bluuebunny/crossref_metadata_2025 huggingface dataset:
Temperature Dependence of the Back‐Stress in Shear for Glassy Polycarbonate
Authors: Negahban Mehrdad , Strabala Kyle , Delabarre Pierre , Goel Ashwani , Feng Ruqiang , Grene Jean
Published: November 2007

Summary: Back‐stress is the equilibrium stress and represents conditions under which relaxation events in the material stop and the material can carry an applied load indefinitely without a change in strain. In most models for glassy polymers, back‐stress plays a central role since relaxation in materials is closely related to the distance of the current conditions from equilibrium. A number of these models that are commonly used for modeling glassy polymers use a modeling structure similar to large deformation plasticity. The flow rule for the plastic strain in these models are directly connected to the “over‐stress,” a properly invariant difference between the stress and the back‐stress. The importance of correctly evaluating the back‐stress to use in these models is clear. For this class of models, the authors have recently developed a method for directly calculating the back‐stress under shear deformations. This method is based on evaluating the slope of the stress‐strain response under conditions of similar elastic and plastic strain, but different strain rates. Since plastic flow goes to zero at equilibrium, the back‐stress can be found by locating points of zero plastic strain rate. Using the proposed method, the back‐stress in glassy polycarbonate has been evaluated under shear in isothermal tests going from room temperature to 120 °C, just below the glass transition temperature for polycarbonate. The proposed method provided a full map of the back‐stress for polycarbonate over a large range of shear strain and temperature.
Liquid Chromatography of Synthetic Polymers under Limiting Conditions of Insolubility III
Authors: Berek Dušan
Published: November 2007

Summary Performance was evaluated of silica based commercial monolithic rod‐like columns in liquid chromatography of synthetic polymers under limiting conditions of enthalpic interactions (LC LC). LC LC employs the barrier effect of the pore permeating and therefore slowly eluting small molecules toward the pore excluded, fast eluting macromolecules. Phase separation (precipitation) barrier action was applied in present study. The barrier was created either by the narrow pulse of an appropriate nonsolvent injected into the column just before the sample solution (LC LC of insolubility – LC LCI) or by the eluent itself. In the latter case, the polymer sample was dissolved and injected in a good solvent (LC LC of solubility – LC LCS). In LC LCI, polymer species cannot break thru the nonsolvent zone while in LC LCS they cannot enter eluent, which is their precipitant. Therefore, polymer species keep moving in the zone of their original solvent. Macromolecules eluting under the LC LC mechanism leave the column in the retention volume (VR) roughly corresponding to VR of the low molar mass substances and can be efficiently separated from the polymer species non‐hindered by the barrier action. The known advantages of monoliths were confirmed. From the point of view of LC LCI and LC LCS the most important quality of monolithic columns represents their excellent permeability, which allows both working at high flow rates and injecting very high (in the range of 5%) sample concentrations. Monolithic column tolerate also extremely high molar mass samples (M>10,000 kg · mol−1). On the other hand, the mesopores (separation pores) of the tested monoliths exhibited rather small volume and wide size distribution. These shortcomings partially impair the permeability advantage of monoliths because in order to obtain high LC LC separation selectivity a tandem of several monolithic columns must be applied. Presence of large mesopores also reduces applicability of monolithic columns for molar masses below about 50 kg · mol−1 because VRs of polymers eluted behind the barrier are similar to that of freely eluting species. The non‐ negligible break‐thru phenomenon was observed for the very high polymer molar masses largely eluting behind the barrier. It is assumed that the fraction of very large mesopores present in the monoliths or association/microphase separation of macromolecules may be responsible for this phenomenon. This is why the presently marketed SiO2 monolithic columns are mainly suitable for the fast purification of the LC LC eluting macromolecules from the polymeric admixtures non‐hindered by the barrier‐forming liquid. Still, monolithic columns have large potential in the LC LCI and LC LCS procedures provided size (effective diameter) of the mesopores can be reduced and their volume increased.
Kinetics of Stable Free Radical Mediated Polymerization inside Submicron Particles
Authors: Tobita Hidetaka
Published: November 2007

Controlled/living radical polymerization systems in which the active period is extremely small, ϕA ≪ 1, such as the cases of stable free radical mediated polymerization (or nitroxide mediated polymerization) and atom transfer radical polymerization, are considered theoretically. The polymerization rate, Rp, for such systems increases by lowering the trapping agent concentration [X]. When the polymerization is conducted inside small particles, Rp decreases with D below the diameter Dp,SMC at which a single molecule concentration (SMC) is equal to [X]bulk. On the other hand, when the average number of trapping agents in a particle $\bar n_X$ is smaller than about 10, the fluctuation of nX among particles is significant, which leads to a larger Rp than in the cases where all particles contain the same nX. Because of the effects of SMC and fluctuation, Rp may show an acceleration window, Dp,SMC < Dp < Dp,Fluct where Rp is slightly larger than that in bulk.

