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Sample records for root 3ag due

  1. CORRIGENDUM: Thermal switching of the electrical conductivity of Si(111)(√3 × √3)Ag due to a surface phase transition

    NASA Astrophysics Data System (ADS)

    Wells, J. W.; Kallehauge, J. F.; Hofmann, Ph

    2008-04-01

    Our recent paper on the surface conductivity of Si(111)(√3 × √3)Ag [1] contains an error in the numerical simulation of the space charge layer conductance presented in figure 2(b) of the paper. A new version of the figure is presented here as figure 1. The incorrect version of this figure suggested that the space charge layer conductivity of Si(111)(√3 × √3)Ag is very similar to that of the clean Si(111)(7 × 7) surface but actually this is not the case. The space charge layer for Si(111)(7 × 7) becomes strongly insulating at low temperatures whereas it is rather conductive over the whole temperature range for Si(111)(√3 × √3)Ag. Figure 1 Figure 1. Experimental results (broken lines and markers) together with simulations (solid lines) of the conductance. The simulation in (b) has now been corrected, but the figure is otherwise the same as figure 2 from [1]. The model calculation shows the expected conductance of the bulk and space charge layer in (a) and (b) and for the expected conductance of a 3 ML Ag film with bulk properties in (c). The error in the calculation of the space charge layer conductivity has an impact on the interpretation of the low temperature measurements. Based on the incorrect calculation, it was concluded that the measurements are always surface sensitive, but this is not the case. In fact, the measured conductance in the low temperature regime is now quite similar to the conductance one could expect for the bulk and space charge layer.The interpretation of the data as a switching due to the surface phase transition is still consistent with results, especially since the transition in conductivity is much steeper than one would expect for a mechanism involving the freezing of carriers in the space charge region. However, we would also like to mention an alternative interpretation at this point. The free-electron like surface state on Si(111)(√3 × √3)Ag is unoccupied at zero temperature because the bottom of the band

  2. Atrial fibrillation due to licorice root syrup.

    PubMed

    Erkuş, Musluhittin Emre; Altıparmak, İbrahim Halil; Demirbağ, Recep; Günebakmaz, Özgür

    2016-04-01

    While it is known that consumption of licorice may lead to cardiac arrhythmias, there have been no reports of atrial fibrillation resulting from the consumption of licorice root syrup. A 57-year-old male with no prior history of cardiovascular disease was admitted to the emergency department with palpitation. His electrocardiogram showed atrial fibrillation with a moderate to rapid ventricular rate. In laboratory assessment, potassium was 2.0 mmol/L and plasma renin activity and aldosterone level were suppressed (<300 ng/L/hour, 42 ng/L respectively). Volumes of the heart chambers were within normal range and functions and structures of the heart valves were normal in echocardiographic assessment. The arrhythmia was resolved with propafenone infusion. PMID:27138313

  3. Secondary chronic cluster headache due to trigeminal nerve root compression.

    PubMed

    Mjåset, Christer; Russell, M B; Russell, M Bjørn

    2010-12-01

    A 50-year-old woman had a gradual onset of chronic headache located in the right temporal region and a burning sensation in the root of the tongue which over a year evolved into chronic cluster headache with a milder chronic headache in-between the severe cluster headache attacks. A cerebral magnetic resonance imaging (MRI) showed vascular compression of the trigeminal nerve root on the pain side. Neurosurgery microvascular decompression relieved the patient's chronic cluster headache, the chronic intermittent headache and the burning tongue sensation. The effect was persistent at a 1 year follow-up. Patients with atypical symptoms of cluster headache should be examined with cerebral MRI angiography of arteries and veins to exclude symptomatic causes. PMID:20384588

  4. Effect of Aggregates Compaction in Soil Hydraulic Properties, due to Root Growth

    NASA Astrophysics Data System (ADS)

    Aravena, J. E.; Tyler, S. W.; Berli, M.

    2009-12-01

    The rhizosphere is critical for soil-root interactions, however, physical processes within the soil around roots and implications of these processes, such as plant water and nutrient uptake, continue to raise questions. Soil compaction, due to root growth, results in favorable physical conditions in the rhizosphere to foster plant growth by providing aeration under wet conditions and improving water storage and flow toward the roots under dry conditions. In unsaturated conditions, the air transfer occurs through the macropores, while the water transfer occurs through the aggregates; providing the plant with these two vital elements, continuously. At the aggregate-scale, compaction gives connectivity within the aggregates. As the contact area between the aggregates increases, more water may be transfer to the plant. As result, the hydraulic conductivity of the rhizosphere may be higher than that at initial conditions (i.e., before compaction). This idea is important, as usually compaction is associated with decreasing water conductivity. This study focuses on understanding the role of roots to modify the soil, and in particular, their impact on rhizosphere hydraulic properties at the aggregate-scale. Using HYDRUS 3D, an aggregate system was modeled. It was found that the saturated hydraulic conductivity of the system increased following an S-shape as contact area increased due to compaction. This result differs from previous studies that assumed a quadratic relation. In addition, it was found that the compaction of big pores within the aggregates will be more beneficial for water extraction purposes, than the change in pore-size distribution within the aggregates due to compaction.

  5. Metabolic Profile and Root Development of Hypericum perforatum L. In vitro Roots under Stress Conditions Due to Chitosan Treatment and Culture Time

    PubMed Central

    Brasili, Elisa; Miccheli, Alfredo; Marini, Federico; Praticò, Giulia; Sciubba, Fabio; Di Cocco, Maria E.; Cechinel, Valdir Filho; Tocci, Noemi; Valletta, Alessio; Pasqua, Gabriella

    2016-01-01

    The responses of Hypericum perforatum root cultures to chitosan elicitation had been investigated through 1H-NMR-based metabolomics associated with morpho-anatomical analyses. The root metabolome was influenced by two factors, i.e., time of culture (associated with biomass growth and related “overcrowding stress”) and chitosan elicitation. ANOVA simultaneous component analysis (ASCA) modeling showed that these factors act independently. In response to the increase of biomass density over time, a decrease in the synthesis of isoleucine, valine, pyruvate, methylamine, etanolamine, trigonelline, glutamine and fatty acids, and an increase in the synthesis of phenolic compounds, such as xanthones, epicatechin, gallic, and shikimic acid were observed. Among the xanthones, brasilixanthone B has been identified for the first time in chitosan-elicited root cultures of H. perforatum. Chitosan treatment associated to a slowdown of root biomass growth caused an increase in DMAPP and a decrease in stigmasterol, shikimic acid, and tryptophan levels. The histological analysis of chitosan-treated roots revealed a marked swelling of the root apex, mainly due to the hypertrophy of the first two sub-epidermal cell layers. In addition, periclinal divisions in hypertrophic cortical cells, resulting in an increase of cortical layers, were frequently observed. Most of the metabolic variations as well as the morpho-anatomical alterations occurred within 72 h from the elicitation, suggesting an early response of H. perforatum roots to chitosan elicitation. The obtained results improve the knowledge of the root responses to biotic stress and provide useful information to optimize the biotechnological production of plant compounds of industrial interest. PMID:27148330

  6. Plant growth promotion may compensate for losses due to moderate Aphanomyces root rot

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A two-year study was conducted to investigate the use of chemically-induced resistance and biocontrol bacteria for reducing sugar beet root rot disease caused by the oomycete organism Aphanomyces cochlioides. Stand establishment, yield, and quality analysis of sugarbeets from replicated field plots...

  7. Root zone salinity and sodicity under seasonal rainfall due to feedback of decreasing hydraulic conductivity

    NASA Astrophysics Data System (ADS)

    van der Zee, S. E. A. T. M.; Shah, S. H. H.; Vervoort, R. W.

    2014-12-01

    Soil sodicity, where the soil cation exchange complex is occupied for a significant fraction by Na+, may lead to vulnerability to soil structure deterioration. With a root zone flow and salt transport model, we modeled the feedback effects of salt concentration (C) and exchangeable sodium percentage (ESP) on saturated hydraulic conductivity Ks(C, ESP) for different groundwater depths and climates, using the functional approach of McNeal (1968). We assume that a decrease of Ks is practically irreversible at a time scale of decades. Representing climate with a Poisson rainfall process, the feedback hardly affects salt and sodium accumulation compared with the case that feedback is ignored. However, if salinity decreases, the much more buffered ESP stays at elevated values, while Ks decreases. This situation may develop if rainfall has a seasonal pattern where drought periods with accumulation of salts in the root zone alternate with wet rainfall periods in which salts are leached. Feedback that affects both drainage/leaching and capillary upward flow from groundwater, or only drainage, leads to opposing effects. If both fluxes are affected by sodicity-induced degradation, this leads to reduced salinity (C) and sodicity (ESP), which suggests that the system dynamics and feedback oppose further degradation. Experiences in the field point in the same direction.

  8. Negligible shift of 3Ag- potential in longer-chain carotenoids as revealed by a single persistent peak of 3Ag-→1Ag- stimulated emission followed by 3Ag-←1Ag- transient-absorption

    NASA Astrophysics Data System (ADS)

    Li, Chunyong; Miki, Takeshi; Kakitani, Yoshinori; Koyama, Yasushi; Nagae, Hiroyoshi

    2007-12-01

    Upon excitation of lycopene, anhydrorhodovibrin or spirilloxanthin to the 1Bu+(0) state, stimulated emission followed by transient-absorption was observed as a single peak with the 3Ag-(0) energy that had been determined by measurement of resonance-Raman excitation profiles. This observation was explained in terms of negligible shift of the 3Ag- potential, in reference to the 1Ag- potential, where only the 3Ag-(υ)→1Ag-(υ) emission and the 3Ag-(υ)←1Ag-(υ) absorption become allowed during the vibrational relaxation of υ = 2 → 1 → 0, starting from the 3Ag-(2) level generated by diabatic internal conversion from the 1Bu+(0) level, in anhydrorhodovibrin, for example.

  9. Oxygen-Ozone Therapy for Herniated Lumbar Disc in Patients with Subacute Partial Motor Weakness Due to Nerve Root Compression

    PubMed Central

    Dall'Olio, Massimo; Princiotta, Ciro; Cirillo, Luigi; Budai, Caterina; de Santis, Fabio; Bartolini, Stefano; Serchi, Elena; Leonardi, Marco

    2014-01-01

    Summary Intradiscal oxygen-ozone (O2-O3) chemonucleolysis is a well-known effective treatment for pain caused by protruding disc disease and nerve root compression due to bulging or herniated disc. The most widely used therapeutic combination is intradiscal injection of an O2-O3 mixture (chemonucleolysis), followed by periradicular injection of O2-O3, steroid and local anaesthetic to enhance the anti-inflammatory and analgesic effect. The treatment is designed to resolve pain and is administered to patients without motor weakness, whereas patients with acute paralysis caused by nerve root compression undergo surgery 24-48h after the onset of neurological deficit. This paper reports on the efficacy of O2-O3 chemonucleolysis associated with anti-inflammatory foraminal injection in 13 patients with low back pain and cruralgia, low back pain and sciatica and subacute partial motor weakness caused by nerve root compression unresponsive to medical treatment. All patients were managed in conjunction with our colleagues in the Neurosurgery Unit of Bellaria Hospital and the IRCCS Institute of Neurological Sciences, Bologna. The outcomes obtained are promising: 100% patients had a resolution of motor weakness, while 84.6% had complete pain relief. Our results demonstrate that O2-O3 therapy can be considered a valid treatment option for this category of patients. PMID:25363257

  10. Increased nitrogen leaching following soil freezing is due to decreased root uptake in a northern hardwood forest.

    PubMed

    Campbell, John L; Socci, Anne M; Templer, Pamela H

    2014-08-01

    The depth and duration of snow pack is declining in the northeastern United States as a result of warming air temperatures. Since snow insulates soil, a decreased snow pack can increase the frequency of soil freezing, which has been shown to have important biogeochemical implications. One of the most notable effects of soil freezing is increased inorganic nitrogen losses from soil during the following growing season. Decreased nitrogen retention is thought to be due to reduced root uptake, but has not yet been measured directly. We conducted a 2-year snow-removal experiment at Hubbard Brook Experimental Forest in New Hampshire, USA to determine the effects of soil freezing on root uptake and leaching of inorganic nitrogen simultaneously. Snow removal significantly increased the depth of maximal soil frost by 37.2 and 39.5 cm in the first and second winters, respectively (P < 0.001 in 2008/2009 and 2009/2010). As a consequence of soil freezing, root uptake of ammonium declined significantly during the first and second growing seasons after snow removal (P = 0.023 for 2009 and P = 0.005 for 2010). These observed reductions in root nitrogen uptake coincided with significant increases in soil solution concentrations of ammonium in the Oa horizon (P = 0.001 for 2009 and 2010) and nitrate in the B horizon (P < 0.001 and P = 0.003 for 2009 and 2010, respectively). The excess flux of dissolved inorganic nitrogen from the Oa horizon that was attributable to soil freezing was 7.0 and 2.8 kg N ha(-1) in 2009 and 2010, respectively. The excess flux of dissolved inorganic nitrogen from the B horizon was lower, amounting to 1.7 and 0.7 kg N ha(-1) in 2009 and 2010, respectively. Results of this study provide direct evidence that soil freezing reduces root nitrogen uptake, demonstrating that the effects of winter climate change on root function has significant consequences for nitrogen retention and loss in forest ecosystems. PMID:24574104

  11. Localized application of soil organic matter shifts distribution of cluster roots of white lupin in the soil profile due to localized release of phosphorus

    PubMed Central

    Li, Hai-Gang; Shen, Jian-Bo; Zhang, Fu-Suo; Lambers, Hans

    2010-01-01

    Background and Aims Phosphorus (P) is a major factor controlling cluster-root formation. Cluster-root proliferation tends to concentrate in organic matter (OM)-rich surface-soil layers, but the nature of this response of cluster-root formation to OM is not clear. Cluster-root proliferation in response to localized application of OM was characterized in Lupinus albus (white lupin) grown in stratified soil columns to test if the stimulating effect of OM on cluster-root formation was due to (a) P release from breakdown of OM; (b) a decrease in soil density; or (c) effects of micro-organisms other than releasing P from OM. Methods Lupin plants were grown in three-layer stratified soil columns where P was applied at 0 or 330 mg P kg−1 to create a P-deficient or P-sufficient background, and OM, phytate mixed with OM, or perlite was applied to the top or middle layers with or without sterilization. Key Results Non-sterile OM stimulated cluster-root proliferation and root length, and this effect became greater when phytate was supplied in the presence of OM. Both sterile OM and perlite significantly decreased cluster-root formation in the localized layers. The OM position did not change the proportion of total cluster roots to total roots in dry biomass among no-P treatments, but more cluster roots were concentrated in the OM layers with a decreased proportion in other places. Conclusions Localized application of non-sterile OM or phytate plus OM stimulated cluster-root proliferation of L. albus in the localized layers. This effect is predominantly accounted for by P release from breakdown of OM or phytate, but not due to a change in soil density associated with OM. No evidence was found for effects of micro-organisms in OM other than those responsible for P release. PMID:20150198

  12. Semitransparent inverted polymer solar cells with MoO3/Ag/MoO3 as transparent electrode

    NASA Astrophysics Data System (ADS)

    Tao, Chen; Xie, Guohua; Liu, Caixia; Zhang, Xindong; Dong, Wei; Meng, Fanxu; Kong, Xiangzi; Shen, Liang; Ruan, Shengping; Chen, Weiyou

    2009-08-01

    Semitransparent inverted polymer solar cells were developed using thermally evaporable MoO3/Ag/MoO3 as transparent anode. The ultrathin inner MoO3 layer was introduced as a buffer layer to improve hole collection, while the outer MoO3 layer served as a light coupling layer to enhance optical transmittance of the device. The dependence of the device performances on the thickness of the outer MoO3 layer was investigated. The results showed that the addition of the outer MoO3 layer improves the transmittance of the anode compared to MoO3/Ag anode and the performances of the semitransparent devices with the outer MoO3 layer are improved due to the reduced series resistance.

  13. Sm3+:Ag NPs assisted modification in absorption features of magnesium tellurite glass

    NASA Astrophysics Data System (ADS)

    Yusoff, N. M.; Sahar, M. R.; Ghoshal, S. K.

    2015-01-01

    Metallic nanoparticles (NPs) assisted enhancements in absorption and emission cross-section of tellurite glass is the present challenge. The influences of samarium (Sm3+) ions and silver (Ag) NPs ratio on physical and optical absorption properties of melt quench synthesized magnesium tellurite glasses are reported. XRD patterns verify the amorphous nature of glasses. Glass density, molar volume and ionic packing fraction are discerned to be in the range of 4.92-5.0 g cm-3, 29.82-30.26 cm3 mol-1 and 0.452-0.446, respectively. Moderate reduction potential of tellurite glass converted Ag1+ to Ag0 via single step process and NPs are formed. TEM image manifest the existence of NPs of average diameter ∼16.94 nm having Gaussian size distribution. The significant changes in structural properties in the presence of Ag NPs are discussed in terms of TeO4 tetrahedra distortion and network depolymerization process. The Sm3+:Ag NPs dependent variation in physical properties are ascribed to the alteration in the number of bridging oxygen to non bridging (NB) one. Enhancement in absorption intensity due to the local field effects of Ag NPs is attributed to the changes in Sm-O bond strength. Optical energy band gap (2.81-3.18 eV) and Urbach energy (0.18-0.24 eV) are found increase and decrease, respectively with the increase of Sm3+:Ag NPs up to 1.33 then quenches and enhances, respectively thereafter which are related to the changes in cross-link and NBO numbers. The FTIR spectra reveal modification in network structures evidenced from vibrational wave-number shifts of TeO4 and TeO3 structural units. The observed notable increase in HOH vibration mode suggests its helpfulness in promoting the absorption of water and light. It is asserted that the physical, optical and structural properties of magnesium tellurite glass can be tuned by controlling Sm3+:Ag NPs.

  14. Highly luminescent material based on Alq3:Ag nanoparticles.

    PubMed

    Salah, Numan; Habib, Sami S; Khan, Zishan H

    2013-09-01

    Tris (8-hydroxyquinoline) aluminum (Alq3) is an organic semiconductor molecule, widely used as an electron transport layer, light emitting layer in organic light-emitting diodes and a host for fluorescent and phosphorescent dyes. In this work thin films of pure and silver (Ag), cupper (Cu), terbium (Tb) doped Alq3 nanoparticles were synthesized using the physical vapor condensation method. They were fabricated on glass substrates and characterized by X-ray diffraction, scanning electron microscope (SEM), energy dispersive spectroscopy, atomic force microscope (AFM), UV-visible absorption spectra and studied for their photoluminescence (PL) properties. SEM and AFM results show spherical nanoparticles with size around 70-80 nm. These nanoparticles have almost equal sizes and a homogeneous size distribution. The maximum absorption of Alq3 nanoparticles is observed at 300 nm, while the surface plasmon resonant band of Ag doped sample appears at 450 nm. The PL emission spectra of Tb, Cu and Ag doped Alq3 nanoparticles show a single broad band at around 515 nm, which is similar to that of the pure one, but with enhanced PL intensity. The sample doped with Ag at a concentration ratio of Alq3:Ag = 1:0.8 is found to have the highest PL intensity, which is around 2 times stronger than that of the pure one. This enhancement could be attributed to the surface plasmon resonance of Ag ions that might have increased the absorption and then the quantum yield. These remarkable result suggest that Alq3 nanoparticles incorporated with Ag ions might be quite useful for future nano-optoelectronic devices. PMID:23653126

  15. Toxicity of canavanine in tomato (Solanum lycopersicum L.) roots is due to alterations in RNS, ROS and auxin levels.

    PubMed

    Krasuska, Urszula; Andrzejczak, Olga; Staszek, Paweł; Borucki, Wojciech; Gniazdowska, Agnieszka

    2016-06-01

    Canavanine (CAN) is non-proteinogenic aminoacid and a structural analog of arginine (Arg). Naturally, CAN occurs in legumes e.g. jack bean and is considered as a strong allelochemical. As a selective inhibitor of inducible nitric oxide synthase in mammalians, it could act as a modifier of nitric oxide (NO) concentration in plants. Modifications in the content of endogenous reactive nitrogen species (RNS) and reactive oxygen species (ROS) influence root structure and architecture, being also under hormonal control. The aim of the work was to investigate regulation of root growth in tomato (Solanum lycopersicum L. cv. Malinowy Ożarowski) seedling by application of CAN at concentration (10 and 50 μM) leading to 50% or 100% restriction of root elongation. CAN at higher concentration led to slight DNA fragmentation, increased total RNA and protein level. Decline in total respiration rate after CAN supplementation was not associated with enhanced membrane permeability. Malformations in root morphology (shorter and thicker roots, limited number of lateral roots) were accompanied by modification in NO and ONOO(-) localization; determined mainly in peridermal cells and some border cells. Although, CAN resulted in low RNS production, addition of exogenous NO by usage of NO donors did not reverse its negative effect, nor recovery effect was detected after roots imbibition in Arg. To build up a comprehensive view on mode of action of CAN as root growth inhibitor, it was shown an elevated level of auxin. To summarize, we demonstrated several secondary mode of action of CAN, indicating its toxicity in plants linked to restriction in RNS formation accompanied by simultaneous overaccumulation of ROS. PMID:26986929

  16. Spectra of surface plasmon polariton enhanced electroluminescence from electroformed Al-Al{sub 2}O{sub 3}-Ag diodes

    SciTech Connect

    Hickmott, T. W.

    2015-03-07

    Narrow band-pass filters have been used to measure the spectral distribution of electroluminescent photons with energies between 1.8 eV and 3.0 eV from electroformed Al-Al{sub 2}O{sub 3}-Ag diodes with anodic Al{sub 2}O{sub 3} thicknesses between 12 nm and 18 nm. Electroforming of metal-insulator-metal (MIM) diodes is a non-destructive dielectric breakdown that results in a conducting channel in the insulator and changes the initial high resistance of the MIM diode to a low resistance state. It is a critical step in the development of resistive-switching memories that utilize MIM diodes as the active element. Electroforming of Al-Al{sub 2}O{sub 3}-Ag diodes in vacuum results in voltage-controlled negative resistance (VCNR) in the current-voltage (I-V) characteristics. Electroluminescence (EL) and electron emission into vacuum (EM) develop simultaneously with the current increase that results in VCNR in the I-V characteristics. EL is due to recombination of electrons injected at the Al-Al{sub 2}O{sub 3} interface with radiative defect centers in Al{sub 2}O{sub 3}. Measurements of EL photons between 1.8 eV and 3.0 eV using a wide band-pass filter showed that EL intensity is exponentially dependent on Al{sub 2}O{sub 3} thickness for Al-Al{sub 2}O{sub 3}-Ag diodes between 12 nm and 20 nm thick. Enhanced El intensity in the thinnest diodes is attributed to an increase in the spontaneous emission rate of recombination centers due to high electromagnetic fields generated in Al{sub 2}O{sub 3} when EL photons interact with electrons in Ag or Al to form surface plasmon polaritons at the Al{sub 2}O{sub 3}-Ag or Al{sub 2}O{sub 3}-Al interface. El intensity is a maximum at 2.0–2.2 eV for Al-Al{sub 2}O{sub 3}-Ag diodes with Al{sub 2}O{sub 3} thicknesses between 12 nm and 18 nm. EL in diodes with 12 nm or 14 nm of Al{sub 2}O{sub 3} is enhanced by factors of 8–10 over EL from a diode with 18 nm of Al{sub 2}O{sub 3}. The extent of EL enhancement in

  17. Reduced Deep Root Hydraulic Redistribution Due to Climate Change Impacts Carbon and Water Cycling in Southern US Pine Plantations

    NASA Astrophysics Data System (ADS)

    Domec, J.; Noormets, A.; King, J. S.; Sun, G.; McNulty, S.; Gavazzi, M. J.; Treasure, E.; Caldwell, P.

    2010-12-01

    It is well known that plants lose water from the canopy through transpiration, and also lose a portion of water drawn up at night from deep, moist soil layers through roots and deposited to shallow, dry soil layers. This process is termed hydraulic redistribution (HR). Deep root water uptake and HR have been a major discovery during the last 15 years, but little is known about the impact of future climatic and environmental conditions on deep root water uptake and its impact on water balance and carbon sequestration. We investigated the temporal variability of soil moisture dynamics in three AmeriFlux sites and used data from the Duke Free-Air CO2 Enrichment site to forecast future environmental impacts on HR and its impact on water cycling and carbon sequestration. Our results showed that HR played a critical role in delaying the drying of upper soil layers by replacing more than 25% of the water utilized during the day with water taken up by deep roots at night. Furthermore, HR mitigated the effects of soil drying in the understory and had important implications for net primary productivity and carbon sink potential of young plantations. A warming climate is associated with higher vapor pressure deficits, which will increase nighttime evapotranspiration and reduce HR because trees will act as a competitor with the upper soil for water. We predicted that increases in temperature, vapor pressure deficit and CO2 would reduce HR and limit shallow soil rewetting, thus decreasing net ecosystem productivity (NEP) especially in young and in shallow rooted forest plantations. Modeled carbon flux showed that in the absence of HR, gross ecosystem productivity (GEP) would be reduced by more than 30%, or 200 g C m-2 yr-1 and 750 g C m-2 yr-1 in a young and in a mid-rotation plantation, respectively. HR-induced decrease of GEP outweighed the decrease of ecosystem respiration, thus leading to a lower NEP. For these two types of managed forests, NEP would also be reduced by 100

  18. Mitigation of antagonistic effects on plant growth due to root co-colonization by dark septate endophytes and ectomycorrhiza.

    PubMed

    Reininger, Vanessa; Sieber, Thomas N

    2013-12-01

    Dark septate endophytes (DSE) are very common root colonizers of woody plant species. Ascomycetes of the Phialocephala fortinii s.l.-Acephala applanata species complex (PAC) are the main representatives of DSE fungi in forest ecosystems. PAC and mycorrhizal fungi share the same habitat, but interactions among PAC, mycorrhizal fungi and plants are poorly understood. We compared the effects of single and dual inoculation of Norway spruce seedlings with PAC and the ectomycorrhizal (ECM) fungus Hebeloma crustuliniforme on host growth, degree of mycorrhization and density of endophytic PAC biomass. Single colonization by H. crustuliniforme or PAC significantly reduced plant biomass. Dual colonization reduced or neutralized plant growth depression caused by single fungal colonization. The degree of mycorrhization was independent on PAC colonization, and mycorrhization significantly reduced endophytic PAC biomass. Plant biomass of dually colonized plants positively correlated with PAC biomass. These results demonstrate the ability of dual inoculation of PAC and H. crustuliniforme to neutralize plant growth depression caused by single fungal inoculation. Our explanations of enhanced plant growth in dually inoculated plants are the inhibition of PAC during root colonization by the ECM mantle and ECM-mediated access to plant growth-promoting nutrients resulting from the mineralization of the potting medium by PAC. PMID:24249297

  19. Properties of a new type Al/Pb-0.3%Ag alloy composite anode for zinc electrowinning

    NASA Astrophysics Data System (ADS)

    Yang, Hai-tao; Liu, Huan-rong; Zhang, Yong-chun; Chen, Bu-ming; Guo, Zhong-cheng; Xu, Rui-dong

    2013-10-01

    An Al/Pb-0.3%Ag alloy composite anode was produced via composite casting. Its electrocatalytic activity for the oxygen evolution reaction and corrosion resistance was evaluated by anodic polarization curves and accelerated corrosion test, respectively. The microscopic morphologies of the anode section and anodic oxidation layer during accelerated corrosion test were obtained by scanning electron microscopy. It is found that the composite anode (hard anodizing) displays a more compact interfacial combination and a better adhesive strength than plating tin. Compared with industrial Pb-0.3%Ag anodes, the oxygen evolution overpotentials of Al/Pb-0.3%Ag alloy (hard anodizing) and Al/Pb-0.3%Ag alloy (plating tin) at 500 A·m-2 were lower by 57 and 14 mV, respectively. Furthermore, the corrosion rates of Pb-0.3%Ag alloy, Al/Pb-0.3%Ag alloy (hard anodizing), and Al/Pb-0.3%Ag alloy (plating tin) were 13.977, 9.487, and 11.824 g·m-2·h-1, respectively, in accelerated corrosion test for 8 h at 2000 A·m-2. The anodic oxidation layer of Al/Pb-0.3%Ag alloy (hard anodizing) is more compact than Pb-0.3%Ag alloy and Al/Pb-0.3%Ag alloy (plating tin) after the test.

  20. Inhibition of tomato (Solanum lycopersicum L.) root growth by cyanamide is due to altered cell division, phytohormone balance and expansin gene expression.

    PubMed

    Soltys, Dorota; Rudzińska-Langwald, Anna; Gniazdowska, Agnieszka; Wiśniewska, Anita; Bogatek, Renata

    2012-11-01

    Cyanamide (CA) has been reported as a natural compound produced by hairy vetch (Vicia villosa Roth.) and it was shown also to be an allelochemical, responsible for strong allelopathic potential in this species. CA phytotoxicity has been demonstrated on various plant species, but to date little is known about its mode of action at cellular level. Treatment of tomato (Solanum lycopersicum L.) roots with CA (1.2 mM) resulted in inhibition of growth accompanied by alterations in cell division, and imbalance of plant hormone (ethylene and auxin) homeostasis. Moreover, the phytotoxic effect of CA was also manifested by modifications in expansin gene expression, especially in expansins responsible for cell wall remodeling after the cytokinesis (LeEXPA9, LeEXPA18). Based on these results the phytotoxic activity of CA on growth of roots of tomato seedlings is likely due to alterations associated with cell division. PMID:22847024

  1. ITO-free flexible organic photovoltaics with multilayer MoO3/LiF/MoO3/Ag/MoO3 as the transparent electrode

    NASA Astrophysics Data System (ADS)

    Chen, Shilin; Dai, Yunjie; Zhao, Dewei; Zhang, Hongmei

    2016-05-01

    We present efficient flexible organic photovoltaics (OPVs) with multiple layers of molybdenum oxide (MoO3)/LiF/MoO3/Ag/MoO3 as the transparent electrode, where the thin Ag layer yields high conductivity and the dielectric layer MoO3/LiF/MoO3 has high transparency due to optical interference, leading to improved power conversion efficiency compared with indium tin oxide (ITO) based devices. The MoO3 contacting organic active layer is used as a buffer layer for good hole extraction. Thus, the multilayer MoO3/LiF/MoO3/Ag/MoO3 can improve light transmittance and also facilitate charge carrier extraction. Such an electrode shows excellent mechanical bendability with a 9% reduction of efficiency after 1000 cycles of bending due to the ductile nature of the thin metal layer and dielectric layer used. Our results suggest that the MoO3/LiF/MoO3/Ag/MoO3 multilayer electrode is a promising alternative to ITO as an electrode in OPVs.

  2. Composition-Dependent Luminescent Properties of GeO2-Eu2O3-Ag Films

    NASA Astrophysics Data System (ADS)

    Bokshyts, Yu. V.

    2013-05-01

    An effect of Eu3+-precursor on the luminescent properties of GeO2-Eu2O3-Ag films was studied. This effect can be attributed to the different phase compositions of europium compounds after heat treatment and the change of structural parameters of the environment for europium ions.

  3. Highly active WO3-Ag-ZnO photocatalyst driven by day light illumination

    NASA Astrophysics Data System (ADS)

    Subash, B.; Krishnakumar, B.; Sreedhar, B.; Swaminathan, M.; Shanthi, M.

    2013-02-01

    The WO3 loaded Ag-ZnO (WO3-Ag-ZnO) was successfully synthesized by precipitation-decomposition method. The catalyst was characterized by X-ray diffraction (XRD), field emission scanning electron microscope (FE-SEM) images, energy dispersive spectrum (EDS), transmission electron microscope (TEM), diffuse reflectance spectra (DRS), photoluminescence spectra (PL), cyclic voltammetry (CV) and BET surface area measurements. The photocatalytic activity of WO3-Ag-ZnO was investigated for the degradation of Naphthol Blue Black (NBB) in aqueous solution using solar light. WO3-Ag-ZnO is found to be more efficient than Ag-ZnO, WO3-ZnO, Ag-WO3, WO3, commercial ZnO, bare ZnO, TiO2-P25 and TiO2 (Merck) at pH 9 for the mineralization of NBB dye. The effects of operational parameters such as the amount of photocatalyst, dye concentration, initial pH on photo mineralization of NBB dye have been analyzed. The mineralization of NBB has been confirmed by Chemical Oxygen Demand (COD) measurements. A degradation mechanism is proposed for the degradation of NBB under solar light. This catalyst is found to be reusable.

  4. Alterations of physiology and gene expression due to long-term magnesium-deficiency differ between leaves and roots of Citrus reticulata.

    PubMed

    Jin, Xiao-Lin; Ma, Cui-Lan; Yang, Lin-Tong; Chen, Li-Song

    2016-07-01

    Seedlings of Ponkan (Citrus reticulata) were irrigated with nutrient solution containing 0 (Mg-deficiency) or 1mM MgSO4 (control) every two day for 16 weeks. Thereafter, we examined magnesium (Mg)-deficiency-induced changes in leaf and root gas exchange, total soluble proteins and gene expression. Mg-deficiency lowered leaf CO2 assimilation, and increased leaf dark respiration. However, Mg-deficient roots had lower respiration. Total soluble protein level was not significantly altered by Mg-deficiency in roots, but was lower in Mg-deficient leaves than in controls. Using cDNA-AFLP, we obtained 70 and 71 differentially expressed genes from leaves and roots. These genes mainly functioned in signal transduction, stress response, carbohydrate and energy metabolism, cell transport, cell wall and cytoskeleton metabolism, nucleic acid, and protein metabolisms. Lipid metabolism (Ca(2+) signals)-related Mg-deficiency-responsive genes were isolated only from roots (leaves). Although little difference existed in the number of Mg-deficiency-responsive genes between them both, most of these genes only presented in Mg-deficient leaves or roots, and only four genes were shared by them both. Our data clearly demonstrated that Mg-deficiency-induced alterations of physiology and gene expression greatly differed between leaves and roots. In addition, we focused our discussion on the causes for photosynthetic decline in Mg-deficient leaves and the responses of roots to Mg-deficiency. PMID:27163764

  5. Crystal structures of the La 3AgSnSe 7 and R3Ag 1-δSnS 7 ( R=La, Ce; δ=0.18-0.19) compounds

    NASA Astrophysics Data System (ADS)

    Daszkiewicz, M.; Gulay, L. D.; Pietraszko, A.; Shemet, V. Ya.

    2007-07-01

    The crystal structures of new quaternary compounds La 3AgSnSe 7 (space group P6 3, Pearson symbol hP24, a=1.0805(4) nm, c=0.6245(1) nm, R1=0.0315), La 3Ag 0.82SnS 7 (space group P6 3, Pearson symbol hP23.64, a=1.0399(1) nm, c=0.6016(1) nm, R1=0.0149) and Ce 3Ag 0.81SnS 7 (space group P6 3, Pearson symbol hP23.62, a=1.0300(1) nm, c=0.6002(1) nm, R1=0.0151) were determined by means of X-ray single crystal diffraction. Structural investigations of the R3Ag 1-δSnS 7 ( R=La, Ce; δ=0.18-0.19(1)) compounds at 450 and 530 K were performed. Low temperature data (12 K) for Ce 3Ag 0.81SnS 7 were also collected. The nearest neighbours of the La(Ce), Ag and Sn atoms are exclusively Se(S) atoms. The latter form distorted trigonal prisms around the La(Ce) atoms, and distorted tetrahedrons around the Sn atoms. The Ag (Ag1) atoms have triangular surroundings: they are located very close to the planes built of three Se(S) atoms. The Ag2 atoms in the structures of the La 3Ag 0.82SnS 7, Ce 3Ag 0.81SnS 7 compounds are located practically in the centres of trigonal antiprisms. The pseudo-potentials determined through the Ag atoms show relatively low barrier between two nearest positions which decreases when temperature rises.

  6. Si(111)-( 3× 3)-Ag surface at low temperatures: symmetry breaking and surface twin boundaries

    NASA Astrophysics Data System (ADS)

    Sato, N.; Nagao, T.; Hasegawa, S.

    1999-11-01

    In contrast to the honeycomb pattern observed at room temperature in empty-state scanning-tunneling-microscopy (STM) images corresponding to the generally accepted honeycomb-chained-triangle (HCT) structure, the Si(111)- ( 3× 3)-Ag surface at low temperatures (62 and 6 K) shows a hexagonal-lattice pattern. This is consistent with an 'inequivalent-triangle (IET) model' recently proposed as the most stable structure for the ( 3× 3)-Ag surface in which two Ag triangles in the unit cell are different in size. Because of the asymmetry of the IET structure, two types of domains whose structures are in the relation of twins to each other are created only at low temperatures, between which surface twin boundaries (TB) appear. The neighboring domains, separated by a conventional out-of-phase boundary (OPB), tend to have the IET structures of the opposite symmetry. The interaction between the OPB and TB is discussed. The TB is observed to fluctuate and to be pinned by some defects.

