An Elastic-Plastic Stress Analysis in Silicon Carbide Fiber Reinforced Magnesium Metal Matrix Composite Beam Having Rectangular Cross Section Under Transverse Loading

Okumus, Fuat The Korean Society of Mechanical Engineers 2004 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.18 No.2

In this work, an elastic-plastic stress analysis has been conducted for silicon carbide fiber reinforced magnesium metal matrix composite beam. The composite beam has a rectangular cross section. The beam is cantilevered and is loaded by a single force at its free end. In solution, the composite beam is assumed perfectly plastic to simplify the investigation. An analytical solution is presented for the elastic-plastic regions. In order to verify the analytic solution results were compared with the finite element method. An rectangular element with nine nodes has been choosen. Composite plate is meshed into 48 elements and 228 nodes with simply supported and in-plane loading condations. Predictions of the stress distributions of the beam using finite elements were overall in good agreement with analytic values. Stress distributions of the composite beam are calculated with respect to its fiber orientation. Orientation angles of the fiber are chosen as $0^{circ},\;30^{circ},\;45^{circ},\;60^{circ}\;and\;90^{circ}$. The plastic zone expands more at the upper side of the composite beam than at the lower side for $30^{circ},\;45^{circ}\;and\;60^{circ}$ orientation angles. Residual stress components of ${\sigma}_{x}\;and \;{\tau}_{xy}$ are also found in the section of the composite beam.

An Elastic-Plastic Stress Analysis in Silicon Carbide Fiber Reinforced Magnesium Metal Matrix Composite Beam Having Rectangular Cross Section Under Transverse Loading

Fuat OKUMUS 대한기계학회 2004 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.18 No.2

In this work, an elastic-plastic stress analysis has been conducted for silicon carbide fiber reinforced magnesium metal matrix composite beam. The composite beam has a rectangular cross section. The beam is cantilevered and is loaded by a single force at its free end. In solution, the composite beam is assumed perfectly plastic to simplify the investigation. An analytical solution is presented for the elastic-plastic regions. In order to verify the analytic solution results were compared with the finite element method. An rectangular element with nine nodes has been choosen. Composite plate is meshed into 48 elements and 228 nodes with simply supported and in-plane loading condations. Predictions of the stress distributions of the beam using finite elements were overall in good agreement with analytic values. Stress distributions of the composite beam are calculated with respect to its fiber orientation. Orientation angles of the fiber are chosen as 0° , 30°, 45°, 60° and 90°. The plastic zone expands more at the upper side of the composite beam than at the lower side for 30°, 45° and 60° orientation angles. Residual stress components of σX and τxy are also found in the section of the composite beam.<br/>

EVOLUTION OF RESEARCH IN THE HOSPITALITY AND TOURISM FIELD

Fevzi Okumus 한국호텔외식관광경영학회 2015 한국호텔외식경영학회 학술발표논문집 Vol.- No.-

EXPLAINING ONLINE BRAND EQUITY WITH WEBSITE INTERACTIVITY THEORY: A STUDY OF CUSTOMER EQUITY

Albert A. Barreda,Fevzi Okumus,Khaldoon Nusair,Anil Bilgihan 글로벌지식마케팅경영학회 2016 Global Marketing Conference Vol.2016 No.7

