bluuebunny/crossref_metadata_2025_split huggingface dataset:
Root turnover of faba beans (Vicia faba L.) and its interaction with P and K supply
Authors: Steingrobe Bernd 
Published: June 2005

AbstractAn increased root turnover can be a mechanism of improved nutrient‐uptake efficiency. The objectives of this study were to investigate P and K efficiency of faba beans (Vicia faba L.), to determine their root growth and root turnover, and to assess the relevance of root turnover on P and K uptake at limited supply. Faba beans were grown as part of a long‐term fertilization experiment on fertilized plots (control) and plots that had not received any P or K fertilizer for 16 years (P0, K0). Although the unfertilized soils were low and very low in their P‐ and K‐supply level, respectively, no differences in shoot‐dry‐matter production occurred compared to the control. However, relative K concentration in dry matter of the K0 plants (control plants = 100) decreased during the experiment and was only 60% of the control at the final harvest. This indicated a high K‐utilization efficiency of faba bean. Relative phosphorus concentration increased in the P0 treatment and was not different from the control at the last harvest, indicating an improvement in P‐uptake efficiency with time. The size of the standing root system determined by sequential auger sampling (net development) was not influenced by P and K supply. Total root production as measured by the ingrowth‐core method was about 6 times higher than the average size of the standing root system and even increased under low‐K conditions. This indicated a fast root turnover. Modeling soil nutrient transport and uptake revealed that calculated uptake of the control was up to 48% higher when root turnover was taken into account, compared to calculations based on the net development of the root systems. This is due to a better soil exploitation. Under K shortage, root turnover resulted in a 117% higher calculated uptake, which was close to measured K uptake. Root turnover was also of benefit for P uptake, but calculated P uptake was significantly less than measured, indicating that root turnover was of little importance for P uptake of faba beans.
Diffusive flux of cationic micronutrients in two Oxisols as affected by low‐molecular‐weight organic acids and cover‐crop residue
Authors: Pegoraro Rodinei F. , Silva Ivo R. , Novais Roberto F. , Mendonça Eduardo S. , Alvarez Victor Hugo , Nunes Flancer N. , Fonseca Frederico M. , Smyth Thomas J. 
Published: June 2005

AbstractLow‐molecular‐weight organic acids with one or more carboxylic groups are ubiquitous. In soils, they can originate from leaching of plants, litter decomposition, plant‐roots exudation, and microbial activity. Their presence in the soil may favor the formation of soluble organo‐metallic complexes that improve the transport of Zn, Cu, Fe, and Mn to plant‐root surfaces via diffusion. The current study sought to determine if some of the organic acids (OA) in soils and a cover‐crop residue influence the diffusive flux (DF) of Zn, Cu, Mn, and Fe. Two OA were added to two Oxisols (Typic Haplustox): a clayey Dark Red Latosol (DRL) and a sandy‐loam Red Yellow Latosol (RYL). Acetic and citric acid were added to achieve concentrations of 0, 250, 500, 1000, and 2000 mmol (m3 soil)–1. The effect of adding plant material (pearl millet) on the soil DF of the cationic micronutrients was also determined. Soil diffusive flux was evaluated by incubating positively charged and negatively charged exchange‐resin membranes with the soil in PVC diffusion chambers for 15 d. Desorption of Zn, Cu, Fe, Mn, and OA from the resins was performed with 0.5 mol l–1 HCl. The results demonstrated that the DF of the cationic micronutrients increased with the addition of organic acid. The DF of Zn and Mn occurred mostly towards the cationic resin, whereas the diffusive flux of Cu and Fe occurred mostly towards the anionic resin. Apparently, the dissolution of oxides and/or complexation of micronutrients adsorbed to the solid phase or in the soil solution contributed to the obtained results. Citric acid was more efficient than acetic acid in maintaining a larger DF value for Zn, Cu, and Fe. The addition of millet plant material to the soil increased the DF in the following order: Mn > Cu > Fe > Zn; Mn moved towards the cationic resin, and the other micronutrients moved towards the anionic resin. These findings suggest that organic compounds play an important role in the short‐distance transport of cationic micronutrients in highly weathered soils.
The umbric epipedon in the N Apennines, Italy—an example from the Vallombrosa Forest
Authors: Sanesi Guido , Certini Giacomo 
Published: June 2005

