| 1. |
- Adlerberth, Josefin, et al.
(författare)
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Thermometric analysis of blood metabolites in ICU patients
- 2020
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Ingår i: Journal of Thermal Analysis and Calorimetry. - : Springer Science and Business Media LLC. - 1388-6150 .- 1588-2926. ; 140:2, s. 763-771
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Tidskriftsartikel (refereegranskat)abstract
- Real-time monitoring of patient’s blood metabolites, such as glucose and lactate, could potentially improve surgery and recovery outcomes for patients in surgical and intensive care units. Our enzyme thermometric biosensor which is based on flow injected calorimetric determination of immobilized enzyme reaction is capable of performing continuous, fast, and quantitative analysis of metabolites using whole blood. A key technical advantage the assay affords is the ability to use unpretreated whole blood. In this article, the enzyme thermometric biosensor was used, for the first time, to determine glucose and lactate concentrations in the blood of ICU patients. The linear detection range for glucose was 0.5–30 mM and 0.25–12 mM for lactate, using a 20 μL sample volume. A maximum sampling rate of 15 measurements per hour was achieved using venous blood samples, which corresponds to a 4-min measurement interval. In order to validate the accuracy of the results, a comparative analysis between the thermometric biosensor and the clinically applied instrument (LifeScan’s OneTouch®) which is based on disposable dry chemical reaction was performed using samples from 33 patients. The results showed a good correlation between the two methods for both glucose (r = 0.843, p < 0.0001) and lactate (r = 0.78, p = 0.0105). The ability to monitor metabolite levels and trends on a clinically relevant timescale of 5 min is critical for intensive monitoring of ICP and operative patients.
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| 2. |
- Ahangar Zonouzi, S., et al.
(författare)
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Experimental study of the subcooled flow boiling heat transfer of magnetic nanofluid in a vertical tube under magnetic field
- 2020
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Ingår i: Journal of thermal analysis and calorimetry (Print). - : Springer. - 1388-6150 .- 1588-2926. ; 140:6, s. 2805-2816
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Tidskriftsartikel (refereegranskat)abstract
- In this study, the subcooled boiling heat transfer of a Fe3O4/water magnetic nanofluid flowing through a vertical tube has been investigated experimentally in the presence and absence of a magnetic field. The magnetic field has been generated by quadrupole magnets. The subcooled boiling heat transfer coefficient and the boiling curves of the ferrofluid flow under the action of the magnetic field have been compared with those in the absence of magnetic field. The results showed that magnetic actuation contributes to have higher heat fluxes at the same wall superheat in comparison with heat fluxes achieved in the no magnetic field case. Therefore, the local subcooled boiling heat transfer coefficients are increased by the magnetic field. The maximum measured enhancement in local subcooled boiling heat transfer coefficient along the length of the tube by applying magnetic field is 46.58% at applied heat flux of 77,000 W m−2 and mass flux of 270 kg m−2 s−1. Furthermore, the enhancement of local heat transfer coefficient by applying magnetic field decreases as the applied heat flux in the subcooled boiling region is increased.
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| 3. |
- Amirinejhad, Sajad, et al.
(författare)
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Calorimetric study of the oxidation of Al-Mg alloys for the prediction of healing of the double oxide film defect
- 2013
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Ingår i: Journal of thermal analysis and calorimetry (Print). - : Springer. - 1388-6150 .- 1588-2926 .- 1572-8943. ; 113:2, s. 769-777
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Tidskriftsartikel (refereegranskat)abstract
- The oxidation of Al alloys containing 0.3-4.5 wt% Mg in an atmosphere with a very low oxygen partial pressure (< 0.5 ppm, to depict the atmosphere within a double oxide film defect) was studied using differential scanning calorimetry and scanning electron microscopy. The results showed that a newly formed Al2O3 layer held in an Al-Mg melt first transformed to MgAl2O4 spinel and then to MgO. This mechanism was the same for all the Al alloys containing 0.3-4.5 wt% Mg, but the kinetics of the transformations were different and depended on the Mg content of the melt. The results also suggest that the two layers of a double oxide film defect that is held in an Al melt containing 0.3-4.5 wt% Mg can heal (i.e. bond to each other) if held in the liquid metal for a long enough period of time.
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| 4. |
- Bogdanova, Ekaterina, et al.
