为了明确0.1％噁霉灵颗粒剂对西瓜枯萎病的防治效果,以70％噁霉灵可溶粉剂525 g/hm2(有效剂量)为药剂对照,以清水为空白对照,0.1％噁霉灵颗粒剂有效剂量分别设450、525和600 g/hm2,2020～2021年连续2 a开展了0.1％噁霉灵颗粒剂防治西瓜枯萎病的田间药效试验.结果表明:0.1％噁霉灵颗粒剂对西瓜枯萎病具有较好的防治效果,且防效稳定,但不同有效剂量处理的防效差异较大,其中,有效剂量600g/hm2处理的防效显著高于对照药剂和其他剂量处理,有效剂量525g/hm2处理的防效与对照药剂相当,而有效剂量450g/hm2处理的防效显著低于对照药剂.0.1％噁霉灵颗粒剂对西瓜和其他有益生物安全,是一种防治西瓜枯萎病的理想药剂.生产上建议使用0.1％噁霉灵颗粒剂525～600 g/hm2防治西瓜枯萎病.

以生物熏蒸、微生物菌剂和化学熏蒸(棉隆)为处理,对3年连作西瓜生长发育和枯萎病的防治效果进行研究.结果表明:(1)试验条件下,各处理对西瓜出苗率无显著影响,且未出现药害现象;(2)生物熏蒸配施微生物菌剂或棉隆对西瓜生长发育均具有一定的促进作用,增加了株高(蔓长),提高了叶绿素含量;(3)生物熏蒸配施微生物菌剂或化学药剂棉隆两个处理对西瓜枯萎病均有良好的防效,且持效期较长;(4)生物熏蒸配施微生物菌剂处理显著提高了西瓜的品质和平均单果重.结论:生物熏蒸配施微生物菌剂不仅能有效防治西瓜枯萎病,还可以促进西瓜的生长发育,提高西瓜单果重,同时显著改善西瓜品质.

土壤微生物区系变化引起的土传病害一直是制约西瓜产业健康发展的重要因素,为揭示土壤真菌群落对生物熏蒸及配施微生物菌剂的响应机制,本研究在连续种植两年的西瓜田设置生物熏蒸(R)、生物熏蒸配施微生物菌剂(RB)和空白对照(CK)处理,于西瓜初花期采集土样,采用Illumina HiSeq高通量测序技术,分析生物熏蒸及配施微生物菌剂对连作西瓜土壤真菌群落组成和多样性的影响及其与土壤环境因子间的相关性.结果表明:与CK相比,R和RB处理均提高了土壤碱解氮、有效磷、速效钾、全氮及有机质含量,降低了土壤pH;Alpha多样性指数显示,R和RB处理显著降低了土壤真菌群落丰富度和多样性,表现为R<RB<CK.3个处理的西瓜连作土壤样本共获得794个OTU,其中含有一些未知真菌;在已知的真菌群落中,子囊菌门、担子菌门和被孢霉门为3个主要菌门,其相对丰度占总丰度的95.14％～96.17％;R处理增加了土壤中子囊菌门和担子菌门的相对丰度,RB处理提高了子囊菌门的相对丰度,显著降低了担子菌门的相对丰度;R和RB处理均显著提高了土壤中毛壳菌科和小囊菌科相对丰度,此外,RB处理显著增加了从赤壳科真菌相对丰度,并降低了柔膜菌科真菌相对丰度.聚类分析表明,RB处理与CK的真菌群落结构相似.RDA分析可知,有机质、全氮、速效钾和pH是驱动土壤真菌群落结构变化的关键因子.综上所述,生物熏蒸配施微生物菌剂不仅能够提高土壤质量,相比于单独生物熏蒸,还可提高土壤真菌群落丰度和多样性,调节西瓜连作土壤真菌群落结构向有益方向发展.

种子处理在作物病虫害防治领域具有广阔的应用前景,尤其在防治蚜虫方面发挥了重要作用.在介绍蚜虫为害与防治的基础上,系统梳理了种子处理在国内外的研究进展,以及种子处理对蚜虫防治的现状.提出新烟碱类农药作为种子处理剂在防治蚜虫方面有巨大潜力,建议进一步开展种子处理防治西瓜、蔬菜等作物蚜虫的系统研究与应用.

