This research investigate and analysis 77 kinds of volatile organic compounds (VOCs) in the sewage system of a southern urban area (A, B, C, D, E and F). The 77 kinds of VOCs will be divided into BTEX, chlorine-containing hydrocarbons and non-chlorine-containing hydrocarbons, and to estimate the emission of 27 kinds of hazardous air pollutants (HAPs). Cancer risk within 12 kinds of HAPs will also be part of the investigation by using Risk Assessment. In terms of consistency, except A1, D5 and E, VOCs are required mainly of non-chlorine-containing hydrocarbons at other areas, and main contribution species are ethylene, acetylene and ethane. There are 55.05 % of BTEX (1298.2 £gg/m3) and 35.51 % of non-chlorine-containing hydrocarbons (837.6 £gg/m3) in A1, but the main contribution are toluene, m-xylene and p-xylene. In D5, there is 76.39 % of BTEX (3744.7 £gg/m3) and the main contribution are m-xylene, p-xylene and toluene. In E, there is 80.02 % of chlorine-containing hydrocarbons (4807.1 £gg/m3) and the main contribution are chloromethane and toluene. Results show that the most emissions of total HAPs is D5 (12195.3 mg/hr), followed by B2 (4602.9 mg/hr), E (2659.4 mg/hr), A4 (2043.7 mg/hr) and A1 (1526.2 mg/hr). BTEX represent the largest proportion of the emissions of total HAPs in D5, A4 and A1. Chloroethene represents the largest proportion of the emissions of total HAPs in B2, followed by trichloroethene and tetrachloroethene. Chloromethane represents the largest proportion of the emissions of total HAPs in E. The most cumulative cancer risk in the sewage space is B2, followed by C2 and A3. The main contribution of the average cancer risk (not include B2) in a southern urban area are 1,1,2-trichloroethane, 1,2-dichloroethane and 1,4-dichlorobenzene.

Thesis (Ph.D.) -- University of Glasgow, 2007. / PhD thesis submitted to Environmental, Agricultural and Analytical Chemistry, Department of Chemistry, University of Glasgow. Includes bibliographical references. Print version also available.

published_or_final_version / Environmental Management / Master / Master of Science in Environmental Management

Not available / text

This study addresses the origin of the combined He-Ne-Ar-Xe noble gas isotopic variation in mantle derived oceanic basalts. High precision heavy noble gas compositions of basalts from the Rochambeau Rift along the Northwestern Lau Basin, the Gakkel Ridge, the Southeast Indian Ridge and the South Atlantic Ridge presented here confirms fundamental differences between the volatile constituents of the depleted mid-ocean ridge basalt (MORB) source and plume sources. We find that the depleted MORB mantle is characterized by systematically lower proportions of Pu-fission derived Xe than the Iceland plume and the Samoan-like plume sampled at the Rochambeau Rift. These two plume sources are associated with low radiogenic \(^{129}Xe/^{130}Xe\) ratios that are not attributable to recycled atmosphere and must sample ancient (4.45 Ga) volatile rich mantle reservoir that experienced a lower degree of mantle processing than the depleted MORB source. I report \(^{128}Xe/^{130}Xe\) ratios in excess with respect to the atmosphere in deeply erupting Gakkel lavas, similar to mantle derived volatiles in natural gas samples. Deconvolution of fission derived xenon isotopes indicate that natural gas samples and the Gakkel MORBs are derived from the same volatile depleted mantle reservoir. The radiogenic He isotopic composition, the low estimated ratio of Pu to U derived xenon isotopes, and the low \(^{129}Xe/^{130}Xe_E\) ratio found in the source of the West Volcanic Zone (WVZ) along the Gakkel Ridge indicates the presence of increased amounts of recycled atmospheric volatiles. I suggest that the low \(^{129}Xe/^{130}Xe\) ratio beneath the WVZ cannot be explained by sampling an ancient (>4.45 Ga) lithospheric mantle component that evolved in isolation from convection throughout Earth's history. Instead, the Xe isotopic composition may be consistent with the presence of subduction derived metasomatizing fluids with atmospheric heavy noble gases trapped in the sub-continental lithospheric mantle sampled along the ridge. Available Ne isotope MORB data and new high precision Ne data presented in this study (including basalts from the East Pacific Rise, the Galapagos Spreading Center, and the Juan de Fuca Ridge) allows me to construct a combined He-Ne isotope distribution and infer first order source mixing systematics in the upper mantle. / Earth and Planetary Sciences

