1,040 research outputs found
Small channel-length SiC nanowire field-effect transistors
No full textNM03.10.12 Small Channel-Length SiC Nanowire Field-Effect Transistors Ali Uzun and Kasif Teker; Electrical and Electronics Engineering, Istanbul SehirUniversity, Istanbul, Turkey.Low-dimensional semiconductor materials offer new ways to develop nanoscaleelectronic and optoelectronic devices and components. From the class of wide band gap semiconductor nanomaterials, SiC nanowires combine the uniqueproperties of one-dimensional materials with that of superior intrinsic SiC characteristics and offer great opportunities for high power and high frequencyelectronic devices as well as in sensors capable of operating at high temperatures or hostile environments.This study presents a systematic investigation of electronic transport properties of p-type SiC nanowire field effect transistors (SiCNW-FET) with multiplechannel lengths (smallest channel length SiCNW-FET reported). The investigation has focused on the parameters including transconductance (gm), carriermobility (µh), ON-OFF current ratio (gating effect- Ion/Ioff). Further, a comprehensive comparison of our experimental measurements with the previouslyreported theoretical and experimental studies is presented.MOCVD-grown long SiCNWs with diameters about 60 nm are placed on a highly doped SiO2/Si substrate. The electrodes (Cr/Au: 3nm/100nm) aredefined by the e-beam lithography (EBL) with varying channel lengths of 120 nm, 220 nm and 1.5 µm followed by metal deposition through e-beamevaporation. The initial electrical measurements from the fabricated p-type SiCNW-FETs exhibited transconductance of 6.9x10-9 A/V (@ Vds = 0.05V),carrier mobility of 1.7 cm2/V.s, carrier concentration (nh) of 3.72 x 1020 cm-3, and Ion/Ioff ratio more than 104 for a device with 120nm channel length. Thegating effect achieved in this study is the highest value reported in the literature for a SiCNW-FET, to the best of our knowledge. As a consequence, thisstudy shows the great potential of SiCNW-FETs to be utilized in nanoelectronic and nanophotonic applications
Fabrication of a fine-pattern flexible nanowire photodetector by shadow mask
No full textF.NM01.10.09 Late News: Fabrication of a Fine-Pattern Flexible Nanowire Photodetector by Shadow Mask Abstract Body: Recently, ultraviolet photodetectors (UVPDs) have been used on largescale applications such as environmental monitoring, flame detection, spacecommunication, biomedical applications, pharmaceutical, and chemical analysis.Besides, advances in internet technologies such as the internet of things (IoT) endorsethe integration of sensors more rapidly in every aspect of our lives. This trend demandsthe fabrication of smaller, lighter, less complicated, and low power devices. Therefore,designing low cost, self-powered, highly sensitive, Óexible UVPD nanodevices arebecoming a hot research area for near future optoelectronics. Silicon carbide (SiC), awide bandgap semiconductor, is an excellent contender to fulfill those expectations. Inaddition to having characteristics of one-dimensional nanostructure such as highsurface to volume ratio, high crystalline quality, SiC nanowires also possess superiormaterial attributes like high breakdown voltage, high thermal conductivity, high driftvelocity, excellent chemical and physical stability. In this study, we propose a very cost-effective, flexible, self-powered single SiC nanowire ultraviolet photodetector (SiCNWUVPD) fabricated on a polyvinylchloride (PVC) substrate. The self-powered flexibleSiCNW-UVPD was fabricated via a commercially available transmission electronmicroscopy (TEM) grid (physical mask) and a sputter coater system. Gold (Au)electrodes of 110 µm x 110 µm and a gap of 4 µm were successfully achieved withoutthe use of complicated and expensive methods like photolithography. Two-probephotocurrent-time (I-t) and I-V measurements were performed to revealphotoresponse characteristics such as the photo-to-dark current ratio (PDCR),sensitivity, and responsivity under 254 nm wavelength UV light at 0 V bias. A shallowdark current around 0.087 pA and a good PDCR value of 18 are obtained. Moreover,sensitivity and