Fluorinated compounds are environmentally persistent and have been demonstrated to bioaccumulate and contribute to climate change. The focus of this work was to better understand the atmospheric chemistry of poly- and per-fluorinated compounds in order to appreciate their impacts on the environment. Several fluorinated compounds exist for which data on climate impacts do not exist. Radiative efficiencies (REs) and atmospheric lifetimes of two new long-lived greenhouse gases (LLGHGs) were determined using smog chamber techniques: perfluoropolyethers and perfluoroalkyl amines. Through this, it was observed that RE was not directly related to the number of carbon-fluorine bonds. A structure-activity relationship was created to allow the determination of RE solely from the chemical structure of the compound. Also, a novel method was developed to detect polyfluorinated LLGHGs in the atmosphere. Using carbotrap, thermal desorption and cryogenic extraction coupled to GC-MS, atmospheric measurements can be made for a number of previously undetected compounds. A perfluoroalkyl amine was detected in the atmosphere using this technique, which is the compound with the highest RE ever detected in the atmosphere. Perfluorocarboxylic acids (PFCAs) are water soluble and non-volatile, suggesting they are not susceptible to long-range transport. A hypothesis was derived to explain the ubiquitous distribution of these compounds involving atmospheric formation of PFCAs from volatile precursors. Using smog chamber techniques with offline analysis, perfluorobutenes and fluorotelomer iodides were shown to yield PFCAs from atmospheric oxidation. Dehydrofluorination of perfluorinated alcohols (PFOHs) is poorly understood in the mechanism of PFCA atmospheric formation. Using density functional techniques, overtone-induced photolysis was shown to lead to dehydrofluorination of PFOHs. In the presence of water, this mechanism could be a sink of PFOHs in the atmosphere. Confirmation of the importance of volatile precursors was derived from examination of snow from High Arctic ice caps. This provided the first empirical evidence of atmospheric deposition. Through the analytes observed, fluxes and temporal trends, it was concluded that atmospheric oxidation of volatile precursors is an important source of PFCAs to the Arctic.

2008 m. Lietuvos žemės ūkio universiteto Bandymų stotyje atlikus organinių azoto trąšų Provita įtakos ekologiškai auginamoms bulvėms tyrimus, nustatyta, kad tręšimas organinėmis azoto trąšomis Provita, bei organinių azoto trąšų Provita deriniais su Patenkali ir fosforitmilčiais esminiai padidino bulvių suminį ir prekinį derlingumą bei derliaus prekingumą. Patręšus Provita, Patenkali ir fosforitmilčiais bei Provita ir Patenkali esminiai padidėjo suminis ir prekinis bulvių derlingumas, lyginant su tręšimu Provita bei Provita ir fosforitmilčių trąšų deriniu. Bulves patręšus Provita, Provita ir Patenkali bei Provita, Patenkali ir fosforitmilčiais esminiai sumažėjo bulvėse krakmolo, lyginant su netręštomis bulvėmis. Patręšus bulves organinėmis azoto trąšomis Provita esminiai sumažėjo sausųjų medžiagų bulvių gumbuose, lyginant su netręštomis bulvėmis bei tręšimu Provita, kalio ir fosforo trąšų deriniais. Tręšiant organinėmis azoto trąšomis Provita gautas neigiamas azoto balansas. Tręšimas N60 organinių azoto trąšų norma, neužtikrino teigiamo azoto balanso dirvožemyje. / Research on the effect of organic nitric fertilizers Provita to organically cultivated potatoes performed in 2008 at the experimental station of Lithuanian University of Agriculture highlighted, that fertilization of potatoes with organic nitric fertilizers Provita, as well as combinations of organic nitric fertilizers Provita with Patenkali and phosphorite powder, significantly increased total and marketable harvest of potatoes, as well as merchantability of harvest. In case of fertilization with Provita, Patenkali and phosphorite powder, as well as Provita and Patenkali, total and marketable harvest of potatoes was significantly increased, compared with fertilization using Provita and the combination of Provita and phosphorite powder. After fertilization of potatoes with Provita, Provita and Patenkali as well as Provita, Patenkali and phosphorite powder, the concentration of starch in potatoes was significanlty lower, than in these never fertilized. After fertilization of potatoes with organic nitric fertilizers Provita, the concentration of dry matterial in potatoes was significantly decreased, compared to these never fertilized, or fertilized with Provita, combinations of kalium and phosphoric fertilizers. Fertilization of potatoes had no significant effect to the concentration of soluble dry matterial in potatoes. Fertilization with organic nitric fertilizers Provita resulted in negative nitric balance. Fertilization with standard volume of organic nitric fertilizers N... [to full text]

