Versatile microanalytical system with porous polypropylene capillary membrane for calibration gas generation and trace gaseous pollutants sampling applied to the analysis of formaldehyde, formic acid, acetic acid and ammonia in outdoor air

The analytical determination of atmospheric pollutants still presents challenges due to the low-level concentrations (frequently in the mu g m(-3) range) and their variations with sampling site and time In this work a capillary membrane diffusion scrubber (CMDS) was scaled down to match with capillary electrophoresis (CE) a quick separation technique that requires nothing more than some nanoliters of sample and when combined with capacitively coupled contactless conductometric detection (C(4)D) is particularly favorable for ionic species that do not absorb in the UV-vis region like the target analytes formaldehyde formic acid acetic acid and ammonium The CMDS was coaxially assembled inside a PTFE tube and fed with acceptor phase (deionized water for species with a high Henry s constant such as formaldehyde and carboxylic acids or acidic solution for ammonia sampling with equilibrium displacement to the non-volatile ammonium ion) at a low flow rate (8 3 nLs(-1)) while the sample was aspirated through the annular gap of the concentric tubes at 25 mLs(-1) A second unit in all similar to the CMDS was operated as a capillary membrane diffusion emitter (CMDE) generating a gas flow with know concentrations of ammonia for the evaluation of the CMDS The fluids of the system were driven with inexpensive aquarium air pumps and the collected samples were stored in vials cooled by a Peltier element Complete protocols were developed for the analysis in air of NH(3) CH(3)COOH HCOOH and with a derivatization setup CH(2)O by associating the CMDS collection with the determination by CE-C(4)D The ammonia concentrations obtained by electrophoresis were checked against the reference spectrophotometric method based on Berthelot s reaction Sensitivity enhancements of this reference method were achieved by using a modified Berthelot reaction solenoid micro-pumps for liquid propulsion and a long optical path cell based on a liquid core waveguide (LCW) All techniques and methods of this work are in line with the green analytical chemistry trends (C) 2010 Elsevier B V All rights reserved

Bioluminescent sensor for naphthalene in air: Cell immobilization and evaluation with a dynamic standard atmosphere generator

A dynamic atmosphere generator with a naphthalene emission source has been constructed and used for the development and evaluation of a bioluminescence sensor based on the bacteria Pseudomonas fluorescens HK44 immobilized in 2% agar gel (101 cell mL(-1)) placed in sampling tubes. A steady naphthalene emission rate (around 7.3 nmol min(-1) at 27 degrees C and 7.4 mLmin(-1) of purified air) was obtained by covering the diffusion unit containing solid naphthalene with a PTFE filter membrane. The time elapsed from gelation of the agar matrix to analyte exposure (""maturation time"") was found relevant for the bioluminescence assays, being most favorable between 1.5 and 3 h. The maximum light emission, observed after 80 min, is dependent on the analyte concentration and the exposure time (evaluated between 5 and 20 min), but not on the flow rate of naphthalene in the sampling tube, over the range of 1.8-7.4 nmol min(-1). A good linear response was obtained between 50 and 260 nmol L-1 with a limit of detection estimated in 20 nmol L-1 far below the recommended threshold limit value for naphthalene in air. (c) 2008 Elsevier B.V. All rights reserved.

Quantification of sex pheromone from Anocentor nitens by gas chromatography-mass spectrometry-selected ion monitoring

Two highly sensitive and selective methods based on gas chromatography coupled to mass spectrometry (GC-MS) in the selected ion monitoring (SIM) mode have been developed for the quantification of 2,6-dichlorophenol (2,6-DCP), a sex pheromone of the tick females of Anocentor nitens. Standard addition method and calibration curve techniques using 5-bromine-4-hydroxy-3- methoxybenzaldehyde (5-BrV) as internal standard (IS) afforded detection limit of 0.1ngml-1. The calibration curve was linear over the concentration range from 0.5 to 500ngml-1 for 2,6-DCP. Results show that the concentration range of sex pheromone in the extracts samples was 1.08-10.35ngml-1. The methods developed provided reliable procedures to determine amounts of 2,6-DCP present in ticks. © 2003 Elsevier B.V. All rights reserved.

