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Particulates
Kinds of Particulates Terms modified by Particulates Selected AbstractsPhotosensitization of TiO2 Nanostructures with CdS Quantum Dots: Particulate versus Tubular Support ArchitecturesADVANCED FUNCTIONAL MATERIALS, Issue 5 2009David R. Baker Abstract TiO2 nanotube arrays and particulate films are modified with CdS quantum dots with an aim to tune the response of the photoelectrochemical cell in the visible region. The method of successive ionic layer adsorption and reaction facilitates size control of CdS quantum dots. These CdS nanocrystals, upon excitation with visible light, inject electrons into the TiO2 nanotubes and particles and thus enable their use as photosensitive electrodes. Maximum incident photon to charge carrier efficiency (IPCE) values of 55% and 26% are observed for CdS sensitized TiO2 nanotube and nanoparticulate architectures respectively. The nearly doubling of IPCE observed with the TiO2 nanotube architecture is attributed to the increased efficiency of charge separation and transport of electrons. [source] Editorial to the Special Issue "Control of Particulate Processes" (Part. Part.PARTICLE & PARTICLE SYSTEMS CHARACTERIZATION, Issue 4 2008Syst. No abstract is available for this article. [source] Indomethacin decreases particulate guanylyl cyclase activity in rat kidneyCLINICAL AND EXPERIMENTAL PHARMACOLOGY AND PHYSIOLOGY, Issue 4 2004JongUn Lee SUMMARY 1.,Effects of non-steroidal anti-inflammatory drugs on the local atrial natriuretic peptide (ANP) and nitric oxide (NO) systems in the kidney were investigated. 2.,Male Sprague-Dawley rats were treated with indomethacin (5 mg/kg, every 12 h, i.p.) for 2 days. The expression of ANP and natriuretic peptide receptor-A (NPR-A) mRNA was determined in the kidney, as was that of endothelial NO synthase (NOS) proteins. Particulate and soluble guanylyl cyclase activities were determined separately. 3.,Following treatment with indomethacin, urinary sodium excretion decreased significantly. Although the renal expression of ANP was not changed significantly, that of NPR-A decreased significantly. The expression of NOS increased significantly. Particulate guanylyl cyclase activity was decreased, whereas the activity of soluble guanylyl cyclase was increased. The catalytic activity of Na+/K+ -ATPase was increased, with no significant changes in its expression. The expression of the type 3 Na/H exchanger and Na,K,2CL cotransporters increased significantly. 4.,The indomethacin-induced decrease in urinary sodium excretion may be attributed, at least in part, to decreased activity of the local ANP/cGMP system. The increased activity of the NO/cGMP system may be a compensatory response to the diminished activity of the prostaglandin system. [source] Speciation and Environmental Fate of Chromium in Rivers Contaminated with Tannery EffluentsENGINEERING IN LIFE SCIENCES (ELECTRONIC), Issue 2 2007J. Dominik Abstract Redox and size speciation of chromium in rivers contaminated with tannery wastewater was carried out to provide insight into its transport and removal mechanisms. Total chromium was determined with Inductively Coupled Plasma-Mass Spectrometry and Cr,(VI) with Catalytic Adsorption Stripping Voltammetry. For the size speciation, particles were retained with a cartridge filter (cut-off 1.2,,m) and the total filterable fraction was further fractionated with Tangential Flow Filtration to determine the concentrations of chromium associated with the High Molecular Weight Colloidal (HMWC), Low Molecular Weight Colloidal (LMWC) and Truly Dissolved (TD) fractions. Two fluvial systems of similar sizes, but located in contrasting climatic zones, were selected for comparison: the Sebou-Fez system in Morocco and Dunajec River-Czorsztyn Reservoir system in Poland. Particulate Cr dominated in the Sebou-Fez system (about 90,%); while in the Dunajec-Czorsztyn system, it represented only 17,53,% of the total chromium in raw water. Still, the partition coefficients [Kd] were of the same magnitude. Chromium,(III) was the only form detected in Sebou-Fez, whereas in Dunajec-Czorsztyn Cr,(VI) was also present with its proportion increasing downstream from the input of tannery wastewater due to the preferential removal of Cr,(III). In the filtered water in Morocco a large fraction of Cr occurred in the HMWC fraction (50,70,%) at the two most contaminated sites, while the LMWC and TD forms prevailed at the non-contaminated sites in the Sebou River. At a very high concentration, in the water in the proximity of tanneries (well above the theoretical saturation level) Cr precipitated as polynuclear Cr-hydroxide. In Dunajec-Czorsztyn, the partition of Cr,(III) was approximately equal between the HMWC, LMWC and TD fractions, in contrast to Cr,(VI) which occurred almost exclusively in the TD fraction. In both systems, Cr,(III) was rapidly removed from the water to the sediments. The confluence of the Sebou with the Fez and the Czorsztyn reservoir trapped efficiently Cr,(III) preventing its spreading over long distances. Cr,(VI) showed conservative behavior and bypassed the Czorsztyn Reservoir. This study provides a first set of data on the partitioning of Cr,(III) and Cr,(VI) between the particulate, the colloidal and truly dissolved fractions in fluvial systems contaminated with tannery effluents. It also suggests that, in these systems, truly dissolved Cr,(III) can be adequately modeled from the total filterable concentrations. [source] Genotoxicity and physicochemical characteristics of traffic-related ambient particulate matterENVIRONMENTAL AND MOLECULAR MUTAGENESIS, Issue 2 2005Theo M. de Kok Abstract Exposure to ambient particulate matter (PM) has been linked to several adverse health effects. Since vehicular