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Bu çalışmada; düşük yoğunluklu polietilen (LDPE) içerisine farklı oranlarda polistiren (PS), stiren etilen bütadien stiren termoplastik blok kopolimeri (SBS) ve montmorillonite nanokil katarak bir polimer kompoziti üretilmiştir. Tüm malzemeler çift vidalı ekstrüzyon makinesinde karıştırılarak altı farklı polimer kompoziti elde edilmiştir. Daha sonra elde edilen bu polimer kompozitlerinden enjeksiyon kalıplama yöntemi ile kalıplama yaparak standart test numuneleri basılmıştır. Kompozitin çeşitli mekanik özellikleri hakkında bilgi edinmek için çekme testi, üç nokta eğme testi, sertlik testi ve darbe testleri yapılmıştır. Ayrıca nanokil tozlarının matris içerisinde dağılımlarını görmek için darbe testleri sonucundan elde edilen kırık yüzeylerden taramalı elektron mikroskobisi (SEM) ile fotoğrafları çekilmiştir. Yapılan testlerin sonuçlarına göre, matris içerisinde nanokil toz oranının artmasıyla; elastiklik modülü, çekme mukavemeti, kopma mukavemeti, eğilme modülü, maksimum eğilme mukavemeti ve sertlik değerlerinin arttığı buna karşılık kopma uzaması, darbe mukavemeti ve eğilme uzaması değerlerinin düştüğü tespit edilmiştir.

OBJECTIVE: Fetal cerebral ventriculomegaly is defined as enlarged cerebral lateral ventricles. The etiology of fetal cerebral ventriculomegaly is multifactorial. Aneuploidy in ventriculomegaly is detected especially in moderate and severe ventriculomegaly accompanied by structural anomalies. This study aims to evaluate patients with fetal cerebral ventriculomegaly for associated structural and genetic abnormalities and their obstetric and neonatal outcomes. STUDY DESIGN: This retrospective cohort study was conducted at Dokuz Eylul University Faculty of Medicine, Obstetrics and Gynecology Department between January 2009 and December 2019. Eighty-seven cases were included in the study and were evaluated for associated structural abnormalities. The results of genetic diagnostic tests were evaluated retrospectively. Postpartum information of the cases was obtained from the hospital records and neurodevelopmental development of the newborns was recorded. RESULTS: Patients were classified as mild, moderate, and severe ventriculomegaly. Concomitant structural abnormalities were observed in 64% of the patients. Corpus callosum agenesis was the most common abnormality. The incidence of accompanying anomalies in severe ventriculomegaly was found to be significantly higher. Invasive prenatal tests were performed on 27 patients and one of them had a chromosomal abnormality. No significant correlation was observed between the incidence of postpartum neurodevelopmental disorders and the degrees of ventriculomegaly. CONCLUSIONS: Fetal cerebral ventriculomegaly is a dynamic process. The etiology is multifactorial and abnormalities can be detected during follow-up. All patients should be evaluated carefully for associated abnormalities. The cases should also be evaluated for neurodevelopmental outcomes after birth. All diagnosis, follow-up, and treatment options should be handled with a multidisciplinary approach.

