bluuebunny/crossref_metadata_2025 huggingface dataset:
Techniques for Validating an Automatic Bottleneck Detection Tool Using Archived Freeway Sensor Data
Authors: Wieczorek Jerzy , Fernández-Moctezuma Rafael J. , Bertini Robert L.
Published: September 2010

Bottlenecks are key features of freeway systems. Their effects in performance and emissions are of increasing importance as congestion worsens in urban areas. In the United States, FHWA has been working to identify and monitor key bottlenecks in each state. In Oregon, a freeway data archive known as the Portland Oregon Regional Transportation Archive Listing archives measured count, density, and speed data from more than 600 locations at 20-s intervals. This archive has enabled development of online freeway performance and reliability analysis tools. This paper describes the rigorous evaluation and refinement of an automated tool for identifying recurrent freeway bottlenecks using historical data within the framework of the data archive. Efforts have focused on identification and display of active bottleneck features by using graphical tools and the selection of optimal variables that enabled careful identification of active bottlenecks. This research aims to detect bottleneck activation historically and, through future work, in real time as well. Ultimately, the results of this research will enhance the prioritization of improvements and implementation of operational strategies on the freeway network.
Effects of Temporal Data Aggregation on Performance Measures and Other Intelligent Transportation Systems Applications
Authors: Bigazzi Alexander Y. , Siri Helene , Bertini Robert L.
Published: September 2010

Intelligent transportation systems (ITSs) data are a valuable resource for traffic operations, transportation systems management, performance measurement, and transportation research. Historically, these data are time-aggregated for collection, transmission, and storage, with only mean values saved for traffic parameters for each arbitrary time interval. This convention of aggregation discards valuable information that is necessary for some applications. To understand whether systems should continue the practice of aggregation, this paper investigates how temporal aggregation can affect performance measures and other data applications. The investigation uses disaggregate speed data from loop detectors on a London freeway and vehicle trajectories from video imaging on a California freeway. Aggregating measured speed data greatly reduces the spread in reported vehicle speeds, which will distort estimates of emissions, fuel consumption, and travel delay. Using aggregate data for travel time estimates from sampled speeds results in errors attributable to the constant-speed assumption, group-averaged travel times, and using the arithmetic mean speed (as opposed to the harmonic mean speed) to estimate average travel time. Arithmetic mean speeds consistently underestimate aggregate delay, although estimating a harmonic mean speed from the arithmetic mean speed and speed variance can partially mitigate this effect. Temporal aggregation also affects the identification of traffic state transitions times, the estimation of shockwave speed and shockwave travel times, and the construction of fundamental diagrams. The results of this research will help increase understanding of the ability of ITS data to describe transportation systems, and improve forthcoming sustainability performance measures in the Portland Oregon Regional Transportation Archive Listing data archive at Portland State University.
Effect of Axle Load Measurement Errors on Pavement Performance and Design Reliability
Authors: Haider Syed Waqar , Harichandran Ronald S. , Dwaikat Monther B.
Published: September 2010

In traffic characterization, axle load spectra (ALS) are one of the most critical inputs in the new Mechanistic–Empirical Pavement Design Guide (MEPDG). ALS have a significant impact on the predicted pavement performance. At the design stage, it is typically assumed that ALS as measured by weigh-in-motion (WIM) systems have adequate data quality and accuracy. In fact, the quality of WIM-based data has inherent uncertainties because of inaccuracy and systematic bias. While WIM data accuracy depends on the sensor technology, calibration errors and drift over time may introduce a systematic bias. Several studies have investigated the impact of traffic data collection technologies, data coverage, accuracy, and calibration errors on pavement loading and performance prediction. However, these studies were limited to a few distress measures and did not address design reliability aspects as considered in the MEPDG. This study investigated the impact of probable WIM errors on the ALS and quantified the effects of these errors on the performance of both flexible and rigid pavements. Furthermore, the impact of uncertainties in ALS on design reliabilities is discussed in this paper. Although most findings reinforce existing concepts, the study provides a systematic overview of WIM data accuracy and calibration requirements, and the effect of associated uncertainties in the pavement design process. The results show that cracking in both flexible and rigid pavements is the distress most affected by ALS variations, while rutting in flexible pavements is moderately affected.
Clustering Analysis to Characterize Mechanistic–Empirical Pavement Design Guide Traffic Data in North Carolina
Authors: Sayyady Fatemeh , Stone John R. , Taylor Kent L. , Jadoun Fadi M. , Kim Y. Richard
Published: September 2010

This paper presents attempts to generate regional average truck axle load distribution factors (ALFs), monthly adjustment factors (MAFs), hourly distribution factors (HDFs), and vehicle class distributions (VCDs) for North Carolina. The results support Mechanistic–Empirical Pavement Design Guide (MEPDG) procedures. Weigh-in-motion data support the analysis and generate seasonal factors. MEPDG damage-based sensitivity analysis shows that pavement performance is sensitive to North Carolina site-specific ALFs, MAFs, and VCDs. Similar results occur for national default values of ALF, MAF, and VCD. Hierarchical clustering analysis based on North Carolina ALFs and MAFs develops representative seasonal traffic patterns for different regions of the state. Findings show that seasonal truck traffic has distinct characteristics for the eastern coastal plain, the central Piedmont, and the western mountains. A simplified decision tree and a related table help the pavement designer select the proper representative patterns of ALF and MAF. To develop VCD factors, the approach uses 48–h classification counts and a seasonal factoring procedure to account for day-of-week and seasonal variations. The approach incorporates site-specific truck traffic to improve the accuracy of pavement design. On the basis of sensitivity analysis results, pavement performance is found to be insensitive to North Carolina site-specific and national default values of HDF; thus, the average statewide HDF values may be used as input to MEPDG. Specific contributions of this research are the relative insensitivity of pavement performance to HDF, the use of 48-h classification counts to estimate VCD inputs, and a decision tree and table to help pavement designers select the proper ALF and MAF inputs.
Volume Data Correction for Single-Channel Advance Loop Detectors at Signalized Intersections
Authors: Wu Yao-Jan , Zhang Guohui , Wang Yinhai
Published: September 2010

