Excitation-Induced Ge Quantum Dot Growth on Si(100)-2X1 by Pulsed Laser Deposition

Self-assembled Ge quantum dots (QD) are grown on Si(100)-(2×1) with laser excitation during growth processes by pulsed laser deposition (PLD). In situ reflection-high energy electron diffraction (RHEED) and post-deposition atomic force microscopy (AFM) are used to study the growth dynamics and morphology of the QDs. A Q-switched Nd:YAG laser (λ = 1064 nm, 40 ns pulse width, 5 J/cm2 fluence, and 10 Hz repetition rate) were used to ablate germanium and irradiate the silicon substrate. Ge QD formation on Si(100)-(2×1) with different substrate temperatures and excitation laser energy densities was studied. The excitation laser reduces the epitaxial growth temperature to 250 °C for a 22 ML film. In addition, applying the excitation laser to the substrate during the growth changes the QD morphology and density and improves the uniformity of quantum dots fabricated at 390 °C. At room temperature, applying the excitation laser during growth decreases the surface roughness although epitaxial growth could not be achieved. We have also studied the surface diffusion coefficient of Ge during pulsed laser deposition of Ge on Si(100)-(2×1) with different excitation laser energy densities. Applying the excitation laser to the substrate during the growth increases the surface diffusion coefficient, changes the QD morphology and density, and improves the size uniformity of the grown quantum dots. To study the effect of high intensity ultralast laser pulses, Ge quantum dots on Si(I00) were grown in an ultrahigh vacuum (UHV) chamber (base pressure ∼7.0x10 -10 Torr) by femtosecond pulsed laser deposition. The results show that excitation laser reduces the epitaxial growth temperature to ∼70 °C. This result could lead to nonthermal method to achieve low temperature epitaxy which limits the redistribution of impurities, reduces intermixing in heteroepitaxy, and restricts the generation of defects by thermal stress. We have ruled out thermal effects and some of the desorption models. Although further studies are needed to elucidate the mechanism involved, a purely electronic mechanism of enhanced surface diffusion of Ge atoms is proposed

STM Study of Pulsed Laser Assisted Growth of Ge Quantum Dot on Si(1 0 0)-(2 × 1)

Ge quantum dot formation on Si(1 0 0)-(2 × 1) by nanosecond pulsed laser deposition under laser excitation was investigated. Scanning tunneling microscopy was used to probe the growth mode and morphology. Excitation was performed during deposition using laser energy density of 25-100 mJ/cm 2. Faceted islands were achieved at a substrate temperature of ∼250 °C only when using laser excitation. The island morphology changes with increased laser excitation energy density although the faceting of the individual islands remains the same. The size of the major length of islands increases with the excitation laser energy density. A purely electronic mechanism of enhanced surface diffusion of the Ge adatoms is proposed. © 2014 EDP Sciences

Excitation-Induced Germanium Quantum Dot Formation on Si (100)-(2×1)

The effect of nanosecond pulsed laser excitation on the self-assembly of Ge quantum dots grown by pulsed laser deposition on Si (100)-(2×1) was studied. In situ reflection high-energy electron diffraction and ex situ atomic force microscopy were used to probe the quantum dot structure and morphology. At room temperature, applying the excitation laser decreased the surface roughness of the grown Ge film. With surface electronic excitation, crystalline Ge quantum dots were formed at 250 °C, a temperature too low for their formation without excitation. At a substrate temperature of 390 °C, electronic excitation during growth was found to improve the quantum dot crystalline quality, change their morphology, and decrease their size distribution almost by half. A purely electronic mechanism of enhanced surface hopping of the Ge adatoms is proposed. © 2010 American Institute of Physics. [doi:10.1063/1.3462436

Electronically Enhanced Surface Diffusion During Ge Growth on Si(100)

The effect of nanosecond pulsed laser excitation on surface diffusion during the growth of Ge on Si(100) at 250 °C was studied. In situ reflection high-energy electron diffraction was used to measure the surface diffusion coefficient while ex situ atomic force microscopy was used to probe the structure and morphology of the grown quantum dots. The results show that laser excitation of the substrate increases the surface diffusion during the growth of Ge on Si(100), changes the growth morphology, improves the crystalline structure of the grown quantum dots, and decreases their size distribution. A purely electronic mechanism of enhanced surface diffusion of the deposited Ge is proposed. © 2011 American Institute of Physics. [doi:10.1063/1.3567918

Low Temperature Epitaxial Growth of Ge Quantum Dot on Si (100) - (2×1) by Femtosecond Laser Excitation