Not available / text

Many producing volatile oil reservoirs experience a significant decrease in well deliverability when the bottom-hole pressure of the well falls below the bubble point pressure. This is due to the liberation of a gas phase which resides in the pore space and blocks the flow of the oil phase. This situation is known as "gas blocking". This occurs because the presence of two or three immiscible phases (gas, oil and water) results in a reduction of the oil saturation and a decrease in the oil relative permeability. The main objective of this research was to develop an effective and durable chemical treatment method to improve and/or restore the productivity of volatile oil wells undergoing "gas blocking". The treatment method is based on the use of fluorinated surfactants in tailored solvents to increase the oil relative permeability by changing the wettability of the rock’s surface. High-temperature high-pressure (HTHP) core flood experiments were used to evaluate the uses of fluorinated surfactants under reservoir conditions. Analytical tools such as X-ray photoelectron spectroscopy (XPS), high-performance liquid chromatography (HPLC) and computerized axial tomography (CT Scan) were also used to interpret the experimental results. High-pressure high-temperature (HPHT) coreflood tests showed that the treatments improved the oil and gas relative permeability in both sandstone and limestone cores. This was observed for synthetic volatile oil mixtures with gas-oil ratios (GOR) in the range of 4000 to 13,000 scf/STB at low capillary numbers (Nc) on the order of 1x10-5 to 1x10-6 and for PVT ratios greater than 0.5. The fluorinated chemical treatments were effective in the presence of connate water over the temperature range of 155°F to 275°F. Wettability alteration was measured using contact angle and imbibition rate tests. Results from analytical tools showed that fluorinated surfactants were uniformly adsorbed along the core and the surfactant desorption after treatment was low (10 ppm or less). The gas saturation decreased following treatment and both the oil and gas relative permeability increased. Numerical simulations using the measured relative permeability data were used to estimate the gain in productivity for treated wells. The proposed fluorinated chemical treatments could be used as a preventive treatment or for a damaged well that has already been producing below the bubble point to increase oil production rates and recoverable reserves. / text