  7. Visible-light-driven photocatalytic inactivation of Escherichia coli by magnetic Fe2O3-AgBr.

    PubMed

    Ng, Tsz Wai; Zhang, Lisha; Liu, Jianshe; Huang, Guocheng; Wang, Wei; Wong, Po Keung

    2016-03-01

    Bacterial inactivation by magnetic photocatalyst receives increasing interests for the ease recovery and reuse of photocatalysts. This study investigated bacterial inactivation by a magnetic photocatalysts, Fe2O3-AgBr, under the irradiation of a commercially available light emitting diode lamp. The effects of different factors on the inactivation of Escherichia coli were also evaluated, in term of the efficiency in inactivation. The results showed that Fe2O3-AgBr was able to inactivate both Gram negative (E. coli) and Gram positive (Staphylococcus aureus) bacteria. Bacterial inactivation by Fe2O3-AgBr was more favorable under high temperature and alkaline pH. Presence of Ca(2+) promoted the bacterial inactivation while the presence of [Formula: see text] was inhibitory. The mechanisms of photocatalytic bacterial inactivation were systemically studied and the effects of the presence of various specific reactive species scavengers and argon suggest that Fe2O3-AgBr inactivate bacterial cells by the oxidation of H2O2 generated from the photo-generated electron and direct oxidation of photo-generated hole. The detection of different reactive species further supported the proposed mechanisms. The results provide information for the evaluation of bacterial inactivation performance of Fe2O3-AgBr under different conditions. More importantly, bacterial inactivation for five consecutive cycles demonstrated Fe2O3-AgBr exhibited highly stable bactericidal activity and suggest that the magnetic Fe2O3-AgBr has great potential for water disinfection. PMID:26724445

  8. Electroforming and Ohmic contacts in Al-Al2O3-Ag diodes

    NASA Astrophysics Data System (ADS)

    Hickmott, T. W.

    2012-03-01

    Electroforming of metal-insulator-metal (MIM) diodes is a non-destructive dielectric breakdown process that changes the diode from its initial high resistance state (HRS) to a low resistance state (LRS). After electroforming, resistance switching memories (RSMs) use voltages to switch from HRS to LRS and back. Many MIM combinations are proposed for use in RSMs. In many cases conduction in the LRS is nearly temperature independent at low temperatures; an Ohmic contact with a barrier to electron injection of ˜0 eV results from electroforming. Electroforming of Al-Al2O3-Ag diodes with amorphous anodic Al2O3 thicknesses between 12 and 41 nm has been studied. Two anodizing electrolytes have been used; 0.1 M ammonium pentaborate (bor-H2O) and a solution of 0.1 M of ammonium pentaborate per liter of ethylene glycol (bor-gly). Polarization of Al2O3 and negative charge in Al2O3 are much larger when Al2O3 is formed in bor-H2O solution than when Al is anodized in bor-gly solution. Electroforming of Al-Al2O3-Ag diodes results in an Ohmic contact at the Al-Al2O3 interface, voltage-controlled negative resistance (VCNR) in the current-voltage (I-V) characteristics, electroluminescence (EL), and electron emission into vacuum (EM) from filamentary conducting channels. Two distinct modes of electroforming occur for Al-Al2O3-Ag diodes. α-forming occurs for 2.5 V ≲ VS ≲ 5 V, where VS is the applied voltage. It is characterized by an abrupt current jump with the simultaneous appearance of EL and EM. β-forming occurs for VS ≳ 7 V. I-V curves, EL, and EM develop gradually and are smaller than for α-forming. Electroforming occurs more readily for diodes with Al2O3 formed in bor-H2O that have greater defect densities. Fully developed I-V curves have similar VCNR, EL, and EM after α-forming or β-forming. A model is proposed in which excited states of F-centers, oxygen vacancies in amorphous anodic Al2O3, form defect conduction bands. Electroforming that results in an Ohmic

  9. Heterogeneity and topsoil depletion due to tillage erosion and soil co-extraction with root vegetables: a serious threat to sustainable agricultural land use in the UK

    NASA Astrophysics Data System (ADS)

    Quine, Timothy; van Oost, Kristof

    2010-05-01

    The term soil erosion has become almost synonymous with water erosion and yet tillage erosion and soil loss with root crop harvest, although less visible, may be responsible for the majority of the on-site costs of soil erosion in many arable areas of the UK. The study reported here is a first attempt to model soil erosion associated with these processes in England and Wales, at the National scale. A GIS-based modelling approach in the Arc/Info environment is employed in order to meet the requirement for large-scale evaluation of erosion severity. Existing models that have been subject to independent test are used or adapted and widely available data is employed in model parameterisation. Tillage erosion is simulated using a diffusion-type model and a slope curvature index derived from coarse-scale topographic data. The curvature index is calibrated by statistical comparison to curvature values derived from a high resolution digital terrain model. Soil loss with root crop harvest is simulated using information concerning patterns of sugar beet and potato cultivation and estimation of soil moisture during the crop harvest season. Soil loss associated with root crop harvest may be as high as 1 t ha-1 year-1 if land is permanently used for root crops in a 3 year rotation. However, when the arable area of the UK is considered as a whole root crop harvest is responsible for a mean rate of soil loss of approximately 0.1 t ha-1 year-1. Tillage erosion is found to be the dominant process of soil redistribution and onsite erosion on arable land, in comparison with both soil loss through root crop harvest and with long-term water erosion rates. Mean gross rates of tillage erosion were found to be 3.7 t ha-1 year-1, representing approximately 7.4 t ha-1 year-1 erosion and the same rate of deposition. Soil redistribution at these rates is generating an heterogeneous soilscape in which continued functioning for food and fibre production may be jeopardized. These problems may be

  10. The fabrication of In2O3/In2S3/Ag nanocubes for efficient photoelectrochemical water splitting.

    PubMed

    Xu, Rui; Li, Haohua; Zhang, Wenwen; Yang, Zepeng; Liu, Guiwu; Xu, Ziwei; Shao, Haicheng; Qiao, Guanjun

    2016-01-28

    In this work, for the first time, a three-component In2O3/In2S3/Ag nanocomposite heterostructured photoanode is prepared on a F-doped SnO2 (FTO) glass substrate. The three-component photoanode exhibits significantly enhanced photoelectrochemical properties compared with the single-component (In2O3) and two-component (In2O3/In2S3 or In2O3/Ag) systems. Ag nanoparticles deposited on the surface of In2O3/In2S3 nanocubes can facilitate the separation of photogenerated charge carriers and enhance the absorption of visible light. In I-V curves, the In2O3/In2S3/Ag photoanode generates a remarkable photocurrent density of 8.75 mA cm(-2) (at 0 V vs. SCE), which is higher than those of the two-component In2O3/In2S3 (4.47 mA cm(-2)) and In2O3/Ag (3.50 mA cm(-2)). Furthermore, it also gives efficiency as high as 67% around 350 nm in the incident photon to electron conversion efficiency (IPCE) spectrum. These results open up a promising avenue for the design and fabrication of novel heterojunctions for photoelectrochemical water splitting. PMID:26725370

  11. The inhibitory effect of a Platycodon root extract on ultraviolet B-induced pigmentation due to a decrease in Kit expression.

    PubMed

    Kasamatsu, Shinya; Hachiya, Akira; Shimotoyodome, Yoshie; Kameyama, Akiyo; Miyauchi, Yuki; Higuchi, Kazuhiko; Fujimori, Taketoshi; Ohuchi, Atsushi; Shibuya, Yusuke; Kitahara, Takashi

    2014-07-01

    The signaling of stem cell factor (SCF) through its receptor Kit is known to play an important role in regulating cutaneous melanogenesis. In the course of UVB-induced pigmentation, the expression of membrane-bound SCF by epidermal keratinocytes is upregulated at an early phase and subsequently activates neighboring melanocytes via their Kit receptors. In order to identify effective skin-lightening materials, we screened botanical extracts to determine their abilities to diminish Kit expression in melanocytes. A Platycodon root extract was consequently found to have a remarkable inhibitory activity on Kit expression. When the extract was applied to three-dimensional human skin substitutes in vitro and to human skin in vivo after UVB irradiation, their pigmentation was significantly reduced, confirming the substantial contribution of the suppression of SCF/Kit signaling to preventing or inhibiting melanin synthesis. These data demonstrate that a Platycodon root extract is a promising material for a skin-lightening product to improve pigmentation-related diseases. PMID:24799080

  12. Roots Revisited.

    ERIC Educational Resources Information Center

    Hughes, Barnabas

    1998-01-01

    Offers historical information about square roots. Presents three different methods--Hero's method, visual method, and remainder method--which can be used to teach the finding of square roots and one method for determining cube roots. (ASK)

  13. Flooding impairs Fe uptake and distribution in Citrus due to the strong down-regulation of genes involved in Strategy I responses to Fe deficiency in roots.

    PubMed

    Martínez-Cuenca, Mary-Rus; Quiñones, Ana; Primo-Millo, Eduardo; Forner-Giner, M Ángeles

    2015-01-01

    This work determines the ffects of long-term anoxia conditions--21 days--on Strategy I responses to iron (Fe) deficiency in Citrus and its impact on Fe uptake and distribution. The study was carried out in Citrus aurantium L. seedlings grown under flooding conditions (S) and in both the presence (+Fe) and absence of Fe (-Fe) in nutritive solution. The results revealed a strong down-regulation (more than 65%) of genes HA1 and FRO2 coding for enzymes proton-ATPase and Ferric-Chelate Reductase (FC-R), respectively, in -FeS plants when compared with -Fe ones. H+-extrusion and FC-R activity analyses confirmed the genetic results, indicating that flooding stress markedly repressed acidification and reduction responses to Fe deficiency (3.1- and 2.0-fold, respectively). Waterlogging reduced by half Fe concentration in +FeS roots, which led to 30% up-regulation of Fe transporter IRT1, although this effect was unable to improve Fe absorption. Consequently, flooding inhibited 57Fe uptake in +Fe and -Fe seedlings (29.8 and 66.2%, respectively) and 57Fe distribution to aerial part (30.6 and 72.3%, respectively). This evidences that the synergistic action of both enzymes H+-ATPase and FC-R is the preferential regulator of the Fe acquisition system under flooding conditions and, hence, their inactivation implies a limiting factor of citrus in their Fe-deficiency tolerance in waterlogged soils. PMID:25897804

  14. Potential for post-closure radionuclide redistribution due to biotic intrusion: aboveground biomass, litter production rates, and the distribution of root mass with depth at material disposal area G, Los Alamos National Laboratory

    SciTech Connect

    French, Sean B; Christensen, Candace; Jennings, Terry L; Jaros, Christopher L; Wykoff, David S; Crowell, Kelly J; Shuman, Rob

    2008-01-01

    Low-level radioactive waste (LLW) generated at the Los Alamos National Laboratories (LANL) is disposed of at LANL's Technical Area (T A) 54, Material Disposal Area (MDA) G. The ability of MDA G to safely contain radioactive waste during current and post-closure operations is evaluated as part of the facility's ongoing performance assessment (PA) and composite analysis (CA). Due to the potential for uptake and incorporation of radio nuclides into aboveground plant material, the PA and CA project that plant roots penetrating into buried waste may lead to releases of radionuclides into the accessible environment. The potential amount ofcontamination deposited on the ground surface due to plant intrusion into buried waste is a function of the quantity of litter generated by plants, as well as radionuclide concentrations within the litter. Radionuclide concentrations in plant litter is dependent on the distribution of root mass with depth and the efficiency with which radionuclides are extracted from contaminated soils by the plant's roots. In order to reduce uncertainties associated with the PA and CA for MDA G, surveys are being conducted to assess aboveground biomass, plant litter production rates, and root mass with depth for the four prominent vegetation types (grasses, forbs, shrubs and trees). The collection of aboveground biomass for grasses and forbs began in 2007. Additional sampling was conducted in October 2008 to measure root mass with depth and to collect additional aboveground biomass data for the types of grasses, forbs, shrubs, and trees that may become established at MDA G after the facility undergoes final closure, Biomass data will be used to estimate the future potential mass of contaminated plant litter fall, which could act as a latent conduit for radionuclide transport from the closed disposal area. Data collected are expected to reduce uncertainties associated with the PA and CA for MDA G and ultimately aid in the assessment and subsequent

  15. Redox Imbalance in the Peripheral Mechanism Underlying the Mirror-Image Neuropathic Pain Due to Chronic Compression of Dorsal Root Ganglion.

    PubMed

    Lv, H; Chen, H; Xu, J J; Jiang, Y S; Shen, Y J; Zhou, S Z; Xu, H; Xiong, Y C

    2016-05-01

    Reactive oxygen species (ROS) play a critical role in the pathogenesis of neuropathic pain, but few studies have examined the role of oxidative stress in the mirror-image neuropathic pain (MINP). The present study was to investigate the role of ROS in MINP caused by chronic compression of the dorsal root ganglion (DRG) (CCD) in a rat model. SD rats were randomly divided into sham group and CCD group. CCD was conducted to induce MINP. CCD rats were intraperitoneally injected with α-Phenyl-N-tert-butyl-nitrone (PBN) at 7 days after surgery. Paw withdrawal mechanical threshold (PWMT) was measured at -1, 1, 3, 5 and 7 days after surgery in sham group and CCD group, and at 8 time points after PBN injection. Rats were sacrificed at 3 and 7 days after surgery in sham group and CCD group and at 0.5 and 2 h after PBN injection, and the superoxide dismutase (SOD) and catalase activities, as well as hydrogen peroxide (H2O2) and malonaldehyde (MDA) contents were determined in the contralateral DRGs. Results showed bilateral PWMT reduced significantly in sham group and CCD group, but it returned to nearly normal level in sham group. MDA content, H2O2 content and SOD activity increased significantly, while catalase activity remained unchanged in CCD rats. PBN at 100 mg/kg significantly attenuated bilateral mechanical hyperalgesia accompanied by the improvement of oxidative stress in the contralateral DRGs. Our results demonstrate that ROS produced in the contralateral DRG are involved in the pathogenesis of CCD induced MINP, and ROS scavenger may be a promising drug for the therapy of MINP. PMID:26471165

  16. Flooding Impairs Fe Uptake and Distribution in Citrus Due to the Strong Down-Regulation of Genes Involved in Strategy I Responses to Fe Deficiency in Roots

    PubMed Central

    Martínez-Cuenca, Mary-Rus; Quiñones, Ana; Primo-Millo, Eduardo; Forner-Giner, M. Ángeles

    2015-01-01

    This work determines the ffects of long-term anoxia conditions—21 days—on Strategy I responses to iron (Fe) deficiency in Citrus and its impact on Fe uptake and distribution. The study was carried out in Citrus aurantium L. seedlings grown under flooding conditions (S) and in both the presence (+Fe) and absence of Fe (-Fe) in nutritive solution. The results revealed a strong down-regulation (more than 65%) of genes HA1 and FRO2 coding for enzymes proton-ATPase and Ferric-Chelate Reductase (FC-R), respectively, in –FeS plants when compared with –Fe ones. H+-extrusion and FC-R activity analyses confirmed the genetic results, indicating that flooding stress markedly repressed acidification and reduction responses to Fe deficiency (3.1- and 2.0-fold, respectively). Waterlogging reduced by half Fe concentration in +FeS roots, which led to 30% up-regulation of Fe transporter IRT1, although this effect was unable to improve Fe absorption. Consequently, flooding inhibited 57Fe uptake in +Fe and –Fe seedlings (29.8 and 66.2%, respectively) and 57Fe distribution to aerial part (30.6 and 72.3%, respectively). This evidences that the synergistic action of both enzymes H+-ATPase and FC-R is the preferential regulator of the Fe acquisition system under flooding conditions and, hence, their inactivation implies a limiting factor of citrus in their Fe-deficiency tolerance in waterlogged soils. PMID:25897804

  17. Quantitative measurements of root water uptake and root hydraulic conductivities

    NASA Astrophysics Data System (ADS)

    Zarebanadkouki, Mohsen; Javaux, Mathieu; Meunier, Felicien; Couvreur, Valentin; Carminati, Andrea

    2016-04-01

    uptake by laterals decreased towards the root tips due to a dissipation of water potential along the root and it had a maximum at a distance of 10 cm from the root tip; (3) water uptake by the taproot was higher in the distal segments and was negligible in the proximal parts, which had a low radial conductivity. The method introduced here enabled us to reconstruct the water fluxes and the profile of hydraulic conductivities of a root system. This method can help to better understand root development and function in response to varying soil conditions. The method can also be used to calibrate and test existing models of root water uptake.

  18. HCV NS3Ag: a reliable and clinically useful predictor of antiviral outcomes in genotype 1b hepatitis C virus-infected patients.

    PubMed

    Ren, S; Jin, Y; Huang, Y; Ma, L; Liu, Y; Meng, C; Guan, S; Xie, L; Chen, X

    2016-07-01

    Since hepatitis C virus (HCV) non-structural 3 (NS3) protease inhibitor (PI) combined with pegylated interferon/ribavirin (PR) has been approved for chronic HCV genotype (GT) 1b infection, a reliable and clinically useful predictor combining with serum HCV RNA to predict early virologic response, breakthrough, and relapse is important during HCV antiviral treatment. We evaluated the role of HCV NS3 antigen (HCV NS3Ag) on the prediction of virologic response in patients with HCV GT1b during PR or PR/simeprevir (triple) therapy. Three hundred patients were recruited, and HCV RNA and HCV NS3Ag were tested at baseline and weeks 2, 4, 12, 24, 48, and 72. NS3Ag and HCV RNA were significantly related (r(2) = 0.67) in the whole patient selection. The kinetic pattern of HCV RNA and HCV NS3Ag during triple treatment was similar. HCV NS3Ag levels in the triple group closely followed those of HCV RNA; the r(2) values were 0.756 (baseline), 0.837 (2 weeks), 0.989 (4 weeks), and 0.993 (12 weeks), respectively. For patients treated with PR, the positive and negative predictive values (PPVs and NPVs) for viral response were 96.31 % and 67.19 %, respectively, at week 4 by using the decrease of NS3Ag (dHCV NS3Ag) combined with HCV RNA. At week 12, the PPV was similar at 94.16 %, while the NPV reached 87.26 %. The PPV and NPV for the prediction of relapse and breakthrough were 90.6 % and 76.7 %, respectively. HCV NS3Ag is a valuable marker and could be a supplementary predictor of HCV RNA for the prediction of antiviral response, breakthrough, or relapse during HCV antiviral treatment. PMID:27173787

  19. Modeling root reinforcement using root-failure Weibull survival function

    NASA Astrophysics Data System (ADS)

    Schwarz, M.; Giadrossich, F.; Cohen, D.

    2013-03-01

    Root networks contribute to slope stability through complicated interactions that include mechanical compression and tension. Due to the spatial heterogeneity of root distribution and the dynamic of root turnover, the quantification of root reinforcement on steep slope is challenging and consequently the calculation of slope stability as well. Although the considerable advances in root reinforcement modeling, some important aspect remain neglected. In this study we address in particular to the role of root strength variability on the mechanical behaviors of a root bundle. Many factors may contribute to the variability of root mechanical properties even considering a single class of diameter. This work presents a new approach for quantifying root reinforcement that considers the variability of mechanical properties of each root diameter class. Using the data of laboratory tensile tests and field pullout tests, we calibrate the parameters of the Weibull survival function to implement the variability of root strength in a numerical model for the calculation of root reinforcement (RBMw). The results show that, for both laboratory and field datasets, the parameters of the Weibull distribution may be considered constant with the exponent equal to 2 and the normalized failure displacement equal to 1. Moreover, the results show that the variability of root strength in each root diameter class has a major influence on the behavior of a root bundle with important implications when considering different approaches in slope stability calculation. Sensitivity analysis shows that the calibration of the tensile force and the elasticity of the roots are the most important equations, as well as the root distribution. The new model allows the characterization of root reinforcement in terms of maximum pullout force, stiffness, and energy. Moreover, it simplifies the implementation of root reinforcement in slope stability models. The realistic quantification of root reinforcement for

  20. Supramolecular structures of halogenated oligothiophenes on the Si(111)-√3 ×√3-Ag surface

    NASA Astrophysics Data System (ADS)

    Liu, R.; Fu, C.; Perepichka, D. F.; Gallagher, M. C.

    2016-05-01

    We have studied the adsorption of brominated tetrathienoanthracene (TBTTA) molecules onto the Si(111)-√3 × √ 3-Ag surface at room temperature. The two-dimensional √ 3 silver adlayer acts to passivate the silicon surface and provides a high-mobility template for TBTTA adsorption. Scanning tunneling microscopy (STM) images reveal that at low coverage, the molecules readily migrate to step edges and defects in the √ 3 overlayer. With increasing coverage, the molecules eventually form compact supramolecular structures. In terms of the hexagonal √ 3 lattice vectors (a√ 3 and b√ 3), the oblique unit cell of these structures can be defined by lattice vectors am = 3a√ 3 + 2b√ 3, and bm = - a√ 3 + b√ 3. The structures are quite fragile and can decompose under repeated STM imaging. This is particularly true at higher bias and suggests an electric field-induced dissociation in these instances. With increasing molecular dose, the size and stability of the structures increases. At higher coverage, the spatial extent of the supramolecular structures is often limited by defects in the underlying √ 3 layer. Our results suggest that the √ 3-Ag surface provides a relatively inert substrate for the adsorption of TBTTA molecules, and that the supramolecular structures are held together by relatively weak intermolecular forces.

  1. The change of coverage and structure of the Si(111)-√3 × √3-Ag surface by isothermal annealing

    NASA Astrophysics Data System (ADS)

    Ishigami, Ryoya; Yuhara, Junji; Morita, Kenji

    1994-12-01

    The thermal stability of the Si(111)-√3 × √3-Ag surface has been studied by means of low energy electron diffraction, Auger electron spectroscopy, and Rutherford backscattering spectrometry techniques. The initial coverages of Ag, which was deposited on the Si(111)-7 × 7 surface at room temperature, are 0.8-1.0 ML ( 1 ML = 7.84 × 10 14{atoms}/{cm 2}). It is found that on isothermal annealing the coverage of Ag decreases exponentially with increasing time when only the √3 × √3 spots continue to be observed and that the Ag coverage shifts to another slower exponential function at about 0.5 ML, at which the 3 × 1 spots begin to appear between the √3 × √3 spots. The activation energies for Ag atoms to decay from the Si(111)-√3 × √3-Ag and √3 × √3 + 3 × 1-Ag surfaces are determined from the two exponential decay curves to be 0.89 ± 0.21 and 2.6 ± 0.3 eV, respectively. The experimental values are compared with those obtained by other authors.

  2. Mechanical Properties of Ca0.9Yb0.1MnO3/Ag Composites for n-Type Legs of Thermoelectric Oxide Devices

    NASA Astrophysics Data System (ADS)

    Kosuga, Atsuko; Urata, Saori; Kurosaki, Ken; Yamanaka, Shinsuke; Funahashi, Ryoji

    2008-08-01

    CaMnO3 systems are known to exhibit excellent thermoelectric (TE) performance at high temperature in air and are, therefore, good candidates for the n-type legs of TE oxide devices. In previous studies, however, several CaMnO3 system legs have fractured easily after the power generation test. The fractures were probably caused by the inherently low mechanical strength of CaMnO3, due to which it developed a great thermal stress arising from the big difference in thermal expansion coefficient between the Ag electrode and the CaMnO3 leg. In the present study, Ag particles were dispersed in a Ca0.9Yb0.1MnO3 matrix to mitigate the problems mentioned above. The incorporation of Ag particles into the matrix led to both improvement of the mechanical strength of Ca0.9Yb0.1MnO3 and to reduction in the thermal stress at the junction between the Ag electrode and the Ca0.9Yb0.1MnO3/Ag composite leg. Additionally, the ability of TE oxides to withstand application of a maximum temperature gradient without impairment of their mechanical strength could be significantly improved as a result.

  3. Square Root +

    ERIC Educational Resources Information Center

    Frederiksen, John G.

    1969-01-01

    A rational presentation of the so-called long division method for extracting the square root of a number. Diagrams are used to show relationship of this technique to the binomial theorem. Presentation exposes student to many facets of mathematics in addition to the mechanics of funding square root and cube root. Geometry, algebraic statements,…

  4. Root Hairs

    PubMed Central

    Grierson, Claire; Nielsen, Erik; Ketelaarc, Tijs; Schiefelbein, John

    2014-01-01

    Roots hairs are cylindrical extensions of root epidermal cells that are important for acquisition of nutrients, microbe interactions, and plant anchorage. The molecular mechanisms involved in the specification, differentiation, and physiology of root hairs in Arabidopsis are reviewed here. Root hair specification in Arabidopsis is determined by position-dependent signaling and molecular feedback loops causing differential accumulation of a WD-bHLH-Myb transcriptional complex. The initiation of root hairs is dependent on the RHD6 bHLH gene family and auxin to define the site of outgrowth. Root hair elongation relies on polarized cell expansion at the growing tip, which involves multiple integrated processes including cell secretion, endomembrane trafficking, cytoskeletal organization, and cell wall modifications. The study of root hair biology in Arabidopsis has provided a model cell type for insights into many aspects of plant development and cell biology. PMID:24982600

  5. Synthesis of Strong Light Scattering Absorber of TiO₂-CMK-3/Ag for Photocatalytic Water Splitting under Visible Light Irradiation.

    PubMed

    Hung, Wei Hsuan; Lai, Sz Nian; Lo, An Ya

    2015-04-29

    The enhanced water splitting photocurrent has been observed through plasmonic mesoporous composite electrode TiO2-CMK-3/Ag under visible light irradiation. Strong light absorption achieved from the integrations of ordered mesoporous carbon (CMK-3) and silver plasmonic nanoparticles (NPs) layer in the TiO2, which significantly increased the effective optical depth of TiO2-CMK-3/Ag photoelectrode. The carbon-based CMK-3 also increased the surface wetting behavior and conductivity of the photoelectrodes, which resulted in a higher ion exchange rate and faster electron transport. The synthesis of high crystalline TiO2-CMK-3/Ag composite photocatalyst was verified by X-ray diffraction (XRD) and scanning electron microscopy (SEM). Pronounced enhancement of light absorption of TiO2-CMK-3/Ag photoelectrode was confirmed by UV/vis spectrophotometers. Two orders of magnitude of the enhanced water splitting photocurrent were obtained in the TiO2-CMK-3/Ag composite photoelectrode with respect to TiO2 only. Finally, spatially resolved mapping photocurrents were also demonstrated in this study. PMID:25848834

  6. Adatom-induced variations of the atomic and electronic structures of Si(111)3×3-Ag : A first-principles study

    NASA Astrophysics Data System (ADS)

    Jeong, Hojin; Yeom, Han Woong; Jeong, Sukmin

    2008-06-01

    Using a first-principles calculation method, we study the changes in the atomic and electronic structures of the Si(111)3×3-Ag surface (hereafter 3-Ag ) via doping of extra Ag adatoms. We present a structural model for the adatom-induced 21×21 superstructure (21-Ag) , which has three Ag adatoms immersed into the substrate Ag layer within a unit cell. The present structural model reproduces well the measured scanning-tunneling-microscopy images as well as the electronic band structure measured by angle-resolved photoelectron spectroscopy. We find out that the complex band structure seen on the 21-Ag phase basically arises from the band folding of the original surface bands of 3-Ag . The extra Ag adatoms doped on 3-Ag modify only the band alignment without any additional adatom-induced surface state. The almost unoccupied two-dimensional free-electron-like band, generally called S1 , at pristine 3-Ag is gradually filled and shifted downward with an increase in the dopant coverage. As this shifted S1 band crosses other surface bands, it loses its free-electron nature.

  7. Optical microcavities and enhanced electroluminescence from electroformed Al-Al{sub 2}O{sub 3}-Ag diodes

    SciTech Connect

    Hickmott, T. W.

    2013-12-21

    Electroluminescence (EL) and electron emission into vacuum (EM) occur when a non-destructive dielectric breakdown of Al-Al{sub 2}O{sub 3}-Ag diodes, electroforming, results in the development of a filamentary region in which current-voltage (I-V) characteristics exhibit voltage-controlled negative resistance. The temperature dependence of I-V curves, EM, and, particularly, EL of Al-Al{sub 2}O{sub 3}-Ag diodes with anodic Al{sub 2}O{sub 3} thicknesses between 12 nm and 30 nm, has been studied. Two filters, a long-pass (LP) filter with transmission of photons with energies less than 3.0 eV and a short-pass (SP) filter with photon transmission between 3.0 and 4.0 eV, have been used to characterize EL. The voltage threshold for EL with the LP filter, V{sub LP}, is ∼1.5 V. V{sub LP} is nearly independent of Al{sub 2}O{sub 3} thickness and of temperature and is 0.3–0.6 V less than the threshold voltage for EL for the SP filter, V{sub SP}. EL intensity is primarily between 1.8 and 3.0 eV when the bias voltage, V{sub S} ≲ 7 V. EL in the thinnest diodes is enhanced compared to EL in thicker diodes. For increasing V{sub S}, for diodes with the smallest Al{sub 2}O{sub 3} thicknesses, there is a maximum EL intensity, L{sub MX}, at a voltage, V{sub LMX}, followed by a decrease to a plateau. L{sub MX} and EL intensity at 4.0 V in the plateau region depend exponentially on Al{sub 2}O{sub 3} thickness. The ratio of L{sub MX} at 295 K for a diode with 12 nm of Al{sub 2}O{sub 3} to L{sub MX} for a diode with 25 nm of Al{sub 2}O{sub 3} is ∼140. The ratio of EL intensity with the LP filter to EL intensity with the SP filter, LP/SP, varies between ∼3 and ∼35; it depends on Al{sub 2}O{sub 3} thickness and V{sub S}. Enhanced EL is attributed to the increase of the spontaneous emission rate of a dipole in a non-resonant optical microcavity. EL photons interact with the Ag and Al films to create surface plasmon polaritons (SPPs) at the metal-Al{sub 2}O

  8. A study of the microstructure, thermal properties and wetting kinetics of Sn-3Ag- xZn lead-free solders

    NASA Astrophysics Data System (ADS)

    Li, Yulong; Yu, Xiao; Sekulic, Dusan P.; Hu, Xiaowu; Yan, Ming; Hu, Ronghua

    2016-06-01

    Microstructure, thermal properties and wetting kinetics of Sn-3Ag- xZn solders ( x = 0.4, 0.6, 0.8, 1, 2 and 4 wt%) were systematically investigated. The results indicate that a small amount of Zn (Zn wt% ≤ 1 wt%) has a rather moderate effect on the microstructure morphology of the Sn-3Ag- xZn solders. The microstructures are composed of a β-Sn phase and the mixture of Ag3Sn and ζ-AgZn particles. However, the β-Sn phase reduces its volume fraction in the entire microstructure and the intermetallic compounds population increases with the increasing of Zn content. The microstructure is dramatically changed with a further increase in the Zn content. The γ-AgZn phase is formed in a Sn-3Ag-2Zn solder. The ɛ-AgZn phase is formed in a Sn-3Ag-4Zn solder. The melting temperature and the undercooling of the Sn-3Ag- xZn solder alloys decrease with the increase in Zn content, reach to a minimum value when the content of Zn is 1 wt%, and then increase with further increase in Zn content. The Sn-3Ag-1Zn demonstrates the minimum value of 228.13 °C in the melting temperature and 13.87 °C in undercooling. The wetting kinetics of the main spreading stage features the power law of R n ~ t ( n = 1), which is controlled by chemical reactions at the triple line.

  9. Surfactant role of Ag atoms in the growth of Si layers on Si(111)√3×√3-Ag substrates

    SciTech Connect

    Yamagami, Tsuyoshi; Sone, Junki; Nakatsuji, Kan; Hirayama, Hiroyuki

    2014-10-13

    The growth of Si layers on Si(111)√3×√3-Ag substrates was studied for coverages of up to a few mono-layers. Atomically flat islands were observed to nucleate in the growth at 570 K. The top surfaces of the islands were covered in Ag atoms and exhibited a √3×√3 reconstruction with the same surface state dispersions as Si(111)√3×√3-Ag substrates. These results indicate that the Ag atoms on the substrate always hop up to the top of the Si layers.

  10. Visualization of Thermally Fluctuating Surface Structure in Noncontact Atomic-Force Microscopy and Tip Effects on Fluctuation: Theoretical Study of Si(111)-( √3 ×√3)-Ag Surface

    NASA Astrophysics Data System (ADS)

    Sasaki, Naruo; Watanabe, Satoshi; Tsukada, Masaru

    2002-01-01

    We investigated noncontact atomic-force microscopy (NC-AFM) images of a thermally fluctuating surface structure together with tip effects based on the first-principles electronic state calculation. As an example the Si(111)-( (3)×(3))-Ag ( (3)-Ag) surface is studied. We have succeeded in theoretically visualizing the thermal fluctuation of the (3)-Ag surface at room temperature, and in reproducing the observed NC-AFM image for the first time. Further, the pinning effect of the thermal fluctuation of the (3)-Ag surface by the tip is clarified, which shows a novel ability of NC-AFM to modify the surface structure.

  11. Roots and Root Function: Introduction

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A number of current issues related to water management, ecohydrology, and climate change are giving impetus to new research aimed at understanding roots and their functioning. Current areas of research include: use of advanced imaging technologies such as Magnetic Resonance Imaging to observe roots...

  12. Adsorbate-Induced Segregation in a PdAg Membrane Model System: Pd3Ag(1 1 1)

    SciTech Connect

    Svenum, I. H.; Herron, Jeffrey A.; Mavrikakis, Manos; Venvik, H. J.

    2012-10-15

    Thin PdAg alloy membranes with 20–25% Ag are being developed for hydrogen separation technology. Despite many investigations on such membranes as well as representative experimental and theoretical model systems, unresolved issues remain concerning the effect of the alloy surface structure and composition on adsorption and vice versa. Therefore, the interaction between hydrogen, carbon monoxide or oxygen with the surface of a PdAg model alloy was studied using periodic self-consistent density functional theory (DFT-GGA) calculations. In particular, the adsorption structure, coverage dependence and possible adsorption-induced segregation phenomena were addressed using Pd3Ag(1 1 1) model surfaces with varying degrees of surface segregation. In agreement with previous experimental and theoretical investigations, we predict Ag surface termination to be energetically favorable in vacuum. The segregation of Ag is then reversed upon adsorption of H, CO or O. For these adsorbates, the binding is strongest on Pd three-fold hollow sites, and hence complete Pd termination is favored at high coverage of H or CO, while 25% Ag may remain under oxygen because of the lower O-saturation coverage. CO adsorption provides a somewhat stronger driving force for Pd segregation when compared to H, and this may have implications with respect to permeation properties of PdAg alloy surfaces. Our predictions for high coverage are particularly relevant in underlining the importance of segregation phenomena to the hydrogen transport properties of thin PdAg alloy membranes.