There is a need for chemical sensors for monitoring volatile organic compounds (VOCs) in air. Acute and chronic inhalation of toxic VOCs can cause adverse health effects in humans, so monitoring these analytes is important for ensuring that their concentrations are maintained below maximum permissible levels. Chemical sensors using polydimethylsiloxane (PDMS) to extract VOCs with partial selectivity, coupled with label-free optical detection methods based on refractive index, can overcome the limitations of conventional VOC detection methods. A variety of tunable and high refractive index PDMS materials were developed by incorporating a range of titanium and zirconium concentrations (2.5 – 30 mol % and 2.5 – 15 mol %, respectively) using a simple sol-gel synthesis and by incorporating a range of titanium concentrations (2.5 – 10 mol %) into naphthyl-functionalized PDMS. These materials ranged in refractive index from 1.4023 ± 0.0002 to 1.5663 ± 0.0001 at 635 nm and 1.3942 ± 0.0003 to 1.5510 ± 0.0007 at 1550 nm. The ability to use tunable refractive index PDMS films to differentiate between m-xylene and cyclohexane was demonstrated by monitoring changes in refractive index and thickness following absorption of these analytes using a refractometer at 1550 nm. The sensitivity of the refractive index response to an analyte using a particular PDMS film was dependent upon the difference between the refractive index of the analyte and film, as well as the film-air partition coefficient of the analyte. The detection limits for m-xylene and cyclohexane were 81 ppm and 4940 ppm, respectively, using PDMS-titanium-oxo nanocomposites with 5 and 10 mol % Ti, respectively. A simple planar waveguide sensor with an input grating coupler was developed to monitor changes in refractive index of the cladding through shifts in peak resonance wavelength. Using high refractive index PDMS materials as the waveguide core, we monitored changes in refractive index arising from absorption of VOCs into the grating. Here, the sensitivity of the waveguide response was dependent upon the difference in refractive index of the analyte and polymer, as well as the film-air partition coefficient of the analyte. The detection limits for m-xylene and cyclohexane were 1980 ppm and 18000 ppm, respectively. / Thesis (Master, Chemistry) -- Queen's University, 2013-08-24 11:45:57.642

Chemical detection, including analysis of gases and liquids, is a large field in environmental research and industry. It requires sensitive, rapid, and inexpensive chemical sensors. Many industrial materials such as coatings and adhesives readily absorb chemical analytes, which may result in changes of their chemical, mechanical, and optical properties. This uptake of volatile organic compounds either from the gas phase or from an aqueous solution into a thin film is frequently accompanied by a change in material refractive index and film thickness. While the undesired swelling of thin film coatings and their refractive index changes affect their use in harsh environments, the sensitivity of some polymers to solvent vapours can also be exploited for sensing applications. In this project, a method is reported for real-time monitoring of vapour uptake by simultaneous detection of the refractive index, n, and thickness, d, of thin transparent films with a precision of 10-4 for refractive index and 100 nm for thickness. The setup combines a total internal reflection refractometer with an interferometric imaging method. Two setups using 1550 nm and 635 nm measurement wavelengths were developed, with a detection rate of 1 second per measurement. Two processing methods using a fast Fourier transform algorithm to calculate n and d are applied to the experimental results and compared. Both methods could extract n and d simultaneously from each image captured by the refractometer. The results show that the setup is capable of monitoring film RI and thickness change in real-time. The partitioning of volatile organic compound vapours into polydimethylsiloxane (PDMS) and PDMS-polydiphenylsiloxane (PDPS) copolymers is described. The system is also suited for characterization of other solid and liquid films like SU-8 photoresist and crude oil. It shows great potential in commercial applications of thin film characterization. / Thesis (Master, Electrical & Computer Engineering) -- Queen's University, 2013-09-19 22:21:38.836

