Synthesis of niobium-alumina composite aggregates and their application in coarse-grained refractory ceramic-metal castables

Niobium-alumina aggregate fractions with particle sizes up to 3150 µm were produced by crushing pre-synthesised fine-grained composites. Phase separation with niobium enrichment in the aggregate class 45–500 µm was revealed by XRD/Rietveld analysis. To reduce the amount of carbon-based impurities, no organic additives were used for the castable mixtures, which resulted in water demands of approximately 27 vol.% for the fine- and coarse-grained castables. As a consequence, open porosities of 18% and 30% were determined for the fine- and coarse-grained composites, respectively. Due to increased porosity, the modulus of rupture at room temperature decreased from 52 MPa for the fine-grained composite to 11 MPa for the coarse-grained one. However, even the compressive yield strength decreased from 49 MPa to 18 MPa at 1300 °C for the fine-grained to the coarse-grained composite, the latter showed still plasticity with a strain up to 5%. The electrical conductivity of fine-grained composite samples was in the range between 40 and 60 S/cm, which is fifteen magnitudes above the values of pure corundum

Multiagent cooperation for solving global optimization problems: an extendible framework with example cooperation strategies

This paper proposes the use of multiagent cooperation for solving global optimization problems through the introduction of a new multiagent environment, MANGO. The strength of the environment lays in itsflexible structure based on communicating software agents that attempt to solve a problem cooperatively. This structure allows the execution of a wide range of global optimization algorithms described as a set of interacting operations. At one extreme, MANGO welcomes an individual non-cooperating agent, which is basically the traditional way of solving a global optimization problem. At the other extreme, autonomous agents existing in the environment cooperate as they see fit during run time. We explain the development and communication tools provided in the environment as well as examples of agent realizations and cooperation scenarios. We also show how the multiagent structure is more effective than having a single nonlinear optimization algorithm with randomly selected initial points

Industrial Designers in UX Practice: Motivations, Professionalization, and the Construction of Designer Identity

Our article discusses the insights from original research conducted with design practitioners to better understand the experiences of industrial design graduates as they are adopting new professional roles in user experience (UX) affiliated positions. We utilize narrative identity work as the theoretical frame to interpret the legitimation strategies of industrial designers while grounding their motivations, perceived competence, and fitness to a UX position. Such narratives support our arguments on the conscious efforts of designers toward the construction of a professional designer identity, which is stimulated by this role change

Erkek köpeklerde intratestiküler gliserol ve etanol uygulamalarının kısırlaştırma üzerine etkilerinin karşılaştırılması (Comporation of the Effects of Intratesticular Glycerol and Ethanol Injections on Sterilization of Male Dogs)

This study was conducted to investigate the effects of intratesticular glycerol and ethanol injection on sterilization. Twelve mature male dogs were used. They were allocated randomly to two equal groups called glycerol and ethanol and one ml glycerol (70%) and ethanol (95%) was injected intratesticularly. The animals were observed during two months. The blood and sperm samples obtained once a week in all groups were examined regarding to serum testosterone level and spermatozoon concentration and motility rate. There was a fistula formation and scrotal wounds resulting from orchitis in all glycerol and two ethanol group dogs after the 5th day of injection. The fistular openings closed spontaneously in all cases in due course. After the 2nd month, testicular atrophy was seen to occur. It was determined the presence of marked decreases (p<0.01) in both groups spermatozoon concentration and motility as well as in the level of serum testosterone two weeks after drug injection. The histopathologic examination conducted after the 2nd month revealed degeneration, necrosis and diffuse connective tissue proliferation in the seminiferus contortus tubulus of both groups. It has been concluded that glycerol and ethanol can be effective for sterilization in male dogs

Coarse‐Grained Refractory Composite Castables Based on Alumina and Niobium

Niobium-alumina composite aggregates with 60 vol% metal content and with particle sizes up to 3150 μm are produced using castable technology followed by sintering, and a crushing and sieving process. X-Ray diffraction (XRD) analysis reveals phase separation during crushing as the niobium:corundum volume ratios is between 37:57 and 64:31 among the 4 produced aggregate classes 0–45, 45–500, 500–1000, and 1000–3150 μm. The synthesized aggregates are used to produce coarse-grained refractory composites in a second casting and sintering step. The fine- and coarse-grained material shows porosities between 32% and 36% with a determined cold modulus of rupture of 20 and 12 MPa, and E-moduli of 37 and 46 GPa, respectively. The synthesized fine-grained composites reached true strain values between 0.08 at 1100 °C and 0.18 at 1500 °C and the coarse-grained ones values between 0.02 and 0.09. The electrical conductivity for the fine-grained and the coarse-grained material is 448±66 and 111±25  S cm$^{−1}$, respectively

Waterpipe (narghile) smoking among medical and non-medical university students in Turkey

Objectives. This investigation was performed in order to determine the prevalence rate of waterpipe smoking in students of Erciyes University and the effects of some socio-demographic factors