为确定噻虫胺拌种对瓜蚜的防治效果,以西瓜蚜虫为防治对象,开展了室内、盆栽及田间条件下的药剂拌种试验.结果表明:在室内条件下,10％噻虫胺种子处理悬浮剂各处理对西瓜发芽率无显著影响,发芽势和发芽指数随着噻虫胺用量的增加呈现先升高后降低的趋势;在盆栽条件下,西瓜出苗15、30、45d后,接虫12 h和24 h时,西瓜成蚜的死亡率均随着噻虫胺用量的增加而升高;在田间条件下,在供试剂量范围内,噻虫胺拌种对西瓜出苗安全,对西瓜蚜虫的防效随用量的增加而升高.

Biochar has the potential to remediate heavy metals in agricultural soil and mitigate nitrous oxide (N2O) emissions; however, the effects of biochar on heavy metal remediation, the soil microbial community and N2O emissions are not completely understood. In this study, we conducted a pot experiment in which Glycine max L. (soybean) was cultivated in two cadmium (Cd)-contaminated soils (low, 3.14 mg kg-1; high, 10.80 mg kg-1) to investigate the effects of biochar on the bioremediation of Cd, N2O emissions and the rhizosphere microbial community structure. The bioaccumulation of Cd in the plant shoots and roots increased with all biochar addition rates (0%, 1%, 5% and 10%); unexpectedly, the translocation capacity of Cd to the edible parts of the plant significantly decreased to 0.58 mg kg-1, which was close to the edible threshold (0.4 mg kg-1). The abundance and activities of functional marker genes of microbial nitrification (amoA) and denitrification (nirK, nirS and nosZ) were quantified with quantitative PCR, and we found that biochar addition reduced the precursor production of rhizoshpere N2O by inhibiting the transcription of the nirK gene. In addition, the nitrogenase activity during anthesis (S) was significantly (P < 0.05) increased with 1% (v/v) biochar addition. Noticeably, biochar addition only changed the microbial community structure in the very first stage before eventually stabilize. This study highlighted that biochar has the potential ability to maintain the quality of agricultural crops, remediate Cd-contaminated soils and may help reduce N2O emissions without disturbing the microbial community.

A design method of a cascaded whole-leaf spring mechanism is proposed, which is a new oscillation guidance device for the mould in continuous casting. Then its prototype designed in this paper is produced in the lab, of which kinematics and dynamics simulations are carried out based on the rigid-flexible coupling virtual model. Simulation curves of the displacement and velocity of the mould are almost consistent with the ideal ones, which verifies the model built in this paper is rational. Furthermore, natural frequencies and mode shapes of the mechanism are calculated by dynamics simulation, and forces applied on leaf springs and revolute joints are analysed and effects of the basic parameters on these forces are also studied, which establish the basis for further studies and next application of this mechanism.

Two new alkaloidal glycosides, canthin-6-one-5-o-beta-D-xylopyranosyl- (1 --> 6)-beta-D-glucopyranoside (1) and canthin-6-one-1-o-beta-D-xylopyranosyl- (1 --> 6)-beta-D-glucopyranoside (2) named ailantcanthinosides A and B, were isolated from the root bark of Ailanthus altissima. Their structures were elucidated by one-and two-dimensional (1)H NMR, (13)C NMR, FAB-MS, HRESI-MS spectra and chemical methods.

