Calcium bioavailability was investigated using isotopic intestinal absorption, and balance study techniques with bone mineralization and biomechanics as endpoint determinants of calcium utilization. In experiment 1, lactose enhancement of paracellular calcium absorption was confirmed, and it was suggested that a critical luminal concentration of lactose was necessary for its action. Despite the enhanced intestinal absorption of calcium in animals fed the 50% lactose containing diet, bone mineralization was not different from controls; and further, a decrease in bone strength of these animals was found to be secondary to nutrient malabsorption. In this study, there was no evidence to indicate a difference in the bioavailability of calcium from milk (colloidal) or yogurt (ionized) sources. In experiment 2, the absorption of calcium from the ileum was significantly enhanced in[formula omitted] normal Wistar rats fed milk protein diets containing casein as compared to whey and soy protein diets. The increase in absorbed calcium was shown to have little physiological significance in bone mineralization and biomechanics when animals were fed a diet adequate in dietary calcium. In experiment 3, paracellular calcium absorption was similar between genetically spontaneously hypertensive (SHR) and normotensive control Wistar-Kyoto (WKY) rats, suggesting that differences in calcium metabolism between these two strains was not due to differences in ileal calcium transport. The effect of casein and soy protein diets containing high (2.0%), adequate (0.5%) and low (0.05%) levels of calcium, respectively on calcium bioavailability and subsequent utilization was determined in SHR and WKY animals. Ileal calcium absorption was greater in casein fed animals than those fed soy at the adequate and low levels of calcium. Femur calcification was enhanced by casein diets at the high and medium levels of dietary calcium only. Femur biomechanics were not influenced by dietary protein source, but were however, adversely affected by the low dietary calcium level. In experiment 4, the effect of dietary fortification with casein phosphopeptides (CPP) was investigated in casein and soy fed SHR animals. CPP added to casein and soy protein diets appeared to result in a greater ileal absorption of calcium. This increase in calcium bioavailability from the casein diet had little effect however, on bone mineralization and biomechanical strength, due to the excretion of excess absorbed calcium. In experiment 5, severe thermal processing of dietary proteins was shown to reduce in vitro digestibility. Animals fed heat denatured casein and soy diets exhibited reduced intestinal calcium absorption, calcium balance as well as bone mineralization and biomechanics. These effects were influenced by the nutrient malabsorption experienced by these animals. In experiment 6, a low (6%) protein, low phosphorus diet resulted in decreased food intake and animal growth. However, ileal calcium absorption (% dose) was similar between 6% and 20% protein fed animals. A low level of dietary protein influenced calcium balance and utilization for bone mineralization and biomechanical strength. These results indicate that paracellular calcium absorption may not necessarily equate with those obtained from a calcium balance study. Notwithstanding, calcium bioavailability from the ileum was shown to be enhanced in animals fed casein, which was likely due to the production of bioactive peptides (CPP) that are involved in sequestering calcium and retaining it in a soluble form. By reducing protein digestibility with heat denaturation, this effect was lost. Reducing the protein content in the diet however, did not reduce the enhancement of calcium bioavailability observed in casein fed animals. Finally, bone mineralization and biomechanical parameters were shown to be sensitive indicators of calcium utilization from diets that varied in calcium content or bioavailability of this mineral. / Land and Food Systems, Faculty of / Graduate

