Danish Technological Institute
Recent publications
Airtight energy-efficient buildings of today need efficient ventilation to secure high indoor air quality. There is a need for affordable and reliable sensors to make demand control available in a broad range of ventilation systems. Low-cost metal oxide semiconductor (MOS) volatile organic compound (VOC) sensors offer such a possibility, but they are usually non-selective and react to broad range of compounds. The objective of the present paper was to use cluster analysis to assess the ability of five commercially available MOS VOC sensors to detect pollutants in a residential setting. We studied three scenarios: emissions from people (human bioeffluents), furnishing materials (linoleum), and human activity (surface cleaning with spray detergent). We monitored each scenario with five MOS VOC sensors and a proton-transfer-reaction–time-of-flight mass spectrometer (PTR-ToF-MS). We applied an agglomerative hierarchical clustering algorithm to evaluate the dissimilarity between clusters. Four of the five tested sensors produced signals in agreement with the concentration patterns measured with the PTR-ToF-MS; one sensor underperformed in all cases. Three sensors showed a very similar performance under all emission scenarios. The results showed that the clustering could help in understanding whether a particular sensor matched the intended emission scenario.
IntroductionThe objective of the study was to investigate long-term food intake patterns and establish possible associations between the inferred dietary habits and levels of reported symptoms among people with multiple sclerosis (MS) in Denmark.Methods The present study was designed as a prospective cohort study. Participants were invited to register daily food intake and MS symptoms and were observed during a period of 100 days. Dropout and inclusion probabilities were addressed using generalized linear models. Dietary clusters were identified among 163 participants using hierarchical clustering on principal component scores. Associations between the dietary clusters and the levels of self-assessed MS symptoms were estimated using inverse probability weighting. Furthermore, the effect of a person’s position on the first and second principal dietary component axis on symptom burden was investigated.ResultsThree dietary clusters were identified: a Western dietary cluster, a plant-rich dietary cluster and a varied dietary cluster. Analyses further indicated a vegetables-fish-fruit-whole grain axis and a red-meat-processed-meat axis. The plant-rich dietary cluster showed reduction in symptom burden in nine pre-defined MS symptoms compared to the Western dietary cluster (between 19 and 90% reduction). This reduction was significant for pain and bladder dysfunction as well as across all nine symptoms (pooled p value = 0.012). Related to the two dietary axes, high intake of vegetables resulted in 32–74% reduction in symptom burden compared to low levels of vegetable intake. Across symptoms, this was significant (pooled p value = 0.015), also regarding walking difficulty and fatigue.Conclusions Three dietary clusters were identified. Compared to levels of self-assessed MS-related symptoms, and adjusted for potential confounders, the results suggested less symptom burden with increased intake of vegetables. Although the research design limits the possibilities of establishing causal inference, the results indicate that general guidelines for healthy diet may be relevant as a tool in coping with MS symptoms.
Background: Smartphones are often equipped with inertial sensors that measure individuals' physical activities. However, their role in remote monitoring of the patients' physical activities in telemedicine needs to be adequately explored. Objective: The main objective of this study was to explore the correlation between a participant's actual daily step counts and the daily step counts reported by their smartphone. In addition, we inquired about the usability of using smartphones for collecting physical activity data. Methods: This prospective observational study was conducted on patients undergoing lower limb orthopedic surgery and a group of non-patients as control. The data from the patients were collected from 2 weeks before surgery until four weeks after the surgery, while the data collection period for the non-patients was two weeks. The participant's daily step count was recorded by physical activity trackers employed 24/7. In addition, a smartphone application collected the number of daily steps registered by the participants' smartphones. We compared the cross-correlation between the daily steps time-series taken from the smartphones and physical activity trackers in different groups of participants. We also employed mixed modeling to estimate the total number of steps, using smartphone step counts and the characteristics of the patients as independent variables. The System Usability Scale was used to evaluate the participants' experience with the smartphone application and the physical activity tracker. Results: Overall, 1067 days of data were collected from 21 patients (11 females) and 10 non-patients (6 females). The median and IQR for the cross-correlation coefficient on the same day was 0.70 [0.53-0.83]. The correlation in the non-patients was slightly higher than in the patients (0.74 [0.60-0.90] and 0.69 [0.52-0.81], respectively). The likelihood ratio tests on the models fitted by mixed effect methods demonstrated that the smartphone step count was positively correlated with the physical activity tracker's total number of steps (χ2 = 34.7, p < .00001). In addition, the usability score for the smartphone app was 78 [73-88] compared to 73 [68-80] for the PA tracker. Conclusions: Considering the ubiquity, convenience, and practicality of smartphones, the high correlation between the smartphones and the total daily step count time-series highlights the potential usefulness of smartphones in detecting the change in the number of steps in remote monitoring of the patient's physical activity.