AbstractThe umbric epipedon is a diagnostic surface horizon recognized by both the World Reference Base for Soil Resources and the U.S. Soil Taxonomy. It is mainly characterized by a dark color, a moderate to high content of OM, and a base saturation of less than 50%. In the N Apennines, Central Italy, forest soils over 600–700 m a.s.l. often have this epipedon. This paper stresses the morphological, chemical, and biological properties of the epipedon, specifically in the Vallombrosa Forest, where considerable work has been done in the last decade. Here, the umbric epipedon forms on sandstone, in high forests of Abies alba, Fagus sylvatica, and Castanea sativa. It does not have homogeneous properties throughout its thickness and often is divided into two distinct genetic horizons, A1 and A2. The A1 horizon is thinner, darker, and richer in OM, more base‐saturated, and biologically more active than the underlying A2 horizon. The mean residence time of the bulk OM amounts to about a century in the A1 horizon, versus half a millennium in the A2. In both A1 and A2 horizons, the non‐humic fraction prevails in the OM; this could account for the high susceptibility of the umbric epipedon to degrade when the forest is clear‐cut or undergoes extensive uprooting due to windstorms or heavy snow loads. Significant discrepancies between the two A horizons have been found in regard to the microbial community. Umbric epipedons which developed under different tree species show minor differences, mainly concerning the microbial community.
Comparison of the prediction efficiency of two pedotransfer functions for soil cation‐exchange capacity
Authors: Horn Andreas L. , Düring Rolf‐Alexander , Gäth Stefan 
Published: June 2005

AbstractThe aim of this study was to provide knowledge of the prediction efficiency of two pedotransfer functions for soil cation‐exchange capacity (CEC), i.e., the approaches of Krogh et al. (2000) and Scheinost (1995). Potential CEC, i.e., CEC at pH 8.1, was predicted for 30 samples of German soils showing a strong variation of soil organic C and clay content which are important soil characteristics for CEC. The results were compared to analyzed potential CEC of the samples by coefficient‐of‐efficiency (EC) criterion of Nash and Sutcliffe (1970). Significant deviations between observed and measured CEC were found for both functions. The approach of Scheinost (1995) showed a higher prediction efficiency (EC = 0.77 in comparison to EC = 0.26 for Krogh et al., 2000) and better results under extrapolative conditions.
Modeling aluminum solubility in intrazonal podzols using WHAM‐S/Model V
Authors: Jansen Boris , Mulder Jan , Verstraten Jacobus M. 
Published: June 2005

AbstractSo far, research in the area of podzolization has not resulted in consensus about the role of organic matter (OM) in regulating the transport and accumulation of Al and Fe at depth. From previous laboratory studies of the role of OM as a driver for podzolization in two intrazonal podzols, we concluded that it controls the mobilization of Al and Fe in A horizons and regulates the immobilization of Al in upper B horizons. In contrast, the solubility of Al in lower B horizons is mainly regulated by equilibrium with its secondary inorganic phases, as is the case for Fe in all B horizons. In the present study, we tested the conclusions with respect to Al through the application of the comprehensive metal‐binding model WHAM‐S 1.0/Model V. Using CuCl2‐extractable Al in horizons with in‐situ pH < 4.3 and ammonium oxalate/oxalic acid‐extractable Al in horizons with in‐situ pH > 4.3 as an estimate of the “reactive” pools of solid‐phase Al, we were able to get reasonable to good descriptions of the measured total Al concentrations in all horizons studied. These results vindicate the use of WHAM‐S 1.0 to help interpret complex interactions between metals and OM as they occur in the podzolization process. They also support our previous conclusions with respect to the mechanisms governing the solubility and mobility of Al in intrazonal podzols.
Novel micro–suction‐cup design for sampling soil solution at defined distances from roots
Authors: Puschenreiter Markus , Wenzel Walter W. , Wieshammer Gottfried , Fitz Walter J. , Wieczorek Simone , Kanitsar Katherina , Köllensperger Gunda 
Published: June 2005

