bluuebunny/crossref_metadata_2025 huggingface dataset:
Characterisation of the interface between nucleophosmin (NPM) and p53: Potential role in p53 stabilisation
Authors: Lambert B. , Buckle M.
Published: December 2005

We have used surface plasmon resonance to quantify the kinetics and stoichiometry of the interaction between p53 and nucleophosmin (NPM). Domains characterising the interface between the two proteins were identified by chemical cross‐linking, proteolytic digestion and mass spectrometry based peptide mapping.We show that the C‐terminal domain of NPM (residues 242–269) interacts with two regions of p53 (residues 175–196 and residues 343–363) which belong, respectively, to the DNA binding domain and the tetramerisation domain. Potential biological consequences of such interactions are discussed.
A novel strategy to identify the regulatory DNA‐organized cooperations among transcription factors
Authors: Niu Gang , Huang Ling , Wang Qiong , Jiang Lichun , Huang Min , Shen Ping , Fei Jian
Published: December 2005

To identify the functional contributions of cooperations among transcription factors on regulatory DNA is critical for understanding transcription activation. But so far there is a great lack of effective identifying methods. Here we describe a novel strategy, based on comprehensively perturbed experiments and a computational model, to identify the cooperations among NF‐κB (p65), CREB, and AP‐1 in transcription activation of human cytomegalovirus major IE1 promoter/enhancer (MIEP). In this strategy, functional profiles of protein–MIEP association and RNA synthesis are achieved through comprehensively perturbing the association of p65, CREB or AP‐1 with MIEP and then subjected to the computational model. Consequently, the ‘real’ cooperations contributing to MIEP activation are found to comprise five but not seven types of potential cooperations. Thus, our research provides a facile systematic approach to identifying the DNA‐organized cooperations among transcription factors and understanding transcription activation.
Gene conversion from SLG to SRK resulting in self‐compatibility in Brassica rapa
Authors: Fujimoto Ryo , Sugimura Tetsu , Nishio Takeshi
Published: December 2005

Self‐compatible S‐54 homozygotic plants were found in progenies of an F1 hybrid cultivar in Chinese cabbage. Pollination tests revealed that this self‐compatibility is controlled by the S locus and caused by the loss of the recognition function of the stigma. SRK, the gene for the recognition molecule in the stigma, was normally transcribed and translated in the self‐compatible plants. The 1034‐bp region in the receptor domain of SRK in the self‐compatible plants was 100% identical to SLG in S‐54, while that in self‐incompatible S‐54 homozygotic plants was 95.1% identical. These results suggest that the self‐compatibility of the S‐54 homozygotes is due to amino‐acid changes caused by gene conversion from SLG to SRK.
ABCA7, a molecule with unknown function
Authors: Abe-Dohmae Sumiko , Ueda Kazumitsu , Yokoyama Shinji
Published: December 2005

Many ABC proteins are functional in cellular lipid transport in various different manners. ABCA7 is a full‐size ABC transporter, the physiological function of which is unknown to date. This is a protein that shows the highest homology known to ABCA1, an essential molecule for producing of plasma high‐density lipoprotein (HDL), and in fact it mimics ABCA1 to mediate the production of HDL from cellular lipid when transfected in vitro. It is therefore rational to assume that ABCA7 plays a relevant role in regulating of lipid metabolism. However, the ABCA7 expression profile is distinct from that of ABCA1, with respect to tissue‐specific distribution and response to some reagents, presumably because of different transcriptional and posttranscriptional regulation. Potential roles and functions of ABCA7 in lipid homeostasis are discussed, especially in relation to HDL metabolism, based on available publications.
The X protein of hepatitis B virus binds to the F box protein Skp2 and inhibits the ubiquitination and proteasomal degradation of c‐Myc
Authors: Kalra Neetu , Kumar Vijay
Published: December 2005

The HBx protein of hepatitis B virus is involved in deregulation of cell cycle and development of hepatocellular carcinoma. Since c‐Myc also plays an important role in cell proliferation and tumor development, we studied its regulation by HBx in a human hepatoma cell line. Co‐expression of HBx and c‐Myc resulted in increased stability of intracellular c‐Myc. HBx blocked the ubiquitination of Myc through a direct interaction with the F box region of Skp2 and destabilization of the SCFSkp2 complex. We suggest that sustained presence of c‐Myc combined with mitogenic activity inherent to HBx may be associated with cell cycle deregulation and transformation.
Phytochromes from Agrobacterium tumefaciens: Difference spectroscopy with extracts of wild type and knockout mutants
Authors: Oberpichler Inga , Molina Isabel , Neubauer Olivia , Lamparter Tilman
Published: December 2005

Phytochromes are photoreceptors that occur in plants, fungi and bacteria, among others in the phytopathogen Agrobacterium tumefaciens. We constructed single and double knockout mutants of the two A. tumefaciens phytochromes Agp1 and Agp2. In liquid culture, the double mutant revealed a reduced growth rate, whereas the growth rates of the single mutants did not differ significantly from that of the wild type. Using these mutants, we analyzed the spectral properties of native A. tumefaciens phytochromes. A wild‐type A. tumefaciens cell contains about 10 molecules of Agp1 and about 19 molecules of Agp2. Dark conversion of native Agp1 and Agp2 proceeds from Pfr to Pr and from Pr to Pfr, respectively, as has already been reported for the recombinant proteins. The spectral properties of recombinant and native Agp2 were significantly different. Mixing experiments with extracts from the double mutant and recombinant Agp2 imply that the spectral properties of Agp2 are modulated by components of the extract.
Elasticity and adhesion of resting and lipopolysaccharide‐stimulated macrophages
Authors: Leporatti Stefano , Gerth Anja , Köhler Guido , Kohlstrunk Bernd , Hauschildt Sunna , Donath Edwin
Published: December 2005