Hybrid plasmas have been reported in various areas of research over the last 40 years. However, a general overview of hybrid plasmas has never been presented or reported. In the present work, a survey of the literature and patents is carried out to provide the reader with a broad view of hybrid plasmas. The term refers to several different configurations of plasmas, including but not limited to: plasmas driven by several power sources simultaneously or sequentially, plasmas that have the properties of both thermal and nonthermal plasmas, plasmas that are enhanced by additional energy, and plasmas that are operated in a unique medium. In addition, a way of evaluating hybrid plasmas in terms of the improvement of processes is discussed, as well as the negative impacts that follow the employment of hybrid plasmas. Regardless of what the hybrid plasma in question is composed of, it often poses a unique advantage to its nonhybrid counterpart, whether it be used for welding, surface treatment, materials synthesis, coating deposition, gas phase reactions, or medicine.
A new in vitro chronic wound biofilm model was recently published, which provided a layered scaffold simulating mammalian tissue composition on which topical wound care products could be tested. In this paper, we updated the model even further to mimic the dynamic influx of nutrients from below as is the case in a chronic wound. The modified in vitro model was created using collagen instead of agar as the main matrix component and contained both Staphylococcus aureus and Pseudomonas aeruginosa. The model was cast in transwell inserts and then placed in wound simulating media, which allowed for an exchange of nutrients and waste products across a filter. Three potential wound care products and chlorhexidine digluconate 2% solution as a positive control were used to evaluate the model. The tested products were composed of hydrogels made from completely biodegradable starch microspheres carrying different active compounds. The compounds were applied topically and left for 2-4 days. Profiles of oxygen concentration and pH were measured to assess the effect of treatments on bacterial activity. Confocal microscope images were obtained of the models to visualise the existence of microcolonies. Results showed that the modified in vitro model maintained a stable number of the two bacterial species over 6 days. In untreated models, steep oxygen gradients developed and pH increased to >8.0. Hydrogels containing active compounds alleviated the high oxygen consumption and decreased pH drastically. Moreover, all three hydrogels reduced the colony forming units significantly and to a larger extent than the chlorhexidine control treatment. Overall, the modified model expressed several characteristics similar to in vivo chronic wounds. This article is protected by copyright. All rights reserved.
Recent policies and research articles call for turning AI into a form of IA ('intelligence augmentation'), by envisioning systems that center on and enhance humans. Based on a field study at an AI company, this article studies how AI is performed as developers enact two predictive systems along with stakeholders in public sector accounting and public sector healthcare. Inspired by STS theories about values in design, we analyze our empirical data focusing especially on how objectives, structured performances, and divisions of labor are built into the two systems and at whose expense. Our findings reveal that the development of the two AI systems is informed by politically motivated managerial interests in cost-efficiency. This results in AI systems that are (1) designed as managerial tools meant to enable efficiency improvements and cost reductions, and (2) enforced on professionals on the 'shop floor' in a top-down manner. Based on our findings and a discussion drawing on literature on the original visions of human-centered systems design from the 1960s, we argue that turning AI into IA seems dubious, and ask what human-centered AI really means and whether it remains an ideal not easily realizable in practice. More work should be done to rethink human-machine relationships in the age of big data and AI, in this way making the call for ethical and responsible AI more genuine and trustworthy.
