Molecular mechanisms of Bacillus thuringiensis resistance in the sugarcane borer

The sugarcane borer, Diatraea saccharalis, is a major target pest of transgenic corn expressing Bacillus thuringiensis (Bt) proteins in many areas of the U.S. mid-southern region. A Cry1Ab-resistant (Cry1Ab-RR) strain of D. saccharalis has been developed from a single two-parent family-line. To examine the molecular mechanisms of the Cry1Ab resistance in this insect strain, cDNAs of five types of potential candidate genes related to Bt resistance were sequenced using reverse transcriptase polymerase chain reaction (RT-PCR) and 5’ rapid amplification of cDNA end (5’ RACE). The Bt resistance candidate genes examined included three trypsins (DsTRYs), three chymotrypsins (DsCHYs), three aminopeptidases N (DsAPNs), one cadherin (DsCAD1), and three alkaline phosphatases (DsALPs). cDNA sequence of each gene and its expression levels were compared between a Cry1Ab-susceptible strain (Cry1Ab-SS) and the Cry1Ab-RR at different larval growth stages. The cDNA sequences of these genes were identical between Cry1Ab-SS and -RR strains. Gene expression levels of the trypsins, chymotrypsins, and alkaline phosphatases were similar between the two strains. There were also no significant differences in total enzymatic activity of trypsins, chymotrypsins, and alkaline phosphatases between Cry1Ab-SS and -RR. However, the gene expression levels of the three DsAPNs and the DsCAD1 in Cry1Ab-RR were significantly lower than those of the Cry1Ab-SS. RNA interference (RNAi) was employed to knock-down the three DsAPNs and the DsCAD1 in the Cry1Ab-SS strain by oral droplet feeding to neonates. Down-regulations of the expressions of these four genes by RNAi were correlated with the decrease in susceptibility to Cry1Ab toxin. Silencing each of the three DsAPNs in D. saccharalis in vivo by RNAi resulted in a decrease of total APN activity. In addition, the total specific APN activities from Cry1Ab-RR larvae were significantly lower than those of the Cry1Ab-SS strain. These results suggest that reduction in expression of the three DsAPNs and DsCAD1 is functionally associated with the Cry1Ab resistance in D. saccharalis

Robust MMSE Precoding Strategy for Multiuser MIMO Relay Systems with Switched Relaying and Side Information

In this work, we propose a minimum mean squared error (MMSE) robust base station (BS) precoding strategy based on switched relaying (SR) processing and limited transmission of side information for interference suppression in the downlink of multiuser multiple-input multiple-output (MIMO) relay systems. The BS and the MIMO relay station (RS) are both equipped with a codebook of interleaving matrices. For a given channel state information (CSI) the selection function at the BS chooses the optimum interleaving matrix from the codebook based on two optimization criteria to design the robust precoder. Prior to the payload transmission the BS sends the index corresponding to the selected interleaving matrix to the RS, where the best interleaving matrix is selected to build the optimum relay processing matrix. The entries of the codebook are randomly generated unitary matrices. Simulation results show that the performance of the proposed techniques is significantly better than prior art in the case of imperfect CSI.

An inequality for the minimum affine curvature of a plane curve

As an application of the affine curve shortening flow, we will prove an inequality for minimum affine curvature of a smooth simple closed curve in the Euclidean plane

An inequality for the minimum affine curvature of a plane curve

As an application of the affine curve shortening flow, we will prove an inequality for minimum affine curvature of a smooth simple closed curve in the Euclidean plane

Effect of the Steam Activation Thermal Treatment on the Microstructure of Continuous TiO 2

The continuous TiO2 fibers have been synthesized by the sol-gel method using the polymer of titanate as the precursor solution. The as-synthesized samples were characterized using XRD, SEM, and HR-TEM analysis methods. The grain growth kinetics was primarily investigated. The results demonstrated that the average diameters of the fibers were in the range of 20–30 μm, the crystal phase of the synthesized TiO2 fiber was transformed from anasate to rutile, and the crystal size became bigger with increasing the temperature using steam activation. The growth exponent and the constant of growth rate of the rutile crystal phase at 500°C were 4 and 2.55×106 nm/h, respectively. The activation energies of crystalline growth during 500°C~700°C and 700°C~800°C were 38.62 kJ/mol and 143.91 kJ/mol, respectively

Experimental study on mechanical performance of partially precast steel reinforced concrete beams

[EN] In order to exploit the potentials in mechanical and constructional performance of steel reinforced concrete structures and prefabricated structures, three innovative kinds of partially precast steel reinforced concrete beams, which are abbreviated here as PPSRC, HPSRC and PPCSRC beam, are presented in this paper. The PPSRC beam is composed of two parts, which are the precast outer shell with high-performance concrete and the cast-in-place inner part with common-strength concrete. Meanwhile, on the basis of PPSRC beam, the PPCSRC beam applies castellated steel shape and the HPSRC beam keeps the beam core hollow. With the aim to investigate the mechanical behavior, failure mode and bearing capacity of the PPSRC, PPCSRC and HPSRC beams, a static loading experiment with twenty four specimens was carried out. The effects of aspect ratio, construction method, section shape, concrete flange and strength of concrete were critically examined. Test results indicate that the HPSRC, PPCSRC and PPSRC beams both exhibit similar mechanical performance and bonding performance. The flexural capacity and shear capacity are seldom affected by the construction method and section shape, and increase with the increasing of the cast-in-place concrete strength. The shear strength of the specimens is significantly affected by the concrete flange and aspect ratio.Yang, Y.; Xue, Y.; Yu, Y.; Liu, R. (2018). Experimental study on mechanical performance of partially precast steel reinforced concrete beams. En Proceedings of the 12th International Conference on Advances in Steel-Concrete Composite Structures. ASCCS 2018. Editorial Universitat Politècnica de València. 107-114. https://doi.org/10.4995/ASCCS2018.2018.6942OCS10711