411 research outputs found
Carbon sequestration patterns in the Yellow River Basin of China are governed by the vegetation structural dynamics
No full texthttp://dx.doi.org/10.13039/501100001809 National Natural Science Foundation of Chinahttp://dx.doi.org/10.13039/501100006606 Tianjin Municipal Natural Science Foundationhttp://dx.doi.org/10.13039/501100007129 Shandong Province Natural Science Foundatio
Performance Evaluation of Distributed-Antenna Communications Systems Using Beam-Hopping
No full textDigital beamforming (DBF) techniques are capable of improving the performance of communications systems significantly. However, if the transmitted signals are conflicted with strong interference, especially, in the direction of the transmitted beams , these directional jamming signals will severely degrade the system performance. In order to efficiently mitigate the interference of the directional jammers, in this contribution a beam-hopping (BH) communications scheme is proposed. In the proposed BH communications scheme, only one pair of the beams is used for transmission and it hops from one to the next according to an assigned BH pattern. In this contribution a range of expressions in terms of the average SINR performance have been derived, when both the uplink and downlink are considered. The average SINR performance of the proposed BH scheme and that of the conventional single-beam (SB) as well as multiple-beam (MB) assisted beam-processing schemes have been investigated. Our analysis and results show that the proposed BH scheme is capable of efficiently combating the directional jamming, with the aid of utilizing the directional gain of the beams generated by both the transmitter and the receiver. Furthermore, the BH scheme is capable of reducing the intercept probability of the communications. Therefore, the proposed BH scheme is suitable for communications, when several distributed antenna arrays are available around a mobile
Virtual Drug Design
No full textThis eBook is a collection of articles from a Frontiers Research Topic. Frontiers Research Topics are very popular trademarks of the Frontiers Journals Series: they are collections of at least ten articles, all centered on a particular subject. With their unique mix of varied contributions from Original Research to Review Articles, Frontiers Research Topics unify the most influential researchers, the latest key findings and historical advances in a hot research area! Find out more on how to host your own Frontiers Research Topic or contribute to one as an author by contacting the Frontiers Editorial Office: frontiersin.org/about/contac
Virtual Drug Design
No full textThis eBook is a collection of articles from a Frontiers Research Topic. Frontiers Research Topics are very popular trademarks of the Frontiers Journals Series: they are collections of at least ten articles, all centered on a particular subject. With their unique mix of varied contributions from Original Research to Review Articles, Frontiers Research Topics unify the most influential researchers, the latest key findings and historical advances in a hot research area! Find out more on how to host your own Frontiers Research Topic or contribute to one as an author by contacting the Frontiers Editorial Office: frontiersin.org/about/contac
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Regulation of Interactions Between Sap-feeding Insects and Their Obligate Endosymbionts
No full textMany insects cultivate obligate endosymbionts for nutrition. Genomic analyses, coupled with physiological evidence demonstrate that insects and their obligate endosymbionts are intimately integrated in biosynthesis of essential nutrients, including essential amino acids. However, the mechanisms that underlie regulation of host/endosymbiont integrations remain elusive. Using sap-feeding insects, I investigated the role of amino acid transporters and microRNAs in host/endosymbiont integrations. In the first data chapter in aphids, I determined the localization of aphid glutamine transporter ApGLNT1 and another amino acid transporter ACYPI008971. ApGLNT1 specifically localizes at the plasma membrane of bacteriocytes, the aphid specialized cells harboring the endosymbiont Buchnera aphidicola. ACYPI008971 localizes at the symbiosomal membrane, a host derived membrane that surrounds each Buchnera cell. In the second data chapter, I determined the role of miRNAs in regulation of host/endosymbiont integration. I found fourteen conserved aphid microRNAs differentially expressed in the symbiotic tissue containing bacteriocytes versus a non- symbiont tissue gut. Those microRNAs potentially target genes involved in amino acid biosynthesis and signal transduction mechanisms. In the third data chapter, I functionally validated one of the predicted miRNA::mRNA interactions using a dual luciferase assay in NIH/3T3 cell culture. In the fourth data chapter, I expanded my investigation of miRNA functions from aphids to sap-feeding insects. I found the majority of microRNAs detected in the bacteriocyte cells of two species of aphids, a psyllid and a mealybug could potentially target their endosymbiont genomes. The distribution of Cluster of Orthologous Groups (COG) of the miRNA targets in the nutritional endosymbiont reflects the COG distribution of the symbiont genomes, indicating that these cross- kingdom miRNA::mRNA interactions are governed by random processes. Together, these studies contribute to elucidation of the mechanisms that underlie the regulation of host/endosymbiont integrations and shed light on the coevolution of hosts and their associated endosymbionts.</p
