Chlorophyll fluorescence response to herbicide stress in Alopecurus myosuroides

Herbicide resistance has been a widely spread problem all over the world. The resistance detection is usually complicated and financial resources consuming. A sensor based monitoring of herbicide resistance would make the resistance detection much faster and spends less. In this research, greenhouse and field experiments with susceptive and resistant populations were conducted to study the chlorophyll fluorescence response of Alopecurus myosuroides after herbicide treatment. The fluorescence sensor WEED-PAM was used for measuring the maximum photosynthesis system II quantum yield (Fv/Fm) of Alopecurus myosuroides after the application for two weeks.The Fv/Fm values of all untreated plants were around 0.7. In the greenhouse, Fv/Fm values of treated susceptive plants reduced significantly from 0.7 to 0.6-0.65 since 3 DAT (days after treatment), but Fv/Fm values of herbicide resistant populations show no significant reductions with ALS and ACCase treatments. With the treatment of PSII inhibitors the Fv/Fm values of susceptive and resistant plants decreased to 0.25 and 0.6 (3DAT) and further to 0.1 and 0.5 (14 DAT), respectively. The field experiments show corresponding results to the greenhouse test. With ALS and ACCase treatment, significant Fv/Fm reduction for the susceptive populations can be detected between 3-7 DAT. During the measurement of PS II inhibitor treatment, Fv/Fm values of susceptive plants decreased continuously from 0.5 to 0.2, while the value of resistant population kept stable in range 0.3-0.4.The prototype WEED-PAM is suitable for the detection of herbicide effects based on Fv/Fm values and takes less time than visual assessment. This research shows the potential usage of fluorescence meter in herbicide resistance detection.Chlorophyll-Fluoreszenz-Reaktion auf Herbizidstress bei Alopecurus myosuroidesHerbizidresistenz ist zu einem weit verbreiteten Problem weltweit geworden. Die Detektion von Resistenzen ist in der Regel kompliziert und kostenintensiv. Eine sensorbasierte Überwachung von Herbizidresistenz würde deren Bestimmung viel schneller und günstiger machen. In dieser Arbeit wurden Feld- und Gewächshausexperimente mit sensitiven und resistenten Populationen von Alopecurus myosuroides durchgeführt. Hierbei wurde die Chlorophyllfluoreszenz der Pflanzen gemessen um die Wirkung von Herbizid-Behandlungen zu untersuchen. Die maximale Quantenausbeute des Photosystem II (Fv/Fm) von Alopecurus myosuroides wurde nach der Herbizid-Behandlung für zwei Wochen mit dem Chlorophyll-Fluoreszenz-Sensor WEEDPAM gemessen.Die unbehandelten Kontrollpflanzen zeigten stabile Fv/Fm Werte von rund 0,7. In den Gewächshausversuchen mit ALS und ACCase Hemmern sanken die Fv/Fm Werte der behandelten sensitiven Pflanzen 3 TnA (Tage nach Applikation) signifikant von 0.7 auf 0.6-0.65 ab. Die resistenten Pflanzen hingegen zeigten keine signifikanten Abnahmen. Die Fv/Fm-Werte sanken in der Behandlung mit PS II-Inhibitoren innerhalb von 3-4 Tagen in der sensitiven Population auf 0.25 und in den resistenten Pflanzen auf 0.6, 14 TnA zeigten sich für sensitive Pflanzen noch niedrigere Werte von 0.1, wohingegen resistente Pflanzen Werte von 0.5 aufwiesen. Die Feldversuche zeigten ähnliche Ergebnisse wie die Gewächshausversuche. In den ALS- und ACCase Behandlungen wurden für die sensitiven Populationen signifikante Fv/Fm Reduktionen bereits nach 3-7 TnA festgestellt. In den Behandlungen mit PS II Inhibitoren fielen die Fv/Fm Werte der sensitiven Pflanzen kontinuerlich von 0.5 auf 0.2 ab (innerhalb von 14 Tagen), während die resistenten Pflanzen stabil auf einem Wert von 0.3-0.4 blieben. Der WEED-PAM Prototyp eignet sich für die sensorbasierte Stress-Detektion von Herbizideffekten mittels der Fv/Fm Werte. Weiterhin ist diese Methode sehr viel schneller als die visuelle Beurteilung der Herbizidsymptome. Diese Untersuchung zeigt den potentiellen Nutzen von Fluoreszenzmessgeräten für die Erfassung von Herbizidresistenzen