Colloidal Force Microscopy was employed to study the viscoelastic and adhesive properties of macrophages upon stimulation with lipopolysaccharide (LPS). Force vs. distance measurements were performed. The adhesion of LPS‐stimulated cells (separation force = 37 ± 3 nN) was almost twice as high as that of resting macrophages (16 ± 1 nN). Upon retraction pulling of membrane tethers was observed. Tether lengths and forces at which rupture take place did not depend on stimulation. The reduced Young's modulus K, a measure of cytoskeleton elasticity, was three times lower than that of the control. The data show that LPS has profound effects on cytomechanical and adhesion properties of macrophages.
Mammalian mitochondrial nitric oxide synthase: Characterization of a novel candidate
Authors: Zemojtel Tomasz , Kolanczyk Mateusz , Kossler Nadine , Stricker Sigmar , Lurz Rudi , Mikula Ivan , Duchniewicz Marlena , Schuelke Markus , Ghafourifar Pedram , Martasek Pavel , Vingron Martin , Mundlos Stefan
Published: December 2005

Recently a novel family of putative nitric oxide synthases, with AtNOS1, the plant member implicated in NO production, has been described. Here we present experimental evidence that a mammalian ortholog of AtNOS1 protein functions in the cellular context of mitochondria. The expression data suggest that a candidate for mammalian mitochondrial nitric oxide synthase contributes to multiple physiological processes during embryogenesis, which may include roles in liver haematopoesis and bone development.
Dynamic force spectroscopy of the digoxigenin–antibody complex
Authors: Neuert G. , Albrecht C. , Pamir E. , Gaub H.E.
Published: December 2005

Small ligands and their receptors are widely used non‐covalent couplers in various biotech applications. One prominent example, the digoxigenin–antibody complex, was often used to immobilize samples for single molecule force measurements by optical trap or AFM. Here, we employed dynamic AFM spectroscopy to demonstrate that a single digoxigenin–antibody bond is likely to fail even under moderate loading rates. This effect potentially could lower the yield of measurements or even obscure the unbinding data of the sample by the rupture events of the coupler. Immobilization by multiple antibody–antigen bonds, therefore, is highly recommended. The analysis of our data revealed a pronounced loading rate dependence of the rupture force, which we analyzed based on the well‐established Bell–Evans‐model with two subsequent unbinding barriers. We could show that the first barrier has a width of Δx
1
= 1.15 nm and a spontaneous rate of k
off1
= 0.015 s−1 and the second has a width of Δx
2
= 0.35 nm and a spontaneous rate of k
off2
= 4.56 s−1. In the crossover region between the two regimes, we found a marked discrepancy between the predicted bond rupture probability density and the measured rupture force histograms, which we discuss as non‐Markovian contribution to the unbinding process.
A physical model for the condensation and decondensation of eukaryotic chromosomes
Authors: Mozziconacci Julien , Lavelle Christophe , Barbi Maria , Lesne Annick , Victor Jean-Marc
Published: December 2005

During the eukaryotic cell cycle, chromatin undergoes several conformational changes, which are believed to play key roles in gene expression regulation during interphase, and in genome replication and division during mitosis. In this paper, we propose a scenario for chromatin structural reorganization during mitosis, which bridges all the different scales involved in chromatin architecture, from nucleosomes to chromatin loops. We build a model for chromatin, based on available data, taking into account both physical and topological constraints DNA has to deal with. Our results suggest that the mitotic chromosome condensation/decondensation process is induced by a structural change at the level of the nucleosome itself.
Diet and size-selective feeding by escaped hatchery rainbow trout Oncorhynchus mykiss (Walbaum)
Authors: Rikardsen A.H. , Sandring S.
Published: December 2005

Escaped hatchery rainbow trout, Oncorhynchus mykiss (Walbaum), at post-smolt (120–340 g) and adult stages (800–3400 g) adapted differently to natural marine prey after escaping from two fish farms in northern Norway. About 1 month after escape (July), more than 57% of the post-smolt fed actively on fish larvae, which contributed 63–75% of the diet by weight. Surface insects were consumed by more than half the post-smolts and represented 24–48% of the diet during the 3-month period of sampling (June–August). One month after escaping, forage ratios (weight stomach/weight fish × 100) exceeded 1, similar to ratios recorded for other wild anadromous salmonid species in the area. Post-smolt weight increased during the sampling period and the condition factor was stable. In contrast, the condition factor of escaped adult fish reduced significantly and the forage ratios were consistently low (0.05–0.77) during the 15 months of sampling (March–August) following their escapement. These fish fed primarily on a variety of different indigestible items (especially particles of seaweed and small pieces of wood) that contributed about 70% of the stomach content weight. They took fish larvae only in July. Although generally contributing little to their overall diet, marine prey of great variety was consumed by the adult fish. The results indicate that young domestic rainbow trout more easily adjust to natural feeding after escape than the older, larger fish, which often fed on indigestible items similar in shape to the commercial pellets to which they were accustomed.
Otolith chemistry: an aid to stock separation of Helicolenus dactylopterus (bluemouth) and Merluccius merluccius (European hake) in the Northeast Atlantic and Mediterranean
Authors: Swan S.C. , Geffen A.J. , Morales-Nin B. , Gordon J.D.M. , Shimmield T. , Sawyer T. , Massutí E.
Published: December 2005

