| 1. |
- Minelli, Caterina, et al.
(författare)
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Versailles project on advanced materials and standards (VAMAS) interlaboratory study on measuring the number concentration of colloidal gold nanoparticles
- 2022
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Ingår i: Nanoscale. - : Royal Society of Chemistry (RSC). - 2040-3372 .- 2040-3364. ; 14, s. 4690-4704
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Tidskriftsartikel (refereegranskat)abstract
- We describe the outcome of a large international interlaboratory study of the measurement of particle number concentration of colloidal nanoparticles, project 10 of the technical working area 34, "Nanoparticle Populations" of the Versailles Project on Advanced Materials and Standards (VAMAS). A total of 50 laboratories delivered results for the number concentration of 30 nm gold colloidal nanoparticles measured using particle tracking analysis (PTA), single particle inductively coupled plasma mass spectrometry (spICP-MS), ultraviolet-visible (UV-Vis) light spectroscopy, centrifugal liquid sedimentation (CLS) and small angle X-ray scattering (SAXS). The study provides quantitative data to evaluate the repeatability of these methods and their reproducibility in the measurement of number concentration of model nanoparticle systems following a common measurement protocol. We find that the population-averaging methods of SAXS, CLS and UV-Vis have high measurement repeatability and reproducibility, with between-labs variability of 2.6%, 11% and 1.4% respectively. However, results may be significantly biased for reasons including inaccurate material properties whose values are used to compute the number concentration. Particle-counting method results are less reproducibile than population-averaging methods, with measured between-labs variability of 68% and 46% for PTA and spICP-MS respectively. This study provides the stakeholder community with important comparative data to underpin measurement reproducibility and method validation for number concentration of nanoparticles.
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| 2. |
- Martinez Avila, Hector, 1985, et al.
(författare)
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Novel bilayer bacterial nanocellulose scaffold supports neocartilage formation in vitro and in vivo
- 2015
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Ingår i: Biomaterials. - : Elsevier BV. - 0142-9612 .- 1878-5905. ; 44, s. 122-133
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Tidskriftsartikel (refereegranskat)abstract
- Tissue engineering provides a promising alternative therapy to the complex surgical reconstruction of auricular cartilage by using ear-shaped autologous costal cartilage. Bacterial nanocellulose (BNC) is proposed as a promising scaffold material for auricular cartilage reconstruction, as it exhibits excellent biocompatibility and secures tissue integration. Thus, this study evaluates a novel bilayer BNC scaffold for auricular cartilage tissue engineering. Bilayer BNC scaffolds, composed of a dense nanocellulose layer joined with a macroporous composite layer of nanocellulose and alginate, were seeded with human nasoseptal chondrocytes (NC) and cultured invitro for up to 6 weeks. To scale up for clinical translation, bilayer BNC scaffolds were seeded with a low number of freshly isolated (uncultured) human NCs combined with freshly isolated human mononuclear cells (MNC) from bone marrow in alginate and subcutaneously implanted in nude mice for 8 weeks. 3D morphometric analysis showed that bilayer BNC scaffolds have a porosity of 75% and mean pore size of 50±25μm. Furthermore, endotoxin analysis and invitro cytotoxicity testing revealed that the produced bilayer BNC scaffolds were non-pyrogenic (0.15±0.09EU/ml) and non-cytotoxic (cell viability: 97.8±4.7%). This study demonstrates that bilayer BNC scaffolds offer a good mechanical stability and maintain a structural integrity while providing a porous architecture that supports cell ingrowth. Moreover, bilayer BNC scaffolds provide a suitable environment for culture-expanded NCs as well as a combination of freshly isolated NCs and MNCs to form cartilage invitro and invivo as demonstrated by immunohistochemistry, biochemical and biomechanical analyses.
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| 3. |
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| 4. |
- Asplund, Teo, et al.
(författare)
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Adaptive Mathematical Morphology on Irregularly Sampled Signals in Two Dimensions
- 2020
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Ingår i: Mathematical Morphology : Theory and Applications. - : Walter de Gruyter. - 2353-3390. ; 4:1, s. 108-126
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Tidskriftsartikel (refereegranskat)abstract
- This paper proposes a way of better approximating continuous, two-dimensional morphologyin the discrete domain, by allowing for irregularly sampled input and output signals. We generalizeprevious work to allow for a greater variety of structuring elements, both flat and non-flat. Experimentallywe show improved results over regular, discrete morphology with respect to the approximation ofcontinuous morphology. It is also worth noting that the number of output samples can often be reducedwithout sacrificing the quality of the approximation, since the morphological operators usually generateoutput signals with many plateaus, which, intuitively do not need a large number of samples to be correctlyrepresented. Finally, the paper presents some results showing adaptive morphology on irregularlysampled signals.