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Identification of desulphoglucosinolates in Brassicaceae by LC/MS/MS: Comparison of ESI and atmospheric pressure chemical ionisation‐MS
Authors: Zimmermann Nadine S. , Gerendás Jóska , Krumbein Angelika
Published: November 2007

In order to develop a sensitive method for the detection of desulphoglucosinolates by HPLC‐MS, the two most common interfaces for HPLC‐MS, atmospheric pressure chemical ionisation (APCI) and ESI, were compared. While working with the APCI‐interface the evaporation temperature and corona amperage were optimised. In doing so 300°C and 6 μA proved to be most suitable for aliphatic and indole desulphoglucosinolates. The use of formic acid instead of water in the eluent in HPLC‐ESI‐MS measurements increased the sensitivity for the indole desulphoglucosinolates in the presence of 1 mM formic acid, while the sensitivity for the aliphatic desulphoglucosinolate desulphoglucoraphanin was substantially increased by the presence of 5 mM formic acid. Using an Agilent ion trap, two optimisation procedures for the MS parameters, smart and expert mode, were available. In smart mode the software optimises several parameters automatically, which is much more time efficient than expert mode, in which the optimisation is done manually. It turned out that ESI‐MS is most sensitive in smart mode, while for APCI‐MS a higher sensitivity could be gained using the expert mode. Comparing both interfaces, APCI‐MS was more sensitive than ESI‐MS. However, no additional information, in terms of structure determination, was obtained by APCI‐MS.
Apolipoprotein E genotype and alpha‐tocopherol modulate amyloid precursor protein metabolism and cell cycle regulation
Authors: Huebbe Patricia , Schaffer Sebastian , Jofre‐Monseny Laia , Boesch‐Saadatmandi Christine , Minihane Anne‐Marie , Müller Walter E. , Eckert Gunter P. , Rimbach Gerald
Published: November 2007

Apolipoprotein E4 (apoE4) genotype is associated with an increased risk for Alzheimer's disease (AD). This is thought to be in part attributable to an impact of apoE genotype on the processing of the transmembrane amyloid precursor protein (APP) thereby contributing to amyloid beta peptide formation in apoE4 carriers, which is a primary patho‐physiological feature of AD. As apoE and alpha‐tocopherol (α‐toc) have been shown to modulate membrane bilayer properties and hippocampal gene expression, we studied the effect of apoE genotype on APP metabolism and cell cycle regulation in response to dietary α‐toc. ApoE3 and apoE4 transgenic mice were fed a diet low (VE) or high (+VE) in vitamin E (3 and 235 mg α‐toc/kg diet, respectively) for 12 weeks. Cholesterol levels and membrane fluidity were not different in synaptosomal plasma membranes isolated from brains of apoE3 and apoE4 mice (–VE and +VE). Non‐amyloidogenic alpha‐secretase mRNA concentration and activity were significantly higher in brains of apoE3 relative to apoE4 mice irrespective of the dietary α‐toc supply, while amyloidogenic beta‐secretase and gamma‐secretase remained unchanged. Relative mRNA concentration of cell cycle related proteins were modulated differentially by dietary α‐toc supplementation in apoE3 and apoE4 mice, suggesting genotype‐dependent signalling effects on cell cycle regulation.
Shape reconstruction for the time‐dependent Navier‐Stokes flow
Authors: Yan Wen‐Jing , Ma Yi‐Chen
Published: November 2007

This article deals with the shape reconstruction of a bounded domain with a viscous incompressible fluid driven by the time‐dependent Navier‐Stokes equations. For the approximate solution of the ill‐posed and nonlinear problem we propose a regularized Newton method. A theoretical foundation for the Newton method is given by establishing the differentiability of the initial boundary value problem with respect to the interior boundary curve in the sense of the domain derivative. Numerical examples indicate the feasibility of our method. © 2007 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq, 2008
Production of superhydrophobic polymer fibers with embedded particles using the electrospinning technique
Authors: Menini Richard , Farzaneh Masoud
Published: November 2007

Superhydrophobic materials are currently used for their water‐repelling, self‐cleaning and anti‐fouling properties but are also potentially attractive to prevent snow or ice accumulation on exposed structures. Using the electrospinning technique, polymer mats made of polystyrene and poly[tetrafluoroethylene‐co‐(vinylidene fluoride)‐co‐propylene] (PTVFP) were prepared. They were found to show highly hydrophobic properties, water contact angle (CA) between 130 and 150°, when a dual fiber–bead microstructure was observed. Superhydrophobicity, CA > 150°, was reached when PTVFP mats were electrospun from a polymer solution containing dispersed polytetrafluoroethylene (PTFE) nanoparticles. Using atomic force microscopy imaging, protruding nanosized asperities on fiber and bead surfaces were observed and this structure led to superhydrophobic properties. Materials prepared from a high‐viscosity PTVFP/ethyl acetate solution with PTFE particles, 200 nm diameter and 8% (w/w), showed an 11.2% improvement in hydrophobicity, CA = 161°, compared to the materials obtained from a particle‐free polymer solution (CA = 143°). Copyright © 2007 Society of Chemical Industry
On the detection of shunts in silicon solar cells by photo‐ and electroluminescence imaging
Authors: Breitenstein Otwin , Bauer Jan , Trupke Thorsten , Bardos Robert A.
Published: November 2007