Amaç: Diş gelişimi, çocuklarda büyüme ve gelişmenin önemli bir göstergesidir. Büyüme sürecinde boy ve kilo artışı ile diş boyutlarının artışı birbirlerine paralel seyreden parametrelerdir. Bu çalışmanın amacı; süt dişlerinin kuron boyu ve meziodistal (MD) genişlikleri ile çocuğun boyu, kilosu ve vücut kitle indeksi (VKİ) arasındaki ilişkinin belirlenmesidir. Gereç ve Yöntemler: Çalışmaya; İstanbul Üniversitesi Diş Hekimliği Fakültesi Pedodonti Anabilim Dalı kliniğine başvurmuş olan 3-6 yaş grubu 68 çocuk (34 kız, 34 erkek) dahil edilmiştir. Çocukların alt-üst çenesinden ölçü alınarak elde edilen alçı model üzerinden dijital bir kumpas yardımıyla dişlerin klinik kuron boyu ve meziodistal genişlik uzunlukları ile çocukların kilo, boy ve yaş değerleri kaydedilmiştir. Kaydedilen bu değerler arasındaki ilişki istatiksel olarak değerlendirilmiştir. Bulgular: Çalışmaya katılan 68 çocuğun 25’i (%36,8) 3-4 yaş grubunda iken 22’si (%32,4) 5 yaş grubuna, 21’i ise (%30,9) 6 yaş grubuna dahildir. Tüm yaş gruplarında, FDI numaralandırma sistemine göre 5. ve 7. bölgedeki dişlerin kuron boyu ortalamaları arasında ve meziodistal genişliği arasında anlamlı bir fark bulunmuştur (p=0,001). Gruplar arası karşılaştırmada erkeklerde 53 numaralı dişin kuron boyu için istatistiksel olarak anlamlılık saptanmıştır (p=0,019). Değerlendirmeye alınan tüm dişlerin kuron boyu ve meziodistal genişliği ile vücut kitle indeksi değişkeni ile karşılaştırılmasında anlamlı bir ilişki bulunamamıştır (p>0,05). Sonuç: Bu çalışmada bireyin boyu ile dişin meziodistal genişliğine göre bireyin boyu ile kuron boyu arasında daha kuvvetli korelasyon olduğu belirlenmiştir. Bunun sonucunda süt dişlerinin kuron boyu ve meziodistal genişliğinin, çocukların muhtemel boylarını tahmin etmede kullanılması ve vücut ölçüleri arasında ilişki kurulmasının değerlendirilebileceği düşünülmektedir., Background: Dental development is an important indicator of growth and development in children. The increase of height and weight of children and the increase of tooth dimensions are convenient to each other at the growth process. The purpose of this study is to determine the relationship between the height, weight and body mass index (BMİ) of the children and the clinical crown length and mesiodistal width of the teeth. Methods: The study includes 68 children (34 girls, 34 boys) aged 3-6-years who were consulted to İstanbul University, Faculty of Dentistry, Department of Pediatric Dentistry. Clinical crown lenght and mesiodistal width of the teeth were recorded with a digital compass on the gypsum model which obtained from the maxilla and mandibula. Weight, height and age of the children were recorded. The relationship between these values were evaluated statistically. Results: 68 children who participated in this study, 25 (36.8 %) were in 3-4-year-old group, 22 (32.4 %) were in 5-year-old group and 21 (30.9 %) were in 6-year-old group. There was a significant difference between the height of teeth and mesiodistal width in 5th and 7th regions in all age groups (p=0.001). Comparison between groups is statistically significant in boys crown height of 53 (p=0.019). There was no significant relationship between height and mesiodistal varianceand body mass index for all teeth evaluated (p> 0,05). Conclusions: This study determined the height of children showed stronger correlations with the height of crown than the mesiodistal width of the teeth. The relationship between the height of crown and the mesiodistal width of deciduous teeth can be use for estimating the possible height of the children and the relationship between body measurements can be evaluated.

The structural capacity of pavement foundation is altered by moisture conditions. Reliable moisture monitoring of geomaterials throughout pavement service life is critical for asset management by transportation agencies. Improved moisture sensing enables transportation officials and practitioners to better understand performance of complex recycled materials under frequent extreme rain events. Although moisture sensing for geomaterials has improved significantly, there are still challenges when using sensors in recycled materials that may contain unhydrated cement, aged asphalt, or both. Challenges include the development of calibration functions that account for the presence of recycled materials and robust installation procedures, as technology was developed mostly for agricultural practices. In this study, a series of experiments were conducted to suggest improvements for installation techniques and data interpretation of soil moisture and water potential sensors. Suggested installation guidelines minimize wash-out and erosion potential at the soil–sensor interface. Experimental results indicate a strong bilinear relation between dielectric of recycled materials and water content, with a region of relatively small change governed by dielectric permittivity of air and a region of rapid change controlled by dielectric permittivity of water. Moreover, it was found that dielectric permittivity is not significantly affected by aggregate internal structure as dielectric for a specific moisture content for different compaction degrees is relatively similar. Furthermore, soil water characteristic curves obtained using the water potential sensor and improved installation technique compare reasonably well with laboratory results obtained with traditional equipment. Reliability of both moisture and water potential sensors was improved with the suggested guidelines.

In this study; a polymer composite was produced by adding different proportions of polystyrene (PS), styrene ethylene butadiene styrene thermoplastic block copolymer (SBS) and montmorillonite nanoclay into low density polyethylene (LDPE). Six different polymer composites were produced by mixing all materials in a twin screw extruder. Later, standard test samples were molded from the obtained polymer composites by injection molding method. To learn about the various physical and wear properties of polymer composite materials obtained; Vicat softening temperature, moisture content, melt flow index (MFI), thermal deflection temperature (HDT), friction coefficient, density and wear tests were performed. In addition, in order to see the distribution of montmorillonite in the polymer matrix, microstructure photographs were taken with scanning electron microscopy (SEM) by using fracture surfaces of impact test samples. According to the results obtained from the tests carried out, which are included in low density polyethylene matrix; It has been determined that there are significant changes in the physical and abrasion values of the polymer composite with the change of PS, SBS and nano clay ratios., Bu çalışmada; düşük yoğunluklu polietilen (LDPE) içerisine farklı oranlarda polistiren (PS), stiren etilen bütadien stiren termoplastik blok kopolimeri (SBS) ve montmorillonite nanokil katarak bir polimer kompoziti üretilmiştir. Tüm malzemeler çift vidalı ekstrüzyon makinesinde karıştırılarak altı farklı polimer kompoziti üretilmiştir. Daha sonra elde edilen bu polimer kompozitlerinden enjeksiyon kalıplama yöntemi ile kalıplama yapılarak standart test numuneleri basılmıştır. Elde edilen polimer kompozit malzemelerin çeşitli fiziksel ve aşınma özellikleri hakkında bilgi edinmek için; Vicat yumuşama sıcaklığı, nem emme oranı, erime akış indeksi (MFI), ısıl çarpılma sıcaklığı (HDT), sürtünme katsayısı, yoğunluk ve aşınma testleri yapılmıştır. Ayrıca darbe testi numunelerinin kırık yüzeylerinden taramalı elektron mikroskobisi (SEM) ile mikroyapı fotoğrafları çekilmiştir. Yapılan testler sonucunda düşük yoğunluklu polietilen içerisine katılan; PS, SBS ve nano kil oranlarının değişimi ile polimer kompozitinin fiziksel ve aşınma değerlerinde önemli değişimlerin olduğu tespit edilmiştir.

