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Perceived Risk and Mental Health Problems among Healthcare Professionals during COVID-19 Pandemic: Exploring the Mediating Effects of Resilience and Coronavirus Fear
No full textNumerical investigation of the effects of design parameters on hydraulic turbine guide vane design
No full textStructural Investıgatıon Of Opto-Mechanıcal Desıgn Under Thermal Loads
No full textGünümüzde Savunma Sanayiinin en önemli ürünleri arasında güdümlü mühimmat sistemleri yer almaktadır. Güdümlü mühimmatların en önemli alt sistemlerinden biri de “mühimmatın gözü” olarak tanımlanan arayıcı sistemleridir. Arayıcıyı dış ortamlardan korumak üzere tasarlanan optik pencere – taşıyıcı metal sisteminin çevre koşullarına dayanıklı olarak çalışabilmeleri gerekmektedir. Mühimmatlar görev döngülerinde belirli senaryolara maruz kaldığında, optik pencere ile taşıyıcı parçalar ciddi termal yüklere maruz kalmaktadır. Yapıda başarısızlığa sebep olan bazı faktörler vardır. Bunların başında, optik pencereler ile taşıyıcı metal arasındaki termal genleşme katsayısı farkı gelmektedir. Sıcaklık farkı oluştuğunda, iki yapı arasında termal genleşme farkından dolayı farklı gerilmeler görülmesi olasıdır. Diğer sebepleri, optik pencerelerin taşıyıcı metale bütünlenme yöntemi, taşıyıcı metal ile optik pencereler arasında kullanılan ara bileşenler (yapıştırıcı) gibi etmenler oluşturmaktadır. Bu çalışmada, kademeli kalınlığa sahip bir silika bazlı standart pencere ile alüminyum metal birleşiminin 22 °C den 90 °C’ye ısınması test edilmiş olup, pencerenin 6 bölgesinden gerinim ve gerilme değerleri okunmuştur. İlgili sonuçlar 3. bölümde verilmiştir. Bir diğer taraftan test kaleminin sonlu eleman modeli kurulmuş ve test sınır koşullarının dâhil edildiği termo-mekanik analiz yapılmıştır. Test sonuçlarını doğrulamak amacıyla 3 farklı alternatif analiz modelinden optimum analiz modeli çıkarılmıştır. Korelasyonu sağlanan analiz modeli ile havacılık ve savunma sanayiinde kullanılan Safir, MgO, ZnSe, Germanyum, CaF2, Silikon, MgF2 pencere türlerinin termal yük altındaki yapısal incelemesi yapılmıştır. Çalışmalarda bu pencere türlerinin farklı kalınlıktaki tipleri ayrıca incelenmiştir. Yine çalışmalara ek olarak pencerelerin alüminyum, titanyum, magnezyum ve çelik metalleri ile birleşiminde üzerinde oluşan gerilmeler bulunmuştur. İlgili sonuçlar 5. bölümde verilmiştir.Today, guided ammunition systems are among the most important products of Defense Industry. One of the most important subsystems of guided ammunition is the seeker systems, defined as the “eye of ammunition”. Designed optical window - carrier metal system must be able to function without being affected by environmental conditions. When +ammunition is exposed to certain scenarios in duty cycles, the optical window and the carrier parts are subjected to severe thermal loads. There are some factors that cause failure in the structure. The main difference is the thermal expansion coefficient between the carrier metal and oprical windows. When the temperature difference occurs, it is possible that different stresses may occur due to the thermal expansion difference between the two structures. Other reasons include the integration of the optical windows into the carrier metal, the intermediate components (adhesive) used between the carrier metal and the optical windows. In this study, a stepwise thickness of silica-based standard window and aluminum metal combination were tested for heating from 22 ° C to 90 ° C. Related results are given in section 3. On the other hand, a finite element model of the test item was established and thermo-mechanical analysis including the test boundary conditions was performed. In order to confirm the test results, the optimum analysis model was developed in 3 different alternative analysis models. Correlated analysis model was used for structural analysis of Safir, MgO, ZnSe, Germanium, CaF2, Silicon, MgF2 window types used in Aviation and Defense Industry under thermal load. Different thickness types of these window types were also investigated in the studies. In addition to these studies, stresses were found on the combination of windows with aluminum, titanium, magnesium and steel metals. Related results are given in section 5
A Duplication Upstream of SOX9 Associated with SRY Negative 46,XX Ovotesticular Disorder of Sex Development: A Case Report
No full textMultiwall carbon nanotube-supported molybdenum catalysts for ammonia decomposition reaction under microwave effect
No full textThe effects on 42CrMo4 steel matrix white iron reinforcement composite properties of production conditions
No full textComposite products are increasingly important materials. Metal-metal
composites are composites that have increased rapidly in recent years.