One step preparation of pure tau-MnAl phase with high magnetization using strip casting method
No full textFerromagnetic phase of Mn-Al exhibits great potential in the rare-earth free permanent magnetic materials due to its high magnetocrystalline anisotropy, high magnetization, high Curie temperature and low cost. In this work, the strip casting technique was applied to prepare MnAl magnetic phase. X-ray diffraction and energy dispersive X-ray analyses indicate that the as-prepared Mn54Al46 strip sample consists of pure tau-MnAl magnetic phase. It is found that the composition of Mn54Al46 is suitable to prepare tau-MnAl phase during the strip casting process. The Mn54Al46 strip sample synthesized through the strip casting exhibits a fairly high magnetization of 114 emu/g under a field of 5 T, while the coercivity of iHc = 2.8 kOe, magnetization of M-5T = 63.9 emu/g at room temperature can be obtained for Mn54Al46 powder sample. This preparation method can produce a large amount of tau-phase MnAl alloy and promote mass industrialized production. (C) 2017 Author(s)
Rapid Screening of Myzus persicae (Green Peach Aphid) RNAi Targets Using Tobacco Rattle Virus
No full textPlant-mediated RNA interference (RNAi) can be used to reduce the growth of insect pests, including Myzus persicae (green peach aphid), a prolific pest of numerous dicot crop species. In one approach, viruses that have been engineered to carry an aphid gene fragment are used to infect plants and thereby silence target gene expression in the aphids feeding on these plants, a process called virus-induced gene silencing, or VIGS. Tobacco Rattle Virus (TRV) in the model plant, Nicotiana benthamiana, was the first of many VIGS systems that have been developed for different plant species. In this chapter, we describe a method for silencing M. persicae gene expression using an established TRV-VIGS vector that infects and spreads in N. benthamiana. The two parts of the TRV genome, RNA1 and RNA2, have been cloned into Agrobacterium T-DNA vectors for initiation of plant infections. The RNA2 construct is modified with a Gateway-compatible cloning site to allow insertion of aphid genes. When feeding on TRV-infected N. benthamiana plants, aphids ingest dsRNAs that silence specific target genes. TRV-VIGS of aphid genes allows rapid identification of essential gene targets that can be used for the control of M. persicae by this and other RNAi methods
Serine proteinase inhibitors from Nicotiana benthamiana, a nonpreferred host plant, inhibit the growth of Myzus persicae (green peach aphid)
No full textBACKGROUND: The green peach aphid (Myzus persicae) is a severe agricultural crop pest that has developed resistance to most current control methods, requiring the urgent development of novel strategies. Plant proteinase inhibitors (PINs) are small proteins that protect plants against pathogens and/or herbivores, likely by preventing efficient protein digestion. RESULTS: We identified 67 protease genes in the transcriptomes of three M. persicae lineages (USDA-Red, G002 and G006). Comparison of gene expression levels in aphid guts and whole aphids showed that several proteases, including a highly expressed serine protease, are significantly overexpressed in the guts. Furthermore, we identified three genes encoding serine protease inhibitors (SerPIN-II1, 2 and 3) in Nicotiana benthamiana, which is a nonpreferred host for M. persicae. Using virus-induced gene silencing (VIGS) with a tobacco rattle virus (TRV) vector and overexpression with a turnip mosaic virus (TuMV) vector, we demonstrated that N. benthamiana SerPIN-II1 and SerPIN-II2 cause reduced survival and growth, but do not affect aphid protein content. Likewise, SerPIN-II3 overexpression reduced survival and growth, and serpin-II3 knockout mutations, which we generated using CRISPR/Cas9, increased survival and growth. Protein content was significantly increased in aphids fed on SerPIN-II3 overexpressing plants, yet it was decreased in aphids fed on serpin-II3 mutants. CONCLUSION: Our results show that three PIN-IIs from N. benthamiana, a nonpreferred host plant, effectively inhibit M. persicae survival and growth, thereby representing a new resource for the development of aphid-resistant crop plants. © 2024 Society of Chemical Industry
Titanium silicalite-1 grafted with carbon nitride as carrier for cerium oxide-catalyzed ozonation of carboxylic acid in water
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