| 1. |
- Li, Xingchen, et al.
(författare)
-
Analysis on breakup dynamics of hydrogen taylor bubble formation in a cross-junction microchannel
- 2021
-
Ingår i: International Journal of Hydrogen Energy. - : Elsevier BV. - 0360-3199. ; 46:67, s. 33438-33452
-
Tidskriftsartikel (refereegranskat)abstract
- The pinch-off dynamics during hydrogen bubble formation was experimentally investigated in a cross-junction microchannel. A binarization interface recognizing and key frame tracking method was established. By analyzing the breakup dynamics through spatial and time domains, the effects of interfacial tension and viscosity on hydrogen bubble pinch-off were revealed. A transitional stage between a liquid squeezing stage and a free pinch-off stage was newly observed and the transitional stage was named as the wave model stage because of the long-wave approximation of the interface at this stage. The time criteria between the three stages are proved to be around 1/10 of tcap (capillary time) and around tcap to the pinch-off moment, respectively. However, the power law exponents of the minimum radial radius R0 for hydrogen - liquid flow, larger than those for nitrogen - liquid flow, are consistent with literature works in terms of both range and tendency.
|
|
| 2. |
- Li, Xingchen, et al.
(författare)
-
Breakup dynamics of gas-liquid interface during Taylor bubble formation in a microchannel flow-focusing device
- 2020
-
Ingår i: Experimental Thermal and Fluid Science. - : Elsevier BV. - 0894-1777. ; 113
-
Tidskriftsartikel (refereegranskat)abstract
- This work aims to investigate the breakup dynamics of the gas-liquid interface during bubble formation in a microchannel flow-focusing device. An interface tracking method is developed to capture the profiles of the gaseous thread evolution. The results show that the pinch-off period can be further divided into a liquid squeezing stage and a free pinch-off stage in both the radial and axial directions. The time domain criterion between these two stages in a low viscous liquid, with Ohnesorge numbers Oh≪1, is proved to be shorter than the capillary time. The effects of surface tension, viscosity and gas inertial force exerting on the interface during the free pinch-off stage are proved similar to those in a quiescent liquid pool. The power law of the minimum diameter at the gaseous thread to the pinch-off remaining time in the present experiments agrees with previous studies in both ranges (1/3 to 1/2) and tendency.
|
|
| 3. |
- Li, Xingchen, et al.
(författare)
-
Breakup dynamics of low-density gas and liquid interface during Taylor bubble formation in a microchannel flow-focusing device
- 2020
-
Ingår i: Chemical Engineering Science. - : Elsevier BV. - 0009-2509. ; 215
-
Tidskriftsartikel (refereegranskat)abstract
- This work aims to investigate the breakup dynamics of the low-density gas and liquid interface during bubble formation in a microchannel flow-focusing device. A high-contrast interface tracking method is developed. After the neck motion analysis in radial and axial directions, the time domain criterion between the liquid squeezing stage and the free pinch-off stage is proved to be two orders of magnitude less than the capillary time and is close to the viscous time of the liquid. Comparing to Nitrogen bubbles, the pinch-off point of Helium bubbles deflects downstream in viscous liquids and upstream in low surface tension liquids. Helium bubbles generate faster in viscous liquids and slower in low surface tension liquids. The power law exponents of thread diameter to the pinch-off remaining time in Helium experiments, which are larger than those in Nitrogen experiments, agree with previous studies in both ranges (1/3–1/2) and tendency.
|
|
| 4. |
- Li, Xingchen, et al.
