The aim of this study was to investigate the utility of direct analysis in real time quadrupole time-of-flight mass spectrometry and gas chromatography quadrupole time-of-flight mass spectrometry in the analysis of 162 different synthetic cannabinoids. Direct analysis in real time quadrupole time-of-flight mass spectrometry is shown to be a rapid and accurate analytical method for synthetic cannabinoids. Spectra can be generated with less than 1.5 ng of the drug in under a minute and be successfully searched against previously generated ESI-QTOF libraries in most cases (118/130 drugs tested) as well as can also be applied to the identification of synthetic cannabinoids in a mixture. Gas chromatography quadrupole time-of-flight mass spectrometry, while requiring a much longer analysis time, is shown to accurately distinguish all but 19 compounds (140/159). These two instruments have proven to be viable alternatives in synthetic cannabinoid analysis and will greatly benefit forensic laboratories.

Mangos (Mangifera indica L.) are tropical/subtropical fruits belonging to the plant family Anacardiaceae. Anthracnose is the most deleterious disease of mango both in the field and during postharvest handling. It is most commonly caused by the Colletotrichum gloeosporioides complex. Mangiferin, a xanthanoid compound found in at least twelve plant families worldwide (Luo et al., 2012), is present in large amounts of the leaves and edible mangos. Even though this compound plays a pivotal role in the plant’s defense against biotic and abiotic stressors, no correlations been made between the compound and mango anthracnose resistance. Mangos were collected, grouped according to their countries of origin, and evaluated for their mangiferin concentrations at four different stages of development. Extracts of interest were then tested against different strains of C. gloeosporioides. The results demonstrated that mangiferin concentrations are significantly different at different stages in fruit development. The antifungal assays were inconclusive.

Human scent has been the focal point of diverse scientific interests and research initiatives for the past several years. The knowledge gained about its composition has favored the advancement of multiple disciplines, and promoted the development of a wide variety of applications. Among these applications is the use of human scent as a resource for Forensic investigations, where scent profiles are often used as evidence to associate individuals to the scene of a crime. The characteristic nature of individual human scent has enabled this type of evidence to be used as a biometric tool for the differentiation of subjects. Nevertheless, the present study discusses a new perspective towards human scent's role and application in Forensic investigations. The foundation of this new perspective consists of employing human scent’s biometric quality to classify individuals using common traits. In this research study, underarm and hand odor samples were collected from Caucasian, Hispanic and East Asian individuals, of both genders. Subjects were also organized into 3 different age groups: 18-30, 35-50 and 55+ years. Headspace Solid Phase Micro-extraction Gas Chromatography Mass Spectrometry (HS-SPME-GC-MS) was used to create individual scent profiles for the evaluation of subject classification by age, gender and race/ethnicity. Individual classification was assessed through the identification of qualitative and quantitative patterns in the volatile organic compound (VOC) constituents that characterize human scent. Principal Component and Linear Discriminant analyses of the collected scent profiles, led to the identification and validation of characteristic VOC marker combinations for age, gender and race/ethnicity. Statistical analysis facilitated group classification and differentiation on the basis of these traits. Moreover, this study also evaluated the use of solvent extraction as a complementary technique to HS-SPME for human scent analysis. Findings from this assessment revealed that the simultaneous consideration of data from both extraction techniques favors an enhancement of the classification of subjects by means of human scent. The discoveries achieved in this study represent a significant step for human scent as a forensic tool. The outcome of this research has cleared a new path for further human scent investigation, and highlighted its further relevance to forensic applications.

The goal of this project was to develop a rapid separation and detection method for analyzing organic compounds in smokeless powders and then test its applicability on gunshot residue (GSR) samples. In this project, a total of 20 common smokeless powder additives and their decomposition products were separated by ultra performance liquid chromatography (UPLC) and confirmed by tandem mass spectrometry (MS/MS) using multiple reaction monitoring mode (MRM). Some of the targeted compounds included diphenylamines, centralites, nitrotoluenes, nitroglycerin, and various phthalates. The compounds were ionized in the MS source using simultaneous positive and negative electrospray ionization (ESI) with negative atmospheric pressure chemical ionization (APCI) in order to detect all compounds in a single analysis. The developed UPLC/MS/MS method was applied to commercially available smokeless powders and gunshot residue samples recovered from the hands of shooters, spent cartridges, and smokeless powder retrieved from unfired cartridges. Distinct compositions were identified for smokeless powders from different manufacturers and from separate manufacturing lots. The procedure also produced specific chemical profiles when tested on gunshot residues from different manufacturers. Overall, this thesis represents the development of a rapid and reproducible procedure capable of simultaneously detecting the widest possible range of components present in organic gunshot residue.