traffic is a PM source of growing importance, we sampled total suspended particulate (TSP), PM10, and PM2.5 at six urban locations with pronounced differences in traffic intensity. The mutagenicity, DNA-adduct formation, and induction of oxidative DNA damage by the samples were studied as genotoxicological parameters, in relation to polycyclic aromatic hydrocarbon (PAH) levels, elemental composition, and radical-generating capacity (RGC) as chemical characteristics. We found pronounced differences in the genotoxicity and chemical characteristics of PM from the various locations, although we could not establish a correlation between traffic intensity and any of these characteristics for any of the PM size fractions. Therefore, the differences between locations may be due to local sources of PM, other than traffic. The concentration of total (carcinogenic) PAHs correlated positively with RGC, direct and S9-mediated mutagenicity, as well as the induction of DNA adducts and oxidative DNA damage. The interaction between total PAHs and transition metals correlated positively with DNA-adduct formation, particularly from the PM2.5 fraction. RGC was not associated with one specific PM size fraction, but mutagenicity and DNA reactivity after metabolic activation were relatively high in PM10 and PM2.5, when compared with TSP. We conclude that the toxicological characteristics of urban PM samples show pronounced differences, even when PM concentrations at the sample sites are comparable. This implies that emission reduction strategies that take chemical and toxicological characteristics of PM into account may be useful for reducing the health risks associated with PM exposure. Environ. Mol. Mutagen., 2005. © 2005 Wiley-Liss, Inc. [source] Profile: air quality regulation policy in PortugalENVIRONMENTAL POLICY AND GOVERNANCE, Issue 1 2004Joăo F. P. Gomes Ten years after the publication of the first air quality laws in Portugal, and seven years after the publication of the respective emission limits, it seems appropriate to analyse the degree of law enforcement by the Portuguese manufacturing industry. Therefore, based on the emission measurements made regularly by ISQ as the only officially accredited laboratory, a set of about 400 sources is analysed in terms of the compliance with the emission limits regarding total suspended particulate, sulphur dioxide, nitrogen oxides and VOCs. The compliance is evaluated through a non-dimensional parameter and plotted versus the emission flow rate to derive conclusions: it was noticed that emission limits are generally respected regarding sulphur dioxide and nitrogen oxides, which does not happen for the other pollutants considered in this study. However, the non-compliance occurs mainly for very low emission flow rates, which suggests some alterations in the emission limits' applicability, which is being revised at the moment. Copyright © 2004 John Wiley & Sons, Ltd and ERP Environment. [source] Noble metal-based catalysts for total oxidation of chlorinated hydrocarbonsENVIRONMENTAL PROGRESS & SUSTAINABLE ENERGY, Issue 3 2001José M. Toledo Catalytic total oxidation of selected chlorinated hydrocarbons utilizing several noble metal (Pt, Pd, Ru)-based catalysts was studied. Chlorinated hydrocarbons used were trichloroethylene, dichloromethane, and chlorobenzene, alone or mixed with other hydrocarbons, such as toluene. Catalysts tested were both commercially available, manufactured by Degussa AG, Süd-Chemie AG, Kataleuna GmbH, Chimet, Johnson Matthey, Prototech Co., etc., and new ones developed by Universities of Leiden in The Netherlands, Budapest in Hungary, and Wroclaw in Poland. Both forms of catalyst, sphere (particulate) and monolith, were used. Selection of the best catalyst(s) was made based on its activity, selectivity, and life. Apparent energies of activation for the reactions on these catalysts, using an empirical firstorder reaction rate, are also given. [source] Concentration dependency of biota-sediment accumulation factors for chlorinated dibenzo- p -dioxins and dibenzofurans in dungeness crab (Cancer magister) at marine pulp mill sites in British Columbia, CanadaENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 12 2000Walter J. Cretney Abstract Biota-sediment accumulation factors (BSAFs) for some chlorinated dibenzo- p -dioxin and dibenzofuran congeners (PCDD/Fs) in Dungeness crab (Cancer magister) hepatopancreas and associated sediments are concentration independent as required by equilibrium partition models. In particular 2, 3, 7, 8-tetrachlorodibenzo- p -dioxin (2, 3, 7, 8-TCDD), 2, 3, 7, 8-tetrachlorodibenzofuran, the 2, 3, 7, 8-substituted pentachlorodibenzofurans, and the non-2, 3, 7, 8-hexachlorodibenzofurans (HxCDFs) seem to fall into this group. The BSAFs for other isomers exhibit significant, nonlinear variations with sediment or crab PCDD/F concentrations. For some of these other isomers (e.g., the non-2, 3, 7, 8 TCDDs and possibility the 2, 3, 7, 8-substituted HxCDFs), association of a variable fraction of the total present with soot carbon may provide a satisfactory explanation for the concentration behavior. For the HxCDDs we propose that the nonlinear concentration behavior may arise from the thermodynamic properties of fluids confined in hydrophobic voids within particulate and colloidal material produced by the pulp mills. The nonlinear relationship between BSAFs and PCDD/F concentrations greatly complicates prediction of the potential for dioxin and furan bioaccumulation in crabs and the formulation of sediment quality criteria. We provide a nonlinear equation relating toxic equivalency and sediment concentrations. [source] Organic matter quality of a forest soil subjected to repeated drying and different re-wetting intensitiesEUROPEAN