Aims: To rapidly determine the causative agent of mass death in Lateolabrax japonicus in Zhelin Bay of Guangdong Province in China in April 2004.Methods and Results: Thirty-six strains, numbered sequentially from RP01 to RP36, were isolated from six diseased fish. All of the strains were identified as being of the same vibrio species according to the results of universal primer PCR combined with DGGE (UPPCR-DGGE). RP30 was one of these strains that was randomly selected and analysed by using a morphological, physiological and biochemical plate, Biolog GN2 Microplate System and API 20E system. Furthermore, RP30' 16S rDNA was sequenced and aligned in Genbank. Its virulence to Lateolabrax japonicus (Cuvier in Cuvier and Valenciennes) was also tested. RP30 is most closely related to four Vibrio ponticus strains (99.3% similarity). LD(50)s were 2.5 (x103 CFU per fish for intraperitoneal inoculation (IP) and 3.2 (x103 CFU per fish for intramuscular inoculation (IM), respectively.Conclusions: The investigated pathogenic agent of Lateolabrax japonicus (Cuvier in Cuvier and Valenciennes) was V. ponticus.Significance and Impact of the Study: UPPCR-DGGE is very helpful in epidemiologic investigation. Interestingly, this is the first report that V. ponticus infects cultured marine fish. DGGE was likewise first introduced to epidemiologic investigation of fish disease.

Uniform γ-CuI octahedral crystals with average size of about 15μm were prepared by a hydrothermal growth method with sodium citrate (SC). SEM observation shows that the shape evolutions of CuI particles from truncated octahedron to octahedron have been arrested. The additive, sodium citrate, plays an important role in the formation of the uniform γ-CuI octahedral crystals.

Aims: To investigate the distribution of the virulence of two Vibrio species among different strains obtained from the mariculture systems on the coast of Guangdong in China and the correlation between the virulence strains and the virulence genes among Vibrio alginolyticus.Methods: Besides three strains, 72 V. alginolyticus strains and seven Vibrio parahaemolyticus strains were examined by PCR or semi-nested PCR for the virulence genes (tlh, trh, tdh, toxR, toxRS, ctxA, VPI). Additionally, the virulence of 18 V. alginolyticus strains was tested.Significance and Impact of the Study: Virulence genes homologous to those in the V. parahaemolyticus and Vibrio cholerae are widely distributed among V. alginolyticus and V. parahaemolyticus in the coastal mariculture systems in Guangdong, China. Some of the V. alginolyticus strains are pathogenic to aquatic animals, and might have derived their virulence genes from V. parahaemolyticus or V. cholerae, representing a possible reservoir of these genes. However, there is no correlation between presence and absence of the virulence genes used to investigate V. alginolyticus and its virulent strains. In this report, we also show that tlh is distributed among V. alginolyticus.

The study examines interspecific interactions between Bemisia tabaci (Hem., Aleyrodidae) and Liriomyza sativae (Dipt., Agromyzidae) feeding on pumpkins and cucumbers. L. sativae density on control pumpkins and cucumbers peaked 3 and 2 weeks after adults were seen, respectively. Compared with controls, L. sativae densities observed for weeks 3-6 and 2-6 in the B. tabaci-pre-infested plants were significantly lower, respectively (F-2.00 = 22.66, P < 0.01). The survival of L. sativae larvae transplanted to B. tabaci-pre-infested pumpkins and cucumbers was 16.06%, 10.02% and 13.09%, 9.21%, whereas those transplanted to control plants were 52.20%, 36.06% and 48.25%, 28.22% after 5 and 10 days, respectively (chi(2) = 6.9, d.f. = 1, P < 0.01). Pupation rates of L. sativae feeding on control plants were 20.25% and 16.45%, whereas those feeding on the B. tabaci-pre-infested plants only 4.08% and 4.21%, respectively (chi(2) = 7.0, d.f. = 1, P < 0.01). The length and number of mines of L. sativae on the control pumpkins and cucumbers were 54.05%, 54.10% and 89.06%, 76.22% longer or higher than those on B. tabaci-pre-infested plants, respectively. Leaf positions of L. sativae feeding on the plants were also affected by B. tabaci-pre-infested. These results showed that B. tabaci infestations had a significantly negative effect on L. sativae when they were feeding simultaneously on the same host plant.

