| 1. |
- Wadsö, Lars, et al.
(author)
-
Isothermal Titration Calorimetry in the Student Laboratory
- 2011
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In: Journal of Chemical Education. - : American Chemical Society (ACS). - 0021-9584 .- 1938-1328. ; 88:1, s. 101-105
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Journal article (peer-reviewed)abstract
- Isothermal titration calorimetry (ITC) is the measurement of the heat produced by the stepwise addition of one substance to another. It is a common experimental technique, for example, in pharmaceutical science, to measure equilibrium constants and reaction enthalpies. We describe a stirring device and an injection pump that can be used with a previously described isothermal calorimeter to perform ITC measurements. Two experiments are also described: an acid−base titration and the binding of Ba2+ to the macrocyclic compound 18-crown-6. These experiments visualize the difference between strong and weak interactions (large and small equilibrium constants) and introduce how reaction enthalpies and equilibrium constants can be calculated from titration calorimetric experiments.
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| 2. |
- Frühwald, Eva, et al.
(author)
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Image analysis study of mould susceptibility of spruce and larch wood dried or heat-treated at different temperatures
- 2008
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In: Wood Material Science & Engineering. - : Informa UK Limited. - 1748-0272 .- 1748-0280. ; 3:1-2, s. 55-61
-
Journal article (peer-reviewed)abstract
- In this study, mould growth on wood was investigated by image analysis. The studied parameters were drying and heat-treatment temperatures (20-210°C), original and resawn surface and different wood species (spruce and larch). Small specimens—some of which were inoculated with a spore suspension—were stored under humid conditions and photographed once a week. Mould growth was assessed by image analysis. In general, results found in earlier studies regarding the influence of several parameters could be confirmed. Image analysis was found to be a useful method to quantify mould growth in an objective and reproducible way.
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| 3. |
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| 4. |
- Jiang, Bowen, 1993, et al.
(author)
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A Novel Approach of Electric Powertrain Co-Simulation with High Fidelity Vehicle Model
- 2022
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In: IECON Proceedings (Industrial Electronics Conference). - 2577-1647 .- 2162-4704. ; 2022-October
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Conference paper (peer-reviewed)abstract
- This paper presents a co-simulation approach for an electric vehicle which combines dynamic models of electric machine, inverter, gearbox in PLECS with high fidelity models of driver, autobody, wheel, road and environment in CarMaker. Lumped parameter thermal networks to model heat dissipation in the electric machine and the inverter are also included. The aim is to demonstrate versatility of the co-simulation method in analyzing effects of driver behaviors on thermal performance of electric machine and inverter. Co-simulation results using two simulation tools are compared to those obtained entirely using a single tool. It is observed that performing co-simulation using low fidelity vehicle model results in underestimation of vehicle speed. Further, the impacts of three different driver models on the temperatures of electric machine windings and semiconductor junctions are analyzed. Differences of 30% and 25% in the maximum temperature are observed respectively between an aggressive and a defensive driver.
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| 5. |
- Jiang, Bowen, 1993, et al.
(author)
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Acceleration-based wheel slip control realized with decentralised electric drivetrain systems
- 2022
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In: IET Electrical Systems in Transportation. - : Institution of Engineering and Technology (IET). - 2042-9738 .- 2042-9746. ; 12:2, s. 143-152
-
Journal article (peer-reviewed)abstract
- Traction control is one of the most important functions in vehicle drivetrain systems. When a vehicle is driven on a low-friction road surface, loss of traction force can cause the driven wheels to spin. This reduces vehicle acceleration performance and can even cause the driver to lose control of the vehicle. The high bandwidth of electric machine control in electric vehicles gives more possibilities to regulate driving torque on wheels and prevent wheel spin. An acceleration-based wheel slip control is designed and investigated. Compared to traditional slip-based traction control, the proposed method does not depend on the estimation of the vehicle speed and only relies on the driven wheel rotational acceleration. The control method is verified using the simulation of an electric vehicle with a decentralised electric drivetrain system. The vehicle and the electric drive are modelled in CarMaker and PLECS, respectively. The simulation results show that the proposed method is able to prevent the driven wheel from spinning when the vehicle is accelerated on an ice road. In addition, the control is fast enough and requires only half a second to reduce the wheel acceleration to a normal range.
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| 6. |
- Jiang, Bowen, 1993, et al.