(författare)
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Assessment of activation energy of enthalpy relaxation in sucrose-water system : effects of DSC cycle type and sample thermal history
- 2022
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Ingår i: Journal of thermal analysis and calorimetry (Print). - : Springer. - 1388-6150 .- 1588-2926. ; 147, s. 9695-9709
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Tidskriftsartikel (refereegranskat)abstract
- The purpose of this study is to critically analyze different methods of calculation of activation energy of relaxation in sucrose-water system from differential scanning calorimetry data. We consider the use of different thermal cycles for calculations together with Moynihan and Kissinger equations. We study the effect of two methods of glass transition temperature determination (half-step and inflection point) on the activation energy values. Along with experimental DSC data, we use the data simulated using Tool-Narayanaswamy-Moynihan model to validate the use of cooling and heating curves and to check the reproducibility of the activation energy calculations. The obtained results show that the thermal cycle with equal cooling and heating rates provides the most reliable data set and the glass transition temperature definition using inflection point rather than half step can be recommended for calculations. Moreover, due to technical reasons, heating rather than cooling scans provide the most reliable results of activation energy calculations. Furthermore, a simple method based on the width of the glass transition region shows reasonable results for single scan experiments. The activation energies of the glass transition in sucrose-water system with different water contents and different thermal histories were studied. Since it is impossible to apply traditional methods based on Moynihan equation for the activation energy evaluation for freeze-dried samples, we propose using another method based on the properties of the recovery peak. Combining the results obtained by different methods, we present a dependence of activation energy in sucrose-water system on water content. The results show that water decreases the activation energy of relaxation process in sucrose matrix.
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| 5. |
- Briggner, Lars-Erik, et al.
(författare)
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Design and testing of a small-scale sublimation apparatus
- 2009
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Ingår i: Journal of Thermal Analysis and Calorimetry. - : Springer Science and Business Media LLC. - 1588-2926 .- 1388-6150 .- 1572-8943. ; 98:1, s. 331-335
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Tidskriftsartikel (refereegranskat)abstract
- In many areas of scientific research and development, for example in the pharmaceutical industry, it is important to prepare and to characterize crystals of pure organic compounds which are thermodynamically stable. The formation of crystals from the gas phase is technically less straightforward than crystallisation from solution, but sublimation techniques can have several important features. In the present paper we report the design and testing of a novel apparatus for small scale sublimation and fractional deposition of crystals. The instrument has been developed with special reference to the needs in the pharmaceutical industry. A few mg of the samples are enclosed, under reduced pressure, in thin-walled glass tubes, along which a well defined temperature gradient can be formed. During an experiment the substance will sublime from the hot end of the glass tube and crystals will be deposited along the temperature gradient. The applicability of the instrument has been verified by experiments with several test compounds. Results from experiments with carbamazepine, are reported in some detail. Carbamazepine single crystals of high quality were obtained and the transition temperature between the triclinic (Form I) and the monoclinic (Form III) crystal modifications agreed with literature values.
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| 6. |
- Ciesla, K, et al.
(författare)
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DSC studies of gamma-irradiation influence on amylose-lipid complex transition in wheat flour
- 2005
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Ingår i: Journal of Thermal Analysis and Calorimetry. - : Springer Science and Business Media LLC. - 1588-2926 .- 1388-6150 .- 1572-8943. ; 79:1, s. 19-27
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Tidskriftsartikel (refereegranskat)abstract
- DSC studies were carried out in the heating-cooling cycles for non-irradiated and irradiated with gamma-rays ((CO)-C-60) using 30 kGy dose wheat flour. The differences between gelatinisation and reversible transition of amylose-lipid complexes occurring in suspensions of non-irradiated and the irradiated flour (characterized by a dry matter to water ratio of 1: 1 and 1:3) depend on the conditions applied in DSC measurements (concentration, heating/cooling rate) and on the preceding treatment of samples. An essential decrease in the temperature of amylose-lipid complex transition was discovered after irradiation. Retrogradation is inhibited in the dense gels of the irradiated samples as compared to the initial ones. The results are discussed in terms of radiation-induced destruction of the polysaccharide chains and lipid modification.
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| 7. |
- Diószegi, Attila, 1962-, et al.
(författare)
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Prediction of volume fraction of primary austenite at solidification of lamellar graphite cast iron using thermal analyses
- 2016
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Ingår i: Journal of thermal analysis and calorimetry (Print). - : Springer Netherlands. - 1388-6150 .- 1588-2926. ; 124:1, s. 215-225
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Tidskriftsartikel (refereegranskat)abstract
- Lamellar graphite cast iron was investigated with carbon equivalents varied between CE = 3.4 and 4.26, cast at various cooling rates between 0.195 and 3.5 °C s-1 covering the limits used for technical applications in the production of complex-shaped lamellar graphite cast iron. Registered cooling curves displaced in two positions in the casting were used to predict the solidification and microstructure formation mechanisms. The predicted volume fraction of primary austenite was compared with the fraction of primary austenite measured on colour micrographs with the help of image analyses. A good correlation has been obtained for medium and slow cooling conditions, while a less good correlation at fast cooling condition was attributed to the used protective environment to preserve thermocouples. The observed fraction and the predicted fraction of primary austenite were in good correlation and followed a consequent variation dependent on the carbon equivalent. Furthermore, the quality of the prediction was dependent on the used numerical algorithm involving cooling information from either one or two thermocouples.
