bluuebunny/crossref_metadata_2025 huggingface dataset:
Development of Internal Stresses in Alumina-Zirconia Laminates
Authors: Chlup Zdeněk , Hadraba Hynek , Drdlík Daniel , Maca Karel , Dlouhý Ivo
Published: March 2012

The laminated ceramics can provide a flaw tolerant behaviour compare to the monolithic ceramics. Two ways how to ensure flaw tolerant behaviour of layered materials are known. The first is based on production of weak interfaces between layers allowing delamination without catastrophic failure. The second way, on the contrary, uses strong bond between layers ensuring high strength and stiffness. The presence of internal stresses developed due to differences in shrinkage of individual layers can effectively change the crack path or even more to stop the crack propagation. Laminated structures with strong bond between layers can be prepared by various methods including tape casting, slip casting and last but not least by electrophoretic deposition. The electrophoretic deposition is probably the most suitable method which is able to create sharp and therefore strong interface in wide range of preciously set layer thicknesses. This contribution demonstrates a way how to determine level of internal stresses based on combined numerical simulation and dilatometric measurements. For this purposes alumina and zirconia monoliths and laminates were prepared. The numerical model of laminated structure using measured data was created for FEM simulation to obtain a stress distribution.
Shiphull Welding: Trajectory Generation Strategies Using a Retrofit Welding Robot
Authors: Hascoet Jean Yves , Hamilton K. , Carabin G. , Rauch M. , Alonso M. , Ares E.
Published: March 2012

Shipbuilding processes involve highly dangerous manual welding operations. Welding of ship hulls presents a hazardous environment for workers. This paper describes a new robotic system, developed by the SHIPWELD consortium, that moves autonomously on the hull and automatically executes the required welding processes. Specific focus is placed on the trajectory control of such a system and forms the basis for the discussion in this paper. It includes a description of the robotic hardware design as well as some methodology used to establish the torch trajectory control.
Application of Different Simulation Strategies for the Analysis of Multi-Stroke Localised-Incremental Forging Operations
Authors: Camacho A.M. , Marín M.M. , Rubio E.M. , Sebastián M.A.
Published: March 2012

The analysis of LIF operations is often difficult, especially when several strokes are necessary to obtain the final shape of the part. The use of FE models is highly recommended and it is known that implicit FE models give more robust results than explicit FE models; however, with the former methodology there are several problems that must be faced. With the main goal to extend the analysis capability of LIF operations, some explicit FE models are developed in this paper and results are compared to those obtained by implicit methodology. It can be concluded that taking into account these guidelines, the developed models could be further used in the analysis of multi-strokes LIF operations, where more complicated trajectories are going to be used.
Customizing Food with an Additive Manufacturing Technology
Authors: Serenó L. , Delgado J. , de Ciurana Joaquim
Published: March 2012

The development of open Additive Manufacturing (AM) technologies, such as the Fab@Home system, has emerged as a freeform approach capable of producing complex three-dimensional objects with a broad variety of materials. The main objective of this work is to analyze and optimize the manufacturing capacity of this system when producing 3D edible objects. A new heated syringe deposition tool was developed and several process parameters were optimized to adapt this technology to consumers needs. The results revealed in this study show the potential of this system to produce customized edible objects without qualified personnel knowledge, therefore saving manufacturing costs compared to traditional technologies.
Experimental Analysis of Laser Micro-Machining Process Parameters
Authors: Teixidor Daniel , Ferrer I. , de Ciurana Joaquim
Published: March 2012

This paper reports the characterization of laser machining (milling) process to manufacture micro-channels in order to understand the incidence of process parameters on the final features. Selection of process operational parameters is highly critical for successful laser micromachining. A set of designed experiments is carried out in a pulsed Nd:YAG laser system using AISI H13 hardened tool steel as work material. Several micro-channels have been manufactured as micro-mold cavities varying different process parameter. Results are obtained by evaluating the dimensions and the surface finish of the micro-channel. The dimensions and shape of the micro-channels produced with laser-micro-milling process exhibit variations. In general the use of low scanning speeds increases the quality of the feature in both surface finishing and dimensional.
FEM Modeling and Experimental Analysis of AA6082 Processed by ECAE
Authors: Puertas Ignacio , Luis-Pérez C.J. , Luri Rodrigo , León Javier , Fuertes Juan Pablo
Published: March 2012

Recent studies have shown that Severe Plastic Deformation (SPD) processes improve the mechanical properties of the parts processed, through a reduction in the grain size. Equal Channel Angular Extrusion (ECAE) is one of the best -known SPD processes. A study was made of the force and the strain after two ECAE passages, as well as of the damage imparted to AA-6082, by means of experiments and Finite Element Simulations (FEM). The aim of this present research is to make a comparative study between experimental results and those obtained by FEM in order to verify the feasibility of these FEM simulations. In addition to this, it is intended to analyze the homogeneity obtained in the strain values after two ECAE passages made through route C.
Microstructure of the Ni-W Solid Solution Prepared by Levitation and after High Pressure Torsion Severe Plastic Deformation
Authors: Czeppe Tomasz , Sypień Anna , Korznikova Galia F. , Korznikov Alexander
Published: March 2012