While the spin trapping properties of thiols have been investigated through EPR analysis and kinetics studies, few groups have studied these properties using strictly computational methods. In particular, α-lipoic acid (ALA) and its reduced form, dihydrolipoic acid (DHLA), one of the strongest endogenously produced antioxidants, show potential for being effective, naturally occurring spin traps for the trapping of reactive oxygen species. This research covers electronic structure calculations of ALA, DHLA, and their corresponding hydroxyl radical spin adducts, performed at the cc-pVDZ/B3LYP/DFT level of theory. The effects on DHLA introduced by other radicals such as ·OOH, ·OCH3, and ·OOCH3 are reported. Explicit solvation was carried out using open-source molecular packing software and was studied using MOPAC PM6 semi-empirical geometry optimizations. Complete Basis Set (CBS) limit extrapolations were performed using cc-pVXZ (X = D, T, Q) Dunning basis sets under the DFT/B3LYP level of theory, and results are compared to the literature.

Plastic pollution is one of if not the biggest threat against earth’s ecosystems. Almost 400 million tons of plastic is produced every year and most of it is discarded outside of the recycling systems. Marine ecosystems are extra exposed due to microplastics which are plastic smaller than 5 mm. The most common type of plastic is PET. Plastic in general is very chemically stable and hard to degrade but scientists have found a bacterium named I.sakaiensis that can degrade PET with a two-enzyme system called PETase and MHETase. Due to being exo-enzymes, they have to be secreted to function, the thermostability of these enzymes are very low so most research has been focused on increasing the thermal stability with its enzyme activity. This report focuses on what structures are important for the PET degrading ability of MHETas and PETas and how they can be applied to cleaning marine ecosystems. A key to solving environmental issues is creating environmentally aware students through the education system. Studies about Context based education have indicated that it sparks motivation and interest in students and the lessons seem more relevant. This report is also about how context-based education can be used to create an environmental perspective in secondary education.

The state-of-the-art tools for machining metals are primarily based on a metal-ceramic composite(WC-Co) coated with different combinations of carbide, nitride and oxide coatings. Combinations of these coating materials are optimized to withstand specific wear conditions. Oxide coatings are especially desired because of their possible high hot hardness, chemical inertness with respect to the workpiece, and their low friction. This thesis deals with process and coating characterization of new oxide coatings deposited by physical vapor deposition (PVD) techniques, focusing on the Cr-Zr-O and Al-Cr-Si-O systems. The thermal stability of α-Cr0.28Zr0.10O0.61 deposited by reactive radio frequency (RF)-magnetron sputtering at 500 °C was investigated after annealing up to 870 °C. The annealed samples showed transformation of α-(Cr,Zr)2O3 and amorphous ZrOx-rich areas into tetragonal ZrO2 and bcc Cr. The instability of the α-(Cr,Zr)2O3 is surprising and possibly related to the annealing being done under vacuum, facilitating the loss of oxygen. The stabilization of the room temperature metastable tetragonal ZrO2 phase, due to surface energy effects, may prove to be useful for metal cutting applications. The observed phase segregation of α-(Cr,Zr)2O3 and formation of tetragonal ZrO2 with corresponding increase in hardness for this pseudo-binary oxide system also opens up design routes for pseudo-binary oxides with tunable microstructural and mechanical properties. The inherent difficulties of depositing insulating oxide films with PVD, demanding a closed circuit, makes the investigation of process stability an important part of this research. In this context, we investigated the influence of adding small amount of Si in Al-Cr cathode on plasma characteristics ,process parameters, and coating properties. Si was chosen here due to a previous study showing improved erosion behavior of Al-Cr-Si over pure Al-Cr cathode without Si incorporation in the coating. This work shows small improvements in cathode erosion and process stability (lower pressure and cathode voltage) when introducing 5 at % Si in the Al70Cr30-cathode. This also led to fewer droplets at low cathode current and intermediate O2 flow. A larger positive effect on cathode erosion was observed with respect to cleaning the cathode from oxide contamination by increasing cathode current with 50%. However, higher cathode current also resulted in increased amount of droplets in the coating which is undesirable. Through plasma analysis the presence of volatile SiO species could be confirmed but the loss of Si through volatile SiO species was negligible, since the coating composition matched the cathode composition. The positive effect of added Si on the process stability at the cathode surface should be weighed against Si incorporation in the coating. This incorporation may or may not be beneficial for the final application since literature states that Si promotes the metastable γ-phase over the thermodynamically stable α-phase of pure Al2O3, contrary to the effect of Cr, which stabilizes the α-phase.