The Internet is considered as a competitive marketing instrument in advancing business-related information and real-time transaction opportunities (Kumar, 2013). Several brand managers are questioning whether the existent marketing approaches to position their brands, with the purpose to operate in a traditional and online setting, may be enhanced (Liu, 2012). The Internet is recognized as an influential instrument that has changed the manner brands conduct business and the way consumers and businesses interact (Boyland et al., 2013). The distinctive value that the Internet offers over conventional media is the capacity to interact with consumers. This permits practitioners to adjust their presentation to adapt specific consumers’ needs. Contrary to other forms of media, the Internet assists companies to create long-term relationships with its consumers as it allows a distinctive reciprocal communication. This reciprocal communication that distinguishes the latest marketing channels from conventional media is website interactivity (Wang et al., 2013). a mechanized environment the same way as a company does in a traditional environment. It includes communicating with consumers directly, generating an exclusive and individual interaction with them. As a central aspect in technology-mediated communication, Website interactivity has been identified as a critical component to create strong brands (Voorveld et al., 2013). Regardless of the significance of Website interactivity, very limited research was identified in the branding and marketing literature that investigate the influential role of interactivity on brand equity. To this date very few researchers have devoted efforts to investigate the influential impact of Website interactivity on branding constructs. Therefore, this study closes this gap with the conceptualization and the impact of the two dimensions of Website interactivity namely social interactivity and system interactivity on brand equity. Additionally, another contribution is to examine the mediating effect of brand image and brand awareness in the formation of brand equity in the online environment. The study propose a theory-based model of Website interactivity as a precursor to build online brand equity and to examine the relationships among Website interactivity, bran image, brand awareness, and brand equity in the context of branded Websites. Leaning on the fundamentals of branding literature and the Website interactivity theory, a theoretical framework is designed and seven hypotheses are examined. A two-phase analysis is considered, first a Confirmatory factor analysis (CFA) and then a Structural Equation Modeling (SEM). The findings show that the dimensions of Website interactivity impact significantly on the brand awareness and brand image which in turn influence online brand equity. As today limited research has been focused on studying the impact of Website interactivity as a branding instrument. In this study, the authors consider Website interactivity to be the interaction between Websites and individuals. In this sense, Website interactivity is viewed as an essential high-tech capability for building brands (Voorveld et al., 2013) as it allows a reciprocal communication with the system and other users. Current literature indicates that for a more real illustration of the dual dimensions of Website interactivity, studies devote user control as an expression of system interactivity and two-way communication as an expression of social interactivity (Wang et al., 2013). Two-way communication (social interactivity) refers to reciprocal communication between individuals. The dimension is perceived as the interaction between the users and the system (e.g. Website) (e.g. through e-mail, chat or toll-free telephone access to customer service, etc.). The user control (system interactivity) perspective is more concerned with the ability of the user to select content and guide the interaction (Lowry et al., 2006). User control is manifested when individuals are granted the opportunity to select the content and influence the communication. For instance, Web users may feel themselves as possessing user control because they have the capacity to select without restrictions (through an internal search engine).

THE IMPACT OF SYSTEM INTERACTIVITY ON ONLINE BRAND EQUITY: THE MEDIATING EFFECT OF TRUST INTEGRITY IN ONLINE ENVIRONMENTS

Albert A. Barreda,Khaldoon Nusair,Fevzi Okumus,Anil Bilgihan 글로벌지식마케팅경영학회 2016 Global Marketing Conference Vol.2016 No.7

Trusting beliefs are playing an increasingly important role in building customer-based brand equity (CBBE) in the business arena. The present study examines the mediating effect of trusting beliefs on the interactivity-brand equity relationship. An online survey was administered to collect data from randomly selected consumers. The results show that system interactivity impact brand equity directly and indirectly through trust integrity. The present theory-driven model contributes to a better understanding of online brand equity. Therefore, allocating resources to influence the perception of system interactivity and trusting integrity beliefs is valuable to develop online brand equity. This research contributes to the interactivity theory and the relationship marketing theory and it also offers implications for practitioners.

The Partial Purification and Properties of Pepsin Obtained from Turkey Proventriculus

Temiz, Hasan,Aykut, Umut,Okumus, Emin,Turhan, Sadettin Korean Society for Biotechnology and Bioengineerin 2007 Biotechnology and Bioprocess Engineering Vol.12 No.4

In this study, pepsin from turkey proventriculus was purified, and its biochemical properties examined. Initially, the turkey proventriculus (stomach) was mixed with 10% NaCl (1:2, w/v) and extracted by centrifugation to produce a crude extract. The partial purification of the extract was carried out using Sephadex G-50 resin in gel filtration column chromatography. The fractions obtained by gel filtration were analyzed for milk clotting activity (MCA), protein content, proteolytic activity (PA), purification factor (PF), and SOS-PAGE electrophoresis was also performed. The enzyme was purified 207-fold with a recovery of 36%. The first 4 fractions did not have any activities; fractions 7, 8, and 9 exhibited the highest levels of milk clotting and proteolytic activity. The electrophoretic patterns revealed that further purification steps should be applied for better results.

Male Breast Cancer: 20 Years Experience of a Tertiary Hospital from the Middle Black Sea Region of Turkey

Serarslan, Alparslan,Gursel, Bilge,Okumus, Nilgun Ozbek,Meydan, Deniz,Sullu, Yurdanur,Gonullu, Guzin Asian Pacific Journal of Cancer Prevention 2015 Asian Pacific journal of cancer prevention Vol.16 No.15