Recently electroluminescence (EL) and photoluminescence (PL) imaging were reported to allow detection of strong ohmic shunts in silicon solar cells. Comparing lock‐in thermography (LIT) images with luminescence images of various shunted cells, measured under different conditions, the ability of luminescence techniques for shunt detection is investigated. Luminescence imaging allows identifying ohmic shunts only if they reach a certain strength. The detection limit for PL measurements of linear shunts was estimated to be in the order of 15 mA at 0·5 V bias for a point‐like shunt in multicrystalline (mc) cells. Pre‐breakdown sites can also be detected by electroluminescence under reverse bias. Copyright © 2007 John Wiley & Sons, Ltd.
Preparation and characterization of monodisperse superparamagnetic poly(vinyl alcohol) beads by reverse spray suspension crosslinking
Authors: Yang Chengli , Guan Yueping , Xing Jianmin , Shan Guobin , Liu Huizhou
Published: November 2007

A novel protocol for preparing magnetic poly(vinyl alcohol) (PVA) beads by reverse spray suspension crosslinking was reported. The hydrophilic Fe3O4 nanoparticles were mixed with PVA, glutaraldehyde, and water to form aqueous phase. Then the aqueous phase was sprayed into vegetable oil by a pressure of nitrogen gas to form water in oil (W/O) suspension. The magnetic PVA beads were obtained in the presence of hydrochloric acid catalyst. It was found that the magnetic PVA beads obtained good properties when the PVA concentration was 10%, and the oil phase temperature was controlled at 40 °C. The mechanical stirring has little impact on the size of magnetic PVA beads in the process of reverse spray suspension crosslinking. The Cibacron Blue (CB) was coupled on the surface of magnetic PVA beads by surface chemical reaction. The morphology, size, and magnetic properties of the magnetic PVA beads were examined by scanning electron microscopy, laser diffraction, and vibrating sample magnetometer, respectively. Compared with the stirring method, it was found that the size of magnetic PVA beads was monodisperse and their saturation magnetization was much higher. Fourier transform infrared and X‐ray photoelectron spectroscopy experimental results proved that CB molecules were covalently immobilized onto the surface of the magnetic PVA beads. Meanwhile, the protein affinity separation experiments demonstrated that the magnetic PVA beads can potentially be used as a carrier for large‐scale protein separation. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 203–210, 2008
Design of Self Compensating Soft Loading Hood
Authors: McBride William , Ilic Dusan
Published: November 2007

This paper presents a design, and a design method, sufficient to engineer a passive solution to the problem of discharge bias resulting from tonnage fluctuation with soft loading transfer chutes. This is achieved by considering the momentum change inherent in the bulk material stream through the hood section of a soft loading transfer point. This momentum change is utilised to move the hood in a predefined path to ensure the discharge centroid remains consistent.

The majority of soft loading transfer points are between conveyor belts that include a plan view change in the material direction which immediately impacts on the design of the transfer point. This impact is, the designer must optimise the transfer for a narrow bandwidth of throughput to achieve optimal outcomes or else accept the potential for mis tracking on the receiving belt. This is due to variations in throughput tonnage altering the location of the discharged materials centroid from a fixed hood section, resulting in a tendency for the receiving belt to mistrack due to biased loading.
RAFT Nano‐constructs: surfing to biological applications
Authors: Boturyn Didier , Defrancq Eric , Dolphin Gunnar T. , Garcia Julian , Labbe Pierre , Renaudet Olivier , Dumy Pascal
Published: November 2007

Biologically programmed molecular recognition provides the basis of all natural systems and supplies evolution‐optimized functional materials from self‐assembly of a limited number of molecular building blocks. Biomolecules such as peptides, nucleic acids and carbohydrates represent a diverse supply of structural building blocks for the chemist to design and fabricate new functional nanostructured architectures. In this context, we review here the chemistry we have developed to conjugate peptides with nucleic acids, carbohydrates, and organic molecules, as well as combinations thereof using a template‐assembled approach. With this methodology, we have prepared new integrated functional systems exhibiting designed properties in the field of nanovectors, biosensors as well as controlled peptide self‐assembly. Thus this molecular engineering approach allows for the rational design of systems with integrated tailor‐made properties and paves the way to more elaborate applications by bottom‐up design in the domain of nanobiosciences. Copyright © 2007 European Peptide Society and John Wiley & Sons, Ltd.
Mutations in deoxyribonucleotide biosynthesis pathway cause spreading of silencing across heterochromatic barriers at the mating‐type region of the fission yeast
Authors: Singh Gurjeet , Klar Amar J. S.
Published: November 2007

The mat2,3‐region of Schizosaccharomyces pombe is flanked by two inverted repeat elements, IRL and IRR, which define the boundaries of the silent domain resulting from heterochromatin assembly in the region. We employed a genetic screen to isolate factors whose mutations allowed spreading of heterochromatin across boundary elements. Surprisingly, this screen revealed that mutations in the genes required for deoxyribonucleotide biosynthesis, cdc22 (encoding the large subunit of ribonucleotide reductase) and tds1 (putative thymidylate synthase), cause silencing of marker genes inserted outside of the silent domain. Chromatin‐immunoprecipitation analysis showed that histone H3 lysine 9 methylation modification, an epigenetic mark associated with gene silencing, is enriched by two‐ to three‐fold in the cdc22 mutant as compared to the level found in the wild‐type strain in regions outside the silent domain. The spreading of heterochromatin across barriers required functional Atf1/Pcr1, ATF‐CREB family proteins, but not the RNA‐interference Dcr1, Ago1, or Rdp1 factors, previously implicated in silencing. These results implicate the deoxyribonucleotide biosynthesis pathway in limiting epigenetic controls at barrier elements at the mating‐type region, but the mechanism remains unknown. Published in 2007 by John Wiley & Sons, Ltd.
Problem of crack perturbation based on level sets and velocities
Authors: Kovtunenko V.A. , Kunisch K.
Published: November 2007

