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Elemental Composition (elemental + composition)
Selected AbstractsTaxonomic and regional patterns in benthic macroinvertebrate elemental composition in streamsFRESHWATER BIOLOGY, Issue 11 2005MICHELLE A. EVANS-WHITE Summary 1. Ecological stoichiometry has been used to better understand dynamics in consumer growth and the role of consumer-recycled nutrients because it focuses on more than one element. Most research has focused on pelagic rather than benthic consumers. Variation in elemental composition among benthic consumer taxa would suggest that taxa differ in their susceptibility to nutrient limitation or in their role in recycling nutrients. 2. We collected benthic macroinvertebrates from streams in two regions (Indiana,Michigan and Wisconsin, U.S.A.) to examine taxonomic and regional variation in benthic macroinvertebrate body carbon (C), nitrogen (N), and phosphorus (P) concentrations and ratios. 3. Elemental composition varied little within taxa common to both regions. In contrast, elemental composition differed greatly among taxa and appeared to be related to phylogeny. The elemental composition of macroinvertebrates clustered into three distinct groups: insects, mollusks, and crustaceans. To a lesser extent, insects and mollusks also differed in elemental composition among genera. 4. Functional feeding groups (FFGs) differed in elemental composition, with predators having a higher N content than other groups. Substantial elemental imbalances between C and N were found between most primary consumers and their likely food sources, and the magnitude of the imbalance depended in part on the FFG. 5. Our results support an assumption of most ecological stoichiometry models that, within a species, the elemental composition of aquatic invertebrates is relatively constant. Variation in elemental composition among taxa at various higher taxonomic levels suggests that susceptibility of stream invertebrates to nutrient limitation and their role in nutrient cycling will strongly depend on phylogeny. [source] Simple Relationship for Predicting Impact Sensitivity of Nitroaromatics, Nitramines, and NitroaliphaticsPROPELLANTS, EXPLOSIVES, PYROTECHNICS, Issue 2 2010Hossein Keshavarz, Mohammad Abstract This paper describes the development of a simple model for predicting the impact sensitivity of nitroaromatics, benzofuroxans, nitroaromatics with ,-CH, nitramines, nitroaliphatics, nitroaliphatics containing other functional groups, and nitrate energetic compounds using their molecular structures. The model is optimized using a set of 86 explosives for which different structural parameters exist. The model is applied to a test set of 120 explosives from a variety of the mentioned chemical families in order to confirm the reliability of a new method. Elemental composition and two specific structural parameters, that can increase or decrease impact sensitivity, would be needed in this new scheme. The predicted impact sensitivities for both sets have a root mean square (rms) of deviation from experiment of 23,cm, which shows good agreement with respect to the measured values as compared to the best available empirical correlations. [source] Nanostructure Copper-exchanged ZSM-5 Catalytic Activity for Conversion of Volatile Organic Compounds (Toluene and Ethyl Acetate)CHINESE JOURNAL OF CHEMISTRY, Issue 2 2010S. Ali Hosseini Abstract Gas phase catalytic oxidation of ethyl acetate and toluene was examined over copper modified ZSM-5 catalysts under atmospheric pressure. Nanostructure of ZSM-5 was characterized by XRD, SEM and TEM techniques. Elemental composition of ZSM-5 was determined using EDX, ICP-AES and XPS techniques. Results of catalytic studies showed better catalytic activity of Cu-ZSM-5 catalysts than those of parent ZSM-5 and HZSM-5, which revealed catalytic role of copper ions in the Cu-ZSM-5 catalysts. Effects of some parameters over catalytic conversion of these compounds were also studied. Ethyl acetate showed more reactivity than toluene over the Cu-ZSM-5 catalysts. Furthermore, the catalytic activity of Cu-ZSM-5 catalysts increased with increasing the copper loadings. The conversion behavior of a binary mixture of ethyl acetate and toluene was different from that of a single form. A promotive and inhibitive behavior was observed for conversion of ethyl acetate and toluene in the binary mixture, respectively. Water vapor as co-feed had an inhibitive effect on conversion of organic compounds over the Cu-ZSM-5 catalysts. [source] Strategy for the elucidation of elemental compositions of trace analytes based on a mass resolution of 100 000 full width at half maximumRAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 14 2010Anton Kaufmann Elemental compositions (ECs) can be elucidated by evaluating the high-resolution mass spectra of unknown or suspected unfragmented analyte ions. Classical approaches utilize the exact mass of the monoisotopic peak (M,+,0) and the relative abundance of isotope peaks (M,+,1 and M,+,2). The availability of high-resolution instruments like the Orbitrap currently permits mass resolutions up to 100 000 full width at half maximum. This not only allows the determination of relative isotopic abundances (RIAs), but also the extraction of other diagnostic information from the spectra, such as fully resolved signals originating from 34S isotopes and fully or partially resolved signals related to 15N isotopes (isotopic fine structure). Fully and partially resolved peaks can be evaluated by visual inspection of the measured peak profiles. This approach is shown to be capable of correctly discarding many of the EC candidates which were proposed by commercial EC calculating algorithms. Using this intuitive strategy significantly extends the upper mass range for the successful elucidation of ECs. Copyright © 2010 John Wiley & Sons, Ltd. [source] Effects of annealing on structural, electrical and optical properties of AgGa(Se0.5S0.5)2 thin films deposited by using sintered stoichometric powderCRYSTAL RESEARCH AND TECHNOLOGY, Issue 4 2009H. Karaagac Abstract The structural, electrical and optical properties of AgGa(Se0.5S0.5 )2 thin films deposited by using the thermal evaporation method have been investigated as a function of annealing in the temperature range of 450,600 °C. X-ray diffraction (XRD) analysis showed that the structural transformation from amorphous to polycrystalline structure started at 450 oC with mixed binary phases of Ga2Se3, Ga2S3, ternary phase of AgGaS2 and single phase of S. The compositional analysis with the energy dispersive X-ray analysis (EDXA) revealed that the as-grown film has different elemental composition with the percentage values of Ag, Ga, Se and S being 5.58, 27.76, 13.84 and 52.82 % than the evaporation source powder, and the detailed information about the stoichometry and the segregation mechanisms of the constituent elements in the structure have been obtained. The optical band gap values as a function of annealing temperature were calculated as 2.68, 2.85, 2.82, 2.83, and 2.81 eV for as-grown, annealed at 450, 500, 550, and 600 °C samples, respectively. It was determined that these changes in the band gap are related with the structural changes with annealing. The temperature dependent conductivity measurements were carried out in the temperature range of 250-430 K for all samples. The room temperature resistivity value of as-grown film was found to be 0.7x108 (,-cm) and reduced to 0.9x107 (,-cm) following to the annealing. From the variation of electrical conductivity as a function of the ambient temperature, the activation energies at specific temperature intervals for each sample were evaluated. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] What can otolith examination tell us about the level of perturbations of Salmonid fish from the Kerguelen Islands?ECOLOGY OF FRESHWATER FISH, Issue 4 2008F. Morat Abstract,,, Otoliths preserve a continuous record of the life cycle from the natal through the adult stage. For that reason, the morphological and chemical characteristics of otoliths of two nonnative Salmonids, brown trout (Salmo trutta) and brook charr (Salvelinus fontinalis) from populations on the Kerguelen Islands were compared. Several approaches were used to study the relationships between otolith morphometry, crystal morph and chemical elemental composition. These salmonids sampled in Kerguelen are well differentiated in terms of species through their otolith shape. The results indicate that ecotypes and river populations can be reasonably well differentiated on the basis of otolith shape. The crystallisation study has revealed the presence of a particular form: the vaterite, present at a high rate: 45% of S. fontinalis and 18% from Salmo trutta fario. Moreover, vaterite and aragonite otoliths presented differences in chemical composition. [source] Ion-Selective Electrodes for Thiocyanate Based on the Dinuclear Zinc(II) Complex of a Bis- N,O -bidentate Schiff BaseELECTROANALYSIS, Issue 12 2004Philippe Bühlmann Abstract An ion selective electrode based on the dinuclear complex formed by two zinc(II) ions and two molecules of the bis- N,O -bidentate Schiff base 2,2,-[methylenebis(4,1-phenylenenitrilomethylidyne)]bisphenol exhibits thiocyanate selectivity with a good discrimination of nitrite, nitrate, and azide. The selectivities of electrode membranes with various compositions indicate that this potentiometric selectivity is based on the formation of a 1,:,1 complex between the thiocyanate anion and the dinuclear ionophore. The 2,:,1 ratio of thiocyanate ions and the dinuclear ionophore that results from higher ratios of cationic sites and ionophore worsens the selectivity, suggesting that binding of a thiocyanate to both zinc(II) centers of the dinuclear ionophore is not favorable. Interestingly, the selectivity patterns of these electrodes differ radically from that of a highly sulfate selective electrode based on a compound reported previously to be the analogous mononuclear 1,:,1 complex of zinc(II) and the same Schiff base. It is suggested that the previously reported 1,:,1 complex with zinc(II) may indeed have been a polymer of the same elemental composition. [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] A novel, multi-layered methanotrophic microbial mat system growing on the sediment of the Black SeaENVIRONMENTAL MICROBIOLOGY, Issue 8 2008Martin Krüger Summary A novel microbially diverse type of 1- to 5-cm-thick mat performing anaerobic oxidation of methane (AOM) and covering several square metres of the seafloor was discovered in the Black Sea at 180 m water depth. Contrary to other AOM-mat systems of the Black Sea these floating mats are not associated to free gas and are not stabilized by authigenic carbonates. However, supply of methane is ensured by the horizontal orientation of the mats acting as a cover of methane enriched fluids ascending from the underlying sediments. Thorough investigation of their community composition by molecular microbiology and lipid biomarkers, metabolic activities and elemental composition showed that the mats provide a clearly structured system with extracellular polymeric substances (EPS) building the framework of the mats. The top black zone, showing high rates of AOM (15 ,mol gdw,1 day,1), was dominated by ANME-2, while the following equally active pink layer was dominated by ANME-1 Archaea. The lowest AOM activity (2 ,mol gdw,1 day,1) and cell numbers were found in the greyish middle part delimited towards the sediment by a second pink, ANME-1-dominated and sometimes a black outer layer (ANME-2). Our work clearly shows that the different microbial populations are established along defined chemical gradients such as methane, sulfate or sulfide. [source] The molecular composition of soil organic matter as determined by 13C NMR and elemental analyses and correlation with pesticide sorptionEUROPEAN JOURNAL OF SOIL SCIENCE, Issue 6 2006R. Ahmad Summary Although the chemical composition of soil organic matter (SOM) is known to significantly influence sorption of pesticides and other pollutants, it has been difficult to determine the molecular nature of SOM in situ. Here, using 13C nuclear magnetic resonance (NMR) data and elemental composition in a molecular mixing model, we estimated the molecular components of SOM in 24 soils from various agro-ecological regions. Substantial variations were revealed in the molecular nature of SOM. As a proportion of soil carbon the proportion of the carbonyl component ranged from 0.006 to 0.05, charcoal from 0 to 0.15, protein from 0.09 to 0.29, aliphatic from 0.14 to 0.30, carbohydrate from 0.21 to 