1. An earlier study by our group revealed that the viscosity of faeces from patients with Crohn's disease is significantly lower than that of healthy subjects. This is due to low concentrations of a high-molecular-mass carbohydrate, probably of bacterial origin. The cause of this phenomenon might be the impaired barrier function of the gut mucosa. Low viscosity may allow close contact of intestinal contents (bacterial products and toxins) with the intestinal wall. This could play a role in the maintenance of the disease.2. The first aim of this study was to investigate the high-molecular-mass carbohydrate fraction, responsible for viscosity, in detail. We also tried (in a pilot study) to raise the intestinal viscosity of patients with Crohn's disease with the undegradable food additive hydroxypropylcellulose (E463), in an attempt to alleviate clinical symptoms.3. The high-molecular-mass fraction (>300 kDa) responsible for faecal viscosity was sensitive to lysozyme and contained high levels of muramic acid. It was concluded that this material consisted mainly of peptidoglycan polysaccharides and was consequently of bacterial origin. The muramic acid in material from patients with Crohn's disease was 7.5 (1.5-13.9)%, which was less than in healthy subjects [11.4 (8.5-24.1)%; P=0.0004]. Furthermore, viscosity in material from patients with Crohn's disease was found to be half [14.9 (1.0-33.6) cP] of that found in healthy subjects [35.0 (2.7-90.7) cP; P=0.004].4.A daily dose of 1 g of hydroxypropylcellulose caused an increase in faecal viscosity in patients with Crohn's disease (from 1.4 to 2.3 cP) and in healthy subjects (from 4.9 to 7.5 cP). Faecal consistency improved in patients with Crohn's disease (from watery and loose to formed) and the defecation frequency decreased from 3-4 to about 2 times a day. No changes in defecation patterns were found in healthy subjects.5. These data indicate that the high-molecular-mass fraction that is responsible for faecal viscosity is peptidoglycan. Furthermore, a daily dose of a hydroxypropylcellulose solution to increase the viscosity of the intestinal contents of patients with Crohn's disease might be beneficial. This approach merits further study.
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This study provides insights into novel combinations of hydrothermal modifications and mineral enrichment by demonstrating the versatility of this environmentally more benign approach compared to other common chemical starch modifications like crosslinking. Heat-moisture treatment (HMT) (15 % moisture, 100 °C) of native potato starch (NPS) affords granular products that gelatinise at lower temperatures, hold more water as gel, and are more susceptible to enzymatic digestion. Prior mineral enrichment of NPS with sodium, potassium, magnesium and calcium ions yielded significant changes in pasting curves, with monovalent cations increasing peak viscosity, while divalent cations decrease peak viscosity through ionic crosslinking of phosphate groups, allowing further fine tuning of swelling behaviour. Both short and long HMT (4 h and 16 h) triggered partial disruption of crystallinity and an increase in particle size without visible surface damage as evidenced by X-ray diffraction, laser diffraction and scanning electron microscopy. These novel products may find applications where a thickening agent is needed, and high levels of target minerals are desirable like sport nutrition. The viscosity behaviour, available energy and essential minerals may be beneficial to the formulation and nutritional value of energy gels, while adhering to clean-label requirements of today`s food industry.
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De snelheid waarmee we eten, speelt een belangrijke rol in ons eetgedrag. Leidt een vork die helpt om langzaam te eten tot een verandering in eetsnelheid, verzadiging en voedselinname?
