bluuebunny/crossref_metadata_2025 huggingface dataset:
The Influence of Environment on Starch Content and Amylose to Amylopectin Ratio in Wheat
Authors: Labuschagne Maryke T. , Geleta Nemera , Osthoff Garry
Published: May 2007

There is evidence that starch content plays an active role in determining dough rheological characteristics. The aim of this study was to determine the influence of environment on starch content and amylose: amylopectin ratio, and how this affects breadmaking quality. Ten hard red spring wheat cultivars were planted in three different environments in a randomized complete block design with three replications. Total starch content, amylose: amylopectin ratio, milling, rheological and baking characteristics were measured. Starch content was significantly influenced by the environment. It was significantly negatively correlated with loaf volume, wet gluten content and flour protein content across the three environments. Starch content and protein content were significantly negatively correlated, yet the value was relatively small (r = −0.4) and the relationship was therefore not directly inverse, and other factors influenced this relationship. Some cultivars interacted with specific environments, and they ranked high for starch content and loaf volume. Amylose: amylopectin ratio was very consistent for the three environments but was not significantly correlated with breadmaking quality characteristics across the environments, although there were significant correlations at individual environments. Cultivar choice and environment where cultivars are planted will therefore affect the starch content. High starch content will not necessarily lead to poor baking quality.
Mechanical properties of (ethylene acrylate copolymer)‐modified polypropylene/TiO2 blends
Authors: Fan Xiyun S.
Published: May 2007

An ethylene‐(methyl acrylate) (EMA) copolymer produced from a tubular reactor was found to be effective in toughening polypropylene, even at low concentrations. The addition of a small amount of TiO2 pigment enhanced the EMA toughening effect. Microscopy and thermal analysis helped to reveal the possible EMA toughening mechanisms. The effects of two processing methods, dry blending and melt blending, on the mechanical properties of the formulation were also studied. J. VINYL ADDIT. TECHNOL., 13:65–70, 2007. © 2007 Society of Plastics Engineers.
Investigation of electrically conductive acrylonitrile‐butadiene rubber
Authors: Kim In
Published: May 2007

Electrically conductive acrylonitrile‐butadiene rubbers (NBRs) containing carbon black (CB) as conductive filler were prepared in order to investigate their electrical and mechanical properties. The effects of conductive CB loading, temperature, acrylonitrile content, crosslinking density of vulcanizates, and plasticizer on conductivity were studied. The change in electrical conductivity of NBRs with different amounts of CB showed that there is a certain critical point (percolation threshold) where a significant decrease in electrical resistivity (increase in conductivity) is observed. Mechanical properties such as tensile strength, elongation to break, and surface hardness of vulcanized NBRs were measured. It was found that the percolation threshold was 5 phr of CB for the NBR/CB composites. J. VINYL ADDIT. TECHNOL., 13:71–75, 2007. © 2007 Society of Plastics Engineers.
Mechanical and heat deflection properties of PVC/PMMA/montmorillonite composites
Authors: Pagé D.J.Y.S. , Cunningham N. , Chan N. , Carran G. , Kim J.
Published: May 2007

Composites based on PVC were compounded with 5% of montmorillonite and 10% of PMMA. Two types of reinforcement were studied, which included a purified sodium montmorillonite and a montmorillonite organically modified with an alkylammonium chloride. The composites were compounded with a Gelimat type thermokinetic mixer and were ejected at a maximum temperature of 180°C. The organically modified montmorillonite discolored the PVC, result which was interpreted as a sign of chemical degradation caused by the alkylammonium modifier. The composite made with 5% of purified montmorillonite and 10 of % PMMA displayed the best overall properties. The most important improvement was obtained on flexural strain at break (0.097–0.175 mm/mm) and maximum flexural strength (62–76 MPa). The HDT increased by up to 8°C. Dynamic mechanical analysis showed that 10% of PMMA in PVC moved the tan δ peak to temperatures 5–6°C higher. The PMMA was completely miscible in PVC and played an important role in the montmorillonite dispersion, as observed by XRD and SEM analysis. It also contributed to the overall increase in properties of PVC/PMMA/montmorillonite composites. J. VINYL ADDIT. TECHNOL., 13:91–97, 2007. © 2007 Society of Plastics Engineers.
Effect of precipitated calcium carbonate on the mechanical properties of poly(vinyl chloride)
Authors: Fernando N. A. S. , Thomas N. L.
Published: May 2007

This study examines the effect of various grades of precipitated and ground calcium carbonate on the tensile strength and Charpy impact energy of extruded PVC profile. The results confirm that ultra‐fine precipitated calcium carbonate (pcc) can give rise to large improvements in single notch impact strengths. Control values of 9 kJ/m−2 were increased to 79 kJ/m−2 through the addition of ultra‐fine pcc. The results have been interpreted in terms of the particle size, shape, and coating of the calcium carbonate grades and the effect on the gelation characteristics of the PVC formulations. J. VINYL ADDIT. TECHNOL., 13:98–102, 2007. © 2007 Society of Plastics Engineers.
Mitochondrial DNA Medicine
Authors: DiMauro Salvatore
Published: May 2007

