| 1. |
- Ghasempour, Farideh, 1981, et al.
(author)
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Identification and characterization of three-dimensional turbulent flow structures
- 2016
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In: AICHE Journal. - : Wiley. - 1547-5905 .- 0001-1541. ; 62:4, s. 1265-1277
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Journal article (peer-reviewed)abstract
- Many phenomena in chemical processes for example fast mixing, coalescence and break-up of bubbles and drops are not correctly described using average turbulence properties as the outcome is governed by the interaction with individual vortices. In this study, an efficient vortex-tracking algorithm has been developed to identify thousands of vortices and quantify properties of the individual vortices. The traditional algorithms identifying vortex-cores only capture a fraction of the total turbulent kinetic energy, which is often not sufficient for modeling of coalescence and break-up phenomena. In the present algorithm, turbulent vortex-cores are identified using normalized Q-criterion, and allowed to grow using morphological methods. The growth is constrained by estimating the influence from all neighboring vortices using the Biot-Sawart law. This new algorithm allows 82% of the total turbulent kinetic to be captured, at the same time the individual vortices can be tracked in time. (c) 2015 American Institute of Chemical Engineers AIChE J, 62: 1265-1277, 2016
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| 2. |
- Kamp, Carl Justin, 1982, et al.
(author)
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Nanofabricated catalyst particles for the investigation of catalytic carbon oxidation by oxygen spillover
- 2017
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In: Langmuir. - : American Chemical Society (ACS). - 1520-5827 .- 0743-7463. ; 33:20, s. 4903-4912
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Journal article (peer-reviewed)abstract
- The catalytic oxidation of carbon by molecular oxygen was studied using C/Pt, Pt/C, Pt/Al2O3/C, Pt/CeO2/C, Al2O3/C and CeO2/C model samples prepared by hole-mask colloidal lithography. By this technique the degree of contact between platinum and carbon was controlled with high precision. The oxidation of carbon was monitored using atomic force microscopy and scanning electron microscopy. The results show that Pt in direct contact with carbon catalyzes the oxidation of carbon by spillover of dissociated oxygen from Pt to carbon. By physically separating Pt and carbon with a 10 nm thin spacer layer of Al2O3, the oxygen spillover was entirely blocked. However, through a corresponding spacer layer of CeO2, carbon oxidation was still observed, either by oxygen spillover from Pt to carbon or directly dissociated on the ceria, although at a slower rate compared to the case with no spacer layer between Pt and carbon.
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| 3. |
- Nugraha, Maulana, 1992, et al.
(author)
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Particle modelling in biomass combustion using orthogonal collocation
- 2019
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In: Applied Energy. - : Elsevier BV. - 1872-9118 .- 0306-2619. ; 255
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Journal article (peer-reviewed)abstract
- Development of an accurate and computational efficient biomass particle model to predict particle pyrolysis and combustion is the focus of this paper. Partial differential equations (PDEs) for heat and mass balance are transformed into a system of coupled ordinary differential equations (ODEs) with the use of orthogonal collocation as the particle discretization method. The orthogonal collocation method is incorporated with comprehensive physicochemical mechanisms to predict the behavior of biomass components during particle pyrolysis and combustion. Heat adsorption by evaporated gas and water movement by diffusion inside the biomass matrix are included in the present work, in parallel with the effect of Stefan flow on the heat and mass transfer rates at the particle surface. Abandoning the classical interface-based modelling approach, the present approach allows decoupling between biomass components and spatial resolution, and the prediction of continuous intra-particle profiles. The new particle model is proven to be accurate and stable through its high degree of agreement with simulation results for particle pyrolysis and combustion experiments using different particle moisture contents and geometrical shapes. The intra-particle temperature gradient, as well as particle mass and size evolution, can be predicted accurately, as validated against experimental data. It is shown that six collocation points provide satisfying resolution. The computational efficiency is confirmed by the short simulation time that was found to be approximately three orders of magnitude faster than mesh-based simulations. This implies that the current model can be used for computational fluid dynamic (CFD) analysis through implementation as sub-grid-scale models to design, for example, biomass furnaces.
