Mechanical properties and thermal stability of rice husk ash filled epoxy foams

Mechanical properties and thermal stability of epoxy foams filled with white and black rice husk ash were studied. Epoxy foams were prepared from a commercial system and filled with different amounts of both the ashes (0, 6.8, 12.8, 18.0, and 22.7 wt %). The incorporation of both the ashes modified the final morphology of the foam, decreasing the average cell size and increasing the number of cells per volume unit. For all filler percentages used, the specific modulus and strength results showed that the white ash is more effective as reinforcing agent than the black ash. The initial degradation temperature was not affected by the content and type of ash used as the filler. The integral procedure decomposition temperature, weight loss, and char residue results were related to the ash type and atmosphere used in the thermogravimetric analysis. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci, 2006     

Advanced oxidation and adsorption technologies for organic micropollutant removal from lake water used as drinking-water supply

The goal of this research is to evaluate the effectiveness of innovative drinking-water treatments designed to remove toxic and mutagenic organic micropollutants from lake waters used for human consumption. The widely used adsorption on granular activated carbon (GAC) filter technique was compared with the more innovative resin column techniques (XAD4 and Ambersorb-563) and with the advanced oxidation processes (AOPs) with UV/O3 and UV/O3/ H2O2. The water samples, collected from lake Como, treated with these techniques were analysed for mutagenic activity using Ames assay, toxicity using bioluminescent bacteria and organic compound were characterized using the GC-MS technique. The results found a decrease of the mutagenic and toxic activities of the lake water after adsorption on GAC and resins, while the AOP process generally increased these parameters. The absence of mutagenic activity was found only when a GAC adsorption step was performed in addition to the AOP process. Similar results were obtained by the toxicological and chemical analyses. In addition, the GC-MS analysis identified some possible mutagenic agents.     

Italian multicentre study on microbial environmental contamination in dental clinics: a pilot study

The dental practice is associated with a high risk of infections, both for patients and healthcare operators, and the environment may play an important role in the transmission of infectious diseases. A microbiological environmental investigation was carried out in six dental clinics as a pilot study for a larger multicentre study that will be performed by the Italian SItI (Society of Hygiene, Preventive Medicine and Public Health) working group "Hygiene in Dentistry". Microbial contamination of water, air and surfaces was assessed in each clinic during the five working days of the week, before and during treatments. Air and surfaces were also examined at the end of the daily activity. A wide variation was found in microbial environmental contamination, both within the participating clinics and relative to the different sampling times. Microbial water contamination in Dental Unit Water Systems (DUWS) reached values of up to 26 × 10⁴ cfu/mL (colony forming units per millilitre). P. aeruginosa was found in 33% of the sampled DUWS and Legionella spp. in 50%. A significant decrease in the Total Viable Count (TVC) was recorded during the activity. Microbial air contamination showed the highest levels during dental treatments and tended to decrease at the end of the working activity (p < 0.05). Microbial buildup on surfaces increased significantly during the working hours. As these findings point out, research on microbial environmental contamination and the related risk factors in dental clinics should be expanded and should also be based on larger collections of data, in order to provide the essential knowledge aimed at targeted preventive interventions.     

Inter-helical interactions in the leucine zipper coiled coil dimer: pH and salt dependence of coupling energy between charged amino acids

We have investigated the physical nature of the observed coupling energy (Delta Delta DeltaGint) between the charged side-chains of the three inter-helical g<-->e' (i, i'+5) pairs (E<-->R, E<-->K, and E<-->E) in the leucine zipper coiled coil dimer. Circular dichroism (CD) spectroscopy measured the thermal stability of eight proteins derived from the basic region leucine zipper domain of chicken VBP, the mammalian TEF at seven pHs and three KCl concentrations. Data from these proteins were used to construct double mutant alanine thermodynamic cycles and determine coupling energies (Delta Delta DeltaGint) for the three g<-->e' pairs. The attractive E<-->R coupling energy of -0.6 kcal mol-1 at low salt decreases to -0.2 kcal mol-1 at high salt. The E<-->K coupling energy of -0.5 kcal mol-1 at low salt decreases to -0.1 kcal mol-1 at high salt. The repulsive E<-->E coupling energy of +0.8 kcal mol-1 at low salt drops to +0.4 at high salt. Reducing the pH to 2.2 halved the attractive coupling energy for the E<-->R and E<-->K pairs while abolishing the repulsion of the E<-->E pair. 13C NMR of a protein selectively labeled with [13Cdelta]glutamate that contained three E<-->R and one R<-->E pair identified four glutamates shifted upfield. We suggest that this is due to electronic perturbation of glutamates in inter-helical E<-->R interactions. Taken together, these data indicate that the E<-->R coupling energy of -0.5 kcal mol-1 at pH 7.4 and 150 mM KCl has an electrostatic component.     