Background: Male breast cancer is a rare neoplasm, and its treatments are based on those of female breast cancer. This study aimed to analyze 20 years of male breast cancer clinical characteristics and treatment results from the Middle Black Sea Region of Turkey. Materials and Methods: A retrospective analysis of 16 male breast cancer patients treated in our tertiary hospital between 1994 and 2014 was performed. Epidemiologic data, tumor characteristics, and treatments were recorded and compared with 466 female breast cancer ((premenopausal; n = 230) + (postmenopausal n = 236)) patients. The 5-year disease-free and overall survival rates were calculated. Results: Male breast cancer constituted 0.1% of all malignant neoplasms in both sexes, 0.2% of all malignant neoplasms in males, and 0.7% of all breast cancers. The mean patient age in this study was $59.8{\pm}9.5$ (39-74) years. The mean time between first symptom and diagnosis was $32.4{\pm}5.3$ (3-60) months. Histology revealed infiltrative ductal carcinoma in 81.3% of patients. The most common detected molecular subtype was luminal A, in 12 (75%) patients. Estrogen receptor rate (93.8%) in male breast cancer patients was significantly higher than that in female breast cancer (70.8% in all females, p = 0.003; 68.2% in postmenopausal females, p = 0.002) patients. Most of the tumors (56.3%) were grade 2. Tumor stage was T4 in 50% of males. The majority (56.3%) of the patients were stage III at diagnosis. Surgery, chemotherapy, radiotherapy and endocrine-therapy were applied to 62.5%, 62.5%, 81.2% and 73.3%, respectively. Loco-regional failure did not occur in any of the cases. All recurrences were metastastic. The 5-year disease-free and overall survival rates in male breast cancer patients were 58% and 68%, respectively. Conclusions: Tumors found in male breast cancer patients were similar in size to tumors found in females, but they advanced to T4 stage more rapidly because of the lack of breast parenchymal tissues. The rate of estrogen receptor expression tended to be higher in male breast cancer patients than in female breast cancer patients. Metastasis is the most important problem in initially non-metastatic male breast cancer patients.

Extreme conformational diversity in human telomeric DNA.

Lee, J Y,Okumus, Burak,Kim, D S,Ha, Taekjip National Academy of Sciences 2005 PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF Vol.102 No.52

<P>DNA with tandem repeats of guanines folds into G-quadruplexes made of a stack of G-quartets. In vitro, G-quadruplex formation inhibits telomere extension, and POT1 binding to the single-stranded telomeric DNA enhances telomerase activity by disrupting the G-quadruplex structure, highlighting the potential importance of the G-quadruplex structure in regulating telomere length in vivo. We have used single-molecule spectroscopy to probe the dynamics of human telomeric DNA. Three conformations were observed in potassium solution, one unfolded and two folded, and each conformation could be further divided into two species, long-lived and short-lived, based on lifetimes of minutes vs. seconds. Vesicle encapsulation studies suggest that the total of six states detected here is intrinsic to the DNA. Folding was severely hindered by replacing a single guanine, showing only the shortlived species. The long-lived folded states are dominant in physiologically relevant conditions and probably correspond to the parallel and antiparallel G-quadruplexes seen in high-resolution structural studies. Although rare under these conditions, the short-lived species determine the overall dynamics because they bridge the different long-lived species. We propose that these previously unobserved transient states represent the early and late intermediates toward the formation of stable G-quadruplexes. The major compaction occurs between the early and late intermediates, and it is possible that local rearrangements are sufficient in locking the late intermediates into the stably folded forms. The extremely diverse conformations of the human telomeric DNA may have mechanistic implications for the proteins and drugs that recognize G-rich sequences.</P>

Physiological Profile of Growing Rats: Effects of Cage Type and Cage Density

Yildiz, A.,Hayirli, A.,Okumus, Z.,Kaynar, O.,Kisa, F. Asian Australasian Association of Animal Productio 2007 Animal Bioscience Vol.20 No.2

This experiment was conducted to examine the effects of cage type (CT) and cage density (CD) on physiological variables in growing rats. Sprague Dawley rats (n=108) weighing an average of 46 g were housed in metallic cage with woodchip bedding (MCWB), metallic cage with wire mesh (MCWM), and plastic shoebox with woodchip bedding (PCWB) separately by sex at normal ($160-cm^2/rat$, ND) and high ($80-cm^2/rat$, HD) CD from 3 to 10 wks of age. All cages were in dimension of $24{\times}40{\times}20$ cm ($W{\times}D{\times}H$). At the end of the experiment, blood samples were collected and 6 rats from each cage were sacrificed. No death was observed among rats at ND, whereas mortality rate at HD was 22.3% for males and 13.9% for females. Heart weight was affected by CT. Doubling CD caused 23, 11.8, 17.9, 8.6, 6.9, and 16.4% decreases in BW and weights of heart, liver, kidney, testis, and ovary, respectively. Except for adrenal gland, other organs for males were heavier than for females. Liver weight of males and females responded differently to CT and CD. Comparing with females, males had 7.3 and 5.2% heavier and 9.9% lighter liver weights in MCWB, MCWM, and PCWB, respectively. As CD doubled, liver weight for males and females decreased by 22.4 and 13.1%, respectively. Mean adrenal gland weight increased by 8.4% and decreased by 9.7% for males and females, respectively, with doubling CD. CT affected glucose, TG, Ca, and ALP levels. However, CD did not alter blood chemistry. Rats housed in metallic cages had greater neutrophil count and neutrophil:lymphocyte ratio than rats housed in plastic cages. Doubling CD caused a 24.2% increase in lymphocyte count. There were CT by CD, CT by sex, and CD by sex interaction effects on lymphocyte count. Doubling CD caused 0.1% decrease and 49.8 and 26.7% increases in lymphocyte count for rats housed in MCWB, MCWM, and PCWB, respectively. Comparing with females, lymphocyte count for males housed in MCWB, MCWM, and PCWB had 8.9 and 12.9% greater and 30.3% less lymphocyte counts, respectively. Lymphocyte count decreased by 4.12% for males, whereas it increased by 61.0% for females as CD doubled. Doubling CD resulted in 2.5 and 2.3% increases in erythrocyte count and hematocrit value. These data suggest that animals perform better in metallic cages than in plastic cages and that cage density had pronounceable effects on physiological parameters in a cage type and sex dependent-manner.

