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  • Author: J. Sun x
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Abstract

In eastern North America, evidence for cryptic northern refugia could contribute to resolving Reid’s Paradox, the disparity between the rate of oak recolonization indicated by pollen deposition and the rate indicated by contemporary seed dispersal studies. Severe anthropogenic disturbance of oak-dominated forests throughout eastern North America followed by regeneration from isolated patches and deliberate planting in some regions could obscure the signal of discontinuity expected from small, cryptic refugia. In this study of northern red oak, Quercus rubra L., the dominant representative of Quercus section Lobatae in the eastern United States, we address the question of appropriate sample size for accurate detection of the biogeographical distribution of chloroplast haplotype diversity in Q. rubra. We examined chloroplast DNA (cpDNA) variation in all Q. rubra over 17 cm in diameter (310 trees) in three forest fragments with documented histories of minimal disturbance for the last 100-190 years. cpDNA polymorphisms in three intergenic regions revealed different haplotype frequencies between the two local fragments located within 1 km of each other and complete discontinuity for the predominant haplotype between these two sites and a site 207 km distant. Haplotypes displayed positive spatial autocorrelation over 10-40 meter distances. Sample sizes of 10 or fewer taken at 50 meter intervals along a linear transect yielded poor estimates of haplotype frequencies and did not accurately detect haplotype richness.

Abstract

Sintering of Cr-prealloyed PM steels requires atmospheres with good quality – low oxygen potential – to achieve satisfactory sintering results. But during heating even the best atmospheres may be oxidizing, the system turns to reducing conditions only at high temperatures, which can be monitored by thermal analysis. During the dewaxing process, oxidizing conditions are favourable for effective dewaxing without sooting and blistering. However, this may result in some oxygen pickup during heating, and then the final properties of the produced parts may be strongly influenced by this intermediate oxidation. This study demonstrates the behaviour of artificially oxidized steels (Fe-C and Fe3Cr-0.5Mo-C) during the sintering process by stepwise sintering. Iron and steel powder were slightly oxidized and then pressed and sintered at different temperatures. In parallel, as a second approach, pressed samples were oxidized and then sintered. Density, hardness and impact energy were measured and dilatometry/MS was used for online monitoring of the sintering process. The starting oxygen content of 0.20 to 0.30 wt% is high enough to change the sintering behaviour of the materials, but still leads to rather good properties. Thermal analysis showed that most of the oxygen picked up was present as iron oxides on the surface which were reduced by hydrogen at rather low temperatures, confirming that these were iron oxides, which also holds for the Cr-prealloyed variant. The biggest influence on the final performance was exerted by the final carbon content and the microstructural development of the material.

Abstract

Experiments were conducted from 1996 to 1998 at the Hefei Institute of Economics and Technology and at the Oriental Experimental Station of the Zhejiang Province (China). Seven F1 hybrids and three parental varieties of Oriental tobaccos were evaluated for the characteristics of photosynthetic and transpiration rates, esterase isozymes, resistance to black shank, quality and product potential from the 1996-1998 growing seasons. Tobacco leaves had higher photosynthetic rates and many differences among genotypes in the early stage of plant vigorous growth compared with more mature leaves. However, transpiration rates were lower in the younger leaves and greater in the more mature leaves. All the entries had four common bands (B1, B3, B4 and B6) of the esterase isoenzymes. Differences between entries resulted from in having or not having the B2 and B5 bands and color intensity differences of all the bands. These differences could be used to identify individual entries. The F1hybrids Samsun X Toy and Samsun X Argjiro, compared with the CK Samsun control, had obvious heterotic vigor in the characteristics of product, for yield, quality and resistance to black shank. The F1 hybrid Samsun X Toy maintained higher photosynthetic and transpiration rates in the two growth stages compared to other entries. However, the F1hybrid Samsun X Argjiro had higher photosynthetic rates and lower transpiration rates in the early growth stage and the two rates were lower in the later stage, but it maintained higher photosynthetic rates for the whole growth stage. Net photosynthetic rates had a significant positive correlation with yield product, quality and resistance to black shank of the Oriental tobacco F1hybrids.

