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In this study, nanostructured WC-12Co powder was produced by ball milling and then agglomerating by spray drying. The produced nanostructured WC-12Co powder was used for laser cladding of AISI 321 stainless steel substrate. In order to evaluate the effect of argon shroud protection, the cladding process was performed with and without argon shroud protection. Microstructural and phase characterization showed that argon shroud protection can reduce the WC decarburization and the relative fraction of WC phase in clads reached up to 74%. In addition, microhardness and porosity percentage of the clads with argon shroud protection showed a significant improvement in comparison with the clads without argon shroud protection. The microhardness (to 2200 HV) and wear resistance increased and the porosity percentage decreased to less than 1%.

International audience; Four D-π-A push–pull derivatives either based on a diphenylmethylamine or a 9-methylcarbazole electron-rich block (D), connected to a dicyanovinyl accepting moiety (A) through two different spacers (π), namely a thiophene or selenophene, were synthesized and characterized. These small and synthetically accessible molecules were indeed selected to rationalize the impact of both i) the rigidification of the arylamine part and ii) the nature of the π-spacer constituting heteroatom on the optical, electrochemical, charge transport and therefore photovoltaic properties

Two push–pull derivatives based on a N,N-bis(4-biphenylyl)aniline (BPA) donor block connected to a dicyanovinyl accepting moiety by thienyl and bithienyl π-conjugated spacers have been synthesized and characterized. All-small-molecule planar-heterojunction organic solar cells show promising power conversion efficiencies and impressive fill factor (>73%) correlated with the high hole-mobility induced by the BPA moiety.

International audience; The first synthesis of an original octamer consisting of a central polyhedral oligomeric silsesquioxane (POSS) cage decorated with electro- and optically active arylamine-based push–pull building-blocks is reported herein. Once fully characterized, the potential of the new compound was evaluated as donor material in bulk heterojunction organic solar cells. With promising power conversion efficiencies, good processability and film forming properties, such multimer architectures turns out to be potential candidates to bridge the gap between small molecules and polymers.

International audience; Two push-pull molecules involving a triarylamine donor unit connected to a dicyanovinyl acceptor moiety by a difluorobenzothiadiazole-thienyl block have been synthesized. In order to simplify the synthesis, avoid intermediate halogenation reactions and the formation of toxic organometallic by-products, building blocks were connected by direct (hetero)-arylation. The optimization of the experimental conditions of the coupling reactions is thus reported herein as well as the preliminary evaluation of the potential of the target compounds as active material in simple air-processed organic solar cells.

A kinetic study of lean methane combustion on a silica-encapsulated bimetallic Pd–Pt (1:1 molar ratio) catalyst at varying methane concentrations and temperatures and in the absence/presence of added water is presented. With dry feed, the kinetic behavior of the bimetallic catalyst is correlated using a previously reported rate expression that is first order in methane and negative one order in water. The model does not adequately correlate the conversion of wet lean CH4 combustion in the temperature range of 550 to 750 K. For wet conditions, an alternative mechanism is suggested that is based on the previous experimental observations of the prevailing chemical state of Pd in wet feed, the ability of Pt to activate methane in oxygen-deficient atmospheres, and the inhibitory effect of water on the support-mediated oxygen exchange. The corresponding rate expression successfully predicts the activity of the silica-encapsulated Pd–Pt catalyst with wet feed (5 vol % water) in the temperature range of 550 to 75...

High-loading silica-encapsulated PdPt catalysts (PdPt@SiO2, 4 wt.% Pd, 7 wt.% Pt) are synthesized using a Stober-based method and are tested in lean methane combustion in the presence of water up to 550 °C. The as-synthesized bimetallic core particles have an average size of 7 nm, are uniform alloys of Pd and Pt, and are well-dispersed inside the oxide shells. The SiO2 shells are about 60 nm in diameter, with a specific surface area of 600 m2/g and a median pore diameter of 3.4 nm. The catalyst shows a stable methane conversion during a hydrothermal ageing (HTA) test which is two- and ten-fold higher than the conversion for the impregnated Al2O3 and SiO2-supported catalysts of the same metal loading, respectively. The surface area of the porous shell remains unaffected after HTA; however, the metal dispersion evaluated by CO chemisorption increases after the ageing and some changes in the morphology of the bimetallic PdPt nanoparticles occur.

