Browsing by Publisher Scope "International"

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1,3-bis(gamma-aminopropyl)tetramethyldisiloxane modified epoxy resins: curing and characterization
(Elsevier, 1998) Department of Chemistry; Department of Chemistry; Yılgör, Emel; Yılgör, İskender; Researcher; Faculty Member; Department of Chemistry; College of Sciences; College of Sciences; 40527; 24181
Incorporation of siloxane oligomers with reactive organofunctional terminal groups, such as amine, epoxy and carboxy, into the structure of epoxy networks, provides improvements in the fracture toughness, water absorption and surface properties of the resultant systems. 1,3-bis(gamma-aminopropyl) tetramethyldisiloxane (DSX) was used as a model curing agent and modifier in bis(4-aminocyclohexyl)methane (PACM-20) cured diglycidyl ether of bisphenol-A (DGEBA) based epoxy resins. Curing reactions followed by differential scanning calorimetry indicated faster reaction rates between DSX and DGEBA as compared with PACM-20 and DGEBA. Mechanical characterization of the modified products showed improvements in tensile and impact strengths as expected. Glass transition temperatures of these materials showed a decrease with an increase in DSX content.
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1.07 - Rubberlike elasticity
(Elsevier, 2012) Mark, J.E.; Department of Chemical and Biological Engineering; Erman, Burak; Faculty Member; Department of Chemical and Biological Engineering; College of Engineering; 179997
Molecular structure, molecular and phenomenological theories, and computer simulations of amorphous rubberlike polymeric networks of rubber elasticity are discussed. Behavior of responsive gels, multimodal, liquid-crystalline, and reinforced elastomers in the state of thermodynamic equilibrium are outlined. Characterization of structure and properties based on stress–strain experiments, optical and spectroscopic techniques, scanning tunneling microscopy, atomic force microscopy, nuclear magnetic resonance, small-angle and Brillouin scattering, and pulse wave propagation are outlined. © 2012 Elsevier B.V. All rights reserved.
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10-NJ multipass-cavity femtosecond CR3+: LiCAF laser pumped by low-power single-mode diodes
(Optical Society of America, 2009) Kärtner, Franz X.; Fujimoto, James G.; Demirbaş, Ümit; Department of Physics; Sennaroğlu, Alphan; Faculty Member; Department of Physics; College of Sciences; 23851
We report on the generation of 9.9-nJ, 95-fs pulses at a repetition rate of 9.58 MHz from a multipass-cavity Cr3+:LiCAF laser pumped by single-mode diodes with a total absorbed pump power of only 540 mW.
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1200 nm pumped Tm3+:Lu2O3 ceramic lasers
(Optical Soc Amer, 2018) Özharar, Sarper; N/A; Department of Physics; Toker, Işınsu Baylam; Sennaroğlu, Alphan; PhD Student; Faculty Member; Department of Physics; N/A; College of Sciences; N/A; 23851
We report on an experimental demonstration of a 1200-nm pumped Tm3+:Lu2O3 ceramic laser. By using a gain-switched, tunable Cr4+:forsterite laser, the excitation spectrum was measured, with optimum pumping bands centered near 1198 nm, 1204 nm, and 1211 nm. The highest slope efficiency of 21.5% was obtained at the pump wavelength of 1204 nm. Comparative energy efficiency measurements performed near 1200-nm and 800-nm pumping further showed that nearly 40% improvement was obtained in slope efficiency measured with respect to the incident pump energy for 1200-nm pumping. A transition was further observed from single-wavelength operation at 2066 nm to dual-wavelength operation near 2066 nm and 1967 nm for absorbed pump energies above 50 mu J. In this regime, two consecutive output pulses were observed in the time domain. The shortest temporal duration of the first pulse was 1.1 mu s at the incident pulse energy of 105 mu J. The duration and build-up time of the second pulse remained around 5.9 mu s and 18.5 mu s. We believe that the improved energy efficiency demonstrated for the 1.5% Tm3+:Lu2O3 ceramic with 1200-nm pumping can be used as an alternative scheme for the excitation of Tm3+:Lu2O3 ceramic lasers.