This study investigates the complex flow structure generated by riparian emergent vegetation along the edge of floodplain. Detailed velocity and boundary shear stress measurements were carried out for various arrangements of emergent rigid cylindric rods of 3 mm, 6 mm and 9 mm diameters and for three different rod densities. In addition, the impact of foliage on the flow field was assessed during a series of experiments where brushes were used instead of smooth rods. The results of these new experiments are first presented. In addition to the laboratory data, field data was obtained through Acoustic Doppler Current Profiler measurements for two flood events in a stretch of the river Rhône that can be approximated to a straight compound channel with vegetated banks. The analysis of the flow structure highlights the presence of strong secondary circulation and increased vorticity on the river banks. The rods on the edge of the floodplain increase significantly flow resistance, reducing velocity and decreasing boundary shear stress. Flow rate was seen to decrease with increasing vegetative density for all cases except when foliage was added. This suggests that an optimum threshold density, for which a smaller density would lead to an increased flow rate might exist. Wakes trailing downstream of the vegetation stem, planform coherent structures advected between the main channel and the floodplain, and eddying motion in the flow due to enhanced turbulence anisotropy are among the defining patterns observed in the studied compound channel flows with one line of emergent vegetation along the edge of the floodplain. The Shiono and Knight Method (SKM) was modified in order to account for the increased turbulence activity due to the rods. The drag force term was introduced in the same way as in the work of Rameshwaran and Shiono (2007). However, a new term was added to the transverse shear stress term in the form of an Elder formulation, incorporating a friction drag coefficient which can be derived from the experimental data. In this proposed version, the advection term was set to zero. Another version of the SKM, similar to Rameshwaran and Shiono (2007), was also tested with the addition of a local drag friction only applied in the rod region. The proposed SKM version without the advection term was favored as it can be more closely related to the experimental data and to physical processes. Finally, the capabilities of Telemac-2D were tested against the experimental data for various turbulence models. The Large Eddy Simulation turbulence model highlighted some unsteady flow patterns that were observed during experiments, while satisfactorily predicting the lateral velocity and boundary shear stress distributions.

Thermosonic ball bonding is a key technology in electrical interconnections between an integrated circuit and an external circuitry in microelectronics. Although this bonding process has been extensively utilised in electronics packaging industry, certain fundamental aspects behind all the practice are still not fully understood. This thesis is intended to address the existing knowledge gap in terms of bonding mechanisms and interfacial characteristics that are involved in thermosonic gold and copper ball bonding on aluminium pads. The research specifically targets the fine pitch interconnect applications where a thin metal wire of approximately 20 µm in diameter is commonly used. In thermosonic ball bonding process, a thin gold or copper ball formed at the end of a wire is attached to an aluminum pad through a combination of ultrasonic energy, pressure and heat, in order to initiate a complex solid-state reaction. In this research, the mechanisms of thermosonic ball bonding were elaborated by carefully examining interfacial characteristics as the results of the bonding process by utilising dual-beam focused ion beam and high resolution transmission electron microscopy, including the breakdown of the native alumina layer on Al pads, and formation of initial intermetallic compounds (IMCs). The effect of bonding parameters on these interfacial behaviours and bonding strength is also investigated in order to establish an inter-relationship between them. Interfacial evolution in both Au-Al and Cu-Al bonds during isothermal annealing in the temperature rage from 175ºC to 250ºC was investigated and compared. The results obtained demonstrated that the remnant alumina remains inside IMCs and moves towards the ball during annealing. The IMCs are formed preferentially in the peripheral and the central areas of the bonds during bonding and, moreover, they grow from the initially formed IMC particles. Growth kinetics of Cu-Al IMCs obey a parabolic growth law before the Al pad is completely consumed. The activation energies calculated for the growth of CuAl2, Cu9Al4 and the combination (CuAl2 + Cu9Al4) are 60.66 kJ/mol, 75.61 kJ/mol, and 65.83 kJ/mol, respectively. In Au-Al bonds, Au-Al IMC growth is controlled by diffusion only at the start of the annealing process. A t^0.2-0.3 growth law can be applied to the Au-Al IMC growth after the Al pad is depleted. The sequence of IMC phase transformation in both Au-Al and Cu-Al bonds were investigated. Voids in Au-Al bonds grow dramatically during annealing, however, only a few voids nucleate and grow very slowly in Cu-Al bonds. The mechanisms of void formation, including volumetric shrinkage, oxidation and metal diffusion were proposed and discussed.

Treatment of dichloromaleic anhydride and 1,8-diaminonaphthalene in either benzene or toluene under refluxing conditions gives low yields of the new heterocyclic compound 8,9-dichloropyrrolo[1,2-a]perimidin-10-one. This product has been isolated and characterized in solution by NMR, IR, and UV/vis spectroscopies, and the solid-state structure of 8,9-dichloropyrrolo[1,2-a]perimidin-10-one has been established by X-ray crystallography. The nature of the HOMO and LUMO levels of 8,9-dichloropyrrolo[1,2-a]perimidin-10-one has been studied by extended Hückel molecular orbital calculations.

