| 1. |
- Aldén, Markus, et al.
(författare)
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Intracellular Reverse Transcription of Pfizer BioNTech COVID-19 mRNA Vaccine BNT162b2 In Vitro in Human Liver Cell Line
- 2022
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Ingår i: Current Issues in Molecular Biology. - : MDPI AG. - 1467-3045. ; 44:3, s. 1115-1126
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Tidskriftsartikel (refereegranskat)abstract
- Preclinical studies of COVID-19 mRNA vaccine BNT162b2, developed by Pfizer and BioNTech, showed reversible hepatic effects in animals that received the BNT162b2 injection. Furthermore, a recent study showed that SARS-CoV-2 RNA can be reverse-transcribed and in-tegrated into the genome of human cells. In this study, we investigated the effect of BNT162b2 on the human liver cell line Huh7 in vitro. Huh7 cells were exposed to BNT162b2, and quantitative PCR was performed on RNA extracted from the cells. We detected high levels of BNT162b2 in Huh7 cells and changes in gene expression of long interspersed nuclear element-1 (LINE-1), which is an endogenous reverse transcriptase. Immunohistochemistry using antibody binding to LINE-1 open reading frame-1 RNA-binding protein (ORFp1) on Huh7 cells treated with BNT162b2 indicated increased nucleus distribution of LINE-1. PCR on genomic DNA of Huh7 cells exposed to BNT162b2 amplified the DNA sequence unique to BNT162b2. Our results indicate a fast up-take of BNT162b2 into human liver cell line Huh7, leading to changes in LINE-1 expression and distribution. We also show that BNT162b2 mRNA is reverse transcribed intracellularly into DNA in as fast as 6 h upon BNT162b2 exposure.
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| 2. |
- De Marinis, Yang, et al.
(författare)
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Detection of SARS-CoV-2 by rapid antigen tests on saliva in hospitalized patients with COVID-19
- 2021
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Ingår i: Infection Ecology and Epidemiology. - : Informa UK Limited. - 2000-8686. ; 11:1
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Tidskriftsartikel (refereegranskat)abstract
- Background: The COVID-19 pandemic presents great challenges on transmission prevention, and rapid diagnosis is essential to reduce the disease spread. Various diagnostic methods are available to identify an ongoing infection by nasopharyngeal (NPH) swab sampling. However, the procedure requires handling by health care professionals, and therefore limits the application in household and community settings. Objectives: In this study, we aimed to determine if the detection of SARS-CoV-2 can be performed alternatively on saliva specimens by rapid antigen test. Study Design: Saliva and NPH specimens were collected from 44 patients with confirmed COVID-19. To assess the diagnostic accuracy of point-of-care SARS-CoV-2 rapid antigen test on saliva specimens, we compared the performance of four test products. Results: RT-qPCR was performed and NPH and saliva sampling had similar Ct values, which associated with disease duration. All four antigen tests showed similar trend in detecting SARS-CoV-2 in saliva, but with variation in the ability to detect positive cases. The rapid antigen test with the best performance could detect up to 67% of the positive cases with Ct values lower than 25, and disease duration shorter than 10 days. Conclusion: Our study therefore supports saliva testing as an alternative diagnostic procedure to NPH testing, and that rapid antigen test on saliva provides a potential complement to PCR test to meet increasing screening demand.
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| 3. |
- Ruan, Can, et al.
(författare)
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Combustion of micron-sized Al-Mg alloy wires in hot H2O/O2/N2 flows
- 2024
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Ingår i: Fuel. - 0016-2361. ; 357
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Tidskriftsartikel (refereegranskat)abstract
- The use of aluminum-magnesium (Al-Mg) alloy particle as energetic additive in solid propellants was previously shown to have many advantages over pure Al particle, such as relatively low ignition temperature, high reaction rate and low particle agglomeration rate. In this paper, the combustion of Al-Mg alloy in hot H2O/O2/N2 flows was experimentally studied using wires with a diameter of 200 µm. The employment of wires instead of particles provided a unique opportunity to obtain fundamental insights into the combustion process due to the spatial stabilization and large size of the sample. High-speed imaging showed that the combustion of Al-Mg alloy wire could be divided into three stages, namely pre-heating, ignition, and combustion. Spectral measurements suggested that the chemiluminescence emissions from Mg, MgO and MgOH dominated the collected spectra, in spite of only 3% Mg (by weight) existed in the alloy. Additionally, it was observed that moderate gaseous reactions could occur well before the breakup of the passive oxide coating, generating obvious fine oxide smokes. Moreover, consumption rates of the wire in different hot oxidizers were obtained and compared. It was shown that O2 featured more significant promotion of the reaction than H2O. Nevertheless, without O2, much less metal-oxide particles were generated. Temperature measurements indicated that the ignition temperature lied within 2160 ∼ 2220 K, which was lower than the melting points of Al2O3 (2350 K) and MgO (3125 K). Large single burning Al-Mg alloy droplets (∼200 µm diameter) were generated after the micro-explosion inside the wire. It was found that the combustion of Al-Mg alloy in both H2O/O2/N2 and H2O/N2 atmospheres were diffusion-controlled with a stand-off distance around 150 µm (stand-off ratios at ∼ 1.3). Finally, SEM and EDS measurements revealed that Al, Mg and O elements coexisted on the surface of the burnt wires. Nevertheless, it was observed that the oxidization of Mg started before Al, and the reaction of alloy was more intense when O2 existed. This led to the generation of much thicker oxide layers and larger number of nanoparticles.
