The relationship between an endangered North American tree and an endophytic fungus

BACKGROUND: The Florida torreya (Torreya taxifolia) began a catastrophic decline in the late 1950s and is now the rarest tree in North America for which a full species designation has been established. The trees have common plant disease symptoms, but the reason for the decline has never been identified. T. taxifolia's imminent extinction gains special poignancy through its close relationship to the Pacific yew (Taxus brevifolia), which produces the potent anticancer agent, taxol. RESULTS: An examination of the endophytic fungal communities of wild torreyas consistently found a filamentous fungus, Pestalotiopsis microspora, associated with diseased trees and also with most symptomless trees. P. microspora can be cultured in the laboratory, and when it is introduced into greenhouse-grown torreyas, it causes disease symptoms similar to those seen in the field. The fungus can then be reisolated from these deliberately infected trees. The phytotoxins pestalopyrone, hydroxypestalopyrone and pestaloside have been isolated and characterized from axenic fungal cultures, and both pestalopyrone and hydroxypestalopyrone can be isolated from artificially infected torreyas. In addition, pestaloside has antifungal activity against other fungal endophytes of T. taxifolia. CONCLUSIONS: The filamentous fungus, P. microspora, has an endophytic-pathologic relationship with T. taxifolia. The fungus resides in the inner bark of symptomless trees, and physiological or environmental factors could trigger its pathological activity. P. microspora produces the phytotoxins pestalopyrone, hydroxypestalopyrone, and pestaloside which give rise to the disease. Pestaloside, which also has antifungal activity, could reduce competition from other fungal endophytes within the host.     

Controlled hydroxylation of diamond for covalent attachment of fullerene molecules

Diamond can adopt a p-type sheet conductivity by surface transfer doping. Fullerene and fluorinated fullerene derivatives have been shown in the past to take the role as efficient surface acceptors. In order to improve the thermal stability of the sheet conductivity so obtained, we have studied the covalent attachment of C₆₀F₄₈ to a hydrogen terminated and partially hydroxylated diamond (100) surface by photoelectron spectroscopy and in situ conductivity measurements. A careful control of the hydroxylation process turned out to be crucial in order to obtain a sufficient amount of OH groups on the surface and keep the concentration of ketone, ether, and carboxyl small.     

Strategies of nutrient transport by ruminal bacteria

The survival of bacteria in natural environments like the rumen depends on the ability of the bacteria to scavenge nutrients. It is now evident that ruminal bacteria use a variety of transport mechanisms. Hydrophobic substances, such as ammonia and acetate, are permeable to the lipid bilayers of cell membranes and can be taken up by passive diffusion. Hydrophilic compounds (e.g., sugars, amino acids, peptides) do not easily pass through lipid bilayers and must be transported across cell membranes on carrier proteins. Facilitated diffusion can display saturable kinetics but does not result in accumulation of solute. Active transport can establish extremely high concentration gradients, and this work may be driven by the hydrolysis of chemical bonds (e.g., ATP) or ion gradients, which are coupled to solute symport. Many solute symports involve protons, but sodium systems also are common in ruminal bacteria. The phosphotransferase system chemically modifies sugars as they pass across the cell membrane, and several ruminal bacteria have this method of group translocation. Many feed additives have either a direct or indirect effect on rumen bacterial transport. For instance, ionophores can inhibit transport by destroying (sometimes even reversing) ion gradients, lowering intracellular pH, or causing excessive ATP hydrolysis.     

Polysaccharide von Swietenia macrophylla King

Ohne Zusammenfassung     

Concentration of ammonia across cell membranes of mixed rumen bacteria

When mixed ruminal bacteria were provided with growth rate limiting amounts of mixed carbohydrates, more than 50 mg ammonia/L were required for maximal protein synthesis. Microbial protein synthesis declined when ammonia concentration was less than 50 mg/L and unfermented carbohydrates increased. Ammonia starvation also decreased growth efficiency. Intracellular ammonia increased as a linear function of extracellular ammonia, but the intracellular concentration was always at least 160 mg/L higher than the extracellular concentration. Maximal protein synthesis was not observed until intracellular ammonia was greater than 220 mg/L. The concentration gradient of ammonia across cell membranes ranged from 15-fold to 1.8-fold and indicated that some of the ruminal bacteria may have active transport mechanisms for ammonia. These concentration gradients were, however, far less than those reported for bacteria from other habitats. The ruminal bacteria left more than 12 mg ammonia/L when carbohydrates were still available, and this observation was consistent with the assumption that active ammonium transport was not readily or maximally induced.     