(författare)
-
High conversion hydrogen peroxide microchannel reactors : Design and two-phase flow instability investigation
- 2021
-
Ingår i: Chemical Engineering Journal. - : Elsevier BV. - 1385-8947. ; 422
-
Tidskriftsartikel (refereegranskat)abstract
- Novel micro-scale reaction devices are progressing in various applications. Whereas, specialized gas-producing reactors of high conversion at micro/mini scale remain challenging and are rarely explored, but are needed urgently in new generation vehicles and aerospace applications. In this work, two kinds of high-aspect-ratio flat channel (200 μm depth, 5.0 mm width, and 40.0 mm length) microreactors with platinum foil catalyst, named as inlet reactors and outlet reactors, are designed and tested for H2O2 decomposition. The wavelet transform method is applied to analyze the effects of reactant flow rate and pin–fin configuration on flow instability in both the time domain and the frequency domain. The inlet reactors utilize periodic flow pattern transitions to achieve an independence of conversion on reactant flow rate. For outlet reactors, the upstream compressible slug volume and the backflow are restricted by the pin–fin array, and thus the H2O2 decomposition reaches a conversion of 59.0% at 5 ml/h reactant flow rate. This conversion is 300% higher than those of H2O2 decomposition in microchannel reactors ever reported in the literature. The results from this work can be used for the design and manufacturing of micro-scale reactors for gas involved applications.
|
|
| 5. |
- Sorensen, Per Soelberg, et al.
(författare)
-
Simvastatin as add-on therapy to interferon beta-1a for relapsing-remitting multiple sclerosis (SIMCOMBIN study): a placebo-controlled randomised phase 4 trial.
- 2011
-
Ingår i: Lancet neurology. - 1474-4465. ; 10:8, s. 691-701
-
Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Treatment of relapsing-remitting multiple sclerosis with interferon beta is only partly effective. We aimed to establish whether add-on of simvastatin, a statin with anti-inflammatory properties, improves this efficacy. METHODS: We enrolled treatment-naive patients with relapsing-remitting multiple sclerosis in a multicentre, placebo-controlled, double-blind, randomised, parallel-group trial of simvastatin (80 mg daily) as add-on treatment to intramuscular interferon beta-1a (30 μg weekly). After starting treatment with interferon beta, patients were randomly assigned (in computer-generated blocks of four patients) to simvastatin 80 mg per day or placebo for 1-3 years. Patients and treating and evaluating physicians were masked to treatment allocation. The primary outcome measure was annual rate of documented relapses; analysis was by intention to treat. This trial is registered at ClinicalTrials.gov, NCT00492765. FINDINGS: We randomly assigned 307 patients to interferon beta plus simvastatin (n=151) or plus placebo (n=156). Annual rate of documented relapses was 0·19 (95% CI 0·13 to 0·28) in the simvastatin group and 0·14 (95% CI 0·09 to 0·23) in the placebo group (absolute difference 0·059, 95% CI -0·21 to 0·09; p=0·35). Time to first documented relapse (20th percentile) was 18·1 months in patients on simvastatin and 21·5 months in those on placebo (hazard ratio 1·21, 95% CI 0·74 to 1·99; p=0·51). Mean number of new or enlarging T2 lesions was 2·96 in the simvastatin group and 2·52 in the placebo group (ratio of new lesions, 1·17, 95% CI 8·89 to 1·55; p=0·25). Eight (6%) patients on simvastatin and 17 (13%) on placebo had no disease activity (odds ratio 0·42, 95% CI 0·17 to 1·00; p=0·05). No unexpected adverse events were seen. Generally, adverse events were mild and there were no group differences in infections or musculoskeletal disorders, including myalgia (five [3%] patients on simvastatin and nine [6%] on placebo). Rhabdomyolysis and myoglobinuria were not reported and there were no differences in serum creatine phosphokinase. INTERPRETATION: We found no beneficial effect of simvastatin as add-on therapy to interferon beta-1a. Although unlikely, we can not exclude that combination of other statins with other disease-modifying drugs still could be beneficial. FUNDING: Biogen Idec.
|
|
| 6. |
- Wang, Zihan, et al.