responsivity values are calculated as 1756 and 170 mA/W, respectively.In addition, the specific detectivity calculations, the e×ect of bias, and vigorous bendingtest results are discussed as well. Our work provides the following unique advantages:(i) to the best of our knowledge, the first demonstration of a single SiC nanowire PD ona flexible substrate with great performance, (ii) a very cost-e×ective fabrication methodand readily applicable to any substrate, (iii) exhibiting high sensitivity and responsivityvalues under UV light at 0 V bias. Therefore, our SiCNW-UVPD device presents anopportunity for low-cost, easy to fabricate, self-powered photodetectors for upcomingfuture technologies such as wearable sensors, electronic skins, and the internet ofthings
Türkiye’de intihara bağlı ölümlerin epidemiyolojik özellikleri ve yıllar içindeki trendi, 2007-2019
No full textObjective: Suicide is an important public health problem today. Accurate, complete, timely,
and rapid registration and evaluation of data about suicide will form the basis for preventive
interventions to be developed. This study aims to determine the epidemiological features of
suicide mortality in Turkey between 2007-2019 and examine the trend of suicide mortality
rates. Methods: In this study, the Turkish Statistical Institute (TURKSTAT) data was used, all
deaths related to suicide in Turkey between 2007-2019 were analyzed. The change in ageadjusted suicide-related mortality rates over time was evaluated by Jointpoint regression
analysis. Results: Between 2007 and 2019, the age standardised suicide-related mortality
rates in males increased by an average of 1.3 percent annually, and this change was statistically
significant (p<0.05). In females, this value decreased by an average of 2.6 percent annually
in the same period, and this change was statistically significant, too (p<0.05). There was no
statistically significant change in total. In 2019, the male/female ratio in age standardised
suicide-related mortality rates was 3.4. However, in the 0-14 age group, the rate was similar
for females and males. Conclusion: While it decreases in the world, the suicide mortality rates
in Turkey do not decrease. The increase in suicide mortality seen in males is noteworthy. In
females, the 0-14 age group is seen as risky. Preventive programs and regulations primarily
for risky groups are essential in combating this important public health problem.
Keyword: Suicide, Mortality, Epidemiology, TurkeyAmaç: İntihar günümüzde önemli bir halk sağlığı sorunudur. İntihar konusundaki verilerin
doğru, tam, zamanında ve hızlı kaydedilmesi ve değerlendirilmesi geliştirilecek koruyucu
müdahaleler için temel oluşturacaktır. Bu araştırmanın amacı Türkiye’de 2007-2019 yılları
arasında meydana gelen intihara bağlı ölümlerin epidemiyolojik özelliklerini belirlemek ve
intihara bağlı ölüm hızlarının yıllar içindeki trendini incelemektir. Yöntem: Türkiye İstatistik
Kurumu (TUİK) verilerinin kullanıldığı bu araştırmada 2007-2019 yılları arasında Türkiye’de
görülen tüm intihara bağlı ölümler analiz edilmiştir. Yaşa göre standardize edilmiş intihara
bağlı ölüm hızlarının zaman içinde göstermiş olduğu değişim Jointpoint regresyon analizi ile
değerlendirilmiştir. Bulgular: 2007-2019 yılları arasında erkeklerde yaşa göre düzeltilmiş
intihara bağlı ölüm hızları yıllık ortalama yüzde 1.3 artış göstermiştir ve bu değişim istatistiksel
olarak anlamlıdır (p<0.05). Kadınlarda ise aynı süreçte bu değer yıllık ortalama yüzde 2.6
azalma göstermiştir ve bu değişim de istatistiksel olarak anlamlıdır (p<0.05). Toplamda ise
istatistiksel olarak anlamlı bir değişim olmamıştır. Yaşa göre standardize edilmiş intihara bağlı
ölüm hızlarının erkek/kadın oranı 2019 yılında 3.4’dir. Ancak 0-14 yaş grubunda kadınlardaki
yaşa göre standardize edilmiş intihar bağlı ölüm hızları erkekler ile benzer seyretmektedir.
Sonuç: Dünyanın aksine Türkiye’de intihara bağlı ölüm hızları azalmamaktadır. Erkeklerde
görülen intihara bağlı ölüm hızlarının artışı çarpıcıdır. Kadınlarda ise 0-14 yaş grubu riskli
görülmektedir. Özellikle riskli gruplara yönelik koruyucu programlar ve düzenlemeler bu
önemli halk sağlığı sorunuyla mücadelede önem taşımaktadır.
