24 resultados para 670200 Fibre Processing and Textiles
em Helda - Digital Repository of University of Helsinki
Resumo:
The auditory system can detect occasional changes (deviants) in acoustic regularities without the need for subjects to focus their attention on the sound material. Deviant detection is reflected in the elicitation of the mismatch negativity component (MMN) of the event-related potentials. In the studies presented in this thesis, the MMN is used to investigate the auditory abilities for detecting similarities and regularities in sound streams. To investigate the limits of these processes, professional musicians have been tested in some of the studies. The results show that auditory grouping is already more advanced in musicians than in nonmusicians and that the auditory system of musicians can, unlike that of nonmusicians, detect a numerical regularity of always four tones in a series. These results suggest that sensory auditory processing in musicians is not only a fine tuning of universal abilities, but is also qualitatively more advanced than in nonmusicians. In addition, the relationship between the auditory change-detection function and perception is examined. It is shown that, contrary to the generally accepted view, MMN elicitation does not necessarily correlate with perception. The outcome of the auditory change-detection function can be implicit and the implicit knowledge of the sound structure can, after training, be utilized for behaviorally correct intuitive sound detection. These results illustrate the automatic character of the sensory change detection function.
Resumo:
This thesis reports on investigations into the influence of heat treatment on the manufacturing of oat flakes. Sources of variation in the oat flake quality are reviewed, including the whole chain from the farm to the consumer. The most important quality parameters of oat flakes are the absence of lipid hydrolysing enzymes, specific weight, thickness, breakage (fines), water absorption. Flavour, colour and pasting properties are also important, but were not included in the experimental part of this study. Of particular interest was the role of heat processing. The first possible heat treatment may occur already during grain drying, which in Finland generally happens at the farm. At the mill, oats are often kilned to stabilise the product by inactivating lipid hydrolysing enzymes. Almost invariably steaming is used during flaking, to soften the groats and reduce flake breakage. This thesis presents the use of a material science approach to investigating a complex system, typical of food processes. A combination of fundamental and empirical rheological measurements was used together with a laboratory scale process to simulate industrial processing. The results were verified by means of industrial trials. Industrially produced flakes at three thickness levels (nominally 0.75, 0.85 and 0.90 mm) were produced from kilned and unkilned oat groats, and the flake strength was measured at different moisture contents. Kilning was not found to significantly affect the force required to puncture a flake with a 2mm cylindrical probe, which was taken as a measure of flake strength. To further investigate how heat processing contributes to flake quality, dynamic mechanical analysis was used to characterise the effect of heat on the mechanical properties of oats. A marked stiffening of the groat, of up to about 50% increase in storage modulus, was observed during first heating at around 36 to 57°C. This was also observed in tablets prepared from ground groats and extracted oat starch. This stiffening was thus attributed to increased adhesion between starch granules. Groats were steamed in a laboratory steamer and were tempered in an oven at 80 110°C for 30 90 min. The maximum force required to compress the steamed groats to 50% strain increased from 50.7 N to 57.5 N as the tempering temperature was increased from 80 to 110°C. Tempering conditions also affected water absorption. A significantly higher moisture content was observed for kilned (18.9%) compared to unkilned (17.1%) groats, but otherwise had no effect on groat height, maximum force or final force after a 5 s relaxation time. Flakes were produced from the tempered groats using a laboratory flaking machine, using a roll gap of 0.4 mm. Apart from specific weight, flake properties were not influenced by kilning. Tempering conditions however had significant effects on the specific weight, thickness and water absorption of the flakes, as well as on the amount of fine material (<2 mm) produced during flaking. Flake strength correlated significantly with groat strength and flake thickness. Trial flaking at a commercial mill confirmed that groat temperature after tempering influenced water absorption. Variation in flake strength was observed , but at the groat temperatures required to inactivate lipase, it was rather small. Cold flaking of groats resulted in soft, floury flakes. The results presented in this thesis suggest that heating increased the adhesion between starch granules. This resulted in an increase in the stiffness and brittleness of the groat. Brittle fracture, rather than plastic flow, during flaking could result in flaws and cracks in the flake. These would be expected to increase water absorption. This was indeed observed as tempering temperature increased. Industrial trials, conducted with different groat temperatures, confirmed the main findings of the laboratory experiments. The approach used in the present study allowed the systematic study of the effect of interacting process parameters on product quality. There have been few scientific studies of oat processing, and these results can be used to understand the complex effects of process variables on flake quality. They also offer an insight into what happens as the oat groat is deformed into a flake.
