Bor nitrür üretimi

TÜBİTAK MAG15.04.2008Bor nitrür, grafite çok benzer altıgen (h-BN) yapıda tabakalar halinde veya kübik yapıda (k- BN) elmasa çok yakın özelliklerde bulunabilir. k-BN bilinen malzemeler içinde elmastan sonra en sert olduğundan malzeme endüstrisinde sert metal kaplamalar yapmada (elmastan daha üstün özelliklerde, metal işlemede) kullanılmaktadır. Ayrıca, elmas sadece p-türü katkılanabildiği halde, k-BN hem p hem de n türü katkılanabilmektedir, ve dolayısıyla elektronik devrelerin yapı taşı olan p-n eklemini üretmek olası olduğundan mor-mavi ışık bölgesinde ışık algılayıcısı (detektör) ve yayınlayıcısı (LED) uygulamasına açıktır. k-BN tabanlı bu devre elemanlarının, opto-elektronik yatkınlıkları yanında, elmastan daha yüksek bir yasak enerji aralığına sahip olmalarından dolayı çok daha yüksek sıcaklık ortamlarında kullanılmalarını sağlanabilir. Son yıllarda yapılan araştırmalar k-BN’nin plazma ortamında Fiziksel Buhar Biriktirme (FBB) veya Kimyasal Buhar Biriktirme (KBB) yöntemleri ile üretilebileceğini göstermiştir. Ancak bu çalışmalar biriktirilen maddenin özelliklerine (k-BN içeriği ve mekanik gerilim) ve birikme hızına etki eden üretim parametrelerinin (kullanılan bor ve azot kaynakları, kullanılan gaz kompozisyonu, kaplanan yüzeyi oluşturan madde(taban), uygulanan plazma yoğunluğu, RF gücü, bias voltaj, taban sıcaklığı) nasıl etki ettiğini sistematik bir yaklaşımla incelememiştir. Elde, çevre birimleriyle birlikte, kurulu bulunan hem FBB, hem de KBB düzenekleriyle (yapılabilir bazı değişiklikler ve eklerle), yukarıda sözü edilen sistematik çalışma olanaklar çerçevesinde gerçekleştirilmiştir. Başka bir deyişle hem RF hem de MW kullanan KBB ve magnetron çığlama kullanan KBB teknikleriyle büyütülen filmler, eldeki ve proje bütçesiyle sağlanan olan ölçüm/test düzenekleriyle çözümlenmiştir. Böylece üretim test döngüsü yinelenerek hedeflenen mekanik ve opto-elektronik özellikte k-BN ince filmleri ve ondan üretilebilecek yapıları oluşturan en uygun üretim koşulları belirlenmeye çalışılmıştır.Boron nitride can be found in hexagonal structure (hBN) which is very much like graphite or in cubic structure with properties very close to those of diamond. Since cBN is the hardest known material after diamond is used in making hard metal covers (used in metal machining with superior properties to diamond). In addition, while diamond can be doped only in p type both p and n type doping is possible in cBN, therefore cBN can be used to make p-n junction which is a basic part of the microelectronic circuits. That means cBN can be used to make a detector or Light Emitting Diode (LED) in violet-blue region. In addition to these optoelectronic properties, cBN based circuit parts are expected to withstand very high temperatures due to the higher forbidden energy gap of cBN compared to that of diamond. Recent studies have shown that cBN can be produced by Physical Vapor Deposition (PVD) and Chemical Vapor Deposition (CVD) in plasma. But these studies have failed to determine) how all of the production parameters (boron and nitrogen sources, composition of the gas used, the material covered (substrate), plasma density, RF power, bias voltage, substrate temperature) affect on the properties (cBN content and mechanical stresses) and the deposition rate of the product with a systematic approach. The systematic study was realized in the range of available experimental ability of the present PVD and CVD equipment and accessories with some possible additions and changes. The cBN films were produced in the plasma equipment and was studied with the measurement and testing facilities that already exist in addition to measurement and testing equipment acquired within the budget of this project. The optimum production conditions of cBN with desired mechanical and optoelectronic properties were studied experimentally