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| 8. |
- El-Sadek, M.H., et al.
(författare)
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Non-isothermal carbothermic reduction kinetics of mechanically activated ilmenite containing self-reducing mixtures
- 2018
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Ingår i: Journal of thermal analysis and calorimetry (Print). - : Springer. - 1388-6150 .- 1588-2926. ; 131:3, s. 2457-2465
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Tidskriftsartikel (refereegranskat)abstract
- Effect of mechanical activation on carbothermic reduction kinetics and mechanism of ilmenite concentrate containing self-reducing mixture has been investigated using a combination of thermogravimetry and X-ray diffraction. Thermogravimetric comparative study of mechanically activated and non-activated ilmenite concentrate containing self-reducing mixtures with C/O molar ratio of 1.5 was conducted non-isothermally. The samples were heated up to 1573 K at three different heating rates (10, 15, and 20 K min−1) under controlled atmosphere. The reduction mechanism of mechanically activated mixture was followed by X-ray diffraction analysis of arrested samples at different reduction extents. In addition, reaction kinetics was further investigated and corresponding kinetic parameters were estimated using isoconversional (model-free) and model-fitting (Coats–Redfern) methods.
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| 9. |
- Farahani, Somayeh Davoodabadi, et al.
(författare)
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Achieving uniform heat transfer coefficient in coaxial pulsating jet
- 2021
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Ingår i: Journal of thermal analysis and calorimetry (Print). - : Springer. - 1388-6150 .- 1588-2926. ; 147:3, s. 2833-2846
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Tidskriftsartikel (refereegranskat)abstract
- The main aim of the present paper is to investigate the inverse design of uniform distribution of heat transfer coefficient on the target plate by employing coaxial jet in the steady and pulsating state. The objective function is defined as the root-mean-square of the deviation of the local Nusselt number on the target plate in computational fluid dynamics simulation from the desired Nusselt number. The heat transfer search method minimizes the objective function. The geometric and fluid parameters are taken into account as design variables. Firstly, optimization in the steady state for the target Nusselt numbers 7, 10 and 13 is carried out and the values of the objective function in the optimal state are found to be 0.51, 0.18 and 0.314, respectively. The range of design variables in the steady and pulsating state is similar, while the heat transfer rate of the pulsating state is higher than that of the steady state. The variations of velocity in the inner and outer nozzles with time are considered to have a sine–sine, cosine–sine and constant–sine behavior. Optimization is carried out in the pulsating state for the Nusselt numbers 33, 44, 55 and 57. The objective function for these numbers in the optimal state is less than 0.02. By employing the conjugate gradient method with adjoint equation and the optimal value of design variables, the distribution of Nusselt number on the target plate in the steady and pulsating state for the constant–sine velocity case is experimentally estimated. The difference between experimental results and the value of the target Nusselt number is about 4–14%, indicating a good agreement between the two approaches.
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| 10. |
- Fatahian, Hossein, et al.
(författare)
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Improving the flow uniformity in compact parallel-flow heat exchangers manifold using porous distributors
- 2022
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Ingår i: Journal of thermal analysis and calorimetry (Print). - : Springer Science and Business Media LLC. - 1388-6150 .- 1588-2926. ; 147:22, s. 12919-12931
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Tidskriftsartikel (refereegranskat)abstract
- The present study deals with the numerical simulation of turbulent flow in a Z-type manifold in which the fluid is distributed via nine distribution tubes. One of the major drawbacks of such devices is the mal-distribution of flow within these tubes. The flow rates are usually low in the first tubes close to the header entrance and increase in the other tubes. To address this problem and achieve a more uniform flow distribution inside the manifold, a novel solution is introduced in the present study, which includes the insertion of thin layers of porous media at the inlet of distribution tubes. In addition, a parametric study is conducted to evaluate the effect of porous media geometrical parameters such as pore diameter, porosity, and porous layer thickness on flow distributions among the tubes. The results demonstrate that the proposed approach increases the uniformity of flow distribution specifically when a porous media with higher resistance against the fluid flow is inserted uniformly within the manifold. In this case, a standard deviation as small as Phi=0.0067 could be reached showing the high level of flow uniformity within the manifold. Also, a maximum pressure drop of 12.557 kPa is observed which is approximately 38% larger than that calculated in the manifold without porous insertions. Moreover, several non-uniform distributions of porous media are also investigated to further improve the flow uniformity and decrease the pressure drop. An improvement in the standard deviation of Phi=0.0043 is obtained in the case of #E3 with a non-uniform porous distribution with a 5% reduction in pressure drop compared to the pressure drop calculated in the corresponding uniform case #E1. The results reveal the effectiveness of the approach presented here to reach a more uniform flow distribution within the manifold without the need for re-designing and altering the manifold geometry which is usually proposed in the literature.
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