| 3811. |
- Xie, L., et al.
(författare)
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Strained Si0.2ge0.8/ge multilayer stacks epitaxially grown on a low-/high-temperature ge buffer layer and selective wet-etching of germanium
- 2020
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Ingår i: Nanomaterials. - : MDPI AG. - 2079-4991. ; 10:9, s. 1-12
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Tidskriftsartikel (refereegranskat)abstract
- With the development of new designs and materials for nano-scale transistors, vertical Gate-All-Around Field Effect Transistors (vGAAFETs) with germanium as channel materials have emerged as excellent choices. The driving forces for this choice are the full control of the short channel effect and the high carrier mobility in the channel region. In this work, a novel process to form the structure for a VGAA transistor with a Ge channel is presented. The structure consists of multilayers of Si0.2Ge0.8/Ge grown on a Ge buffer layer grown by the reduced pressure chemical vapor deposition technique. The Ge buffer layer growth consists of low-temperature growth at 400 °C and high-temperature growth at 650 °C. The impact of the epitaxial quality of the Ge buffer on the defect density in the Si0.2Ge0.8/Ge stack has been studied. In this part, different thicknesses (0.6, 1.2 and 2.0 µm) of the Ge buffer on the quality of the Si0.2Ge0.8/Ge stack structure have been investigated. The thicker Ge buffer layer can improve surface roughness. A high-quality and atomically smooth surface with RMS 0.73 nm of the Si0.2Ge0.8/Ge stack structure can be successfully realized on the 1.2 µm Ge buffer layer. After the epitaxy step, the multilayer is vertically dry-etched to form a fin where the Ge channel is selectively released to SiGe by using wet-etching in HNO3 and H2O2 solution at room temperature. It has been found that the solution concentration has a great effect on the etch rate. The relative etching depth of Ge is linearly dependent on the etching time in H2O2 solution. The results of this study emphasize the selective etching of germanium and provide the experimental basis for the release of germanium channels in the future. © 2020 by the authors. Licensee MDPI, Basel, Switzerland.
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| 3812. |
- Xie, L. Y., et al.
(författare)
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Calculations of electron-impact excitation and dielectronic recombination rate coefficients of highly charged silicon ions
- 2022
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Ingår i: Physical Review A: covering atomic, molecular, and optical physics and quantum information. - 2469-9926 .- 2469-9934. ; 105:1
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Tidskriftsartikel (refereegranskat)abstract
- The rate coefficients for dielectronic recombination and electron-impact excitation processes with H-like to Be-like silicon ions (Si13+−Si10+) are calculated using relativistic distorted-wave approach. The prominent △n=1 and the weaker △n=2 and 3 dielectronic recombination (DR) resonances with K-shell excitations are presented, and compared with the existing DR experimental rate coefficients of Si13+, Si12+, and Si11+ ions, it is found that the theoretical DR rate coefficients are in very good agreement with the experimental results. With the same approach, the direct and resonant electron-impact excitation (EIE) cross sections associated with 1s−n′l′ core excitations are calculated for the ground states of Si13+−Si10+ ions and found in excellent agreement with the available experiment. Finally, we present the synthesized DR and EIE rate coefficients for the sum of all detected (13+∼10+) charge states of Si and these agree well with the experimental results.
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| 3813. |
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| 3814. |
- Xie, Y. C., et al.
(författare)
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Molecular dynamics study of the recognition of ATP by nucleic acid aptamers
- 2020
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Ingår i: Nucleic acids research. - : Oxford University Press (OUP). - 1362-4962 .- 0305-1048. ; 48:12, s. 6471-6480
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Tidskriftsartikel (refereegranskat)abstract
- Despite their great success in recognizing small molecules in vitro, nucleic acid aptamers are rarely used in clinical settings. This is partially due to the lack of structure-based mechanistic information. In this work, atomistic molecular dynamics simulations are used to study the static and dynamic supramolecular structures relevant to the process of the wild-type (wt) nucleic acid aptamer recognition and binding of ATP. The effects brought about by mutation of key residues in the recognition site are also explored. The simulations reveal that the aptamer displays a high degree of rigidity and is structurally very little affected by the binding of ATP. Interaction energy decomposition shows that dispersion forces from π-stacking between ATP and the G6 and A23 nucleobases in the aptamer binding site plays a more important role in stabilizing the supramolecular complex, compared to hydrogen-bond interaction between ATP and G22. Moreover, metadynamics simulations show that during the association process, water molecules act as essential bridges connecting ATP with G22, which favors the dynamic stability of the complex. The calculations carried out on three mutated aptamer structures confirm the crucial role of the hydrogen bonds and π-stacking interactions for the binding affinity of the ATP nucleic acid aptamer. © The Author(s) 2020. Published by Oxford University Press on behalf of Nucleic Acids Research.
