Browsing by Publisher "Springer Netherlands"
Now showing 1 - 20 of 20
Results Per Page
Sort Options
Item Freeness conditions for crossed squares and squared complexes(Springer Netherlands, 2000) Mutlu A.; Porter T.Following Ellis, we investigate the notion of totally free crossed square and related squared complexes. It is shown how to interpret the information in a free simplicial group given with a choice of CW-basis, in terms of the data for a totally free crossed square. Results of Ellis then apply to give a description in terms of tensor products of crossed modules. The paper ends with a purely algebraic derivation of a result of Brown and Loday.Item Iterated Peiffer pairings in the Moore complex of a simplicial group(Springer Netherlands, 2001) Mutlu A.; Porter T.We introduce a pairing structure within the Moore complex NG of a simplicial group G and use it to investigate generators for NGn ∩ Dn where Dn is the subgroup generated by degenerate elements. This is applied to the study of algebraic models for homotopy types.Item N-Heterocyclic carbene complexes of palladium(II) and rhodium(I) with pendant ferrocenylmethyl groups: Synthesis and electrochemistry(Springer Netherlands, 2003) Demirhan F.; Yıldırım Ö.; Çetinkaya B.1-Ferrocenylmethyl-3-benzylimidazolidinium iodide and 1-ferrocenylmethyl-3-(2,4,6-trimethylbenzyl)imidazolidinium iodide were prepared in good yields by boiling, under reflux, a solution of (ferrocenylmethyl)-trimethylammonium iodide and the appropriate N-alkyl-2-imidazoline in MeCN. From the 1-ferrocenylmethyl-3-ben- zylimidazolidinium iodide salt, N-heterocylic carbene complexes of Pd II and Rh I were synthesized by in situ deprotonation and subsequent trapping. The new compounds were characterized by C, H, N analyses, 1 H-n.m.r., 13 C-n.m.r. and by cyclic voltammetry. The n.m.r. properties of the complexes are compared with those of nonferrocenylated carbene derivatives. The c.v.'s of these compounds show a number of resolved redox processes, indicating that CH 2 Fc substituents are electronically isolated from the remaining molecular framework.Item Preliminary tests of the radiopharmaceutical potential of N-(2,6-diisopropylphenyl)-N'-(4-pyridyl)-perylene-3,4,9,10-tetracarboxylic diimide radiolabeled with 131 I(Springer Netherlands, 2007) Avcıbaşı U.; Dinçalp H.; Ünak T.; Yıldırım Y.; Avcibaşi N.; Duman Y.; Içli S.Perylene diimide denvatives are one of the G-quadruplex DNA interactive agents which are thought to be useful in application of cancer treatment Starting from this consideration, N-(2,6-diisopropylphenyl)-N'-(4-pyridyl)- perylene-3,4,9,10-tetracarboxylic diimide (PYPER) was synthesized, radioiodinated with 131 I, and its radiopharmaceutical potentials were tested on a male Albino rabbit and male Albino Wistar rats. This compound was successfully radioiodinated with 131 I with a radioiodination yield of about 100%. Scintigraphic imaging with the radiiodinated compound ( 131 I-PYPER) was performed on a rabbit. Static images were obtained from posterior projection using a Diacan gamma camera at several time intervals. The scintigrams clearly showed that the radioiodinated compound was not quickly cleared from the metabolism, accumulating in the stomach over about 30 minutes. The clearance time of this compound was considerably longer than 5 hours. The results obtained in this study agreed with that of the biodistribution studies and indicated that 131 I-PYPER might be used as a scintigraphic agent for examining stomach diseases. © 2007 Springer Science+Business Media, Inc.Item Impact of hemostatic gene single point mutations in patients with non-diabetic coronary artery disease(Springer Netherlands, 2009) Var A.; Ütük O.; Akçalı S.; Şanlıdağ T.; Uyanık B.S.; Dinç G.Single point mutations in the genes coding for hemostatic factors were shown to be major inherited predisposing factors for venous thromboembolism. However, their contribution in the development of non-diabetic coronary artery disease [nDCAD] remains controversial. Angiographically demonstrated nDCAD patients (n = 86) and healthy controls (n = 90) were included in the study. Genotype analysis of hemostatic gene polymorphisms were assessed by using CVD strip assay, based on allele specific oligonucleotide probes. The carrier frequency of factor V (FV) H1299R, prothrombin