0.31, and lignin from 0.05 to 0.42. The relationships between Koc (sorption per unit mass of organic carbon) of carbaryl (1-naphthyl methylcarbamate) and phosalone (S- 6-chloro-2,3-dihydro-2-oxobenzoxazol-3-ylmethyl O,O -diethyl phosphorodithioate) and the molecular nature of organic matter in the soils were significant. Of the molecular components estimated, lignin and charcoal contents correlated best with sorption of carbaryl and phosalone. Aliphatic, carbohydrate and protein contents were found to be negatively correlated with the Koc of both pesticides. The study highlights the importance of the molecular nature of SOM in determining sorption affinities of non-ionic pesticides and presents an indirect method for sorption estimation of pesticides. [source] A systematic approach to nuclear microscopy of water trees for a large number of field-aged HV cable samplesEUROPEAN TRANSACTIONS ON ELECTRICAL POWER, Issue 1 2006M. Ahmed Abstract In order to perform micro-PIXE measurements on water trees in underground HV cables when a large number of cable samples are involved, a sequence of tests has been devised to minimize time and effort for sample preparation, water tree detection and analysis. These tests include electrical diagnostic tests to predict the possible presence of water trees, optical microscopy on cable insulation to detect water trees in the samples screened by the electrical tests, scanning electron microscopy for detailed surface topography of water trees, and nuclear microscopy for elemental composition and distribution maps of water trees. Correlations among the results of the four types of measurements are discussed to evaluate the usefulness of the methodology. Copyright © 2005 John Wiley & Sons, Ltd. [source] Resource quality and stoichiometric constraints on stream ecosystem functioningFRESHWATER BIOLOGY, Issue 5 2009SALLY HLADYZ Summary 1. Resource quality and stoichiometric imbalances in carbon : nutrient ratios between consumers and resources can influence key ecosystem processes. In many streams, this has important implications for food webs that are based largely upon the utilization of terrestrial leaf-litter, which varies widely among litter types in its value as a food source for detritivores and as a substrate for microbial decomposers. 2. We measured breakdown rates and macroinvertebrate colonization of leaf-litter from a range of native and exotic plants of differing resource quality and palatability to consumers [e.g. carbon : nitrogen : phosphorus (C : N : P) ratios, lignin and cellulose content], in a field experiment. We also measured C : N : P ratios of the principal leaf-shredding invertebrates, which revealed strong stoichiometric imbalances across trophic levels: C : N and C : P ratios typically differed by at least one order of magnitude between consumers and resources, whereas N : P imbalances were less marked. Application of the threshold elemental ratio approach, which integrates animal bioenergetics and body elemental composition in examining nutrient deficiency between consumers and resources, revealed less marked C : P imbalances than those based on the simpler arithmetic differences described above. 3. Litter breakdown rates declined as nutrient imbalances widened and resource quality fell, but they were independent of whether resources were exotic or native. The principal drivers of total, microbial and invertebrate-mediated breakdown rates were lignin : N, lignin : P and fungal biomass, respectively. However, multiple regression using orthogonal predictors yielded even more efficient models of litter breakdown, as consumers responded to more than one aspect of resource quality. For example, fungal biomass and litter C : N both influenced invertebrate-mediated breakdown. 4. Large stoichiometric imbalances and changes in resource quality are likely to have serious consequences for stream ecosystem functioning, especially when riparian zones have been invaded by exotic plant species whose chemical composition differs markedly from that of the native flora. Consequently, the magnitude and direction of change in breakdown rates and, thus, resource depletion, will be driven to a large extent by the biochemical traits (rather than taxonomic identity per se) of the resident and invading flora. [source] Effects of food-web structure on periphyton stoichiometry in eutrophic lakes: a mesocosm studyFRESHWATER BIOLOGY, Issue 10 2008M. DANGER Summary 1. Aquatic herbivores typically have much higher concentrations of nutrients (e.g. N and P) in their tissues than there is in the food they eat. These stoichiometric differences can cause herbivores to be limited by the elemental quality of their food, which could affect, in turn, the structure of consumer communities and even alter key ecosystem processes. 2. In streams and in the littoral zone of shallow lakes, periphyton is an important food resource for benthic animals. Studying the elemental composition of periphyton may help us to understand food-web structure, and any reciprocal effect of this structure on periphyton stoichiometry. 3. To understand how alterations in the food-web structure affect the elemental composition of periphyton in a eutrophic lake, we carried out a long-term experiment (14 months) in large-scale mesocosms (40 m3), in which we manipulated food-web structure, and which were dominated either by planktivorous fish (Rutilus rutilus) or herbivorous invertebrates (without fish). Periphyton was sampled monthly at three depths (0.5, 1.5 and 2.5 m) to determine its biomass and elemental composition (C/N/P ratio). Food-web structure, physical and chemical parameters were monitored throughout the experiment. 4. Fish had indirect positive effect on periphyton biomass, leading to twofold higher levels than in herbivore-dominated mesocosms. This result was probably due to control of benthic consumers by fish, suggesting a strong top,down control on periphyton by their consumers in fishless enclosures. 5. The elemental ratios C/P and C/N were lower in deep water in both treatments, mainly mediated by light availability, in accordance with the light/nutrient ratio hypothesis. These ratios were also lower in fishless treatments, probably due to increases in inorganic nutrient availability and grazing pressure in herbivore-dominated systems. During winter, periphyton elemental composition was similar in both treatments, and was unrelated to inorganic nutrient availability. 