Thesis (M. Sc. (Chemistry)) -- University of Limpopo, 2016 / In this study, the use of synthetic hierarchical MFI zeolites as supports for palladium hydrocracking catalysts was investigated. Hierarchical zeolites were synthesised through two different routes, viz., (i) the indirect and (ii) direct routes. In (i) pristine ZSM-5 zeolites with different SiO2/Al2O3 ratios (SARs) were synthesised hydrothermally using tetrapropylammonium bromide as structure-directing agent (SDA), followed by a brief desilication of its calcined form in 0.2 M NaOH solution at 65 °C for 0.5 h. Procedure (ii) involved prior synthesis of three polyquaternary ammonium surfactants (containing 2 - 4 ammonium centres), followed by their use as SDAs in the hydrothermal synthesis of hierarchical MFI zeolites. The resulting materials were characterised by XRD, FT-IR, SEM and N2 adsorption isotherms (including BET surface area measurements). Successful synthesis of different classes of the hierarchical MFI zeolites was confirmed by XRD patterns, while successful synthesis of polyquaternary ammonium surfactants was confirmed by both their 1H NMR spectra and their ability to direct the MFI structure. On the basis of IR, peak intensities in the OH region between 3500 and 3800 cm-1, the surfactant-templated zeolites were inferred to be more acidic than zeolites prepared through the desilication route. Significant changes in crystal morphology were observed upon desilication of ZSM-5(50), while the ZSM-5(77) and ZSM-5(100) retained their agglomerated morphology upon a similar treatment. The micrograph pristine of ZSM-5(50) showed a predominant morphology of large and small spheroids, together with some ill-defined cubic shapes. After desilication, the zeolite did not retain the original morphology entirely, showing hexagonal prismatic crystals with twinning occurring in other areas and large spheroids “hatching” to reveal their contents upon treatment. Desilicated zeolites exhibited improved textural properties (i.e., increased SBET, pore volumes and pore diameters) and minor structural readjustments compared to their pristine counterparts. Textural properties of surfactant-templated zeolites were superior to those of desilicated zeolites, and improved with increasing number of quaternary ammonium centres in the surfactant template. These materials were generally more crystalline than the conventional zeolites. Hydrocracking catalysts containing 0.9 wt.% Pd loading on different MFI supports were prepared by the incipient wetness impregnation method. The n- v hexadecane hydrocracking conditions used were typical of LTFT process (i.e., Temperature = 215 - 310 °C, WHSV = 1 h-1, Pressure = 20 bar, in addition to the H2 /n-C16 ratio of 10). The catalytic activity in all catalyst systems increased with increasing reactor temperature and displayed C4/C12 ratios ≠ 1, evidence of the occurrence of secondary cracking (i.e., a non-ideal hydrocracking behaviour). This was also supported by the shapes of their product distribution profiles, which showed dominant C3 - C7 n-paraffins. Co-feeding H2O with n-C16 into the reactor was found to be detrimental to n-C16 conversion, but promoted the selectivity to iso-paraffins in the product spectrum. Simultaneous introduction of CO and H2O aggravated secondary cracking. Amongst the pristine ZSM-5 zeolite-based catalysts, Pd/P-ZSM-5(77) showed the best catalytic performance. Upon desilication, the performance order changed to favour Pd/D-ZSM-5(50*). For the surfactant-templated supports, Pd/HSZ(N4) showed the most superior hydrocracking performance. Comparison of catalytic activities of the best performing catalyst systems derived from the conventional and surfactant-templated zeolites in the hydrocracking of n-hexadecane, follow the order Pd/D-ZSM-5(50*) > Pd/P-ZSM-5(77) > Pd/HSZ(N4). That is, the pristine and desilicated zeolite-based catalysts performed better than their surfactant-templated zeolite-based counterparts. Therefore, the post-synthesis generation of mesoporosity through desilicating ZSM-5 with a SAR of 50 has proven beneficial for the resulting catalyst system. One of the possible reasons for the relatively inferior hydrocracking performance of the Pd/HSZ(N4) catalyst may be the aluminium-richness of the support (SAR = 40) compared to the conventional ZSM-5-based supports. In summary, catalysts Pd/D-ZSM-5(50*), Pd/P-ZSM-5(77) and Pd/HSZ(N4) are promising for diesel-selective catalysis and need further refinements and exploration.

