Damak Yarıklarının İn Situ Doku Mühendisliği ile Onarımı: Alveolar Yarık Hayvan Modeli Oluşturulması ve Farklı Rejimlerde Biyobozunur Doku Iskeleleri ile Onarımı

In this study, the tricalcium phosphate polymer, a tissue scaffold known for its direct effects on tissue healing, and that is used commonly in bone defect models, was upgraded by adding collagen by the Hacettepe University Department of Bioengineering. This study aims to compare this new enriched tissue scaffold with the standard tissue scaffold (ɛ-kaprolakton) and autogeneous bone grafting, which is the gold standard in alveolar cleft treatment. In this study, 64 animals were used, 48 for histological and radiological analyses, and 16 for gene expression studies. Regardless of groups, a bone defect of critical size (7x4x3 mm) was created, as formerly defined. The subjects in 8 different groups were examined in 2 different time intervals (4 groupx2, n= 48). In the negative control group, alveolar defect was created on the subjects, and no further procedures were performed. In the positive control group (the autograft group), the autograft harvested from the iliac bone of the subject was implanted on the deficient area. In the other two groups, the alveolar bone defects were reconstructed by the newly developed Collagen/ β-TCP and the standard ɛ-kaprolakton tissue scaffolds. The specimens gathered from the defective areas of the sacrificed animals were examined first macroscopically in the 1st and 4th months, then by micro-CT, in which the volume of the new bone tissue was calculated. When the micro-CT images were examined with respect to the volume of the newly formed bone, the autogenous graft group was found to have the best ossification on both histological and radiological analyses. Also, the amount of ossification on the 4th month was detected to be more than the amount of ossification on the 1st month. When the results of the Collagen/β-TCP group, the main component of this study, was analyzed, the increase in the rate of ossification was found to be statistically important, compared to the Standard tissue sacaffold group. This was also the group whose ossification results were closest to the autogenous graft group. For the histological examination, the specimens were stained with hematoxyllin, eosin and mason trichrome stains; and the blocks were examined for healing of the defect, new bone formation and tissue response. These data show that there is a quick healing in the autogenous graft group in the 1st and 4th months, and the Collagen/β-TCP group had the closest results in regard to the new bone formation. Likewise, in the gene expression studies, the best groups were the autograft and Collagen/β-TCP group. In conclusion, these data show that although the gold standard for treatment is autogenous bone grafting, tissue scaffolds developed through bioengineering can be regarded as an alternative when cost, donor area morbidity, and length of hospital stay are considered.Bu çalışmada, kemik iyileşmesi üzerine doğrudan etkileri olduğu bilinen ve kemik defektleri modellerinde sıkça kullanılan doku iskelesi modellerinden trikalsiyum fosfat polimeri Hacettepe Üniversitesi Biyomühendislik Bölümü laboratuarlarında üzerine kollojen eklenerek daha da kullanışlı hale getirildi. Bu geliştirilen doku iskelesi modelinin, diğer standart doku iskelesi (ɛ-kaprolakton) ve alveolar kemik defekti tedavisinde altın standart olan otogreft ile karşılaştırılması amaçlanmıştır. Çalışmada 48'i histolojik ve radyolojik analizlerde,16 taneside gen ifade düzeyi çalışmalarında kullanılmak üzere toplam 64 hayvan kullanılmıştır. Grup farketmeksizin hayvanların alveoler bölgesinde daha önce tanımlandığı üzere kritik boyutlu (7x4x3 mm)kemik defekti oluşturulmuştur. Toplam 8 grupta denekler 2 farklı zaman diliminde incelenmiştir. (4 grupx2,n=48) Negatif kontrol grubu olarak seçilen grupta alveol defekti oluşturulup denekler başka işleme maruz bırakılmamıştır. Pozitif kontrol grubu olan otogreft grubunda ise deneğin iliyak kemiğinden alınan otogreft hasarlı bölgeye implante edilmiştir. Diğer iki gruplarda alveolar kemik defektleri, asıl geliştirilen doku iskelesi modeli olan Kollajen/β-TCP ve standart doku iskelesi olan ɛ-kaprolakton ile rekonstrükte edilmiştir. 1. ve 4. aylarda sakrifiye edilen hayvanların defekt bölgelerinden alınan örnekler önce makroskopik olarak ve sonrasında mikro-CT analizleri yapılarak yeni kemik dokusunun hacimsel değeri hesaplanmıştır. Yapılan micro-CT incelemelerinde oluşan kemik hacmi bakımından Otogreft grubunda hem histolojik hem radyolojik analizlerde en iyi kemikleşmenin olduğu görülmüştür, ayrıca 4.ay gruplarındaki kemikleşme oranları 1.aylarındakilere göre daha fazla olarak saptanmıştır. Doku iskelesi olarak geliştirilen ve bu tez çalışmasının ana basamağını oluşturan Kollajen/β-TCP grubunun sonuçları analiz edildiğinde diğer doku iskelesi grubuna göre istatistiksel olarak anlamlı kemikleşme elde edilmiştir, Otogreft grubunada en yakın kemikleşme sonuçları elde edilmiştir. Örnekler micro-CT incelemeleri sonrasında histolojik incelemeye tabi tutulmuştur. Bu incelemelerde hematoksilin, eozin ve masson trikrom ile boyanmış, kesitler defekt iyileşmesi, yeni kemik oluşumu ve doku cevabı açısından değerlendirilmiştir. Histolojik çalışmalardan elde edilen veriler 1. ve 4. aylarda otogreft grubunda hızlı bir iyileşmenin olduğunu gösterirken Kollajen/β-TCP grubunun otogreft grubundaki yeni kemik oluşum değerlerine en yakın sonuçları verdiği saptanmıştır. Yine aynı şekilde gen ifade düzeyi çalışmalarında en iyi iki grubun otogreft ve Kollajen/β-TCP olduğu görülmüştür. Sonuç olarak elde edilen bu veriler ışığında altın standart tedavi yöntemi otojen kemik grefti olmasına karşın, doku mühendisliği ve yöntemleri ile geliştirilen doku iskeleleride maliyet, donör saha morbiditeleri, hastanede yatış süreleri düşünüldüğünde alternatif bir tedavi seçeneği olarak düşünülebilir