Parasitic myomas occur especially after laparoscopic myomectomy and its incidence increases due to the use of morcellators. Parasitic myomas can rarely occur at the port entry site, being more commonly seen on the intestines, the omentum, the ureter, the bladder, and the diaphragm in different periods after surgery, with the average duration being 24 months. In this article, we present the case of parasitic myoma developing secondary to the port site in a 45-year-old nulliparous woman after the use of laparoscopic myomectomy and morcellation 8 years ago. The patient presented with complaints of pelvic pain and a palpable mass in the left trocar incision line, and an appearance compatible with multiple myomas in the subcutaneous tissue of the left trocar incision line. Besides, myomas were also observed in the mesentery of the rectosigmoid colon and at the uterus in the present study. Numerous and large myomas were observed in the uterus, in the mesentery of the rectosigmoid colon, on the left pelvic peritoneum, and under the skin corresponding to the port entrance. The pathological examination of the myomas excised was reported as leiomyoma. In this article, the diagnosis, the treatment, the possible risk factors, and the complications of myomas were discussed in the light of the literature.

The Turizm Mecmuası was published when tourism movement began to rise in the world and in Turkey. With 343 issues, the journal had been continuously published between 1957 and 1987. The purpose of this journal was to make Turkey an attraction hub by presenting what Turkey can offer, and to spread such movement throughout the society. The Turizm Mecmuası became a popular periodical among state institutions, private sector, and entrepreneurs. The purpose of this study is to introduce the journal, which witnessed the development of tourism in Turkey For this purpose, its all issues were reviewed by the authors, and the journal was examined contextually and formalistically. A descriptive approach was adopted, and qualitative research method was used in this study. Following the reviews, it was observed that the journal constituted a formal standard and maintained this standard from beginning to the end. The contextual examination indicates that the journal brought forward the events that might affect tourism movements in that period, and discussed various subjects, such as political and economic events and natural disasters, in terms of tourism., Turizm Mecmuası, dünyada ve Türkiye’de turizm hareketinin hızlandığı bir dönemde yayımlanmıştır. Dergi 1957 yılından 1987 yılına kadar aralıksız bir biçimde 343 sayı olarak okuyucusuyla buluşmuştur. Derginin yayın amacı, Türkiye’nin sahip olduğu güzellikleri okuyuculara aktararak Türkiye’yi bir çekim noktası haline getirmek ve turizm hareketini topluma yaymak olarak ifade edilmiştir. Turizm Mecmuası dergisi devlet kurumları, özel yatırımcılar ve işletmeciler tarafından ilgiyle takip edilen süreli bir yayın olmuştur. Bu çalışmada, Türkiye’de turizmin gelişimine tanıklık eden ve 30 yıl boyunca kesintisiz bir biçimde yayımlanan turizm dergisini, turizm sektörüne ve turizm araştırmacılarına tanıtmak amaçlanmıştır. Bu amaçla derginin tüm sayıları araştırmacılar tarafından incelenmiş ve dergi içerik ve biçimsel olarak değerlendirilmeye tabi tutulmuştur. Bu noktada çalışmada, betimsel bir yaklaşım benimsemiş ve nitel araştırma yönteminden yararlanılmıştır. Yapılan incelemelerden sonra derginin biçimsel bir standart oluşturduğu ve bu standardını ilk sayısından son sayısına kadar koruduğu anlaşılmıştır. Diğer yandan dergi içerik olarak incelendiğinde, dergide dönemin turizmini etkileyecek olayların gündeme getirildiği, siyasi, askeri, ekonomik ve doğal afetler gibi birbirinden farklı tüm unsurların turizm açısından değerlendirildiği görülmüştür.

Objectives: To determine the COVID-19 pandemic’s effect on female sexual functions among Turkish women. Material and methods: The present study was performed by using the previous study data that was conducted before the pandemic to detect female sexual function by using questionnaires. Comparison of Female Sexual Function Index (FSFI), Beck Anxiety Inventory (BAI), and Beck Depression Inventory (BDI) scores in women during and before the pandemic. Participants were asked to fill questionnaire forms again. Results: FSFI scores of the participants were higher before the pandemic, however, this finding was not statistically significant (21.8 vs 21.0, p = 0.27). BAI and BDI scores with high scores accompanied by anxiety and depression were found statistically significantly higher in the study (11.2 vs 13.3, p < 0.01; 10.0 vs 13.7, p < 0.01; respectively). BAI scores had a negative correlation with FSFI scores, however, BDI scores had not a significant correlation with FSFI scores in the present study (p < 0.01, correlation coefficient = –0.302; p = 0.07; correlation coefficient = –0.183; respectively). Conclusions: Pandemic seems not to affect female sexual behavior. However, the pandemic is associated with anxiety and depression.