  13. Reactive Sputter Deposition of WO3/Ag/WO3 Film for Indium Tin Oxide (ITO)-Free Electrochromic Devices.

    PubMed

    Yin, Yi; Lan, Changyong; Guo, Huayang; Li, Chun

    2016-02-17

    Functioning both as electrochromic (EC) and transparent-conductive (TC) coatings, WO3/Ag/WO3 (WAW) trilayer film shows promising potential application for ITO-free electrochromic devices. Reports on thermal-evaporated WAW films revealed that these bifunctional WAW films have distinct EC characteristics; however, their poor adhesive property leads to rapid degradation of coloring-bleaching cycling. Here, we show that WAW film with improved EC durability can be prepared by reactive sputtering using metal targets. We find that, by introducing an ultrathin tungsten (W) sacrificial layer before the deposition of external WO3, the oxidation of silver, which leads to film insulation and apparent optical haze, can be effectively avoided. We also find that the luminous transmittance and sheet resistance were sensitive to the thicknesses of tungsten and silver layers. The optimized structure for TC coating was obtained to be WO3 (45 nm)/Ag (10 nm)/W (2 nm)/WO3 (45 nm) with a sheet resistance of 16.3 Ω/□ and a luminous transmittance of 73.7%. Such film exhibits compelling EC performance with decent luminous transmittance modulation ΔTlum of 29.5%, fast switching time (6.6 s for coloring and 15.9 s for bleaching time), and long-term cycling stability (2000 cycles) with an applied potential of ±1.2 V. Thicker external WO3 layer (45/10/2/100 nm) leads to larger modulation with maximum ΔTlum of 46.4%, but at the cost of significantly increasing the sheet resistance. The strategy of introducing ultrathin metal sacrificial layer to avoid silver oxidation could be extended to fabricating other oxide-Ag-oxide transparent electrodes via low-cost reactive sputtering. PMID:26726834

  14. Automated Root Tracking with "Root System Analyzer"

    NASA Astrophysics Data System (ADS)

    Schnepf, Andrea; Jin, Meina; Ockert, Charlotte; Bol, Roland; Leitner, Daniel

    2015-04-01

    Crucial factors for plant development are water and nutrient availability in soils. Thus, root architecture is a main aspect of plant productivity and needs to be accurately considered when describing root processes. Images of root architecture contain a huge amount of information, and image analysis helps to recover parameters describing certain root architectural and morphological traits. The majority of imaging systems for root systems are designed for two-dimensional images, such as RootReader2, GiA Roots, SmartRoot, EZ-Rhizo, and Growscreen, but most of them are semi-automated and involve mouse-clicks in each root by the user. "Root System Analyzer" is a new, fully automated approach for recovering root architectural parameters from two-dimensional images of root systems. Individual roots can still be corrected manually in a user interface if required. The algorithm starts with a sequence of segmented two-dimensional images showing the dynamic development of a root system. For each image, morphological operators are used for skeletonization. Based on this, a graph representation of the root system is created. A dynamic root architecture model helps to determine which edges of the graph belong to an individual root. The algorithm elongates each root at the root tip and simulates growth confined within the already existing graph representation. The increment of root elongation is calculated assuming constant growth. For each root, the algorithm finds all possible paths and elongates the root in the direction of the optimal path. In this way, each edge of the graph is assigned to one or more coherent roots. Image sequences of root systems are handled in such a way that the previous image is used as a starting point for the current image. The algorithm is implemented in a set of Matlab m-files. Output of Root System Analyzer is a data structure that includes for each root an identification number, the branching order, the time of emergence, the parent

  15. Root gravitropism

    NASA Technical Reports Server (NTRS)

    Masson, P. H.

    1995-01-01

    When a plant root is reoriented within the gravity field, it responds by initiating a curvature which eventually results in vertical growth. Gravity sensing occurs primarily in the root tip. It may involve amyloplast sedimentation in the columella cells of the root cap, or the detection of forces exerted by the mass of the protoplast on opposite sides of its cell wall. Gravisensing activates a signal transduction cascade which results in the asymmetric redistribution of auxin and apoplastic Ca2+ across the root tip, with accumulation at the bottom side. The resulting lateral asymmetry in Ca2+ and auxin concentration is probably transmitted to the elongation zone where differential cellular elongation occurs until the tip resumes vertical growth. The Cholodny-Went theory proposes that gravity-induced auxin redistribution across a gravistimulated plant organ is responsible for the gravitropic response. However, recent data indicate that the gravity-induced reorientation is more complex, involving both auxin gradient-dependent and auxin gradient-independent events.

  16. Root canal

    MedlinePlus

    Endodontic therapy ... the root of a tooth. Generally, there is pain and swelling in the area. The infection can ... You may have some pain or soreness after the procedure. An over-the-counter anti-inflammatory drug, such as ibuprofen or naproxen, can help relieve ...

  17. Facile synthesis of hybrid nanorods with the Sb2Se3/AgSbSe2 heterojunction structure for high performance photodetectors.

    PubMed

    Chen, Shuo; Qiao, Xvsheng; Wang, Fengxia; Luo, Qun; Zhang, Xianghua; Wan, Xia; Xu, Yang; Fan, Xianping

    2016-01-28

    An effective colloidal process involving the hot-injection method is developed to synthesize uniform single-crystalline Sb2Se3 nanorods in high yields. The photoconductive characteristics of the as-synthesized Sb2Se3 nanorods are investigated by developing a film-based photodetector and this device displays a remarkable response to visible light with an "ON/OFF" ratio as high as 50 (with an incident light density of 12.05 mW cm(-2)), short response/recovery times and long-term durability. To overcome the challenge of the intrinsic low electrical conductivity of Sb2Se3, hybrid nanorods with the Sb2Se3/AgSbSe2 heterojunction structure having a type-II band alignment are firstly prepared. The electric current of the photodetector based on the Sb2Se3/AgSbSe2 hybrid nanorod film has been significantly increased both in the dark and under light illumination. The responsivity of the photodetector based on the Sb2Se3/AgSbSe2 hybrid nanorod film is about 4.2 times as much as that of the photodetector based on the Sb2Se3 nanorod film. This improvement can be considered as an important step to promote Sb2Se3 based semiconductors for applications in high performance photodetectors. PMID:26743461

  18. Geophysical Imaging of Root Architecture and Root-soil Interaction

    NASA Astrophysics Data System (ADS)

    Wu, Y.; Dafflon, B.; Hubbard, S. S.

    2015-12-01

    Roots play a critical role in controlling water and nutrient uptake, soil biogeochemical processes, as well as the physical anchorage for plants. While important processes, such as root hydraulic redistribution for optimal growth and survival have been recognized, representation of roots in climate models, e.g. its carbon storage, carbon resilience, root biomass, and role in regulating water and carbon fluxes across the rhizosphere and atmosphere interface is still challenging. Such a challenge is exacerbated because of the large variations of root architecture and function across species and locations due to both genetic and environmental controls and the lack of methods for quantifying root mass, distribution, dynamics and interaction with soils at field scales. The scale, complexity and the dynamic nature of plant roots call for minimally invasive methods capable of providing quantitative estimation of root architecture, dynamics over time and interactions with the soils. We present a study on root architecture and root-soil interactions using geophysical methods. Parameters and processes of interests include (1) moisture dynamics around root zone and its interaction with plant transpiration and environmental controls and (2) estimation of root structure and properties based on geophysical signals. Both pot and field scale studies were conducted. The pot scale experiments were conducted under controlled conditions and were monitored with cross-well electrical resistivity tomography (ERT), TDR moisture sensors and temperature probes. Pots with and without a tree were compared and the moisture conditions were controlled via a self regulated pumping system. Geophysical monitoring revealed interactions between roots and soils under dynamic soil moisture conditions and the role of roots in regulating the response of the soil system to changes of environmental conditions, e.g. drought and precipitation events. Field scale studies were conducted on natural trees using

  19. Sensitivity of the "Root Bundle Model" to root mechanical properties and root distribution: Implication for shallow landslide stability.

    NASA Astrophysics Data System (ADS)

    Schwarz, Massimiliano; Giadrossich, Filippo; Cohen, Denis

    2015-04-01

    Root reinforcement is recognized as an important factor for shallow landslides stability. Due to the complexity of root reinforcement mechanisms and the heterogeneity of the root-soil system, the estimation of parameters used in root reinforcement models is difficult, time consuming, and often highly uncertain. For practical applications, it is necessary to focus on the estimation of the most relevant parameters. The objective of the present contribution is to review the state of the art in the development of root reinforcement models and to discuss the sensitivity of the "Root Bundle Model" (RBM) when considering the variability of root mechanical properties and the heterogeneity of root distributions. The RBM is a strain-step loading fiber bundle model extended to include the mechanical and geometrical properties of roots. The model allows the calculation of the force-displacement behavior of a root bundle. In view of new results of field pullout tests performed on coarse roots of spruce (Picea abies) and considering a consistent dataset of root distribution of alpine tree species, we quantify the sensitivity of the RBM and the uncertainty associated with the most important input parameters. Preliminary results show that the extrapolation of force-diameter values from incomplete datasets (i.e., when only small roots are tested and values for coarse roots are extrapolated) may result in considerable errors. In particular, in the case of distributions with root diameters larger than 5 mm, root reinforcement tends to be dominated by coarse roots and their mechanical properties need to be quantified. In addition to the results of the model sensitivity, we present a possible best-practice method for the quantification of root reinforcement in view of its application to slope stability calculations and implementations in numerical models.

  20. Descendant root volume varies as a function of root type: estimation of root biomass lost during uprooting in Pinus pinaster

    PubMed Central

    Danjon, Frédéric; Caplan, Joshua S.; Fortin, Mathieu; Meredieu, Céline

    2013-01-01

    Root systems of woody plants generally display a strong relationship between the cross-sectional area or cross-sectional diameter (CSD) of a root and the dry weight of biomass (DWd) or root volume (Vd) that has grown (i.e., is descendent) from a point. Specification of this relationship allows one to quantify root architectural patterns and estimate the amount of material lost when root systems are extracted from the soil. However, specifications of this relationship generally do not account for the fact that root systems are comprised of multiple types of roots. We assessed whether the relationship between CSD and Vd varies as a function of root type. Additionally, we sought to identify a more accurate and time-efficient method for estimating missing root volume than is currently available. We used a database that described the 3D root architecture of Pinus pinaster root systems (5, 12, or 19 years) from a stand in southwest France. We determined the relationship between CSD and Vd for 10,000 root segments from intact root branches. Models were specified that did and did not account for root type. The relationships were then applied to the diameters of 11,000 broken root ends to estimate the volume of missing roots. CSD was nearly linearly related to the square root of Vd, but the slope of the curve varied greatly as a function of root type. Sinkers and deep roots tapered rapidly, as they were limited by available soil depth. Distal shallow roots tapered gradually, as they were less limited spatially. We estimated that younger trees lost an average of 17% of root volume when excavated, while older trees lost 4%. Missing volumes were smallest in the central parts of root systems and largest in distal shallow roots. The slopes of the curves for each root type are synthetic parameters that account for differentiation due to genetics, soil properties, or mechanical stimuli. Accounting for this differentiation is critical to estimating root loss accurately. PMID

  1. Pythium Root Rot (and Feeder Root Necrosis)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Pythium species cause a number of diseases on corn. Among the Pythium diseases, root rot presents the least conspicuous aboveground symptoms. Broadly defined, root rot also includes feeder root necrosis. At least 16 species of Pythium are known to cause root rot of corn. These include P. acanthicu...

  2. Modeling root reinforcement using a root-failure Weibull survival function

    NASA Astrophysics Data System (ADS)

    Schwarz, M.; Giadrossich, F.; Cohen, D.

    2013-11-01

    Root networks contribute to slope stability through complex interactions with soil that include mechanical compression and tension. Due to the spatial heterogeneity of root distribution and the dynamics of root turnover, the quantification of root reinforcement on steep slopes is challenging and consequently the calculation of slope stability also. Although considerable progress has been made, some important aspects of root mechanics remain neglected. In this study we address specifically the role of root-strength variability on the mechanical behavior of a root bundle. Many factors contribute to the variability of root mechanical properties even within a single class of diameter. This work presents a new approach for quantifying root reinforcement that considers the variability of mechanical properties of each root diameter class. Using the data of laboratory tensile tests and field pullout tests, we calibrate the parameters of the Weibull survival function to implement the variability of root strength in a numerical model for the calculation of root reinforcement (RBMw). The results show that, for both laboratory and field data sets, the parameters of the Weibull distribution may be considered constant with the exponent equal to 2 and the normalized failure displacement equal to 1. Moreover, the results show that the variability of root strength in each root diameter class has a major influence on the behavior of a root bundle with important implications when considering different approaches in slope stability calculation. Sensitivity analysis shows that the calibration of the equations of the tensile force, the elasticity of the roots, and the root distribution are the most important steps. The new model allows the characterization of root reinforcement in terms of maximum pullout force, stiffness, and energy. Moreover, it simplifies the implementation of root reinforcement in slope stability models. The realistic quantification of root reinforcement for tensile

  3. In situ observation of thermomigration of Sn atoms to the hot end of 96.5Sn-3Ag-0.5Cu flip chip solder joints

    NASA Astrophysics Data System (ADS)

    Ouyang, Fan-Yi; Kao, C.-L.

    2011-12-01

    In this study, we investigated the phenomenon of thermomigration in 96.5Sn-3Ag-0.5Cu flip chip solder joints at an ambient temperature of 150 °C. We observed mass protrusion on the chip side (hot end), indicating that Sn atoms moved to the hot end, and void formation on the substrate side (cold end). The diffusion markers also moved to the substrate side, in the same direction of the vacancy flux, indicating that the latter played a dominant role during the thermomigration process. The molar heat of transport (Q*) of the Sn atoms was 3.38 kJ/mol.

  4. Nutritional regulation of root development.

    PubMed

    Ruiz Herrera, León Francisco; Shane, Michael W; López-Bucio, José

    2015-01-01

    Mineral nutrients such as nitrogen (N), phosphorus (P), and iron (Fe) are essential for plant growth, development, and reproduction. Adequate provision of nutrients via the root system impacts greatly on shoot biomass and plant productivity and is therefore of crucial importance for agriculture. Nutrients are taken up at the root surface in ionic form, which is mediated by specific transport proteins. Noteworthy, root tips are able to sense the local and internal concentrations of nutrients to adjust growth and developmental processes, and ultimately, to increase or decrease the exploratory capacity of the root system. Recently, important progress has been achieved in identifying the mechanisms of nutrient sensing in wild- and cultivated species, including Arabidopsis, bean, maize, rice, lupin as well as in members of the Proteaceae and Cyperaceae families, which develop highly sophisticated root clusters as adaptations to survive in soils with very low fertility. Major findings include identification of transporter proteins and transcription factors regulating nutrient sensing, miRNAs as mobile signals and peptides as repressors of lateral root development under heterogeneous nutrient supply. Understanding the roles played by N, P, and Fe in gene expression and biochemical characterization of proteins involved in root developmental responses to homogeneous or heterogeneous N and P sources has gained additional interest due to its potential for improving fertilizer acquisition efficiency in crops. PMID:25760021

  5. Rhizosphere biophysics and root water uptake

    NASA Astrophysics Data System (ADS)

    Carminati, Andrea; Zarebanadkouki, Mohsen; Ahmed, Mutez A.; Passioura, John

    2016-04-01

    The flow of water into the roots and the (putative) presence of a large resistance at the root-soil interface have attracted the attention of plant and soil scientists for decades. Such resistance has been attributed to a partial contact between roots and soil, large gradients in soil matric potential around the roots, or accumulation of solutes at the root surface creating a negative osmotic potential. Our hypothesis is that roots are capable of altering the biophysical properties of the soil around the roots, the rhizosphere, facilitating root water uptake in dry soils. In particular, we expect that root hairs and mucilage optimally connect the roots to the soil maintaining the hydraulic continuity across the rhizosphere. Using a pressure chamber apparatus we measured the relation between transpiration rate and the water potential difference between soil and leaf xylem during drying cycles in barley mutants with and without root hairs. The samples were grown in well structured soils. At low soil moistures and high transpiration rates, large drops in water potential developed around the roots. These drops in water potential recovered very slowly, even after transpiration was severely decreased. The drops in water potential were much bigger in barley mutants without root hairs. These mutants failed to sustain high transpiration rates in dry conditions. To explain the nature of such drops in water potential across the rhizosphere we performed high resolution neutron tomography of the rhizosphere of the barleys with and without root hairs growing in the same soil described above. The tomograms suggested that the hydraulic contact between the soil structures was the highest resistance for the water flow in dry conditions. The tomograms also indicate that root hairs and mucilage improved the hydraulic contact between roots and soil structures. At high transpiration rates and low water contents, roots extracted water from the rhizosphere, while the bulk soil, due its

  6. Root Canal Treatment of a Two-Rooted C-Shaped Maxillary First Molar: A Case Report

    PubMed Central

    Paksefat, Sara; Rahimi, Saeed

    2014-01-01

    The most difficult maxillary teeth for endodontic treatment are the maxillary first molars (MFM) due to their complex root canal anatomy. The presence of two roots and C-shaped canals in MFMs has been reported in rare cases. The present case reports root canal treatment of MFM with two roots, where the palatal and buccal roots were joined together in a C-shaped configuration. PMID:25386214

  7. Spin and orbital magnetism of coinage metal trimers (Cu{sub 3}, Ag{sub 3}, Au{sub 3}): A relativistic density functional theory study

    SciTech Connect

    Afshar, Mahdi; Sargolzaei, Mohsen

    2013-11-15

    We have demonstrated electronic structure and magnetic properties of Cu{sub 3}, Ag{sub 3} and Au{sub 3} trimers using a full potential local orbital method in the framework of relativistic density functional theory. We have also shown that the non-relativistic generalized gradient approximation for the exchange-correlation energy functional gives reliable magnetic properties in coinage metal trimers compared to experiment. In addition we have indicated that the spin-orbit coupling changes the structure and magnetic properties of gold trimer while the structure and magnetic properties of copper and silver trimers are marginally affected. A significant orbital moment of 0.21μ{sub B} was found for most stable geometry of the gold trimer whereas orbital magnetism is almost quenched in the copper and silver trimers.

  8. Energies and excited-state dynamics of 1Bu+, 1Bu- and 3Ag- states of carotenoids bound to LH2 antenna complexes from purple photosynthetic bacteria

    NASA Astrophysics Data System (ADS)

    Christiana, Rebecca; Miki, Takeshi; Kakitani, Yoshinori; Aoyagi, Shiho; Koyama, Yasushi; Limantara, Leenawaty

    2009-10-01

    Time-resolved pump-probe stimulated-emission and transient-absorption spectra were recorded after excitation with ˜30 fs pulses to the 1Bu+(0) and optically-forbidden diabatic levels of carotenoids, neurosporene, spheroidene and lycopene having n = 9-11 double bonds, bound to LH2 antenna complexes from Rhodobacter sphaeroides G1C, 2.4.1 and Rhodospirillum molischianum. The low-energy shift of stimulated emission from the covalent 1Bu-(0) and 3Ag-(0) levels slightly larger than that from the ionic 1Bu+(0) state suggests the polarization, whereas more efficient triplet generation suggests the twisting of the conjugated chain in Cars bound to the LH2 complexes, when compared to Cars free in solution.

  9. Affine root systems and dual numbers

    NASA Astrophysics Data System (ADS)

    Kostyakov, I. V.; Gromov, N. A.; Kuratov, V. V.

    The root systems in Carroll spaces with degenerate metric are defined. It is shown that their Cartan matrices and reflection groups are affine. Due to the geometric consideration the root system structure of affine algebras is determined by a sufficiently simple algorithm.

  10. Vibrational relaxation and internal conversion in the overlapped optically-allowed 1Bu+ and optically-forbidden 1Bu- or 3Ag- vibronic levels of carotenoids: Effects of diabatic mixing as determined by Kerr-gate fluorescence spectroscopy

    NASA Astrophysics Data System (ADS)

    Kakitani, Yoshinori; Miki, Takeshi; Koyama, Yasushi; Nagae, Hiroyoshi; Nakamura, Ryosuke; Kanematsu, Yasuo

    2009-07-01

    The time constants of the vibrational relaxation, υ = 2 → υ = 1 and υ = 1 → υ = 0, in the 1Bu+ manifold and those of internal conversion from the 1Bu+(0) level, which is isoenergetic (so-called 'diabatic') with the 1Bu- vibronic levels in neurosporene and spheroidene and with the 3Ag- vibronic levels in lycopene and anhydrorhodovibrin, were determined by Kerr-gate fluorescence spectroscopy. The time constants of the vibrational relaxation were in the ˜1:2 ratio, and those of internal conversion agreed with the lifetimes of the diabatic counterparts, i.e., the 1Bu- and 3Ag- electronic states, respectively.

  11. Root-Gel Interactions and the Root Waving Behavior of Arabidopsis1[w

    PubMed Central

    Thompson, Matthew V.; Holbrook, N. Michele

    2004-01-01

    Arabidopsis roots grown on inclined agarose gels exhibit a sinusoidal growth pattern known as root waving. While root waving has been attributed to both intrinsic factors (e.g. circumnutation) and growth responses to external signals such as gravity, the potential for physical interactions between the root and its substrate to influence the development of this complex phenotype has been generally ignored. Using a rotating stage microscope and time-lapse digital imaging, we show that (1) root tip mobility is impeded by the gel surface, (2) this impedance causes root tip deflections by amplifying curvature in the elongation zone in a way that is distinctly nontropic, and (3) root tip impedance is augmented by normal gravitropic pressure applied by the root tip against the gel surface. Thus, both lateral corrective bending near the root apex and root tip impedance could be due to different vector components of the same graviresponse. Furthermore, we speculate that coupling between root twisting and bending is a mechanical effect resulting from root tip impedance. PMID:15247406

  12. Charge carrier mobility and concentration as a function of composition in AgPO3-AgI glasses

    NASA Astrophysics Data System (ADS)

    Rodrigues, Ana Candida Martins; Nascimento, Marcio Luis Ferreira; Bragatto, Caio Barca; Souquet, Jean-Louis

    2011-12-01

    Conductivity data of the xAgI(1 - x)AgPO3 system (0 ≤ x ≤ 0.5) were collected in the liquid and glassy states. The difference in the dependence of ionic conductivity on temperature below and above their glass transition temperatures (Tg) is interpreted by a discontinuity in the charge carrier's mobility mechanisms. Charge carrier displacement occurs through an activated mechanism below Tg and through a Vogel-Fulcher-Tammann-Hesse mechanism above this temperature. Fitting conductivity data with the proposed model allows one to determine separately the enthalpies of charge carrier formation and migration. For the five investigated compositions, the enthalpy of charge carrier formation is found to decrease, with x, from 0.86 to 0.2 eV, while the migration enthalpy remains constant at ≈0.14 eV. Based on these values, the charge carrier mobility and concentration in the glassy state can then be calculated. Mobility values at room temperature (≈10-4 cm2 V-1 s-1) do not vary significantly with the AgI content and are in good agreement with those previously measured by the Hall-effect technique. The observed increase in ionic conductivity with x would thus only be due to an increase in the effective charge carrier concentration. Considering AgI as a weak electrolyte, the change in the effective charge carrier concentration is justified and is correlated to the partial free energy of silver iodide forming a regular solution with AgPO3.

  13. A statistical approach to root system classification

    PubMed Central

    Bodner, Gernot; Leitner, Daniel; Nakhforoosh, Alireza; Sobotik, Monika; Moder, Karl; Kaul, Hans-Peter

    2013-01-01

    Plant root systems have a key role in ecology and agronomy. In spite of fast increase in root studies, still there is no classification that allows distinguishing among distinctive characteristics within the diversity of rooting strategies. Our hypothesis is that a multivariate approach for “plant functional type” identification in ecology can be applied to the classification of root systems. The classification method presented is based on a data-defined statistical procedure without a priori decision on the classifiers. The study demonstrates that principal component based rooting types provide efficient and meaningful multi-trait classifiers. The classification method is exemplified with simulated root architectures and morphological field data. Simulated root architectures showed that morphological attributes with spatial distribution parameters capture most distinctive features within root system diversity. While developmental type (tap vs. shoot-borne systems) is a strong, but coarse classifier, topological traits provide the most detailed differentiation among distinctive groups. Adequacy of commonly available morphologic traits for classification is supported by field data. Rooting types emerging from measured data, mainly distinguished by diameter/weight and density dominated types. Similarity of root systems within distinctive groups was the joint result of phylogenetic relation and environmental as well as human selection pressure. We concluded that the data-define classification is appropriate for integration of knowledge obtained with different root measurement methods and at various scales. Currently root morphology is the most promising basis for classification due to widely used common measurement protocols. To capture details of root diversity efforts in architectural measurement techniques are essential. PMID:23914200

  14. A statistical approach to root system classification.

    PubMed

    Bodner, Gernot; Leitner, Daniel; Nakhforoosh, Alireza; Sobotik, Monika; Moder, Karl; Kaul, Hans-Peter

    2013-01-01

    Plant root systems have a key role in ecology and agronomy. In spite of fast increase in root studies, still there is no classification that allows distinguishing among distinctive characteristics within the diversity of rooting strategies. Our hypothesis is that a multivariate approach for "plant functional type" identification in ecology can be applied to the classification of root systems. The classification method presented is based on a data-defined statistical procedure without a priori decision on the classifiers. The study demonstrates that principal component based rooting types provide efficient and meaningful multi-trait classifiers. The classification method is exemplified with simulated root architectures and morphological field data. Simulated root architectures showed that morphological attributes with spatial distribution parameters capture most distinctive features within root system diversity. While developmental type (tap vs. shoot-borne systems) is a strong, but coarse classifier, topological traits provide the most detailed differentiation among distinctive groups. Adequacy of commonly available morphologic traits for classification is supported by field data. Rooting types emerging from measured data, mainly distinguished by diameter/weight and density dominated types. Similarity of root systems within distinctive groups was the joint result of phylogenetic relation and environmental as well as human selection pressure. We concluded that the data-define classification is appropriate for integration of knowledge obtained with different root measurement methods and at various scales. Currently root morphology is the most promising basis for classification due to widely used common measurement protocols. To capture details of root diversity efforts in architectural measurement techniques are essential. PMID:23914200

  15. Impact of Heterobasidion root-rot on fine root morphology and associated fungi in Picea abies stands on peat soils.

    PubMed

    Gaitnieks, Talis; Klavina, Darta; Muiznieks, Indrikis; Pennanen, Taina; Velmala, Sannakajsa; Vasaitis, Rimvydas; Menkis, Audrius

    2016-07-01

    We examined differences in fine root morphology, mycorrhizal colonisation and root-inhabiting fungal communities between Picea abies individuals infected by Heterobasidion root-rot compared with healthy individuals in four stands on peat soils in Latvia. We hypothesised that decreased tree vitality and alteration in supply of photosynthates belowground due to root-rot infection might lead to changes in fungal communities of tree roots. Plots were established in places where trees were infected and in places where they were healthy. Within each stand, five replicate soil cores with roots were taken to 20 cm depth in each root-rot infected and uninfected plot. Root morphological parameters, mycorrhizal colonisation and associated fungal communities, and soil chemical properties were analysed. In three stands root morphological parameters and in all stands root mycorrhizal colonisation were similar between root-rot infected and uninfected plots. In one stand, there were significant differences in root morphological parameters between root-rot infected versus uninfected plots, but these were likely due to significant differences in soil chemical properties between the plots. Sequencing of the internal transcribed spacer of fungal nuclear rDNA from ectomycorrhizal (ECM) root morphotypes of P. abies revealed the presence of 42 fungal species, among which ECM basidiomycetes Tylospora asterophora (24.6 % of fine roots examined), Amphinema byssoides (14.5 %) and Russula sapinea (9.7 %) were most common. Within each stand, the richness of fungal species and the composition of fungal communities in root-rot infected versus uninfected plots were similar. In conclusion, Heterobasidion root-rot had little or no effect on fine root morphology, mycorrhizal colonisation and composition of fungal communities in fine roots of P. abies growing on peat soils. PMID:26861482

  16. The Root Pressure Phenomenon

    ERIC Educational Resources Information Center

    Marsh, A. R.

    1972-01-01

    Describes experiments demonstrating that root pressure in plants is probably controlled by a circadian rhythm (biological clock). Root pressure phenomenon plays significant part in water transport in contradiction with prevalent belief. (PS)

  17. Using Square Roots

    ERIC Educational Resources Information Center

    Wilson, William Wynne

    1976-01-01

    This article describes techniques which enable the user of a comparatively simple calculator to perform calculations of cube roots, nth roots, trigonometric, and inverse trigonometric functions, logarithms, and exponentials. (DT)

  18. Root Traits and Phenotyping Strategies for Plant Improvement

    PubMed Central

    Paez-Garcia, Ana; Motes, Christy M.; Scheible, Wolf-Rüdiger; Chen, Rujin; Blancaflor, Elison B.; Monteros, Maria J.

    2015-01-01

    Roots are crucial for nutrient and water acquisition and can be targeted to enhance plant productivity under a broad range of growing conditions. A current challenge for plant breeding is the limited ability to phenotype and select for desirable root characteristics due to their underground location. Plant breeding efforts aimed at modifying root traits can result in novel, more stress-tolerant crops and increased yield by enhancing the capacity of the plant for soil exploration and, thus, water and nutrient acquisition. Available approaches for root phenotyping in laboratory, greenhouse and field encompass simple agar plates to labor-intensive root digging (i.e., shovelomics) and soil boring methods, the construction of underground root observation stations and sophisticated computer-assisted root imaging. Here, we summarize root architectural traits relevant to crop productivity, survey root phenotyping strategies and describe their advantages, limitations and practical value for crop and forage breeding programs. PMID:27135332

  19. Root Traits and Phenotyping Strategies for Plant Improvement.

    PubMed

    Paez-Garcia, Ana; Motes, Christy M; Scheible, Wolf-Rüdiger; Chen, Rujin; Blancaflor, Elison B; Monteros, Maria J

    2015-01-01

    Roots are crucial for nutrient and water acquisition and can be targeted to enhance plant productivity under a broad range of growing conditions. A current challenge for plant breeding is the limited ability to phenotype and select for desirable root characteristics due to their underground location. Plant breeding efforts aimed at modifying root traits can result in novel, more stress-tolerant crops and increased yield by enhancing the capacity of the plant for soil exploration and, thus, water and nutrient acquisition. Available approaches for root phenotyping in laboratory, greenhouse and field encompass simple agar plates to labor-intensive root digging (i.e., shovelomics) and soil boring methods, the construction of underground root observation stations and sophisticated computer-assisted root imaging. Here, we summarize root architectural traits relevant to crop productivity, survey root phenotyping strategies and describe their advantages, limitations and practical value for crop and forage breeding programs. PMID:27135332

  20. Influence of heat treatment on characteristics of In2O3/Ag/MoO3 multilayer films as transparent anode for optoelectronic applications

    NASA Astrophysics Data System (ADS)

    Varnamkhasti, Mohsen Ghasemi; Shahriari, Esmaeil

    2015-09-01

    In this study, In2O3/Ag/MoO3 (IAM) nano-multilayer films are designed, and optimum thickness of each layer is calculated. These films were deposited by thermal evaporation technique and then annealed in air atmosphere at different temperatures for 1 h. The effects of annealing temperature on electrical, optical, and structural properties of the IAM system were investigated. The UV-visible-near-IR transmittance and reflectance spectra confirmed that the annealing temperature has significant influence on the electro-optical characteristics of IAM films. High-quality IAM films with a low sheet resistance of 8.2 (Ω/□) and the maximum optical transmittance of 85 % at 120 °C annealing temperature were obtained. The effect of heat treatment on surface roughness of the layers was also investigated. Figure-of-merit quantity showed that the IAM films annealed at 120 °C have the best performance. X-ray diffraction patterns showed that the crystallinity of the structures enhanced with increase in annealing temperature. Organic light-emitting diodes (OLEDs) were fabricated on IAM anodes. The current density-voltage-luminance (J-V-L) characteristic measurements show that the electroluminescence performances of OLED with IAM anode are improved compared with the conventional ITO-based device. The results indicate that the designed system is suitable for use as transparent conductive anode in optoelectronic devices.

  1. Effect of Joint Scale and Processing on the Fracture of Sn-3Ag-0.5Cu Solder Joints: Application to Micro-bumps in 3D Packages

    NASA Astrophysics Data System (ADS)

    Talebanpour, B.; Huang, Z.; Chen, Z.; Dutta, I.

    2016-01-01

    In 3-dimensional (3D) packages, a stack of dies is vertically connected to each other using through-silicon vias and very thin solder micro-bumps. The thinness of the micro-bumps results in joints with a very high volumetric proportion of intermetallic compounds (IMCs), rendering them much more brittle compared to conventional joints. Because of this, the reliability of micro-bumps, and the dependence thereof on the proportion of IMC in the joint, is of substantial concern. In this paper, the growth kinetics of IMCs in thin Sn-3Ag-0.5Cu joints attached to Cu substrates were analyzed, and empirical kinetic laws for the growth of Cu6Sn5 and Cu3Sn in thin joints were obtained. Modified compact mixed mode fracture mechanics samples, with adhesive solder joints between massive Cu substrates, having similar thickness and IMC content as actual micro-bumps, were produced. The effects of IMC proportion and strain rate on fracture toughness and mechanisms were investigated. It was found that the fracture toughness G C decreased with decreasing joint thickness ( h Joint). In addition, the fracture toughness decreased with increasing strain rate. Aging also promoted alternation of the crack path between the two joint-substrate interfaces, possibly proffering a mechanism to enhance fracture toughness.

  2. Morphology of the Tin Whiskers on the Surface of a Sn-3Ag-0.5Cu-0.5Nd Alloy

    NASA Astrophysics Data System (ADS)

    Chuang, Tung-Han; Jain, Chao-Chi

    2011-03-01

    Rapid growth of tin whiskers has been observed on the surface of rosette-shaped NdSn3 intermetallic phase in a Sn-3Ag-0.5Cu-0.5Nd alloy after air storage. It is shown that various cross sections of NdSn3 rosettes in the solder matrix reveal different morphologies of tin whiskers, which can be classified as four types: long fibers, short fibers, tiny sprouts, and hillocks. The fibrous whiskers and tiny sprouts are found on the surfaces of specimens exposed to air at room temperature and 423 K (150 °C), while hillocks appear only after storage at 423 K (150 °C). In addition, it is observed that, in most cases, each oxidized NdSn3 intermetallic phase contains only a single whisker at its center. Through metallographic observations and chemical analyses on the cross sections of the oxidized NdSn3 intermetallics, a "successive compressive stress model" has been proposed to interpret the tin whisker growth on the surface of a rare earth (RE)-containing solder.

  3. Semitransparent inverted organic solar cell with improved absorption and reasonable transparency perception based on the nanopatterned MoO3/Ag/MoO3 anode

    NASA Astrophysics Data System (ADS)

    Tian, Ximin; Zhang, Ye; Hao, Yuying; Cui, Yanxia; Wang, Wenyan; Shi, Fang; Wang, Hua; Wei, Bin; Huang, Wei

    2015-01-01

    We demonstrate an inverted low bandgap semitransparent organic solar cell with improved absorption as well as reasonable transparency perception based on a nanopatterned MoO3/Ag/MoO3 (MAM) multilayer film as the transparent anode under illumination from the MAM side. The integrated absorption efficiency of the active layer at normal hybrid-polarized incidence considering an AM 1.5G solar spectrum is up to 51.69%, increased by 18.53% as compared to that of the equivalent planar device (43.61%) and reaching 77.3% of that of the corresponding opaque nanopatterned device (66.90%). Detailed investigations reveal that the excitation of plasmonic waveguide modes (at transverse magnetic polarization) and photonic modes (at transverse electric polarization) are responsible for the observed enhancement in absorption. Importantly, the proposed device exhibits an average transmittance of up to 28.4% and an average transparency perception of 26.3% for the human eyes under hybrid-polarized light illumination along with a good color rendering property. Additionally, our proposal works very well over a fairly wide angular range.

  4. Omnidirectional and broadband optical absorption enhancement in small molecule organic solar cells by a patterned MoO3/Ag/MoO3 transparent anode

    NASA Astrophysics Data System (ADS)

    Tian, Ximin; Hao, Yuying; Zhang, Ye; Cui, Yanxia; Ji, Ting; Wang, Hua; Wei, Bin; Huang, Wei

    2015-03-01

    We designed and calculated a novel organic solar cell (OSC) with MoO3/Ag/MoO3 (MAM) grating as transparent anode and the patterned copper phthalocyanine (CuPc)/fullerence (C60) as active layer. The numerical results indicate that a broadband, omnidirectional light absorption enhancement is realized by utilizing such a one-dimensional (1D) grating with core-shell structure. The total absorption efficiency of the active layer over the wavelength range from 400 to 900 nm is enhanced by 178.88%, 19.44% and 99.16% relative to the equivalent planar cell considering the weight of air-mass 1.5 global (AM 1.5G) solar spectrum at normally incident transverse magnetic (TM), transverse electric (TE) and TM/TE hybrid polarized light, respectively. The improved light trapping is attributed to the multiple modes hybridization of propagating surface plasmon polaritons (SPPs), localized surface plasmons (LSPs) and the strong coupling of SPP waves at TM polarization along with the Floquet modes at TE polarization. Furthermore, the proposed optimized architecture also exhibits an expected short-circuit current density (Jsc) with the value of 11.11 mA/cm2 in theory, which is increased by 116.6% compared with that of the planar control device.

  5. Armillaria root rot

    Technology Transfer Automated Retrieval System (TEKTRAN)

    First described on grapevines in California in the 1880s, Armillaria root rot occurs in all major grape-growing regions of the state. The causal fungus, Armillaria mellea, infects woody grapevine roots and the base of the trunk (the root collar), resulting in a slow decline and eventual death of the...

  6. BLACK ROOT ROT

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Black Root Rot Prepared by G. S. Abawi, Revised by L.E. Hanson Black root rot is caused by Thielaviopsis basicola (syn. Chalara elegans). The pathogen is widely distributed, can infect more than 130 plant species in 15 families, and causes severe black root rot diseases in ornamentals and crops suc...