The study focuses on the determination of metal site availability in silica-encapsulated Pd catalysts (Pd@SiO2). Existing synthetic methods are modified to achieve a high metal loading (up to 6 wt%) and porosity (surface area of 700 m2 g−1) while maintaining the original Pd nanoparticle size of 8 nm. Two synthesis schemes are used for encapsulating Pd NPs, and the resulting catalysts are assessed in lean methane combustion at up to 823 K. Application of poly(vinylpyrrolidone) (PVP) as a Pd particle stabilizer and a potential porogen alone is concluded to be inadvisable as it results in catalysts with a surface area of 70 m2 g−1 that show extremely low activity due to Pd inaccessibility. The high-surface area materials (700 m2 g−1) prepared via a separate introduction of PVP and an additional porogen (cetyltrimethylammonium bromide, CTAB) are active and exhibit the same turnover frequencies as the traditional catalysts but require smaller reactor sizes because of the high metal loading. However, 2/3 of the Pd nanoparticle surface is blocked by the shell material even in the highly porous catalysts. The silica-encapsulated catalysts, thus, offer advantages of high mass-based activity and sintering resistance of the metal cores, but their high porosity must be ensured for efficient mass transfer by the addition of a porogen (such as CTAB) during the Stober process. Above a certain limit, the increased amount of the porogen does not improve the metal accessibility and only leads to precious metal loss during synthesis.

The number of people who use computer for business purposes increases as technology grows. Application of ergonomics practices on computer workstations reduces musculoskeletal discomfort experienced and increased overall job satisfaction of the employees. Keyboards are available in various systems, computers to mobile devices, which have difference shapes and sizes. Keyboard size and shape is known to influence upper extremities. Alternative keyboard designs may prevent or reduce arm pain or disorders, and probably the mechanism is by reducing awkward arm postures. Previous researchers have put their effort on optimizing the character arrangement of the keyboard by taking into account the co-occurrence frequency of characters in words, typing ergonomics, and word disambiguation effectiveness. This research considers the frequency of appearance of the most used 3000 words in the English language. First, the text Analyzer calculates the frequency of each letter pair. Then, a genetic algorithm is applied to design an ergonomically optimized keyboard to minimize the total distance of finger travel among the selected alphanumeric characters. The results showed that the distance travelled obtained by the proposed keyboard layout is less than that for the QWERTY keyboard in all different types of texts, in which an average of 6.04% improvement was achieved. Therefore, the proposed design can be used for keyboards to reduce time and fatigue. Keywords: Keyboard design, Systematic layout planning, Genetic algorithm ÖZ: Teknoloji ilerledikçe iş amaçlı bilgisayar kullananan kişilerinde sayısı da artmaktadır. Bilgisayarlı iş istasyonlarında uygulanan ergonomik tasarımlar, yaşanan kas-iskelet sistemi rahatsızlıklarını azaltmakta ve çalışanların genel iş memnuniyetini artırmaktadır. Farklı şekil ve boyutlara sahip bilgisayarlardan mobil cihazlara kadar çeşitli sistemlerde klavyeler mevcuttur. Klavye boyutu ve şeklinin üst ekstremiteleri etkilediği bilinmektedir. Alternatif klavye tasarımları kol ağrısını veya bozukluklarını önleyebilir veya azaltabilir, ayrıca bu tasarımlar uygunsuz kol duruşlarını azaltmaktır. Literatürde kelimelerdeki karakterlerin bir arada bulunma sıklığı, yazma ergonomisi ve kelime belirsizliğini giderme etkinliğini dikkate alarak klavyenin karakter düzenlemesini optimize etmek için çalışmalar mevcutturr. Bu araştırma, İngilizcede en çok kullanılan 3000 kelimenin görülme sıklığını ele almaktadır. İlk olarak, metin çözümleyici her bir harf çiftinin frekansını hesaplandı. Ardından, seçilen alfasayısal karakterler arasında parmak hareketinin toplam mesafesini en aza indirmek için ergonomik olarak optimize edilmiş bir klavye tasarlamak için genetik bir algoritma uygulandı. Sonuçlar önerilen klavye düzeniyle elde edilen mesafenin tüm farklı metin türlerinde QWERTY klavyeden daha az olduğunu ve ortalama% 6,04'lük bir iyileştirmenin elde edildiğini göstermektedir. Bu nedenle önerilen tasarım, klavyeler için zamanı ve yorgunluğu azaltmak için kullanılabilir. Anahtar Kelimeler: Klavye tasarımı, Sistematik vaziyet planı, Genetik alogritma Doctor of Philosophy in Industrial Engineering. Thesis (Ph.D.)--Eastern Mediterranean University, Faculty of Engineering, Dept. of Industrial Engineering, 2020. Supervisor: Assoc. Prof. Dr. Orhan Korhan.

The synthesis, characterization and use of three donor-σ-acceptor molecular dyads as organic photoactive layer are reported herein. Based on push-pull π-conjugated systems, the donor moiety is connected through a non-conjugated σ-linker to a PC61BM derived block. Three different π-connectors, constituting the push-pull unit, namely a bithiophene (BT), a thienothiophene (TT) and a cyclopentadithiophene (CPDT) units were selected to assess the impact of the chemical bridging (CPDT) or fusing (TT) on the electronic, electrochemical and therefore photovoltaic properties. Hence through a better understanding of the structure-property relationships, power conversion efficiencies exceeding the symbolic percent have been reached in single-molecule organic solar cells.