JOURNAL OF SOIL SCIENCE, Issue 2 2010A. Schmitt Extended drought periods followed by heavy rainfall may increase in many regions of the Earth, but the consequences for the quality of soil organic matter and soil microbial communities are poorly understood. Here, we investigated the effect of repeated drying and re-wetting on microbial communities and the quality of particulate and dissolved organic matter in a Haplic Podzol from a Norway spruce stand. After air-drying, undisturbed soil columns were re-wetted at different intensities (8, 20 and 50 mm per day) and time intervals, so that all treatments received the same amount of water per cycle (100 mm). After the third cycle, SOM pools of the treatments were compared with those of non-dried control columns. Lignin phenols were not systematically affected in the O horizons by the treatments whereas fewer lignin phenols were found in the A horizon of the 20- and 50-mm treatments. Microbial biomass and the ratio of fungi to bacteria were generally not altered, suggesting that most soil microorganisms were well adapted to drying and re-wetting in this soil. However, gram-positive bacteria and actinomycetes were reduced whereas gram-negative bacteria and protozoa were stimulated by the treatments. The increase in the (cy 17: 0 + cy 19: 0)/(16:1,7c + 18:1,7c) ratio indicates physiological or nutritional stress for the bacterial communities in the O, A and B horizons with increasing re-wetting intensity. Drying and re-wetting reduced the amount of hydrolysable plant and microbial sugars in all soil horizons. However, CO2 and dissolved organic carbon fluxes could not explain these losses. We postulate that drying and re-wetting triggered chemical alterations of hydrolysable sugar molecules in organic and mineral soil horizons. [source] Synthesis and Low Cycle Fatigue Behavior of In-situ Al-based Composite Reinforced with Submicron TiB2 and TiC Particulates,ADVANCED ENGINEERING MATERIALS, Issue 12 2004S.C. Tjong Low cycle fatigue behavior of in-situ aluminum based composite reinforced with submicron TiB2 and TiC particulates was investigated. This novel composite was prepared from the TiO2 -Al-B-C system via reactive hot pressing. The incorporation of carbon into such a system induces the formation of TiC particulate at the expense of brittle Al3Ti phase. The influence of submicron particulate formation on the tensile and fatigue properties of the composite is discussed. [source] An evaluation of actual and simulated smoke propertiesFIRE AND MATERIALS, Issue 2 2005Jill Suo-Anttila Abstract Federal regulations require that aircraft cargo compartment smoke detection systems be certified by testing their operation in flight. For safety reasons, only simulated smoke sources are permitted in these certification tests. To provide insight into smoke detection certification in cargo compartments, this research investigates the morphology, transport and optical properties of actual and simulated smoke sources. Experimental data show the morphology of the particulate in smoke from flaming fires is considerably different from simulated smoke. Although the detection of smoldering fires is important as well, only a qualitative assessment and comparison of smoldering sources was possible; therefore, efforts were concentrated on the quantitative comparison of smoke from flaming fires and smoke generators. The particulate for all three different flaming fires was solid with similar morphological properties. Simulated smoke was composed of relatively large liquid droplets, and considerably different size droplets can be produced using a single machine. Transport behavior modeling showed that both the actual and simulated smoke particulates are sufficiently small to follow the overall gas flow. However, actual smoke transport will be buoyancy driven due to the increased temperature, while the simulated smoke temperature is typically low and the release may be momentum driven. The morphology of the actual and simulated smoke were then used to calculate their optical properties. In contrast to the actual smoke from a flaming fire, which is dominated by absorption, all of the extinction for the simulated smoke is due to scattering. This difference could have an impact on detection criteria and hence the alarm time for photoelectic smoke detectors since they alarm based on the scattering properties of the smoke. Copyright © 2004 John Wiley & Sons, Ltd. [source] Isocyanates, aminoisocyanates and amines from fires,a screening of common materials found in buildingsFIRE AND MATERIALS, Issue 6 2003Per Blomqvist Abstract Isocyanates, aminoisocyanates and amines were quantified from the combustion of 24 different materials or products typically found in buildings. Small-scale combustion experiments were conducted in the cone calorimeter, where generally well-ventilated combustion conditions are attained. Measurements were further made in two different full-scale experiments. Isocyanates and amino-compounds were sampled using an impinger-filter sampling system with a reagent solution of di-n-butylamine in toluene. Filter and impinger solution were analysed separately using LC-MS technique. Further the particulate distribution in the smoke gases was determined by impactor technique, and selected gaseous compounds quantified by FTIR. It was found in the small-scale that isocyanates were produced from the majority of the materials tested. The highest concentration was found for glass wool insulation, and further high concentrations were found for PUR products, particleboard, nitrile rubber and melamine. Lower concentrations were found for wood and cable-products. Amino-isocyanates and amines were generally found from PUR products only. The distribution of isocyanates between the particulate- and