The single-channel detection scheme has been widely used in practice for traffic control. Differing from lane-by-lane detection, single-channel detection has all loop detectors across multiple lanes wired together and provides a single input to the controller. Although single-channel (wired-together) detectors are commonly used by traffic agencies, the traffic volume data collected from these single-channel loops are inaccurate because of high misdetection rates, compared with lane-by-lane detection. This study focuses on developing a probability-based approach for correcting the traffic volume data collected by the single-channel loop detectors at signalized intersections. The proposed probability-based nonlinear model (NM) explicitly describes a potential model compared with a multiple linear regression model. Both models were calibrated and validated using real-life data from seven two-lane intersection approaches and three three-lane intersection approaches under various traffic conditions. The results showed that the proposed NM requires much less effort to calibrate and can effectively reduce system errors by reducing absolute mean errors by 60% on average. The correction effect of the model positively scales with increases in the system error rate. The verification results indicate the proposed NMs are capable of correcting the misdetection resulting from single-channel loop detectors and accurately estimate hourly traffic volume. The NM demonstrated its transferability to different locations and can be a general application in practice.
Simulation and Evaluation of Automated Vehicle Identification at Weigh-in-Motion Inspection Stations
Authors: Ismail Karim , Lim Clark , Sayed Tarek
Published: September 2010

This paper describes the development and validation of a discrete event microsimulation model that was applied to investigate the implementation of automated vehicle identification (AVI) technologies at Nordel Inspection Station in Delta, British Columbia. Current operational policies require commercial vehicles passing through the area to be inspected. The study, which includes an extensive field survey to collect validation data, determined that the implementation of a conservative industry participation of 10% in the AVI program would result in benefits ranging from $2.4 million to $7.9 million (2008 CAD), or benefit–cost ratios ranging from 11 to 47 for a range of net-present value project costs of $50 to $200,000. Benefits also include the reduction of emissions, with 5-year greenhouse gas (GHG) emissions reductions ranging from 2,200 to 7,200 metric tons, or a cost of $9.1 to $123 per reduction of 1 ton of GHG, for a range of project implementation scenarios.
Synthesis Framework for Generating County-Level Freight Data Using Public Sources for Spatial Autocorrelation Analysis
Authors: Ruan Minyan , Lin Jie (Jane)
Published: September 2010

Current publicly available national commodity flow databases have been restricted to the metropolitan level [e.g., freight analysis framework (FAF), Commodity Flow Survey, etc.], which is of little use to regional freight planning. Some local agencies have conducted regional surveys to obtain freight data in areas as small as the travel analysis zone or ZIP code level, but high costs and uncertainties associated with these surveys are hindrances to the availability and usefulness of the data. This paper presents a framework to synthesize high geography resolution freight outbound and inbound shipment data using the publicly existing commodity flow data, primarily FAF. Furthermore, the paper investigates the cross-county interdependency and spatial clusters of shipment generation in terms of spatial autocorrelation by using the generated county-level inbound and outbound flows. The outcome of this study is of two significances: (a) to provide an applicable data synthesis framework that generates the high geography resolution commodity flow data with acceptable accuracy; and (b) to understand the spatial characteristics of commodity flow across counties nationally.
Isolation and characterization of polymorphic microsatellite loci in Camellia nitidissima Chi (Theaceae)
Authors: Wei Ji‐Qing , Chen Zong‐You , Wang Zheng‐Feng , Tang Hui , Jiang Yun‐Sheng , Wei Xiao , Li Xiao‐Yi , Qi Xiao‐Xue
Published: September 2010

• Premise of the study: Microsatellite markers were developed in Camellia nitidissima for further population genetic studies.

• Methods and Results: Eight microsatellite markers were newly developed from C. nitidissima and 7 were transferred from other Camellia species. Two to 13 alleles per locus were identified for these microsatellites. Observed and expected heterozygosities ranged from 0.040 to 0.909, and 0.184 to 0.916, respectively. Four loci showed a significant deviation from Hardy–Weinberg equilibrium and five locus pairs displayed linkage disequilibrium.

• Conclusions: These microsatellite markers will be useful to assess the genetic variation and genetic structure of C. nitidissima.
Characterization and multiplexing of EST‐SSR primers in Cynodon (Poaceae) species1
Authors: Jewell Margaret C. , Frere Celine H. , Prentis Peter J. , Lambrides Christopher J. , Godwin Ian D.
Published: September 2010

• Premise of the study: Cynodon species are multiple‐use grasses that display varying levels of adaptation to biotic and abiotic stress. Previously identified EST‐SSR primers were characterized and multiplexed to assess the level of genetic diversity present within a collection of almost 1200 Cynodon accessions from across Australia.

• Methods and Results: Two multiplex reactions were developed comprising a total of 16 EST‐SSR markers. All SSR markers amplified across different Cynodon species and different levels of ploidy. The number of alleles ranged from one to eight per locus and the total number of alleles for the germplasm collection was 79.