National audience

This paper presents the preparation, characterization, and application of four different nanocomposites in photocatalytic degradation of the Brilliant Red M5B as a dye contaminant. Nanocomposites include ZnFe2O4, porous ZnFe2O4, ZnFe2O4–TiO2, and FeTiO3 prepared and coated on a glass slide by doctor blade method. Different techniques to characterize composites are X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM) and diffuse reflectance spectra (DRS). FESEM shows that nanocomposites are nanocrystallines and a narrow dispersion in size. XRD confirms that the prepared nanocomposites are composed of ZnFe2O4, FeTiO3 and TiO2. Degradation efficiency of composites is evaluated using Brilliant Red M5B as a model pollutant under UV irradiation with homemade photocatalytic apparatus. The results showed that the photocatalytic efficiency of ZnFe2O4–TiO2 is higher than that of other photocatalyst, which is mainly ascribed to ZnFe2O4 NPs with the spinel structure.

An efficient and scalable one-pot synthetic method to prepare nanostructure composite of ZnFe2O4–FeFe2O4–ZnO (ZFZ) has been investigated. This method is based on thermal decomposition of iron(III) acetate and zinc acetate in monoethanolamine (MEA) as a capping agent. Moreover, thermogravimetric analysis (TG-DTG) was performed to determine the temperature at which the decomposition and oxidation of the chelating agents took place. ZFZ was immobilized on glass using doctor blade method and calcinated at different temperatures. The properties of the ZFZ nanocomposite have been examined by different techniques, such as X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM) and diffuse reflectance (DRS). FESEM shows that nanocomposite is monocrystallines and a narrow dispersion in size of 48 nm. XRD confirms that the prepared nanocomposite is composed of franklinite, ZnFe2O4 (54%), magnetite, FeFe2O4 (8%) and wurtzite, ZnO (48%). Photocatalytic activity of ZFZ immobilized on glass was carried out by choosing an azo textile dye, Reactive Red 195 (F3B) as a model pollutant under UV irradiation with homemade photocatalytic apparatus and the results indicated that ZFZ exhibited good photocatalytic activity.

This research investigates the performance of a zinc ferrite (ZF) as working electrodes in a dye-sensitized solar cell (DSSC). This ZF working electrode was prepared by sol-gel and thermal decomposition of four different precursors including: zinc acetate dihydrate (Zn(CH3COO)2·2H2O), ferric nitrate nonahydrate (Fe(NO3)3·9H2O), iron(III) acetate; Fe(C2H3O2)3, and zinc nitrate hexahydrate, Zn(NO3)2·6H2O. The effects of annealing temperature and precursors on the structural, morphological, and optical properties were investigated. The field emission scanning electron microscope images (FESEM) and scanning electron microscopy (SEM) show that ZFe films are polycrystalline in nature and homogeneous with densely packed grains. Nanoporous zinc ferrite coatings were prepared by doctor blade technique on the fluorine-doped tin oxide (FTO) and used as working electrodes in DSSC. In all DSSCs, platinized FTO and [Co(bpy)3](2+/3+) in 3-methoxy proponitrile were used as counter electrode and redox mediator system respectively. Comparing the fill factors of four different zinc ferrite nanocomposites, the highest fill factor was for ZnFe2O4-TBL sample. Cell fabricated with ZnFeA working electrode shows relatively higher Jsc.

Zinc ferrite nanocomposite was synthesized via thermal decomposition of zinc acetate and iron nitrate at three different temperatures (350, 450, and 550 °C). The influence of the thermal decomposition of precursors on the formation zinc ferrites was studied by differential thermal gravimetry and thermogravimetry (TG). The TG curve shows two steps for the thermal decomposition with mass loss of 17.3 % at 78 °C and 63.3 % at 315 °C. The prepared zinc ferrites nanocomposite was characterized by X-ray diffraction and scanning electron microscopy. The X-ray diffractograms of ZnFe2O4 shows that a crystalline phase, spinel system is formed. SEM micrograph of the zinc ferrite nanocomposite indicates the formation of uniformly spherical 48-nm nanograins. The properties of the zinc ferrite phase were strongly dependent on their calcinations temperature and molar ratio of precursors.

