 6). In SEMF and PEMF groups, rats were subjected to 1.5 mT EMF exposure eight hours per day for eight days. In order to obtain tooth movement, holes were drilled on the right and left maxillary central incisors of the rats at a distance 1.5-2 mm away from the gingiva and 20 g of orthodontic forces were applied to the teeth. Generated linear model for repeated measures and Bonferroni tests were used to evaluate the differences between the groups. Interactions among groups by days were found by using Pillai's trace multivariate test. The results showed that significant differences were present among the groups (F = 5.035; p = 0.03) according to the extent of tooth movement. Significant differences between the amount of tooth movements were determined especially after the fifth day and the following days six, seven and eight (p < 0.001). Within the limitations, according to the results of the present study, the application of ELF-EMF accelerated the orthodontic tooth movement in rats.
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    In Vitro Evaluation of Shear Bond Strength of Two Different Fluoride-Releasing Sealants
    (Sci Printers & Publ Inc, 2021) Dogru, Mehmet; Salman, Afsin
    OBJECTIVE: To evaluate shear bond strength of 2 different fluoride-releasing sealants and their adhesive remnant index (ARI). STUDY DESIGN: A total of 105 extracted human maxillary premolars were divided into 3 groups of 35. Slot brackets (0.018-inch) were bonded to buccal surfaces of teeth using Pro Seal, Opal Seal, and, as a control group, Transbond XT. Transbond XT Composite was used only as an adhesive material. All samples were subjected to thermocycling for 5,000 cycles in water baths between 5 degrees C and 55 degrees C. Subsequently, the shear bond strengths of specimens were determined under loads vertically at 0.5 mm/min crosshead speed until rupture occurred. After the shear bond strength test, specimens were examined with a stereomicroscope at x20 magnification and grouped according to ARI analysis. Statistical analyses were performed using one-way ANOVA analysis of variance for shear bond strength data and Kruskal-Wallis and Mann-Whitney U tests for ARI analysis. RESULTS: There was no significant difference between all the groups (p>0.05) with regard to shear bond strength. According to ARI analyses, the control group was statistically different from both the Pro Seal and Opal Seal groups (p <0.05). However, there was no significant difference between the Pro Seal and Opal Seal groups for ARI analyses. CONCLUSION: The results of this study showed that the potential of caries and white spot lesions during orthodontic treatment can be decreased by using new fluoride-releasing sealants. However, this is an in vitro study and these results should be supported with clinical studies.
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    Preconcentration of cadmium and nickel using the bioadsorbent Geobacillus thermoleovorans subsp stromboliensis immobilized on Amberlite XAD-4
    (Springer Wien, 2010) Ozdemir, Sadin; Gul-Guven, Reyhan; Kilinc, Ersin; Dogru, Mehmet; Erdogan, Sait
    Cadmium and nickel ions have been preconcentrated on Geobacillus thermoleovorans subsp. stromboliensis, immobilized on Amberlite XAD-4, and were determined by flame atomic absorption spectrometry (FAAS). Parameters such as pH, amount of adsorbent, eluent type and volume, flow rate of solution and the matrix interference effect on retention have been studied, and extraction conditions were optimized. Elution of Cd(II) and Ni(II) from minicolumns was carried out with 1.0 M hydrochloric acid or nitric acid with recoveries from 97 to 100%. The sorption capacity is 0.0373 and 0.0557 mmol g(-1) for Cd(II) and Ni(II), respectively. The detection limits were 0.24 mu g L-1 for cadmium and 0.3 mu g L-1 for nickel. The relative standard deviations of the procedure were below 10%. The procedure was validated by analyzing certified reference materials and applied to the determination of Cd(II) and Ni(II) in natural water and food samples.
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    Production of extracellular alkaline ?-amylase by solid state fermentation with a newly isolated Bacillus sp.
    (Taylor & Francis Inc, 2008) Baysal, Zuebeyde; Uyar, Fikret; Dogru, Mehmet; Alkan, Hueseyin
    Production of alkaline -amylase employing our laboratory isolate, Bacillus sp., under solid state fermentation, was optimized. The effect of wheat bran and lentil husk was examined. Lentil husk exhibited the highest enzyme production. The appropriate incubation time, inoculum size, moisture level, and buffer solution level were determined. Maximum yields of 216,000 and 172,800 U/g were achieved by employing lentil husk and wheat bran as substrates in 0.1 M carbonate/bicarbonate buffer at pH 10.0 with 30% initial moisture level at 24h. Inoculum size and buffer solution level were found to be 20% and 1:0.5 for two solid substrates.
