| 1. |
- Faatz, B., et al.
(författare)
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Simultaneous operation of two soft x-ray free-electron lasers driven by one linear accelerator
- 2016
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Ingår i: New Journal of Physics. - : IOP Publishing. - 1367-2630. ; 18
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Tidskriftsartikel (refereegranskat)abstract
- Extreme-ultraviolet to x-ray free-electron lasers (FELs) in operation for scientific applications are up to now single-user facilities. While most FELs generate around 100 photon pulses per second, FLASH at DESY can deliver almost two orders of magnitude more pulses in this time span due to its superconducting accelerator technology. This makes the facility a prime candidate to realize the next step in FELs-dividing the electron pulse trains into several FEL lines and delivering photon pulses to several users at the same time. Hence, FLASH has been extended with a second undulator line and self-amplified spontaneous emission (SASE) is demonstrated in both FELs simultaneously. FLASH can now deliver MHz pulse trains to two user experiments in parallel with individually selected photon beam characteristics. First results of the capabilities of this extension are shown with emphasis on independent variation of wavelength, repetition rate, and photon pulse length.
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| 2. |
- Ahrné, Lilia, et al.
(författare)
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Microwave convective drying of plant foods at constant and variable microwave power
- 2007
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Ingår i: Drying Technology. - : Informa UK Limited. - 0737-3937 .- 1532-2300. ; 25:42193, s. 1149-1153
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Tidskriftsartikel (refereegranskat)abstract
- Microwave convective drying of plant foods is a promising process due to the shorter drying time and better product quality. High microwave power decreases the drying time but causes charring of the product. In this work, microwave drying under constant and variable microwave power were compared. Temperature-sensitive products, such as plant foods, are especially affected by microwave power during the final drying period. Therefore, drying at variable microwave power was found to be a more suitable drying process. Air (temperature and velocity) has an important role during microwave drying, not only as carrier of evaporated moisture but also as it contributes to a more homogeneous and faster drying.
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| 3. |
- Staack, N., et al.
(författare)
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Effect of infrared heating on quality and microbial decontamination in paprika powder
- 2008
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Ingår i: Journal of Food Engineering. - : Elsevier BV. - 0260-8774 .- 1873-5770. ; 86:1, s. 17-24
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Tidskriftsartikel (refereegranskat)abstract
- Infrared radiation (IR) was explored as a technique for decontaminating paprika powder. The effect of water activity (aw) and IR heat flux on paprika temperature and water loss were measured during near- or medium-IR heating. Paprika was evaluated in terms of colour, aw, natural flora, and inoculated Bacillus cereus spores. Surface temperatures were considerably higher than temperatures inside the powder, especially at low aw; greater differences were observed with medium- than with near-IR. Surface darkening was observed, though the overall colour was not considerably affected. IR effectively removed water from paprika, especially at aw 0.5 and 0.8, resulting in unsatisfactory spore reduction. However, at aw 0.8, the load of the natural flora was reduced (P < 0.05). In aw 0.96 powder, areas with high remaining aw displayed a reduction >6 log10 CFU/g for B. cereus (P < 0.05). In addition, no microbial counts of the natural background flora were observed in the paprika. © 2007 Elsevier Ltd. All rights reserved.
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| 4. |
- Staack, N., et al.
(författare)
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Effects of temperature, pH, and controlled water activity on inactivation of spores of Bacillus cereus in paprika powder by near-IR radiation
- 2008
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Ingår i: Journal of Food Engineering. - : Elsevier BV. - 0260-8774 .- 1873-5770. ; 89:3, s. 319-324
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Tidskriftsartikel (refereegranskat)abstract
- A process to decontaminate paprika powder using variable near-infrared (IR) radiation was tested using a closed sample holder allowing water to be retained in the powder. The reduction in the concentration of Bacillus cereus spores and changes in water activity (aw) and colour were measured during IR heating. High heat flux was applied initially to heat the powder rapidly to the desired temperature, followed by low heat flux to maintain the temperature for a given time. The water activity (aw) value of the powder could be maintained within the bulk of the closed sample, but the surface aw value decreased during heating. Due to carotenoid sensitivity to temperature, surface and overall colour values declined, though remaining acceptable values of medium red and red, respectively. For powder with an aw value of 0.88 heated to 95-100 °C, the load of B. cereus spores was reduced by 4.5 log10 CFU/g within 6 min; the final spore concentration remained approximately 2 log10 CFU/g due to tailing. Reducing pH to 4.0 from 4.5 did not significantly affect the reduction of the B. cereus spore concentration. © 2008 Elsevier Ltd. All rights reserved.
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