G20210A, glycoprotein (Gp) IIIa L33P, plasminogen activator inhibitor-I (PAI-1) 4G/5G, 4G/4G, 5G/5G, methylenetetrahydrofolate reductase (MTHFR) A1298C and β-fibrinogen -455 G > A were similar between patients and controls. In contrast, frequency of FV Leiden was significantly higher among patients (12.5%) than controls (5%, OR: 7.94; 95%CI: 1.9-49.6) and FXIII V34L was significantly lower among patients (23.7%) than controls (40%, OR: 0.24; 95%CI: 0.1-0.89). In addition, the frequency of the MTHFR C677T polymorphism was 32.5% among patients compared with 42.5% in controls, of which the T/T genotype was significantly lower among patients (5%) than controls (17.5%, OR: 0.06; 95%CI: 0.01-0.58). No difference was observed in prevalence of prothrombin G20210A, FV H1299R, Gp IIIa L33P, PAI-1 4G5G, MTHFR A1298C, β fibrinogen 455 G > A mutations between patients and controls. However, lower frequency of FXIII Val34Leu and MTHFR C677T polymorphisms may decrease, while FV Leiden polymorphism may increase development of nDCAD. © 2009 Springer Science+Business Media B.V.Item Three-to-one internal resonance in multiple stepped beam systems(Springer Netherlands, 2009) Tekin A.; Özkaya E.; Bağdatlı S.M.In this study, the vibrations of multiple stepped beams with cubic nonlinearities are considered. A three-to-one internal resonance case is investigated for the system. A general approximate solution to the problem is found using the method of multiple scales (a perturbation technique). The modulation equations of the amplitudes and the phases are derived for two modes. These equations are utilized to determine steady state solutions and their stabilities. It is assumed that the external forcing frequency is close to the lower frequency. For the numeric part of the study, the three-to-one ratio in natural frequencies is investigated. These values are observed to be between the first and second natural frequencies in the cases of the clamped-clamped and clamped-pinned supports, and between the second and third natural frequencies in the case of the pinned-pinned support. Finally, a numeric algorithm is used to solve the three-to-one internal resonance. The first mode is externally excited for the clamped-clamped and clamped-pinned supports, and the second mode is externally excited for the pinned-pinned support. Then, the amplitudes of the first and second modes are investigated when the first mode is externally excited. The amplitudes of the second and third modes are investigated when the second mode is externally excited. The force-response, damping-response, and frequency-response curves are plotted for the internal resonance modes of vibrations. The stability analysis is carried out for these plots. © 2009 Shanghai University and Springer Berlin Heidelberg.Item Investigation of therapeutic efficiency of phenytoin (PHT) labeled with radioactive 131I in the cancer cell lines(Springer Netherlands, 2016) Uzaras C.; Avcıbaşı U.; Demiroğlu H.; Medine E.İ.; Kılçar A.Y.; Müftüler F.Z.B.; Ünak P.The aim of this study is to determine the incorporations of PHT radiolabeled with 131I (131I-PHT) on U-87 MG, Daoy and A549 cancerous cell lines. For this, cold and radio-labeling studies were carried out. The radio-labeling yield of 131I-PHT was obtained about 95 %. Subsequently, cell culture studies were carried out and radio-labeling yields of 131I, 131I-PHT on U-87 MG, Daoy and A549 cancerous cells were investigated. Cell culture studies demonstrated that the incorporation values of 131I-PHT on the three cell lines decreased with increasing radioactivity. Consequently, 131I-PHT may be a good radiopharmaceutical for targeting radionuclide therapy of Central Nervous System Tumors. © 2015, Akadémiai Kiadó, Budapest, Hungary.Item Fuzzy Systems Tuned By Swarm Based Optimization Algorithms for Predicting Stream flow(Springer Netherlands, 2016) Turan M.E.River flow prediction is an important phenomenon in water resources for which different methods and perspective have been used. Using fuzzy system with black box perspective is one of them. Fuzzy systems have some parameters and properties that have to be determined. This is an optimization problem that can be solved by swarm optimization techniques among several techniques. Swarm optimization are developed by inspiring from the