Τις τελευταίες δεκαετίες, η ανάπτυξη των non-volatile μνημών (NVMs) κατέστησε ικανή την αντικατάσταση volatile μνημών, όπως των DRAMs και των μαγνητικών σκληρών δίσκων (HDDs), σε caching και storage εφαρμογές, αντίστοιχα. Οι δίσκοι στερεάς κατάστασης (SSDs) που βασίζονται σε NAND Flash μνήμες έχουν ήδη αναδειχθεί ως ένα χαμηλού κόστους, υψηλής απόδοσης και αξιόπιστο μέσο στα σύγχρονα συστήματα αποθήκευσης. Επιπλέον, οι ιδιότητες των υλικών αλλαγής φάσης και η πρόσφατη κλιμάκωση της Phase-Change μνήμης (PCM), την καθιστά ένα τέλειο υποψήφιο για την ανάπτυξη μνημών τυχαίας προσπέλασης αλλαγής φάσης (PCRAMs). Η ραγδαία κλιμάκωση των NVMs, με διαδικασίες ολοκλήρωσης κάτω από 19nm, και η χρήση της multi-level cell (MLC) τεχνολογίας συνέβαλλαν στην αύξηση της πυκνότητας αποθήκευσης πληροφορίας και συνεπώς μείωσαν το κόστος αποθήκευσης δραματικά. Ωστόσο, η διάρκεια ζωής των NV μνημών δεν παρέμεινε ανεπηρέαστη. Διαφορετικές παρεμβολές και πηγές θορύβου σε συνδυασμό με την επίδραση της γήρανσης έχουν ένα μεγάλο αντίκτυπο στην αξιοπιστία και την αντοχή αυτών των τεχνολογιών μνήμης, και ως εκ τούτου, των συστημάτων αποθήκευσης στα οποία χρησιμοποιούνται (SSDs, PCRAMs). Πολλές μέθοδοι και τεχνικές, όπως η μέθοδος wear-leveling, εξειδικευμένοι κώδικες ανίχνευσης και διόρθωσης λαθών (ECC) και τεχνικές pre-coding έχουν χρησιμοποιηθεί για να αντισταθμίσουν αυτές τις επιπτώσεις, ενώ άλλες, πιο περίπλοκες μεν, αλλά και πιο αποτελεσματικές, όπως η δυναμική προσαρμογή των κατωφλίων ανάγνωσης, βρίσκονται σε πειραματικό στάδιο. Η ανάπτυξη αυτών των τεχνικών βασίζεται στον πειραματικό χαρακτηρισμό των NV μνημών, τόσο σε επίπεδο κελιού όσο και σε επίπεδο ολοκληρωμένου κυκλώματος. Ο χαρακτηρισμός αυτός σχετίζεται με την μέτρηση του λόγου του αριθμού των bit σφαλμάτων προς τον αριθμό των συνολικών bits (BER) και το χρόνο απόκρισης (ανάγνωσης και εγγραφής) καθ' όλη τη διάρκεια ζωής της μνήμης, για διάφορες μορφές δεδομένων και σενάρια χρονισμών. Η διαδικασία αυτή, μέχρι τώρα, γίνεται με τη χρήση της πραγματικής NV μνήμης, συνήθως με ολοκληρωμένα κυκλώματα που βρίσκονται στο στάδιο της προ-παραγωγής, ενώ πιο ενδελεχής έλεγχος γίνεται στο τελικό στάδιο της παραγωγής. Αυτή η προσέγγιση έχει δύο σημαντικά μειονεκτήματα. Από τη μία πλευρά, είναι μια πολύ χρονοβόρα διαδικασία, δεδομένου ότι η γήρανση μίας NVM μπορεί να απαιτεί ένα μεγάλο αριθμό από program / erase (P/E) κύκλους που πρέπει να εκτελεστούν για κάθε πείραμα. Ο αριθμός αυτός κυμαίνεται από κάποιες δεκάδες χιλιάδες (NAND Flash) έως και κάποια εκατομμύρια κύκλους (PCM). Από την άλλη πλευρά, τα χαρακτηριστικά γήρανσης μίας NVM είναι αναλόγως εξαρτώμενα από τον αριθμό των Ρ/Ε κύκλων που εκτελούνται, καθιστώντας έτσι αδύνατη την διεξαγωγή διαφορετικών ή διαδοχικών πειραμάτων στην ίδια κατάσταση γήρανσης της μνήμης. Σε αυτή την εργασία παρουσιάζουμε ένα μοντέλο που αντιπροσωπεύει με ακρίβεια τη διαδικασία γήρανσης NV μνημών, αντιμετωπίζοντας τες ως ένα χρονικά μεταβαλλόμενο κανάλι επικοινωνίας βασισμένο σε ένα μη συμμετρικό n-PAM μοντέλο. Με βάση τη μοντελοποίηση των χαρακτηριστικών γήρανσης, υλοποιούμε ένα σύστημα εξομοίωσης σε πραγματικό χρόνο και με μεγάλη ακρίβεια της συμπεριφοράς NV-μνημών, κάτω από ορισμένες από το χρήστη συνθήκες γήρανσης, σε τεχνολογία FPGA. Η πλατφόρμα που παρουσιάζεται στην παρούσα εργασία βασίζεται σε μια αναπροσαρμόσιμη αρχιτεκτονική υλικού και λογισμικού που επιτρέπει την ακριβή εξομοίωση των νέων και αναδυόμενων τεχνολογιών και μοντέλων των NVMs. Η πλατφόρμα που αναπτύχθηκε μπορεί να αποτελέσει ένα πολύτιμο εργαλείο για την ανάπτυξη και αξιολόγηση αλγορίθμων και τεχνικών κωδικοποίησης. / Over the last few years, non-volatle memory (NVM) has shown a great potential in replacing volatile memory, like DRAM in caching applications, and magnetic HDDs in storage applications. NAND Flash-based solid state drives (SSDs) have already emerged as a low-cost, high-performance and reliable storage medium for both commercial and enterprise storage systems. Additionally, the properties of phase-change materials and the recent scaling of Phase-Change Memory (PCM) has made it a perfect candidate for developing phase-change random access memories (PCRAMs). The rapid scaling of NVMs, with process nodes below 19nm, and the use of multi-level cell (MLC) technologies has increased their storage density and reduced the storage cost per bit. However, their lifetime capacity has not remained unaffected. Different interferences and noise sources along with aging effects have now a great impact on the reliability and endurance of these memory technologies, and hence, on the storage systems where these memories are used (SSDs, PCRAMs). Numerous techniques, such as wear-leveling, specialized error correcting codes (ECC) and precoding techniques have been employed to compensate these effects, while others, more complex but also more efficient, like dynamic adaptation of read reference thresholds, are at an experimental level. The development of these techniques is based on experimental characterization of NVM cells and chips. Characterization is related with measuring bit error ratio (BER) and response time (read and write time) during the whole lifetime of a device, for various loading data patterns and timing scenarios. This process is performed using real NVM integrated chips, usually the engineering, pre-production parts, while more thorough testing at the system level is performed when production parts are available. This approach has two major drawbacks. On one hand it is a very time-consuming process, since the aging of an NVM may require a large number of program/erase (P/E) cycles to be performed for each experiment, ranging from tens of thousands (NAND Flash) to millions (PCM) program cycles. On the other hand, the aging characteristics of an NVM are proportionally dependent on the number of the performed P/E cycles, thus making it impossible to conduct different or successive experiments at the same aging state of a memory chip. In this work, we present a model that accurately represents the aging process of an NVM cell, by treating it as a time-variant communications channel, based on an asymmetric n-PAM model. We present the architecture of a flexible FPGA-based platform, designed for accurate emulations of NVM technologies, focusing mainly on MLC NAND Flash technologies. Accuracy is measured in reference to experimentally specified bit error probabilities for various aging conditions (ie. the number of P/E cycles applied to a NAND Flash chip), usually for random data patterns. The hardware platform presented in this work is based on a reconfigurable hardware-software architecture, which enables the accurate emulation of new and emerging models and technologies of NVMs. The developed platform can be a valuable tool for the evaluation of memory-related algorithms, signal processing and coding techniques.