The Ni-4at%W alloys was prepared with cold crucible levitation, subsequent levitation re-melting and high pressure torsion (HPT) intensive deformation. In samples after levitation precipitates of Ni4W phase as well as grain boundary continuous phase were formed. Levitation re-melting resulted in partial dissolution of the precipitates, increasing W content in the matrix and lead to the microstructure refinement. The deformation by HPT, in the range of 300-400%, lead to the lead to the homogenization of the solid solution and partial decomposition of the alloys into pure Ni and W. In the homogenous majority of the sample the microstructure transformed from dendrite microstructure to faceted grains. The analysis of the grains sizes and shapes showed that the average grain size in the sample re-melted by levitation was twice the grain size of the sample only prepared with CCLM. Also, the grains in this sample were elongated by 50-60% in one direction, while in the sample prepared by CCLM they were equiaxial. As the nominal composition of the alloys in both cases was the same, differences observed in the microstructure after re-melting and HPT processing must result only from the differences in the cooling rate leading to small differences in W content in solid solution and phase composition after solidification. High rate of cooling in the levitation methods resulted in Ni4W metastable phase precipitation as well as in the refinement of the microstructure, stronger after additional re-melting of the alloy by levitation.
Orientation and Phase Mapping in TEM Microscopy (EBSD-TEM Like): Applications to Materials Science
Authors: Rauch Edgar F. , Véron Muriel , Nicolopoulos Stavros , Bultreys Daniel
Published: March 2012

EBSD is a well known technique that allows orientation and phase mapping using an SEM. Although the technique is very powerful, has serious limitations related with a) special resolution limited to 50 nm (SEM-FEG) and b) specimen preparation issues as is not possible to obtain EBSD signal from rough surfaces or strained materials , nanoparticles etc.. To address those difficulties , a novel technique has been developed recently (EBSD-TEM like) allowing automatic orientation and phase mapping using template matching analysis of acquired diffraction patterns in TEM. Electron beam is scanned through the sample area of interest ; the acquired electron diffraction patterns from several sample locations are compared via cross-correlation matching techniques with pre-calculted simulated templates to reveal local crystal orientation and phases. The dedicated device (ASTAR) allows orientation and phase identification of crystallographic orientation in a region of interest up to 10µm2, with a step size ranging from 1nm to 20nm depending on the transmission electron microscope setting (FEG or LaB6).
Microstructure of AgNi and AgSnBi Powders Consolidated by CEC
Authors: Richert Maria W. , Richert Jan , Książek Marzanna , Hotloś Agnieszka , Pałka Paweł , Perek-Nowak Małgorzata , Maślanka Marcin
Published: March 2012

Powder metallurgy is widely used to the production of AgNi and AgSnBi powders employed for electrical contacts. In the work AgNi and AgSnBi powders were consolidated by the cyclic extrusion compression (CEC) method enabling cyclic unlimited deformation. In the initial stage the AgNi powder contained the two phases Ag and Ni, recognized by the EDX technique using scanning electron microscopy (SEM). The investigations shown that the Ni phase is distributed in the form of small granules around larger Ag granules. In the AgSnBi powder phases Ag + Bi + Ag3Sn (ξ) were distributed uniformly. It was found that after the CEC consolidation phases were excellently joined without cavities and cracks. Detailed observations of microstructure have been performed by the transmission electron microscopy (TEM) and revealed inside the consolidated granules nanometric grains with the nanometric twins inside.
Correlation between SEM and X-Ray Diffraction Imaging of Defect Structure in Single-Crystal Ni-Based Superalloy
Authors: Bogdanowicz Włodzimierz , Albrecht Robert , Sieniawski Jan , Kubiak Krzysztof , Onyszko Arkadiusz
Published: March 2012

In the work the single-crystalline alloy CMSX-4 was studied. The main aim of the study was an attempt to find correlations between images of X-Ray topography, X-ray diffraction maps of lattice parameter and misorientation angle and Scanning Electron Microscopy (SEM) images obtained by back-scattered electron (BSE) technique. Topography images were obtained by Auleytner method with wide beam. Diffractometer provided by EFG company was used for obtaining orientation and lattice parameter maps. Material for research was produced in Research and Development Laboratory for Aerospace Materials of Rzeszów University of Technology. Casts were obtained in ALD furnace by the Bridgman technique. It was found that X-ray topograms were correlated with SEM images of microstructures as well as with orientation and lattice parameter maps. X-Ray topograms showed high contrast bands which corresponded to dendrite arms. There was a correlation between low angle boundary and lattice parameter map.
High Temperature Deformation of Superalloy Inconel 718
Authors: Nowotnik Andrzej
Published: March 2012

Experimental results on hot deformation and dynamic structural processes of nickel based alloy Inconel 718 are reviewed. The focus is the analysis of dynamic precipitation processes which operate during hot deformation of these materials at elevated temperatures. Hot compression tests were performed on the solution treated precipitation hardenable nickel based superalloy Inconel 718 at 720-1150°C with a constant true strain rates of 10-4 and 4x10-4s-1. True stress - true strain curves and microstructure analysis of the deformed nickel based superalloy is presented. The properties and dynamic behaviour are explained through observation of the microstructure using standard optical, scanning and transmission electron microscopy. Structural observations of solution treated Inconel 718 deformed at high temperatures, reveal non uniform deformation effects. The distribution of niobium-rich carbides were affected by localized flow within the strain range investigated at relatively low deformation temperatures 720 - 850°C.
Microstructure Investigation in Thin Films WO3 Produced by Pulsed Laser Deposition
Authors: Kopia Agnieszka
Published: March 2012