Fibre-reinforced epoxy composites are well established in regard to load-bearing applications in the aerospace, automotive and wind power industries, owing to their light weight and high durability. These composites are based on thermoset resins embedding glass or carbon fibres¹. In lieu of viable recycling strategies, end-of-use composite-based structures such as wind turbine blades are commonly landfilled1–4. Because of the negative environmental impact of plastic waste5,6, the need for circular economies of plastics has become more pressing7,8. However, recycling thermoset plastics is no trivial matter1–4. Here we report a transition-metal-catalysed protocol for recovery of the polymer building block bisphenol A and intact fibres from epoxy composites. A Ru-catalysed, dehydrogenation/bond, cleavage/reduction cascade disconnects the C(alkyl)–O bonds of the most common linkages of the polymer. We showcase the application of this methodology to relevant unmodified amine-cured epoxy resins as well as commercial composites, including the shell of a wind turbine blade. Our results demonstrate that chemical recycling approaches for thermoset epoxy resins and composites are achievable.
Surface tensions of solid materials have been studied over 200 years and widely used for industrial or engineering applications. The surface tensions and surface tension components can be calculated using measured contact angles, for example, by the model studied by Owens and Wendt. The model is often represented in an asymmetric linear form, called the Owens-Wendt-Rabel-Kaelble method, with the use of the linear least squares method. However, due to the practical preference not to use many types of test liquids, the existing statistical analysis is unsuitable, especially when the data measured are scattered. The present work proposes symmetric linear and circular expressions of the model of the two surface tension components. The symmetric linear expression can be used for obtaining the polar and dispersion components of surface tension of a solid; it enables appropriate choices for test liquids, physically meaningful screening of measured values, and clear validation of deduced surface tension components of solids. The symmetric circular expressions can be applied to deduce polar and dispersion components of liquids by using test solids. In conjunction with this, appropriate choices of test solids can be determined.
The enzymes of microorganisms that live in cold environments must be able to function at ambient temperatures. Cold-adapted enzymes generally have less ordered structures that convey a higher catalytic rate, but at the cost of lower thermodynamic stability. In this study, we characterized P355, a novel intracellular subtilisin protease (ISP) derived from the genome of Planococcus halocryophilus Or1, which is a bacterium metabolically active down to −25°C. P355′s stability and activity at varying pH values, temperatures, and salt concentrations, as well as its temperature-dependent kinetics, were determined and compared to an uncharacterized thermophilic ISP (T0099) from Parageobacillus thermoglucosidasius , a previously characterized ISP (T0034) from Planococcus sp. AW02J18, and Subtilisin Carlsberg (SC). The results showed that P355 was the most heat-labile of these enzymes, closely followed by T0034. P355 and T0034 exhibited catalytic constants ( k cat ) that were much higher than those of T0099 and SC. Thus, both P355 and T0034 demonstrate the characteristics of the stability-activity trade-off that has been widely observed in cold-adapted proteases.
Mutations in BRAF exon 15 lead to conformational changes in its activation loops, resulting in constitutively active BRAF proteins which are implicated in the development of several human cancer types. Different BRAF inhibitors have been developed and introduced in clinical practice. Identification of BRAF mutations influences the clinical evaluation, treatment, progression and for that reason a sensitive and specific identification of BRAF mutations is on request from the clinic. Here we present the SensiScreen® FFPE BRAF qPCR Assay that uses a novel real-time PCR-based method for BRAF mutation detection based on PentaBases proprietary DNA analogue technology designed to work on standard real-time PCR instruments. The SensiScreen® FFPE BRAF qPCR Assay displays high sensitivity, specificity, fast and easy-to-use. The SensiScreen® FFPE BRAF qPCR Assay was validated on two different FFPE tumour biopsy cohorts, one cohort included malignant melanoma patients previously analyzed by the Cobas® 4800 BRAF V600 Mutation Test, and one cohort from colorectal cancer patients previously analyzed by mutant-enriched PCR and direct sequencing. All BRAF mutant malignant melanoma patients were confirmed with the SensiScreen® FFPE BRAF qPCR Assay and additional four new mutations in the malignant melanoma cohort were identified. All the previously identified BRAF mutations in the colorectal cancer patients were confirmed, and additional three new mutations not identified with direct sequencing were detected. Also, one new BRAF mutation not previously identified with ME-PCR was found. Furthermore, the SensiScreen® FFPE BRAF qPCR Assay identified the specific change in the amino acid. The SensiScreen® FFPE BRAF qPCR Assay will contribute to a more specific, time and cost saving approach to better identify and characterize mutations in patients affected by cancer, and consequently permits a better BRAF characterization that is fundamental for therapy decision.