fluid phases varied for the different materials and a tendency to enrichment of particles was seen for some of the materials. Further, when comparing the potential health hazard between isocyanates and other major fire gases (based on NIOSH IDLH-values) it was found that isocyanates in several cases represented the greatest hazard. Copyright © 2003 John Wiley & Sons, Ltd. [source] Lability of organic carbon in lakes of different trophic statusFRESHWATER BIOLOGY, Issue 6 2009A. P. OSTAPENIA Summary 1. We used first-order kinetic parameters of biological oxygen demand (BOD), the constant of aerobic decomposition (k) and the asymptotic value of BOD (BODult), to characterise the lability of organic carbon pools in six lakes of different trophic state: L. Naroch, L. Miastro and L. Batorino (Belarus), L. Kinneret (Israel), L. Ladoga (Russia) and L. Mendota (U.S.A.). The relative contributions of labile and refractory organic carbon fractions to the pool of total organic carbon (TOC) in these lakes were quantified. We also determined the amounts of labile organic carbon within the dissolved and particulate TOC pools in the three Belarus lakes. 2. Mean annual chlorophyll concentrations (used as a proxy for lake trophic state) ranged from 2.3 to 50.6 ,g L,1, labile organic carbon (OCL = 0.3BODult) from 0.75 to 2.95 mg C L,1 and k from 0.044 to 0.14 day,1. 3. Our data showed that there were greater concentrations of OCL but lower k values in more productive lakes. 4. In all cases, the DOC fraction dominated the TOC pool. OCL was a minor component of the TOC pool averaging about 20%, irrespective of lake trophic state. 5. In all the lakes, most (c. 85%) of the DOC pool was refractory, corresponding with published data based on measurements of bacterial production and DOC depletion. In contrast, a larger fraction (27,55%) of the particulate organic carbon (POC) pool was labile. The relative amount of POC in the TOC pool tended to increase with increasing lake productivity. 6. Long-term BOD incubations can be valuable in quantifying the rates of breakdown of the combined particulate and dissolved organic carbon pools and in characterising the relative proportions of the labile and recalcitrant fractions of these pools. If verified from a larger number of lakes our results could have important general implications. [source] Freshwater and marine virioplankton: a brief overview of commonalities and differencesFRESHWATER BIOLOGY, Issue 6 2008STEVEN W. WILHELM Summary 1. Viruses are a pervasive component of microbial food webs in both marine and freshwater systems. The abundance of viruses in individual aquatic systems appears to be independent of salinity but related to the biomass of primary and secondary producers as well as seasonal effects. Burst size, virus production rate and the percentage of microbial cells carrying a viral burden also appear to be more closely correlated to trophic status than to salinity. 2. In marine environments, the roles of planktonic viruses as regulators of carbon and nutrient cycling as well as microbial community structure have been a focus of numerous studies, yet the roles of freshwater virioplankton remain much less studied. Nevertheless, a survey of published freshwater studies demonstrates that virioplankton recycle important quantities of growth-limiting nutrients from hosts via generation of dead particulate and dissolved organic matter during cell lysis, and suggests that both the chemical speciation and concentration of these organic compounds and nutrients may have important influences on the microbial community. 3. Parallel observations on the spatial patterns and dynamics of microbial mortality due to viruses or grazing are more advanced in freshwaters than in marine environments. However, the constraints that determine whether virus- or grazer-mediated mortality dominates are not yet understood in either environment. 4. Application of molecular approaches has facilitated the examination of the diversity and ecological dynamics of specific viral populations and entire communities. The depth of detail achieved in marine environments towards characterizing these populations and communities is just beginning to be matched in freshwater systems. The few available data suggest that viruses targeting-related hosts in freshwater and marine systems may be genetically distinct. 5. Although the role of viruses in aquatic systems is complex and remains insufficiently studied, our survey of the literature indicates that, despite some differences, many of the controls on virioplankton activity and diversity are similar in marine and freshwater environments. [source] Achieving ,excellent' indoor air quality in commercial offices equipped with air-handling unit , respirable suspended particulateINDOOR AIR, Issue 2 2006K. S. Lam First page of article [source] Numerical model for the prediction of dilute, three-dimensional, turbulent fluid,particle flows, using a Lagrangian approach for particle tracking and a CVFEM for the carrier phaseINTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN FLUIDS, Issue 5 2008L. A. Oliveira Abstract A numerical model for dilute, three-dimensional, turbulent, incompressible fluid,solid particle flows and its application to a demonstration problem are presented. An Eulerian description is used to model the flow of the fluid (carrier) phase, and the governing equations are solved using a control-volume finite element method (CVFEM). The motion of the solid (particulate) phase is simulated using a Lagrangian approach. An efficient algorithm is proposed for locating the particles in the finite element mesh. In the demonstration problem, which involves a particle-laden axisymmetric jet, a modified k,, turbulence model is used to characterize the velocity and