Bulunan: 34 Adet 0.001 sn
Koleksiyon [4]
Tam Metin [1]
Yazar [20]
Yayın Türü [2]
Konu Başlıkları [20]
Yayın Tarihi [16]
Dergi Adı [7]
Dil [2]
Yazar Departmanı [1]
Secondary metabolites from Sambucus ebulus

Atay, İrem | Kırmızıbekmez, Hasan | Yeşilada, Erdem | Gören, Ahmet Ceyhan

Other | 2015 | Turkish Journal of Chemistry39 ( 1 ) , pp.34 - 41

Abstract: A new nonglycosidic iridoid, sambulin B (1), was isolated from the methanol extract of Sambucus ebulus L. leaves along with a recently reported new nonglycosidic iridoid, 10-O-acetylpatrinoside aglycone (sambulin A) (2); 2 flavonoids, isorhamnetin-3-O-eta-D-glucopyranoside (3) and isorhamnetin-3-O-rutinoside (4); and a mixture of 2 flavonoids (5), quercetin-3-O-eta-D-glucopyranoside and quercetin-3-O-eta-D-galactopyranoside. Their structures were elucidated by 1-D and 2-D nuclear magnetic resonance spectroscopy (NMR) and mass spectrometry (MS) experiments.

Neural Network Based Classification of Melanocytic Lesions in Dermoscopy: Role of Input Vector Encoding

Ertaş, Gökhan

Article | 2018 | Electrica18 ( 2 ) , pp.242 - 248

Melanocytic lesions are the main cause of death from skin cancer, and early diagnosis is the key to decreasing the mortality rate. This studyassesses the role of input-vector encoding in neural network-based classification of melanocytic lesions in dermoscopy. Twelve dermoscopicmeasures from 200 melanocytic lesions are encoded by compact encoding, ACD encoding, 1-of-N encoding, normalized encoding, and rawencoding, resulting in five different input-vector sets. Feed-forward neural networks with one hidden layer and one output layer are designedwith several neurons in the hidden layer, ranging from two to twenty-two for each type of . . .input-vector set, to classify a melanocytic lesion intocommon nevus, atypical nevus, and melanoma. Accordingly, 105 networks are designed and trained using supervised learning and then testedby performing a 10-fold cross validation. All the neural networks achieve high sensitivities, specificities, and accuracies in classification. However,the network with seven neurons in the hidden layer and raw encoded dermoscopic measures as the input vector realizes the highest sensitivity(97.0%), specificity (98.1%), and accuracy (98.0%). The practical use of the network can facilitate lesion classification by retaining the neededexpertise and minimizing diagnostic variability among dermatologists Daha fazlası Daha az

Design, synthesis, and biological evaluation of indole-based 1,4-disubstituted piperazines as cytotoxic agents

Köksal, Meriç Akkoc | Yarım, Mine Yüksel | Durmaz, İrem | Çetin, Rengül Atalay

Article | 2012 | Turkish Journal of Chemistry36 ( 4 ) , pp.503 - 514

A series of 3-[(4-substitutedpiperazin-1-yl)methyl]-1H -indole derivatives were synthesized, and their structures were confirmed by spectral analysis. All the compounds were tested for their cytotoxic activity in vitro against 3 human tumor cell lines: human liver (HUH7), breast (MCF7), and colon (HCT116). Among the designed derivatives, most of the compounds showed significant cytotoxicity against liver and colon cancer cell lines with lower IC50 concentrations than the standard drug 5-fluorouracil. Compound 3s, with 3,4-dichlorophenyl substituent on the piperazine ring, was the most active in suppressing the growth of all screened . . . cancer cells Daha fazlası Daha az


Utku, Feride Sermin | Basaran, Kubra | Sunar, Yagmur | Celebıoglu, Hulya | Kapıcı, Ibrahim

Article | 2017 | Istanbul University Journal of Electrical and Electronics Engineering17 ( 2 ) , pp.3439 - 3443

Mineralized natural protein based novel bone replacement materials are investigated for tissue engineering. Mineralized silk fibroin composite foams and films display excellent biocompatibility. In this study, the biomimetic and electrochemical mineralization of orderly oriented silk fibroin scaffolds was studied. Commercially obtained pure silk woven fabric was boiled in 0.02 M Na2CO3 for 20 min. Calcium phosphate was deposited at 37°C for twenty minutes in seven sequential immersion steps, using 250 mM CaCl2 2H2O and 120 mM K2HPO4, containing 0.15 M NaCl and 50mM TRIS-HCl, pH 7.4, followed by electrochemical treatment in modif . . .ied SBF solution at 40°C at a current density of -25mA/cm2 for 60 min. The amount of biomimetically deposited Ca-P increased with the number of immersion steps. SEM images and XRD analysis of the Ca-P deposit indicated the initial formation of brushite with its monoclinic crystal structure and characteristic peak at 11.76 2?, and electrochemical conversion of brushite to hydroxyapatite on silk after electrochemical cathodization as confirmed by XRD and SEM analysis. Thus, a silk-fibroin-hydroxyapatite composite material prepared as a xenograft consisting of biocompatible components, and easily prepared as an economical bone segment replacement material with highly oriented fibers Daha fazlası Daha az