Anahtar Kelimeler: Intihar, Ölüm, Epidemiyoloji, Türkiy
Enhanced photoresponse of a self-powered gallium nitride photodetector via sequentially-deposited gold nanoparticles for sustainable optoelectronics
No full text© 2023, The Minerals, Metals & Materials Society.It is becoming crucial to design/fabricate eco-friendly, sustainable electronic and photonic devices to minimize the carbon footprint for future systems. In this study, we have demonstrated a steady photoresponse enhancement of the self-powered GaN ultraviolet photodetector (GaN-UVPD) via sequentially deposited gold nanoparticles (Au NPs) under 254, 302, and 365 nm UV light exposure. The AuNP-deposited GaN-UVPD exhibited excellent responsivity of 0.65 A/W and detectivity of 6.51 × 1012 cm.Hz1/2 W−1 under 302 nm UV light without any external power. Moreover, the sensitivity of the device increased from 1.98 × 106% to 3.32 × 106% following Au nanoparticle deposition. Additionally, the plausible mechanisms for the self-powered and Au nanoparticle-induced photoresponse enhancement have been discussed. In brief, the high-performance photoresponsivity of our self-powered GaN-UVPD could find many useful applications in sustainable energy and eco-friendly optoelectronic devices
BMP1 5'UTR+104 T/C gene variation: can be a predictive marker for serum HDL and apoprotein A1 levels in male patients with coronary heart disease
No full textAkadam Teker, Aysegul Basak/0000-0003-3618-0560; Ozturk, Oguz/0000-0002-2439-9269WOS: 000444752900058PubMed: 30062502Apolipoprotein A1 (Apo A1), the major protein of HDL, is secreted as a proprotein and then is cleaved by C-terminal procollagen endoproteinase/bone morphogenetic protein-1 (BMP1). BMP1 stimulates the conversion of newly secreted proapo A1 to its phospholipid-binding form. Therefore, genetic variations of BMP1 gene may affect serum ApoA1 and HDL levels. We aimed to investigate the effects of the functional 5'UTR + 104 (T/C) variant of BMP1 on serum ApoA1 and HDL levels and risk of coronary heart disease (CHD) in this study. The BMP1 5'UTR + 104 (T/C) (rs143383) variation was determined in 131 male patients with CHD and 51 male controls by real-time polymerase chain reaction technique. ApoA1 levels were measured by immunoturbidimetry. The serum Apo-A1 levels were found higher in controls with the BMP1-CC genotype than those with the T-allele (p < 0.001). Our findings show the association of this variation with serum ApoA1 and HDL-C levels which increase in the order of CT < TT < CC in the controls. No effect was found on ApoA1 and HDL-C levels in CHD patients, as it was observed in the controls. However, the BMP1-TT genotype was associated with higher triglyceride (TG) levels as compared to C-allele (p = 0.009). These discrepancies could be due to statin therapy which has dominant effects on lowering cholesterol levels comparing to TG levels. Our results indicated that the BMP1 5'UTR + 104 (T/C) variation may affect the serum ApoA1 and lipoprotein levels depending on statin therapy so that contributes to the development of CHD.Scientific Research Projects Coordination Unit of Istanbul UniversityIstanbul University [11304]The present study was supported by a grant from the Scientific Research Projects Coordination Unit of Istanbul University (Project No: 11304)
Gallium nitride nanowire field effect transistor for high temperature applications
No full textF.SF01.09.04 Gallium Nitride Nanowire Field Effect Transistor for High Temperature Applications Abstract Body: Wide bandgap (WBG) semiconductor-based electronics are becomingthe center of interest due to their ability to operate at high temperatures and highvoltages. Gallium Nitride (GaN), as one of the WBG semiconductors, is a strongcandidate that can meet expectations in high-temperature electronic applications suchas military systems, automotive and aerospace control units, gas and oil explorationdrilling systems. The superior physical properties of GaN nanowires such as high directbandgap, high breakdown voltage, and high thermal conductivity, as well as highsurface area to volume ratio, make it even more signiÒcant material for harshenvironments. In this work, we investigate the electrical transport properties of a backgated single GaN nanowire Òeld-e×ect transistor (GaNNW-FET) at elevatedtemperatures. In order to analyze transport properties (IDS-VDS and IDS-VGS),electrical measurements were performed at temperatures ranging from roomtemperature to as high as 350°C. The device performs very well until 250°C, whereas itshows some reduction in current values beyond 300°C. In fact, the drain currentincreases by 2.1, 13.6 and 19.7 times at the temperatures of 100°C and 200°C, 250°C,respectively, with respect to room temperature current at the same bias voltage of 1 V.The enhancement of current is likely due to the reduction of contact resistancebetween the nanowire and electrodes as well as an increase in thermally excited carrierconcentration. On the other hand, degradation of current is likely due to the increase inlattice scattering, lowering the carrier mobility, of the GaN nanowire. Moreover, theinÓuence of high temperature on important transport properties such astransconductance, carrier concentration and carrier mobility will be presented indetails. The device o×ers the following unique advantages: (i) stable operation at hightemperatures (at 350°C), (ii) exhibiting an on/o× current ratio of 5.5 x 102 and a hightransconductance value of 3.09 µS at 350°C indicating a good gating e×ect even at hightemperatures, and iii) o×ering solutions not only for high-power but also for low-powercircuit and photonic applications at high temperature ambients (&gt; 300oC). In summary,GaNNW-FET proves to be an excellent device capable of operating at hightemperatures enabling the development of high-performance nanoelectronic/photonicdevices especially for harsh conditions