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Native potato starch is an excellent carrier of minerals due to its inherent ion exchange capacity. Mineral enrichment not only changes the nutritional value but also influences starch pasting and swelling properties. Hydrothermal treatments like annealing constitute a straightforward and green way to tune functional properties. Here, novel combinations of mineral enrichment and annealing were studied. Ion exchange was readily achieved by suspending starch in a salt solution at room temperature over 3 h and confirmed by ICP-OES. Annealing at 50 °C for 24 h using demineralized water or salt solutions strongly affected pasting, thermal, and swelling properties. The obtained XRD and DSC results support a more ordered structure with relative crystallinity increasing from initially 41.7% to 44.4% and gelatinization onset temperature increasing from 60.39 to 65.94 J/g. Solid-state NMR spectroscopy revealed no detectable changes after annealing. Total digestible starch content decreased after annealing from 8.89 to 7.86 g/100 g. During both ion exchange at room temperature and annealing, monovalent cations promoted swelling and peak viscosity, and divalent cations suppressed peak viscosity through ionic crosslinking. The presented combination allows fine-tuning of pasting behavior, potentially enabling requirements of respective food applications to be met while offering an alternative to chemically modified starches.
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Mild heat pasteurization, high pressure processing (HP) and pulsed electric field (PEF) processing of freshly squeezed orange juice were comparatively evaluated examining their impact on microbial load and quality parameters immediately after processing and during two months of storage. Microbial counts for treated juices were reduced beyond detectable levels immediately after processing and up to 2 months of refrigerated storage. Quality parameters such as pH, dry matter content and brix were not significantly different when comparing juices immediately after treatment and were, for all treatments, constant during storage time. Quality parameters related to pectinmethylesterase (PME) inactivation, like cloud stability and viscosity, were dependent on the specific treatments that were applied. Mild heat pasteurization was found to result in the most stable orange juice. Results for HP are nearly comparable to PEF except on cloud degradation, where a lower degradation rate was found for HP. For PEF, residual enzyme activity was clearly responsible for changes in viscosity and cloud stability during storage. Industrial relevance: Development of mild processing technologies with a minimal impact on fruit juice can be considered as a true alternative of fresh fruit. The present work presents a fair comparison of mild heat treated, high pressure (HP) and pulsed electric field (PEF) processed orange juice as an alternative for thermal pasteurization. Orange juices were monitored during two months of storage.
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Abstract geschreven door R.J. Dijkink (Saxion), J.C. Lötters (Universiteit van Twente & Bronkhorst High-Tech BV), B.I. van den Berg (Medical Spectrum Twente) en C.A.J. Damen (Saxion). Initial investigations into the use of a MEMS based multi-parameter sensor for the characterization of medicine mixtures are presented. The current results show good results for density and mediocre results for heat capacity. Viscosity measurements have not yet produced any usable results. However there are clear flaws in the setup which could be the cause of this and which will no
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With a market demand for low cost, easy to produce, flexible and portable applications in healthcare, energy, biomedical or electronics markets, large research programs are initiated to develop new technologies to provide this demand with new innovative ideas. One of these fast developing technologies is organic printed electronics. As the term printed electronics implies, functional materials are printed via, e.g. inkjet, flexo or gravure printing techniques, on to a substrate material. Applications are, among others, organic light emitting diodes (OLED), sensors and Lab-on-a-chip devices. For all these applications, in some way, the interaction of fluids with the substrate is of great importance. The most used substrate materials for these low-cost devices are (coated) paper or plastic. Plastic substrates have a relatively low surface energy which frequently leads to poor wetting and/or poor adhesion of the fluids on the substrates during printing and/ or post-processing. Plasma technology has had a long history in treating materials in order to improve wetting or promote adhesion. The µPlasma patterning tool described in this thesis combines a digital inkjet printing platform with an atmospheric dielectric barrier discharge plasma tool. Thus enabling selective and local plasma treatment, at atmospheric pressure, of substrates without the use of any masking materials. In this thesis, we show that dependent on the gas composition the substrate surface can either be functionalized, thus increasing its surface energy, or material can be deposited on the surface, lowering its surface energy. Through XPS and ATR-FTIR analysis of the treated (polymer) substrate surfaces, chemical modification of the