The goal of this study was to define the differences between desktop computer users and laptop computer users. Also define the affection of working with computer on different body regions. A questionnaire prepared and published on a web site. 100 people filled it. The information of the questionnaire give important data about the work related musculoskeletal disorders. The questionnaire result showed that women have more disorders in their muscles. Also ache and pain is two important type of discomforts that most of the people fill them on their body regions. Neck, shoulder, upper back, lower back and hands recognized as a region with maximum risk for suffering to muscles disorders and elbows, hips\thighs\buttocks, knees and ankles\feet have been reported as a region with minimum pain. Electromyography tests have been done on 5 respondents. The experiments have been done on 6 different body regions for each of the respondents when they are working with a desk type computer and a laptop computer. Electromyography chart draw for each position. The chart analysis shows that desktop computer user and laptop computer user burden pressure when they are using computer. In some position showed that desktop computer respondents have more pressure than laptop computer respondents. Also sometimes the result for each of the respondent in a same position was different. But totally a significant pressure observed when the respondents working with laptop, especially in neck muscles. For analyzing of electromyography data used a hypothesis test. For each respondent for all of the body regions an ANOVA table prepared per working with desktop computer and laptop computer. In all of the tests, hypothesis test rejected and it shows that working with computer and laptop cause discomforts for all of the respondents in all of the body regions. In another ANOVA analysis, we studied the affection of using of desktop computer and laptop computer on each of the body regions for all of the respondents. The result shows that just in shoulder region when the respondents working with desktop computer we cannot say that it has affection, in other region for both of computer we ham significant disorders. Also we studied the interaction between type of computer and body regions. The ANOVA result showed that each of them did not have any affection on respondents but the interaction between them has a significant difference. Keywords: Musculoskeletal discomfort, Desktop computer and laptop computer use. …………………………………………………………………………………………………………………………………………………………………………………………………………………… ÖZ: Bu çalışmanın amacı, masaüstü bilgisayar kullanıcıları ve dizüstü bilgisayar kullanıcıları arasındaki farklılıkları tanımlamaktır. Ayrıca, bu çalışmanın bir digger amacı; vücudun farklı bölgelerini bilgisayar ile çalışma etkisini ortaya koymaktır. Bu çalışma için bir anket hazırlanmıştır ve bu anket bir web sitesinde yayınlanarak 100 kişi tarafından doldurulmuştur. Anket sonuçları; bilgisayar kullanımı esnaasındaki kas-iskelet bozuklukları ile ilgili önemli bilgiler vermektedir. Anket sonuçları, kadınlarda kas rahatsızlıklaırnın daha yaygın olduğunu göstermiştir. Ayrıca ağrı ve sızlamanın, değişik vücut noktalarında rastlanan en sık rahatsızlıklar olduğu saptanmıştır. Boyun, omuz, üst sırt, alt sırt ve dirseklerde kas rahatsızlıkları yaygın bir şekilde saptanırken, eller, kalça, diz ve ayak bileklerinde bu tür rahatsızlıklara pek de sık rastanılmamaktadır. 5 katılımcıya elektromiyografi testi yapılmıştır. Bu testler; masaüstü ve dizüstü bilgisayarlar kullanılarak, 6 değişik vücut bölgesinden kas hareketleri izlenerek gerçekleştirilmiştir. Her bir bölge için elektromiyografik grafik çizilmiştir. Grafik analizleri, masaüstü ve dizüstü bilgisayar kullanıcılarında ortaya çıkan baskıyı göstermektedir. Genellikle dizüstü kullanıcılarında kaslara daha çok yük yapıldığı ortaya konmuştur. Ayrıca bazen aynı pozisyonda her bir katılımcı için farklı sonuçlar elde edilmiştir. Katılımcılarda özellikle dizüstü bilgisayar ile çalışırken boyun kaslarında basınç gözlemlenmiştir. Elektromiyografik verilerin analiz edilmesi için bir hipotez testi kullanılmıştır. Her katılımcı için; masaüstü ve dizüstü bilgisayar kullanımında tüm vücut bölgeleri için bir ANOVA tablosu hazırlanmıştır. Tüm testlerde, hipotez reddedilmiştir. Bu da tüm katılımcılarda, tüm vücut noktalarında her hem masaüstü hem de dizüstü bilgisasyarın rahatsızlıklara yolaçtığı göstermektedir. Ayrıca bilgisayar ve vücut bölgeleri türü arasındaki etkileşim incelenmiştir. ANOVA sonucu her biri katılımcıda bilgisayar tipinin (masaüstü/dizüstü) ve vücut bölgesinin etkileşerek kas-iskelet sistemi rahatsızlıklarına yol açtığı ortaya konmuştur. Anahtar Kelimeler: Kas-iskelet rahatsızlıkları, masaüstü bilgisayar ve dizüstü bilgisayar. Master of Science in Industrial Engineering. Thesis (M.S.)--Eastern Mediterranean University, Faculty of Engineering, Dept. of Industrial Engineering, 2011. Supervisor: Assist. Prof. Dr. Orhan Korhan.

International audience