AbstractMicro–suction cups made of nylon membranes and polyacrylic tubes with planar geometry of the membrane were designed for repeated sampling of rhizosphere solution at defined distances from a root monolayer. Adsorption tests revealed that the materials used (nylon membrane, polyacrylic tube) have little influence on the concentration of heavy metals in the sample solution, whereas some organic acids are partly retained by the suction cup. A sampling protocol was developed for collecting extremely small solution volumes (i.e., droplets of 28.3±2.46 μl) for subsequent measurements of trace elements using ICP‐SFMS. A homogeneity test showed that soil‐solution concentrations of Ca, K, Mg, and Ni could be reproduced independent of the suction‐cup position in a rhizobox experiment without plants. In a similar experiment, the rhizobox was planted with the Ni hyperaccumulator Thlaspi goesingense. Compared to more distant soil layers, an increase of Ni and a concurrent decrease of Ca, K, and Mg at 1 mm distance from the root plane was found. These changes can be related to plant uptake and mobilization processes. Our results show that the novel micro–suction cups are a valuable tool for elucidating rhizosphere processes.
Growth, phosphorus uptake, and rhizosphere microbial‐community composition of a phosphorus‐efficient wheat cultivar in soils differing in pH
Authors: Marschner Petra , Solaiman Zakaria , Rengel Zed 
Published: June 2005

AbstractIn a pot experiment, the P‐efficient wheat (Triticum aestivum L.) cultivar Goldmark was grown in ten soils from South Australia covering a wide range of pH (four acidic, two neutral, and four alkaline soils) with low to moderate P availability. Phosphorus (100 mg P kg–1) was supplied as FePO4 to acidic soils, CaHPO4 to alkaline, and 1:1 mixture of FePO4 and CaHPO4 to neutral soils. Phosphorus uptake was correlated with P availability measured by anion‐exchange resin and microbial biomass P in the rhizosphere. Growth and P uptake were best in the neutral soils, lower in the acidic, and poorest in the alkaline soils. The good growth in the neutral soils could be explained by a combination of extensive soil exploitation by the roots and high phosphatase activity in the rhizosphere, indicating microbial facilitation of organic‐P mineralization. The plant effect (soil exploitation by roots) appeared to dominate in the acidic soils. Alkaline phosphatase and diesterase activities in acidic soils were lower than in neutral soils, but strongly increased in the rhizosphere compared with the bulk soil, suggesting that microorganisms contribute to P uptake in these acidic soils. Shoot and root growth and P uptake per unit root length were lowest in the alkaline soils. Despite high alkaline phosphatase and diesterase activities in the alkaline soils, microbial biomass P was low, suggesting that the enzymes could not mineralize sufficient organic P to meet the demands of plants and microorganisms. Microbial‐community composition, assessed by fatty acid methylester (FAME) analysis, was strongly dependent on soil pH, whereas other soil properties (organic‐C or CaCO3 content) were less important or not important at all (soil texture).
The intake of dietary fiber from grape seeds modifies the antioxidant status in rat cecum
Authors: Goñi Isabel , Serrano José 
Published: June 2005

AbstractThe aim of this study was to measure the antioxidant activity and polyphenolic compounds in cecum and feces of rats fed with a grape seed concentrate. The grape concentrate was rich in indigestible compounds (dietary fiber, polyphenols and other associated compounds) which presented significant antioxidant activity. Polyphenols extracted by aqueous–organic solvents (extractable polyphenols, EPs) and non‐extractable polyphenols (NEPs) exhibited high antioxidant capacity as measured by the ABTS method. High correlations were found between antioxidant capacity values and EP (r2 = 0.9608) and NEP content (r2 = 0.9179). EPs and NEPs exhibited considerable antioxidant activity within the large intestine. Significant antioxidant activity was also found in feces derived from excreted EPs and NEPs. The grape fiber concentrate enhanced the antioxidant status in the large intestine. The antioxidant activity in the intestinal content should be considered when assessing the effects of dietary components on bowel diseases. Copyright © 2005 Society of Chemical Industry
Enhancing the transfer of knowledge resources through effective utilization of labor and technology in a global organization: a case study of Bovis Lend Lease Inc.'s global knowledge transfer system
Authors: Kudyba Stephan 
Published: June 2005

