No description available.

[pt] O uso do calor como meio alternativo para a remediação de áreas contaminadas por compostos orgânicos - hidrocarbonetos derivados de petróleo e policíclicos aromáticos, organoclorados, pesticidas, dentre outros - tem se mostrado competitivo quando comparado a outras soluções, principalmente levando-se em consideração questões práticas como a eficiência dos seus resultados e o seu tempo de execução. Seguindo uma linha de pesquisa do Núcleo de Geotecnia Ambiental da PUC-Rio, esta dissertação se propõe a aperfeiçoar o sistema de dessorção térmica in situ a partir do desenvolvimento de um novo bastonete térmico e de um sistema de medição de temperaturas in situ. O seu escopo envolveu, principalmente, a avaliação do seu desempenho quando submetido às condições naturais de campo a partir de experimentos realizados em dois locais diferentes: nas dependências da EMBRAPA Solos, no Jardim Botânico, e na área externa do Laboratório de Geotecnia e Meio Ambiente da PUC-Rio. No primeiro caso, por ser um solo areno-argiloso, a temperatura se manteve mais concentrada em pontos mais próximos ao bastonete. Já no segundo, representado por um solo areno- siltoso, a temperatura chegou a pontos mais distantes com maior intensidade. Não houve modificação estrutural significativa em ambos os solos. Nos dois casos, a eficiência do sistema foi extremamente dificultada pelos baixos graus de saturação e teor de umidade, o que fez com que o calor aplicado se perdesse com maior facilidade. Após algumas modificações em seu projeto original, o bastonete térmico desenvolvido se comportou bem, principalmente no último ensaio, que durou 24 dias. Paralelamente, em laboratório, foram avaliados o comportamento da microbiota após a aplicação de calor no solo e a possibilidade de aptidão deste meio à existência de novos seres vivos após a injeção de água e nutrientes inorgânicos. Verificou-se uma recuperação e estabilização destes indivíduos em aproximadamente 03 semanas. Observou-se ainda a recuperação parcial da atividade metabólica; no entanto foi visto que a sua taxa decresce com o tempo, motivada provavelmente pela falta de matéria orgânica no solo. / [en] The use of thermal processes in order to remediate contaminated sites has been shown a great deal of promise, especially when time and effectiveness are considered. The present work describes the development of a new in situ device that simultaneously applies heat and delivers compressed air into the porous media. Additionally, a new set of instruments were also designed and built in order to monitor temperature and to extract vapor from the vadose zone. Tests performed at EMBRAPA Solos site and PUC-Rio Campus showed a good performance of the pieces of equipment developed. In addition, microbiological tests performed at the Geotechnical and Environmental Lab showed that is possible to recover the natural microbiota after prolonged exposure to temperatures above 400 ºC. Results have shown a recovery and stabilization of the population in about 3 weeks. However, it was also observed that metabolic activity was not fully recovered, in part due the lack of nutrients and organic matter in the porous media.

Abstract not available

Abstract not available

A constrained thin film desorption scheme has been experimentally tested to determine the desorption rates for water from an aqueous lithium bromide mixture through a confining membrane. Variable conditions include the inlet concentration, pressure differential across the membrane, and channel height. Desorption takes place in a channel created between two parallel plates with one of the walls being both heated and porous. A hydrophobic porous membrane creates a liquid-vapor interface and allows for vapor removal from the channel. Inlet concentrations of 32 wt%, 40 wt%, and 50 wt% lithium bromide were tested at an inlet sub-atmospheric pressure of 33.5 kPa. Pressure differentials across the membrane of 6 kPa and 12 kPa were imposed along with two channel heights of 170 μm and 745 μm. All cases were run at an inlet mass flow rate of 3.2 g/min, corresponding to Reynolds numbers of approximately 2.5 to 4.5. The membrane surface area for desorption was 16.8 cm². A maximum desorption rate (vapor mass flow rate) of 0.51 g/min was achieved, for the 32 wt%, 12 kPa pressure differential, and 170 μm channel. Increasing the pressure differential across the channel allowed for higher desorption rates at a fixed wall superheat, and delayed the transition to boiling. As the inlet concentration increased the desorber's performance decreased as more energy was required to produce a fixed desorption rate. Results are also presented for the variation in the heat transfer coefficient with the wall superheat temperature. The increase in the channel height had a negative influence on the heat transfer coefficient, requiring larger superheat values to produce a fixed desorption rate. / Graduation date: 2005 / Best scan available for tables and computer code in the appendices. The original is faded.