Helicolenus dactylopterus and Merluccius merluccius are widely distributed on the continental slopes of the Atlantic and Mediterranean and have quite different life histories. Both are commercially exploited, but little is known about their stock structure. Fish otolith composition is thought to reflect both endogenous processes and external factors, some of which relate to the surrounding environment, and therefore may be used as a tool for stock discrimination. The elemental composition of sagittal otoliths was examined using both solution-based inductively coupled plasma mass spectrometry of the whole otolith and laser-ablation analysis of the otolith nucleus. The relative concentrations of strontium, barium, and copper in dissolved whole otoliths contributed to the discrimination between H. dactylopterus samples from different geographic areas. Surface analysis of the otolith nucleus did not allow separation of geographic groups. For M. merluccius, separate analyses of the whole otolith data for the Atlantic and Mediterranean samples gave a clear distinction of the different groups within each ocean basin. Analysis of the M. merluccius nucleus composition indicated some differences in elemental concentration among both Atlantic and Mediterranean samples. Magnesium and lead were important elements in separating the groups in the Atlantic, and barium, strontium, and lead were important in the Mediterranean.
Adverse effects of EMLA (lidocaine/prilocaine) cream and efficacy for the placement of jugular catheters in hospitalized cats
Authors: Wagner Karin A. , Gibbon Kristi J. , Strom Tami L. , Kurian Joseph R. , Trepanier Lauren A.
Published: December 2005

EMLA is a lidocaine/prilocaine cream used for topical analgesia in human pediatric patients. The purpose of this study was to establish the safety of EMLA in clinically ill cats, to measure systemic absorption and to determine whether EMLA reduced the need for sedation for the placement of jugular catheters. Thirty-one cats were randomized to either a placebo or EMLA cream group. Cream was applied to a 10 cm2 area over the jugular vein, with 1 h of occlusive dressing. Neither anesthetic was systemically absorbed in any cat, and no adverse clinical signs were observed. Struggling during catheter placement was less in the EMLA-treated cats compared to placebo, but did not reach significance ( P=0.06). Jugular catheters were successfully placed in 60% of EMLA-treated cats and 38% of placebo cats; this difference was not statistically significant and may not justify the added steps of EMLA cream administration for this purpose. However, EMLA does appear to be safe in clinically ill cats, and may be useful for other applications such as for skin mass removal or repeated venepuncture.
Using urea dilution to standardise cellular and non-cellular components of pleural and bronchoalveolar lavage (BAL) fluids in the cat
Authors: Mills Paul C. , Litster Annette
Published: December 2005

A technique to standardise the analysis of cellular and non-cellular components in epithelial lining fluid (ELF) collected during saline lavage of pulmonary and pleural cavities was developed using the urea dilution method. Bronchoalveolar lavage (BAL) and pleural lavage (PL) fluids were collected from 12 clinically healthy cats. Total and differential cell counts in BAL fluid were within normal ranges for the cat, while cell counts in PL fluid were assumed to be normal based on clinical health during examination, auscultation and lactate dehydrogenase (LDH) activities being comparable with other species. The major clinical implication of this study was that nucleated cell counts within feline ELF could not be predicted from analysis of lavage fluid which suggests that calculation of the proportion of ELF in lavage fluid by the urea dilution method may be necessary to avoid misdiagnosis of health or disease in pulmonary or pleural cavities.
Service Guarantee Strength: The key to service quality
Authors: Hays Julie M. , Hill Arthur V.
Published: December 2005

While most authors describe a service guarantee as a “zero‐one variable” indicating the presence or absence of an explicit written service guarantee, this paper develops a construct called “Service Guarantee Strength” (SGS) that is a continuous variable. This construct measures the degree to which a firm sets clear service quality standards for itself on dimensions that customers care about, and has an formal policy for quickly giving meaningful compensation to customers when these standards are not met.

The paper builds upon established micro‐level behavioral theory to develop the “Service Guarantee Strength Framework”. This framework posits that high Service Guarantee Strength leads to improved service quality, customer satisfaction, and loyalty through three intervening variables—marketing communications impact, employee motivation and vision, and learning through service failure.

