Structure and Light Emission in Germanium Nanoparticles

PhDIn this study, advanced techniques in the synthesis of germanium nanoparticles have been investigated. Based on physical and chemical production methods, including stain etching, liquid-phase pulsed laser ablation, sol-gel synthesis and two benchtop colloidal synthesis techniques, germanium nanoparticles with various surface terminations were formed. Out of those, colloidal synthesis by benchtop chemistry (named CS1) were found to be the most promising synthesis route in terms of yield and stability of the as-prepared Ge qdots and its luminescence with almost no oxides present. For the characterisation of Ge nanoparticles, Raman spectroscopy, Photoluminescence (PL) spectroscopy, Transmission electron microscopy (TEM) with energy dispersive X-ray spectroscopy (EDX) and selective area electron diffraction (SAED) techniques were utilised before conducting X-ray absorption spectroscopy (XAS) measurements. The structure and morphology of Ge quantum dots formed using colloidal synthesis routes were found to fit best to the model of a nanocrystalline core surrounded by disordered Ge layers. Optically-detected X-ray absorption studies have enabled us to establish a direct link between nanoparticles structure and the source of the luminescence. The most important outcome of this study is that it provides a direct experimental route linking synthesis conditions and properties of nanosized Ge quantum dots. Furthermore, using annealing, we can control surface termination even further, as well as change particle size and possibly produce metastable phases.School of Physics and Astronomy, Queen Mary University of Londo

Structure and effects of annealing in colloidal matrix-free Ge quantum dots

This research was supported by Queen Mary, University of London. We would like to thank Diamond synchrotron light source for the beamline (B18) and the corporation work. AK and OE acknowledge the Turkish Ministry of National Education. WL is grateful to the South East Physics Network (SEPnet). YZ was supported by Chinese Scholarship Council (CSC) for PhD study

Local structure of amorphous and nanoscale systems by numerical XANES calculations

EPSRC grant EP/K000128/1

Synthesis and structure of free-standing germanium quantum dots and their application in live cell imaging

Free-standing Ge quantum dots around 3 nm in size were synthesized using a bench-top colloidal method and suspended in water and ethanol. In the ethanol solution, the photoluminescence of the Ge quantum dots was observed between 650 and 800 nm. Structural and optical properties of these colloidal Ge quantum dots were investigated by utilizing X-ray diffraction, X-ray absorption spectroscopy, Raman spectroscopy, and photoluminescence spectroscopy and transmission electron microscopy. The structure of the as-prepared Ge quantum dots that were found is best described by a core-shell model with a small crystalline core and an amorphous outer shell with a surface that was terminated by hydrogen-related species. As-prepared Ge quantum dots were suspended in cell growth medium, and then loaded into cervical carcinoma (HeLa) cells. The fluorescent microscopy images were then collected using 405 nm, 488 nm, 561 nm and 647 nm wavelengths. We observed that, based on fluorescence measurements, as-prepared Ge quantum dots can remain stable for up to 4 weeks in water. Investigation of toxicity, based on a viability test, of as-prepared uncoated Ge quantum dots in HeLa cells was carried out and compared with the commercial carboxyl coated CdSe/ZnSe quantum dots. The viability tests show that Ge quantum dots are less toxic when compared to commercial carboxyl coated CdSe/ZnS quantum dots. This journal i

Spectroscopic super-resolution fluorescence cell imaging using ultra-small Ge quantum dots

QMUL/CSC scholarship (2011611045); BBSRC grant (BB/J001473/1)

Pressure-Induced Amorphization and a New High Density Amorphous Metallic Phase in Matrix-Free Ge Nanoparticles.

Over the last two decades, it has been demonstrated that size effects have significant consequences for the atomic arrangements and phase behavior of matter under extreme pressure. Furthermore, it has been shown that an understanding of how size affects critical pressure-temperature conditions provides vital guidance in the search for materials with novel properties. Here, we report on the remarkable behavior of small (under ~5 nm) matrix-free Ge nanoparticles under hydrostatic compression that is drastically different from both larger nanoparticles and bulk Ge. We discover that the application of pressure drives surface-induced amorphization leading to Ge-Ge bond overcompression and eventually to a polyamorphic semiconductor-to-metal transformation. A combination of spectroscopic techniques together with ab initio simulations were employed to reveal the details of the transformation mechanism into a new high density phase-amorphous metallic Ge