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16.4: the optics of an autostereoscopic multiview display
(SID, 2010) Baghsiahi, Hadi; Selviah, David R.; Willman, Eero; Fernández, Anibal; Day, Sally E.; Surman, Phil A.; N/A; Department of Electrical and Electronics Engineering; Department of Electrical and Electronics Engineering; Erden, Erdem; Chellappan, Kishore Velichappattu; Ürey, Hakan; Master Student; Researcher; Faculty Member; Department of Electrical and Electronics Engineering; Graduate School of Sciences and Engineering; College of Engineering; College of Engineering; N/A; N/A; 8579
An autostereoscopic head-tracked back projection display that uses an RGB laser illumination source and a fast light engine is described. Images are horizontally scanned columns controlled by a spatial light modulator that directs two or more images in the directions of the apposite viewers 'eyes.
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18F-FDG PET/CT imaging in a patient with a rare diagnosis of sarcomatoid malignant peritoneal mesothelioina
(Lippincott Williams & Wilkins, 2013) Tokmak, Handan; Demirkol, Onur M.; Kaban, Kerim; N/A; Mandel, Nil Molinas; Dilege, Şükrü; Faculty Member; Faculty Member; School of Medicine; School of Medicine; 194197; 122573
Malignant peritoneal mesothelioma is an uncommon but deadly disease arising from serosal surfaces of the peritoneum. Asbestos exposure is the most recognized risk factor. We report a case of diffuse, sarcomatoid malignant peritoneal mesothelioma who presented to the hospital with abdominal pain. The patient had an abdominal MRI scan as initial scanning which demonstrated nonspecific findings suspected of peritoneal carcinomatosis. The patient was admitted to our department for the metabolic characterization of the lesions with F-18-FDG PET/CT imaging and the diagnosis of the primary malignancy. F-18-FDG PET/CT imaging revealed diffusely increased metabolic activity throughout the peritoneum and the histopathological features were compatible with sarcomatoid malignant peritoneal mesothelioma.
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18F-FDG PET/CT mean suv and metabolic tumor volume for mean survival time in non-small cell lung cancer
(Lippincott Williams and Wilkins, 2015) Kurtipek, Ercan; Çaycı, Mustafa; Düzgün, Nuri; Esme, Hıdır; Terzi, Yüksel; Bakdık, Süleyman; Ünlü, Yaşar; Burnik, Cengiz; Bekçi, Taha Tahir; N/A; Aygün, Murat Serhat; Teaching Faculty; School of Medicine; Koç University Hospital; 291692
Objective: The study was designed to determine the relationship between survival time of standardized uptake value (SUVmax and SUVmean) and metabolic tumor volume (MTV) in patients with non-small cell lung cancer (NSCLC), and examine the impact of demographic, clinical, and radiological data of these patients on survival. Materials and Methods: We performed a retrospective analysis of the records of 79 patients with NSCLC who presented to our hospital between May 2010 and March 2013, received a final diagnosis, and underwent 18F-FDG PET/CT for staging. Clinical, radiological, and 18F-FDG PET/CT parameters with an impact on prognosis such as the SUVmax of the primary tumor as calculated by the volumetric region of interest in the 18F-FDG PET/CT scans during initial diagnosis, mean SUV of the tumor, and MTV obtained with a threshold of SUVmax greater than 2.5 were recorded and statistically analyzed. A statistical analysis was carried out based on the clinical, radiological, and PET/CT findings of the patients who were divided into 2 groups: survivors and nonsurvivors. Results: Seventy patients (88.6%) were men, and 9 (11.4%) were women. The mean age was 63.65 ± 11.51 years in the nonsurvivor group (n = 40) versus 62.74 ± 10.60 years in the survivor group (n = 39) (Table 1). The mean survival time from diagnosis was 7.9 ± 6.52 months in the nonsurvivor group versus 14.09 ± 7.41 months in the survivor group. The mean survival time was 12.9 ± 7.9 months for those aged 60 or younger, whereas it was 9.9 ± 7.2 years for those aged 60 or older. According to the Cox regression analysis, higher MTV [relative risk (RR), 1.006; P = 0.03] and mean SUVmax (mSUV) (RR, 1.302; P = 0.03) had a significant impact on shortening of the mean survival time. However, no statistical significance was reached for SUVmax measurements (RR, 0.970; P = 0.39). Furthermore, there was a significant relationship between increased tumor size (andlt;2 cm, 2-4 cm, and ≥4 cm) and shortened mean survival time (P = 0.03). Conclusion: The present study showed that MTV and mSUV of FDG PET/CT scans of the tumor, but not SUVmax, had a significant impact on survival time of patients with NSCLC. Based on this result, we believe that we might have more accurate information about the survival time of our patients if we also evaluate mSUV and MTV in combination with mSUV, which is frequently used for diagnosis and monitoring of patients with NSCLC during our daily practice. © 2015 Wolters Kluwer Health, Inc. All rights reserved.