Anaerobic digestion is a common process for treatment of wastewater sludge from municipal sewage systems. Volatile sulfur compounds, including volatile organic sulfur compounds (VOSCs) and hydrogen sulfide, have been reported as the most odorous compounds in digestion emissions and impurities which can damage facilities for generation, transportation, storage, and utilization of biogas. There has been no comprehensive study on biological generation and degradation kinetics of VOSC or modeling VOSC behaviors through anaerobic sludge digestion. The goal of the present study was to establish a model for VOSC conversions in anaerobic sludge digestion which could facilitate quantitative analysis of VOSC emissions in anaerobic digestion. VOSCs and methionine were employed in dosed batch tests. VOSC conversion processes in anaerobic methionine digestion have been identified. The kinetics for the identified VOSC degradation and conversion processes were determined at 35 and 55 °C respectively. Mixed-second order kinetics were found to best fit the conversion processes. A model was established based on the identified processes and estimated kinetic constants. To extend the model to VOSC release in anaerobic sludge digestion, mesophilic and thermophilic incubations were conducted with four different sludge samples. The effects of temperature and sludge source on VOSC release patterns were assessed. It was found that an unidentified DMS generation mechanism was triggered in the mesophilic incubation of activated sludge in which iron was dosed. To apply the model which was established based on methionine degradation in sludge digestion, hydrolysis of particulate materials was incorporated. The model simulations for VOSC behavior in thermophilic batch incubation were able to represent the observed VOSC releases. However, the simulations could not well fit the observed VOSC release at 35 ° because the model did not include the unidentified DMS generation mechanism. Application of the model to bench-scale digesters was lack-of-fit. It may have been due to imprecise estimation of the degradable sulfur in the feed sludge. In addition, in the batch tests and digester operation the ratios of the raw and digested sludge were different. This might have resulted in different concentrations of the microorganisms which mediated biotransformations and hence resulted in different kinetic constants.

Fragaria ananassa, generally known as strawberry is a nutritious fruit that is rich in polyphenols and widely consumed as part of a healthy diet. Anthocyanins have been found to be the main group of phenolic components present in strawberry with pelargonidin-3-glucoside as the major component in all strawberry cultivars studied. The main volatile component has been identified as caryophyllene oxide, a sesquiterpene compound that was present abundantly in all cultivars. The effect of preharvest spray applications of a formulation containing hexanal which is known to enhance membrane preservation, was evaluated using two strawberry cultivars, ‘Jewel’ and ‘Mira’. Our results suggest that preharvest spray application of hexanal formulation results in biochemical changes that alter the profile of phenolic compounds and the volatiles of the fruit. An osmotic infusion treatment was implemented to generate an intermediate moisture food product with high quality and enhanced storage life that can be potentially used in processed food. Infusing strawberry with other functional ingredients such as fructoligosaccharides, lecithin, and ascorbic acid showed that the infused strawberry produced by this technique was structurally and organoleptically similar to fresh strawberry, and visually similar to the intial fruits. Drying of infused fruits could extend their shelf life up to several months, while providing fruit products with superior nutritional qualities. Subjecting strawberry fruit extract to a simulated in vitro digestion of strawberry greatly affected the polyphenol composition and concentrations during different stages of digestion. The concentrations of most polyphenols increased during gastric digestion suggesting that the acidic environment of the stomach may help to release polyphenols that are bound to the strawberry matrix. Following incubation of the IN and the OUT fractions with colonic bacteria, the presence of urolithin B glucunoride in the IN fraction and the increase of ellagic acid deoxyhexoside in both the IN and OUT fractions after fermentation process, suggest that the polyphenols are catabolized into simple phenolic compounds in the colon. The remaining polyphenols as well as the catabolites in the gut, could potentially have a beneficial effect in enhancing colonial health. / Ministry of Higher Education Malaysia, Universiti Putra Malaysia