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Frontiers of Structural and Civil Engineering 2021年第5期15卷 1277-1291页

作者： Ali NEMATZADEH burcu aytekin Ali MARDANL-AGHABAGLOU Department of Civil Engineering Bursa Uludag UniversityNilufer-Bursa 16059Turkey

In this paper,the effect of usage of the permeability reducing admixture(PRA)having different action mechanisms on hardened state properties of cementitious systems containing mineral additives is *** this aim,three commercial PRAs were used during *** effective parameters in the first and third PRAs were air-entraining and high-rate air-entraining,*** second one contained the insoluble calcium carbonate residue and had a small amount of the air-entraining *** mixes with binary and ternary cementitious systems were prepared by partially replacing cement with fly ash and *** hardened state properties of mortar mixtures such as compressive strength,ultrasonic pulse velocity,water absorption,drying shrinkage and freeze-thaw resistance were *** ternary cement-based mixture having both fly ash and metakaolin was selected as the most successful mineral-additive bearing mix in regard to hardened state *** this sense,PRA-B,with both insoluble residues and a small amount of air-entraining properties,showed the best performance among the mixtures containing *** combined use of mineral additive and PRA had a more positive effect on the properties of the mixes.

关键词： cementitious system mineral additive permeability reducing admixture mechanical properties durability performance

ON THE NUMERICAL SOLUTION OF QUASILINEAR WAVE EQUATION WITH STRONG DISSIPATIVE TERM

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Applied Mathematics and Mechanics(English Edition) 2004年第7期25卷 806-811页

作者： aytekin Gülle Department of Mathematics

The numerical solution for a type of quasilinear wave equation is *** three-level difference scheme for quasi-linear waver equation with strong dissipative term is constructed and the convergence is *** error of the d... 详细信息

关键词： periodical problem quasilinear wave equation difference scheme numerical solution

Effects of Tungsten and Boron Contents on Crystallization Temperature and Microhardness of Tungsten Based Metallic Glasses

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Acta Metallurgica Sinica(English Letters) 2015年第6期28卷 733-738页

作者： Pelin ztürk aytekin Hitit Department of Materials Science and Engineering AfyonKocatepe University

Effects of tungsten and boron contents on the thermal properties and microhardness of W-Fe-B metallic glass system were studied. Thin foils, with thicknesses of 20 and 100 ktm, of the alloys were produced by piston and anvil method in an arc furnace. The structures of the foils were investigated by X-ray diffraction. Thermal stabilities of the alloys were examined by using differential scanning calorimetry. 20-μm- thick foils of all the alloys were determined to be fully amorphous, but crystalline phases were detected in the 100-μm-thick foils. It was found that crystallization temperatures of the alloys are between 1060 and 1177 K. Tungsten and boron content increases improve the crystallization temperature and microhardness of the alloys significantly, but deteriorate the glass forming ability of the alloys. It was also observed that for constant Fe content, increasing tungsten content to the level higher than that of boron content does not result in any further improvement in crystallization temperature, but improves glass forming ability significantly. The alloy containing highest total amount of tungsten and boron, W35Fe35B3o, has the highest crystallization temperature, 1177 K, and microhardness, 1634 HV.

关键词： Metallic glass Refractory metal Crystallization temperature Hardness

Physical,Anatomical,and Photochemical Analyses of Some ExoticWood Species Submitted to Heat Treatment

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Journal of Renewable Materials 2021年第8期9卷 1485-1501页

作者： Alper aytekin Hikmet Yazıcı Bartın University Department of Management Information SystemsBartın74100Turkey Zonguldak Bulent Ecevit University Çaycuma Vocational SchoolZonguldak67100Turkey

The objective of this study was to evaluate the effect of heat treatment on decorative properties including glossiness,color coordinates including lightness(L),blue-yellow(b^(*))and red-green(a^(*)),hardness(shore-D)morphological characterization and thermal properties of some exotic wood *** treatment of anigre(Aningeria altissima),cedrorana(Cedrelinga catenaeformis),cemara(Casuarina sumatrana)and coronilla(Scutia buxifolia)wood materials were performed in an oven with a programmable controller at 210°C for 3 *** obtained samples were conditioned in a climate cabin and the decorative properties,morphological characterization with scanning electron microscopy(SEM)and thermal properties with thermogravimetric analyzer(TGA)of the obtained samples were *** test results showed that color got darker with heat treatment,specifically L and b^(*)decreased,and a^(*)increased for anigre and cedrorana but a^(*)decreased for cemara and *** glossiness for all samples generally increased from 20°to 85°but heat treatment decreased the *** density generally decreased with heat treatment and decrease ratio in the density was found to be in range from 5.6%to 10.6%.According to the SEM analysis,some cracks,pit aspiration and layer decomposition in the micro level of the wood structure were *** showed that heat treatment makes thermally more stable *** a result,it can be said that heat treatment improved the decorative properties of the exotic wood.