The small, maternally inherited mitochondrial DNA (mtDNA) has turned out to be a hotbed of pathogenic mutations: 15 years into the era of ‘mitochondrial medicine’, over 150 pathogenic point mutations and countless rearrangements have been associated with a variety of multisystemic or tissue-specific human diseases. MtDNA-related disorders can be divided into two major groups: those due to mutations in genes affecting mitochondrial protein synthesis in toto and those due to mutations in specific protein-coding genes. Here we review the mitochondrial genetics and the clinical features of the mtDNA-related diseases.
The Effect of Local Corticosteroid or Ketorolac Exposure on Histologic and Biomechanical Properties of Rabbit Tendon and Cartilage
Authors: Shapiro Paul S. , Rohde Rachel S. , Froimson Mark I. , Lash Richard H. , Postak Paul , Greenwald A. Seth
Published: May 2007

Tendonitis, tenosynovitis, and the arthritides are clinical problems commonly encountered in daily orthopaedic practice. Systemic anti-inflammatories, physical therapy, and local corticosteroid injections all are used as nonoperative treatments of these conditions. Systemic anti-inflammatory agents and local corticosteroid agents, however, can be associated with adverse effects that render them intolerable to some patients. As a preliminary study assessing the feasibility of local injection of nonsteroidal anti-inflammatory medication, the histological and biomechanical effects of local exposure of rabbit cartilage and tendon to injectable steroidal (corticosteroid) and injectable nonsteroidal anti-inflammatory agents (ketorolac tromethamine, KT) were determined. Thirty rabbits underwent bilateral knee joint, patellar tendon, and Achilles tendon injections with either normal saline, corticosteroid, or KT. Mechanical and histologic evaluation of the tissues was performed at 6 and 15 weeks after injection. Gross tendon adhesions were observed in more corticosteroid-treated specimens than those exposed to normal saline or KT. Microscopic evaluation of tendons revealed no significant differences among the three groups. Mild cartilage degenerative changes were noted across all groups. Evidence of cartilage necrosis was noted for the corticosteroid-treated group only. Tendons exposed to corticosteroid or KT demonstrated increased load and energy to failure, but exhibited no difference in material stiffness or strain. The use of an injectable nonsteroidal anti-inflammatory agent may be safe and even pose less threat to local tissues after intra-articular and peri-tendinous administration.
Paracrine effects of direct intramyocardial implantation of bone marrow derived cells to enhance neovascularization in chronic ischaemic myocardium
Authors: Tse Hung‐Fat , Siu Chung‐Wah , Zhu Shu‐Guang , Songyan Liao , Zhang Qing‐Yong , Lai Wing‐Hon , Kwong Yok‐Lam , Nicholls John , Lau Chu‐Pak
Published: May 2007

Objective

To determine the optimal bone marrow (BM) cell types, and their potential mechanisms of action for neovascularization in chronic ischaemic myocardium.

Methods and results

The functional effects, angiogenic potential and cytokine expression of direct intramyocardial implantation of autologous BM CD31‐positive endothelial progenitor cells (EPC, n=9), BM mononuclear cells (MNCs, n=9), and saline (n=9) were compared in a swine model of chronic ischaemic myocardium. Autologous BM cells were harvested and catheter‐based electromechanical mapping‐guided direct intramyocardial injection was performed to target ischaemic myocardium. After 12 weeks, injection of BM‐MNC resulted in significant improvements in left ventricular dP/dt (+21±8%, P=0.032), left ventricular pressure (+17±4%, P=0.048) and regional microsphere myocardial perfusion over ischaemic endocardium (+74±28%, P<0.05) and epicardium (+73±29%, P<0.05). No significant effects were observed following injection of BM‐EPC or saline. Capillary density (1132±69 versus 903±44 per mm2, P=0.047) and expression of mRNA of vascular endothelial growth factor (VEGF, 32.3±5.6 versus 13.1±3.7, P<0.05,) and angiopoietin‐2 (23.9±3.6 versus 13.7±3.1, P<0.05) in ischaemic myocardium was significantly greater in the BM‐MNC group than the saline group. The capillary density in ischaemic myocardium demonstrated a significant positive correlation with VEGF expression (r=0.61, P<0.001).

Conclusion

Catheter‐based direct intramyocardial injection of BM‐MNC enhanced angiogenesis more effectively than BM‐EPC or saline, possibly via a paracrine effect, with increased expression of VEGF that subsequently improved cardiac performance of ischaemic myocardium.
State-Civil Society Cooperation and Conflict in the Spanish Empire: The Intellectual and Political Activities of the Ultramarine Consulados and Economic Societies, c. 1780–1810
Authors: PAQUETTE GABRIEL B.
Published: May 2007

This article analyses the intellectual and political activities of the newly-created consulados and Economic Societies in Spanish America between 1780 and 1810. It argues that these institutions decisively shaped both the formulation and implementation of metropolitan policy. Colonial elites used the consulados and Economic Societies as a vehicle to pursue licensed privilege and moderate, incremental reform in the context of a revivified, socio-economically stable Old Regime. They embraced the Bourbon reforms and used them to their advantage. Judging from consulado documents, the prevailing relationship between civil society and the state in Spanish America, at least until the late 1790s, was amicable and mutually supportive. After that time, mainly due to the disruption of Atlantic commerce, close co-operation gave way to conflict, but always within the framework of a cohesive empire. Drawing on archives in Argentina, Chile, Cuba and Spain, this essay traces the coalescence of numerous local intelligentsias that collaborated, to varying degrees, in the renovation of imperial governance and, simultaneously, incubated a robust public sphere in the nascent polities which gradually emerged after the collapse of Spanish royal authority in 1808.
Where Do Institutions Come From? Exploring the Origins of the Senate Blue Slip
Authors: Binder Sarah A.
Published: May 2007