(author)
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Real-Time FPGA/CPU-Based Simulation of a Full-Electric Vehicle Integrated with a High-Fidelity Electric Drive Model
- 2022
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In: Energies. - : MDPI AG. - 1996-1073 .- 1996-1073. ; 15:5
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Journal article (peer-reviewed)abstract
- Real-time simulations refer to the simulations of a physical system where model equations for one time-step are solved within the same time period as in reality. An FPGA/CPU-based real-time simulation platform is presented in this paper, with a full-electric vehicle model implemented in a central processing unit (CPU) board and an electric drive model implemented in a field programmable gate arrays (FPGA) board. It has been a challenge to interface two models solved with two different processors. In this paper, one open-loop and three closed-loop interfaces are proposed. Real-time simulation results show that the best method is to transmit electric machine speed from the vehicle model to the electric derive model, with feedback electric machine torque calculated in FPGA. In addition, a virtual vehicle testing tool (CarMaker) is used when building the vehicle model, achieving more accurate modeling of vehicle subsystems. The presented platform can be used to verify advanced vehicle control functions during hardware-in-the-loop (HIL) testing. Vehicle anti-slip control is used as an example here. Finally, experiments were performed by connecting the real-time platform with a back-to-back electric machine test bench. Results of torque, rotor speed, and d&q axis currents are all in good agreement between simulations and experiments.
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| 7. |
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| 8. |
- Li, Bo, et al.
(author)
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Contact mechanism of a rock fracture subjected to normal loading and its impact on fast closure behavior during initial stage of fluid flow experiment
- 2015
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In: International Journal for Numerical and Analytical Methods in Geomechanics. - : Wiley. - 0363-9061 .- 1096-9853. ; 39:13, s. 1431-1449
-
Journal article (peer-reviewed)abstract
- Fast closure of rock fractures has been commonly observed in the initial stage of fluid flow experiments at environmental temperatures under low or moderate normal stresses. To fully understand the mechanisms that drive this fast closure, the evolution of local stresses acting on contacting asperities on the fracture surfaces prior to fluid flow tests needs to be evaluated. In this study, we modeled numerically the asperity deformation and failure processes during initial normal loading, by adopting both elastic and elastic-plastic deformation models for the asperities on a real rock fracture with measured surface topography data, and estimated their impact on initial conditions for fluid flow test performed under laboratory conditions. Compared with the previous models that simulate the normal contact of a fracture as the approach of two rigid surfaces without deformations, our models of deformable asperities yielded smaller contact areas and higher stresses on contacting asperities at a given normal stress or normal displacement. The results show that the calculated local stresses were concentrated on the contacts of a few major asperities, resulting in crushing of asperity tips. With these higher contact stresses, however, the predicted closure rates by pressure solution are still several orders of magnitude lower than that of the experimental measurements at the initial stage of fluid flow test. This indicates that single pressure solution may not likely to be the principal compaction mechanism for this fast closure, and that the damages on contacting asperities that occur during the initial normal loading stage may play an important role.
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| 9. |
- Li, Bo, et al.
(author)
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Experimental study of the hydro-mechanical behavior of rock joints using a parallel-plate model containing contact areas and artificial fractures
- 2008
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In: International Journal of Rock Mechanics And Mining Sciences. - : Elsevier BV. - 1365-1609 .- 1873-4545. ; 45:3, s. 362-375
-
Journal article (peer-reviewed)abstract
- In recent years, geological disposal of radioactive wastes is considered to be the most promising option, which requires the understanding of the coupled mechanical, hydraulic and thermal properties of the host rock masses and rock fractures. The hydro-mechanical behavior and properties of rock fractures are usually determined by laboratory experiments on fracture specimens that serve as the basic building block of the constitutive models of fractured rock masses. Laboratory testing of rock fractures involve a number of technical issues that may have significant impacts on the reliability and applicability of the testing results, chief among them are the quantitative estimation of the evolutions of hydraulic transmissivity fields of fractures during shear under different normal constraint conditions, and the sealing techniques when fluid flow during shear is involved. In this study, a new shear-flow testing apparatus with specially designed fluid sealing techniques for rock fractures were developed, under constant normal load (CNL) or constant normal stiffness (CNS) constraint. The topographical data of all fracture specimens were measured before testing to constitute the geometrical models for simulating the change of mechanical aperture distributions during shearing. A number of shear-flow coupling tests were carried out on three kinds of rock fracture specimens to evaluate the influence of morphological properties of rock fractures on their hydro-mechanical behaviour. Some empirical relations were proposed to evaluate the effects of contact area and surface roughness on the behavior of fluid flow through rock fractures.