• Conclusions: The 16 markers show sufficient variation for the characterization of Cynodon core collections and analysis of population genetic diversity in Cynodon grasses.
IL-1RL2 and Its Ligands Contribute to the Cytokine Network in Psoriasis
Authors: Blumberg Hal , Dinh Huyen , Dean Charles , Trueblood Esther S. , Bailey Keith , Shows Donna , Bhagavathula Narasimharao , Aslam Muhammad Nadeem , Varani James , Towne Jennifer E. , Sims John E.
Published: September 2010

Psoriasis is a common immune-mediated disease in European populations; it is characterized by inflammation and altered epidermal differentiation leading to redness and scaling. T cells are thought to be the main driver, but there is also evidence for an epidermal contribution. In this article, we show that treatment of mouse skin overexpressing the IL-1 family member, IL-1F6, with phorbol ester leads to an inflammatory condition with macroscopic and histological similarities to human psoriasis. Inflammatory cytokines thought to be important in psoriasis, such as TNF-α, IL-17A, and IL-23, are upregulated in the mouse skin. These cytokines are induced by and can induce IL-1F6 and related IL-1 family cytokines. Inhibition of TNF or IL-23 inhibits the increased epidermal thickness, inflammation, and cytokine production. Blockade of IL-1F6 receptor also resolves the inflammatory changes in human psoriatic lesional skin transplanted onto immunodeficient mice. These data suggest a role for IL-1F family members in psoriasis.
Lytic Granule Polarization, Rather than Degranulation, Is the Preferred Target of Inhibitory Receptors in NK Cells
Authors: Das Asmita , Long Eric O.
Published: September 2010

Natural cytotoxicity is achieved by polarized release of perforin and granzymes at the NK cell–target cell immunological synapse. Signals for granule polarization and degranulation can be uncoupled in NK cells, which raises the question of their respective sensitivity to inhibitory receptors. Expression of either HLA-C or HLA-E on the human cell line 721.221 blocked granule polarization, degranulation, and CD16-dependent MIP-1α secretion by NK cell clones that expressed inhibitory receptors of matching HLA specificity. To test inhibition of signals for polarization and degranulation separately, Drosophila S2 cells expressing ICAM-1 with either HLA-C or HLA-E were used. CD16-dependent degranulation and MIP-1α secretion were not fully inhibited, suggesting that other receptor–ligand interactions, which occur with 721.221 cells, contribute to inhibition. In contrast, HLA-C or HLA-E on S2 cells coexpressing ICAM-1 or ULBP1 were sufficient to block granule polarization induced by either LFA-1 or NKG2D, even during concomitant CD16-dependent degranulation. Similarly, expression of a ligand for NKR-P1A on S2 cells inhibited granule polarization but not CD16-induced degranulation. Therefore, granule polarization, rather than degranulation, is the preferred target of inhibitory receptors in NK cells.
GATA2 and Sp1 Positively Regulate the c-kit Promoter in Mast Cells
Authors: Maeda Keiko , Nishiyama Chiharu , Ogawa Hideoki , Okumura Ko
Published: September 2010

The c-kit gene is expressed in hematopoietic stem cells and lineage progenitor cells but is downregulated during cell development in most lineages, except for mast cells. In mast cells, high expression of c-kit is maintained during development, and c-Kit signaling is essential for mast cell development. To analyze the mechanisms by which c-kit gene expression are regulated in mast cells, we examined mast cell type-specific regulation of the c-kit promoter region. We observed that a GC-box in the c-kit promoter was critical for transcriptional activity and was bound to the transcription factor Sp1 as assessed using reporter assay and electrophoretic mobility assay. Chromatin immunoprecipitation assay and coexpression analyses showed that the transcription factor GATA2, which was recruited to the c-kit promoter in a mast cell-specific manner, in addition to Sp1, transactivated the c-kit promoter via the GC-box. Electrophoretic mobility assay and rechromatin immunoprecipitation assay indicated that GATA2 binds to the GC-box by forming a complex with Sp1. Introduction of Sp1 small interfering RNA significantly reduced the amount not only of Sp1 but also of GATA2 binding to the c-kit promoter in mast cells, resulting in suppression of c-kit transcription. Knockdown of GATA2 suppressed the recruitment of GATA2 toward the c-kit promoter, subsequently suppressing cell surface expression of c-Kit. These findings indicate that GATA2 and Sp1 play crucial roles in expression of the c-kit gene in mast cells.
Innate Immune Proteins C1q and Mannan-Binding Lectin Enhance Clearance of Atherogenic Lipoproteins by Human Monocytes and Macrophages
Authors: Fraser Deborah A. , Tenner Andrea J.
Published: September 2010

