| 1. |
- Bargigia, Ilaria, et al.
(författare)
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Diffuse optical techniques applied to wood characterisation
- 2013
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Ingår i: Journal of Near Infrared Spectroscopy. - : SAGE Publications. - 0967-0335 .- 1751-6552. ; 21:4, s. 259-268
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Tidskriftsartikel (refereegranskat)abstract
- We propose an optical method for non-invasive characterisation of wood samples based on two optical techniques: time-resolved diffuse optical spectroscopy and gas in scattering media absorption spectroscopy. While the latter is sensitive to gases present inside wood pores, the former extracts information on the bulk material regarding light scattering and absorption. Measurements on spruce samples, cut along different wood fibre directions, are presented to show an example of the advantages of this combined approach: by applying these two non-destructive techniques together, in fact, relevant information on wood such as porosity, permeability and moisture content can be assessed. Furthermore, the chemical composition, internal structure and the anisotropy due to the wood fibres can be investigated.
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| 2. |
- Barup, Kerstin, et al.
(författare)
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Multi-disciplinary lidar applications
- 2010
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Ingår i: Laser Applications to Chemical, Security and Environmental Analysis, LACSEA 2010. - 2162-2701. - 9781557528803
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Konferensbidrag (refereegranskat)abstract
- Lidar is a powerful technique normally associated with atmospheric monitoring. However, lidar techniques, also of the laser-induced fluorescence and laser-induced breakdown spectroscopy varieties, provide many new possibilities in unconventional fields including cultural heritage and ecological applications.
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| 3. |
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| 4. |
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| 5. |
- Brydegaard, Mikkel, et al.
(författare)
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Feasibility study: fluorescence lidar for remote bird classification
- 2010
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Ingår i: Applied Optics. - 2155-3165. ; 49:24, s. 4531-4544
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Tidskriftsartikel (refereegranskat)abstract
- We present a method for remote classification of birds based on eye-safe fluorescence lidar techniques. Mechanisms of quenching are discussed. Plumage reflectance is related to plumage fluorescence. Laboratory measurements on reflectance and fluorescence are presented, as well as test-range measurements. Also we present examples of birds' in-flight lidar returns. The methods are suitable for studies of night migrating species and high-altitude classification with implications for the detailed understanding of bird migration and global virus spread. (C) 2010 Optical Society of America
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| 6. |
- Ferreira, Jorge A., et al.
(författare)
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Spent sulphite liquor for cultivation of an edible Rhizopus sp.
- 2012
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Ingår i: BioResources. - : North Carolina State University: College of Natural Resources. - 1930-2126. ; 7:1, s. 173-188
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Tidskriftsartikel (refereegranskat)abstract
- Spent sulphite liquor, the major byproduct from the sulphite pulp production process, was diluted to 50% and used for production of an edible zygomycete Rhizopus sp. The focus was on production, yield, and composition of the fungal biomass composition. The fungus grew well at 20 to 40°C, but 32°C was found to be preferable compared to 20 and 40°C in terms of biomass production and yield (maximum of 0.16 g/g sugars), protein content (0.50-0.60 g/g), alkali-insoluble material (AIM) (ca 0.15 g/g), and glucosamine content (up to 0.30 g/g of AIM). During cultivation in a pilot airlift bioreactor, the yield increased as aeration was raised from 0.15 to 1.0 vvm, indicating a high demand for oxygen. After cultivation at 1.0 vvm for 84 h, high yield and production of biomass (up to 0.34 g/g sugars), protein (0.30-0.50 g/g), lipids (0.02-0.07 g/g), AIM (0.16-0.28 g/g), and glucosamine (0.22-0.32 g/g AIM) were obtained. The fungal biomass produced from spent sulphite liquor is presently being tested as a replacement for fishmeal in feed for fish aquaculture and seems to be a potential source of nutrients and for production of glucosamine.
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| 7. |
- Guan, Zuguang, et al.
(författare)
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Insect monitoring with fluorescence lidar techniques: field experiments.