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| 10. |
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| 11. |
- Li, Yujing
(author)
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Calorimetric methods for the study of fungi on building materials
- 2004
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Licentiate thesis (other academic/artistic)abstract
- The aim of this project is to study the fungal growth habits on building materials as a function of humidity, temperature and other environmental parameters. The method of calorimetry is used as a way to quantify fungal activity on building materials. Calorimetry is a general, but sensitive method that can continuously monitor biological processes as a function of environmental conditions. In this report, three different studies are presented: (1) A calorespirometric device was developed and used to study the energetics and gas exchange of one rot fungus and two mould fungi. (2) Calorimetry was correlated with the quantification of ergosterol, an established method in fungal research. It is shown that there is correlation between these two methods. (3) Calorimetry combined with equipment for humidity and temperature modification makes it possible to measure fungal activity at different temperature and humidity levels.
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| 12. |
- Li, Yujing, et al.
(author)
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Correlating two methods of quantifying fungal activity: Heat production by isothermal calorimetry and ergosterol amount by gas chromatography-tandem mass spectrometry
- 2007
-
In: Thermochimica Acta. - : Elsevier BV. - 0040-6031. ; 458:1-2, s. 77-83
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Journal article (peer-reviewed)abstract
- Two methods of quantifying fungal activity have been compared and correlated: isothermal calorimetry for measuring heat production and gas chromatography-tandem mass spectrometry (GC-MS/MS) for measuring ergosterol, a proxy for biomass. The measurements were made on four different fungi: Penicillium roqueforti, Cladosporiurn cladosporioides, Neopetromyces muricatus and the dry rot fungus Serpula lacrymans. The results showed linear correlations between ergosterol production and total heat production for these four fungal species during the initial fast growing stage. At the later stages heat was produced but ergosterol amount was constant. The heat produced per ergosterol amount varied from species to species and between different temperatures. This might be due to the different metabolic efficiencies of different species or the same species at different temperatures. Isothermal calorimetry can be used in fungal studies on its own or in combination with other techniques for a more complete understanding of fungal physiology.
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| 13. |
- Li, Yujing, et al.
(author)
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Fungal activities of indoor moulds on wood as a function of relative humidity during desorption and adsorption processes
- 2013
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In: Engineering in Life Sciences. - : Wiley. - 1618-2863 .- 1618-0240. ; 13:6, s. 528-535
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Journal article (peer-reviewed)abstract
- Activities of moulds from domestic dwellings are normally classified into three groupsprimary, secondary, and tertiary colonizersaccording to the minimum relative humidity they require to colonize a substrate. With the help of isothermal calorimetry it is possible to directly measure the thermal activity from moulds as a function of climatic parameters. This makes it possible to provide more precise and detailed information of the growth behavior of these types of moulds under different temperature and relative humidity level than traditional methods. From this study, it is found that the optimal relative humidities and the recovery from drying are different for these three different colonizers. The fungal activities during desorption process are higher than during adsorption processes under the same relative humidity level for all of the samples. Such information makes it possible to model mould behavior indoors and can be used to access the risk for mould growth in the buildings.
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| 14. |
- Li, Yujing, et al.
(author)
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Impact of temperature on growth and metabolic efficiency of Penicillium roqueforti - Correlations between produced heat, ergosterol content and biomass
- 2009
-
In: Journal of Applied Microbiology. - : Oxford University Press (OUP). - 1364-5072 .- 1365-2672. ; 106:Online 4 Feb 2009, s. 1494-1501
-
Journal article (peer-reviewed)abstract
- The influence of temperature on the growth of the mould Penicillium roqueforti growing on malt extract agar was studied by correlating the produced heat (measured by isothermal calorimetry), ergosterol content (quantified by GC-MS/MS) and biomass of the mould at 10, 15, 20, 25 and 30°C. The results were analysed with a simple metabolic model from which the metabolic efficiency was calculated. The results show that the impact of temperature on growth rate and metabolic efficiency are different: although the mould fungus had the highest growth rate (in terms of thermal power, which was continuously measured) at 25°C, the substrate carbon conversion efficiency (biomass production divided by substrate consumption, both counted as moles carbon) was highest at 20°C. The temperature of the most rapid growth did therefore not equal the temperature of the most efficient growth.