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| 3815. |
- Xie, Y., et al.
(författare)
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Development and validation of multilayer perceptual neural network in glomerular filtration rate evaluation
- 2022
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Ingår i: Chinese Journal of Nephrology. - : Chinese Medical Journals Publishing House Co.Ltd. - 1001-7097. ; 38:5, s. 369-378
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Tidskriftsartikel (refereegranskat)abstract
- Objective To develop a neural network model for the evaluation of glomerular filtration rate (GFR) based on multilayer perceptual neural network, and to compare with the improved Chinese based creatinine GFR evaluation formula (C - GFRcr) and the evaluation formula (EPI - GFRcr) of the American Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) for the clinical applicability of multilayer perceptual neural network model in evaluating GFR. Methods A total of 684 chronic kidney disease (CKD) patients used for developing a modified version of China′s based creatinine GFR evaluation formula were taken as the research object. The data of 454 patients were randomly selected as the development group and the data of the other 230 patients were as the verification group. The multilayer perceptual neural network GFR evaluation model (M - GFRcr) was established. With the double plasma GFR as the reference value (rGFR), the correlation, mean difference, mean absolute difference, precision and accuracy of C - GFRcr, EPI - GFRcr and M - GFRcr were compared. Results Among the 684 CKD patients, there were 352 males and 332 females, with age of (49.9 ± 15.8) years. The correlation between M - GFRcr and rGFR was the highest (Pearson correlation =0.93, P＜0.001). The mean difference of M - GFRcr was lower than that of C - GFRcr (Z=9.929, P＜0.001) and EPI - GFRcr (Z=10.573, P＜0.001). The mean absolute difference of M - GFRcr was also lower than that of C - GFRcr (Z=3.953, P＜0.001) and EPI - GFRcr (Z=4.210, P＜0.001). The accuracy of ± 15% of M - GFRcr was higher than that of C - GFRcr (χ2=26.068, P＜0.001) and EPI - GFRcr (χ2=23.154, P＜0.001). The accuracy of ±30% of M-GFRcr was also higher than that of C-GFRcr (χ2=8.264, P=0.001) and EPI-GFRcr (χ2=11.963, P=0.001). The results of different stages of CKD showed that in the early stage of CKD (CKD 1-2), the mean difference of M - GFRcr was lower than that of C - GFRcr (Z=7.401, P＜0.001) and EPI - GFRcr (Z=8.096, P ＜ 0.001); the mean absolute difference of M - GFRcr was also lower than that of C - GFRcr (Z=4.723, P＜0.001) and EPI - GFRcr (Z=4.946, P＜0.001); the accuracy of ±15% of M - GFRcr was higher than that of C - GFRcr (χ2=23.547, P＜0.001) and EPI - GFRcr (χ2=26.421, P＜0.001); the accuracy of ± 30% of M - GFRcr was also higher than that of C - GFRcr (χ2=12.089, P=0.001) and EPI - GFRcr (χ2=16.168, P ＜ 0.001). But there was no significant difference in the applicability among C - GFRcr, EPI - GFRcr and M - GFRcr in the advanced stages of CKD (CKD 3-5). Conclusion Compared with the improved Chinese based creatinine GFR evaluation formula C - GFRcr and CKD - EPI evaluation formula EPI - GFRcr, the accuracy of multilayer perceptual neural network model to evaluate GFR in CKD patients has been significantly improved, especially in CKD 1-2 stage.
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| 3816. |
- Xiong, M., et al.
(författare)
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41.6 Gb/s RZ-DPSK to NRZ-DPSK format conversion in a microring resonator
- 2012
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Ingår i: 2012 17th Opto-Electronics and Communications Conference. ; , s. 891-892
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Konferensbidrag (refereegranskat)abstract
- RZ-DPSK to NRZ-DPSK format conversion in a silicon microring resonator is demonstrated experimentally for the first time at 41.6 Gb/s. The converted signal eye diagrams and bit-error-rate measurements show the good performance of the scheme.
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| 3817. |
- Xiong, R., et al.
(författare)
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A data-driven method for extracting aging features to accurately predict the battery health
- 2023
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Ingår i: Energy Storage Materials. - : Elsevier B.V.. - 2405-8289 .- 2405-8297. ; 57, s. 460-470
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Tidskriftsartikel (refereegranskat)abstract
- Data-driven methods have been widely used for estimating the state of health (SOH) of lithium-ion batteries (LiBs). The aging process can be characterized by degrading features. To achieve high accuracy, a novel method combining four algorithms, i.e. the correlation coefficient, least absolute shrinkage and selection operator regression, neighborhood component analysis, and ReliefF algorithm, is proposed to select the most important features, which are derived from the measured and calculated parameters. To demonstrate the effectiveness of the proposed method, it is adopted to estimate the SOH of two types of LiBs: i.e. NCA and LFP batteries. Compared to the case using all features, using the selected features can improve the accuracy of SOH estimation by 63.5% and 71.1% for the NCA and LFP batteries, respectively. The method can also enable the use of data obtained in partial voltage ranges, based on which the minimum root mean square errors on SOH estimation are 1.2% and 1.6% for the studied NCA and LFP batteries, respectively. It demonstrates the capability for onboard applications.