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18F-FDG PET/CT texture analysis of anthracotic lymph nodes detected with EBUS and comparison with cytological findings
(P.Ziti and Co, 2022) N/A; N/A; N/A; N/A; N/A; N/A; N/A; N/A; Çağlayan, Benan Niku; Fırat, Pınar Arıkan; Seymen, Hülya; Bulutay, Pınar; Falay, Fikri Okan; Demirtaş, Elif; Demirkol, Mehmet Onur; Meriçöz, Çisel Aydın; Faculty Member; Faculty Member; Teaching Faculty; Teaching Faculty; Teaching Faculty; Master Student; Faculty Member; Teaching Faculty; School of Medicine; School of Medicine; School of Medicine; School of Medicine; School of Medicine; Graduate School of Health Sciences; School of Medicine; School of Medicine; 230719; 207545; 350778; 133565; 246484; N/A; 196946; 162418
Objective: Lymph node metastasis is the most important factor both in the selection of treatment since many alternatives have been created in recent years, and in the evaluation of prognosis in lung cancer. The most unpredictable cause of lymph node false positivity in fluorine-18-fluorodeoxyglucose (18F-FDG) positron emission tomography/computed tomography (PET/CT) is anthracosis. The aim of this study is to compare 18F-FDG PET/CT texture information of anthracotic (ALN) and metastatic (MLN) lymph nodes, after re-evaluation of the cytological samples obtained from anthracotic lymph nodes by EBUS-TBNA. Subjects and Methods: Ninety nine patients, 78 of whom had primary lung cancer were included in the study. Two hundred and three lymph nodes from 99 patients sampled by EBUS-TBNA and diagnosed cytologically as ALN or MLN were evaluated retrospectively. All ALN were classified as grades 1, 2 and 3 cytologically. Volume of interest (VOI) of 203 lymph nodes was re-drawn and maximum standardized uptake value (SUVmax), metabolic tumor volume (MTV) and total lesion glycolysis (TLG) values were recorded. Results: There was a statistically significant difference in MTV and TLG values in MLN and all ALN grades. However, only grade 1-2 ALNs could be differentiated from MLNs with SUVmax, and no statistically significant difference was found in grade 3 ALN and MLN. Metabolic tumor volume and TLG values over 4.10cm3 and 26.57 showed 60% and 59% sensitivity and 83% and 94 specificity respectively for the identification of MLN. Conclusion: The contribution of MTV and TLG values of 18F-FDG PET/CT to the differential diagnosis of ALN is much more valuable than SUVmax values, especially for grade 3 anthracosis. It was thought that cytological reporting of only grade 3 ALN could make a better contribution to the 18F-FDG PET/CT evaluation analysis.
