This thesis developed thin film extraction technique, which is a solid phase microextraction (SPME) technique with enhanced sensitivity, without sacrificing analysis time due to the large surface area-to-volume ratio of thin film. Thin film extraction was applied for both spot sampling and time weighted average (TWA) sampling in laboratory and on site. First, an electric drill coupled with a SPME polydimethylsiloxane (PDMS) fiber or a PDMS thin film was used for active spot sampling of polycyclic aromatic hydrocarbons (PAHs) in aqueous samples. Laboratory experiments demonstrated that the sampling rates of fiber and thin film can be predicted theoretically. The performance of a PDMS-coated stir bar at a constant stirring speed was also investigated. Compared with the fiber or the stir bar, the thin film sampler exhibited a higher sampling rate and much better sensitivity due to its higher surface-to-volume ratio and its larger extraction-phase volume. A new thin film active sampler was developed; field tests illustrated that it was excellent for rapid on-site water sampling due to its short sampling period, high sampling efficiency and durability. Second, modeling was applied to study the kinetics of fiber SPME and thin film extraction by COMSOL Multiphysics. The symmetry of absorption of analyte onto the fiber (or thin film) and desorption of calibrant from the fiber in static aqueous solution and a flow through system, was demonstrated by modeling. Furthermore, kinetic calibration method was illustrated to be feasible for fiber SPME in complex aqueous matrix and then was used to calculate the total concentration of analyte in the system. Third, thin film extraction was used in on-site sampling in Hamilton Harbour and for the determination of TWA concentrations of PAHs based on the kinetic calibration. When the thin film sampler, a fiber-retracted SPME field water sampler, and a SPME rod were used simultaneously, the thin film sampler exhibited the highest sampling rate compared to the other water samplers, due to its large surface-to-volume ratio. Fourth, partition equilibriums and extraction rates of PAHs were examined for live biomonitoring with black worms and for the PDMS thin-film in passive sampling mode. In the initial extraction stage, the extracted amounts per surface area by two samplers were similar indicating that thin-film samplers could mimic the behavior of black worms for passive monitoring. A good linear relationship between bioconcentration factors and film-water partition coefficients of PAHs demonstrated the feasibility of thin-film sampler for determining the bioavailability of PAHs in water. Finally, thin film extraction was used for the analysis of human skin and breath under different experimental conditions. Thin film technique could study several skin areas of one person, characterize the skins of different persons, and measure volatile fractions of cosmetic products that were released from the skin. The sampling time in the breath analysis could be further reduced to only 20 seconds when the thin film was rotated with a portable drill.

The overall objective of this research was to develop and assess a new method, named remedial extraction and catalytic hydrodehalogenation (REACH), for removing and destroying soil contaminants. In particular, I considered hydrophobic halogenated organic compounds (HHOCs). In this research, I developed a closed-loop treatment process that catalytically destroys the contaminants of concern, and does not generate a secondary waste stream. Mixtures of water and ethanol appear to be good candidates for the extraction of 1,2,4,5-tetrachlorobenzne (TeCB) or pentachlorophenol (PCP) from contaminated soil. Palladium-catalyzed hydrodehalogenation (HDH) was applied for destroying TeCB or PCP in mixtures of water and ethanol in a batch mode. The experimental results are all consistent with a Langmuir-Hinshelwood model for heterogeneous catalysis. Major findings that can be interpreted within the Langmuir- Hinshelwood framework are as follows: the rate of HDH depends strongly on the solvent composition, increasing as the water fraction of the solvent increases; the kinetics of the HDH reaction are apparently first-order with respect to the concentration of TeCB in the solvent; and the HDH rate increases as the catalyst concentration in the reactor increases. Also, TeCB is converted rapidly and quantitatively to benzene, with only trace concentrations of 1,2,4-trichlorobenzene appearing as a reactive intermediate. PCP is transformed to phenol by sequential reductive dehalogenation to tetrachlorophenols, then to trichlorophenols, then to phenol. The degradation of PCP does not follow firstorder kinetics, probably because of competitive reactions of intermediate products that are generated during PCP degradation. Following the batch studies, the REACH technology was applied in continuous mode under baseline conditions for a span of 7 weeks to treat soils that had been synthetically contaminated by HHOCs in the laboratory. Extraction of TeCB and PCP from soils was almost completed within two days by a 50:50 mixture of water and ethanol. Higher reaction rates were observed for TeCB than for PCP. The activity of the catalyst was slowly lost as contaminant mass was removed from the soil. The deactivated catalyst was successfully regenerated with a dilute sodium hypochlorite solution. The results of this research suggest that REACH could be a viable technology for some contaminated soils.