  7. Corky root rot

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Corky root rot (corchosis) was first reported in Argentina in 1985, but the disease was presumably present long before that. The disease occurs in most alfalfa-growing areas of Argentina but is more common in older stands. In space-planted alfalfa trials scored for root problems, corky root rot was ...

  8. WHY ROOTING FAILS.

    SciTech Connect

    CREUTZ,M.

    2007-07-30

    I explore the origins of the unphysical predictions from rooted staggered fermion algorithms. Before rooting, the exact chiral symmetry of staggered fermions is a flavored symmetry among the four 'tastes.' The rooting procedure averages over tastes of different chiralities. This averaging forbids the appearance of the correct 't Hooft vertex for the target theory.

  9. Investigation of VEGGIE Root Mat

    NASA Technical Reports Server (NTRS)

    Subbiah, Arun M.

    2013-01-01

    VEGGIE is a plant growth facility that utilizes the phenomenon of capillary action as its primary watering system. A cloth made of Meta Aramid fiber, known as Nomex is used to wick water up from a reservoir to the bottom of the plants roots. This root mat system is intended to be low maintenance with no moving parts and requires minimal crew interface time. Unfortunately, the water wicking rates are inconsistent throughout the plant life cycle, thus causing plants to die. Over-wicking of water occurs toward the beginning of the cycle, while under-wicking occurs toward the middle. This inconsistency of wicking has become a major issue, drastically inhibiting plant growth. The primary objective is to determine the root cause of the inconsistent wicking through experimental testing. Suspect causes for the capillary water column to break include: a vacuum effect due to a negative pressure gradient in the water reservoir, contamination of material due to minerals in water and back wash from plant fertilizer, induced air bubbles while using syringe refill method, and material limitations of Nomex's ability to absorb and retain water. Experimental testing will be conducted to systematically determine the cause of under and over-wicking. Pressure gages will be used to determine pressure drop during the course of the plant life cycle and during the water refill process. A debubbler device will be connected to a root mat in order to equalize pressure inside the reservoir. Moisture and evaporation tests will simultaneously be implemented to observe moisture content and wicking rates over the course of a plant cycle. Water retention tests will be performed using strips of Nomex to determine materials wicking rates, porosity, and absorptivity. Through these experimental tests, we will have a better understanding of material properties of Nomex, as well as determine the root cause of water column breakage. With consistent test results, a forward plan can be achieved to resolve

  10. Why fine tree roots are stronger than thicker roots: The role of cellulose and lignin in relation to slope stability

    NASA Astrophysics Data System (ADS)

    Zhang, Chao-Bo; Chen, Li-Hua; Jiang, Jing

    2014-02-01

    Plant roots help to reinforce the soil, increase slope stability and decrease water erosion. Root tensile strength plays an important role in soil reinforcement and slope stabilization. The relationship between tensile strength and internal chemical composition of roots is unknown due to limited studies. Thus, it is difficult to determine why root tensile strength tends to decrease with increasing root diameter. In this study, biomechanical and biochemical tests were performed on the roots of Chinese pine (Pinus tabulaeformis) to determine the relationships among tensile strength and the contents of the main chemical composition: cellulose, alpha-cellulose and lignin in the roots with different diameters. Our results confirmed that the tensile strength of Chinese pine roots decreased with increasing root diameter, and this relationship might be a power function. The chemical contents of the roots and root diameter were also related to each other with significant power regression. With increasing root diameter, the cellulose content and alpha-cellulose content increased, but the lignin content decreased. In addition, the lignin content exhibited a significantly positive relationship with tensile strength. Furthermore, the ratios of lignin/cellulose and lignin/alpha-cellulose decreased with increasing root diameter following significant power regressions, and they also demonstrated a positive relationship with tensile strength. Taken together, these results may be useful for studies on root tensile strength, soil reinforcement and slope stability.

  11. Malformations of the tooth root in humans.

    PubMed

    Luder, Hans U

    2015-01-01

    The most common root malformations in humans arise from either developmental disorders of the root alone or disorders of radicular development as part of a general tooth dysplasia. The aim of this review is to relate the characteristics of these root malformations to potentially disrupted processes involved in radicular morphogenesis. Radicular morphogenesis proceeds under the control of Hertwig's epithelial root sheath (HERS) which determines the number, length, and shape of the root, induces the formation of radicular dentin, and participates in the development of root cementum. Formation of HERS at the transition from crown to root development appears to be very insensitive to adverse effects, with the result that rootless teeth are extremely rare. In contrast, shortened roots as a consequence of impaired or prematurely halted apical growth of HERS constitute the most prevalent radicular dysplasia which occurs due to trauma and unknown reasons as well as in association with dentin disorders. While odontoblast differentiation inevitably stops when growth of HERS is arrested, it seems to be unaffected even in cases of severe dentin dysplasias such as regional odontodysplasia and dentin dysplasia type I. As a result radicular dentin formation is at least initiated and progresses for a limited time. The only condition affecting cementogenesis is hypophosphatasia which disrupts the formation of acellular cementum through an inhibition of mineralization. A process particularly susceptible to adverse effects appears to be the formation of the furcation in multirooted teeth. Impairment or disruption of this process entails taurodontism, single-rooted posterior teeth, and misshapen furcations. Thus, even though many characteristics of human root malformations can be related to disorders of specific processes involved in radicular morphogenesis, precise inferences as to the pathogenesis of these dysplasias are hampered by the still limited knowledge on root formation

  12. Malformations of the tooth root in humans

    PubMed Central

    Luder, Hans U.

    2015-01-01

    The most common root malformations in humans arise from either developmental disorders of the root alone or disorders of radicular development as part of a general tooth dysplasia. The aim of this review is to relate the characteristics of these root malformations to potentially disrupted processes involved in radicular morphogenesis. Radicular morphogenesis proceeds under the control of Hertwig's epithelial root sheath (HERS) which determines the number, length, and shape of the root, induces the formation of radicular dentin, and participates in the development of root cementum. Formation of HERS at the transition from crown to root development appears to be very insensitive to adverse effects, with the result that rootless teeth are extremely rare. In contrast, shortened roots as a consequence of impaired or prematurely halted apical growth of HERS constitute the most prevalent radicular dysplasia which occurs due to trauma and unknown reasons as well as in association with dentin disorders. While odontoblast differentiation inevitably stops when growth of HERS is arrested, it seems to be unaffected even in cases of severe dentin dysplasias such as regional odontodysplasia and dentin dysplasia type I. As a result radicular dentin formation is at least initiated and progresses for a limited time. The only condition affecting cementogenesis is hypophosphatasia which disrupts the formation of acellular cementum through an inhibition of mineralization. A process particularly susceptible to adverse effects appears to be the formation of the furcation in multirooted teeth. Impairment or disruption of this process entails taurodontism, single-rooted posterior teeth, and misshapen furcations. Thus, even though many characteristics of human root malformations can be related to disorders of specific processes involved in radicular morphogenesis, precise inferences as to the pathogenesis of these dysplasias are hampered by the still limited knowledge on root formation

  13. Pressure induced silver ion displacement in La{sub 3}Ag{sub 0.82}SnS{sub 7}

    SciTech Connect

    Daszkiewicz, Marek; Gulay, Lubomir D.

    2012-02-15

    Highlights: Black-Right-Pointing-Pointer The silver ion shifts with increasing pressure in the direction of the central-point of sulphur trigonal antiprism. Black-Right-Pointing-Pointer Coordination number changes from CN = 3 to CN = 6 at {approx}3 GPa. Black-Right-Pointing-Pointer Zero-pressure bulk modulus is B{sub 0} = 61.74 GPa and the pressure derivative is B{sup Prime }{sub 0}=4.02. Black-Right-Pointing-Pointer No phase transition up to 4.5 GPa was detected. -- Abstract: The compounds with the general formula Ln{sub 3}MTX{sub 7} (space group P6{sub 3}) (Ln - rare-earth element, M - monovalent element (Cu, Ag), T - Si, Ge, Sn and X - S, Se) are interesting owing to the possible application in the field of ionic conductivity. In the crystal structure the face-sharing [Ag(S){sub 6}] triangular antiprisms form the channels where the Ag{sup +} ion can migrate along the crystallographic c axis. High-pressure X-ray diffraction shows that Ag{sup +} ion moves towards the central-point of [Ag(S){sub 6}] when pressure is risen. As a consequence, the coordination number of Ag{sup +} changes from CN = 3 to CN = 6 at {approx}3 GPa. The La{sub 3}Ag{sub 0.82}SnS{sub 7} has stiff structure; zero-pressure bulk modulus is B{sub 0} = 61.74 GPa and the pressure derivative is B{sup Prime }{sub 0}=4.02.

  14. High resolution modeling of water and nutrient uptake by plant roots: at a scale from single root to root system

    NASA Astrophysics Data System (ADS)

    Abesha, Betiglu; Vanderborght, Jan; Javaux, Mathieu; Schnepf, Andrea; Vereecken, Harry

    2014-05-01

    The uptake of nutrients by plant roots is a multiscale problem. At the small scale, nutrient fluxes towards single roots lead to strong gradients in nutrient concentrations around single roots. At the scale of the root system and soil profile, nutrient fluxes are generated by water fluxes and variations in nutrient uptake due to spatially varying root density, nutrient concentrations and water contents. In this contribution, we present a numerical simulation model that describes the processes at the scale of a single root and the scale of the entire root system simultaneously. Water flow and nutrient transport in the soil are described by the 3-D Richards and advection-dispersion equations, respectively. Water uptake by a root segment is simulated based on the difference between the soil water potential at the soil root interface and in the xylem tissue. The xylem water potential is derived from solving a set of flow equations that describe flow in the root network (Javaux et al., 2008). Nutrient uptake by a segment is simulated as a function of the nutrient concentration at the soil-root interface using a nonlinear Michaelis-Menten equation. An accurate description of the nutrient concentrations gradients around single roots requires a spatial resolution in the sub mm scale and is therefore not feasible for simulations of the entire root system or soil profile. In order to address this problem, a 1-D axisymmetric model (Barber and Cushman, 1981) was used to describe nutrient transport towards a single root segment. The network of connected cylindrical models was coupled to a 3-D regular grid that was used to solve the flow and transport equations at the root system scale. The coupling was done by matching the fluxes across the interfaces of the voxels of the 3-D grid that contain root segments with the fluxes at the outer boundaries of the cylindrical domains and by matching the sink terms in these voxels with uptake by the root segments. To demonstrate the

  15. Root canal irrigants

    PubMed Central

    Kandaswamy, Deivanayagam; Venkateshbabu, Nagendrababu

    2010-01-01

    Successful root canal therapy relies on the combination of proper instrumentation, irrigation, and obturation of the root canal. Of these three essential steps of root canal therapy, irrigation of the root canal is the most important determinant in the healing of the periapical tissues. The primary endodontic treatment goal must thus be to optimize root canal disinfection and to prevent reinfection. In this review of the literature, various irrigants and the interactions between irrigants are discussed. We performed a Medline search for English-language papers published untill July 2010. The keywords used were ‘root canal irrigants’ and ‘endodontic irrigants.’ The reference lists of each article were manually checked for additional articles of relevance. PMID:21217955

  16. Presence and absence of electronic mixing in shorter-chain and longer-chain carotenoids: Assignment of the symmetries of 1Bu- and 3Ag- states located just below the 1Bu+ state

    NASA Astrophysics Data System (ADS)

    Sutresno, Adita; Kakitani, Yoshinori; Zuo, Ping; Li, Chunyong; Koyama, Yasushi; Nagae, Hiroyoshi

    2007-10-01

    In spheroidene (having the number of conjugated double bonds n = 10), stimulated emission was observed from the mixed vibronic levels of 1Bu+(0)+1Bu-(2) and 1Bu+(1)+1Bu-(3), whereas in lycopene, anhydrorhodovibrin and spirilloxanthin ( n = 11-13), stimulated emission, from the pure vibronic levels of 1Bu+(0) and 1Bu+(1). Thus, the 1Bu+ state can mix with the 1Bu- state but not with the 3Ag- state, both being located just below the 1Bu+ state. The presence and absence of the mixing of the neighboring diabatic states support the symmetries of the next low-lying 1Bu- and 3Ag- states.

  17. Fabrication of a Homogeneous, Integrated, and Compact Film of Organic-Inorganic Hybrid Ni(en)3Ag2I4 with Near-Infrared Absorbance and Semiconducting Features.

    PubMed

    Chen, Tian-Yu; Shi, Lei; Yang, Hao; Ren, Xiao-Ming; Xiao, Chen; Jin, Wanqin

    2016-02-01

    The organic-inorganic hybrid crystal Ni(en)3Ag2I4 (where en represents 1,2-ethylenediamine) crystallizes in hexagonal space group P63, in which the AgI4(3-) tetrahedra connect into a diamondlike inorganic framework via sharing of the vertex and the Ni(en)3(2+) octahedra fill in the pores of the framework. UV-vis-near-IR (NIR) spectroscopy disclosed that this hybrid shows intense NIR absorbance centered at ca. 870 nm, and the variable-temperature conductivity measurement revealed that the hybrid is a semiconductor with Ea = 0.46 eV. The electronic band structure of Ni(en)3Ag2I4 was calculated using the density functional theory method, indicating that the NIR absorbance arises from d-d transition within the Ni(2+) cation of Ni(en)3(2+). The homogeneous, compact, and transparent crystalline film of Ni(en)3Ag2I4 was fabricated via a secondary seed growth strategy, which has promising application in NIR devices. PMID:26771538

  18. Root conditioning in periodontology — Revisited

    PubMed Central

    Nanda, Tarun; Jain, Sanjeev; Kaur, Harjit; Kapoor, Daljit; Nanda, Sonia; Jain, Rohit

    2014-01-01

    Objective: Root surfaces of periodontitis-affected teeth are hypermineralized and contaminated with cytotoxic and other biologically active substances. To achieve complete decontamination of the tooth surfaces, various methods including root conditioning following scaling and root planning are present. The main objective of this article is to throw light on the different root conditioning agents used and the goals accomplished by root conditioning in the field of periodontology. Materials and Methods: 20 human maxillary anterior teeth indicated for extraction due to chronic periodontitis were collected and root planned. The teeth were sectioned and specimens were divided into two groups — Group I and II. Group I dentin specimens were treated with EDTA and group II specimens were treated with tetracycline HCl solution at concentration of 10% by active burnishing technique for 3 minutes. The root surface samples were then examined by scanning electron microscope (SEM). Results: The results of the study showed that EDTA and tetracycline HCl were equally effective in removing the smear layer. It was observed that the total and patent dentinal tubules were more in number in teeth treated with tetracycline as compared to EDTA group. However, EDTA was found to be much more effective as root conditioning agent because it enlarged the diameter of dentinal tubules more than that of tetracycline HCl. Conclusion: Results of in-vitro study showed that both the agents are good root conditioning agents if applied in addition to periodontal therapy. However, further studies are required to establish the in-vivo importance of EDTA and tetracycline HCL as root conditioners. PMID:25097414

  19. Comparative behavior of root pathogens in stems and roots of southeastern Pinus species.

    PubMed

    Matusick, George; Nadel, Ryan L; Walker, David M; Hossain, Mohammad J; Eckhardt, Lori G

    2016-04-01

    Root diseases are expected to become a greater threat to trees in the future due to accidental pathogen introductions and predicted climate changes, thus there is a need for accurate and efficient pathogenicity tests. For many root pathogens, these tests have been conducted in stems instead of roots. It, however, remains unclear whether stem and root inoculations are comparable for most fungal species. In this study we compared the growth and damage caused by five root pathogens (Grosmannia huntii, Grosmannia alacris, Leptographium procerum, Leptographium terebrantis, and Heterobasidion irregulare) in root and stem tissue of two Pinus species by inoculating mature trees and tissue amended agar in the laboratory. Most fungal species tested caused greater damage in roots of both pine hosts following inoculation. The relationship between root and stem damage was, however, similar when most combinations of pathogens were compared. These results suggest that although stem inoculations are not suitable for determining the actual damage potential of a given species, they may be viewed as a useful surrogate for root inoculations when comparing the relative pathogenicity of multiple species. When grown on amended agar, fungal species generally had greater growth in stem tissue, contrasting with the findings from tree inoculations. PMID:27020149

  20. Pythium Root Rot

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Pythium root rot is a disease that is found in agricultural and nursery soils throughout the United States and Canada. It is caused by several Pythium species, and the symptoms are typified by leaf or needle chlorosis, stunting, root rot, and plant death. The disease is favored by wet soils, overc...

  1. Root-knot nematodes

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Although root-knot nematodes (Meloidogyne species) can reduce crop yields worldwide, methods for their identification are often difficult to implement. This review summarizes the diagnostic morphological and molecular features for distinguishing the ten major previously described root-knot nematode ...

  2. The Roots of Literacy.

    ERIC Educational Resources Information Center

    Goodman, Yetta M.

    This review of research with children aged two to six on their reading, writing, and oral language development speaks of five roots of a tree of literate life that require nourishment in the soil of a written language environment. The roots discussed are the development of print awareness in situational contexts, the development of print awareness…

  3. Cylindrocarpon root rot

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Cylindrocarpon root rot of alfalfa has been found sporadically in Canada and the northern United States. The etiology of this disease is not fully understood, but the priority for research has not been high because of its infrequent occurrence. The infected area of the root initially has a water-soa...

  4. Irrational Square Roots

    ERIC Educational Resources Information Center

    Misiurewicz, Michal

    2013-01-01

    If students are presented the standard proof of irrationality of [square root]2, can they generalize it to a proof of the irrationality of "[square root]p", "p" a prime if, instead of considering divisibility by "p", they cling to the notions of even and odd used in the standard proof?

  5. Trees and Roots.

    ERIC Educational Resources Information Center

    Jones, Lethonee A.

    Constructing a family history can be significant in helping persons understand and appreciate the root system that supports and sustains them. Oral history can be a valuable resource in family research as Alex Haley demonstrated in writing "Roots." The major difficulty of using oral tradition in tracing a family history is that family members with…

  6. Sugarbeet root aphid on postharvest root storage

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The sugarbeet root aphid (SBRA), Pemphigus betae Doane, is a serious insect pest of sugarbeet in several North American sugarbeet production areas; however, it is rarely an economic pest in the Red River Valley (RRV). In 2012 and 2013, all RRV factory districts were impacted by SBRA outbreaks, and ...

  7. Root Nutrient Foraging1

    PubMed Central

    Giehl, Ricardo F.H.; von Wirén, Nicolaus

    2014-01-01

    During a plant's lifecycle, the availability of nutrients in the soil is mostly heterogeneous in space and time. Plants are able to adapt to nutrient shortage or localized nutrient availability by altering their root system architecture to efficiently explore soil zones containing the limited nutrient. It has been shown that the deficiency of different nutrients induces root architectural and morphological changes that are, at least to some extent, nutrient specific. Here, we highlight what is known about the importance of individual root system components for nutrient acquisition and how developmental and physiological responses can be coupled to increase nutrient foraging by roots. In addition, we review prominent molecular mechanisms involved in altering the root system in response to local nutrient availability or to the plant's nutritional status. PMID:25082891

  8. How to bond to root canal dentin

    NASA Astrophysics Data System (ADS)

    Nica, Luminita; Todea, Carmen; Furtos, Gabriel; Baldea, Bogdan

    2014-01-01

    Bonding to root canal dentin may be difficult due to various factors: the structural characteristic of the root canal dentin, which is different from that of the coronal dentin; the presence of the organic tissue of the dental pulp inside the root canal, which has to be removed during the cleaning-shaping of the root canal system; the smear-layer resulted after mechanical instrumentation, which may interfere with the adhesion of the filling materials; the type of the irrigants used in the cleaning protocol; the type of the sealer and core material used in the obturation of the endodontic space; the type of the materials used for the restoration of the endodontically treated teeth. The influence of the cleaning protocol, of the root canal filling material, of the type of the adhesive system used in the restoration of the treated teeth and of the region of the root canal, on the adhesion of several filling and restorative materials to root canal dentin was evaluated in the push-out bond strength test on 1-mm thick slices of endodontically treated human teeth. The results showed that all these factors have a statistically significant influence on the push-out bond strength. Formation of resin tags between radicular dentin and the investigated materials was observed in some of the samples at SEM analysis.

  9. Root cap-dependent gravitropic U-turn of maize root requires light-induced auxin biosynthesis via the YUC pathway in the root apex.

    PubMed

    Suzuki, Hiromi; Yokawa, Ken; Nakano, Sayuri; Yoshida, Yuriko; Fabrissin, Isabelle; Okamoto, Takashi; Baluška, František; Koshiba, Tomokazu

    2016-08-01

    Gravitropism refers to the growth or movement of plants that is influenced by gravity. Roots exhibit positive gravitropism, and the root cap is thought to be the gravity-sensing site. In some plants, the root cap requires light irradiation for positive gravitropic responses. However, the mechanisms regulating this phenomenon are unknown. We herein report that maize roots exposed to white light continuously for ≥1-2h show increased indole-3-acetic acid (IAA) levels in the root tips, especially in the transition zone (1-3mm from the tip). Treatment with IAA biosynthesis inhibitors yucasin and l-kynurenine prevented any increases in IAA content and root curvature under light conditions. Analyses of the incorporation of a stable isotope label from tryptophan into IAA revealed that some of the IAA in roots was synthesized in the root apex. Furthermore, Zmvt2 and Zmyuc gene transcripts were detected in the root apex. One of the Zmyuc genes (ZM2G141383) was up-regulated by light irradiation in the 0-1mm tip region. Our findings suggest that IAA accumulation in the transition zone is due to light-induced activation of Zmyuc gene expression in the 0-1mm root apex region. Light-induced changes in IAA levels and distributions mediate the maize root gravitropic U-turn. PMID:27307546

  10. Root cap-dependent gravitropic U-turn of maize root requires light-induced auxin biosynthesis via the YUC pathway in the root apex

    PubMed Central

    Suzuki, Hiromi; Yokawa, Ken; Nakano, Sayuri; Yoshida, Yuriko; Fabrissin, Isabelle; Okamoto, Takashi; Baluška, František; Koshiba, Tomokazu

    2016-01-01

    Gravitropism refers to the growth or movement of plants that is influenced by gravity. Roots exhibit positive gravitropism, and the root cap is thought to be the gravity-sensing site. In some plants, the root cap requires light irradiation for positive gravitropic responses. However, the mechanisms regulating this phenomenon are unknown. We herein report that maize roots exposed to white light continuously for ≥1–2h show increased indole-3-acetic acid (IAA) levels in the root tips, especially in the transition zone (1–3mm from the tip). Treatment with IAA biosynthesis inhibitors yucasin and l-kynurenine prevented any increases in IAA content and root curvature under light conditions. Analyses of the incorporation of a stable isotope label from tryptophan into IAA revealed that some of the IAA in roots was synthesized in the root apex. Furthermore, Zmvt2 and Zmyuc gene transcripts were detected in the root apex. One of the Zmyuc genes (ZM2G141383) was up-regulated by light irradiation in the 0–1mm tip region. Our findings suggest that IAA accumulation in the transition zone is due to light-induced activation of Zmyuc gene expression in the 0–1mm root apex region. Light-induced changes in IAA levels and distributions mediate the maize root gravitropic U-turn. PMID:27307546

  11. DMA thermal analysis of yacon tuberous roots

    NASA Astrophysics Data System (ADS)

    Blahovec, J.; Lahodová, M.; Kindl, M.; Fernández, E. C.

    2013-12-01

    Specimens prepared from yacon roots in first two weeks after harvest were tested by dynamic mechanical analysis thermal analysis at temperatures between 30 and 90°C. No differences between different parts of roots were proved. There were indicated some differences in the test parameters that were caused by short time storage of the roots. One source of the differences was loss of water during the roots storage. The measured modulus increased during short time storage. Detailed study of changes of the modulus during the specimen dynamic mechanical analysis test provided information about different development of the storage and loss moduli during the specimen heating. The observed results can be caused by changes in cellular membranes observed earlier during vegetable heating, and by composition changes due to less stable components of yacon like inulin.

  12. Developmental anatomy and branching of roots of four Zeylanidium species (podostemaceae), with implications for evolution of foliose roots.

    PubMed

    Hiyama, Y; Tsukamoto, I; Imaichi, R; Kato, M

    2002-12-01

    Podostemaceae have markedly specialized and diverse roots that are adapted to extreme habitats, such as seasonally submerged or exposed rocks in waterfalls and rapids. This paper describes the developmental anatomy of roots of four species of Zeylanidium, with emphasis on the unusual association between root branching and root-borne adventitious shoots. In Z. subulatum and Z. lichenoides with subcylindrical or ribbon-like roots, the apical meristem distal (exterior) to a shoot that is initiated within the meristem area reduces and loses meristematic activity. This results in a splitting into two meristems that separate the parental root and lateral root (anisotomous dichotomy). In Z. olivaceum with lobed foliose roots, shoots are initiated in the innermost zone of the marginal meristem, and similar, but delayed, meristem reduction usually occurs, producing a parenchyma exterior to shoots located between root lobes. In some extreme cases, due to meristem recovery, root lobing does not occur, so the margin is entire. In Z. maheshwarii with foliose roots, shoots are initiated proximal to the marginal meristem and there is no shoot-root lobe association. Results suggest that during evolution from subcylindrical or ribbon-like roots to foliose roots, reduction of meristem exterior to a shoot was delayed and then arrested as a result of inward shifting of the sites of shoot initiation. The evolutionary reappearance of a protective tissue or root cap in Z. olivaceum and Z. maheshwarii in the Zeylanidium clade is implied, taking into account the reported molecular phylogeny and root-cap development in Hydrobryum. PMID:12451029

  13. Economic strategies of plant absorptive roots vary with root diameter

    NASA Astrophysics Data System (ADS)

    Kong, D. L.; Wang, J. J.; Kardol, P.; Wu, H. F.; Zeng, H.; Deng, X. B.; Deng, Y.

    2016-01-01

    Plant roots typically vary along a dominant ecological axis, the root economics spectrum, depicting a tradeoff between resource acquisition and conservation. For absorptive roots, which are mainly responsible for resource acquisition, we hypothesized that root economic strategies differ with increasing root diameter. To test this hypothesis, we used seven plant species (a fern, a conifer, and five angiosperms from south China) for which we separated absorptive roots into two categories: thin roots (thickness of root cortex plus epidermis < 247 µm) and thick roots. For each category, we analyzed a range of root traits related to resource acquisition and conservation, including root tissue density, different carbon (C), and nitrogen (N) fractions (i.e., extractive, acid-soluble, and acid-insoluble fractions) as well as root anatomical traits. The results showed significant relationships among root traits indicating an acquisition-conservation tradeoff for thin absorptive roots while no such trait relationships were found for thick absorptive roots. Similar results were found when reanalyzing data of a previous study including 96 plant species. The contrasting economic strategies between thin and thick absorptive roots, as revealed here, may provide a new perspective on our understanding of the root economics spectrum.

  14. Deep rooting conferred by DEEPER ROOTING 1 enhances rice yield in paddy fields.

    PubMed

    Arai-Sanoh, Yumiko; Takai, Toshiyuki; Yoshinaga, Satoshi; Nakano, Hiroshi; Kojima, Mikiko; Sakakibara, Hitoshi; Kondo, Motohiko; Uga, Yusaku

    2014-01-01

    To clarify the effect of deep rooting on grain yield in rice (Oryza sativa L.) in an irrigated paddy field with or without fertilizer, we used the shallow-rooting IR64 and the deep-rooting Dro1-NIL (a near-isogenic line homozygous for the Kinandang Patong allele of DEEPER ROOTING 1 (DRO1) in the IR64 genetic background). Although total root length was similar in both lines, more roots were distributed within the lower soil layer of the paddy field in Dro1-NIL than in IR64, irrespective of fertilizer treatment. At maturity, Dro1-NIL showed approximately 10% higher grain yield than IR64, irrespective of fertilizer treatment. Higher grain yield of Dro1-NIL was mainly due to the increased 1000-kernel weight and increased percentage of ripened grains, which resulted in a higher harvest index. After heading, the uptake of nitrogen from soil and leaf nitrogen concentration were higher in Dro1-NIL than in IR64. At the mid-grain-filling stage, Dro1-NIL maintained higher cytokinin fluxes from roots to shoots than IR64. These results suggest that deep rooting by DRO1 enhances nitrogen uptake and cytokinin fluxes at late stages, resulting in better grain filling in Dro1-NIL in a paddy field in this study. PMID:24988911

  15. Grass Rooting the System

    ERIC Educational Resources Information Center

    Perlman, Janice E.

    1976-01-01

    Suggests a taxonomy of the grass roots movement and gives a general descriptive over view of the 60 groups studied with respect to origin, constituency, size, funding, issues, and ideology. (Author/AM)

  16. Reading with Roots

    ERIC Educational Resources Information Center

    Gibson, Margaret I.

    1986-01-01

    Recommends a method of teaching Russian vocabulary that focuses on new words in context and on their structure: root, prefix, suffix, sound changes, and borrowings. Sources for teachers are given in the bibliography. (LMO)

  17. Roots in plant ecology.

    PubMed

    Cody, M L

    1986-09-01

    In 1727 the pioneer vegetation scientist Stephen Hales realized that I much that was of importance to his subject material took place below on ground. A good deal of descriptive work on plant roots and root systems was done in the subsequent two centuries; in crop plants especially, the gross morphology of root systems was well known by the early 20th century. These descriptive studies were extended to natural grasslands by Weaver and his associates and to deserts by Cannon by the second decade of this century, but since that time the study of subterranean growth form appears to have lapsed, as a recent review by Kummerow indicates. Nevertheless, growth form is an important aspect of plant ecology, and subterranean growth form is especially relevant to the study of vegetation in and areas (which is the main subject of this commentary). Moreover, there is a real need for more research to be directed towards understanding plant root systems in general. PMID:21227785

  18. The phenomenology of rooting.

    PubMed

    Kerievsky, Bruce Stephen

    2010-09-01

    This paper examines the attractions of passionate involvement in wanting particular outcomes, which is popularly known as rooting. The author's lifelong personal experience is the source of his analysis, along with the insights provided by spiritual literature and especially the work of Dr. Thomas Hora, with whom the author studied for 30 years. The phrase "choiceless awareness," utilized by J. Krishnamurti, and attained via meditation, is seen as the means of transcending a rooting mode of being in the world. PMID:20165983

  19. The root cap: a short story of life and death.

    PubMed

    Kumpf, Robert P; Nowack, Moritz K

    2015-09-01

    Over 130 years ago, Charles Darwin recognized that sensory functions in the root tip influence directional root growth. Modern plant biology has unravelled that many of the functions that Darwin attributed to the root tip are actually accomplished by a particular organ-the root cap. The root cap surrounds and protects the meristematic stem cells at the growing root tip. Due to this vanguard position, the root cap is predisposed to receive and transmit environmental information to the root proper. In contrast to other plant organs, the root cap shows a rapid turnover of short-lived cells regulated by an intricate balance of cell generation, differentiation, and degeneration. Thanks to these particular features, the root cap is an excellent developmental model system, in which generation, differentiation, and degeneration of cells can be investigated in a conveniently compact spatial and temporal frame. In this review, we give an overview of the current knowledge and concepts of root cap biology, focusing on the model plant Arabidopsis thaliana. PMID:26068468

  20. Neighbor influences on root morphology and mycorrhizal fungus colonization in tallgrass prairie plants

    SciTech Connect

    Jastrow, J.D. Univ. of Illinois, Chicago ); Miller, R.M. )

    1993-03-01

    A field study was conducted across a chronosequence of tallgrass prairie restorations to investigate the influence a plant's neighbor may have on its gross root morphology and association with mycorrhizal fungi. The root systems of a warm-season grass, Andropogon gerardii, and two perennial forbs, Coreopsis tripteris and Solidago altissima, were sampled by excavating soil blocks representing all pairwise inter- and intra-specific combinations of these species. With forb neighbors, Andropogon had higher percentages of its firbrous roots colonized by mycorrhizal fungi than with conspecific neighbors. Andropogon root morphology (as measured by average root radius, specific root length, and root branching) did not vary with neighbor growth form; however, Andropogon roots did become finer as restoration age and root densities increased. For Coreopsis and Solidago, colonization of fibrous roots did not vary with neighbor species, but both forbs had coarser roots with interspecific neighbors than with conspecifics. With interspecific neighbors, Coreopsis almost doubled the number of branches per centimetre of root observed in conspecific pairs. Although some of the variations in colonization and root morphology may be attributable specifically to neighbor root mass, others were related to the overall root mass of the target-neighbor pair. The observed variations in mycorrhizal colonization may be related to increased opportunities for colonization by the fungus that are due not only to higher root densities but also to some sort of interaction between the root systems of Andropogon and the forbs. 44 refs., 2 figs., 2 tabs.

  1. The "Green" Root Beer Laboratory

    ERIC Educational Resources Information Center

    Clary, Renee; Wandersee, James

    2010-01-01

    No, your students will not be drinking green root beer for St. Patrick's Day--this "green" root beer laboratory promotes environmental awareness in the science classroom, and provides a venue for some very sound science content! While many science classrooms incorporate root beer-brewing activities, the root beer lab presented in this article has…

  2. Modelling increased soil cohesion by plant roots with EUROSEM

    NASA Astrophysics Data System (ADS)

    de Baets, S.; Poesen, J.; Torri, D.; Salvador, M. P.

    2009-04-01

    analysis performed with EUROSEM for different vegetation treatments, indicates that runoff and soil loss on root-permeated topsoils are slightly higher as compared to fully covered grass fields or harvested grass fields with some plant residue left, but much smaller as compared to bare topsoils. Moreover, when re-vegetating bare soils, roots are responsible for a large part of the reduction in soil loss and runoff by concentrated flow. Hence, this analysis shows that the contribution of roots to soil cohesion is very important for preventing soil loss and reducing runoff volume. The increase in soil shear strength due to the binding effect of roots on soil particles is two orders of magnitude lower as compared with soil reinforcement achieved when roots mobilize their tensile strength during soil shearing and root breakage.

  3. The root economics spectrum: divergence of absorptive root strategies with root diameter

    NASA Astrophysics Data System (ADS)

    Kong, D.; Wang, J.; Kardol, P.; Wu, H.; Zeng, H.; Deng, X.; Deng, Y.

    2015-08-01

    Plant roots usually vary along a dominant ecological axis, the root economics spectrum (RES), depicting a tradeoff between resource acquisition and conservation. For absorptive roots, which are mainly responsible for resource acquisition, we hypothesized that root strategies as predicted from the RES shift with increasing root diameter. To test this hypothesis, we used seven contrasting plant species for which we separated absorptive roots into two categories: thin roots (< 247 μm diameter) and thick roots. For each category, we analyzed a~range of root traits closely related to resource acquisition and conservation, including root tissue density, carbon (C) and nitrogen (N) fractions as well as root anatomical traits. The results showed that trait relationships for thin absorptive roots followed the expectations from the RES while no clear trait relationships were found in support of the RES for thick absorptive roots. Our results suggest divergence of absorptive root strategies in relation to root diameter, which runs against a single economics spectrum for absorptive roots.

  4. Arabidopsis alcohol dehydrogenase expression in both shoots and roots is conditioned by root growth environment

    NASA Technical Reports Server (NTRS)

    Chung, H. J.; Ferl, R. J.

    1999-01-01

    It is widely accepted that the Arabidopsis Adh (alcohol dehydrogenase) gene is constitutively expressed at low levels in the roots of young plants grown on agar media, and that the expression level is greatly induced by anoxic or hypoxic stresses. We questioned whether the agar medium itself created an anaerobic environment for the roots upon their growing into the gel. beta-Glucuronidase (GUS) expression driven by the Adh promoter was examined by growing transgenic Arabidopsis plants in different growing systems. Whereas roots grown on horizontal-positioned plates showed high Adh/GUS expression levels, roots from vertical-positioned plates had no Adh/GUS expression. Additional results indicate that growth on vertical plates closely mimics the Adh/GUS expression observed for soil-grown seedlings, and that growth on horizontal plates results in induction of high Adh/GUS expression that is consistent with hypoxic or anoxic conditions within the agar of the root zone. Adh/GUS expression in the shoot apex is also highly induced by root penetration of the agar medium. This induction of Adh/GUS in shoot apex and roots is due, at least in part, to mechanisms involving Ca2+ signal transduction.