Measurement of monoterpenes including / alpha-pinene, camphene, beta-pinene, d-limonene, gamma-terpinene, linalool, 1-isopulegol, 1-borneol, dl-menthol, alpha-terpineol, dihydrocarveol, citronellol, pulegone, geraniol / and gas phase inorganic pollutants (O3 and NOx) were investigated on Uludag Mountain, which is the highest point in North-west Turkey. The sampling site (1645 m altitude) is surrounded by mainly Uludag fir, which is characteristic to Uludag, while altitudes lower than 1000 m were composed of mixed deciduous trees. Sampling apparatus and sampling strategy for collection of the studied terpenes on Uludag Mountain were developed. Breakthrough Volume experiments were performed for accurate sampling. Samples were collected in a field campaign performed during October 2002 by means of active sampling onto glass coated stainless steel tubes containing Tenax&amp / #61666 / TA (55 mg) and Carbopack&amp / #61652 / B (65 mg). The mass flow rate and duration of sampling were 30 mL/min and 4 hours. Short-Path-Thermal-Desorption/Gas Chromatography-Mass Spectrometer (SPTD/GC-MS) was used for the analysis of monoterpenes during 12-14 October 2002. The cryogenic preconcentration (-40oC) was maintained by liquid CO2. HP-1-MS capillary column provided good resolution of peaks, except for pulegone and citronellol at standard operation procedure. Internal standard calibration was applied by adding carefully measured spikes of fenchone to the samples and standards. The detection limits for each terpene were found to be at sub-ppbv level. Daily intermediate standard measurements and auto-tune provided checking the instrumental capabilities. Selected Ion Monitoring mode was used for analysis of the terpenes. For quantitation of the spectra at least one qualifier ion was expected to be within 80% correlation with target ion. Alpha-pinene, camphene, beta-pinene, and d-limonene were determined. The average concentrations of monoterpenes were found to be 0.385, 0.168, 0.111, and 0.204 ppbv respectively. Simultaneous measurements of O3, NOx, SO2, and meteorological parameters were also performed. The data resolution was 15 min for each pollutant. Ozone displayed strong diurnal variation (around 5-30 ppb), while NOx concentrations were almost constant around 15 ppb. During the sampling campaign terpenes showed similar behaviours with O3, but not with NOx. Terpenes had a direct relation with temperature and relative humidity.

Refrigeration systems employing the NH3-H2O absorption cycle provide cooling using a thermal energy input. This cycle relies on the zeotropic nature of the refrigerant - absorbent pair: because of the difference in boiling temperatures between NH3 and H2O, they can be separated through selective boiling in the desorber. Desorbers with counter-current flow of the solution and generated vapor enable efficient heat and mass transfer between the two phases, reducing the absorbent content in the generated vapor. Flow visualization experiments at temperatures, concentrations and pressures representative of operating conditions are necessary to understand the heat and mass transfer processes and flow regime characteristics within the component. In this study, a Flooded Column desorber, which accomplishes desorption of the refrigerant vapor through a combination of falling-film and pool boiling, was fabricated and tested. Refrigerant-rich solution enters the top of the component and fills a column, which is heated by an adjacent heated microchannel array. The vapor generated within the component is removed from the top of the component, while the dilute solution drains from the bottom. Flow visualization experiments showed that the Flooded Column desorber operated most stably in a partially flooded condition, with a pool-boiling region below a falling-film region. It was found that the liquid column level was dependent on operating conditions, and that the pool-boiling region exhibits aggressive mixing between the vapor and solution phases. Heat transfer coefficients were calculated from the data for the pool-boiling region, and were compared with the predictions of several mixture pool-boiling correlations from the literature. The correlations from the literature were in general unable to predict the data from this study adequately. It was found that the Flooded Column desorber yielded higher heat transfer coefficients within the pool-boiling region than those predicted by these correlations. Therefore, modifications to existing mixture boiling correlations are suggested based on the findings of this study. The resulting modified correlation predicts 33 of the 35 data points from this study within ±40%, with an average absolute error of 19%.