Orientation development in retensilized,biaxially oriented polypropylene films

A basic study of orientation development in retensilized, biaxially oriented polypropylene films was performed. Wide-angle X-ray scattering (WAXS) and birefringence measurement techniques were used to examine films prepared under specific processing conditions. Biaxial orientation factors were determined for these films and were correlated with end-use properties of the materials. In particular, the dispensability of oriented polypropylene films was found to correlate with crystalline-phase and amorphous-phase orientation factors. Dispensability is a relatively important property of pressure-sensitive tapes; it is defined as the force necessary to cut a film backing over a serrated blade of the type used in commercially available adhesive-tape dispensers.     

Interpersonal workplace stressors and well-being: A multi-wave study of employees with and without arthritis.

The within-person influence of interpersonal stressors on affective well-being and physical well-being was investigated for 109 women with and without arthritis. Participants were interviewed on a weekly basis for 12 consecutive weeks, and the prospective data were analyzed by using hierarchical linear modeling. Overall, interpersonal workplace stressors independently predicted both well-being outcomes. Interpersonal stressors outside the workplace were related to negative affect but not to arthritis symptoms. Compared with healthy controls, arthritis patients' ratings of negative affect were equally reactive to workplace stressors. Neuroticism did not moderate stressor reactivity for either dependent variable but did predict mean levels of negative affect. The data support the hypothesis that the psychosocial environment of the workplace contributes unique effects on well-being. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Characterization of the thermal and fluid flow behavior of industrial ribbon burners

This study focuses on the key parameters that enhance the stability of ribbon burners used in various industrial processes, characterizing the flame environment and flow regimes that the burner creates under changing operating conditions. The research includes the exploration of ribbon-pack configurations in order to define the effects of separation distance and port arrangement on flame stability and thermal and fluid flow. Flow visualization studies reveal that burners having a 1.5–2.0 mm division between rows appear to be the most stable. More than four rows of ports in the ribbon-pack are required to resist entrainment of ambient air as a result of impinging surface motion. The flame environment created by the ribbon burner experiences higher levels of mixing, at a lower Reynolds number in comparison to a single non-reacting jet due to combustion-induced turbulence and jet interaction. Under these high flow velocity conditions there is little entrainment of ambient air along the impingement surface and a very stable flame environment is created.     

Verification of aero‐elastic offshore wind turbine design codes under IEA Wind Task XXIII

This work presents the results of a benchmark study on aero‐servo‐hydro‐elastic codes for offshore wind turbine dynamic simulation. The codes verified herein account for the coupled dynamic systems including the wind inflow, aerodynamics, elasticity and controls of the turbine, along with the incident waves, sea current, hydrodynamics and foundation dynamics of the support structure. A large set of time series simulation results such as turbine operational characteristics, external conditions, and load and displacement outputs was compared and interpreted. Load cases were defined and run with increasing complexity to trace back differences in simulation results to the underlying error sources. This led to a deeper understanding of the underlying physical systems. In four subsequent phases—dealing with a 5‐MW turbine on a monopile with a fixed foundation, a monopile with a flexible foundation, a tripod and a floating spar buoy—the latest support structure developments in the offshore wind energy industry are covered, and an adaptation of the codes to those developments was initiated. The comparisons, in general, agreed quite well. Differences existed among the predictions were traced back to differences in the model fidelity, aerodynamic implementation, hydrodynamic load discretization and numerical difficulties within the codes. The comparisons resulted in a more thorough understanding of the modeling techniques and better knowledge of when various approximations are not valid. More importantly, the lessons learned from this exercise have been used to further develop and improve the codes of the participants and increase the confidence in the codes’ accuracy and the correctness of the results, hence improving the standard of offshore wind turbine modeling and simulation. One purpose of this paper is to summarize the lessons learned and present results that code developers can compare to. The set of benchmark load cases defined and simulated during the course of this project—the raw data for this paper—is available to the offshore wind turbine simulation community and is already being used for testing newly developed software tools. Despite that no measurements are included, the large number of participants and the—in general—very fine level of agreement indicate high trustworthy results within the physical assumptions of the codes and the simulation cases chosen. Other cases, such as large prebend flexible blades, large wind shear, large yaw error or transient maneuvers, may not show the same level of agreement. These cases were deliberately left out because the focus is on the specific offshore application. Further on, this benchmark study includes participating codes and organizations by name (contrary to several previous benchmark studies) that gives the reader a chance to find results from one particular code of interest.Copyright © 2013 John Wiley & Sons, Ltd.