6. These results indicate that any alteration of food-web structure in lakes, such as in biomanipulation experiments, is likely to modify both the biomass and elemental quality of periphyton. Resultant effects on the consumers of periphyton and macrophytes could play a key role in the success of biomanipulations and should be taken into account in further studies. [source] Taxonomic and regional patterns in benthic macroinvertebrate elemental composition in streamsFRESHWATER BIOLOGY, Issue 11 2005MICHELLE A. EVANS-WHITE Summary 1. Ecological stoichiometry has been used to better understand dynamics in consumer growth and the role of consumer-recycled nutrients because it focuses on more than one element. Most research has focused on pelagic rather than benthic consumers. Variation in elemental composition among benthic consumer taxa would suggest that taxa differ in their susceptibility to nutrient limitation or in their role in recycling nutrients. 2. We collected benthic macroinvertebrates from streams in two regions (Indiana,Michigan and Wisconsin, U.S.A.) to examine taxonomic and regional variation in benthic macroinvertebrate body carbon (C), nitrogen (N), and phosphorus (P) concentrations and ratios. 3. Elemental composition varied little within taxa common to both regions. In contrast, elemental composition differed greatly among taxa and appeared to be related to phylogeny. The elemental composition of macroinvertebrates clustered into three distinct groups: insects, mollusks, and crustaceans. To a lesser extent, insects and mollusks also differed in elemental composition among genera. 4. Functional feeding groups (FFGs) differed in elemental composition, with predators having a higher N content than other groups. Substantial elemental imbalances between C and N were found between most primary consumers and their likely food sources, and the magnitude of the imbalance depended in part on the FFG. 5. Our results support an assumption of most ecological stoichiometry models that, within a species, the elemental composition of aquatic invertebrates is relatively constant. Variation in elemental composition among taxa at various higher taxonomic levels suggests that susceptibility of stream invertebrates to nutrient limitation and their role in nutrient cycling will strongly depend on phylogeny. [source] Indoor/outdoor concentrations and elemental composition of PM10/PM2.5 in urban/industrial areas of Kocaeli City, TurkeyINDOOR AIR, Issue 2 2010B. Pekey Abstract, This study presents indoor/outdoor PM2.5 and PM10 concentrations measured during winter and summer in 15 homes in Kocaeli, which is one of the most industrialized areas in Turkey. Indoor and outdoor PM2.5 and PM10 mass concentrations and elemental composition were determined using an X-ray fluorescence spectrometer. Quantitative information was obtained on mass concentrations and other characteristics such as seasonal variation, indoor/outdoor (I/O) ratio, PM2.5/PM10 ratio, correlations and sources. Average indoor and outdoor PM2.5 concentrations were 29.8 and 23.5 ,g/m3 for the summer period, and 24.4 and 21.8 ,g/m3 for the winter period, respectively. Average indoor and outdoor PM10 concentrations were 45.5 and 59.9 ,g/m3 for the summer period, and 56.9 and 102.3 ,g/m3 for the winter period, respectively. A varimax rotated factor analysis (FA) was performed separately on indoor and outdoor datasets in an effort to identify possible heavy metal sources of PM2.5 and PM10 particle fractions. FA of outdoor data produced source categories comprising polluted soil, industry, motor vehicles, and fossil fuel combustion for both PM fractions, while source categories determined for indoor data for both PM2.5 and PM10 comprised industry, polluted soil, motor vehicles, and smoking, with an additional source category of cooking activities detected for the PM2.5 fraction. Practical Implications In buildings close to industrial areas or traffic arteries, outdoor sources may have an important effect on indoor air pollution. Therefore, indoor and outdoor investigations should be conducted simultaneously to assess the relationship between indoor and outdoor pollution. This study presents the simultaneous measurement of PM fractions (PM2.5 and PM10) and their elemental compositions to determine the sources of respirable PM and the heavy metals bound to these particles in indoor air. Factor analysis of indoor data indicated that the contribution of outdoor pollutant sources to indoor pollution was about 70%, making these sources the most significant for indoor heavy metal pollution, wheras other sources of indoor pollution included smoking and cooking activities. [source] Use of trace elements in feathers of sand martin Riparia riparia for identifying moulting areasJOURNAL OF AVIAN BIOLOGY, Issue 3 2003Tibor Szép We investigated whether trace elements in tail feathers of an insectivorous and long-distance migratory bird species could be used to identify moulting areas and hence migratory pathways. We analysed tail feathers from birds of different age and sex collected from a range of different breeding sites across Europe. The site of moult had a large effect on elemental composition of feathers of birds, both at the European and African moulting sites. Analysis of feathers of nestlings with known origin suggested that the elemental composition of feathers depended largely upon the micro-geographical location of the colony. The distance between moulting areas could not explain the level of differences in trace elements. Analysis of feathers grown by the same individuals on the African wintering grounds and in the following breeding season in Europe showed a large difference in composition indicating that moulting site affects elemental composition. Tail feathers moulted in winter in Africa by adults breeding in different European regions differed markedly in elemental composition, indicating that they used different moulting areas. Analysis of tail feathers of the same adult individuals in two consecutive years showed that sand martins in their first and second wintering season grew feathers with largely similar elemental composition, although the amounts of several elements in tail feathers of the