Aircraft soot from conventional fuels and biofuels during ground idle and climb-out conditions: Electron microscopy and X-ray micro-spectroscopy.

Aircraft soot has a significant impact on global and local air pollution and is of particular concern for the population working at airports and living nearby. The morphology and chemistry of soot are related to its reactivity and depend mainly on engine operating conditions and fuel-type. We investigated the morphology (by transmission electron microscopy) and chemistry (by X-ray micro-spectroscopy) of soot from the exhaust of a CFM 56-7B26 turbofan engine, currently the most common engine in aviation fleet, operated in the test cell of SR Technics, Zurich airport. Standard kerosene (Jet A-1) and a biofuel blend (Jet A-1 with 32% HEFA) were used at ground idle and climb-out engine thrust, as these conditions highly influence air quality at airport areas. The results indicate that soot reactivity decreases from ground idle to climb-out conditions for both fuel types. Nearly one third of the primary soot particles generated by the blended fuel at climb-out engine thrust bear an outer amorphous shell implying higher reactivity. This characteristic referring to soot reactivity needs to be taken into account when evaluating the advantage of HEFA blending at high engine thrust. The soot type that is most prone to react with its surrounding is generated by Jet A-1 fuel at ground idle. Biofuel blending slightly lowers soot reactivity at ground idle but does the opposite at climb-out conditions. As far as soot reactivity is concerned, biofuels can prove beneficial for airports where ground idle is a common situation; the benefit of biofuels for climb-out conditions is uncertain.

The Combination of APRI and ALBI Facilitates Preoperative Risk Stratification for Patients Undergoing Liver Surgery After Neoadjuvant Chemotherapy.

BACKGROUND: Neoadjuvant chemotherapy (NeoCTx) is performed for most patients with colorectal cancer liver metastases (CRCLM). However, chemotherapy-associated liver injury (CALI) has been associated with poor postoperative outcome. To date, however, no clinically applicable and noninvasive tool exists to assess CALI before liver resection. METHODS: Routine blood parameters were assessed in 339 patients before and after completion of NeoCTx and before surgery. The study assessed the prognostic potential of the aspartate aminotransferase (AST)-to-platelet ratio index (APRI), the albumin-bilirubin grade (ALBI), and their combinations. Furthermore, an independent multi-center validation cohort (n = 161) was included to confirm the findings concerning the prediction of postoperative outcome. RESULTS: Higher ALBI, APRI, and APRI + ALBI were found in patients with postoperative morbidity (P = 0.001, P = 0.064, P = 0.001, respectively), liver dysfunction (LD) (P = 0.009, P = 0.012, P < 0.001), or mortality (P = 0.037, P = 0.045, P = 0.016), and APRI + ALBI had the highest predictive potential for LD (area under the curve [AUC], 0.695). An increase in APRI + ALBI was observed during NeoCTx (P < 0.001). Patients with longer periods between NeoCTx and surgery showed a greater decrease in APRI + ALBI (P = 0.006) and a trend for decreased CALI at surgery. A cutoff for APRI + ALBI at - 2.46 before surgery was found to identify patients with CALI (P = 0.002) and patients at risk for a prolonged hospital stay (P = 0.001), intensive care (P < 0.001), morbidity (P < 0.001), LD (P < 0.001), and mortality (P = 0.021). Importantly, the study was able to confirm the predictive potential of APRI + ALBI for postoperative LD and mortality in a multicenter validation cohort. CONCLUSION: Determination of APRI + ALBI before surgery enables identification of high-risk patients for liver resection. The combined score seems to dynamically reflect CALI. Thus, APRI + ALBI could be a clinically relevant tool for optimizing timing of surgery in CRCLM patients after NeoCTx.

Sexual isolation promotes divergence between parapatric lake and stream stickleback.

Speciation can be initiated by adaptive divergence between populations in ecologically different habitats, but how sexually based reproductive barriers contribute to this process is less well understood. We here test for sexual isolation between ecotypes of threespine stickleback fish residing in adjacent lake and stream habitats in the Lake Constance basin, Central Europe. Mating trials exposing females to pairings of territorial lake and stream males in outdoor mesocosms allowing for natural reproductive behaviour reveal that mating occurs preferentially between partners of the same ecotype. Compared to random mating, this sexual barrier reduces gene flow between the ecotypes by some 36%. This relatively modest strength of sexual isolation is surprising because comparing the males between the two ecotypes shows striking differentiation in traits generally considered relevant to reproductive behaviour (body size, breeding coloration, nest size). Analysing size differences among the individuals in the mating trials further indicates that assortative mating is not related to ecotype differences in body size. Overall, we demonstrate that sexually based reproductive isolation promotes divergence in lake-stream stickleback along with other known reproductive barriers, but we also caution against inferring strong sexual isolation from the observation of strong population divergence in sexually relevant traits.