Abstract

Niche sports have limited opportunities to promote their sport offerings via traditional communication channels and may rely upon alternatives such as social media to accomplish their marketing goals (). developed a relationship marketing conceptual framework to examine social media usage and marketing within a sports context. This study used the framework with the burgeoning sport of CrossFit and examined three primary organizational relationship-marketing activities: (a) Information, (b) Interaction, and (c) Promotion. The purpose of this study was to investigate the use of social media by key members of the CrossFit community. The study addressed the following research questions: RQ1. What are the usage categories similarities and differences observed across the social media platforms? RQ2. What are the group usage similarities and differences observed across the social media platforms? and RQ3. What are the group usage similarities and differences observed across the usage categories? A content analysis of 5,565 Twitter, Facebook, and YouTube messages was used to explore these activities. The CrossFit social media users—CrossFit Games, regions, boxes, athletes, and sponsors—used the platforms primarily to provide information about the sport and interact with the community, while promotion was employed less frequently. CrossFit and other niche sports can use social media to provide information and build community within their sports, before attempting to create online communities and promote their products.

Abstract

Since 2017, the Institute of Applied Astronomy of the Russian Academy of Sciences in cooperation with the National Astronomical Observatories of the Chinese Academy of Sciences has been conducting observations of the Chang’E-3 lander carrier wave signal. The paper presents the features of observation scheduling and results of data processing. High-precision phase radar measurements have been obtained with an instrumental error of 1–2 mm. The deviation of residuals in model calculations does not exceed ± 1 cm. The estimates of CE-3 lander position have been obtained with an accuracy of 0.5’’, 7.4 m and 3.2 m in celenocentric cylindrical longitude, Px and Py coordinates, respectively.

Abstract

Adventitious root development is crucial for cutting propagation in hybrid larch. In the present study, semilignified cuttings of Larix kaempferi × L. olgensis clones were used to study the morphological and anatomical changes during the different development stages and compare the changes in contents of endogenous phytohormone in two clones with evidently different rooting capacity (25-5 and 23-12), and the effects of exogenous Indole-3-Butyric Acid (IBA) on phytohormone content of a very low native rooting capacity clone (8-9) during the development of adventitious roots. The results showed that the development of adventitious root in semi-lignified cuttings involves three key stages: root cell dedifferentiation and division (14-18 DAC); meristem formation and development (25-35 DAC); root formation and elongation (50-55 DAC). The endogenous phytohormones play a key role during adventitious root development. For 25-5 and 23-12, the level of endogenous phytohormones, especially the ABA content, has an important effect on rooting capacity. For the effects of IBA on 8-9, except lower ABA content, the temporary peak of IAA on the 1 DAC was important for initiating the rooting process. The ratio of (IAA + GA3 + ZR)/ABA can be used as an indicator of rooting capacity. The anatomical and physiological data described here for semi-lignified cuttings of L. kaempferi × L. olgensis clones improves our knowledge of adventitious roots development. Our study will also benefit future research on examining the molecular mechanisms of the adventitious roots development in hybrid larch.

Abstract

Oat seed with dormancy characteristics, which can germinate after one season or one year, are used to build and maintain vegetation to protect soils from been damaged by desertification in Northern China. The aim of this study was to estimate the effects of endogenous and exogenous GA3 and ABA on oat seed (var. Baiyan 7) germination. The results showed that seeds without peel hull had lower endogenous ABA content and the ratio of ABA/GA3 than seeds with peel hull. The best GA3 treatment duration for milky ripe, wax ripe, full ripe seeds were 60 min or 120 min, 60 min and 30 min, respectively. Seed germination rate, germination potential and germination index increased before they declined with the increasing of GA3 concentrations. The best GA3 concentration treatment was 100 mg/l, while the turning point was 200 mg/l. The dormancy rate of low temperature storage seeds were higher than those of room temperature storage seeds at each storage time, and both decreased with the increase of the storage time. For the seeds which were new or stored for 1-2 months, the germination rates were enhanced significantly by exogenous GA3. For the seeds that had been stored for over three months, GA3 treatment had no effect on germination rate. Germination rate decreased with the increase of ABA concentrations. The most inhibitive effect, which leaded to a seed germination reduction by 37.7% and 4.0%, appeared, when the concentration of ABA was 500 mg/L and 1000 mg/l, respectively. GA3 could abate the effect which ABA inhibited seed germination.