关键词： Heat treatment color gloss hardness anigre wood cedrorana wood cemara wood coronilla wood

Effect of Annealing on Microstructure and Microhardness of Co-Fe-Ni-Ta-B-Si Bulk Metallic Glass

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Journal of Materials Science & Technology 2015年第2期31卷 148-152页

作者： aytekin Hitit Merve Gecgin Pelin Oztürk Department of Materials Science and Engineering Afyon Kocatepe UniversityAfyonkarahisar 03200Turkey Department of Materials Science and Engineering Anadolu UniversityEskisehir 26555Turkey

Effects of annealing temperature and time on microstructure and microhardness of Co41Ni2Fe20Ta5.5B26.5Si5 amorphous alloy have been investigated. Microhardness of the as-cast alloy is found to be 1170 HV. The maximum microhardness,1798 HV,is achieved after annealing the amorphous alloy at 1250 K for 10 *** of the microstructure reveals that(Co,Fe)2B,(Co,Fe)21Ta2B6 and(Co,Fe)16Ta6Si7 phases precipitate in the matrix after annealing. Intrinsic hardness and Hall-Petch coefficients of the precipitates indicate that high hardness values result from precipitation of(Co,Fe)2B and(Co,Fe)21Ta2B6 phases. It is also observed that increasing the annealing time results in the decrease in microhardness values because of the increase in particle sizes of the precipitates.

关键词： Metallic glass Annealing Microhardness

Acceleration of coxarthrosis by an exostosis causing femoroacetabular impingement

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Health 2010年第4期2卷 318-320页

作者： Mahmut Nedim aytekin Hakan Atalar burcu Yanik Murat Arikan 不详

Here we describe a 28-year-old man with a history of right hip pain for the past 11 years and ankylosing spondylitis for the past 6 months. Imaging studies showed an exostosis in the femoral neck causing femoroacetabular imping- ement. The patient was diagnosed with coxar- throsis. This case report suggests that femoro- acetabular impingement may accelerate the degenerative process in the hip joint.

关键词： Femoroacetabular Impingement Exostosis

Assessment of the consecutive harmful dinoflagellate blooms during 2015 in the Izmit Bay(the Marmara Sea)

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Acta Oceanologica Sinica 2018年第8期37卷 91-101页

作者： ERGüL Halim aytekin AKSAN Serdar IPSIROGLU Merve Department of Biology Science and Arts FacultyKocaeli UniversityKocaeli 41380Turkey

A series of red tides were observed during 2015 in the Izmit Bay（the Marmara Sea） which is located in the most industrialized and populated region of Turkey. Six samplings were carried out in this area following the red ***-N, nitrate-N, ammonia, silica and orthophosphate concentrations were analyzed *** conditions were measured by CTD probe. Plankton quantification was performed using counting chambers under microscopes. Prorocentrum micans was the most abundant species, except on May 14,2015, when Noctiluca scintillans was dominant. The abundance of P. micans reached average 18×10~6 ind./L on May 3, 2015 in the Karamürsel station, simultaneously with elevated levels of NH_3 and o-PO_4^（3–）. The sample was also abundant in dead amphipods（（72±12） ind./L） that had been covered by mucilage aggregates produced by ***. The highest biomass（calculated by carbon） was recorded as（268±26.0） mg/L on May 14 in the Hereke station. Beside the anthropogenic wastewater discharges, unknown sources and resuspensions caused increases in nutrient levels. After long term northeaster gusts（35 km/h for 5 d） an upwelling occurred on November 6, 2015 after wind-induced sediment resuspension. Although nutrient discharges remarkably decreased over 30 years through established wastewater treatment plants, harmful phytoplankton blooms still occur. Comparing the present results with other studies in nearby Mediterranean seas reveals that the most intense harmful dinoflagellate bloom in recent years occurred in the Izmit Bay. Therefore, additional protection measures necessary for a cleaner Izmit Bay. These incidents also demonstrate that contaminants, accumulated in sediment,may have long-lasting effects on enclosed marine ecosystems.

关键词： red tide harmful algal bloom phytoplankton dinoflagellate Izmit Bay Marmara Sea mucilage

An Opinion Mining Task in Turkish Language： A Model for Assigning Opinions in Turkish Blogs to the Polarities

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Journalism and Mass Communication 2013年第3期3卷 179-198页

作者： Cigdem aytekin Marmara University Istanbul Turkey

Global changes took place at a neck-breaking speed in lots of fields along with the Web 2.0 era, which can be stated as the new Internet trend. Web pages which once were a statical structure that can be said to become dynamic pages created by users, and in this regard they can be said to have been democratized by evolving. Social media, which were structured alongside with this era, by providing a large data flow for businesses, present new and improvable opportunities in the field of creating effective strategies. There are lots of blogs in today＇s Internet environment which includes customer ideas regarding the products/services that they possess. This environment, which in a way globalizes the customer ideas, is a new medium suitable for examination in terms of its increasing the business-customer interaction and due to its transporter nature; it provides the text data that may be analyzed in the field of Customer Relationship Management to businesses. Thus, businesses should follow blog environments to see how the product/service they provide is greeted in terms of the customer focus and it should be seen as an important job on which they can conduct effective analyses. For this purpose, a model proposal that will assign the ideas to the Turkish blogs was given in the study. Opinion mining methods were used in the model, and so to perceive a general look-on about products/services, a methodology was devised, which will assign the text based opinion data on the Turkish blogs to the poles. Success of the pole assignment of the model is evaluated with the precision measure.