length scales of the turbulent flow of the fluid phase. The effect of turbulence on the particle trajectories is accounted for through a stochastic model. The effect of the particles on the fluid time,mean velocity and turbulence (two-way coupling) is also addressed. Comparisons between predictions and available experimental data for the demonstration problem are presented. Satisfactory agreement is obtained. Copyright © 2008 John Wiley & Sons, Ltd. [source] Effect of aroclor 1248 and two pure PCB congeners on phospholipase D activity in rat renal tubular cell culturesJOURNAL OF BIOCHEMICAL AND MOLECULAR TOXICOLOGY, Issue 2 2007Mercedes Fernández Santiago Abstract This paper elucidates the effect of different polychlorinated biphenyls (PCBs) on the phospholipase D (PLD) activity in soluble and particulate fractions of rat renal proximal tubular culture cells. Treatment with Aroclor 1248 (a commercial PCB mixture) caused a marked increase in the activity of PLD in intact renal tubular cells. The PLD activity was increased by Aroclor 1248 in the particulate fraction while the enzyme activity was unaffected in the soluble fraction. This work also shows that PCB 153 (2,2',4,4',5,5'-hexachlorobiphenyl, a di-ortho-substituted nonplanar congener) can increase the activity of PLD only in the particulate fraction. The exposure of cell cultures to PCB 77 (3,3',4,4'-tetrachlorobiphenyl, a non-ortho-substituted planar congener) does not alter PLD activity. These results suggest that PCB effects are structure dependent. Therefore, in order to clarify the molecular mechanism of activation of PLD by PCBs, the contents of immunoreactive PLD were examined by immunoblot analysis. Renal tubular cells expressed a PLD protein of 120 kDa corresponding with the PLD1 mammalian isoform in both the particulate and the soluble fraction. Aroclor 1248, PCB 153, and PCB 77 do not induce changes in the levels of PLD protein. These data indicate that PCBs, particularly nonplanar congeners, increase PLD activity. Moreover, these changes could not be demonstrated in the enzyme content in rat renal tubular cell cultures. © 2007 Wiley Periodicals, Inc. J Biochem Mol Toxicol 21:68,75, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/jbt.20160 [source] Quantitative evaluation of the prosthetic head damage induced by microscopic third-body particles in total hip replacementJOURNAL OF BIOMEDICAL MATERIALS RESEARCH, Issue 4 2001Manuela Teresa Raimondi Abstract The increase of the femoral head roughness in artificial hip joints is strongly influenced by the presence of abrasive particulate entrapped between the articulating surfaces. The aim of the present study is to evaluate the dependence of such damage on the geometry of the particles entrapped in the joint, with reference to the UHMWPE/chrome-cobalt coupling. Five chrome-cobalt femoral heads and their coupled UHMWPE acetabular cups, retrieved at revision surgery after a short period of in situ functioning, have been investigated for the occurrence of third-body damage. This was found on all the prosthetic heads, where the peak-to-valley height of the scratches, as derived from profilometry evaluations, ranged from 0.3,1.3 ,m. The observed damage has been divided into four classes, related to the particle motion while being embedded into the polymer. Two kinds of particle morphology have been studied, spherical and prismatic, with size ranging from 5,50 ,m. In order to provide an estimation of the damage induced by such particles, a finite element model of the third-body interaction was set up. The peak-to-valley height of the impression due to the particle indentation on the chrome-cobalt surface is assumed as an index of the induced damage. The calculated values range from 0.1,0.5 ,m for spherical particles of size ranging from 10,40 ,m. In the case of prismatic particles, the peak-to-valley height can reach 1.3 ,m and depends both on the size and width of the particle's free corner, indenting the chrome-cobalt. As an example, a sharp-edged particle of size 30 ,m can induce on the chrome-cobalt an impression with peak-to-valley height of 0.75 ,m, when embedded into the polyethylene with a free edge of 5 ,m facing the metallic surface. Negligible damage is induced, if a free edge of 7.5 ,m is indenting the counterface. Our findings offer new support to the hypothesis that microscopic third-body particles are capable of causing increased roughening of the femoral head and provide a quantitative evaluation of the phenomenon. © 2001 John Wiley & Sons, Inc. J Biomed Mater Res (Appl Biomater) 58: 436,448, 2001 [source] Anti-gingivitis effect of a dentifrice containing bioactive glass (NovaMin®) particulateJOURNAL OF CLINICAL PERIODONTOLOGY, Issue 2 2006Bao Jun Tai Abstract Background: The objective of this pilot clinical trial was to evaluate the anti-gingivitis and anti-plaque effects of a dentifrice containing bioactive glass (NovaMin®) compared with a placebo control dentifrice in a 6 weeks clinical study. Methods: The study design was a randomized, double-blinded, controlled clinical trial. One hundred volunteers took part in the study and were matched for plaque index (PLI), gingival bleeding index (GBI), age and gender. The protocol was reviewed and approved by the Ethical Committee of the University. The subjects received a supragingival prophylaxis to remove all plaque, calculus and extrinsic stain. Following the baseline examination, subjects were instructed to brush with their assigned dentifrice and toothbrush. The PLI and GBI were determined for the baseline and 6 weeks. The data were analysed using a repeated-measures anova conducted on the two dependent measures to compare the effect between the test and control group. Results: Ninety-five subjects finished the study. The results