Fabrication and Characterization of In Situ Synthesized SiC/Al Composites by Combustion Synthesis and Hot Press Consolidation Method

The in situ SiC/Al composites were fabricated in Al-Si-C systems with different Si/C mass ratios and holding time by the method of combustion synthesis and hot press consolidation. The influences of Si/C mass ratio and holding time on the phase constitution, microstructure, and hardness of the composites were investigated. The results indicate that the increase of Si/C mass ratio leads to more uniform size distribution of the SiC particles in the Al matrix. Moreover, by improving the Si/C mass ratio from 4 : 1 to 5 : 1, the maximum size of SiC particle was reduced from 4.1 μm to 2.0 μm. Meanwhile, the percentage of submicroparticles was increased from 22% to 63%, and the average hardness value of the composites was increased by 13%. In addition, when the holding time is set to be fifteen minutes, the Al4C3 phase did not exist in the composites because of its total reactions with Si atoms to form SiC particles, and the average hardness value was 73.8 HB

Molecular evolution of Wcor15 gene enhanced our understanding of the origin of A, B and D genomes in Triticum aestivum

Publisher's Version/PDFThe allohexaploid bread wheat originally derived from three closely related species with A, B and D genome. Although numerous studies were performed to elucidate its origin and phylogeny, no consensus conclusion has reached. In this study, we cloned and sequenced the genes Wcor15-2A, Wcor15-2B and Wcor15-2D in 23 diploid, 10 tetraploid and 106 hexaploid wheat varieties and analyzed their molecular evolution to reveal the origin of the A, B and D genome in Triticum aestivum. Comparative analyses of sequences in diploid, tetraploid and hexaploid wheats suggest that T. urartu, Ae. speltoides and Ae. tauschii subsp. strangulata are most likely the donors of the Wcor15-2A, Wcor15-2B and Wcor15-2D locus in common wheat, respectively. The Wcor15 genes from subgenomes A and D were very conservative without insertion and deletion of bases during evolution of diploid, tetraploid and hexaploid. Non-coding region of Wcor15-2B gene from B genome might mutate during the first polyploidization from Ae. speltoides to tetraploid wheat, however, no change has occurred for this gene during the second allopolyploidization from tetraploid to hexaploid. Comparison of the Wcor15 gene shed light on understanding of the origin of the A, B and D genome of common wheat

A look at the other 90 per cent: Investigating British Sign Language vocabulary knowledge in deaf children from different language learning backgrounds

In this study we present new data on deaf children's receptive and expressive vocabulary knowledge in British Sign Language (BSL) from a sample consisting of children with deaf parents, children with hearing parents, and children with additional needs. Their performance on three BSL vocabulary tasks was compared with (previously reported findings from) a sample of deaf fluent signers. We use these data to assess the effects of some key demographic/ child variables on deaf signing children's vocabulary and discuss findings in the relation to the meaning of 'normative' data and samples for this heterogeneous population. Findings show no effect of the presence of additional disabilities on participants' scores for any of the three tasks. As expected, chronological age is the most significant factor in performance on all vocabulary tasks while the number of deaf relatives only becomes statistically significant for the form recall task. This study contributes to the field of sign language assessment by seeking to identify key variables in heterogeneity and how these variables affect signed vocabulary acquisition with the long-term objective of informing intervention

The listening talker: A review of human and algorithmic context-induced modifications of speech

International audienceSpeech output technology is finding widespread application, including in scenarios where intelligibility might be compromised - at least for some listeners - by adverse conditions. Unlike most current algorithms, talkers continually adapt their speech patterns as a response to the immediate context of spoken communication, where the type of interlocutor and the environment are the dominant situational factors influencing speech production. Observations of talker behaviour can motivate the design of more robust speech output algorithms. Starting with a listener-oriented categorisation of possible goals for speech modification, this review article summarises the extensive set of behavioural findings related to human speech modification, identifies which factors appear to be beneficial, and goes on to examine previous computational attempts to improve intelligibility in noise. The review concludes by tabulating 46 speech modifications, many of which have yet to be perceptually or algorithmically evaluated. Consequently, the review provides a roadmap for future work in improving the robustness of speech output

Robust estimation of bacterial cell count from optical density

Optical density (OD) is widely used to estimate the density of cells in liquid culture, but cannot be compared between instruments without a standardized calibration protocol and is challenging to relate to actual cell count. We address this with an interlaboratory study comparing three simple, low-cost, and highly accessible OD calibration protocols across 244 laboratories, applied to eight strains of constitutive GFP-expressing E. coli. Based on our results, we recommend calibrating OD to estimated cell count using serial dilution of silica microspheres, which produces highly precise calibration (95.5% of residuals <1.2-fold), is easily assessed for quality control, also assesses instrument effective linear range, and can be combined with fluorescence calibration to obtain units of Molecules of Equivalent Fluorescein (MEFL) per cell, allowing direct comparison and data fusion with flow cytometry measurements: in our study, fluorescence per cell measurements showed only a 1.07-fold mean difference between plate reader and flow cytometry data

Chitosan Reduces Damages of Strawberry Seedlings under High-Temperature and High-Light Stress

High-temperature and high-light are the main adversity stresses faced by strawberry seedlings and open-field cultivation in summer. Chitosan (CTS) is widely used in agriculture as a soil amendment, plant growth regulator, and promoter of cold resistance. However, the effects of CTS on strawberry seedlings under the combined stress of high-temperature and high-light are unclear. This study aimed to determine the effect of CTS on strawberry seedlings under the combined stress of high-temperature and high-light. In this study, Xuelixiang strawberry was used as the experimental plant material. The leaves were sprayed with 100 mg/Kg CTS or deionized aqueous solution and placed under high-temperature and high-light (38 °C, 1800 μ mol·m−2·s−1, respectively) for 8 h. In addition, a suitable temperature and light (23 °C, 400 μ mol·m−2·s−1, respectively) was sprayed with deionized water as a control. The results showed that compared with non-CTS treatment, the chlorophyll (Chl) content in strawberry plants increased by 16.9% after CTS treatment; the net CO2 exchange (Pn) increased by 74.9%; and the maximum photochemical efficiency increased by 20.1%. In addition, CTS treatment increased the content of antioxidants; increased osmotic adjustment substances; improved the activity of reduced glutathione with reduced ascorbic acid (AsA-GSH) circulating antioxidant enzymes; removed reactive oxygen species in plants in time; and reduced the damage of reactive oxygen species to photosynthetic organs and cell membranes, thereby reducing high-temperature and high-light injury to strawberry seedlings. This study shows that CTS can improve the negative effects of high-temperature and high-light stress on strawberry seedlings

Total omnidirectional reflection by sub-wavelength gradient metallic gratings

In this letter, we find that nearly total omnidirectional reflection could be achieved in a metallic grating structure with gradient index materials, regardless of the polarization of the incident wave. By bending the straight structure into a metallic grating ring, we design a metacage that can well shield the electromagnetic wave. All the phenomena are well demonstrated from theoretical analysis and numerical simulations