A Molecularly Imprinted Polymer Based Biosensor for Electrochemical Impedance Spectroscopic Analysis

Utku, Feride Şermin | Özdemir, Ozan Enver | Bakay, Melahat Sevgül

Article | 2018 | Electrica18 ( 1 ) , pp.39 - 44

A molecularly imprinted polymer (MIP)-based impedimetric biosensor was developed for the electrochemical analysis of low-weight biological molecules. Synthetic polymeric matrices with specific and selective recognition sites, which are complementary to the shapes and sizes of the functional groups of analytes, can be prepared using the molecular imprinting method. In this study, a small molecule, tris(hydroxymethyl)aminomethane (TRIS), was used to coat a graphite pencil tip with a TRIS-containing polyacrylamide gel to fabricate a working electrode. The electrode modification and performance were evaluated using cyclic voltammetry an . . .d electrochemical impedance spectroscopy. The electrochemical properties of the modified electrodes were observed using an electrochemical cell comprising a Ag/AgCl reference electrode, a Pt wire as the counter electrode, and a pencil graphite tip as the working electrode using a redox-phosphate buffer solution with different concentrations of TRIS and Ethylenediaminetetraacetic acid (EDTA). The I–V and impedance performance of the chemically modified graphite pencil-tip electrodes exhibited decreased conductance and increased impedance correlating with the increase in TRIS concentration. Thus, MIP-based small-molecule biosensor prototypes can be promising economical replacements over other expensive sensors Daha fazlası Daha az

Square wave voltammetric determination of valproic acid in pharmaceuticalPreparations

Acar, Ebru Türköz | Onar, Atiye Nur

Article | 2016 | Turkish Journal of Chemistry40 ( 1 ) , pp.106 - 116

The electrochemical behavior of valproic acid (VAL) was investigated using square wave voltammetry, cyclicvoltammetry, and sampled direct current polarography and a new square wave voltammetric method was developed fordetermination of VAL in pharmaceutical preparations. VAL showed two reduction peaks at about {0.2 V and {0.8 V vs.Ag/AgCl 3 M KCl with a hanging mercury drop electrode in 0.05 M pH 3.3 Britton{Robinson (BR) buffer. These peakswere named peak I and peak II, respectively. The types of limiting current of both peaks were determined as diffusioncontrolled based on cyclic voltammetry studies. A linear calibration graph was . . .obtained in the range 1.46104{1.0103M. The limit of detection (LOD) and limit of quanti cation (LOQ) were 1.09104M (21.05g/mL) and1.10104M (144.20g/mL), respectively. Recovery studies for the accuracy of the method were performed byadding known amounts of VAL and it was found to be 109.674.85%. The proposed method was successfully appliedto pharmaceutical products on the market Daha fazlası Daha az

Dynamics, stability, and actuation methods for powered compass gait walkers

Şafak, Koray Kadir

Article | 2014 | Turkish Journal of Electrical Engineering and Computer Sciences22 ( 6 ) , pp.1611 - 1624

In this paper, methods to achieve actively powered walking on level ground using a simple 2-dimensional walking model (compass-gait walker) are explored. The walker consists of 2 massless legs connected at the hip joint, a point mass at the hip, and an infinitesimal point mass at the feet. The walker is actuated either by applying equal joint torques at the hip and ankle, by an impulse applied at the toe off, immediately before the heel strike, or by the combination of both. It is shown that actuating the walker by equal joint torques at the hip and ankle on level ground is equivalent to the dynamics of the passive walker on a downh . . .ill slope. The gait cycle for the simplified walker model is determined analytically for a given initial stance angle. Stability of the gait cycle by an analytical approximation to the Jacobian of the walking map is calculated. The results indicate that the short-period cycle always has an unstable eigenvalue, whereas stability of the long-period cycle depends on selection of the initial stance angle. The effect of the torso mass by adding a third link attached at the hip joint is investigated. The torso link is kept in the vertical position by controlling the torque applied to it. The proportional-derivative control law is utilized to regulate the angular position error of the torso link. Using linearized dynamics for this walker, active control is applied to the ankle, which reduces the dynamics of the walker to the passive walker without the torso. The proposed walker is capable of producing stable walking while keeping the torso in an upright positio Daha fazlası Daha az