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| 15. |
- Li, Yujing, et al.
(author)
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Microbial growth in stored dust samples as a function of the relative humidity
- 2005
-
In: Indoor Air 2005: Proceedings of the 10th International Conference on Indoor Air Quality and Climate, Vols 1-5. - 7894948306 ; , s. 2435-2438
-
Conference paper (peer-reviewed)abstract
- House dusts, collected for detection of microorganisms in buildings, sometimes have to be stored before measurement. It is possible that continued growth of microorganisms in the stored samples will increase the levels of CFU, chemical marker, biomass etc. The aim of this investigation was to assess the influence of relative humidity on microbial growth in dust samples. We have exposed dust samples to different RH and measured their thermal activity with isothermal microcalorimetry. We also measured concentrations of the three microbial markers ergosterol (fungi), 3-OH fatty acids (Gram-negative bacterial), and muramic acid (Gram-positive bacteria) by GC-MS-MS. The calorimetric results showed that there were a significant biological activity in samples kept at 75 and 94% RH, but not at 54% RH. The marker for Gram-positive bacteria only showed an increase at the highest RH (94%). No changes were seen in the marker for Gram-negative bacteria. We conclude that at least fungi will continue to grow in dust which is kept at 75% RH and higher. Significantly higher amounts of ergosterol and other measures of fungal growth may be found in such samples after storage with higher humidity.
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| 16. |
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| 17. |
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| 18. |
- Li, Yujing
(author)
-
Mould on building materials - A calorimetric study of fungal activity as a function of environmental factors
- 2007
-
Doctoral thesis (other academic/artistic)abstract
- Mould problems in buildings have become a growing concern during the past decades. The growth of mould fungi indoors deteriorates air quality, influences human health and causes economical losses. Preventing mould growth from occurring is a more cost effective option than cleaning and renovation of buildings with mould problems. Mould growth will occur in buildings when there are moisture problems. Many constructions have various defects that cause high humidity or even condensation on cold surfaces. Some of these defects are avoidable and can be corrected at the design stage. A calculation tool and knowledge of mould growth behaviour as a function of environmental parameters are therefore needed to predict the risk of mould growth for building design. The aim of this project was to study mould behaviour on building materials as a function of environmental parameters, such as temperature and relative humidity and therefore to serve as a tool for preventing mould problems in buildings. Isothermal calorimetry is the main method used in this project to quantify mould activity. This method has not been applied much in fungal studies. Therefore it was tested and investigated to increase the understanding of the information that could be obtained from such measurements. Calorespirometry experiments (simultaneous calorimetry and respirometry) have been done on several mould fungi as well as on one rot fungus for understanding the correlation between fungal respiration and their heat production. Calorimetry was also compared with some traditional methods used in studying fungal growth by comparing heat produced by mould fungi with its biomass and ergosterol content. This also gave an increased understanding of fungal growth mechanisms. The results proved that calorimetry can not only be used on its own but can also be combined with other techniques to study fungal physiology. The impact of temperature on mould growth was studied by comparing the produced heat, biomass and ergosterol of mould at five different temperature levels. Mould growth is highly influenced by temperature and this study also showed that the temperature at which that mould has the most rapid growth is not necessary the temperature at which it has its most efficient growth. This finding reveals the complexity of the influence of temperature on the fungal metabolism. The influence of relative humidity on mould was also studied by measuring the fungal activities of mould growing on wood at different relative humidities. The results showed that although mould activities decreased when the relative humidity was low, too high relative humidity could also seem to inhibit part of its activity. Not only relative humidity but also moisture content is an important factor influencing mould activity. However the interpretation of these measurements was complicated by transient effects. Mould growth development on wood, which were dried and treated at different temperatures was also studied by image analysis. All kiln-dried material exhibited higher mould growth levels than the air-dried material. Spruce heartwood had better resistance against mould growth than spruce sapwood. Heat-treated spruce had very low levels of mould growth. The measurements confirmed that nutrient transport to the drying surface increases the risk of mould growth there.
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| 19. |
- Li, Yujing, et al.
