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Intercity travel is one of the most important parameters for combating a pandemic. The ongoing COVID-19 pandemic has resulted in different computational studies involving intercity connections. In this study, the effects of intercity connections during an epidemic such as COVID-19 are evaluated using a new network model. This model considers the actual geographic neighborhood and population density data. This new model is applied to actual Turkish data by the means of provincial connections and populations. A Monte Carlo algorithm with a hybrid lattice model is applied to a lattice with 8,802 data points. Results show that this model is quantitatively very efficient in modeling real world COVID-19 epidemic data based on populations and geographical intercity connections, by the means of estimating the number of deaths, disease spread, and epidemic termination., 10 pages, 7 figures

Üç farklı kompozisyona sahip SiAlON seramikleri ile saf demir ve dört ayrı tipteki çelik arasında meydana gelen kimyasal etkilesim; statik etkilesim çifti deneyleri yoluyla incelenmistir. Etkilesim çifti deneyleri; $10^{-2}$mbar vakum altında, 1150°C’de 5-7MPa yük kullanılarak 15 saat süreyle gerçeklestirilmistir. Etkilesime giren seramik-metal çiftlerinin ara yüzeyleri optik ve taramalı elektron mikroskobunda (SEM) incelenmis, enerji saçınımlı X-ısını spektrometresi (EDX) ile analiz edilmistir. Bu çalısmada, seramik kompozisyonunun ve alasım elementlerinin kimyasal reaktiviteye etkisi; etkilesim bölgeleri belirlenerek incelenmis, SiAlON seramiklerinin çelik tipine bağlı olarak difüzivite eğilimleri karsılastırılmıs ve sonuçlar ayrıntılı olarak tartısılmıstır., The chemical interaction between SiAlON ceramics in three different compositions and four different types of steel and also pure iron as reference, were investigated by means of static interaction couple experiments. The tests were carried out in $10^{-2}$mbar vacuum at 1150°C, under the pressure of 5-7MPa for 15 hours. Interfaces of reacted couples were analysed by optical and scanning electron microscope (SEM) including energy-dispersive X-Ray spectroscopy (EDX). In this study, the effects of alloying elements in steel and starting compositions of SiAlON on the chemical reactivity were investigated by comparing the tendency of diffusivity of SiAlON ceramics according to steel type and discussed in detail by determining the interaction zones.

Bu çalışmada, farklı α:β faz oranına, kırılma tokluğuna ve sertliğe sahip gaz basınçlı sinterlenme (GPS) ve basınçsız sinterleme (PLS) ile üretilmiş SiAlON seramiklerinin tribolojik davranışı incelenmiştir. SiAlON seramiklerinin tribolojik özellikleri ticari SiAlON bilye kullanılarak yağlayıcı kullanmaksızın test edilmiştir. Triboloji testleri sonrasında sürtünme katsayısının dar bir aralıkta (0.590.64) değiştiği ve aşınma oranının 10-5-10-6 mm3/N.m arasında olduğu görülmüştür. Mevcut test koşulları için malzemelerin kırılma tokluğu, sertlik ve mikroyapı tribolojik davranış ilişkisi açıklanmıştır. SiAlON seramiklerinin aşınma davranışı üzerine mikroyapının en fazla etkisi olduğu görülmüştür. Sonuç olarak gaz basınçlı sinterleme tekniğine göre daha ekonomik üretim tekniği olan basınçsız sinterleme ile üretilmiş SiAlON seramiklerinin aşınma uygulamalarında potansiyel olabilecekleri ve böylece SiAlON seramiklerinin kullanım alanlarının artacağı düşünülmektedir

WOS: 000302846400001, …

ß SiAlON ceramics were produced from different starting Si3N4 powders including P-Si3N4 and ?-Si3N4 powders and mixtures of these powders. Gas pressure sintering was used for sintering. After sintering, resultant fracture toughness values were correlated with microstructure and starting powders. By optimizing chemistry and process parameters; ?-ß SiAlON ceramics with reasonable fracture toughness can be produced from rather coarse ß-Si 3N4 powder. This could improve the economic viability of SiAlON ceramics since ß-Si3N4 powders are less costly.

2nd International Symposium on SiAIONs and Non-Oxides -- DEC 02-05, 2007 -- Mie, JAPAN, WOS: 000266237700028, alpha-beta SiAlON ceramics were produced from different starting Si3N4 powders including beta-Si3N4 and alpha-Si3N4 powders and mixtures of these powders. Gas pressure sintering was used for sintering. After sintering, resultant fracture toughness values were correlated with microstructure and starting powders. By optimizing chemistry and process parameters; alpha-beta SiAlON ceramics with reasonable fracture toughness can be produced from rather coarse beta-Si3N4 powder. This could improve the economic viability of SiAlON ceramics since beta-Si3N4 powders are less costly., Japan Soc Promot Sci, Yokohama Natl Univ, JSPS 124th Comm, Hosokawa Power Technol Fdn

SACMI;Iris Ceramica;SITI - B and T Group;Element Six;Corning, 2nd International Congress on Ceramics, ICC 2008 -- 29 June 2008 through 4 July 2008 -- Verona -- 94842, As long as fossil fuels are being used as the primary energy source, the world will face great environmental problems and the development of ceramic technology may be the key for the solution. Environmental ceramics especially ceramic supports, filters and substrates will have increasing attention in the next years due to the new regulations for automobile emissions and industrial gases.