Unique physical properties such as small effective mass, high electron drift velocities, high electron mobility and small band gap energy make InN a candidate for applications in high-speed microelectronic and optoelectronic devices. The aim of this research is to understand the surface properties, desorption kinetics and thermal stability of InN epilayers that affect the growth processes and determine film quality as well as device performance and life time. We have investigated the structural properties, the surface desorption kinetics, and the thermal stability using Auger electron spectroscopy (AES), x-ray diffraction (XRD), Raman spectroscopy, atomic force microscopy (AFM), high resolution electron energy loss spectroscopy (HREELS), and temperature programmed desorption (TPD). Investigations on high pressure chemical vapor deposition (HPCVD)-grown InN samples revealed the presence of tilted crystallites, which were attributed to high group V/III flux ratio and lattice mismatch. A study of the thermal stability of HPCVD-grown InN epilayers revealed that the activation energy for nitrogen desorption was 1.6±0.2 eV, independent of the group V/III flux ratio. Initial investigations on the ternary alloy In0.96Ga0.04N showed single-phase, N-polar epilayers using XRD and HREELS, while a thermal desorption study revealed an activation energy for nitrogen desorption of 1.14 ± 0.06 eV. HREELS investigations of atomic layer epitaxy (ALE)-grown InN revealed vibrational modes assigned to N-N vibrations. The atomic hydrogen cleaned InN surface also exhibited modes assigned to surface N-H without showing In-H species, which indicated N-polar InN. Complete desorption of hydrogen from the InN surface was best described by the first-order desorption kinetics with an activation energy of 0.88 ± 0.06 eV and pre-exponential factor of (1.5 ± 0.5) ×105 s-1. Overall, we have used a number of techniques to characterize the structure, surface bonding configuration, thermal stability and hydrogen desorption kinetics of InN and In0.96Ga0.04N epilayers grown by HPCVD and ALE. High group V/III precursors ratio and lattice mismatch have a crucial influence on the film orientation. The effects of hydrogen on the decomposition add to the wide variation in the activation energy of nitrogen desorption. Presence of surface defects lowers the activation energy for hydrogen desorption from the surface.

Ambient ionization mass spectrometry, which has witnessed a flurry of recent developments, is a set of useful techniques for the analysis of samples under open-air conditions. It allows direct, rapid, real-time, high-throughput analysis with little or no sample pretreatment for the chemicals in solids or liquids. In this study, thermal desorption electrospray ionization mass spectrometry ( TD-ESI/MS ) involving direct insertion probe ( DIP ), thermal desorption ( TD ) and electrospray ionization ( ESI ) was used for the rapid screening of various types of samples. The source mainly consists of the sampling probe device, thermal desorption heating device, electrospray ionization device, ion source and temperature controller. A novel strategy involved in TD-ESI/MS processes where sampling, desorption, and ionization are separated as three independent events. The sampling probe is first used for the sampling of analytes and then inserted into a heat unit for thermal desorption. The desorbed analytes are finally carried into a reaction region with a stream of nitrogen gas, where charged methanol droplets were generated continuously by electrospray for post-ionization. Total analysis time is less than 10 seconds. Traditionally, three standard methods are used for the analysis for pesticide residues, biochemical, immunoassay and instrument. And, the instrument analysis is the most widely used because it provides lots of advantages in particularly accurate quantitative approach. However, its complicated steps take a long period of time for preparation. Here, we used TD-ESI/MS to rapidly screen the pesticide residues on the surface of fruits and vegetables. The MS/MS analysis was also performed to confirm those detected compounds. The experimental results of the standard deviation for reproducibility is 13.2% (n = 10), and the detection limit is approximately 10 ppb. Furthermore, several fruits and vegetables purchased from local market were used as test samples and pesticide residues on the surface of samples can be successfully detected via TD-ESI/MS. In addition, the TD-ESI/MS technique was also applied to the analysis of illegal additives or phthalates in food. In this study, the TD-ESI/MS technique emerges lots of advantages such as direct, rapid, real-time analysis of sample surface and sample pretreatment is not necessary, and shows highly potential for rapid screening of chemicals in food safety.

Asthma, current detection methods and metabolites proposed as asthma markers are described. The limitation of the disease diagnosis is outlined and metabolomics is introduced as the approach carried out within this research with the potential to measure the group metabolites that characterise the metabolic responses of a biological system to a specific disease. Chemistry underlying breathing, current breath collection and analytical techniques are described as well as detection and data processing technology associated within our research. A work-flow for the collection, analysis and processing of exhaled breath samples in respiratory diseases is described. The non-invasive sampling method allows collection of exhaled breath samples on children and adults without experiencing any discomfort. The analysis of exhaled breath samples using thermal desorption gas chromatography mass spectrometry outlines the use of retention index for the alignment of VOCs retention time shifting over time. This methodology enables the creation of a breath matrix for multivariate analysis data processing where each VOC is defined by retention index and most intense fragments of the mass spectrum. This methodology is tested in two cohorts of participants: paediatric asthma and severe asthmatic participants whose breath profiles are compared against healthy controls and within the two asthmatic phenotypes to prospect the markers that differentiate between the different groups. Eight candidate markers are identified to discriminate between asthmatic children and healthy children and seven markers between asthmatics undergoing therapy and healthy controls. The database from severe and paediatric asthma is compared, establishing seven non-age related markers between the two groups. A new interface is developed for the faster analysis of exhaled breath samples using thermal desorption ion mobility mass spectrometry. The interface front end has been modified and optimised to achieve the best sensitivity and resolution of VOCs in exhaled breath. A preliminary study carried out in a small cohort of volunteers shows the feasibility of the technique for the differentiation of asthmatic and healthy adults.