Perhaps the most striking feature of the Senate's practice of advice and consent today is the deference accorded home state senators in reviewing presidential appointments to the federal bench. Although the Constitution calls for the advice and consent of the Senate body, informal norms of the Senate provide home state senators with a potential veto of nominations to fill federal judgeships within their states. One norm—senatorial courtesy—historically ensured that senators would defer to the views of the home state senator from the president's party. Another practice—the Senate “blue slip”—allocates special procedural rights to both home state senators regardless of political party. A single objection from a home state senator from either party has historically been considered sufficient to defeat confirmation of a nominee. The blue slip also allows home state senators to influence the course of nominations prospectively—encouraging presidents to heed the preferences of home state senators in selecting new federal judges.
Parallel Computation Approach for the Restoration of AFM Images
based on the Tikhonov Regularization Method
Authors: Stutz D. , Silva Neto A. J. , Cidade G. A. G.
Published: May 2007

This work proposes a parallel implementation for image restoration,
applied to biological images, obtained from an Atomic Force Microscope
(AFM) [1]. Depending on the scanning dimensions, any image obtained from
this technique can present either poor signal/noise ratios and blurred
contents. In order to restore or, at least, decrease the effects of such
degradations, image restoration methods are usually employed. The
algorithm of restoration is based on the use of the Tikhonov
methodology, described elsewhere, known here as the serial approach [2].
Unraveling the Architecture and Structural Dynamics of Pathogens by
High-Resolution in vitro Atomic Force Microscopy
Authors: Malkin A. J. , Plomp M. , Leighton T. J. , McPherson A. , Wheeler K. E.
Published: May 2007

Progress in structural biology very much depends upon the development
of new high-resolution techniques and tools. Despite decades of study of
viruses, bacteria and bacterial spores and their pressing importance in
human medicine and biodefense, many of their structural properties are
poorly understood. Thus, characterization and understanding of the
architecture of protein surface and internal structures of pathogens is
critical to elucidating mechanisms of disease, immune response,
physicochemical properties, environmental resistance and development of
countermeasures against bioterrorist agents. Furthermore, even though
complete genome sequences are available for various pathogens, the
structure-function relationships are not understood. Because of their
lack of symmetry and heterogeneity, large human pathogens are often
refractory to X-ray crystallographic analysis or reconstruction by
cryo-electron microscopy (cryo-EM). An alternative high-resolution
method to examine native structure of pathogens is atomic force
microscopy (AFM), which allows direct visualization of macromolecular
assemblies at near-molecular resolution. The capability to image single
pathogen surfaces at nanometer scale in vitro would profoundly impact
mechanistic and structural studies of Progress in structural biology
very much depends upon the development of new high-resolution techniques
and tools. Despite decades of study of viruses, bacteria and bacterial
spores and their pressing importance in human medicine and biodefense,
many of their structural properties are poorly understood. Thus,
characterization and understanding of the architecture of protein
surface and internal structures of pathogens is critical to elucidating
mechanisms of disease, immune response, physicochemical properties,
environmental resistance and development of countermeasures against
bioterrorist agents. Furthermore, even though complete genome sequences
are available for various pathogens, the structure-function
relationships are not understood. Because of their lack of symmetry and
heterogeneity, large human pathogens are often refractory to X-ray
crystallographic analysis or reconstruction by cryo-electron microscopy
(cryo-EM). An alternative high-resolution method to examine native
structure of pathogens is atomic force microscopy (AFM), which allows
direct visualization of macromolecular assemblies at near-molecular
resolution. The capability to image single pathogen surfaces at
nanometer scale in vitro would profoundly impact mechanistic and
structural studies of pathogenesis, immunobiology, specific cellular
processes, environmental dynamics and biotransformation.
Deposition of Lipid Bilayers with Atomic Force Microscopy
Authors: Tavares G. D. , de Oliveira M. C. , Vilela J. M. C. , Andrade M. S.
Published: May 2007

Biological membranes are constituted of lipids organized as a two
dimensional bilayer supporting peripheral and integral proteins,
providing a barrier between the inside and the outside of a cell [1].
Similar membranes can be prepared from the lipid mixtures forming
liposomes. The liposomes are multi or unilamellar spherical vesicles in
which an aqueous volume is enclosed and can be used to encapsulate some
drugs [2]. In order to better expose the details of their structure,
these membranes are generally deposited on the surface of a flat
substrate. These supported planar lipid membranes can also provide a
model system for investigating the properties and functions of the
complex cell membrane and membrane mediated processes such as
recognition events and biological signal transduction. Various methods
have been used to create artificial lipid membranes supported on a solid
surface, being the most used the Langmuir-Blodgett monolayers formation
[3], the vesicle fusion or liposome adsorption [4] and the solution
spreading [5].
Atomic Force Microscopy Applied to the Characterization of Solid Lipid Nanoparticles
Authors: Peixoto F. S. , Dias P. M. , Ramaldes G. A. , Vilela J. M. C. , Andrade M. S. , Cunha A. S.
Published: May 2007