The WO3 films were grown by pulsed laser deposition on Si [100] substrate, using an Nd-YAG laser (=355 mm, LOTIS TII). The substrate was heated from 25°C up to 650°C and the films were deposited in oxygen pressures 5 Pa. To characterize the structure and morphology of the surface we used the XPS, Transmission and High Resolution Electron Microscopy (TEM, HREM). From XPS analyses, it was clearly established, that even though in PLD process was used oxygen atmosphere in thin films we observed two phases WO3 and small amount WO2. The amorphous structure with small crystalline we observed in thin films obtained at ambiance temperature. At temperature T = 650 °C TEM analysis show crystalline structure with crystalline about 5 ÷ 10 nm.
Microstructural Investigations of Ca and La Doped CoO Thin Films Prepared by Pulsed Laser Deposition Technique
Authors: Cieniek Łukasz , Kusiński Jan
Published: March 2012

Two types of different oxides multifunctional thin films were deposited by PLD technique on the surface of Si and MgO substrates. First of them was CoO doped with Ca content characterized by fcc (halite) structure and second one was perovskite-type LaCoO3 compound. Their microstructure, chemical/phase composition and morphology were examined by means of diverse techniques (SEM, TEM, EDS). For the surface topography observations of thin films the Atomic Force Microscopy (AFM) was applied. Nanohardness and scratch tests (adhesion measurements) were also performed for estimation of (Co,Ca)O and LaCoO3 films mechanical properties and quality. Obtained results confirm that using PLD technique it is possible to carry stoichiometric composition of different compounds from the target to single crystal substrate however the microstructure and properties of obtained thin films are highly influenced by the substrate’s material and laser ablation parameters (laser wavelength, energy density, time and target-substrate distance).
Effect of Silicon Additions in CrSi (10, 20, 30, 40 at. % Si) Magnetron Targets on Microstructure of Reactively Deposited (Cr,Si)N Coatings
Authors: Grzonka Justyna , Mania Ryszard , Lábár János L. , Morgiel Jerzy
Published: March 2012

The CrSi compacts containing 10, 20, 30 and 40 at. % Si sintered from mixed elemental powders were used as targets for reactively deposited magnetron (Cr,Si)N coatings. The silicon substrates were kept either at ambient temperature or heated up to 600 °C. The microstructure observations were performed using TECNAI FEG (200 kV) with EDAX X-ray Energy Dispersive Spectroscopy (EDS) system and JEOL 3010 (300 kV) with Gatan Energy Filtering (GIF) attachment microscopes. The thin foils were cut using QUANTA Focused Ion Beam (FIB) system. The performed investigations proved that increasing silicon content in coatings deposited at 600 °C using CrSi10, CrSi20 and CrSi30 targets caused a refining of their fully crystalline CrN-type columnar microstructure from ~ 40 to ~ 35 and ~ 25 nm. The deposition performed from the same targets, but at ambient temperatures, i.e. without resistive heating of the substrates, produced coatings of mixed crystalline-amorphous type. They were characterized by gradient microstructure, i.e. amorphous material was prevailing close to the substrate and decreasing close to coating surface. The rising of silicon content in the targets resulted in decreasing amount of crystalline phase. The coatings obtained from Cr40Si target were fully amorphous independently of substrate temperature during deposition. The measurements of local chemical compositions obtained using EDS technique indicated that the Cr:Si ratio in the coatings roughly reproduced that present in the targets used for their deposition. Additionally, these measurements indicated that all coatings are contaminated with oxygen. The mapping of chemical composition using GIF technique of mixed crystalline-amorphous coatings proved that they are enriched in Cr and Si, respectively. The present results showed, that relying on single CrSi target magnetron sputtering the crystalline-amorphous nano-composite could be obtain at silicon additions from 10 to 30 at %, i.e. well above were that type of microstructure is formed during deposition using double target magnetron systems. Additionally, for the first time, the measurements helped to prove that the crystallites and amorphous material are enriched in chromium and silicon respectively, i.e. confirmed presence of CrN/Si3N4 composite.
TEM Studies of Structure of Ag Base Nanocomposite Strengthened with Amorphous NiNbTiZr Alloy Intended for Electric Contact Materials
Authors: Dutkiewicz Jan , Lityńska-Dobrzyńska Lidia , Berent Katarzyna , Woch Mieczysław , Osadnik Małgorzata
Published: March 2012

The nanocrystalline silver powder and the amorphous powders of composition Ni49,5Ti20,5Nb15Zr15 (numbers indicate at%) were prepared by ball milling in the planetary Fritsch mill for 40 hours. TEM studies confirmed almost complete amorphization of milled alloys powders allowed to detect a small fraction of a small intermetallic inclusions within the amorphous matrix. The erosion of composites during contact cycling was similar as in Ag-W composites known as a good contact materials. SEM and TEM studies have shown a low solubility of tungsten in silver after ball milling and no solubility of silver in tungsten. The grain size of silver crystals within powders drastically decreased after milling down to about 30 nm and only a small increase in the grain size up to 200 nm was observed after hot pressing. These results were confirmed using TEM studies of composites after hot pressing. TEM microstructures have shown very narrow transition layer at the amorphous/silver interface (between 10-30 nm thick) containing all elements from the amorphous powders plus silver due to short time of hot pressing. The amorphous part has shown growth of intermetallic phases there, however diffused ring from the amorphous part was still visible. The composites prepared from silver and tungsten have shown presence of coherent tungsten rich precipitates showing typical strain field contrast within fine grains near 100 nm formed most probably during hot pressing of silver solid solution formed during mechanical alloying. The structure of tungsten has shown less defects and consequently less grain refinement than silver particles. SEM studies of the compression tested samples of silver-amorphous composites have shown crack formation at the interfaces of both components most probably due to presence of a brittle transition phase containing all elements.
Microstructure and Mechanical Properties of PVD Nanoncrystalline Layers
Authors: Lukaszkowicz Krzysztof , Konieczny Jarosław
Published: March 2012