older birds was lower. There was no difference between the sexes in the elemental composition of their feathers grown in Africa. Investigation of the trace element composition of feathers could be a useful method for studying similarity among groups of individuals in their use of moulting areas. [source] Metallurgical characterization, galvanic corrosion, and ionic release of orthodontic brackets coupled with Ni-Ti archwiresJOURNAL OF BIOMEDICAL MATERIALS RESEARCH, Issue 1 2007Myrsini S. Darabara Abstract In orthodontics, a combination of metallic alloys is placed into the oral cavity during medical treatment and thus the corrosion resistance and ionic release of these appliances is of vital importance. The aim of this study is to investigate the elemental composition, microstructure, hardness, corrosion properties, and ionic release of commercially available orthodontic brackets and Copper Ni-Ti archwires. Following the assessment of the elemental composition of the orthodontic wire (Copper Ni-TiÔ) and the six different brackets (Micro Loc, Equilibrium, OptiMESHXRT, Gemini, Orthos2, and Rematitan), cyclic polarization curves were obtained for each material to estimate the susceptibility of each alloy to pitting corrosion in 1M lactic acid. Galvanic corrosion between the orthodontic wire and each bracket took place in 1M lactic acid for 28 days at 37°C and then the ionic concentration of Nickel and Chromium was studied. The orthodontic wire is made up from a Ni-Ti alloy with copper additions, while the orthodontic brackets are manufactured by different stainless steel grades or titanium alloys. All tested wires and brackets with the exception of Gemini are not susceptible to pitting corrosion. In galvanic corrosion, following exposure for 28 days, the lowest potential difference (,250 mV) appears for the orthodontic wire Copper Ni-Ti and the bracket made up from pure titanium (Rematitan) or from the stainless steel AISI 316 grade (Micro Loc). Following completion of the galvanic corrosion experiments, measurable quantities of chromium and nickel ions were found in the residual lactic acid solution. © 2006 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2006 [source] Porosity and surface characteristics of activated carbons produced from waste tyre rubberJOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 1 2002Guillermo San Miguel Abstract Waste tyre rubber has proven to be a suitable precursor for the production of high quality activated carbons. The performance of these carbons in commercial applications such as water treatment or gas purification is highly dependent on their surface characteristics. This paper presents an in-depth investigation on how production conditions may affect the yield and characteristics of activated carbons produced from tyre rubber. For this purpose, three tyre rubbers of different particle sizes were consecutively pyrolysed and then activated in a steam atmosphere at 925,°C using a laboratory-scale rotary furnace. Activation was conducted at different intervals over 80,640,min to achieve different degrees of carbon burn-off. The resulting carbons were analysed for their elemental composition, ash content and nitrogen gas adsorption characteristics. The BET and t -plot models were used to investigate various aspects of their porosity and surface area characteristics. SEM analyses were also conducted for visual examination of the carbon surface. Results show that pyrolytic chars, essentially mesoporous materials, developed a very narrow microporosity during the initial stages of the activation process (up to 15,25,wt% burn-off). Further activation resulted in the progressive enlargement of the average micropore width and a gradual development of the mesoporous structure. Total micropore volumes and BET surface areas increased continuously with the degree of activation to reach values up to 0.498,cm3g,1 and 1070,m2g,1 respectively, while external surface areas developed more rapidly at degrees of activation above 45,wt% burn-off. Results presented in this work also illustrate that carbons produced from powdered rubber developed a narrower and more extensive porosity, both in the micropore and mesopore range, than those produced from rubber of a larger particle size. © 2001 Society of Chemical Industry [source] Effect of diet on otolith composition in Pomatomus saltatrix, an estuarine piscivoreJOURNAL OF FISH BIOLOGY, Issue 6 2004J. A. Buckel To test the hypothesis that elemental composition of otoliths (sagittae) could be influenced by differences in natural prey type, young-of-the-year bluefish Pomatomus saltatrix were captured immediately after their migration from oceanic waters into mid-Atlantic Bight estuaries and fed either shrimp, Crangon septemspinosa and Palaemonetes spp. or fish Menidia menidia under similar temperature and salinity regimes in two separate 60 day experiments. Unlimited rations of fish and shrimp prey were provided in the first experiment which led to differences in bluefish growth rate between the two prey treatments; fish prey was limited in the second experiment to ensure that growth rates of bluefish in the two prey treatments were similar. Concentrations of seven elements in bluefish otoliths were determined using solution-based inductively coupled plasma mass spectrometry (ICPMS). There was no significant effect of diet on five of the seven elements examined (Na, Mg, K, Ca and Mn). The levels of Sr and Ba in the otoliths of shrimp-fed bluefish, however, were significantly higher than fish-fed bluefish in both experiments. Concentrations of Ba in shrimp-fed bluefish otoliths were double that found in fish-fed bluefish. The results suggest that diet can explain some of the variation in otolith chemistry previously attributed to physical and chemical properties of the water. [source] Morphometry and composition of aragonite and vaterite otoliths of deformed laboratory reared juvenile herring from two populationsJOURNAL OF FISH BIOLOGY, Issue 6 2003J. Tomás Vaterite otoliths were sampled from two reared populations (Celtic and Clyde Seas) of juvenile herring Clupea harengus. The crystallography, elemental composition and morphometry were analysed and compared with those of normal aragonite otoliths. The incidence of vaterite otoliths in the juveniles sampled (n = 601) ranged from 7·8% in the