Solid lipid nanoparticles (SLN) have generated increasing attention
as an alternative carrier system, particularly for lipophilic drugs
[1-2]. The system consists of lipid nanoparticles, which are solid at
room temperature. The solid matrix offers the possibility to improve the
stability against coalescence and the reduced mobility of incorporated
drug molecules is a pre requisite for controlled drug release [3].
Dexamethasone acetate was used as a model drug because of its wide
application in the pharmaceutical field and lipophilic properties.
Characterization of Liposomes Containing 5-Fluorouracil in
Hydrophilic Gel Using Atomic Force Microscopy
Authors: Azevedo E. G. , Ramaldes G. A. , Frézard F. , Vilela J. M. C. , Andrade M. S. , Ferreira L. A. M.
Published: May 2007

Actinic Kerarosis (AK) are hyperqueratotic cutaneous lesions, in
which an abnormal proliferation of keratinocytes of the epidermis is
present [1]. Since 1960s, topical 5-Fluorouracil (5-FU), a hydrophilic
antimetabolite drug, has been widely used as an effective treatment for
many pre-cancerous conditions and certain malignant tumors. However, the
severe inflammatory reaction, clinically characterized by erosion and
ulceration, which occurs in the skin following topical therapy, is still
a major treatment disadvantage. Topical delivery of hydrophilic drugs
through intact skin usually creates problems due to the inability of the
drugs to penetrate into stratum corneum. Liposomal formulations have
demonstrated capacity to increase penetration across and into skin of
these drugs when compared to conventional formulations [2]. Besides,
when applied on the stripped skin, in absence of barrier for drug
permeation, liposomes were found to provide targeted and sustained
topical delivery [3]. Thus, we hypothesized that liposomal formulation
containing entrapped 5-FU could be an interesting alternative for
topical treatment of AK. 5-FU encapsulation efficiency (EE) and
retention in liposomes are usually low (EE less than 10%). 5-FU does not
associate with the lipid bilayer [4] and EE depends mainly on the
internal aqueous volume of vesicles [5]. Therefore, EE has been greater
in large unilamellar vesicles (LUV) when compared to multilamellar
vesicles (MLV) and the physical state of the bilayer determines the
retention capacity of the vesicles [6]. Recently, MLV liposomes
containing 5-FU were prepared with high EE, but with an average vesicle
diameter of 5 m [7].
AFM In-Situ Characterization of Supported Phospholipid Layers
Formed by Vesicle Fusion
Authors: Munford M. L. , Lima V. R. , Vieira T. O. , Heinzelmann G. , Creczynski-Pasa T. B. , Pasa A. A.
Published: May 2007

Atomic force microscopy (AFM) is a powerful tool for direct
visualization of supported biological membranes [1]. Moreover, in-situ
AFM measurements permit investigations of biological phenomena in real
time and in physiological environments. In a previous work, we have
studied the morphology and stability of supported phospholipid layers
prepared by solution spreading (casting) on mica [2]. The images were
acquired in the contact or contact-intermittent modes and the samples
analyzed ex-situ just after solvent evaporation and after a hydration
step, and in-situ with immersion in a buffer solution. Contact-mode
imaging is less suitable for soft or weakly attached materials, since
the tip can often scrape or drag the membranes during scanning, a
disadvantage that can be overcome by applying intermittent methods.
However, studies have also demonstrated that by adjusting the operative
force it is possible to use contact-mode to obtain AFM images of soft
phospholipids layers [3]. In the present work, we applied successfully
in-situ AFM contact-mode to characterize phospholipid layers of
1,2-dimyristoyl-sn-glycero-3-phosphatitidylcholine (DMPC) and
1,2-dioleoyl-sn-glycero-3-phosphatidylcholine (DOPC), as well as a
binary mixture of these phospholipids. The supported membranes were
prepared on mica substrates by vesicle fusion method.
Morphology Dependence on Fluorine Doped Tin Oxide Film Thickness
Studied with Atomic Force Microscopy
Authors: Macedo A. G. , Cava C. E. , Canestraro C. D. , L. Contini  , Roman L. S.
Published: May 2007

Tin oxide (TO) or fluorine doped tin oxide (FTO) has been frequently
used as a transparent electrode in our organic opto-electronic devices
[1-3]. In general, these devices are fabricated in a sandwich structure
where an organic thin layer (approx. 100nm thick) stays between two
conducting electrodes, TO or FTO and Al. Due to higher conductivity FTO
is normally our choice. The morphology of the electrodes influences the
morphology of the organic layer, mainly when the deposition of the
organic layer is done electrochemically.
Characterization of PMMA/PVB Blend Films by Means of AFM
Authors: Almeida A. T. , Gliemann H. , Schimmel Th. , Petri D. F. S.
Published: May 2007

Polymer blends are of increasing interest in the field of surface
technology because they can be used to change or tailor the properties
of surfaces for special application. In most cases not only the chemical
nature of the components is important for the physical properties of the
blend but also the components distribution on the blend surface. This
distribution is strongly dependent on the adsorption energy of the
polymers onto the substrate. According to the Flory-Huggins theory, the
criterion for polymer miscibility in blends is that the average
interaction parameter for a binary mixture of polymers, 12, must be less
than a critical value cri, which is calculated from weight-average
degrees of polymerization of the two polymers [1]. This parameter also
describes the difference of the interaction energies between similar and
different monomers. During the spin coating process the system tries to
reach a state of low energy, indicating that the substrate surface and
the vapor phase influence the wetting and dewetting of the substrate by
the resulting polymer films. However, one should notice that spin-coated
film structure may not correspond to the equilibrium one due to the
rapid solvent evaporation during the spin coating process and to solvent
effects [2].
Morphological and Electrical Characterization of Ti and Zr
Sputter-Deposited Thin Films
Authors: Chinaglia E. F. , Oppenheim I. C.
Published: May 2007