Sensitivity and fragmentation calibration of the ROSINA double focusing mass spectrometer

The goal of this work has been to calibrate sensitivities and fragmentation pattern of various molecules as well as further characterize the lab model of the ROSINA Double Focusing Mass Spectrometer (DFMS) on board ESA’s Rosetta spacecraft bound to comet 67P/Churyumov-Gerasimenko. The detailed calibration and characterization of the instrument is key to understand and interpret the results in the coma of the comet. A static calibration was performed for the following species: Ne, Ar, Kr, Xe, H2O, N2, CO2, CH4, C2H6, C3H8, C4H10, and C2H4. The purpose of the calibration was to obtain sensitivities for all detectors and emissions, the fragmentation behavior of the ion source and to show the capabilities to measure isotopic ratios at the comet. The calibration included the recording of different correction factors to evaluate the data, including a detailed investigation of the detector gain. The quality of the calibration that could be tested for different gas mixtures including the calibration of the density inside the ion source when calibration gas from the gas calibration unit is introduced. In conclusion the calibration shows that DFMS meets the design requirements and that DFMS will be able to measure the D/H at the comet and help shed more light on the puzzle about the origin of water on Earth.

A simple and inexprensive method to generate a microaerophilic atmosphere for the isolation of Campylobacter sp

Faeces of 138 chickens were inoculated on Blaser agar plates. One set of plates was incubated in jars with CampyPak envelopes. The others were incubated in "Zip-lock" plastic bags (7 x X in.) and a microaerophilic atmosphere was generated exhaling into the "Zip-lock" plastic bag, after holding the breath for 20 sec. Then, the bag was pressed to evacuate its atmosphere, inflated again, and pressed (4 times), and finally sealed. Campylobacter was isolated from 127 (96.2%) of samples incubated in jars with gas generator envelopes and from 129 (98%) of the specimens incubated into the bags. The proposed methodology offers good savings for cost-conscious laboratories.

Quality assessment of eggs packed under modified atmosphere

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Massenspektrometrische Wasserdampfmessung in der oberen Troposphäre und unteren Stratosphäre