- 2010
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Ingår i: Applied Optics. - 2155-3165. ; 49:27, s. 5133-5142
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Tidskriftsartikel (refereegranskat)abstract
- Results from field experiments using a fluorescence lidar system to monitor movements of insects are reported. Measurements over a river surface were made at distances between 100 and 300 m, detecting, in particular, damselflies entering the 355 nm pulsed laser beam. The lidar system recorded the depolarized elastic backscattering and two broad bands of laser-induced fluorescence, with the separation wavelength at 500 nm. Captured species, dusted with characteristic fluorescent dye powders, could be followed spatially and temporally after release. Implications for ecological research are discussed.
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| 8. |
- Guan, Zuguang, et al.
(författare)
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Vertical lidar sounding of atomic mercury and nitric oxide in a major Chinese city
- 2010
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Ingår i: Applied Physics B. - : Springer Science and Business Media LLC. - 0946-2171 .- 1432-0649. ; 101:1-2, s. 465-470
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Tidskriftsartikel (refereegranskat)abstract
- Vertical range-resolved measurements of atmospheric pollutants were performed in a major city in southern China, employing a lidar system operating with an optical parametric oscillator transmitter. Recordings of atomic mercury (Hg) and nitric oxide (NO) absorbing in the deep-UV region were taken, yielding concentration profiles only attainable with lidar techniques. In particular, the potential influence of molecular oxygen in low-concentration mercury monitoring was elucidated. Diurnal observations are discussed and presented together with weather parameters.
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| 9. |
- Kroon, Renee, 1982, et al.
(författare)
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Effect of electron-withdrawing side chain modifications on the optical properties of thiophene-quinoxaline acceptor based polymers
- 2013
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Ingår i: Polymer. - : Elsevier BV. - 0032-3861. ; 54:4, s. 1285-1288
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Tidskriftsartikel (refereegranskat)abstract
- Four new thiophene-quinoxaline acceptor based polymers have been synthesized. The parent thiophene-quinoxaline acceptor based copolymer was modified by introducing different electron-withdrawing groups adjacent to the thiophene side group. The effect on the physical, electrochemical and optical properties of the polymer series is discussed with respect to the parent thiophene-quinoxaline acceptor based polymer. The side chain carbonyl from one modified monomer could conveniently be transformed to either a difluoromethylene or an -ylidene malononitrile group via carbonyl transformations. For all polymers incorporating an electron-withdrawing side group both the HOMO and especially the LUMO were significantly shifted away from vacuum while all exhibit enhanced light harvesting ability. Especially the incorporation of an -ylidine malononitrile side group increases both the spectral coverage and absorption coefficient. Incorporation of a difluoromethylene side group resulted in a twofold increase of the molecular weight compared to the parent polymer structure.
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| 10. |
- Lagerqvist, Bo, et al.
(författare)
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Outcomes 1 year after thrombus aspiration for myocardial infarction.
- 2014
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Ingår i: New England Journal of Medicine. - : Massachusetts Medical Society. - 0028-4793 .- 1533-4406. ; 371:12, s. 1111-1120
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Tidskriftsartikel (refereegranskat)abstract
- Routine intracoronary thrombus aspiration before primary percutaneous coronary intervention (PCI) in patients with ST-segment elevation myocardial infarction (STEMI) has not been proved to reduce short-term mortality. We evaluated clinical outcomes at 1 year after thrombus aspiration.
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| 11. |
- Lewander, Märta, et al.
(författare)
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Non-intrusive measurements of headspace gas composition in liquid food packages made of translucent materials
- 2011
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Ingår i: Packaging Technology & Science. - : Wiley. - 0894-3214. ; 24:5, s. 271-280
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Tidskriftsartikel (refereegranskat)abstract
- The increase in chilled food consumption requires enhanced food safety and quality assurance. Food deteriorating processes are affected by the presence of oxygen, combined with factors such as time and temperature. To slow down deterioration processes and prolong shelf life, traditional packaging methods are being replaced by Modified Atmosphere Packaging (MAP), for example. Oxygen, which is naturally present in the headspace of most food packages, is then reduced and controlled. Many sensing techniques for food quality assurance have been developed; however, almost all are intrusive, increasing the complication level and causing sample waste. The purpose of this article is to introduce a non-intrusive technique (GASMAS) for measuring gas composition in the headspace of liquid food packages. The GASMAS method uses diode laser absorption spectroscopy combined with diffuse light propagation to analyze gas located inside solids and liquids. By illuminating the package from the outside and analyzing the scattered light that emerges, the absorption from the gas inside the headspace can be studied. The GASMAS technique was evaluated on a series of carton packages with high quality orange juice and a nitrogen headspace. A clear variation in oxygen content was measured for samples with different storage times. The results demonstrate the possibility of using the GASMAS method for non-intrusive quality measurements in food products and packaging. They also indicate the potential for non-intrusive quality assurance applications without waste of samples. A further development of the technique could include “in-line” quality control of packed food items throughout the food packaging supply chain.