(author)
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Simultaneous measurements of colony size and heat production rate of a mould (Penicillium brevicompactum) growing on agar
- 2011
-
In: Journal of Thermal Analysis and Calorimetry. - : Springer Science and Business Media LLC. - 1588-2926 .- 1388-6150 .- 1572-8943. ; 104:1, s. 105-111
-
Journal article (peer-reviewed)abstract
- Fungal colony size development, often measured as the increase in colony diameter, is used frequently as a parameter for presenting and modelling fungi's biomass growth. Another measure of fungal growth is the heat production rate (thermal power), which represents the metabolic activities of the fungi. In this study, the colony size and the heat production rate were simultaneously measured on a filamentous fungus, Penicillium brevicompactum, at five temperatures. The colony growth was recorded by digital photography and the colony size was quantified by image analysis. The heat production rate was measured by an isothermal calorimeter. The results showed that the growth of mould is temperature dependent. During the active growing stage, the colony size increase is correlated to the heat produced by the mould.
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| 20. |
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| 21. |
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| 22. |
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| 23. |
- Li, Zhongqiang, et al.
(author)
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Heat Waves Alter Macrophyte-Derived Detrital Nutrients Release under Future Climate Warming Scenarios
- 2021
-
In: Environmental Science and Technology. - : American Chemical Society (ACS). - 0013-936X .- 1520-5851. ; 55:8, s. 5272-5281
-
Journal article (peer-reviewed)abstract
- In addition to a rise in global air and water mean temperatures, extreme climate events such as heat waves are increasing in frequency, intensity, and duration in many regions of the globe. Developing a mechanistic understanding of the impacts of heat waves on key ecosystem processes and how they differ from just an increase in mean temperatures is therefore of utmost importance for adaptive management against effects of global change. However, little is known about the impact of extreme events on freshwater ecosystem processes, particularly the decomposition of macrophyte detritus. We performed a mesocosm experiment to evaluate the impact of warming and heat waves on macrophyte detrital decomposition, applied as a fixed increment (+4 °C) above ambient and a fluctuating treatment with similar energy input, ranging from 0 to 6 °C above ambient (i.e., simulating heat waves). We showed that both warming and heat waves significantly accelerate dry mass loss of the detritus and carbon (C) release but found no significant differences between the two heated treatments on the effects on detritus dry mass loss and C release amount. This suggests that moderate warming indirectly enhanced macrophyte detritus dry mass loss and C release mainly by the amount of energy input rather than by the way in which warming was provided (i.e., by a fixed increment or in heat waves). However, we found significantly different amounts of nitrogen (N) and phosphorus (P) released between the two warming treatments, and there was an asymmetric response of N and P release patterns to the two warming treatments, possibly due to species-specific responses of decomposers to short-term temperature fluctuations and litter quality. Our results conclude that future climate scenarios can significantly accelerate organic matter decomposition and C, N, and P release from decaying macrophytes, and more importantly, there are asymmetric alterations in macrophyte-derived detrital N and P release dynamic. Therefore, future climate change scenarios could lead to alterations in N/P ratios in the water column via macrophyte decomposition processes and ultimately affect the structure and function of aquatic ecosystems, especially in the plankton community.
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| 24. |
- Pedersen, Eja, et al.
(author)
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Challenges in transdisciplinary research : Example from a study on people as part of energy and ventilation systems in residential buildings (PEIRE)
- 2019
-
In: Cold Climate HVAC 2018 : Sustainable Buildings in Cold Climates - Sustainable Buildings in Cold Climates. - 9783030006617 - 9783030006624 ; , s. 802-812
-
Conference paper (peer-reviewed)abstract
- Energy efficiency measures in residential buildings typically include changes in ventilation and heating systems, and increased thermal insulation of the building envelope. The expected energy efficiency is not always reached, despite large knowledge and professional implementation of each separate measure. Thereis a lack in understanding of how technical systems interact, and how the ocupants are influenced by and in turn influence the systems by their behaviour. A holistic view and a transdisciplinary research approach are needed to understand relevant interactions and propose integrated energy efficiency measures. The aim of this paper is to reveal challenges in transdisciplinary research projects that include real world studies on both humans and technical systems with measurements before and after renovation of multifamily housing. It is based on experiences from the PEIRE-project (People, Environment, Indoor, Renovation, Energy) carried out by a research team with expertise on environmental psychology, human behaviour, interaction design, universal design, building physics, building services, thermal comfort, aerosol technology, exposure assessment, acoustics, daylight, and complex thinking. Differences in theoretical bases and methodology needed to be dealt with. Metatheory building could help with the transition from a multi- to a transdisciplinary understanding.