surface structure was confirmed. The chemical modification and wetting properties of the treated substrates remained present for at least one month after storage. Localized changes in wettability through µPlasma patterning were obtained with a resolution of 300µm. Next to the control of wettability of an ink on a substrate in printed electronics is the interaction of ink droplets with themselves of importance. In printing applications, coalescence of droplets is standard practice as consecutive droplets are printed onto, or close to each other. Understanding the behaviour of these droplets upon coalescence is therefore important, especially when the ink droplets are of different composition and/or volume. For droplets of equal volume, it was found that dye transport across the coalescence bridge could be fully described by diffusion only. This is as expected, as due to the droplet symmetry on either side of the bridge, the convective flows towards the bridge are of equal size but opposite in direction. For droplets of unequal volume, the symmetry across the bridge is no longer present. Experimental analysis of these merging droplets show that in the early stages of coalescence a convective flow from the small to large droplet is present. Also, a smaller convective flow of shorter duration from the large into the small droplet was identified. The origin of this flow might be due to the presence of vortices along the interface of the bridge, due to the strong transverse flow to open the bridge. To conclude, three potential applications were showcased. In the first application we used µPlasma patterning to create hydrophilic patterns on hydrophobic dodecyl-trichlorosilane (DTS) covered glass. Capillaries for a Lab-on-a-chip device were successfully created by placing two µPlasma patterned glass slides on top of each other separated by scotch tape. In the second application we showcased the production of a RFID tag via inkjet printing. Functional RFID-tags on paper were created via inkjet printing of silver nanoparticle ink connected to an integrated circuit. The optimal operating frequency of the produced tags is in the range of 860-865 MHz, making them usable for the European market, although the small working range of 1 m needs further improvement. Lastly, we showed the production of a chemresistor based gas sensor. In house synthesised polyemeraldine salt (PANi) was coated by hand on top of inkjet printed silver electrodes. The sensor proved to be equally sensitive to ethanol and water vapour, reducing its selectivity in detecting changes in gas composition.
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Understanding sludge rheology and optimizing equipment performance is crucial for energy efficiency in wastewater treatment plants (WWTPs). This study examined sludge rheology after thermal hydrolysis pretreatment (THP) at 60, 80, and 120 ◦C for 2 h, followed by anaerobic digestion (AD) at 37 ◦C for 20 days, and assessed impacts on pump and agitator performance. Post-treatment, sludge showed reduced viscosity and improved flowability, indicated by changes in Herschel-Bulkley parameters, enhancing pump and agitator efficiency, particularly at 120 ◦C. These rheological improvements were correlated to the solubilization of sludge components after THP and solids reduction after AD, highlighting the interconnectedness of rheology and treatment outcomes. Despite high heat demands, an energy balance showed that THP scenarios, especially at 120 ◦C, had lower energy requirements for pumps and agitators, leading to energy savings without increased heat consumption. These findings underscore the influence of rheological changes in improving energy efficiency in WWTPs.
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Currently the advances in the field of 3D printing are causing a revolution in the (bio-)medical field. With applications ranging from patient-specific anatomical models for surgical preparation to prosthetic limbs and even scaffolds for tissue engineering, the possibilities seem endless. Today, the most widely used method is FDM printing. However, there is still a limited range of biodegradable and biocompatible materials available. Moreover, printed implants like for instance cardiovascular stents require higher resolution than is possible to reach with FDM. High resolution is crucial to avoid e.g. bacterial growth and aid to mechanical strength of the implant. For this reason, it would be interesting to consider stereolithography as alternative to FDM for applications in the (bio-) medical field. Stereolithography uses photopolymerizable resins to make high resolution prints. Because the amount of commercially available resins is limited and hardly biocompatible, here we investigate the possibility of using acrylates and vinylesters in an effort to expand the existing arsenal of biocompatible resins. Mechanical properties are tailorable by varying the crosslink density and by varying the spacer length. To facilitate rapid production of high-resolution prints we use masked SLA (mSLA) as an alternative to conventional SLA. mSLA cures an entire layer at a time and therefore uses less time to complete a print than conventional SLA. Additionally, with mSLA it takes the same time to make 10 prints as it would to make only one. Several formulations were prepared and tested for printability and mechanical strength.
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