An empirical investigation was conducted to test the SGS Framework using both employee and customer data from three pairs of firms, with each pair in a different industry. None of these firms had an explicit service guarantee. Unlike many behavioral research studies, this study measured both employee and customer perceptual data and compared the two. The research finds that Service Guarantee Strength is positively related to customer perceptions of service quality, customer satisfaction, and loyalty.
Six Sigma: The role of goals in improvement teams
Authors: Linderman Kevin , Schroeder Roger G. , Choo Adrian S.
Published: December 2005

The tenets of goal theory have been well established as a motivation mechanism in the management literature. However, some quality‐management advocates, such as W. Edwards Deming, often criticize the use of goals. This research investigates the tension between goals and quality management in the Six Sigma context. We find empirical support that goals can be effective in Six Sigma improvement teams when teams adhere to the Six Sigma tools and method. However, challenging goals are counterproductive when Six Sigma teams do not use the tools and methods rigorously. This research reconciles the differences between quality management and goal theory by showing that the Six Sigma tools and method interact with goals.
A behavioral study of supply manager decision‐making: Factors influencing make versus buy evaluation
Authors: Mantel Susan Powell , Tatikonda Mohan V. , Liao Ying
Published: December 2005

This paper investigates behavioral factors influencing a supply manager's decision to insource or outsource the manufacture of a product component. To do so we posit a theoretical framework that integrates the heretofore distinct operational make–buy literature and the behavioral decision‐making literature. Within the framework three factors influencing the make–buy decision are brought into account: the decision‐maker's perception of supply risk or “strategic vulnerability”, the degree of core competency represented by the product component under consideration and the formality of the information about supply alternatives. The results of a controlled experimental survey show that: strategic vulnerability and core competency do influence the make–buy decision, strategic vulnerability has greater influence than core competency and information formality moderates the make–buy decision when the strategic vulnerability and core competency conditions are mixed. The practical implications of these results include the notion that management can ensure a more rational make–buy decision if they understand the biases that influence the decision and point these biases out to the decision maker.
Interplay between uncertainty and flexibility across the value‐chain: Towards a transformation model of manufacturing flexibility
Authors: Sawhney Rajeev
Published: December 2005

Traditionally, flexibility, in its reactive application, has been viewed as a coping mechanism against uncertainty in an organization's internal or external environment. It has also been shown that flexibility can be utilized proactively to create a competitive advantage for a company. Despite the recognition that it serves a dual purpose, little work has been done to synthesize these competing uses of flexibility. This study proposes a model that not only articulates an effective use of flexibility concurrently for both proactive and reactive purposes, it also allows a simultaneous view of the opportunities and uncertainties along the value‐chain. By embracing the entire value‐chain, this model considers the implications of the inter‐relating feedback loops within the supply‐chain, which to‐date has been overlooked in the flexibility literature. Such an approach provides managers with a tool that allows them to consider more options in configuring flexibility between its two competing uses. Within the model, eleven dimensions of flexibility are identified and then classified into three levels comprising a transformation process. This model is grounded in observations from a field study of 10 printed circuit board (PCB) fabrication companies.
Mechanics and erosion of basement‐cored uplift provinces
Authors: Hilley G. E. , Blisniuk P. M. , Strecker M. R.
Published: December 2005

Basement‐cored uplift provinces are often characterized by high‐angle reverse faulting along preexisting crustal heterogeneities, which may greatly affect the mechanics of deformation and the coupling between erosion and orogenic structure. Herein we construct a coupled deformation‐erosion model to understand the mechanics and erosion of mountain belts in which the spatial distribution of deformation is largely influenced by the presence of preexisting high‐angle faults. In this case, deformation is accommodated along, and topography is built above, these structures. This topographic loading leads to increasing lithostatic stresses beneath these regions. As a result, active deformation may migrate to frictionally stronger structures in adjacent regions where lithostatic loading is lower. The migration of deformation to such nearby structures depends on the Hubbert‐Rubey pore fluid pressure ratio of the crust (λ), the orientations of the frictionally weaker and stronger preexisting faults (β1 and β2, respectively), the friction coefficients (μb1 and μb2) and Hubbert‐Rubey fluid‐pressure ratios (λb1 and λb2) of these faults, and the surface slope of the topography above the frictionally weaker structure (α), assuming zero surface slope above the frictionally stronger structure. In general, we found that for a given α and β1, as μb1 increases λ = λb1 = λb2 increases, and β2 decreases, the value of μb2 required to force deformation to migrate increases. However, as erosional processes lead to decreasing surface slopes, deformation will be inhibited from migrating to frictionally stronger structures in adjacent regions. Our model results may help to explain some aspects of the deformation observed and the possible correlation between precipitation and the migration of deformation within these tectonic provinces.
Inverse modeling of NOx emissions at regional scale over northern France: Preliminary investigation of the second‐order sensitivity
Authors: Quélo Denis , Mallet Vivien , Sportisse Bruno
Published: December 2005

The purpose of this article is to perform the inverse modeling of emissions at regional scale for photochemical applications. The case study is the region of Lille in northern France for simulations in May 1998. The chemistry‐transport model, Polair3D, has been validated with 1 year of model‐to‐observation comparisons over Lille. Polair3D has an adjoint mode, which enables inverse modeling with a variational approach. A sensitivity analysis has been performed so as to select the emission parameters to be modified in order to improve ozone forecasts. It has been shown that inverse modeling of the time distribution of nitrogen oxide emissions leads to satisfactory improvements even after the learning period. A key issue is the robustness of the inverted emissions with respect to uncertain parameters. A brute force second‐order sensitivity analysis of the optimized emissions has been performed with respect to other parameters and has proven that the optimized time distribution of NOx emissions is robust.
Comparisons between POLDER 2 and MODIS/Terra aerosol retrievals over ocean
Authors: Gérard B. , Deuzé J.‐L. , Herman M. , Kaufman Y. J. , Lallart P. , Oudard C. , Remer L. A. , Roger B. , Six B. , Tanré D.
Published: December 2005