showed that the PLI (baseline=1.54, 6 weeks=1.29) and GBI (baseline=1.14, 6 weeks=0.47) were significantly reduced, respectively, over the 6 weeks period in the test group (p<0.001 for each measure). There was a 58.8% reduction in gingival bleeding and a 16.4% reduction in plaque growth. There was no difference of the PLI (baseline=1.60, 6 weeks=1.57) and GBI (baseline=1.18, 6-week=1.02) over the 6 week period in the control group. Conclusion: This study demonstrated that a dentifrice containing NovaMin® significantly improves oral health as measured by a reduction in gingival bleeding and reduction in supragingival plaque compared with a negative dentifrice over the 6 weeks study period. [source] Air pollution: A half century of progressAICHE JOURNAL, Issue 6 2004John H. Seinfeld Abstract In the 50 years since the air pollution episodes of Donora, PA and London, U.K., a great deal of progress has been made in understanding the nature and sources of air pollution and the atmospheric transport and transformation of pollutants. Also, many significant technological advances in air pollution control equipment, such as the automobile exhaust gas catalytic converter, have led to effective reduction of emissions from a variety of major pollution sources. Finally, remarkable developments in instrumentation for sampling the trace species in the atmosphere have been and continue to be made. Relatively less progress has been made in understanding the biological mechanisms by which pollutants lead to human injury and mortality. In this review the focus is on the extraordinary progress that has been made over the last half century in understanding the atmospheric nature and behavior of pollutants, both gaseous and particulate. A major breakthrough was the determination of the gas-phase chemistry of both the natural and polluted atmosphere, chemistry that leads to the formation of ozone and a vast array of oxidized molecules. The mechanisms of the oxidation of atmospheric sulfur dioxide, one of the main primary pollutants, were elucidated. Finally, the chemistry, physics, and optics of atmospheric particulate matter (aerosols) have been laid open by many stunning research achievements. Whereas 50 years ago air pollution was thought to be confined to the area around a city, it is now recognized that species emitted on one continent frequently find their way to other continents. Strategies for dealing with a truly global atmospheric backyard now represent a major challenge. © 2004 American Institute of Chemical Engineers AIChE J, 50:1096,1108, 2004 [source] Scrubbing of fly-ash laden SO2 in modified multistage bubble column scrubberAICHE JOURNAL, Issue 9 2002B. C. Meikap The emission of SO2 from various chemical industries is associated with particulate (fly-ash), mostly concentrations of particulate laden sulfur dioxide in and around these plants overshoot the danger point. Prediction of fly-ash laden SO2 removal efficiency is very important for the selection of pollution control equipment. Experimental investigations were conducted on the scrubbing of fly-ash laden SO2 in the modified multistage bubble column scrubber using water. Experimental results show that almost zero penetration (100% removal efficiency) of fly-ash laden SO2 can be achieved in this system. A correlation was developed for predicting the percentage collection efficiency of sulfur dioxide in the presence of fly-ash. Experimental results agreed excellently with the correlation. Enhancement of SO2 collection due to the presence of fly-ash was also quantified. [source] THE ROLE OF PERIPHYTON IN PHOSPHORUS RETENTION IN SHALLOW FRESHWATER AQUATIC SYSTEMSJOURNAL OF PHYCOLOGY, Issue 5 2003Article first published online: 26 SEP 200, Walter K. Dodds Eutrophication caused by phosphorus (P) leads to water quality problems in aquatic systems, particularly freshwaters, worldwide. Processing of nutrients in shallow habitats removes P from water naturally and periphyton influences P removal from the water column in flowing waters and wetlands. Periphyton plays several roles in removing P from the water column, including P uptake and deposition, filtering particulate P from the water, and attenuating flow, which decreases advective transport of particulate and dissolved P from sediments. Furthermore, periphyton photosynthesis locally increases pH by up to 1 unit, which can lead to increased precipitation of calcium phosphate, concurrent deposition of carbonate-phosphate complexes, and long-term burial of P. Actively photosynthesizing periphyton can cause super-saturated O2 concentrations near the sediment surface encouraging deposition of metal phosphates. However, anoxia associated with periphyton respiration at night may offset this effect. Linking the small-scale functional role of periphyton to ecosystem-level P retention will require more detailed studies in a variety of ecosystems or large mesocosms. A case study from the Everglades illustrates the importance of considering the role of periphyton in P removal from wetlands. In general, periphyton tends to increase P retention and deposition. In pilot-scale constructed periphyton-dominated wetlands in South Florida, about half of the inflowing total P was removed. [source] Middle school students' beliefs about matterJOURNAL OF RESEARCH IN SCIENCE TEACHING, Issue 5 2005Mary B. Nakhleh The objective of this study was to examine middle school students' developing understanding of the nature of matter and to compare middle school students' ideas to those of elementary schools students, as was done by Nakhleh and Samarapungavan [J Res Sci Teach 36(7):777,805, 1999]. Nine middle school students were interviewed using a scripted, semistructured interview. The interview probed students' understanding of the composition