Low temperature epitaxy of Ge quantum dots on Si (100) - (2×1) by femtosecond pulsed laser deposition under femtosecond laser excitation was investigated. Reflection high-energy electron diffraction and atomic force microscopy were used to analyze the growth mode and morphology. Epitaxial growth was achieved at ∼70 °C by using femtosecond laser excitation of the substrate. A purely electronic mechanism of enhanced surface diffusion of the Ge adatoms is proposed. © 2011 American Institute of Physics. [doi:10.1063/1.3537813

Faktor-faktor yang mempengaruhi remaja Lembah Klang untuk terus membaca dan membeli melalui pengiklanan Facebook

Facebook bukan sahaja menghubungkan individu atau komuniti, malah ia juga bertindak sebagai laman penting bagi industri pengiklanan untuk menjalankan urusan perniagaan secara global. Kajian ini melihat sejauhmanakah faktor-faktor kepuasan keperluan kognitif, kepuasan keperluan afektif, kepuasan keperluan peribadi integratif serta kepuasan keperluan sosial integratif mempengaruhi tahap penerimaan remaja yang berada pada lingkungan umur 18-24 tahun terhadap pengiklanan dalam Facebook. Model kajian dibentuk berdasarkan Teori Kegunaan dan Kepuasan oleh Elihu Katz, Michael Gurevitch & Jay G. Blumler (1973). Seramai 200 responden dipilih secara Purposive Sampling di sekitar Lembah Klang. Data dikumpulkan menerusi kaedah tinjauan menggunakan soal selidik. Hasil kajian ini menunjukkan pembelian produk untuk memenuhi tuntutan ego sendiri merupakan faktor kepuasan keperluan kognitif yang dapat mempengaruhi tahap penerimaan remaja terhadap pengiklanan Facebook. Selain itu, bagi aspek kepuasan keperluan afektif pula menunjukkan bahawa hanya ciri-ciri keistimewaan iaitu pelbagai aplikasi Facebook yang digunakan dalam pengiklanan Facebook dapat mempengaruhi tahap penerimaan remaja terhadap pengiklanan dalam Facebook. Bagi faktor kepuasan keperluan peribadi integratif pula iaitu ciri pengguna dan sikap berhati-hati terhadap perubahan didapati mempunyai hubungan secara langsung dengan tahap penerimaan pengiklanan Facebook. Dari segi sikap kepuasan keperluan sosial integratif, majoriti responden dalam kajian ini didapati adalah bersikap kolektivisme di mana ia dibuktikan mempengaruhi tahap penerimaan golongan remaja terhadap pengiklanan Facebook

Hutbelerdeki İslam iktisadı ile ilgili söylemlerin tahlili : İstanbul İli örneği (2001-2018)