Atherosclerosis is a chronic inflammatory disorder that is characterized by the accumulation of modified lipoproteins in the arterial intima. C1q and mannan-binding lectin (MBL) are not only recognition components involved in activation of inflammation via the complement cascade, but they are also able to directly modulate phagocyte activation. Studies in C1q−/− and MBL−/− mice suggest that these molecules play a protective role in the early atherosclerotic lesion in the absence of, or prior to, expression of other complement components. However, in later stages, complement activation becomes an inappropriate inflammatory response, contributing to disease pathology. Therefore, to investigate possible molecular interactions of C1q and MBL in atherosclerotic lesions, we examined the influence of C1q and MBL in the clearance of native and modified lipoproteins by human monocytes and monocyte-derived macrophages. Both C1q and MBL are shown to bind and enhance the monocyte/monocyte-derived macrophage clearance of modified forms of low-density lipoprotein (LDL), including oxidized LDL and acetylated LDL, but not native LDL. Modified forms of LDL activate the classical complement pathway, but no lectin pathway activation was detected. Interestingly, monocytes that ingested modified LDL in the presence of C1q or MBL upregulated surface CD80 and CD31, as well as CCL2 chemokine gene expression. However, C1q and MBL also significantly reduced levels of free cholesterol accumulation in monocytes and human monocyte-derived macrophages that ingested oxidized LDL, while enhancing high-density lipoprotein–specific cholesterol efflux from these cells. These results suggest a novel pathway in which C1q and MBL influence removal and metabolism of atherogenic forms of LDL in the early stages of atherosclerosis.
The Effect of Melt Treatment on Glass Forming Ability and Thermal Stability of Al‐Based Amorphous Alloy
Authors: Mu Juan , Fu Huameng , Zhu Zhengwang , Wang Aimin , Li Hong , Hu Zhuangqi , Zhang Haifeng
Published: September 2010

Melt treatment is widely used to mediate the structure of materials. Recently, it is evidenced to be a new way to improve the glass forming ability (GFA) and thermal stability of the amorphous alloys. Bulk metallic glass was obtained through this process in the Al–Ni–La alloy system. In this work, the mechanism of melt treatment on the GFA and thermal stability of the Al–Ni–La alloy was studied. A Ni‐rich metastable high‐melting‐temperature‐phase is found to occur to this alloy system. The elimination of the Ni‐rich phase through the melt treatment is attributed to stabilize the thermal stability of the melt and, accordingly, enhances the GFA and thermal stability of the amorphous alloy.
Summary of “proposed national strategies for the prevention of leading work‐related diseases and injuries, Part 1”
Authors: Millar J. Donald
Published: September 2010

Strategies for the prevention of leading occupational health problems have been proposed by the National Institute for Occupational Safety and Health (NIOSH). NIOSH prepared these strategies following publication in 1983 of its suggested list of ten leading work‐related diseases and injuries. At a national symposium in 1985, occupational health experts from academia, organized labor, management, professional associations, and voluntary organizations conducted an in‐depth evaluation of the prevention strategies for the first five conditions on the list: occupational lung diseases, musculoskeletal injuries, occupational cancers, severe occupational traumatic injuries, and occupational cardiovascular diseases. The strategies were then revised to incorporate improvements suggested at the symposium and were published in booklet form. A summary of the revised strategies is provided.
Effects of informing workers of their health risks from exposure to toxic materials
Authors: Houts Peter S. , Mcdougall Vernon
Published: September 2010

This study compared the mental health, attitudes, and smoking behaviors of 133 workers who had been informed of health risks from exposure to toxic materials on the job with 137 workers who worked in similar conditions but who had not been told that their health was at risk because of exposure to toxic materials. The informed workers reported more health problems than controls, but there were no significant differences between the informed and uninformed groups in mental health, attitudes toward health hazards in or outside of the workplace, or in smoking rates. Ninety percent of all respondents felt that exposed workers definitely should be told of their health risks. These findings indicate little psychological risk from informing workers about their risks because of exposure to toxic substances and a strong desire on the part of workers to be informed.
Central facial palsy revisited: A clinical‐radiological study
Authors: Cattaneo Luigi , Saccani Elena , De Giampaulis Piero , Crisi Girolamo , Pavesi Giovanni
Published: September 2010

We investigated the pattern of volitional facial motor deficits in acute stroke patients. We assessed the strength of single facial movements and correlated it to the site of infarct classified on computed tomography scans. Exclusion criteria were previous stroke, cerebral hemorrhage, and subcortical stroke. Results showed that weakness in eyelid closure was associated with anterior cerebral artery (ACA) stroke. Weakness in lip opening was associated with middle cerebral artery (MCA) stroke. We suggest that sparing of upper facial movements in MCA stroke is due to the presence of an upper face motor representation in both the MCA and ACA territories. ANN NEUROL 2010;68:404–408
General axial shapes of sodium clusters
Authors: Frauendorf S. , Pashkevich V. V.
Published: September 2010

The shell correction method is applied to calculate the shapes and binding energies of Na clusters. The axial equilibrium shapes are calculated by minimizing five deformation parameters simultaneously. Strong deviations from spheroidal shapes including reflection asymmetric ones are found. The influence of cluster deformation on the separation energies and ionization potentials and on the splitting of the photo ‐ resonance are compared with the available experimental data. The N‐dependence of the cluster shape and its relation to the N‐ and Z‐dependences of the nuclear shape is discussed.
Thermodynamic properties of CeCu6‐xAux: Fermi‐liquid vs. non‐Fermi‐liquid behaviour
Authors: Finsterbusch D. , Willig H. , Wolf B. , Bruls G. , Lüthi B. , Waffenschmidt M. , Stockert O. , Schröder A. , Löhneysen H. V.
Published: September 2010