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2018-1-TR01-KA103-050583
Office of International Programs (OIP) ; Office of International Programs (OIP)
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2019 Erasmus KA107
Office of International Programs (OIP) ; Office of International Programs (OIP)
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2019 KA103 ERASMUS + KEY ACTION1 STUDENT AND STAFF EXCHANGE
Office of International Programs (OIP) ; Office of International Programs (OIP)
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2020 Erasmus KA107
Office of International Programs (OIP) ; Office of International Programs (OIP)
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2021-1-TR01-KA131-HED-000005368
Office of International Programs (OIP) ; Office of International Programs (OIP)
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2022-1-TR01-KA171-HED-000076256
Office of International Programs (OIP) ; Office of International Programs (OIP)
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2023-1-TR01-KA131-HED-000113765
Office of International Programs (OIP) ; Office of International Programs (OIP)
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21 fs Cr:LiSAF laser mode locked with a single-walled carbon nanotube saturable absorber
(Optical Soc Amer, 2019) Bae, Ji Eun; Rotermund, Fabian; Demirbaş, Ümit; N/A; N/A; N/A; Department of Physics; Tanısalı, Gökhan; Toker, Işınsu Baylam; Taşçı, Mısra; Sennaroğlu, Alphan; PhD Student; PhD Student; Undergraduate Student; Faculty Member; Department of Physics; Koç University Surface Science and Technology Center (KUYTAM) / Koç Üniversitesi Yüzey Teknolojileri Araştırmaları Merkezi (KUYTAM); Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; School of Medicine; College of Sciences; N/A; N/A; N/A; 23851
We report the shortest femtosecond pulses directly generated from a solid-state laser that is mode locked by using a single-walled carbon nanotube saturable absorber (SWCNT-SA). In the experiments, we used a 660 nm diode-pumped, low-threshold extended-cavity Cr:LiSAF laser operating around 850 nm with a repetition rate of 47.9 MHz. The SWCNT-SA mode-locked Cr:LiSAF laser produced 21 fs pulses with a time-bandwidth product of 0.56 by using only 210 mW of pump power. Pump-probe spectroscopy measurements showed that the SWCNT-SA exhibited saturable absorption with slow and fast decay times of 2.7 ps and 0.4 ps. The single-pass modulation depth and saturation fluence of the SWCNT-SA were further determined as 0.3% and 45 mu J/cm(2) at the pump wavelength of 850 nm.
Open Access
25-hydroxyvitamin D levels are low but not associated with disease activity in chronic spontaneous urticaria and depression
(AEPress, 2020) Vurgun, Eren; Güntaş, Gürkan; Kocatürk Göncü, Özgür Emek; Memet, Bachar; Doctor; School of Medicine; Koç University Hospital; 217219; N/A
Aim: to evaluate vitamin D levels in patients with chronic spontaneous urticaria (CSU), depression and both of them, thus to fi nd out whether vitamin D may be a common causative factor of CSU and depression. Methods: thirty patients with CSU, 30 patients with depression, 30 patients with both CSU and depression and 30 healthy volunteers as control group were involved in the study. Serum 25-hydroxyvitamin D (25(OH) D) levels of these groups were measured and compared. Correlations between 25(OH)D levels and the activity of CSU and depression were analyzed. Results: healthy controls' 25(OH)D levels (17.2±8.8 ng/mL) were higher than patients with CSU (9.1±5.1 ng/mL), depression (8.9±6.1 ng/mL) and CSU with depression (7.7±4.7 ng/mL) (p<0.001, p<0.001 and p<0.001, respectively). There were no differences in 25(OH)D levels between CSU patients with and without depression, between depression patients and CSU patients with and without depression (p=0.43, p=0.82 and p=0.92, respectively). There were no correlations between 25(OH)D levels and the activity of CSU or depression (p=0.99 and p=0.76, respectively). Conclusion: Lower 25(OH)D levels in CSU and/or depression may appear as a secondary phenomenon, which means being result of these diseases rather than the cause (Tab. 1, Fig. 2, Ref. 41).