Experimental and numerical characterization of a mid-infrared plasmonic perfect absorber for dual-band enhanced vibrational spectroscopy

Plasmonic perfect absorbers (PPAs) have promising properties to be utilized in molecular sensing and spectroscopy applications such as surface enhanced infrared absorption (SEIRA) and surface enhanced Raman spectroscopy (SERS). In order to employ these properties and demonstrate the great potential of PPAs, investigation and demonstration of PPA designs and their sensing applications are highly needed. In this context, we present the design, optical characterization, experimental realization and dual-band sensing application of a subwavelength PPA array for infrared detection and surface enhanced spectroscopy applications. We analyze the PPA to investigate the absorption spectra and the fine-tuning mechanism through the parameter sweep simulations and experiments. In order to understand the absorption mechanism, we investigate the charge and current density distribution maps with electric and magnetic field enhancement effects. Additionally, we demonstrate the potential usage and reliability of the proposed PPA by presenting the experimental results of the dual-band detection of a conformal polymethyl methacrylate layer with nanometer-scale thickness atop the PPA. According to the experimental and simulation results of this study, the proposed PPA can be utilized in multiband molecular detection and high sensitive spectroscopy applications. (C) 2017 Elsevier B.V. All rights reserved

A Real-Time PHIL Implementation of a Novel Nonlinear Distributed Control Strategy for a Multi-Terminal DC Microgrid

Multi-terminal DC Microgrids have great potential for integrating Renewable Energy Sources, Storage Technologies, and modern loads more efficiently because most of them operate on DC power. Besides the reduced conversion steps between the components, which avoids considerable losses, multi-terminal DC MicroGrids offer advantages due to the lack of skin effects and reactive power. Nevertheless, stabilizing such a DC network by controlling its power converters is a very challenging task in view of the fact that the classical solution, to use PI controllers based on linearized models, may lead to stable behavior only in a small region around the respective equilibrium point. In this paper, we present a real-time PHIL implementation of a novel nonlinear control scheme for a multi-terminal DC MicroGrid. The amount of needed capacitors is reduced significantly concerning previous approaches. The proposed nonlinear controller is compared with a cascaded PI controller based on a linearized model, the socalled vector control. Both approaches, nonlinear and linear, are implemented and validated on a real PHIL multi-terminal DC MicroGrid consisting of a battery, a PV, and two load ports. The real-time experimental results of PI-based and nonlinear control-based DC Microgrids are then compared. They show that the nonlinear control allows to better deal with disturbances and nonlinearities of the system, for several points of operation without re-tuning

Metamaterial plasmonic absorber for reducing the spectral shift between near- and far-field responses in surface-enhanced spectroscopy applications

The spectral shift between near- and far-field responses of the plasmonic nanoantennas has negative effects on the performance of surface-enhanced spectroscopy measurements. In order to reduce these effects, we propose use of the plasmonic absorber (PA) concept that promises lower spectral-shift between the near- and far-field responses. In this context, we present the design, characterization and experimental realization of a novel PA structure which utilizes hexagonally arranged nanoantennas operating in the mid-infrared regime. Additionally, we analyze the PA device numerically and experimentally to investigate tunability of resonant modes. To reveal the absorption mechanism, we investigate the near-field distribution maps in addition to the charge and current density distributions. With the aim of comparing the proposed PA device with the conventional particle-based nanoantenna according to the amount of spectral shift between the near- and far-field peaks, we present the near- and far-field spectra of each configuration and show that PA structure exhibits significantly lower spectral-shift. Finally, we present the effect of reduced spectral-shift on the surface-enhanced infrared absorption spectroscopy through the simulations for the detection of the molecular absorption mode of a polymer and compare with the results of particle nanoantenna configuration. (C) 2017 Elsevier B.V. All rights reserved

An effective triple-band enhanced-infrared-absorption detection by honeycomb-shaped metamaterial-plasmonic absorber

Nowadays, accessing to new electromagnetic properties can be realized by fabricating metamaterials consist of artificial functional and subwavelength-scaled structures. Promoting artificial and functional metamaterial designs with large electromagnetic near-field enhancement especially over throughout multiband spectral range can provide critical contributions for infrared spectroscopy applications. In this context, the design and experimental realization of a photonic metamaterial are presented which can be utilized as an infrared biosensor. We utilize a honeycomb-shaped plasmonic nanoantenna for the design of the proposed novel absorber metamaterial. The fabrication and optical characterization of the structures are carried out and the sensor potential of the metamaterial is demonstrated through the detection of a polymer nanofilm. (C) 2019 Elsevier B.V. All rights reserved

Karamanlı Tartan ailesi ve Tartan Konağı hikayesi

Ankara : İhsan Doğramacı Bilkent Üniversitesi İktisadi, İdari ve Sosyal Bilimler Fakültesi, Tarih Bölümü, 2016.This work is a student project of the The Department of History, Faculty of Economics, Administrative and Social Sciences, İhsan Doğramacı Bilkent University.by Öztürk, İbrahim Mert