Coupling a Knudsen reactor with the short lived radioactive tracer (13)N for atmospheric chemistry studies.

A Knudsen cell flow reactor was coupled to an online gas phase source of the short-lived radioactive tracer (13)N to study the adsorption of nitrogen oxides on ice at temperatures relevant for the upper troposphere. This novel approach has several benefits over the conventional coupling of a Knudsen cell with a mass spectrometer. Experiments at lower partial pressures close to atmospheric conditions are possible. The uptake to the substrate is a direct observable of the experiment. Operation of the experiment in continuous or pulse mode allows to retrieve steady state uptake kinetics and more details of adsorption and desorption kinetics.

Standard states and thermochemical kinetics in heterogeneous atmospheric chemistry.

The significance of the (often implicit) choice of standard state in the analysis and interpretation of heterogeneous chemical processes is not well acknowledged. This paper attempts to illuminate how the specific choice of standard state influences the numerical values of the parameters obtained from such analysis. Examples are drawn from air-solution and air-surface equilibria.

Acetone adsorption on ice investigated by X-ray spectroscopy and density functional theory.

Using a combination of X-ray photoemission and near-edge X-ray absorption spectroscopy (NEXAFS) as well as density-functional theory (DFT), we have investigated the adsorption of acetone on ice in the temperature range from 218 to 245 K. The adsorption enthalpy determined from experiment (45 kJ mol(-1)) agrees well with the adsorption energy predicted by theory (41 to 44 kJ mol(-1)). Oxygen K-edge NEXAFS spectra indicate that the presence of acetone at the ice surface does not induce the formation of a pre-melted layer at temperatures up to 243 K. DFT calculations show that the energetically most favored adsorption geometry for acetone on ice is with the molecular plane almost parallel to the surface.

An in situ cell to study phase transitions in individual aerosol particles on a substrate using scanning transmission x-ray microspectroscopy.

A new in situ cell to study phase transitions and chemical processes on individual aerosol particles in the x-ray transmission microscope at the PolLux beamline of the Swiss light source has been built. The cell is machined from stainless steel and aluminum components and is designed to be used in the standard mount of the microscope without need of complicated rearrangements of the microscope. The cell consists of two parts, a back part which contains connections for the gas supply, heating, cooling devices, and temperature measurement. The second part is a removable clip, which hosts the sample. This clip can be easily exchanged and brought into a sampling unit for aerosol particles. Currently, the cell can be operated at temperatures ranging from -40 to +50 °C. The function of the cell is demonstrated using two systems of submicron size: inorganic sodium bromide aerosols and soot originating from a diesel passenger car. For the sodium bromide we demonstrate how phase transitions can be studied in these systems and that O1s spectra from aqueous sodium bromide solution can be taken from submicron sized particles. For the case of soot, we demonstrate that the uptake of water onto individual soot particles can be studied.

First-principles constraints on diffusion in lower-mantle minerals and a weak D'' layer.

Post-perovskite MgSiO(3) is believed to be present in the D'' region of the Earth's lowermost mantle. Its existence has been used to explain a number of seismic observations, such as the D'' reflector and the high degree of seismic anisotropy within the D'' layer. Ionic diffusion in post-perovskite controls its viscosity, which in turn controls the thermal and chemical coupling between the core and the mantle, the development of plumes and the stability of deep chemical reservoirs. Here we report the use of first-principles methods to calculate absolute diffusion rates in post-perovskite under the conditions found in the Earth's lower mantle. We find that the diffusion of Mg(2+) and Si(4+) in post-perovskite is extremely anisotropic, with almost eight orders of magnitude difference between the fast and slow directions. If post-perovskite in the D'' layer shows significant lattice-preferred orientation, the fast diffusion direction will render post-perovskite up to four orders of magnitude weaker than perovskite. The presence of weak post-perovskite strongly increases the heat flux across the core-mantle boundary and alters the geotherm. It also provides an explanation for laterally varying viscosity in the lowermost mantle, as required by long-period geoid models. Moreover, the behaviour of very weak post-perovskite can reconcile seismic observation of a D'' reflector with recent experiments showing that the width of the perovskite-to-post-perovskite transition is too wide to cause sharp reflectors. We suggest that the observed sharp D'' reflector is caused by a rapid change in seismic anisotropy. Once sufficient perovskite has transformed into post-perovskite, post-perovskite becomes interconnected and strain is partitioned into this weaker phase. At this point, the weaker post-perovskite will start to deform rapidly, thereby developing a strong crystallographic texture. We show that the expected seismic contrast between the deformed perovskite-plus-post-perovskite assemblage and the overlying isotropic perovskite-plus-post-perovskite assemblage is consistent with seismic observations.