Resumo:
Fatty acids, fibre, carotenoids and tocopherols in relation to glucose metabolism in subjects at high risk for type 2 diabetes a cross-sectional analysis Type 2 diabetes (T2D) is a heterogeneous disorder of carbohydrate, lipid and protein metabolism, resulting from genetics, environmental influences and interactions between these. The disease is characterized by insulin resistance, β-cell dysfunction, hepatic glucose overproduction and disordered fat mobilization and storage. The literature on associations between dietary factors and glucose metabolism is inconsistent. One factor behind the discrepant results may be genetic heterogeneity of study populations. Data on nutrient-gene interactions in relation to glucose metabolism are scarce. Thus, investigating high-risk populations and exploring nutrient-gene interactions are essential for improving the understanding of T2D aetiology. Ideally, this information could help to develop prevention programmes that take into account the genetic predisposition to the disease. In this study, associations between measures of glucose metabolism predicting T2D and fatty acids, antioxidative nutrients and fibre were examined in a high-risk population, i.e., in non-diabetic relatives of affected patients. Interactions between the PPARG Pro12Ala polymorphism and fatty acids on glucose metabolism were taken into consideration. This common polymorphism plays an important role in the regulation of glucose metabolism. The inverse associations observed between dietary fibre and insulin resistance are consistent with the prevailing recommendations urging increased intake of fibre to prevent T2D. Beneficial associations observed between the intake of carotenoids and glucose levels stress that a high consumption of vegetables, fruits and berries rich in carotenoids might also play a role in the prevention of T2D. Whether tocopherols have an independent association with glucose metabolism remains questionable. Observed interactions between fatty acids and glucose metabolism suggest that a high intake of palmitic acid is associated with high fasting glucose levels mainly in female Ala allele carriers. Furthermore, the PPARG Pro12Ala polymorphism may modify the metabolic response to dietary marine fat. The beneficial associations of high intake of marine n 3 fatty acids with insulin resistance and glucose levels may be restricted to carriers of the Ala allele. The findings pertain to subjects with a family history of T2D, and the cross-sectional nature of the study precludes inferences about causality. Results nevertheless show that associations of dietary factors with glucose metabolism may be modulated by the genetic makeup of an individual. Additional research is warranted to elucidate the role of probably numerous nutrient-gene interactions, some of which may be sex-specific, in the aetiology of T2D.
Resumo:
Flax and hemp have traditionally been used mainly for textiles, but recently interest has also been focused on non-textile applications. Microbial quality throughout the whole processing chain of bast fibres has not previously been studied. This study concentrates on the microbial quality and possible microbial risks in the production chain of hemp and flax fibres and fibrous thermal insulations. In order to be able to utilize hemp and flax fibres, the bast fibres must be separated from the rest of the plant. Non-cellulosic components can be removed with various pretreatment processes, which are associated with a certain risk of microbial contamination. In this study enzymatic retting and steam explosion (STEX) were examined as pretreatment processes. On the basis of the results obtained in this study, the microbial contents on stalks of both plants studied increased at the end of the growing season and during the winter. However, by processing and mechanical separation it is possible to produce fibres containing less moulds and bacteria than the whole stem. Enzymatic treatment encouraged the growth of moulds in fibres. Steam explosion reduced the amount of moulds in fibres. Dry thermal treatment used in this study did not markedly reduce the amount of microbes. In this project an emission measurement chamber was developed which was suitable for measurements of emissions from both mat type and loose fill type insulations, and capable of interdisciplinary sampling. In this study, the highest amounts of fungal emissions were in the range of 10^3 10^5 cfu/m^3 from the flax and hemp insulations at 90% RH of air. The fungal emissions from stone wool, glass wool and recycled paper insulations were below 10^2 cfu/m^3 even at 90% RH. Equally low values were obtained from bast fibrous materials in lower humidities (at 30% and 80% RH of air). After drying of moulded insulations at 30% RH, the amounts of emitted moulds were in all cases higher compared to the emissions at 90% RH before drying. The most common fungi in bast fibres were Penicillium and Rhizopus. The widest variety of different fungi was in the untreated hemp and linseed fibres and in the commercial loose-fill flax insulation. Penicillium, Rhizopus and Paecilomyces were the most tolerant to steam explosion. According to the literature, the most common fungi in building materials and indoor air are Penicillium, Aspergillus and Cladosporium, which were all found in some of the bast fibre materials in this study. As organic materials, hemp and flax fibres contain high levels of nutrients for microbial growth. The amount of microbes can be controlled and somewhat decreased by the processing methods presented.
