Hacettepe Üniversitesi Açık Erişim Sistemi (HÜAES)

  • HÜAES, Hacettepe Üniversitesi bünyesinde üretilen kitap, makale, tez, bildiri, rapor gibi tüm akademik kaynakları uluslararası standartlarda dijital ortamda depolar, etkisini artırmak için telif haklarına uygun olarak Açık Erişime sunar.
 

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İş Becerikliliğinin Çalışan Yaratıcılığı Üzerindeki Etkisinde Psikolojik Güvenlik ve Algılanan Örgütsel Desteğin Düzenleyici Rolü: Bir Alan Çalışması
(Sosyal Bilimler Enstitüsü, 2026) Aysu Helin Ay Büyükorhan; İşletme
In contemporary working life, increasing uncertainty, changing job structures, and growing expectations for proactive employee behavior require employees not only to perform formally defined tasks but also to reshape their jobs. In this context, job crafting is regarded as an important behavioral mechanism that enables employees to reorganize their job resources and demands in line with their needs, competencies, and goals. Employee creativity, on the other hand, is a critical variable for organizations’ innovation capacity, problem-solving ability, and competitive advantage. The aim of this study is to examine the effect of job crafting on employee creativity and to reveal the moderating roles of psychological safety and perceived organizational support in this relationship. Within this framework, the relationships between the subdimensions of job crafting—increasing structural job resources, increasing social job resources, increasing challenging job demands, and decreasing hindering job demands—and employee creativity were examined separately. The study was conducted with survey data collected from white-collar employees working in various sectors. Factor, reliability, correlation, regression, and moderation analyses were performed on the dataset. The hypotheses proposed within the scope of the study were analyzed using SPSS and AMOS 23 (IBM Corp., 2014), and the findings obtained were evaluated in line with the theoretical framework of the research and the relevant literature. The findings indicated that job crafting had a generally positive effect on employee creativity. More specifically, increasing structural job resources, increasing challenging job demands, and decreasing hindering job demands had significant and positive effects on employee creativity, whereas increasing social job resources did not have a significant effect. In addition, perceived organizational support had a positive and significant direct effect on employee creativity, while the direct effect of psychological safety was not supported. Regarding moderating effects, only psychological safety played a significant role in the relationship between increasing challenging job demands and employee creativity, and this effect occurred in a weakening direction, contrary to expectations. Perceived organizational support did not exhibit a consistent moderating effect across the examined models; however, a negative, low-effect-size, and marginally significant moderating effect was observed in the relationship between decreasing hindering job demands and employee creativity. These findings reveal that the relationship between job crafting and employee creativity cannot be evaluated independently of contextual conditions, indicating that organizations need to shape both their job design and work climate by taking this complexity into account.
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İleriye Etkili Sadakat Yükümlülüğü
(Sosyal Bilimler Enstitüsü, 2026) Şimşekler Songül; Özel Hukuk
Contrary to the traditional understanding, an obligation relationship is not a static structure that terminates merely with the performance of obligations; rather, it constitutes a dynamic relational framework grounded in the principles of good faith and reliance, extending beyond the temporal limits of performance. Accordingly, the liquidation of the obligation does not necessarily entail the extinction of all duties. On the contrary, as a reflection of the qualified social interaction between the parties, duties of loyalty may, in certain contractual relationships, continue to exist even after termination. This study examines post-contractual duties of loyalty within the framework of Turkish and comparative law. Its primary aim is to determine the extent to which the legal bond between the parties persists after the termination of the contract and to analyse how this bond is shaped through post-contractual duties of loyalty. In this context, the definition, legal nature, scope, and limits of such duties are identified, and the liability regime applicable in case of their breach is systematically evaluated in light of doctrinal approaches. The study further illustrates the practical manifestations of these duties through concrete examples such as confidentiality, non-compete obligations, duties to inform, and the obligation to re-employ. It is emphasised that, in order to prevent post-contractual duties of loyalty from transforming into a perpetual restriction on contractual freedom, any interference must remain exceptional, proportionate to the circumstances of the конкрет case, and aligned with the requirements of good faith and fairness. In the event of a breach, unlike liability based on culpa in contrahendo, the existence of a valid contractual basis generally leads to the compensation of expectation (positive) damages. Ultimately, this study seeks to delineate the dogmatic boundaries of post-contractual duties of loyalty—an area not yet sufficiently systematised in Turkish law—and to offer solutions to practical challenges.
