bluuebunny/crossref_metadata_2025 huggingface dataset:
Ultrasonic Evaluation of Severely Plastically Deformed Metals
Authors: Kozhushko Victor V. , Paltauf Günther , Krenn Heinz , Pippan Reinhard
Published: January 2011

Disc-shaped specimens of nickel and iron of about 30 mm diameter and a few millimeters thick were prepared by the high pressure torsion (HPT) method [1]. The produced equivalent shear strain ε linearly increased from a minimum at the centre to the periphery. The cold working process multiplied the dislocations and led to the grain fragmentation. The saturation of the grain refinement was approached at the circumference of the disk-specimens yielding a narrow distribution of the grain size with a mean value of about few hundred nanometers that depends on the material purity, temperature of the deformation [2]. The refinement of the microstructure changes the elastic properties of the material such as hardness, strength and has an influence on the attenuation and phase velocity of the ultrasound [3]. The paper reports the measurements of the longitudinal wave velocity and the attenuation in metals with polycrystalline (pc) and ultrafine (uf) microstructure.
Influence of Finish-Rolling Conditions on Microstructure and Mechanical Properties of Low-Alloy Mn-Ni-Cr-Mo Steel Grade
Authors: Kawulok Petr , Kawulok Rostislav , Schindler Ivo , Sojka Jaroslav , Kraus Martin , Čmiel Karel Milan , Legerski Miroslav , Rusz Stanislav
Published: January 2011

A physical simulation of the thermomechanical processing of the Mn-Ni-Cr-Mo low-alloy steel was performed in the laboratory rolling mill Tandem in the Institute of Modelling and Control of Forming Processes at VŠB – Technical University of Ostrava. The task was to determine the influence of the finish rolling temperature on the structural and mechanical properties of the rolled products. After different modes of rolling and slow cooling in the furnace, the final structure of the tested samples was in all cases composed of ferrite, bainite and islands of martensite. The finish rolling temperature markedly influenced a part by volume of the individual phases as well as the structure homogeneity. The results of the tensile tests at room temperature indicated that the studied steel did not show any pronounced dependence of the yield stress on the finish rolling temperature in the investigated range of values (750 – 1000 °C). On the other hand, the closely corresponding dependences of the ultimate tensile stress and elongation exhibited a considerable and very complex course, which can be explained mainly by the martensite fraction originating during the last stage of the final air cooling from temperature 600 °C.
On the Cutting Performance of Nano-(Tix,Al1-x)N PVD Coatings
Authors: Piska Miroslav , Dvořáček Jan , Sizová Alexandra , Sedlák Josef , Polzer Aleš , Forejt Miloslav
Published: January 2011

It is well known that hard coatings can extend the lifetime of production tools in many industrial applications significantly [1]. Higher cutting speeds, dry cutting or a better quality of machined surface can present the typical benefits of the protective surfaces so hard coatings receive a great interest from industrial and research organizations. Among the most important parameters of the coatings belong properties such as resistance to oxidation, thermal and abrasion, and good adhesion and tribological properties. The hard coatings based on (Tix,Al1-x)N prevails with unique properties belong to the most used coatings today. These coatings are deposited by PVD technology using either arc technologies or magnetron sputtering systems. New nanocomposite coatings (Ti,Al)N and (Ti0.4,Al0.6)N were tested in dry and wet cooling conditions and this paper deals with material analyses of the coating, testing of the cutting performance for a grooving technology in hardened low-alloyed steel.
Micromechanical Aspects of Transgranular and Intergranular Failure Competition
Authors: Dlouhý Ivo , Tarafder Mita , Hadraba Hynek
Published: January 2011

Quantification of characteristics that govern intergranular fracture initiation and propagation of this fracture micromechanism in competition with cleavage one is main aim of the paper. A NiCr steel of commercial quality and the same steel with an increased content of impurity elements, Sn and Sb, were used. Step cooling ageing was applied in order to induce intergranular embrittlement. Standard and pre-cracked Charpy type specimens were both tested in three-point bending to determine fracture toughness characteristics. In order to characterise the quantitative differences in fracture surfaces roughness a fractal analysis was applied. A boundary level of fractal dimension has been determined to be 1.12: fracture surface roughness with a higher value reflects high level of intergranular embrittlement and thus fracture resistance degradation.
Initiation and Growth of Short Cracks during Cycling in an Aged Superduplex Stainless Steel
Authors: Balbi M. , Hereñú S. , Proriol Serre Ingrid , Vogt Jean Bernard , Armas A.F. , Alvarez-Armas I.
Published: January 2011

The kinetics of short crack growth during cycling has been studied in a superduplex stainless steel in aged condition. After few cycles, slip lines appear distributed in both phases but the preferred phase for microcrack nucleation is the ferrite. Contrary to the exponential behavior observed in the as-received material, the growth rate of microcracks in aged condition follows a rather linear law. Internal dislocation structures were studied in the near surface region; microbands that sometimes extend over several grains were found at approximately 45º of the tensile axis on ferrite grains. The origin of the microbands has been analyzed and correlated with the microcracks.
Study of Fatigue Crack Growth and Threshold Values in an Inconel 718 - René 41 Weld at High Temperature and Low Load Frequency
Authors: Černý Ivo , Remar Luboš , Mikulová Dagmar
Published: January 2011