Clyde population to 13·9% in the Celtic Sea population, and was 5·5% in the small sample (n = 36) of wild adults examined. In all but one case fish had only one vaterite otolith; the corresponding otolith of the pair was completely aragonite. Although the majority of the juveniles sampled showed craniofacial deformities, there was no link between the skull or jaw malformation and the incidence of vaterite otoliths. All vaterite otoliths had an aragonite inner area, and vaterite deposition began sometime after the age of 90 days. The vaterite otoliths were larger and lighter than their corresponding aragonite partners, and were less dense as a consequence of the vaterite crystal structure. The vaterite areas of the otoliths were depleted in Sr, Na and K. Concentrations of Mn were higher in the vaterite areas. The transition between the aragonite inner areas and the vaterite areas was sharply delineated. Within a small spatial scale (20 ,m3) in the vaterite areas, however, there was co-precipitation of both vaterite and aragonite. The composition of the aragonite cores in the vaterite otoliths was the same as in the cores of the normal aragonite otoliths indicating that the composition of the aragonite cores did not seed the shift to vaterite. Vaterite is less dense than aragonite, yet the concentrations of Ca analysed with wavelength-dispersive spectrometry (WDS) were the same between the two polymorphs, indicating that Ca concentrations measured with WDS are not a good indicator of hypermineralized zones with high mineral density. The asymmetry in density and size of the otoliths may cause disruptions of hearing and pressure sensitivity for individual fish with one vaterite otolith, however, the presence of vaterite otoliths did not seem to affect the growth of these laboratory reared juvenile herring. [source] Detection of Visible and Latent Fingerprints Using Micro-X-ray Fluorescence Elemental Imaging,JOURNAL OF FORENSIC SCIENCES, Issue 1 2006Christopher G. Worley Ph.D. ABSTRACT: Using micro-X-ray fluorescence (MXRF), a novel means of detecting fingerprints was examined in which the prints were imaged based on their elemental composition. MXRF is a nondestructive technique. Although this method requires a priori knowledge about the approximate location of a print, it offers a new and complementary means for detecting fingerprints that are also left pristine for further analysis (including potential DNA extraction) or archiving purposes. Sebaceous fingerprints and those made after perspiring were detected based on elements such as potassium and chlorine present in the print residue. Unique prints were also detected including those containing lotion, saliva, banana, or sunscreen. This proof-of-concept study demonstrates the potential for visualizing fingerprints by MXRF on surfaces that can be problematic using current methods. [source] Laser desorption/ionization techniques in the characterization of high-molecular-weight oil fractions,Part 2: de-asphalted oilsJOURNAL OF MASS SPECTROMETRY (INCORP BIOLOGICAL MASS SPECTROMETRY), Issue 7 2007Andrea Rizzi Abstract The composition of the de-asphalted oil fraction obtained from two different Italian fields was studied by laser desorption/ionization mass spectrometry. These fractions were treated with different solvent mixtures, and subfractions containing saturates, aromatic and polar compounds were obtained and analyzed by the same instrumental approach. The investigation showed clear differences between the samples coming from the two oils. The instrumental approach did not lead to an accurate description of the different components in terms of elemental composition and structures; however, valid information could be obtained on the molecular weight distribution of the components of the different fractions. Copyright © 2007 John Wiley & Sons, Ltd. [source] Electron ionization mass spectrometric study of monomeric models of O -polysaccharides of Vibrio cholerae O:1, serotypes Ogawa and InabaJOURNAL OF MASS SPECTROMETRY (INCORP BIOLOGICAL MASS SPECTROMETRY), Issue 9 2003Vladimír Ková Abstract Fragmentation mechanisms of electron ionization (EI) mass spectrometry of the title compounds have been elucidated by high-resolution (HR) mass spectrometric measurements of the elemental composition and measurements of the metastable transitions (B2/E, CID). The experimental results were interpreted with the help of Mass Frontier 3.0 software, which aided the elucidation of fragmentation mechanisms and helped to deduce structures of the ions formed. Characteristic under the conditions of EI-MS measurement was the production of protonated adducts. Three distinct pathways observed include the formation of oxonium type ions, the conjugated transfer of electrons in the pyranose ring, and cleavage of the acylamide side chains. By applying the results obtained, the molecular mass, as well as the structures of both the saccharide and acylamide side chain involved in related substances, can be determined. Copyright © 2003 John Wiley & Sons, Ltd. [source] Matrix-assisted laser desorption/ionization Fourier transform mass spectrometric analysis of oxygenated triglycerides and phosphatidylcholines in egg tempera paint dosimeters used for environmental monitoring of museum display conditionsJOURNAL OF MASS SPECTROMETRY (INCORP BIOLOGICAL MASS SPECTROMETRY), Issue 5 2001Oscar F. van den Brink Abstract Oxidative changes in triacylglycerols and diacylphosphatidylcholines in egg tempera paint strips are used for chemical dosimetry of the quality of the museum environment. High-resolution matrix-assisted laser desorption/ionization Fourier transform mass spectrometry (MALDI-FTMS) was used as a rapid method for the determination of the exact elemental composition of the alteration products from diacylphosphatidylcholines and triacylglycerols. Light exposure of the egg tempera paints yields oxygenated diacylphosphatidylcholines and triacylglycerols. In the latter multiple incorporation of oxygen was observed as a recurring mass difference of 15.995, the exact atomic mass of oxygen. Owing to the high resolution of the FTMS data (routinely 20 000 at m/z 1000 in broadband mode), oxidation products with different elemental compositions but identical nominal mass could be distinguished. Products of oxidative cleavage of triacylglycerols were