(författare)
-
Phosphorus flow analysis in the maize based food-feed-energy systems in China
- 2020
-
Ingår i: Environmental Research. - : Elsevier. - 0013-9351 .- 1096-0953. ; 184
-
Tidskriftsartikel (refereegranskat)abstract
- Phosphorus (P) is an essential and limiting nutrient for agricultural systems, where the demand for agricultural products such as food, feed, and bio-fuel are the major drivers of the intensification of agricultural production systems. Globally, maize is one of three main cereal crops, a main feedstock for animal production and a substrate for the production of bio-ethanol. This study investigated P flows through the multiple utilization systems of maize (as represented by the subsystems of food, feed and energy production) at a crop level of 2016 as reference year and made future predictions of P flows for the year 2030 based on different scenarios for food-feed-energy systems in China. For 2016, the subsystem of animal production resulted in the highest waste of P due to inappropriate manure management, but the subsystem of value-added products (Bio-fuel production, distillers dried grains with solubles (DDGS), maize-oil) showed the lowest P use efficiency (39%). From the value-added subsystem, 17% of P from the process flow to the subsystem of animal production as DDGS, and 61% of P is wasted associated with wastewater and sludge. Future scenarios of structural adjustments in the maize consumption system predict that the supply of maize for animal feed will be threatened if the policy of the Biofuel National Promotion before 2020 is fully implemented in China, as current maize production will not meet the future demand of food, feed and energy simultaneously. The results emphasized the use of P waste resources and better sludge management from a systems perspective. This also implied the importance of exploring coordinated development and integrated strategies for sustainable P flow management in multiple utilization systems.
|
|
| 7. |
- Wu, Xingchen
(författare)
-
Multiple sclerosis : MRI diagnosis, potential treatment and future potential for nanoparticle applications
- 2005
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Multiple Sclerosis is an inflammatory demyelinating and neurodegenerative disease of the central nervous system. Magnetic resonance imaging is an important tool for diagnosing of Multiple Sclerosis and for, in vivo, monitoring its evolution of pathology. The introduction of interferon (IFN)-beta therapy has altered the natural course of Multiple Sclerosis. We investigated the effect of low-dose low-frequency and high-dose high frequency IFNbeta-1a treatment in patients with secondary progressive Multiple Sclerosis, and also after discontinuation of treatment by volumetric magnetic resonance imaging and clinical assessments. The longitudinal study showed that a single weekly dose of 22 µg IFN-beta-1a had a mild beneficial effect as visualized by magnetic resonance imaging, but this dosage and frequency of administration was insufficient in controlling clinical disease activity. Discontinuation of IFN-beta1a was associated with an acceleration of neurological disability and progression of brain lesion. A major hurdle in the research of neuroinflammatory disorders of the central nervous system is the inaccessibility of the organ. To overcome such limitations development of relevant animal models has been an important approach. Experimental autoimmune/or allergic encephalomyelitis (EAE) is an animal model that closely mimics key features of human Multiple Sclerosis. We studied EAE-regulatory genes and explored novel individualized therapeutic strategies in EAE models. Genetic factors play an important role in the expression of the disease, also shown experimentally in a number of inbred rat strains that differ in their relative susceptibilities to EAE. The availability of such strains of rats, the discovery of polymorphic genetic markers, as well as the development of genetic and physical maps provided an opportunity for mapping of disease-regulating genes in EAE. We fine-mapped quantitative trait loci (QTL) that regulate EAE on rat chromosome 10 in the 7th generation of an advanced intercross line (AIL). AIL mapping was proved to be an efficient approach to narrow down QTL and to resolve closely situated QTL. Dendritic cells (DC) not only control immunity, but also maintain tolerance to self-antigens, thereby minimizing autoaggressive immune responses. We investigated the therapeutic potential of IFN-gamma modified DC and CD8alpha+ DC, respectively, in rat and mouse EAE models. The severity of the disease was dramatically inhibited in animals injected with IFN-gamma modified DC or CD8alpha+ DC evaluated clinically and by magnetic resonance imaging. In conclusion, in my thesis I have studied Multiple Sclerosis from clinical and experimental perspective, genetic pathogenesis into therapeutic strategies using magnetic resonance imaging and EAE animal models as tools.
|
|
