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In recent years, there has been a paradigm shift in the building sector towards more sustainable, resource efficient, and renewable materials. Bio-based insulation derived from renewable resources, such as plant or animal fibres, is one promising group of such materials. Compared to mineral wool and polystyrene-based insulation materials, these bio-based insulation materials generally have a slightly higher thermal conductivity, and they are significantly more hygroscopic, two factors that need to be considered when using these bio-based insulation materials. This study assesses the hygrothermal properties of three bio-based insulation materials: eelgrass, grass, and wood fibre. All three have the potential to be locally sourced in Sweden. Mineral wool (stone wool) was used as a reference material. Hygrothermal material properties were measured with dynamic vapour sorption (DVS), transient plane source (TPS), and sorption calorimetry. Moisture buffering of the insulation materials was assessed, and their thermal insulation capacity was tested on a building component level in a hot box that exposed the materials to a steady-state climate, simulating in-use conditions in, e.g., an external wall. The tested bio-based insulation materials have significantly different sorption properties to stone wool and have higher thermal conductivity than what the manufacturers declared. The hot-box experiments showed that the insulating capacity of the bio-based insulators cannot be reliably calculated from the measured thermal conductivity alone. The results of this study could be used as input data for numerical simulations and analyses of the thermal and hygroscopic behaviour of these bio-based insulation materials.

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In recent decades, the calorimetric monitoring of microbial metabolism, i [...].

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Horticultural crops have a low tolerance to dehydration. In this paper, we show that the reversible electroporation (200 monopolar, rectangular pulses of 50 µs pulse duration, 760 µs between pulses and nominal field strength of 650 V/cm) of Thai basil leaves followed by 24 h resting before hot air drying at 40 °C enhanced the survivability of the tissues at certain levels of dehydration (moisture ratio = 0.2 and 0.1). However, this increased survival was rather limited. Through measurements of metabolic heat production during resting, rehydration kinetics, respiration and photosynthesis of the rehydrated leaves, we show that resting after the application of a reversible pulse-electric field (PEF) may allow a phase of hardening that has a protective effect on the cells, thus decreasing damage during the subsequent drying phase. Increased preservation of cell vitality would be associated with a more turgid and fresh-like rehydrated product, as cells would have the capacity to retain the rehydration water.

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Blood samples are widely used for PCR-based DNA analysis in fields such as diagnosis of infectious diseases, cancer diagnostics, and forensic genetics. In this study, the mechanisms behind blood-induced PCR inhibition were evaluated by use of whole blood as well as known PCR-inhibitory molecules in both digital PCR and real-time PCR. Also, electrophoretic mobility shift assay was applied to investigate interactions between inhibitory proteins and DNA, and isothermal titration calorimetry was used to directly measure effects on DNA polymerase activity. Whole blood caused a decrease in the number of positive digital PCR reactions, lowered amplification efficiency, and caused severe quenching of the fluorescence of the passive reference dye 6-carboxy-X-rhodamine as well as the double-stranded DNA binding dye EvaGreen. Immunoglobulin G was found to bind to single-stranded genomic DNA, leading to increased quantification cycle values. Hemoglobin affected the DNA polymerase activity and thus lowered the amplification efficiency. Hemoglobin and hematin were shown to be the molecules in blood responsible for the fluorescence quenching. In conclusion, hemoglobin and immunoglobulin G are the two major PCR inhibitors in blood, where the first affects amplification through a direct effect on the DNA polymerase activity and quenches the fluorescence of free dye molecules, and the latter binds to single-stranded genomic DNA, hindering DNA polymerization in the first few PCR cycles. Graphical abstract PCR inhibition mechanisms of hemoglobin and immunoglobulin G (IgG). Cq quantification cycle, dsDNA double-stranded DNA, ssDNA single-stranded DNA.

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The impregnation of leafy vegetables with cryoprotectants using a combination of vacuum impregnation (VI) and pulsed electric fields (PEF) has been proposed by our research group as a method of improving their freezing tolerance and consequently their general quality after thawing. In this study, we have investigated the metabolic consequences of the combination of these unit operations on spinach. The vacuum impregnated spinach leaves showed a drastic decrease in the porosity of the extracellular space. However, at maximum weight gain, randomly located air pockets remained, which may account for oxygen-consuming pathways in the cells being active after VI. The metabolic activity of the impregnated leaves showed a drastic increase that was further enhanced by the application of PEF to the impregnated tissue. Impregnating the leaves with trehalose by VI led to a significant accumulation of trehalose-6-phosphate (T6P), however, this was not further enhanced by PEF. It is suggested that the accumulation of T6P in the leaves may increase metabolic activity, and increase tissue resistance to abiotic stress.

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A new vessel for simultaneous isothermal calorimetry and respirometry (calorespirometry) on terrestrial (non-aqueous) samples has been developed. All types of small (<1 g) biological samples (insects, soil, leaves, fungi, etc.) can be studied. The respirometric measurements are made by opening and closing a valve to a vial inside the sample ampoule containing a carbon dioxide absorbent. Typically a 7 h measurement results in seven measurements of heat production rate, oxygen consumption and carbon dioxide production, which can be used to evaluate how the metabolic activity in a sample changes over time. Results from three experiments on leaves, a cut vegetable, and mold are given. As uncertainties--especially in the carbon dioxide production--tend to be quite high, improvements to the technique are also discussed.