behavior of the animals living as swarm. The study presents two achievements fuzzy system that tuned by swarm optimization algorithms can be used for prediction of monthly mean streamflow and which swarm optimization algorithm is better than the others for tuning fuzzy systems. Three swarm optimization algorithms, hunter search, firefly, artificial bee colony are used in this study. These algorithms are compared with mean performance values and convergence speed. Monthly streamflow data of three stream gauging stations in Susurluk Basin are used for the case study. The results show, swarm optimization algorithms can be used for prediction of monthly mean streamflow and ABC algorithm has better performance values than other optimization algorithms. © 2016, Springer Science+Business Media Dordrecht.Item Patterns and drivers of phytodiversity in steppe grasslands of Central Podolia (Ukraine)(Springer Netherlands, 2016) Kuzemko A.A.; Steinbauer M.J.; Becker T.; Didukh Y.P.; Dolnik C.; Jeschke M.; Naqinezhad A.; Uğurlu E.; Vassilev K.; Dengler J.We asked: (i) Which environmental factors determine the level of α-diversity at several scales and β-diversity in steppic grasslands? (ii) How do the effects of environmental factors on α- and β-diversity vary between the different taxonomic groups (vascular plants, bryophytes, lichens)? We sampled nested-plot series ranging from 0.0001 to 100 m2 and additional 10-m2 plots, covering different vegetation types and management regimes in steppes and semi-natural dry grasslands of Central Podolia (Ukraine). We recorded all terricolous taxa and used topographic, soil, land-use and climatic variables as predictors. Richness-environment relationships at different scales and across taxonomic groups were assessed with multimodel inference. We also fitted power-law species-area relationships, using the exponent (z value) as a measure of β-diversity. In general, the richness values in the study region were intermediate compared to those known from similar grasslands throughout the Palaearctic, but for 1 cm2 we found seven species of vascular plants, a new world record. Heat index was the most important factor for vascular plants and bryophytes (negative relation), while lichen diversity depended mainly on stone and rock cover (positive). The explanatory power of climate-related variables increased with increasing grain size, while anthropogenic burning was the most important factor for richness patterns at the finest grain sizes (positive effect). The z values showed more variation at the finest grain sizes, but no significant differences in their mean between scales. The results highlight the importance of integrating scale into ecological analyses and nature conservation assessments in order to understand and manage biological diversity in steppe ecosystems. © 2016, Springer Science+Business Media Dordrecht.Item Multifunctional molecular imaging probes for estrogen receptors: 99mTc labeled diethylstilbestrol (DES) conjugated, cuinp quantum dot nanoparticles (DESCIP)(Springer Netherlands, 2017) Moharrami P.; Unak P.; Guldu O.K.; Medine E.I.; Gumuser G.; Bilgin E.S.; Aras O.A theranostic nanoparticle was synthesized based on diethylstilbestrol conjugated with phosphate, copper, and indium (DESCIP) and labelled with 99mTc which can be used for SPECT imaging of ER-enriched cancers. In vitro biological activity of 99mTc-DESCIP was examined in breast adenocarcinoma cells (MCF-7), prostatic carcinoma cells (PC-3), and pulmonary epithelial cells (A-549). In vivo lymph node imaging was performed in normal and receptor blocked female New Zealand rabbits. Results demonstrated that 99mTc-DESCIP and DESCIP has potential for imaging ER-enriched tumors such as breast and prostate tumors, and their metastases in the lung, as well as improving management for their therapies. © 2017, Akadémiai Kiadó, Budapest, Hungary.Item The effect of radiolabeled antibiotics on biofilm and microorganism within biofilm(Springer Netherlands, 2018) Avcıbaşı U.; Demiroğlu H.; Sakarya S.; Ünak P.; Tekin V.; Ateş B.The aim of this study was to investigate the 131I and 127I labeled linezolid and moxifloxacin effects of minimum inhibitory concentration, and minimum bactericidal concentration on mature biofilm and microorganism within the biofilm. Linezolid and moxifloxacin