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GİRİŞİMCİ LİDERLİĞİN YENİLİKÇİ İŞ DAVRANIŞI ÜZERİNDEKİ ETKİSİNDE ÇALIŞANLARIN PSİKOLOJİK DAYANIKLILIĞININ DÜZENLEYİCİ ROLÜ: BİR ALAN ÇALIŞMASI
(Sosyal Bilimler Enstitüsü, 2026-06-04) Yıldız Türkay; İşletme
In today's business environment, characterized by increasing competition and uncertainty, unlocking employees’ innovative potential has become a critical requirement for organizations seeking to achieve sustainable competitive advantage. The primary purpose of this study is to examine the direct effect of entrepreneurial leadership on employees’ innovative work behavior and to investigate the moderating role of psychological resilience in this relationship. The research model was evaluated within the theoretical framework of Strong Situation Theory and the Resource Substitution perspective, both of which are widely discussed in the organizational behavior literature. The sample of the study consists of 386 white-collar employees working at different hierarchical levels in both public and private sector organizations across Türkiye. Data were collected through an online survey using a convenience sampling method. The obtained dataset was analyzed and prepared for statistical examination using SPSS and AMOS software packages. To test the proposed research model, confirmatory factor analysis, reliability analysis, correlation analysis, and multiple linear regression analyses were conducted. The moderating effect was examined using PROCESS Macro (Model 1). The findings revealed that entrepreneurial leadership has a statistically significant and positive effect on innovative work behavior. However, psychological resilience was found to have no significant direct effect on innovative work behavior. Furthermore, contrary to expectations, psychological resilience did not moderate the relationship between entrepreneurial leadership and innovative work behavior. In the discussion section, this noteworthy finding is interpreted through the argument that the visionary climate, support for experimentation, and tolerance for mistakes fostered by entrepreneurial leaders may function as a strong and inclusive organizational resource that compensates for individual deficiencies in psychological resilience. The findings were discussed in light of the relevant literature, the limitations of the study were addressed, and several recommendations were presented for future researchers, organizations, and practitioners.
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İpek Mikrotaşıyıcı Destekli Biyoreaktörlerde Göbek Kordonu Mezenkimal Kök Hücre Kültürasyonu
(Fen Bilimleri Enstitüsü, 2025) Yolalan Gizem; Biyomühendislik
Mesenchymal stem cells (MSCs) play a significant role in tissue engineering and regenerative medicine due to their ability to differentiate into specialized cell types such as osteoblasts, chondrocytes, myocytes, and adipocytes under specific environmental conditions. MSCs can be isolated from many tissues in the body, primarily bone marrow, adipose tissue, and umbilical cord. Depending on their source of isolation, MSCs exhibit characteristic differences and are mainly used in clinical studies related to inflammation, wound healing, infection, and various degenerative diseases affecting organs and tissues. Umbilical cord-derived mesenchymal stem cells (UC-MSCs) are increasingly used in the field of tissue engineering due to their ability to maintain in vitro differentiation potential over extended periods compared to other adult MSCs, their low immunogenic response, and non-tumorigenic nature. Large-scale cell production is required for the clinical use of UC-MSCs. For this purpose, microcarrier-supported bioreactor systems have been developed. In these systems, microcarriers produced using polymers with appropriate properties based on the needs of the culture are utilized. Within the scope of this thesis, silk fibroin (SF) polymer was selected for microcarrier production due to its biocompatibility, biodegradability, and favorable mechanical properties. The emulsified phase separation method was used for the production of microcarriers. Using this method, four different SF concentrations—2.5%, 3.5%, 4.5%, and 5.5% (w/v) were