Characterization of diesel particles: effects of fuel reformulation, exhaust aftertreatment, and engine operation on particle carbon composition and volatility

Diesel exhaust particles are the major constituent of urban carbonaceous aerosol being linked to a large range of adverse environmental and health effects. In this work, the effects of fuel reformulation, oxidation catalyst, engine type, and engine operation parameters on diesel particle emission characteristics were investigated. Particle emissions from an indirect injection (IDI) and a direct injection (DI) engine car operating under steady-state conditions with a reformulated low-sulfur, low-aromatic fuel and a standard-grade fuel were analyzed. Organic (OC) and elemental (EC) carbon fractions of the particles were quantified by a thermal-optical transmission analysis method and particle size distributions measured with a scanning mobility particle sizer (SMPS). The particle volatility characteristics were studied with a configuration that consisted of a thermal desorption unit and an SMPS. In addition, the volatility of size-selected particles was determined with a tandem differential mobility analyzer technique. The reformulated fuel was found to produce 10-40% less particulate carbon mass compared to the standard fuel. On the basis of the carbon analysis, the organic carbon contributed 27-61% to the carbon mass of the IDI engine particle emissions, depending on the fuel and engine operation parameters. The fuel reformulation reduced the particulate organic carbon emissions by 10-55%. In the particles of the DI engine, the organic carbon contributed 14-26% to the total carbon emissions, the advanced engine technology, and the oxidation catalyst, thus reducing the OC/EC ratio of particles considerably. A relatively good consistency between the particulate organic fraction quantified with the thermal optical method and the volatile fraction measured with the thermal desorption unit and SMPS was found.     

Polyfunctional bioceramics based on calcium phosphate and M-type hexagonal ferrite for medical applications

Magnetic biologically active ceramics based on calcium phosphate with a content of M-type hexagonal ferrite (HF) particles varying from 10 to 50 wt % has been synthesized and characterized. It has been found that the ceramics synthesized consists of a biocompatible carbonated hydroxyapatite (CHA) with the matrix containing M-type HF particles, leading to the magnetic characteristics of the ceramics synthesized being significantly higher than those of iron-oxide-modified bioglass ceramics used in medicine.     

Evaluating the potential of new technological tools for safety critical work

Defining user requirements of complex human–system interaction technologies and testing the fulfilment of these requirements in the end-product are issues of design practice that are currently not solved in an optimal way. In the current paper several dilemmas of “task-artefact-cycle”, “abstraction level of requirements” and the “tendency for conservative decisions” in requirement definition and testing are tackled. A new simulation method is proposed to tackle these design dilemmas in a case study on emergency response (ER) activity. Modelling and simulation are used as means to anticipate future activity, and the concept of “zone of proximal development” serves to illustrate the change in work demands of the ER activity. One of the key issues in ER is to create a realistic and timely understanding of the situation and to identify adequately the needs for action, the Common Operational Picture (COP). In the project, prototypes of new technological tools were designed to facilitate creation of an appropriate COP. First, normal emergency response activity was modelled. Then, the modelled situation and corresponding activity were enacted by competent actors as undisturbed as possible. Parallel to this, a second activity took place. This involved two professional fire fighters acting in the roles of incident commander and supporting officer. They observed the actual demands of the situation and the activities of the first responder actors. They also observed the available information provided by the new technologies. In the present paper the focus is on the presentation of the design and evaluation methodology. The demonstration of the methodology in a complex design task indicates the feasibility of the approach.     

Analysis and detection of mimicked speech based on prosodic features

This paper describes a work aimed towards understanding the art of mimicking by professional mimicry artists while imitating the speech characteristics of known persons, and also explores the possibility of detecting a given speech as genuine or impostor. This includes a systematic approach of collecting three categories of speech data, namely original speech of the mimicry artists, speech while mimicking chosen celebrities and original speech of the chosen celebrities, to analyze the variations in prosodic features. A?method is described for the automatic extraction of relevant prosodic features in order to model speaker characteristics. Speech is automatically segmented as intonation phrases using speech/nonspeech classification. Further segmentation is done using valleys in energy contour. Intonation, duration and energy features are extracted for each of these segments. Intonation curve is approximated using Legendre polynomials. Other useful prosodic features include average jitter, average shimmer, total duration, voiced duration and change in energy. These prosodic features extracted from original speech of celebrities and mimicry artists are used for creating speaker models. Support Vector Machine (SVM) is used for creating speaker models, and detection of a given speech as genuine or impostor is attempted using a speaker verification framework of SVM models.     

Remarkable improvement in tribological behavior of plasma sprayed carbon nanotube and graphene nanoplatelates hybrid reinforced alumina nanocomposite coating

Addition of 0.5?wt% of graphene nanoplatelates (GNPs) and 1?wt% carbonnanotube (CNTs) in plasma sprayed Al₂O₃ coating showed the reduction of 93.25% in wear volume loss and 90.94% in wear rate. This could be attributed to the simultaneous effect of enhanced densification, presence of the transferred layer from the counterpart, strong interface between Al₂O₃, GNP and CNTs and toughening offered by the GNPs and CNTs. The lowest COF value of 0.27 was recorded on addition of 0.5?wt% of GNP in Al₂O₃ coating, which could be attributed to the graphitic lubrication on the worn track during the wear.     

