Corrosion Protection of Stainless Steel by Poly(Carbazole-co-pyrrole) Films Deposited on TiO2 Sol–Gel Film

The poly(carbazole-co-pyrrole) copolymer was synthesized on TiO₂ sol–gel precoated 304 stainless steel (TiO₂) by cyclic voltammetry in tetrabutylammonium perchlorate containing acetonitrile solution. The synthesized coating was characterized by attenuated total reflectance–Fourier transform infrared spectroscopy, scanning electron microscopy, and solid-state conductivity measurements. Corrosion protection behavior of the TiO₂/poly(carbazole-co-pyrrole)-coated steel was evaluated by open circuit potential–time curves, potentiodynamic polarization, and electrochemical impedance spectroscopy methods. Corrosion test results showed that TiO₂/poly(carbazole-co-pyrrole) composite film enhanced corrosion resistance of stainless steel up to 50 days of immersion in 0.1M HCl corrosive medium.     

The incidence of neurological disorders in tropical South America. Experience in the Bolivian lowlands

BACKGROUND: The Chiquitano tribe lives in the southern Amazonas region in Bolivia, remote from larger towns. Data on the epidemiology of neurological disorders are completely lacking. METHODS: A combined prospective-retrospective study was designed to determine the prevalence and annual incidence of major neurological diseases. In an one-year prospective study 1514 individuals (total population 5652) who consulted the general practitioner were interviewed and examined for neurological disturbances. These histories were analysed retrospectively by a neurologist and classified according the diagnosis key of the DGN. RESULTS: During a one-year period (April 1995-March 1996), 139 patients suffering from neurological diseases were seen (one-year incidence and prevalence 2.45%). Cervical and lumbosacral pain syndromes were the most common neurological problems; these were caused by sleeping in hammocks, and by hard agricultural labour. Tropical myositis (12.9%) was very frequent and the most frequent muscle disease. Epilepsy was found in 11 patients and extrapyramidal syndromes in 2 patients. Regarding epilepsy, a high dark rate is assumed because of social and cultural traditions. Strokes are rare, since many risk factors are not present. All cases of meningitis were lethal and clearly demonstrated infrastructural problems. Patients with social diseases (AIDS, drug- and alcohol addiction, injuries caused by violence) were rarely seen. CONCLUSION: In a shrinking world, and with the development of "Tropical Neurology" as a specialised discipline neuroepidemiological data are increasingly important for two reasons. First of all, they sensitise neurologists to this topic, and secondly, they can be used to estimate the need for neurologists serving the Third World's minority populations.     

Hydraulic Alumina Binder for Extrusion of Alumina Ceramics

The present work describes the effect of hydraulic alumina (HA) as a new inorganic binder on extrusion of alumina ceramics. The addition of a small amount of HA imparted significant flowability and rigidity to the extruded alumina. Under optimum processing conditions such as amounts of HA and water, and curing period, alumina rods and tubes were successfully extruded using a single screw extruder. Sintered specimens have achieved a relative density of 97% after sintering at 1600°C for 2 h. Dense alumina samples prepared using organic and inorganic binders had similar mechanical properties, that is, Young's modulus >380 GPa and H _v>2000. These results suggest that HA is a new kind of inorganic binder applicable to the extrusion of ceramics.     

Synthesis and properties of radiation‐induced acrylamide–acrylic acid hydrogels

Acrylamide (AAm)/acrylic acid (AAc) hydrogels in the cylindirical form were prepared by γ‐irradiating binary systems of AAm/AAc with 2.6–20.0 kGy γ‐rays. The effect of the dose and relative amounts of AAc and pH on the swelling properties, diffusion behavior of water, diffusion coefficients, and network properties of hydrogel systems was investigated. The swelling capacities of AAm/AAc hydrogels were in the range of 1000–3000%, while poly(acrylamide) (PAAm) hydrogels swelled in the range of 450–700%. Water diffusion into hydrogels was found to be non‐Fickian‐type diffusion. Diffusion coefficients of AAm/AAc hydrogels were found between 0.79 × 10^?5 and 2.78 × 10^?5 cm² min^?1. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 3570–3580, 2002     

Minimizing the earliness/tardiness costs on parallel machine with learning effects and deteriorating jobs: a mixed nonlinear integer programming approach

In this study, we introduce a mixed nonlinear integer programming formulation for parallel machine earliness/tardiness (ET) scheduling with simultaneous effects of learning and linear deterioration, sequence-dependent setups, and a common due-date for all jobs. By the effects of learning and linear deterioration, we propose that the processing time of a job is defined by increasing function of its execution start time and position in the sequence. The developed model allows sequence-dependent setups and sequence-dependent early/tardy penalties. The model can easily provide the optimal solution to problems involving about eleven jobs and two machines.     

Addressing Learner Satisfaction Outcomes in Electronic Instrumentation and Measurement Laboratory Course Organization

This paper proposes and details a course organization methodology based on learner satisfaction achievement. The approach follows the prevailing tendency in modern university reforms which are primarily concerned about "how people learn." As a consequence, the learner has been placed as the main actor of the teaching-learning process. Nevertheless, the current learning literature has not addressed the measurement of learner satisfaction within laboratory and practical subjects. This study develops a general and comprehensive methodology for learner satisfaction measurement in practical subjects. As a case example, the proposed methodology has been applied to an electronic instrumentation and measurement course, confirming the variables with a significant influence on learner satisfaction and becoming the starting point for curriculum redesign based on the learner satisfaction approach. To assess the improvement of the proposed course organization methodology, a comparison with previous academic years has been performed showing the students' rated score evolution. Results fully confirm the validity of the technique and the novel course organization     

Use of the wavelet method for analyzing electrochemical noise data

This research paper shows the application of the mathematical tool “wavelet's” to be used in the interpretation and analysis of electrochemical noise signals. The Fast Fourier Transformation (FFT) is one of the most commonly used techniques for analyzing electrochemical noise. But the application of this methodology to the analysis of stochastic signals does not allow their interpretation in a suitable way. The wavelet's methodology carries out the analysis by means of the construction of finite base functions. In several studies, it has been found out that the function that is closest to the electrochemical oscillations is the one called “coiflets,” which presents a similar geometry to what it is observed when an ionic–electronic interchange occurs during an electrochemical interphase. The analysis that appears here was implemented using the toolbox “LabView?.”