İletişim teknolojilerinde yaşanan gelişmelerle birlikte iletişim biçimimizi kökten değiştiren sosyal ağlar, işletmeler tarafından rakiplerinden ayrışmak ve doğrudan hedef kitleye ulaşmak için bir reklam aracı olarak kullanılmaktadır. Sosyal medya reklamları, işletmelerin bilinirliliğini arttırması ve hedef kitleden geri dönüş almaları açısından önem arz etmektedir. Öte yandan sosyal medyada reklamveren işletmeler için tüketici satın alma davranışlarını bilmeleri başarılı olmalarının ön şartını oluşturmaktadır. Sosyal medya reklamlarının genç tüketicilerin satın alma niyetleri üzerinde etkili olup olmadığını Teknoloji Kabul Modeli ile incelemeyi amaçlayan bu araştırma, 450 üniversite öğrencisiyle gerçekleştirilmiştir. Çalışmada yirmi altı tane araştırma sorusu oluşturulmuş ve ardından hipotezleri test etmek amacıyla regresyon analizi uygulanmış ve veriler yorumlanmıştır. Ulaşılan sonuçlara göre, örneklem dahilindeki üniversiteli gençlerin sosyal medya reklamlarını faydalı, kullanışlı ve güvenilir bulmaları satın almaya yönelik tutum ve niyetlerinin olumlu olmasına, tutum ve niyetlerinin olumlu olmasının ise satın alma davranışları gerçekleştirmelerine sebep olmaktadır. Ayrıca işletmelerin reklamlarda doğru ve açıklayıcı bilgiler sunmalarının, tüketicilerin güvenini kazanmaları açışından gerekli olduğu sonucuna varılmıştır. Social networks, which have radically changed our communication style with the developments in communication technologies, are used by businesses as an advertising tool to differentiate from their competitors and directly reach the target audience. In addition, social media advertisements are important in terms of increasing awareness of businesses and gaining return from the target audience. On the other hand, knowing consumer purchasing behavior is a prerequisite for advertiser businesses to be successful in social media. Twenty-six research questions were created in the study, and then, by testing the hypotheses, regression analysis was applied to test the hypotheses, and the data were interpreted. The results obtained result in the fact that university students in the sample find social media advertisements useful, useful and reliable, have positive attitudes and intentions towards purchasing, and positive attitudes and intentions cause them to perform purchasing behaviors. In addition to provide accurate and descriptive information in advertisements.

Bu çalışmanın amacı, Eskişehir’in turistik çekim unsurlarının yerel basında okuyucuya nasıl aktarıldığının belirlenmesidir. Bu kapsamda yerel gazetelerde çıkan turizm içerikli haberler ve köşe yazıları, yerel gazetelerin web sayfaları üzerinden araştırmacılar tarafından incelenmiştir. Gazetelerde turizm ile ilgili ele alınan yazıların türü, kökeni ve haber kaynakları detaylı bir biçimde irdelenmiştir. Benzer bir biçimde turizmle ilgili yazıların teması ve alt konuları belirlenmiş , bu yazıların bireyleri destinasyona çekecek unsurları içerip içermediği araştırılmıştır. Çalışmada nitel araştırma yaklaşımlarından biri olan doküman taramasından yararlanılmıştır. Bu kapsamda Eskişehir ilinde çıkarılan yerel gazeteler araştırmacılar tarafından belirlenmiş ve toplamda sekiz yerel gazeteye ulaşılmıştır. Bu gazeteler; İstikbal, Eskişehir Anadolu, Sakarya, 2 Eylül, Milli İrade, Sonhaber, Şehir ve Yenigün şeklinde sıralanmaktadır. Bu gazetelerden Şehir ve İstikbal gazetelerinin web sayfalarının arama özelliği olmamasından dolayı araştırma kapsamından çıkarılmış ve araştırmaya diğer altı gazete üzerinden devam edilmiştir. Bu altı gazete üzerinden ‘’haberlerin yayın sayıları, ‘’yayın türü’’, ‘’kökeni’’, ‘’bilgi kaynağı’’, ‘’haber içeriklerinin niteliği’’, ‘’görsel malzemelerin sunumu’’ ve ‘’Eskişehir’in çekicilikleri’’ olmak üzere yedi değişken kapsamında turizm yazıları içerik analizine tabii tutulmuştur. Toplamda 535 turizm yazısı incelenmiştir. Yapılan içerik analizi sonucunda kamu kurumlarının, Eskişehir turizmi için en önemli bilgi kaynakları olduğu görülmüştür. Bu noktada özel sektörün Eskişehir turizmiyle ilgili yapılan haberlere bilgi kaynağı olabilme rolünün oldukça kısıtlı olduğu söylenebilir. Diğer yandan yazılan haberlerin içeriğinin, ‘’ümit veren’’ ve ‘’bilgi veren’’ özellikte olduğu belirlenmiştir.