This work presents the research results on the structure and mechanical properties of coatings deposited by PVD methods on the X40CrMoV5-1 hot work tool steel substrates. It was found that tested coatings have nanostructural character with fine crystallites, while their average size fitted within the range 10–15 nm, depending on the coating type. The morphology of the fracture of coatings is characterized by a dense microstructure. The coatings demonstrated good adhesion to the substrate, the latter not only being the effect of interatomic and intermolecular interactions, but also by the transition zone between the coating and the substrate, developed as a result of diffusion and high-energy ion action that caused mixing of the elements in the interface zone and the compression stresses values. The critical load LC2 lies within the range 66–85 N, depending on the coating type. The coatings demonstrate a high hardness (4000 HV).
Microstructural Investigation of the Ferritic GX12CrMoVNbN9-1 (GP91) Cast Steel
Authors: Golański Grzegorz , Wieczorek Paweł
Published: March 2012

The paper presents research on the microstructure of high chromium martensitic GX12CrMoVNbN9-1 (GP91) cast steel. The steel was subject to investigation in the as-cast state, after hardening as well as after quenching and tempering. The microstructure and morphology of precipitates in GP91 cast steel was examined in terms of changes taking place during the technological process. It has been shown that the examined cast steel is characterized by a microstructure of lath martensite (and polygonized ferrite) with numerous precipitates, such as: M3C, M23C6 and MX (NbC, VX) of diverse morphology. Tempered martensite in the cast steel consists of former austenite grains separated by high angle grain boundaries. These grains are subdivided by high angle boundaries into blocks of martensite laths. The dislocation density of the tempered martensite is high (of about 1014 m-2).
Identification of Phases in Alloy Steels after Quenching and after Isothermal Quenching
Authors: Smalc-Koziorowska Julita , Jezierska Elżbieta , Świątnicki Wiesław
Published: March 2012

The purpose of the work is the analysis and the identification of phases in alloy steels after various heat treatments by means of transmission electron microscopy. We have investigated the phases formed during austenitising followed by quenching with various rates or by isothermal quenching, as martensite, upper and lower bainite. In order to identify the phases, we used their morphological characteristics and the kind of orientation relationship between the given phase and the austenite. We concluded that the identification of phases occurring in steels after various heat treatments may be performed in a clear manner according to their morphological features combined with the diffraction patterns analysis as observed by transmission electron microscopy.
3D Imaging and Metrology of Yttria Dispersoids in INCOLOY MA956 by Electron Tomography
Authors: Kruk Adam , Dubiel Beata , Czyrska-Filemonowicz Aleksandra
Published: March 2012

TEM, HAADF-STEM tomography and FIB/SEM tomography studies have been carried out to visualize three-dimensional morphology of the oxide dispersoids in ferritic ODS alloy INCOLOY MA956. Electron tomography results provided quantitative data about particle shape, size and distribution of the particles, complementary to those obtained by means of quantitative TEM metallography. It was shown that FIB/SEM, a meso-scale tomography technique, is suitable for 3D reconstruction of the objects of 100 nm in size or even smaller.
Investigations of Fine Grained Metallic Materials by Means of Orientation Maps in Transmission Electron Microscope
Authors: Bieda Magdalena
Published: March 2012

New subdivision of microscopic investigation called Orientation Microscopy (OM) is already well known in scanning electron microscope (SEM). Needs for investigation in nanoscale contribute to development of an appropriate method for transmission electron microscope (TEM). Automated acquisition and indexing of diffraction patterns, necessary for creation of orientation maps in TEM, cause more difficulties then in SEM. Nevertheless, the techniques of OM are also being developed in the Transmission Electron Microscope (TEM). Microdiffraction has been successfully introduced for creating such maps. Individual orientation measurements, which appeared in the convergent beam mode, can be used for quantitative description of microstructure of fine grained and deformed materials. The idea of the operation of the automated system in transmission electron microscope (TEM) which is developed in IMIM PAS relies on an automatic (with control position of the beam) acquisition of diffraction patterns using digital CCD camera, and indexing them, and then on the analysis of the set of individual crystallographic orientations. The graphic presentation of received sets of orientation can be analysed in order to obtain parameters and characteristics such as texture characteristics, characteristics of grain boundaries (based on orientation relationship) or the stereological characteristics. To illustrate application of this system, orientation maps measured in cold-rolled polycrystalline aluminium and its alloy 6013, and in multi-phase alloys of Fe-Cr-Co system after severe plastic deformation are presented.
Characterization of Grain Boundary Geometry in the TEM, Exemplified in Si Thin Films
Authors: Lábár János L. , Kiss Ákos K. , Christiansen Silke , Falk Fritz
Published: March 2012