We describe cracks with the help of a given velocity as zero‐level sets of a non‐negative function satisfying a transport equation. For smooth velocities this description is equivalent to the coordinate transformation of a domain containing the crack inside. Analytical examples of cracks described by smooth as well as discontinuous velocities are presented in 2D and 3D domains. Based on a level‐set formulation we consider the crack perturbation problem subject to a non‐penetration condition and derive the formula for the shape derivative.
Exhaust explained
Authors: Förster K.
Published: November 2007

The gasdynamic state of a plug of gas which was exhausted through a valve opened for a short time interval is quite inhomogeneous. In this paper a computational method based upon a onedimensional model is revived, and the complicated structure of the plug demonstrated in a realistic example.

Der gasdynamische Zustand eines durch ein kurzzeitig geöffnetes Ventil entwichenen Gaspfropfens ist ganz uneinheitlich. Die vorgelegte Arbeit berechnet diesen Zustand auf der Basis des bekannten eindimensionalen Modells und zeigt ein realistisches Beispiel.
A functional type a posteriori error analysis for the Ramberg‐Osgood model
Authors: Bildhauer M. , Fuchs M. , Repin S.
Published: November 2007

We discuss the weak form of the Ramberg‐Osgood equations (also known as the Norton‐Hoff model) for nonlinear elastic materials and prove functional type a posteriori error estimates for the difference of the exact stress tensor and any tensor from the admissible function space. These equations are of great importance since they can be used as an approximation for elastic‐perfectly plastic Hencky materials.
Physical Properties of Two Isomers of Conjugated Linoleic Acid
Authors: Uehara Hidetaka , Suganuma Tomomi , Negishi Satoshi , Uda Yukihiro , Furukawa Yoshinori , Ueno Satoru , Sato Kiyotaka
Published: November 2007

Thermal properties, powder X‐ray diffraction patterns and FT‐IR absorption spectra of crystals of two isomers of conjugated linoleic acid (CLA), 9‐cis, 11‐trans‐CLA (c9t11), 10‐trans, 12‐cis‐CLA (t10c12) were examined. To search for polymorphic modifications, we carefully performed crystallization from melt and solution phases, and isolated one type of crystalline form in c9t11 and t10c12. The melting temperature (Tm) was 14.9 °C, enthalpy of fusion (ΔH) was 38.7 kJ/mol, and entropy of fusion (ΔS) was 134 J/mol K for c9t11, and Tm = 19.8 °C, ΔH = 35.6 kJ/mol and ΔS = 122 J/mol K for t10c12. The X‐ray diffraction and FT‐IR measurements indicated O⊥ subcell packing in the crystals of c9t11 and t10c12, and long spacing values of 4.22 nm for c9t11 and 3.88 nm for t10c12. The unique molecular structures of the two isomers of CLA are discussed in comparison to the polymorphism of oleic acid, petroselinic acid, elaidic acid and linoleic acid, all of which are unsaturated fatty acids having the same carbon number of 18 as that of the two CLA isomers.
Chronic widespread musculoskeletal pain – A comparison of those who meet criteria for fibromyalgia and those who do not
Authors: Cöster Lars , Kendall Sally , Gerdle Björn , Henriksson Chris , Henriksson Karl G. , Bengtsson Ann
Published: November 2007

Fibromyalgia is currently classified as chronic widespread pain with widespread allodynia to pressure pain. There are few data describing pain characteristics, quality of life, consequences for daily living, and psychosocial status in patients who meet the classification criteria for fibromyalgia proposed by the American College of Rheumatology compared with patients with chronic widespread pain but not widespread allodynia.

This study used a randomly selected sample from the general population. A postal questionnaire and a pain mannequin were sent to 9952 people. The response rate was 76.7%. The pain drawings showed that 345 people had widespread pain; that is, they noted pain in all four extremities and axially. Clinical examination, which included a manual tender point examination, was performed in 125 subjects. These people answered commonly used questionnaires on pain, quality of life, coping strategies, depression, and anxiety.

Compared with chronic widespread pain without widespread allodynia, fibromyalgia was associated with more severe symptoms/consequences for daily life and higher pain severity. Similar coping strategies were found. Chronic widespread pain without widespread allodynia to pressure pain was found in 4.5% in the population and fibromyalgia in 2.5%.
Role of singlet oxygen in chloroplast to nucleus retrograde signaling in Chlamydomonas reinhardtii
Authors: Fischer Beat B. , Krieger-Liszkay Anja , Hideg Éva , Šnyrychová Iva , Wiesendanger Manuela , Eggen Rik I.L.
Published: November 2007

High light illumination of photosynthetic organisms stimulates the production of singlet oxygen by photosystem II and causes photooxidative stress. In Chlamydomonas reinhardtii, singlet oxygen also induces the expression of the nuclear‐encoded glutathione peroxidase homologous gene GPXH. We provide evidence that singlet oxygen stimulates GPXH expression by activating a signaling mechanism outside the thylakoid membrane. Singlet oxygen from photosystem II could be detected with specific probes in the aqueous phase of isolated thylakoid suspensions and the cytoplasm of high light stressed cells. This indicates that singlet oxygen can stimulate a response farther from its production site than generally believed.
Observed relationships between the Southern Annular Mode and atmospheric carbon dioxide
Authors: Butler Amy H. , Thompson David W. J. , Gurney Kevin R.
Published: November 2007