Resumo:
The number of drug substances in formulation development in the pharmaceutical industry is increasing. Some of these are amorphous drugs and have glass transition below ambient temperature, and thus they are usually difficult to formulate and handle. One reason for this is the reduced viscosity, related to the stickiness of the drug, that makes them complicated to handle in unit operations. Thus, the aim in this thesis was to develop a new processing method for a sticky amorphous model material. Furthermore, model materials were characterised before and after formulation, using several characterisation methods, to understand more precisely the prerequisites for physical stability of amorphous state against crystallisation. The model materials used were monoclinic paracetamol and citric acid anhydrate. Amorphous materials were prepared by melt quenching or by ethanol evaporation methods. The melt blends were found to have slightly higher viscosity than the ethanol evaporated materials. However, melt produced materials crystallised more easily upon consecutive shearing than ethanol evaporated materials. The only material that did not crystallise during shearing was a 50/50 (w/w, %) blend regardless of the preparation method and it was physically stable at least two years in dry conditions. Shearing at varying temperatures was established to measure the physical stability of amorphous materials in processing and storage conditions. The actual physical stability of the blends was better than the pure amorphous materials at ambient temperature. Molecular mobility was not related to the physical stability of the amorphous blends, observed as crystallisation. Molecular mobility of the 50/50 blend derived from a spectral linewidth as a function of temperature using solid state NMR correlated better with the molecular mobility derived from a rheometer than that of differential scanning calorimetry data. Based on the results obtained, the effect of molecular interactions, thermodynamic driving force and miscibility of the blends are discussed as the key factors to stabilise the blends. The stickiness was found to be affected glass transition and viscosity. Ultrasound extrusion and cutting were successfully tested to increase the processability of sticky material. Furthermore, it was found to be possible to process the physically stable 50/50 blend in a supercooled liquid state instead of a glassy state. The method was not found to accelerate the crystallisation. This may open up new possibilities to process amorphous materials that are otherwise impossible to manufacture into solid dosage forms.
Resumo:
Activation of midbrain dopamine systems is thought to be critically involved in the addictive properties of abused substances. Drugs of abuse increase dopamine release in the nucleus accumbens and dorsal striatum, which are the target areas of mesolimbic and nigrostriatal dopamine pathways, respectively. Dopamine release in the nucleus accumbens is thought to mediate the attribution of incentive salience to rewards, and dorsal striatal dopamine release is involved in habit formation. In addition, changes in the function of prefrontal cortex (PFC), the target area of mesocortical dopamine pathway, may skew information processing and memory formation such that the addict pays an abnormal amount of attention to drug-related cues. In this study, we wanted to explore how long-term forced oral nicotine exposure or the lack of catechol-O-methyltransferase (COMT), one of the dopamine metabolizing enzymes, would affect the functioning of these pathways. We also wanted to find out how the forced nicotine exposure or the lack of COMT would affect the consumption of nicotine, alcohol, or cocaine. First, we studied the effect of forced chronic nicotine exposure on the sensitivity of dopamine D2-like autoreceptors in microdialysis and locomotor activity experiments. We found that the sensitivity of these receptors was unchanged after forced oral nicotine exposure, although an increase in the sensitivity was observed in mice treated with intermittent nicotine injections twice daily for 10 days. Thus, the effect of nicotine treatment on dopamine autoreceptor sensitivity depends on the route, frequency, and time course of drug administration. Second, we investigated whether the forced oral nicotine exposure would affect the reinforcing properties of nicotine injections. The chronic nicotine exposure did not significantly affect the development of conditioned place preference to nicotine. In the intravenous self-administration paradigm, however, the nicotine-exposed animals self-administered nicotine at a