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| 12. |
- Lundin, Patrik, et al.
(författare)
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Active feedback regulation of a Michelson interferometer to achieve zero-background absorption measurements
- 2011
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Ingår i: Applied Optics. - 2155-3165. ; 50:3, s. 373-378
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Tidskriftsartikel (refereegranskat)abstract
- An active phase-controlling scheme based on a proportional-integral-derivative-controlled piezoelectric transducer is presented with the purpose of stabilizing a quasi-zero-background absorption spectrometer. A fiber-based balanced Michelson interferometer is used, and absorption due to a gas sample in one of its arms results in an increased light signal to a detector, which otherwise, thanks to destructive interference, experiences a very low light level. With the presented approach, the sensitivity of already potent absorption measurement techniques, e.g., based on modulation, could be improved even further. (C) 2011 Optical Society of America
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| 13. |
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| 14. |
- Lundin, Patrik, et al.
(författare)
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Gas Monitoring in Human Body Cavities Using Non-Intrusive Diode Laser Absorption Spectroscopy
- 2012
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Ingår i: 2012 Asia Communications and Photonics Conference. - : IEEE. - 2162-108X. ; , s. 4-7
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Konferensbidrag (refereegranskat)abstract
- Diode laser absorption spectroscopy was utilized for non-intrusive assessment of gas content in human body cavities, including intestines and lungs of a new-born, the mastoid bone, and sinus cavities for monitoring sinusitis recovery in adults.
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| 15. |
- Lundin, Patrik
(författare)
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Laser Sensing for Quality Control and Classification – Applications for the Food Industry, Ecology and Medicine
- 2014
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Monitoring constitutes a cornerstone, both for efficient control of optimized industrial processes and for obtaining knowledge about non-controlled, natural phenomena. This thesis is all about monitoring, or measurements. In this case the primary information is gathered with light, and in a non-intrusive, and usually a stand-off or remote way. The applications of optical monitoring in this work are directed towards some main areas: atmospheric gas monitoring, the food industry, ecology, and medicine. Some of the work cannot be classified as belonging solely to one of those groups, but is instead aimed at improving optical monitoring in general. Monitoring of gases in food packaging is the primary area within the food industry explored in the work of this thesis. A current trend is that food is increasingly often packed in so called modified atmospheres, where the air surrounding the product in the package has been replaced by another gas mixture. Monitoring is currently performed by intrusive spot-checks on a small number of packages, to make sure that they are actually tight enough to maintain the modified atmosphere all the way from manufacturing to the kitchen of the consumer. The studies in this thesis aim at introducing non-intrusive methods based on diode laser absorption spectroscopy, by which the gas in the packages may be checked, and re-checked, without breaking the seal. A long-term goal that could be realized with this technique is that more packages could be checked, perhaps on the production line and, at later stages, in the store. Waste could in this way be reduced if poor packing can be avoided, or remade, and the packing process and materials improved. The results are so far very promising and one specific technique variety was commercialized during the time of this thesis work. Diode laser spectroscopy has also been used in the medical field, where the primary goal was to introduce a way to monitor the air distribution in the lungs and intestines of prematurely born children. Both of these organs are often affected by a premature birth, and our results indicate that spectroscopic gas monitoring could be helpful. Interestingly enough, the techniques used for these medical measurements and for the packaging industry applications are almost identical. Apart from the work related to the food's packaging a pair of studies were also performed on the ``food" directly, namely on apple tissue and on tea. In a study of gas exchange in apples it was found, to our surprise, that apple pieces exposed to vacuum could maintain a low internal pressure for hours after re-exposure to ambient pressure. In a study on tea, fluorescence spectroscopy was evaluated as a means to obtain information on the quality of the product with a rapid, stand-off technique. A good correlation was found between the assessment by tea tasting experts and the fluorescence technique. Fluorescence spectroscopy was also used in this work on other organic materials, in the field of ecology where damselflies and birds were studied with the light detection and ranging (LIDAR) technique. Harmless pulses of UV laser radiation were emitted in a beam out into the atmosphere. The UV radiation induces fluorescence in the feathers of the birds and the abdomen and wings of the damselflies. The spectral features of the fluorescence are characteristic for different species, genders, or other characteristics, of the animals, and the technique can therefore be used for classification. The analogy with the tea study is strong. %A variety LIDAR was also employed for monitoring of gaseous mercury and nitric oxide in the atmosphere.