The authors examine the observed relationships between large‐scale climate variability and concentrations of atmospheric carbon dioxide (CO2) in the Southern Hemisphere. The results reveal that month‐to‐month variations in the rate of change of atmospheric CO2 at Palmer Station on the Antarctic Peninsula are significantly related to fluctuations in the dominant mode of Southern Hemisphere atmospheric variability, the so‐called Southern Annular Mode (SAM). A similar but weaker relationship between the SAM and atmospheric CO2 is evident at Syowa Station in eastern Antarctica, but not at the South Pole or stations located in Southern Hemisphere middle latitudes. Hence the SAM is most clearly related to fluctuations in atmospheric CO2 at locations that sample the westerly flow over the high latitudes of the Southern Ocean. Results based on CO2 flux estimates from the Atmospheric Tracer Transport Model Intercomparison Project (TransCom) suggest the observed relationships at least partially reflect the impact of the SAM on the flux of CO2 over the Southern Ocean.
Measurements of water vapor D/H ratios from Mauna Kea, Hawaii, and implications for subtropical humidity dynamics
Authors: Galewsky Joseph , Strong Mel , Sharp Zachary D.
Published: November 2007

Water vapor D/H ratios were measured from samples collected on Mauna Kea, Hawaii, in July 2006, and provide new constraints on the processes that control subtropical humidity. D/H ratios ranged from −88‰ at sea level to −321‰ on the summit of Mauna Kea, with sharply decreased D/H ratios above the trade inversion. A simple Rayleigh distillation model underpredicts the observed clear‐sky D/H ratios by as much as 160‰ at the summit. A model that accounts for large‐scale condensation, fractionation, mixing, and transport of water vapor, but ignores more detailed microphysical processes, is able to reproduce the first‐order characteristics of the clear‐sky free troposphere relative humidity and D/H ratios. These results are consistent with remote sensing studies of subtropical D/H ratios and suggest that subtropical clear‐sky water vapor isotopologues may be relatively insensitive to microphysical processes.
Chemical overprint on the natural remanent magnetization of a subtropical red soil sequence in the Bose Basin, southern China
Authors: Deng Chenglong , Liu Qingsong , Wang Wei , Liu Caicai
Published: November 2007

We present a high‐resolution paleomagnetic investigation of the subtropical red soil sequence at the Damei section, Bose Basin, southern China. Maghemite with low coercivities and fine‐grained hematite with high coercivities but relatively low unblocking temperatures were identified as main carriers of the natural remanent magnetization (NRM). Strong chemical weathering occurring under subtropical climatic conditions in southern China led to a chemical remanent magnetization (CRM) overprint that is sufficiently strong to mask the primary NRM. Analysis of the Bose Basin soil sequence indicates that the CRM has a large lock‐in depth (>4 m). This example shows that magnetostratigraphic studies on red soil sequences in subtropical‐tropical southern China should be interpreted with caution.
Explaining soil moisture variability as a function of mean soil moisture: A stochastic unsaturated flow perspective
Authors: Vereecken H. , Kamai T. , Harter T. , Kasteel R. , Hopmans J. , Vanderborght J.
Published: November 2007

Understanding soil moisture variability and its relationship with water content at various scales is a key issue in hydrological research. In this paper we predict this relationship by stochastic analysis of the unsaturated Brooks‐Corey flow in heterogeneous soils. Using sensitivity analysis, we show that parameters of the moisture retention characteristic and their spatial variability determine to a large extent the shape of the soil moisture variance‐mean water content function. We demonstrate that soil hydraulic properties and their variability can be inversely estimated from spatially distributed measurements of soil moisture content. Predicting this relationship for eleven textural classes we found that the standard deviation of soil moisture peaked between 0.17 and 0.23 for most textural classes. It was found that the β parameter, which describes the pore‐size distribution of soils, controls the maximum value of the soil moisture standard deviation.
Surface circulation in the Gulf of Cadiz: Model and mean flow structure
Authors: Peliz Alvaro , Dubert Jesus , Marchesiello Patrick , Teles‐Machado Ana
Published: November 2007

The mean flow structure of the Gulf of Cadiz is studied using a numerical model. The model consists of a set of one‐way nested configurations attaining resolutions on the order of 2.6 km in the region of the Gulf of Cadiz. In the large‐scale configuration, the entrainment of the Mediterranean Water is parameterized implicitly through a nudging term. In medium‐ and small‐scale nested configurations, the Mediterranean outflow is introduced explicitly. The model reproduces all the known features of the Azores Current and of the circulation inside the Gulf of Cadiz. A realistic Mediterranean Undercurrent is generated and Meddies develop at proper depths on the southwest tip of the Iberian slope. The hypothesis that the Azores Current may generate in association with the Mediterranean outflow (β‐plume theories) is confirmed by the model results. The time‐mean flow is dominated by a cyclonic cell generated in the gulf which expands westward and has transports ranging from 4 to 5 Sv. The connection between the cell and the Azores Current is analyzed. At the scale of the Gulf, the time‐mean flow cell is composed by the westward Mediterranean Undercurrent, and by a counterflow running eastward over the outer edge of the Mediterranean Undercurrent deeper vein, as the latter is forced downslope. This counterflow feeds the entrainment at the depths of the Mediterranean Undercurrent and the Atlantic inflow at shallower levels. Coastward and upslope of this recirculation cell, a second current running equatorward all the way along the northern part of the gulf is revealed. This current is a very robust model result that promotes continuity between the southwestern Iberian coast and the Strait of Gibraltar, and helps explain many observations and recurrent SST features of the Gulf of Cadiz.
Weekly cycle of aerosol‐meteorology interaction over China
Authors: Gong Dao‐Yi , Ho Chang‐Hoi , Chen Deliang , Qian Yun , Choi Yong‐Sang , Kim Jinwon
Published: November 2007