lower unit dose than the control animals, indicating that their sensitivity to the reinforcing effects of nicotine was enhanced. Next, we wanted to study whether the Comt gene knock-out animals would be a suitable model to study alcohol and cocaine consumption or addiction. Although previous work had shown male Comt knock-out mice to be less sensitive to the locomotor-activating effects of cocaine, the present study found that the lack of COMT did not affect the consumption of cocaine solutions or the development of cocaine-induced place preference. However, the present work did find that male Comt knock-out mice, but not female knock-out mice, consumed ethanol more avidly than their wild-type littermates. This finding suggests that COMT may be one of the factors, albeit not a primary one, contributing to the risk of alcoholism. Last, we explored the effect of COMT deficiency on dorsal striatal, accumbal, and prefrontal cortical dopamine metabolism under no-net-flux conditions and under levodopa load in freely-moving mice. The lack of COMT did not affect the extracellular dopamine concentrations under baseline conditions in any of the brain areas studied. In the prefrontal cortex, the dopamine levels remained high for a prolonged time after levodopa treatment in male, but not female, Comt knock-out mice. COMT deficiency induced accumulation of 3,4-dihydroxyphenylacetic acid, which increased further under levodopa load. Homovanillic acid was not detectable in Comt knock-out animals either under baseline conditions or after levodopa treatment. Taken together, the present results show that although forced chronic oral nicotine exposure affects the reinforcing properties of self-administered nicotine, it is not an addiction model itself. COMT seems to play a minor role in dopamine metabolism and in the development of addiction under baseline conditions, indicating that dopamine function in the brain is well-protected from perturbation. However, the role of COMT becomes more important when the dopaminergic system is challenged, such as by pharmacological manipulation.
Resumo:
The ability to deliver the drug to the patient in a safe, efficacious and cost-effective manner depends largely on the physicochemical properties of the active pharmaceutical ingredient (API) in the solid state. In this context, crystallization is of critical importance in pharmaceutical industry, as it defines physical and powder properties of crystalline APIs. An improved knowledge of the various aspects of crystallization process is therefore needed. The overall goal of this thesis was to gain better understanding of the relationships between crystallization, solid-state form and properties of pharmaceutical solids with a focus on a crystal engineering approach to design technological properties of APIs. Specifically, solid-state properties of the crystalline forms of the model APIs, erythromycin A and baclofen, and the influence of solvent on their crystallization behavior were investigated. In addition, the physical phenomena associated with wet granulation and hot-melting processing of the model APIs were examined at the molecular level. Finally, the effect of crystal habit modification of a model API on its tabletting properties was evaluated. The thesis enabled the understanding of the relationship between the crystalline forms of the model APIs, which is of practical importance for solid-state control during processing and storage. Moreover, a new crystalline form, baclofen monohydrate, was discovered and characterized. Upon polymorph screening, erythromycin A demonstrated high solvate-forming propensity thus emphasizing the need for careful control of the solvent effects during formulation. The solvent compositions that yield the desirable crystalline form of erythromycin A were defined. Furthermore, new examples on solvent-mediated phase transformations taking place during wet granulation of baclofen and hot-melt processing of erythromycin A dihydrate with PEG 6000 are reported. Since solvent-mediated phase transformations involve the crystallization of a stable phase and hence affect the dissolution kinetics and possibly absorption of the API these transformations must be well documented. Finally, a controlled-crystallization method utilizing HPMC as a crystal habit modifier was developed for erythromycin A dihydrate. The crystals with modified habit were shown to posses improved compaction properties as compared with those of unmodified crystals. This result supports the idea of morphological crystal engineering as a tool for designing technological properties of APIs and is of utmost practical interest.