Volatile organic compounds (VOCs) are organic chemicals typically characterized as having low molecular weight, low solubility in water, and high vapor pressure. Consequently, they readily evaporate from liquid to the gaseous phase at standard temperature and pressure. VOCs are produced by many microorganisms as a result of both uninduced and induced metabolic pathways. Volatile-based microbial inhibition in environments such as soil is well founded, with numerous antimicrobial VOCs and formulations having been identified. Inhibitory VOCs are of particular interest as microbial control agents, as low concentrations of gaseous VOCs have been observed to elicit significant antimicrobial effects. It is believed that this contact-independent antagonism may present unique advantages over traditional microbial control methods, particularly where contact-dependent treatment methods are either impractical or inconvenient. This method may be of particular benefit for managing infections where disease may become pervasive in the population, such as with white-nose syndrome (WNS) among bats. A list of potential antifungal compounds and formulations was compiled by referencing the scientific literature. Screening of compounds and formulations was conducted through toxicity analyses and antimicrobial susceptibility testing for the in vitro ability of VOCs and formulations to inhibit growth of select pathogenic fungi. A dispersal system was developed that entailed electrical circuit and software engineering as well as quantitative analysis to validate consistent and accurate dispersal of potential treatment compounds and formulations. Successful completion of these goals culminated in exposure trials involving live bats to determine any significant toxicological effects. Ex and in situ treatment trials were conducted to determine efficacy of promoting the reduction of disease severity and increasing survivorship of infected bat populations. The identification of volatile-based inhibitory compounds, in conjunction with a novel method for accurate and automated delivery, could prove a promising treatment and prophylactic in combatting microbial pathogenesis and contamination.

The design, fabrication and performance of an Extraordinary Magnetoresistance (EMR) and a Vertical Mesa Hall Sensor (VMHS) are studied. EMR devices have been fabricated from a 2DEG InAs/GaSb structures which exhibit a low carrier density and high mobility that achieve the best performance. The general electrical magneto-transport properties are given. The experiments investigate mainly different metallic patterns, which are Rectangular, Triangular and Tip pattern between 4-300 K. Probe configurations and the enhancement of relative size of metallic patterns are described. EMR effect is due to current deflection around the metal-semiconductor interface. The results are metallic pattern dependent. Using finite element analysis, good agreement between experimental and theoretical results was found. The best performance sensor is a symmetrical metallic Tip pattern. It is enhanced by the length of the Tip’s point and the large metallic area. This pattern when combines with an asymmetrical probe configuration, exhibits the highest EMR of 900% at –0.275T measured by inner probes and the best sensitivity of 54Ω/T at room temperature. The second study presents in-plane Hall effect sensors made from InSb. A simple device geometry has been used in which current flows in a plane perpendicular to the device surface. Device sensitivity depends on its geometry and a series of different contacts are used to investigate the geometry of the current flow distribution. The structures produced are only sensitive to the presence of one in-plane field component, and they also demonstrate good angular selectivity. Multi-electrodes were used to investigate biasing current from both mesa and substrate condition. We are able to examine the Hall voltage as a function of contact positions and also to create multiple VMHS. Offset reduction of devices has been achieved by moving the ground contacts to re-balance the current distribution under the mesa surface.

Fundamental studies on thermodynamic properties of vanadium-containing oxides systems are essential to understand practical vanadium metallurgical process. The CALPHAD technique is here applied to the thermodynamic modelling of the V-O, Ca-V-O and Ti-V-O systems. The compound energy formalism is used for all the solution phases. All optimization processes and calculations are performed using the Thermo-Calc software package. The present work attempts to develop a self-consistent thermodynamic database of all phases in the studied systems. The obtained datasets can be used to calculate thermodynamic properties, stable as well as metastable phase equilibria and driving forces for oxidation etc. Steelmaking slag is an important secondary source for vanadium extraction. The phase relationships and vanadium distribution in the CaO-SiO2-MgO-V2O3-Al2O3 synthetic slags, whose compositions were chosen based on the relevance to the steel producers, are also studied. Phase equilibria in the temperature range of 1773 to 1823 K at oxygen partial pressure of 10-10 bar and 0.21 bar were characterized. An investigation of the volatilization of vanadium oxide was also carried out in the present work. Isothermal evaporation of vanadium pentoxide in the temperature range between 1723 and 1873 K was investigated by Thermogravimetric Analysis under different oxygen partial pressures, viz. oxygen, air or CO2. The Arrhenius activation energy for the evaporation reaction in various atmospheres was calculated from the experimental results. A mathematical model was developed to describe the kinetics of the evaporation process. Evaporation coefficients and enthalpies in various atmospheres were also estimated. The present results may have some implications in recovering vanadium from different vanadium-bearing sources. / <p>QC 20161202</p>