关键词： opinion mining text classification sentiment classification semantic orientation positive/negative polarity

Knowledge and attitudes of orthopedic surgeons regarding prosthesis joint infection

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World Journal of Orthopedics 2023年第4期14卷 240-247页

作者： Mahmut Nedim aytekin Imran Hasanoglu Recep Öztürk Nihat Tosun Department of Orthopedics and Traumatology Ankara Yıldırım Beyazıt UniversityFaculty of MedicineAnkara 06500Turkey Department of Infectious Diseases and Clinical Microbiology Ankara Yıldırım Beyazıt UniversityFaculty of MedicineAnkara City HospitalAnkara 06500Turkey Department of Orthopedics and Traumatology Dr.Abdurrahman Yurtaslan Ankara Oncology Training and Research HospitalAnkara 06200Turkey

BACKGROUND Periprosthetic joint infection(PJI)is a critical complication after joint arthroplasty and is accompanied by increasing rates of morbidity and *** studies have aimed at preventing *** To research the knowledge level and attitudes of orthopedic surgeons,who play a key role in both preventing and managing *** We conducted a web-based survey to evaluate orthopedic surgeons'knowledge level and attitudes regarding *** Likert scale survey utilized consisted of 30 questions which were prepared based on the"Proceedings of the International Consensus on Periprosthetic Joint Infection".RESULTS A total of 264 surgeons participated in the *** average age was 44.8,and 173 participants(65.5%)had more than 10 years of *** statistically significant relationship was found between the PJI knowledge of the surgeons and their years of ***,participants who worked in training and research hospitals demonstrated higher levels of knowledge than the ones in the state *** was also noticed that surgeons'knowledge concerning the duration of antibiotic therapy and urinary infections was not consistent with their *** Even though orthopedic surgeons have adequate knowledge about preventing and managing PJI,their attitudes might contradict their *** studies are required to examine the causes and solutions of the contradictions between orthopedic surgeons'knowledge and attitudes.

关键词： Antibiotic prophylaxis Periprosthetic joint infection Prevention Total joint replacement Turkey

Comprehensive clinicopathologic characteristics of intraabdominal neurogenic tumors:Single institution experience

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World Journal of Clinical Cases 2021年第10期9卷 2218-2227页

作者： Cem Simsek Meral Uner Feride Ozkara Orkun Akman aytekin Akyol Taylan Kav Cenk Sokmensuer Gokhan Gedikoglu Department of Gastroenterology Hacettepe UniversityAnkara 06230Turkey Department of Pathology Hacettepe UniversityAnkara 06230Turkey Department of Internal Medicine Hacettepe UniversityAnkara 06230Turkey Department of Pathology Yozgat City HospitalYozgat 66100Turkey

BACKGROUND Neurogenic tumors are rare but represent an important consideration in the differential diagnosis of abdominal mesenchymal *** on their incidence,pathological features and clinical characteristics are *** To advance the overall knowledge on the histologic,immunohistochemical,clinical and radiologic characteristics of neurogenic tumors through this case *** An established database of a nationwide tertiary referral center,covering a 15-year period(2005 and 2020),was retrospectively *** of neurogenic tumor cases were confirmed by two experts following review of the macroscopic,histological and immunohistochemical records along with findings from analysis of archived tissue sections for each included *** microarrays were constructed for cases lacking necessary immunohistochemical *** data and follow-up information were collected from the hospital records and the patients themselves,when *** The study included 19 cases of intraabdominal neurogenic tumors,representing 12 women and 7 men, between 18 and 86 years of age (median: 51 years). Finalconfirmed diagnoses were 12 schwannomas, 2 diffuse submucosal neurofibromatoses,2 ganglioneuromas, 2 malignant peripheral sheath nerve tumors,and 1 mucosal Schwann cell hamartoma. Sizes of the tumors were variable, with amedian diameter of 4 cm;the two largest (> 10 cm) were schwannomas. Themajority of cases were asymptomatic at presentation, but the most frequentsymptom was abdominal pain. Gastrointestinal tract lesions were detected withendoscopy and extra-luminal lesions were detected with cross-sectional *** cases were S100-positive and CD117-negative;most cases were negative fordesmin, epithelial membrane antigen, smooth muscle actin and CD34. In all but 5cases, the Ki67 proliferation index was ≤ 1%.CONCLUSION Re-evaluation of 19 cases of abdominal neurogenic tumors demonstrated considerablevariability in clinicopathologic ch

关键词： Neurogenic tumors Mesenchymal tumors Schwannoma Neurofibroma Malignant peripheral sheath tumor Intraabdominal