Resumo:
The present research focused on motivational and personality traits measuring individual differences in the experience of negative affect, in reactivity to negative events, and in the tendency to avoid threats. In this thesis, such traits (i.e., neuroticism and dispositional avoidance motivation) are jointly referred to as trait avoidance motivation. The seven studies presented here examined the moderators of such traits in predicting risk judgments, negatively biased processing, and adjustment. Given that trait avoidance motivation encompasses reactivity to negative events and tendency to avoid threats, it can be considered surprising that this trait does not seem to be related to risk judgments and that it seems to be inconsistently related to negatively biased information processing. Previous work thus suggests that some variable(s) moderate these relations. Furthermore, recent research has suggested that despite the close connection between trait avoidance motivation and (mal)adjustment, measures of cognitive performance may moderate this connection. However, it is unclear whether this moderation is due to different response processes between individuals with different cognitive tendencies or abilities, or to the genuinely buffering effect of high cognitive ability against the negative consequences of high trait avoidance motivation. Studies 1-3 showed that there is a modest direct relation between trait avoidance motivation and risk judgments, but studies 2-3 demonstrated that state motivation moderates this relation. In particular, individuals in an avoidance state made high risk judgments regardless of their level of trait avoidance motivation. This result explained the disparity between the theoretical conceptualization of avoidance motivation and the results of previous studies suggesting that the relation between trait avoidance motivation and risk judgments is weak or nonexistent. Studies 5-6 examined threat identification tendency as a moderator for the relationship between trait avoidance motivation and negatively biased processing. However, no evidence for such moderation was found. Furthermore, in line with previous work, the results of studies 5-6 suggested that trait avoidance motivation is inconsistently related to negatively biased processing, implying that theories concerning traits and information processing may need refining. Study 7 examined cognitive ability as a moderator for the relation between trait avoidance motivation and adjustment, and demonstrated that cognitive ability moderates the relation between trait avoidance motivation and indicators of both self-reported and objectively measured adjustment. Thus, the results of Study 7 supported the buffer explanation for the moderating influence of cognitive performance. To summarize, the results showed that it is possible to find factors that consistently moderate the relations between traits and important outcomes (e.g. adjustment). Identifying such factors and studying their interplay with traits is one of the most important goals of current personality research. The present thesis contributed to this line of work in relation to trait avoidance motivation.
Resumo:
The synchronization of neuronal activity, especially in the beta- (14-30 Hz) /gamma- (30 80 Hz) frequency bands, is thought to provide a means for the integration of anatomically distributed processing and for the formation of transient neuronal assemblies. Thus non-stimulus locked (i.e. induced) gamma-band oscillations are believed to underlie feature binding and the formation of neuronal object representations. On the other hand, the functional roles of neuronal oscillations in slower theta- (4 8 Hz) and alpha- (8 14 Hz) frequency bands remain controversial. In addition, early stimulus-locked activity has been largely ignored, as it is believed to reflect merely the physical properties of sensory stimuli. With human neuromagnetic recordings, both the functional roles of gamma- and alpha-band oscillations and the significance of early stimulus-locked activity in neuronal processing were examined in this thesis. Study I of this thesis shows that even the stimulus-locked (evoked) gamma oscillations were sensitive to high-level stimulus features for speech and non-speech sounds, suggesting that they may underlie the formation of early neuronal object representations for stimuli with a behavioural relevance. Study II shows that neuronal processing for consciously perceived and unperceived stimuli differed as early as 30 ms after stimulus onset. This study also showed that the alpha band oscillations selectively correlated with conscious perception. Study III, in turn, shows that prestimulus alpha-band oscillations influence the subsequent detection and processing of sensory stimuli. Further, in Study IV, we asked whether phase synchronization between distinct frequency bands is present in cortical circuits. This study revealed prominent task-sensitive phase synchrony between alpha and beta/gamma oscillations. Finally, the implications of Studies II, III, and IV to the broader scientific context are analysed in the last study of this thesis (V). I suggest, in this thesis that neuronal processing may be extremely fast and that the evoked response is important for cognitive processes. I also propose that alpha oscillations define the global neuronal workspace of perception, action, and consciousness and, further, that cross-frequency synchronization is required for the integration of neuronal object representations into global neuronal workspace.