The current period of human history is considered to be the plastics age due to its versatile characteristics, especially the lightweight, durability and low production cost. Plastics can be manufactured to suit multifarious functions, for example, for personal care products, food/drink storage and medical purposes. Thus, the use of plastics is unavoidable now, finally contributing to the severe pollution worldwide. In 2018 alone, the global plastics production amount has exceeded 359 million tons, around 10% of which ultimately become waste persisting in the environment. When plastic wastes exposed to the sun's radiation, climate change and mechanic abrasion, degradation and fragmentation may occur. Once the size of the fragmentation products is less than 5 mm, they are commonly defined as microplastics (MPs) by the National Oceanographic and Atmospheric Administration. Currently, microplastics have been regarded as the most pervasive environmental pollution problems, not only because of their physical hazards but also due to their interactions with other pollutants in the environment. Pollution can be attributed by the release of additives from MPs, as well as the MPs with adsorbed toxic contaminants. Moreover, MPs additives together with adsorbed chemicals can be easily uptaken by animals, which may cause further propagated effects on the ambient ecosystem. Through the bioaccumulation and biomagnification effect, MPs can even be accumulated in the organisms from different trophic levels and cause serious impacts on aquatic ecology and human health. Despite growing number of evidences that have confirmed the presence and consequential effects of microplastics, researches on microplastic pollution are still lacking. Investigations on occurrence, determination and environmental fate of MPs in aquatic systems are clearly needed. Therefore, the major objective of this study is to elucidate the distribution of MPs in natural environment, to develop novel determination methods to characterize the micro-(nano-)plastics (MNPs), and to study the interactions of MPs with other contaminants in different conditions, as well as their consequential fate in different matrices (e.g. freshwater, cold-blooded intestine, and warm-blooded intestine). The spatial-temporal distribution of the MPs along the Maozhou River was investigated for both the surface water and sediments from 17 sites. Results showed that MPs were widely and unevenly distributed along the river. The MP abundances in dry season ranged from 4.0 ± 1.0 to 25.5 ± 3.5 items·L-1 in water and 35 ± 15 to 560 ± 70 item·kg-1 in sediments, which were relatively higher than those observed in wet season (water: 3.5 ± 1.0 to 10.5 ± 2.5 items·L-1; sediments: 25 ± 5 to 360 ± 90 item·kg-1; p value < 0.05). The dominant types of MPs were identified as: polyethylene (PE, water: 45.0%, sediments: 42.0%), polypropylene (PP, water and sediments: 12.5%), polystyrene (PS, water: 34.5%; sediments 14.5%) and polyvinyl chloride (PVC, water: 2.0%; sediments: 15%). Moreover, metals such as Al, Si, Ca were discovered on the rough surface of the MPs, indicating the interactions between the MPs and the aquatic environment. After obtaining the occurrence of the MPs in the aquatic systems, we proposed an accurate method for MNPs identification and quantification with the employment of the matrix-assisted laser desorption/ionization-time of flight mass spectrometry (MALDI-TOF MS). By optimizing the conditions (e.g. the laser energy, matrix, analyte, cationization agent and their ratio), the peaks of PS and polyethylene terephthalate (PET) were successfully identified. A quantitative correlation was built between the normalized signal intensity and ln[polymer concentration], with a correlation coefficient above 0.96 for low-molecular-weight (LM-) polymers and 0.98 for high-molecular-weight (HM-) polymers. Furthermore, two types of environmental MPs samples were prepared, including the particles of an aviation cup as the fresh plastics and the aged MPs extracted from river sediment. By using MALDI-TOF MS, the PS-related micro-(nano-)plastics (in both aviation cup and sediment) consisted of C8H8 and C16H16O oligomers, while the PET-related MNPs (only found in sediment) were identified with compositions of C10H8O4 and C12H12O4. The contents of PS and PET MNPs in sediment were quantified as 8.56 ± 0.04 and 28.71 ± 0.20 mg·kg-1, respectively. Also, the interaction between MPs and bisphenols was investigated. PVC was selected as the representative target because it is comparatively easy to decompose into MPs with the release of additives, especially the bisphenols. The released bisphenols may then be readsorbed by the PVC MPs and cause consequential pollution to the ecosystem. To elaborate on the interactions mechanism, a systematic study was carried out to determine the adsorption mechanisms of five bisphenol analogues (BPA, BPS, BPF, BPB, and BPAF) on PVC MPs. The equilibrium adsorption numbers of the bisphenols on PVC MPs are 0.19 ± 0.02 mg/g (BPA), 0.15 ± 0.01 mg/g (BPS), 0.16 ± 0.01 mg/g (BPF), 0.22 ± 0.01 (BPB), 0.24 ± 0.02 mg/g (BPAF), respectively. Intraparticle diffusion modeling (kinetics) divided the adsorption process into three stages: external mass transport, intraparticle diffusion and dynamic equilibrium. The isotherm results showed a better fit of the adsorption to the Freundlich model. Furthermore, the adsorption mechanisms of the five bisphenol analogues were explored intensively, with respect to hydrophobic interaction, electrostatic force and noncovalent bonds. Besides the adsorption process, the transfer and release behaviors of contaminated MPs are of critically importance in the exploration of their role as culprits and/or vectors for the aforementioned toxicity. Therefore, experiments were performed to examine desorption behaviors and cytotoxicity performance of contaminated MPs in aquatic surroundings and intestinal environment after ingestion by organisms (cold-/warm-blooded). The kinetic study showed that the rate of desorption for bisphenols could be enhanced threefold under simulated warm intestinal conditions. The Freundlich isotherms indicated multiple-layer desorption of the bisphenols on the heterogeneous surfaces of PVC MPs. Hysteresis was detected in the adsorption/desorption of bisphenols in a water environment, but no adsorption/desorption hysteresis was observed in the simulated intestinal conditions of warm-blooded organisms. Due to the enhanced bioaccessibility, the desorption results implied that the environmental risk of contaminated PVC MPs might be significantly increased after ingestion at a high bisphenols dosage. Although with different IC50, the five bisphenols released under the intestinal conditions of warm-blooded organisms can cause higher proliferation reduction in fish and human cell lines than the bisphenols released in water. In summary, this study elucidated the spatial-temporal distribution behaviors of MPs, developed effective determination methods for MNPs revealed the interactions mechanisms of MPs with other contaminants, and explored their consequential fate in different environments. The obtained results are helpful of better understanding on the land-based input of MPs from the intensively affected inland waters, realizing the role of microplastics as both source and carrier for emerging organic pollutants, and providing a novel alternative for MPs determination in future studies.