Abstract

Quercus acutissima is a large deciduous tree of hillsides ranging from South Korea to Japan. It occurs in many plant communities, often as a pioneer species in monospecific stands which colonized gaps after gap formation. This study used multilocus allozyme genotypes mapped from two disturbed populations near farm houses in southern Korea to compare our results with previous studies conducted on undisturbed populations of trees in southern Korea. Coancestry measures (fij), RIPLEY’s L-statistics, and WRIGHT’s F-statistics were then calculated to examine the distribution of individuals and spatial genetic structure both within and between populations. RIPLEY’s Lstatistics indicated significant aggregation of individuals at interplant distances. A weak but significant positive fine-scale genetic structure at 10 m distance was detected in the two disturbed populations, which is consistent with the structure found in an inland, disturbed population in southern Korea. Estimates of near-distance fij in the two populations (0.020 and 0.036) were considerably lower than that expected for half-sibs (0.125) under random mating, suggesting secondary seed dispersal and substantial overlap of seed shadows. The levels of genetic diversity within the two disturbed populations of Q. acutissima were found to be comparable to the within-mean for populations of other oak species. Significant deficits of heterozygosity were detected in both populations, probably due to several parent-offspring and sib matings. Finally, a significant but low differentiation between the two disturbed populations of Q. acutissima was found, which is likely to be attributable to long-distance pollen movement by wind, which should enhance homogeneity of allele frequencies between adjacent local oak populations.

Summary

During a nematode biodiversity survey from 2012 to 2014 in Shenzhen, China, ten nematode populations (SZX1301–SZX1310) of Xiphinema were recovered from rhizosphere of different plants, namely Acacia mangium (SZX1306), A. confuse (SZX1309), Blechnum orientale (SZX1301, SZX1302, SZX1307, SZX1308), Litchi chinensis (SZX1304, SZX1310) in Tianxinshan and Gleichenia linearis (SZX1303, SZX1305) in Yangmeikeng environmental monitoring sites. Morphological and molecular profiles of these populations were determined. Three species of Xiphinema, i.e., X. hunaniense , X. brasiliense and X. americanum Cobb, 1913 sensu lato were identified using morphological characters and molecular data of partial 18S and 28S D2–D3 rDNA expansion segments. Four populations (SZX1301–SZX1304) were X. hunaniense, one population (SZX1305) X. brasiliense, and five populations (SZX1306–SZX1310) X. americanum s.l.. Phylogenetic analysis based on sequences of the 28S rDNA D2–D3 expansion segment revealed these three species are all distinct species and supported a close relationship with their corresponding species. This is the first report of X. hunaniense, X. brasiliense and X. americanum s.l. in their hosts except for L. chinensis.

Summary

The paramyosin (Pmy) protein has been presented as a potential vaccine candidate against Schistosoma spp. However, it remains elusive whether it works in controlling cystic echinococcosis (CE), which is caused by the larval stages of Echinococcus granulosus (E. granulosus). This study investigated the characteristics of E. granulosus Pmy (EgPmy) using in silico analysis and evaluated its potential as an epitope vaccine. The secondary structure was predicted by SOPMA software and linear B-cell epitopes were screened by the Kolaskar and Tongaonkar’s method on IEBD while conformational B-cell epitopes were predicted by the Ellipro. Additionally, the epitopes of cytotoxic T lymphocyte (CTL) were analyzed by the NetCTL-1.2 server. The results showed that α-helices, extended strands, random coils and β-turns accounted for 84.82 %, 6.60 %, 5.56 % and 3.01 % in EgPmy’s secondary structure, respectively. A total of 29 linear B-cell epitopes and 6 conformational epitopes were identified together with 25 CTL epitopes. The CTL epitope 709KLEEAEAFA717 showed a high potential to elicit CTL response. These results suggested that EgPmy has a strong immunogenicity, which could serve as a reference for the development of EgPmy-based epitope vaccine against CE.