Weak penetration and radiation through apertures in conducting bodies of revolution

Yeğin, Korkut

Article | 2009 | Turkish Journal of Electrical Engineering and Computer Sciences17 ( 3 ) , pp.231 - 239

The simplest way to solve for penetration through small apertures in conducting surfaces is to treat the body as a scatterer and determine the interior field as the sum of the incident field and the scattered field contributed by the current induced on the surface of the body. However, it is well known that, if the aperture is very small or if the penetrated field is very weak this method yields very inaccurate results, which, in turn, prohibits proper design of electronic systems, especially for electromagnetic compatibility and interference. Previously, alternative integral equations formulations were proposed to remedy this probl . . .em and applied to two-dimensional conducting cylinders with slots [1–2]. Application of these alternative techniques to threedimensional conducting bodies of revolution (BOR) is studied in this work. In addition, the reciprocity principle is used to recast a weak penetration problem into a weak radiation problem, and it is shown that the alternative formulations useful for weak penetration are also useful for weak radiation. The important features and relative accuracies of each formulation together with numerical results are detailed for mock missile-shape structures Daha fazlası Daha az

Molecular modeling and antimycobacterial studies of Mannich bases: 5-hydroxy-2-methyl-4H-pyran-4-ones

Berk, Barkın | Us, Demet | Öktem, Sinem | Kocagöz, Z. Tanıl | Çağlayan, Berrak | Kurnaz, Işıl Aksan | Erol, Dilek Demir

Article | 2011 | Turkish Journal of Chemistry35 ( 2 ) , pp.317 - 330

The World Health Organization lists tuberculosis among the top 3 leading causes of death from a single infectious agent, and reported cases of multidrug-resistant tuberculosis (MDR-TB) are on the rise. In an attempt to improve MDR-TB drug-directed therapy, we synthesized 11 4-substituted piperazine derivatives of 3-hydroxy-6-methyl-4H -pyran-4-one pharmacophore by reacting 5-hydroxy-2-methyl- 4H-pyran-4-one with suitable piperazine derivatives under Mannich reaction conditions. Inhibitory effects of the 11 compounds on Escherichia coli DNA gyrase were evaluated via DNA gyrase supercoiling assay. The minimum inhibitory concentrations . . . (MIC) of the 11 compounds and 41 compounds from our previous studies against Mycobacterium tuberculosis H37RV were assessed, in vitro, by a broth dilution method. To determine the interaction pattern between active site amino acids and all 52 compounds, homology modeling for the construction of M. tuberculosis DNA gyrase B subunit was performed, followed by a docking study. The data presented here could prove useful in future studies on interaction field analysis and high throughput virtual screening of the derivatives of the 3-hydroxy-6-methyl-4H -pyran-4-one pharmacophore toward the development of more clinically applicable compounds Daha fazlası Daha az

Mannich base derivatives of 3-hydroxy-6-methyl-4H-pyran-4-one with antimicrobial activity

Us, Demet | Berk, Barkın | Gürdal, Ece | Aytekın, Nihan | Kocagöz, Tanıl | Layan, Berrak Çağ | Erol, Dilek Demir

Article | 2010 | Turkish Journal of Chemistry34 ( 3 ) , pp.447 - 456

A series of 3-hydroxy-6-methyl-2-[(substitutedpiperidine-1-yl)methyl]-4H -pyran-4-one structured compounds were synthesized by reacting 5-hydroxy-2-methyl-4H -pyran-4-one with suitable piperidine derivatives using Mannich reaction conditions. Antibacterial activities of the compounds for E. coli ATCC 25922, S. paratyphi ATCC BAA-1250, S. flexneri ATCC 12022, E. gergoviae ATCC 33426, and M. smegmatis ATCC 14468 were assessed in vitro by the broth dilution method for determination of minimum inhibitory concentration (MIC). In addition, their inhibitory effects over DNA gyrase enzyme were evaluated using a DNA gyrase supercoiling assay . . .. All the synthesized compounds showed a MIC value of either 8 or 16 μg/mL for M. smegmatis, whereas minimum to moderate activity was achieved for the others. Those tested in the supercoiling assay had at best a very mild inhibition of the enzyme. This series deserves further attention for testing over Mycobacterium species and topoisomerase II inhibition to develop new lead drugs to treat non-tuberculous mycobacterial infections Daha fazlası Daha az

4H-Pyran-4-one derivatives:; leading molecule for preparation of compounds with antimycobacterial potential

