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  • 1
    In: Journal of Applied Crystallography, International Union of Crystallography (IUCr), Vol. 49, No. 5 ( 2016-10-01), p. 1544-1560
    Abstract: A precise determination of sample composition and water uptake of La 6− x WO 12−δ (0.4 ≤ x ≤ 0.8) and Re-substituted La 5.4 W 1− y Re y O 12−δ (0 ≤ y  ≤ 0.2) lanthanum tungstate is carried out. Sample compositions and water uptake were determined by electron probe micro-analysis and thermogravimetry, respectively. A single-phase region of Re-substituted lanthanum tungstates is reported. The crystal structure of two selected specimens produced by the citrate-complexation route based on the Pechini method, namely La 5.4 WO 12−δ and La 5.4 W 0.8 Re 0.2 O 12−δ , was investigated by neutron diffraction in the temperature range 1.5 ≤ T ≤ 1200 K. The structural model for lanthanum tungstates is validated, according to which the Wyckoff site shared by La and W (Fm{\overline 3}m space group, 24 d site) is split with half-site occupancies (Fm{\overline 3}m space group, 48 h site). Replacement of W by up to 20 mol% Re does not change the lattice structure, and Re atoms substitute for W statistically in both 4 a and 48 h Wyckoff sites of the Fm{\overline 3}m space group, as shown by combining the average neutron scattering length procedure, thermogravimetry and electron probe micro-analysis. Using the Willis and Pryor approach to anisotropic displacement parameters it is shown that the remaining static disorder in the unit cell found in La 5.4 WO 12−δ and La 5.4 W 0.8 Re 0.2 O 12−δ structures is comparable, when the Fm{\overline 3}m space group with split 48 h site is employed. Through the estimation of the Debye temperature for both compounds, extracted from the analysis of thermal expansion coefficients and from the Willis and Pryor approach, anion anharmonic vibrations like those in yttria-stabilized zirconia are proven to exist in LaWO for the first time.
    Type of Medium: Online Resource
    ISSN: 1600-5767
    Language: Unknown
    Publisher: International Union of Crystallography (IUCr)
    Publication Date: 2016
    detail.hit.zdb_id: 2020879-0
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  • 2
    In: Journal of Applied Crystallography, International Union of Crystallography (IUCr), Vol. 52, No. 5 ( 2019-10-01), p. 1043-1053
    Abstract: A determination of the detailed crystal structure of an Mo-substituted lanthanum tungstate series, La 6− x W 1− y Mo y O 12−δ (0 ≤ y ≤ 0.2, δ is the oxygen deficiency), is presented. Material of composition La 5.4 W 0.8 Mo 0.2 O 12−δ ( y = 0.2) produced by the citrate-complexation route based on the Pechini method was investigated by high-resolution X-ray diffraction and neutron diffraction in the temperature range 10 ≤ T ≤ 298 K. The results are compared with a non-substituted material La 5.4 WO 12−δ . A structural model established earlier for lanthanum tungstates and Re-substituted lanthanum tungstates is confirmed, according to which the Wyckoff site shared by La and W is split with half site occupancies (Fm\bar 3m space group, 48 h site) and also accommodates Mo atoms. Substitution of W by up to 20 mol% Mo does not change the face-centred cubic lattice: Mo atoms substitute W statistically on both 4 a and 48 h Wyckoff sites of the crystal structure, which is described by the Fm\bar 3m space group. These results were obtained from the combination of the average neutron-scattering length and average X-ray scattering power procedures with electron-probe micro-analysis. The temperature dependence of bond lengths in dry and wet (D 2 O) conditions shows that vacant oxygen sites are located on the 32 f Wyckoff sites also in Mo-substituted lanthanum tungstates, and that the bond lengths between La on 4 b and O on 32 f increase with increasing p O 2 and p D 2 O, reflecting the filling of oxygen vacancies and the increase in coordination of La on 4 b .