Diese Arbeit beschreibt die Entwicklung des flugzeuggetragenen Atmosphärischen Ionisations-Massenspektrometers AIMS-H2O zur Messung von Wasserdampf in der oberen Troposphäre und unteren Stratosphäre (UTLS) und erste Flugzeugmessungen mit dem Instrument. Wasserdampf beeinflusst das Klima in der UTLS aufgrund seiner Strahlungseigenschaften und agiert als wichtiger Parameter bei der Bildung von Zirruswolken und Kondensstreifen. Deshalb sind genaue Wasserdampfmessungen für das Verständnis vieler atmosphärischer Prozesse unerlässlich. Instrumentenvergleiche wie sie im SPARC Report No. 2 und dem Bericht der AUQAVIT Kampagne zusammengefasst sind, haben gezeigt, dass große Abweichungen zwischen einzelnen Methoden und Instrumenten bestehen. Diese Unsicherheiten limitieren das Verständnis des Einflusses von Wasserdampf auf die Dynamik und die Strahlungseigenschaften in der UTLS. Die in dieser Arbeit vorgestellte Entwicklung einer neuen Messmethode für Wasserdampf mit dem Massenspektrometer AIMS-H2O ist deshalb auf die genaue Messung niedriger Wasserdampfkonzentrationen in der UTLS fokussiert. Mit AIMS H2O wird Umgebungsluft in einer neu entwickelten Gasentladungsquelle ionisiert. Durch eine Reihe von Ionen-Molekül-Reaktionen entstehen H3O+(H2O) und H3O+(H2O)2 Ionen. Diese Ionen werden genutzt, um die Wasserdampfkonzentration in der Atmosphäre zu bestimmen. Um die erforderliche hohe Genauigkeit zu erzielen, wird AIMS H2O im Flug kalibriert. In dem zu diesem Zweck aufgebauten Kalibrationsmodul wird die katalytische Reaktion von Wasserstoff und Sauerstoff auf einer Platinoberfläche genutzt, um definierte Wasserdampfkonzentrationen für die Kalibration im Flug zu erzeugen. Bei ersten Messungen auf der Falcon während der Kampagne CONCERT 2011 konnte dabei eine Genauigkeit von 8 bis 15% für die Messung der Wasserdampfkonzentration in einem Messbereich von 0,5 bis 250 ppmv erreicht werden. Die Messfrequenz betrug 4 Hz, was einer räumlichen Auflösung von etwa 50 m entspricht. Der Vergleich der Messung des Massenspektrometers mit dem Laserhygrometer Waran zeigt eine sehr gute Übereinstimmung im Rahmen der Unsicherheiten. Anhand zweier Fallstudien werden die Messungen von AIMS H2O während CONCERT 2011 detailliert analysiert. In der ersten Studie werden zwei Flüge in eine stratosphärische Intrusion über Nordeuropa untersucht. In dieser Situation wurde stratosphärische Luft bis hinunter auf 6 km Höhe transportiert und war dadurch mit der Falcon erreichbar. Es konnte gezeigt werden, dass AIMS-H2O sehr gut für die genaue Messung niedriger Wasserdampfkonzentrationen, in diesem Fall bis etwa 3,5 ppmv, geeignet ist. Der Vergleich der Messung mit Analysen des ECMWF Integrated Forecast Systems zeigt eine gute Übereinstimmung der gemessenen Wasserdampfstrukturen mit der dynamischen Tropopause. Unterschiede tauchen dagegen beim Vergleich der Wasserdampfkonzentrationen in der unteren Stratosphäre auf. Hier prognostiziert das Modell deutlich höhere Feuchten. Die zweite Fallstudie beschäftigt sich mit der Verteilung der relativen Feuchte in jungen Kondensstreifen im Vergleich zu ihrer direkten Umgebung. Dabei wurde für drei Messsequenzen im Abgasstrahl von Flugzeugen beobachtet, dass die relative Feuchte innerhalb des Kondensstreifens im Vergleich zur Umgebung sowohl bei unter- als auch übersättigten Umgebungsbedingungen in Richtung Sättigung verschoben ist. Die hohe Anzahl an Eispartikeln und die damit verbundene große Eisoberfläche in jungen Kondensstreifen führt also zu einer schnellen Relaxation von Gasphase und Eis in Richtung Gleichgewicht. In der Zukunft soll AIMS-H2O auch auf HALO für die genaue Messung von Wasserdampf bei ML-CIRRUS und weiteren Kampagnen eingesetzt werden.

Definizione e analisi delle mappe di prestazione di un turboalbero aeronautico

Nel presente lavoro di tesi, in seguito ad acquisizioni di dati effettuate nella sala prove del "Laboratorio di Macchine e Propulsione" della Scuola di Ingegneria e Architettura di Forlì sul turboshaft Allison 250 C18, in una prima fase sono state ricavate le mappe prestazionali dei singoli componenti del motore, elaborando i dati sperimentali in ambiente MatLab. Le acquisizioni sono state effettuate mediante l'utilizzo di sensori di pressione, temperatura e velocità installati in precedenza sul motore e opportunamente calibrati. In seguito alla realizzazione delle mappe prestazionali, si è passati all'allestimento completo di un modello dinamico in ambiente Simulink, del motore Allison 250 C18. Tale modello riproduce, in opportuni blocchi, ciascun componente facente parte della motorizzazione. Ogni blocco riceve in ingresso le caratteristiche fisiche di interesse del flusso (temperatura, pressione, calore specifico a pressione costante e gamma) provenienti dal blocco precedente tramite un "filo", le rielabora al suo interno risolvendo le equazioni tipiche di ciascun componente e interpolando le mappe di prestazione ricavate precedentemente in MatLab, e le invia come input al blocco successivo o in retroazione ai blocchi precedenti. In ogni blocco è stato realizzato un sistema di dinamica di pressione che, ad ogni istante, risolve un'equazione differenziale dipendente dalla differenza di portata a monte e a valle di un componente e dal volume di controllo, che restituisce il valore di pressione in uscita proporzionale alla variazione di portata stessa. Nel presente lavoro di tesi si è cercato di stabilizzare questo complesso sistema in una condizione di progetto, fissata a 30000 rpm del gruppo gas generator. Un sistema di controllo del numero di giri tramite variazione di portata di combustibile è stato realizzato al fine di poter, in futuro, far funzionare il modello anche fuori dalla condizione di progetto e riuscire a simulare l'andamento delle prove sperimentali reali.