Weblogs have been growing quickly and transforming the World Wide Web toward a dynamic environment that Web pages are frequently updated. Although, Google has developed the search engine successfully in cope with the traditional web pages, it cannot effectively handle the dynamic blogspace. This research proposes an ontology-based semantic annotation framework based on concepts level in order to adaptively recommend blogrolls. The keyword match is being replaced by the semantic annotation technology of IE (Information Extraction) domain to implement a recommendation system. The objective of the recommendation system is to produce a recommended blogroll to the target weblog based on the weblog¡¦s concept affinities. Data sources of this research are from java.blogs community. The experiment of recommendation system is evaluated by Java programmers. The recommended blogrolls are evaluated by relevance that subjects score the degree of relevance between a target blogger and the recommended blogroll. The reliability of relevance among subjects is also tested. The results show that the recommended blogrolls obtain the middle level of relevance measured by subjects. The relevance evaluation of the recommended blogroll is independent from the concept density of the target blogger. The recommendation system is also reliable. Moreover, this study shed light on directions to improve the automated blogroll recommendation.

Extraction with sodium phosphate has been used as a method of accessing arsenic in soils. Arsenic extraction efficiency by phosphate from rice-paddy soils of Bangladesh usually has been low and highly variable between soils. The major objectives of this study were to examine the relationships between phosphate-extractable arsenic and soil iron-oxide composition and to investigate the experimental factors which might influence arsenic-extraction efficiency from rice-paddy soils of Bangladesh by phosphate. Statistical analysis of approximately 500 surface soils from Bangladesh indicated that phosphate-extractable arsenic was well correlated with total soil arsenic (r2 = 0.832) and oxalate-extractable arsenic (r2 = 0.825), though extraction efficiency varied widely (5 - 54 % of the total soil arsenic). The thanas with the lowest arsenic contents generally also had the soils with the lowest arsenic-extraction efficiencies. Quantity of phosphate-extractable arsenic was weakly correlated with the soil iron-oxide content, but extraction efficiency (i.e., the proportion of phosphate-extractable arsenic to total soil arsenic) was not correlated with any iron-oxide parameter. Arsenic extraction was strongly influenced by reaction variables such as sample grinding, phosphate concentration, principal counterion, reaction pH, and reaction time. The extraction efficiency was impacted by the influence of these individual factors on reaction kinetics and accessibility of arsenic adsorption sites for ligand exchange by phosphate. A portion of the arsenic was readily exchanged during the first few hours of extraction, followed by a much slower subsequent extraction. These results indicate that some of the arsenic is easily exchanged, but for a substantial portion of the arsenic, either the reaction kinetics is very slow or the sites are not accessible for reaction with phosphate. Extraction by phosphate is a useful procedure for the assessment of readily ligand-exchanged arsenic.

The MixAlco process, a proprietary technology owned by Texas A&M University, converts biomass (e.g., municipal solid waste, sewage sludge, paper, agricultural residues, and energy crops) into usable chemicals (e.g., acetic acid) and fuels (e.g., ethanol). Historically, calcium carbonate has been used as the buffer. Recently, it was found that using ammonium bicarbonate as the buffering agent enhances the fermentation conversion. In this case, fermentation broth contains ammonium salts (e.g., ammonium acetate, propionate, butyrate, pentanoate). Therefore, the downstream processing steps (including extraction, purification, esterification, and product separation) must be compatible with the ammonium carboxylate salts formed in the fermentation. This research focuses on converting fermentation broth carboxylate salts into their corresponding acids via "acid springing." Reactive extraction and thermal conversion (distillation) are crucial parts of the acid springing process. Because the components of the fermentation broth are over 80% ammonium acetate and 20% other ammonium carboxylate salts (ammonium propionate, butyrate, pentanoate, etc.), all the initial experiments in this study were performed using reagentgrade ammonium acetate to simplify the reaction. Later, actual fermentation broth was employed. The primary objective of this study was to provide the optimal operating conditions to make the downstream processing steps of the MixAlco process compatible with ammonium carboxylate salts formed in the fermentation. The optimal initial concentration for reactive extraction should be 150-200 g/L and the volume ratio of aqueous phase and extractant should be 1:1. The distribution coefficient reaches the maximum value when the concentration of TOA is 20% (vol %) in n-octanol. The batch distillation study shows that there are two reaction stages: (1) water leaves the system at 100-106 °C and (2) the acid-amine complex decomposes at 160-180 °C.

Reproduction de : Thèse de doctorat : Science des agroressources : Toulouse, INPT : 2006. / Titre provenant de l'écran-titre. Bibliogr. 58 réf.

