bluuebunny/crossref_metadata_2025 huggingface dataset:
Application of fluorescence recovery after photobleaching to diffusion of a polyelectrolyte in a multilayer film
Authors: Picart Catherine , Mutterer Jérôme , Arntz Youri , Voegel Jean‐Claude , Schaaf Pierre , Senger Bernard
Published: April 2005

The diffusion coefficient, D, and the proportion of mobile molecules, p, is measured for a fluorescently labeled polyelectrolyte in a multilayer film using fluorescence recovery after photobleaching (FRAP). The film was composed of poly(L‐lysine) (PLL) and hyaluronan (HA). The labeled polyelectrolyte (PLLFITC) was either deposited on top of the film or embedded within it. A circular area of diameter ≈ 60 μm was bleached using a confocal laser scanning microscope. Because molecules do already diffuse during the bleaching step, the initial light intensity profile is not characteristic of a uniformly bleached circular area. A formalism is developed in which a simple mathematical representation of a measured profile serves as starting profile. This radial distribution is introduced in the equation describing the time evolution of the labeled molecule concentration under the hypothesis that the recovery results from pure, two‐dimensional Brownian diffusion of the mobile molecules according to Fick's law. The analysis of a series of images taken at successive times after bleaching (up to approximately one hour) leads to estimates of D of the order of 0.2 μm2 s−1 for labeled molecules deposited on top of the film and a 5‐fold smaller value for the molecules embedded in the film. However, p is remarkably insensitive to the position in the multilayer architecture (p ≈ 0.40). Microsc. Res. Tech. 66:43–57, 2005. © 2005 Wiley‐Liss, Inc.
Carbon stocks and sequestration potentials of agricultural soils in the federal state of Baden‐Württemberg, SW Germany
Authors: Neufeldt Henry
Published: April 2005

Soil organic carbon (SOC) inventories are important tools for studying the effects of land‐use and climate change and evaluating climate‐change policies. A detailed inventory of SOC in the agricultural soils of the federal state of Baden‐Württemberg was therefore prepared based on the highest‐resolution geo‐referenced soil, land‐use, and climate data (BÜK200 inventory). In order to estimate the quality of different approaches, C inventories of the region were also prepared based on data from the National Inventory Report (UBA, 2003) and by applying the IPCC (1997) method to the two data sets. Finally, the BÜK200 inventory was used to estimate potentials of no‐tillage agriculture (NT) and peatland restoration to contribute to C sequestration and greenhouse‐gas (GHG)‐emission mitigation since both measures are discussed in this context. Scenario assumptions were change to NT on 40% of the cropland and restoration of 50% of cultivated peatlands within 20 years.

On average, grasslands contained 9.5 kg C m–2 to 0.3 m depth as compared to only 6.0 kg C m–2 under cropland, indicating strong land‐use effects. The SOC content depended strongly on waterlogging and elevation, thus reflecting reduced C mineralization under aquic moisture regimes and low temperatures. Comparison of the BÜK200 inventory with the approach used for UBA (2003) showed high inconsistencies due to map resolution and SOC contents, whereas the IPCC method led to fairly good agreements. Results on the simulated effects of NT and peatland restoration suggested that 5%–14% of total agricultural GHG emissions could be abated with NT whereas peat restoration appeared to have a minor mitigation potential (0.2%–2.7%) because the total area of cultivated organic soils was too small to have larger impact.
Changes in P fractions and sorption in an Alfisol following crop residues application
Authors: Reddy Damodar D. , Rao Subba A. , Singh Muneshwar
Published: April 2005

With the emphasis on sustainable agriculture, attention has been increasingly turning to recycling of crop residues as a component of fertility management strategies for tropical soils. We assessed the effects of soybean residue (SR) and wheat residue (WR) applied either alone or in combination with fertilizer P (FP) on dynamics of labile P, distribution of P fractions, and P sorption in a semiarid tropical Alfisol by conducting a 16 w long incubation experiment. The amount of P added through crop residues, FP or their combinations was kept constant at 10 mg P (kg soil)–1. Addition of SR or WR resulted in net increase of labile inorganic (Pi) and organic P (Po) and microbial P throughout the incubation period, except that the WR decreased labile Pi during first 2 w due to Pi immobilization. The P immobilization associated with WR addition was, however, offset when fertilizer P was combined with WR. Generally, the increases in labile‐P fractions were larger with the SR and SR+FP than with the WR and WR+FP. The sequential fractionation of soil P at the end of 16 w indicated that a major part of added fertilizer P transformed into moderately labile and stable P fractions as evident from the increased NaOH‐Pi and HCl‐P in the FP treatment. In contrast, the addition of SR and WR alone or in combination with FP favored a build‐up in NaHCO3‐Pi and ‐Po and NaOH‐Po fractions while causing a decrease in NaOH‐Pi and HCl‐P fractions. The addition of these crop residues also effectively decreased the P‐sorption capacity and hence reduced the standard P requirement of the soil (i.e., the amount of P required to maintain optimum solution P concentration of 0.2 mg P l–1) by 24%–43%. Results of the study, thus, imply that soybean and wheat crop residues have the potential to improve P fertility of Alfisols by decreasing P‐sorption capacity and by redistributing soil P in favor of labile‐P fractions and promoting accretion of organic P.
Field measurements of the water content in the top soil using a new capacitance sensor with a flat sensitive volume
Authors: Ruth Bernhard , Munch Jean Charles
Published: April 2005