This paper presents a comparison between simultaneous radiance measurements and aerosol retrievals of POLDER 2/ADEOS 2 and MODIS/Terra, two instruments devoted to monitor the Earth and its atmosphere from space. This study focuses on aerosol remote sensing over ocean. Geophysical results from both inversions are compared. MODIS and POLDER total radiance (and also polarized radiance for POLDER) measurements are compared with radiance simulations based on POLDER and MODIS inversed aerosol products (cross‐simulations). Such comparisons emphasize advantages of each instrument and its inversion process. Both instruments generally agree on aerosol retrievals except when POLDER detects nonspherical particles within the coarse mode, which is not possible for MODIS. Combining measurements provided by POLDER 2 and MODIS, the spectral variation of optical properties of nonspherical aerosols can be derived. In order to retrieve more accurately aerosol optical properties, combining directional and polarized information from POLDER 2 with simultaneous MODIS spectral data is needed. The results of this study will guide us in the realization of a coupled inversion scheme.
Inferring CO2 sources and sinks from satellite observations: Method and application to TOVS data
Authors: Chevallier F. , Fisher M. , Peylin P. , Serrar S. , Bousquet P. , Bréon F.‐M. , Chédin A. , Ciais P.
Published: December 2005

Properly handling satellite data to constrain the inversion of CO2 sources and sinks at the Earth surface is a challenge motivated by the limitations of the current surface observation network. In this paper we present a Bayesian inference scheme to tackle this issue. It is based on the same theoretical principles as most inversions of the flask network but uses a variational formulation rather than a pure matrix‐based one in order to cope with the large amount of satellite data. The minimization algorithm iteratively computes the optimum solution to the inference problem as well as an estimation of its error characteristics and some quantitative measures of the observation information content. A global climate model, guided by analyzed winds, provides information about the atmospheric transport to the inversion scheme. A surface flux climatology regularizes the inference problem. This new system has been applied to 1 year's worth of retrievals of vertically integrated CO2 concentrations from the Television Infrared Observation Satellite Operational Vertical Sounder (TOVS). Consistent with a recent study that identified regional biases in the TOVS retrievals, the inferred fluxes are not useful for biogeochemical analyses. In addition to the detrimental impact of these biases, we find a sensitivity of the results to the formulation of the prior uncertainty and to the accuracy of the transport model. Notwithstanding these difficulties, four‐dimensional inversion schemes of the type presented here could form the basis of multisensor data assimilation systems for the estimation of the surface fluxes of key atmospheric compounds.
Comparing landscape calculations with calorimetric data on ortho-terphenyl, and the question of the configurational fraction of the excess entropy
Authors: Goldstein Martin
Published: December 2005

Mossa et al. [Phys. Rev. E 65, 041205 (2002)] have calculated the total and configurational entropies of supercooled ortho-terphenyl liquid using the potential-energy landscape formalism and a simplified model of the intermolecular potential. I show here that the agreement of their calculated configurational entropy with the experimental data depends on what is assumed about the configurational fraction of the excess entropy and its temperature dependence. In particular, if the configurational fraction is taken as 0.70 and independent of temperature the agreement is excellent; if a marked temperature dependence of that fraction inferred from calorimetric data is assumed the agreement is only fair at best. This marked temperature dependence of the configurational fraction also implies some implausible behavior of contributions to the excess entropy at the Kauzmann temperature, but no obvious reason for disregarding it presents itself.
Phase behavior and local dynamics of concentrated triblock copolymer micelles
Authors: Yardimci H. , Chung B. , Harden J. L. , Leheny R. L.
Published: December 2005

We report a neutron-scattering study to characterize the ordering and local dynamics of spherical micelles formed by the triblock copolymer polyethylene oxide (PEO) - polypropylene oxide (PPO) - polyethylene oxide (Pluronic) in aqueous solution. The study focuses on two Pluronic species, F68 and F108, that have the same weight fraction of PEO but that differ in chain length by approximately a factor of 2. At sufficiently high concentration, both species undergo a sequence of phase changes with increasing temperature from dissolved chains to micelles with liquidlike order to a cubic crystal phase and finally back to a micelle liquid phase. A comparison of the phase diagrams constructed from small-angle neutron scattering indicates that crystallization is suppressed for shorter chain micelles due to fluctuation effects. The intermediate scattering function I(Q,t)∕I(Q,0) determined by neutron spin echo displays a line shape with two distinct relaxations. Comparisons between I(Q,t)∕I(Q,0) for fully hydrogenated F68 chains in D2O and for F68 with deuterated PEO blocks reveal that the slower relaxation corresponds to Rouse modes of the PPO segments in the concentrated micelle cores. The faster relaxation is identified with longitudinal diffusive modes in the PEO corona characteristic of a polymer brush.
Relativistic two-component calculations of electronic g-tensors that include spin polarization
Authors: Malkin Irina , Malkina Olga L. , Malkin Vladimir G. , Kaupp Martin
Published: December 2005