This study presents the results of a set of large‐scale fire tests performed on horizontal polyurethane foam slabs. Slab thickness, ignition location, and environment (free burn or corner wall) were varied over 23 individual tests. In a continuation of a previous study by the authors, four different slab thicknesses, five different ignition locations, and three environmental modification combinations were tested to examine the potential effects these parameters may have on the test outcomes. Wall configurations were composed of either gypsum plaster board or particle board wall linings and enclosed two sides of the foam slabs. The results obtained were heat release rate, peak HRR, total heat release, and effective heat of combustion, smoke production rate, total smoke production, specific extinction area and soot yield along with flame spread rate calculations obtained using a specifically designed sample tray. These were then analysed to quantify the effects of the test input parameter changes. Results highlight the influence of test input parameter changes on almost all the chosen fire metrics analysed. Slab thickness showed relatively straight forward linear changes to global metrics such as total heat release and total smoke production, while effective heat of combustion showed no change. The smoke production parameters of specific extinction area and soot yield showed minor trends towards higher values with increased slab thickness. Flame spread rates also showed an increased velocity with thicker slabs. Changes to the environment surrounding the foam slabs, from a free‐burning scenario to a corner wall configuration that obstructed two sides of the foam slab generally resulted in faster growth of HRR and higher peak values when compared to the free‐burn tests. This outcome was most obvious for the wall tests using combustible materials, where growth rates were comparative to an ultra‐fast t^2 fire, and peak HRR value rose to over triple that of the free‐burn test results. Flame spread rates were highly impacted by the addition of a corner wall, spread rates increased, and the overall pattern of spread rates across the face of the slabs changed entirely. The influence on smoke production values was minor, and for other smoke metrics, the scenario changes showed little influence. However, the values obtained for soot yields were approximately an order of magnitude lower than those given in standard reference books, such as the SFPE handbook for flexible polyurethane foam. This was an interesting additional finding as soot yield values are often directly used in CFD models to simulate smoke spread and determine life safety criteria in fire safety engineering (FSE).
DS 490:2018 "Akustik - Lydklassifikation af boliger", translated to "Acoustics - Acoustic Classification of Dwellings" relates to many acoustical parameters, and two of them "Noise from ventilation" and "Reverberation times" are now being tested in real life in the Danish "Voluntary sustainability classification".(Called FBK) Danish building regulation state a sound level limit in dwellings from all kinds of technical systems at 30 dB(A), equal to the Acoustical class C, comparable with the limit in several countries. Research shows that 30 dB(A) does not ensure acoustic satisfying comfort for most people. The FBK have chosen to lower the noise limit to 25 dB(A), equal to acoustical class B. We need to improve the ventilation systems in order to reach such lower level of sound emission, and to be able to measure it implemented in dwellings. The paper describes some methods and in situ experience fighting background noise problems caused by activities around and in the dwelling, as well as in the measurement systems. Special analyses and editing of recordings based on listening and pragmatic judgements are relevant. The goal is: Measure and document low noise without a cost in time and money being a barrier for lower noise levels in dwellings.