used to fabricate the microcarriers. As part of the characterization, size measurements showed that the diameters of 2.5%, 3.5%, 4.5%, and 5.5% SF microcarriers were 277 µm, 213 µm, 226 µm, and 234 µm, respectively. In terms of surface roughness, no surface irregularities were observed in the 2.5% SF microcarriers, while the 3.5% SF group exhibited significantly rough surfaces. Static culture was performed using the produced microcarriers. MTT analysis showed that the absorbance values on day 7 for 2.5%, 3.5%, and 4.5% SF microcarriers were similar, whereas the lowest absorbance value was recorded for the 5.5% SF group. To evaluate the effect of surface topography on UC-MSC attachment and proliferation, dynamic culture studies were conducted using 2.5% and 3.5% SF microcarriers. The 3.5% SF microcarriers demonstrated more homogeneous cell distribution under dynamic conditions. MTT analysis revealed that absorbance values obtained with 3.5% SF microcarriers on days 3 and 7 were approximately six times higher than those of 2.5% SF microcarriers. Flow cytometry analyses conducted following static and dynamic cultures confirmed that the cells proliferating on the surface of the microcarriers retained their stem cell characteristics after being removed from the surface. This study is the first to investigate the effect of entirely natural silk fibroin-based microcarriers, produced without the use of any coating or additional materials such as collagen or gelatin, on the proliferation of UC-MSCs under dynamic culture conditions.
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Üç Boyutlu (3B) Ortamda Oluşturulan Meme Kanseri Sferoidlerinde Abemaciclibin Etkisinin Araştırılması
(Fen Bilimleri Enstitüsü, 2025) Sürücüoğlu, Can; Biyoloji
Cancer remains one of the most prevalent and lethal diseases worldwide. Breast cancer—the most common malignancy in women—also ranks first in cancer-related mortality. Among its subtypes, triple-negative breast cancer (TNBC) stands out for its pronounced aggressiveness, metastatic potential, and poor prognosis. Inhibiting serine/threonine kinases has emerged as an innovative drug-development strategy; in this context, Abemaciclib, a selective cyclin-dependent kinase 4/6 (CDK-4/6) inhibitor, halts the cell cycle and can curb the uncontrolled proliferation of tumour cells. Because ethical constraints limit human studies and animal models do not fully recapitulate human physiology, three-dimensional (3D) cell-culture systems that better mimic tumour tissue are gaining importance. Spheroids—3D aggregates formed by self-organization of cells in a scaffold-free environment—are now widely used to elucidate oncogenic mechanisms and to improve drug screening. In this thesis, spheroids of the triple-negative breast cancer (TNBC) cell line MDA-MB-231 were generated using the 3D Petri Dish® method. The effects of Abemaciclib, a selective CDK-4/6 inhibitor, were then compared with those of the positive control Doxorubicin. Abemaciclib was applied at 10, 20 and 25 µM, while Doxorubicin was administered at 5, 10 and 20 µM, and the cytotoxic effects of the drugs against the cells were measured with 3-(4,5-dimethylthiazol-2-yl)-5-(3 carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium (MTS) assay. Immunofluorescence staining for E-cadherin and filamentous actin (F-actin) was performed to assess changes in the cytoskeleton and cell–cell junctions. Finally, cellular death pathways were explored by analyzing the cell cycle via flow cytometry. The results showed that 3D spheroids exhibited greater resistance to Abemaciclib than conventional two-dimensional (2D) cultures. F-actin staining confirmed structural changes in the cytoskeleton and intercellular contacts, while E-cadherin expression was absent, reflecting the diminished expression of this junctional protein. Cell-cycle analysis revealed that Abemaciclib reduced uncontrolled proliferation of MDA-MB-231 cells by arresting them in both G0/G1 and G2/M phases in a dose-dependent manner. Overall, this study demonstrates that 3D cell-culture models provide a more realistic platform for evaluating drug responses in aggressive cancers such as TNBC and highlights Abemaciclib as a promising therapeutic candidate for TNBC.