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Permanent URI for this collectionhttps://hdl.handle.net/20.500.14288/3
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Publication Metadata only Multiscale coupling based on quasicontinuum method in nanowires at finite temperatures(IEEE, 2015) Sonne, Mads Rostgaard; Hattel, Jesper Henri; N/A; Department of Mechanical Engineering; Esfahani, Mohammad Nasr; Alaca, Burhanettin Erdem; PhD Student; Faculty Member; Department of Mechanical Engineering; Graduate School of Sciences and Engineering; College of Engineering; N/A; 115108Nanoelectromechanical systems have been developed for ultra-high frequency oscillators because of their small size and excellent material properties. Using flexural modes and electrothermal features in nanowires for frequency tuning necessitates a sound modeling approach. The quasicontinuum method was developed to link atomistic models with the continuum finite element method in order to study the material behavior across multiple length scales. These significant efforts to develop a continuum theory based on atomistic models have so far been limited to zero temperature. The purpose of this work is to develop the theoretical framework needed to study the mechanical response in nanoscale components such as nanowires at finite temperatures. This is achieved up to a temperature of 1000 K by integrating Engineering Molecular Mechanics and the Cauchy-Born hypothesis. The proposed method is verified with Molecular Dynamics and Molecular Mechanics simulations reported in literature. Bending properties of nanowires at finite temperatures were studied with the proposed method. Thermomechanical properties were investigated by including surface effects.Publication Metadata only A novel magnetomechanical pump to actuate ferrofluids in minichannels(Begell House, Inc, 2011) Bilgin, Alp; Kurtoglu, Evrim; Erk, Hadi Cagdas; Sesen, Muhsincan; Kosar, Ali; Department of Chemistry; Acar, Havva Funda Yağcı; Faculty Member; Department of Chemistry; College of Sciences; 178902An improvement in the current methods of ferrofluid actuation was presented in this paper. A novel magnetomechanical microfluidic pump design was implemented with a ferrofluid as the active working fluid. Obtained flow rates were comparable to previous results in this research line. It was also seen that the basic pump architecture, which the subject pump is based on, enables much more room for further development.Publication Metadata only Challenges of the nose-to-brain route(Academic Press Ltd-Elsevier Science Ltd, 2017) Şekerdağ, Emine; PhD Student; Graduate School of Health Sciences; N/AThe main goal for investigating new techniques for brain drug delivery is to improve and/or elevate treatment outcomes. Targeted nose-to-brain delivery is a potential noninvasive drug delivery technique with many benefits, such as optimized drug distribution, reduced side effects, and improved patient compliance. Despite the fact that transport mechanism of drugs administered nasally are not fully understood, this pathway is still under investigation by many research groups to optimize the search for evidence and/or improve the direct nose-to-brain route. The most important challenges are translating study designs and obtaining data. Furthermore, the low drug uptake by the brain and environmental tissues in the nasal cavity is an issue that needs to be overcome by the utilization of nanotechnology-based techniques, which incorporate drugs in nanoparticles and or other drug delivery systems.Publication Metadata only Batch fabrication of self-assembled nickel-iron nanowires by electrodeposition(IEEE, 2006) N/A; Department of Electrical and Electronics Engineering; Department of Mechanical Engineering; Şardan, Özlem; Yalçınkaya, Arda Deniz; Alaca, Burhanettin Erdem; Master Student; Researcher; Faculty Member; Department of Electrical and Electronics Engineering; Department of Mechanical Engineering; Graduate School of Sciences and Engineering; College of Engineering; College of Engineering; N/A; 144523; 115108Lack of batch-compatible fabrication techniques can be considered as the most important challenge in the integration of nanostructures with microelectromechanical systems (MEMS). a solution to the micro-nano integration problem is offered by introducing a batch-compatible nanowire fabrication technique based on basic lithographic techniques and guided self-assembly. the basic principle is obtaining cracks at predetermined locations in a sacrificial SiO2 layer on Si and filling these cracks with a suitable metal by electrodeposition. the technique is demonstrated by using Nickel-Iron as the deposition material and verifying the magnetic behavior of resulting nanowires.Publication Metadata only Mechanically coupled comb drive MEMS stages(IEEE, 2008) Hedsten, Karin; Enoksson, Peter; Department of Electrical and Electronics Engineering; N/A; Department of Electrical and Electronics Engineering; N/A; Department of Electrical and Electronics Engineering; Arslan, Aslıhan; Ataman, Çağlar; Holmstrom, Sven; Seren, Hüseyin Rahmi; Ürey, Hakan; Researcher; PhD Student; Researcher; Master Student; Faculty Member; Department of Electrical and Electronics Engineering; College of Engineering; Graduate School of Sciences and Engineering; College of Engineering; Graduate School of Sciences and Engineering; College of Engineering; N/A; N/A; N/A; N/A; 8579An electrostatic large clear-aperture in-plane scanner with a novel actuation principle is presented for fast and large stroke scanning applications. 