06.03.2018 tarihli ve 30352 sayılı Resmi Gazetede yayımlanan “Yükseköğretim Kanunu İle Bazı Kanun Ve Kanun Hükmünde Kararnamelerde Değişiklik Yapılması Hakkında Kanun” ile 18.06.2018 tarihli “Lisansüstü Tezlerin Elektronik Ortamda Toplanması, Düzenlenmesi ve Erişime Açılmasına İlişkin Yönerge” gereğince tam metin erişime açılmıştır.Hicretten sonra Müslümanlara cuma namazı ibadetinin farz kılınmasıyla birlikte ilk olarak Hz. Peygamber tarafından başlatılan cuma hutbesi, Türkiye'de 1924 senesinden bugüne Diyanet İşleri Başkanlığı kontrolünde devam etmektedir. Ülke genelinde her cuma aynı hutbe okunmakta ve hutbeler aracılığıyla farklı toplumsal sınıflardan milyonlarca insana ulaşılmaktadır. Bu sebeple hutbe esnasında gündeme alınan her bir konu ve söylenen her bir cümle ayrı ayrı önem taşımaktadır. Literatüre bakıldığında hutbeler üzerine sınırlı sayıda çalışma yapılmış olmakla birlikte hutbelerde İslam iktisadı üzerine yapılmış bir çalışma bulunmamaktadır. Öncelikli olarak bu çalışmamızda, hutbenin kavramsal bir çerçevesi çizilerek tanımlaması yapılmış ve İslam dinindeki yeri belirtilerek tarihi süreci aktarılmıştır. Ardından ise günümüz Diyanet İşleri Başkanlığının hutbe hizmetleri üzerinde durulmuş ve son bölümde ise 2001-2018 yılları arasında İstanbul ilinde irâd edilen hutbelerde İslam iktisadına ilişkin hangi kavramların konu edildiği, ne sıklıklarla kullanıldığı ve nasıl bir içerik ile sunulduğu incelenmiştir. Ayrıca bu çalışmamız ile hutbeler üzerine alansal bir inceleme yapılmış ve hutbeler aracılığıyla günümüz Türkiye'sinde İslam iktisadı değerlerinin ele alınışı incelenmiştir. Yapılan analiz neticesinde ise ilgili dönemde İslam iktisadıyla ilişkili farklı alanlara yönelik kavramlara çok sık olmasa da hutbelerde yer verildiği görülmektedir. Bu kavramlar arasından özellikle sadaka, infak ve zekât gibi daha çok karşılıksız maddi destek vermeye ilişkin kavramların tercih edildiği ve bu kavramların da özellikle Ramazan aylarında hutbelerde konu edildiği tespit edilmiştir. Bununla birlikte kapitalist sistemin temel dinamikleri olan ve İslam dininde çok sert biçimde yasaklanan faiz gibi kavramlardan ise neredeyse hiç bahsedilmediği görülmektedir. Bu bağlamda çalışmamızın sonuç bölümünde ise ilgili hutbelerdeki eksiklikler belirtilerek çözüm önerileri sunulmuş ve ayrıca İslam iktisadının toplumda daha çok yaygınlık kazanmasının hutbeler yoluyla nasıl gerçekleştirilebileceğine değinilmiştir.After hejira, together with its' obligation for Muslims, for the first time initiated by Hz. Muhammed the prophet of Islam, Friday Pray has been carried out under control of the Ministry of Religious Affairs since 1924. Every Friday, throughout the country, the same khutba is read and through the khutbas, millions of people from different classes are reached. For this reason, any subject, even any sentence mentioned during the khutba is important. A limited number of studies have been conducted on khutbas but there is no study on Islamic economics in sermons. In this study, firstly, a conceptual framework of the sermon was defined and its historical process was conveyed by stating its importance in the Islamic world. Secondly, the ministry of religious affairs was focused on the services of the khutba. Finally, the khutbas, which were read in Istanbul between the years of 2001-2018, were examined in terms of the concepts related to Islamic economics, how frequently they were used and how they were presented. As a result of analysis performed, although very often associated with the concept for different areas of Islamic economics in the relevant period it has been given in different khutba. The concepts for giving more unrequited financial support such as zakat and charity were transferred to the community during Ramadan, especially in the khutbas. However, there is hardly any mention of the fundamental dynamics of the dominant system, such as interest which is banned in Islam. A study on spatial khutbas made by this study, dealing with the economic value of Islam in the today's TURKEY, were examined through khutbas. In addition, shortcomings have been stated and suggestions have been presented by raising awareness about how Islamic economics can become more known and widespread in the society through the khutbas

Determınatıon of toxıcıty of gaseous ozone agaınst adult stages of German Cockroach (Blatella germanıca L.): Poster

In this study, the effects of two different concentrations of ozone gas (16.7 and 33.3 mg / L) against Blatella germanica adults at different exposure times (10, 20, 30, 40 and 50 minutes) were investigated under laboratory conditions. It was determined that the ozone gas had a noticeable effect on mortality of B. germanica adults. In general, ozone gas caused higher paralyisis-mortality rates of B. germanica adults than mortality rates of B.germanica adults at both concentrations and all exposure times. A concentration of 33.3 mg / L of ozone gas with 40 and 50 minute exposure times killed all cockroach adults after 24 hours. On the other hand, 16.7 mg / L concentration of ozone gas with 50 minute exposure time killed 90% of the B. germanica adults after 24 hours. When ozone gas is evaluated in terms of exposure time to B. germanica adults, the concentration of 33.3 mg / L of ozone gas with 10-20 minute exposure times caused 65 % adult mortality, with 30 minute exposure time caused 90% adult mortality and with 50 minute exposure times caused 100 % adult mortality after 24 hours. At a concentration of 16.7 mg / L of ozone gas, as the exposure times increased, the adult mortalities gradually increased after 24 hours and the adult mortality reached 90% with 50 minute exposure times. All these results show that ozone gas (33.3 mg / L) with 40-50 minute exposure times can successfully control B.germanica adults.In this study, the effects of two different concentrations of ozone gas (16.7 and 33.3 mg / L) against Blatella germanica adults at different exposure times (10, 20, 30, 40 and 50 minutes) were investigated under laboratory conditions. It was determined that the ozone gas had a noticeable effect on mortality of B. germanica adults. In general, ozone gas caused higher paralyisis-mortality rates of B. germanica adults than mortality rates of B.germanica adults at both concentrations and all exposure times. A concentration of 33.3 mg / L of ozone gas with 40 and 50 minute exposure times killed all cockroach adults after 24 hours. On the other hand, 16.7 mg / L concentration of ozone gas with 50 minute exposure time killed 90% of the B. germanica adults after 24 hours. When ozone gas is evaluated in terms of exposure time to B. germanica adults, the concentration of 33.3 mg / L of ozone gas with 10-20 minute exposure times caused 65 % adult mortality, with 30 minute exposure time caused 90% adult mortality and with 50 minute exposure times caused 100 % adult mortality after 24 hours. At a concentration of 16.7 mg / L of ozone gas, as the exposure times increased, the adult mortalities gradually increased after 24 hours and the adult mortality reached 90% with 50 minute exposure times. All these results show that ozone gas (33.3 mg / L) with 40-50 minute exposure times can successfully control B.germanica adults