Water content directly near the soil surface plays an essential role for degradation of natural organic material and agrochemicals by soil microbes. Furthermore, the water losses by evaporation depend sensitively on the top‐soil water content. Rain, irrigation, evaporation, and the water flow between the soil horizons together with the natural inhomogeneity of soils cause a high spatial gradient and a pronounced time dependence of the water content in the top soil. To understand processes in top soil such as redox gradients, the knowledge on ecological conditions in the top soil, which is subject to rapid changes, is essential. In order to meet the requirements for such field measurements, a capacitance sensor with a depth resolution of 1 cm and an active area of 7.5 cm × 14 cm was constructed and operated by a special electronic circuit. Field measurements using these sensors at 1 cm depth showed the high dynamics when measurements were carried out every 10 min. As simultaneous measurements of the soil temperature at 1 cm depth exhibit large temperature variations during the day, its influence on the measurements must be compensated for. As the data, measured during drying periods, allow the assessment of the temperature coefficient, the water content at a reference temperature can be calculated. The course of the water content reflects precipitation events and quantifies the drying of the soil, providing these parameters for process evaluation. Furthermore, the diurnal variation exhibits the drying during the day and the possible rewetting from deeper horizons during the night.
Long‐term effects of cropped vs. fallow and fertilizer amendments on soil organic matter II. Nitrogen
Authors: Singh Antil Rajinder , Gerzabek Martin H. , Haberhauer Georg , Eder Gerfried
Published: April 2005

The present study evaluated the effect of fertilizer amendments (organic manure and mineral fertilizers), management practices (fallow and untilled vs. cropped and tilled) on changes of N in bulk soil and N associated with different particle‐size fractions. The long‐term field experiment was conducted since 1962 in Gumpenstein, Austria, on a Dystric Cambisol. The N content of the topsoils changed distinctively during 28 and 38 yr of treatments under both fallow and cropped management practices. Highest increase in total N content was found in animal‐manure (liquid)‐treated plots. The remaining ranking was: animal manure (solid) > cattle slurry > half cattle slurry + straw = PK = NPK.

Quite short N‐half‐life values of around 2 yr were found for the cattle‐slurry application, while animal manure exhibited longer N‐half‐lives of around 8 yr. Crop removal of N and mineralization losses in cropped plots obviously were higher than N losses from the bare soil plots lacking a plant cover to keep N in the system. This was confirmed by a consistent shift in the natural 15N abundances. Comparing the mean N contribution of particle‐size fractions to the total N amounts revealed the following ranking after 28 and 38 yr of different treatments: silt > clay > fine sand > coarse sand, with small exceptions. Particle‐size separates showed more significant responses to changes in the N dynamics of the system due to the various treatments than the bulk soil and can be regarded as the better indicators in this respect.
Effect of orientation on the free volume and oxygen transport of a polypropylene copolymer
Authors: Somlai L. S. , Liu R. Y. F. , Landoll L. M. , Hiltner A. , Baer E.
Published: April 2005

The effect of uniaxial orientation on the free‐volume and oxygen‐transport properties of a propylene copolymer with 4.5 wt % ethylene was examined. The free‐volume hole size and hole density were measured with positron annihilation lifetime spectroscopy. Subsequently, the free‐volume characteristics were correlated with the oxygen‐transport properties. Orientation had only a small effect on the total amount of free volume: a small increase in the hole density was offset by a small decrease in the hole size. As a result, the oxygen solubility and amorphous‐phase density were unchanged by orientation. However, a pronounced decrease in the oxygen diffusivity when the draw ratio exceeded 6 indicated a change in the dynamic free volume. This was attributed to an increasing number of taut tie chains, which retarded oxygen diffusion. The reduced amorphous chain mobility was also manifest in the increased glass‐transition temperature, decreased bulk thermal expansivity, and decreased expansivity of free‐volume holes. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 1230–1243, 2005
Helix‐coil transition of alanine peptides in water: Force field dependence on the folded and unfolded structures
Authors: Gnanakaran S. , García Angel E.
Published: April 2005

The force fields used in classical modeling studies are semiempirical in nature and rely on their validation by comparison of simulations with experimental data. The all‐atom replica‐exchange molecular dynamics (REMD) methodology allows us to calculate the thermodynamics of folding/unfolding of peptides and small proteins, and provides a way of evaluating the reliability of force fields. We apply the REMD to obtain equilibrium folding/unfolding thermodynamics of a 21‐residue peptide containing only alanine residues in explicit aqueous solution. The thermodynamics of this peptide is modeled with both the OPLS/AA/L and the A94/MOD force fields. We find that the helical content and the values for the helix propagation and nucleation parameters for this alanine peptide are consistent with measurements on similar peptides and with calculations using the modified AMBER force field (A94/MOD). The nature of conformations, both folded and unfolded, that contributes to the helix‐coil transition profile, however, is quite different between these two force fields. Proteins 2005. © 2005 Wiley‐Liss, Inc.
Recommendations for standardized human pedigree nomenclature
Authors: Bennett Robin L. , Steinhaus Kathryn A. , Uhrich Stefanie B. , O'Sullivan Corrine K. , Resta Robert G. , Lochner‐Doyle Debra , Markel Dorene S. , Vincent Victoria , Hamanishi Jan
Published: April 2005