  5. Root architecture and root and tuber crop productivity.

    PubMed

    Villordon, Arthur Q; Ginzberg, Idit; Firon, Nurit

    2014-07-01

    It is becoming increasingly evident that optimization of root architecture for resource capture is vital for enabling the next green revolution. Although cereals provide half of the calories consumed by humans, root and tuber crops are the second major source of carbohydrates globally. Yet, knowledge of root architecture in root and tuber species is limited. In this opinion article, we highlight what is known about the root system in root and tuber crops, and mark new research directions towards a better understanding of the relation between root architecture and yield. We believe that unraveling the role of root architecture in root and tuber crop productivity will improve global food security, especially in regions with marginal soil fertility and low-input agricultural systems. PMID:24630073

  6. Growth in Turface® clay permits root hair phenotyping along the entire crown root in cereal crops and demonstrates that root hair growth can extend well beyond the root hair zone.

    PubMed

    Goron, Travis L; Watts, Sophia; Shearer, Charles; Raizada, Manish N

    2015-01-01

    In cereal crops, root hairs are reported to function within the root hair zone to carry out important roles in nutrient and water absorption. Nevertheless, these single cells remain understudied due to the practical challenges of phenotyping these delicate structures in large cereal crops growing on soil or other growth systems. Here we present an alternative growth system for examining the root hairs of cereal crops: the use of coarse Turface® clay alongside fertigation. This system allowed for root hairs to be easily visualized along the entire lengths of crown roots in three different cereal crops (maize, wheat, and finger millet). Surprisingly, we observed that the root hairs in these crops continued to grow beyond the canonical root hair zone, with the most root hair growth occurring on older crown root segments. We suggest that the Turface® fertigation system may permit a better understanding of the changing dynamics of root hairs as they age in large plants, and may facilitate new avenues for crop improvement below ground. However, the relevance of this system to field conditions must be further evaluated in other crops. PMID:25889276

  7. Simulating root-induced rhizosphere deformation and its effect on water flow

    NASA Astrophysics Data System (ADS)

    Aravena, J. E.; Ruiz, S.; Mandava, A.; Regentova, E. E.; Ghezzehei, T.; Berli, M.; Tyler, S. W.

    2011-12-01

    Soil structure in the rhizosphere is influenced by root activities, such as mucilage production, microbial activity and root growth. Root growth alters soil structure by moving and deforming soil aggregates, affecting water and nutrient flow from the bulk soil to the root surface. In this study, we utilized synchrotron X-ray micro-tomography (XMT) and finite element analysis to quantify the effect of root-induced compaction on water flow through the rhizosphere to the root surface. In a first step, finite element meshes of structured soil around the root were created by processing rhizosphere XMT images. Then, soil deformation by root expansion was simulated using COMSOL Multiphysics° (Version 4.2) considering the soil an elasto-plastic porous material. Finally, fluid flow simulations were carried out on the deformed mesh to quantify the effect of root-induced compaction on water flow to the root surface. We found a 31% increase in water flow from the bulk soil to the root due to a 56% increase in root diameter. Simulations also show that the increase of root-soil contact area was the dominating factor with respect to the calculated increase in water flow. Increase of inter-aggregate contacts in size and number were observed within a couple of root diameters away from the root surface. But their influence on water flow was, in this case, rather limited compared to the immediate soil-root contact.

  8. Improving predictions of root biomechanical properties, is age a better determinant than diameter?

    NASA Astrophysics Data System (ADS)

    Loades, Kenneth; Hallett, Paul; Lynch, Jonathan; Chimungu, Joseph; Bengough, Anthony

    2014-05-01

    Roots mechanically reinforce many soils. Root tensile strength and stiffness is critical for soil stabilisation with plants potentially providing civil engineers a 'green' alternative for soil stabilisation. Relatively little is known on factors influencing root tensile strength. Through a better understanding of these factors the adoption of 'green engineering' techniques by civil engineers will improve. Existing models are limited in their accuracy due to simplistic assumptions to derive root contributions to the resistance of soil to failure. Current models typically use relationships between strength and diameter, however, there are a number of other factors potentially influencing root biomechanical properties. The effects of root age on biomechanical properties have largely been overlooked. Barley (Hordeum vulgare) was grown under differing soil conditions, waterlogged, moderate mechanical impedance and in unimpeded, control, conditions. The root system was excavated and tensile tests performed on root sections along the length of each root axis. Root tensile strength increased with increasing distance along the root axes in control soil from 0.5 MPa to 7.0 MPa at a distance of 800mm from the root tip and from 1.0 Mpa to 8.0 MPa, 500mm from the root tip when under moderate mechanical impedance. Increases in strength were also observed when plants were subjected to waterlogging with tensile strength increasing from 1.0 MPa to 3.0 MPa, 200mm from the root tip. Young's modulus increased from ~10 MPa at the root tip to ~60 MPa 400mm and 800mm from the root tip in mechanically impeded and control treatments respectively. Distance from root tip explained over 47% of the variance in root tensile strength and 34% of root stiffness. Including root diameter in the model led to further improvements in predicting root properties, explaining ~54% of root strength variance and ~49% of root stiffness. Root age has been shown to improve predictions of root tensile strength

  9. Geoperception in primary and lateral roots of Phaseolus vulgaris (Fabaceae). III. A model to explain the differential georesponsiveness of primary and lateral roots

    NASA Technical Reports Server (NTRS)

    Ransom, J. S.; Moore, R.

    1985-01-01

    Half-tipped primary and lateral roots of Phaseolus vulgaris bend toward the side of the root on which the intact half tip remains. Therefore, tips of lateral and primary roots produce growth effectors capable of inducing gravicurvature. The asymmetrical placement of a tip of a lateral root onto a detipped primary root results in the root bending toward the side of the root onto which the tip was placed. That is, the lesser graviresponsiveness of lateral roots as compared with primary roots is not due to the inability of their caps to produce growth inhibitors. The more pronounced graviresponsiveness of primary roots is positively correlated with the presence of columella tissues that are 3.8 times longer, 1.7 times wider, and 10.5 times more voluminous than the columellas of lateral roots. We propose that the lack of graviresponsiveness exhibited by lateral roots is due to the fact that they (i) produce smaller amounts of the inhibitor than primary (i.e., strongly graviresponsive) roots and (ii) are unable to redistribute the inhibitor so as to be able to create a concentration gradient sufficient to induce a pronounced gravitropic response.

  10. Side-Branching Statistics of Plant Root Networks

    NASA Astrophysics Data System (ADS)

    Pollen, N.; Malamud, B.

    2001-12-01

    Many studies exist that characterise plant root architecture by calculating the fractal dimension of the root network, but few studies quantify the branching characteristics of the root network. This paper examines the Tokunaga side-branching statistics for the root systems of four plants--Sugar Beet (Beta vulgaris), Lucern (Medicago sativa), Common Wheat (Triticum aestivum) and White Clover (Trifolium michelianum)--and compares the resulting statistics to those calculated by similar means (by other authors) for the Kentucky and Powder River drainage basins and several Diffusion Limited Aggregation (DLA) models. The plant root networks studied all contained similar numbers of different order roots, but the side-branching statistics differed, offering one explanation for the differing visual appearance of the branching root networks. The White Clover plant had similar Tokunaga branching statistics to the drainage networks and DLA models. This may be due to the dichotomous root structure of the White Clover plant, which produces a network that is much more similar in appearance to the two drainage networks and DLA models than the other three plants, which had herringbone root. All of the root networks, drainage basins, and DLA models had branching networks that could be quantified well to very well by Tokunaga side-branching statistics. For many years, engineers have avoided implementation of stabilisation schemes involving vegetation, due to the inherent problems involved in the quantification of their dynamic and complex root structures. The use of Tokunaga statistics as a simplifying measure of root branching characteristics, may aid in this aspect, as well as others, such as the modelling of nutrient or water uptake.

  11. Violet root rot

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The fungus causing violet root rot, Helicobasidium brebissonii (anamorph Rhizoctonia crocorum), is widely distributed in Europe and North America but is rarely of much economic importance on alfalfa. The disease has also been reported in Australia, Argentina, and Iran. The disease is characterized b...

  12. "Roots": Medium and Message.

    ERIC Educational Resources Information Center

    Kinnamon, Keneth

    A national telephone survey indicated that audiences rated the television production of "Roots" positively in terms of the following: realistic portrayal of the people and the times; relevance for contemporary race relations; perceived emotional effect; and increased understanding of the psychology of black people. However, a comparison of the…

  13. Stachbotrys Root Rot

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Stachybotrys root rot is caused by Stachybotrys chartarum, a cellulytic saprophytic hyphomycete fungus. The pathogen produces mycotoxins including a host of immunosupressant compounds for human and is one of the causes of the "sick building syndrome." Although S. chartarum is rarely known as a plan...

  14. Great Plains Roots.

    ERIC Educational Resources Information Center

    Frey, Jennifer

    2001-01-01

    Sandy White Hawk, Sicangu Lakota, was adopted by white missionaries as an infant and suffered child abuse. After 33 years, she found her birth family and formed First Nations Orphans Association, which uses songs and ceremonies to help adoptees return to their roots. Until the 1970s, federal agencies and welfare organizations facilitated removal…

  15. The Roots of Reading.

    ERIC Educational Resources Information Center

    Montoya, Colleen, Ed.

    2002-01-01

    This newsletter covers educational issues affecting schools in the Western Regional Educational Laboratory's 4-state region (Arizona, California, Nevada, and Utah) and nationwide. The following articles appear in the Volume 4, Number 1 issue: (1) "The Roots of Reading"; (2) "Breaking the Code: Reading Literacy in K-3"; (3) "Improving Secondary…

  16. Fine root turnover: a story of root production and root phenology

    NASA Astrophysics Data System (ADS)

    McCormack, M. L.; Adams, T. S.; Smithwick, E. A.; Eissenstat, D. M.

    2012-12-01

    Fine root turnover in terrestrial ecosystems partially controls carbon flow from plants into soils as well the amount of roots available for nutrient and water uptake. However, we have poor understanding of basic patterns and variability in fine root turnover. We address this shortfall through the use of a heuristic model and analysis of a multi-year minirhizotron dataset exploring the impacts of fine root phenology and production on fine root turnover rates across 12 temperate tree species in a common garden experiment. The heuristic model allowed us to calculate fine root turnover given different patterns of root production and different fine root lifespans. Using the model we found that patterns of phenology characterized by a single, concentrated peak resulted in slower calculated root turnover rates while broader and bi-modal production patterns resulted in faster turnover rates. For example, for roots with median lifespans of 91 days, estimates of root turnover increased from 1.5 yr-1 to 4.0 yr-1 between the pattern of concentrated root production and the pattern with root production spread equally throughout the year. Turnover rates observed in the common garden ranged from 0.75 yr-1 to 1.33 yr-1 and 0.93 yr-1 to 2.14 yr-1 when calculated as annual production divided by maximum standing root crop or average standing root crop, respectively. Turnover varied significantly across species and interannual variability in root production and turnover was high. Patterns of root phenology observed at the common garden included concentrated root production in late spring as well as several examples of bi-modal and broader patterns of root production with roots produced across spring, summer and fall. Overall, both phenology and total root production impacted estimates of root turnover, particularly for short-lived fine roots with median lifespans of less than one year. Our results suggest that better understanding fine root phenology and production will improve our

  17. Dichotomization of mycorrhizal and NPA-treated short roots in Pinus sylvestris.

    PubMed

    Raudaskoski, Marjatta; Salo, Vanamo

    2008-02-01

    Conifers like Scots pine (Pinus sylvestris) have a complicated root system consisting of morphologically and anatomically different root types, of which the short roots have a very limited ability to elongate. Short roots have an important role in nature since they are able to establish ectomycorrhizal symbiosis, in which the growth of fungal mycelium between the epidermal cells and in the intercellular space between cortical cells leads to formation of dichotomous short roots, which may, through further splitting of the meristem, form coralloid root structures. Dichotomous short roots have been suggested to result from changes in either auxin or ethylene concentrations due to the fungal growth inside the root. NPA, the inhibitor of polar auxin transport, enhances the dichotomization of P. sylvestris short root tips similarly to the fungal growth in the root, thus confirming that auxin plays a role in short root morphogenesis. Ethylene is also known to have an important role in the regulation of root morphogenesis. In future the research dealing with the root system and ectomycorrhiza development in P. sylvestris must take into account that both auxin and ethylene are involved and that there is no contradiction in obtaining the same phenotype with both hormones. The expression analysis of PIN proteins, auxin efflux carriers, could give valuable information about the role of auxin transport in regulating the root growth and morphogenesis of coniferous root system and mycorrhiza. PMID:19704726

  18. The Physiology of Adventitious Roots.

    PubMed

    Steffens, Bianka; Rasmussen, Amanda

    2016-02-01

    Adventitious roots are plant roots that form from any nonroot tissue and are produced both during normal development (crown roots on cereals and nodal roots on strawberry [Fragaria spp.]) and in response to stress conditions, such as flooding, nutrient deprivation, and wounding. They are important economically (for cuttings and food production), ecologically (environmental stress response), and for human existence (food production). To improve sustainable food production under environmentally extreme conditions, it is important to understand the adventitious root development of crops both in normal and stressed conditions. Therefore, understanding the regulation and physiology of adventitious root formation is critical for breeding programs. Recent work shows that different adventitious root types are regulated differently, and here, we propose clear definitions of these classes. We use three case studies to summarize the physiology of adventitious root development in response to flooding (case study 1), nutrient deficiency (case study 2), and wounding (case study 3). PMID:26697895

  19. Evaluating Ecohydrological Theories of Woody Root Distribution in the Kalahari

    PubMed Central

    Bhattachan, Abinash; Tatlhego, Mokganedi; Dintwe, Kebonye; O'Donnell, Frances; Caylor, Kelly K.; Okin, Gregory S.; Perrot, Danielle O.; Ringrose, Susan; D'Odorico, Paolo

    2012-01-01

    The contribution of savannas to global carbon storage is poorly understood, in part due to lack of knowledge of the amount of belowground biomass. In these ecosystems, the coexistence of woody and herbaceous life forms is often explained on the basis of belowground interactions among roots. However, the distribution of root biomass in savannas has seldom been investigated, and the dependence of root biomass on rainfall regime remains unclear, particularly for woody plants. Here we investigate patterns of belowground woody biomass along a rainfall gradient in the Kalahari of southern Africa, a region with consistent sandy soils. We test the hypotheses that (1) the root depth increases with mean annual precipitation (root optimality and plant hydrotropism hypothesis), and (2) the root-to-shoot ratio increases with decreasing mean annual rainfall (functional equilibrium hypothesis). Both hypotheses have been previously assessed for herbaceous vegetation using global root data sets. Our data do not support these hypotheses for the case of woody plants in savannas. We find that in the Kalahari, the root profiles of woody plants do not become deeper with increasing mean annual precipitation, whereas the root-to-shoot ratios decrease along a gradient of increasing aridity. PMID:22470506

  20. Accounting carbon storage in decaying root systems of harvested forests.

    PubMed

    Wang, G Geoff; Van Lear, David H; Hu, Huifeng; Kapeluck, Peter R

    2012-05-01

    Decaying root systems of harvested trees can be a significant component of belowground carbon storage, especially in intensively managed forests where harvest occurs repeatedly in relatively short rotations. Based on destructive sampling of root systems of harvested loblolly pine trees, we estimated that root systems contained about 32% (17.2 Mg ha(-1)) at the time of harvest, and about 13% (6.1 Mg ha(-1)) of the soil organic carbon 10 years later. Based on the published roundwood output data, we estimated belowground biomass at the time of harvest for loblolly-shortleaf pine forests harvested between 1995 and 2005 in South Carolina. We then calculated C that remained in the decomposing root systems in 2005 using the decay function developed for loblolly pine. Our calculations indicate that the amount of C stored in decaying roots of loblolly-shortleaf pine forests harvested between 1995 and 2005 in South Carolina was 7.1 Tg. Using a simple extrapolation method, we estimated 331.8 Tg C stored in the decomposing roots due to timber harvest from 1995 to 2005 in the conterminous USA. To fully account for the C stored in the decomposing roots of the US forests, future studies need (1) to quantify decay rates of coarse roots for major tree species in different regions, and (2) to develop a methodology that can determine C stock in decomposing roots resulting from natural mortality. PMID:22535427

  1. Intentional retention of vital submerged roots in dogs.

    PubMed

    Plata, R L; Kelln, E E; Linda, L

    1976-07-01

    In this study, intact and untreated roots of twelve teeth in three dogs were submerged 2 mm. below the alveolar bone crest. On eight regeneration of alveolar bone was seen in 3 weeks, with complete bone coverage in 5 weeks. A complete lamina dura surrounded the buried roots, the original root canal tissue remained vital, and vessels and other structures now entered (or exited) from both ends. Cementum covered the cut end, making the end similar to a normal apex. Bone failed to regenerate completely over four of the twelve roots. Two of these had dentinal spicules which impeded complete bone coverage (Fig 9). Another was a case of delayed healing due to the early loss of sutures and subsequent infection where a sinus tract developed, connecting the oral environment with the resected root. This led to bone resorption and a partial pulp necrosis. In the fourth case the decreased depth of root burial and subsequent lack of bone cover led to external resorption of the cut dentin. Histologic examination after 12 weeks revealed the regeneration of bone, a regenerated periodontal membrane, and a layer of cementoblasts over the cut and exposed root dentin in a typical manner. This study suggests that when healthy bone and roots are present, particularly in an otherwise edentulous mandible retaining only a few nonrestorable anterior teeth, the roots can be retained in a nonpathologic state by means of a simple surgical technique. PMID:1065830

  2. Root canal retained restorations: 3. Root-face attachments.

    PubMed

    Dummer, P M; Edmunds, D H; Gidden, J R

    1990-10-01

    It has been common practice for many years to use retained roots to provide support and stability for partial or full dentures. The retention of such overdentures is greatly enhanced if the remaining roots are modified and restored with posts and root-face attachments. The final article in this series on root canal retained restorations classifies and describes some of the root-face attachments currently available, and also describes a number of prefabricated post systems with integral overdenture attachments. Guidelines for clinical and laboratory procedures are given. PMID:2097234

  3. Hairy roots are more sensitive to auxin than normal roots.

    PubMed

    Shen, W H; Petit, A; Guern, J; Tempé, J

    1988-05-01

    Responses to auxin of Lotus corniculatus root tips or protoplasts transformed by Agrobacterium rhizogenes strains 15834 and 8196 were compared to those of their normal counterparts. Three different types of experiments were performed, involving long-term, medium-term, or short-term responses to a synthetic auxin, 1-naphthaleneacetic acid. Root tip elongation, proton excretion by root tips, and transmembrane electrical potential difference of root protoplasts were measured as a function of exogenous auxin concentration. The sensitivity of hairy root tips or protoplasts to exogenous auxin was found to be 100-1000 times higher than that of untransformed material. PMID:16593928

  4. Hairy roots are more sensitive to auxin than normal roots

    PubMed Central

    Shen, Wen Hui; Petit, Annik; Guern, Jean; Tempé, Jacques

    1988-01-01

    Responses to auxin of Lotus corniculatus root tips or protoplasts transformed by Agrobacterium rhizogenes strains 15834 and 8196 were compared to those of their normal counterparts. Three different types of experiments were performed, involving long-term, medium-term, or short-term responses to a synthetic auxin, 1-naphthaleneacetic acid. Root tip elongation, proton excretion by root tips, and transmembrane electrical potential difference of root protoplasts were measured as a function of exogenous auxin concentration. The sensitivity of hairy root tips or protoplasts to exogenous auxin was found to be 100-1000 times higher than that of untransformed material. PMID:16593928

  5. Strigolactones Effects on Root Growth

    NASA Astrophysics Data System (ADS)

    Koltai, Hinanit

    2012-07-01

    Strigolactones (SLs) were defined as a new group of plant hormones that suppress lateral shoot branching. Our previous studies suggested SLs to be regulators of root development. SLs were shown to alter root architecture by regulating lateral root formation and to affect root hair elongation in Arabidopsis. Another important effect of SLs on root growth was shown to be associated with root directional growth. Supplementation of SLs to roots led to alterations in root directional growth, whereas associated mutants showed asymmetrical root growth, which was influenced by environmental factors. The regulation by SLs of root development was shown to be conducted via a cross talk of SLs with other plant hormones, including auxin. SLs were shown to regulate auxin transport, and to interfere with the activity of auxin-efflux carriers. Therefore, it might be that SLs are regulators of root directional growth as a result of their ability to regulated auxin transport. However, other evidences suggest a localized effect of SLs on cell division, which may not necessarily be associated with auxin efflux. These and other, recent hypothesis as to the SLs mode of action and the associated root perception and response to environmental factors will be discussed.

  6. Aquaporins and root water relations

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Water is one of the most critical resources limiting plant growth and crop productivity, and root water uptake is an important aspect of plant physiology governing plant water use and stress tolerance. Pathways of root water uptake are complex and are affected by root structure and physiological res...

  7. Springback in root gravitropism.

    PubMed

    Leopold, A C; Wettlaufer, S H

    1989-01-01

    Conditions under which a gravistimulus of Merit corn roots (Zea mays L.) is withdrawn result in a subsequent loss of gravitropic curvature, an effect which we refer to as springback.' This loss of curvature begins within 1 to 10 minutes after removal of the gravistimulus. It occurs regardless of the presence or absence of the root cap. It is insensitive to inhibitors of auxin transport (2,3,5-triiodobenzoic acid, naphthylphthalamic [correction of naphthylphthalmaic] acid) or to added auxin (2,4-dichlorophenoxyacetic acid). Springback is prevented if a clinostat treatment is interjected to neutralize gravistimulation during germination, which suggests that the change in curvature is a response to a memory' effect carried over from a prior gravistimulation. PMID:11537456

  8. Springback in root gravitropism

    NASA Technical Reports Server (NTRS)

    Leopold, A. C.; Wettlaufer, S. H.

    1989-01-01

    Conditions under which a gravistimulus of Merit corn roots (Zea mays L.) is withdrawn result in a subsequent loss of gravitropic curvature, an effect which we refer to as springback.' This loss of curvature begins within 1 to 10 minutes after removal of the gravistimulus. It occurs regardless of the presence or absence of the root cap. It is insensitive to inhibitors of auxin transport (2,3,5-triiodobenzoic acid, naphthylphthalamic [correction of naphthylphthalmaic] acid) or to added auxin (2,4-dichlorophenoxyacetic acid). Springback is prevented if a clinostat treatment is interjected to neutralize gravistimulation during germination, which suggests that the change in curvature is a response to a memory' effect carried over from a prior gravistimulation.

  9. Diagravitropism in corn roots

    NASA Technical Reports Server (NTRS)

    Leopold, A. C.; Wettlaufer, S. H.

    1988-01-01

    The diagravitropic behavior of Merit corn (Zea mays L.) roots grown in darkness provides an opportunity for comparison of two qualitatively different gravitropic systems. As with positive gravitropism, diagravitropism is shown to require the presence of the root cap, have a similar time course for the onset of curvature, and a similar presentation time. In contrast with positive gravitropism, diagravitropism appears to have a more limited requirement for calcium, for it is insensitive to the elution of calcium by EGTA and insensitive to the subsequent addition of a calcium/EGTA complex. These results are interpreted as indicating that whereas the same sensing system is shared by the two types of gravitropism, separate transductive systems are involved, one for diagravitropism, which is relatively independent of calcium, and one for positive gravitropism, which is markedly dependent on calcium.

  10. Control of Arabidopsis Root Development

    PubMed Central

    Petricka, Jalean J.; Winter, Cara M.; Benfey, Philip N.

    2013-01-01

    The Arabidopsis root has been the subject of intense research over the past decades. This research has led to significantly improved understanding of the molecular mechanisms underlying root development. Key insights into the specification of individual cell types, cell patterning, growth and differentiation, branching of the primary root, and responses of the root to the environment have been achieved. Transcription factors and plant hormones play key regulatory roles. Recently, mechanisms involving protein movement and the oscillation of gene expression have also been uncovered. Root gene regulatory networks controlling root development have been reconstructed from genome-wide profiling experiments, revealing novel molecular connections and models. Future refinement of these models will lead to a more complete description of the complex molecular interactions that give rise to a simple growing root. PMID:22404466

  11. Factors influencing the future need for treatment of root surfaces.

    PubMed

    Ettinger, R L; Hand, J S

    1994-10-01

    This paper discusses the current status of root surface caries in the elderly population and the need for treatment of this condition in the future. Although root surface exposure and root caries have been reported for adults at all ages, the people at greatest risk for these conditions are the elderly. In the United States, life expectancy and the population aged 65 years and older has increased substantially, and the proportion of the elderly population who are dentate has increased and is projected to increase further. Utilization of dental services by the elderly is similar to that of employed adults. Interpretation of studies of the prevalence and incidence of root surface caries are difficult due to differences in sampling, definition of lesions, and reporting conventions. Root surface caries prevalence is related to age and continues to be a significant problem for this population as they age. Factors that may affect the future need for treatment are explored. PMID:7986448

  12. Root growth and development in response to CO2 enrichment

    NASA Technical Reports Server (NTRS)

    Day, Frank P., Jr.

    1994-01-01

    A non-destructive technique (minirhizotron observation tubes) was used to assess the effects of CO2 enrichment on root growth and development in experimental plots in a scrub oak-palmetto community at the Kennedy Space Center. Potential effects of CO2 enrichment on plants have a global significance in light of concerns over increasing CO2 concentrations in the Earth's atmosphere. The study at Kennedy Space Center focused on aboveground physiological responses (photosynthetic efficiency and water use efficiency), effects on process rates (litter decomposition and nutrient turnover), and belowground responses of the plants. Belowground dynamics are an exceptionally important component of total plant response but are frequently ignored due to methodological difficulties. Most methods used to examine root growth and development are destructive and, therefore, severely compromise results. Minirhizotrons allow nondestructive observation and quantification of the same soil volume and roots through time. Root length density and root phenology were evaluated for CO2 effects with this nondestructive technique.

  13. Safety of CT-Guided Lumbar Nerve Root Infiltrations

    PubMed Central

    Gossner, Johannes

    2014-01-01

    Summary Selective nerve root infiltrations are frequently performed in patients with lumbar radiculopathy. Computed tomography (CT) is now commonly used for image guidance. Despite the widespread use of CT-guided lumbar nerve root infiltrations few studies have systematically examined the safety of this approach. In a two-year period, 231 lumbar nerve root infiltrations were performed on in-patients and were retrospectively reviewed. No major complications like inflammation (especially spondylodiscitis), large haematomas requiring surgery, severe allergic reactions or spinal ischaemia occurred. In accordance with other published studies, CT-guided lumbar nerve root infiltrations seem to be safe. To minimize the risk of catastrophic neurological complications due to spinal ischaemia, careful needle placement dorsal to the nerve root and the use of a non-particulate corticosteroid, like dexamethasone, are advocated. PMID:25363255

  14. Quantitative Distribution and Metabolism of Auxin Herbicides in Roots 1

    PubMed Central

    Scott, Peter C.; Morris, Roy O.

    1970-01-01

    The internal concentrations of four auxin herbicides— 2,4-dichlorophenoxyacetic acid, dicamba, picloram, and naphthaleneacetic acid—were measured in the roots of treated pea seedlings. Intact seedlings were immersed in solutions of labeled herbicides at concentrations sufficient to produce toxic symptoms (inhibition of elongation, radial enlargement, and lateral root proliferation). Measurements of volume and herbicide content of segments taken sequentially along the root showed that an acropetal concentration gradient of each herbicide was established within the root immediately following treatment. Although there was a net loss of herbicide in the following 24 hours, the gradient was maintained. Initially, the concentration of herbicide in the root tips exceeded that in the external medium. In support of the contention that toxic symptoms due to herbicide treatment are caused by the presence of unmetabolized chemical at the site of action, it was found that metabolism was negligible for all herbicides except naphthaleneacetic acid. PMID:16657529

  15. Redefining fine roots improves understanding of below-ground contributions to terrestrial biosphere processes

    DOE PAGESBeta

    McCormack, M. Luke; Dickie, Ian A.; Eissenstat, David M.; Fahey, Timothy J.; Fernandez, Christopher W.; Guo, Dali; Helmisaari, Heljä-Sisko; Hobbie, Erik A.; Iversen, Colleen M.; Jackson, Robert B.; et al

    2015-03-10

    Fine roots acquire essential soil resources and mediate biogeochemical cycling in terrestrial ecosystems. Estimates of carbon and nutrient allocation to build and maintain these structures remain uncertain due to challenges in consistent measurement and interpretation of fine-root systems. Traditionally, fine roots have been defined as all roots less than or equal to 2 mm in diameter, yet it is now recognized that this approach fails to capture the diversity of form and function observed among fine-root orders. Here, we demonstrate how order-based and functional classification frameworks improve our understanding of dynamic root processes in ecosystems dominated by perennial plants. Inmore » these frameworks, fine roots are separated into either individual root orders or functionally defined into a shorter-lived absorptive pool and a longer-lived transport fine root pool. Using these frameworks, we estimate that fine-root production and turnover represent 22% of terrestrial net primary production globally a ca. 30% reduction from previous estimates assuming a single fine-root pool. Future work developing tools to rapidly differentiate functional fine-root classes, explicit incorporation of mycorrhizal fungi in fine-root studies, and wider adoption of a two-pool approach to model fine roots provide opportunities to better understand belowground processes in the terrestrial biosphere.« less

  16. Can diversity in root architecture explain plant water use efficiency? A modeling study

    PubMed Central

    Tron, Stefania; Bodner, Gernot; Laio, Francesco; Ridolfi, Luca; Leitner, Daniel

    2015-01-01

    Drought stress is a dominant constraint to crop production. Breeding crops with adapted root systems for effective uptake of water represents a novel strategy to increase crop drought resistance. Due to complex interaction between root traits and high diversity of hydrological conditions, modeling provides important information for trait based selection. In this work we use a root architecture model combined with a soil-hydrological model to analyze whether there is a root system ideotype of general adaptation to drought or water uptake efficiency of root systems is a function of specific hydrological conditions. This was done by modeling transpiration of 48 root architectures in 16 drought scenarios with distinct soil textures, rainfall distributions, and initial soil moisture availability. We find that the efficiency in water uptake of root architecture is strictly dependent on the hydrological scenario. Even dense and deep root systems are not superior in water uptake under all hydrological scenarios. Our results demonstrate that mere architectural description is insufficient to find root systems of optimum functionality. We find that in environments with sufficient rainfall before the growing season, root depth represents the key trait for the exploration of stored water, especially in fine soils. Root density, instead, especially near the soil surface, becomes the most relevant trait for exploiting soil moisture when plant water supply is mainly provided by rainfall events during the root system development. We therefore concluded that trait based root breeding has to consider root systems with specific adaptation to the hydrology of the target environment. PMID:26412932

  17. Redefining fine roots improves understanding of belowground contributions to terrestrial biosphere processes

    SciTech Connect

    McCormack, M. Luke; Dickie, Ian A.; Eissenstat, David M.; Fahey, Timothy J.; Fernandez, Christopher W.; Guo, Dali; Helmisaari, Helja -Sisko; Hobbie, Erik A.; Iversen, Colleen M.; Jackson, Robert B.; Leppälammi-Kujansuu, Jaana; Norby, Richard J.; Phillips, Richard P.; Pregitzer, Kurt S.; Pritchard, Seth G.; Rewald, Boris; Zadworny, Marcin

    2015-03-10

    Fine roots acquire essential soil resources and mediate biogeochemical cycling in terrestrial ecosystems. Estimates of carbon and nutrient allocation to build and maintain these structures remain uncertain due to challenges in consistent measurement and interpretation of fine-root systems. We define fine roots as all roots less than or equal to 2 mm in diameter, yet it is now recognized that this approach fails to capture the diversity of form and function observed among fine-root orders. We demonstrate how order-based and functional classification frameworks improve our understanding of dynamic root processes in ecosystems dominated by perennial plants. In these frameworks, fine roots are separated into either individual root orders or functionally defined into a shorter-lived absorptive pool and a longer-lived transport fine root pool. Furthermore, using these frameworks, we estimate that fine-root production and turnover represent 22% of terrestrial net primary production globally a ca. 30% reduction from previous estimates assuming a single fine-root pool. In the future we hope to develop tools to rapidly differentiate functional fine-root classes, explicit incorporation of mycorrhizal fungi in fine-root studies, and wider adoption of a two-pool approach to model fine roots provide opportunities to better understand belowground processes in the terrestrial biosphere.

  18. Redefining fine roots improves understanding of belowground contributions to terrestrial biosphere processes

    DOE PAGESBeta

    McCormack, M. Luke; Dickie, Ian A.; Eissenstat, David M.; Fahey, Timothy J.; Fernandez, Christopher W.; Guo, Dali; Helmisaari, Helja -Sisko; Hobbie, Erik A.; Iversen, Colleen M.; Jackson, Robert B.; et al

    2015-03-10

    Fine roots acquire essential soil resources and mediate biogeochemical cycling in terrestrial ecosystems. Estimates of carbon and nutrient allocation to build and maintain these structures remain uncertain due to challenges in consistent measurement and interpretation of fine-root systems. We define fine roots as all roots less than or equal to 2 mm in diameter, yet it is now recognized that this approach fails to capture the diversity of form and function observed among fine-root orders. We demonstrate how order-based and functional classification frameworks improve our understanding of dynamic root processes in ecosystems dominated by perennial plants. In these frameworks, finemore » roots are separated into either individual root orders or functionally defined into a shorter-lived absorptive pool and a longer-lived transport fine root pool. Furthermore, using these frameworks, we estimate that fine-root production and turnover represent 22% of terrestrial net primary production globally a ca. 30% reduction from previous estimates assuming a single fine-root pool. In the future we hope to develop tools to rapidly differentiate functional fine-root classes, explicit incorporation of mycorrhizal fungi in fine-root studies, and wider adoption of a two-pool approach to model fine roots provide opportunities to better understand belowground processes in the terrestrial biosphere.« less

  19. Unresolving the "real age" of fine roots in forest ecosystems

    NASA Astrophysics Data System (ADS)

    Solly, Emily; Brunner, Ivano; Herzog, Claude; Schöning, Ingo; Schrumpf, Marion; Schweigruber, Fritz; Trumbore, Susan; Hagedorn, Frank

    2016-04-01

    Estimating the turnover time of tree fine roots is crucial for modelling soil organic matter dynamics, but it is one of the biggest challenges in soil ecology and one of the least understood aspects of the belowground carbon cycle. The methods used - ranging from radiocarbon to ingrowth cores and root cameras (minirhizotrons) - yield very diverse pictures of fine root dynamics in forest ecosystems with turnover rates reaching from less than one year to decades. These have huge implications on estimates of carbon allocation to root growth and maintenance and on the persistence of root carbon in soils before it is decomposed or leached. We will present a new approach, involving techniques to study plant anatomy, which unravels the "real age" of fine roots. For a range of forests with diverse water and nutrient limitations located at different latitudes, we investigated the annual growth rings in the secondary xylem of thin transversal sections of fine roots belonging to tree species which form distinct growth rings. In temperate forests we find mean root "ring ages" of 1-2 years while in sub-arctic forests living fine roots can also persist for several years. The robustness of these results were tested by counting the maximum yearly growth rings in tree seedlings of known age and by counting the maximum number of growth rings of fine roots grown in ingrowth cores which were kept in temperate forest soils for one and two years. Radiocarbon estimates of mean "carbon ages", which define the time elapsed since structural carbon was fixed from the atmosphere, instead average around a decade in root systems of temperate forests (mixture of newly produced and older living roots). This dramatic difference may not be related to methodological bias, but to a time lag between C assimilation and production of a portion of fine root tissues due to the storage of older carbon components. The time lag depends very likely on tree species and environmental conditions. We further

  20. Root Mediation of Soil Organic Matter Feedbacks to Climate Change

    NASA Astrophysics Data System (ADS)

    Pendall, E.; Carrillo, Y.; Nie, M.; Osanai, Y.; Nelson, L. C.; Sanderman, J.; Baldock, J.; Hovenden, M.

    2014-12-01

    The importance of plant roots in carbon cycling and especially soil organic matter (SOM) formation and decomposition has been recently recognized. Up to eighty percent of net primary production may be allocated to roots in ecosystems such as grasslands, where they contribute substantially to SOM formation. On the other hand, root induced priming of SOM decomposition has been implicated in the loss of soil C stocks. Thus, the accurate prediction of climate change impacts on C sequestration in soils largely depends upon improved understanding of root-mediated SOM formation and loss in the rhizosphere. This presentation represents an initial attempt to synthesize belowground observations from free-air CO2 enrichment and warming experiments in two grassland ecosystems. We found that the chemical composition of root carbon is similar to particulate organic matter (POM), but not to mineral associated organic matter (MOM), suggesting less microbial modification during formation of POM than MOM. While root biomass and production rates increased under elevated CO2, POM and MOM fractions did not increase proportionally. We also observed increased root decomposition with elevated CO2, which was likely due to increased soil water and substrate availability, since root C quality (determined by NMR) and decomposition (in laboratory incubations) were unaltered. Further, C quality and decomposition rates of roots differed between C3 and C4 functional types. Changes in root morphology with elevated CO2 have altered root functioning. Increased root surface area and length per unit mass allow increased exploration for nutrients, and potentially enhanced root exudation, rhizodeposition, and priming of SOM decomposition. Controlled chamber experiments demonstrated that uptake of N from SOM was linearly correlated with specific root length. Taken together, these results indicate that root morphology, chemistry and function all play roles in affecting soil C storage and loss, and that

  1. Defective secretion of mucilage is the cellular basis for agravitropism in primary roots of Zea mays cv. Ageotropic

    NASA Technical Reports Server (NTRS)

    Miller, I.; Moore, R.