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| 16. |
- Lundin, Patrik, et al.
(författare)
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Laser spectroscopic gas concentration measurements in situations with unknown optical path length enabled by absorption line shape analysis
- 2013
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Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 103:3
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Tidskriftsartikel (refereegranskat)abstract
- The concentrations of molecular oxygen and nitrogen in a gas mixture were determined by their impact on the shape of a water vapor line in the near infrared region using diode laser absorption spectroscopy. The shape of the water vapor line depends on the composition of other gases in the mixture and can therefore be used to deduce the concentration of partner molecules, e. g., oxygen, in the buffer. The method enables gas concentration measurements in situations when the path length is unknown, measurements of many gases simultaneously, and measurements of gases lacking suitable absorption lines. (C) 2013 AIP Publishing LLC.
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| 17. |
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| 18. |
- Lundin, Patrik, et al.
(författare)
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Non-intrusive headspace gas measurements by laser spectroscopy – Performance validation by a reference sensor
- 2012
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Ingår i: Journal of Food Engineering. - : Elsevier BV. - 0260-8774. ; 111:4, s. 612-617
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Tidskriftsartikel (refereegranskat)abstract
- Abstract in UndeterminedThe oxygen concentration in the headspace of a large number of liquid food containers is assessed with non-intrusive diode laser absorption spectroscopy. The results are compared to those given by a traditional intrusive measurement method. The upper portions of the containers are made of translucent but non-transparent plastic materials, through which the laser light is diffusively transmitted. Measurements are performed both on packages with modified atmosphere and with normal air conditions. It is concluded that the novel non-intrusive technique provides oxygen concentrations that generally differ by less than one percentage point from the reference sensor values.
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| 19. |
- Lundin, Patrik, et al.
(författare)
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Non-invasive gas monitoring in newborn infants using diode laser absorption spectroscopy: A case study
- 2012
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Ingår i: Optical Diagnostics and Sensing XII: Toward Point-of-Care Diagnostics; and Design and Performance Validation of Phantoms Used in Conjunction with Optical Measurement of Tissue IV. - : SPIE. - 1996-756X .- 0277-786X. ; 8229
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Konferensbidrag (refereegranskat)abstract
- Non-invasive diode laser spectroscopy was, for the first time, used to assess gas content in the intestines and the lungs of a new-born, 4 kg, baby. Two gases, water vapor and oxygen, were studied with two low-power tunable diode lasers, illuminating the surface skin tissue and detecting the diffusely emerging light a few centimeters away. The light, having penetrated into the tissue, had experienced absorption by gas located in the lungs and in the intestines. Very distinct water vapor signals were obtained from the intestines while imprint from oxygen was lacking, as expected. Detectable, but minor, signals of water vapor were also obtained from the lungs, illuminating the armpit area and detecting below the collar bone. Water vapor signals were seen but again oxygen signals were lacking, now due to the difficulties of penetration of the oxygen probing light into the lungs of this full-term baby. Ultra-sound images were obtained both from the lungs and from the stomach of the baby. Based on dimensions and our experimental findings, we conclude, that for early pre-term babies, also oxygen should be detectable in the lungs, in addition to intestine and lung detection of water vapor. The present paper focuses on the studies of the intestines while the lung studies will be covered in a forthcoming paper.
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| 20. |
- Lundin, Patrik, et al.
(författare)
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Noninvasive monitoring of gas in the lungs and intestines of newborn infants using diode lasers: feasibility study.