A method is presented here for complete geometrical characterization of grain boundaries, based on measurement of thin films in the TEM. First, the three parameters, characterizing the misorientation of the two neighboring grains are determined from convergent beam electron diffraction (CBED). Next, the last two (of the total five macroscopic degrees of freedom) parameters are determined from bright field (BF) images to describe the orientation of the boundary plane between them. Ambiguity in the tilt direction of the plane is resolved from BF images recorded at two distinct goniometer settings. Application of the method is demonstrated in Silicon thin films. GB-plane distribution in a thin film is not necessarily identical to the distribution of similar planes in bulk materials. It was observed in low dimensional fcc metals (wires or thin films) that energy minimization of GBs can follow two (mainly alternative) routes. Either low energy planes (like {111}) are formed in 3 boundaries, or alternatively, it is observed that the GB plane has a general index (and high energy density) but it ends at both free surfaces of the sample, resulting in a GB, almost normal to the sample surface, minimizing the total area of the GB. We observed that this later type of planes is mainly characteristic of non-3 boundaries in thin Si films, crystallized from melt on glass substrates (separated by a thin SiN barrier layer). This observation is important for the expected recombination properties of the multicrystalline Si (m-Si) in planned solar cell (SC) applications.
Nanotexture Studies of NiTi Shape Memory Alloy after Severe Plastic Deformation with the Use of TEM
Authors: Stróż Danuta , Palka Jakub , Lekston Zdzisław
Published: March 2012

In this paper a specific method of severe plastic deformation (SPD) applied to the NiTi shape memory alloy and the obtained structure and the alloy properties are presented. Cold rolling combined with transverse movement of the rolls was the method. The maximal strain obtained was εc ≈ 10.20 for the relatively large specimens. Then the alloy was annealed in order to obtain samples of a given grain size. In the paper the structure of the alloy annealed at 350°C was studied with the use of TEM equipped with Nanomegas attachment ASTAR allowing determination of the orientation of grains in nanoareas.
Profound Depletion of Host Conventional Dendritic Cells, Plasmacytoid Dendritic Cells, and B Cells Does Not Prevent Graft-versus-Host Disease Induction
Authors: Li Hongmei , Demetris Anthony J. , McNiff Jennifer , Matte-Martone Catherine , Tan Hung Sheng , Rothstein David M. , Lakkis Fadi G. , Shlomchik Warren D.
Published: March 2012

The efficacy of allogeneic hematopoietic stem cell transplantation is limited by graft-versus-host disease (GVHD). Host hematopoietic APCs are important initiators of GVHD, making them logical targets for GVHD prevention. Conventional dendritic cells (DCs) are key APCs for T cell responses in other models of T cell immunity, and they are sufficient for GVHD induction. However, we report in this article that in two polyclonal GVHD models in which host hematopoietic APCs are essential, GVHD was not decreased when recipient conventional DCs were inducibly or constitutively deleted. Additional profound depletion of plasmacytoid DCs and B cells, with or without partial depletion of CD11b+ cells, also did not ameliorate GVHD. These data indicate that, in contrast with pathogen models, there is a surprising redundancy as to which host cells can initiate GVHD. Alternatively, very low numbers of targeted APCs were sufficient. We hypothesize the difference in APC requirements in pathogen and GVHD models relates to the availability of target Ags. In antipathogen responses, specialized APCs are uniquely equipped to acquire and present exogenous Ags, whereas in GVHD, all host cells directly present alloantigens. These studies make it unlikely that reagent-based host APC depletion will prevent GVHD in the clinic.
Long-term fertilization effects on carbon and nitrogen in particle-size fractions of a Chinese Mollisol
Authors: Yan Y. , He H. , Zhang X. , Chen Y. , Xie H. , Bai Z. , Zhu P. , Ren J. , Wang L.
Published: March 2012

Yan, Y., He, H., Zhang, X., Chen, Y., Xie, H., Bai, Z., Zhu, P., Ren, J. and Wang, L. 2012. Long-term fertilization effects on carbon and nitrogen in particle-size fractions of a Chinese Mollisol. Can. J. Soil Sci. 92: 509–519. The response of soil organic matter (SOM) dynamics to long-term fertilization may be deduced from changes in the accumulation and distribution of different soil organic carbon (SOC) and nitrogen (N) pools. The SOC and N in particle-size fractions were therefore measured to assess the influences of pig manure and synthetic fertilizer application on the characteristics of these pools. A long-term fertilization experiment, established in 1979 in the Mollisol area (Gongzhuling, China) was used for this study. Composite soil samples (0–20cm) were collected in 2005 from 12 treatment plots that had received annual applications of pig manure, synthetic fertilizers or combinations of both. Soils were fractionated into fine clay (<0.2 µm), coarse clay (0.2–2 µm), silt (2–50 µm), fine sand (50–250 µm) and coarse sand (250–2000 µm) and then SOC and N contents in each particle-size fraction were measured. Although most of the SOC and N were associated with clay and silt fractions, the large proportion of silt in the soil mass played a key role in the retention of SOC and N. The application of pig manure alone increased accumulation of SOC and N in each particle-size fraction, but preferential enrichment was found in the coarse sand fraction. This indicates that pig manure is efficient in restoring SOM in the temperate Chinese Mollisol under a tilled maize (Zea mays L.) monocropping system and having a long frozen period in winter. The application of synthetic fertilizers had no clear effect on SOC and N accumulation or their distribution in particle-size fractions. However, the combined application of pig manure and synthetic fertilizers enhanced the accumulation of SOC and N in all particle-size fractions, and led to a shift of SOC and N from fine to coarse particles. We extended the hierarchy model for SOC protection to consider a shift in SOC accumulation from fine to coarse particles, depending on the initial SOC content of the specific soil. The findings reveal a clear positive interaction between pig manure and synthetic fertilizers that may improve the quantity of SOM in the temperate Chinese Mollisol.
Estimating changes of residual soil nitrogen in Chernozemic soils in Canada
Authors: Yang J. Y. , Huffman T. , Drury C. F. , Yang X. M. , De Jong R. , Campbell C. A.
Published: March 2012

