Detonation-Sprayed Coatings of (Ti,Cr)B2–NiAlCr Composite Materials II. Mechanical and Tribotechnical Properties

Powder Metallurgy and Metal Ceramics - The mechanical and tribotechnical properties of detonation-sprayed coatings produced from (Ti, Cr)B2–NiAlCr composites were studied. The influence of...     

Surface preparation for the application of hardening protective coatings

Conclusion Quantitative monitoring of the energy state of the treated surface made it possible to select the optimal treatment regime using SPD; this ensured an increase in the growth rate of the organometallic coating being applied and its adhesive strength.Moscow Automobile Traffic and Highway Construction Institute. Translated from Metallovedenie i Termicheskaya Obrabotka Metallov, No. 12, pp. 2–4, December, 1993.     

Temperature Dependence of Excited-State Proton Transfer and Geminate Recombination Processes in Water and in Glycerol-Doped Ice

The reversible proton dissociation and geminate recombination of photoacids was studied as a function of temperature in neat water, binary water mixture containing 0.6 mol% glycerol, and doped ice containing 0.6 mol% glycerol. The deuterium isotope effect on both condensed phases was also studied. 8-hydroxypyrene-1,3,6 trisulfonate trisodium salt was used as the electronically-excited-state proton emitter. The experimental data are analyzed by the Debye–Smoluchowski equation solved numerically with boundary conditions to account for the reversibility of the reaction. We propose a qualitative model to describe the unusual temperature dependence of the proton transfer rate in the liquid phase. We also propose a model for proton transfer in solid ice based on L-defects transport as proton acceptors. While in the liquid phase at t > 10°C the proton dissociation rate constant is almost temperature independent, in glycerol-doped ice we find a large temperature dependence.     

Effect of additives on the properties of silicon carbide-based refractories obtained by self-propagating high-temperature synthesis (SHS)

The effect of refractory additives (alumina, alumosilicate mortar, and zircon concentrate) on the properties of SHS refractories based on silicon carbide is studied. It is shown that introduction of the additives favors enhancement of the compressive strength of the material. The enhancement is especially efficient in the case of an admixture of zircon concentrate. The resistance of the silicon carbide material to corrosion in slags of titanium production and iron foundry production is improved when the content of the additives is increased from 5 to 30%. The addition of zircon concentrate allows the slag-resistance of the silicon carbide material to be increased by a factor of 6, while the effect of alumina and alumosilicate mortar is less pronounced. Translated from Ogneupory i Tekhnicheskaya Keramika, No. 1, pp. 17–18, January, 1997.     

Learning and engagement in a gamified course: Investigating the effects of student characteristics

The current study investigated college students' experiences of a gamified informatics course. We surveyed 139 students aged 18–31 years (M = 20 years, SD = 1.5) enrolled in an undergraduate informatics course focused on social networking technologies. Surveys were conducted at 3 time points during the course (beginning, middle, and end). Overall, we found positive trends with respect to students' perceptions of gamification's impact on their learning, achievement, and engagement in the course material. Although students who played and identified variously with recreational games were more alike than not, we did uncover one notable difference with respect to how students' gaming frequency impacted their engagement in the course. Nongamers expressed somewhat less motivation to do well in the course than frequent gamers. For all other measures of engagement, however, nongamers appeared to be equally engaged by the gamified format of the course as gamers. There were virtually no differences between male and female students' perceptions of gamification. This study contributes new insight into the conditions under which gamification succeeds or fails in educational settings. These insights will be useful to designers and instructors of gamified learning environments as they seek to engage and support a variety of learners.     

Performance of Optimal Super‐Twisting Controller for Liquid Level

Higher‐order sliding mode control algorithms and second‐order in particular have become a popular research area. This research analyzes the performance of optimally designed Super‐Twisting (STW) controllers, with application to the liquid level process. The problem of optimal design of the STW controller is formulated and a solution methodology is presented. Performance of the STW controller is compared with the performance of an optimally tuned PID controller. The study is carried out through analytical approach, simulations and experiments. From the comparison of performance, conclusions are drawn about suitability and the use of the STW controller for the process specifically considered in this research as well as other process control applications.     

Reliability of skin biopsy pathology

BACKGROUND: The diagnosis of skin disease by histologic examination is regarded as the reference standard upon which therapy and follow-up are determined. Our study investigated the reliability of skin biopsy diagnosis requested by family physicians and physicians' assistants. METHODS: Biopsy diagnoses by a community-based pathology group were reinterpreted by our study dermatopathologist on a sample of 119 skin biopsies randomly selected from the 1844 biopsies performed by family physicians and physicians' assistants at a large Washington State health maintenance organization during a 4 1/2-year period. RESULTS: There were 107 exact matches and 3 mismatches of premalignant lesions and 6 mismatches of benign diagnoses. In addition, two melanomas diagnosed by the community-based pathologists were interpreted as benign by our study dermatopathologist. A third melanoma diagnosed by the community-based group was interpreted as a poorly differentiated squamous cell cancer by the university dermatopathologist. The weighted kappa, 0.83, indicated excellent interrater agreement. CONCLUSION: Although our study showed excellent interrater concordance of skin biopsy interpretation, there was disagreement about three melanomas between a community-based general pathology group and our study dermatopathologist. The melanoma disagreement is consistent with previous studies that found poor interrater agreement for early melanomas. The community-based pathologists were uncertain about two of these melanomas, and as part of their quality control and review procedures requested confirmation by an expert pathologist, who agreed with the melanoma diagnosis. Family physicians are justified in requesting a second opinion (if not automatically requested by a community laboratory) when the histopathologic diagnosis is not in concordance with the clinical history or impression or when the pathologist is unsure of the diagnosis.