Thin film morphology and electrical resistivity play an important
role in modern technologies. In particular, subcomponents fabricated by
Ti play an increasing role in microelectronic device technology as well
as in the biomedical area [1-2]. Here the influence of substrate
temperature (during deposition) and film thickness on the surface
morphology and electrical resistivity of polycrystalline Ti and Zr thin
films have been investigated.
Local Stiffness in Nylon 6/Rubber Blends Determined by Digital
Pulsed Force Mode-SPM
Authors: Segatelli M. G. , Costa C. A. R. , Galembeck F. , Goncalves M. C.
Published: May 2007

The incorporation of soft rubber into a thermoplastic matrix can lead
to tough blends. Generally, such binary blends are immiscible and
exhibit poor mechanical properties caused by the unfavorable
interactions between the two phases. Thus, there is an enormous interest
in polymer blend compatibility to improve the properties of the polymer
blends by the addition of an appropriate compatibilizer [1,2].
AFM Studies of Ni Electrodeposits on GaAs
Authors: Zoldan V. C. , Kirkwood D. M. , Zangari G. , Munford M. L. , Figueiredo W. , Pasa A. A.
Published: May 2007

In this study, the surface morphology of electrodeposited Ni on
single crystal GaAs (001) was investigated by atomic force microscopy
(AFM). The images show granular deposits with stepped contours typical
of single-crystalline grains. The correlation length correlates very
well with the size of the grains, indicating that the layers grow as
columns with diameter increasing with thickness. This growth mechanism
is observed for layers with thicknesses in the range of 10 to 500 nm at
a deposition rate of ~0.5 nm/s.
Welcome from the Society Presidents
Authors: Jerome Jay , Gauvin Raynald , Hetzner Dennis , Botton Gianluigi
Published: May 2007

WELCOME! On behalf of the Microscopy Society of America (MSA), the
Microbeam Analysis Society (MAS), the International Metallographic Society
(IMS), and the Microscopy Society of Canada/Société de
Microscopie du Canada (MSC/SMC), we invite scientists throughout the
world who develop and use microscopy to the jointly-sponsored Microscopy
and Microanalysis 2006 meeting in Chicago, Illinois. The meeting will take
place from July 30 through August 3, 2006. The venue for the meeting is
the exciting, and popular Navy Pier. The Program Committee, chaired by
Paul Kotula, has arranged a unique series of symposia and tutorials
covering both instrumentation and applications development as well as
sessions illustrating the practical uses of these developments in the
biological and physical sciences. As you look through this booklet, we
think you will agree that the Program Committee has put together a program
that will excite microscopists in all fields. The program features two
named Symposia. The first will be on “Cell Biology and
Microscopy” and is dedicated to the memory of Hans Ris and the
second will cover “Quantitative X-ray Microanalysis” and
honors Art Chodos. The program also has sessions celebrating the 50th
Anniversary of the Observation of Dislocations and the 50th Anniversary of
X-ray Mapping. Of course, an essential aspect of the scientific program is
your vital contributed paper! We encourage you to contribute your work for
presentation as part of this exciting program.
Sediment undulations on the Llobregat prodelta: Signs of early slope instability or sedimentary bedforms?
Authors: Urgeles Roger , De Mol Ben , Liquete Camino , Canals Miquel , De Batist Marc , Hughes‐Clarke John E. , Amblàs David , Arnau Pedro A. , Calafat Antoni M. , Casamor José L. , Centella Víctor , De Rycker Koen , Fabrés Joan , Frigola Jaime , Lafuerza Sara , Lastras Galderic , Sànchez Anna , Zuñiga Diana , Versteeg Wim , Willmott Verónica
Published: May 2007

A field of sediment undulations has been mapped by means of high‐resolution multibeam bathymetry and seismic reflection profiles in the Llobregat River prodelta, off the city of Barcelona, Catalonia, Spain. Similar features had previously been recognized in other prodelta environments and interpreted either as downslope sediment deformation or sedimentary structures induced by bottom currents or hyperpycnal flows. Since the study area is undergoing significant offshore development, proper interpretation of such sediment undulations is needed for a correct risk assessment. The occurrence of the sediment undulations is restricted to the prodelta front on slope gradients between 3 and 0.2°. The undulations have developed at the edge and atop an area of gas bearing sediments within the Late Holocene high‐stand mud wedge. An evaluation is made of the characteristics of the sediment undulations in order to determine the most likely process for the origin of these structures. Among these characteristics are the continuity of the reflections and lack of diffractions in between different undulations, their size distribution (large to small) both from shallow to deep and with depth in section, the asymmetry (decreasing from proximal to distal), the crest to trough vertical distance on the landward side of the undulations (up to 0.5 m), and the lack of features that could indicate a progressive movement such as growth structures and drag folds. These characteristics indicate that the sediment undulations on the Llobregat River prodelta do not result from sediment deformation but rather from the interaction of bottom currents generated by hyperpycnal flows from the Llobregat River with regional sea water circulation. Their identification as sediment waves implies that such features do not pose a major hazard for further offshore development.
Northern Hemisphere atmospheric blocking in ice core accumulation records from northern Greenland
Authors: Rimbu Norel , Lohmann Gerrit , Grosfeld Klaus
Published: May 2007

