| 920111. |
- Liu, Hai-Bin, et al.
(author)
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Synthesis of Tri- and Disalicylaldehydes and Their Chiral Schiff Base Compounds
- 2010
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In: Synthetic Communications. - : Informa UK Limited. - 0039-7911 .- 1532-2432. ; 40:7, s. 1074-1081
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Journal article (peer-reviewed)abstract
- A suitable procedure for convenient preparation of 1,3,5-tris(4-hydroxy-5-formylphenyl)benzene (6) was exploited via 5-bromosalicylaldehyde as starting reactant. Among the obtained products, compound 6, 4-methoxy-3-formylphenylboronic acid (9), 1,3,5-tris(4-methoxy-5-formylphenyl)benzene (10), and 4-methoxy-4'-hydroxyl-3,3'-diformyl-1,1'-diphenyl (11) had not been reported previously. Two new chiral Schiff base ligands, L1 and L2, were obtained from the tri- or disalicylaldehydes.
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| 920112. |
- Liu, Haichun, et al.
(author)
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Balancing power density based quantum yield characterization of upconverting nanoparticles for arbitrary excitation intensities.
- 2013
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In: Nanoscale. - : Royal Society of Chemistry (RSC). - 2040-3372 .- 2040-3364. ; 5:11, s. 4770-4775
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Journal article (peer-reviewed)abstract
- Upconverting nanoparticles (UCNPs) have recently shown great potential as contrast agents in biological applications. In developing different UCNPs, the characterization of their quantum yield (QY) is a crucial issue, as the typically drastic decrease in QY for low excitation power densities can either impose a severe limitation or provide an opportunity in many applications. The power density dependence of the QY is governed by the competition between the energy transfer upconversion (ETU) rate and the linear decay rate in the depopulation of the intermediate state of the involved activator in the upconversion process. Here we show that the QYs of Yb(3+) sensitized two-photon upconversion emissions can be well characterized by the balancing power density, at which the ETU rate and the linear decay rate have equal contributions, and its corresponding QY. The results in this paper provide a method to fully describe the QY of upconverting nanoparticles for arbitrary excitation power densities, and is a fast and simple approach for assessing the applicability of UCNPs from the perspective of energy conversion.
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| 920113. |
- Liu, Han, et al.
(author)
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BarR, an Lrp-type transcription factor in Sulfolobus acidocaldarius, regulates an aminotransferase gene in a beta- alanine responsive manner
- 2014
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In: Molecular Microbiology. - : Wiley. - 0950-382X .- 1365-2958. ; 92:3, s. 625-639
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Journal article (peer-reviewed)abstract
- In archaea, nothing is known about the -alanine degradation pathway or its regulation. In this work, we identify and characterize BarR, a novel Lrp-like transcription factor and the first one that has a non-proteinogenic amino acid ligand. BarR is conserved in Sulfolobus acidocaldarius and Sulfolobus tokodaii and is located in a divergent operon with a gene predicted to encode -alanine aminotransferase. Deletion of barR resulted in a reduced exponential growth rate in the presence of -alanine. Furthermore, qRT-PCR and promoter activity assays demonstrated that BarR activates the expression of the adjacent aminotransferase gene, but only upon -alanine supplementation. In contrast, auto-activation proved to be -alanine independent. Heterologously produced BarR is an octamer in solution and forms a single complex by interacting with multiple sites in the 170bp long intergenic region separating the divergently transcribed genes. In vitro, DNA binding is specifically responsive to -alanine and site-mutant analyses indicated that -alanine directly interacts with the ligand-binding pocket. Altogether, this work contributes to the growing body of evidence that in archaea, Lrp-like transcription factors have physiological roles that go beyond the regulation of -amino acid metabolism.
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| 920114. |
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| 920115. |
- Liu, Hebin, et al.