We report on a detailed comparison of the thermodynamic properties of the heavy‐fermion system CeCu6 which can be described as a Fermi liquid at low temperatures T < 0.1 K, and CeCu5.9Au0.1 where strong deviations from the Fermi‐liquid behaviour were found previously in the T dependence of the specific heat C, magnetization M and electrical resistivity p. The specific heat, magnetization and elastic constants are investigated in a large range of magnetic fields, corroborating the idea that the non‐Fermi‐liquid behaviour arises from low‐lying spin excitations. For the elastic constants, a striking linear T dependence is found for CeCu5.9Au0.1 in contrast to the T2 Fermi‐liquid behaviour of CeCu6.
Structure and dynamics at the Pt(100)‐surface
Authors: Wachter A. , Bohnen K. P. , Ho K. M.
Published: September 2010

Using first‐principles total‐energy calculations the lattice relaxation, surface energy, work function and surface phonons have been determined for the Pt(100)‐surface. Calculation of forces allows for a very efficient determination of equilibrium geometries and interplanar force constants. Results will be presented and compared with available experimental information.
Electronic excitations in NiO
Authors: Takahashi Manabu , Igarashi Jun‐Ichi
Published: September 2010

A many‐body theory for a multi‐orbital tight‐binding model is developed by taking account of local three‐body correlations. The theory is applied to the antiferromagnetic NiO. The multiple structures of three‐particle states are fully taken into account. It is shown that the self‐energy correction leads to the correct value of the band gap, the orbital character of the valence band top which is consistent with the charge‐transfer insulator, and the presence of the satellite intensities. The quasiparticle band is obtained in good agreement with the angular‐resolved photoemission data of NiO.
Mixed spin‐ and spin‐ Ising models with random nearest‐neighbour interactions
Authors: Benayad N. , Dakhama A. , Klümper A. , Zittartz J.
Published: September 2010

Using the effective field theory with correlations, we study mixed spin−3/2 and spin−1/2 Ising models with random bonds and crystal‐field interactions on the honeycomb lattice. The nearest‐neighbour couplings Jij are taken as random variables with distribution P(Jij) = pδ(Jij − J)+(1 − p)δ(Jij − αJ), where J > 0 and |α| ≤ 1. In a certain range of negative values of α, the phase diagrams exhibit re‐entrant behaviour. In detail, we investigate separately two kinds of disorder: Bond dilution (α = 0) and random ±J interactions (α = −1). In both cases, the influence of the an‐isotropy on the phase diagrams shows some new outstanding features.
Low energy properties of identical and strongly correlated particles
Authors: Häusler W.
Published: September 2010

Interesting qualitative consequences can arise from the quantum mechanical identity among strongly correlated particles that carry spin. This is demonstrated for properties connected with the low energy excitations in molecular and electronic systems. Spatial permutations among the identical particles are used as the key features.

The particular behaviour of rotational tunneling molecules or molecular parts under the influence of dissipation are discussed together with the consequences arising for conversion transitions. The relationship between the thermal shifting of the tunneling line and the conversion rate at low and at elevated temperatures is explicated. The valuable information, that can be extracted from the conversion behaviour after isotopical substitution, is explained in detail. At low temperatures qualitative changes are predicted for the conversion rate by deuteration. Weakly hindered rotors show, also experimentally, drastic isotopic effects.

The second part is devoted to finite systems of strongly interacting electrons that appear in semi‐conductor nano‐structures. The lowest excitation energies are strongly influenced by the interaction. They can be understood and determined starting from the limit of crystallized electrons by introducing localized many particle ‘pocket states’. The energy levels show multiplet structure, in agreement with numerical results. The total electron spin, associated with the low energy excitations, is crucially important for the nonlinear transport properties through quantum dots. It allows for instance to explain the appearance of negative differential conductances.
Eigenmodes of a compressible liquid drop
Authors: Wehner J. , Krappe H. J.
Published: September 2010

The eigenmodes of a non‐viscous, compressible liquid drop are investigated. The spectrum is shown to be derivable from two Hermitian eigenvalue problems which are weakly coupled by a non‐Hermitian operator. It is shown that both eigenvalue problems admit an asymptotic, lepto‐dermous expansion. Their contribution to the entropy of the droplet therefore also allows for such an expansion.
Brillouin‐Wigner and Feenberg perturbation methods in many‐body theory
Authors: Keiter H. , Kilić S.
Published: September 2010

Brillouin‐Wigner (BW) perturbation formulae can be rearranged into a form first proposed by Feenberg. Feenberg's perturbation formulae also follow from a variational principle. They are successfully tested at two typical problems, for which ordinary perturbation techniques completely fail. The first is to find conditions for the bosonization of the Tomonaga model perturbatively. The second is to clarify whether non‐Fermi liquid behavior of the momentum distribution function of the Luttinger model can be achieved perturbatively.
Exchange anisotropy of cobalt fine particles
Authors: Petrov A. , Kudrenitskis I. , Belogurov S. , Nepijko S.
Published: September 2010

The present paper is devoted to the investigation of exchange anisotropy of fine cobalt particles with oxidized surface. From the value of hysteresis loop shift the value of exchange magnetic anisotropy constant and its dependence of the particle size has been determined. X‐ray structure analysis has shown, that cobalt core of the particle is surrounded by a thin layer of the CoO which, in turn, is covered by a layer of Co3O4.
Quantum corrections to the conductivity and periodic orbits: Integrable systems
Authors: Hackenbroich Gregor , von Oppen Felix
Published: September 2010

We extend the recently developed semiclassical theory for the conductivity to periodic semiconductor structures whose classical dynamics is integrable. We find that the conductivity of integrable systems exhibits quantum oscillations as function of magnetic field and Fermi energy which are closely related to both the Shubnikov‐de Haas oscillations and the oscillations observed in the conductivity of antidot lattices. A general expression for the quantum oscillations is derived which is analogous to the Berry‐Tabor formula for the spectral density of integrable systems.
Grafting of iPP powder with methacrylate monomers in water medium
Authors: Chmela S̆. , Fiedlerová A. , Janigová I. , Novák I. , Borsig E.
Published: September 2010