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Calorespirometry is the simultaneous measurement of heat and gas exchange from biological systems. Such measurements can be used to assess fundamental properties of many different types of systems from small ecosystems to isolated tissues. Techniques for calorespirometric measurements on terrestrial (non-aquatic) samples are described. Methods and models for evaluation of carbon conversion efficiencies, growth rates, and responses to environmental variables from calorespirometric measurements are described. A realistic model of the system under study is essential in the evaluation. Calorespirometry allows testing of models for tissues, individual organisms, and ecosystems.

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The water interactions of polymer electrolyte membranes are of significant interest when these materials are used in, for example, fuel cells. We have therefore studied the sorption thermodynamics of Nafion with a sorption calorimeter that simultaneously measures the sorption isotherm and the mixing (sorption) enthalpy. This unique method is suitable for investigating the sorption thermodynamics of ionic polymers. The measurements were made at 25 °C on a series of samples dried at different temperatures from 25 to 120 °C. The sorption isotherms indicate that the samples dried at 120 °C lost about 0.8 more water molecules per sulfonic group during the drying than did the samples dried at 25 °C, and this result was verified gravimetrically. The mixing enthalpies showed several peaks or plateaus for the samples dried at 60-120 °C. This behavior was seen up to about 2 water molecules per sulfonic group. As these peaks were not directly related to any feature in the sorption isotherm, they probably have their origin in a secondary process, such as a reorganization of the polymer.

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A calorimetric method to determine water activity covering the full range of the water activity scale is presented. A dry stream of nitrogen gas is passed either over the solution whose activity should be determined or left dry before it is saturated by bubbling through water in an isothermal calorimeter. The unknown activity is in principle determined by comparing the thermal power of vaporization related to the gas stream with unknown activity to that with zero activity. Except for three minor corrections (for pressure drop, non-perfect humidification, and evaporative cooling) the unknown water activity is calculated solely based on the water activity end-points zero and unity. Thus, there is no need for calibration with references with known water activities. The method has been evaluated at 30 °C by measuring the water activity of seven aqueous sodium chloride solutions ranging from 0.1 mol kg(-1) to 3 mol kg(-1) and seven saturated aqueous salt solutions (LiCl, MgCl(2), NaBr, NaCl, KCl, KNO(3), and K(2)SO(4)) with known water activities. The performance of the method was adequate over the complete water activity scale. At high water activities the performance was excellent, which is encouraging as many other methods used for water activity determination have limited performance at high water activities.

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Sorption balances are instruments in which samples are weighed as they are exposed to a programmed relative humidity (RH). Such instruments are used to measure sorption isotherms and to study solid-vapour interaction. There are different methods to validate the performance of the RH generation in such instruments by charging them with saturated salt solutions and ramping/stepping the RH past the deliquescence RH of the salts. In this paper, an improved approach to perform validation is presented, where the RH is kept stepwise constant at a quasi-randomly chosen set of RH-values above and below the deliquescence RH. From the rates of change of mass as a function of RH, it is possible to calculate the RH at which deliquescence takes place. This alternative method gives similar results as the slow ramp method, but it is less sensitive to disturbances and is less time consuming.

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Film formation from latex dispersions with varying concentrations of sodium dodecylsulfate (SDS) and sodium persulfate (NaPS) was studied with a sorption balance. The drying rate decreased significantly at a critical volume fraction of polymer (phi pc). Under constant drying conditions the phi pc varied due to differences in particle stabilization. In SDS containing samples, the droplets wetted larger areas, the film thicknesses decreased and, consequently, the initial evaporation rate was decreased. The decrease in the initial evaporation rate first continued with increasing SDS concentration but leveled off at an apparent critical micelle concentration (CMC). Samples containing NaPS had different types of film formation mechanisms with large variations in phi pc and the total drying time, which could be explained by differences in the electrostatic stabilization. For dialyzed dispersions containing no NaPS, phi pc was close to 0.7. In samples with medium high NaPS concentration a skin was formed at the air interface causing an early shift in the evaporation rate, resulting in 0.25

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We investigate how a small polar molecule, urea, can act to protect a phospholipid bilayer system against osmotic stress. Osmotic stress can be caused by a dry environment, by freezing, or by exposure to aqueous systems with high osmotic pressure due to solutes like in saline water. A large number of organisms regularly experience osmotic stress, and it is a common response to produce small polar molecules intracellularly. We have selected a ternary system of urea-water-dimyristoyl phosphatidylcholine (DMPC) as a model to investigate the molecular mechanism behind this protective effect, in this case, of urea, and we put special emphasis on the applications of urea in skin care products. Using differential scanning calorimetry, X-ray diffraction, and sorption microbalance measurements, we studied the phase behavior of lipid systems exposed to an excess of solvent of varying compositions, as well as lipid systems exposed to water at reduced relative humidities. From this, we have arrived at a rather detailed thermodynamic characterization. The basic findings are as follows: (i) In excess solvent, the thermally induced lipid phase transitions are only marginally dependent on the urea content, with the exception being that the P(beta) phase is not observed in the presence of urea. (ii) For lipid systems with limited access to solvent, the phase behavior is basically determined by the amount (volume) of solvent irrespective of the urea content. (iii) The presence of urea has the effect of retaining the liquid crystalline phase at relative humidities down to 64% (at 27 degrees C), whereas, in the absence of urea, the transition to the gel phase occurs already at a relative humidity of 94%. This demonstrates the protective effect of urea against osmotic stress. (iv) In skin care products, urea is referred to as a moisturizer, which we find slightly misleading as it replaces the water while keeping the physical properties unaltered. (v) In other systems, urea is known to weaken the hydrophobic interactions, while for the lipid system we find few signs of this loosening of the strong segregation into polar and apolar regions on addition of urea.

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