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    Production of lipase by a newly isolated Bacillus coagulans under solid-state fermentation using melon wastes
    (Humana Press Inc, 2007) Alkan, Huseyin; Baysal, Zubeyde; Uyar, Fikret; Dogru, Mehmet
    An extracellular lipase was produced by Bacillus coagulans by solid-state fermentation. Solid waste from melon was used as the basic nutrient source and was supplemented with olive oil. The highest lipase production (78,069 U/g) was achieved after 24 h of cultivation with 1% olive oil enrichment. Enzyme had an optimal activity at 37 degrees C and pH 7.0, and sodium dodecyl sulfate increased lipase activity. NH4NO3 increased enzyme production, whereas organic nitrogen had no effect. The effect of the type of carbon sources on lipolytic enzyme production was also studied. The best results were obtained with starch and maltose (148,932 and 141,629 U/g, respectively), whereas a rather low enzyme activity was found in cultures grown on glucose and galactose (approx 118,769 and 123,622 U/g, respectively). Enzyme was inhibited with Mn+2 and Ni+2 by 68 and 74%, respectively. By contrast, Ca+2 enhanced enzyme production by 5%.
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    Three dimensional evaluation of the effect of rapid maxillary expansion on maxillary sinus volume
    (Elsevier, 2022) Akkurt, Atilim; Dogru, Mehmet
    Aim: To compare the maxillary sinus volume (MSV) of posterior cross bite (PCB) patients before and after rapid maxillary expansion (RME) by cone-beam computed tomography (CBCT).Methods: A total of 24 patients' CBCT scans that underwent RME therapy for their orthodontic treatment were used. CBCTs were obtained before (T1), immediately after (T2), and 6 months after (T3) RME. MSVs were calculated by using the 3D module of Dolphin 11.0 software. Repeated measures ANOVA (RMANOVA) was used to identify the MSV differences.Results: The results showed no significant differences between the right and left MSVs of the T1 group (p>.05). No significant differences were found between the right and left side MSV of the T2 group (p>.05). There were no significant differences between the right and left side MSV of the T3 group (p>.05). According to the intergroup comparisons, the RMANOVA test results revealed statistically significant right (F = 459.37, p<.001), left (F = 409.34, p<.001), and mean (F = 489.33, p<.001) MSV differences between groups. Multiple comparisons of the right, left, and mean MSV between the T1 and T2, T2 and T3, and T1 and T3 groups with Bonferroni's test revealed no significant differences between the T1 and T2 (p>.05) and T2 and T3 (p>.05) groups. However, significant differences were found in the right (p<.05), left (p<.05), and mean (p<.05) MSV between the T1 and T3 groups. The right, left, and mean MSV of the T3 group were significantly higher than those of the T1 group.Conclusion: No significant change was detected in the MSV immediately after RME. However, MSV was signif-icantly increased at the end of the retention period.(c) 2022 Elsevier Masson SAS. All rights reserved.
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    The use of Bacillus subtilis immobilized on Amberlite XAD-4 as a new biosorbent in trace metal determination
    (Elsevier Science Bv, 2007) Dogru, Mehmet; Gul-Guven, Reyhan; Erdogan, Sait
    The present work proposes the use of Bacillus subtilis immobilized on Amberlite XAD-4 as new biosorbent in trace metal determination. The procedure is based on the biosorption of Cu and Cd ions on a column of Amberlite XAD-4 resin loaded with dried, dead bacterial components prior to their determination by flame AAS. Various parameters such as pH, amount of adsorbent, eluent type and volume, flow rate of solution and matrix interference effect on the retention of the metal ions have been studied. The optimum pH values of quantitative sorption for Cu and Cd were found to be 7.0 and 7.5, respectively. These metal ions can be desorbed with 1 M HCl (recovery, 96-100%). The,sorption capacity of the resin was 0.0297 and 0.035 mmol g(-1) for Cu(2+) and Cd(2+), respectively. The tolerance limit of some electrolytes were also studied. This procedure was applied to Cu(2+) and Cd(2+) determination in aqueous solutions, including river and well water systems. In order to evaluate the accuracy of the proposed procedure, the certified reference materials, NRCC-SLRS-4 Riverine water and LGC7162 Strawberry leaves were analyzed. (C) 2007 Elsevier B.V. All rights reserved.