The grafting of different methacrylates on iPP in the solid state has been studied under various reaction conditions using a radical initiation. Three peroxides and five grafting agents representing methyl‐, ethyl‐, butyl‐, ethyl hexyl‐, and dodecyl methacrylate were tested. The grafting efficiency (GE) performed in water medium (slurry) as possible heat transfer medium was compared with the GE obtained without using water. The iPP powder was first impregnated with monomer and peroxide initiator and then water solution of NaCl was added. Obtained GEs were much higher for all peroxides and monomers used when compared with GE performed without water. Quantity of grafted monomer was determined by Fourier transform infrared spectroscopy (FTIR). The products were characterized by differential scanning calorimetry (DSC) and surface energies of grafted iPP films were measured. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011
Polarometrie van kwikoplossingen
Authors: Poma K.
Published: September 2010

1. Des essais ont' été effectués en vue du titrage polarométrique des ions Hg(I) et Hg(II) par I, SCN et CN.

2. II est possible de déduire la concentration des ions Hg(II) à l'aide d'une courbe d'étalonnage donnant la relation entre cette concentration et le saut du potentiel, tant à l'aide d'ions I que d'ions CN−.

3. Des solutions d'ions Hg(II) peuvent être titrées par voie polarométrique à l'aide d'ions SCN avec une précision de 1%. Le titrage inverse est également réalisable.

4. Le titrage polarométrique des ions Hg(II) par les ions CN est incertain ainsi que le titrage inverse.
La tension superficielle des mélanges binaires
Authors: Prigogine I.
Published: September 2010

L'objet de ce travail est de montrer que la méthods pour l'étude de la tension superficielle que l'auteur a développée récemment en collaboration avec R. Delay permet de préciser l'état moléculaire de la phase superficielle. On étudie successivement les systèmes sulfure de carbone‐éther éthylique, acétone‐éther éthylique, chloroforme‐éther éthylique, ainsi que benzène‐acide acétique et benzène‐alcool éthylique.

Nous comparons la composition de la phase superficielle à celle de la solution et nous discutons em particulier l'effet de l'association dans la phase superficielle sur la tension superficielle.

Dans les cas chloroforme‐éther, benzène‐alcool, l'association semble avoir la même importance que dans la phase volumique. Dans le second cas la courbe de la tension superficielle est compatible avec la présence, tout comme dans la solution, de complexes d'association formés d'un nombre quelconque de particules. Au contraire, dans le cas benzène‐acide acétique, l'association dans la phase superficielle semble beaucoup plus faible que dans la phase volumique.
Contribution à l'étude de l'acide ribonucléique de la levure
Authors: Chantrenne H.
Published: September 2010

Dans la première partie de ce travail, nous montrons qu'il est possible d'isoler d'une préparation d'acide nucléique de la levure, une fraction A qui précipite dans des conditions parfaitement reproductibles. Les préparations commerciales contiennent cet acide A en proportions très variables.

L'étude électrophorétique d'une préparation de nucléate A a montré qu'elle contenait plus de 91 % d'une substance bien définie et parfaitement séparable par électrophorèse.

L'électrotitration du nucléate. A, de la partie soluble B et d'un nucléate commercial a fourni les résultats suivants:

L'acide A contient des fonctions répondant aux pK suivants: 3, 7 ‐4, 2–6, 2–8, 6–10, 1–10, 2. Il se distingue donc de l'acide B par la présence d'une fonction supplémentaire de pK 8, 6 et un petit déplacement de la fonction dont le pK est voisin de 6. De plus il est possible qu'il ne possède pas la fonction dont le pK est voisin de 2, 3.

Le produit B possède dans la région étudiée, des fonctions ionisables dont les pK sont voisins de 2, 3–3, 7–4, 2–6, 0–10, 1–10, 2.

Il possède une fonction correspondant à chacun des dits pK par quatre atomes de phosphore. La courbe de titration est conforme à la courbe théorique de Levene dans toute la région éludiée, soit de pH 2, 5 à pH 10, 0.

L'acide commercial de Boehringer qui est un mélange des acides A et B fournit une courbe de titration intermédiaire.
Études sur L'Invertase. II. Étude Physico‐Chimique des Solutions D'Invertase
Authors: Dieu H.
Published: September 2010

Les solutions d'invertase d'activité spécifique constante dont l'obtention est décrite dans une première publication ont été soumises à différents critères de pureté dont l'électrophorèse, la diffusion et la solubilité.

Deux électrophorèses ont été réalisées à deux pH différents: 4,50 et 5,52 par la Schlierenmethode de Tiselius, le pH 4,50 étant le pH de mobilité minimuné, comme des expériences de migration électrophorétique par ultramicroscopie l'ont montré. Il résulte de ces expériences que ces solutions d'invertase contiennent deux substances, dont l'une a une charge électrique très faible dans une zone étendue de pH. Les expériences de diffusion confirment cette hypothèse.

La méthode de diffusion de Northrop, modifiée, nous indique une masse moléculaire d'environ 3.500 pour le ferment, alors que la méthode de diffusion de Lamm montre une masse moléculaire de l'ordre de 100.000 due très sûrement à une protéine d'accompagnement.

