Mophological and Molecular Identification of Potato Cyst Nematode from Sichuan,China

[Objectives]The infection symptoms of cyst nematodes were found in Yuexi, Sichuan. In order to identify the pathogen, the isolated nematodes were identified by morphology and molecular biology. [Methods] The potato roots and soil around the roots were collected, the nematodes in the roots were stained and observed, and the cysts were separated by the simple floating method. The second-stage juveniles(J2 s), females and cysts were found, and they were photographed and morphologically measured. The DNA of cysts and J2 s were extracted and identified by species-specific PCR. The DNA sequences of 18 S gene, 28 S D2-D3 region and ITS region in ribosomal DNA were obtained. Sequences of some cyst nematode species were downloaded from GenBank for sequence alignment, and MrBayes 3.2.3 software was used to construct a Bayesian phylogenetic tree. [Results] The nematodes could invade hosts’ root system. The basal knobs of J2 s was nearly round and inclined backward;the average length of the stylet was shorter than 23 μm;the Granek ratio of cysts was greater than or equal to 3, which is highly consistent with that of Globodera rostochiensis. The DNA templates of three cysts and four J2 s were amplified by species-specific PCR, and a band of about 430 bp was obtained. After further sequencing, the length was 434 bp, which is consistent with G. rostochiensis. The evolutionary analysis of rDNA 18 S and 28 S showed that the cyst nematode population was a Globodera species, and further evolutionary analysis of ITS gene confirmed that the population was G. rostochiensis. [Conclusions] The nematodes are G. rostochiensis, which is a quarantine species of great concern to both domestic and import quarantine. Once introduced and colonized, it is hard to eradicate. It is necessary to establish a monitoring system as soon as possible, strengthen the quarantine, supervision and management, increase investment in G. rostochiensis research and development, and develop detection and control technologies, so as to escort the healthy and sustainable development of China’s potato industry.

Interface engineering constructs oxide composite bulkγ-Fe_(4 )N magnetic alloys with high resistivity:Superior magnetization and manufacturability

O2 Soft magnetic material with high saturation magnetization(Ms)and high resistance(ρ)is vital to improve the power density and conversion efficient of modern electrical magnetic equipment.Yet,increasing Ms is always at the expense of high resistivity,such as soft magnetic alloys substitute for the ferrite.In this work,the superior comprehensive electromagnetic properties,namely the close association of high saturation magnetization and high resistivity,are combined in a new way in a newly Fe-N based magnetic materials.A high resistance oxide interface engineering was constructed between the conducting ferromagnetic phases in the process of spark plasma sintering(SPS)to achieve superior electromagnetic properties.The ZnO compositeγ’-Fe_(4) N bulk has a maximum resistivity of 220μcm and a Ms of up to 156.02 emu/g,while the TiO_(2)compositeγ’-Fe_(4) N bulk has a maximum resistivity of 379μcm and a Ms of 149.7 emu/g.The research findings offer valuable insights for the advancement of the next generation of soft magnetic materials,which hold significant potential for use in high-frequency,high-efficiency,and energy-saving power equipment applications.

Multifunctional flower-like core-shell Fe/Fe_(4)N@SiO_(2)composites for broadband and high-efficiency ultrathin electromagnetic wave absorber

The nano-iron nitride soft magnetic material has excellent magnetic properties and is expected to be a brilliant electromagnetic wave absorber.However,how to fully exploit its wave-absorbing potential re-mains a thought-provoking question.Here,we have synthesized Fe/Fe_(4)N@SiO_(2)nanomagnetic core-shell materials with different Fe/Fe_(4)N ratios by performing nitridation reactions at different temperatures.Then,the flower-like core-shell Fe/Fe_(4)N@SiO_(2)structure was obtained by the etching method.Finally,with the synergy of the excellent magnetic and dielectric losses,an outstanding absorption performance could be achieved with a minimum refection loss(RL min)of−71.31 dB at the matching thickness of 1.4 mm,and the widest effective absorption bandwidth(EAB max)of 6.1 GHz less than−10 dB was realized at 1.16 mm.Moreover,this material also shows a preeminent advance in corrosion resistance to adapt to harsh environments.Hence,this iron nitride flower-like core-shell structure exhibits great potential in microwave absorption in harsh conditions.