Medan Flow är ett njutbart medvetandetillstånd där ens agerande tycks ske automatiskt så definieras Grit som uthållighet och passion i strävan mot ett långsiktigt mål. Studien undersökte om det fanns ett positivt samband mellan generell Flow och Grit samt mellan arbetsrelaterad Flow och Grit. Arbetsrelaterad Flow definieras av absorption, arbetsglädje och inre motivation. 75 yrkesverksamma personer, varav 50 coacher, deltog i studien genom att svara på en enkät som publicerades på sociala medier. Enkäten utgjordes av mätinstrumenten Flow Short Scale, WOLF (arbetsrelaterad Flow) samt Grit Scale. Materialet undersöktes med korrelationer och regressionsanalyser. Flow och absorption korrelerade positivt med både uthållighet och passion och arbetsglädje visade ett positivt samband med uthållighet. Flow hade det starkaste sambandet med uthållighet medan absorption visade den starkaste relationen till passion. En framtida studie skulle genom en intervention kunna undersöka hur Grit påverkas om förutsättningarna för Flow påverkas.

This diploma work deals with the topic application of cogeneration and trigeneration for outlying buildings supplying. The first part this work containes description of technology and methods of realization. In this part there is also described absorption circulation. The second part this work targets concepts energy independedce the building, that has concrete energy consumption, including economic analysis.

Laser-based sensors can be used as non-invasive monitoring tools to measure parts per billion (ppb) levels of trace gases. Ammonia sensors are useful for applications in environmental pollutant monitoring, atmospheric and combustion kinetic studies, and medical diagnostics. This sensor was specifically designed to measure ammonia in exhaled breath to be used as a medical diagnostic and monitoring tool, however, it can also be extended for use in other applications. Although ammonia is a naturally occurring species in exhaled breath, abnormally elevated levels can be an indication of adverse medical conditions. Laser-based breath diagnostics have many benefits since they are cost effective, non-invasive, painless, real time monitors. They have the potential to improve the quality of medical care by replacing currently used blood tests and providing immediate feedback to physicians. This sensor utilizes a Quantum Cascade Laser and Wavelength Modulation Spectroscopy with second harmonic normalized by first harmonic detection in a 76 m multi-pass absorption cell to measure ppb levels of ammonia with improved sensitivity over previous sensors. Initial measurements to determine the ammonia absorption line parameters were performed using direct absorption spectroscopy. This is the first experimental study of the ammonia absorption line transitions near 1103.46 cm-1 with absorption spectroscopy. The linestrengths were measured with uncertainties less than 10%. The collisional broadening coefficients for each of the ammonia lines with nitrogen, oxygen, water vapor, and carbon dioxide were also measured, many of which had uncertainties less than 5%. The sensor was characterized to show a detectability limit of 10 ppb with an uncertainty of less than 5% at typical breath ammonia levels. Initial breath test results showed that some of the patients with chronic kidney disease had elevated ammonia levels while others had ammonia levels in the same range as expected for healthy patients. For all of the patients the breath ammonia level decreased during dialysis but the percent decrease varied considerably for each patient. The sensor has demonstrated improved sensitivity and has been applied to measure ppb levels of ammonia in exhaled breath. Further tests have been designed to improve the sensor and continue to investigate the medical applications.

