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We have found experimentally and theoretically that laminated composites comprising one layer of length-magnetized Tb 0.3 Dy 0.7 Fe 1.92 ͑Terfenol-D͒ magnetostrictive alloy sandwiched between two layers of thickness-polarized, electro-parallel-connected 0.7Pb͑Mg 1/3 Nb 2/3 ͒O 3 -0.3PbTiO 3 ͑PMN-PT͒ piezoelectric single crystal have a large converse magnetoelectric effect characterized by a large magnetic induction in response to an applied ac voltage. The reported converse magnetoelectric effect originates from the product of the converse piezoelectric effect in the PMN-PT layers and the converse magnetostrictive effect in the Terfenol-D layer. Large converse magnetoelectric coefficient in excess of 105 mG/ V is obtained in the composites at a low magnetic bias field of 170 Oe. The measured magnetic induction has an excellent linear relationship to the applied ac voltage with amplitude varying from 50 to 160 V. These made the composites to be a promising material for direct realization of core-free magnetic flux control devices.

In order to better utilize the superior transverse piezoelectric properties of [011] poled (1−x)Pb(Mg1∕3Nb2∕3)O3–xPbTiO3 single crystals with the composition near the morphotropic phase boundary, a complete set of elastic, dielectric, and piezoelectric constants of [011] poled 0.71Pb(Mg1∕3Nb2∕3)O3–0.29PbTiO3 single crystal was measured by ultrasonic and resonance methods at room temperature. The electromechanical coupling coefficient k32 and transverse piezoelectric constant d32 can reach 0.94 and −1883pC∕N, respectively. This complete set of material properties will provide convenience for device designs and fundamental theoretical studies.

Using neutron elastic and inelastic scattering and high-energy x-ray diffraction, we present a comparison of 40% Pb͑Mg 1/3 Nb 2/3 ͒O 3 -60% PbTiO 3 ͑PMN-60PT͒ with pure Pb͑Mg 1/3 Nb 2/3 ͒O 3 ͑PMN͒ and PbTiO 3 ͑PT͒. We measure the structural properties of PMN-60PT to be identical to pure PT, however, the lattice dynamics are exactly that previously found in relaxors PMN and Pb͑Zn 1/3 Nb 2/3 ͒O 3 ͑PZN͒. PMN-60PT displays a welldefined macroscopic structural transition from a cubic to tetragonal unit cell at 550 K. The diffuse scattering is shown to be weak indicating that the structural distortion is long-range in PMN-60PT and short-range polar correlations ͑polar nanoregions͒ are not present. Even though polar nanoregions are absent, the soft optic mode is short-lived for wave vectors near the zone center. Therefore PMN-60PT displays the same waterfall effect as prototypical relaxors PMN and PZN. We conclude that it is random fields resulting from the intrinsic chemical disorder which is the reason for the broad transverse optic mode observed in PMN and PMN-60PT near the zone center and not due to the formation of short-ranged polar correlations. Through our comparison of PMN, PMN-60PT, and pure PT, we interpret the dynamic and static properties of the PMN-xPT system in terms of a random field model in which the cubic anisotropy term dominates with increasing doping of PbTiO 3 .

BackgroundAccumulation of cadmium (Cd) in maize (Zea mays L.) poses a significant risk to human health as it is ingested via the food chain. A genome-wide association study (GWAS) was conducted in a population of 269 maize accessions with 43,737 single nucleotide polymorphisms (SNPs) to identify candidate genes and favorable alleles for controlling Cd accumulation in maize.ResultsWhen grown in contaminated soil, accessions varied significantly in leaf Cd concentration at both the seeding and maturing stages with phenotypic variation and the coefficient of variation all above 48%. The co-localized region between SYN27837 (147,034,650 bp) and SYN36598 (168,551,327 bp) on chromosome 2 was associated with leaf Cd under three soil conditions varying in Cd content in 2015 and 2016. The significant SNP (SYN25051) at position 161,275,547 could explained 27.1% of the phenotype variation. Through QTL mapping using the IBMSyn10 double haploid (DH) population, we validated the existence of a major QTL identified by GWAS; qLCd2 could explain the 39.8% average phenotype variation across the experiments. Expression of GRMZM2G175576 encoding a cadmium/zinc-transporting ATPase underlying the QTL was significantly increased in roots, stems and leaves of B73, a low Cd accumulation line in response to Cd stress.ConclusionsOur findings provide new insights into the genetic control of Cd accumulation and could aid rapid development of maize genotypes with low-Cd accumulation by manipulation of the favorable alleles.Electronic supplementary materialThe online version of this article (doi: 10.1186/s12864-017-4395-x) contains supplementary material, which is available to authorized users.

Michelia coriacea, a critically endangered tree, has a restricted and fragmented distribution in Southeast Yunnan Province, China. The genetic diversity, genetic structure and gene flow in the three extant populations of this species were detected by 10 inter-simple sequence repeat (ISSR) markers and 11 simple sequence repeat (SSR) markers. Examination of genetic diversity revealed that the species maintained a relatively high level of genetic diversity at the species level (percentage of polymorphic bands) PPB = 96.36% from ISSRs; PPL (percentage of polymorphic loci) = 95.56% from SSRs, despite several fragmental populations. Low levels of genetic differentiation among the populations of M. coriacea were detected by Nei’s Gst = 0.187 for ISSR and Wright’s Fst = 0.090 for SSR markers, which is further confirmed by Bayesian model-based STRUCTURE and PCoA analysis that could not reveal a clear separation between populations, although YKP was differentiated to other two populations by ISSR markers. Meanwhile, AMOVA analysis also indicated that 22.84% and 13.90% of genetic variation existed among populations for ISSRs and SSRs, respectively. The high level of genetic diversity, low genetic differentiation, and the population, structure imply that the fragmented habitat and the isolated population of M. coriacea may be due to recent over-exploitation. Conservation and management of M. coriacea should concentrate on maintaining the high level of genetic variability through both in and ex-situ conservation actions.

The composition and orientation dependence of the room temperature piezoelectric constant d33 and the dielectric constant tunability was investigated in poled single crystals of (1− x)Pb(Mg1/3Nb2/3)O3–xPbTiO3 (PMN–PT) with x varying from 0.24 to 0.38. The temperature, frequency, orientation and composition dependence of the dielectric constant in the poled crystals shows that domain configurations and phase transitions in the poled crystals strongly depend on both composition and orientation. Poled polydomain crystals near the morphotropic phase boundary, especially for -poled 0.70PMN–0.30PT crystals with a critical composition for the relaxor state, possess a large piezoelectric constant d33 = 2210 pC N−1 and a high dielectric constant tunability of 40.6% (at a dc bias of 1 kV mm−1). The large tunability of εr in PMN–PT crystals is expected to be the most promising candidate for potential applications in continuously adjustable capacitors and dielectric amplifiers.

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