Weekly cycles of the concentration of anthropogenic aerosols have been observed in many regions around the world. The phase and the magnitude of these cycles, however, vary greatly depending on region and season. In the present study the authors investigated important features of the weekly cycles of aerosol concentration and the covariations in meteorological conditions in major urban regions over east China, one of the most polluted areas in the world, in summertime during the period 2001–2005/2006. The PM10 (aerosol particulate matters of diameter < 10 μm) concentrations at 29 monitoring stations show significant weekly cycles with the largest values around midweek and smallest values in weekend. Accompanying the PM10 cycle, the meteorological variables also show notable and consistent weekly cycles. The wind speed in the lower troposphere is relatively small in the early part of the week and increases after about Wednesday. At the same time, the air temperature anomalies in low levels are positive and then become negative in the later part of the week. The authors hypothesize that the changes in the atmospheric circulation may be triggered by the accumulation of PM10 through diabatic heating of lower troposphere. During the early part of a week the anthropogenic aerosols are gradually accumulated in the lower troposphere. Around midweek, the accumulated aerosols could induce radiative heating, likely destabilizing the middle to lower troposphere and generating anomalously vertical air motion and thus resulting in stronger winds. The resulting circulation could promote ventilation to reduce aerosol concentrations in the boundary layer during the later part of the week. Corresponding to this cycle in anthropogenic aerosols the frequency of precipitation, particularly the light rain events, tends to be suppressed around midweek days through indirect aerosol effects. This is consistent with the observed anthropogenic weather cycles, i.e., more (less) solar radiation near surface, higher (lower) maximum temperature, larger (smaller) diurnal temperature range, and fewer (more) precipitation events in midweek days (weekend).
HSP90 and eNOS partially co‐localize and change cellular localization in relation to different ECM components in 2D and 3D cultures of adult rat cardiomyocytes
Authors: Di Felice Valentina , Cappello Francesco , Montalbano Antonella , Ardizzone Nella Maria , De Luca Angela , Macaluso Filippo , Amelio Daniela , Cerra Maria Carmela , Zummo Giovanni
Published: November 2007

Background information. Cultivation techniques promoting three‐dimensional organization of mammalian cells are of increasing interest, since they confer key functionalities of the native ECM (extracellular matrix) with a power for regenerative medicine applications. Since ECM compliance influences a number of cell functions, Matrigel‐based gels have become attractive tools, because of the ease with which their mechanical properties can be controlled. In the present study, we took advantage of the chemical and mechanical tunability of commonly used cell culture substrates, and co‐cultures to evaluate, on both two‐ and three‐dimensional cultivated adult rat cardiomyocytes, the impact of ECM chemistry and mechanics on the cellular localization of two interacting signalling proteins: HSP90 (heat‐shock protein of 90 kDa) and eNOS (endothelial nitric oxide synthase).

Results. Freshly isolated rat cardiomyocytes were cultured on fibronectin, Matrigel gel or laminin, or in co‐culture with cardiac fibroblasts, and tested for both integrity and viability. As validation criteria, integrity of both plasma membrane and mitochondria was evaluated by transmission electron microscopy. Cell sensitivity to microenvironmental stimuli was monitored by immunofluorescence and confocal microscopy. We found that HSP90 and eNOS expression and localization are affected by changes in ECM composition. Elaboration of the images revealed, on Matrigel‐cultured cardiomyocytes, areas of high co‐localization between HSP90 and eNOS and co‐localization coefficients, which indicated the highest correlation with respect to the other substrates.

Conclusions. Our three‐dimensional adult cardiomyocyte cultures are suitable for both analysing cell—ECM interactions at electron and confocal microscopy levels and monitoring micro‐environment impact on cardiomyocyte phenotype.
A novel motility pattern in quail spermatozoa with implications for the mechanism of flagellar beating
Authors: Woolley David M.
Published: November 2007

Background information. The spermatozoon of the quail (Coturnix coturnix L., var japonica) has a ‘9+2’ flagellum that is unusually long. When it moves in a viscous medium, near to the coverslip, it develops a meander waveform. Because of the high viscosity, the meander bends are static in relation to the field of view; bend propagation is therefore manifest as the forward movement of the flagellum through the meander shape. At the same time, the origin of the oscillation typically shifts proximally in a stepwise fashion. These movements have been analysed in the hope of contributing to the resolution of problems in flagellar mechanics.