Yang, J. Y., Huffman, T., Drury, C. F., Yang, X. M., De Jong, R. and Campbell, C. A. 2012. Estimating changes of residual soil nitrogen in Chernozemic soils in Canada. Can. J. Soil Sci. 92: 481–491. Chernozemic soils (Mollisols) account for approximately 68% of total farmland in the prairies and 54% of farmland in Canada. Although many field studies have focused on the importance of N in Chernozemic soils, few modelling studies have been conducted to examine the risk of N contamination to the environment The objective of this research was to estimate temporal and spatial changes in residual soil nitrogen (RSN) on Chernozemic soils at the 1:1 million regional scale. An annual N budget was developed for the study area for the period 1981 to 2006, using the Canadian Agricultural Nitrogen Budget (CANB v3.0) model. The difference between N inputs and outputs is considered RSN, which is defined as the inorganic N left in the soil after harvest. Average RSN levels in the sub-humid Black and Dark Gray Chernozemic soils increased from 7–9 kg N ha−1in 1981 to 20–23 kg N ha−1in 2006. Changes in RSN were much less pronounced in the arid and semi-arid Brown and Dark Brown soil zones, where average values increased from approximately 1 kg N ha−1to 4–7 kg N ha−1over 25 yr. Commercial fertilizer, manure and biological N2fixation were the three main sources of the increased N inputs. Drought conditions also contributed to the surplus of N in some years by reducing crop growth and thus the amount of N removed in grain and forage crops. In Chernozemic soils, more careful use of chemical fertilizer N, improved manure N management and greater use of legume-cereal rotations are recommended as methods to maintain soil fertility and reduce nitrogen loss to the environment.
Field study on macropore flow in typical Black soils of northeast China
Authors: Jiang Xiaojin , Wang Enheng , Chen Xiangwei , Xia Xiangyou , Shi Changting
Published: March 2012

Jiang, X., Wang, E., Chen, X., Xia, X. and Shi, C. 2012. Field study on macropore flow in typical Black soils of northeast China. Can. J. Soil Sci. 92: 559–566. Macropores are important preferential pathways for the transport of water and contaminants in soil. A series of hood infiltration experiments were conducted using dye tracers (Brilliant Blue FCF) at pressure heads of −5.0 cm, −3.0 cm, and −1.0 cm at a conventional tilled site on Keshan Farm, northeast China. The study objective was to combine the test method of dye tracing with a hood infiltrometer to analyze soil subjected to conventional tillage methods. Dye staining patterns and macroporous networks were analyzed by excavation, mapping, photography, and image analysis. Results showed that macropore flow began very near the soil surface under three pressures heads of −5.0 cm, −3.0 cm and −1.0 cm, and that a pressure head of −1.0 cm resulted in more lateral flow. Soil deeper than 40.0 cm was less disturbed, which resulted in good continuity. At pressure heads of −5.0, −3.0 and −1.0 cm, the dye staining technique resulted in maximum stained depths of 74.3, 60.7 and 64.7 cm, respectively, with maximum stained widths of 41.6, 41.5 and 47.9 cm, respectively (at depths from 14.0 to 28.0 cm). Soil under a pressure head of −1.0 cm had the highest initial and steady infiltration rates of 13.0 and 4.1 mm min−1, respectively. Soil under a pressure head of −5.0 cm showed the most connectivity. To distinguish the macropores from the interaction area of macropore flow and the soil matrix surrounding the macropores, the stained area was separated into different classes based on dye color.
Nitrogen loss on tile-drained Mollisols as affected by nitrogen application rate under continuous corn and corn-soybean rotation systems
Authors: Helmers M.J. , Zhou X. , Baker J.L. , Melvin S.W. , Lemke D.W.
Published: March 2012