Corrosion mechanism of H_2O on Sm_2Fe_(17) and nitrogenation process of corroded Sm_2Fe_(17)

Sm_2 Fe_(17) prepared by reduction-diffusion method needs to be washed with water to remove calcium oxide. Electrochemical corrosion occurs when Sm_2 Fe_(17) powder is in contact with liquid water. Corrosion mechanism of H_2 O on Sm_2 Fe_(17) powder and nitrogenation process of corroded Sm_2 Fe_(17) were studied by analyzing the structure and morphology. It is indicated that the metallic hydroxide forms and deposits on the Sm_2 Fe_(17) powder surfaces during water corrosion. At the same time, oxygen and hydrogen enter the unit cell of Sm2 Fe_(17), causing a slight increase in Curie temperature. In the subsequent nitriding process,the hydroxide is dehydrated and hydrogen is desorbed. The resulting oxide reacts with Sm_2 Fe_(17)N_x to form a-Fe and Sm_2 O_3. Thermodynamic calculations using the HSC Chemistry 6.0 software indicate that the reaction can occur spontaneously. The effect of water corrosion on the magnetic properties of the nitride can be eliminated by hydrogen reduction prior to nitriding.

Shoot rot of Zizania latifolia and the first record of its pathogen Pantoea ananatis in China

The aquatic grass Zizania latifolia grows symbiotically with the fungus Ustilago esculenta producing swollen structures called Jiaobai,widely cultivated in China.A new disease of Z.latifolia was found in Zhejiang Province,China.Initial lesions appeared on the leaf sheaths or sometimes on the leaves near the leaf sheaths.The lesions extended along the axis of the leaf shoots and formed long brown to dark brown streaks from the leaf sheath to the leaf,causing sheath rot and death of entire leaves on young plants.The pathogen was isolated and identified as the bacterium Pantoea ananatis,based on 16 S ribosomal RNA(r RNA)gene sequencing,multilocus sequence analysis(atp D(β-subunit of ATP synthase F1),gyr B(DNA gyrase subunit B),inf B(translation initiation factor 2),and rpo B(β-subunit of RNA polymerase)genes),and pathogenicity tests.Ultrastructural observations using scanning electron microscopy revealed that the bacterial cells colonized the vascular tissues in leaf sheaths,forming biofilms on the inner surface of vessel walls,and extended between vessel elements via the perforated plates.To achieve efficient detection and diagnosis of P.ananatis,species-specific primer pairs were designed and validated by testing closely related and unrelated species and diseased tissues of Z.latifolia.This is the first report of bacterial sheath rot disease of Z.latifolia caused by P.ananatis in China.

Enhanced maximum energy product of(SmY)FeN caused by abundant yttrium doping

Replacement of samarium(Sm) with abundant yttrium(Y) can help solve the potential shortage of Sm in the preparation of promising Sm2 Fe17 Nx magnets.In this article,phase composition,microstructure and magnetic properties of(Sm1-yYy)2 Fe17Nx(y=0,0.2,0.4,0.6,0.8,1.0) were investigated.Maximum energy product(BH)max is improved when less than 40 at% Y is doped in(Sm1-yYy)2 Fe17Nx powder.In particular,when 20 at% Y replaces Sm,(BH)max of(Sm1-yYy)2 Fe17Nx powder increases by 15.1% from 131.7 to151.6 kJ/m3.The effect of annealing temperature on the structural properties of high Y doping(Sm0.6Y0.4)2 Fe17 and the magnetic properties of the corresponding nitrides were subsequently investigated.In the RE2 Fe17 phase grain combination process,the interlaced structure of the rhombohedral Th2 Zn17-type structural phase and the hexagonal Th2 Ni17-type structural phase is formed.Due to shortrange exchange coupling,the nitride with the highest content of two interlaced RE2 Fe17 phases has the highest magnetic properties:Br=1.23 T,HcJ=443.9 kA/m and(BH)max=197.6 kJ/m3.