The construction of an accurate family pedigree is a fundamental component of a clinical genetic evaluation and of human genetic research. Previous surveys of genetic counselors and human genetic publications have demonstrated significant inconsistencies in the usage of common pedigree symbols representing situations such as pregnancy, termination of pregnancy, miscarriage, and adoption, as well as less common scenarios such as pregnancies conceived through assisted reproductive technologies. The Pedigree Standardization Task Force (PSTF) was organized through the Professional Issues Committee of the National Society of Genetic Counselors, to establish recommendations for universal standards in human pedigree nomenclature. Nomenclature was chosen based on current usage, consistency among symbols, computer compatibility, and the adaptability of symbols to reflect the rapid technical advances in human genetics. Preliminary recommendations were presented for review at three national meetings of human genetic professionals and sent to >100 human genetic professionals for review. On the basis of this review process, the recommendations of the PSTF for standardized human pedigree nomenclature are presented here. By incorporating these recommendations into medical genetics professional training programs, board examinations, genetic publications, and pedigree software, the adoption of uniform pedigree nomenclature can begin. Usage of standardized pedigree nomenclature will reduce the chances for incorrect interpretation of patient and family medical and genetic information. It may also improve the quality of patient care provided by genetic professionals and facilitate communication between researchers involved with genetic family studies.
Parental guilt: The part played by the clinical geneticist
Authors: Chapple Alison , May Carl , Campion Peter
Published: April 2005

Parents of children born with a disability often suffer feelings of inappropriate guilt and shame. Although some genetic counselors see their main task to be that of diagnosis and education, they also aim to relieve these feelings of guilt and shame. Little is known about the process of genetic counseling, and whether or not counselors achieve this aim. An exploratory study of one clinic, and one geneticist working with 30 families, using video recordings and taped interviews, indicated that this particular doctor sometimes succeeded in reducing guilt, either intentionally or unintentionally, but on one occasion guilt was iatrogenic, and increased rather than decreased. Further research is needed to examine other types and other styles of genetic counseling so that in future iatrogenic guilt can be avoided, and the distressing aspects of inappropriate guilt and shame reduced as much as possible.
Newborn screening for cystic fibrosis: Educational implications
Authors: Rae John , Partington Michael W.
Published: April 2005

We examined the educational implications of newborn screening for cystic fibrosis (CF) as performed by combining the measurement of immunoreactive trypsin with analysis for the most common CF mutation, ΔF508. Four out of 77 (5%) of maternity staff from 11 hospitals in rural New South Wales, Australia had learned about the salient features of the screening protocol from a pamphlet distributed from a central laboratory. In comparison, a didactic lesson resulted in a significantly greater (p<0.00006) number of maternity staff learning about the salient features of the screening protocol. Most maternity staff expanded their explanation to parents of newborn babies because of the didactic lesson.
Resilience in siblings of children with sickle cell disease
Authors: Royal Charmaine D. , Headings Verle E. , Molnar Eva T. , Ampy Franklin R.
Published: April 2005

This pilot study was conducted to identify factors responsible for promoting resilience in siblings of children with sickle cell disease. Twenty siblings (10–17 years of age) of children (5–13 years) with sickle cell disease were selected from the Pediatric Clinic of Howard University Center for Sickle Cell Disease. The siblings responded to questionnaires, and the data obtained was analyzed by chi‐square for association. The results indicated that age, birth order, and gender had no effect on resilience in the siblings. However, family size, number of parents in the home, sibling's knowledge of the illness, degree of morbidity of the illness, socioeconomic status of the family, and parents' attitudes and childrearing practices were all found to affect resilience. These findings provide additional insight into the psychosocial aspects of, and genetic counseling for sickle cell disease, as well as for other chronic genetic disorders.
Pre‐screening education in multiple marker screening programs: The effect on patient anxiety and knowledge
Authors: Ormond Kelly E. , Pergament Eugene , Fine Beth A.
Published: April 2005

Previous studies have shown that unexplained deviations in maternal serum multiple marker screening (MMS) generate considerable anxiety during the remainder of pregnancy. While the role of education in decreasing anxiety is documented, to date there has been no prospective evaluation of which educational practices might minimize this emotional stress. In a pilot study, we prospectively examined the effects on anxiety and knowledge by providing information about MMS (1) by genetic counselor, (2) by pamphlet, and (3) by primary physician. Women randomized to one of these three modalities were administered the Spielberger State‐ Trait Anxiety Inventory [STAI] and knowledge questionnaires at their initial obstetrics visit, at their second visit after educational intervention and 1–2 weeks after MMS results were provided to patients. Education resulted in an increase in knowledge and post‐education knowledge was different between educational modalities. Anxiety declined in patients educated through genetic counseling or a pamphlet.
Embryo genetic disorder analysis demonstration project: A model protocol
Authors: Singer Niecee
Published: April 2005