Strahlwäscher sind durch Ihre Fluiddynamik gekennzeichnet, was eine detaillierte Simulation erschwert. Es konnte gezeigt werden, dass die in der Literatur üblichen empirischen Ansätze aufgrund Ihrer Vereinfachungen den Prozess nur ungenau beschreiben und daher nur für eingeschränkte Bedingungen gelten. Die für die Auslegung von Strahlwäschern relevanten Größen, die erreichbare Pressung und die Stoffaustauschfläche, für beliebige Betriebspunkte wurden in dieser Arbeit durch eine dreidimensionale CFD Simulation berechnet. Es wurden entsprechende Unterprogramme implementiert, um den Stoffübergang im Strahlwäscher zu berechnen. Die chemische Absorption wurde sowohl für die Tropfen als auch für den sich ausbildenden Wandfilm berechnet und als Senke an die Gasphase zurückgegeben. Die Tropfengröße und der Sprühwinkel haben einen essentiellen Einfluss auf die Strömungsverhältnisse im Strahlwäscher. Diese, im wesentlichen von der Düse abhängigen Größen, wurden experimentell mit der Phasen-Doppler-Anemometrie bestimmt. Die Simulationsergebnisse wurden durch Versuche in einer Technikumsanlage verifiziert.

The impulse technique is progressively being developed for determining the steady state rate of heat transfer systems involving exponential temperature-time histories. A pulse thermocouple system has been utilized in such a technique having a steady state response time on the order of one time constant of the thermocouple used. When an impulse thermocouple system is not used, the required time in obtaining the steady state value is on the order of five time constants or the time required to reach steady state.

Airborne measurements of the downward spectral solar irradiance were analyzed with differential optical absorption spectroscopy for the integrated water vapor (IWV) in the atmospheric column above the aircraft. The measurements are obtained from two campaigns in 2016, during which the High Altitude and Long Range Research Aircraft (HALO) took measurements of the downward solar irradiance within the upper troposphere and lower stratosphere (UTLS). The feasibility and limitations of the presented method are discussed for the dry conditions, which are typical for the high altitudes of the UTLS and above. Considering the uncertainties encountered in the irradiance measurements and the high sensitivity of the retrieval, the method was unable to provide sound results for the stratosphere, but provided reasonable results in the troposphere. / Flugzeuggetragene Messungen der abwärtsgerichteten spektralen solaren Irradianz wurden mit der Methode der differenziellen optischen Absorptionsspektroskopie auf den integrierten Wasserdampf (IWV) in der Atmosphäre oberhalb des Flugzeuges untersucht. Im Rahmen zweier Messkampagnen im Jahr 2016 führte das High Altitude and Long Range Research Aircraft (HALO) Messungen der spektralen solaren Irradianz in dem Höhenbereich der oberen Troposphäre und unteren Stratosphäre (UTLS) durch. Hier werden das Potential und die Limitierungen eines solchen Verfahrens untersucht, um Wasserdampf in den trockenen Gegebenheiten abzuleiten, die in und oberhalb der UTLS herrschen. Angesichts der Messunsicherheiten und der hohen Sensitivität des Verfahrens, konnten in der Statosphäre nicht aussagekräftige Ergebnisse erreicht werden, aber in der Troposphäre konnte das Verfahren zuverlässige Ergebnisse liefern.

Jag har undersökt hur tillståndet absorption kan användas för att förstå hur försjunkenhet skapas i en målning. Detta har gjorts genom en fallstudie av sex verk, tre av Anna Ancher och tre av Johannes Vermeer. Urvalet har berott på verkens fotorealistiska stil samt att de avbildar en kvinna utförandes en aktivitet, till synes försjunken i det hon gör. Jag har undersökt målningarnas olika beståndsdelar genom att använda mig av Ervin Panofskys ikonologiska och ikonografiska analys och sedan ställt dem mot Michael Frieds begrepp absorption i en jämförande analys. Jag har kommit fram till är att absorptionen och försjunkenheten i dessa sex verk syns genom den aktivitet som den avbildade figuren utför, figurens hållning och blickriktning. Ljussättningen och kompositionen bidrar även till en känsla av närhet och intimitet som förstärker känslan av försjunkenhet.