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| 4. |
- Soltani, Soheil, 1984, et al.
(author)
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Enhancement of time resolution in transient kinetics
- 2015
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In: Chemical Engineering Journal. - : Elsevier BV. - 1385-8947. ; 264, s. 188-196
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Journal article (peer-reviewed)abstract
- © 2014 Elsevier B.V. A methodology for enhancement of time resolution in transient experiments has been formulated where the mathematical background of the deconvolution problem is outlined. The analysis leads to an algorithm based on the discrepancy principle for calculation of the regularization parameter, which exhibits satisfactory convergence and can successfully handle the noise that is present in the original measurements. Application of the algorithm for different synthetic datasets has shown that the extent of enhancement in time resolution depends on the broadening function and the sampling frequency of the detector. Consequently, shorter residence times and higher sampling frequencies are in general desirable.The impact of deviations from the Beer-Lambert law in Fourier-transform infra-red spectroscopy has also been evaluated using computational fluid dynamics simulations. The flow field and concentration distribution in a gas cell with ~5. m optical pathlength have been simulated, and the absorbance-concentration correlations have been implemented in the analysis. Carbon monoxide and nitric oxide have been chosen as species with significant nonlinear infra-red absorption features, and their mixtures with different concentrations have been considered in separate simulations. Due to the nonlinear characteristics of the problem, various levels of error have been observed in the results, which are dependent on the concentration at the inlet of the gas cell and the gas phase species as well.The variance of concentration distribution normalized with mean squared concentration has been defined as a measure of intensity of segregation, which displays strong similarity for the same flow field pattern and relatively close molecular diffusivities.
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| 5. |
- Soltani, Soheil, 1984, et al.
(author)
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The effect of exhaust gas composition on the kinetics of soot oxidation and diesel particulate filter regeneration
- 2018
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In: Fuel. - : Elsevier BV. - 0016-2361. ; 220, s. 453-463
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Journal article (peer-reviewed)abstract
- Experimental investigation of the effect of water vapor on non-catalyzed carbon oxidation with NO 2 has shown a promoting effect of about a factor 2. The promoting effect of water increases with decreasing temperature. Similarly, water was observed to promote carbon oxidation with molecular oxygen. Furthermore, a synergistic effect was observed when NO 2 , water and oxygen were all present in the gas phase. Evidences have been found suggesting that the promoting effect of water proceeds via an interaction with surface oxygen complexes. Implementing the results of this study in the control unit of diesel vehicles will increase the efficiency of filter regeneration. Therefore, the fuel penalty associated with active regeneration cycles can be minimized. To this end, a global kinetic model was developed that can successfully fit the observed reaction rates over the entire range of carbon conversion. The model can be used to optimize filter regeneration by predicting the required exhaust condition for maintaining a balance between soot accumulation and burn-off. A population balance model was formulated that makes it possible to keep track of age distribution in a reactor channel or in a soot filter.
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| 6. |
- Soltani, Soheil, 1984, et al.
(author)
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Time Resolution in Transient Kinetics
- 2015
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In: Springer Proceedings in Mathematics and Statistics. - Cham : Springer International Publishing. - 2194-1017 .- 2194-1009. ; 120, s. 81-96
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Conference paper (peer-reviewed)abstract
- This study presents the mathematical background of deconvolution of concentrationdata in transient kinetic studies. In a case study with a flow reactor setup,it has been shown that the deconvolution algorithm results in a significant reductionin the time lag of an FTIR detector from around 23 s to around 1.2 s. This is an importantachievement as otherwise the dynamic information of a reactive system (like therate of adsorption or accumulation of surface species) would have been lost duringthat time interval. Using the regularizing theory of ill-posed, inverse problems,an algorithm for deconvolution of concentration measurements has been developedbased on the discrepancy principle. Our software package, TranKin, can be easilyadapted to various other laboratory reactor systems to enhance the time resolutionof transient experiments.