A demonstration project designed for couples at a minimum 25% risk for having a child with cystic fibrosis is being undertaken using embryo genetic disorder analysis within an organization proficient inin vitro fertilization techniques. Prior to offering the project to patients, issues were identified that needed to be addressed in order to improve the likelihood of success. We then developed a set of protocols that would enable us to introduce this new technology to our staff and to prospective patients in a consistent manner.
Code of ethics: Day‐to‐day applications
Authors: Benkendorf Judith L. , Callanan Nancy P. , Grobstein Rose , Schmerler Susan , FitzGerald Kevin T.
Published: April 2005

The following article was originally presented as a workshop at the 1992 NSGC Annual Education Conference. It was the first in a series of programs designed to fulfill the educational component of the Board of Directors' charge to the Ethics Subcommittee of the interpretation, education and application of the Code of Ethics. Applications of the Code to actual problems experienced by genetic counselors are presented. The Code is shown to be a practical guide in the areas of confidentiality and patient advocacy. Because the Committee has received several communications regarding sexual harassment, the need for addressing this issue seemed particularly timely. The third scenario presents a more general discussion regarding this topic.
The Challenge of Military Surgical Education
Authors: Becker Horst Peter , Gerngross Heinz , Schwab Robert
Published: April 2005

Now that field hospitals and rescue stations have been provided with state‐of‐the‐art equipment, it is important to tailor the medical qualifications of military surgeons to the specific requirements of missions outside Germany. The objective of this article is to provide guidelines for a new training model. Einsatzchirurgie is defined as surgical treatment provided under restricted conditions in an unfamiliar environment. Its purpose is, first and foremost, to provide emergency treatment. The spectrum of Einsatzchirurgie, however, also encompasses maximum medical treatment on a case‐by‐case basis and emergency surgical treatment in a mass casualty situation. Training, for example, may consist of a 6‐year basic training course in surgery followed by specialist training in abdominal surgery, traumatology, and courses in further disciplines — e.g., urology, gynecology, or neurosurgery. In addition to the qualifications required by the Landesärztekammem (professional organizations of German physicians at the federal countries level), military surgeons who are to become senior medical officers should also be qualified to provide immediate non‐surgical emergency care. In these times, the education of military surgeons remains a great challenge. Motivation to work as a surgeon in the armed forces with multiple deployments during the career requires enthusiasm and professionalism. The attractivness of the training institution and the home hospital is key for successful work as a military surgeon.
Links between the Antarctic Oscillation and winter rainfall over western South Africa
Authors: Reason C. J. C. , Rouault M.
Published: April 2005

Relationships between the Antarctic Oscillation (AAO) and winter rainfall over western South Africa are investigated. This region receives most of its annual rainfall during austral winter and often experiences severe drought. It is found that 6 (6) of the 7 (8) wettest (driest) winters (JJA) during 1948–2004 occur during negative (positive) AAO phase, i.e., positive (negative) pressure anomalies over Antarctica and negative (positive) anomalies over the midlatitudes. The mechanisms by which the AAO appears to influence winter rainfall involve shifts in the subtropical jet, and changes in the low‐level moisture flux upstream over the South Atlantic and in the mid‐level uplift, low‐level convergence and relative vorticity over the region. The anomalous circulation patterns extend into spring; thus, the springs following the identified winters also show similar rainfall anomalies.
Statins and Stroke
Authors: Endres Matthias
Published: April 2005

Inhibitors of HMG-CoA reductase (statins) are potent cholesterol-lowering drugs. Large clinical trials have shown that statins reduce the incidence of cerebrovascular events, which might be surprising because cholesterol is not an established risk factor for stroke. In addition to their cholesterol-lowering properties, statins exert a number of pleiotropic, vasculoprotective actions that include improvement of endothelial function, increased nitric oxide (NO) bioavailability, antioxidant properties, inhibition of inflammatory responses, immunomodulatory actions, regulation of progenitor cells, and stabilization of atherosclerotic plaques. In fact, statins augment cerebral blood flow and confer significant protection in animal models of stroke partly via mechanisms related to the upregulation of endothelial nitric oxide synthase. Retrospective clinical evidence suggests that long-term statin administration may not only reduce stroke risk but also improve outcome. Early secondary prevention trials are underway to test the hypothesis that statin treatment initiated immediately after an event improves short-term outcome. Lastly, recent evidence suggests that sudden discontinuation of statin treatment leads to a rebound effect with downregulation of NO production. Withdrawal of statin treatment may impair vascular function and increase morbidity and mortality in patients with vascular disease.
Ion beam nitriding of single and polycrystalline austenitic stainless steel
Authors: Abrasonis G. , Rivière J. P. , Templier C. , Declémy A. , Pranevicius L. , Milhet X.
Published: April 2005