Türkiye'deki İtfaiyelerin Afete Hazırlıklarının Değerlendirilmesi

Karatutlu C., Evaluation of the Disaster Preparedness of the Fire Brigades in Turkey, Hacettepe University Graduate School of Health Sciences, Department of Public Health, Health Management In Disasters Program Master’s Thesis, Ankara 2021. The aim of the study is to examine the disaster preparedness of fire departments affiliated with the fire brigades of metropolitan, provincial, district and town municipalities in Turkey. The universe of this study includes the fire departments of the metropolitan municipalities and the fire brigades of the provincial, district and town municipalities in Turkey and it was tried to reach all of the universe of the study. This is a cross-sectional epidemiological study. The questionnaires were sent via ordinary mail. Within the scope of the survey, 74.7% of the fire brigades were reached. Population of the area of responsibility of fire brigades participating in the research study makes up 83.3 % (69,240,155) of the population of Turkey, and the surface area of the area of responsibility of fire brigades makes up 78.6% (612,735 km2) of the surface area of Turkey. 26.9% of the fire brigades participating in the survey stated that their preparedness in the units for disasters is sufficient and 30.6% of them stated that personnel working in disasters and fires are at a sufficient level. 50.0% of the fire brigades participating in the study stated that their units have internal service instructions, 42.1% have an internal disaster plan in their units, and 23.4% have an external disaster plan in their units. The average point value of the disaster preparedness of the fire brigades involved in the study is 20,3; the standard deviation is 14,4; the median value is 17.Karatutlu C., Türkiye’deki İtfaiyelerin Afete Hazırlıklarının Değerlendirilmesi, Hacettepe Üniversitesi Sağlık Bilimleri Enstitüsü Halk Sağlığı Anabilim Dalı Afetlerde Sağlık Yönetimi Programı Yüksek Lisans Tezi, Ankara 2021. Bu çalışmada Türkiye’de il, ilçe ve belde belediyelerine ve büyükşehir belediyesi itfaiye daire başkanlıklarına bağlı itfaiye birimlerinin afete hazırlık durumunun incelenmesi amaçlanmaktadır. Türkiye’ deki büyükşehir belediyelerine bağlı itfaiye daire başkanlıkları, il, ilçe ve belde belediyelerine bağlı itfaiye birimleri araştırmanın evrenini oluşturmaktadır ve tamamına ulaşılmaya çalışılmıştır. Araştırma kesitsel tipte epidemiyolojik bir araştırmadır. Araştırmada mektup ile anket uygulama yöntemi kullanılmıştır. Araştırma kapsamında itfaiye birimlerinin %74,7’sine ulaşılmıştır. Araştırmaya katılan itfaiye birimlerinin sorumluluk alanı nüfusu, Türkiye nüfusunun %83,3’ünü (69.240.155), itfaiye birimlerinin sorumluluk alanı yüz ölçümü, Türkiye yüz ölçümünün %78,6’sını (612.735 km2) oluşturmaktadır. Araştırmaya katılan itfaiye birimlerinin %26,9’u birimlerinin afetlere müdahale etme durumlarının ve %30,6’sı afet ve yangınlarda görev yapacak personelin yeterli düzeyde olduğunu belirtmiştir. Araştırmaya katılan itfaiye birimlerinin %50,0’ı birimlerinde iç hizmet yönergesinin olduğunu, %42,1’i birimlerinde iç afet planının bulunduğunu, %23,4’ü birimlerinde dış afet planının bulunduğunu belirtmiştir. Araştırmaya katılan itfaiye biriminin afete hazırlık puanlarının ortalama değeri 20,3, standart sapması 14,4, ortanca değeri ise 17’dir

The Effect Of The Foreıgn Dırect Investment On Mıddle East And North Afrıcan Countrıes (Mena): An Emprıcal Study

Bu tezin amacı Doğrudan Yabancı Yatırımların Ortadoğu-Kuzey Afrika Ülkeleri (MENA) Üzerine Etkisini; 1995–2014 yılları arasında zaman seri analizi ve OLS yöntemi ile incelemektir. Tezin birinci bölümünde Doğrudan Yabancı Yatırımların tanımları, tarihçesi, önemi ve massetme kapasitesinin tanımı, büyüme üzerine etkisi incelenirken ikinci bölümde MENA ülkelerinin ekonomik-sosyal yapıları ve DYY’lerin ekonomik büyüme üzerine etkilerine yer verilmiş olup, üçüncü bölümde de literatür taraması incelenmiştir. Dördüncü bölümde ise MENA ülkeleri için tek tek zaman serileri oluşturularak OLS yöntemi ile ampirik çalışma yapılmıştır. Analiz sonuçlarında MENA ülkeleri belirli bir massetme kapasitesine sahip ise DYY’ler ekonomik büyüme üzerinde olumlu etkiye sahiptir. Massetme kapasitesine sahip olmayan ülkelerde DYY’ler ekonomik büyüme üzerinde olumsuz etkiye sahip olduğu sonuca ulaşılmıştır.The purpose of this thesis is to analyse the effect of the effect of the foreign investment on Middle East and North African countries (MENA) between 1995-2014 by time series analysis and OLS method. In first chapter of the thesis, history, importance and the definitions of foreign direct investment have been mentioned. In the second chapter, the definition of absorptive capacity and its effects on development have been dwelled on, and in the third chapter, the economic and social structures of MENA countries and the effect of FDY on the economic development have been mentioned. In the fourth chapter, literature has been reviewed. In the fifth chapter, an empirical study has been used with OLS method by creating time-series for each MENA countries. If the MENA countries have the capacity to absorb certain FDI’s has a positive effect on economic growth. In countries that do not have the capacity to absorb FDI it has reached the conclusion that they have a negative effect on economic growth