- 2013
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Ingår i: Journal of Biomedical Optics. - 1083-3668. ; 18:12
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Tidskriftsartikel (refereegranskat)abstract
- ABSTRACT. Preterm newborn infants have a high morbidity rate. The most frequently affected organs where free gas is involved are the lungs and intestines. In respiratory distress syndrome, both hyperexpanded and atelectatic (collapsed) areas occur, and in necrotizing enterocolitis, intramural gas may appear in the intestine. Today, these conditions are diagnosed with x-ray radiography. A bed-side, rapid, nonintrusive, and gas-specific technique for in vivo gas sensing would improve diagnosis. We report the use of noninvasive laser spectroscopy, for the first time, to assess gas content in the lungs and intestines of three full-term infants. Water vapor and oxygen were studied with two low-power diode lasers, illuminating the skin and detecting light a few centimeters away. Water vapor was easily detected in the intestines and was also observed in the lungs. The relatively thick chest walls of the infants prevented detection of the weaker oxygen signal in this study. However, results from a previous phantom study, together with scaling of the results presented here to the typical chest-wall thickness of preterm infants, suggest that oxygen also should be detectable in their lungs.
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| 21. |
- Lundin, Patrik, et al.
(författare)
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Passive unmanned sky spectroscopy for remote bird classification
- 2011
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Ingår i: Remote Sensing For Agriculture, Ecosystems, And Hydrology XIII. - : SPIE. - 0277-786X .- 1996-756X. ; 8174
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Konferensbidrag (refereegranskat)abstract
- We present a method based on passive spectroscopy with aim to remotely study flying birds. A compact spectrometer is continuously recording spectra of a small section of the sky, waiting for birds to obscure part of the field-of-view when they pass the field in flight. In such situations the total light intensity received through the telescope, looking straight up, will change very rapidly as compared to the otherwise slowly varying sky light. On passage of a bird, both the total intensity and the spectral shape of the captured light changes notably. A camera aimed in the same direction as the telescope, although with a wider field-of-view, is triggered by the sudden intensity changes in the spectrometer to record additional information, which may be used for studies of migration and orientation. Example results from a trial are presented and discussed. The study is meant to explore the information that could be gathered and extracted with the help of a spectrometer connected to a telescope. Information regarding the color, size and height of flying birds is discussed. Specifically, an application for passive distance determination utilizing the atmospheric oxygen A-band absorption at around 760 nm is discussed.
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| 22. |
- Lundin, Patrik, et al.
(författare)
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Remote nocturnal bird classification by spectroscopy in extended wavelength ranges
- 2011
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Ingår i: Applied Optics. - 2155-3165. ; 50:20, s. 3396-3411
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Tidskriftsartikel (refereegranskat)abstract
- We present optical methods at a wide range of wavelengths for remote classification of birds. The proposed methods include eye-safe fluorescence and depolarization lidar techniques, passive scattering spectroscopy, and infrared (IR) spectroscopy. In this paper we refine our previously presented method of remotely classifying birds with the help of laser-induced beta-keratin fluorescence. Phenomena of excitation quenching are studied in the laboratory and are theoretically discussed in detail. It is shown how the ordered microstructures in bird feathers induce structural "colors" in the IR region with wavelengths of around 3-6 mu m. We show that transmittance in this region depends on the angle of incidence of the transmitted light in a species-specific way and that the transmittance exhibits a close correlation to the spatial periodicity in the arrangement of the feather barbules. We present a method by which the microstructure of feathers can be monitored in a remote fashion by utilization of thermal radiation and the wing beating of the bird. (C) 2011 Optical Society of America
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| 23. |
- Mei, Liang, et al.
(författare)
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Characterization and validation of the frequency-modulated continuous-wave technique for assessment of photon migration in solid scattering media
- 2012
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Ingår i: Applied physics. B, Lasers and optics (Print). - : Springer Nature. - 0946-2171 .- 1432-0649. ; 109:3, s. 467-475
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Tidskriftsartikel (refereegranskat)abstract
- The frequency-modulated continuous-wave (FM-CW) technique, based on the beat signal of a Mach-Zehnder interferometer employing a frequency-ramped light source, is studied for solid scattering media applications. The method is used to evaluate the mean time-of-flight (MTOF) of light traveling in scattering media, specifically polystyrene foams. We assume that each the time-of-flight (TOF) time corresponds to different light scattering paths resulting in a different phase shift. The phase shift variations produce a speckle pattern, which together with the frequency leakage induced by the discrete Fourier transform (DFT) cause "spikes" in the power spectrum of the beat signal, thus decreasing the accuracy of the measured MTOF values in solid scattering media. For comparison, time-of-flight spectroscopy (TOFS) is also employed to evaluate the MTOF for the same samples, while the geometrical difference between these two techniques is compensated for by using diffusion theory. The MTOFs measured by the FMCW and TOFS techniques agree well, which demonstrates a great potential to develop a robust FMCW setup for simplified MTOF assessment.