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268th ENMC workshop - Genetic diagnosis, clinical classification, outcome measures, and biomarkers in Facioscapulohumeral Muscular Dystrophy (FSHD): Relevance for clinical trials
(Elsevier B.V., 2023) Montagnese F, de Valle K, Lemmers RJLF, Mul K, Dumonceaux J, Voermans N; 268th ENMC workshop participants.; Oflazer, Piraye; ; School of Medicine;
Highlights This ENMC workshop has seen the participation of many important stakeholders working together to improve trial readiness in FSHD: patients and patients’ organizations (FSHD-Europe, FSHD-Society and FSHD Global), neuromuscular clinicians, geneticists, basic researchers, representatives of the TREAT-NMD network, the FSHD-CTRN and EMA. COMs represent useful tools for the standardized collection of clinical features but need to be selected to match the clinical setting of use. For patient care, they need to be informative, with practical and time efficient utility so as not to detract from clinical care. For clinical trial purposes, the need to be reliable, valid, meaningful and sensitive to change to better depict therapeutic responses. An optimized clinical evaluation and genetic test form is one of the goals of WG1 and 2. A diagnostic flowchart for FSHD1 and FSHD2 has been proposed. Another important unmet need for clinical trial readiness in FSHD is the identification of good therapeutic biomarkers, which ideally should be quantitative, non-invasive, applicable across the entire range of disease severity, sensitive to change, reliable and clinically meaningful. The WG 3 will produce standard operating procedures (SOPs) for DUX4 detection. Similarly, large differences in the reporting of studies performed on animal models, thus hindering interpretation, repeatability and comparison of the results need to be addressed. Guidelines regarding minimum information for publication of work including animal models for FSHD will therefore be published.
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2d -> 3d polycatenated and 3d -> 3d interpenetrated metal-organic frameworks constructed from thiophene-2,5-dicarboxylate and rigid bis(imidazole) ligands
(Elsevier, 2014) Erer, Hakan; Yesilel, Okan Zafer; Arici, Mursel; Buyukgungor, Orhan; Department of Chemical and Biological Engineering; Keskin, Seda; Faculty Member; Department of Chemical and Biological Engineering; College of Engineering; 40548
Hydrothermal reactions of rigid 1,4-bis(imidazol-1-yl)benzene (dib) and 1,4-bis(imidazol-1-yl)-2, 5-dimethylbenzene (dimb) with deprotonated thiophene-2,5-dicarboxylic acid (H(2)tdc) in the presence of Zn(II) and Cd(II) salts in H2O produced three new metal-organic frameworks, namely, [Zn(mu-tdc)(H2O) (mu-dib)](n) (1), [Cd(mu-tdc)(H2O)(mu-dib)(n) (2), and {[Cd-2(mu(3)-tdc)(2)(mu-dimb)(2)] center dot (H2O)}(n) (3). These MOFs were characterized by FT-IR spectroscopy, elemental, thermal (TG, DTA, DTG and DSC), and single-crystal X-ray diffraction analyses. Isomorphous complexes 1 and 2 reveal polycatenated 2D+2D -> 3D framework based on an undulated (4,4)-sql layer. Complex 3 exhibits a new 4-fold interpenetrating 3D framework with the point symbol of 6(6). Molecular simulations were used to assess the potentials of the complexes for H-2 storage application. Moreover, these coordination polymers exhibit blue fluorescent emission bands in the solid state at room temperature.
Open Access
2D hybrid meshes for direct simulation Monte Carlo solvers
(Institute of Physics (IOP) Publishing, 2013) Şengil, Nevsan; Department of Mathematics; Şengil, Uluç; Master Student; Department of Mathematics; College of Sciences
The efficiency of the direct simulation Monte Carlo (DSMC) method decreases considerably if gas is not rarefied. In order to extend the application range of the DSMC method towards non-rarefied gas regimes, the computational efficiency of the DSMC method should be increased further. One of the most time consuming parts of the DSMC method is to determine which DSMC molecules are in close proximity. If this information is calculated quickly, the efficiency of the DSMC method will be increased. Although some meshless methods are proposed, mostly structured or non-structured meshes are used to obtain this information. The simplest DSMC solvers are limited with the structured meshes. In these types of solvers, molecule indexing according to the positions can be handled very fast using simple arithmetic operations. But structured meshes are geometry dependent. Complicated geometries require the use of unstructured meshes. In this case, DSMC molecules are traced cell-by-cell. Different cell-by-cell tracing techniques exist. But, these techniques require complicated trigonometric operations or search algorithms. Both techniques are computationally expensive. In this study, a hybrid mesh structure is proposed. Hybrid meshes are both less dependent on the geometry like unstructured meshes and computationally efficient like structured meshes.