and particulate (atomic/molecular) structure of a variety of material substances; the relationship between particulate structure and macroscopic properties such as fluidity and malleability; as well as understanding of processes such as phase transition and dissolving. The results indicate that most of the middle school students interviewed knew that matter was composed of atoms and molecules and some of them were able to use this knowledge to explain some processes such as phase transitions of water. In contrast, almost no elementary students knew that matter was composed of atoms and molecules. However, the middle school students were unable to consistently explain material properties or processes based on their knowledge of material composition. In contrast to elementary school students, who had scientifically inaccurate but relatively consistent (macrocontinuous or macroparticulate) knowledge frameworks, the middle school students could not be classified as having consistent knowledge frameworks because their ideas were very fragmented. The fragmentation of middle school students' ideas about matter probably reflects the difficulty of assimilating the microscopic level scientific knowledge acquired through formal instruction into students' initial macroscopic knowledge frameworks. © 2005 Wiley Periodicals, Inc. [source] Al2O3/TiC Based Metal Cutting Tools by Microwave Sintering Followed by Hot Isostatic PressingJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 6 2000Adrian Goldstein The feasibility of producing Al2O3/TiC metal cutting tools by fast microwave sintering followed by hot isostatic pressing was examined. Microwave heating profiles able to ensure near-full densification of Al2O3/TiC ceramic components were determined. Simple-shape specimens could be sintered to a bulk density of 97% theoretical density (TD) while in the case of tool-shaped ones maximal densification levels attained were somewhat lower, i.e., ,95% TD. Temperature uniformization,within the heating chamber,by using a particulate SiC susceptor noticeably reduced tool cracking propensity. Densification levels in the range acceptable for commercial tool manufacturing (,98% TD) were achieved by hot isostatic pressing of the microwave-sintered parts. The isostatically pressed parts exhibited a Vickers hardness Hv, 2000 kg/mm2 and a fracture toughness KIC, 4.3 MPa·m1/2. [source] Air pollution and hospitalization for venous thromboembolic disease in ChileJOURNAL OF THROMBOSIS AND HAEMOSTASIS, Issue 4 2010R. E. DALES See also Mannucci PM. Fine particulate: it matters. This issue, pp 659,61; Bonzini M, Tripodi A, Artoni A, Tarantini L, Marinelli B, Bertazzi PA, Apostoli P, Baccarelli A. Effects of inhalable particulate matter on blood coagulation. This issue, pp 662,8. Summary.,Background:,Ambient air pollution is a risk factor for stroke and myocardial infarction, possibly because of alterations in coagulation that influence the arterial circulation. Whether air pollution influences diseases associated with peripheral venous thrombogenesis remains largely unknown. Objectives: To determine the association between air pollution and venous thromboembolic disease (VTE) in a sample of the general population. Methods: A time-series analysis was used to test the association between daily air pollution and VTE hospitalizations in Santiago between 2001 and 2005. Results were adjusted for long-term trends, day of the week and average daily humidex. Results: From a population of 5.4 million, there were, on average, 2.3 admissions for VTE per day. Pooled estimates of relative risk (RR) [95% confidence interval (CI)] of hospitalization for venous disease were: 1.07 (1.05, 1.09) for a 58.4 p.p.b. increase in ozone (O3); 1.06 (1.02, 1.09) for a 5.85 p.p.b. increase in sulphur dioxide (SO2); 1.08 (1.03, 1.12) for a 29.25 ,g/m3 increase in nitrogen dioxide (NO2); and 1.05 (1.03, 1.06) for a 20.02 ,g/m3 increase in particulate matter , 2.5 ,m in mean aerodynamic diameter (PM2.5). For pulmonary embolism (PE) results were: 1.10 (1.07, 1.13) for O3; 1.05 (1.02, 1.08) for SO2; 1.07 (1.04, 1.09) for NO2; and 1.05(1.03, 1.06) for PM2.5, respectively. Conclusion: Air pollution appears to be a risk factor for venous thrombosis and PE, a disease with a significant fatality rate. [source] Short-term effects of air pollution on cardiovascular diseases: outcomes and mechanismsJOURNAL OF THROMBOSIS AND HAEMOSTASIS, Issue 11 2007M. FRANCHINI Summary. The effects of air pollution on health have been intensively studied in recent years. Acute exposure to environmental pollutants such as particulate and gaseous matters (carbon monoxide, nitrogen oxides, sulphur dioxide and ozone) was associated with an increased rate of events and mortality because of cardiovascular diseases. These effects were investigated in short-term studies, which related day-to-day variations in air pollution to disease, and in long-term studies, which have followed cohorts of exposed individuals over time. The evidence from the literature on the short-term cardiovascular effects of air pollutants is discussed from clinical and mechanistic points of view. [source] Partition of metals in the Vistula River and in effluents from sewage treatment plants in the region of Cracow (Poland)LAKES & RESERVOIRS: RESEARCH AND MANAGEMENT, Issue 2 2000C. Guéguen Abstract The Vistula River suffers from heavy pollution with multiple origins. In the upper reaches, metallic and chlorine pollution originates from the mining and industrial region of Upper Silesia. Downstream from Upper Silesia, urban and industrial sewage adds more metallic and organic contaminants from the large urban agglomeration of Cracow. Although the river status is monitored routinely, little is known about the partition of metals between