Improvement of properties of self-flowing low-cement castables based on brownfused alumina

Necip Ünlü,Cem Gögtas,Akln Odabasl,Levent Sezer,Filiz Çlnar,Sule Güner,Niyazi Eruslu 한양대학교 세라믹연구소 2007 Journal of Ceramic Processing Research Vol.8 No.5

A new self flowing brown-fused alumina based castable with 5 wt.% cement has been developed. An Andreason mathematical model (q=0.25) was used to adjust the granulometric particle size distribution. To achieve optimum self-leveling flowability, 5.6% water was used. The main physical and mechanical properties of the present castable were studied. Phase analysis using X-ray diffraction (XRD), scanning electron microscopy (SEM) and apparent porosity (AP), bulk density (BD), water absorption (WA), cold crushing strength (CCS), hardness, and self-leveling flowability were investigated as a function of the firing temperature. The castable exhibited low AP and WA, and high CCS values with an increase in the firing temperature as a result of the corresponding phases. A new self flowing brown-fused alumina based castable with 5 wt.% cement has been developed. An Andreason mathematical model (q=0.25) was used to adjust the granulometric particle size distribution. To achieve optimum self-leveling flowability, 5.6% water was used. The main physical and mechanical properties of the present castable were studied. Phase analysis using X-ray diffraction (XRD), scanning electron microscopy (SEM) and apparent porosity (AP), bulk density (BD), water absorption (WA), cold crushing strength (CCS), hardness, and self-leveling flowability were investigated as a function of the firing temperature. The castable exhibited low AP and WA, and high CCS values with an increase in the firing temperature as a result of the corresponding phases.

An assessment of machine learning models for slump flow and examining redundant features

Ramazan Ünlü 사단법인 한국계산역학회 2020 Computers and Concrete, An International Journal Vol.25 No.6

Over the years, several machine learning approaches have been proposed and utilized to create a prediction model for the high-performance concrete (HPC) slump flow. Despite HPC is a highly complex material, predicting its pattern is a rather ambitious process. Hence, choosing and applying the correct method remain a crucial task. Like some other problems, prediction of HPC slump flow suffers from abnormal attributes which might both have an influence on prediction accuracy and increases variance. In recent years, different studies are proposed to optimize the prediction accuracy for HPC slump flow. However, more state-of-the-art regression algorithms can be implemented to create a better model. This study focuses on several methods with different mathematical backgrounds to get the best possible results. Four well-known algorithms Support Vector Regression, M5P Trees, Random Forest, and MLPReg are implemented with optimum parameters as base learners. Also, redundant features are examined to better understand both how ingredients influence on prediction models and whether possible to achieve acceptable results with a few components. Based on the findings, the MLPReg algorithm with optimum parameters gives better results than others in terms of commonly used statistical error evaluation metrics. Besides, chosen algorithms can give rather accurate results using just a few attributes of a slump flow dataset.

Remarkable effects of deep eutectic solvents on the esterification of lactic acid with ethanol over Amberlyst-15

Ayşe Ezgi Ünlü,Azime Arıkaya,Aybike Altundağ,Serpil Takaç 한국화학공학회 2020 Korean Journal of Chemical Engineering Vol.37 No.1

Deep eutectic solvents (DESs) are widely used in numerous reactions both as a solvent and a catalyst. In this study, different types of DESs were investigated as a supplementary component for Amberlyst-15 to enhance its catalytic activity in the esterification reaction of lactic acid with ethanol. The effects of the following parameters such as DES type, choline chloride : glycerol (ChCl-Gly) (1 : 2) amount, molar ratio of reactants, temperature and agitation rate on the initial rate of reaction and yield of ethyl lactate were investigated. According to the results, DESs alone did not have any catalytic effect on the esterification; however, DESs together with Amberlyst-15 provided a significant increase in the initial rate of reaction and yield. The activation energy of the reaction decreased significantly with the combined use of Amberlyst-15 and ChCl-Gly (1 : 2). Internal and external mass transfer limitations were found to be negligible under optimum reaction conditions.

