The biology and control of reed canarygrass (Phalaris arundinacea L.) on irrigation ditchbanks

Reed canarygrass (Phalaris arundinacea L.) is a desirable pasture grass on wet areas in the Northern United States and Southern Canada, but it is a serious and troublesome ditchbank weed in the Pacific Northwest and Rocky Mountain States. The purpose of this study was to learn more about the development, growth habits, and control of reed canarygrass on irrigation ditchbanks. Ninety-seven percent or more of the seed of this species germinated ediately after harvest under favorable conditions. Seeds stored in damp sand at constant temperatures of 1 and 23C for periods of time up to one year did not germinate until they were subjected to alternating temperatures of 20 and 30C. The first rhizome development on reed canarygrass seedlings grown in the greenhouse was observed 26 days after emergence. Within 16 weeks after emergence, the plants were in bloom and had 48 short rhizomes (6.5 cm maximum) per plant. In the field, 88 percent or more of the emergent: shoots on established plants originated from rhizome or tiller buds located in the upper 5 cm of soil. Some shoots developed from buds located at depths up to 20 cm, but none arose from a greater depth. Several vegetative characteristics of reed canarygrass plants collected from six irrigation projects in four states differed widely when grown in a garden at Prosser, Washington. The plant height, seed weights, panicle length, leaf length, leaf width, number of stems per plant, stem diameter, and the rate of spread by rhizomes were statistically different at the 5% level of probability. Large differences in the color and posture of the leaves were also observed. Plants collected near Huntley, Montana, were the most vigorous. Total available carbohydrates in the roots and rhizomes of established reed canarygrass were not affected by single applications of 2,2,dichloropropionic acid (dalapon) at 22 kg/ha, 3-amino-s-triazoleammonium thiocyanate (amitrole-T) at 4.5 kg/ha, or 1,1i-dimethy1-4,4'- bipyridinium ion (paraquat) at 1.1 kg/ha until 2 months after treatments were applied in May. By October, single applications of dalapon and amitrole-T and five repeated applications of paraquat reduced the carbohydrates 24, 28, and 50 percent, respectively. Two additional treatments of dalapon or amitrole-T or five additional treatments of paraquat in the second year of the study did not reduce the carbohydrate levels below those present during the first year. Dalapon and trichloroacetic acid (TCA), applied to the soil or to the senescent foliage in November at rates from 22 to 88 kg/ha, provided good to excellent temporary control of reed canarygrass without denuding ditchbanks. Redtop (Avostis alba L.) and reed canarygrass seedlings developed on the treated areas the following summer and reed canarygrass retained the dominant position unless the seedlings and plants that escaped the fall treatment were controlled with post-emergence applications of dalapon or amitrole-T. When the latter plants were controlled, redtop developed from natural or artificial seeding of the ditchbank and became the dominant species. Maximum residue levels of TCA in irrigation water ranged from 104 to 225 ppb following fall applications of TCA at 82 kg/ha to both banks of three irrigation laterals that ranged from 4 to 14.5 kilometers long. Average residue levels at the downstream ends of the laterals during the first four hours that water flowed through them in the spring ranged from 34 to 47 ppb. Eight hours after the initial flow of water through laterals 4, 8.4, and 14.5 kilometers long, residue levels were less than 1 ppb in the two shortest laterals and only 2.7 ppb in the longest lateral. No residues were detectable in the water from any of the laterals after 48 hours

Jahn-Teller-driven Phase Segregation in Mnx_{x}Co3−x_{3-x}O4_{4} Spinel Thin Films

Transition metal spinel oxides comprised of Earth-abundant Mn and Co have long been explored for their use in catalytic reactions and energy storage. However, understanding of functional properties can be challenging due to differences in sample preparation and the ultimate structural properties of the materials. Epitaxial thin film synthesis provides a novel means of producing precisely-controlled materials to explore the variations reported in the literature. In this work, Mn$_{x}$Co$_{3-x}$O$_{4}$ samples from x = 0 to x = 1.28 were synthesized through molecular beam epitaxy and characterized to develop a material properties map as a function of stoichiometry. Films were characterized via in situ X-ray photoelectron spectroscopy, X-ray diffraction, scanning transmission electron microscopy, and polarized K-edge X-ray absorption spectroscopy. Mn cations within this range were found to be octahedrally coordinated, in line with an inverse spinel structure. Samples largely show mixed Mn$^{3+}$ and Mn$^{4+}$ character with evidence of phase segregation tendencies with increasing Mn content and increasing Mn$^{3+}$ formal charge. Phase segregation may occur due to structural incompatibility between cubic and tetragonal crystal structures associated with Mn$^{4+}$ and Jahn-Teller active Mn$^{3+}$ octahedra, respectively. Our results help to explain the reported differences across samples in these promising materials for renewable energy technologies.Comment: 25 pages, 8 figures; Supplemental info and figures, 9 page

Dynamics of cubic-tetragonal phase transition in KNbO3_3 perovskite

The low-energy part of the vibration spectrum in KNbO$_3$ was studied by cold neutron inelastic scattering in the cubic phase. In addition to acoustic phonons, we observe strong diffuse scattering, which consists of two components. The first one is quasi-static and has a temperature-independent intensity. The second component appears as quasi-elastic scattering in the neutron spectrum indicating a dynamic origin. From analysis of the inelastic data we conclude that the quasi-elastic component and the acoustic phonon are mutually coupled. The susceptibility associated with the quasi-elastic component grows as the temperature approaches T$_C$

Polarization Dependence of Born Effective Charge and Dielectric Constant in KNbO3_3

