Low genetic diversity of Phytophthora infestans population in potato in north China

Late blight, caused by Phytophthora infestans is the most important disease of potato (Solanum tuberosum). This study reveals the genetic diversity of P. infestans population in north China. A total of 134 strains of P. infestans were isolated from different agricultural fields in Hebei, Liaoning, Jinlin and Heilongjiang Provinces in north China. The genetic variation among these strains were analyzed using 15 ‘simple-sequence repeat’ (SSR) markers. The results show that forty different SSR genotypes and an average of 3.8 (range 2 to 9) alleles per locus were found. Low genetic diversity (Shannon’s diversity index = 0.26) was found among these 134 strains from four provinces, revealing the presence of clonal populations of the pathogen in this region. The average heterozygosity was 0.162, indicating the low level of genetic variations of P. infestans populations. There was no correlation between population genetic diversity of P. infestans and geographical origin. These results provided a foundation for making integrated control measures in the future.Key words: Phytophthora infestans, population genetics, simple-sequence repeat (SSR), potato late blight

Homogenized finite element analysis on effective elastoplastic mechanical behaviors of composite with imperfect interfaces

A three-dimensional (3D) representative volume element (RVE) model was developed for analyzing effective mechanical behavior of fiber-reinforced ceramic matrix composites with imperfect interfaces. In the model, the fiber is assumed to be perfectly elastic until its tensile strength, and the ceramic material is modeled by an elasto-plastic Drucker-Prager constitutive law. The RVE model is then used to study the elastic properties and the tensile strength of composites with imperfect interfaces and validated through experiments. The imperfect interfaces between the fiber and the matrix are taken into account by introducing some cohesive contact surfaces. The influences of the interface on the elastic constants and the tensile strengths are examined through these interface models

Electromagnetic wave absorbing properties and hyperfine interactions of Fe-Cu-Nb-Si-B nanocomposites

The Fe–Cu–Nb–Si–B alloy nanocomposite containing two ferromagnetic phases (amorphous phase and nanophase phase) is obtained by properly annealing the as-prepared alloys. High resolution transmission electron microscopy (HRTEM) images show the coexistence of these two phases. It is found that Fe–Si nanograins are surrounded by the retained amorphous ferromagnetic phase. Mossbauer spectroscopy measurements show that the nanophase is the D03-type Fe– Si phase, which is employed to find the atomic fractions of resonant 57Fe atoms in these two phases. The microwave permittivity and permeability spectra of Fe–Cu–Nb–Si–B nanocomposite are measured in the frequency range of 0.5 GHz– 10 GHz. Large relative microwave permeability values are obtained. The results show that the absorber containing the nanocomposite flakes with a volume fraction of 28.59% exhibits good microwave absorption properties. The reflection loss of the absorber is less than −10 dB in a frequency band of 1.93 GHz–3.20 GHz

DEFEM Method and Its Application in Pebble Flows

Based on the concept of embedded discrete elements (EDEs), the discrete element-embedded finite element model (DEFEM) is extended in this work. The new method can be used to calculate the motion and stress variation of particles. This work discusses its application in granular flow simulation for particle motions with small deformations. The updated Lagrangian finite element method is used to obtain the coupling solution of the internal stress and the overall motion of particles in the DEFEM. The computation of deformation displacement is based on the concepts of displacement decomposition (translational and rotational motions and deformation displacement). The deformation displacement is the difference between particles and template particles [rigid body, using the discrete element method (DEM) to calculate translational and rotational displacements]. It is used to calculate the dynamic stress distribution of particles and the internal force of the node. Therefore, it has a wide scope of application (for example, it can be extended to non-spherical particles). The software validation proves the accuracy of this method. The application of the DEFEM in the accumulation process of particles is given. The motion characteristics and deformation of particles are discussed, and the stress distribution and force chain structure in particle accumulation are obtained

Comparison of clinical outcomes of Ibutilide-guided cardioversion and direct current synchronized cardioversion after radiofrequency ablation of persistent atrial fibrillation