Polycrystalline and single crystalline [orientations (001) and (011)] AISI 316L austenitic stainless steel was implanted at 400 °C with 1.2 keV nitrogen ions using a high current density of 0.5mAcm−2. The nitrogen distribution profiles were determined using nuclear reaction analysis (NRA). The structure of nitrided polycrystalline stainless steel samples was analyzed using glancing incidence and symmetric x-ray diffraction (XRD) while the structure of the nitrided single crystalline stainless steel samples was analyzed using x-ray diffraction mapping of the reciprocal space. For identical treatment conditions, it is observed that the nitrogen penetration depth is larger for the polycrystalline samples than for the single crystalline ones. The nitrogen penetration depth depends on the orientation, the ⟨001⟩ being more preferential for nitrogen diffusion than ⟨011⟩. In both type of samples, XRD analysis shows the presence of the phase usually called “expanded” austenite or γN phase. The lattice expansion depends on the crystallographic plane family, the (001) planes showing an anomalously large expansion. The reciprocal lattice maps of the nitrided single crystalline stainless steel demonstrate that during nitriding lattice rotation takes place simultaneously with lattice expansion. The analysis of the results based on the presence of stacking faults, residual compressive stress induced by the lattice expansion, and nitrogen concentration gradient indicates that the average lattice parameter increases with the nitrided layer depth. A possible explanation of the anomalous expansion of the (001) planes is presented, which is based on the combination of faster nitriding rate in the (001) oriented grains and the role of stacking faults and compressive stress.
Assigning signs to the electronic nonadiabatic coupling terms:  The {H2,O} system as a case study
Authors: Vibók Ágnes , Halász Gábor J. , Suhai Sándor , Baer Michael
Published: April 2005

This paper is devoted to a specific difficulty related to the electronic nonadiabatic coupling terms (NACT), namely, how to determine correctly their signs. It is well known that correct NACTs, including their signs, are crucial for any numerical treatment of the nuclear Schrödinger equation [see, i.e., A. Kuppermaan and R. Abrol, Adv. Chem. Phys. 124, 283 (2003)]. In most cases the derivation of the correct sign of the nonadiabatic coupling matrix (NACM) is done employing various continuity procedures. However, there are cases where these procedures do not suffice and for these cases we suggest to apply an additional procedure based on a mathematical lemma which asserts that the exponentiated line integral which yields the D matrix is invariant with respect to the initial point of the integration [M. Baer, J. Phys. Chem. A 104, 3181 (2000)]. In the numerical study we apply this lemma to determine the signs of the 3×3 NACM elements for the three excited states of the {H2,O} system (some of these NACTs are presented here for the first time). It turns out that the ab initio treatment yields results from which one can form eight different 3×3 NACMs. However the application of this lemma (which does not require any significant additional numerical effort) reduces this number to two. The final selection is done by an enhanced numerical study which requires more accurate calculations.
Magnetotransport properties in La1−xCaxMnO3 (x=0.33, 0.5) thin films deposited on different substrates
Authors: Xiong Y. M. , Wang G. Y. , Luo X. G. , Wang C. H. , Chen X. H. , Chen X. , Chen C. L.
Published: April 2005

Magnetotransport properties of La1−xCaxMnO3 (x=0.33, 0.5) thin films on different substrates are systematically studied. Due to the different lattice-substrate mismatch between films and substrates, compressive, and tensile epitaxial strain can be induced, respectively. The structure distortion induced by the strain with different sign influences the transport property and magnetoresistance. The tensile strain induces an increase of resistivity and magnetoresistance, while the resistivity peak temperature decreases. Compressive strain leads to a contrary behavior. The microstructure of films is also dominated by the lattice-substrate mismatch strongly. The inhomogeneities and different mixed domain structure induce the broadening of magnetic transition in films on SrTiO3 and NdGaO3, and a sharp increase in magnetoresistance in La0.67Ca0.33MnO3 films with increasing field. In addition, the low temperature metal–insulator transition in the resistivity of La0.5Ca0.5MnO3 film on LaAlO3 also indicates the sample inhomogeneities. The suppression of the charge-ordering state in La0.5Ca0.5MnO3 films is mainly dominated by the magnetic field, whereas the effect of the lattice-substrate mismatch is weak. It is due to the origin of the charge-ordering state. When the charge-ordering state is completely suppressed, the effect of lattice-substrate mismatch on charge transport and magnetoresistance shows up obviously.
Generalized density functional theory for degenerate states
Authors: Nagy Á. , Liu S. , Bartolloti L.
Published: April 2005

An extension of density functional theory is proposed for degenerate states. There are suitably selected basic variables beyond the subspace density. Generalized Kohn–Sham equations are derived. A direct method is proposed to ensure the fixed value of ensemble quantities. Then the Kohn–Sham equations are similar to the conventional Kohn–Sham equations. But the Kohn–Sham potential is different for different ensembles. A simple local expression is proposed for the correlation energy.
Interface characterization of nanoscale laminate structures on dense dielectric substrates by x-ray reflectivity
Authors: Travaly Y. , Schuhmacher J. , Hoyas A. M. , Van Hove M. , Maex K. , Abell T. , Sutcliffe V. , Jonas A. M.
Published: April 2005