were labeled with 131I and 127I and chromatography studies were carried out with thin layer radiochromatograpy and high-pressure liquid radiochromatography techniques. Specific activities of radiolabeled LZD and MXF was found to be 53.3 ± 3.1 and 127.3 ± 1.1 MBq/µmol for [131I]LZD and 7.6 ± 0.02 and 55.6 ± 0.8 MBq/µmol for [131I]MXF, respectively. The minimum inhibitory concentration and Time-Kill of Linezolid and moxifloxacin alone and their 131I and 127I labeled forms were tested with a standard strain of meticillin-susceptible Staphylocıccus aureus. MIC values of LNZ and MXF were 2.96 nmol/mL (1 µg/ml) and 0.141 nmol/mL (0.062 µg/ml). Time Kills of MXF and LZD were found to be 0.06 and 1 μg, respectively. Antibiotics labeled with beta-emitting radioactive molecule may be a new theranostics strategy for biofilm infections. © 2018, Akadémiai Kiadó, Budapest, Hungary.Item One-step conjugation of glycylglycine with [18F]FDG and a pilot PET imaging study(Springer Netherlands, 2018) Şenk A.M.; İçhedef Ç.; Kılçar A.Y.; Uçar E.; Arı K.; Göksoy D.; Parlak Y.; Sayıt Bilgin B.E.; Teksöz S.This study describes a single step conjugation of Glycylglycine (GlyGly) which is a small peptide, with [18F]FDG via oxime formation. Amiooxy-functionalization of GlyGly (AO-GlyGly) was accomplished through the reaction of Boc-aminooxy succinimide ester. Conjugation reaction was performed at 100 °C for 30 min in a vial containing AO-GlyGly and [18F]FDG solution. The radiolabeled product ([18F]FDG-GlyGly) was obtained with 98.65 ± 0.35% yield without any purification step which makes this method more attractive for 18F radiolabeling. The present study is concluded with an in vivo pilot animal PET study to assess biodistribution and kinetics of chemoselectively [18F]FDG tagged GlyGly in vivo. © 2018, Akadémiai Kiadó, Budapest, Hungary.Item Dynamics of HIV/AIDS in Turkey from 1985 to 2016(Springer Netherlands, 2018) Sayan M.; Hınçal E.; Şanlıdağ T.; Kaymakamzade B.; Sa’ad F.T.; Baba I.A.In this paper, we formulated a mathematical model that studies the dynamics of HIV/AIDS in Turkey from 1985 to 2016. We find two equilibrium points, disease free equilibrium and endemic equilibrium. Global stability analysis of the equilibria was conducted using Lyapunov function which depends on the basic reproduction ratio R0. If R0 < 1, the disease free equilibrium point is globally asymptotically stable, and if R0 ≥ 1 the endemic equilibrium point is globally asymptotically stable. We computed and predicted the basic reproduction ratios across all the years. It was found out that there were flaws in the exact values of R0 which is related to the poor registration system of HIV/AIDS in Turkey. Hence, there is need for the government to improve the system in order to cover the actual cases of the disease. The increase of the basic reproduction ratio over the years also shows the need for the relevant authorities to adopt appropriate control measures in combating the disease. © 2017, Springer Science+Business Media B.V.Item Adsorption of thorium (IV) by amorphous silica; response surface modelling and optimization(Springer Netherlands, 2018) Kaynar U.H.; Şabikoğlu İ.The amorphous SiO2 (200–300 nm) was synthesized as an absorbent and thorium adsorption of SiO2 was investigated using experimental and RSM method. The SiO2 particles were made for the adsorption of thorium from aqueous solutions, and characterized by particle size measurement, XRD and SEM. The adsorption of thorium process was optimized with RSM method. The correlation between four variables was modeled and studied. Under optimum conditions, the adsorption capacity of SiO2 particles was found to be 134.4 mg/g, the correlation coefficient (R2) and the F value was obtained 0.96 and 1.98 × 10−6, respectively. In addition, the adsorption isotherms were examined. © 2018, Akadémiai Kiadó, Budapest, Hungary.Item Role of awareness in controlling HIV/AIDS: a mathematical model(Springer Netherlands, 2018) Kaymakamzade B.; Şanlıdağ T.; Hınçal E.; Sayan M.; Sa’ad F.T.; Baba I.A.This paper proposes and analyzes two epidemic models incorporating the effects of the awareness programs. One of the models is for HIV awareness and the other AIDS awareness. Awareness programs play a promising role in disseminating the information about outbreak of any