Abstract:  Analysis of the genetic diversity among 27 different geographical populations of Bemisia tabaci and determination of biotypes of B. tabaci in China based on amplified fragment‐length polymorphism (AFLP) and the mitochondrial cytochrome oxidase I (mtDNA COI) gene sequences were conducted. In AFLP assay, the use of five primer combinations selected from 64 primer combinations allowed the identification of 229 polymorphic bands (97.03%) from 60 to 500 bp, suggesting abundant genetic diversity among different geographical populations of B. tabaci. To further identify biotypes of B. tabaci in China, the mtDNA COI gene sequences of nine representative populations from China, Israel and Spain were obtained. Molecular phylogenetic tree based on AFLP and mtDNA COI gene analyses revealed the presence, in China, of at least four different genetic groups of B. tabaci. B biotype, Q biotype and two non‐B/Q biotype. B biotype was distributed nationwide. Q biotype was present only in the local region of China including the YunNan province and BeiJing city. This was also the first report about the invasion of Q biotype into China. Of the other two non‐B/Q biotype groups, one was found in ShanDong and HeBei provinces, and another in ZheJiang province. The non‐B/Q biotype ZheJiang population showed very high similarity with another Asian population India‐IW (AF110704) in mtDNA COI sequences and was possibly a Chinese indigenous population. The close monitoring of the Q biotype in locales of China where commercial plants were exported or imported, is now essential to avoid the further accidental distribution of the Q biotype.

An alcohol-thermal route has been developed to the growth of single crystals of yellow metastable PbO in largest dimensions of 11×1×0.1mm3, using freshly synthesized β-PbO crystallites as seeds. The transformation of metastable β-PbO to stable form (α-PbO) can be slowed down by choosing appropriate solvent as the growth medium. The obtained β-PbO crystals have a strong orientational growth parallel to the (001) plane and exhibit a lath shape. Studies found that cooling rate and NaOH concentration also have great influence on the crystallographic forms of the final products during the alcohol-thermal process.

对不同寄主植物烟粉虱(Bemisia tabaci)种群动态研究结果发现,不同寄主植物烟粉虱种群数量达高峰的时间有所差异,波幅也不一致,12种作物烟粉虱种群数量依次为油葵＞西葫芦＞棉花＞大豆＞南瓜＞茄子＞丝瓜＞番茄＞辣椒＞黄瓜＞菜豆＞玉米,说明烟粉虱对其寄主植物具有一定的自然选择性.用扩散系数(C＝S2 / )对烟粉虱在棉花、油葵和大豆作物田空间分布型初步分析结果均为聚集分布型.

This paper proposes a novel mold modification tool path regeneration algorithm for three-axis CNC machining based on ball end-mills. It utilizes the existing tool path points that have been generated for the original mold design prior to modification. With the proposed algorithm, a closed profile of the tool path points for the boundary of the modified region is first calculated. It is proven that if the boundary of the mold modification is interference-free, only the tool path points inside this boundary are affected by the mold modification. The tool path points that are outside the boundary can be reused to machine the modified mold. When the affected tool path points are detected, they are removed and replaced by the new tool path points. The scallop height values for the modified region are then checked. If the scallop height is greater than the given value, more CL points are added to this region to maintain the required surface finish. The algorithm has been tested on several industrial parts, and it is proven to be efficient and robust. The generated new tool path is interference-free and meets the required surface finish.

Reactions of MeSPCl(2), EtSPCl(2) and CIPSCH2CH2S, respectively with Co-2(CO)(8) in the presence of zinc powder give the Co-6 clusters [Co-6(mu 6-P)(mu-SMe)(3)(CO)(12)] 1, [Co-6(mu(6)-P)(mu-SEt)(3)(CO)(12)] 2 and [Co-6(mu-P)(mu(4)-SCH2CH2S)(mu-PSCH2CH2S) (CO)12] 3 respectively; in 1 six Co atoms form a boat-shaped array consisting of a basal square of four cobalt atoms with two opposite edges bridged by two apical Co atoms, with the metal arrangement surrounding a semi-interstitial P atom, and with two mu-SMe ligands bridging underneath the basal square and another bridging mu-SMe side-linked to the basal square.

Bulk Al3Ti samples have been fabricated successfully by combining mechanical alloying of mixtures of Al and Ti powders with subsequent pseudo-HIP processing at relatively low temperatures. The bending strength and fracture toughness of the as-fabricated Al3Ti have been improved substantially by alloying with 5 at% Ni during the processing.