The first two-component relativistic density-functional approach for the calculation of electronic g-tensors is reported that includes spin polarization using noncollinear spin-density functionals. The method is based on the relativistic Douglas-Kroll-Hess Hamiltonian and has been implemented into the ReSpect program package. Using three self-consistent-field calculations with orthogonal orientations of total magnetization J, the full g-matrix may be obtained. In contrast to previous spin-restricted two-component treatments, results with the new approach agree excellently with spin-polarized one-component calculations for light-atom radicals. Additionally, unlike one-component approaches, the method also reproduces successfully the negative Δg‖-values of heavy-atom Σ2 radicals and the negative Δg⊥ components in cysteinyl. The new method removes effectively the dilemma existing up to now regarding the simultaneous inclusion of spin polarization and higher-order spin-orbit effects in g-tensor calculations. It is straightforwardly applicable to higher than doublet spin multiplicities and has been implemented with hybrid functionals.
Experimental and theoretical study of the adsorption of fumaramide [2]rotaxane on Au(111) and Ag(111) surfaces
Authors: Mendoza Sandra M. , Whelan Caroline M. , Jalkanen Jukka-Pekka , Zerbetto Francesco , Gatti Francesco G. , Kay Euan R. , Leigh David A. , Lubomska Monika , Rudolf Petra
Published: December 2005

Thin films of fumaramide [2]rotaxane, a mechanically interlocked molecule composed of a macrocycle and a thread in a “bead and thread” configuration, were prepared by vapor deposition on both Ag(111) and Au(111) substrates. X-ray photoelectron spectroscopy (XPS) and high-resolution electron-energy-loss spectroscopy were used to characterize monolayer and bulklike multilayer films. XPS determination of the relative amounts of carbon, nitrogen, and oxygen indicates that the molecule adsorbs intact. On both metal surfaces, molecules in the first adsorbed layer show an additional component in the C 1s XPS line attributed to chemisorption via amide groups. Molecular-dynamics simulation indicates that the molecule orients two of its eight phenyl rings, one from the macrocycle and one from the thread, in a parallel bonding geometry with respect to the metal surfaces, leaving three amide groups very close to the substrate. In the case of fumaramide [2]rotaxane adsorption on Au(111), the presence of certain out-of-plane phenyl ring and Au–O vibrational modes points to such bonding and a preferential molecular orientation. The theoretical and experimental results imply that the three-dimensional intermolecular configuration permits chemisorption at low coverage to be driven by interactions between the three amide functions of fumaramide [2]rotaxane and the Ag(111) or Au(111) surface.
In
As
Sb
∕
In
P
quantum dots for midwave infrared emitters: A theoretical study
Authors: Cornet C. , Doré F. , Ballestar A. , Even J. , Bertru N. , Le Corre A. , Loualiche S.
Published: December 2005

A theoretical study of the electronic properties of InAsSb quantum dots (QDs) deposited on InP substrate is presented. Unstrained bulk materials present a direct gap between 0.1and 0.35eV suitable for mid-infrared emitters (2–5μm). However, strain and quantum-confinement effects may limit the extension of the emission spectrum of these nanostructures towards the higher wavelengths. Various associations of materials in the barrier are considered. Among the possible associations, InAs0.5Sb0.5∕GaAs0.5Sb0.5 QDs may provide a low-energy emission with a material system similar to the well-known InAs∕GaAs system. Other materials associations such as InAsSb∕InGaAsP∕InP are also studied. Band lineups, optical transitions, optical losses, and effective masses are computed and discussed.
What does pressure decide to cook with orientationally disordered plastic phase of cubane: An orientational glass or crystal?
Authors: Arul Murugan N.
Published: December 2005

The effect of pressure on the structure and reorientational motion of molecules in orientationally disordered (OD) crystalline phase of cubane has been investigated in detail using variable shape molecular simulations in constant-pressure constant-temperature ensemble. Complete orientational ordering occurs at a pressure of 1.0 GPa and the OD phase transforms to an orientationally ordered phase at this pressure. The transition is associated with a kink in the variation of structural parameters such as cell parameters, unit-cell volume, and interaction energy. This transition is also associated with an anomaly in specific heat. Above this transition pressure, the structural quantities display only smaller changes with further increase in pressure. The structure of high-pressure orientationally ordered (HPOO) phase has been characterized using radial distribution functions and orientational distribution function. From detailed analysis of the structure of HPOO phase we conclude that it is isostructural with low-temperature orientationally ordered phase. The OD phase has four times larger compressibility than the HPOO phase.
Molecular-dynamics study of liquid nickel above and below the melting point
Authors: Jakse Noël , Pasturel Alain
Published: December 2005

We have investigated the structural and dynamic properties of liquid nickel by means of large-scale molecular-dynamics simulations, using an effective-pair potential derived from the second-order pseudopotential perturbation theory. The model of interactions is assessed on the single-atom as well as collective dynamic properties. The short-range order in the stable and undercooled liquids is also examined. We show that the present model potential gives a description of the local structure in both states in close agreement with first-principles molecular-dynamics simulations.
Initial stage of InAs growth on Si (001) studied by high-resolution transmission electron microscopy
Authors: Zhao Z. M. , Hulko O. , Yoon T. S. , Xie Y. H.
Published: December 2005