    1990-01-01

    Root caps of primary, secondary, and seminal roots of Z. mays cv. Kys secrete large amounts of mucilage and are in close contact with the root all along the root apex. These roots are strongly graviresponsive. Secondary and seminal roots of Z. mays cv. Ageotropic are also strongly graviresponsive. Similarly, their caps secrete mucilage and closely appress the root all along the root apex. However, primary roots of Z. mays cv. Ageotropic are non-responsive to gravity. Their caps secrete negligible amounts of mucilage and contact the root only at the extreme apex of the root along the calyptrogen. These roots become graviresponsive when their tips are coated with mucilage or mucilage-like materials. Peripheral cells of root caps of roots of Z. mays cv. Kys contain many dictyosomes associated with vesicles that migrate to and fuse with the plasmalemma. Root-cap cells of secondary and seminal (i.e. graviresponsive) roots of Z. mays cv. Ageotropic are similar to those of primary roots of Z. mays cv. Kys. However, root-cap cells of primary (i.e. non-graviresponsive) roots of Z. mays cv. Ageotropic have distended dictyosomal cisternae filled with an electron-dense, granular material. Large vesicles full of this material populate the cells and apparently do not fuse with the plasmalemma. Taken together, these results suggest that non-graviresponsiveness of primary roots of Z. mays cv. Ageotropic results from the lack of apoplastic continuity between the root and the periphery of the root cap. This is a result of negligible secretion of mucilage by cells along the edge of the root cap which, in turn, appears to be due to the malfunctioning of dictyosomes in these cells.

  2. The Roots of Beowulf

    NASA Technical Reports Server (NTRS)

    Fischer, James R.

    2014-01-01

    The first Beowulf Linux commodity cluster was constructed at NASA's Goddard Space Flight Center in 1994 and its origins are a part of the folklore of high-end computing. In fact, the conditions within Goddard that brought the idea into being were shaped by rich historical roots, strategic pressures brought on by the ramp up of the Federal High-Performance Computing and Communications Program, growth of the open software movement, microprocessor performance trends, and the vision of key technologists. This multifaceted story is told here for the first time from the point of view of NASA project management.

  3. Philosophical Roots of Cosmology

    NASA Astrophysics Data System (ADS)

    Ivanovic, M.

    2008-10-01

    We shall consider the philosophical roots of cosmology in the earlier Greek philosophy. Our goal is to answer the question: Are earlier Greek theories of pure philosophical-mythological character, as often philosophers cited it, or they have scientific character. On the bases of methodological criteria, we shall contend that the latter is the case. In order to answer the question about contemporary situation of the relation philosophy-cosmology, we shall consider the next question: Is contemporary cosmology completely independent of philosophical conjectures? The answer demands consideration of methodological character about scientific status of contemporary cosmology. We also consider some aspects of the relation contemporary philosophy-cosmology.

  4. Graviresponsiveness of surgically altered primary roots of Zea mays

    NASA Technical Reports Server (NTRS)

    Maimon, E.; Moore, R.

    1991-01-01

    We examined the gravitropic responses of surgically altered primary roots of Zea mays to determine the route by which gravitropic inhibitors move from the root tip to the elongating zone. Horizontally oriented roots, from which a 1-mm-wide girdle of epidermis plus 2-10 layers of cortex were removed from the apex of the elongating zone, curve downward. However, curvature occurred only apical to the girdle. Filling the girdle with mucilage-like material transmits curvature beyond the girdle. Vertically oriented roots with a half-girdle' (i.e. the epidermis and 2-10 layers of the cortex removed from half of the circumference of the apex of the elongating zone) curve away from the girdle. Inserting the half-girdle at the base of the elongating zone induces curvature towards the girdle. Filling the half-circumference girdles with mucilage-like material reduced curvature significantly. Stripping the epidermis and outer 2-5 layers of cortex from the terminal 1.5 cm of one side of a primary root induces curvature towards the cut, irrespective of the root's orientation to gravity. This effect is not due to desiccation since treated roots submerged in water also curved towards their cut surface. Coating a root's cut surface with a mucilage-like substance minimizes curvature. These results suggest that the outer cell-layers of the root, especially the epidermis, play an important role in root gravicurvature, and the gravitropic signals emanating from the root tip can move apoplastically through mucilage.

  5. Periodontal healing after bonding treatment of vertical root fracture.

    PubMed

    Sugaya, T; Kawanami, M; Noguchi, H; Kato, H; Masaka, N

    2001-08-01

    Vertical root fractures lead to advanced periodontal breakdown with deep periodontal pockets and vertical bone defects. The purpose of this study is to evaluate clinically the periodontal healing of root fracture treatment using adhesive resin cement. In 22 patients, 23 teeth with vertical root fractures were treated with 4-META/MMA-TBB resin cement. Eleven fractured roots were bonded through the root canal (group A) and 12 fractured roots were bonded extra-orally and replanted (group B). All teeth were then restored with full cast crowns (n=20) or coping (n=3). Mean probing depth was 6.6 mm at pre-treatment and 4.4 mm 6 months after the treatment in group A, and 7.4 mm and 4.6 mm, respectively, in group B. Bleeding scores were 100% at pre-treatment and 36.4% after 6 months in group A and 91.7% and 8.3%, respectively in group B. Radiographic bone level was 56.8% at pretreatment and 59.1% after 6 months in group A, and 18.8% and 29.2%, respectively, in group B. Two roots of group A and three roots of group B were extracted due to refracture, deterioration of periodontal inflammation, mobility, and luxation. The remaining roots (n=18) presented no discomfort to the patients and there was no deterioration of periodontal conditions over a mean period of 33 months (range 14-74 months) in group A and over a mean period of 22 months (range 6-48 months) in group B. There was no ankylosed teeth nor was any root resorption detected. The results suggested that the treatment of vertical root fracture using 4-META/MMA-TBB resin has good prognostic possibilities. PMID:11585144

  6. Investigation of the structural aspects in the formation of optical properties of the GeO2-Eu2O3-Ag nanosystem

    NASA Astrophysics Data System (ADS)

    Belushkin, A. V.; Kichanov, S. E.; Kozlenko, D. P.; Lukin, E. V.; Savenko, B. N.; Rakhmanov, S. K.; Shevchenko, G. P.; Gurin, V. S.; Malashkevich, G. E.; Haramus, V.; Pogoreliy, D. K.; Podurets, K. M.

    2010-07-01

    The structural characteristics of the 95GeO2-5Eu2O3, 94.9GeO2-5Eu2O3-0.1Ag, and 99.9GeO2-0.1Ag xerogels annealed in air at the temperature T an = 850°C have been studied using X-ray diffraction and small-angle neutron scattering. It has been established that the significant change in the relative intensity of the 7 F 0 → 5 L 6 and 7 F 0 → 5 H 6 luminescence excitation bands of Eu3+ ions upon introduction of silver correlates with the decrease in the characteristic sizes of polydisperse clusters formed during annealing. The character of the changes in chemical bonds in the system due to the clustering and their role in the formation of optical properties have been analyzed.

  7. Matching roots to their environment

    PubMed Central

    White, Philip J.; George, Timothy S.; Gregory, Peter J.; Bengough, A. Glyn; Hallett, Paul D.; McKenzie, Blair M.

    2013-01-01

    Background Plants form the base of the terrestrial food chain and provide medicines, fuel, fibre and industrial materials to humans. Vascular land plants rely on their roots to acquire the water and mineral elements necessary for their survival in nature or their yield and nutritional quality in agriculture. Major biogeochemical fluxes of all elements occur through plant roots, and the roots of agricultural crops have a significant role to play in soil sustainability, carbon sequestration, reducing emissions of greenhouse gasses, and in preventing the eutrophication of water bodies associated with the application of mineral fertilizers. Scope This article provides the context for a Special Issue of Annals of Botany on ‘Matching Roots to Their Environment’. It first examines how land plants and their roots evolved, describes how the ecology of roots and their rhizospheres contributes to the acquisition of soil resources, and discusses the influence of plant roots on biogeochemical cycles. It then describes the role of roots in overcoming the constraints to crop production imposed by hostile or infertile soils, illustrates root phenotypes that improve the acquisition of mineral elements and water, and discusses high-throughput methods to screen for these traits in the laboratory, glasshouse and field. Finally, it considers whether knowledge of adaptations improving the acquisition of resources in natural environments can be used to develop root systems for sustainable agriculture in the future. PMID:23821619

  8. Arabidopsis thaliana root growth kinetics and lunisolar tidal acceleration.

    PubMed

    Fisahn, Joachim; Yazdanbakhsh, Nima; Klingele, Emile; Barlow, Peter

    2012-07-01

    • All living organisms on Earth are continually exposed to diurnal variations in the gravitational tidal force due to the Sun and Moon. • Elongation of primary roots of Arabidopsis thaliana seedlings maintained at a constant temperature was monitored for periods of up to 14 d using high temporal- and spatial-resolution video imaging. The time-course of the half-hourly elongation rates exhibited an oscillation which was maintained when the roots were placed in the free-running condition of continuous illumination. • Correlation between the root growth kinetics collected from seedlings initially raised under several light protocols but whose roots were subsequently in the free-running condition and the lunisolar tidal profiles enabled us to identify that the latter is the probable exogenous determinant of the rhythmic variation in root elongation rate. Similar observations and correlations using roots of Arabidopsis starch mutants suggest a central function of starch metabolism in the response to the lunisolar tide. The periodicity of the lunisolar tidal signal and the concomitant adjustments in root growth rate indicate that an exogenous timer exists for the modulation of root growth and development. • We propose that, in addition to the sensitivity to Earthly 1G gravity, which is inherent to all animals and plants, there is another type of responsiveness which is attuned to the natural diurnal variations of the lunisolar tidal force. PMID:22583121

  9. Drought alters interactions between root and foliar herbivores.

    PubMed

    Tariq, Muhammad; Rossiter, John T; Wright, Denis J; Staley, Joanna T

    2013-08-01

    Drought can alter plant quality and the strength of trophic interactions between herbivore groups, and is likely to increase in occurrence and severity under climate change. We hypothesized that changes in plant chemistry due to root herbivory and drought stress would affect the performance of a generalist and a specialist aphid species feeding on a Brassica plant. High drought stress increased the negative effect of root herbivory on the performance of both aphid species (30% decrease in fecundity and 15% reduction in intrinsic rate of increase). Aphid performance was greatest at moderate drought stress, though the two species differed in which treatment combination maximized performance. Nitrogen concentration was greatest in high and moderately drought-stressed plants without root herbivores and moderately drought-stressed plants under low root herbivore density, and correlated positively with aphid fecundity for both species. Glucosinolate concentrations increased 62% under combined drought stress and root herbivory, and were positively correlated with extended aphid development time. Root herbivory did not influence relative water content and foliar biomass under normal water regimes but they decreased 24 and 63%, respectively, under high drought stress. This study shows that drought can alter the strength of interactions between foliar and root herbivores, and that plant chemistry is key in mediating such interactions. The two aphid species responded in a broadly similar way to root herbivore and drought-stress treatments, which suggests that generalized predictions of the effects of abiotic factors on interactions between above- and below-ground species may be possible. PMID:23292454

  10. Perennial roots to immortality.

    PubMed

    Munné-Bosch, Sergi

    2014-10-01

    Maximum lifespan greatly varies among species, and it is not strictly determined; it can change with species evolution. Clonal growth is a major factor governing maximum lifespan. In the plant kingdom, the maximum lifespans described for clonal and nonclonal plants vary by an order of magnitude, with 43,600 and 5,062 years for Lomatia tasmanica and Pinus longaeva, respectively. Nonclonal perennial plants (those plants exclusively using sexual reproduction) also present a huge diversity in maximum lifespans (from a few to thousands of years) and even more interestingly, contrasting differences in aging patterns. Some plants show a clear physiological deterioration with aging, whereas others do not. Indeed, some plants can even improve their physiological performance as they age (a phenomenon called negative senescence). This diversity in aging patterns responds to species-specific life history traits and mechanisms evolved by each species to adapt to its habitat. Particularities of roots in perennial plants, such as meristem indeterminacy, modular growth, stress resistance, and patterns of senescence, are crucial in establishing perenniality and understanding adaptation of perennial plants to their habitats. Here, the key role of roots for perennial plant longevity will be discussed, taking into account current knowledge and highlighting additional aspects that still require investigation. PMID:24563283

  11. Cold Temperature Delays Wound Healing in Postharvest Sugarbeet Roots.

    PubMed

    Fugate, Karen K; Ribeiro, Wellington S; Lulai, Edward C; Deckard, Edward L; Finger, Fernando L

    2016-01-01

    Storage temperature affects the rate and extent of wound-healing in a number of root and tuber crops. The effect of storage temperature on wound-healing in sugarbeet (Beta vulgaris L.) roots, however, is largely unknown. Wound-healing of sugarbeet roots was investigated using surface-abraded roots stored at 6 and 12°C for 28 days. Surface abrasions are common injuries of stored roots, and the storage temperatures used are typical of freshly harvested or rapidly cooled roots. Transpiration rate from the wounded surface and root weight loss were used to quantify wound healing. At 12°C, transpiration rate from the wounded surface declined within 14 days and wounded roots lost weight at a rate similar to unwounded controls. At 6°C, transpiration rate from the wounded surface did not decline in the 28 days after injury, and wounded roots lost 44% more weight than controls after 28 days storage. Melanin formation, lignification, and suberization occurred more rapidly at 12°C than at 6°C, and a continuous layer of lignified and suberized cells developed at 12°C, but not at 6°C. Examination of enzyme activities involved in melanin, lignin, and suberin formation indicated that differences in melanin formation at 6 and 12°C were related to differences in polyphenol oxidase activity, although no relationships between suberin or lignin formation and phenylalanine ammonia lyase or peroxidase activity were evident. Wound-induced respiration was initially greater at 12°C than at 6°C. However, with continued storage, respiration rate of wounded roots declined more rapidly at 12°C, and over 28 days, the increase in respiration due to injury was 52% greater in roots stored at 6°C than in roots stored at 12°C. The data indicate that storage at 6°C severely slowed and impaired wound-healing of surface-abraded sugarbeet roots relative to roots stored at 12°C and suggest that postharvest losses may be accelerated if freshly harvested roots are cooled too quickly. PMID

  12. Cold Temperature Delays Wound Healing in Postharvest Sugarbeet Roots

    PubMed Central

    Fugate, Karen K.; Ribeiro, Wellington S.; Lulai, Edward C.; Deckard, Edward L.; Finger, Fernando L.

    2016-01-01

    Storage temperature affects the rate and extent of wound-healing in a number of root and tuber crops. The effect of storage temperature on wound-healing in sugarbeet (Beta vulgaris L.) roots, however, is largely unknown. Wound-healing of sugarbeet roots was investigated using surface-abraded roots stored at 6 and 12°C for 28 days. Surface abrasions are common injuries of stored roots, and the storage temperatures used are typical of freshly harvested or rapidly cooled roots. Transpiration rate from the wounded surface and root weight loss were used to quantify wound healing. At 12°C, transpiration rate from the wounded surface declined within 14 days and wounded roots lost weight at a rate similar to unwounded controls. At 6°C, transpiration rate from the wounded surface did not decline in the 28 days after injury, and wounded roots lost 44% more weight than controls after 28 days storage. Melanin formation, lignification, and suberization occurred more rapidly at 12°C than at 6°C, and a continuous layer of lignified and suberized cells developed at 12°C, but not at 6°C. Examination of enzyme activities involved in melanin, lignin, and suberin formation indicated that differences in melanin formation at 6 and 12°C were related to differences in polyphenol oxidase activity, although no relationships between suberin or lignin formation and phenylalanine ammonia lyase or peroxidase activity were evident. Wound-induced respiration was initially greater at 12°C than at 6°C. However, with continued storage, respiration rate of wounded roots declined more rapidly at 12°C, and over 28 days, the increase in respiration due to injury was 52% greater in roots stored at 6°C than in roots stored at 12°C. The data indicate that storage at 6°C severely slowed and impaired wound-healing of surface-abraded sugarbeet roots relative to roots stored at 12°C and suggest that postharvest losses may be accelerated if freshly harvested roots are cooled too quickly. PMID

  13. [Changes of root biomass, root surface area, and root length density in a Populus cathayana plantation].

    PubMed

    Yan, Hui; Liu, Guang-quan; Li, Hong-sheng

    2010-11-01

    By using soil core method, the biomass, surface area, and length density of roots < or =2 mm and 2-5 mm in diameter in a 50-year-old Populus cathayana plantation on the northern slope of Qinling Mountains were determined during growth season. Among the roots <5 mm in diameter, those < or =2 mm and 2-5 mm in diameter accounted for 77.8% and 22.2% of the total root biomass, respectively. The surface area and length density of the roots < or =2 mm in diameter accounted for more than 97% of the total, and those of the roots 2-5 mm in diameter only occupied less than 3%. The biomass, surface area, and root length density of roots < or =2 mm in diameter decreased with soil depth, while those of the roots 2-5 mm in diameter were the least in 20-30 cm soil layer. The biomass, surface area, and length density of roots < or =2 mm in diameter were significantly correlated with soil organic matter and available nitrogen, but no significant correlations were found for the roots 2-5 mm in diameter. PMID:21360997

  14. Calcium enriched mixture cement for primary molars exhibiting root perforations and extensive root resorption: report of three cases.

    PubMed

    Tavassoli-Hojjati, Sara; Kameli, Somayeh; Rahimian-Emam, Sara; Ahmadyar, Maryam; Asgary, Saeed

    2014-01-01

    In primary molars with root perforations of endodontic origin, tooth extraction and space maintainer are recommended. Calcium-enriched mixture (CEM) cement is a new biomaterial demonstrating favorable sealability/biocompatibility. This report presents a novel treatment modality for cases of primary molar teeth with root perforations associated with a periodontal lesion due to extensive inflammatory root resorption, whereby CEM was used as a perforation repair/pulpotomy biomaterial. Three cases of primary molar root perforations due to inflammatory resorption were selected; all cases were associated with furcal lesions of endodontic origin. Pulp chambers were accessed/irrigated with NaOCl; the root canal orifices were filled with CEM and restored with stainless steel crowns. Clinical/radiographic examinations up to 17 months revealed that all teeth were functional and free of signs/symptoms of infection and all had complete bone healing. Further trials are suggested to confirm CEM use for management of root perforations in primary molars exhibiting root perforation. PMID:24717704

  15. Transgene expression in regenerated roots.

    PubMed

    Malamy, Jocelyn

    2007-01-01

    INTRODUCTIONThis procedure, which uses a root transformation protocol, provides a rapid method for assessing gene expression in Arabidopsis roots. It is useful for testing promoter:reporter gene constructs, for expressing genes, the overexpression of which is lethal in whole plants, and for transforming the roots of plants that are recalcitrant to conventional transformation techniques. The protocol has been used successfully with Ws, No-0, and RLD ecotypes. PMID:21357026

  16. Quantifying root-reinforcement of river bank soils by four Australian tree species

    NASA Astrophysics Data System (ADS)

    Docker, B. B.; Hubble, T. C. T.

    2008-08-01

    The increased shear resistance of soil due to root-reinforcement by four common Australian riparian trees, Casuarina glauca, Eucalyptus amplifolia, Eucalyptus elata and Acacia floribunda, was determined in-situ with a field shear-box. Root pull-out strengths and root tensile-strengths were also measured and used to evaluate the utility of the root-reinforcement estimation models that assume simultaneous failure of all roots at the shear plane. Field shear-box results indicate that tree roots fail progressively rather than simultaneously. Shear-strengths calculated for root-reinforced soil assuming simultaneous root failure, yielded values between 50% and 215% higher than directly measured shear-strengths. The magnitude of the overestimate varies among species and probably results from differences in both the geometry of the root-system and tensile strengths of the root material. Soil blocks under A. floribunda which presents many, well-spread, highly-branched fine roots with relatively higher tensile strength, conformed most closely with root model estimates; whereas E. amplifolia, which presents a few, large, unbranched vertical roots, concentrated directly beneath the tree stem and of relatively low tensile strength, deviated furthest from model-estimated shear-strengths. These results suggest that considerable caution be exercised when applying estimates of increased shear-strength due to root-reinforcement in riverbank stability modelling. Nevertheless, increased soil shear strength provided by tree roots can be calculated by knowledge of the Root Area Ratio ( RAR) at the shear plane. At equivalent RAR values, A. floribunda demonstrated the greatest earth reinforcement potential of the four species studied.

  17. A Split-Root Technique for Measuring Root Water Potential

    PubMed Central

    Adeoye, Kingsley B.; Rawlins, Stephen L.

    1981-01-01

    Water encounters various resistances in moving along a path of decreasing potential energy from the soil through the plant to the atmosphere. The reported relative magnitudes of these pathway resistances vary widely and often these results are conflicting. One reason for such inconsistency is the difficulty in measuring the potential drop across various segments of the soil-plant-atmosphere continuum. The measurement of water potentials at the soil-root interface and in the root xylem of a transpiring plant remains a challenging problem. In the divided root experiment reported here, the measured water potential of an enclosed, nonabsorbing branch of the root system of young corn (Bonanza) plants to infer the water potential of the remaining roots growing in soil was used. The selected root branch of the seedling was grown in a specially constructed Teflon test tube into which a screen-enclosed thermocouple psychrometer was inserted and sealed to monitor the root's water potential. The root and its surrounding atmosphere were assumed to be in vapor equilibrium. Images PMID:16661886

  18. [A case of appendicular supplementary root with external root resorption].

    PubMed

    González Bahillo, J; Martínez Insua, A; Varela Patiño, P; Rivas Lombardero, P; Paz Pumpido, F

    1991-01-01

    The case of a lateral maxillary incisor with a supplementary root fractured by external root resorption, is presented. The role played for the periodontal disease is shown in the clinical and radiographic achievements, and their implications in the pulpal disease. Endodontic therapy was performed and the diagnosis confirmed in the specimen histological research. PMID:1858059

  19. The roots of predictivism.

    PubMed

    Barnes, Eric Christian

    2014-03-01

    In The Paradox of Predictivism (2008, Cambridge University Press) I tried to demonstrate that there is an intimate relationship between predictivism (the thesis that novel predictions sometimes carry more weight than accommodations) and epistemic pluralism (the thesis that one important form of evidence in science is the judgments of other scientists). Here I respond to various published criticisms of some of the key points from Paradox from David Harker, Jarret Leplin, and Clark Glymour. Foci include my account of predictive novelty (endorsement novelty), the claim that predictivism has two roots, the prediction per se and predictive success, and my account of why Mendeleev's predictions carried special weight in confirming the Periodic Law of the Elements. PMID:24984449

  20. [Modeling of Cs-137 vertical soil transfer by a tree root system].

    PubMed

    Bulgakov, A A; Konoplev, A V

    2002-01-01

    A model of 137Cs vertical soil transport by a tree root system is presented. As distinct from other models the radionuclide root uptake is described as a reversible process and depth distribution of roots is given as a function of time. The model was used for prediction of 137Cs release from a surface disposal site located in a territory with conditions similar to that in the Chernobyl NPP exclusion zone. Prediction indicates that during several decades 137Cs transport from the waste layer by the root system of pine can lead to significant contamination of the soil surface due to needles fallout and, probably, ionic leakage from roots. PMID:12449825

  1. New roots for agriculture: exploiting the root phenome

    PubMed Central

    Lynch, Jonathan P.; Brown, Kathleen M.

    2012-01-01

    Recent advances in root biology are making it possible to genetically design root systems with enhanced soil exploration and resource capture. These cultivars would have substantial value for improving food security in developing nations, where yields are limited by drought and low soil fertility, and would enhance the sustainability of intensive agriculture. Many of the phenes controlling soil resource capture are related to root architecture. We propose that a better understanding of the root phenome is needed to effectively translate genetic advances into improved crop cultivars. Elementary, unique root phenes need to be identified. We need to understand the ‘fitness landscape’ for these phenes: how they affect crop performance in an array of environments and phenotypes. Finally, we need to develop methods to measure phene expression rapidly and economically without artefacts. These challenges, especially mapping the fitness landscape, are non-trivial, and may warrant new research and training modalities. PMID:22527403

  2. A novel bioassay using root re-growth in Lemna.

    PubMed

    Park, Areum; Kim, Youn-Jung; Choi, Eun-Mi; Brown, Murray T; Han, Taejun

    2013-09-15

    A new phytotoxicity test method based on root elongation of three Lemna species (Lemna gibba, L. minor, and L. paucicostata) has been developed. Tests with aquatic plants have, typically, favored measurements on fronds (e.g. frond number, area, biomass) rather than on roots, due, in part, to issues associated with handling fragile roots and the time-consuming procedures of selecting roots with identical root lengths. The present method differs in that roots were excised prior to exposure with subsequent measurements on newly developed roots. Results show that there were species-specific difference in sensitivity to the five metals tested (Ag, Cd, Cr, Cu and Hg), with Ag being the most toxic (EC50=5.3-37.6 μgL(-1)) to all three species, and Cr the least toxic for L. gibba and L. minor (1148.3 and 341.8 μgL(-1), respectively) and Cu for L. paucicostata (470.4 μgL(-1)). Direct comparisons were made with measurements of frond area, which were found to be less sensitive. More generally, root re-growth was shown to reflect the toxic responses of all three Lemna species to these five important metals. The root growth bioassay differs from three internationally standardized methods (ISO, OCED and US EPA) in that it is completed in 48 h, the required volume of test solutions is only 3 ml and non-axenic plants are used. Our results show that the Lemna root method is a simple, rapid, cost-effective, sensitive and precise bioassay to assess the toxic risks of metals and has practical application for monitoring municipal and industrial waste waters where metals are common constituents. PMID:23917640

  3. [Microbial decontamination of the root canals of devitalized teeth].

    PubMed

    Kováč, Ján; Kováč, Daniel

    2012-12-01

    The primary goal of endodontic therapy is the reduction or elimination of microorganisms and their by-products from the root canal system. Although a number of instrumentation and irrigation techniques exist, debris is often left behind in the root canal system and proper canal cleaning, shaping, and irrigation are needed to reduce significantly or sometimes even eliminate microorganisms from the canals. Residual microbes in the root canal system are the primary cause of post-treatment apical periodontitis that may persist in both poorly and properly treated cases. Apical periodontitis is a sequel to endodontic infection and manifests itself as the host defense response to microbial challenge emanating from the root canal system to the periapical tissue. It results in local inflammation, resorption of hard tissues, destruction of other periapical tissues, and eventual formation of various histopathological categories of apical periodontitis, commonly referred to as periapical lesions. When the root canal treatment is carried out properly, healing of the periapical lesion usually follows, with bone regeneration. In certain cases, post-treatment apical periodontitis still persists, the condition being commonly referred to as endodontic failure. It is widely acknowledged that such post-treatment apical periodontitis occurs when root canal treatment has not adequately controlled and eliminated the infection. However, complete elimination of microorganisms is not always achieved in clinical practice due to the anatomical complexities of root canals and consequent limitations in access by instruments and irrigants. The use of antimicrobial medication has been advocated to disinfect the root canal system. The recovery of Candida albicans and Enterococcus faecalis is common after failed root canal treatment. Therefore, when testing different antimicrobial agents for efficacy in endodontic treatment, 100% inhibition of the growth of the two microorganisms is required. The

  4. Compensatory Root Water Uptake of Overlapping Root Systems

    NASA Astrophysics Data System (ADS)

    Agee, E.; Ivanov, V. Y.; He, L.; Bisht, G.; Shahbaz, P.; Fatichi, S.; Gough, C. M.; Couvreur, V.; Matheny, A. M.; Bohrer, G.

    2015-12-01

    Land-surface models use simplified representations of root water uptake based on biomass distributions and empirical functions that constrain water uptake during unfavorable soil moisture conditions. These models fail to capture the observed hydraulic plasticity that allows plants to regulate root hydraulic conductivity and zones of active uptake based on local gradients. Recent developments in root water uptake modeling have sought to increase its mechanistic representation by bridging the gap between physically based microscopic models and computationally feasible macroscopic approaches. It remains to be demonstrated whether bulk parameterization of microscale characteristics (e.g., root system morphology and root conductivity) can improve process representation at the ecosystem scale. We employ the Couvreur method of microscopic uptake to yield macroscopic representation in a coupled soil-root model. Using a modified version of the PFLOTRAN model, which represents the 3-D physics of variably saturated soil, we model a one-hectare temperate forest stand under natural and synthetic climatic forcing. Our results show that as shallow soil layers dry, uptake at the tree and stand level shift to deeper soil layers, allowing the transpiration stream demanded by the atmosphere. We assess the potential capacity of the model to capture compensatory root water uptake. Further, the hydraulic plasticity of the root system is demonstrated by the quick response of uptake to rainfall pulses. These initial results indicate a promising direction for land surface models in which significant three-dimensional information from large root systems can be feasibly integrated into the forest scale simulations of root water uptake.

  5. Mucilage exudation facilitates root water uptake in dry soils

    NASA Astrophysics Data System (ADS)

    Ahmed, Mutez; Kroener, Eva; Holz, Maire; Zarebanadkouki, Mohsen; Carminati, Andrea

    2014-05-01

    As plant roots take up water and the soil dries, water depletion is expected to occur in the rhizosphere. However, recent experiments showed that the rhizosphere of lupines was wetter than the bulk soil during root water uptake. On the other hand, after irrigation the rhizosphere remained markedly dry and it rewetted only after one-two days. We hypothesize that: 1) drying/wetting rates of the rhizosphere are controlled by mucilage exuded by roots; 2) mucilage alters the soil hydraulic conductivity: in particular, wet mucilage increases the soil hydraulic conductivity and dry mucilage makes the soil water repellent; 3) mucilage exudation favors root water uptake in dry soil; and 4) dry mucilage limits water loss from roots to dry soils. We used a root pressure probe to measure the hydraulic conductance of artificial roots sitting in soils. As an artificial root we employed a suction cup with a diameter of 2 mm and a length of 45 mm. The root pressure probe gave the hydraulic conductance of the soil-root continuum during pulse experiments in which water was injected into or sucked from the soil. First, we performed experiments with roots in a relatively dry soil with a volumetric water content of 0.03. Then, we repeated the experiment with artificial roots covered with mucilage and then placed into the soil. As a model for mucilage, we collected mucilage from Chia seeds. The water contents (including that of mucilage) in the experiments with and without mucilage were equal. The pressure curves were fitted with a model of root water that includes rhizosphere dynamics. We found that the artificial roots covered with wet mucilage took up water more easily. In a second experimental set-up we measured the outflow of water from the artificial roots into dry soils. We compared two soils: 1) a sandy soil and 2) the same soil wetted with mucilage from Chia seeds and then let dry. The latter soil became water repellent. Due to the water repellency, the outflow of water from

  6. Density of the continental roots: Compositional and thermal contributions

    USGS Publications Warehouse

    Kaban, M.K.; Schwintzer, P.; Artemieva, I.M.; Mooney, W.D.

    2003-01-01

    The origin and evolution of cratonic roots has been debated for many years. Precambrian cratons are underlain by cold lithospheric roots that are chemically depleted. Thermal and petrologic data indicate that Archean roots are colder and more chemically depleted than Proterozoic roots. This observation has led to the hypothesis that the degree of depletion in a lithospheric root depends mostly on its age. Here we test this hypothesis using gravity, thermal, petrologic, and seismic data to quantify differences in the density of cratonic roots globally. In the first step in our analysis we use a global crustal model to remove the crustal contribution to the observed gravity. The result is the mantle gravity anomaly field, which varies over cratonic areas from -100 to +100 mGal. Positive mantle gravity anomalies are observed for cratons in the northern hemisphere: the Baltic shield, East European Platform, and the Siberian Platform. Negative anomalies are observed over cratons in the southern hemisphere: Western Australia, South America, the Indian shield, and Southern Africa. This indicates that there are significant differences in the density of cratonic roots, even for those of similar age. Root density depends on temperature and chemical depletion. In order to separate these effects we apply a lithospheric temperature correction using thermal estimates from a combination of geothermal modeling and global seismic tomography models. Gravity anomalies induced by temperature variations in the uppermost mantle range from -200 to +300 mGal, with the strongest negative anomalies associated with mid-ocean ridges and the strongest positive anomalies associated with cratons. After correcting for thermal effects, we obtain a map of density variations due to lithospheric compositional variations. These maps indicate that the average density decrease due to the chemical depletion within cratonic roots varies from 1.1% to 1.5%, assuming the chemical boundary layer has the same

  7. Determinants and Polynomial Root Structure

    ERIC Educational Resources Information Center

    De Pillis, L. G.

    2005-01-01

    A little known property of determinants is developed in a manner accessible to beginning undergraduates in linear algebra. Using the language of matrix theory, a classical result by Sylvester that describes when two polynomials have a common root is recaptured. Among results concerning the structure of polynomial roots, polynomials with pairs of…

  8. Response of millet and sorghum to a varying water supply around the primary and nodal roots

    PubMed Central

    Rostamza, M.; Richards, R. A.; Watt, M.

    2013-01-01

    Background and Aims Cereals have two root systems. The primary system originates from the embryo when the seed germinates and can support the plant until it produces grain. The nodal system can emerge from stem nodes throughout the plant's life; its value for yield is unclear and depends on the environment. The aim of this study was to test the role of nodal roots of sorghum and millet in plant growth in response to variation in soil moisture. Sorghum and millet were chosen as both are adapted to dry conditions. Methods Sorghum and millet were grown in a split-pot system that allowed the primary and nodal roots to be watered separately. Key Results When primary and nodal roots were watered (12 % soil water content; SWC), millet nodal roots were seven times longer than those of sorghum and six times longer than millet plants in dry treatments, mainly from an 8-fold increase in branch root length. When soil was allowed to dry in both compartments, millet nodal roots responded and grew 20 % longer branch roots than in the well-watered control. Sorghum nodal roots were unchanged. When only primary roots received water, nodal roots of both species emerged and elongated into extremely dry soil (0·6–1·5 % SWC), possibly with phloem-delivered water from the primary roots in the moist inner pot. Nodal roots were thick, short, branchless and vertical, indicating a tropism that was more pronounced in millet. Total nodal root length increased in both species when the dry soil was covered with plastic, suggesting that stubble retention or leaf mulching could facilitate nodal roots reaching deeper moist layers in dry climates. Greater nodal root length in millet than in sorghum was associated with increased shoot biomass, water uptake and water use efficiency (shoot mass per water). Millet had a more plastic response than sorghum to moisture around the nodal roots due to (1) faster growth and progression through ontogeny for earlier nodal root branch length and (2

  9. Glutamate Oxaloacetate Transaminase in Pea Root Nodules 1

    PubMed Central

    Appels, Michiel A.; Haaker, Huub

    1991-01-01

    Glutamate oxaloacetate transaminase (l-glutamate: oxaloacetate aminotransferase, EC 2.6.1.1 [GOT]), a key enzyme in the flow of carbon between the organic acid and amino acid pools in pea (Pisum sativum L.) root nodules, was studied. By ion exchange chromatography, the presence of two forms of GOT in the cytoplasm of pea root nodule cells was established. The major root nodule form was present in only a small quantity in the cytoplasm of root cells. Fractionation of root nodule cell extracts demonstrated that the increase in the GOT activity during nodule development was due to the increase of the activity in the cytoplasm of the plant cells, and not to an increase in activity in the plastids or in the mitochondria. The kinetic properties of the different cytoplasmic forms of GOT were studied. Some of the Km values differed, but calculations indicated that not the kinetic properties but a high concentration of the major root nodule form caused the observed increase in GOT activity in the pea root nodules. It was found that the reactions of the malate/aspartate shuttle are catalyzed by intact bacteroids, and that these reactions can support nitrogen fixation. It is proposed that the main function of the nodule-stimulated cytoplasmic form of GOT is participation in this shuttle. PMID:16668048

  10. Cassava root membrane proteome reveals activities during storage root maturation.

    PubMed

    Naconsie, Maliwan; Lertpanyasampatha, Manassawe; Viboonjun, Unchera; Netrphan, Supatcharee; Kuwano, Masayoshi; Ogasawara, Naotake; Narangajavana, Jarunya

    2016-01-01

    Cassava (Manihot esculenta Crantz) is one of the most important crops of Thailand. Its storage roots are used as food, feed, starch production, and be the important source for biofuel and biodegradable plastic production. Despite the importance of cassava storage roots, little is known about the mechanisms involved in their formation. This present study has focused on comparison of the expression profiles of cassava root proteome at various developmental stages using two-dimensional gel electrophoresis and LC-MS/MS. Based on an anatomical study using Toluidine Blue, the secondary growth was confirmed to be essential during the development of cassava storage root. To investigate biochemical processes occurring during storage root maturation, soluble and membrane proteins were isolated from storage roots harvested from 3-, 6-, 9-, and 12-month-old cassava plants. The proteins with differential expression pattern were analysed and identified to be associated with 8 functional groups: protein folding and degradation, energy, metabolism, secondary metabolism, stress response, transport facilitation, cytoskeleton, and unclassified function. The expression profiling of membrane proteins revealed the proteins involved in protein folding and degradation, energy, and cell structure were highly expressed during early stages of development. Integration of these data along with the information available in genome and transcriptome databases is critical to expand knowledge obtained solely from the field of proteomics. Possible role of identified proteins were discussed in relation with the activities during storage root maturation in cassava. PMID:26547558

  11. Investigation of electrochemical migration on Sn-0.7Cu-0.3Ag-0.03P-0.005Ni solder alloy in HNO{sub 3} solution

    SciTech Connect

    Sarveswaran, C.; Othman, N. K.; Ali, M. Yusuf Tura; Ani, F. Che; Samsudin, Z.