We investigate the connection between frequency of atmospheric blocking circulation and the variability of five high‐resolution accumulation records from northern Greenland. It is shown that during years of high ice accumulation records the frequency of winter blocking circulation in the Euro‐Atlantic region is significantly higher relative to the years of low accumulation. Our results show an enhanced Greenland storm track as well as enhanced moisture transport toward Greenland during the periods of high blocking activity relative to the periods of low blocking activity. The time series associated with the dominant mode of accumulation variability shows significant multidecadal variations during the last five centuries. We suggest that the positive (negative) phase of these multidecadal oscillations is related to high (low) blocking activity in the Euro‐Atlantic region.
Corotating high‐speed solar‐wind streams and recurrent cosmic ray modulation
Authors: Singh Y. P. , Badruddin
Published: May 2007

We studied the solar magnetic cycle dependence of cosmic ray depressions due to the corotating high‐speed solar wind streams (CSWS) during different polarity states of the heliosphere. The daily averaged cosmic ray intensity data from Climax, Oulu, and Thule neutron monitors together with simultaneous solar wind plasma and field data were subjected to the superposed epoch analysis with respect to CSWS start time. These analyses were carried out separately in different polarity states of the heliosphere A < 0 and A > 0 during solar minimum as well as during the periods of variable solar activity. Although the average variations in the solar wind velocity, IMF strength, and its variance are almost similar, the amplitudes of CSWS‐associated cosmic ray depressions are quite different during different polarity epochs; they are larger during A > 0 than A < 0 periods. Further, correlation analysis between cosmic ray intensity and solar wind velocity during CSWS shows differences in their relationship during A > 0 and A < 0; they are much better during A > 0 than A < 0. Two other solar wind parameters, IMF strength and its variance, do not show a significant relationship with cosmic ray intensity change through the passage of these streams, although the initial depression coincides the enhancement of the two parameters. These results are discussed in the light of existing models of galactic cosmic ray modulation.
A possible intrinsic mechanism for the quasi‐periodic dynamics of the Jovian magnetosphere
Authors: Kronberg E. A. , Glassmeier K.‐H. , Woch J. , Krupp N. , Lagg A. , Dougherty M. K.
Published: May 2007

Most regions of the Jovian magnetosphere covered by the Galileo spacecraft measurements undergo quasi‐periodic modulations with a time period of several Earth days. These modulations appear in various field and particle properties. Most prominent are periodically recurring ion flow bursts associated with disturbances in the meridional component of the magnetic field in the Jovian magnetotail or variations of the energy spectral shape of the particle distribution associated with the stretching and dipolarization of the magnetic field. Each individual cycle of these modulations is believed to represent a global reconfiguration of the Jovian magnetosphere. We present a simple conceptual model for these periodic processes assuming (1) ion mass loading from internal plasma sources and (2) fast planetary rotation causing magnetotail field line stretching due to centrifugal forces. This leads to a magnetotail configuration favoring magnetic reconnection. Magnetic reconnection causes plasmoid formation and release as well as dipolarization of field lines connected to the planet. Continued mass loading leads again to a stretching of the tail field lines. Our model shows that the suggested intrinsic mechanism can explain the observed periodicities of several days in Jovian substorm‐like processes.
Viscosity of the Earth's fluid core and torsional oscillations
Authors: Mound Jon , Buffett Bruce
Published: May 2007

Viscous effects on the temporal behavior and spatial structure of torsional oscillation normal modes of the Earth's fluid core are examined. If the viscosity of the fluid core is equal to that inferred from theoretical and experimental studies of liquid metals, then viscous effects on torsional oscillations are unlikely to be important; however, if the viscosity is as high as allowed from observational constraints, then Ekman layers at the fluid core boundaries may play an important role in damping torsional oscillations. The observationally inferred decay time of decadal torsional oscillations leads to an upper bound on the viscosity of the fluid core at the core‐mantle boundary of the order of 10−2 m2/s. A sufficiently large viscosity would result in torsional oscillation normal modes that undergo pure decay, as opposed to damped oscillatory motion. The viscosity value at which the temporal behavior switches between these regimes depends on the period of the normal mode. Numerical geodynamo models must reach an Ekman number of the order of 10−7 for free‐slip boundaries or 10−10 for no‐slip boundaries to accurately model the temporal behavior of decadal period torsional oscillations.
A new strategy for discrete element numerical models: 2. Sandbox applications
Authors: Egholm David Lundbek , Sandiford Mike , Clausen Ole Rønø , Nielsen Søren Bom
Published: May 2007

Here we present a series of numerical experiments using a new formulation of the discrete element method (DEM) that improves performance in modeling faults and shear zones. In the new method, named the stress‐based discrete element method (SDEM), which is introduced in the companion paper by Egholm, stress tensors are stored at each circular particle. Further, SDEM includes rotational resistivity of particles and elastoplastic constitutive rules for governing particle deformation. When combining these new features, the SDEM is capable of reproducing the friction properties of rocks and soils, without the need for the ad hoc calibration routines normally associated with DEM. In contrast to the conventional DEM, the friction properties of a SDEM particle system are in agreement with the Mohr‐Coulomb constitutive model with friction angles specified on a particle level. “Benchmark” sandbox models show that unlike most commonly used numerical methods, SDEM faults and shear zones develop at angles in agreement with general observations from structural geology and analogue modeling studies.
Fundamentally distinct outcomes of asteroid collisional evolution: Itokawa and Eros
Authors: Cheng A. F. , Barnouin‐Jha O. , Hirata N. , Miyamoto H. , Nakamura R. , Yano H.
Published: May 2007