Scientific and Technological Research Council of Turkey, 5th International Symposium on Nitrides -- 3 April 2006 through 5 April 2006 -- Eskisehir -- 71251, In this study, effect of seed addition on the microstructural development of Y-Sm ?-SiAlON system has been investigated. Besides using pre-produced rod-like ?-SiAlON seeds, growth in the glassy phase and harvested by chemical treatment, powdered Y-Sm/?-SiAlON was also used as nuclei. Microstructural results of both systems were compared with un-seeded samples. It was found that the powdered ?-SiAlON addition has also caused the acicular ?-SiAlON grain formation, which indicates the dominant effect of thermodynamic stability on the preferential growth of ?-SiAlON grains in the c direction.

Scientific and Technological Research Council of Turkey, 5th International Symposium on Nitrides -- 3 April 2006 through 5 April 2006 -- Eskisehir -- 71251, In this study, textured ?-SiAlON ceramic was produced by templated grain growth process. In order to enhance the alignment of the seeds, gated tape casting arrangement was utilized. Y-Ce codoped seeds were synthesized to induce the preferred orientation. For the production of the seeds, Ce3+ was used as a sintering additive due to its well-known effect on the formation of elongated ?-SiAlON grains. In addition, Y3+ was used to stabilize Ce3+ in ?-SiAlON structure. Gated tape casting arrangement was also used to enhance the alignment of the seeds in the green tape. After the lamination and sintering, preferentially aligned ?-SiAlON grains were observed by the microstructural investigation. In addition, XRD results obtained from the planes parallel and perpendicular to the casting direction indicated the alignment of grains in ?-SiAlON ceramics. Hardness measurements also confirmed that the alignment of the grains results in 8% increase in hardness value of the plane perpendicular to the casting direction with respect to that of the parallel one.

8th Conference of the European-Ceramic-Society -- JUN 29-JUL 03, 2003 -- Istanbul, TURKEY, WOS: 000223059700264, In the present work, stabilization of MgO and CeO2 in alpha-SiAlON structure is studied. Mg and CeO2 were used in 50:50 molar ratios as additives. The mixture was sintered at 1830degreesC for 1 hour in gas pressure sintering furnace (GPS). The results show that sintered sample was composed of alpha-SiAlON and beta-SiAlON phases. According to X-ray diffraction (XRD) and energy dispersive X-ray measurements (EDX) analyses, Mg and Ce cation could be incorporated into alpha-SiAlON structure higher than single R cation (R=Mg or Ce) doped compositions., Turkish Ceram Soc, European Ceram Soc

Turkish Ceramic Society;European Ceramic Society, Proceedings of the 8th Conference and Exhibition of the European Ceramic Society -- 29 June 2003 through 3 July 2003 -- Istanbul -- 63890, In the present work, stabilization of MgO and CeO2 in ?-SiAlON structure is studied. Mg and CeO2 were used in 50:50 molar ratios as additives. The mixture was sintered at 1830°C for 1 hour in gas pressure sintering furnace (GPS). The results show that sintered sample was composed of ?-SiAlON and ß-SiAlON phases. According to X-ray diffraction (XRD) and energy dispersive X-ray measurements (EDX) analyses, Mg and Ce cation could be incorporated into ?-SiAlON structure higher than single R cation (R=Mg or Ce) doped compositions.

4th International Symposium on Nitrides -- NOV 17-19, 2003 -- Mons, BELGIUM, WOS: 000223970800007, In the present study, pressureless joining of gas pressure sintered (alpha-beta)-SiAlON ceramics to pyrex glass was investigated. Preoxidized SiAlON ceramics were used to enhance wettability and provide chemical compatibility of the components. Microstructure and chemistry of the joints were characterised by scanning electron microscopy (SEM) in combination with energy dispersive X-ray (EDX) spectroscopy. It was shown that chemical reactions took place at the interface region of the joined samples and as a result, phases were formed such as Y-aluminium silicate and cristobalite. Considering the well-known phase transformations of cristobalite at around 210degreesC, further studies were also undertaken to avoid cristobalite formation during joining.

4th International Symposium on Nitrides -- NOV 17-19, 2003 -- Mons, BELGIUM, WOS: 000223970800017, Due to the favorable properties possessed by novel alpha-beta SiAlONs, they are attractive materials for cutting tool applications. Such applications require materials with high hardness, high fracture toughness and high strength. The present study reports on a preliminary investigation involving the production of alpha-beta SiAlON composites with the incorporation of TiN (ranging from 0 to 30-wt %) and TiCN (ranging from 0 to 10-wt %) by gas pressure sintering at 1920degreesC. The resultant microstructures were investigated using XRD and SEM techniques. Additionally, Vickers hardness and fracture toughness of the representative samples were measured. It was shown that dense composites could be obtained by choosing a right amount of additions.