Validation of 131I ecological transfer models and thyroid dose assessments using Chernobyl fallout data from the Plavsk district, Russia.

Within the project "Environmental Modelling for Radiation Safety" (EMRAS) organized by the IAEA in 2003 experimental data of (131)I measurements following the Chernobyl accident in the Plavsk district of Tula region, Russia were used to validate the calculations of some radioecological transfer models. Nine models participated in the inter-comparison. Levels of (137)Cs soil contamination in all the settlements and (131)I/(137)Cs isotopic ratios in the depositions in some locations were used as the main input information. 370 measurements of (131)I content in thyroid of townspeople and villagers, and 90 measurements of (131)I concentration in milk were used for validation of the model predictions. A remarkable improvement in models performance comparing with previous inter-comparison exercise was demonstrated. Predictions of the various models were within a factor of three relative to the observations, discrepancies between the estimates of average doses to thyroid produced by most participant not exceeded a factor of ten.

Kinetics of the heterogeneous reaction of nitric acid with mineral dust particles: an aerosol flowtube study.

The heterogeneous reaction of HNO3 with mineral dust aerosol (Arizona Test Dust) was studied in an aerosol flow tube at atmospherically relevant conditions (298 K, approximately 1 atm, 6-60% RH) and using radioactively labelled HNO3. The uptake of nitric acid was found to depend on HNO3 and H2O concentrations in the gas phase. A reaction mechanism is suggested to describe the heterogeneous interaction, involving Langmuir type adsorption and surface reaction. This mechanism is incorporated in a flux based aerosol kinetic model framework that is able to reproduce the observations within the range of experimental conditions. The experiments show that the reactive surface sites of the relatively calcium poor, but silicate rich dust surface are efficiently depleted at higher HNO3 concentrations in the gas phase or longer exposure times. A set of kinetic parameters is extracted from the data, which can be used to calculate uptake coefficients as function of time, concentration and humidity for use in atmospheric chemistry models to improve especially the representation of the effects of relative humidity on dust aging and to allow following dust aging with time.

Validation of environmental transfer models and assessment of the effectiveness of countermeasures using data on (131)I releases from Chernobyl.

The studies undertaken by the (131)I Working Group, part of the International Atomic Energy Agency's EMRAS (Environmental Modelling for Radiation Safety) programme, were focused primarily on evaluating the predictive capability of environmental models. Particular emphasis was placed on applying models to evaluate the effectiveness of countermeasures.

[Fine-needle aspiration cytology. Aspects of a minimally invasive diagnostic procedure]. / Die Feinnadelpunktion. Aspekte einer minimal-invasiven Diagnosemethode.

All practicable applications of fine-needle aspiration cytology (FNAC) for palpable tumors or non-palpable lesions guided with endoscopic and imaging procedures are presented. Multidisciplinary procedures and the technical and biological aspects of FNAC are presented. Indications and diagnostic challenges of FNAC on selected organs and neoplasms are discussed based on personal experience and the literature. Skilled and well-trained cytopathologists, the quality of the aspirate and the cytological preparation as well as supplementary immunocytochemical and molecular genetic analyses are mandatory for reliable diagnostic results. The indications and advantages of liquid-based techniques are discussed.

Bromine enrichment in the near-surface region of Br-doped NaCl single crystals diagnosed by Rutherford backscattering spectrometry.