Genetic polymorphisms of the SHBG gene can be the effect on SHBG and HDL-cholesterol levels in Coronary Heart Disease: a case-control study
No full textAkadam Teker, Aysegul Basak/0000-0003-3618-0560WOS: 000478684300060PubMed: 31111369Sex hormone binding globulin (SHBG) level is positively associated with the high-density lipoprotein cholesterol (HDL-C) levels. The aim of this study was to investigate the effects of the SHBG gene variations (D356N, rs1799941, and P156L) on SHBG and HDL-C levels and Coronary Heart Disease (CHD) risk. The SHBG D356N (rs6259,G>A), P156L (rs6258,C>T), and rs1799941(G>A) polymorphisms were determined in 131 male CHD patients and 55 male controls by PCR-RFLP and real-time PCR techniques. SHGB levels were measured by Electro-chemiluminescence immunoassay (ECLIA). In the patients who had SHBG levels lower than threshold 35nmol/l value, the risk of being HDL-C levels lower than threshold 0.90mmol/l value was observed statistically significant (p=0.017; OR 2.522, 95% CI 1.170-5.438). The rs1799941 GG was associated with increased CHD risk when compared with the A allele carriers (GA+AA) (p=0.019, OR 2.222, 95% CI 1.130-4.371). In addition, the rs1799941 GG genotype and D356NN allele were associated with lower SHBG in the CHD group (p<0.01). The logistic regression analysis also revealed the rs1799941 GG genotype was significantly associated with low SHBG in CHD patients. It was observed that Haplotype-1(rs1799941 G allele-P156L P allele-D356N D allele) was associated with increased CHD risk, while Haplotype-2 (rs1799941 rare A allele-P156L C allele- D356N G allele) was correlated with the decreased CHD risk (p=0.0167). Our findings suggest that there is a positive correlation between SHBG and HDL-C levels in CHD patients, and this association might be affected by SHBG gene variations.Research Fund of Istanbul UniversityIstanbul University [12104]The present work was supported by the Research Fund of Istanbul University. Project No. 12104. The authors would like to thank Professor Oguz Ozturk and Associate Professor Ozlem Kucukhuseyin for their statistical contribution and valuable comments and suggestions, which were helpful in improving the paper
National income distribution: a countrywise analysis
No full textPurpose- This study aimsto analyze the changes in income distribution for selected developing countries over a time period in between 2015 and 2022, 8 years of observations. It hypothesizes that Covid19 pandemic period of 2020 and 2021 significantly impacted income distribution in all developing countries investigated. Methodology- Income distribution data for this study are extracted from the World Inequality Database addressing household income adjusted for after-tax income. Each household’s income is equally divided among the adult population aged 20 or older. The data are categorized into 10% income groups resulting in ten distinct income levels for the analysis. The study examines income distribution of five developing comprising Turkiye, Czechia, Greece, Hungary, and Romania. Findings- The top 10% of the population in the developing countries take 33% of national income on average. The average per capita income was 42,610 in 2022 after a dip of with a similar Covid19 dip. However, social policies generally failed resulting in income shifting from lower and middle-income groups to the top 30%. Conclusion- All countries implemented various social programs to support those most affected by Covid19. The social policies and measures implemented by governments to mitigate the effects of Covid19 appear to have been more successful in some of the developing countries comparing to the other developing countries. Although the developing countries could manage to increase their overall national income, they failed to restore their pre-pandemic income distribution. Significant income transfer occurred from the bottom 20% and middle 50% to the top 30% in these countries.Publisher's Versio
Türkiye’de İntihara Bağlı Ölümlerin Epidemiyolojik Özellikleri ve Yıllar İçindeki Trendi, 2007-2019
No full textGiriş-Amaç: İntihar günümüzde önemli bir halk sağlığı sorunudur. İntihar konusundaki verilerin doğru, tam,
zamanında ve hızlı kaydedilmesi ve değerlendirilmesi geliştirilecek koruyucu müdahaleler için temel oluşturacaktır. Bu araştırmanın amacı Türkiye’de 2007-2019 yılları arasında meydana gelen intiharların epidemiyolojik özelliklerini belirlemek ve intihara bağlı ölüm hızlarının yıllar içindeki trendini incelemektir.