The outcomes of asteroid collisional evolution are presently unclear: are most asteroids larger than 1 km size gravitational aggregates reaccreted from fragments of a parent body that was collisionally disrupted, while much smaller asteroids are collisional shards that were never completely disrupted? The 16 km mean diameter S‐type asteroid 433 Eros, visited by the NEAR mission, has surface geology consistent with being a fractured shard. The Hayabusa spacecraft visited an S‐asteroid smaller than 1 km, namely 25143 Itokawa. Here we report the first comparative analyses of Itokawa and Eros geology. Itokawa lacks a global lineament fabric, and its blocks, craters, and regolith are inconsistent with formation and evolution as a fractured shard, unlike Eros. Itokawa is not a scaled‐down Eros, but formed by a distinct process of catastrophic disruption and reaccumulation.
Fine tuning of coercivity in electrodeposited, Co-rich Co–Pt alloy films with perpendicular orientation
Authors: Xu X. , Weston J. , Zangari G.
Published: May 2007

We study the effect of applied current density j on the magnetic properties of Co-rich Co–Pt electrodeposited onto Ru(0001)∕Cu(111)∕Si(011). We find that varying j in the range of 10–100mA∕cm2 has a limited influence on film composition but has a strong effect on coercivity Hc. For example, Hc increases from 1600to4700Oe in 100nm thick Co–Pt films simply by increasing current density, providing an easily accessible parameter for the direct tuning of film coercivity. A higher current density increases nucleation density and consequently reduces grain size. It is hypothesized that the increased rate of side reactions at high j induces an increase in interface pH, affecting the hydrolysis equilibria in the electrolyte and leading to a variable incorporation of nonmagnetic matter that preferentially segregates at grain boundaries.
Effect of annealing temperature on exchange coupling in NiFe∕FeMn and FeMn∕NiFe systems
Authors: Chen Kuang-Ching , Wu Y. H. , Wu Kuo-Ming , Wu J. C. , Horng Lance , Young S. L.
Published: May 2007

Most studies on exchange bias in spin valves are for antiferromagnetic/ferromagnetic structures, and Fe[50]Mn[50]∕Ni[79]Fe[21] is widely used. The results of the exchange-bias field (Hex) and coercivity (Hc) as a function of the annealing temperature in NiFe∕FeMn and FeMn∕NiFe systems are given in the study. We prepare two types of films, type I: substrate/∕Ta∕NiFe∕FeMn∕Ta and type II: substrate/Ta∕FeMn∕NiFe∕Ta, respectively. Annealing was performed at 150–450°C under 720Oe for 2h, Hex and Hc of type I samples increase slightly with the increase of the annealing temperature. But Hex and Hc of type II samples increase rapidly after annealing over 300°C, then decrease after annealing at 375°C. The strong exchange-bias field and low coercivity were exhibited for type I samples, where NiFe is the buffer layer and is also the pinned layer. In type II samples, the increase in the exchange-bias field is attributed to the altered interface of FeMn∕NiFe due to interdiffusion. The interpretation of the fluctuation of the magnetic properties for these two types of films in connection with the crystalline texture and morphology by x-ray scattering technologies as well as atomic force microscopy was given. This research leads to a better understanding of the annealing temperature and microstructures in the two types of bilayers.
Exceptional magnetic properties of Fe substituted nickel chromite
Authors: Park Seung-Iel , Kim Chul Sung
Published: May 2007

The NiCr2−xFexO4, (x=0.1,0.3,0.5) samples have a cubic structure at room temperature. For the sample with x=0.1, the lattice constant is determined to be a0=8.319Å with a cubic spinel (Fd-3m) structure. The ferrimagnetic Néel temperature (TN) of NiCr2O4 is determined to be 80K by zero field cooled magnetization curves under the external field of 100Oe. With increasing Fe substitution, TN increases, and for x=0.1, TN is determined to be 135K. For the sample with x=0.1, the Mössbauer spectrum at 4.2K was fitted to two magnetic components of the magnetic hyperfine fields Hhf=488 and 472kOe and isomer shifts δ=0.29 and 0.28mm∕s. The electric quadrupole splittings (ΔEQ) were found to be nearly zero below the TN=135K. For the spectrum at 295K, the ΔEQ are observed with large values of 0.54 and 0.37mm∕s, respectively. The values of the isomer shifts show that for all temperature ranges, the states are ferric (Fe3+). The Mössbauer spectra below the TN show the line broadening with the Jahn-Teller distortion and accompanying relaxation effects, respectively.
Magnetic anisotropy in doped and undoped LiFePO4 single crystals
Authors: Chen D. P. , Wang Xiaolin , Hu Y. S. , Lin C. T. , Dou S. X. , Nigam R.
Published: May 2007

We report on the magnetic anisotropic properties of pure and Mg doped LiFePO4 single crystals grown by the traveling solvent floating zone technique. Our results reveal a considerable anisotropy in the susceptibilities along H‖a, H‖b, and H‖c for both crystals. LiFePO4 and Li0.99Mg0.01FePO4 crystals show antiferromagnetic long-range ordering below the Néel temperature of about 52K, with the b axis being the magnetic easy axis. The effective moments have been determined to be 6.18μB and 6.07μB for the pure and the doped crystals, respectively. These values are higher than what is expected on the basis of the spin-only value of 6.70μB with a high-spin d6 configuration for the Fe2+ ion.
Order-disorder transformations in Sm–Co and Sm–Co–ZrC systems with 2-17 stoichiometry
Authors: Kostogorova-Beller Y. Y. , Shield J. E. , Kramer M. J.
Published: May 2007