The initial stage of InAs growth on Si (001) substrate was studied via high-resolution transmission electron microscopy analysis. InAs of thickness less than 1 monolayer grown by molecular beam epitaxy was found to form islands at the onset of the growth, i.e., it follows the Volmer–Weber growth mode. By the introduction of 60° and 90° dislocations, the misfit strain was relieved at the early growth stage for island size as small as 10nm. The average distance between the 60° dislocations is approximately 2nm, indicating nearly complete strain relaxation. The shape evolution of individual islands reveals the transition from pyramidal shape with (111) facets for island diameters smaller than 15nm to dome shape for island diameters larger than 20nm.
Experimental investigations and three-dimensional transmission line matrix simulation of Ca5−xAxB2TiO12 (A=Mg, Zn, Ni, and Co; B=Nb and Ta) ceramic resonators
Authors: Bijumon Pazhoor Varghese , Sebastian Mailadil Thomas , Mohanan Pezholil
Published: December 2005

Temperature-stable, low-loss Ca5−xAxB2TiO12 (A=Mg, Zn, Ni, and Co; B=Nb and Ta) dielectrics suitable for microwave telecommunication applications were prepared by the conventional solid-state ceramic route. Investigations were made on the structure and microstructure of the ceramics employing x-ray and scanning electron microscopic techniques. The dielectric properties were measured in the 3.5–7GHz frequency range. The time domain simulation of electromagnetic wave interaction with dielectric materials, using three-dimensional transmission line matrix modeling methods, is presented. Excellent agreement between experimental and simulated values of microwave dielectric properties was observed. The materials are potential candidates for applications in filters, oscillators and high efficiency low-loss dielectric antennas working especially at millimeter wave region.
Resonant-cavity approach to noninvasive, pulse-to-pulse emittance measurement
Authors: Kim J. S. , Nantista C. D. , Miller R. H. , Weidemann A. W.
Published: December 2005

We present a resonant-cavity approach for noninvasive, pulse-to-pulse, beam emittance measurements of noncircular multibunch beams. In a resonant cavity, desired field components can be enhanced up to QLλ∕π, where QLλ is the loaded quality factor of the resonant mode λ, when the cavity resonant mode matches the bunch frequency of a bunch-train beam pulse. In particular, a quad cavity, with its quadrupole mode (TM220 for rectangular cavities) at beam operating frequency, rotated 45° with respect to the beamline, extracts the beam quadrupole moment exclusively, utilizing the symmetry of the cavity and some simple networks to suppress common modes. Six successive beam quadrupole-moment measurements, performed at different betatron phases in a linear transport system, determine the beam emittance, i.e., the beam size and shape in the beam’s phase space, if the beam current and position at these points are known. In the presence of x-y beam coupling, ten measurements are required. One measurement alone provides the rms beam size of a large aspect ratio beam. The resolution for such a measurement of rms beam size with the rectangular quad-cavity monitor presented in this article is estimated to be on the order of 10μm. A prototype quad cavity was fabricated and preliminary beam tests were performed at the Next Linear Collider Test Accelerator at the Stanford Linear Accelerator Center. The results were mainly limited by beam jitter and uncertainty in the beam position measurement at the cavity location. This motivated the development of a position-emittance integrated monitor [J. S. Kim et al., Rev. Sci. Instrum. 76, 073302 (2005)].
Solid-state growth kinetics of Ni3Sn4 at the Sn–3.5Ag solder∕Ni interface
Authors: Alam M. O. , Chan Y. C.
Published: December 2005

Systematic experimental work was carried out to understand the growth kinetics of Ni3Sn4 at the Sn–3.5Ag solder∕Ni interface. Sn–3.5%Ag solder was reflowed over Ni metallization at 240°C for 0.5min and solid-state aging was carried out at 150–200°C, for different times ranging from 0to400h. Cross-sectional studies of interfaces have been conducted by scanning electron microscopy and energy dispersive x ray. The growth exponent n for Ni3Sn4 was found to be about 0.5, which indicates that it grows by a diffusion-controlled process even at a very high temperature near to the melting point of the SnAg solder. The activation energy for the growth of Ni3Sn4 was determined to be 16kJ∕mol.
Field electron emission from undoped, continuous, submicron-thick diamond films
Authors: Ternyak O. , Akhvlediani R. , Hoffman A. , Wong W. K. , Lee S. T. , Lifshitz Y. , Daren S. , Cheifetz E.
Published: December 2005

The present work shows that the field electron emission (FEE) properties of polycrystalline diamond films can be enhanced by control over the film thickness. The FEE properties of undoped, continuous, and smooth submicron-thick diamond films with initial nucleation densities of ∼5×1010particles∕cm2 were investigated as a function of diamond film thickness. A set of films with thickness ranging from 70–100to830nm yielded turn-on field values of 6–8V∕μm and threshold field values of 8.5–17.5V∕μm (for 0.3μA∕cm2), respectively, without any conditioning. It was found that the films of thickness up to ∼370nm can sustain stable current density as high as 0.1A∕cm2 without morphological modification. The thicker films, however, suffer from a strong degradation of the film and breakdown. The best FEE (lower turn-on and threshold fields and morphological stability) was obtained for a thin (100nm) continuous diamond film. This result is suggested to be attributed mainly to the efficient electron conduction from the back contact to the surface.
Evidence of self-frequency doubling from two inequivalent Nd3+ centers in the La2CaB10O19:Nd3+ bifunctional crystal
Authors: Brenier A. , Wu Yicheng , Fu Peizhen , Guo Rui , Jing Fangli
Published: December 2005