observed in samples exposed for longer times. The relative intensities of the peaks of singly and multiply oxygenated triacylglycerols were used to derive the degree of oxygenation of the egg lipids in the tempera paint dosimeters. The degree of oxygenation was found to be directly related to the light exposure time. Exposure to elevated temperature (60 °C) for a period of 21 days did not lead to oxygenation of the triacylglycerols and diacylphosphatidylcholines. Exposure to NOx and SO2 in the dark greatly increased the degree of oxygenation. Addition of lead- or copper-containing pigments to the egg binding medium (and subsequent storage for 6 months in the dark) led to accelerated conversion of egg lipids to oxidised products. Copyright © 2001 John Wiley & Sons, Ltd. [source] PETROLEUM POTENTIAL, THERMAL MATURITY AND THE OIL WINDOW OF OIL SHALES AND COALS IN CENOZOIC RIFT BASINS, CENTRAL AND NORTHERN THAILANDJOURNAL OF PETROLEUM GEOLOGY, Issue 4 2006H. I. Petersen Oil shales and coals occur in Cenozoic rift basins in central and northern Thailand. Thermally immature outcrops of these rocks may constitute analogues for source rocks which have generated oil in several of these rift basins. A total of 56 oil shale and coal samples were collected from eight different basins and analysed in detail in this study. The samples were analysed for their content of total organic carbon (TOC) and elemental composition. Source rock quality was determined by Rock-Eval pyrolysis. Reflected light microscopy was used to analyse the organic matter (maceral) composition of the rocks, and the thermal maturity was determined by vitrinite reflectance (VR) measurements. In addition to the 56 samples, VR measurements were carried out in three wells from two oil-producing basins and VR gradients were constructed. Rock-Eval screening data from one of the wells is also presented. The oil shales were deposited in freshwater (to brackish) lakes with a high preservation potential (TOC contents up to 44.18 wt%). They contain abundant lamalginite and principally algal-derived fluorescing amorphous organic matter followed by liptodetrinite and telalginite (Botryococcus-type). Huminite may be present in subordinate amounts. The coals are completely dominated by huminite and were formed in freshwater mires. VR values from 0.38 to 0.47%Ro show that the exposed coals are thermally immature. VR values from the associated oil shales are suppressed by 0.11 to 0.28%Ro. The oil shales have H/C ratios >1.43, and Hydrogen Index (HI) values are generally >400 mg HC/g TOC and may reach 704 mg HC/ gTOC. In general, the coals have H/C ratios between about 0.80 and 0.90, and the HI values vary considerably from approximately 50 to 300 mg HC/gTOC. The HImax of the coals, which represent the true source rock potential, range from ,160 to 310 mg HC/g TOC indicating a potential for oil/gas and oil generation. The steep VR curves from the oil-producing basins reflect high geothermal gradients of ,62°C/km and ,92°C/km. The depth to the top oil window for the oil shales at a VR of ,0.70%Ro is determined to be between ,1100 m and 1800 m depending on the geothermal gradient. The kerogen composition of the oil shales and the high geothermal gradients result in narrow oil windows, possibly spanning only ,300 to 400 m in the warmest basins. The effective oil window of the coals is estimated to start from ,0.82 to 0.98%Ro and burial depths of ,1300 to 1400 m (,92°C/km) and ,2100 to 2300 m (,62°C/km) are necessary for efficient oil expulsion to occur. [source] GRAZING IMPACT OF, AND INDIRECT INTERACTIONS BETWEEN MESOGRAZERS ASSOCIATED WITH KELP (LAMINARIA DIGITATA),JOURNAL OF PHYCOLOGY, Issue 1 2010Markus Molis Little is known about the indirect effects of nonlethal grazing impacts in mesograzer,seaweed interactions. Using laboratory experiments, the effect of grazing by the seasonally abundant kelp-associated gastropod Lacuna vincta on subsequent kelp consumption by one kelp-associated (Idotea granulosa) and one nonassociated species of isopod (I. emarginata) was determined. Measurements of the toughness and elemental composition of different parts of the sporophyte of Laminaria digitata (Huds.) J. V. Lamour., as well as grazer-induced changes in the palatability of the blade, were conducted to explore possible mechanisms of indirect effects. In situ grazing pressure was the highest between July and September, with the blade being the preferred part of the kelp sporophyte, despite missing differences in the elemental composition among kelp parts. The laboratory experiments supported our hypotheses in that kelp consumption by both species of isopods was lower on intact than on L. vincta,damaged areas of the blade. This pattern was not caused by grazing-induced changes in blade palatability. Instead, the observed increase in isopod consumption following grazing by L. vincta resulted more likely from the combined effects of a reduction in the toughness of L. vincta,damaged kelp blades and some unknown gastropod cue(s). These results suggest that kelp-associated and nonassociated mesograzers may benefit from the nonlethal grazing impact of L. vincta due to changes in physical traits of the seaweed. Thus, the nonlethal grazing impact by one species of mesograzer can positively modify the trophic interactions between kelp and other potential competitors, suggesting that the interactions among mesograzers might be more complex than previously assumed. [source] Characterization of Azerbaijani and Croatian brown naphthalaneJOURNAL OF SEPARATION SCIENCE, JSS, Issue 13 2005Andja Alajbeg Abstract In spite of the fact that noncolored (nonaromatic) naphthalane containing high sterane content has been proved as bioactive and efficient in the treatment of psoriasis vulgaris, brown naphthalanes, which contain aromatics, are still in use. Thousands of patients, who have been passing through the therapy, deserve thorough and permanent study of brown naphthalanes. For that reason, two frequently used brown naphthalane preparations, one of the Azerbaijani (N1) and the other of the Croatian (N2) origin, were studied. The samples underwent the study by means of GC, OT LC, and normal-phase HPLC, as separation techniques. In addition, some bulk properties, elemental composition, and group composition by 1H NMR were determined. GC-MS served in