Modeling of the nitrogen cycling in the sediments of the Baltic Sea is the major objective of thepresent study. A model of the nitrogen cycling in the sediment of the Western Gotland Basinwas developed. The model simulates the sedimentary biogeochemical processes such asdecomposition of the organic detritus and transformation of nitrogen species in the sediment.The development of the model is based on the methods and approaches implemented in themodel of the freshwater Haringvliet Lake, Netherland. The sediments of Haringvliet and the Baltic Sea were examined in terms of the interactions andcontrols of biogeochemistry. Both systems are eutrophied. This results in a high sedimentationrate of organic matter and creates the same chemical and physical conditions to theirsediments. However, the sedimentation rate and decomposition of organic detritus is higherand nitrification and denitrification is lower in Haringvliet lake system compared to the BalticSea. The results of the model tests show that profiles of the chemical compounds and rates of theprocesses are in good agreement with the observations made in different areas of the BalticSea. The model can be used for simulation of the sediment processes when there is a constantinput of organic matter. The model can also reproduce the behavior of the sediment whensome of the process parameters and conditions are changed. A comparison of the rates of the biogeochemical processes predicted by model and thosemeasured in the different basins of the Baltic Sea was performed. The rates of decompositionof organic detritus, denitrification and nitrification were in agreement with the field data. Basedon the results of the model the nitrogen removal in the sediment was calculated and it wasfound that 26-32% of total nitrogen entering the sediment is removed by denitrification. / <p>www.ima.kth.se</p>

The increasing spread of antibiotic resistance among bacteria poses a major threat to the public health. There is an urge for the development of innovative formulations of existing and new antibiotics. One area of interest is in wound care, where two interesting antimicrobials are the conventional antibiotic amoxicillin and the antimicrobial peptide AP114. The objective of this work was to systemically evaluate topical gel formulations of these APIs by following a Quality by Design approach. A short excipient compatibility study was performed and the thickening agents poloxamer 407 and HPMC were chosen to be included in the following Design of Experiment (DoE) study of formulation composition and storage climate. The DoE set up was generated by the software MODDE Pro® and a short stability study of four weeks was performed, including analysis of the apparent pH, rheology stability, appearance, BCA assay, UV-Vis and FTIR spectroscopy and Franz cell diffusion. The results showed that AP114 formulations stored at 2-8˚C with poloxamer 407 should be with buffer pH 5-6 and 5-15 wt% organic phase to maximize stability, while HPMC based AP114 gels should be with buffer pH 6-8 and 10-40 wt% organic phase. Poloxamer 407 was not preferrable for amoxicillin formulations. The optimal HPMC based amoxicillin formulations included the storage temperature 25˚C, a buffer pH 7-8 and 40-60 wt% organic phase. HPMC based amoxicillin gels stored at 2-8˚C should be composed with buffer pH 6-8 and 10-40 wt% organic phase.

Eastern hemlock (Tsuga canadensis) is in decline because of infestation by the invasive hemlock woolly adelgid (Adelges tsugae; ‘HWA’) and, to a lesser extent, the elongate hemlock scale (Fiorinia externa; ‘EHS’). Many conifers respond to insect herbivory by inducing oleoresin-based defenses, however it is unknown whether eastern hemlock is capable of this inducible response. We conducted a plantation setting study of artificially infested saplings to determine if feeding by HWA or EHS induces changes in the tree’s volatile chemistry. The induced changes in volatiles we found were unlike the terpenoid-based defenses of related conifers. Only HWA feeding elevated methyl salicylate, a plant signal for systemic acquired resistance, and benzyl alcohol, a known antimicrobial and aphid deterrent. The influence of environmental conditions and tree life-stage on hemlock volatile chemistry, potentially important factors for wild hemlock populations, is unknown. We investigated whether mature and immature forest trees respond to HWA infestation with the same patterns of volatile production as plantation saplings in full sun and amended soils. HWA induced volatile changes comparable to those of plantation saplings, with many-fold benzenoid increases and no terpenoid-based resinosis. Nearly all volatiles were substantially more abundant in forest than plantation trees, suggesting the effect of site conditions should be addressed in investigations of mechanisms operative in HWA-resistant biotypes of eastern hemlock. Our findings represent the first important step toward understanding the influence of inducible phytochemical responses on hemlock susceptibility to exotic pests, and highlight the possibility of salicylic acid-dependent biosynthetic activity in this gymnosperm system.