Quality of care in academic neurology departments

In striving to improve the quality of patient care, today's academic neurology department faces special problems. Factors that are inherent in the department's broader academic mission and in the organization of a major teaching hospital can compromise practice efficiency, reduce ease of access, and undermine cost competitiveness. However, the same environment also provides the opportunity to exploit areas of unique clinical expertise, create value-added services, and develop regional approaches to service-line integration and disease management strategies. A major challenge for the academic department is to validate the quality and efficiency of its current services while assuming a leadership role in the development of new approaches to quality improvement. This challenge must be met without losing sight of the department's equally important parallel commitments to research and education.     

Quality assessment of bed sediments of the Po River (Italy)

Comprehensive and contemporary evaluations of physical, chemical and toxicological endpoints have been performed on bed sediments of the Po River, the major Italian watercourse. Two extensive sampling campaigns were conducted in summer and winter low-flow conditions. Composite sediment samples were collected from ten reaches of the main river: the first was located in the upper region (ambient control), and the others downstream of the confluences of nine principal tributaries. The two sampling programs were paralleled by contemporary investigations on the macroinvertebrate community. The particle-size composition along the Po River showed a relatively uniform distribution of fine sand, a progressive downstream decrease of coarse sands and a corresponding increase of fine materials. The levels of polychlorinated biphenyls (PCB), polycyclic aromatic hydrocarbons (PAH), extractable organo halides (EOX), Cd, Cr, Cu, Hg, Ni, Pb and Zn were determined in sediment fine particles (< 63 microm), and showed marked changes across the ten river reaches. Their longitudinal trends, as those of organic carbon and total nitrogen, were very similar and largely independent of the survey season. Sediment quality benchmarks were used to evaluate sediment chemistry, and, although the overall level of contamination was from moderate to low, the reaches located downstream of the tributaries Dora Riparia, Dora Baltea, Lambro and Oglio were considered to be at risk. Sediments were tested for toxicity on Oncorhynchus mykiss, Ceriodaphnia dubia, Raphidocelis subcapitata and Vibrio fischeri. The toxicity tests were conducted both with sediment extracts and whole samples. Sediment extracts showed toxic potentials that were consistent with the spatial distribution of contaminants. Whole-sediment toxicity showed moderate/low effects which also included false positives and negatives. Alterations of the macroinvertebrate community were found for many kilometers downstream of Dora Riparia, and with a seasonal dependence, also in other reaches of the Italian river. Principal component analysis (PCA) was used to describe the longitudinal and temporal changes of the Po River, and allowed the selection of the most useful and discriminating indicators.     

Graft copolymers of lignin from straw with 1‐ethenylbenzene: Synthesis and characterization

The synthesis of copolymers between lignin from steam‐exploded straw and 1‐ethenylbenzene is described. Beforehand, lignin from steam‐exploded straw was fully characterized by using elemental analysis, ultraviolet spectroscopy, gel permeation chromatography (GPC), Fourier transform infrared (FTIR), and both ¹H and ¹³C nuclear magnetic resonance (NMR) spectroscopy. Using a previously described procedure utilizing calcium chloride and hydrogen peroxide as reagents the synthesis of the copolymers was performed. FTIR of the copolymers showed the presence of both lignin and polystyrene. GPC analysis showed the presence of a fraction with high molecular weights. These results were confirmed from both viscosity data and differential calorimetry. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 79: 72–79, 2001