| 1. |
- Cheng, Yajuan, et al.
(författare)
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Controllable fabrication of large-area 2D colloidal crystal masks with large size defect-free domains based on statistical experimental design
- 2014
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Ingår i: Applied Surface Science. - : Elsevier BV. - 0169-4332 .- 1873-5584. ; 313, s. 144-151
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Tidskriftsartikel (refereegranskat)abstract
- A large-area hexagonal packed monolayer of silica spheres with consistent defect-free domains of a size larger than 3000 mu m(2) was prepared by spin coating on glass substrates with the assistance of experimental design and statistical analysis. The ratio of the defect-free monolayer area to the square of sphere diameter is nearly two times of the previously reported maximum values. Several parameters involved in the spin coating systems were investigated. The results indicated that the relative humidity and the rotational speed of the first step of the spin coating had the most important impact on the ordering degree of the prepared monolayer. Furthermore, the ordering degree of the obtained monolayer increased with a decreased relative humidity. In addition, it reached an optimal value when the first rotational speed during spin coating reached a value of 1000 rpm. From this study, it can be concluded that statistical experimental design is an efficient strategy, especially for multi-factor phenomenon studies.
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| 2. |
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| 3. |
- Cheng, Yajuan, et al.
(författare)
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Improvement and optimization of the growth quality of upright ZnOrod arrays by the response surface methodology
- 2015
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Ingår i: Applied Surface Science. - Amsterdam : Elsevier. - 0169-4332 .- 1873-5584. ; 351, s. 451-459
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Tidskriftsartikel (refereegranskat)abstract
- Response surface methodology was employed to guide the growth of ZnO rod arrays. With its assistance, the growth quality of the obtained samples was improved dramatically. The morphologies evolved from sparsely, randomly oriented rods to dense and upright rod arrays. Moreover, the significant parameters for ZnO rod arrays growth and their optimal regions were also determined. Furthermore, with the optimized parameters, the obtained aspect ratio of the vertically aligned ZnO rod arrays reached a value of 31. This is relatively a high value of ZnO rod arrays synthesized by wet chemical methods without capping agents in neutral solutions.
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| 4. |
- Cheng, Yajuan, et al.
(författare)
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Optimization of high-quality vertically aligned ZnO rod arrays by the response surface methodology
- 2015
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Ingår i: Journal of Alloys and Compounds. - : Elsevier BV. - 0925-8388 .- 1873-4669. ; 626, s. 180-188
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Tidskriftsartikel (refereegranskat)abstract
- Optimization of the deposition parameters was conducted by the response surface methodology to synthesize high-quality ZnO rod arrays with a high texture coefficient, a large aspect ratio and a narrow bandgap. In addition, mathematical models based on statistical analysis were also developed to predict the texture coefficient, aspect ratio and bandgap of the ZnO rod arrays. With the optimized parameters, all of the three involved responses obtained the desired optimum values. The results show that the texture coefficient can be elevated up to a value of 0.998, which represents an almost perfect value. Moreover, wide range of aspect ratios was obtained for various applications and the obtained maximum value of 21.3 is relatively high value by wet chemical method, especially when no capping agent and no refreshing growth solution in a nearly neutral solution is used.