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| 7. |
- Burda, P, et al.
(author)
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Characterization and review of MTHFD1 deficiency: four new patients, cellular delineation and response to folic and folinic acid treatment.
- 2015
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In: Journal of Inherited Metabolic Disease. - : Wiley. - 0141-8955 .- 1573-2665. ; 38:5, s. 863-872
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Journal article (peer-reviewed)abstract
- In the folate cycle MTHFD1, encoded by MTHFD1, is a trifunctional enzyme containing 5,10-methylenetetrahydrofolate dehydrogenase, 5,10-methenyltetrahydrofolate cyclohydrolase and 10-formyltetrahydrofolate synthetase activity. To date, only one patient with MTHFD1 deficiency, presenting with hyperhomocysteinemia, megaloblastic anaemia, hemolytic uremic syndrome (HUS) and severe combined immunodeficiency, has been identified (Watkins et al J Med Genet 48:590-2, 2011). We now describe four additional patients from two different families. The second patient presented with hyperhomocysteinemia, megaloblastic anaemia, HUS, microangiopathy and retinopathy; all except the retinopathy resolved after treatment with hydroxocobalamin, betaine and folinic acid. The third patient developed megaloblastic anaemia, infection, autoimmune disease and moderate liver fibrosis but not hyperhomocysteinemia, and was successfully treated with a regime that included and was eventually reduced to folic acid. The other two, elder siblings of the third patient, died at 9weeks of age with megaloblastic anaemia, infection and severe acidosis and had MTFHD1 deficiency diagnosed retrospectively. We identified a missense mutation (c.806C>T, p.Thr296Ile) and a splice site mutation (c.1674G>A) leading to exon skipping in the second patient, while the other three harboured a missense mutation (c.146C>T, p.Ser49Phe) and a premature stop mutation (c.673G>T, p.Glu225*), all of which were novel. Patient fibroblast studies revealed severely reduced methionine formation from [(14)C]-formate, which did not increase in cobalamin supplemented culture medium but was responsive to folic and folinic acid. These additional cases increase the clinical spectrum of this intriguing defect, provide in vitro evidence of disturbed methionine synthesis and substantiate the effectiveness of folic or folinic acid treatment.
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| 8. |
- Drevinge, Christina, 1983, et al.
(author)
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Perilipin 5 is protective in the ischemic heart
- 2016
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In: International Journal of Cardiology. - : Elsevier BV. - 0167-5273 .- 1874-1754. ; 219, s. 446-454
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Journal article (peer-reviewed)abstract
- Background: Myocardial ischemia is associated with alterations in cardiac metabolism, resulting in decreased fatty acid oxidation and increased lipid accumulation. Here we investigate how myocardial lipid content and dynamics affect the function of the ischemic heart, and focus on the role of the lipid droplet protein perilipin 5 (Plin5) in the pathophysiology of myocardial ischemia. Methods and results: We generated Plin5(-/-) mice and found that Plin5 deficiency dramatically reduced the triglyceride content in the heart. Under normal conditions, Plin5(-/-) mice maintained a close to normal heart function by decreasing fatty acid uptake and increasing glucose uptake, thus preserving the energy balance. However, during stress or myocardial ischemia, Plin5 deficiency resulted in myocardial reduced substrate availability, severely reduced heart function and increased mortality. Importantly, analysis of a human cohort with suspected coronary artery disease showed that a common noncoding polymorphism, rs884164, decreases the cardiac expression of PLIN5 and is associated with reduced heart function following myocardial ischemia, indicating a role for Plin5 in cardiac dysfunction. Conclusion: Our findings indicate that Plin5 deficiency alters cardiac lipid metabolism and associates with reduced survival following myocardial ischemia, suggesting that Plin5 plays a beneficial role in the heart following ischemia. (C) 2016 The Authors. Published by Elsevier Ireland Ltd.