Helmers, M. J., Zhou, X., Baker, J. L., Melvin, S. W. and Lemke, D. W. 2012. Nitrogen loss on tile-drained Mollisols as affected by nitrogen application rate under continuous corn and corn-soybean rotation systems. Can. J. Soil Sci. 92: 493–499. Nitrate-nitrogen (NO3-N) loss from production agricultural systems through subsurface drainage networks is of local and regional concern throughout the Midwestern United States. The increased corn acreage and the practice of growing continuous corn instead of a corn-soybean rotation system due to the increasing demand for food and energy have raised questions about the environmental impacts of this shift in cropping systems. The objective of this 4-yr (1990–1993) study was to evaluate the effect of nitrogen (N) application rate (0–168 kg N ha−1 for corn following soybean and 0–224 kg N ha−1 for corn following corn) on NO3-N concentration, NO3-N losses, and crop yields in continuous corn and corn-soybean production systems on tile-drained Mollisols in north central Iowa. The results show that NO3-N concentrations from the continuous corn system were similar to NO3-N concentrations from the corn-soybean rotation at equivalent N application rates.When extra N fertilizer (approximately 56 kg N ha−1) was applied to continuous corn than the corn-soybean rotation, this resulted in 14–36% greater NO3-N concentrations in subsurface drainage from the continuous corn system. While corn yield increased as N application rate increased, corn yields at the recommended N application rates (112–168 kg N ha−1) in the corn-soybean rotation were up to 3145 kg ha−1 greater than corn yields at the recommended application rates (168–224 kg N ha−1) in the continuous corn system. The corn-soybean rotation with recommended N application rates (168–224 kg N ha−1) appeared to be beneficial environmentally and economically.
Characterization of seasonal freeze-thaw and potential impacts on soil erosion in northeast China
Authors: Zhao Yusen , Wang Enheng , Cruse Richard M. , Chen Xiangwei
Published: March 2012

Zhao, Y., Wang, E., Cruse, R. M. and Chen, X. 2012. Characterization of seasonal freeze-thaw and potential impacts on soil erosion in northeast China. Can. J. Soil Sci. 92: 567–571. Freeze-thaw cycles are regarded as a critical factor inducing and accelerating gully erosion in the Black soil region (Chernozem) of northeast China. The major objective of this study was to identify the effect of seasonal freeze-thaw processes on soil structure relevant to soil erosion. Perched water due to an argillic horizon brings about higher water potential in the top soil, which lowers the soil shear strength and increases the risk of soil erosion by rainfall and surface flow; and the argillic horizon, with a higher clay content, is more vulnerable to freeze-thaw processes, which break or weaken the structure of the argillic horizon, increasing its vulnerability to gully erosion.
Long-term effects of crop rotations and fertilization on soil C and N in a thin Black Chernozem in southeastern Saskatchewan
Authors: Lemke R.L. , Vandenbygaart A.J. , Campbell C.A. , Lafond G.P. , McConkey B.G. , Grant B.
Published: March 2012

Lemke, R. L., VandenBygaart, A. J., Campbell, C. A., Lafond, G. P., McConkey, B. G. and Grant, B. 2012. Long-term effects of crop rotations and fertilization on soil C and N in a thin Black Chernozem in southeastern Saskatchewan. Can. J. Soil Sci. 92: 449–461. Carbon sequestration in soil is important due to its influence on soil fertility and its impact on the greenhouse gas (GHG) phenomenon. Carbon sequestration is influenced by agronomic factors, but to what extent is still being studied. Long-term agronomic studies provide one of the best means of making such assessments. In this paper we discuss and quantify the effect of cropping frequency, fertilization, legume green manure (LGM) and hay crops in rotations, and tillage on soil organic carbon (SOC) changes in a thin Black Chernozemic fine-textured soil in southeastern Saskatchewan. This was based on a 50-yr (1958–2007) crop rotation experiment which was initiated on land that had previously been in fallow-wheat (Triticum aestivum L.) (F-W), or F-W-W receiving minimum fertilizer for the previous 50 yr. We sampled soil in 1987, 1996 (6 yr after changing from conventional tillage to no-tillage management and increasing N rates markedly) and again in 2007. The SOC (0–15 cm depth) in unfertilized F-W and F-W-W appears not to have changed from the assumed starting level, even after 20 yr of no-till, but SOC in unfertilized continuous wheat (Cont W) increased slightly [not significant (P>0.05)] in 30 yr, but increased more after 20 yr of no-till (but still not significant). No-till plus proper fertilization for 20 yr increased the SOC of F-W, F-W-W and Cont W in direct proportion to cropping frequency. The SOC in the LGM-W-W (unfertilized) system was higher than unfertilized F-W-W in 1987, but 20 yr of no-tillage had no effect, likely because grain yields and C inputs were depressed by inadequate available P. Soil organic carbon in the two aggrading systems [Cont W (N+P) and F-W-W-hay(H)-H-H (unfertilized)] increased significantly (P<0.05) in the first 30 yr; however, a further 20 yr of no-tillage (and increased N in the case of the Cont W) did not increase SOC suggesting that the SOC had reached a steady-state for this soil and management system. The Campbell model effectively simulated SOC changes except for Cont W(N+P), which it overestimated because the model is ineffective in simulating SOC in very fertile systems. After 50 yr, efficiency of conversion of residue C inputs to SOC was negligible for unfertilized F-W and F-W-W, was 3 to 4% for fertilized fallow-containing systems, was about 6 or 7% for Cont W, and about 11% for the unfertilized F-W-W-H-H-H systems.
Quality and dynamics of soil organic matter in a typical Chernozem of Ukraine under different long-term tillage systems
Authors: Kravchenko Y. , Rogovska N. , Petrenko L. , Zhang X. , Song C. , Chen Y.
Published: March 2012