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| 25. |
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| 26. |
- Pedersen, Eja, et al.
(author)
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Challenges in Transdisciplinary Research—Example from a Study on People as Part of Energy and Ventilation Systems in Residential Buildings (PEIRE)
- 2018
-
In: Cold Climate HVAC 2018. - Cham : Springer. - 9783030006617 - 9783030006624 ; , s. 803-812
-
Book chapter (other academic/artistic)abstract
- Energy efficiency measures in residential buildings typically include changes in ventilation and heating systems, and increased thermal insulation of the building envelope. The expected energy efficiency is not always reached, despite large knowledge and professional implementation of each separate measure. There is a lack in understanding of how technical systems interact, and how the occupants are influenced by and in turn influence the systems by their behaviour. A holistic view and a transdisciplinary research approach are needed to understand relevant interactions and propose integrated energy efficiency measures. The aim of this paper is to reveal challenges in transdisciplinary research projects that include real world studies on both humans and technical systems with measurements before and after renovation of multifamily housing. It is based on experiences from the PEIRE-project (People, Environment, Indoor, Renovation, Energy) carried out by a research team with expertise on environmental psychology, human behaviour, interaction design, universal design, building physics, building services, thermal comfort, aerosol technology, exposure assessment, acoustics, daylight, and complex thinking. Differences in theoretical bases and methodology needed to be dealt with. Metatheory building could help with the transition from a multi- to a transdisciplinary understanding.
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| 27. |
- Pedersen, Eja, et al.
(author)
-
Good indoor environmental quality (IEQ) and high energy efficiency in multifamily dwellings: How do tenants view the conditions needed to achieve both?
- 2021
-
In: Building and Environment. - : Elsevier BV. - 0360-1323 .- 1873-684X. ; 191
-
Journal article (peer-reviewed)abstract
- Sustainable housing that both creates good indoor environmental quality (IEQ) and avoids unnecessary energy use has proved difficult to realize. Renovations of multifamily houses provide an opportunity to find this balance. This study concerns whether tenants perceive that conditions for achieving sufficient IEQ with low energy use exist. Focus group interviews with 42 participants, in areas where the rents were in the lower range and included heating up to 21 °C, aimed to capture the tenants' perceptions of: IEQ and actions taken to regulate it; information and control; the connections between IEQ and energy use; and the role of the housing company. Good IEQ was crucial to interviewees, who described it as sufficient heat without draughts, ability to ventilate, and no disturbing sounds or smells. The main responsibility was attributed to the housing company, but daily regulation controlled by tenants. However, unclear interfaces between tenants and the systems that regulate IEQ make it difficult for tenants to act as a positive part of the system. Tenants did not link IEQ to energy use. A holistic view of the physical environment's affordances, including intuitive interfaces, could optimize the balance between good IEQ and energy use.
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| 28. |
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| 29. |
- Wadsö, Lars, et al.
(author)
-
Measurements on two mould fungi with a calorespirometric method
- 2004
-
In: Thermochimica Acta. - : Elsevier BV. - 0040-6031. ; 422:1-2, s. 63-68
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Journal article (peer-reviewed)abstract
- This paper presents results from dynamic calorespirometric measurements on the two mould fungi Penicillium roqueforti and P. camemberti growing on agar. The measurements were made with two isothermal heat conduction calorimeters connected by a tube. In one of the calorimeters, the sample was placed and the other contained a carbon dioxide absorbent. Pressure sensors were connected to both the ampoules. The equipment also contained a valve on the tube that was opened and closed at regular intervals. Measurements were started at normal atmospheric pressure and gas composition, and continued after oxygen was consumed. The response of the fungi to the changing gas composition was followed and gas exchange ratios and metabolic enthalpies were calculated by approximate methods. (C) 2004 Published by Elsevier B.V.
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| 30. |
- Wang, Xiaoyu, et al.