compound types, especially in sterane detection. Both of the samples were found to be unresolved complex mixtures, relatively poor in n -alkanes. Isoalkanes, cycloalkanes, and aromatic compounds, in a great variety of isomers and homologs, made the majority of both of the samples. N1 was a dark, viscous, nontransparent fluid with a strong petroleum smell. Aromatics, which made 53% mass by OT LC and 54% mass by 1H NMR were found to be composed of mono-, di-, and tri+-aromatic compounds. Tri+-aromatic compounds were three to four times more abundant in N1 than in N2. Beside hydrocarbons, N1 comprised some organic compounds with polar functional groups. Also, some asphaltenes were found in it. N1 contained well-presented steranes, which are thought to be bioactive naphthalane ingredients. N2 was a pale brown liquid, with smell similar to gasoline. It contained somewhat lower percentage of aromatics (46% mass) and comparatively lower percentage of tri+ fused aromatics among which carcinogens might be expected. N2 was almost purely composed of hydrocarbons. It seemed to contain low content of steranes due to relatively low upper temperature of the distillation range applied in N2 preparation. [source] Corrosion behaviour of tool steels in tannic acidsMATERIALS AND CORROSION/WERKSTOFFE UND KORROSION, Issue 3 2009H. Winkelmann Abstract It is well known that cutting knifes in the wood industry often suffer from corrosion. Investigations showed that the corrosiveness of different wood types is responsible for a major part of the damage, and that different woods have a different corrosive impact. It is revealed that tannin, a water-soluble acid, which can be found in all woods in different concentrations, is the most aggressive acid contained in the wood, and so it is responsible for the main part of the corrosive attack. In view of the above, the ability of different cold-work steels to resist corrosion caused by tannic acid has been investigated. Often corrosion is measured by the mass loss of the sample divided by the surface of the sample under certain conditions during a fixed period of time. One problem with this method is that there is also a weight gain caused by oxidation or by other side reactions at the samples surface. So in some cases the weight of the sample even increases during the testing time, which makes the quantification of the corrosion impossible with this method. Due to the reasons already mentioned, another method was used to quantify the test results. This method is based on inductive coupled plasma,optical emission spectral analyses (ICP-OES), where the released Fe is quantified. The results of the corrosion resistant tests get correlated to the microstructure and the elemental composition of the analysed cold-work steels. The present investigations improve the understanding of important material parameters to enhance the corrosion resistance against tannin. It is revealed that the higher the primary carbide concentration is the more Cr or other passivating elements are necessary in the matrix to show a good protection against corrosion by tannin. Three materials with different elemental compositions have been investigated, and for one of those materials the influence of different heat treatments was also analysed. The investigations could show that annealing parameters and freeze-cycle processing (FCP) have less impact on the corrosion resistance to tannin than elemental composition and austenitising temperature. [source] Rapid structural determination of alkaloids in a crude extract of Stemona saxorum by high-performance liquid chromatography/electrospray ionization coupled with tandem mass spectrometryRAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 23 2009Shu-Ying Peng The electrospray ionization (ESI) mass spectrometric behavior of five Stemona alkaloids, stemokerrin, oxystemokerrin, oxystemokerrilactone, oxystemokerrin N -oxide and stemokerrin N -oxide, was studied using an ESI tandem mass technique (MSn). These compounds, isolated from Stemonasaxorum endemic in Vietnam, represent a class of alkaloids containing a pyrido[1,2-a]azepine A,B-ring core with a 1-hydroxypropyl side chain attached to C-4. Their fragmentation pathways were elucidated by ESI-MSn results and the elemental composition of the major product ions was confirmed by accurate mass measurement. In order to rationalize some fragmentation pathways, the relative Gibbs free energies of some product ions were estimated using the B3LYP/6-31+G(d) method. Based on the ESI-MSn results of five reference compounds, a reversed-phase high-performance liquid chromatography with tandem mass spectrometry (RP-HPLC/MSn) method was developed for the characterization of Stemona alkaloids with a pyrido[1,2-a]azepine A,B-ring core from the extract of S. saxorum. A total of 41 components were rapidly identified or tentatively characterized, of which 12 compounds were identified as Stemona alkaloids with a pyrido[1,2-a]azepine A,B-ring core, including four new compounds. This method is convenient and sensitive, especially for minor components in complex natural product extracts. Copyright © 2009 John Wiley & Sons, Ltd. [source] UPLC/MSE; a new approach for generating molecular fragment information for biomarker structure elucidationRAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 13 2006Robert S. Plumb A new approach to obtain fragmentation information in liquid chromatography/mass spectrometry (LC/MS) studies of small molecules in complex mixtures is presented using simultaneous acquisition of exact mass at high and low collision energy, MSE. LC/MS-TOF and LC/MS/MS-TOF are powerful tools for the analysis of complex mixtures, especially those for biological fluids allowing the elucidation of elemental composition and fragmentation information. In this example the composition of rat urine was studied using this new approach, allowing the structures of several endogenous components to be confirmed in one analytical run by the simultaneous acquisition of exact mass precursor and fragment ion data. The spectral data obtained using this new approach are comparable to those obtained by conventional LC/MS/MS as exemplified by the identification of endogenous metabolites present in rat urine. Copyright © 2006 John Wiley & Sons, Ltd. 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