particulate and dissolved forms. This study focuses on metal partitioning and on the impact of the two main wastewater treatment plants at Cracow on metal concentrations in the Vistula River. The Cd, Co, Cu, Mn, Pb and Zn content was measured in both dissolved and particulate fractions. High metal concentrations in the Vistula River persist, although current levels seem to be lower than those in the past. Metal concentrations in the Vistula River and effluents from the sewage treatment plants at Cracow are similar, indicating a relatively minor contribution from the treated sewage. However, untreated sewage may be a significant source of contaminants. Despite high anthropogenic metal concentrations, the metal partitioning coefficients (Kd) in the Vistula are similar to these found in unpolluted rivers. Within a narrow pH range, Kd values depend on the metal affinity to particles, but there is no evidence of dependence on particle or chloride concentrations. An important fraction of the toxic metals Pb and Cd is associated with particles, which may decrease their immediate availability to the biota of the river. [source] The allergen Bet v 1 in fractions of ambient air deviates from birch pollen countsALLERGY, Issue 7 2010J. T. M. Buters To cite this article: Buters JTM, Weichenmeier I, Ochs S, Pusch G, Kreyling W, Boere AJF, Schober W, Behrendt H. The allergen Bet v 1 in fractions of ambient air deviates from birch pollen counts. Allergy 2010; 65: 850,858. Abstract Background:, Proof is lacking that pollen count is representative for allergen exposure, also because allergens were found in nonpollen-bearing fractions of ambient air. Objective:, We monitored simultaneously birch pollen and the major birch pollen allergen Bet v 1 in different size fractions of ambient air from 2004 till 2007 in Munich, Germany. Methods:, Air was sampled with a ChemVol® high-volume cascade impactor equipped with stages for particulate matter (PM)>10 ,m, 10 ,m>PM>2.5 ,m, and 2.5 ,m>PM>0.12 ,m. Allergen was determined with a Bet v 1-specific ELISA. Pollen count was assessed with a Burkard pollen trap. We also measured the development of allergen in pollen during ripening. Results:, About 93 ± 3% of Bet v 1 was found in the PM,>,10 ,m fraction, the fraction containing birch pollen. We did not measure any Bet v 1 in 2.5 ,m,>,PM,>,0.12 ,m. Either in Munich no allergen was in this fraction or the allergen was absorbed to diesel soot particles that also deposit in this fraction. Pollen released 115% more Bet v 1 in 2007 than in 2004. Also within 1 year, the release of allergen from the same amount of pollen varied more than 10-fold between different days. This difference was explained by a rapidly increasing expression of Bet v 1 in pollen in the week just before pollination. Depending on the day the pollen is released during ripening, its potency varies. Conclusion:, In general, pollen count and allergen in ambient air follow the same temporal trends. However, because a 10-fold difference can exist in allergen potency of birch pollen, symptoms might be difficult to correlate with pollen counts, but perhaps better with allergen exposure. [source] EPR oximetry in the beating heart: Myocardial oxygen consumption rate as an index of postischemic recoveryMAGNETIC RESONANCE IN MEDICINE, Issue 4 2004Govindasamy Ilangovan Abstract Oxygen plays a critical role in the pathophysiology of myocardial injury during both ischemia and subsequent reperfusion (I/R). Thus, oxygen concentration is an important variable to measure during I/R. In the present work, electron paramagnetic resonance (EPR)-based oximetry was used to measure the oxygen concentration during a series of I/R episodes and oxygenation levels were correlated with the contractile and hemodynamic functions of the heart. A custom-developed electronically tunable surface coil resonator working at 1.1 GHz was used to determine tissue pO2 in the beating heart. Microcrystalline particulate of lithium phthalocyanine was used as an EPR oximetry probe. Isolated and perfused rat hearts were subjected to 1 or 3 hr durations of preischemic perfusion, followed by 15-min I/R cycles. In hearts perfused for 3 hr prior to 15-min I/R cycles, the myocardial pO2 decreased gradually on subsequent reperfusions of three successive I/R cycles. However, in hearts perfused for 1 hr there was almost 100% recovery of myocardial pO2 in all three I/R cycles. The extent of oxygenation recovered in each reperfusion cycle correlated with the recovery of hemodynamic and contractile function. The results also showed that the oxygen consumption rate of the heart at the end of each I/R episode decreased in direct proportion to the functional recovery. In summary, it was observed that the amount of myocardial oxygen consumption during I/R could provide a reliable index of functional impairment in the heart. Magn Reson Med 51:835,842, 2004. © 2004 Wiley-Liss, Inc. [source] Design of forming shoulders with complex cross-sectionsPACKAGING TECHNOLOGY AND SCIENCE, Issue 4 2005C. J. McPherson Abstract Vertical ,form, fill and seal' machines are used to produce bags for packing particulate or multiple objects. In operation, film is drawn over a forming shoulder and the good design of the surfaces of the shoulder is vital to the successful operation. This paper reviews underlying geometrical definition for the shoulder, corresponding to a filling tube with circular cross-section. In practice, such cross-sections occur frequently, but other variant shapes are becoming increasingly common. A method is discussed and demonstrated for extending the approach to allow tubes formed from circular arcs and straight line segments to be handled. Copyright © 2005 John Wiley & Sons, Ltd. [source] | |||||||||||||||||||||||||||||||||||||||||||