Composite materials are produced for a variety of purposes and using
different techniques. In this study, the use of casting technique in
metal-metal composite production, the application of heat treatment and
the effects on composite properties were evaluated. For this purpose,
composite production was performed by using White Cast Iron in solid
state and 4140 (42CrMo4) Steel in liquid state. The combined materials
were then subjected to 1, 2, 3 and 4 hours of normalization in order to
increase the interfacial bonding and improve its properties. At the end
of this study; it has been found that the interfacial bonding can be
further increased by normalization, in which metal-metal composite
production can be successfully performed using the casting technique. As
a result of these processes; according to the casting situation, the
mechanical properties of the composite increased up to 3 hours with
normalization and decreased to 4 hours due to grain roughening
Evaluation of brain fdg pet images in temporal lobe epilepsy for lateralization of epileptogenic focus using data mining methods
No full textAn Observational, Prospective, Multicenter, Registry-Based Cohort Study Comparing Conservative and Medical Management for Patent Ductus Arteriosus
No full textNo consensus has been reached on which patent ductus arteriosus (PDAs)
in preterm infants require treatment and if so, how, and when they
should be treated. A prospective, multicenter, cohort study was
conducted to compare the effects of conservative approaches and medical
treatment options on ductal closure at discharge, surgical ligation,
prematurity-related morbidities, and mortality. Infants between
24(0/7)and 28(6/7)weeks of gestation from 24 neonatal intensive care
units were enrolled. Data on PDA management and patients' clinical
characteristics were recorded prospectively. Patients with
moderate-to-large PDA were compared. Among the 1,193 enrolled infants
(26.7 +/- 1.4 weeks and 926 +/- 243 g), 649 (54\%) had no or small PDA,
whereas 544 (46\%) had moderate-to-large PDA. One hundred thirty (24\%)
infants with moderate-to-large PDA were managed conservatively, in
contrast to 414 (76\%) who received medical treatment. Eighty (62\%) of
130 infants who were managed conservatively did not receive any rescue
treatment and the PDA closure rate was 53\% at discharge. There were no
differences in the rates of late-onset sepsis, necrotizing enterocolitis
(NEC), retinopathy of prematurity, intraventricular hemorrhage (>= Grade
3), surgical ligation, and presence of PDA at discharge between
conservatively-managed and medically-treated infants (p> 0.05).
Multivariate analysis including perinatal factors showed that medical
treatment was associated with increased risk for mortality (OR 1.68,
95\% Cl 1.01-2.80,p= 0.046), but decreased risk for BPD or death
(BPD/death) (OR 0.59, 95\%Cl 0.37-0.92,p= 0.022). The preferred
treatment options were ibuprofen (intravenous 36\%, oral 31\%), and
paracetamol (intravenous 26\%, oral 7\%). Infants who were treated with
oral paracetamol had higher rates of NEC and mortality in comparison to
other treatment options. Infants treated before postnatal day 7 had
higher rates of mortality and BPD/death than infants who were
conservatively managed or treated beyond day 7 (p= 0.009 and 0.007,
respectively). In preterm infants born at <29 weeks of gestation with
moderate-to-large PDA, medical treatment did not show any reduction in
the rates of open PDA at discharge, surgical or prematurity-related
secondary outcomes. In addition to the high incidence of spontaneous
closure of PDA in the first week of life, early treatment (<7 days) was
associated with higher rates of mortality and BPD/death