    Type of Medium: Online Resource
    ISSN: 1600-5767
    Language: Unknown
    Publisher: International Union of Crystallography (IUCr)
    Publication Date: 2019
    detail.hit.zdb_id: 2020879-0
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  • 3
    In: European Journal of Inorganic Chemistry, Wiley, Vol. 2013, No. 35 ( 2013-12-02), p. 6049-6059
    Abstract: Orange‐red trinuclear nickel(II) complexes are obtained by reacting Ni(ClO 4 ) 2 (H 2 O) 6 with 3(5)‐arylpyrazoles in the presence of a base. Herein, the diamagnetic nickel centers are coordinated in a square‐pyramidal manner by four pyrazolato ligands, each of which bridges two nickel sites. The structurally unique complexes were investigated by NMR, IR, fluorescence, and X‐ray spectroscopy. All seven compounds described here were structurally elucidated by single‐crystal X‐ray diffraction. With 3(5)‐ferrocenylpyrazole as the substrate, a nonametallic system that possesses six redox‐active ferrocenyl moieties was obtained.
    Type of Medium: Online Resource
    ISSN: 1434-1948 , 1099-0682
    URL: Issue
    RVK:
    Language: English
    Publisher: Wiley
    Publication Date: 2013
    detail.hit.zdb_id: 1475009-0
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  • 4
    Online Resource
    Online Resource
    Cambridge University Press (CUP) ; 1997
    In:  Weed Science Vol. 45, No. 1 ( 1997-02), p. 108-119
    In: Weed Science, Cambridge University Press (CUP), Vol. 45, No. 1 ( 1997-02), p. 108-119
    Abstract: Intensive surveys were conducted in 2 fields in eastern Nebraska to determine the spatial stability of common sunflower, velvetleaf, green and yellow foxtail, and hemp dogbane over 4 yr (1992 to 1995). The 1st field was planted to soybean in 1992 and corn in 1993, 1994, and 1995. The 2nd field was planted to corn in 1992 and 1994 and soybean in 1993 and 1995. Weed density was sampled prior to postemergence herbicide application at approximately 800 locations per year in each field on a regular 7 m grid. The same locations were sampled every year. Weed density at locations between the sample sites was determined by linear triangulation interpolation. Weed seedling distribution was significantly aggregated, with large weed-free areas in both fields. Common sunflower, velvetleaf, and hemp dogbane patches were very persistent in diameter in the east-west and north-south directions and in location and area over 4 yr in the 1st field. Foxtail distribution and density continuously increased in each of the 4 yr in the first field and decreased in the 2nd field. A geographic information system was used to overlay maps from each year for a species. This showed that 36% of the sampled area was continuously free of common sunflower, 62.5% was free of hemp dogbane, and 11.5% was free of velvetleaf in the 1st field, but only 1% was free of velvetleaf in the 2nd field. The persistence of broadleaf weed patches suggests that weed seedling distributions mapped in one year are good predictors of future seedling distributions. Improved and more efficient sampling methods are needed.
    Type of Medium: Online Resource
    ISSN: 0043-1745 , 1550-2759
    Language: English
    Publisher: Cambridge University Press (CUP)
    Publication Date: 1997
    detail.hit.zdb_id: 2123881-9
    SSG: 12
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  • 5
    Online Resource
    Online Resource
    Cambridge University Press (CUP) ; 2014
    In:  Weed Science Vol. 62, No. 4 ( 2014-12), p. 608-618
    In: Weed Science, Cambridge University Press (CUP), Vol. 62, No. 4 ( 2014-12), p. 608-618
    Abstract: The effect of weed interference on corn yield and the critical period for weed control (CPWC) were determined in Germany and Benin. Treatments with weed control starting at different crop growth stages and continuously kept weed-free until harvest represented the “weed-infested interval.” Treatments that were kept weed-free from sowing until different crop growth stages represented the “weed-free interval.” Michaelis–Menten, Gompertz, logistic and log–logistic models were employed to model the weed interference on yield. Cross-validation revealed that the log–logistic model fitted the weed-infested interval data equally well as the logistic and slightly better than the Gompertz model fitted the weed-free interval. For Benin, economic calculations considered yield revenue and cost increase due to mechanical weeding operations. Weeding once at the ten-leaf stage of corn resulted already profitable in three out of four cases. One additional weeding operation may optimize and assure profit. Economic calculations for Germany determined a CPWC starting earlier than the four-leaf stage, challenging the decade-long propagated CPWC for corn. Differences between Germany and Benin are probably due to the higher yields and high costs in Germany. This study provides a straightforward method to implement economic data in the determination of the CPWC for chemical and nonchemical weed control strategies.