Türk turizm tarihinin, modern anlamda, 1863yılında gerçekleşen Sergi–i Umumi–i Osmani ile başladığı ifade edilebilir (Özdemir 2011: 88). Bu serginin yapıldığı yıldan günümüze değin Türk turizmi ile ilgili birçok süreli yayının çıktığı görülmektedir. Ancak, modern anlamda nitelendirilenTürk turizm tarihinin bu 155 yıllıkserüveninde çıkan süreli yayınların devamlılığı konusunda sorunların yaşandığı da bilinen bir durumdur. Kurumlar tarafından çıkan süreli yayınların ömürleri ya o zamanki yöneticilerinin değişmesi ya da kurumların maddi tasarruflara gitmesiyle genellikle son bulmuştur.

Images of La-exchanged NaY zeolite obtained with aberration-corrected scanning transmission electron microscopy (STEM) show that about 80% of the La cations were present as site-isolated species, with the remainder in pair sites. The observed distances between La cations in the pair sites ranged from 1.44 to 3.84 A, consistent with the presence of pairs of cations tilted at various angles with respect to the support surface. The actual distance between La cations in the pair sites is inferred to be approximately 3.84 A. The results suggest the presence of dimeric structures of La cations bridged with O anions, and the presence of such species has been inferred previously on the basis of X-ray photoelectron spectroscopy (W. Grunert, U. Sauerlandt, R. Schlogl, H.G. Karge, J. Phys. Chem., 97 (1993) 1413).

Agglomerative sintering of an atomically dispersed, zeolite Y-supported catalyst, Ir1/zeolite Y, formed initially from the well-characterized precatalyst [Ir(C2H4)2]/zeolite Y and in the presence of liquid-phase reactants, was monitored over three cycles of 3800 turnovers (TTOs) of cyclohexene hydrogenation at 72 °C. The catalyst evolved and sintered during each cycle, even at the relatively mild temperature of 72 °C in the presence of the cyclohexene plus H2 reactants and cyclohexane solvent. Post each of the three cycles of catalysis, the resultant sintered catalyst was characterized by extended X-ray absorption fine structure spectroscopy and atomic-resolution high-angle annular dark-field scanning transmission electron microscopy. The results show that higher-nuclearity iridium species, Irn, are formed during each successive cycle. The progression from the starting mononuclear precursor, Ir1, is first to Ir∼4–6; then, on average, Ir∼40; and finally, on average, Ir∼70, the latter more accurately descri...

Bu çalışma, A ve B kişilik tiplerinin boş zaman davranışlarının kıyaslanmasını amaçlamaktadır. Çalışma kapsamında A ve B kişilik tiplerinin hangi güdülerle boş zaman aktivitelerine yöneldiği ve hangi boş zaman aktivitelerini tercih ettiği araştırılmıştır. Araştırmaya konu olan veriler, 11 Mayıs-15 Haziran 2015 tarihleri arasında Eskişehir ilinin Odunpazarı ve Tepebaşı ilçelerinde yer alan boş zaman hizmeti sunan mekânlardan anket tekniği ile elde edilmiştir. Yapılan analizler sonucunda A ve B kişilik tiplerini boş zaman aktivelerine katılmaya güdüleyen altı faktör; sosyalleşme, kişisel gelişim ve başarma, rekabet, yenilenme ve rahatlama, kaçış ve keşfetme olarak belirlenmiştir. Rekabet faktörünün kişilik tipine göre farklılaştığı, ayrıca A ve B kişilik tiplerinin katılmayı tercih ettiği boş zaman aktivitelerinin farklı olduğu ortaya çıkarılmıştır. Çalışmanın sonuçlarının; boş zaman endüstrisinde faaliyet gösteren işletmelere; pazarlama karması oluşturmada, ürettikleri mal ve hizmetlerin planlanmasında ve tanıtılmasında yol gösterici olması beklenmektedir., The present research aims to compare the leisure activities of A and B type personalities. In this regard, leisure motivations and activity choices of A and B type personalities were investigated in this study. Questionnaires were collected from places offering leisure services in Odunpazarı and Tepebaşı districts of Eskişehir, between May 11th, 2015 and June 15th,, 2015. Factors, motivating the A and B type personalities to attend certain types of leisure activities were named as; Socialization, Personal Growth and Success, Competition, Renewal and Relaxation, Escaping and Discovery. Competition factor differed according to the personality type of the individual. Furthermore, it was determined that leisure activities that A and B personalities chose to attend were different.

Size, shape, nuclearity: Aberration-corrected scanning transmission electron microscopy was used to determine the 3D structures of MgO-supported Os3, Os4, Os5, and Os10 clusters, which have structures nearly matching those of osmium carbonyl compounds with known crystal structures. The samples are among the best-defined supported catalysts.