Results. (1) Meander waves originate from spontaneous sigmoid bend complexes. (2) On a given flagellum, fully developed meander bends are uniform in their large angle, curvature and propagation speed; interbends can vary in length and shape. (3) No intra‐axonemal sliding is transmitted through formed bends; sliding related to new bends is accommodated proximally. (4) Sliding reversal is initiated at a threshold shear angle of approx. 1 rad. (5) The arc wavespeed is the product of the arc wavelength and the beat frequency. (6) Physical obstruction to bend development causes a pause in the oscillation. (7) New bend initiation can thus be dissociated from bend propagation on the distal flagellum. (8) The steps in the forward advance of the oscillation site occur during the early phase of bend growth.

Conclusions. (1) The main conclusion is that, in meander waves, the mechanical basis of the oscillation appears to be that the propulsive thrust arising from bend propagation acts as a bending stress to trigger sliding reversal, thus perpetuating the rhythmic beating. (2) Oscillations can originate at any position, provided the position is distal to a location where doublet sliding is restrained. (3) Meander waves are an example of new bend development without ‘paradoxical’ classes of sliding.
Identification of a bipartite focal adhesion localization signal in RhoU/Wrch‐1, a Rho family GTPase that regulates cell adhesion and migration
Authors: Ory Stéphane , Brazier Hélène , Blangy Anne
Published: November 2007

Background information. Rho GTPases are important regulators of cytoskeleton dynamics and cell adhesion. RhoU/Wrch‐1 is a Rho GTPase which shares sequence similarities with Rac1 and Cdc42 (cell division cycle 42), but has also extended N‐ and C‐terminal domains. The N‐terminal extension promotes binding to SH3 (Src homology 3)‐domain‐containing adaptors, whereas the C‐terminal extension mediates membrane targeting through palmitoylation of its non‐conventional CAAX box. RhoU/Wrch‐1 possesses transforming activity, which is negatively regulated by its N‐terminal extension and depends on palmitoylation.

Results. In the present study, we have shown that RhoU is localized to podosomes in osteoclasts and c‐Src‐expressing cells, and to focal adhesions of HeLa cells and fibroblasts. The N‐terminal extension and the palmitoylation site were dispensable, whereas the C‐terminal extension and effector binding loop were critical for RhoU targeting to focal adhesions. Moreover, the number of focal adhesions was reduced and their distribution changed upon expression of activated RhoU. Conversely, RhoU silencing increased the number of focal adhesions. As RhoU was only transiently associated with adhesion structures, this suggests that RhoU may modify adhesion turnover and cell migration rate. Indeed, we found that migration distances were increased in cells expressing activated RhoU and decreased when RhoU was knocked‐down.

Conclusions. Our data indicate that RhoU localizes to adhesion structures, regulates their number and distribution and increases cell motility. It also suggests that the RhoU effector binding and C‐terminal domains are critical for these functions.
Non-Born-Oppenheimer molecular dynamics of Na⋯FH photodissociation
Authors: Jasper Ahren W. , Truhlar Donald G.
Published: November 2007

The accuracy of non-Born-Oppenheimer (electronically nonadiabatic) semiclassical trajectory methods for simulations of “deep quantum” systems is reevaluated in light of recent quantum mechanical calculations of the photodissociation of the Na⋯FH van der Waals complex. In contrast to the conclusion arrived at in an earlier study, semiclassical trajectory methods are shown to be qualitatively accurate for this system, thus further validating their use for systems with large electronic energy gaps. Product branching in semiclassical surface hopping and decay-of-mixing calculations is affected by a region of coupling where the excited state is energetically forbidden. Frustrated hops in this region may be attributed to a failure of the treatment of decoherence, and a stochastic model for decoherence is introduced into the surface hopping method and is shown to improve the agreement with the quantum mechanical results. A modification of the decay-of-mixing method resulting in faster decoherence in this region is shown to give similarly improved results.
Spontaneous quasi single helicity regimes in EXTRAP T2R reversed-field pinch
Authors: Frassinetti L. , Brunsell P. R. , Drake J. R. , Menmuir S. , Cecconello M.
Published: November 2007

In recent years, good progress toward a better understanding and control of the plasma performance in reversed-field pinch devices has been made. These improvements consist both of the discovery of spontaneous plasma regimes, termed the quasi single helicity (QSH) regime, in which part of the plasma core is no longer stochastic, and of the development of techniques for active control of plasma instabilities. In this paper, a systematic study of spontaneous QSH in the EXTRAP T2R device [P. R. Brunsell, H. Bergsaker, M. Cecconello et al., Plasma Phys. Control. Fusion 43, 1457 (2001)] is presented. In this device, QSH states can occur spontaneously and it is associated with magnetic and thermal structures. A statistical analysis to determine the most favorable experimental conditions to have a transition to the QSH regime will be presented. The results described here are useful to understand the underlying properties of QSH regimes in view of future applications of the QSH active control in EXTRAP T2R; they are also important to have a comparison with the QSH studied in other devices.
Dielectric, piezoelectric, and ferroelectric properties of grain-orientated Bi3.25La0.75Ti3O12 ceramics
Authors: Liu Jing , Shen Zhijian , Yan Haixue , Reece Michael J. , Kan Yanmei , Wang Peiling
Published: November 2007