The Born effective charge Z^{*} and dielectric tensor \epsilon_{\infty} of KNbO_3 are found to be very sensitive to the atomic geometry, changing by as much as 27% between the paraelectric cubic and ferroelectric tetragonal and rhombohedral phases. Subtracting the bare ionic contribution reveals changes of the dynamic component of Z^{*} as large as 50%, for atomic displacements that are typically only a few percent of the lattice constant. Z^{*}, \epsilon_{\infty} and all phonon frequencies at the Brillouin zone center were calculated using the {\it ab initio} linearized augmented plane-wave linear response method with respect to the reference cubic, experimental tetragonal, and theoretically determined rhombohedral ground state structures. The ground state rhombohedral structure of KNbO_3 was determined by minimizing the forces on the relaxed atoms. By contrast with the cubic structure, all zone center phonon modes of the rhombohedral structure are stable and their frequencies are in good agreement with experiment. In the tetragonal phase, one of the soft zone center modes in the cubic phase is stablized. In view of the small atomic displacements involved in the ferroelectric transitions, it is evident that not only the soft mode frequencies but also the Born effective charge and dielectric constants are very sensitive to the atomic geometry.Comment: 26 pages, revtex, no figures; to appear in Phys. Rev. B15 (Oct.), 199

Comparison of the Electronic Structures and Energetics of Ferroelectric LiNbO3 and LiTaO3

This paper explains the origin of the ferroelectric instability in LiNbO3 and LiTaO3 and compares the electronic structures and energetics of the two materials.Comment: 31 pages, 11 Postscript figure

The Energetics of Li Off-Centering in K1−x_{1-x}Lix_xTaO3_3; First Principles Calculations

K$_{1-x}$Li$_{x}$TaO$_3$ (KLT) solid solutions exhibit a variety of interesting physical phenomena related to large displacements of Li-ions from ideal perovskite A-site positions. First-principles calculations for KLT supercells were used to investigate these phenomena. Lattice dynamics calculations for KLT exhibit a Li off-centering instability. The energetics of Li-displacements for isolated Li-ions and for Li-Li pairs up to 4th neighbors were calculated. Interactions between nearest neighbor Li-ions, in a Li-Li pair, strongly favor ferroelectric alignment along the pair axis. Such Li-Li pairs can be considered "seeds" for polar nanoclusters in KLT. Electrostriction, local oxygen relaxation, coupling to the KT soft-mode, and interactions with neighboring Li-ions all enhance the polarization from Li off-centering. Calculated hopping barriers for isolated Li-ions and for nearest neighbor Li-Li pairs are in good agreement with Arrhenius fits to experimental dielectric data.Comment: 14 pages including 10 figures. To Physical Review B. Replaced after corrections due to referees' remark

Gamma phonons and microscopic structure of orthorhombic KNbO3 from first-principles calculations

{}From a series of total energy calculations by the full-potential linear muffin-tin orbital method, the total energy hypersurface as function of atomic displacements from equilibrium positions has been fitted for different Gamma phonon modes in orthorhombic KNbO3. Frequencies and eigenvectors of all TO Gamma phonons have been calculated in the harmonic approximation, and in the quantum oscillator scheme -- for A2 and B2 modes. The microscopic structure of the orthorhombic phase has been analyzed in a series of supercell calculations for different patterns of Nb displacements, providing indications in favour of the chain structure, with oppositely directed neighboring chains.Comment: 10 pages, including 3 LaTeX figure

Genome-Wide Analysis of DNA Methylation and Fine Particulate Matter Air Pollution in Three Study Populations: KORA F3, KORA F4, and the Normative Aging Study

BACKGROUND: Epidemiological studies have reported associations between particulate matter (PM) concentrations and cancer and respiratory and cardiovascular diseases. DNA methylation has been identified as a possible link but so far it has only been analyzed in candidate sites. OBJECTIVES: We studied the association between DNA methylation and short-and mid-term air pollution exposure using genome-wide data and identified potential biological pathways for-additional investigation. METHODS: We collected whole blood samples from three independent studies-KORA F3 (2004-2005) and F4 (2006-2008) in Germany, and the Normative Aging Study (1999-2007) in the United States-and measured genome-wide DNA methylation proportions with the Illumina 450k BeadChip. PM concentration was measured daily at fixed monitoring stations and three different trailing averages were considered and regressed against DNA methylation: 2-day, 7-day and 28-day. Meta-analysis was performed to pool the study-specific results. RESULTS: Random-effect meta-analysis revealed 12 CpG (cytosine-guanine dinucleotide) sites as associated with PM concentration (1 for 2-day average, 1 for 7-day, and 10 for 28-day) at a genome-wide Bonferroni significance level (p 0.05 and I-2< 0.5: the site from the 7-day average results and 3 for the 28-day average. Applying false discovery rate, p-value < 0.05 was observed in 8 and 1,819 additional CpGs at 7- and 28-day average PM2.5 exposure respectively. CONCLUSION: The PM-related CpG sites found in our study suggest novel plausible systemic pathways linking ambient PM exposure to adverse health effect through variations in DNA methylation

Highly Sensitive Fluorescence Probe Based on Functional SBA-15 for Selective Detection of Hg2+

An inorganic–organic hybrid fluorescence chemosensor (DA/SBA-15) was prepared by covalent immobilization of a dansylamide derivative into the channels of mesoporous silica material SBA-15 via (3-aminopropyl)triethoxysilane (APTES) groups. The primary hexagonally ordered mesoporous structure of SBA-15 was preserved after the grafting procedure. Fluorescence characterization shows that the obtained inorganic–organic hybrid composite is highly selective and sensitive to Hg2+ detection, suggesting the possibility for real-time qualitative or quantitative detection of Hg2+ and the convenience for potential application in toxicology and environmental science