HIV/AIDS in Turkey. This motivates people to take precautionary measures and guides the infected individuals to get the required treatment. The aim of this study is to investigate the impact of the awareness on the spread and control of HIV/AIDS in Turkey. The models are analyzed using stability theory of differential equations. The sensitivity of parameters has been discussed and it has been found that the awareness education programs have positive impact in reducing the infection prevalence of the infective population in Turkey. © 2017, Springer Science+Business Media B.V.Item Developments and assessments on barrier-free it in Turkey(Springer Netherlands, 2018) Kalaç M.Ö.; Telli Yamamoto G.The ratio of the population with disabilities in Turkey was approximately 12 percent as of 2002, and only a very little portion of them were found to have reached the higher education level. Furthermore, contribution of people with disabilities to employment is also important for their wellness and experiencing civil liberties. Barrier-free IT is among the most important tools in this respect. There is a legislation in Turkey for the practices in this field, and the special circumstances and technological services-related studies for accessibility are considered within the framework of a universal service. The shift towards an information society should offer an environment which involves all individuals of the society. Inter-institutional cooperation and more effective use of the resources are required to overcome the barriers. Furthermore, keeping a national database is also important for correct distribution and ensuring effectiveness of the resources. The problem of accessibility and availability in information technologies and services is waiting for a solution. Information technologies play a critical and distinctive role to solve these problems and create employment for people with impairment. This is a descriptive study on the developments and assessments regarding Barrier-Free IT in Turkey. © 2018, Springer Science+Business Media B.V., part of Springer Nature.Item Expression profiles of histone modification genes in gastric cancer progression(Springer Netherlands, 2018) Orenay-Boyacioglu S.; Kasap E.; Gerceker E.; Yuceyar H.; Demirci U.; Bilgic F.; Korkmaz M.Gastric cancer (GC) development can be attributed to several risk factors including atrophic gastritis (AG), intestinal metaplasia (IM), and the presence of Helicobacter pylori (HP). Also, histone modification is an epigenetic mechanism that plays a pivotal role in GC carcinogenesis. In this preliminary study, we aimed to describe the expression profiles of histone modification in the AG, IM, and GC patient groups. A total of 80 patients with AG (n = 27), IM (n = 25), and GC (n = 28) with an additional 20 control subjects were included in the study. Expression profiles of three histone phosphorylation genes (PAK1, NEK6, and AURKA) and five histone deacetylation genes (HDACs 1, 2, 3, 5, and 7) were examined based on the results of Real Time qPCR method. It was observed that AURKA and HDAC2 genes were significantly overexpressed in all groups compared to the control (P < 0.05). In GC patients, overexpression of HDAC2 gene was detected in the absence of metastasis, and overexpression of AURKA, HDAC2, and NEK6 genes was detected in the presence of metastasis. When cancer involvements were compared, significant overexpression of the HDAC2 gene was noted in overall and corpus involvements (P < 0.05). In addition, overexpression of AURKA, NEK6, HDAC1, and HDAC2 genes and underexpression of HDAC5 gene were detected in the antrum involvement (P < 0.05). In conclusion, decreased expression of HDAC5 in GC is reported for the first time in this study, while supporting the existing literature in AURKA, NEK6, HDAC1, and HDAC2 up regulations during GC development. © 2018, Springer Nature B.V.Item Chronic tinnitus and BDNF/GDNF CpG promoter methylations: a case–control study(Springer Netherlands, 2019) Orenay-Boyacioglu S.; Caliskan M.; Boyacioglu O.; Coskunoglu A.; Bozkurt G.; Cam F.S.Brain-derived neurotrophic factor (BDNF) and Glial-derived neurotrophic factor (GDNF) are neurotrophic factors that play key roles in the auditory pathway. While the relationship between serum levels and polymorphisms of BDNF/GDNF and chronic