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| 5. |
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| 6. |
- Cheng, Yajuan, 1987-
(författare)
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Synthesis of well arrayed structures with assistance of statistical experimental design
- 2015
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- During the synthesis of well arrayed nano/micro structures through wet chemical methods, plenty of parameters are usually involved. Consequently, it is extremely time- and cost-consuming to find out the optimized synthesis conditions by using the conventional "changing one separate factor at a time" (COST) strategy. Instead, the "statistical experimental design" method has been proven in a few works to be an efficient method for experiments involving many parameters. With this method, the responses could be optimized efficiently by using only a few experiments. Besides, several responses can be optimized simultaneously. Also, models could be built up and the changing tendency can be plotted to predict the required experimental settings for specific tasks.Two types of well arrayed structures including monolayer arrays of silica spheres and vertically aligned ZnO rod arrays were investigated in this work. Monolayer arrays of silica spheres were synthesized by using a dual-speed spin coating method. With assistance of statistical experimental design, the accelerating rate, the second rotation speed and time of the dual-speed spin coating system were found as non-significant parameters to the ordering degree of the obtained monolayer, and thus they can be fixed. This finding could remarkably increase the feasibility of optimizing the practical process. On the other hand, the relative humidity, the first rotation speed and the suspension concentration are identified as the significant parameters to the structures of the monolayer. Moreover, the optimal values for these three parameters were identified: 23% for the relative humidity, 1000 rpm for the first rotation speed and 30 wt.% for the suspension concentration. With these optimized parameters, the area of the obtained silica sphere monolayers reached over 1 cm2 and the defect-free domain size reached over 4000 μm2. These values are considerably higher compared to the previously reported values.Vertically aligned ZnO rod arrays were fabricated by chemical bath deposition. Parameters including precursor concentration, pH value, reaction temperature, reaction time and addition of capping agent were optimized by using statistical experimental design to improve and optimize the growth quality of ZnO rod arrays. Through several stages of optimization, the growth quality of the obtained structures was remarkably enhanced from sparse or clustered ZnO rods to upright and dense ZnO rods. The boundary conditions to achieve vertically aligned ZnO rods, such as a neutral solution and a precursor concentration over 0.02M, were determined. The changing tendency of the texture coefficient and aspect ratio with the factors was also plotted to predict the required experimental settings for specific requests. The points or regions to achieve the optimal properties were identified as well. For instance, the concentration should be as close as to 0.1 M, while the reaction temperature should be limited to 80-90 ◦C, to achieve the ideal preferential growth. With the optimized parameters, the texture coefficient reached almost the perfect value 1, and the aspect ratio was elevated to 21. Moreover, to obtain a dense ZnO thin film, tri-sodium citrate was added to the reaction system. The diameter was systematically controlled through varying the parameters. When both the diameter and the texture coefficient reached the optimal values, the rods were merged together to form a dense ZnO thin film.Furthermore, comments on the statistical experimental method are proposed, and both the advantages and disadvantages are presented according to the present thesis work. This might help the researchers to avoid the disadvantages and thus to employ this method more efficiently in the future.
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| 7. |
- de Vries, Paul S., et al.
(författare)
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Multiancestry Genome-Wide Association Study of Lipid Levels Incorporating Gene-Alcohol Interactions
- 2019
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Ingår i: American Journal of Epidemiology. - : Oxford University Press. - 0002-9262 .- 1476-6256. ; 188:6, s. 1033-1054
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Tidskriftsartikel (refereegranskat)abstract
- A person's lipid profile is influenced by genetic variants and alcohol consumption, but the contribution of interactions between these exposures has not been studied. We therefore incorporated gene-alcohol interactions into a multiancestry genome-wide association study of levels of high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, and triglycerides. We included 45 studies in stage 1 (genome-wide discovery) and 66 studies in stage 2 (focused follow-up), for a total of 394,584 individuals from 5 ancestry groups. Analyses covered the period July 2014-November 2017. Genetic main effects and interaction effects were jointly assessed by means of a 2-degrees-of-freedom (df) test, and a 1-df test was used to assess the interaction effects alone. Variants at 495 loci were at least suggestively associated (P < 1 x 10(-6)) with lipid levels in stage 1 and were evaluated in stage 2, followed by combined analyses of stage 1 and stage 2. In the combined analysis of stages 1 and 2, a total of 147 independent loci were associated with lipid levels at P < 5 x 10(-8) using 2-df tests, of which 18 were novel. No genome-wide-significant associations were found testing the interaction effect alone. The novel loci included several genes (proprotein convertase subtilisin/kexin type 5 (PCSK5), vascular endothelial growth factor B (VEGFB), and apolipoprotein B mRNA editing enzyme, catalytic polypeptide 1 (APOBEC1) complementation factor (A1CF)) that have a putative role in lipid metabolism on the basis of existing evidence from cellular and experimental models.
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| 8. |
- Feitosa, Mary F., et al.