Gereç-Yöntem: Türkiye İstatistik Kurumu (TUİK) verilerinin kullanıldığı bu araştırmada 2007-2019 yılları
arasında Türkiye’de görülen tüm intihara bağlı ölümler analiz edilmiştir. TUİK’ten alınan intihar sayıları ile
öncelikle her yıl için kadın ve erkeklere ait kaba ölüm hızları ve yaşa özel ölüm hızları hesaplanmış daha sonra
Dünya Sağlık Örgütü’ne (DSÖ) ait standart nüfus oranları kullanılarak yaşa göre standardize edilmiş intihara
bağlı ölüm hızları bulunmuştur. Yaşa göre standardize edilmiş intihara bağlı ölüm hızlarının zaman içinde
göstermiş olduğu değişim Jointpoint regresyon analizi ile değerlendirilmiştir. Bu analiz ölüm hızlarının yıllar
içinde gösterdiği değişimin istatistiksel olarak anlamlı olup olmadığını göstermektedir. İstatistiksel anlamlılık
düzeyi <0,05 olarak alınmıştır. Araştırma için gerekli etik kurul izni Marmara Üniversitesi Tıp Fakültesi Etik
Kurulu’ndan alınmıştır (Protokol Numarası: 09.2021.717 Tarih:04.06.2021).
Bulgular: 2007-2019 yılları arasında Türkiye’de toplam 40 180 intihara bağlı ölüm görülmüştür. Bunların 29
287’si erkeklerde; 10 893’ü kadınlarda olmuştur. 2007 yılında toplam intihara bağlı ölüm sayısı 2 793 iken bu
sayı 2019 yılında 3 406 olmuştur. Erkeklerde yaşa göre standardize edilmiş intihara bağlı ölüm hızı yıllık ortalama yüzde 1.3 artış göstermiştir ve bu değişim istatistiksel olarak anlamlıdır (p<0.05). Kadınlarda ise aynı
süreçte bu değer yıllık ortalama yüzde 2.6 azalma göstermiştir ve bu değişim de istatistiksel olarak anlamlıdır
(p<0.05). Yaşa göre standardize edilmiş intihara bağlı ölüm hızlarının erkek/kadın oranı 2019 yılında 3.4’dir.
0-14 yaş grubu hariç tüm yaş gruplarında erkeklerdeki yaşa göre standardize edilmiş intihara bağlı ölüm hızı
kadınlardan daha yüksektir.
Sonuç: Dünyanın aksine Türkiye’de intihara bağlı ölüm hızları azalmamaktadır. Erkeklerde görülen artış
çarpıcıdır. Kadınlarda ise 0-14 yaş grubu riskli görülmektedir. Özellikle riskli gruplara yönelik koruyucu programlar ve düzenlemeler bu önemli halk sağlığı sorunuyla mücadelede önem taşımaktadı
Long covid in hospitalized COVID-19 patients: A retrospective cohort study
No full textBackground: We aimed to evaluate the Long COVID frequency, and related factors in patients followed up
after hospitalization.
Methods: This retrospective cohort study included 133 inpatients with COVID-19 PCR test positivity from
Nigde Province, Turkey between 01.01.2021 and 28.02.2021. The characteristics of the patients were recorded
by examining the files, and the symptom questioning was made by telephone interviewing with the patients
approximately four months after the date of diagnosis. The presence of at least one symptom lasting more than
four weeks was described as Long COVID.
Results: The frequency of Long COVID was 64.7%. The most common Long COVID symptoms were fatigue (45.9%), respiratory distress (25.6%), and muscle / joint pain (24.8%), respectively. In comparison analysis to identify factors associated with Long COVID; Long COVID was found to be more frequent among
women (P=0.04); patients with severe COVID-19 (P<0.01), patients with prolonged hospital stay (P=0.03),
patients with the comorbid disease (P=0.03), and Diabetes Mellitus patients (P=0.02). Additionally, the frequency of Long COVID increased as the depression score stated by the person increased after COVID-19
disease (P=0.02).
Conclusion: The treatment of COVID-19 patients should not end when they are discharged from the hospital. On the contrary, these patients, especially high-risk patients, should be followed up in post-COVID clinics
and rehabilitated physically and psychosocially with a multidisciplinary approach following the recovery period
of the acute illness
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