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| 3818. |
- Xiong, Y, et al.
(författare)
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A characteristic study on the start-up performance of molten-salt heat pipes : Experimental investigation
- 2017
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Ingår i: Experimental Thermal and Fluid Science. - : Elsevier BV. - 0894-1777 .- 1879-2286. ; 82, s. 433-438
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Tidskriftsartikel (refereegranskat)abstract
- This paper reports a fundamental experimental investigation of the start-up characteristics of heat pipes using a dedicated molten-salt mixture as the working fluid. Based on four single salt, i.e. NaNO3(AR), KNO3(AR), LiNO3(AR) and Ca(NO3)2(AR), a quaternary molten-salt working fluid was developed and charged at different masses into four heat pipes with the same dimensions of 980 mm in length and 22 mm in diameter. A parallel comparison on the start-up performance of these heat pipes was then conducted to observe the influence of the charging mass and the inclination angle under the consistent lab-controlled conditions. The experimental results showed the heat pipe with molten-salt charge of 40 g responded much quicker than those with molten salt charge of 60 g, 70 g and 80 g respectively; meanwhile, the molten-salt heat pipe achieved the maximum condensation temperature at inclination angle of 50°. Comparing to the conventional naphthalene heat pipe, the dedicated molten-salt heat pipe had a much shorter start-up time when they were charged with the same amount of 40 g. The overall research result is expected to provide certain guidance for further design and operation of molten-salt heat pipe in high-and-medium-temperature heat transfer and storage scenarios.
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| 3819. |
- Xu, An, et al.
(författare)
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Rewired m6A epitranscriptomic networks link mutant p53 to neoplastic transformation
- 2023
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Ingår i: Nature Communications. - : Springer Nature. - 2041-1723. ; 14:1
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Tidskriftsartikel (refereegranskat)abstract
- N6-methyladenosine (m6A), one of the most prevalent mRNA modifications in eukaryotes, plays a critical role in modulating both biological and pathological processes. However, it is unknown whether mutant p53 neomorphic oncogenic functions exploit dysregulation of m6A epitranscriptomic networks. Here, we investigate Li-Fraumeni syndrome (LFS)-associated neoplastic transformation driven by mutant p53 in iPSC-derived astrocytes, the cell-of-origin of gliomas. We find that mutant p53 but not wild-type (WT) p53 physically interacts with SVIL to recruit the H3K4me3 methyltransferase MLL1 to activate the expression of m6A reader YTHDF2, culminating in an oncogenic phenotype. Aberrant YTHDF2 upregulation markedly hampers expression of multiple m6A-marked tumor-suppressing transcripts, including CDKN2B and SPOCK2, and induces oncogenic reprogramming. Mutant p53 neoplastic behaviors are significantly impaired by genetic depletion of YTHDF2 or by pharmacological inhibition using MLL1 complex inhibitors. Our study reveals how mutant p53 hijacks epigenetic and epitranscriptomic machinery to initiate gliomagenesis and suggests potential treatment strategies for LFS gliomas.
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| 3820. |
- Xu, C., et al.
(författare)
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Crystallographic Analysis of Nucleation at Hardness Indentations in High-Purity Aluminum
- 2016
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Ingår i: Metallurgical and Materials Transactions. A. - : Springer. - 1073-5623 .- 1543-1940. ; 47:12, s. 5863-5870
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Tidskriftsartikel (refereegranskat)abstract
- Nucleation at Vickers hardness indentations has been studied in high-purity aluminum cold-rolled 12 pct. Electron channeling contrast was used to measure the size of the indentations and to detect nuclei, while electron backscattering diffraction was used to determine crystallographic orientations. It is found that indentations are preferential nucleation sites. The crystallographic orientations of the deformed grains affect the hardness and the nucleation potentials at the indentations. Higher hardness gives increased nucleation probabilities. Orientation relationships between nuclei developed at different indentations within one original grain are analyzed and it is found that the orientation distribution of the nuclei is far from random. It is suggested that it relates to the orientations present near the indentation tips which in turn depend on the orientation of the selected grain in which they form. Finally, possible nucleation mechanisms are briefly discussed. © 2016, The Minerals, Metals & Materials Society and ASM International.
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