Characterization of short-length multi-walled carbon nanotubes and cytotoxicity on MDA-MB-231 and HUVEC cell lines

Dinç Bircan,Ünlü Ayhan,Bektaş Muhammet 한국탄소학회 2020 Carbon Letters Vol.30 No.2

Multi-walled carbon nanotubes (MWNTs) are suitable for delivering large biomolecules with lower cytotoxicity values and low prime cost. Surface modifcations of MWNTs afect interaction with cells and proteins. Oxidation with strong acids decreases cytotoxicity of CNTs and increases protein-loading capacity. Here, after oxidation, TEM images revealed more aligned structure and carboxylated groups at the surface which decreases toxicity. Functionalized MWNTs showed more gradual degradation than the pristine MWNTs and mass loss increased by 2% in the same temperature range. Raman spectroscopy corrected graphitic structure with characteristic D and G bands at 1330 and 1579 cm−1 and increased intensity after oxidation. FTIR spectroscopy peaks at 1443 cm−1, 1560, 1640 cm−1, 2100–2200 cm−1 and 3426 cm−1 are ascribed to C–O–C vibrational stretch, C=C bonds, vibration of C≡C bonds and stretch of hydroxyl groups, respectively. The sonication�driven dispersion of in phosphate-bufered saline, distilled water and cell culture medium were detected by UV–vis–NIR spectroscopy, water-dispersed functionalized MWNTs revealed the highest absorbance value. Cytotoxicity of MWNTs was investigated before and after functionalization in breast cancer (MDA-MB-231) and human vein endothelial (HUVEC) cells. Relatively low-toxicity results were obtained in functionalized MWNTs and cellular uptake of MWNTs were corrected with fuorescent imaging of cells and cell lysates. Protein-loading capacity of fsMWNTs (functionalized short-length multi-walled carbon nanotubes) was evaluated by using bovine serum albumin (BSA) and with an equal amount of fsMWNTs and BSA; 36% binding yield was obtained. Protein corona after covalent functionalization potentially lowered cytotoxicity up to 6%

Testicular Adrenal Rest Tumor in 11-Beta-Hydroxylase Deficiency Driven Congenital Adrenal Hyperplasia

Mehmet Kaynar,Mehmet Giray Sönmez,Yaşar Ünlü,Tuna Karatağ,Erdem Tekinarslan,Alpay Sümer 대한비뇨의학회 2014 Investigative and Clinical Urology Vol.55 No.4

Testicular adrenal rest tumors (TART) occur often as asymptomatic nodules in corticotropin-dependent lesions aberrant adrenal tissue in congenital adrenal hyperplasia(CAH) patients. The present manuscript is about an unusual case of a 16-year-old CAHpatient due to 11β-hydroxylase deficiency. He underwent testicle biopsy because of testicletumor suspicion and diagnosed with TART.

Evaluating the effect of donor anxiety levels and lifestyle characteristics on the activation of platelet concentrates

Soner Yılmaz,İbrahim Eker,Elif Elçi,Aysel Pekel,Rıza Aytaç Çetinkaya,Aytekin Ünlü,Cengizhan Açıkel,İsmail Yaşar Avcı 대한혈액학회 2019 Blood Research Vol.54 No.4

BackgroundSmoking, alcohol use, performing regular physical exercise, dietary habits, and anxiety level may cause platelet activation. We aimed to evaluate the anxiety levels, smoking sta-tus, alcohol intake, and sportive habits of donors, and determine their impact on the qual-ity of apheresis-platelets.MethodsState and Transient Anxiety Inventory (STAI) was used to determine the level of donors’anxiety. STAI has two subscales: S-anxiety scale (STAI-I) and T-anxiety scale (STAI-II), each comprising 20 questions rated on a 4-point Likert scale. Data on smoking, alcohol con-sumption, and performing regular physical exercise were obtained from a questionnaire filled out before donation. Flow cytometric analysis was used to quantify activated platelets.ResultsThe STAI-I level of 86 participants was normal, while that of 12 was higher. No significant difference was found in the active platelet absolute count [1.8×1011 (2.7) and 1.4×1011 (1.3), respectively; P=0.665] between donors with normal STAI-I levels and those with higher STAI-I levels. Of 98 donors, 42 had normal STAI-II levels, while 56 had higher STAI-II levels. No significant difference was found in the active platelet absolute count [2.3×1011 (3.1) and 1.5×1011 (2.3), respectively; P=0.224] between donors with normal STAI-II levels and those with higher STAI-II levels. Platelet counts of individuals who perform regular physical exercise were significantly higher than those of individuals who did not perform regular physical exercise (6.3±1.4×1011 vs. 5.5±1.4×1011).ConclusionThe quality of apheresis platelets is not affected by anxiety levels and lifestyle character-istics of blood donors. There is no need to organize apheresis blood donor pool consider-ing with these subjects.