Z-contrast imaging in an aberration-corrected scanning transmission electron microscope can be used to observe and quantify the sizes, shapes, and compositions of the metal frames in supported mono-, bi-, and multimetallic metal clusters and can even detect the metal atoms in single-metal-atom complexes, as well as providing direct structural information characterizing the metal–support interface. Herein, we assess the major experimental challenges associated with obtaining atomic resolution Z-contrast images of the materials that are highly beam-sensitive, that is, the clusters readily migrate and sinter on support surfaces, and the support itself can drastically change in structure if the experiment is not properly controlled. Calibrated and quantified Z-contrast images are used in conjunction with ex situ analytical measurements and largerscale characterization methods such as extended X-ray absorption fine structure spectroscopy to generate an atomic-scale understanding of supported catalysts and their function. Examples of the application of these methods include the characterization of a wide range of sizes and compositions of supported clusters, primarily those incorporating Ir, Os, and Au, on highly crystalline supports (zeolites and MgO).

Bu çalışmada, farklı rekreasyon aktivitelerine katılan rekreasyonistlerin örtük liderlikle ilgili algılarının belirlenmesine çalışılmaktadır. Çalışmanın sonuçları, rekreasyon aktivitelerinde liderlik yapan bireylerin, rekreasyonistlerin beklentileri doğrultusunda liderlik sürecini planlayabilmeleri açısından önemlidir. Nicel araştırma yönteminin kullanıldığı bu çalışmada, veriler anket aracılığıyla toplanmıştır. Veriler, 05.07.2016 ile 20.10.2016 tarihleri arasında ‘’rekreasyon’’ ve ‘’boş zaman’’ ismiyle oluşturulan sosyal medya gruplarından anket tekniği ile elde edilmiştir. Verilerin analiz edilmesinde, faktör analizi, tek yönlü varyans analizi ve T testinden yararlanılmıştır. Örtük liderlik algısına yönelik faktörlerin belirlenmesinde alanyazından sağlanan; beceriklilik, duyarlılık, kişisel ahlak ve güç faktörleri kullanılmıştır. Örtük liderlikte, başta beceriklilik faktörü olmak üzere sırasıyla duygusallık, kişisel ahlak ve güç faktörlerinin önemli olduğu belirlenmiştir. Ayrıca, açık ve kapalı alan aktivitelerine katılan rekreasyonistlerin beceriklilik, duyarlılık ve kişisel ahlak faktörlerinde, kadın ve erkek rekreasyonistlerin beceriklilik, kişisel ahlak ve güç faktörlerinde ve eğitim durumuna göre rekreasyonistlerin ise beceriklilik, duyarlılık ve güç faktörlerinde farklılaştığı gözlenmiştir., The purpose of this study is to determine the perceptions of recreationalists who attend to different recreational activities on implicit leadership. The results of the study are important for the individuals who lead the recreational activities to plan the leadership process in the direction of the recreationalist’s expectations. The quantitative research method was performed and the survey technique was used for data collection. The questionnaires were collected from different activity groups in the social media entitled ‘’recreation’’ and ‘’leisure time.’’ The data were collected by sending survey questionnaire to social media and receiving the answers during a specified period between 05.07.2016 and 20.10.2016. Factor analysis, one way analysis of variance and T test were applied for analyzing the data. Factors such as versatility, sensitivity, personal morality, and strength are used in determining the implicit leadership perception. It has been concluded that sensitivity, personal morality, strength factors as well as versatility factors are important in the implicit leadership. It has also been observed that recreationists who participate in outdoor and indoor activities differ in their versatility, sensitivity, and personal morality factors. While male and female recreationalists differ in versatility, personal ethics and power factors, they also differ in their versatility, sensitivity and power factors according to their educational background.

Results from a wide selection of literature sources reviewed here show that treatments of iridium complexes on various supports under harsh reductive conditions (e.g., 873 K in H2) lead to the formation of only uniform iridium clusters limited to a critical diameter of ~1 nm. The observations have been explained by the results of calculations at the level of density functional theory ory showing that cubic structures of this size are resistant to aggregation because coalescence of two such clusters would require energetically unfavorable rearrangements of their surface atoms, and this point has been reinforced by scanning transmission electron microscopy images demonstrating the non-coalescence behavior of iridium clusters of the critical size—which instead bounce off each other. Here we consider supported iridium catalysts in light of the literature, aiming to (1) demonstrate the generality of the sinter-resistant property of iridium nanoclusters (in contrast to those of other noble metals) and (2) summarize information regarding sample synthesis and preparation methods that lead to supported iridium catalyst with sinter-resistant properties.

The conversion of guaiacol catalyzed by Pt/MgO in the presence of H2 was investigated with a flow reactor at 573 K and 140 kPa. Among the dozens of reaction products identified by gas chromatography (GC) and GC/mass spectrometry, the predominant ones were phenol, catechol, and (surprisingly) cyclopentanone, with others including methane, n-butane, butenes, n-pentane, and carbon monoxide. The predominant reactions were hydrodeoxygenation (with about 70 % of the guaiacol that was converted forming products that were reduced in oxygen). In contrast, when the catalyst incorporated an acidic support, Pt/γ-Al2O3, other reactions became kinetically significant, exemplified by transalkylation, and the selectivity to deoxygenated products was reduced to about half the value observed with Pt/MgO at guaiacol conversions in the range of about 6–20 %. Pt/MgO underwent deactivation less rapidly than Pt/γ-Al2O3, consistent with a lower rate of coke formation and with observations by scanning transmission electron microscopy showing that the average platinum cluster diameter, approximately 1–2 nm in each catalyst, did not change significantly during operation. The results point to the advantages of basic supports for noble metal hydrodeoxygenation catalysts. .