New Steel Alloys for the Design of Heat Recovery Steam Generator Components of Combined Cycle Gas Plants

Demand for power is growing every day, mainly due to emerging economies in countries such as China, Russia, India, and Brazil. During the last 50 years steam pressure and temperature in power plants have been continuously raised to improve thermal efficiency. Recent efforts to improve efficiency leads to the development of a new generation of heat recovery steam generator, where the Benson once-through technology is applied to improve the thermal efficiency. The main purpose of this paper is to analyze the mechanical behavior of a high pressure superheater manifold by applying finite element modeling and a finite element analysis with the objective of analyzing stress propagation, leading to the study of damage mechanism, e.g., uniaxial fatigue, uniaxial creep for life prediction. The objective of this paper is also to analyze the mechanical properties of the new high temperature resistant materials in the market such as 2Cr Bainitic steels (T/P23 and T/P24) and also the 9-12Cr Martensitic steels (T/P91, T/P92, E911, and P/T122). For this study the design rules for construction of power boilers to define the geometry of the HPSH manifold were applied.

Microfluidic hydrogen generator : featuring passive on-demand gas generation and self-circulated reactant for integration with micro fuel cell

A microfluidic hydrogen generator is presented in this work. Its fabrication, characterization, and integration with a micro proton exchange membrane (PEM) fuel cell are described. Hydrogen gas is generated by the hydrolysis of aqueous ammonia borane. Gas generation, as well as the circulation of ammonia borane from a rechargeable fuel reservoir, is performed without any power consumption. To achieve this, directional growth and selective venting of hydrogen gas is maintained in the microchannels, which results in the circulation of fresh reactant from the fuel reservoir. In addition to this self-circulation mechanism, the hydrogen generator has been demonstrated to self-regulate gas generation to meet demands of a connected micro fuel cell. All of this is done without parasitic power consumption from the fuel cell. Results show its feasibility in applications of high-impedance systems. Lastly, recommendations for improvements and suggestions for future work are described

Calibration of cosmogenic noble gas production in ordinary chondrites based on 36 Cl- 36 Ar ages. Part 1: Refined produced rates for cosmogenic 21 Ne and 38 Ar

We measured the concentrations and isotopic compositions of He, Ne, and Ar in bulk samples and metal separates of 14 ordinary chondrite falls with long exposure ages and high metamorphic grades. In addition, we measured concentrations of the cosmogenic radionuclides 10Be, 26Al, and 36Cl in metal separates and in the nonmagnetic fractions of the selected meteorites. Using cosmogenic 36Cl and 36Ar measured in the metal separates, we determined 36Cl-36Ar cosmic-ray exposure (CRE) ages, which are shielding-independent and therefore particularly reliable. Using the cosmogenic noble gases and radionuclides, we are able to decipher the CRE history for the studied objects. Based on the correlation 3He/21Ne versus 22Ne/21Ne, we demonstrate that, among the meteorites studied, only one suffered significant diffusive losses (about 35%). The data confirm that the linear correlation 3He/21Ne versus 22Ne/21Ne breaks down at high shielding. Using 36Cl-36Ar exposure ages and measured noble gas concentrations, we determine 21Ne and 38Ar production rates as a function of 22Ne/21Ne. The new data agree with recent model calculations for the relationship between 21Ne and 38Ar production rates and the 22Ne/21Ne ratio, which does not always provide unique shielding information. Based on the model calculations, we determine a new correlation line for 21Ne and 38Ar production rates as a function of the shielding indicator 22Ne/21Ne for H, L, and LL chondrites with preatmospheric radii less than about 65 cm. We also calculated the 10Be/21Ne and 26Al/21Ne production rate ratios for the investigated samples, which show good agreement with recent model calculations.

