| 1. |
- Chen, Jun, et al.
(författare)
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A self-healing elastomer based on an intrinsic non-covalent cross-linking mechanism
- 2019
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Ingår i: Journal of Materials Chemistry A. - : Royal Society of Chemistry. - 2050-7488. ; 7:25, s. 15207-15214
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Tidskriftsartikel (refereegranskat)abstract
- Synthesis and comprehensive examination of a polyurethane (urea) elastomer that self-heals based on intrinsic dynamic non-covalent bonds (van der Waals and hydrogen) are reported. The dynamic non-covalent bonds include hydrogen bonds and van der Waals forces. The difference in the previous approach in which hydrogen bond self-healing materials introduced dense quadruple hydrogen bonds at the ends or branched chains poly(propylene carbonate) (PPC) diol was used as the soft segment of the polyurethane (urea) material, and strong van der Waals forces were provided by the large number of carbonyl groups in its main chain; hydrogen bonds were formed by urethane bonds, urea bonds, and the carbonyl groups on PPC. The mechanical properties and healing efficiency of the self-healing polyurethane (urea) elastomer were studied. In situtemperature-dependent infrared and low-field nuclear magnetic resonance (LNMR) measurements were combined with molecular dynamics simulations to investigate the self-healing mechanisms. The results of the studies on the self-healing polyurethane demonstrate that the dynamic cross-linking between hydrogen bonds and van der Waals forces is the basic driving force for the self-healing ability of the material, and temperature is the key factor that affects hydrogen bonding and van der Waals forces. The effect of crystallization on the self-healing ability of the material was also studied. The molecular dynamics simulation results also demonstrate interplay between van der Waals forces and hydrogen bonds at different temperatures.
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| 2. |
- Chen, Jun, et al.
(författare)
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Genomic data provide new insights on the demographic history and the extent of recent material transfers in Norway spruce
- 2019
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Ingår i: Evolutionary Applications. - : WILEY. - 1752-4571. ; 12:8, s. 1539-1551
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Tidskriftsartikel (refereegranskat)abstract
- Primeval forests are today exceedingly rare in Europe, and transfer of forest reproductive material for afforestation and improvement has been very common, especially over the last two centuries. This can be a serious impediment when inferring past population movements in response to past climate changes such as the last glacial maximum (LGM), some 18,000 years ago. In the present study, we genotyped 1,672 individuals from three Picea species (P. abies, P. obovata, and P. omorika) at 400K SNPs using exome capture to infer the past demographic history of Norway spruce (P. abies) and estimate the amount of recent introduction used to establish the Norway spruce breeding program in southern Sweden. Most of these trees belong to P. abies and originate from the base populations of the Swedish breeding program. Others originate from populations across the natural ranges of the three species. Of the 1,499 individuals stemming from the breeding program, a large proportion corresponds to recent introductions from mainland Europe. The split of P. omorika occurred 23 million years ago (mya), while the divergence between P. obovata and P. abies began 17.6 mya. Demographic inferences retrieved the same main clusters within P. abies than previous studies, that is, a vast northern domain ranging from Norway to central Russia, where the species is progressively replaced by Siberian spruce (P. obovata) and two smaller domains, an Alpine domain and a Carpathian one, but also revealed further subdivision and gene flow among clusters. The three main domains divergence was ancient (15 mya), and all three went through a bottleneck corresponding to the LGM. Approximately 17% of P. abies Nordic domain migrated from P. obovata ~103K years ago, when both species had much larger effective population sizes. Our analysis of genomewide polymorphism data thus revealed the complex demographic history of Picea genus in Western Europe and highlighted the importance of material transfer in Swedish breeding program.
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| 3. |
- Li, Lili, et al.
(författare)
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Clinal variation in growth cessation and FTL2 expression in Siberian spruce
- 2019
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Ingår i: Tree Genetics & Genomes. - : Springer Science and Business Media LLC. - 1614-2942 .- 1614-2950. ; 15:82
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Tidskriftsartikel (refereegranskat)abstract
- Forest trees exhibit strong patterns of local adaptation in phenological traits along latitudinal gradients. Previous studies in spruce have shown that variation at genes from the photoperiodic pathway and the circadian clock are associated to these clines but it has been difficult to find solid evidence of selection for some of these genes. Here, we used growth cessation, gene expression, and single nucleotide polymorphism (SNP) data at two major candidate loci, FLOWERING LOCUS T/TERMINAL FLOWER1-Like2 (FTL2) and GIGANTEA (GI), as well as at background loci from a latitudinal gradient in Siberian spruce (Picea obovata) populations along the Ob River to test for clinal variation in growth cessation and at the two candidate genes. As in previous studies, there was a strong latitudinal cline in growth cessation that was accompanied by a significant cline in the expression of FTL2. Expression of FTL2 was significantly associated with allele frequencies at some of the GI’s SNPs. However, the cline in allele frequency at candidate genes was not as steep as in a Norway spruce cline and in a parallel Siberian spruce cline studied previously and nonsignificant when a correction for population structure was applied. A McDonald-Kreitman test did not detect decisive evidence of selection on GI (p value = 0.07) and could not be applied to FTL2 because of limited polymorphism. Nonetheless, polymorphisms contributed more to the increased neutrality index of PoGI than to that of control loci. Finally, comparing the results of two previously published studies to our new dataset led to the identification of strong candidate SNPs for local adaptation in FTL2 promoter and GI.