AbstractManagement initiatives have increased their intensity on enhancing operating efficiency and productivity across functional areas of the organization. Early efforts focused on investment in information technologies as organizations sought to transform their capital infrastructures to become more IT intensive. To more fully achieve productivity gains, however, management tactics have recently focused on more effectively utilizing the available knowledge resources that reside in their organization that exist in their employee base. The process of effectively identifying and transferring value‐added knowledge existing in the firm to functional areas which require the resource in a timely manner often involves the incorporation of labor and technology. The following paper illustrates current trends in knowledge management initiatives for a global real estate investment and construction services company. Copyright © 2005 John Wiley & Sons, Ltd.
Modeling of Particle Fragmentation in Heterogeneous Olefin Polymerization Reactions, 2
Authors: Merquior Douglas M. , Lima Enrique L. , Pinto José C. 
Published: May 2005

AbstractSummary: A two phase dynamic model is proposed here for the first time to describe the first stages of heterogeneous olefin polymerization and to improve predictions of particle morphology. Taking into account the solid and fluid phases, the two phase model allows for the calculation of the convective flux inside the growing polymer particle. Numerical simulations performed for both gas and slurry polymerizations show that the performances of the traditional diffusion model and of the proposed heterogeneous model are similar when mild polymerization conditions are considered, but may be very different when vigorous polymerization conditions are analyzed. It is shown that the development of convective flow inside the particle can exert a large influence on the course of the polymerization and on the final morphological characteristics of the polymer particle. When the initial catalyst particle contains inert material, it is also shown here that the inert material can contribute to a reduction of local reaction rates during particle breakup and, therefore, to a more uniform particle fragmentation.Schematic representation of a nascent polymer particle.magnified imageSchematic representation of a nascent polymer particle.
Investigation of the Variation of Unit Cell Dimensions of Crystalline Polymers with High‐Resolution FT‐IR Spectroscopy
Authors: Su Zhiqiang , Zhao Ying , Kang Ning , Zhang Xiuqin , Xu Yizhuang , Wu Jinguang , Wang Dujin , Han Charles C. , Xu Duanfu 
Published: June 2005

AbstractSummary: High‐resolution FT‐IR spectroscopy has been used for the first time to characterize the variation of the unit cell dimensions of high‐density polyethylene (HDPE). In combination with the unit cell parameters of HDPE measured at different temperatures by Swan using wide‐angle X‐ray diffraction, the relationship between the rocking band shift (730 cm−1) and the change of the unit cell volume of HDPE has been established.High‐resolution variable‐temperature FT‐IR spectra of HDPE rocking bands with decreasing temperature.magnified imageHigh‐resolution variable‐temperature FT‐IR spectra of HDPE rocking bands with decreasing temperature.
Discovering new invertebrate neuropeptides using mass spectrometry
Authors: Hummon Amanda B. , Amare Andinet , Sweedler Jonathan V. 
Published: June 2005

AbstractNeuropeptides are a complex set of messenger molecules controlling a wide array of regulatory functions and behaviors within an organism. These neuromodulators are cleaved from longer protein molecules and often experience numerous post‐translational modifications to achieve their bioactive form. As a result of this complexity, sensitive and versatile analysis schemes are needed to characterize neuropeptides. Mass spectrometry (MS) through a variety of approaches has fueled the discovery of hundreds of neuropeptides in invertebrate species in the last decade. Particularly successful are direct tissue and single neuron analyses by matrix‐assisted laser desorption/ionization (MALDI) MS, which has been used to elucidate approximately 440 neuropeptides, and examination of neuronal homogenates by electrospray ionization techniques (ESI), also leading to the characterization of over 450 peptides. Additional MS methods with great promise for the discovery of neuropeptides are MS imaging and large‐scale peptidomics studies in combination with a sequenced genome. © 2005 Wiley Periodicals, Inc.
Role of Electrospun Nanofibers in Stem Cell Technologies and Tissue Engineering
Authors: Boudriot Ulrich , Goetz Bernhard , Dersch Roland , Greiner Andreas , Wendorff Joachim‐H. 
Published: June 2005