Comparison of muscle activation level, pain, posture, disability, and balance in individuals with and without temporomandibular joint dysfunction

Objective: Temporomandibular dysfunction is a common condition seen in 60-70 % of the population and can affect all age groups. The aim of this cross-sectional study is to compare muscle activation level, pain, posture, disability, and balance between individuals with temporomandibular dysfunction and healthy individuals. Materials and Methods: Total 44 participants, 21 with temporomandibular joint dysfunction and 23 healthy individuals, were included in the study. Demographic data of the two groups were obtained. Superficial electromyography was applied to Masseter Muscle to evaluate muscle activation level. Pain was evaluated with an algometer. New York Posture Analysis, Neck Pain and Disability Index and Biodex Balance System were used to compare overall body health between the two groups. Results: No significant differences found for demographic data between groups (p≥0.05). Right-left masseter muscle activation level was found higher in the healthy group compared to the Temporomandibular Joint Dysfunction group (p≤0.05). According to the algometer results, pain level both sides masseter muscle; both sides temporalis muscle was higher in Temporomandibular Joint Dysfunction group (p≤0.05). Posture of healthy individuals was better than Temporomandibular Joint Dysfunction group (p≤0.05). Most of the static and dynamic balance measurements performed on single and double legs were found significantly better (p≤0.05) in the healthy group except static double legs (p=0.12) and dynamic left legs (p=0.08). No significant difference was found between groups in Neck Pain and Disability Index (p≥0.05). Conclusion: Pain and muscle activation level were found higher in individuals with temporomandibular joint dysfunction compared to healthy individuals. Balance parameters were found better in healthy individuals than temporomandibular joint dysfunction group. Posture score was decreased in temporomandibular joint dysfunction group compared to healthy individuals and there was no significant difference in the level of disability between two groups

Gebelerde Farklı Trimesterlerde Görülebilen Problemlerin İncelenmesi

AMAÇ: Çalışmamızda, gebelikte görülebilen bel ağrısı, üriner inkontinans, konstipasyon ve sistit gibi problemlerin farklı trimesterlerdeki görülme sıklığının incelenmesi amaçlanmaktadır.YÖNTEM: Gebelerin değerlendirilmesinde, bel ağrısı için Revize Oswestry Skalası, konstipasyon için Konstipasyon Ciddiyet Ölçeği, üriner inkontinans için İnkontinans Şiddet Ölçeği ve sistit için İnterstisyel Sistit Semptom İndeksi kullanıldı.BULGULAR: Bel ağrısı; 1. trimesterdeki gebelerin %13,3’ünde şiddetli iken, 2. trimesterdeki gebelerin %7,3’ünde şiddetli olup 3. trimesterdaki gebelerin %16,9’unda şiddetlidir. Konstipasyon; 1. trimesterdeki gebelerin %86,7’sinde, 2. trimesterdeki gebelerin %87,8’inde ve 3.trimesterdeki gebelerin %86,4’ünde görülmektedir.Üriner inkontinans; 1. trimesterdeki gebelerin %13,3’ünde, 2. trimesterdeki gebelerin %56,1’inde ve 3.trimesterdeki gebelerin %45,8’inde görülmektedir.Sistit; 1. trimesterdeki gebelerin %46,7’sinde, 2. trimesterdeki gebelerin %43,9’unda ve 3.trimesterdeki gebelerin %57,6’sında görülmektedir. Fakat trimesterler arasında istatistiksel olarak anlamlı bir fark bulunmamıştır (p>0.05).SONUÇ: Gebeliğin tüm trimesterlerinde bel ağrısı, üriner inkontinans, konstipasyon ve sistit problemleri görülmekte olup, gebeliğin haftası ilerledikçe şikayetlerin görülme sıklığında artış olduğu bulunmuştur.OBJECTIVE: In our study, it is aimed to examine the incidence of problems such as low back pain, urinary incontinence, constipation and cystitis that can be seen during pregnancy in different trimesters.METHODS: Revised Oswestry Scale for low back pain, Constipation Severity Scale for constipation, Incontinence Severity Scale for urinary incontinence, and Interstitial Cystitis Symptom Index for cystitis were used in the evaluation of pregnant women.RESULTS: Low back pain; while it is severe in 13.3% of the pregnants in the 1st trimester, it is severe in 7.3% of the pregnants in the 2nd trimester and severe in 16.9% of the pregnants in the 3rd trimester. Constipation; it is seen in 86.7% of the pregnants in the 1st trimester, 87.8% of the pregnants in the 2nd trimester and 86.4% of the pregnants in the 3rd trimester. Urinary incontinence; it is seen in 13.3% of the pregnants in the 1st trimester, 56.1% of the pregnants in the 2nd trimester and 45.8% of the pregnants in the 3rd trimester. Cystitis; it is seen in 46.7% of the pregnants in the 1st trimester, 43.9% of the pregnants in the 2nd trimester and 57.6% of the pregnants in the 3rd trimester. However, there was no statistically significant difference between trimesters (p>0.05).CONCLUSION: Low back pain, urinary incontinence, constipation and cystitis problems are seen in all trimesters of pregnancy, and it has been found that the frequency of complaints increases as the week of pregnancy progresses