Background: Removal of teeth results in both horizontal and vertical changes of hard and soft tissue dimensions. The magnitude of these changes is important for decision-making and comprehensive treatment planning, with provisions for possible solutions to expected complications during prosthetic rehabilitation. Objectives: to review all English dental literature to assess the magnitude of dimensional changes of both the hard and soft tissues of the alveolar ridge up to 12 months following tooth extraction in humans. Materials and methods: An electronic MEDLINE and CENTRAL search complemented by manual searching was conducted to identify randomized controlled clinical trials and prospective cohort studies on hard and soft tissue dimensional changes after tooth extraction. Only studies reporting on undisturbed post-extraction dimensional changes relative to a fixed reference point over a clearly stated time period were included. Assessment of the identified studies and data extraction was performed independently by two reviewers. Data collected were reported by descriptive methods. Weighted means and percentages of the dimensional changes over time were calculated where appropriate. Results: The search provided 3954 titles and 238 abstracts. Full text analysis was performed for 104 articles resulting in 20 studies that met the inclusion criteria. In human hard tissue, horizontal dimensional reduction (3.79 ± 0.23 mm) was more than vertical reduction (1.24 ± 0.11 mm on buccal, 0.84 ± 0.62 mm on mesial and 0.80 ± 0.71 mm on distal sites) at 6 months. Percentage vertical dimensional change was 11-22 % at 6 months. Percentage horizontal dimensional change was 32% at 3 months, and 29-63% at 6-7 months. Soft tissue changes demonstrated 0.4-0.5 mm gain of thickness at 6 months on the buccal and lingual aspects. Horizontal dimensional changes of hard and soft tissue (loss of 0.1 mm to 6.1 mm) was more substantial than vertical change (loss 0.9 mm to gain 0.4mm) during observation periods of up to 12 months, when study casts were utilised as a means of documenting the changes. Conclusions: Human re-entry studies showed horizontal bone loss of 29-63% and vertical bone loss of 11-22% after 6 months following tooth extraction. These studies demonstrated rapid reductions in the first 3-6 months that was followed by gradual reductions in dimensions thereafter. / published_or_final_version / Dental Surgery / Master / Master of Dental Surgery

Background: Removal of teeth results in both horizontal and vertical changes of hard and soft tissue dimensions. The magnitude of these changes is important for decision-making and comprehensive treatment planning, with provisions for possible solutions to expected complications during prosthetic rehabilitation. Objectives: to review all English dental literature to assess the magnitude of dimensional changes of both the hard and soft tissues of the alveolar ridge up to 12 months following tooth extraction in humans. Materials and methods: An electronic MEDLINE and CENTRAL search complemented by manual searching was conducted to identify randomised controlled clinical trials and prospective cohort studies on hard and soft tissue dimensional changes after tooth extraction. Only studies reporting on undisturbed post-extraction dimensional changes relative to a fixed reference point over a clearly stated time period were included. Assessment of the identified studies and data extraction was performed independently by two reviewers. Data collected were reported by descriptive methods. Weighted means and percentages of the dimensional changes over time were calculated where appropriate. Results: The search provided 3954 titles and 238 abstracts. Full text analysis was performed for 104 articles resulting in 20 studies that met the inclusion criteria. In human hard tissue, horizontal dimensional reduction (3.79 ± 0.23 mm) was more than vertical reduction (1.24 ± 0.11 mm on buccal, 0.84 ± 0.62 mm on mesial and 0.80 ± 0.71 mm on distal sites) at 6 months. Percentage vertical dimensional change was 11-22 % at 6 months. Percentage horizontal dimensional change was 32% at 3 months, and 29-63% at 6-7 months. Soft tissue changes demonstrated 0.4-0.5 mm gain of thickness at 6 months on the buccal and lingual aspects. Horizontal dimensional changes of hard and soft tissue (loss of 0.1 mm to 6.1 mm) was more substantial than vertical change (loss 0.9 mm to gain 0.4mm) during observation periods of up to 12 months, when study casts were utilised as a means of documenting the changes. Conclusions: Human re-entry studies showed horizontal bone loss of 29-63% and vertical bone loss of 11-22% after 6 months following tooth extraction. These studies demonstrated rapid reductions in the first 3-6 months that was followed by gradual reductions in dimensions thereafter. / published_or_final_version / Dental Surgery / Master / Master of Dental Surgery

Abstract Surface water and sediment samples collected from Jukskei River in South Africa, were subjected to different extraction techniques, liquid–liquid (LLE), solidphase extraction (SPE), activated carbon extraction (ACE) and soxhlet extraction (SE) for sediment. The samples were extracted with dichloromethane, cleaned in a silica gel column and the extracts quantified using a Varian 3800 GC-ECD. The percentage recovery test for 2,40DDT, DDE and DDD and 4,40DDT, DDE and DDD in water ranged from 80%–96% and 76%–95% (LLE); 56%–76% and 56%–70% (SPE) and 75%–84% (ACE), respectively; while that recoveries for sediment samples varied from 65%– 95% for 2,40DDT, DDE and DDD and 80%–91% for 4,40DDT, DDE and DDD. The high recoveries exhibited by ACE compared very well with LLE and SE. This was not the case with SPE which exhibited the lowest value of recoveries for both 2,4 and 4,40DDD, DDE and DDT standard samples. The mean concentrations of DDT and metabolites ranged from nd-1.10 lg/L, nd-0.80 lg/L, nd- 1.21 lg/L and 1.92 lg/L for LLE, SPE, ACE and SE, respectively. The total DDT (2,40 and 4,40-DDT) in water and sediment samples ranged from 1.20–3.25 lg/L and 1.82–5.24 lg/L, respectively. The low concentrations of the DDT metabolites obtained in the present study may suggest a recent contamination of the river by DDT.

The concept of an Image Difference Spectrum, a novel tool for the extraction of global image information, is introduced. It is shown that Image Difference Spectra are fast alternatives to granulometric curves, also referred to as pattern spectra. Image Difference Spectra are computationally easy to implement and are suitable for real-time applications.