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| 24. |
- Mei, Liang, et al.
(författare)
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First attempt to monitor atmospheric glyoxal using differential absorption lidar
- 2012
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Ingår i: Proceedings of the SPIE. - : SPIE. ; 853412
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Konferensbidrag (refereegranskat)abstract
- Glyoxal (CHOCHO), as an indicator of photochemical “hot spots”, was for the first time the subject of a differential absorption lidar (DIAL) campaign. The strongest absorption line of glyoxal in the blue wavelength region – 455.1 nm – was chosen as the experimental absorption wavelength. In order to handle the effects of absorption cross-section variation of the interfering gas – nitrogen dioxide (NO2) – three-wavelength DIAL measurements simultaneously detecting glyoxal and NO2, were performed. The differential absorption curves, recorded in July 2012, indicate an extremely low glyoxal concentration in Lund, Sweden, although it is expected to be peaking at this time of the year.© (2012) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
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| 25. |
- Mei, Liang, et al.
(författare)
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Gas spectroscopy and optical path-length assessment in scattering media using a frequency-modulated continuous-wave diode laser
- 2011
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Ingår i: Optics Letters. - : Optica Publishing Group. - 0146-9592 .- 1539-4794. ; 36:16, s. 3036-3038
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Tidskriftsartikel (refereegranskat)abstract
- Simultaneous assessment of the spectroscopic absorption signal of gas enclosed in a scattering medium and the corresponding optical path length of the probing light is demonstrated using a single setup. Sensitive gas absorption measurements are performed by a tunable diode laser using wavelength-modulation spectroscopy, while the path length is evaluated by the frequency-modulated cw technique commonly used in the field of telecommunication. Proof-of-principle measurements are demonstrated with water vapor as the absorbing gas and using polystyrene foam as an inhomogeneously scattering medium. The combination of these techniques opens up new possibilities for straightforward evaluation of gas presence and exchange in scattering media.
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| 26. |
- Mei, Liang, et al.
(författare)
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Tea classification and quality assessment using laser-induced fluorescence and chemometric evaluation
- 2012
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Ingår i: Applied Optics. - 1559-128X .- 2155-3165. ; 51:7, s. 803-811
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Tidskriftsartikel (refereegranskat)abstract
- Laser-induced fluorescence was used to evaluate the classification and quality of Chinese oolong teas and jasmine teas. The fluorescence of four different types of Chinese oolong teas-Guangdong oolong, North Fujian oolong, South Fujian oolong, and Taiwan oolong was recorded and singular value decomposition was used to describe the autofluoresence of the tea samples. Linear discriminant analysis was used to train a predictive chemometric model and a leave-one-out methodology was used to classify the types and evaluate the quality of the tea samples. The predicted classification of the oolong teas and the grade of the jasmine teas were estimated using this method. The agreement between the grades evaluated by the tea experts and by the chemometric model shows the potential of this technique to be used for practical assessment of tea grades.
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| 27. |
- Mill, O., et al.
(författare)
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Analysis and development of hydro power research : synthesis within Swedish Hydro Power Centre
- 2010
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- The market for hydropower re-investments in Sweden is approx 2.5 billion SEK/yr the coming decade. Large investments will also be carried out in Swedish tailing dams. This will result in challenging projects and need of experts. A crucial factor for a successful management of these challenges is the supply of engineers and researchers with hydro power and dam skills and knowledge. Swedish Hydro Power Centre (Svenskt vattenkraftcentrum, SVC) is a competence centre for university education and research environments within hydro power and mining dams. SVC comprises of two knowledge areas: Hydraulic Engineering and Hydro Turbines and Generators, respectively. SVC builds high-quality and long term sustainable knowledge at selected universities...
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| 28. |
- Nyman, Jonas, et al.