(author)
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Associations of Insomnia With Insulin Resistance Traits : A Cross-sectional and Mendelian Randomization Study
- 2023
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In: Journal of Clinical Endocrinology and Metabolism. - : Endocrine Society. - 0021-972X .- 1945-7197. ; 108:8, s. e574-e582
-
Journal article (peer-reviewed)abstract
- Context: Insomnia is associated with insulin resistance (IR) in observational studies; however, whether insomnia is causally associated with IR remains unestablished.Objective: This study aims to estimate the causal associations of insomnia with IR and its related traits.Methods: In primary analyses, multivariable regression (MVR) and 1-sample Mendelian randomization (1SMR) analyses were performed to estimate the associations of insomnia with IR (triglyceride-glucose index and triglyceride to high-density lipoprotein cholesterol [TG/HDL-C] ratio) and its related traits (glucose level, TG, and HDL-C) in the UK Biobank. Thereafter, 2-sample MR (2SMR) analyses were used to validate the findings from primary analyses. Finally, the potential mediating effects of IR on the pathway of insomnia giving rise to type 2 diabetes (T2D) were examined using a 2-step MR design.Results: Across the MVR, 1SMR, and their sensitivity analyses, we found consistent evidence suggesting that more frequent insomnia symptoms were significantly associated with higher values of triglyceride-glucose index (MVR, beta = 0.024, P < 2.00E-16; 1SMR, beta = 0.343, P < 2.00E-16), TG/HDL-C ratio (MVR, beta = 0.016, P = 1.75E-13; 1SMR, beta = 0.445, P < 2.00E-16), and TG level (MVR, beta = 0.019 log mg/dL, P < 2.00E-16, 1SMR: beta = 0.289 log mg/dL, P < 2.00E-16) after Bonferroni adjustment. Similar evidence was obtained by using 2SMR, and mediation analysis suggested that about one-quarter (25.21%) of the association between insomnia symptoms and T2D was mediated by IR.Conclusions: This study provides robust evidence supporting that more frequent insomnia symptoms are associated with IR and its related traits across different angles. These findings indicate that insomnia symptoms can be served as a promising target to improve IR and prevent subsequent T2D.
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| 31. |
- Wierzbicka, Aneta, et al.
(author)
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Healthy Indoor Environments : The Need for a Holistic Approach
- 2018
-
In: International Journal of Environmental Research and Public Health. - : MDPI. - 1661-7827 .- 1660-4601. ; 15:9
-
Journal article (peer-reviewed)abstract
- Indoor environments have a large impact on health and well-being, so it is important to understand what makes them healthy and sustainable. There is substantial knowledge on individual factors and their effects, though understanding how factors interact and what role occupants play in these interactions (both causative and receptive) is lacking. We aimed to: (i) explore interactions between factors and potential risks if these are not considered from holistic perspective; and (ii) identify components needed to advance research on indoor environments. The paper is based on collaboration between researchers from disciplines covering technical, behavioural, and medical perspectives. Outcomes were identified through literature reviews, discussions and workshops with invited experts and representatives from various stakeholder groups. Four themes emerged and were discussed with an emphasis on occupant health: (a) the bio-psycho-social aspects of health; (b) interaction between occupants, buildings and indoor environment; (c) climate change and its impact on indoor environment quality, thermal comfort and health; and (d) energy efficiency measures and indoor environment. To advance the relevant research, the indoor environment must be considered a dynamic and complex system with multiple interactions. This calls for a transdisciplinary and holistic approach and effective collaboration with various stakeholders.
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| 32. |
- Zhao, Kefan, et al.
(author)
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High-Quality Solution-Processed Quasi-2D Perovskite for Low-Threshold Lasers
- 2024
-
In: ACS Applied Materials and Interfaces. - 1944-8244. ; 16:17, s. 22361-22368
-
Journal article (peer-reviewed)abstract
- Spin-coated quasi-two-dimensional halide perovskite films, which exhibit superior optoelectronic properties and environmental stability, have recently been extensively studied for lasers. Crystallinity is of great importance for the laser performance. Although some parameters related to the spin-coating process have been studied, the in-depth understanding and effective control of the acceleration rate on two-dimensional perovskite crystallization during spin-coating are still unknown. Here we investigate the effect of solvent evaporation on the microstructure of the final perovskite films during the spin-coating process. The crystallization quality of the film can be significantly improved by controlling solvent evaporation. As a result, the prepared quasi-2D perovskite film exhibits a stimulated emission threshold (pump: 343 nm, 6 kHz, 290 fs) of 550 nm as low as 16.2 μJ/cm2. Transient absorption characterization shows that the radiative biexciton recombination time is reduced from 738.5 to 438.3 ps, benefiting from the improved crystallinity. The faster biexciton recombination significantly enhanced the photoluminescence efficiency, which is critical for population inversion. This work could contribute to the development of low-threshold lasers.
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| 33. |
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