Bromine released from sea-salt aerosols and seawater ice is known for its high chemical reactivity. Previous studies have suggested that its availability to the gas-phase could be enhanced by segregation processes increasing Br concentration on the aerosol surface as compared to the bulk. However, little is known about the composition within the near-surface region, that is, the outermost approximately 100 monolayers. We used Rutherford backscattering spectrometry (RBS) to measure Br concentration profiles to a depth of about 750 nm of Br-doped NaCl single crystals to characterize the thermodynamics and kinetics of Br segregation to the near-surface region in moist air. These experiments were carried out on cleavage planes of melt-grown and of annealed solution-grown crystals at room temperature and relative humidities (RH) too low for formation of a stable liquid phase. Segregation of Br was below the detection limit on melt-grown crystals with Br/Cl = 0.01. In the case of annealed solution-grown crystals with Br/Cl = 0.002, average segregations of (0.24 +/- 0.11) x 10(15) and (0.42 +/- 0.12) x 10(15) Br atoms cm-2 were observed at 50% and 65% RH, respectively. No segregation was found at 20% RH. The observed Br segregation can be explained by the formation of an adsorbed liquid layer (depending on crystal surface properties and relative humidity) and preferential, diffusion-limited dissolution of Br into this layer according to the partition coefficient of Br between aqueous and solid NaCl. The thickness of the adsorbed liquid layer, which depends on crystal surface geometry and on relative humidity, can be estimated to range from 4 to at most 59 nm on the basis of measured Br concentrations and partition coefficients. Applying this concept of partitioning to natural sea salt suggests a Br/Cl molar ratio of up to 0.2 in adsorbed surface water of crystallized natural aerosol particles compared to about 0.0015 in seawater. This would have a major impact on heterogeneous reactions on sea-salt particles under dry conditions such as in the freeze-dried Arctic boundary layer.

Finnish workshop on the restoration of contaminated residential areas after a nuclear accident: strategy generation and impact assessment.

Scenario-focused workshops on the restoration of contaminated residential areas are planned in a number of European countries within the EVATECH project of the EU's Fifth Framework Programme. The intention is to identify factors driving decision-making, explore the kinds of strategies that might be appropriate, develop methods for stakeholder involvement, and reveal information needs. The scenario of the Finnish workshop is presented. A policy generation scheme is proposed that yields a manageable but feature-rich set of strategies that is not constraint by lack of feasibility, justification, or public acceptability. The scheme rests on the premise that the affected area is divided into zones according to the level of contamination and that clean-up actions are applied in any combination and in combination with relocation.

Photoenhanced uptake of gaseous NO2 on solid organic compounds: a photochemical source of HONO?

In several recent field campaigns the existence of a strong daytime source of nitrous acid was demonstrated. The mechanism of this source remains unclear. Accordingly, in the present laboratory study, the effect of light (in the range 300-500 nm) on the uptake kinetics of NO2 on various surfaces taken as proxies for organic surfaces encountered in the troposphere (as organic aerosol but also ground surfaces) was investigated. In this collaborative study, the uptake kinetics and product formation rate were measured by different flow tube reactors in combination with a sensitive HONO instrument. Uptake on light absorbing aromatic compounds was significantly enhanced when irradiated with light of 300-420 nm, and HONO was formed with high yield when the gas was humidified. Especially organic substrates containing a combination of electron donors, such as phenols, and of compounds yielding excited triplet states, such as aromatic ketones, showed a high reactivity towards NO2. Based on the results reported a mechanism is suggested, in which photosensitised electron transfer is occurring. The results show that HONO can be efficiently formed during the day in the atmosphere at much longer wavelengths compared to the recently proposed nitrate photolysis.

Heterogeneous reaction of NO2 on diesel soot particles.

Soot particles were collected from a diesel engine using a procedure that realistically mimics exhaust gas conditions in tailpipes and during dilution at room temperature. After being sampled, the particles were exposed to NO2 concentrations and relative humidity in ranges relevant for the troposphere using 13N as tracer. Gas-phase nitrous acid(HONO) and irreversibly bound (i.e., chemisorbed) species were the main reaction products with initial yields of 80-90% and about 10%, respectively. Neither NO nor HNO3 were detectable. The HONO formation increased with increasing engine load (i.e., with a decreasing air to fuel ratio, lambda). The reaction rates of HONO and chemisorbed NO2 increased with increasing NO2 concentration and did not depend on relative humidity. At the beginning of reaction, the uptake coefficient averaged over 3 min ranged from 5 x 10(-6) to 10(-5) for NO2 concentrations between 2 and 40 ppb. The HONO formation rates decreased with time, indicating consumption of reactive surface species, while the chemisorption rates remained almost constant. The total HONO formation potential of the particles was estimated to about 1.3 x 10(17) molecules/mg of diesel soot or to about 4.7 mg/kg of diesel fuel, indicating that the reaction between NO2 and diesel soot particles does not provide a significant secondary HONO source in the atmosphere. A Langmuir-Hinshelwood type reaction mechanism was proposed that adequately describes the observed results and also allows discussing important general features of reactions on soot.