BackgroupIbutilide has already been used for cardioversion of persistent atrial fibrillation (PsAF) after radiofrequency catheter ablation (RFCA). The purpose of this study was to determine the effect of Ibutilide-guided cardioversion on clinical outcomes after individualized ablation of PsAF.MethodsFrom October 2020 to September 2021, consecutive patients with PsAF accepted for RFCA were prospectively enrolled. After individualized ablation including pulmonary vein isolation plus left atrial roof line ablation and personalized linear ablation based on left atrial low-voltage zones, patients were divided into the spontaneous conversion (SCV) group, direct current synchronized cardioversion (DCC) group and Ibutilide group according to different cardioversion types during ablation. The rates of freedom from atrial tachyarrhythmia (ATT) among the three groups were evaluated after follow-up.ResultsIn this study, 110 patients were enrolled, including 12 patients with SCV, 50 patients receiving DCC and 48 patients receiving Ibutilide cardioversion after individualized ablation. Among the three groups, the SCV group had shorter AF duration {12 months [interquartile range (IQR) 12–16], P = 0.042} and smaller left atrial diameter (LAD) [35 mm (IQR: 33–42), P = 0.023]. A 12-month freedom from ATT rate was 83.3% in SCV group, 69.4% in DCC group, and 79.2% in Ibutilide group, respectively (Log-rank, P = 0.745). During the follow-up [17 months (IQR: 15–19)], the rate of freedom from ATT of SCV group (83.3%), and Ibutilide group (72.9%) were both higher than that of DCC group (53.1%, P = 0.042). Moreover, Kaplan–Meier analysis showed a significantly higher sinus rhythm (SR) maintenance in Ibutilide group than in DCC group (Log-rank, P = 0.041). After adjusting for risk factors of AF recurrence, the hazard ratio for AF recurrence of the DCC group with reference to the Ibutilide group was 4.10 [95% confidence interval (CI) (1.87–8.98), P < 0.001]. Furthermore, subgroup analysis showed that freedom from ATT rate in effective Ibutilide subgroup was significantly higher than noneffective Ibutilide subgroup (Log-rank, P < 0.001).ConclusionFor the treatment of the patients with PsAF, Ibutilide-guided cardioversion after individualized RFCA may be benefit for maintenance of SR compared to conventional DCC, especially for the patients who are effective for administration of Ibutilide

XTH31, Encoding an in Vitro XEH/XET-Active Enzyme, Regulates Aluminum Sensitivity by Modulating in Vivo XET Action, Cell Wall Xyloglucan Content, and Aluminum Binding Capacity in Arabidopsis

Xyloglucan endohydrolase (XEH) and xyloglucan endotransglucosylase (XET) activities, encoded by xyloglucan endotransglucosylase-hydrolase (XTH) genes, are involved in cell wall extension by cutting or cutting and rejoining xyloglucan chains, respectively. However, the physiological significance of this biochemical activity remains incompletely understood. Here, we find that an XTH31 T-DNA insertion mutant, xth31, is more Al resistant than the wild type. XTH31 is bound to the plasma membrane and the encoding gene is expressed in the root elongation zone and in nascent leaves, suggesting a role in cell expansion. XTH31 transcript accumulation is strongly downregulated by Al treatment. XTH31 expression in yeast yields a protein with an in vitro XEH:XET activity ratio of >5000:1. xth31 accumulates significantly less Al in the root apex and cell wall, shows remarkably lower in vivo XET action and extractable XET activity, has a lower xyloglucan content, and exhibits slower elongation. An exogenous supply of xyloglucan significantly ameliorates Al toxicity by reducing Al accumulation in the roots, owing to the formation of an Al-xyloglucan complex in the medium, as verified by an obvious change in chemical shift of (27)Al-NMR. Taken together, the data indicate that XTH31 affects Al sensitivity by modulating cell wall xyloglucan content and Al binding capacity