    Type of Medium: Online Resource
    ISSN: 0043-1745 , 1550-2759
    Language: English
    Publisher: Cambridge University Press (CUP)
    Publication Date: 2014
    detail.hit.zdb_id: 2123881-9
    SSG: 12
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  • 6
    In: Weed Technology, Cambridge University Press (CUP), Vol. 27, No. 4 ( 2013-12), p. 768-777
    Abstract: Se encontró que Calystegia hederacea fue una de las especies de malezas más abundantes y más difíciles de controlar en un estudio observacional de 2 años de duración en más de 100 campos de trigo de invierno en la región de las Planicies del Norte de China. Análisis multivariado de datos mostró que C. hederacea es más abundante en sitios con niveles comparativos bajos de intensidad de fertilización con nitrógeno (N) y densidades de cultivo bajas. Para ganar un mayor conocimiento sobre la biología de C. hederacea bajo intensidades variables de N, densidades de siembra de trigo de invierno, tratamientos con herbicidas, y sus interacciones, se realizó un experimento de campo durante 2 años. En parcelas sin fertilización, se encontró una eficacia del herbicida (basada en reducción de la densidad de la maleza) de 22% con 2,4-D, y de 25% con tribenuron-methyl. La eficacia máxima de herbicidas, en parcelas fertilizadas usando el método N min , fue 32% con 2,4-D y 34% con tribenuron-methyl. En las parcelas fertilizadas de acuerdo a las prácticas de los productores, la eficacia máxima del herbicida observada fue 72% para 2,4-D y 64% para tribenuron-methyl. Además, densidades de siembra medias y altas mejoraron la eficacia del herbicida en al menos 39% con tribenuron-methyl y 44% con 2,4-D al comparase con la densidad de siembra baja. El rendimiento del trigo de invierno no fue afectado significativamente por la densidad de siembra, mientras que en las densidades de siembra baja y media, la fertilización N min disminuyó el rendimiento del trigo de invierno significativamente, al compararse con las prácticas de fertilización usuales de los productores. En la densidad de siembra alta, la fertilización N min resultó en rendimientos iguales en comparación con las prácticas de fertilización de los productores.
    Type of Medium: Online Resource
    ISSN: 0890-037X , 1550-2740
    Language: English
    Publisher: Cambridge University Press (CUP)
    Publication Date: 2013
    detail.hit.zdb_id: 2119100-1
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  • 7
    Online Resource
    Online Resource
    MDPI AG ; 2018
    In:  Sensors Vol. 18, No. 11 ( 2018-11-05), p. 3771-
    In: Sensors, MDPI AG, Vol. 18, No. 11 ( 2018-11-05), p. 3771-
    Abstract: Herbicide resistant weeds need to be identified early so that yield loss can be avoided by applying proper field management strategies. A novel chlorophyll-fluorescence-imaging sensor has been developed to conduct real-time herbicide effect evaluation. In this research, greenhouse and field experiments were conducted to calibrate the capability of the sensor in monitoring herbicide effects on different biotypes of two grass weeds (Alopecurus myosuroides, Apera spica-venti) in southwestern Germany. Herbicides with different modes of action were applied for the effect monitoring. Chlorophyll fluorescence yield of the plants was measured 3–15 days after treatment (DAT) using the new fluorescence sensor. Visual assessment of the weeds was carried out on 21 DAT. The results showed that the maximal PS II quantum yield (Fv/Fm) of herbicide sensitive weeds was significantly lower than the values of resistant populations in 5 DAT. The new technology was capable of quickly identifying the herbicide’s effect on plants. It can be used to optimize management strategies to control herbicide resistant weeds.