Utjecaj otopine u čvrstom stanju i starenja na mikrostrukturu i mehanička svojstva kompozita čestica SiCp/Al-Si-Cu-Mg

The SiC particles (SiCp, mass fraction 30 %) reinforced with the Al-Si-Cu-Mg matrix composite have been prepared using one-way press method, sintering, and hot extrusion. The composite was subjected to solid solution treatment at temperatures of 470 °C, 485 °C, 500 °C, 515 °C, and 530 °C for 4 h. The sample was then subjected to ageing treatment at temperatures of 160 °C and 180 °C during different times after solid solution treatment at 515 °C for 4 h. The microstructure and mechanical properties of the SiCp/Al-Si-Cu-Mg matrix composite under the different ageing and solid solution treatments were tested using SEM and TEM microhardness analysis. The results show that the white granulated metallic compounds of the SiCp/Al-Si-Cu-Mg composite materials, which are formed in the sintering process of composite materials, dissolve back after the solid solution treatment at different temperatures. The higher the solid solution temperature, the more metallic compounds dissolve back. The microhardness of the composites reached maximum after solution treatment at 515 °C for 4 h. Following the ageing treatment and with the prolongation of ageing time, the hardness of the composite material reached “double peak” phenomenon. With the increase in ageing temperature, the hardening speed of the composite material also increased, but at the same time, the hardening ability had reduced. After the ageing treatment, the second phases of the composite are discoid Al5Cu6Mg2. This work is licensed under a Creative Commons Attribution 4.0 International License.Pripravljen je kompozit čestica SiC (SiCp) u masenom udjelom 30 % u matrici Al-Si-Cu-Mg prešanjem, sinteriranjem i ekstrudiranjem. Kompozit je 4 sata bio izložen otapanju u čvrstom stanju pri 470 °C, 485 °C, 500 °C, 515 °C i 530 °C. Nakon toga na uzorak je 4 sata pri 515 °C djelovalo otapanje u čvrstom stanju, a zatim su uzorci starili različito vrijeme pri temperaturama 160 i 180 °C. Mikrostruktura i mehanička svojstva kompozita proučena su tehnikama pretražnom i transmisijskom mikroskopijom te analizom mikrotvrdoće. Pri sinteriranju kompozita SiCp/Al-Si-Cu-Mg nastaje bijeli zrnasti metalni spoj koji se otapa u čvrstu otopinu pri različitim temperaturama. Što je viša temperatura čvrste otopine, više se otopi metalnog spoja. Mikrotvrdoća doseže maksimum pri izlaganju reakcijama u čvrstom stanju pri 515 °C kroz četiri sata. Nakon starenja i s produljenjem starenja tvrdoća materijala pokazuje dvostruki vrh. S povišenjem temperature povećava se brzina očvršćivanja, no istodobno se smanjuje mogućnost očvršćenja. Druga faza kompozita nakon starenja je diskoidni Al5Cu6Mg2. Ovo djelo je dano na korištenje pod licencom Creative Commons Imenovanje 4.0 međunarodna

Additive manufacturing of interstitial-strengthened high entropy alloy: Scanning strategy dependent anisotropic mechanical properties