[Advanced breast biopsy instrumentation (ABBI). Histopathologic evaluation of a new investigation method]. / Advanced breast biopsy instrumentation (ABBI). Histopathologische Evaluierung einer neuen Untersuchungsmethode.

The ABBI (advanced breast biopsy instrumentation) system has only recently been available for diagnostic excisional biopsy of small, non-palpable lesions of the breast. Between 1.1.1998 and 31.3.1999 this method was utilized in 40 patients with suspicious microcalcifications (n = 25), newly developed densities (n = 11) and a combination of microcalcifications and densities (n = 4). In 12 cases malignancy was diagnosed, in 11 cases a subsequent resection was performed. In every case sufficient tissue for diagnosis was obtained, in not a single case the diagnosis had to be revised in case of subsequent resection. Orientation within the specimen is accurate, the resection margins can be judged unequivocally. Any necessary special examinations can be performed on the resected tissue. In our experience, ABBI is a valuable and elegant tool for diagnosing small suspicious lesions of the breast.

Estimating the uptake of traffic-derived NO2 from 15N abundance in Norway spruce needles.

The 15N ratio of nitrogen oxides (NOx) emitted from vehicles, measured in the air adjacent to a highway in the Swiss Middle Land, was very high [δ15N(NO2) = +5.7‰]. This high 15N abundance was used to estimate long-term NO2 dry deposition into a forest ecosystem by measuring δ15N in the needles and the soil of potted and autochthonous spruce trees [Picea abies (L.) Karst] exposed to NO2 in a transect orthogonal to the highway. δ15N in the current-year needles of potted trees was 2.0‰ higher than that of the control after 4 months of exposure close to the highway, suggesting a 25% contribution to the N-nutrition of these needles. Needle fall into the pots was prevented by grids placed above the soil, while the continuous decomposition of needle litter below the autochthonous trees over previous years has increased δ15N values in the soil, resulting in parallel gradients of δ15N in soil and needles with distance from the highway. Estimates of NO2 uptake into needles obtained from the δ15N data were significantly correlated with the inputs calculated with a shoot gas exchange model based on a parameterisation widely used in deposition modelling. Therefore, we provide an indication of estimated N inputs to forest ecosystems via dry deposition of NO2 at the receptor level under field conditions.

[Diagnosis of malignant uterine tumors by transvaginal ultrasound]. / Diagnostik maligner Uterustumoren durch die transvaginale Sonographie.

Two hundred and three non-pregnant women who underwent diagnostic dilatation and curettage or hysterectomy were included in a prospective study designed to assess the accuracy of transvaginal sonography in conforming or excluding the presence of uterine cancer. All preoperative sonographic findings were compared with the final histological diagnosis. The predictive value of sonographic evidence of malignancy was 71.1% (32/45), the predictive value of benign disease was 95.6% (151/158). Sensitivity was 82.1% (32/39) and specificity 92.1% (151/164). Although sensitivity and specificity increased as compared to an earlier study using transabdominal ultrasound, we recommend dilatation and curettage in women with postmenopausal bleeding.

Doppler sonography of varicocele: long-term follow-up after venography and transcatheter sclerotherapy.

Sixty-eight patients with unilateral left-sided idiopathic varicocele who had not been treated previously were examined with Doppler sonography before and 1, 3, and 12 months after selective venography with balloon occlusion and transcatheter sclerotherapy of the internal spermatic vein. Varicocele and its persistence or recurrence was diagnosed by reflux only. Reflux was differentiated into stop-type and shunt-type by Doppler sonography. The resolution of varicocele was defined by absence of any reflux. The rate of resolution was greatest 3 months after sclerotherapy (49 patients, 72%). The diagnosis of persisting or recurring varicocele at this time does not seem to be justified, however, as in our study both further improvement and deterioration were observed up to 12 months after treatment. Twenty patients (29%) had a persisting or recurring varicocele 12 months after sclerotherapy. Reflux is the parameter of significance for diagnosing varicocele and its persistence or recurrence after therapy. Improvement of clinical aspects of varicocele (e.g., sperm count, sperm motility, and conception rates) depends on therapy of even subclinical varicoceles. Therefore, diagnosis and retreatment of persistent or recurrent varicoceles seems essential. The high sensitivity of Doppler sonography permits adequate assessment of the therapeutic result and evaluation of real rates of persistent or recurrent varicoceles after venography with balloon occlusion and transcatheter sclerotherapy.