tinnitus is emphasized in the literature, there is no study showing the link between the promoter methylations of these genes and tinnitus. For this purpose, the relationship between chronic tinnitus and peripheral blood derived BDNF/GDNF promoter methylations was investigated to identify their role in the pathophysiology of tinnitus. In this case–control study, we examined the possible effects of BDNF/GDNF methylations in the blood samples of patients with tinnitus complaints for more than 3 months. Sixty tinnitus subjects between the ages of 18–55 and 50 healthy control subjects in the same age group who were free of any otorhinolaryngology and systemic disease were selected for examination. Methylation of total 12 CpG sites in BDNF and GDNF promoter regions were determined by the bisulfite-pyrosequencing method. Statistically significant differences were detected between BDNF CpG6 and GDNF CpG3-5-6 methylation ratios in the comparison of control group and the chronic tinnitus patients (P = 0.002, 0.0005, 0.00003, and 0.0029, respectively). To our knowledge, this is the first study in the literature investigating the relationship between chronic tinnitus and peripheral blood derived BDNF/GDNF promoter methylations. It is believed that the current results might be supported by investigating the relationships between BDNF/GDNF methylations and genotypes in future research using higher sample sizes. © 2019, Springer Nature B.V.Item Transition from start-up to scale-up for fucoxanthin production in flat plate photobioreactor(Springer Netherlands, 2019) Aslanbay Guler B.; Deniz I.; Demirel Z.; Oncel S.S.; Imamoglu E.Fucoxanthin is one of the most important carotenoids and is found in diatoms such as Phaeodactylum tricornutum. The aim of this study was to evaluate the use of both the constant volumetric power consumption rate as scale-up strategy and the constant light energy per unit volume for transition from 1000-mL bottle to 2-L and 7-L flat plate photobioreactors for fucoxanthin production in P. tricornutum, considering whether an increase in the fucoxanthin yield could be achieved. The cell concentration and fucoxanthin content were enhanced with increasing the cultivation volume. It was found that the fucoxanthin yield increased 2.3 times in 2-L photobioreactor and 2.6 times in 7-L photobioreactor in comparison to the value of 1.05 mg g−1 dry weight in the cultivation bottle. Consequently, fucoxanthin production was successfully step-wise scaled-up from 1000-mL bottle to 7-L photobioreactor using both constant volumetric power consumption rate and the constant light energy per unit volume under laboratory conditions. © 2019, Springer Nature B.V.Item A new colorimetric method for rapid detection of ethambutol and streptomycin resistance in Mycobacterium tuberculosis: crystal violet decolorization assay (CVDA)(Springer Netherlands, 2019) Coban A.Y.; Akbal A.U.; Ceyhan I.; Uzun M.; Sertel Selale D.; Aslan G.; Delialioglu N.; Ozyurt M.; Bektore B.; Bicmen C.; Aslanturk A.; Ucarman N.; Albay A.; Sig A.K.; Ozkutuk N.; Surucuoglu S.Streptomycin (STR) and ethambutol (EMB) are important drugs used for the treatment of tuberculosis. There is a need for fast, reliable and inexpensive methods for detecting resistance to these drugs. The aim of this study was to evaluate the performance of the crystal violet decolorization assay (CVDA) for the detection of STR and EMB resistance that is important drugs in tuberculosis treatment. In this study, drug susceptibility testing was performed on 140 Mycobacterium tuberculosis isolates provided from nine centers. Three tubes were used for each isolate. One of the tubes had a concentration of 2 mg/L STR and the other 5 mg/L EMB. The third was drug-free control tube. Sensitivity, specificity, positive predictive value (PPD), negative predictive value (NPD) and agreement for STR were found to be 81.8%, 94.6%, 87.8%, 91.5% and 90.57%, respectively. For EMB, sensitivity, specificity, PPD, NPD, and agreement were found to be 76%, 98.23%, 90.47%, 94.87% and 94.2%, respectively. The results were obtained in 11.3 ± 2.7 days (8–21 days). CVDA is rapid, reliable, inexpensive, and easy to perform for rapid detection of STR and EMB resistance, and it could be adapted for drug susceptibility testing. © 2018, Springer Nature Switzerland AG.