This work addresses the question of what is the true catalyst when beginning with a site-isolated, atomically dispersed precatalyst for the prototype catalytic reaction of cyclohexene hydrogenation in the presence of cyclohexane solvent: is the atomically dispersed nature of the zeolite-supported, [Ir(C2H4)2]/zeolite Y precatalyst retained, or are possible alternatives including Ir4 subnanometer clusters or larger, Ir(0)n, nanoparticles the actual catalyst? Herein we report the (a) kinetics of the reaction; (b) physical characterizations of the used catalyst, including extended X-ray absorption fine structure spectra plus images obtained by high-angle annular dark-field scanning transmission electron microscopy, demonstrating the mononuclearity and site-isolation of the catalyst; and the (c) results of poisoning experiments, including those with the size-selective poisons P(C6H11)3 and P(OCH3)3 determining the location of the catalyst in the zeolite pores. Also reported are quantitative poisoning experime...

Supported triosmium clusters, formed from Os3(CO)12 on MgO, were treated in helium at 548 K for 2 h, causing fragmentation of the cluster frame and the formation of mononuclear osmium dicarbonyls. The cluster breakup and the resultant fragmented species were characterized by infrared and X-ray absorption spectroscopies, and the fragmented species were imaged by scanning transmission electron microscopy. The spectra identify the surface osmium complexes as Os(CO)2{Osupport}n (n = 3 or 4) (where the braces denote support surface atoms). The images show site-isolated Os atoms in mononuclear osmium species on MgO. The intensity analysis on the images of the MgO(110) face showed that the Os atoms were located atop Mg columns. This information led to a model of the Os(CO)2 on MgO(110), with the distances approximated as those determined by EXAFS spectroscopy, which are an average over the whole MgO surface; the results imply that these complexes were located at Mg vacancies.

Zeolite HSSZ-53, which has 1-dimensional channels with 14-ring extra-large pores, was used as a support for a molecular iridium complex synthesized from Ir(C2H4)2(C5H7O2) and characterized with infrared (IR) and extended X-ray absorption fine structure (EXAFS) spectroscopies and atomic-resolution aberration-corrected scanning transmission electron microscopy (STEM). The spectra show that Ir(C2H4)2(C5H7O2) reacted readily with the bridging OH groups of the zeolite, leading to the removal of C5H7O2 ligands and the formation of mononuclear Ir(C2H4)2 complexes bonded to the zeolite by Ir–O bonds at the framework aluminum sites. STEM images confirm the spectra, showing site-isolated iridium centers within the zeolite channels, with no evidence of iridium clusters. The samples constitute a highly uniform, well-defined array of essentially molecular catalytic species in a highly uniform, confined environment, allowing precise investigations of the chemistry of the iridium complex in the absence of solvents. IR s...

The formation of iridium clusters from supported mononuclear iridium complexes in H(2) at 300 K and 1 bar was investigated by spectroscopy and atomic-resolution scanning transmission electron microscopy. The first steps of cluster formation from zeolite-supported Ir(C(2)H(4))(2) complexes are triggered by the activation of H(2) and the formation of iridium hydride, accompanied by the breaking of iridium-support bonds. This reactivity can be controlled by the choice of ligands on the iridium, which include the support.

Using aberration-corrected scanning transmission electron microscopy (STEM), we imaged iridium atoms in isolated iridium complexes in the one-dimensional nonintersecting 14-ring channels of zeolite SSZ-53. STEM allows tracking of the movement of atoms in the channels, demonstrating the interaction of iridium with the zeolite framework (channel confinement) and providing a direct visualization of the initial steps of metal nanocluster formation. The results demonstrate how STEM can be used to help design improved catalysts by identifying the catalytic sites and observing how they change in reactive atmospheres.

By use of the precursor Ir(CO)2(acac) (acac is acetylacetonate), a ship-in-a-bottle synthesis was used to prepare Ir6(CO)16 and, by decarbonylation, clusters well approximated as Ir6 in the supercages of zeolite NaY. The samples were characterized by infrared and extended X-ray absorption fine structure (EXAFS) spectroscopies and imaged by aberration-corrected scanning transmission electron microscopy with a high-dose electron beam (∼108 e–/Ǻ2, 200 kV), and the catalyst performance was characterized by turnover frequencies for ethene hydrogenation at 298 K and atmospheric pressure. The images characterizing a sample with about 17% of the supercages occupied by decarbonylated nanoclusters indicated clusters well approximated as Ir6, with diameters consistent with such clusters, and some of the images show the clusters with atomic resolution and indicating each of the 6 Ir atoms. The cluster size was confirmed by EXAFS spectra. Two bonding positions of the Ir6 clusters in the supercages were distinguished; ...