On nanoscale laminate structures, the interface cannot be identified any longer as the separation between two films of bulk materials. The formation of the interface defines the final composition and structure of the laminate structure. As such, the characterization of the interface becomes an important challenge. In this work the nanoscale laminate structures were formed by atomic layer deposition (ALD) of tungsten nitride carbide and tantalum nitride thin films on dense dielectrics [silicon carbide and silicon oxide (SiO2)]. The laminates were studied using x-ray reflectivity. The starting substrate surface is a primary factor in determining the density of the ALD layer. Moreover, in some cases, electron-density perturbations are observed in the vicinity of the interfacial region. A characterization strategy, using a density contrast layer between the silicon substrate and the SiO2 dielectric is presented. Depending on the chemical nature of precursors and substrate, ALD processes can either form specific interfacial organization or induce dielectric modifications, in any case, leading to unexpected metal-dielectric interactions.
An ab initio study of the vibronic, spin–orbit, and magnetic hyperfine structure in the XΠ2 electronic state of NCO
Authors: Mladenović Milena , Perić Miljenko , Engels Bernd
Published: April 2005

In the present study we give the results of the ab initio calculations on the vibronic, spin–orbit, and magnetic hyperfine structure in the XΠ2 electronic state of the NCO radical. The calculations of the potential surfaces and the electronic mean values of the hyperfine coupling constants are carried out by means of the density functional theory approach (B3LYP functional combined with an atomic orbital basis set suitable for calculations of the hyperfine structure). The vibronic levels, spin–orbit splitting, and the vibronic mean values of the components of the hyperfine tensor in the vibronic species are calculated using a variational method. The results of the calculations are in good agreement with the available experimental data.
Specific external forcing of spatiotemporal dynamics in reaction–diffusion systems
Authors: Lebiedz Dirk , Brandt-Pollmann Ulrich
Published: April 2005

Self-organization behavior and in particular pattern forming spatiotemporal dynamics play an important role in far from equilibrium chemical and biochemical systems. Specific external forcing and control of self-organizing processes might be of great benefit in various applications ranging from technical systems to modern biomedical research. We demonstrate that in a cellular chemotaxis system modeled by one-dimensional reaction–diffusion equations particular forms of spatiotemporal dynamics can be induced and stabilized by controlling spatially distributed influx patterns of a chemical species as a function of time. In our model study we show that a propagating wave with certain shape and velocity and static symmetrical and asymmetrical patterns can be forced and manipulated by numerically computing open-loop optimal influx controls.
Multiple junction biasing of superconducting tunnel junction detectors
Authors: Segall K. , Mazo J. J. , Orlando T. P.
Published: April 2005

We describe a biasing scheme for single-photon detectors based on superconducting tunnel junctions. It replaces a single detector junction with a circuit of three junctions and achieves biasing of a detector junction at subgap currents without the use of an external magnetic field. This potentially increases the capability of these types of detectors and eases constraints in making large arrays. The biasing occurs through the nonlinear interaction of the three junctions, which we demonstrate through numerical simulation. This nonlinear state is numerically stable against external fluctuations and is compatible with high-fidelity electrical readout of the photon-induced current.
Nanoplate elasticity under surface reconstruction
Authors: Shim Hyun Woo , Zhou L. G. , Huang Hanchen , Cale Timothy S.
Published: April 2005

Using classical molecular statics simulations, we show that nanoplate elasticity strongly depends on surface reconstruction and alignment of bond chains. Because of its well-established surface reconstructions and the readily available interatomic potential, diamond-cubic silicon is the prototype of this study. We focus on silicon nanoplates of high-symmetry surfaces, {111} and {100}; with 7×7 and 2×1 reconstructions. Nanoplates with unreconstructed {111} surfaces are elastically stiffer than bulk. In contrast, the same nanoplates with 7×7 reconstructed {111} surfaces are elastically softer than bulk. On {100} surfaces, the 2×1 surface reconstruction has little impact. The bond chains are along one of the two ⟨110⟩ directions, making the two ⟨110⟩ directions nonequivalent. The alignment of the bond chains on the opposite surfaces of a nanoplate dictates its elastic anisotropy. The sensitivity of nanoplate elasticity on details of surface atomic arrangements may impact the application of nanoplates (or nanocantilevers) as sensors.
In situ x-ray diffraction study of the thermal expansion of silver nanoparticles in ambient air and vacuum
Authors: Hu Jinlian , Cai Weiping , Li Cuncheng , Gan Yanjie , Chen Li
Published: April 2005

The thermal expansion behavior of silver nanoparticles in ambient air and vacuum was studied by in situ x-ray diffraction (XRD) measurement of the particles dispersed within mesoporous silica in the temperature range of 25–700 °C. It has been shown that thermal expansion coefficient of Ag nanoparticles in vacuum is about 0.6×10−5∕°C, only near one fourth that of bulk silver (2.2×10−5∕°C). However, the coefficient in air is about 1.7×10−5∕°C, about 3 times as high as that in vacuum and close to the value of bulk Ag. These were explained in terms of Ag particles’ surface energy, oxygen surface adsorption, and dissolution into lattice. This study is of importance in architectonics of future nanodevices.
Measurement of the mean inner potential of ZnO nanorods by transmission electron holography
Authors: Müller E. , Kruse P. , Gerthsen D. , Schowalter M. , Rosenauer A. , Lamoen D. , Kling R. , Waag A.
Published: April 2005