(author)
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Calcium regulation of GM-CSF by calmodulin-dependent kinase II phosphorylation of Ets1
- 2002
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In: Molecular Biology of the Cell. - 1059-1524 .- 1939-4586. ; 13:12, s. 4497-4507
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Journal article (peer-reviewed)abstract
- The multipotent cytokine granulocyte macrophage-colony stimulating factor (GM-CSF) is involved in particular in the physiological response to infection and in inflammatory responses. GM-CSF is produced by many cell types, including T lymphocytes responding to T-cell receptor activation and mantle zone B lymphocytes. B-cell receptor and T-cell receptor activation generates two major signals: an increase in intracellular Ca(2+) concentration and a protein kinase cascade. Previous studies have shown that the Ca(2+)/calmodulin-dependent phosphatase calcineurin mediates stimulation of GM-CSF transcription in response to Ca(2+). In this study, we show that Ca(2+) signaling also regulates GM-CSF transcription negatively through Ca(2+)/calmodulin-dependent kinase II (CaMK II) phosphorylation of serines in the autoinhibitory domain for DNA binding of the transcription factor Ets1. Wild-type Ets1 negatively affects GM-CSF transcription on Ca(2+) stimulation in the presence of cyclosporin A, which inhibits calcineurin. Conversely, Ets1 with mutated CaMK II target serines showed an increase in transactivation of the GM-CSF promoter/enhancer. Moreover, constitutively active CaMK II inhibited transactivation of GM-CSF by wild-type Ets1 but not by Ets1 with mutated CaMK II sites. Mutation of CaMK II target serines in Ets1 also relieves inhibition of cooperative transactivation of GM-CSF with the Runx1/AML1 transcription factor. In addition, the Ca(2+)-dependent phosphorylation of Ets1 reduces the binding of Ets1 to the GM-CSF promoter in vivo.
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| 920116. |
- Liu, Huayang, et al.
(author)
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Cathode Pressure Control of Air Supply System for PEMFC
- 2021
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In: IFAC-PapersOnLine. - : Elsevier BV. - 2405-8963 .- 2405-8963. ; 54:10, s. 247-252
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Conference paper (peer-reviewed)abstract
- This paper proposes a backstepping method controller for the polymer electrolyte membrane fuel cell (PEMFC)air supply system. The control objective is adjusting the cathode pressure to its reference value quickly, in order to solve the problem of excessive extreme pressure difference between anode and cathode in practice. Considering model uncertainty and some disturbances, we design an extend state observer (ESO) to estimate disturbances. Next, a backstepping method is proposed to adjust control law. Finally, the experiment results demonstrate the effectiveness and robustness of the control strategy.
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| 920117. |
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| 920118. |
- Liu, Hui, et al.
(author)
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Centromere-Specific Retrotransposons and Very-Long-Chain Fatty Acid Biosynthesis in the Genome of Yellowhorn (Xanthoceras sorbifolium, Sapindaceae), an Oil-Producing Tree With Significant Drought Resistance
- 2021
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In: Frontiers in Plant Science. - : Frontiers Media S.A.. - 1664-462X. ; 12
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Journal article (peer-reviewed)abstract
- In-depth genome characterization is still lacking for most of biofuel crops, especially for centromeres, which play a fundamental role during nuclear division and in the maintenance of genome stability. This study applied long-read sequencing technologies to assemble a highly contiguous genome for yellowhorn (Xanthoceras sorbifolium), an oil-producing tree, and conducted extensive comparative analyses to understand centromere structure and evolution, and fatty acid biosynthesis. We produced a reference-level genome of yellowhorn, ∼470 Mb in length with ∼95% of contigs anchored onto 15 chromosomes. Genome annotation identified 22,049 protein-coding genes and 65.7% of the genome sequence as repetitive elements. Long terminal repeat retrotransposons (LTR-RTs) account for ∼30% of the yellowhorn genome, which is maintained by a moderate birth rate and a low removal rate. We identified the centromeric regions on each chromosome and found enrichment of centromere-specific retrotransposons of LINE1 and Gypsy in these regions, which have evolved recently (∼0.7 MYA). We compared the genomes of three cultivars and found frequent inversions. We analyzed the transcriptomes from different tissues and identified the candidate genes involved in very-long-chain fatty acid biosynthesis and their expression profiles. Collinear block analysis showed that yellowhorn shared the gamma (γ) hexaploidy event with Vitis vinifera but did not undergo any further whole-genome duplication. This study provides excellent genomic resources for understanding centromere structure and evolution and for functional studies in this important oil-producing plant.