Analysis of Observed Voltage Oscillations in Silver Doped High Temperature Superconductor YBCO

5th International Conference on Oxide Materials for Electronic Engineering - Fabrication, Properties and Applications (OMEE) -- MAY 29-JUN 02, 2017 -- Lviv, UKRAINEWOS: 000431684900064The effect of square wave current was investigated by the voltage time (V-t curves) measurements at various external magnetic fields and periods (P) in silver doped YBCO. The general sinusoidal behavior of V-t curves was mainly interpreted as a dynamic competition between driving and pinning forces. It is observed that as the period of square wave current is increased, the amplitude of oscillation is also increased. The observed oscillations in the voltage was fitted by an common sinusoidal equation V(t) similar to sin(omega t + phi). It is also found that there is different phase angle phi values for each cycle. Fast Fourier transform measurements is applied to oscillation period (P-I) of the square wave current. The results give us that a physical mechanism is related with charge density waves. Intrinsically, in Ag doped YBCO, the pinned flux line system evokes the general behavior of charge density waves. Due to properties of the converting the square wave current to sinusoidal voltage oscillations, Ag doped YBCO sample can behave as double-integrator for the defined period, amplitude of square wave current and magnetic field values in time.Lviv Polytechn Natl Univ, Sci Res Co Electron Carat, Polish Acad Sci, Inst Phys, Representat Off Polish Acad Sci, Int Ctr Diffract Dat

Examining the Cultural Validity of Fear Survey Schedule for Children: The Contemporary Fears of Turkish Children and Adolescents

The authors examined the cultural validity of Fear Survey Schedule for Children (FSSC-AM) developed by J. J. Burnham (2005) with Turkish children. The relationships between demographic variables and the level of fear were also tested. Three independent data sets were used. The first data set comprised 676 participants (321 women and 355 men) and was used for examining factor structure and internal reliability of FSSC. The second data set comprised 639 participants (321 women and 318 men) and was used for testing internal reliability and to confirm the factor structure of FSCC. The third data set comprised 355 participants (173 women and 182 men) and used for analyses of test-retest reliability, inter-item reliability, and convergent validity for the scores of FSSC. The sum of the first and second samples (1,315 participants; 642 women and 673 men) was used for testing the relationships between demographic variables and the level of fear. Results indicated that FSSC is a valid and reliable instrument to examine Turkish children's and adolescents' fears between the ages of 8 and 18years. The younger, female, children of low-income parents reported a higher level of fear. The findings are discussed in light of the existing literature