The mean inner potential of ZnO was measured by means of electron holography in a transmission electron microscope. Accurate measurements of the mean inner potential by transmission electron holography are often hampered by imprecise knowledge of the sample thickness. To overcome this problem, ZnO nanorods with a well-defined geometry and diameter were used in our study. Holograms were taken under kinematical diffraction conditions using high-resolution transmission electron microscopy images for magnification calibration. The phase shift of the transmitted beam of the image wave with respect to the reference wave traveling through the vacuum yields the mean inner potential which was determined to be (15.9±1.5)V for ZnO.
Manipulation of carbon nanotubes using AC dielectrophoresis
Authors: Li Jingqi , Zhang Qing , Peng Ning , Zhu Qi
Published: April 2005

Single-wall carbon nanotubes (SWNTs) suspended in isopropyl alcohol are placed between two cross-structured electrodes using an ac dielectrophoresis technique. The SWNTs are found to attach to the electrodes along the direction of the ac external electric field. The SWNTs predominately bridge the shortest gap between the two electrodes and the spatial distribution of the tubes becomes wider for a long manipulation time (say, greater than 300 s). The observed phenomenon is analyzed in terms of the dielectrophoresis-induced torque and force on the SWNTs. Our simulation shows that the time for rotating SWNTs to the direction of the electric field is much smaller than that for translating SWNTs. We also found that metallic SWNTs are forced along the gradient direction of spacial distribution of the electric field strength while semiconducting SWNTs are forced in the opposite direction.
Electrical characterization of Er- and Pr-implanted GaN films
Authors: Song S. F. , Chen W. D. , Zhang Chunguang , Bian Liufang , Hsu C. C. , Lu L. W. , Zhang Y. H. , Zhu Jianjun
Published: April 2005

Hall, current–voltage, and deep-level transient spectroscopy measurements were used to characterize the electrical properties of metalorganic chemical vapor deposition grown undoped, Er- and Pr-implanted GaN films. Only one deep level located at 0.270 eV below the conduction band was found in the as-grown GaN films. However, four defect levels located at 0.300, 0.188, 0.600, and 0.410 eV below the conduction band were found in the Er-implanted GaN films after annealing at 900 °C for 30 min, and four defect levels located at 0.280, 0.190, 0.610, and 0.390 eV below the conduction band were found in the Pr-implanted GaN films after annealing at 1050 °C for 30 min. The origins of the deep defect levels are discussed.
A study of some aspects of the hydrology of some irrigated soils of western New South Wales
Authors: Collis-George N , Smiles DE
Published: April 2005

In an investigation of soil degeneration in an irrigation area adjacent to a channel, piezometric techniques were used to establish that seepage from the channel was the main source of water contributing to an abnormally high water-table, and by graphical integration methods it was possible to establish a rate of seepage which was verified using a numerical solution of the approximate equation �z/�t = KH/f . �2z/�x2 The two-well method of Childs, Collis-George, and Holmes (1957) was used to establish that there was little or no difference in horizontal permeability between various sites but that the areas with no or degenerate vegetation were isotropic, while the normal areas in terms of plant behaviour and soil surface stability were anisotropic with a value for the horizontal component of permeability greater than that of the vertical component. These observations, together with observations of a high water-table and high rate of potential evaporation, are used to propose a consistent theory to explain the incidence of and the increase in size of degenerate areas predisposed to become saline.
Cracks, peds, and their surfaces in some soils of the Riverine Plain, New South Wales
Authors: Sleeman JR
Published: April 2005

The nature and arrangement of cracks (planar voids) and peds in two redbrown earth profiles and two grey and brown soils of heavy texture profiles are described and their possible origin is discussed. The planar voids are classified and six patterns recognized. The vertical sequence of these patterns in each profile appears to be mainly controlled by the wetting and drying history, but in all profiles vertical cracking tends to predominate in the uppermost clay horizons and horizontal cracking becomes more significant with increasing depth. Specific modifications on natural surfaces (cutans) are not associated with particular kinds or patterning of planar voids, but are probably influenced to some extent by the swelling-shrinkage behaviour of the material. Peds have been redefined on the basis of recognizable natural surfaces as distinct from the occurrence of populations of units of similar size and shape; certain of the crack patterns separate peds of variable size and shape.
The uptake of calcium and strontium by plants from some Australian soils
Authors: Williams CH , David DJ
Published: April 2005