By dynamic forging during Spark Plasma Sintering (SPS), grain-orientated ferroelectric Bi3.25La0.75Ti3O12 (BLT) ceramics were prepared. Their ferroelectric, piezoelectric, and dielectric properties are anisotropic. The textured ceramics parallel and perpendicular to the shear flow directions have similar thermal depoling behaviors. The d33 piezoelectric coefficient of BLT ceramics gradually reduces up to 350 °C; it then drops rapidly. The broadness of the dielectric constant and loss peaks and the existence of d33 above the permittivity peak, Tm, show that the BLT ceramic has relaxor-like behavior.
A broadband laser plasma x-ray source for application in ultrafast chemical structure dynamics
Authors: Fullagar Wilfred , Harbst Michael , Canton Sophie , Uhlig Jens , Walczak Monika , Wahlström Claes-Göran , Sundström Villy
Published: November 2007

A plasma source free from characteristic emission lines is described, based on laser irradiation of a water jet in a helium atmosphere. Various key aspects of the laser interaction are presented along with practical characterization of the observed isotropic ∼4–10keV x-ray emissions, measurements of which indicate subpicosecond duration. Observations are consistent with a vacuum heating plasma mechanism at the helium-water interface and indicate strong potential for in-house ultrafast chemical structure dynamics application when coupled to contemporary detector developments.
Role of synthesis for oxygen defect incorporation in crystalline rubrene
Authors: Mitrofanov Oleg , Kloc Christian , Siegrist Theo , Lang David V. , So Woo-Young , Ramirez Arthur P.
Published: November 2007

Using photoluminescence characteristics at room temperature, we analyze incorporation of an oxygen-related defect, most likely rubrene peroxide, which produces an acceptor state in crystalline rubrene. Incorporation of rubrene-peroxide molecules can occur during the crystal growth as well as a result of the postgrowth oxidation, which depends on the presence of structural disorder.
High strength and high electrical conductivity in bulk nanograined Cu embedded with nanoscale twins
Authors: Zhang Y. , Li Y. S. , Tao N. R. , Lu K.
Published: November 2007

A bulk nanograined Cu sample embedded with nanoscale twins is produced by means of dynamic plastic deformation at cryogenic temperatures. It exhibits a tensile yield strength of 610MPa and an electrical conductivity of 95% IACS at room temperature. The unique combination of a high strength and a high conductivity is primarily attributed to the presence of a considerable amount of nanoscale twins which strengthen the material significantly while having a negligible influence on electrical conductivity.
Modification of local structures in multicrystals revealed by spatially resolved x-ray rocking curve analysis
Authors: Usami Noritaka , Kutsukake Kentaro , Fujiwara Kozo , Nakajima Kazuo
Published: November 2007

We show that spatially resolved x-ray rocking curve analysis can be a useful technique to investigate local structures in bulk multicrystals and their modification during crystal growth when combined with appropriate samples. For this purpose, a model crystal growth experiment was carried out using a Si seed crystal with artificially controlled ⟨110⟩ tilted grain boundaries. The growth orientation was chosen as the scan axis for rocking curve measurements in different crystal grains. Thanks to the superior angle resolution, the gradual structural changes can be monitored by the changes in the rocking curve profile such as the peak shift and the peak splitting. The amount as well as the sign of the peak shift was found to be strongly dependent on the initial grain boundary structure. Furthermore, the technique was applied to investigate local structures of Si multicrystals with controlled grain orientation grown without any seeds.
Dose dependence of x-ray luminescence from CaF2:Eu2+, Mn2+ phosphors
Authors: Chen Wei , Westcott Sarah L. , Zhang Jun
Published: November 2007

In CaF2:Mn2+, Eu2+, the emission from Eu2+ decreases while the emission from Mn2+ increases in intensity as the x-ray duration time increases. The decrease of Eu2+ emission is due to the oxidation of Eu2+ to Eu3+ upon x-ray irradiation, while the increase of Mn2+ emission in intensity is likely due to the breakdown of the forbidden transition by the defects. This phenomenon has potential for dose-dependent radiation detection because utilizing the ratio of the two emissions from Mn2+ and Eu2+ for radiation dosimetry is more sensitive and more reliable than using emission intensity change only.
Strategies and External Relationships of Small and Medium-Sized Enterprises in the US Agricultural Biotechnology Sector
Authors: Bagchi-Sen Sharmistha , Scully Jennifer
Published: November 2007

This paper examines the characteristics of small and medium-sized enterprises (SMEs) involved in the agricultural biotechnology (agro-bio) sector. Specific objectives are to understand firm-specific strategies utilized to remain competitive in an uncertain business environment, and to examine the impact of government/policy and farmers on strategies. The controversial nature of processes used and the ethical debate surrounding genetically modified organisms (GMOs) contribute to an ongoing struggle for these firms in negotiating their position in society as innovators. Data from surveys of US-based firms and farmers are used to show how firms respond to external conditions and how farmers adjust to the GMO controversy, and, in turn, affect the business of biotech. At first cut, the data suggest that firms are worried only about science; as the survey probes into firm-level evaluation of external actors, the importance of Federal over local – regional initiatives stand out. While states are investing to promote biotechnology clusters, the lack of perceived importance of state/local level efforts to innovators is of particular significance. The discussion also notes the disconnect between policymakers and SMEs. Farmers point out the indirect effect of public opinion in sustaining the business of agro-bio. This study raises questions about gaps in our understanding of the relationship among firms (innovators), users (farmers who are the traditional innovators), and the government (regulator – facilitator) in the agro-bio subsector of the biotech industry. The need to engage other partners (food companies, wholesalers, retailers, consumer groups) in understanding the prospect of agro-bio is evident.