| 1. |
- Tran, Ngoc Hieu, et al.
(author)
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Genetic profiling of Vietnamese population from large-scale genomic analysis of non-invasive prenatal testing data
- 2020
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In: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 10:1
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Journal article (peer-reviewed)abstract
- The under-representation of several ethnic groups in existing genetic databases and studies have undermined our understanding of the genetic variations and associated traits or diseases in many populations. Cost and technology limitations remain the challenges in performing large-scale genome sequencing projects in many developing countries, including Vietnam. As one of the most rapidly adopted genetic tests, non-invasive prenatal testing (NIPT) data offers an alternative untapped resource for genetic studies. Here we performed a large-scale genomic analysis of 2683 pregnant Vietnamese women using their NIPT data and identified a comprehensive set of 8,054,515 single-nucleotide polymorphisms, among which 8.2% were new to the Vietnamese population. Our study also revealed 24,487 disease-associated genetic variants and their allele frequency distribution, especially 5 pathogenic variants for prevalent genetic disorders in Vietnam. We also observed major discrepancies in the allele frequency distribution of disease-associated genetic variants between the Vietnamese and other populations, thus highlighting a need for genome-wide association studies dedicated to the Vietnamese population. The resulted database of Vietnamese genetic variants, their allele frequency distribution, and their associated diseases presents a valuable resource for future genetic studies.
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| 2. |
- Li, Yutang, et al.
(author)
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Enantiotopic Discrimination by Coordination-Desymmetrized meso-Ligands
- 2020
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In: ChemCatChem. - : Wiley. - 1867-3880 .- 1867-3899. ; 12:6, s. 1575-1579
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Journal article (peer-reviewed)abstract
- The first examples of enantiopure catalysts that are chiral merely due to coordination of different metal ions at enantiotopic positions of an achiral meso-ligand are reported. These catalysts exhibit a pseudo-Cs symmetry and are able to catalyze reactions demanding simultaneous involvement of two catalytic sites. The latter was demonstrated by application in the asymmetric ring-opening of meso-epoxides.
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| 3. |
- Olsson, Joel, et al.
(author)
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Functionalizing polystyrene with N-alicyclic piperidine-based cations via Friedel-Crafts alkylation for highly alkali-stable anion-exchange membranes
- 2020
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In: Macromolecules. - : American Chemical Society (ACS). - 0024-9297 .- 1520-5835. ; 53:12, s. 4722-4732
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Journal article (peer-reviewed)abstract
- Different anion-exchange membranes (AEMs) based on polystyrene (PS) carrying benzyltrimethyl ammonium cations are currently developed for use in alkaline fuel cells and water electrolyzers. However, the stability of these state-of-the-art cations needs to be further improved. Here, we introduce highly alkali-stable mono- and spirocyclic piperidine-based cations onto PS by first performing a superacid mediated Friedel-Crafts alkylation using 2-(piperidine-4-yl)propane-2-ol. This is followed by quaternization of the piperidine rings either using iodomethane to produce N,N-dimethylpiperidinium cations or cyclo-quaternizations using 1,5-dibromopentane and 1,4-dibromobutane, respectively, to obtain N-spirocyclic quaternary ammonium cations. Thus, it is possible to functionalize up to 27% of the styrene units with piperidine rings, and subsequently achieve complete quaternization. The synthetic approach ensures that all the sensitive β-hydrogens of the cations are present in ring structures to provide high stability. AEMs based on these polymers show high alkaline stability and less than 5% ionic loss was observed by 1H NMR spectroscopy after 30 days in 2 M aq. NaOH at 90 °C. AEMs functionalized with N,N-dimethylpiperidinium cations show a higher stability than the ones carrying N-spirocyclic quaternary ammonium. Careful analysis of the latter revealed that the rings formed in the cyclo-quaternization are more prone to degrade via Hofmann elimination than the rings introduced in the Friedel-Crafts reaction. AEMs with an ion exchange capacity of 1.5 meq g-1 reach a hydroxide conductivity of 106 mS cm-1 at 80 °C under fully hydrated conditions. The AEMs are further tuned and improved by blending with polybenzimidazole (PBI). For example, an AEM containing 2 wt% PBI shows reduced water uptake and much improved robustness during handling, and reaches 71 mS cm-1 at 80 °C. The study demonstrates that the critical alkaline stability of PS-containing AEMs can be significantly enhanced by replacing the benchmark benzyltrimethyl ammonium cations with N-alicyclic piperidine-based cations.
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| 4. |
- Pham, Thanh Huong, et al.
(author)
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Rational molecular design of anion exchange membranes functionalized with alicyclic quaternary ammonium cations
- 2020
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In: Polymer Chemistry. - 1759-9962. ; 11:43, s. 6953-6963
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Journal article (peer-reviewed)abstract
- High alkaline stability is critical for polymeric anion exchange membranes (AEMs) and ionomers for use in alkaline electrochemical energy conversion and storage devices such as fuel cells, electrolyzer cells and advanced batteries. Here, we have prepared and studied ether-free polyfluorenes tethered with N,N-dimethylpiperidinium (DMP) and 6-azonia-spiro[5.5]undecane (ASU) cations, respectively, attached thorough heteroatom-free alkyl spacers. By employing alkyl-alkyl Suzuki cross-coupling, these alicyclic quaternary ammonium cations are attached at the 4-position to impede ionic loss. Thus, all the β-hydrogens sensitive to elimination reactions are placed in strain-free rings able to fully relax by the spacer flexibility. Consequently, the AEM carrying DMP cations shows a very high alkaline and thermal stability, retaining more than 91% of the cations after 2,400 h immersion in 2 M NaOH at 90 °C. Compared with corresponding AEMs functionalized with N-alkyl-N-methylpiperidinium (AMP) cations (conventionally tethered via the 1(N)-position), the ionic loss by β-elimination is successfully reduced by up to 92%. AEMs functionalized with DMP also reach a high hydroxide conductivity of 124 mS cm-1 at 80 °C. Consequently, tethering piperidine-based cations via the 4-position instead of the 1(N)-position results in AEMs with substantially improved thermal and alkaline stability, combined with high hydroxide conductivity.
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