Calcium and strontium in eastern Australian soils and their uptake by plants have been examined in pot culture and under field conditions. The ratio of calcium to strontium in the plant material was closely related to the ratio of exchangeable calcium to exchangeable strontium in the soil, although the plants always contained a higher proportion of calcium. This was probably due to the difference in the adsorption of calcium and strontium by the soil colloids, and to small differences in the relative movement of calcium and strontium from the roots to the plant tops. The proportion of calcium to strontium in the plant material was similar to that in a water extract of the soil; this suggests that the two ions are taken up through the soil solution without any marked discrimination between them. While the proportion of calcium to strontium in the plant roots of oats and cocksfoot was generally similar to that in the plant tops, the roots of subterranean clover and Erodium botrys contained an appreciably higher proportion of strontium. However, since less than 20% of the total calcium and strontium uptake by these two species remained in the roots the effect of this on the proportions in the plant tops was small. Decreases in exchangeable calcium and strontium in soils following the growth of subterranean clover plants in pots were sufficient to account for almost 80 % of their total uptake by the plants. The amounts of calcium and strontium taken up by the clover in pots were related to the amounts of the exchangeable ions in the soil but the smaller uptake of calcium by oats was more closely related to the water-soluble calcium. When soluble calcium and strontium were added to soils in pot culture the ratio Ca/Sr (plant tops) in oats was closely related to the ratio Ca/Sr (exchangeable + added). The addition of calcium carbonate to the surface of three soils in pots markedly increased the ratio of calcium to strontium in the plant tops of subterranean clover in each case. Under field conditions the uptake of calcium and strontium by subterranean clover appeared to be related to the exchangeable forms in the surface 4 in. of soil. With wheat, however, other factors seemed to Influence their uptake including the soil calcium and strontium at depths below 4 in. The accumulation of calcium from superphosphate in the exchangeable form under subterranean clover pastures increased the ratio Ca/Sr (exchangeable) in the surface soil.
Calculation of soil water contents from gamma ray readings
Authors: Gurr CG
Published: April 2005

A method is given for calculating water contents of a column of soil from gamma ray data. The method is particularly useful for undisturbed field samples of unknown initial conditions. Values of water content and bulk density determined at the end of an experiment are used for calibration. To aid the calculation of large numbers of results, a nomogram has been constructed.
The solubility of potassium from soil illites. II. Mechanisms of potassium release
Authors: Tucker BM
Published: April 2005

The release of potassium from four soil clays containing illites of different degrees of degradation was found to be independent of the solution of silicic acid or aluminium from the clay minerals. The lattice potassium is released into solution by a displacement reaction. The displacement of potassium by calcium ions is dependent on the prior release of one lattice potassium by one hydrogen ion, presumably because the entry of the hydrogen ion makes the potassium at neighbouring sites in the lattice accessible to other cations. The reaction may be written as 7Ks+ + H+ + 3Ca2+ 7K+ + 3CaS2+, where the subscript S refers to the solid (clay) phase. At pH values above pH 11, potassium is released by breakdown of the mineral structure by the action of hydroxyl ions.
The graphical representation of planar pore patterns in soils
Authors: Lafeber D
Published: April 2005

Many soils, not necessarily only those with a high clay content, develop at low moisture contents a system of pores, in which one of the principal geometrical axes is much shorter than the other two (planar pores). The spatial orientation of such planar pore patterns is considered here to reflect significant aspects of the functional or physical fabric of the particular soils. Quantitative graphical methods are described to express the orientation characteristics of single cross sections and of series of parallel cross sections through such planar pore patterns. The procedures are demonstrated on a number of Australian soils with different clay contents. It is shown that very distinct indications of preferred orientation of planar pores, and sometimes elongated skeleton grains, occur in all these instances. It is considered that the significance of the quantitative description and analysis of soil planar pore patterns extends far beyond the significance of these patterns themselves, as they can be expected to be an expression of the depositional and/or stress-strain history of the particular soils. As such they should be of paramount importance in the study of the mutual relations between soil fabric and soil mechanical behaviour.
Quantitative study of a layered soil
Authors: Oertel AC , Giles JB
Published: April 2005

Results of particle-size and chemical analyses of a sample of the Hanwood sandy loam, a red-brown earth, indicate that the parent sediments consisted of at least four, probably five, depositional layers. These layers correspond only in part to those detected by other methods. Some important properties of the soil show no evidence for a layer that is clearly indicated by abrupt changes in the magnitude or the trend of other properties.
Comparison of some properties of soil humic acids and synthetic phenolic polymers incorporating amino derivaties
Authors: Ladd JN , Butler JHA
Published: April 2005

Twenty-three model phenolic polymers, either nitrogen-free or incorporating amino acids, peptides, or proteins, have been prepared from p-benzoquinone and catechol under mild oxidative conditions. Two lines of experimentation have demonstrated properties of soil humic acids closely similar to those of polymers incorporating proteins, but different from those of polymers incorporating amino acids: (1) fractionation of humic acids and synthetic polymers by 'Sephadex' gel filtration showed that the percentage of components of molecular weights nominally greater than 100 000 ranged from 52-76 % for eight humic acids tested, 53-59 % for benzoquinone-protein polymers (excluding polymers containing protamine), but less than 20% for all other polymers; (2) acid hydrolysis with 6M HCl resulted in a partial release of polymer nitrogen. Amino acid nitrogen in the hydrolysates accounted for 32.4-51.9 % of humic acid nitrogen, 31.2-56.3 % of the nitrogen of polymers incorporating protein, but less than 10.8% of the nitrogen of polymers incorporating individual amino acids. Experiments with model monomeric N-phenylglycine derivatives and with polymers incorporating simple peptides showed that the bond between the carbon atom of an aromatic ring and the nitrogen atom of an a-amino acid is far more stable to acid hydrolysis than peptide bonds or bonds linking amino acids in humic acids. Glycine is, however, readily released from N-phenylglycine derivatives when conditions favour their oxidation to a quinone-imine intermediate. Incorporation of proteins into phenolic polymers prevented the detection of peptide bonds by the Folin reagent.