Splat morphology of plasma sprayed aluminum oxide reinforced with carbon nanotubes: A comparison between experiments and simulation

This study elucidates the effect of carbon nanotube (CNT) addition on the splat formation in plasma sprayed aluminum oxide (Al₂O₃) composite coating using experimental and computational methods. CNT content was varied as 0, 4 and 8 wt.% in Al₂O₃ matrix. With an increasing CNT content, splat morphology became more circular and disk-shaped. The average diameter of disk-shaped splats increased from 28.6 ± 1.4 μm for Al₂O₃ to 43.2 ± 1.3 μm for Al₂O₃–8 wt.% CNT. The population density of splats with fingers, fragments, and voids was the lowest for the highest (8 wt.%) CNT content. The addition of CNTs resulted in two simultaneously competing phenomena viz. increased thermal capacity and increased viscosity of the melt. Increased thermal capacity delayed the localized solidification resulting in higher splat diameter while agglomeration of CNTs at the periphery of the splat results in higher viscosity of the melt which suppresses the splat fragmentation that leads to increased population density of disk shaped splats. Splat morphology of three compositions was also simulated using SIMDROP software, which showed a good agreement with the experimentally collected splats.     

Nitrate, nitrite, and N-nitroso compounds in Finnish foods and the estimation of the dietary intakes

Summary An estimate of the dietary intakes of nitrite, nitrate andN-nitroso compounds is presented, based on the analytical data supplied by the Finnish Food Quality Control. Figures on the food consumption of the Finnish population, taken from a national dietary survey, and food consumption of 1768 children and adolescents over a 48-h recall period were used. The mean daily dietary nitrate intakes were estimated to be about 55 mg for the total population and for children and adolescents. The mean nitrite intakes were 1.88 mg for the total population and 1.07 mg for children and adolescents. The intake ofN-nitroso compounds (NDMA) was estimated to be 0.08 g for the total population and 0.02 g for children. Nitrates were found to originate mainly from vegetables (80%), nitrites from meat products (97%) and nitrosamines mostly from fish products and beer. A comparison of the estimate of dietary intake of nitrite with ADI values indicated that the nitrite intake of the total population was 23% and by children 39% of ADI. The average weight was approximately 60 kg for adults and 20 kg for children. When measured average weight (39 kg) was used, and the nitrite intake was found to be 28% of ADI. Nitrate intakes from food additives were 2.5% and 1.4% of the ADI value, respectively. When the total nitrate intake from various food sources was compared with the ADI (which is given only for food additives), the estimated nitrate intake of the total population was 25% and that of children 28% of the ADI value.

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Nitrat, Nitrit und N-nitroso-Verbindungen in der finnischen Nahrung

Zusammenfassung Die Einnahme von Nitrat, Nitrit undN-Nitroso-Verbindungen stützt sich auf die analytischen Werte der finnischen Lebensmittelkontrolle. Für die Schätzung der Nahrungsaufnahme der finnischen Bevölkerung benutzte man Resultate einer nationalen Nahrungsforschung und eines 48-Stunden-Befundes für 1768 Kinder und Jugendliche. Die durchschnittliche tägliche Einnahme von Nitrat schätzte man auf ungefähr 55 mg für die ganze Bevölkerung. Die durchschnittliche Einnahme von Nitrit betrug 1,88 mg für die ganze Bevölkerung und 1,07 mg für Kinder und Jugendliche. Die Einnahme vonN-Nitroso-Verbindungen (NDMA) schätzte man auf 0,08 g für die ganze Bevölkerung und 0,02 g für Kinder. Die hauptsächliche Nahrungsquelle der Nitrate war Gemüse (80%) und bei den Nitriten die Fleischwaren (97%). Nitrosamine stammten hauptsächlich aus Fischwaren und aus Bier. Als man die geschätzte Einnahme von Nitrit mit den ADI-Werten verglich, ergab sich, daß die Einnahme von Nitrit 23% (ganze Bevölkerung) und 39% (Kinder) des ADI-Wertes war. Als durchschnittliches Körpergewicht nahm man 60 kg für Erwachsene und 20 kg für Kinder an. Wenn man den Wert des gemessenen durchschnittlichen Körpergewichts (39 kg) für Kinder benutzte, war die Einnahme von Nitrit 28% des ADI-Wertes. Die Einnahme von Nitrat in Zusatzstoffen war 2,5% und entsprechend 1,4% des ADI-Wertes. Die Einnahme von Nitrat in der Nahrung schätzte man auf 25% (ganze Bevölkerung) und auf 28% (Kinder) des ADI-Wertes (gegeben nur für Nitrat als Zusatzstoffe).

     

In vitro blood and fibroblast responses to BisGMA–TEGDMA/bioactive glass composite implants

This in vitro study was designed to evaluate both blood and human gingival fibroblast responses to bisphenol A–glycidyl methacrylate–triethyleneglycol dimethacrylate (BisGMA–TEGDMA)/bioactive glass (BAG) composite, aimed to be used as composite implant abutment surface modifier. Three different types of substrates were investigated: (a) plain polymer (BisGMA 50 wt%–TEGDMA 50 wt%), (b) BAG–composite (50 wt% polymer + 50 wt% fraction of BAG–particles, <50 μm), and (c) plain BAG plates (100 wt% BAG). The blood response, including the blood–clotting ability and platelet adhesion morphology were evaluated. Human gingival fibroblasts were plated and cultured on the experimental substrates for up to 10 days, then the cell proliferation rate was assessed using AlamarBlue assay?. The BAG–composite and plain BAG substrates had a shorter clotting time than plain polymer substrates. Platelet activation and aggregation were most extensive, qualitatively, on BAG–composite. Analysis of the normalized cell proliferation rate on the different surfaces showed some variations throughout the experiment, however, by day 10 the BAG–composite substrate showed the highest (P < 0.001) cell proliferation rate. In conclusion, the presence of exposed BAG–particles enhances fibroblast and blood responses on composite surfaces in vitro.