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| 9. |
- Laurell, Anna, et al.
(author)
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Intratumorally injected pro-inflammatory allogeneic dendritic cells as immune enhancers: a first-in-human study in unfavourable risk patients with metastatic renal cell carcinoma
- 2017
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In: Journal for Immunotherapy of Cancer. - : BMJ. - 2051-1426. ; 5
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Journal article (peer-reviewed)abstract
- Background: Accumulating pre-clinical data indicate that the efficient induction of antigen-specific cytotoxic CD8+ T cells characterizing viral infections is caused by cross-priming where initially infected DCs produce an unique set of inflammatory factors that recruit and activate non-infected bystander DCs. Our DC-based immunotherapy concept is guided by such bystander view and accordingly, we have developed a cellular adjuvant consisting of pre-activated allogeneic DCs producing high levels of DC-recruiting and DC-activating factors. This concept doesn't require MHC-compatibility between injected cells and the patient and therefore introduces the possibility of using pre-produced and freeze-stored DCs from healthy blood donors as an off-the-shelf immune enhancer. The use of MHC-incompatible allogeneic DCs will further induce a local rejection process at the injection site that is expected to further enhance recruitment and maturation of endogenous bystander DCs. Methods: Twelve intermediate and poor risk patients with newly diagnosed metastatic renal cell carcinoma (mRCC) where included in a phase I/II study. Pro-inflammatory allogeneic DCs were produced from a leukapheresis product collected from one healthy blood donor and subsequently deep-frozen. A dose of 5-20 x 106 DCs (INTUVAX) was injected into the renal tumor twice with 2 weeks interval before planned nephrectomy and subsequent standard of care. Results: No INTUVAX-related severe adverse events were observed. A massive infiltration of CD8+ T cells was found in 5 out of 12 removed kidney tumors. No objective tumor response was observed and 6 out of 11 evaluable patients have subsequently received additional treatment with standard tyrosine kinase inhibitors (TKI). Three of these 6 patients experienced an objective tumor response including one sunitinib-treated patient who responded with a complete and durable regression of 4 brain metastases. Median overall survival (mOS) is still not reached (currently 42.5 months) but has already passed historical mOS in patients with unfavourable risk mRCC on standard TKI therapy. Conclusions: Our findings indicate that intratumoral administration of proinflammatory allogeneic DCs induces an antitumor immune response that may prolong survival in unfavourable risk mRCC-patients given subsequent standard of care. A randomized, multi-center, phase II mRCC trial (MERECA) with INTUVAX in conjuction with sunitinib has been initiated.
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| 10. |
- Megeus, Veronika, 1983, et al.
(author)
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Hand Contamination, Cross-Transmission, and Risk-Associated Behaviors: An Observational Study of Team Members in ORs
- 2015
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In: AORN Journal. - : Wiley. - 0001-2092. ; 102:6
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Journal article (peer-reviewed)abstract
- Team members in ORs have frequent hand contact with many surfaces and sites during high workload, thus increasing the risk for microorganism cross-transmission. This study aimed at identifying risks for hand contamination and microorganism cross-transmission during invasive procedures in ORs. We carried out observations during 22 daytime sessions and analyzed data using qualitative content analysis. The results revealed that clinicians’ hands may be contaminated by self-contamination, via objects, or by touching the patient. Contamination may occur before, during, or directly after performing an invasive procedure requiring the use of aseptic technique, which risks cross-transmitting microorganisms. The results of the study contribute detailed knowledge about risk-associated activities and behaviors in relation to performing invasive procedures in the OR. This knowledge provides clinicians, managers, and educators with specific information that can be used in nursing and medical education and in quality improvement projects aimed at improving hand hygiene routines and enhancing aseptic technique.
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