The active sites of enzymes are contained within nanoscale environments that exhibit exquisite levels of specificity to particular molecules. The development of such nanoscale environments on synthetic surfaces, which would be capable of discriminating between molecules that would nominally bind in a similar way to the surface, could be of use in nanosensing, selective catalysis and gas separation. However, mimicking such subtle behaviour, even crudely, with a synthetic system remains a significant challenge. Here, we show that the reactive sites on the surface of a tetrairidium cluster can be controlled by using three calixarene–phosphine ligands to create a selective nanoscale environment at the metal surface. Each ligand is 1.4 nm in length and envelopes the cluster core in a manner that discriminates between the reactivities of the basal-plane and apical iridium atoms. CO ligands are initially present on the clusters and can be selectively removed from the basal-plane sites by thermal dissociation and from the apical sites by reactive decarbonylation with the bulky reactant trimethylamine-N-oxide. Both steps lead to the creation of metal sites that can bind CO molecules, but only the reactive decarbonylation step creates vacancies that are also able to bond to ethylene, and catalyse its hydrogenation.

Zeolite Hβ- and γ-Al(2)O(3)-supported mononuclear iridium complexes were synthesized by the reaction of Ir(C(2)H(4))(2)(acac) (acac is acetylacetonate) with each of the supports. The characterization of the surface species by extended X-ray absorption fine structure (EXAFS) and infrared (IR) spectroscopies demonstrated the removal of acac ligands during chemisorption, leading to the formation of essentially isostructural Ir(C(2)H(4))(2) complexes anchored to each support by two Ir-O(support) bonds. Atomic-resolution aberration-corrected scanning transmission electron microscopy (STEM) images confirm the spectra, showing only isolated Ir atoms on the supports with no evidence of iridium clusters. These samples, together with previously reported Ir(C(2)H(4))(2) complexes on zeolite HY, zeolite HSSZ-53, and MgO supports, constitute a family of isostructural supported iridium complexes. Treatment with CO led to the replacement of the ethylene ligands on iridium with CO ligands, and the ν(CO) frequencies of these complexes and white line intensities in the X-ray absorption spectra at the Ir L(III) edge show that the electron density on iridium increases in the following order on these supports: zeolite HYzeolite Hβzeolite HSSZ-53 ≪ γ-Al(2)O(3)MgO. The IR spectra of the iridium carbonyl complexes treated in flowing C(2)H(4) show that the CO ligands were replaced by C(2)H(4), with the average number of C(2)H(4) groups per Ir atom increasing as the amount of iridium was increasingly electron-deficient. In contrast to the typical supported catalysts incorporating metal clusters or particles that are highly nonuniform, the samples reported here, incorporating uniform isostructural iridium complexes, provide unprecedented opportunities for a molecular-level understanding of how supports affect the electronic properties, reactivities, and catalytic properties of supported metal species.

[EN] The performance of a supported catalyst is influenced by the size and structure of the metal species, the ligands bonded to the metal, and the support. Resolution of these effects has been lacking because of the lack of investigations of catalysts with uniform and systematically varied catalytic sites. We now demonstrate that the performance for ethene hydrogenation of isostructural iridium species on supports with contrasting properties as ligands (electron-donating MgO and electron-withdrawing HY zeolite) can be elucidated on the basis of molecular concepts. Spectra of the working catalysts show that the catalytic reaction rate is determined by the dissociation of H-2 when the iridium, either as mono- or tetra-nuclear species, is supported on MgO and is not when the support is the zeolite. The neighboring iridium sites in clusters are crucial for activation of both H-2 and C2H4 when the support is MgO but not when it is the zeolite, because the electron-withdrawing properties of the zeolite support enable even single site-isolated Ir atoms to bond to both C2H4 and H-2 and facilitate the catalysis., This research was supported by the DOE (Basic Energy Sciences, Contract FG02-04ER15513) (J.L. and C.A.). The research leading to these results has received funding from the European Union Seventh Framework Programme (FP7/2007-2013) under grant agreement no. PIOF-GA-2009-253129 (P.S.) We acknowledge beam time and the support of the DOE Division of Materials Sciences for its role in the operation and development of beamlines MR-CAT and Sector 9 at the Advanced Photon Source at Argonne National Laboratory. We thank Rodrigo Lobo-Lapidus, Tomohiro Shibata, and Trudy Bolin for valuable support.

Extended abstract of a paper presented at Microscopy and Microanalysis 2012 in Phoenix, Arizona, USA, July 29 – August 2, 2012.

Extended abstract of a paper presented at Microscopy and Microanalysis 2011 in Nashville, Tennessee, USA, August 7–August 11, 2011.

Rh(C2H4)2 complexes supported on HY zeolite selectively catalyze ethylene dimerization in the presence of H2, but iridium complexes anchored near the rhodium alter the selectivity by spilling over hydrogen that limits the adsorption of ethylene on Al–OH sites that act in concert with the rhodium sites, thereby triggering the rhodium complexes to operate as hydrogenation rather than dimerization catalysts.