Calibration of cosmogenic noble gas production based on ³⁶Cl-³⁶Ar ages. Part 2. The ⁸¹Kr-Kr dating technique

We calibrated the ⁸¹Kr-Kr dating system for ordinary chondrites of different sizes using independent shielding-corrected ³⁶Cl-³⁶Ar ages. Krypton concentrations and isotopic compositions were measured in bulk samples from 14 ordinary chondrites of high petrologic type and the cosmogenic Kr component was obtained by subtracting trapped Kr from phase Q. The thus-determined average cosmogenic ⁷⁸Kr/⁸³Kr, ⁸⁰Kr/⁸³Kr, ⁸²Kr/⁸³Kr, and ⁸4Kr/⁸³Kr ratiC(Lavielle and Marti 1988; Wieler 2002). The cosmogenic ⁷⁸Kr/⁸³Kr ratio is correlated with the cosmogenic 22Ne/21Ne ratio, confirming that ⁷⁸Kr/⁸³Kr is a reliable shielding indicator. Previously, ⁸¹Kr-Kr ages have been determined by assuming the cosmogenic production rate of ⁸¹Kr, P(⁸¹Kr)c, to be 0.95 times the average of the cosmogenic production rates of ⁸⁰Kr and ⁸²Kr; the factor Y = 0.95 therefore accounts for the unequal production of the various Kr isotopes (Marti 1967a). However, Y should be regarded as an empirical adjustment. For samples whose ⁸⁰Kr and ⁸²Kr concentrations may be affected by neutron-capture reactions, the shielding-dependent cosmogenic (⁷⁸Kr/⁸³Kr)c ratio has been used instead to calculate P(⁸¹Kr)/P(⁸³Kr), as for some lunar samples, this ratio has been shown to linearly increase with (⁷⁸Kr/⁸³Kr)c (Marti and Lugmair 1971). However, the ⁸¹Kr-Kr ages of our samples calculated with these methods are on average ~30% higher than their ³⁶Cl-³⁶Ar ages, indicating that most if not all the ⁸¹Kr-Kr ages determined so far are significantly too high. We therefore re-evaluated both methods to determine P(⁸¹Kr)c/P(⁸³Kr)c. Our new Y value of 0.70 ± 0.04 is more than 25% lower than the value of 0.95 used so far. Furthermore, together with literature data, our data indicate that for chondrites, P(⁸¹Kr)c/P(⁸³Kr)c is rather constant at 0.43 ± 0.02, at least for the shielding range covered by our samples ([⁷⁸Kr/⁸³Kr]c = 0.119–0.185; [22Ne/21Ne]c = 1.083–1.144), in contrast to the observations on lunar samples. As expected considering the method used, ⁸¹Kr-Kr ages calculated either directly with this new P(⁸¹Kr)c/P(⁸³Kr)c value or with our new Y value both agree with the corresponding ³⁶Cl-³⁶Ar ages. However, the average deviation of 2% indicates the accuracy of both new ⁸¹Kr-Kr dating methods and the precision of the new dating systems of ~10% is demonstrated by the low scatter in the data. Consequently, this study indicates that the ⁸¹Kr-Kr ages published so far are up to 30% too high.

Unit, intermediate (field) (direct and general support) and depot maintenance repair parts and special tools list : generator set, aviation, gas turbine engine driven, integral trailer mounted, 10KW, 28 volts : DoD model MEP 362A, class precise, mode DC, NSN 6115-01-161-3992.

Includes index.

Operator's and unit maintenance manual : gas turbine engine driven aviation generator set, NSN 6115-01-161-3992.

Includes index.

Operator/crew and organizational maintenance manual : generator set, gas turbine engine driven, skid mounted, 150 KW, alternating current, tactical, model D424A, class precise, hertz 400, NSN 6115-01-113-1093.

"8 October 1982."