(författare)
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Novel genetic associations for blood pressure identified via gene-alcohol interaction in up to 570K individuals across multiple ancestries
- 2018
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Ingår i: PLOS ONE. - : Public library science. - 1932-6203. ; 13:6
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Tidskriftsartikel (refereegranskat)abstract
- Heavy alcohol consumption is an established risk factor for hypertension; the mechanism by which alcohol consumption impact blood pressure (BP) regulation remains unknown. We hypothesized that a genome-wide association study accounting for gene-alcohol consumption interaction for BP might identify additional BP loci and contribute to the understanding of alcohol-related BP regulation. We conducted a large two-stage investigation incorporating joint testing of main genetic effects and single nucleotide variant (SNV)-alcohol consumption interactions. In Stage 1, genome-wide discovery meta-analyses in approximate to 131 K individuals across several ancestry groups yielded 3,514 SNVs (245 loci) with suggestive evidence of association (P <1.0 x 10(-5)). In Stage 2, these SNVs were tested for independent external replication in individuals across multiple ancestries. We identified and replicated (at Bonferroni correction threshold) five novel BP loci (380 SNVs in 21 genes) and 49 previously reported BP loci (2,159 SNVs in 109 genes) in European ancestry, and in multi-ancestry meta-analyses (P < 5.0 x 10(-8)). For African ancestry samples, we detected 18 potentially novel BP loci (P< 5.0 x 10(-8)) in Stage 1 that warrant further replication. Additionally, correlated meta-analysis identified eight novel BP loci (11 genes). Several genes in these loci (e.g., PINX1, GATA4, BLK, FTO and GABBR2 have been previously reported to be associated with alcohol consumption. These findings provide insights into the role of alcohol consumption in the genetic architecture of hypertension.
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| 9. |
- Liang, Yongqi, et al.
(författare)
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Achieving High Open-Circuit Voltages up to 1.57 V in Hole-Transport-Material-Free MAPbBr(3) Solar Cells with Carbon Electrodes
- 2018
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Ingår i: Advanced Energy Materials. - : Wiley-VCH Verlagsgesellschaft. - 1614-6832 .- 1614-6840. ; 8:4
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Tidskriftsartikel (refereegranskat)abstract
- An open-circuit voltage (V-oc) of 1.57 V under simulated AM1.5 sunlight in planar MAPbBr(3) solar cells with carbon (graphite) electrodes is obtained. The hole-transport-material-free MAPbBr(3) solar cells with the normal architecture (FTO/TiO2/MAPbBr(3)/carbon) show little hysteresis during current-voltage sweep under simulated AM1.5 sunlight. A solar-to-electricity power conversion efficiency of 8.70% is achieved with the champion device. Accordingly, it is proposed that the carbon electrodes are effective to extract photogenerated holes in MAPbBr(3) solar cells, and the industry-applicable carbon electrodes will not limit the performance of bromide-based perovskite solar cells. Based on the analysis of the band alignment, it is found that the voltage (energy) loss across the interface between MAPbBr(3) and carbon is very small compared to the offset between the valence band maximum of MAPbBr(3) and the work function of graphite. This finding implies either Fermi level pinning or highly doped region inside MAPbBr(3) layer exists. The band-edge electroluminescence spectra of MAPbBr(3) from the solar cells further support no back-transfer pathways of electrons across the MAPbBr(3)/TiO2 interface.
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| 10. |
- Sheng, Xiaofei, et al.
(författare)
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Controllable Fabrication of Large-Size Defect-Free Domains of 2D Colloidal Crystal Masks Guided by Statistical Experimental Design
- 2021
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Ingår i: Coatings. - : MDPI. - 2079-6412. ; 11:1
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Tidskriftsartikel (refereegranskat)abstract
- Large defect-free domains of a hexagonal packed monolayer of silica spheres with the size of 4000 mu m(2) were successfully prepared by dual-speed spin coating. Experimental design and statistical analysis instead of the traditional 'changing one separate factor at a time' (COST) approach were employed to guide the implementation of the experiments. With its assistance, the hexagonal-close-packed (HCP) percentage was elevated to 84% in this study. Furthermore, almost all the samples with parameters in the selected ranges possessed more than a 60% HCP percentage. In addition, the optimal values for parameters of the suspension concentration, the first rotation speed, and the spinning time to obtain well-ordered silica spheres arrays were also identified as 30 wt.%, 1000 rpm and 20 s, respectively.
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