Kravchenko, Y., Rogovska, N., Petrenko, L., Zhang, X., Song, C. and Chen, Y. 2012. Quality and dynamics of soil organic matter in a typical Chernozem of Ukraine under different long-term tillage systems. Can. J. Soil Sci. 92: 429–438. Tillage has been reported to induce changes in soil organic matter (SOM) concentrations and quality. Conversion of plow-tillage to minimum till and no-till (NT) farming enhances the SOM pool. Enrichment of the SOM pool is essential for maintaining fertility of Chernozems, advancing food security, and improving the environment. The main objective of this study was to examine the effect of different tillage systems on the SOM concentration, its quality and dynamics including CO2assimilation by heterotrophic bacteria and humus characteristics – the carbon (C) concentration in humic substances and the labile soil organic C fraction (SOCL) extracted with 0.1 N NaOH – as well as the molecular masses, spectroscopic parameters and physiological effects of humic acids on germinating pea (Pisum sativum L.) seeds. Our study was conducted on a long-term experimental site on a Haplick Chernozem in the Poltava region of Ukraine over a 10-yr period from 1996 to 2006. Results indicate that conversion from conventional to reduced soil tillage systems increased SOM concentrations in 0- to 10-cm soil layer and led to the accumulation of C in fulvic acids and humins. No significant differences in SOM storage in the 0- to 100-cm layer were observed among tillage systems. However, reduced tillage systems had a higher proportion of SOCL, a lower ratio of C in humic acids/C in fulvic acids and more humic acids with molecular masses from 110 to 2000 kDa. Our study demonstrated that the quality and dynamics of SOM are closely related to soil tillage practices.
Burnout in Occupational Therapists and Physical Therapists Working in Head Injury Rehabilitation
Authors: Schlenz Kathleen C. , Guthrie Mark R. , Dudgeon Brian
Published: March 2012

Objectives. Burnout has been linked to job retention in occupational therapy, physical therapy, and other health professions. Professional development activities are often suggested to reduce burnout, but little empirical evidence supports this contention. This study explored the prevalence of burnout among occupational and physical therapists working in head injury rehabilitation and evaluated the relationship between burnout and professional development activities.

Method. Forty therapists working full-time in head injury rehabilitation were surveyed. Correlations between subscale scores of the Maslach Burnout Inventory (i.e., Emotional Exhaustion, Depersonalization, and Personal Accomplishment) and responses to a survey of professional development activities are reported.

Results. Professional development activities are most strongly associated with feelings of personal accomplishment. Emotional exhaustion was relatively high among these therapists, but few feelings of depersonalization were evident.

Conclusions. Professional development activities in the workplace may augment feelings of personal accomplishment and minimize burnout as an issue in job retention. Strategies to effectively identify and manage therapists’ feelings of emotional exhaustion require further study.
Issuing Assistive Devices to Older Patients in Rehabilitation: An Exploratory Study
Authors: Gitlin Laura N. , Burgh Desirée
Published: March 2012

Occupational therapists play a critical role in determining which assistive devices are provided to older adults and when and how instruction occurs during rehabilitation. This exploratory qualitative study used focus group methodology and Fleming’s concept of the therapist with a three-track mind to examine how occupational therapists describe the process of issuing assistive devices to elderly persons in rehabilitation. We identified six interrelated steps involved in issuing an assistive device to an older person with a cerebrovascular accident. These steps were the selection of a device, an activity, a site for instruction, a method of instruction, the time to introduce a device during hospitalization, and reinforcement of its use. Therapists used procedural, interactive, and conditional reasoning to make decisions within each step and individualize device training. The findings from this study underscore the complex series of decisions and skilled clinical judgments involved in issuing assistive devices to older persons. Additionally, the study shows that focus group methodology is a valuable approach by which to identify how therapists reason about specific therapeutic practices.
Polarization data from SCIAMACHY limb backscatter observations compared to vector radiative transfer model simulations
Authors: Liebing P. , Bramstedt K. , Noël S. , Rozanov V. , Bovensmann H. , Burrows J. P.
Published: March 2012

Abstract. SCIAMACHY is a passive imaging spectrometer onboard ENVISAT, designed to obtain trace gas abundances from measured radiances and irradiances in the UV to SWIR range in nadir, limb and occultation viewing modes. Its grating spectrometer introduces a substantial sensitivity to the polarization of the incoming light with nonnegligible effects on the radiometric calibration. To be able to correct for the polarization sensitivity, SCIAMACHY utilizes broadband Polarization Measurement Devices (PMDs). While for the nadir viewing mode the measured atmospheric polarization has been validated against POLDER data (Tilstra and Stammes, 2007, 2010), a similar validation study regarding the limb viewing mode has not yet been performed. This paper aims at an assessment of the quality of the SCIAMACHY limb polarization data. Since limb polarization measurements by other air- or spaceborne instruments in the spectral range of SCIAMACHY are not available, a comparison with radiative transfer simulations by SCIATRAN V3.1(Rozanov et al., 2012) using a wide range of atmospheric parameters is performed. SCIATRAN is a vector radiative transfer model (VRTM) capable of performing calculations of the multiply scattered radiance in a~spherically symmetric atmosphere. The study shows that the limb polarization data exhibit a large systematic bias which is decreasing with wavelength. The most likely reason for this bias is an instrumental phase shift which changes the relative contributions of different Stokes vector components to the PMD signal as compared to on-ground calibration measurements. It is also shown that it is in principle feasible to recalibrate the polarization sensitivity using the in-flight data and the VRTM simulations, enabling also the monitoring of its degradation. Together with an optimization of the algorithm used to calculate the in-flight polarization data an improved polarization correction can increase the radiometric accuracy of SCIAMACHY limb radiance spectra substantially.