Resumo:
Cathepsin D (CTSD) is a lysosomal protease, the deficiency of which is fatal and associated with neurodegeneration. CTSD knock-out mice, which die at the age of four weeks, show intestinal necrosis, loss of lymphoid cells and moderate pathological changes in the brain. An active-site mutation in the CTSD gene underlies a neurodegenerative disease in newborn sheep, characterized by brain atrophy without any changes to visceral tissues. The CTSD deficiences belong to the group of neuronal ceroid-lipofuscinoses (NCLs), severe neurodegenerative lysosomal storage disorders. The aim of this thesis was to examine the molecular and cellular mechanisms behind neurodegeneration in CTSD deficiency. We found the developmental expression pattern of CTSD to resemble that of synaptophysin and the increasing expression of CTSD to coincide with the active period of myelination in the rat brain, suggesting a role for CTSD in early rat brain development. An active-site mutation underlying the congenital ovine NCL not only affected enzymatic activity, but also changed the stability, processing and transport of the mutant protein, possibly contributing to the disease pathogenesis. We also provide CTSD deficiency as a first molecular explanation for human congenital NCL, a lysosomal storage disorder, characterized by neuronal loss and demyelination in the central nervous system. Finally, we show the first evidence for synaptic abnormalities and thalamocortical changes in CTSD-deficient mice at the molecular and ultrastructural levels. Keywords: cathepsin D, congenital, cortex, lysosomal storage disorder, lysosome, mutation, neurodegeneration, neuronal ceroid-lipofuscinosis, overexpression, synapse, thalamus
Latent TGF-β binding proteins -3 and -4 : transcriptional control and extracellular matrix targeting
Resumo:
Extracellular matrix (ECM) is a complex network of various proteins and proteoglycans which provides tissues with structural strength and resilience. By harvesting signaling molecules like growth factors ECM has the capacity to control cellular functions including proliferation, differentiation and cell survival. Latent transforming growth factor β (TGF-β) binding proteins (LTBPs) associate fibrillar structures of the ECM and mediate the efficient secretion and ECM deposition of latent TGF-β. The current work was conducted to determine the regulatory regions of LTBP-3 and -4 genes to gain insight into their tissue-specific expression which also has impact on TGF-β biology. Furthermore, the current research aimed at defining the ECM targeting of the N-terminal variants of LTBP-4 (LTBP-4S and -4L), which is required to understand their functions in tissues and to gain insight into conditions in which TGF-β is activated. To characterize the regulatory regions of LTBP-3 and -4 genes in silico and functional promoter analysis techniques were employed. It was found that the expression of LTBP-4S and -4L are under control of two independent promoters. This finding was in accordance with the observed expression patterns of LTBP-4S and -4L in human tissues. All promoter regions characterized in this study were TATAless, GC-rich and highly conserved between human and mouse species. Putative binding sites for Sp1 and GATA family of transcription factors were recognized in all of these regulatory regions. It is possible that these transcription factors control the basal expression of LTBP-3 and -4 genes. Smad binding element was found within the LTBP-3 and -4S promoter regions, but it was not present in LTBP-4L promoter. Although this element important for TGF-β signaling was present in LTBP-4S promoter, TGF-β did not induce its transcriptional activity. LTBP-3 promoter activity and mRNA expression instead were stimulated by TGF-β1 in osteosarcoma cells. It was found that the stimulatory effect of TGF-β was mediated by Smad and Erk MAPK signaling pathways. The current work explored the ECM targeting of LTBP-4S and identified binding partners of this protein. It was found that the N-terminal end of LTBP-4S possesses fibronectin (FN) binding sites which are critical for its ECM targeting. FN deficient fibroblasts incorporated LTBP-4S into their ECM only after addition of exogenous FN. Furthermore, LTBP-4S was found to have heparin binding regions, of which the C-terminal binding site mediated fibroblast adhesion. Soluble heparin prevented the ECM association of LTBP-4S in fibroblast cultures. In the current work it was observed that there are significant differences in the secretion, processing and ECM targeting of LTBP-4S and -4L. Interestingly, it was observed that most of the secreted LTBP-4L was associated with latent TGF-β1, whereas LTBP-4S was mainly secreted as a free form from CHO cells. This thesis provides information on transcriptional regulation of LTBP-3 and -4 genes, which is required for the deeper understanding of their tissue-specific functions. Further, the current work elucidates the structural variability of LTBPs, which appears to have impact on secretion and ECM targeting of TGF-β. These findings may advance understanding the abnormal activation of TGF-β which is associated with connective tissue disorders and cancer.