Radiation Exposure to Premature Infants in a Neonatal Intensive Care Unit in Turkey

Turan Olgar,Esra Onal,Dogan Bor,Nurullah Okumus,Yildiz Atalay,Canan Turkyilmaz,Ebru Ergenekon,Esin Koc 대한영상의학회 2008 Korean Journal of Radiology Vol.9 No.5

Objective: The aim of this work was to determine the radiation dose received by infants from radiographic exposure and the contribution from scatter radiation due to radiographic exposure of other infants in the same room. Materials and Methods: We retrospectively evaluated the entrance skin doses (ESDs) and effective doses of 23 infants with a gestational age as low as 28 weeks. ESDs were determined from tube output measurements (ESDTO) (n = 23) and from the use of thermoluminescent dosimetry (ESDTLD) (n = 16). Scattered radiation was evaluated using a 5 cm Perspex phantom. Effective doses were estimated from ESDTO by Monte Carlo computed software and radiation risks were estimated from the effective dose. ESDTO and ESDTLD were correlated using linear regression analysis. Results: The mean ESDTO for the chest and abdomen were 67 μGy and 65 μGy per procedure, respectively. The mean ESDTLD per radiograph was 70 μGy. The measured scattered radiation range at a 2 m distance from the neonatal intensive care unit (NICU) was (11-17 μGy) per radiograph. Mean effective doses were 16 and 27 μSv per procedure for the chest and abdomen, respectively. ESDTLD was well correlated with ESDTO obtained from the total chest and abdomen radiographs for each infant (R2 = 0.86). The radiation risks for childhood cancer estimated from the effective dose were 0.4 × 10-6 to 2 × 10-6 and 0.6 × 10-6 to 2.9 × 10-6 for chest and abdomen radiographs, respectively. Conclusion: The results of our study show that neonates received acceptable doses from common radiological examinations. Although the contribution of scatter radiation to the neonatal dose is low, considering the sensitivity of the neonates to radiation, further protective action was performed by increasing the distance of the infants from each other. Objective: The aim of this work was to determine the radiation dose received by infants from radiographic exposure and the contribution from scatter radiation due to radiographic exposure of other infants in the same room. Materials and Methods: We retrospectively evaluated the entrance skin doses (ESDs) and effective doses of 23 infants with a gestational age as low as 28 weeks. ESDs were determined from tube output measurements (ESDTO) (n = 23) and from the use of thermoluminescent dosimetry (ESDTLD) (n = 16). Scattered radiation was evaluated using a 5 cm Perspex phantom. Effective doses were estimated from ESDTO by Monte Carlo computed software and radiation risks were estimated from the effective dose. ESDTO and ESDTLD were correlated using linear regression analysis. Results: The mean ESDTO for the chest and abdomen were 67 μGy and 65 μGy per procedure, respectively. The mean ESDTLD per radiograph was 70 μGy. The measured scattered radiation range at a 2 m distance from the neonatal intensive care unit (NICU) was (11-17 μGy) per radiograph. Mean effective doses were 16 and 27 μSv per procedure for the chest and abdomen, respectively. ESDTLD was well correlated with ESDTO obtained from the total chest and abdomen radiographs for each infant (R2 = 0.86). The radiation risks for childhood cancer estimated from the effective dose were 0.4 × 10-6 to 2 × 10-6 and 0.6 × 10-6 to 2.9 × 10-6 for chest and abdomen radiographs, respectively. Conclusion: The results of our study show that neonates received acceptable doses from common radiological examinations. Although the contribution of scatter radiation to the neonatal dose is low, considering the sensitivity of the neonates to radiation, further protective action was performed by increasing the distance of the infants from each other.