    2015-09-25

    Current issue in lead-free solder in term of its reliability is still under investigation. This high impact research attempts to investigate the electrochemical migration (ECM) on Sn-0.7Cu-0.3Ag-0.03P-0.005Ni solder alloy by Water Drop Test (WDT) in different concentration of HNO{sub 3} solution. The concentration of HNO{sub 3} solution used in this research was 0.05, 0.10, 0.50 and 1M. Optical Microscope (OM), Field Emission Scanning Electron Microscope (FESEM) and Energy Dispersive X-Ray Analysis (EDX) were carried out in order to analysis the ECM behavior based on the growth of dendrite formation after WDT. In general, the results demonstrated that dendrite growth is faster in higher concentration compared with low concentration of HNO{sub 3}. The concentration of HNO{sub 3} solution used has a strong correlation with Mean-Time-To-Failure (MTTF). As the concentration of HNO{sub 3} increases, the MTTF value decreases. Based on the MTTF results the solder alloy in 1M HNO{sub 3} solution is most susceptible to ECM. SnO{sub 2} forms as a corrosion by-product in the samples proved by EDX analysis. The solder alloy poses a high reliability risk in microelectronic devices during operation in 1M HNO{sub 3} solution.

  12. Resistive switching and electrical control of ferromagnetism in a Ag/HfO2/Nb:SrTiO3/Ag resistive random access memory (RRAM) device at room temperature

    NASA Astrophysics Data System (ADS)

    Ren, Shaoqing; Zhu, Gengchang; Xie, Jihao; Bu, Jianpei; Qin, Hongwei; Hu, Jifan

    2016-02-01

    Electrically induced resistive switching and modulated ferromagnetism are simultaneously found in a Ag/HfO2/Nb:SrTiO3/Ag resistive random access memory device at room temperature. The bipolar resistive switching (RS) can be controlled by the modification of a Schottky-like barrier with an electron injection-trapped/detrapped process at the interface of HfO2-Nb:SrTiO3. The multilevel RS transition can be observed in the reset process with larger negative voltage sweepings, which is connected to the different degree of electron detrapping in the interfacial depletion region of the HfO2 layer during the reset process. The origin of the electrical control of room-temperature ferromagnetism may be connected to the change of density of oxygen vacancies in the HfO2 film. The multilevel resistance states and the electric field controlled ferromagnetism have potential for applications in ultrahigh-density storage and magnetic logic device.

  13. “Internal root resorption: An endodontic challenge”: A case series

    PubMed Central

    Mittal, Sunandan; Kumar, Tarun; Mittal, Shifali; Sharma, Jyotika

    2014-01-01

    Management of internal root resorption is a challenge to the endodontists. It may occur in cases with chronic pulpal inflammation, following caries or due to trauma in the form of an accidental blow. Most cases of internal root resorption are seen in anterior teeth, due to their susceptibility to trauma. However, it may be seen in posterior teeth, most likely because of carious involvement of the pulp. Early diagnosis, removal of the cause, proper treatment of the resorbed root is mandatory for successful treatment outcome. This paper is an attempt to summarize the knowledge on internal root resorption and present various cases, which were successfully managed with different treatment modalities. PMID:25506152

  14. Gravisensing in roots

    NASA Astrophysics Data System (ADS)

    Perbal, G.

    1999-01-01

    The mode of gravisensing in higher plants is not yet elucidated. Although, it is generally accepted that the amyloplasts (statoliths) in the root cap cells (statocytes) are responsible for susception of gravity. However, the hypothesis that the whole protoplast acts as gravisusceptor cannot be dismissed. The nature of the sensor that is able to transduce and amplify the mechanical energy into a biochemical factor is even more controversial. Several cell structures could potentially serve as gravireceptors: the endoplasmic reticulum, the actin network, the plasma membrane, or the cytoskeleton associated with this membrane. The nature of the gravisusceptors and gravisensors is discussed by taking into account the characteristics of the gravitropic reaction with respect to the presentation time, the threshold acceleration, the reciprocity rule, the deviation from the sine rule, the movement of the amyloplasts, the pre-inversion effect, the response of starch free and intermediate mutants and the effects of cytochalasin treatment. From this analysis, it can be concluded that both the amyloplasts and the protoplast could be the gravisusceptors, the former being more efficient than the latter since they can focus pressure on limited areas. The receptor should be located in the plasma membrane and could be a stretch-activated ion channel.

  15. Root functional diversity in C3 and C4 grasslands in Hawaii

    NASA Astrophysics Data System (ADS)

    Angelo, C. L.; Pau, S.

    2014-12-01

    Root systems play an integral role in grassland ecosystem functioning due to their resource acquisition and conservation strategies. A considerable gap in our knowledge of C3 and C4 grasslands is our understanding of belowground root functional diversity. Our aim was to determine whether root system traits allowed for the identification of functional strategies of grass species and to see if these traits differed along resource gradients (precipitation and nitrogen). The functional root traits (specific root length, diameter, root tissue density, root length density, and % of fine roots) of nine grass species, four C3 and five C4, were evaluated from root samples collected from field plots at 100 -150 m intervals along an elevation gradient in Hawaii Volcanoes National Park. An analysis of variance found that there were significant differences in individual root trait values between species (P < 0.000) and photosynthetic pathway (P < 0.025). There was also evidence that the relationships between individual root traits and gradient resources were influenced by photosynthetic pathway (P and r2-values for all interactions were < 0.001 and > 0.625, respectively). A principal component analysis (PCA) found that two components accounted for 86 % of the explainable variation in our data. PCA found that C4 species had larger root diameters, whereas, C3 species had higher % of fine roots and specific root lengths. C3 and C4 species diverged less in root tissue density. C3 species had more resource acquisition root traits, while C4 grasses had a more conservative resource strategy. These results have important implications for how grassland ecosystem dynamics may be altered by shifting patterns of C3-C4 grasses with global change.

  16. Root development during soil genesis: effects of root-root interactions, mycorrhizae, and substrate

    NASA Astrophysics Data System (ADS)

    Salinas, A.; Zaharescu, D. G.

    2015-12-01

    A major driver of soil formation is the colonization and transformation of rock by plants and associated microbiota. In turn, substrate chemical composition can also influence the capacity for plant colonization and development. In order to better define these relationships, a mesocosm study was set up to analyze the effect mycorrhizal fungi, plant density and rock have on root development, and to determine the effect of root morphology on weathering and soil formation. We hypothesized that plant-plant and plant-fungi interactions have a stronger influence on root architecture and rock weathering than the substrate composition alone. Buffalo grass (Bouteloua dactyloides) was grown in a controlled environment in columns filled with either granular granite, schist, rhyolite or basalt. Each substrate was given two different treatments, including grass-microbes and grass-microbes-mycorrhizae and incubated for 120, 240, and 480 days. Columns were then extracted and analyzed for root morphology, fine fraction, and pore water major element content. Preliminary results showed that plants produced more biomass in rhyolite, followed by schist, basalt, and granite, indicating that substrate composition is an important driver of root development. In support of our hypothesis, mycorrhizae was a strong driver of root development by stimulating length growth, biomass production, and branching. However, average root length and branching also appeared to decrease in response to high plant density, though this trend was only present among roots with mycorrhizal fungi. Interestingly, fine fraction production was negatively correlated with average root thickness and volume. There is also slight evidence indicating that fine fraction production is more related to substrate composition than root morphology, though this data needs to be further analyzed. Our hope is that the results of this study can one day be applied to agricultural research in order to promote the production of crops

  17. Random root movements in weightlessness.

    PubMed

    Johnsson, A; Karlsson, C; Iversen, T H; Chapman, D K

    1996-02-01

    The dynamics of root growth was studied in weightlessness. In the absence of the gravitropic reference direction during weightlessness, root movements could be controlled by spontaneous growth processes, without any corrective growth induced by the gravitropic system. If truly random of nature, the bending behavior should follow so-called 'random walk' mathematics during weightlessness. Predictions from this hypothesis were critically tested. In a Spacelab ESA-experiment, denoted RANDOM and carried out during the IML-2 Shuttle flight in July 1994, the growth of garden cress (Lepidium sativum) roots was followed by time lapse photography at 1-h intervals. The growth pattern was recorded for about 20 h. Root growth was significantly smaller in weightlessness as compared to gravity (control) conditions. It was found that the roots performed spontaneous movements in weightlessness. The average direction of deviation of the plants consistently stayed equal to zero, despite these spontaneous movements. The average squared deviation increased linearly with time as predicted theoretically (but only for 8-10 h). Autocorrelation calculations showed that bendings of the roots, as determined from the 1-h photographs, were uncorrelated after about a 2-h interval. It is concluded that random processes play an important role in root growth. Predictions from a random walk hypothesis as to the growth dynamics could explain parts of the growth patterns recorded. This test of the hypothesis required microgravity conditions as provided for in a space experiment. PMID:11541141

  18. Hypocotyl adventitious root organogenesis differs from lateral root development

    PubMed Central

    Verstraeten, Inge; Schotte, Sébastien; Geelen, Danny

    2014-01-01

    Wound-induced adventitious root (AR) formation is a requirement for plant survival upon root damage inflicted by pathogen attack, but also during the regeneration of plant stem cuttings for clonal propagation of elite plant varieties. Yet, adventitious rooting also takes place without wounding. This happens for example in etiolated Arabidopsis thaliana hypocotyls, in which AR initiate upon de-etiolation or in tomato seedlings, in which AR initiate upon flooding or high water availability. In the hypocotyl AR originate from a cell layer reminiscent to the pericycle in the primary root (PR) and the initiated AR share histological and developmental characteristics with lateral roots (LRs). In contrast to the PR however, the hypocotyl is a determinate structure with an established final number of cells. This points to differences between the induction of hypocotyl AR and LR on the PR, as the latter grows indeterminately. The induction of AR on the hypocotyl takes place in environmental conditions that differ from those that control LR formation. Hence, AR formation depends on differentially regulated gene products. Similarly to AR induction in stem cuttings, the capacity to induce hypocotyl AR is genotype-dependent and the plant growth regulator auxin is a key regulator controlling the rooting response. The hormones cytokinins, ethylene, jasmonic acid, and strigolactones in general reduce the root-inducing capacity. The involvement of this many regulators indicates that a tight control and fine-tuning of the initiation and emergence of AR exists. Recently, several genetic factors, specific to hypocotyl adventitious rooting in A. thaliana, have been uncovered. These factors reveal a dedicated signaling network that drives AR formation in the Arabidopsis hypocotyl. Here we provide an overview of the environmental and genetic factors controlling hypocotyl-born AR and we summarize how AR formation and the regulating factors of this organogenesis are distinct from LR

  19. Amyloplast Distribution Directs a Root Gravitropic Reaction

    NASA Astrophysics Data System (ADS)

    Kordyum, Elizabeth

    Immobile higher plants are oriented in the gravitational field due to gravitropim that is a physiological growth reaction and consists of three phases: reception of a gravitational signal by statocytes, its transduction to the elongation zone, and finally the organ bending. As it is known, roots are characterized with positive gravitropism, i. e. they grow in the direction of a gravitational vector, stems - with negative gravitropism, i. e. they grow in the direction opposite to a gravitational vector. According to the Nemec’s and Haberlandt’s starch-statolith hypothesis, amyloplasts in diameter of 1.5 - 3 μ in average, which appear to act as gravity sensors and fulfill a statolythic function in the specialized graviperceptive cells - statocytes, sediment in the direction of a gravitational vector in the distal part of a cell, while a nucleus is in the proximal one. There are reasonable data that confirm the amyloplasts-statoliths participation in gravity perception: 1) correlation between the statoliths localization and the site of gravity sensing, 2) significant redistribution (sedimentation) of amyloplasts in statocytes under gravistimulation in comparison with other cell organelles, 3) root decreased ability to react on gravity under starch removal from amyloplasts, 4) starchless Arabidopsis thaliana mutants are agravitropic, 5) amyloplasts-statoliths do not sediment in the absence of the gravitational vector and are in different parts or more concentrated in the center of statocytes. Plant tropisms have been intensively studied for many decades and continue to be investigated. Nevertheless, the mechanisms by which plants do so is still not clearly explained and many questions on gravisensing and graviresponse remain unanswered. Even accepted hypotheses are now being questioned and recent data are critically evaluated. Although the available data show the Ca2+ and cytoskeleton participation in graviperception and signal transduction, the clear evidence

  20. Amyloplast Distribution Directs a Root Gravitropic Reaction

    NASA Astrophysics Data System (ADS)

    Kordyum, Elizabeth

    Immobile higher plants are oriented in the gravitational field due to gravitropim that is a physiological growth reaction and consists of three phases: reception of a gravitational signal by statocytes, its transduction to the elongation zone, and finally the organ bending. As it is known, roots are characterized with positive gravitropism, i. e. they grow in the direction of a gravitational vector, stems - with negative gravitropism, i. e. they grow in the direction opposite to a gravitational vector. According to the Nemec’s and Haberlandt’s starch-statolith hypothesis, amyloplasts in diameter of 1.5 - 3 μ in average, which appear to act as gravity sensors and fulfill a statolythic function in the specialized graviperceptive cells - statocytes, sediment in the direction of a gravitational vector in the distal part of a cell, while a nucleus is in the proximal one. There are reasonable data that confirm the amyloplasts-statoliths participation in gravity perception: 1) correlation between the statoliths localization and the site of gravity sensing, 2) significant redistribution (sedimentation) of amyloplasts in statocytes under gravistimulation in comparison with other cell organelles, 3) root decreased ability to react on gravity under starch removal from amyloplasts, 4) starchless Arabidopsis thaliana mutants are agravitropic, 5) amyloplasts-statoliths do not sediment in the absence of the gravitational vector and are in different parts or more concentrated in the center of statocytes. Plant tropisms have been intensively studied for many decades and continue to be investigated. Nevertheless, the mechanisms by which plants do so is still not clearly explained and many questions on gravisensing and graviresponse remain unanswered. Even accepted hypotheses are now being questioned and recent data are critically evaluated. Although the available data show the Ca2+ and cytoskeleton participation in graviperception and signal transduction, the clear evidence

  1. Towards a multidimensional root trait framework: a tree root review.

    PubMed

    Weemstra, Monique; Mommer, Liesje; Visser, Eric J W; van Ruijven, Jasper; Kuyper, Thomas W; Mohren, Godefridus M J; Sterck, Frank J

    2016-09-01

    Contents 1159 I. 1159 II. 1161 III. 1164 IV. 1166 1167 References 1167 SUMMARY: The search for a root economics spectrum (RES) has been sparked by recent interest in trait-based plant ecology. By analogy with the one-dimensional leaf economics spectrum (LES), fine-root traits are hypothesised to match leaf traits which are coordinated along one axis from resource acquisitive to conservative traits. However, our literature review and meta-level analysis reveal no consistent evidence of an RES mirroring an LES. Instead the RES appears to be multidimensional. We discuss three fundamental differences contributing to the discrepancy between these spectra. First, root traits are simultaneously constrained by various environmental drivers not necessarily related to resource uptake. Second, above- and belowground traits cannot be considered analogues, because they function differently and might not be related to resource uptake in a similar manner. Third, mycorrhizal interactions may offset selection for an RES. Understanding and explaining the belowground mechanisms and trade-offs that drive variation in root traits, resource acquisition and plant performance across species, thus requires a fundamentally different approach than applied aboveground. We therefore call for studies that can functionally incorporate the root traits involved in resource uptake, the complex soil environment and the various soil resource uptake mechanisms - particularly the mycorrhizal pathway - in a multidimensional root trait framework. PMID:27174359

  2. IAA transport in corn roots includes the root cap

    SciTech Connect

    Hasenstein, K.H. )

    1989-04-01

    In earlier reports we concluded that auxin is the growth regulator that controls gravicurvature in roots and that the redistribution of auxin occurs within the root cap. Since other reports did not detect auxin in the root cap, we attempted to confirm the IAA does move through the cap. Agar blocks containing {sup 3}H-IAA were applied to the cut surface of 5 mm long apical segments of primary roots of corn (mo17xB73). After 30 to 120 min radioactivity (RA) of the cap and root tissue was determined. While segments suspended in water-saturated air accumulated very little RA in the cap, application of 0.5 {mu}1 of dist. water to the cap (=controls) increased RA of the cap dramatically. Application to the cap of 0.5 {mu}1 of sorbitol or the Ca{sup 2+} chelator EGTA reduced cap RA to 46% and 70% respectively compared to water, without affecting uptake. Control root segments gravireacted faster than non-treated or osmoticum or EGTA treated segments. The data indicate that both the degree of hydration and calcium control the amount of auxin moving through the cap.

  3. Papilledema Due to Mirtazapine

    PubMed Central

    Ceylan, Mehmet Emin; Evrensel, Alper; Cömert, Gökçe

    2016-01-01

    Background: Mirtazapine is a tetracyclic antidepressant that enhances both noradrenergic and serotonergic transmission. The most common cause of papilledema is increased intracranial pressure due to brain tumor. Also it may occur as a result of idiopathic intracranial hypertension (IIH, pseudo tumor cerebri). Moreover, papilledema may also develop due to retinitis, vasculitis, Graves’ disease, hypertension, leukemia, lymphoma, diabetes mellitus and radiation. Case Report: In this article, a patient who developed papilledema while under treatment with mirtazapine (30 mg/day) for two years and recovered with termination of mirtazapine treatment was discussed to draw the attention of clinicians to this side effect of mirtazapine. Conclusion: Idiopathic intracranial hypertension and papilledema due to psychotropic drugs has been reported in the literature. Mirtazapine may rarely cause peripheral edema. However, papilledema due to mirtazapine has not been previously reported. Although papilledema is a very rare side effect of an antidepressant treatment, fundoscopic examinations of patients must be performed regularly. PMID:27308085

  4. Root hairs improve root penetration, root-soil contact, and phosphorus acquisition in soils of different strength.

    PubMed

    Haling, Rebecca E; Brown, Lawrie K; Bengough, A Glyn; Young, Iain M; Hallett, Paul D; White, Philip J; George, Timothy S

    2013-09-01

    Root hairs are a key trait for improving the acquisition of phosphorus (P) by plants. However, it is not known whether root hairs provide significant advantage for plant growth under combined soil stresses, particularly under conditions that are known to restrict root hair initiation or elongation (e.g. compacted or high-strength soils). To investigate this, the root growth and P uptake of root hair genotypes of barley, Hordeum vulgare L. (i.e. genotypes with and without root hairs), were assessed under combinations of P deficiency and high soil strength. Genotypes with root hairs were found to have an advantage for root penetration into high-strength layers relative to root hairless genotypes. In P-deficient soils, despite a 20% reduction in root hair length under high-strength conditions, genotypes with root hairs were also found to have an advantage for P uptake. However, in fertilized soils, root hairs conferred an advantage for P uptake in low-strength soil but not in high-strength soil. Improved root-soil contact, coupled with an increased supply of P to the root, may decrease the value of root hairs for P acquisition in high-strength, high-P soils. Nevertheless, this work demonstrates that root hairs are a valuable trait for plant growth and nutrient acquisition under combined soil stresses. Selecting plants with superior root hair traits is important for improving P uptake efficiency and hence the sustainability of agricultural systems. PMID:23861547

  5. Substantive due process after Gonzales v. Carhart.

    PubMed

    Calabresi, Steven G

    2008-06-01

    This Article begins in Part I with a doctrinal evaluation of the status of Washington v. Glucksberg ten years after that decision was handed down. Discussion begins with consideration of the Roberts Court's recent decision in Gonzales v. Carhart and then turns to the subject of Justice Kennedy's views in particular on substantive due process. In Part II, the Article goes on to consider whether the Glucksberg test for substantive due process decision making is correct in light of the original meaning of the Fourteenth Amendment. The Article concludes in Parts II and III that Glucksberg is right to confine substantive due process rights recognition to recognition only of those rights that are deeply rooted in history and tradition. PMID:18595213

  6. Power and Roots by Recursion.

    ERIC Educational Resources Information Center

    Aieta, Joseph F.

    1987-01-01

    This article illustrates how questions from elementary finance can serve as motivation for studying high order powers, roots, and exponential functions using Logo procedures. A second discussion addresses a relatively unknown algorithm for the trigonometric exponential and hyperbolic functions. (PK)

  7. Ultrasonic cleaning of root canals

    NASA Astrophysics Data System (ADS)

    Verhaagen, Bram; Boutsioukis, Christos; Jiang, Lei-Meng; Macedo, Ricardo; van der Sluis, Luc; Versluis, Michel

    2011-11-01

    A crucial step during a dental root canal treatment is irrigation, where an antimicrobial fluid is injected into the root canal system to eradicate all bacteria. Agitation of the fluid using an ultrasonically vibrating miniature file has shown significant improvement in cleaning efficacy over conventional syringe irrigation. However, the physical mechanisms underlying the cleaning process, being acoustic streaming, cavitation or chemical activity, and combinations thereof, are not fully understood. High-speed imaging allows us to visualize the flow pattern and cavitation in a root canal model at microscopic scales, at timescales relevant to the cleaning processes (microseconds). MicroPIV measurements of the induced acoustic streaming are coupled to the oscillation characteristics of the file as simulated numerically and measured with a laser vibrometer. The results give new insight into the role of acoustic streaming and the importance of the confinement for the cleaning of root canals.

  8. Root Patterns in Heterogeneous Soils

    NASA Astrophysics Data System (ADS)

    Dara, A.; Moradi, A. B.; Carminati, A.; Oswald, S. E.

    2010-12-01

    Heterogeneous water availability is a typical characteristic of soils in which plant roots grow. Despite the intrinsic heterogeneity of soil-plant water relations, we know little about the ways how plants respond to local environmental quality. Furthermore, increasing use of soil amendments as partial water reservoirs in agriculture calls for a better understanding of plant response to soil heterogeneity. Neutron radiography is a non-invasive imaging that is highly sensitive to water and root distribution and that has high capability for monitoring spatial and temporal soil-plant water relations in heterogeneous systems. Maize plants were grown in 25 x 30 x 1 cm aluminum slabs filled with sandy soil. On the right side of the compartments a commercial water absorbent (Geohumus) was mixed with the soil. Geohumus was distributed with two patterns: mixed homogeneously with the soil, and arranged as 1-cm diameter aggregates (Fig. 1). Two irrigation treatments were applied: sufficient water irrigation and moderate water stress. Neutron radiography started 10 days after planting and has been performed twice a day for one week. At the end of the experiment, the containers were opened, the root were removed and dry root weight in different soil segments were measured. Neutron radiography showed root growth tendency towards Geohumus treated parts and preferential water uptake from Geohumus aggregates. Number and length of fine lateral roots were lower in treated areas compared to the non-treated zone and to control soil. Although corn plants showed an overall high proliferation towards the soil water sources, they decreased production of branches and fine root when water was more available near the main root parts. However there was 50% higher C allocation in roots grown in Geohumus compartments, as derived by the relative dry weight of root. The preferential C allocation in treated regions was higher when plants grew under water stress. We conclude that in addition to the

  9. Root Caries in Older Adults.

    PubMed

    Gregory, Dick; Hyde, Susan

    2015-08-01

    Older adults are retaining an increasing number of natural teeth, and nearly half of all individuals aged 75 and older have experienced root caries. Root caries is a major cause of tooth loss in older adults, and tooth loss is the most significant negative impact on oral health-related quality of life for the elderly. The need for improved preventive efforts and treatment strategies for this population is acute. PMID:26357814

  10. Formation of AgFeO2, α-FeOOH, and Ag2O from mixed Fe(NO3)3-AgNO3 solutions at high pH

    NASA Astrophysics Data System (ADS)

    Krehula, Stjepko; Musić, Svetozar

    2013-07-01

    Precipitation of ternary oxide silver ferrite (AgFeO2), iron oxyhydroxide goethite (α-FeOOH) and silver(I) oxide (Ag2O) from mixed Fe(NO3)3-AgNO3 solutions in a whole [Ag+]:[Fe3+] concentration ratio range at high pH was investigated using X-ray powder diffraction (XRD), 57Fe Mössbauer, FT-IR and UV-Vis-NIR spectroscopies and field emission scanning electron microscopy (FE-SEM). Strong alkalis organic tetramethylammonium hydroxide (TMAH) or inorganic NaOH were used as precipitating agents. Monodispersed lath-like α-FeOOH particles were formed from a pure Fe(NO3)3 solution. The presence of Ag+ ions influenced the formation of the delafossite-type ternary oxide AgFeO2 beside α-FeOOH. The positions of XRD and Mössbauer lines did not suggest any significant incorporation of Ag+ ions into the α-FeOOH structure. AgFeO2 was formed in the precipitation system with the equimolar initial [Ag+]:[Fe3+] concentration ratio. The size and shape of AgFeO2 particles, as well as their structural polytype (2H or 3R), were dependent on reaction temperature, aging time and alkali used. In systems with an excess of Ag+ ions mixtures of AgFeO2 and Ag2O were formed. Single phase Ag2O precipitated from a pure AgNO3 solution.

  11. Breakage of transgenic tobacco roots for monoclonal antibody release in an ultra-scale down shearing device.

    PubMed

    Hassan, Sally; Keshavarz-Moore, Eli; Ma, Julian; Thomas, Colin

    2014-01-01

    Transgenic tobacco roots offer a potential alternative to leaves for monoclonal antibody (MAb) production. A possible method for extraction of MAbs from roots is by homogenization, breaking the roots into fragments to release the antibody. This process was assessed by shearing 10 mm root sections ("roots") in a 24 mL ultra-scale down shearing device, including an impeller with serrated blade edges, intended to mimic the action of a large-scale homogenizer. Size distributions of the remaining intact roots and root fragments were obtained as a function of shearing time. The data suggest that about 36% of the roots could not be broken under the prevailing conditions and, beyond these unbreakable roots, the fragmentation was approximately first order with respect to intact root number. It was postulated that root breakage in such a high shearing device was due to root-impeller collisions and the particle size data suggest that roots colliding with the impeller were completely fragmented into debris particles of the order of 0.1 mm in length. IgG release normalized to release by grinding appeared to lag behind the number of roots that had fragmented, suggesting that a process of leakage followed fragmentation in the ultra-scale down shearing device. PMID:23860965

  12. Genetic analysis of the gravitropic set-point angle in lateral roots of Arabidopsis

    NASA Technical Reports Server (NTRS)

    Mullen, J. L.; Hangarter, R. P.; Kiss, J. Z. (Principal Investigator)

    2003-01-01

    Research on gravity responses in plants has mostly focused on primary roots and shoots, which typically orient to a vertical orientation. However, the distribution of lateral organs and their characteristically non-vertical growth orientation are critical for the determination of plant form. For example, in Arabidopsis, when lateral roots emerge from the primary root, they grow at a nearly horizontal orientation. As they elongate, the roots slowly curve until they eventually reach a vertical orientation. The regulation of this lateral root orientation is an important component affecting overall root system architecture. We found that this change in orientation is not simply due to the onset of gravitropic competence, as non-vertical lateral roots are capable of both positive and negative gravitropism. Thus, the horizontal growth of new lateral roots appears to be determined by what is called the gravitropic set-point angle (GSA). This developmental control of the GSA of lateral roots in Arabidopsis provides a useful system for investigating the components involved in regulating gravitropic responses. Using this system, we have identified several Arabidopsis mutants that have altered lateral root orientations but maintain normal primary root orientation. c2003 COSPAR. Published by Elsevier Ltd. All rights reserved.

  13. Modelling Rooting Depth and Soil Strength in a Drying Soil Profile

    PubMed

    Bengough

    1997-06-01

    A combined root growth and water extraction model is described that simulates the affects of mechanical impedance on root elongation in soil. The model simulates the vertical redistribution of water in the soil profile, water uptake by plant roots, and the effects of decreasing water content on increasing soil strength and decreasing the root elongation rate. The modelling approach is quite general and can be applied to any soil for which a relation can be defined between root elongation and penetrometer resistance. By definition this excludes soils that contain a large proportion of continuous channels through which roots can grow unimpeded. Root elongation rate is calculated as a function of the penetrometer resistance which is determined by the soil water content. Use of the model is illustrated using input data for a sandy loam soil. The results confirm reports in the literature that the depth of water extraction can exceed the rooting depth. The increase in mechanical impedance to root growth due to this water extraction restricted the maximum rooting depth attained, and this limited the depth of soil from which a crop could extract water and nutrients. This study highlighted the lack of published data sets for single crop/soil combinations containing both the strength/root growth information and the hydraulic conductivity characteristics necessary for this type of model. Copyright 1997 Academic Press Limited PMID:9344728

  14. Rootin, a compound that inhibits root development through modulating PIN-mediated auxin distribution.

    PubMed

    Jeong, Suyeong; Kim, Jun-Young; Choi, Hyunmo; Kim, Hyunmin; Lee, Ilhwan; Soh, Moon-Soo; Nam, Hong Gil; Chang, Young-Tae; Lim, Pyung Ok; Woo, Hye Ryun

    2015-04-01

    Plant roots anchor the plant to the soil and absorb water and nutrients for growth. Understanding the molecular mechanisms regulating root development is essential for improving plant survival and agricultural productivity. Extensive molecular genetic studies have provided important information on crucial components for the root development control over the last few decades. However, it is becoming difficult to identify new regulatory components in root development due to the functional redundancy and lethality of genes involved in root development. In this study, we performed a chemical genetic screen to identify novel synthetic compounds that regulate root development in Arabidopsis seedlings. The screen yielded a root growth inhibitor designated as 'rootin', which inhibited Arabidopsis root development by modulating cell division and elongation, but did not significantly affect shoot development. Transcript analysis of phytohormone marker genes revealed that rootin preferentially altered the expression of auxin-regulated genes. Furthermore, rootin reduced the accumulation of PIN1, PIN3, and PIN7 proteins, and affected the auxin distribution in roots, which consequently may lead to the observed defects in root development. Our results suggest that rootin could be utilized to unravel the mechanisms underlying root development and to investigate dynamic changes in PIN-mediated auxin distribution. PMID:25711819

  15. Mechanisms of waterlogging tolerance in wheat - a review of root and shoot physiology.

    PubMed

    Herzog, Max; Striker, Gustavo G; Colmer, Timothy D; Pedersen, Ole

    2016-05-01

    We review the detrimental effects of waterlogging on physiology, growth and yield of wheat. We highlight traits contributing to waterlogging tolerance and genetic diversity in wheat. Death of seminal roots and restriction of adventitious root length due to O2 deficiency result in low root:shoot ratio. Genotypes differ in seminal root anoxia tolerance, but mechanisms remain to be established; ethanol production rates do not explain anoxia tolerance. Root tip survival is short-term, and thereafter, seminal root re-growth upon re-aeration is limited. Genotypes differ in adventitious root numbers and in aerenchyma formation within these roots, resulting in varying waterlogging tolerances. Root extension is restricted by capacity for internal O2 movement to the apex. Sub-optimal O2 restricts root N uptake and translocation to the shoots, with N deficiency causing reduced shoot growth and grain yield. Although photosynthesis declines, sugars typically accumulate in shoots of waterlogged plants. Mn or Fe toxicity might occur in shoots of wheat on strongly acidic soils, but probably not more widely. Future breeding for waterlogging tolerance should focus on root internal aeration and better N-use efficiency; exploiting the genetic diversity in wheat for these and other traits should enable improvement of waterlogging tolerance. PMID:26565998

  16. Effect of parameter choice in root water uptake models - the arrangement of root hydraulic properties within the root architecture affects dynamics and efficiency of root water uptake

    NASA Astrophysics Data System (ADS)

    Bechmann, M.; Schneider, C.; Carminati, A.; Vetterlein, D.; Attinger, S.; Hildebrandt, A.

    2014-10-01

    Detailed three-dimensional models of root water uptake have become increasingly popular for investigating the process of root water uptake. However, they suffer from a lack of information on important parameters, particularly on the spatial distribution of root axial and radial conductivities, which vary greatly along a root system. In this paper we explore how the arrangement of those root hydraulic properties and branching within the root system affects modelled uptake dynamics, xylem water potential and the efficiency of root water uptake. We first apply a simple model to illustrate the mechanisms at the scale of single roots. By using two efficiency indices based on (i) the collar xylem potential ("effort") and (ii) the integral amount of unstressed root water uptake ("water yield"), we show that an optimal root length emerges, depending on the ratio between roots axial and radial conductivity. Young roots with high capacity for radial uptake are only efficient when they are short. Branching, in combination with mature transport roots, enables soil exploration and substantially increases active young root length at low collar potentials. Second, we investigate how this shapes uptake dynamics at the plant scale using a comprehensive three-dimensional root water uptake model. Plant-scale dynamics, such as the average uptake depth of entire root systems, were only minimally influenced by the hydraulic parameterization. However, other factors such as hydraulic redistribution, collar potential, internal redistribution patterns and instantaneous uptake depth depended strongly on the arrangement on the arrangement of root hydraulic properties. Root systems were most efficient when assembled of different root types, allowing for separation of root function in uptake (numerous short apical young roots) and transport (longer mature roots). Modelling results became similar when this heterogeneity was accounted for to some degree (i.e. if the root systems contained between

  17. Root foraging influences plant growth responses to earthworm foraging.

    PubMed

    Cameron, Erin K; Cahill, James F; Bayne, Erin M

    2014-01-01

    Interactions among the foraging behaviours of co-occurring animal species can impact population and community dynamics; the consequences of interactions between plant and animal foraging behaviours have received less attention. In North American forests, invasions by European earthworms have led to substantial changes in plant community composition. Changes in leaf litter have been identified as a critical indirect mechanism driving earthworm impacts on plants. However, there has been limited examination of the direct effects of earthworm burrowing on plant growth. Here we show a novel second pathway exists, whereby earthworms (Lumbricus terrestris L.) impact plant root foraging. In a mini-rhizotron experiment, roots occurred more frequently in burrows and soil cracks than in the soil matrix. The roots of Achillea millefolium L. preferentially occupied earthworm burrows, where nutrient availability was presumably higher than in cracks due to earthworm excreta. In contrast, the roots of Campanula rotundifolia L. were less likely to occur in burrows. This shift in root behaviour was associated with a 30% decline in the overall biomass of C. rotundifolia when earthworms were present. Our results indicate earthworm impacts on plant foraging can occur indirectly via physical and chemical changes to the soil and directly via root consumption or abrasion and thus may be one factor influencing plant growth and community change following earthworm invasion. More generally, this work demonstrates the potential for interactions to occur between the foraging behaviours of plants and soil animals and emphasizes the importance of integrating behavioural understanding in foraging studies involving plants. PMID:25268503

  18. Root Foraging Influences Plant Growth Responses to Earthworm Foraging

    PubMed Central

    Cameron, Erin K.; Cahill, James F.; Bayne, Erin M.