Seaweeds (macroalgae) are gaining attention as potential sustainable feedstock for the production of fuels and chemicals. This comparative study focuses on the characterization of the microbial production of alcohols from fermentable carbohydrates in the hydrolysate of the macroalgae Laminaria digitata as raw material. The potential of a hydrolysate as a carbon source for the production of selected alcohols was tested, using three physiologically different fermentative microbes, in two main types of processes. For the production of ethanol, Saccharomyces cerevisiae was used as a benchmark microorganism and compared with the strictly anaerobic thermophile Thermoanaerobacterium strain AK17. For mixed production of acetone/isopropanol, butanol, and ethanol (A/IBE), three strictly anaerobic Clostridium strains were compared. All strains grew well on the hydrolysate, and toxicity constraints were not observed, but fermentation performance and product profiles were shown to be both condition- and strain-specific. S. cerevisiae utilized only glucose for ethanol formation, while strain AK17 utilized glucose, mannitol, and parts of the glucan oligosaccharides. The clostridia strains tested showed different nutrient requirements, and were able to utilize glucan, mannitol, and organic acids in the hydrolysate. The novelty of this study embodies the application of different inoculates for fermenting a common brown seaweed found in the northern Atlantic Ocean. It provides important information on the fermentation properties of different microorganisms and pinpoints the value of carbon source utilization when selecting microbes for efficient bioconversion into biofuel and chemical products of interest.
Cold Water Extraction (CWE) is a technique used to extract the pore solution of cementitious materials and to study its alkalinity. CWE can be used on paste, mortar or concrete, and requires only standard laboratory equipment. The method is not yet standardised, so several parameters must be arbitrarily selected when conducting the test. This work investigated the influence of four parameters on the calculated alkali metal concentrations in the pore solution: the method for determining the amount of pore solution (oven-drying at 40 and 105°C, desiccator with silica gel and solvent exchange), the size fraction of the powdered material, the leaching duration and the liquid-to-solid ratio. A comparison with values obtained by Pore Water Extraction (PWE) on two cement types emphasises and quantifies the crucial impact of the amount of pore solution on CWE results. The results suggest that some bound alkali metals may be released during CWE. A mechanism is proposed, and recommendations are made to limit any effect of this on CWE results.
This paper presents a scoping review of methods for fire evacuation training in buildings. It adopts the PRISMA methodology (Transparent Reporting of Systematic Reviews and Meta-Analyses) and systematically identifies 73 sources among scientific literature published between 1997 and 2022. It was found that the literature is dominated by research on modern technology (Augmented Reality, Virtual Reality, Serious Games) for evacuation training emphasizing that increased immersion, engagement, and realism positively affect learning effects. These technologies may be able to overcome main drawbacks of traditional evacuation drills bringing down cost and reducing the disruptiveness of evacuation training. However, great inconsistencies in measuring performance of trainees and lack of reasoning in the design of training programmes impede conclusions that go beyond qualitative trends. The field would profit from clear methodologies to assess evacuation performance and training effects and from transdisciplinary approaches aimed at ensuring that training can deliver on its educational goals.
In this study ignition of premixed ammonia was tested using a compression-ignited (CI) pilot fuel. n-heptane (C7H16) was used as pilot fuel, injected with a GDI injector, enabling very small pilot fuel injections. With this setup, the engine was run using up to 98.5 % energy from ammonia – higher than seen in other CI-engine studies with ammonia at the time of writing. The ammonia energy contribution was varied 80–98.5 %, while keeping the total λ-value constant. An important result observed was an increase in combustion efficiency from 81%–90% with higher ammonia energy due to a lower local λ-value of the ammonia–air mixture, indicating that for ammonia-ignition an easily ignitable ammonia–air mixture is preferable compared to a strong pilot injection. Lean ammonia–air mixtures showed a gap in heat release between the pilot and ammonia combustion phases, which lowered the combustion efficiency. Increased ammonia energy led to reduced ammonia-slip and N2O-emissions and increased NO-emissions, and a lower CO-formation showed better pilot fuel oxidation.
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305 members
Marchen Hviid
  • Danish Meat Research Institute
Dimitar Karakashev
  • Biomass and Biorefinery
Mari Ann Tørngren
  • Meat Technology
Lotte Bjerrum
  • School of Life Sciences
Anne Belinda Bjerre
  • Climate and Energy
Kongsvang Allé, 8000, Taastrup, Denmark