Enfin une courbe de solubilité avec teneurs en azote très faible, semble indiquer que cette protéine d'accompagnement constitue la majeure partie de la substance protéique de nos solutions.
La Recherche des Acides α‐Monoaminés Monocarboxyles dans les Hydrolysats Protéiques par la Spectrographie Raman
Authors: Renard Marcel
Published: September 2010

l'auteur après avoir montré que, dans la région qu'il a choisie pour ses déterminations qualitatives (250 à 1.400 cm−1) le spectre Raman d'un mélange d'acides α‐chlorés est l'exacte superposition des spectres de ses constituants, expose comment la méthode de comparaison des microphotogrammes permet de retrouver rapidement et correctement les constituants du mélange.
Sur un nouveau réactif général des alcaloïdes Applications qualitatives et quantitatives
Authors: Wachsmuth H.
Published: September 2010

Le réactif que nous proposons comme réactif général des alcaloïdes (iodure d'antimoine en solution éthérée) s'est révélé extrêmement sensible pour tous les alcaloïdes tant basiques que salifiés (sensibilité ± 1: 1.000.000 — 1: 7.000.000). Il permet la détermination quantitative des bases alcaloïdiques ou de leurs sels, ainsi que le dosage de certaines pseudobases.
The Dissociation and Titration Constants of Polybasic Acids
Authors: Overbeek J. Th. G.
Published: September 2010

La variation de la “constante de dissociation» des acides macromoléculaires polybasiques en fonction du degré de neutralisation, de la dilution de l'acide et de la teneur en électrolyte de la solution est expliquée par la présence d'une charge négative sur la macromolécule. Par l'attraction des ions d'hydrogène cette charge diminue la tendance de dissociation.

Une forme compacte et une charge élevée de la macromolécule et une faible teneur en électrolyte favorisent cette interaction et par conséquence entraînent une diminution de la constante de dissociation.

Quand la teneur en électrolytes et la constante de dissociation ont été déterminées, le diamètre de la molécule en suspension peut être calculé. Le diamètre de la molécule de la gomme arabique dérivé de cette manière est en bon accord avec d'autres déterminations de la même grandeur.

En introduisant la statistique d'une grosse molécule en chaîne, qui porte des charges, on dérive une relation quantitative entre la constante de dissociation, la charge et la teneur en électrolyte. Cette relation est représentée dans la figure 1.
Mesure de la polydispersité de la nitrocellulose par titration turbidimétrique
Authors: Oth André
Published: September 2010

Une méthode de mesure de la polydispersité des polymères proposée par Morey et Tamblyn [1] a été étudiée dans le cas de la dinitrocellulose.

Une série de fractions ont été préparées pour calibrer la méthode.

Les conditions expérimentales (concentration, vitesse d'addition du précipitant) ont été standardisées.

On a trouvé que, dans le cas particulier de la nitrocellulose, la turbidité des suspensions était indépendante du poids moléculaire.

Moyennant une approximation sur la loi de solubilité, on peut calculer la courbe de distribution des poids moléculaires à partir de la courbe de précipitation turbidimétrique.

Le résultat obtenu est alors comparé a celui obtenu par la méthode gravimétrique classique et à la courbe calculée à partir des moyennes Mn et Mw.
La déshydrogénation des alcools secondaires en phase liquide sur le nickel
Authors: Thonon C. I. , Jungers J. C.
Published: September 2010

La déshydrogénation des alcools secondaires en cétone, qui se produit sur le nickel dès la température d'ébullition, est d'ordre zéro par rapport au réactif et d'ordre négatif par rapport au produit. L'inhibition par la cétone est si marquée que la réaction est pratiquement bloquée bien avant que la transformation ne soit complète. Ces faits s'interprètent en admettant que la cétone produite présente un coefficient d'adsorption nettement supérieur à celui de l'alcool. On a pu estimer le rapport de ces coefficients et étudier comment il est influencé par la température, l'emploi de solvants et la nature du catalyseur.
Synthèse et transformation de l'éthylmercaptan sur l'alumine
Authors: Limido J. , Mallah I. A. , Jungers J. C.
Published: September 2010

Ce travail présente les résultats obtenus dans l'étude de la synthèse et de la décomposition de l'éthylmercaptan sur l'alumine. La décomposition en thioéther, étudiée d'abord, est une réaction limitée; elle est, à l'origine, d'ordre zéro par rapport au mercaptan et d'ordre négatif par rapport au thioéther. L'énergie d'activation qui est de 25.000 calories aux basses températures diminue à mesure que la température s'élève. La synthèse du mercaptan qui est aussi limitée, est d'ordre 1 par rapport au mélange stéchiométrique et d'ordre négatif par rapport au mercaptan; l'énergie d'activation est de 10.000 calories. Ces réactions ont pu être appliquées à la production de mercaptan et de thioéther en quantités pondérables. Les réactions inverses présentent une vitesse faible ou nulle dans les conditions réalisées dans ce travail.
On the Constitution of the β Hops Acid
Authors: Verzele M. , Govaert F.
Published: September 2010

According to the authors, the lupulone formula should be changed. The difference with the Wieland formula lies in the position of two double bonds. Experimental evidence to support the general lupulone structure and the new double bond positions was obtained by splitting up the lupulone molecule with alkali, and by isolating and identifying the different scission products obtained.
Contribution à l'étude du mécanisme de la catalyse hétérogène: L'Activation de l'Azote par le fer et le Nickel
Authors: D'Hont M. , Jungers J. C.
Published: September 2010

