Effect of ash on maximum thickness of plastic layer of coals

A study of the effect of ash yield on the maximum thickness of the plastic layer (MTPL) of some coking coals (as measured by the Sapozhnikov plastometer) has revealed that with an increase in the former the latter in general decre?es. A rectilinear relation approximately exists between the ash percentage (dry basis) and log MTPL values of coals. For the samples studied, a multiple correlation incorporating the rank factor was found to be unnecessary. Higher Fe₂O₃ and SO₃ contents from the coal were found to be associated with higher MTPL values.     

Polarization-based compensation of astigmatism

One approach to aberration compensation of an imaging system is to introduce a suitable phase mask at the aperture plane of an imaging system. We utilize this principle for the compensation of astigmatism. A suitable polarization mask used on the aperture plane together with a polarizer-retarder combination at the input of the imaging system provides the compensating polarization-induced phase steps at different quadrants of the apertures masked by different polarizers. The aberrant phase can be considerably compensated by the proper choice of a polarization mask and suitable selection of the polarization parameters involved. The results presented here bear out our theoretical expectation.     

Neural network optimized with evolutionary computing technique for solving the 2-dimensional Bratu problem

In this paper, a stochastic technique is developed to solve 2-dimensional Bratu equations using feed-forward artificial neural networks, optimized with genetic and interior-point algorithms. The 2-dimensional equations are first transformed into a 1-dimensional boundary value problem, and a mathematical model of the transformed equation is then formulated with neural networks using an unsupervised error. Network weights are optimized to minimize the error. Evolutionary computing based on genetic algorithms is used as a tool for global search, integrated with an interior-point method for rapid local convergence. The methodology is applied to solve three cases of boundary value problems for the Bratu equations. The accuracy, convergence and effectiveness of the scheme is validated for a large number of simulations. Comparison of results is made with the exact solution derived using MATHEMATICA, and is found to be in good agreement.     

Impact of Multimedia-Based Instruction on Learning and Retention

Studies measuring and evaluating the impact of the same multimedia-based education on learners in universities and high schools are a relatively new phenomenon. This study provides a summary of the results from research on the effects of multimedia-based safety education conducted by the M. E. Rinker Sr. School of Building Construction at the University of Florida. The findings are presented along with their related statistical test results. The findings indicate multimedia-based, self-paced learning offers very distinct advantages over traditional, instructor-led classroom learning. Overall, both the high-school and university student groups involved in the study exhibited superior retention rates when learning from the multimedia-based materials. Higher scoring students in the classroom showed little difference in either media, while students who tended to score at the low end of the grading scale uniformly scored higher on multimedia-based materials. The reduced variation in student performance based on test scores in the CD-ROM instruction indicates the positive effects of multimedia-based instruction.     

Characterization of surface texture generate multi-process manufacture

In recent years, surfaces are being engineered to make their surface texture more suitable to their function. Most of the “engineered surfaces” are manufactured by more than one manufacturing process which results in a texture that is based on the combined processes. In order to characterize the surface texture generated by multi-process manufacture, various methods have been developed. In this paper, the existing methods that are based on the technique of linearization of the bearing area curve are reviewed and a segmented regression model for the surfaces generated by multi-process manufacture is presented. The parameters of this model can be used to control the manufacturing processes or to verify the suitability of the surface for the intended function.     

Mono-, Bi- and Multifunctional Single-Sites: Exploring the Interface Between Heterogeneous and Homogeneous Catalysis

This mini-review contrasts the characteristics of traditional heterogeneous (solid) catalysts with those of homogeneous ones: the nature of the active sites in each case is very different, a fact well illustrated in ammonia synthesis. It is recalled that certain chemical transformations can be effected only with heterogeneous catalysts. It is also demonstrated that the scope for introducing multifunctional sites is greater with open-structured inorganic heterogeneous catalysts than with homogeneous ones: for example, Ti^IV ions distributed in a spatially isolated and accessible manner at the large areas of a nanoporous support smoothly convert cyclohexene to adipic acid (with H₂O₂) in a cascade of six consecutive reactions. A sharp distinction is drawn between nanocluster and nanoparticle “metal” catalysts, both electronic and geometric arguments being utilized to explain this difference. In the extreme case, a few (or single) metal atoms (supported on oxides) have been shown (see refs. Fu et al. Science 301:935, 2003 and Rim et al J Phys Chem C 113:10198, 2009) to be more important determinants of catalytic activity than nanoparticle metals such as Au and Pd. Recent advances in high-resolution electron microscopy is a key technique in this facet of catalysis. The merits of immobilizing single-site homogeneous catalysts and of creating atomically well-defined single-site heterogeneous ones on high-area solids are illustrated both from a practical viewpoint and also as a strategy for the design of new catalysts.     

Development of coating materials from liquid wax esters for wood top-based coating

Of late, UV-curable products are gaining attention in the wood industry because of the effectiveness and efficiency of this method. UV-curable surface coatings are widely used because of their excellent properties and because they are environmentally friendly products. In this study, immobilized Candida antarctica lipase B was used to catalyze formation of liquid wax esters, such as adipate esters, via a solvent-free process. The adipate esters formed were then used as UV-curable reactants in the wood coating formulations, consisting of epoxy acrylate, additives, and a photoinitiator. The performance of the products was evaluated by coating them onto glass tiles (using gel content, hardness, and scratch resistance tests) and wood panels (using adhesion, impact, and heat resistance tests). The coated film from this formulation performed well during the evaluation tests. The gel content exhibited more than 90% polymerization, while the pendulum hardness gave a value of 55.25%. Both analyses were significant in determining the effect of irradiation cycles. A scratch test was also carried out to verify the resistance of the coating. The maximum weight load which can be resisted by the wax esters formulation is 4.5 N.     

Tunneled Catheter–Associated Atrial Thrombi: Successful Treatment with Chronic Anticoagulation

Tunneled dialysis catheter–associated right atrial thrombus (RAT) is a rarely reported complication. We reviewed hospital records of 10 patients from a teaching hospital dialysis unit, in whom RAT was diagnosed by trans‐esophageal echocardiography (TEE). Patients were treated with chronic anticoagulation (heparin followed by warfarin) and followed over time. The group included 7 women; 6 patients were African American, 3 were Caucasian, and 1 was Hispanic. The average age was 52.1 ± 15.3 years. The most common presenting symptom was poor catheter flow on hemodialysis followed by fever and chills. On average, the patients had had 3.4 ± 2.7 catheter insertions before diagnosis of RAT, and the tunneled dialysis catheter (TC) had been in place for a mean of 91 ± 89.4 days when the thrombi were diagnosed. Trans‐thoracic echocardiography (2‐D echo) was done in 4 patients, but it identified RAT in only 1 patient. The catheter tip was at the junction of the superior vena cava and right atrium (SVC/RA) in most patients. Thrombolysis (unsuccessful) was attempted with urokinase in 3 patients, complicated in 2 patients by hemorrhage. After anticoagulation, 90% of the RAT resolved on repeated TEE. One patient had persistent RAT for 23 weeks and underwent surgical thrombolysis, but died postoperatively. We conclude that RAT is a frequently missed complication of a TC. Positioning the tip of the TC at the SVC/RA junction may not prevent RAT. Trans‐esophageal echocardiography is a more sensitive diagnostic tool than 2‐D echo and should be obtained early. Most patients can be successfully treated with anticoagulation alone. Thrombolytic therapy and surgical thrombolysis have high morbidity and mortality.