Adsorption of Bismark Brown dye on activated carbons prepared from rubberwood sawdust (Hevea brasiliensis) using different activation methods

Hevea brasiliensis or rubberwood tree, as it is commonly known finds limited use once the latex has been tapped. The sawdust of this tree is chosen to ascertain it viability as a precursor for activation. The carbons thus obtained were characterized in terms of iodine, methylene blue number and surface area. The best carbon in each method was utilized to study the adsorption of Bismark Brown, a dye used in the leather industry. Adsorption equilibrium studies were carried out with the synthetic solutions of the dye, at room temperature (298 K). Equilibrium data are fitted with the Langmuir and the Freundlich isotherms models for the system. The effects of contact time, adsorbent dosage and initial dye concentrations on sorption capacity were carried out. Excellent adsorption capacities of 2000 and 1111 mg g(-1) were obtained for steam and chemical followed by steam-activated carbons, respectively. Pilot-plant experimental studies have been performed using packed-bed column with different feed concentrations, flow rates and bed heights, to evaluate sorption of Bismark Brown on steam-activated carbon. Bed depth service time (BDST) design model have been used to analyze the data.     

Ultrasonic guided wave scattering in a plate overlap

Guided wave scattering in a plate overlap is investigated by numerical calculations and experimental measurements of transmission and reflection factors from the overlap region. In the numerical study, a hybrid boundary element-finite element method is used to calculate the guided wave scattered field from the overlap region. Transmission and reflection factors are calculated for incident A0 and S0 Lamb and n0 shear horizontal waves, including higher modes generated through mode conversion phenomena. In addition, parametric studies of transmission and reflection factors in this problem are performed numerically over various incident modes, frequencies, and overlap lengths. For verification and comparison with numerical results, experiments were conducted to measure the transmission and reflection factors for incident Lamb and shear horizontal waves in steel plates with two different overlap areas. The experimental results agree well with the numerical calculations. The numerical and experimental results show that it is highly feasible to carry out efficient Lamb wave nondestructive evaluation (NDE) in overlapped plates and in multilayer structures with various lap joints by selecting various modes and tuning frequency.     

Porosimetry Measurements on Low Dielectric Constant—Thin Layers by Coupling Spectroscopic Ellipsometry and Solvent Adsorption-Desorption

Ellipsometric measurements are carried out on different commercial ultra low-K mesoporous thin films under several solvent vapor pressures. In a first step, both open porosity and skeleton refractive indices are estimated using linear and Lorentz-lorenz laws. In a second step, adsorption-desorption isotherms of selected solvents, giving refractive index as a function of the relative pressure, are acquired. Pore size distributions (PSD) are calculated. The effect of the nature of the adsorbate on the PSD is also discussed.     

Learning opportunity and preparedness for practice: perceptions from dietetics programs in Canada.

PURPOSE: This study determined dietetics trainees' and program coordinators' perceptions about trainees' preparedness to practice, based on Dietitians of Canada's 145 competency statements. Depth and breadth of learning opportunity were also determined with definitions of these two concepts based on Elliott's view of professional education and practice. METHODS: Research questions were: 1. How prepared were trainees for practice? 2. What were the depth and breadth of learning opportunity in assessment, planning, implementation and evaluation? 3. How many learning opportunities were there in professional practice and communication? 4. Did responses vary between integrated programs and internships or between trainees and program coordinators? RESULTS: Of 313 trainees, 168 (54%) responded and 23 (72%) of 32 coordinators responded. Preparedness was rated as "well prepared" or better for 25 (56%) of the 45 main competencies. For every competency, preparedness ratings were higher in integrated programs than in internships. Learning opportunities were rated as sufficient in depth and breadth or number for 88 (61%) of the 145 competency statements. Low ratings for preparedness were accompanied by low ratings for depth and/or breadth or number of learning opportunities. CONCLUSIONS: The notion of depth and breadth is useful as a framework to assess learning opportunities for developing entry-level competence.     

Review of factors affecting microbial survival in groundwater

This review quantitatively examines a number of published studies that evaluated survival and inactivation of public-health-related microorganisms in groundwater. Information from reviewed literature is used to express microbial inactivation in terms of log10 decline per day for comparison to other studies and organisms. The geometric mean value for inactivation rates for coliphage, poliovirus, echovirus, coliform bacteria, enterococci, and Salmonella spp. were similar at approximately 0.07-0.1 log10 day(-1), while geometric mean inactivation rates for hepatitis A virus, coxsackievirus, and phage PRD-1 were somewhat less at 0.02-0.04 log10 day(-1). Viruses show a temperature dependency with greater inactivation at greater temperatures; however this occurs largely at temperatures greater than 20 degrees C. Coliform bacteria die off in groundwater does not show the temperature dependency that viruses show, likely indicating a complex interplay of inactivation and reproduction subject to influences from native groundwater organisms, temperature, and water chemistry. The presence of native microorganisms seems to negatively impact E. coli survival more so than viruses, but in most cases, nonsterile conditions led to a greater inactivation for viruses also. The effect of attachment to solid surfaces appears to be virus-type-dependent, with PRD-1 more rapidly inactivated as a result of attachment and hepatitis A and poliovirus survival prolonged when attached.     

Modeling Beliefs and Solution Strategies in a Distributed Learning System

We present algorithms guiding the identification of student solution strategies in the Domain-Independent Adaptive Tutoring System (DIATS). The DIATS is a distributed computer-assisted instruction system with a prototype in the domain of psychiatric mental disorders. Problems are solved using differential diagnosis decision trees from the DMS-IV-TR. Student solution strategy identification is performed by the Response Analysis Unit of the modeler. The Domain-Independent Adaptive Tutoring System (DIATS) has a distributed architecture that combines shared-data and client-server styles.     

Poly(arylene ether sulphones) by polyetherification: 2. Polycondensations

Several alkali metal halogenophenylsulphonyl phenoxides have been polymerized in the melt and in solution. Poly(arylene ether sulphones) have also been prepared by polycondensation of 4-halogenophenylsulphonyl compounds with phenols in the presence of potassium fluoride. The effects of structural factors on the ease with which polymers of high molecular weight could be obtained were examined and found to correlate with previous data concerning functional group reactivities. A procedure for the synthesis of polymer samples containing branched macromolecules has been devised and evaluated.     

Automatic processing of fundamental information: The case of frequency of occurrence.

Reviews the evidence that suggests that information about frequency of occurrence is stored in memory by an implicit or automatic encoding process. This evidence shows that frequency information is stored for a wide variety of naturally occurring events. Laboratory research shows that usually powerful task variables (e.g., instructions, practice) and S variables (e.g., age, ability) do not influence the encoding process. Evidence is also reviewed that either directly or indirectly implicates the use of frequency information across issues in psychology ranging from the acquisition and representation of knowledge domains to decision making to sex-role development. (120 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)