Us, Demet | Gürdal, Ece | Berk, Barkın | Öktem, Sinem | Kocagöz, Tanıl | Çağlayan, Berrak | Erol, Dilek Demir

Article | 2009 | Turkish Journal of Chemistry33 ( 6 ) , pp.803 - 812

A series of 3-hydroxy-6-methyl-2-((4-substitutedpiperazin-1-yl)methyl)-4H-pyran-4-one structured compounds were synthesized by reacting 5-hydroxy-2-methyl-4H-pyran-4-one with suitable piperazine derivatives using Mannich reaction conditions. Antibacterial activities of the compounds for E. coli, S. paratyphi, S. flexneri, E. gergoviae, and M. smegmatis were assessed in vitro by using broth dilution for determination of the minimum inhibitory concentration (MIC). In addition, their inhibitory effects over DNA gyrase enzyme were evaluated using a DNA gyrase supercoiling assay. Among the synthesized compounds; compound 7 showed a 4 &am . . .p;#956;g/mL MIC value for M. smegmatis, whereas the other compounds demonstrated moderate to high activity. Those tested in the supercoiling assay had at best a very mild inhibition of the enzyme. This series deserves further attention for testing over Mycobacterium species and topoisomerase II inhibition to develop new lead drugs Daha fazlası Daha az

Design of a Respiration Pattern Detecting Device based on Thoracic Motion Tracking with Complementary Filtering

Ertaş, Gökhan | Gültekin, Nida

Article | 2018 | Süleyman Demirel Üniversitesi Fen Bilimleri Enstitüsü Dergisi22 ( 1 ) , pp.32 - 37

The respiration pattern represents the volume of air in the lungs as afunction of time during human respiration process. Abnormal changes in thispattern can be signs of several diseases or conditions. There exit severalrespiration pattern detection methods. Among them, an easy technique relies onsensing the movements of thoracic and (or) abdominal regions. In this study, adevice based on thoracic motion tracking with complementary filtering has beendeveloped to detect the respiration pattern. The device is equipped with a motionsensor placed in a flexible belt housing a three-axis accelerometer and a three-axisgyroscope and a UART-t . . .o-USB converter providing computer connectivity. Thedevice is operated by a microcontroller that controls the operation of the motionsensor, applies complementary filtering to the motion data acquired and transfersthe results to a personal computer. The device is powered from the computer it isconnected to. Experiments with using the device during continues inhaling andexhaling, deep inhaling followed by breath-hold and deep exhaling followed bybreath-hold respiration activities in standing, lying and seated postures show thatthoracic motion tracking with complementary filtering may provide quite wellrespiration pattern detections. Solunum motifi, insan solunum işlemi sırasında zamanın bir fonksiyonuolarak akciğerlerdeki hava hacmini temsil eder. Bu desendeki anormaldeğişiklikler birtakım hastalıkların veya durumların belirtileri olabilir. Solunummotifinin tespitinde birçok yöntem bulunmaktadır. Bunlar arasında kolay birteknik göğüs ve (veya) karın bölgelerinin hareketlerinin algılanmasınadayanmaktadır. Bu çalışmada, tamamlayıcı filtreleme ile göğüs hareket izlemeyedayalı bir solunum deseni tespit cihazı geliştirilmiş bulunmaktadır. Cihaz esnek birkemer içine yerleştirilmiş üç eksenli bir ivmeölçer ve üç eksenli bir jiroskopbarındıran bir hareket algılayıcısı ve bilgisayar bağlantısı sağlayan bir UART-USBdönüştürücüsü ile donatılmıştır. Cihaz hareket algılayıcısının çalışmasını kontroleden, elde edilen hareket verilerine tamamlayıcı filtreleme uygulayan ve sonuçlarıkişisel bir bilgisayara aktaran bir mikrodenetleyici tarafından işletilmektedir.Cihaz bağlı olduğu bilgisayardan beslenmektedir. Ayakta durma, yatma ve oturmapozisyonlarında; sürekli nefes alma ve verme, derin nefes almayı takiben nefestutma ve derin nefes vermeyi takiben nefes tutma solunum aktiviteleri süresincecihaz kullanarak gerçekleştirilen deneyler tamamlayıcı filtreleme ile göğüshareketi izlemenin oldukça iyi solunum deseni tespitlerine imkân tanıyabildiğinigöstermektedir Daha fazlası Daha az

6698 sayılı Kişisel Verilerin Korunması Kanunu kapsamında yükümlülüklerimiz ve çerez politikamız hakkında bilgi sahibi olmak için alttaki bağlantıyı kullanabilirsiniz.

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