This work investigates the order-disorder transformations utilizing time-resolved x-ray diffraction at the Advanced Photon Source. The metastable phases that can form during the order-disorder transformations in the Sm–Co intermetallics have the potential to produce materials with enhanced permanent magnetic properties. The high-temperature experiments transformed the disordered alloys with the TbCu7-type structure obtained by rapid solidification into the mixture of the hexagonal and rhombohedral ordered structures at 1375K. The ordering process and the role of the ZrC alloying on the phase formation and ordering transformations were examined. The results showed the formation of shoulders of the fundamental peaks and superlattice peak broadening prior to complete ordering. The lattice parameters expanded linearly up to the onset of ordering, after which an abrupt change of slope was observed. The change in slope suggests a nucleation and growth mechanism for the ordering transformation. The effect of ZrC alloying promoted the formation of the disordered structure in the as-solidified state and lowered the onset of the ordering temperature.
Interpretation of ferromagnetic Fe doped ZnO by Mössbauer spectroscopy
Authors: Park Seung-Iel , Ahn Geun Young , Kim Chul Sung
Published: May 2007

Single phase Zn0.95Fe0.05O sample was obtained by the sol-gel method with annealing at 650°C for 6h in H2 5%/Ar balance gas atmosphere. The crystalline structure of Zn0.95Fe0.05O is determined to be a P63mc hexagonal structure with lattice constants a0=3.255Å and c0=5.207Å at room temperature. The Mössbauer spectra were obtained at various temperatures ranging from 4.2to295K. The values of the isomer shifts (δ) show that for all temperature ranges, they are in the ferrous (Fe2+) state. The magnetic hyperfine field (Hhf) and electric quadrupole splitting (ΔEQ) in the weak ferromagnetic state at 4.2K have been analyzed, yielding the following results: Hhf=37.8kOe, θ=67.5°, φ=0°, η=0.75, ΔEQ=2.06mm∕s, and R=7.4, respectively. From the Mössbauer spectrum at 77K, the paramagnetic quadrupole phase is related to the temperature dependence of spin-lattice relaxation.
Demagnetization protocols for frustrated interacting nanomagnet arrays
Authors: Wang R. F. , Li J. , McConville W. , Nisoli C. , Ke X. , Freeland J. W. , Rose V. , Grimsditch M. , Lammert P. , Crespi V. H. , Schiffer P.
Published: May 2007

We report a study of demagnetization protocols for frustrated arrays of interacting single-domain permalloy nanomagnets by rotating the arrays in a changing magnetic field. The most effective demagnetization is achieved by not only stepping the field strength down while the sample is rotating, but also by combining each field step with alternation in the field direction. By contrast, linearly decreasing the field strength or stepping the field down without alternating the field direction leaves the arrays with a larger remanent magnetic moment. These results suggest that nonmonotonic variations in field magnitude around and below the coercive field are important for the demagnetization process.
The influence of cobalt population on the structural properties of CoxFe3−xO4
Authors: Nakagomi F. , da Silva S. W. , Garg V. K. , Oliveira A. C. , Morais P. C. , Franco Júnior A. , Lima E. C. D.
Published: May 2007

Co x Fe 3 − x O 4 -based (x=0.05–1.6) nanoparticles prepared by combustion reaction were investigated using x-ray diffraction, Raman spectroscopy, and Mössbauer spectroscopy. The Mössbauer data revealed Co2+ in both tetrahedral (site A) and octahedral (site B) sites of the cubic ferrite structure. For x⩽0.4 the experimental data indicated the synthesis of a core-shell structure, with hematite as the shell and cobalt ferrite as the core of the nanoparticle. Differences in crystalline structure between the two phases support the evidences we found of a highly stressed core-shell interface, leading to symmetry reduction of the tetrahedral and octahedral sites.
Magnetic and magnetoelastic properties of Ga-substituted cobalt ferrite
Authors: Song S. H. , Lo C. C. H. , Lee S. J. , Aldini S. T. , Snyder J. E. , Jiles D. C.
Published: May 2007

Magnetic and magnetoelastic properties of a series of Ga-substituted cobalt ferrites, CoGaxFe2−xO4 (x=0.0–0.8), have been investigated. The Curie temperature TC and hysteresis properties were found to vary with gallium content (x), which indicates that exchange and anisotropy energies changed as a result of substitution of Ga for Fe. The maximum magnitude of magnetostriction decreased monotonically with increasing gallium content over the range x=0.0–0.8. The rate of change of magnetostriction with applied magnetic field (dλ∕dH) showed a maximum value of 3.2×10−9A−1m for x=0.2. This is the highest value among recently reported cobalt ferrite based materials. It was found that the dependence of magnetic and magnetoelastic properties on the amount of substituent (x) was different for Mn, Cr, and Ga. This is considered to be due to the differences in cation site occupancy preferences of the elements within the spinel crystal structure: Mn3+ and Cr3+ prefer the octahedral (B) sites, whereas Ga3+ prefers the tetrahedral (A) sites.