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| 5. |
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| 6. |
- Asplund, Teo
(författare)
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Precise Image-Based Measurements through Irregular Sampling
- 2019
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Mathematical morphology is a theory that is applicable broadly in signal processing, but in this thesis we focus mainly on image data. Fundamental concepts of morphology include the structuring element and the four operators: dilation, erosion, closing, and opening. One way of thinking about the role of the structuring element is as a probe, which traverses the signal (e.g. the image) systematically and inspects how well it "fits" in a certain sense that depends on the operator.Although morphology is defined in the discrete as well as in the continuous domain, often only the discrete case is considered in practice. However, commonly digital images are a representation of continuous reality and thus it is of interest to maintain a correspondence between mathematical morphology operating in the discrete and in the continuous domain. Therefore, much of this thesis investigates how to better approximate continuous morphology in the discrete domain. We present a number of issues relating to this goal when applying morphology in the regular, discrete case, and show that allowing for irregularly sampled signals can improve this approximation, since moving to irregularly sampled signals frees us from constraints (namely those imposed by the sampling lattice) that harm the correspondence in the regular case. The thesis develops a framework for applying morphology in the irregular case, using a wide range of structuring elements, including non-flat structuring elements (or structuring functions) and adaptive morphology. This proposed framework is then shown to better approximate continuous morphology than its regular, discrete counterpart.Additionally, the thesis contains work dealing with regularly sampled images using regular, discrete morphology and weighting to improve results. However, these cases can be interpreted as specific instances of irregularly sampled signals, thus naturally connecting them to the overarching theme of irregular sampling, precise measurements, and mathematical morphology.
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| 7. |
- Taal, Cees H., et al.
(författare)
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A Short-Time Objective Intelligibility Measure for Time-Frequency Weighted Noisy Speech
- 2010
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Konferensbidrag (refereegranskat)abstract
- Existing objective speech-intelligibility measures are suitable for several types of degradation, however, it turns out that they are less appropriate for methods where noisy speech is processed by a time-frequency (TF) weighting, e.g., noise reduction and speech separation. In this paper, we present an objective intelligibility measure, which shows high correlation (rho=0.95) with the intelligibility of both noisy, and TF-weighted noisy speech. The proposed method shows significantly better performance than three other, more sophisticated, objective measures. Furthermore, it is based on an intermediate intelligibility measure for short-time (approximately 400 ms) TF-regions, and uses a simple DFT-based TF-decomposition. In addition, a free Matlab implementation is provided.
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| 8. |
- Taal, Cees H., et al.
(författare)
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An Algorithm for Intelligibility Prediction of Time-Frequency Weighted Noisy Speech
- 2011
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Ingår i: IEEE Transactions on Audio, Speech, and Language Processing. - 1558-7916 .- 1558-7924. ; 19, s. 2125-2136
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Tidskriftsartikel (refereegranskat)abstract
- In the development process of noise-reduction algorithms, an objective machine-driven intelligibility measure which shows high correlation with speech intelligibility is of great interest. Besides reducing time and costs compared to real listening experiments, an objective intelligibility measure could also help provide answers on how to improve the intelligibility of noisy unprocessed speech. In this paper, a short-time objective intelligibility measure (STOI) is presented, which shows high correlation with the intelligibility of noisy and time-frequency weighted noisy speech (e.g., resulting from noise reduction) of three different listening experiments. In general, STOI showed better correlation with speech intelligibility compared to five other reference objective intelligibility models. In contrast to other conventional intelligibility models which tend to rely on global statistics across entire sentences, STOI is based on shorter time segments (386 ms). Experiments indeed show that it is beneficial to take segment lengths of this order into account. In addition, a free Matlab implementation is provided.
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| 9. |
- Taal, Cees. H., et al.
(författare)
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An evaluation of objective measures for intelligibility prediction of time-frequency weighted noisy speech
- 2011
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Ingår i: Journal of the Acoustical Society of America. - : Acoustical Society of America (ASA). - 0001-4966. ; 130, s. 3013-3027
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Tidskriftsartikel (refereegranskat)abstract
- Existing objective speech-intelligibility measures are suitable for several types of degradation, however, it turns out that they are less appropriate in cases where noisy speech is processed by a time-frequency weighting. To this end, an extensive evaluation is presented of objective measure for intelligibility prediction of noisy speech processed with a technique called ideal time frequency (TF) segregation. In total 17 measures are evaluated, including four advanced speech-intelligibility measures (CSII, CSTI, NSEC, DAU), the advanced speech-quality measure (PESQ), and several frame-based measures (e.g., SSNR). Furthermore, several additional measures are proposed. The study comprised a total number of 168 different TF-weightings, including unprocessed noisy speech. Out of all measures, the proposed frame-based measure MCC gave the best results (rho = 0.93). An additional experiment shows that the good performing measures in this study also show high correlation with the intelligibility of single-channel noise reduced speech.
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| 10. |
- Taal, Cees H., et al.
(författare)
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An Evaluation of Objective Quality Measures for Speech Intelligibility Prediction
- 2009
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Konferensbidrag (refereegranskat)abstract
- In this research various objective quality measures are evaluated in order to predict the intelligibility for a wide range of non-linearly processed speech signals and speech degraded by additive noise. The obtained results are compared with the prediction results of a more advanced perceptual-based model proposed by Dau et al. and an objective intelligibility measure, namely the coherence speech intelligibility index (cSII). These tests are performed in order to gain more knowledge between the link of speech-quality and speech-intelligibility and may help us to exploit the extensive research done into the field of speech-quality for speech-intelligibility. It is shown that cSII does not necessarily show better performance compared to conventional objective (speech)-quality measures. In general, the DAU-model is the only method with reasonable results for all processing conditions.
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