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| 920119. |
- Liu, Hongyuan, et al.
(author)
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Characterisation of rock aggregate breakage properties using realistic texture-based modelling
- 2012
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In: International Journal for Numerical and Analytical Methods in Geomechanics. - : Wiley. - 0363-9061 .- 1096-9853. ; 36:10, s. 1280-1302
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Journal article (peer-reviewed)abstract
- Realistic texture-based modelling methods, that is microstructural modelling and micromechanical modelling, are developed to simulate the rock aggregate breakage properties on the basis of the rock actual microstructure obtained using microscopic observations and image analysis. The breakage properties of three types of rocks, that is Avja, LEP and Vandle taken from three quarries in Sweden, in single aggregate breakage tests and in inter-aggregate breakage tests are then modelled using the proposed methods. The microstructural modelling directly integrates the microscopic observation, image analysis and numerical simulation together and provides a valuable tool to investigate the mechanical properties of rock aggregates on the basis of their microstructure properties. The micromechanical modelling takes the most important microstructure properties of rock aggregates into consideration and can model the major mechanical properties. Throughout this study, it is concluded that in general, the microstructure properties of rock aggregate work together to affect their mechanical properties, and it is difficult to correlate a single microstructure property with the mechanical properties of rock aggregates. In particular, for the three types of rock Avja, LEP and Vandle in this study, crack size distribution, grain size and grain perimeter (i.e. grain shape and spatial arrangement) show good correlations with the mechanical properties. The crack length and the grain size negatively affect the mechanical properties of Avja, LEP and Vandle, but the perimeter positively influences the mechanical properties. Besides, the modelled rock aggregate breakage properties in both single aggregate and inter-aggregate tests reveal that the aggregate microstructure, aggregate shape and loading conditions influence the breakage process of rock aggregate in service. For the rock aggregate with the same microstructure, the quadratic shape and good packing dramatically improve its mechanical properties. During services, the aggregate is easiest to be fragmented under point-to-point loading condition, and then in the sequence of multiple-point, point-to-plane and plane-to-plane loading conditions.
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| 920120. |
- Liu, Hongyuan, et al.
(author)
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Characterization of rock heterogeneity and numerical verification
- 2004
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In: Engineering Geology. - : Elsevier BV. - 0013-7952 .- 1872-6917. ; 72:1, s. 89-119
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Journal article (peer-reviewed)abstract
- On the basis of microstructure analysis and image analysis, rock heterogeneity is modelled by the rock and tool (R-T2D) interaction code according to homogenisation theory. The simulated results predict very well the non-linear stress–strain behaviour and the progressive fracture process of heterogeneous rock material. It is found that the weak parts and subsequent fractures before localization represent an obvious statistically uniform characteristic. Therefore, a statistical method is used to model rock heterogeneity. The results from the statistical modelling are in surprisingly good agreement with those from the homogenisation modelling. Considering the research scale, the rock heterogeneity is characterized better by the Weibull statistical method as a few characteristic parameters: the homogeneous index and the elemental seed parameters of the R-T2D finite element network. Finally, a series of numerical experiments are conducted to validate that the characterization of rock heterogeneity is reasonable and feasible, and that the R-T2D code is stable, repeatable and a valuable tool to research the fracture process of heterogeneous material.
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