    2014-01-01

    Interactions among the foraging behaviours of co-occurring animal species can impact population and community dynamics; the consequences of interactions between plant and animal foraging behaviours have received less attention. In North American forests, invasions by European earthworms have led to substantial changes in plant community composition. Changes in leaf litter have been identified as a critical indirect mechanism driving earthworm impacts on plants. However, there has been limited examination of the direct effects of earthworm burrowing on plant growth. Here we show a novel second pathway exists, whereby earthworms (Lumbricus terrestris L.) impact plant root foraging. In a mini-rhizotron experiment, roots occurred more frequently in burrows and soil cracks than in the soil matrix. The roots of Achillea millefolium L. preferentially occupied earthworm burrows, where nutrient availability was presumably higher than in cracks due to earthworm excreta. In contrast, the roots of Campanula rotundifolia L. were less likely to occur in burrows. This shift in root behaviour was associated with a 30% decline in the overall biomass of C. rotundifolia when earthworms were present. Our results indicate earthworm impacts on plant foraging can occur indirectly via physical and chemical changes to the soil and directly via root consumption or abrasion and thus may be one factor influencing plant growth and community change following earthworm invasion. More generally, this work demonstrates the potential for interactions to occur between the foraging behaviours of plants and soil animals and emphasizes the importance of integrating behavioural understanding in foraging studies involving plants. PMID:25268503

  19. Plant root-microbe communication in shaping root microbiomes.

    PubMed

    Lareen, Andrew; Burton, Frances; Schäfer, Patrick

    2016-04-01

    A growing body of research is highlighting the impacts root-associated microbial communities can have on plant health and development. These impacts can include changes in yield quantity and quality, timing of key developmental stages and tolerance of biotic and abiotic stresses. With such a range of effects it is clear that understanding the factors that contribute to a plant-beneficial root microbiome may prove advantageous. Increasing demands for food by a growing human population increases the importance and urgency of understanding how microbiomes may be exploited to increase crop yields and reduce losses caused by disease. In addition, climate change effects may require novel approaches to overcoming abiotic stresses such as drought and salinity as well as new emerging diseases. This review discusses current knowledge on the formation and maintenance of root-associated microbial communities and plant-microbe interactions with a particular emphasis on the effect of microbe-microbe interactions on the shape of microbial communities at the root surface. Further, we discuss the potential for root microbiome modification to benefit agriculture and food production. PMID:26729479

  20. Providers get their due.

    PubMed

    Morrissey, J

    1994-11-01

    Providers are getting their due, but only after employing computer software programs to help sort through the complex managed-care contracts they've negotiated. More and more accounting departments are relying on contract management systems to ensure accurate billing. PMID:10138187

  1. Paying Their Dues.

    ERIC Educational Resources Information Center

    Scalzo, Teresa

    1995-01-01

    Some colleges and universities have found that alumni prefer to have ownership of their alumni association, and such a membership program can raise revenues for the institution while providing a valuable communication tool. A strong dues program can work well with an annual giving campaign. A variety of membership structures is possible. Details…

  2. Aphanomyces root rot of alfalfa: widespread distribution of race 2

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The early spring of 2012 with prolonged wet soil conditions in many parts of the country resulted in reports of poor performance of alfalfa due to Aphanomyces root rot (ARR). Varieties with resistance to ARR are available, although fewer varieties have resistance to both race 1 and race 2 of the pat...

  3. Proteome changes induced by aluminum stress in tomato roots

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Growth inhibition in acid soils due to Al stress affects crop production worldwide. To understand mechanisms in sensitive crops that are affected by Al stress, a proteomic analysis of primary tomato root tissue, grown in Alamended and non-amended liquid cultures, was performed. DIGE-SDS-MALDI-TOF-TO...

  4. Characterization of Root-Knot Nematode Resistance in Medicago truncatula

    PubMed Central

    Dhandaydham, Murali; Charles, Lauren; Zhu, Hongyan; Starr, James L.; Huguet, Thierry; Cook, Douglas R.; Prosperi, Jean-Marie; Opperman, Charles

    2008-01-01

    Root knot (Meloidogyne spp.) and cyst (Heterodera and Globodera spp.) nematodes infect all important crop species, and the annual economic loss due to these pathogens exceeds $90 billion. We screened the worldwide accession collection with the root-knot nematodes Meloidogyne incognita, M. arenaria and M. hapla, soybean cyst nematode (SCN-Heterodera glycines), sugar beet cyst nematode (SBCN-Heterodera schachtii) and clover cyst nematode (CLCN-Heterodera trifolii), revealing resistant and susceptible accessions. In the over 100 accessions evaluated, we observed a range of responses to the root-knot nematode species, and a non-host response was observed for SCN and SBCN infection. However, variation was observed with respect to infection by CLCN. While many cultivars including Jemalong A17 were resistant to H. trifolii, cultivar Paraggio was highly susceptible. Identification of M. truncatula as a host for root-knot nematodes and H. trifolii and the differential host response to both RKN and CLCN provide the opportunity to genetically and molecularly characterize genes involved in plant-nematode interaction. Accession DZA045, obtained from an Algerian population, was resistant to all three root-knot nematode species and was used for further studies. The mechanism of resistance in DZA045 appears different from Mi-mediated root-knot nematode resistance in tomato. Temporal analysis of nematode infection showed that there is no difference in nematode penetration between the resistant and susceptible accessions, and no hypersensitive response was observed in the resistant accession even several days after infection. However, less than 5% of the nematode population completed the life cycle as females in the resistant accession. The remainder emigrated from the roots, developed as males, or died inside the roots as undeveloped larvae. Genetic analyses carried out by crossing DZA045 with a susceptible French accession, F83005, suggest that one gene controls resistance in DZA

  5. Fruit removal increases root-zone respiration in cucumber

    PubMed Central

    Kläring, H.-P.; Hauschild, I.; Heißner, A.

    2014-01-01

    Background and Aims Many attempts have been made to avoid the commonly observed fluctuations in fruit initiation and fruit growth in crop plants, particularly in cucumber (Cucumis sativus). Weak sinks of the fruit have been assumed to result in low sink/source ratios for carbohydrates, which may inhibit photosynthesis. This study focuses on the effects of low sink–source ratios on photosynthesis and respiration, and in particular root-zone respiration. Methods Mature fruit-bearing cucumber plants were grown in an aerated nutrient solution. The root containers were designed as open chambers to allow measurement of CO2 gas exchange in the root zone. A similar arrangement in a gas-exchange cuvette enabled simultaneous measurements of CO2 exchange in the shoot and root zones. Key Results Reducing the sinks for carbohydrates by removing all fruit from the plants always resulted in a doubling of CO2 exchange in the root zone within a few hours. However, respiration of the shoot remained unaffected and photosynthesis was only marginally reduced, if at all. Conclusions The results suggest that the increased level of CO2 gas exchange in the root zone after removing the carbon sinks in the shoot is due primarily to the exudation of organic compounds by the roots and their decomposition by micro-organisms. This hypothesis must be tested in further experiments, but if proved correct it would make sense to include carbon leakage by root exudation in cucumber production models. In contrast, inhibition of photosynthesis was measurable only at zero fruit load, a situation that does not occur in cucumber production systems, and models that estimate production can therefore ignore (end-product) inhibition of photosynthesis. PMID:25301817

  6. Quantifying bank retreat rates with exposed tree roots

    NASA Astrophysics Data System (ADS)

    Stotts, S. N.; O'Neal, M. A.; Pizzuto, J. E.

    2013-12-01

    In this study we use a biometric approach based on anatomical changes in the wood of exposed tree roots to quantify riverbank erosion along South River, Va, a site where commonly applied techniques for determining bank erosion rates are either not appropriate due to the required spatial scale of analysis (i.e., erosion pins, traditional surveys, LiDAR analysis) or have failed to detect obvious erosion (i.e. photogrammetric techniques). We sampled 78 exposed roots from 24 study reaches and processed them both macroscopically (2 to 20 times magnification) and microscopically (20 to 100 times magnification), comparing the estimated erosion rates between levels of magnification and to those obtained with photogrammetric techniques. We found no statistical differences between the output of macroscopic and microscopic analyses (t-test, alpha =0.01) but encountered difficulty in identifying the year of root exhumation in some samples. Therefore, we suggest analyzing roots at both levels of magnification to increase confidence and obtain erosion rate estimates from every sample. When comparing exposed root analysis to photogrammetric techniques, the results indicate that the exposed root approach is a feasible and effective method for estimating decadal to centennial scale bank erosion. In addition to producing erosion rates statistically indistinguishable from photogrammetric techniques (t-test, alpha = 0.01), exposed root analysis demonstrated more consistent detection of erosion. The results of this study indicate that exposed tree root analysis is a robust tool that provides insights into decadal scale erosion where other commonly applied techniques may not be appropriate or easily applied.

  7. Root anatomical phenes predict root penetration ability and biomechanical properties in maize (Zea Mays)

    PubMed Central

    Chimungu, Joseph G.; Loades, Kenneth W.; Lynch, Jonathan P.

    2015-01-01

    The ability of roots to penetrate hard soil is important for crop productivity but specific root phenes contributing to this ability are poorly understood. Root penetrability and biomechanical properties are likely to vary in the root system dependent on anatomical structure. No information is available to date on the influence of root anatomical phenes on root penetrability and biomechanics. Root penetration ability was evaluated using a wax layer system. Root tensile and bending strength were evaluated in plant roots grown in the greenhouse and in the field. Root anatomical phenes were found to be better predictors of root penetrability than root diameter per se and associated with smaller distal cortical region cell size. Smaller outer cortical region cells play an important role in stabilizing the root against ovalization and reducing the risk of local buckling and collapse during penetration, thereby increasing root penetration of hard layers. The use of stele diameter was found to be a better predictor of root tensile strength than root diameter. Cortical thickness, cortical cell count, cortical cell wall area and distal cortical cell size were stronger predictors of root bend strength than root diameter. Our results indicate that root anatomical phenes are important predictors for root penetrability of high-strength layers and root biomechanical properties. PMID:25903914

  8. How Can Science Education Foster Students' Rooting?

    ERIC Educational Resources Information Center

    Østergaard, Edvin

    2015-01-01

    The question of how to foster rooting in science education points towards a double challenge; efforts to "prevent" (further) uprooting and efforts to "promote" rooting/re-rooting. Wolff-Michael Roth's paper discusses the uprooting/rooting pair of concepts, students' feeling of alienation and loss of fundamental sense of the…

  9. Singlet internal conversion processes in the order of 1Bu+→3Ag-→1Bu-→2Ag-→1Ag- in all- trans-spheroidene and lycopene as revealed by subpicosecond time-resolved Raman spectroscopy

    NASA Astrophysics Data System (ADS)

    Rondonuwu, Ferdy S.; Kakitani, Yoshinori; Tamura, Hiroshi; Koyama, Yasushi

    2006-09-01

    Key Raman lines ascribable to the 1Bu+, 3Ag-, 1Bu- and 2Ag- states were identified in the subpicosecond time-resolved Raman spectra of spheroidene and lycopene having 10 and 11 conjugated double bonds, respectively. The sequential rise-and-decay of the key Raman lines showed the internal conversion processes of 1Bu+→3Ag-→1Bu-→2Ag-→1Ag- (ground). The time constant in each step of internal conversion reflects the energy gap between the relevant states that had been determined by measurement of resonance - Raman excitation profiles [K. Furuichi, T. Sashima, Y. Koyama, Chem. Phys. Lett. 356 (2002) 547].

  10. RESPONSE OF SOYBEAN ISOLINES DIFFERING IN PHYTOPHTHORA ROOT ROT RESISTANCE TO FIELD FLOODING

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Phytophthora root rot (PRR) and flooding in soybeans is often a problem on heavy clays or poorly drained soils. Phytophthora root rot (PRR) resistance could decrease losses due to flooding? Alleles for PRR resistance in soybean have been found at eight loci with some loci having more than one all...

  11. Stem and root carbohydrate dynamics in modern vs obsolete cotton cultivars

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The lower stem and root starch reserve is a necessary source of photoassimilates for completion of reproductive development in cotton. The objectives of this research was to determine if carbohydrate levels in the lower stem and roots have been altered due to over 100 years of breeding efforts. In ...

  12. ROOT GROWTH AND TURNOVER IN DIFFERENT AGED PONDEROSA PINE STANDS IN OREGON, USA

    EPA Science Inventory

    The impacts of pollution and climate change on soil carbon dynamics are poorly understood, in part due to a lack of information regarding root production and turnover in natural ecosystems. In order to examine how root dynamics change with stand age in ponderosa pine forests (...

  13. MES Buffer Affects Arabidopsis Root Apex Zonation and Root Growth by Suppressing Superoxide Generation in Root Apex

    PubMed Central

    Kagenishi, Tomoko; Yokawa, Ken; Baluška, František

    2016-01-01

    In plants, growth of roots and root hairs is regulated by the fine cellular control of pH and reactive oxygen species (ROS). MES, 2-(N-morpholino)ethanesulfonic acid as one of the Good’s buffers has broadly been used for buffering medium, and it is thought to suit for plant growth with the concentration at 0.1% (w/v) because the buffer capacity of MES ranging pH 5.5–7.0 (for Arabidopsis, pH 5.8). However, many reports have shown that, in nature, roots require different pH values on the surface of specific root apex zones, namely meristem, transition zone, and elongation zone. Despite the fact that roots always grow on a media containing buffer molecule, little is known about impact of MES on root growth. Here, we have checked the effects of different concentrations of MES buffer using growing roots of Arabidopsis thaliana. Our results show that 1% of MES significantly inhibited root growth, the number of root hairs and length of meristem, whereas 0.1% promoted root growth and root apex area (region spanning from the root tip up to the transition zone). Furthermore, superoxide generation in root apex disappeared at 1% of MES. These results suggest that MES disturbs normal root morphogenesis by changing the ROS homeostasis in root apex. PMID:26925066

  14. MES Buffer Affects Arabidopsis Root Apex Zonation and Root Growth by Suppressing Superoxide Generation in Root Apex.

    PubMed

    Kagenishi, Tomoko; Yokawa, Ken; Baluška, František

    2016-01-01

    In plants, growth of roots and root hairs is regulated by the fine cellular control of pH and reactive oxygen species (ROS). MES, 2-(N-morpholino)ethanesulfonic acid as one of the Good's buffers has broadly been used for buffering medium, and it is thought to suit for plant growth with the concentration at 0.1% (w/v) because the buffer capacity of MES ranging pH 5.5-7.0 (for Arabidopsis, pH 5.8). However, many reports have shown that, in nature, roots require different pH values on the surface of specific root apex zones, namely meristem, transition zone, and elongation zone. Despite the fact that roots always grow on a media containing buffer molecule, little is known about impact of MES on root growth. Here, we have checked the effects of different concentrations of MES buffer using growing roots of Arabidopsis thaliana. Our results show that 1% of MES significantly inhibited root growth, the number of root hairs and length of meristem, whereas 0.1% promoted root growth and root apex area (region spanning from the root tip up to the transition zone). Furthermore, superoxide generation in root apex disappeared at 1% of MES. These results suggest that MES disturbs normal root morphogenesis by changing the ROS homeostasis in root apex. PMID:26925066

  15. The bHLH transcription factor SPATULA regulates root growth by controlling the size of the root meristem

    PubMed Central

    2013-01-01

    Background The Arabidopsis thaliana gene SPATULA (SPT), encoding a bHLH transcription factor, was originally identified for its role in pistil development. SPT is necessary for the growth and development of all carpel margin tissues including the style, stigma, septum and transmitting tract. Since then, it has been shown to have pleiotropic roles during development, including restricting the meristematic region of the leaf primordia and cotyledon expansion. Although SPT is expressed in roots, its role in this organ has not been investigated. Results An analysis of embryo and root development showed that loss of SPT function causes an increase in quiescent center size in both the embryonic and postembryonic stem cell niches. In addition, root meristem size is larger due to increased division, which leads to a longer primary root. spt mutants exhibit other pleiotropic developmental phenotypes, including more flowers, shorter internodes and an extended flowering period. Genetic and molecular analysis suggests that SPT regulates cell proliferation in parallel to gibberellic acid as well as affecting auxin accumulation or transport. Conclusions Our data suggest that SPT functions in growth control throughout sporophytic growth of Arabidopsis, but is not necessary for cell fate decisions except during carpel development. SPT functions independently of gibberellic acid during root development, but may play a role in regulating auxin transport or accumulation. Our data suggests that SPT plays a role in control of root growth, similar to its roles in above ground tissues. PMID:23280064

  16. Human due diligence.

    PubMed

    Harding, David; Rouse, Ted

    2007-04-01

    Most companies do a thorough job of financial due diligence when they acquire other companies. But all too often, deal makers simply ignore or underestimate the significance of people issues in mergers and acquisitions. The consequences are severe. Most obviously, there's a high degree of talent loss after a deal's announcement. To make matters worse, differences in decision-making styles lead to infighting; integration stalls; and productivity declines. The good news is that human due diligence can help companies avoid these problems. Done early enough, it helps acquirers decide whether to embrace or kill a deal and determine the price they are willing to pay. It also lays the groundwork for smooth integration. When acquirers have done their homework, they can uncover capability gaps, points of friction, and differences in decision making. Even more important, they can make the critical "people" decisions-who stays, who goes, who runs the combined business, what to do with the rank and file-at the time the deal is announced or shortly thereafter. Making such decisions within the first 30 days is critical to the success of a deal. Hostile situations clearly make things more difficult, but companies can and must still do a certain amount of human due diligence to reduce the inevitable fallout from the acquisition process and smooth the integration. This article details the steps involved in conducting human due diligence. The approach is structured around answering five basic questions: Who is the cultural acquirer? What kind of organization do you want? Will the two cultures mesh? Who are the people you most want to retain? And how will rank-and-file employees react to the deal? Unless an acquiring company has answered these questions to its satisfaction, the acquisition it is making will be very likely to end badly. PMID:17432159

  17. Applicability of optical scanner method for fine root dynamics

    NASA Astrophysics Data System (ADS)

    Kume, Tomonori; Ohashi, Mizue; Makita, Naoki; Khoon Kho, Lip; Katayama, Ayumi; Matsumoto, Kazuho; Ikeno, Hidetoshi

    2016-04-01

    Fine root dynamics is one of the important components in forest carbon cycling, as ~60 % of tree photosynthetic production can be allocated to root growth and metabolic activities. Various techniques have been developed for monitoring fine root biomass, production, mortality in order to understand carbon pools and fluxes resulting from fine roots dynamics. The minirhizotron method is now a widely used technique, in which a transparent tube is inserted into the soil and researchers count an increase and decrease of roots along the tube using images taken by a minirhizotron camera or minirhizotron video camera inside the tube. This method allows us to observe root behavior directly without destruction, but has several weaknesses; e.g., the difficulty of scaling up the results to stand level because of the small observation windows. Also, most of the image analysis are performed manually, which may yield insufficient quantitative and objective data. Recently, scanner method has been proposed, which can produce much bigger-size images (A4-size) with lower cost than those of the minirhizotron methods. However, laborious and time-consuming image analysis still limits the applicability of this method. In this study, therefore, we aimed to develop a new protocol for scanner image analysis to extract root behavior in soil. We evaluated applicability of this method in two ways; 1) the impact of different observers including root-study professionals, semi- and non-professionals on the detected results of root dynamics such as abundance, growth, and decomposition, and 2) the impact of window size on the results using a random sampling basis exercise. We applied our new protocol to analyze temporal changes of root behavior from sequential scanner images derived from a Bornean tropical forests. The results detected by the six observers showed considerable concordance in temporal changes in the abundance and the growth of fine roots but less in the decomposition. We also examined

  18. Root traits for infertile soils

    PubMed Central

    White, Philip J.; George, Timothy S.; Dupuy, Lionel X.; Karley, Alison J.; Valentine, Tracy A.; Wiesel, Lea; Wishart, Jane

    2013-01-01

    Crop production is often restricted by the availability of essential mineral elements. For example, the availability of N, P, K, and S limits low-input agriculture, the phytoavailability of Fe, Zn, and Cu limits crop production on alkaline and calcareous soils, and P, Mo, Mg, Ca, and K deficiencies, together with proton, Al and Mn toxicities, limit crop production on acid soils. Since essential mineral elements are acquired by the root system, the development of crop genotypes with root traits increasing their acquisition should increase yields on infertile soils. This paper examines root traits likely to improve the acquisition of these elements and observes that, although the efficient acquisition of a particular element requires a specific set of root traits, suites of traits can be identified that benefit the acquisition of a group of mineral elements. Elements can be divided into three Groups based on common trait requirements. Group 1 comprises N, S, K, B, and P. Group 2 comprises Fe, Zn, Cu, Mn, and Ni. Group 3 contains mineral elements that rarely affect crop production. It is argued that breeding for a limited number of distinct root ideotypes, addressing particular combinations of mineral imbalances, should be pursued. PMID:23781228

  19. Electrotropism of Maize Roots 1

    PubMed Central

    Ishikawa, Hideo; Evans, Michael L.

    1990-01-01

    We examined the kinetics of electrotropic curvature in solutions of low electrolyte concentration using primary roots of maize (Zea mays L., variety Merit). When submerged in oxygenated solution across which an electric field was applied, the roots curved rapidly and strongly toward the positive electrode (anode). The strength of the electrotropic response increased and the latent period decreased with increasing field strength. At a field strength of 7.5 volts per centimeter the latent period was 6.6 minutes and curvature reached 60 degrees in about 1 hour. For electric fields greater than 10 volts per centimeter the latent period was less than 1 minute. There was no response to electric fields less than 2.8 volts per centimeter. Both electrotropism and growth were inhibited when indoleacetic acid (10 micromolar) was included in the medium. The auxin transport inhibitor pyrenoylbenzoic acid strongly inhibited electrotropism without inhibiting growth. Electrotropism was enhanced by treatments that interfere with gravitropism, e.g. decapping the roots or pretreating them with ethyleneglycol-bis-[β-ethylether]-N,N,N′,N′-tetraacetic acid. Similarly, roots of agravitropic pea (Pisum sativum, variety Ageotropum) seedlings were more responsive to electrotropic stimulation than roots of normal (variety Alaska) seedlings. The data indicate that the early steps of gravitropism and electrotropism occur by independent mechanisms. However, the motor mechanisms of the two responses may have features in common since auxin and auxin transport inhibitors reduced both gravitropism and electrotropism. PMID:11537481

  20. Magnetophoretic Induction of Root Curvature

    NASA Technical Reports Server (NTRS)

    Hasenstein, Karl H.

    1997-01-01

    The last year of the grant period concerned the consolidation of previous experiments to ascertain that the theoretical premise apply not just to root but also to shoots. In addition, we verified that high gradient magnetic fields do not interfere with regular cellular activities. Previous results have established that: (1) intracellular magnetophoresis is possible; and (2) HGMF lead to root curvature. In order to investigate whether HGMF affect the assembly and/or organization of structural proteins, we examined the arrangement of microtubules in roots exposed to HGMF. The cytoskeletal investigations were performed with fomaldehyde-fixed, nonembedded tissue segments that were cut with a vibratome. Microtubules (MTs) were stained with rat anti-yeast tubulin (YOL 1/34) and DTAF-labeled antibody against rat IgG. Microfilaments (MFs) were visualized by incubation in rhodamine-labeled phalloidin. The distribution and arrangement of both components of the cytoskeleton were examined with a confocal microscope. Measurements of growth rates and graviresponse were done using a video-digitizer. Since HGMF repel diamagnetic substances including starch-filled amyloplasts and most The second aspect of the work includes studies of the effect of cytoskeletal inhibitors on MTs and MFs. The analysis of the effect of micotubular inhibitors on the auxin transport in roots showed that there is very little effect of MT-depolymerizing or stabilizing drugs on auxin transport. This is in line with observations that application of such drugs is not immediately affecting the graviresponsiveness of roots.

  1. Root standing crop and chemistry after six years of soil warming in a temperate forest.

    PubMed

    Zhou, Yumei; Tang, Jianwu; Melillo, Jerry M; Butler, Sarah; Mohan, Jacqueline E

    2011-07-01

    Examining the responses of root standing crop (biomass and necromass) and chemistry to soil warming is crucial for understanding root dynamics and functioning in the face of global climate change. We assessed the standing crop, total nitrogen (N) and carbon (C) compounds in tree roots and soil net N mineralization over the growing season after 6 years of experimental soil warming in a temperate deciduous forest in 2008. Roots were sorted into four different categories: live and dead fine roots (≤1mm in diameter) and live and dead coarse roots (1-4 mm in diameter). Total root standing crop (live plus dead) in the top 10 cm of soil in the warmed area was 42.5% (378.4 vs. 658.5 g m(-2)) lower than in the control area, while live root standing crop in the warmed area was 62% lower than in the control area. Soil net N mineralization over the growing season increased by 79.4% in the warmed relative to the control area. Soil warming did not significantly change the concentrations of C and C compounds (sugar, starch, hemicellulose, cellulose and lignin) in the four root categories. However, total N concentration in the live fine roots in the warmed area was 10.5% (13.7 vs. 12.4 mg g(-1)) higher and C:N ratio was 8.6% (38.5 vs. 42.1) lower than in the control area. The increase in N concentration in the live fine roots could be attributed to the increase in soil N availability due to soil warming. Net N mineralization was negatively correlated with both live and dead fine roots in the mineral soil that is home to the majority of roots, suggesting that soil warming increases N mineralization, decreases fine root biomass and thus decreases C allocation belowground. PMID:21813516

  2. Root dynamics in native grassland exposed to elevated CO2 and warming

    NASA Astrophysics Data System (ADS)

    Pendall, E.; Carrillo, Y.; Morgan, J. A.; Newcomb, J.

    2011-12-01

    Responses of belowground processes to global change play a major role in terrestrial ecosystem carbon (C) storage and feedbacks to climate, but remain understudied in comparison to aboveground processes. In grasslands, roots comprise about 75 percent of the biomass, and are responsible for increased inputs of C to soil pools under elevated CO2. Root exudation may also be responsible for increased rates of soil organic matter decomposition, or priming, potentially offsetting inputs of new C. Understanding the fate of belowground C allocation requires a better understanding of root processes including growth, rhizodeposition, turnover and decomposition. We studied root dynamics in mixed C3/C4 grassland at the Prairie Heating and CO2 Enrichment experiment near Cheyenne, WY, where Free-Air CO2 Enrichment is applied at 600 ppm during daytime in the growing season, and temperature is elevated by 1.5/3 deg C day/night all year. We applied several belowground techniques, including direct biomass measurements coupled with C isotope labeling, root litter decomposition measured in litter bags and in plots with herbicide applied, and image analysis of intact and harvested root systems . Direct measurements indicated that elevated CO2 increased root biomass, a trend that became increasingly significant over the first four years of treatments. Warming by itself tended to decrease root biomass in the first two years, and this effect declined in the next two years of the experiment, suggesting a transient negative response of root growth to warming. Continuous 13C labeling in elevated CO2 plots allowed detection of a greater proportion of new C in warmed than ambient temperature plots, demonstrating greater allocation of C to roots exposed to both elevated CO2 and warming. A root litter bag decomposition experiment showed that C3 grass roots decomposed more rapidly with elevated CO2 alone, but more slowly when elevated CO2 was combined with warming, possibly due to soil drying. C4

  3. Using thermodynamics to assess biotic and abiotic impediments to root water uptake

    NASA Astrophysics Data System (ADS)

    Bechmann, Marcel; Hildebrandt, Anke; Kleidon, Axel

    2016-04-01

    evaluate energy fluxes afterwards. The results show that a minimum of energy is exported in mixed root systems, but a wide range of root systems act near the optimum. A great loss of efficiency only occurs in the extreme cases (only young or only old roots). In all systems near the optimum root water uptake is impeded equally by abiotic and biotic factors in moist conditions, whereas abiotic factors become the limiting factor in dry conditions. The abiotic factors depend on the soil type and are either due to the water retention function or water flow towards individual roots. Small changes in the distribution of root resistance shift the impediments from radial to axial flow path within the root, but without much affecting overall energy export. This suggests that abiotic factors are a dominant control for efficient root water uptake, while morphology only has a comparatively smaller effect, as long as the root system contains a minimum mixture of uptake and transport roots.

  4. Community composition of root-associated fungi in a Quercus-dominated temperate forest: “codominance” of mycorrhizal and root-endophytic fungi

    PubMed Central

    Toju, Hirokazu; Yamamoto, Satoshi; Sato, Hirotoshi; Tanabe, Akifumi S; Gilbert, Gregory S; Kadowaki, Kohmei

    2013-01-01

    In terrestrial ecosystems, plant roots are colonized by various clades of mycorrhizal and endophytic fungi. Focused on the root systems of an oak-dominated temperate forest in Japan, we used 454 pyrosequencing to explore how phylogenetically diverse fungi constitute an ecological community of multiple ecotypes. In total, 345 operational taxonomic units (OTUs) of fungi were found from 159 terminal-root samples from 12 plant species occurring in the forest. Due to the dominance of an oak species (Quercus serrata), diverse ectomycorrhizal clades such as Russula, Lactarius, Cortinarius, Tomentella, Amanita, Boletus, and Cenococcum were observed. Unexpectedly, the root-associated fungal community was dominated by root-endophytic ascomycetes in Helotiales, Chaetothyriales, and Rhytismatales. Overall, 55.3% of root samples were colonized by both the commonly observed ascomycetes and ectomycorrhizal fungi; 75.0% of the root samples of the dominant Q. serrata were so cocolonized. Overall, this study revealed that root-associated fungal communities of oak-dominated temperate forests were dominated not only by ectomycorrhizal fungi but also by diverse root endophytes and that potential ecological interactions between the two ecotypes may be important to understand the complex assembly processes of belowground fungal communities. PMID:23762515

  5. Evidence of Differences between the Communities of Arbuscular Mycorrhizal Fungi Colonizing Galls and Roots of Prunus persica Infected by the Root-Knot Nematode Meloidogyne incognita▿

    PubMed Central

    Alguacil, Maria del Mar; Torrecillas, Emma; Lozano, Zenaida; Roldán, Antonio

    2011-01-01

    Arbuscular mycorrhizal fungi (AMF) play important roles as plant protection agents, reducing or suppressing nematode colonization. However, it has never been investigated whether the galls produced in roots by nematode infection are colonized by AMF. This study tested whether galls produced by Meloidogyne incognita infection in Prunus persica roots are colonized by AMF. We also determined the changes in AMF composition and biodiversity mediated by infection with this root-knot nematode. DNA from galls and roots of plants infected by M. incognita and from roots of noninfected plants was extracted, amplified, cloned, and sequenced using AMF-specific primers. Phylogenetic analysis using the small-subunit (SSU) ribosomal DNA (rDNA) data set revealed 22 different AMF sequence types (17 Glomus sequence types, 3 Paraglomus sequence types, 1 Scutellospora sequence type, and 1 Acaulospora sequence type). The highest AMF diversity was found in uninfected roots, followed by infected roots and galls. This study indicates that the galls produced in P. persica roots due to infection with M. incognita were colonized extensively by a community of AMF, belonging to the families Paraglomeraceae and Glomeraceae, that was different from the community detected in roots. Although the function of the AMF in the galls is still unknown, we hypothesize that they act as protection agents against opportunistic pathogens. PMID:21984233

  6. The role of roots in the accumulation and removal of cadmium by the aquatic plant Hydrilla verticillata.

    PubMed

    He, Yan; Rui, Haiyun; Chen, Chen; Chen, Yahua; Shen, Zhenguo

    2016-07-01

    Aquatic macrophytes can absorb heavy metals either from sediments via the root system, from the water phase by leaves, or from both sources. In this study, cadmium accumulation and distribution in the aquatic plant Hydrilla verticillata were investigated, with a focus on the role of roots. Results showed that leaves of H. verticillata had a higher Cd concentration than roots when intact plants were grown in sediments and solutions containing Cd. Cadmium can significantly decrease the leaf chlorophyll content, and the leaves of intact plants with roots had lower chlorophyll contents than the leaves of detached ones without roots due to the transfer effect of roots. The majority of the Cd accumulated in leaves of H. verticillata was bound to the cell walls. When roots were submerged in a solution containing Cd, with shoots in a control solution without Cd, the Cd concentrations in leaves were considerably lower than in roots. In contrast, Cd was almost undetectable in roots when the shoots were submerged in a solution containing Cd, with roots in the control solution. Compared to the leaves and stems of detached shoots without roots, the concentrations of Cd were much higher in the leaves and stems of intact plants with roots. It is suggested that the roots of intact plants absorb Cd and transfer it to leaves and that more Cd is removed from the solution by intact plants. PMID:27023818

  7. Breakage of transgenic tobacco roots for monoclonal antibody release in an ultra-scale down shearing device

    PubMed Central

    Hassan, Sally; Keshavarz-Moore, Eli; Ma, Julian; Thomas, Colin

    2014-01-01

    Transgenic tobacco roots offer a potential alternative to leaves for monoclonal antibody (MAb) production. A possible method for extraction of MAbs from roots is by homogenization, breaking the roots into fragments to release the antibody. This process was assessed by shearing 10 mm root sections (“roots”) in a 24 mL ultra-scale down shearing device, including an impeller with serrated blade edges, intended to mimic the action of a large-scale homogenizer. Size distributions of the remaining intact roots and root fragments were obtained as a function of shearing time. The data suggest that about 36% of the roots could not be broken under the prevailing conditions and, beyond these unbreakable roots, the fragmentation was approximately first order with respect to intact root number. It was postulated that root breakage in such a high shearing device was due to root-impeller collisions and the particle size data suggest that roots colliding with the impeller were completely fragmented into debris particles of the order of 0.1 mm in length. IgG release normalized to release by grinding appeared to lag behind the number of roots that had fragmented, suggesting that a process of leakage followed fragmentation in the ultra-scale down shearing device. PMID:23860965

  8. Cache Complexity and Multicore Implementation for Univariate Real Root Isolation

    NASA Astrophysics Data System (ADS)

    Chen, Changbo; Moreno Maza, Marc; Xie, Yuzhen

    2012-02-01

    We present parallel algorithms with optimal cache complexity for the kernel routine of many real root isolation algorithms, namely the Taylor shift by 1. We then report on multicore implementation for isolating the real roots of univariate polynomials with integer coefficients based on a classical algorithm due to Vincent, Collins and Akritas. For processing some well-known benchmark examples with sufficiently large size, our software tool reaches linear speedup on an 8-core machine. In addition, we show that our software is able to fully utilize the many cores and the memory space of a 32-core machine to tackle large problems that are out of reach for a desktop implementation.

  9. Efficient hydraulic properties of root systems

    NASA Astrophysics Data System (ADS)

    Bechmann, Marcel; Schneider, Christoph; Carminati, Andrea; Hildebrandt, Anke

    2013-04-01

    Understanding the mechanisms of ecosystem root water uptake (RWU) is paramount for parameterizing hydrological models. With the increase in computational power it is possible to calculate RWU explicitly up to the single plant scale using physical models. However, application of these models for increasing our understanding of ecosystem root water uptake is hindered by the deficit in knowledge about the detailed hydraulic parameter distribution within root systems. However, those physical models may help us to identify efficient parameterizations and to describe the influence of these hydraulic parameters on RWU profiles. In this research, we investigated the combined influence of root hydraulic parameters and different root topologies on shaping efficient root water uptake. First, we use a conceptual model of simple branching structures to understand the influence of branching location and transitions in root hydraulic properties on the RWU patterns in typical sub root structures. Second, we apply a physical model called "aRoot" to test our conclusions on complex root system architectures of single plants. aRoot calculates the distribution of xylem potential within arbitrary root geometries to satisfy a given water demand depending on the available water in the soil. Redistribution of water within the bulk soil is calculated using the Richards equation. We analyzed results using a measure of uptake efficiency, which describes the effort necessary for transpiration. Simulations with the conceptual model showed that total transpiration in sub root structures is independent of root hydraulic properties over a wide range of hydraulic parameters. On the other hand efficiency of root water uptake depends crucially on distribution hydraulic parameters in line with root topology. At the same time, these parameters shape strongly the distribution of RWU along the roots, and its evolution in time, thus leading to variable individual root water uptake profiles. Calculating

  10. Orthodontic treatment in patient with idiopathic root resorption: A case report

    PubMed Central

    Rey, Diego; Smit, Rosana Martínez; Gamboa, Liliana

    2015-01-01

    Multiple idiopathic external root resorption is a rare pathological condition usually detected as an incidental radiographic finding. External root resorption of permanent teeth is a multifactorial process related to several local and systemic factors. If an etiological factor cannot be identified for root resorption, the term "idiopathic" is applied. This report presents a case of multiple idiopathic apical root resorption. The condition was found in a young female patient seeking orthodontic treatment due to malocclusion. This kind of resorption starts apically and progresses coronally, causing a gradual shortening and rounding of the remaining root. Patients with this condition are not the ideal candidates for orthodontic treatment; however, the aim of this report is to describe an unusual case of idiopathic root resorption involving the entire dentition, and to present the orthodontic treatment of this patient. It describes the progress and completion of orthodontic therapy with satisfactory end results. PMID:25741832