Divers arguments conduisent à admettre que c'est l'activation de l'azote moléculaire qui constitue l'étape difficile dans la synthèse catalytique de l'ammoniaque par le fer ou le nickel. Dans ce travail on a montré qu'on peut obtenir de l'ammoniaque dès la température de 60° C par hydrogénation des complexes produits par adsorption destructive de l'acide cyanhydrique sur ces catalyseurs. On constate, en outre, que le carbone se désorbe sous forme de méthane dès la température de 140° C dans le cas du nickel, mais seulement vers 400° C pour le fer. Ces observations permettent de rendre compte du comportement de ces catalyseurs dans d'autres réactions.
Dérivés β‐anilinovinyliques de bases hétérocycliques I Dérivés Substitués Dans La Fonction Anilino
Authors: van Dormael A. , Jaeken J. , Nys J.
Published: September 2010

Les auteurs décrivent une série de dérivés anilinovinyliques de sels cycloammoniques portant dans le groupement anilino des substituants, tels que chlore, méthoxy, thiométhyle, diéthylamino, phényle (accolé). Les modes d'obtention consistent en l'action soit d'une formamidine substituée, soit d'une aniline substituée en présence de formiate d'éthyle sur un sel cycloammonique porteur d'un groupement méthyle réactionnel, ou bien en l'action d'une aniline substituée sur un sel cycloammonique portant une fonction β‐acétanilinovinylique.

Les données optiques de ces nouveaux dérivés sont également discutées.
Dérivés β‐anilinovinyliques de bases hétérocycliques (*) II Nouveaux Modes D'obtention D'une Hémicyanine Double
Authors: van Dormael A. , De Cat A.
Published: September 2010

Les auteurs décrivent la synthèse de la bis‐β‐β′‐(iodoéthylate de 2‐vinyl‐benzoxazol)‐p. phénylène‐diamine par réaction:

1° De l'iodoéthylate du 2‐(β‐acétanilinovinyl)‐benzoxazole sur la p. phénylène‐diamine;

2° De l'iodoéthylate du 2‐méthyl‐benzoxazole sur la p. phénylène‐diamine en présence d'orthoformiate d'éthyle;

3° De l'iodoéthylate du 2‐(β‐p. amino‐anilinovinyl)‐benzoxazole soit sur l'iodoéthylate du 2‐(β‐acétanilinovinyl)‐benzoxazole : 4° Soit sur l'iodoéthylate du 2‐méthyl‐benzoxazole en présence d'orthoformiate d'éthyle.
Contribution à l'étude du dosage polarographique du titane
Authors: Vandenbosch V.
Published: September 2010

Le potentiel de mi‐vague du système Ti+4/Ti+3 a été déterminé à différentes valeurs de pH. Diverses solutions de base: oxalique, tartrique et citrique ont été étudiées.

La solution oxalique, contenant 10 % d'acide sulfurique, est stable pendant quelques heures et peut servir à des déterminations quantitatives. La vague du fer (Fe+3/Fe+2) précède de très près celle du titane.

En milieu tartrique on pourrait opérer soit en solution très acide soit à pH 6,5. Dans le premier cas la mesure précise du courant de diffusion est difficile, dans le second cas le pouvoir tampon est insuffisant.

En milieu citrique la solution de pH 5,7, à l'exclusion de toute autre valeur de pH se prête très bien au dosage quantitatif du titane. Le complexe citrique est stable et la différence des potentiels de réduction du fer et du titane rend possible le dosage simultané de ces deux éléments.

II a été démontré en outre que la réaction d'oxydo‐réduction est réversible en solution fortement acide seulement.
Propriétés thermodynamiques des solutions associées
Authors: Prigogine I. , Mathot V. , Desmyter A.
Published: September 2010

Considering an associated solution, e. g. alcohol‐carbon tetrachloride, as a system of monomolecules and associated complexes in equilibrium with one another, it is shown that the thermodynamic properties, particularly activity coefficients, are completely determined by the chemical potentials of the monomolecules only.

Using the principle of detailed balancing of elementary processes, it is shown that the following relation holds between the activity coefficients ƒA/ƒB = α where α is the fraction of molecules of the associated constituent which appear as monomolecules. This relation may be checked by comparing thermodynamic measurements of ƒA, and ƒB with values of a obtained from the spectroscopic study of the intensity of the OH monomolecular vibration band. Different statistical models are used for the calculation of the thermodynamic properties of the associated solutions. The results are compared and discussed. The influence of the size and shape of the associated complexes is studied.

The calculated results are compared to the experimental ones for the systems magnified image In these three cases, the relation ƒA/ƒB = α holds quite fairly. A direct proof is thus given that the deviations from ideality may be justified by the formation of complexes in these systems.

In addition, the comparison of the observed activity coefficients and those calculated by the different statistical models used shows that, in concentrated solutions, an important part of the complexes must be formed by two or three dimensional molecular aggregates. A chain‐association alone is not sufficient to interpret the departures from ideality.
Application de la méthode des extinctions compensées au dosage par spectrophotométrie infra‐rouge de l'isomère γ dans les mélanges d'hexachlorocyclohexanes
Authors: Pirlot G.
Published: September 2010

By means of a particular definition of the “compensated extinction”, it is possible, with the help of only one calibration curve, to determine the concentration of one substance when there is some overlapping between the characteristic band of this substance and the spectra of the other constituents of the mixture.

This method was applied to the determination of γ.hexachlorocyclohexane in the presence of the α, β an δ isomers.