Effects of Dexmedetomidine Infusion During Sevoflurane Anesthesia on Otoacoustic Emissions

Mehmet İlhan Şahin,Alperen Vural,Aynur Akın,İbrahim Ketenci,Yaşar Ünlü 대한청각학회 2019 Journal of Audiology & Otology Vol.23 No.2

Background and Objectives: Knowing the ototoxic potential of the agents used in medical treatments is important for the protection of hearing. Although we have knowledge regarding some effects of dexmedetomidine, which is an anesthetic-sparing drug, its influence over the hearing system has never been studied and is obscure yet. The aim of this study is to determine the effects of intravenous dexmedetomidine application during sevoflurane anesthesia on otoacoustic emissions (OAEs). Subjects and Methods: This prospective randomized study was performed on 60 patients (34 male, 26 female, mean age: 30.6±9.2 years) who were scheduled for an elective surgery under general anesthesia and the patients were enrolled and randomly divided into 2 groups. They received dexmedetomidine (Group D) or Saline (Group S) infusion during a standardized Sevoflurane anesthesia. Transient and distortion product OAEs were measured preoperatively and postoperatively (24th hour). OAE results were compared within and between groups. Results: In group D postoperative OAEs were lower than preoperative OAEs and postoperative levels of group S, especially at low frequencies (p<0.05). Conclusions: Dexmedetomidine infusion affects the micromechanical function of cochlea especially in the low-frequency region. Dexmedetomidine should be carefully used during general anesthesia to avoid its probable harmful effects on cochlear micromechanics.

Premedication Methods in Nasal Endoscopy: A Prospective, Randomized, Double-Blind Study

Mehmet İlhan Şahin,Kerem Kökoğlu,Şafak Güleç,İbrahim Ketenci,Yaşar Ünlü 대한이비인후과학회 2017 Clinical and Experimental Otorhinolaryngology Vol.10 No.2

Objectives. To identify the optimal pharmacological method of preparing patients for nasal endoscopy. Methods. Twenty healthy volunteers were enrolled in this prospective, randomized, double-blind study. Four types of medications were applied in their nostrils with binary combinations of spray bottles on four different days in a random order: placebo (normal saline [NS]+NS), decongestant (NS+oxymetazoline), anesthetic (NS+lidocaine), and decongestant plus anesthetic (oxymetazoline+lidocaine). Rigid nasal endoscopy was performed 10 minutes after spray application. The volunteers evaluated the discomfort caused by each spray application, and nasal pain scores due to the passage of the endoscope. The physicians quantified nasal decongestion using a visual analogue scale. Endoscopy duration as well as pulse and mean blood pressure (MBP) before spray application, 10 minutes after the application, and immediately after endoscopic examination were also recorded. Results. The discomfort caused by lidocaine was significantly higher than that caused by the other sprays (P<0.001). The lowest pain score related to endoscopy was obtained for oxymetazoline+lidocaine (P<0.001). Nasal decongestion was best achieved with NS+oxymetazoline (P<0.001). Endoscopy duration was the shortest for oxymetazoline+lidocaine (P<0.05). Statistically significant MBP changes were only seen with the application of NS+oxymetazoline (P<0.05). However, neither MBP nor pulse rate change was significant clinically. Conclusion. Application of decongestant and anesthetic sprays together seems to be the best method of pharmacological preparation of patients for nasal endoscopy.

