Spin Caloritronics

This is a brief overview of the state of the art of spin caloritronics, the science and technology of controlling heat currents by the electron spin degree of freedom (and vice versa).Comment: To be published in "Spin Current", edited by S. Maekawa, E. Saitoh, S. Valenzuela and Y. Kimura, Oxford University Pres

Nitrate deposition in northern hardwood forests and the nitrogen metabolism of Acer saccharum marsh

It is generally assumed that plant assimilation constitutes the major sink for anthropogenic Nitrate NO 3 − deposited in temperate forests because plant growth is usually limited by nitrogen (N) availability. Nevertheless, plants are known to vary widely in their capacity for NO 3 − uptake and assimilation, and few studies have directly measured these parameters for overstory trees. Using a combination of field and greenhouse experiments, we studied the N nutrition of Acer saccharum Marsh. in four northern hardwood forests receiving experimental NO 3 − additions equivalent to 30 kg N ha −1 year −1 . We measured leaf and fine-root nitrate reductase activity (NRA) of overstory trees using an in vivo assay and used 15 N to determine the kinetic parameters of NO 3 − uptake by excised fine roots. In two greenhouse experiments, we measured leaf and root NRA in A. saccharum seedlings fertilized with 0–3.5 g NO 3 − −N m −2 and determined the kinetic parameters of NO 3 − and NH 4 + uptake in excised roots of seedlings. In both overstory trees and seedlings, rates of leaf and fine root NRA were substantially lower than previously reported rates for most woody plants and showed no response to NO 3 − fertilization (range = non-detectable to 33 nmol NO 2 − g −1 h −1 ). Maximal rates of NO 3 − uptake in overstory trees also were low, ranging from 0.2 to 1.0 μmol g −1 h −1 . In seedlings, the mean V max for NO 3 − uptake in fine roots (1 μmol g −1 h −1 ) was approximately 30 times lower than the V max for NH 4 + uptake (33 μmol g −1 h −1 ). Our results suggest that A. saccharum satisfies its N demand through rapid NH 4 + uptake and may have a limited capacity to serve as a direct sink for atmospheric additions of NO 3 − .Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/47695/1/442_2004_Article_BF00334659.pd

Stříbrem dopovaný hydroxidapatitový povlak nanášený pomocí suspenzního plazmatického nástřiku

Čistá suspenze hydroxidapatatu byla vyrobena pomocí chemické sysntézy. S použitím WSP hořáku byl vytvořen HA povlak na substrátu z SS304 a Ti6Al4V. Vlastnosti povlaku byly hodnoceny pomocí SEM, XRD a EDX. PO dopozici bylo dosaženo 4-10% podílu amorfní fáze a 75-82% krystalické HA fáze v tloušťcě cca 145 um. Tribologické chování bylo hodnoceno pomocí testu pin-on-disc. Přídavek AgNO3 do suspenze vedl k vzniku Ag disperze mezi splaty v 8% podílu Ag. Úspěšné přidání antibakteriálního Ag je pokrokem v oblasti výzkumu materiálů kloubních náhrad.Pure hydroxyapatite suspension was produced by wet chemical synthesis. Using a hybrid water-stabilized torch, a series of HA coatings were produced on SS304 and Ti6Al4V substrates and their properties were characterized by SEM, EDX and XRD techniques. After deposition, the amorphous phase content reached 6-10% and the coatings retained 75-82% of crystalline HA phase. Their thickness reached 145 lm. To understand the wear behavior of the coatings, pin-on-disc tribology evaluation was performed. Additionally, a set of HA coatings was prepared with pure metallic Ag content. This formed by in situ chemical decomposition of AgNO3 added into the HA suspension. The Ag was dispersed evenly within the coatings in the form of submicron-sized particles situated predominantly along the HA splats boundaries with a total Ag content of 8 wt.%. Given the antibacterial properties of Ag, such result presents a promising step forward in the hard tissue replacement research

Landscape, regional and global estimates of nitrogen flux from land to sea: errors and uncertainties

Regional to global scale modelling of N flux from land to ocean has progressed to date through the development of simple empirical models representing bulk N flux rates from large watersheds, regions, or continents on the basis of a limited selection of model parameters. Watershed scale N flux modelling has developed a range of physically-based approaches ranging from models where N flux rates are predicted through a physical representation of the processes involved, through to catchment scale models which provide a simplified representation of true systems behaviour. Generally, these watershed scale models describe within their structure the dominant process controls on N flux at the catchment or watershed scale, and take into account variations in the extent to which these processes control N flux rates as a function of landscape sensitivity to N cycling and export. This paper addresses the nature of the errors and uncertainties inherent in existing regional to global scale models, and the nature of error propagation associated with upscaling from small catchment to regional scale through a suite of spatial aggregation and conceptual lumping experiments conducted on a validated watershed scale model, the export coefficient model. Results from the analysis support the findings of other researchers developing macroscale models in allied research fields. Conclusions from the study confirm that reliable and accurate regional scale N flux modelling needs to take account of the heterogeneity of landscapes and the impact that this has on N cycling processes within homogenous landscape units

Service employee burnout and engagement: the moderating role of power distance orientation

Studies show that service employees are among the most disengaged in the workforce. To better understand service employees’ job engagement, this study broadens the scope of the job demands-resources (JD-R) model to include power distance orientation (PDO). The inclusion of PDO enriches the JD-R model by providing a key piece of information that has been missing in prior JD-R models: employees’ perceptions of the source of job demands (i.e., supervisors) or employees’ views of power and hierarchy within the organization. Study 1 uses a survey-based field study to show that employees with a high (compared to low) PDO feel more burnout due to supervisors when they are closely monitored by their supervisors. Study 1 further supports the finding that employees with high (compared to low) PDO feel less disengagement despite burnout due to supervisors. Study 2, using a lab experiment, and Study 3, relying on a survey-based field study, unveil why these effects were observed. Stress and job satisfaction emerge as mediators that explain the findings from Study 1. Implications of the role of PDO are discussed to improve the current understanding of how job engagement can improve customer service performance