A non-equiatomic interstitial-strengthened high entropy alloy (iHEA), Fe49.5Mn30Co10Cr10C0.5 (at.%), is manufactured by laser powder-bed fusion (LPBF) with stripe and chessboard scanning strategies. The present study highlights the correlation between the laser scanning strategies with resulting microstructure, textures, and anisotropic mechanical properties in as-built iHEA. The results show that the LPBF processed iHEA exhibits an excellent strength-ductility synergy due to the combined deformation mechanisms of dislocation slip, martensite phase transformation- and nano twinning-induced plasticity. The samples printed by the stripe scanning strategy show more evident mechanical anisotropy than that of the chessboard-scanned samples. The difference in the degree of mechanical anisotropy is mainly attributed to the heterogeneous grain morphology and crystallographic texture resulted from different scanning strategies

Two-Step Sintering of Ceramics with Constant Grain-Size, I. Y\u3csub\u3e2\u3c/sub\u3eO\u3csub\u3e3\u3c/sub\u3e

Isothermal and constant-grain-size sintering have been carried out to full density in Y2O3 with and without dopants, at as low as 40% of the homologous temperature. The normalized densification rate follows Herring’s scaling law with a universal geometric factor that depends only on density. The frozen grain structure, however, prevents pore relocation commonly assumed in the conventional sintering models, which fail to describe our data. Suppression of grain growth but not densification is consistent with a grain boundary network pinned by triple-point junctions, which have a higher activation energy for migration than grain boundaries. Long transients in sintering and grain growth have provided further evidence of relaxation and threshold processes at the grain boundary/triple point

DESIGN AND OPTIMIZATION OF THE VARIABLE-DENSITY LATTICE STRUCTURE BASED ON LOAD PATHS

Lattice structure is more and more widely used in engineering by replacing solid structure. But its mechanical performances are constrained by the external shape if the unit cells are directly filled in the design domain, and the traditional topology optimization methods are difficult to give the explicitly mechanical guidance for the distribution of internal unit cells. In this paper, a novel design and optimization method of variable-density lattice structure is proposed in order to simultaneously optimize the external shape and the internal unit cells. First of all, the envelope model of any given structure should be established, and the load paths need to be visualized by the theory of load path. Then, the design criteria of external shape are established based on the principle of smoother load paths in the structure. An index of load flow capacity is defined to indicate the load paths density and to control the density distribution of unit cells, and a detailed optimization strategy is given. Finally, three examples of a cantilever plate, an L-shaped bracket and a classical three-point bending beam are used to verify the method. The results show that the models designed by the proposed method have better mechanical performances, lower material usage and less printing time

Bis(ethyl­enediammonium) tetra­deca­borate

The title compound, 2C2H10N2 2+·B14O20(OH)6 4−, consists of a centrosymmetric tetra­deca­borate anion and two ethyl­enediammonium cations. The anions are inter­connected through strong O—H⋯O hydrogen bonds into a three-dimensional supra­molecular network with channels along [100], [010], [001] and [111]. The diprotonated cations reside in the channels and inter­act with the inorganic framework by extensive N—H⋯O hydrogen bonds

When Social Influence Meets Item Inference

Research issues and data mining techniques for product recommendation and viral marketing have been widely studied. Existing works on seed selection in social networks do not take into account the effect of product recommendations in e-commerce stores. In this paper, we investigate the seed selection problem for viral marketing that considers both effects of social influence and item inference (for product recommendation). We develop a new model, Social Item Graph (SIG), that captures both effects in form of hyperedges. Accordingly, we formulate a seed selection problem, called Social Item Maximization Problem (SIMP), and prove the hardness of SIMP. We design an efficient algorithm with performance guarantee, called Hyperedge-Aware Greedy (HAG), for SIMP and develop a new index structure, called SIG-index, to accelerate the computation of diffusion process in HAG. Moreover, to construct realistic SIG models for SIMP, we develop a statistical inference based framework to learn the weights of hyperedges from data. Finally, we perform a comprehensive evaluation on our proposals with various baselines. Experimental result validates our ideas and demonstrates the effectiveness and efficiency of the proposed model and algorithms over baselines.Comment: 12 page