(författare)
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Pellet formation of zygomycetes and immobilization of yeast
- 2013
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Ingår i: New Biotechnology. - : Elsevier BV. - 1871-6784 .- 1876-4347. ; 30:5, s. 516-522
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Tidskriftsartikel (refereegranskat)abstract
- Pelleted growth provides many advantages for filamentous fungi, including decreased broth viscosity, improved aeration, stirring, and heat transfer. Thus, the factors influencing the probability of pellet formation of Rhizopus sp. in a defined medium was investigated using a multifactorial experimental design. Temperature, agitation intensity, Ca2+-concentration, pH, and solid cellulose particles, each had a significant effect on pelletization. Tween 80, spore concentration, and liquid volume were not found to have a significant effect. All of the effects were additive; no interactions were significant. The results were used to create a simple defined medium inducing pelletization, which was used for immobilization of a flocculating strain of Saccharomyces cerevisiae in the zygomycetes pellets. A flor-forming S. cerevisiae strain was also immobilized, while a non-flocculating strain colonized the pellets but was not immobilized. No adverse effects were detected as a result of the close proximity between the filamentous fungus and the yeast, which potentially allows for co-fermentation with S. cerevisiae immobilized in pellets of zygomycetes
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| 29. |
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| 30. |
- Tylewicz, Urszula, et al.
(författare)
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Gas in Scattering Media Absorption Spectroscopy (GASMAS) Detected Persistent Vacuum in Apple Tissue After Vacuum Impregnation
- 2012
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Ingår i: Food Biophysics. - : Springer Science and Business Media LLC. - 1557-1866 .- 1557-1858. ; 7:1, s. 28-34
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Tidskriftsartikel (refereegranskat)abstract
- The microstructure and the capillary pressure of the pore space are important variables for better understanding of the complex phenomena occurring during vacuum impregnation (VI) of plant tissues. In this study, we used GASMAS (Gas in Scattering Media Absorption Spectroscopy) of oxygen to, non-destructively, measure the dynamics of the internal pressure in apple pieces after restoration of the atmospheric pressure. Apple pieces were impregnated with isotonic sucrose solution (18% w/v) at different reduced pressures (15, 30, 45 kPa (abs.)). After restoration of the atmospheric pressure, the pressure of the remaining pore space gas could remain as low as 50 kPa (abs) and rise slowly toward ambient over a time scale of hours. Both the residual vacuum and the timescale of pressure equilibration with ambient varied with applied vacuum level and apple variety. It is proposed that at least a part of the pore space of apples may be hydrophobic, giving rise to a negative Laplace pressure, and thus the convective flow of impregnating solution is arrested at a mechanical equilibrium where internal pressure is lower than external pressure. Further pressure equilibration can then only be achieved either by gas diffusion in gas phase, or by gradual wetting of the pores.
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| 31. |
- Zhuang, Wenliu, 1979, et al.
(författare)
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Influence of Incorporating Different Electron-Rich Thiophene-Based Units on the Photovoltaic Properties of Isoindigo-Based Conjugated Polymers: An Experimental and DFT Study
- 2013
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Ingår i: Macromolecules. - : American Chemical Society (ACS). - 1520-5835 .- 0024-9297. ; 46:21, s. 8488-8499
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Tidskriftsartikel (refereegranskat)abstract
- A series of novel donor–acceptor conjugated alternating copolymers based on the isoindigo acceptor moiety have been designed, synthesized, and characterized, in order to explore the potential of isoindigo for efficient donor materials with high photovoltages in solar cells. We have systematically investigated and discussed the effect of combining different electron-rich thiophene-based units on the structural, optical, electronic, and photovoltaic properties of the resulting polymers. Morphological studies and quantum-chemical calculations are carried out to gain insights into the different properties. The power conversion efficiencies (PCEs) of the solar cells based on these polymers are increased step by step by over 3-fold through a rational structural modification. Among them, PBDTA-MIM shows a PCE of 5.4%, which is to our knowledge the best result achieved among isoindigo-based polymers for solar cells combined with PC61BM as the acceptor using the conventional device configuration. Our results further emphasize the use of isoindigo as an effective acceptor unit and highlight the importance of carefully choosing appropriate chemical structure to design efficient donor–acceptor polymers for organic solar cells. In addition, the resulting low optical gaps, the promising PCEs with PC61BM as the acceptor, and the good open-circuit voltages (up to 0.8 V) synergistically demonstrate the potential of this class of polymers as donor materials for bottom subcells in organic tandem solar cells.
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