9 pm resonant deflection at 11.51 KHz with 100 Vpp excitation is observed.Publication Metadata only Development of highly stable and luminescent aqueous CdS quantum dots with the poly(acrylic acid)/mercaptoacetic acid binary coating system(Amer Scientific Publishers, 2009) Lieberwirth, I.; Department of Chemistry; N/A; Department of Chemical and Biological Engineering; Acar, Havva Funda Yağcı; Çelebi, Serdar; Serttunalı, Nazlı İpek; Faculty Member; Master Student; Undergraduate Student; Department of Chemistry; Department of Chemical and Biological Engineering; College of Sciences; Graduate School of Sciences and Engineering; College of Engineering; 178902; N/A; N/AHighly stable and luminescent CdS quantum dots (QD) were prepared in aqueous solutions via in situ capping of the crystals with the poly(acrylic acid) (PAA) and mercaptoacetic acid (MAA) binary mixtures. The effect of reaction temperature and coating composition on the particle size, colloidal stability and luminescence were investigated and discussed in detail. CdS QDs coated with either PAA or MAA were also prepared and compared in terms of properties. CdS-MAA QDs were highly luminescent but increasing reaction temperature caused an increase in the crystal size and a significant decrease in the quantum yield (QY). Although less luminescent and bigger than CdS-MAA, CdS-PAA QDs maintained the room temperature size and QY at higher reaction temperatures. CdS-MAA QDs lacked long term colloidal stability whereas CdS-PAA QDs showed excellent stability over a year. Use of PAA/MAA mixture as a coating for CdS nanoparticles during the synthesis provided excellent stability, high QY and ability to tune the size and the color of the emission. Combination of all of these properties can be achieved only with the mixed coating. CdS coated with PAA/MAA at 40/60 ratio displayed the highest QY (50% of Rhodamine B) among the other compositions.Publication Metadata only Recent technological developments in the diagnosis and treatment of cerebral edema(Wiley-V C H Verlag Gmbh, 2021) Deshmukh, Karthikeya P.; Jiang, Nan; Yetişen, Ali K.; N/A; Department of Mechanical Engineering; Dabbagh, Sajjad Rahmani; Taşoğlu, Savaş; N/A; Faculty Member; Department of Mechanical Engineering; Graduate School of Sciences and Engineering; College of Engineering; N/A; 291971Latest technological advancements in neurocritical care have translated to improved clinical outcomes and have paved the way for the effective diagnosis and treatment of cerebral edema. Effective management of cerebral edema has the potential to provide a personalized treatment by obtaining the complete pathophysiological information of the patient. The aims of this review are to inform the reader about the research and development in this field in the past decade as well as the materialization of scientific literature through patents. There is a growing interest in multimodal monitoring of the diseased brain as it provides a necessary means to implement effective intervention strategies. Although there is a gradual shift toward the adoption of noninvasive devices for research purposes, their clinical applications are hindered by their inaccuracies. However, the inherent risk of complication and high costs of implementation challenge the status quo. The role of neuroprotectants is explored and the combination of neurodiagnostic and neuroprotective approaches is proposed. Finally, the impacts of the current state of global affairs are discussed and it is predicted that the rising number of traumatic brain injury patents will inevitably translate to improvements in technologies to effectively address cerebral edema.Publication Metadata only Silicon microsphere based filtering application for near-infrared optical fiber based telecommunication(IEEE, 2011) Tamer, Mehmet Selman; Gurlu, Oguzhan; N/A; N/A; Department of Physics; Yılmaz, Huzeyfe; Gökay, Ulaş Sabahattin; Serpengüzel, Ali; Master Student; PhD Student; Faculty Member; Department of Physics; Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; College of Sciences; N/A; N/A; 27855We demonstrate an optical filter based on the resonances of a silicon microsphere in the near-IR O-Band. The 1300 nm laser light is coupled to the silicon microsphere and optical resonances are observed as dips in the transmission spectrum.Publication Metadata only Stroke(Academic Press Inc Elsevier Science, 2017) N/A; N/A; Çakmak, Özgür Öztop; Vanlı-Yavuz, Ebru Nur; Özdemir, Yasemin Gürsoy; Faculty Member; Doctor; Faculty Member; Koç University Research Center for Translational Medicine (KUTTAM) / Koç Üniversitesi Translasyonel Tıp Araştırma Merkezi (KUTTAM); School of Medicine; School of Medicine; School of Medicine; N/A; Koç University Hospital; N/A; 299358; 251177; 170592Stroke is a devastating neurological disease with a few therapeutic approaches. Despite the acute and prophylactic treatment options, novel effective treatments are required. The main limitation for effective treatment strategies to be developed is the presence of the blood–brain barrier. Targeted nanoparticulate treatment options may help to overcome this issue. This chapter deals with novel studies performed for targeted drug delivery technologies for stroke.Publication Metadata only Nasal physiology and drug transport(academic Press Ltd-Elsevier Science Ltd, 2017) Şekerdağ, Emine; PhD Student; Graduate School of Health Sciences; N/AOnce a compound enters the nasal cavity, it can be navigated along several pathways. There is a chance for a drug to be: (1) rapidly cleared by the mucociliary mechanism, (2) absorbed and reach the systemic circulation (lipophilic compounds mostly), and (3) absorbed by the olfactory epithelium and reach the olfactory bulb. When a drug compound is cleared away in the nasal cavity, it is degraded by enzymes in the nasal mucus, which therefore interrupts the drug delivery to the target zone. A drug compound can also enter the systemic circulation and may effectively reach the target area followed by elimination from the blood by clearance mechanisms present throughout the body. In case of the latter, to reach the brain the drug has to bypass the BBB, which is an obstacle for most hydrophilic and/or large compounds. Moreover, once the compound passes through the BBB into the brain it can still be eliminated from the CSF back into the blood circulation. Furthermore, a drug compound entering the nasal cavity can also pass through the olfactory epithelium and reach the olfactory bulb, which can transport the drug into the brain without facing the BBB.