    Type of Medium: Online Resource
    ISSN: 1424-8220
    Language: English
    Publisher: MDPI AG
    Publication Date: 2018
    detail.hit.zdb_id: 2052857-7
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  • 8
    In: Agriculture, MDPI AG, Vol. 8, No. 5 ( 2018-04-29), p. 65-
    Type of Medium: Online Resource
    ISSN: 2077-0472
    Language: English
    Publisher: MDPI AG
    Publication Date: 2018
    detail.hit.zdb_id: 2651678-0
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  • 9
    Online Resource
    Online Resource
    International Union of Crystallography (IUCr) ; 2016
    In:  Acta Crystallographica Section A Foundations and Advances Vol. 72, No. a1 ( 2016-08-28), p. s307-s307
    In: Acta Crystallographica Section A Foundations and Advances, International Union of Crystallography (IUCr), Vol. 72, No. a1 ( 2016-08-28), p. s307-s307
    Type of Medium: Online Resource
    ISSN: 2053-2733
    Language: Unknown
    Publisher: International Union of Crystallography (IUCr)
    Publication Date: 2016
    detail.hit.zdb_id: 2020844-3
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  • 10
    Online Resource
    Online Resource
    Walter de Gruyter GmbH ; 2009
    In:  itit Vol. 51, No. 6 ( 2009-12), p. 347-354
    In: itit, Walter de Gruyter GmbH, Vol. 51, No. 6 ( 2009-12), p. 347-354
    Abstract: Das DFG-Graduiertenkolleg 722 erarbeitet in einem interdisziplinären Ansatz Methoden und Verfahren für einen teilschlagspezifischen und effizienten Schutz von Nutzpflanzen vor Ertragsverlusten durch Unkräuter, Pathogene und Nematoden. Durch die Nutzung bzw. Entwicklung innovativer Methoden der Sensortechnik, von Geoinformationssystemen, der Informationsverarbeitung und Regeltechnik soll es ermöglicht werden, Pflanzenschutzmaßnahmen im Bestand nur durchzuführen, wo und wann sie ökonomisch erforderlich sind. Mit Methoden der Nah- und Fernerkundung sowie des Global Positioning Systems wird zunächst die Heterogenität des Auftretens der Schaderreger bzw. deren Symptome im Bestand georeferenziert erfasst. In Offline- bzw. Online-Verfahren werden diese Informationen in Schaderreger-spezifischen Expertensystemen analysiert und für die Ableitung ortsspezifischer Bekämpfungsentscheidungen herangezogen. Der Erfolg der Maßnahmen bzw. die längerfristigen Auswirkungen eines präzisierten, teilschlagspezifischen Pflanzenschutzes auf das Schaderregerauftreten werden wiederum mit den Sensoren erfasst. Diese neue Qualität des Pflanzenschutzes kann durch die Dokumentation aller Teilschritte belegt werden und soll dem Anwender dadurch die Entwicklung neuer Produktstandards bzw. eine ökologischen Bilanz seiner Tätigkeiten ermöglichen.
    Type of Medium: Online Resource
    ISSN: 2196-7032 , 1611-2776
    RVK:
    RVK:
    Language: English
    Publisher: Walter de Gruyter GmbH
    Publication Date: 2009
    detail.hit.zdb_id: 2102301-3
    detail.hit.zdb_id: 144419-0
    detail.hit.zdb_id: 165820-7
    detail.hit.zdb_id: 2028598-X
    detail.hit.zdb_id: 6242-X
    detail.hit.zdb_id: 1146417-3
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