Lethal effect of Turkish diatomaceous earth (Bgn-1 ) agaınst adults of German cockroaches (Blatella germanıca L.): Presentation

In this study, mortality effects of BGN-1 which is local diatomaceous earths, were investigated against adults of German cockroach (Blatella gemanica (L.)) on concrete, ceramic floor tile and laminate flooring. On these three different surfaces, B. germanica adults were exposed to BGN-1 diatomaceous earth at the doses of 2.5, 5, 10, 20 g/m2 along 6 days. In all surface applications of BGN-1 diatomaceous earth, exposure time and dose caused significant effect on mortality rates of B. germanica adults. It was determined that BGN-1 coded Turkish diatomaceous earth has the lowest mortality effect on all application surfaces at the dose of 2.5 g/m2. 2.5 g/m2 BGN-1 caused 100 % mortality after 6 days concrete surface and caused 100 % mortality at the end of the fourth day on ceramic floor tile and laminate flooring. On the other hand, doses of 5 and 10 g/m2 of BGN-1 caused 100% B. germanica mortality on all surfaces at the end of the second day, while the highest dose of 20 g /m2 of BGN-1 reached 100% B. germanica mortality at the end of the first day on all application surfaces. In general, the mortality activity of BGN-1 diatomites against B. germanica adults was found to be similar on all three surfaces. At the end of this study, local diatomaceous earth coded BGN-1 was found to be good alternatives for controlling B. germanica which is a medical pest insect

Naturally existing Beauveria on the surface of stored wheat kernels, and their pathogenicity on Rhyzopertha dominica and Sitophilus oryzae adults: Poster

Entomopathogenic fungi have been investigated to control stored product pests, as an alternative strategy to chemical insecticides. Although many studies evaluated isolates from various sources, few studies surveyed fungi naturally infecting stored product pests, revealing predominantly Beauveria isolates. This study aimed to reveal the amount of Beauveria carried on the surface of stored wheat kernels, and their pathogenicity against Rhyzopertha dominica and Sitophilus oryzae adults. Sixteen wheat samples from different storage facilities in four cities were examined for existence of Beauveria. One-hundred g of wheat was washed in 100 mL of 2% Tween80 solution. After increasing concentration of possible fungi by centrifugation, the liquid was spread on medium with dodine and monitored at 25±2°C. Nine of the isolates were tested for pathogenicity at 500 ppm (w/w) at 25±2°C, 65±5% r.h. in darkness with five replicates. While only four samples did not have Beauveria, others had 17-2992 cfu/100 g wheat. Six samples had 17-50, four samples 150-858, one sample 1625 and one had 2992 cfu/100 g wheat. Mortalities against R. dominica adults ranged between 5-86% and 32-100% in 7 and 14 days, respectively. Mortality of S. oryzae ranged from 3-45% and 8-83% in 7 and 14 days, respectively. This study demonstrated that wheat kernels can naturally carry Beauveria with various levels of pathogenicity. Potential naturally occurring entomopathogenic fungi can be isolated directly from stored commodities to be evaluated as biological control agents for stored product pest control.Entomopathogenic fungi have been investigated to control stored product pests, as an alternative strategy to chemical insecticides. Although many studies evaluated isolates from various sources, few studies surveyed fungi naturally infecting stored product pests, revealing predominantly Beauveria isolates. This study aimed to reveal the amount of Beauveria carried on the surface of stored wheat kernels, and their pathogenicity against Rhyzopertha dominica and Sitophilus oryzae adults. Sixteen wheat samples from different storage facilities in four cities were examined for existence of Beauveria. One-hundred g of wheat was washed in 100 mL of 2% Tween80 solution. After increasing concentration of possible fungi by centrifugation, the liquid was spread on medium with dodine and monitored at 25±2°C. Nine of the isolates were tested for pathogenicity at 500 ppm (w/w) at 25±2°C, 65±5% r.h. in darkness with five replicates. While only four samples did not have Beauveria, others had 17-2992 cfu/100 g wheat. Six samples had 17-50, four samples 150-858, one sample 1625 and one had 2992 cfu/100 g wheat. Mortalities against R. dominica adults ranged between 5-86% and 32-100% in 7 and 14 days, respectively. Mortality of S. oryzae ranged from 3-45% and 8-83% in 7 and 14 days, respectively. This study demonstrated that wheat kernels can naturally carry Beauveria with various levels of pathogenicity. Potential naturally occurring entomopathogenic fungi can be isolated directly from stored commodities to be evaluated as biological control agents for stored product pest control