AbstractTissue engineering is a promising tool to manage structural and functional defects in bone and cartilage. To provide optimal conditions for three‐dimensional cell growth the use of a scaffold is necessary. The aim of the study was to prove osteogenic differentiation of human mesenchymal stem cells (hMSC) onto a three‐dimensional, nanostructured scaffold of electrospun poly (l‐lactide)‐nanofibers. HMSC were seeded onto this matrix and differentiated for 21 days. Cells clearly preferred a guided growth along the nanofibers and revealed no signs of cell‐death. Osteogenic differentiation of hMSC onto the matrix has been demonstrated. Due to the fine structure, electrospun nanofibers promises to be an ideal scaffold for tissue engineering. They can be enriched with additives and are equally biocompatible and biodegradable.
Ultra‐Hydrophilic Transition Metals as Histophilic Biomaterials
Authors: Jennissen Herbert P. 
Published: June 2005

AbstractExtremely hydrophilic surfaces have been prepared on titanium, stainless steel and cobalt chromium alloys after treatment by a chromosulfuric acid method at 200‐240 °C. In spite of a ca. 300‐500‐fold higher surface roughness (Ra ∼ 880‐1100 nm) in comparison to the quartz glass controls (Ra ∼ 2‐3 nm), surfaces with contact angles close to 0° in the absence of contact angle hysteresis (ultra‐hydrophilic surfaces) were obtained. We have called this phenomenon “Inverse Lotus Effect”. Metal surface layers exhibiting such properties form excellent priming coats with bioadhesive properties (histophilic surfaces) for the attachment of biocoats consisting of BMP‐2 with bioactive properties in bone. Direct immobilization of BMP‐2 on implant surfaces eliminates the need for a separate BMP‐2 carrier or delivery system such as collagen, as is widely employed by others. A fundamental problem in such surfaces is that it is not at all certain that a protein immobilized in such a manner will retain its biological activity. In the case of BMP‐2 it can be shown in vitro that the novel surfaces are biologically active. Similarly in vivo studies indicate an accelerated and improved osseointegration.
The Effect of Degradation and Stabilization on the Mechanical Properties of Polymers Using Polypropylene Blends as the Main Example
Authors: Kausch H.H. 
Published: June 2005

AbstractDegradation can result from a variety of chemical, physical and mechanical mechanisms, most of them involving a reduction of molecular weight and thus a decrease in the mechanical performance of the degraded polymer. A clear understanding and control of these mechanisms is absolutely essential: without stabilization some polymers (e.g. PVC, polyolefins) would not survive their processing undamaged. In this paper an overview of the different degradation mechanisms, their effect on molecular chains, and the methods used to characterize the extent of degradation will be given. Subsequently we establish some fundamental relationships between the microstructure and the mechanical performance (of thermoplastic polymers) using differently aged and stabilized polypropylene (PP) ‐ EPR compounds.In particular we investigate the influence of two types of heat stabilizers (phenolic antioxidants and hindered amine stabilizer HAS) on the degradation behaviour of test specimens thermally aged at 120 and 135°C respectively. From an investigation of the changes with aging time in structure and low‐strain properties (yield stress, strain at yield, tensile modulus) and from the differences in the evolution of the fracture properties a molecular model of the chain scission mechanisms and of inter‐lamellar connectivity (through tie‐chain molecules) has been established, which allowed an explanation of the gradual change of the dominant deformation mechanism from cold drawing to crazing and brittle fracture.
Degradation of Polyolefins Prepared with Fischer‐Tropsch Derived Olefins
Authors: Tincul I. , Govender V. Thakally 
Published: June 2005

AbstractDegradation of some copolymers of ethylene with Fischer‐Tropsch derived olefins was investigated. Hydroperoxide and carbonyl formation in samples of ethylene copolymers with heptene‐1, and ethylene multiple polymers with the Fischer‐Tropsch derived 3,4 methyl‐pentene and linear olefins were monitored by IR spectroscopy. The results correlated with results obtained from thermogravimetry, multiple extrusion and rheology in previous studies. It was shown that degradation of ethylene with Fischer‐Tropsch derived olefins is related to the type of branch introduced into the chain by the copolymerization with the particular olefin.