Extraspinal Incidental Findings on Routine MRI of Lumbar Spine: Prevalence and Reporting Rates in 1278 Patients

Sedat Alpaslan Tuncel,Bekir Çaglı,Aslan Tekatas¸,Mehmet Yadigar Kırıcı,Ercüment Ünlü,Hakan Gençhellaç 대한영상의학회 2015 Korean Journal of Radiology Vol.16 No.4

The aim of the present study was to determine the prevalence and reporting rate of incidental findings (IF) in adult outpatients undergoing lumbar magnetic resonance imaging (MRI). Re-evaluation of a total of 1278 lumbar MRI images (collected from patients with a mean age of 50.5 years, range 16–91 years) captured between August 2010–August 2011 was done by a neuroradiologist and a musculoskeletal radiologist. IFs were classified according to organ or system (liver, gallbladder, kidney, bladder, uterus, ovary, lymph node, intestine and aorta). The rate of reporting of a range of IF was examined. The outcome of each patient’s treatment was evaluated based on review of hospital records and by telephone interviews. A total of 253 IFs were found in 241 patients (18.8% of 1278). Among these, clinically significant IFs (n = 34) included: 2 renal masses (0.15%), 2 aortic aneurysms (0.15%), 2 cases of hydronephrosis (0.15%), 11 adrenal masses (0.86%), 7 lymphadenopathies (0.55%), 6 cases of endometrial or cervical thickening (0.47%), 1 liver hemangioma (0.08%), 1 pelvic fluid (0.08%) and 2 ovarian dermoid cysts (0.15%). Overall, 28% (71/253) of IFs were included in the clinical reports, while clinically significant findings were reported in 41% (14/34) of cases. Extraspinal IFs are commonly detected during a routine lumbar MRI, and many of these findings are not clinically significant. However, IFs including clinically important findings are occasionally omitted from formal radiological reports.

Characterization of the physical properties of a self-flowing low-cement castable based on white-fused alumina

Cem Gö tas,Akln Odabasl,Levent Sezera,Filiz Çlnarb,Sule Günerc,Niyazi Eruslua,Necip Ünlü 한양대학교 세라믹연구소 2009 Journal of Ceramic Processing Research Vol.10 No.1

A white-fused low cement refractory castable was prepared from pure refractories that consisted of 77 wt.% white fused alumina, 10 wt.% calcined alumina, 8 wt.% microsilica, 5 wt.% cement and 0.05 wt.% dispersant. Optimum self-leveling flowability was achieved by using 5.6 wt.% water. To determine the effect of the firing temperature on the white-fused low cement refractory castable, studies of apparent porosity (AP), bulk density (BD), water absorption (WA), cold crushing strength (CCS), hardness, X-ray diffraction (XRD) and microstructural-based evaluation using electron probe microanalyser (EPMA) were performed. The present castable heat treated at 1500℃ for 2 h exhibited the following properties: the AP −14%, the BD −3.12 gcm−3, the WA −2.5%, the CCS −2000 kgcm−2 and the hardness −3185 kg㎟. The new white-fused alumina castable presents unique properties that would make it desirable to use in industrial refractory applications. A white-fused low cement refractory castable was prepared from pure refractories that consisted of 77 wt.% white fused alumina, 10 wt.% calcined alumina, 8 wt.% microsilica, 5 wt.% cement and 0.05 wt.% dispersant. Optimum self-leveling flowability was achieved by using 5.6 wt.% water. To determine the effect of the firing temperature on the white-fused low cement refractory castable, studies of apparent porosity (AP), bulk density (BD), water absorption (WA), cold crushing strength (CCS), hardness, X-ray diffraction (XRD) and microstructural-based evaluation using electron probe microanalyser (EPMA) were performed. The present castable heat treated at 1500℃ for 2 h exhibited the following properties: the AP −14%, the BD −3.12 gcm−3, the WA −2.5%, the CCS −2000 kgcm−2 and the hardness −3185 kg㎟. The new white-fused alumina castable presents unique properties that would make it desirable to use in industrial refractory applications.