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| 4. |
- Mao, Jia, et al.
(författare)
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A hybrid reader tranceiver design for industrial internet of things
- 2016
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Ingår i: Journal of Industrial Information Integration. - : Elsevier. - 2467-964X .- 2452-414X. ; 2, s. 19-29
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Tidskriftsartikel (refereegranskat)abstract
- This paper presents an integrated asymmetric UHF/UWB reader transceiver in 90 nm CMOS technology for industrial enterprise IoT applications. The reader uses UHF transmitter to power up and inventory the tags. Instead of backscattering, tag replies the reader using Ultra-wideband (UWB) pulses, allowing high throughput transmission and precise positioning. Therefore, a UWB receiver is deployed in the proposed reader for data reception and Time-of-Arrival (ToA) estimation using energy detection schemes. The transmitter delivers 160 kb/s ASK modulated data by an integrated modulator and a Digital Controlled Oscillator (DCO). The DCO has 11% tuning range ability to cover different UHF signal channels. On the UWB receiver side, the 3–5 GHz energy detection receiver supports maximum 33 Mb/s data rate in both OOK and PPM modulations. The receiver front-end provides 59 dB voltage gain and 8.5 dB noise figure (NF). Measurement results shows that the receiver achieves an input sensitivity of -79 dBm at 10 Mb/s, and the power consumption of transceiver is 21.5 mW.
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| 5. |
- Milesi, Pascal, et al.
(författare)
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Assessing the potential for assisted gene flow using past introduction of Norway spruce in southern Sweden : Local adaptation and genetic basis of quantitative traits in trees
- 2019
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Ingår i: Evolutionary Applications. - : John Wiley & Sons. - 1752-4571. ; 12:10, s. 1946-1959
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Tidskriftsartikel (refereegranskat)abstract
- Norway spruce (Picea abies) is a dominant conifer species of major economic importance in northern Europe. Extensive breeding programs were established to improve phenotypic traits of economic interest. In southern Sweden, seeds used to create progeny tests were collected on about 3,000 trees of outstanding phenotype (‘plus’ trees) across the region. In a companion paper, we showed that some were of local origin but many were recent introductions from the rest of the natural range. The mixed origin of the trees together with partial sequencing of the exome of >1,500 of these trees and phenotypic data retrieved from the Swedish breeding program offered a unique opportunity to dissect the genetic basis of local adaptation of three quantitative traits (height, diameter and bud-burst) and assess the potential of assisted gene flow. Through a combination of multivariate analyses and genome-wide association studies, we showed that there was a very strong effect of geographical origin on growth (height and diameter) and phenology (bud-burst) with trees from southern origins outperforming local provenances. Association studies revealed that growth traits were highly polygenic and bud-burst somewhat less. Hence, our results suggest that assisted gene flow and genomic selection approaches could help to alleviate the effect of climate change on P. abies breeding programs in Sweden.
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| 6. |
- Zeng, Shumao, et al.
(författare)
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Modeling of solid oxide fuel cells with optimized interconnect designs
- 2018
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Ingår i: International Journal of Heat and Mass Transfer. - : Elsevier BV. - 0017-9310. ; 125, s. 506-514
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Tidskriftsartikel (refereegranskat)abstract
- A 3D model is developed to investigate solid oxide fuel cells (SOFCs) contacting with optimized interconnect designs and the results indicate that the current density and thermal stress are closely related to both the shape of tip in interconnects and the depth of it in the cathode. The interconnect with triangular rips can yield the best electrochemical performance compared to those with tips of rectangle and trapezium, and the current densities increase with the depth of tips in cathodes, except the trapezoidal ribs, which shows a concaving change with the depth. The 1st principle stress reaches around 21.9 MPa and 16.6 MPa at the interfaces of electrodes and electrolytes, but it rises to 60 MPa and 18 MPa for the rectangular tips at the air and fuel inlets, respectively, which sharply decreases to nearly 25 MPa and 10 MPa with the depth in cathodes approaching 5 μm. The maximum shear stresses are found to reach 34.4 MPa and 32.1 MPa at the two interfaces, and the triangular tips will induce the most intensive stresses at electrolyte-cathode interface. The resulting conclusions are beneficial to optimize interconnect design to improve the efficiency of current collection and also reduce the risk of generation of remarkable thermal stresses.
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