Nd x La 2 − x Ca B 10 O 19 crystals with different Nd3+ concentrations were grown by the high-temperature flux method. Room-temperature spectroscopy, i.e., absorption, emission, and lifetime measurements, was used to obtain the signatures of two inequivalent Nd3+ centers in the crystal host. They are attributed to Nd3+ substitution of both La3+ and Ca2+ sites. Nonradiative energy losses were estimated with the help of the Judd-Ofelt analysis. Self-frequency doubling of the F3∕24→I11∕24 Nd3+ laser channel with 5% efficiency was demonstrated in the XZ principal plane. It is clearly shown that self-frequency doubling can occur from two inequivalent luminescent centers.
Two-dimensionally localized modes of a nanoscale gap plasmon waveguide
Authors: Pile D. F. P. , Ogawa T. , Gramotnev D. K. , Matsuzaki Y. , Vernon K. C. , Yamaguchi K. , Okamoto T. , Haraguchi M. , Fukui M.
Published: December 2005

We report numerical analysis and experimental observation of two dimensionally localized plasmonic modes guided by a nanogap in a thin metal film. Dispersion, dissipation, and field structure of these modes are analyzed using the finite-difference time-domain algorithm. The experimental observation is conducted by the end-fire excitation of the proposed gap plasmon waveguides and detection of the generated modes using their edge scattering and charge coupled device camera imaging. Physical interpretation of the obtained results is presented and origins of the described modes are discussed.
Sensitive elemental analysis by ArF laser-induced fluorescence of laser ablation plumes: Elucidation of the fluorescence mechanism
Authors: Ho S. K. , Cheung N. H.
Published: December 2005

Numerous atomic analytes in plumes produced by pulsed-laser ablation fluoresced upon ArF laser irradiation. The likely mechanism was photoexcitation to levels near the ionization limit. These levels were dense and were probably broadened by the extreme plume density to allow efficient absorption of 193 nm photons. The excited atoms relaxed to intermediate states as the plume expanded. Interparticle interaction weakened and transitions from these states produced sharp spectral lines for elemental analysis. This ArF-induced fluorescence technique was orders of magnitude more sensitive than laser-induced plasma spectroscopy.
Electrode dependence of resistance switching in polycrystalline NiO films
Authors: Seo S. , Lee M. J. , Kim D. C. , Ahn S. E. , Park B.-H , Kim Y. S. , Yoo I. K. , Byun I. S. , Hwang I. R. , Kim S. H. , Kim J.-S. , Choi J. S. , Lee J. H. , Jeon S. H. , Hong S. H. , Park B. H.
Published: December 2005

We investigated resistance switching in top-electrode/NiO∕Pt structures where the top electrode was Au, Pt, Ti, or Al. For Pt∕NiO∕Pt and Au∕NiO∕Pt structures with ohmic contacts, the effective electric field inside the film was high enough to induce trapping or detrapping at defect states and thus resistance switching. For a Ti∕NiO∕Pt structure with well-defined Schottky contact at Ti∕NiO interface accompanied by an appreciable voltage drop, the effective electric field inside the NiO film was not enough to induce resistance switching. For an Al∕NiO∕Pt structure with a low Schottky barrier at the Al∕NiO interface, resistance switching could be induced at a higher voltage since the voltage drop at the Al∕NiO interface was not negligible but small.
Strain-induced ordering of small Ge islands in clusters at the surface of multilayered Si–Ge nanostructures
Authors: Marchetti R. , Montalenti F. , Miglio Leo , Capellini G. , De Seta M. , Evangelisti F.
Published: December 2005

Classical molecular-dynamics simulations based on the Tersoff potential are used to compute at the atomic level the strain-induced potential well generated at the surface of the capping layer by a buried, three-dimensional Ge island on Si(001). A simple model is outlined in order to predict the configurational arrangement for the nucleation of small Ge islands in such a potential well. The theoretical predictions are compared with atomic force microscope images of multilayered SiGe nanostructures grown by chemical vapor deposition. The cluster configuration is shown to be strongly dependent on the capping layer thickness, and to closely mimic the behavior predicted by the model.
Effects of conservation tillage farming on soil microbial biomass, organic matter and earthworm populations, in north-eastern Victoria
Authors: Haines PJ , Uren NC
Published: December 2005

A long-term field experiment was set up in 1981 in north-eastern Victoria to determine the effects of conservation tillage farming on agronomic and soil properties. Conventional cultivation was compared with direct drilling, and stubbles retained from the previous crop were compared with burning under direct drilling. Wheat was grown continuously over the 7 years of the experiment. Organic carbon (C), total nitrogen (N), soil microbial biomass and earthworm populations were measured. When samples were taken incrementally down the soil profile, there was a significant concentration gradient of organic matter under direct drilling. In the surface 2.5 cm, biomass C and N, and N mineralisation were 35, 30 and 62% greater, respectively, than under conventional cultivation. Direct drilling into retained stubble did not significantly increase organic C or total N. Of the estimated 7.8 t C/ha added to the soil from conserved crop stubbles, 4% was retained in the top 7.5 cm at the time of sampling. Organic C, total N and biomass C and N decreased with depth in both treatments. Microbial biomass varied considerably with season. The biomass of earthworms in the top 10 cm, under direct drilling, was more than twice that of conventional cultivation, while total worm numbers increased significantly (P<0.05), from 123 to 275/m2, when wheat stubble was retained with direct drilling compared to stubble burning.