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| 4. |
- Sadanandan, R, et al.
(författare)
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Detailed investigation of ignition by hot gas jets
- 2007
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Ingår i: Proceedings of the Combustion Institute. - : Elsevier BV. - 1540-7489. ; 31:1, s. 719-726
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Konferensbidrag (refereegranskat)abstract
- Experimental and numerical investigations of the ignition of hydrogen/air mixtures by jets of hot exhaust gases are reported. An experimental realisation of such an ignition process, where a jet of hot exhaust gas impinges through a narrow nozzle into a quiescent hydrogen/air mixture, possibly initiating ignition and combustion, is studied. High-speed laser-induced fluorescence (LIF) image sequences of the hydroxyl radical (OH) and laser Schlieren methods are used to gain information about the spatial and temporal evolution of the ignition process. Recording temporally resolved pressure traces yields information about ambient conditions for the process. Numerical experiments are performed that allow linking these observables to certain characteristic states of the gas mixture. The outcome of numerical modelling and experiments indicates the important influence of the hot jet temperature and speed of mixing between the hot and cold gases on the ignition process. The results show the quenching of the flame inside the nozzle and the subsequent ignition of the mixture by the hot exhaust jet. These detailed examinations of the ignition process improve the knowledge concerning flame transmission out of electrical equipment of the type of protection flameproof enclosure.
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| 5. |
- Samuelsson, Per, et al.
(författare)
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Airborne Gold Nanoparticle Detection Using Photoluminescence Excited with a Continuous Wave Laser
- 2021
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Ingår i: Applied Spectroscopy. - : SAGE Publications. - 0003-7028 .- 1943-3530. ; 75:11, s. 1402-1409
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Tidskriftsartikel (refereegranskat)abstract
- We report the observation of photoluminescence emission from airborne gold, silver, and copper nanoparticles. A continuous wave 532 nm laser was employed for excitation. Photoluminescence from gold nanoparticles carried in a nitrogen gas flow was both spectrally resolved and directly imaged in situ using an intensified charge-coupled device camera. The simultaneously detected Raman signal from the nitrogen molecules enables quantitative estimation of the photoluminescence quantum yield of the gold nanoparticles. Photoluminescence from metal nanoparticles carried in a gas flow provides a potential tool for operando imaging of plasmonic metal nanoparticles in aerosol reactions.
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| 6. |
- Tunér, Martin, et al.
(författare)
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Formaldehyde and Hydroxyl Radicals in an HCCI Engine - Calculations and LIF-Measurements
- 2007
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Ingår i: SAE technical paper series.
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Tidskriftsartikel (refereegranskat)abstract
- Concentrations of hydroxyl radicals and formaldehyde were calculated using homogeneous (HRM) and stochastic reactor models (SRM), and the result was compared to LIF measurements from an optically accessed iso-octane/n-heptane-fuelled homogeneous charge compression ignition (HCCI) engine. The comparison was at first conducted from averaged total concentrations/signal strengths over the entire combustion volume, which showed a good qualitative agreement between experiments and calculations. Time- and the calculation-inlet-temperature-resolved concentrations of formaldehyde and hydroxyl radicals obtained through HRM are presented. Probability density plots (PDPs) through SRM calculations and LIF measurements are presented and compared, showing a very good agreement considering their delicate and sensitive nature. Thus it is concluded that SRM is a valid model for these purposes, justifying the use of SRM in order to extend the evaluated concentration ranges of the analyzed species beyond the detection/separation level. It is shown that formaldehyde concentration increases slowly, contrary to hydroxyl which is fast developed. Formaldehyde is locally fast consumed once high temperature chemistry has started, and the highest maximum concentrations of formaldehyde are found in cases where low-temperature chemistry was never transitioned to high-temperature ignition. The PDP's from SRM calculations give increased insight of the occurrence and development of autoignition. During the onset of ignition, the regions with the highest formaldehyde concentrations also have the highest concentrations of hydroxyl radicals. The low-temperature heat release (LTHR) maximum occurs before maximum of formaldehyde, and the regions of (for the LTHR regime relatively) high hydroxyl concentrations gradually becomes fewer until they cease to exist; this occurs after the LTHR peak but before formaldehyde maximum. During the transition state all regions have similar formaldehyde concentrations but varying concentrations of hydroxyl.
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