An evaluation of threshold values and fatigue crack growth (FCG) rates is a fundamental condition for an application of damage tolerance philosophy in numerous machinery components. This philosophy starts to be applied even in such problematic cases like aircraft engine blades. The paper contains results of an evaluation of FCG rates including threshold values in a heat resistant Inconel 718 / René 41 welds used in advanced manufacture processes of jet engine rotor blades. Measurement was performed at load asymmetry R = 0.05, temperature 700 oC, at low load frequency f = 0.3 Hz. Methodological approaches are mentioned. Results of FCG and particularly threshold values are discussed in connection with fractographical analyses. In addition, crack closure phenomenon and closure values are considered and discussed.
Effect of Temperature on the Cyclic Stress Components of Gamma - TiAl Based Alloy with Niobium Alloying
Authors: Petrenec Martin , Buček Petr , Kruml Tomáš , Polák Jaroslav
Published: January 2011

Cyclic strain controlled multiple step tests have been performed on cylindrical specimens of cast -TiAl based alloy with 2 at.% of Nb with nearly lamellar microstructure at 23 and 750 °C in laboratory atmosphere with the aim to study the effect of temperature on the internal and effective cyclic stress components. At these temperatures, the evolution of the effective and internal stress components and the effective elastic moduli were derived from the hysteresis loops analyzed according to the statistical theory of hysteresis loop. Cyclic hardening/softening curves and cyclic stress-strain curves were obtained at both temperatures. Cyclic stress–strain curves measured using short-cut procedure coincide with the basic cyclic stress-strain curve. They are shifted to lower stresses with increasing temperature. Cyclic stress-strain response at both temperatures was compared and discussed in relation to changes of internal and effective stress components and dislocation modes referred in literature concerning this class of the material.
Influence of Heat Treatment on Fatigue Crack Growth in Ti-6Al-4V Alloy
Authors: Rozumek Dariusz
Published: January 2011

The paper contains the results of experimental work carried out in order to analyse the initiation and propagation of fatigue cracks in Ti-6Al-4V titanium alloy. The tests were performed on plane specimens with the stress concentrators in form of one-sided sharp notches. The tested specimens were made of the oxygenated Ti-6Al-4V subjected to various variants of heat treatment.
Oscillation Marks and Hooks on the Surface of Concast Slabs and their Relation to Breakout
Authors: Stránský Karel , Kavička František , Sekanina Bohumil , Dobrovská Jana , Stetina Josef , Mauder T. , Masarik M.
Published: January 2011

In the secondary-cooling zone, where the slab is beginning to straighten out the breakout of the steel can occur in points of increased local chemical and temperature heterogeneity of the steel, from increased tension as a result of the bending of the slab and also from a high local concentration of non-metal, slag inclusions. Especially dangerous are the changes in the chemical composition of the steel during the actual concasting. In the case of two melts one immediately after the other, this could lead to immediate interruption in the concasting and a breakout. The material, physical, chemical and technological parameters, which both melts differed in were determined. If the dimensionless analysis is applied for assessing and reducing the number of these parameters, then it is possible to express the level of risk of breakout as a function of five dimensionless criteria.
Fracture Toughness of HVOF Sprayed Cermet Coatings Measured by Vickers Indentation
Authors: Houdková Šárka , Zahálka František , Kašparová Michaela
Published: January 2011

In the paper, the indentation fracture toughness of the HVOF sprayed WC-12%Co coatings is determined by the Vickers indentation test in dependence on used load. The relations, proposed by Chicot, were used to calculate the value of KIc at condition of the Palmqvist, Intermediate and Radial-median cracking mode. The applicability of using different equations is discussed with respect to the size indentation effect of IFT.
Mechanical Analysis of Multi-Textural Rocks (Brecciated Dolostones and Limestones): A New Micro-Compression Test for Rocks
Authors: Martínez Martínez Javier , Benavente David , García Del Cura Ángeles
Published: January 2011

Both strength and elastic modulus of rocks are usually determined by compression testing at the mesoscopic scale (UNE-EN 1926; ASTMD 3148-96), and the values obtained are representative of homogeneous rocks. However, heterogeneous and texturally complex rocks show a broad dispersion range and their strength and elastic modulus depend on the presence of different textures and their mechanical properties. The aim of this study was to quantify the mechanical behaviour of these textures individually in order to understand the strength and elasticity of the whole rock. Four varieties of brecciated carbonates (limestones and dolostones) were studied. These rocks have a very complex fabric, presenting a dense network of fractures and clasts between fractures (mm-cm size). The fractures are completely filled with calcite cement, and clasts can have one or two different textures, each presenting differences in crystal size, mineralogy and porosity percentage and type. Samples measuring 4x4x4 mm were obtained in order to test each texture individually. These micro-samples were tested in a uniaxial compression press and the stress-strain curve was recorded. In addition, mean strength and Young’s moduli were calculated for each texture. Results show that textures with a larger crystal size, lower porosity and intercrystalline porosity had the lowest strength and were the least elastic.
Effects of Hydrogen Concentration, Specimen Thickness and Loading Frequency on the Hydrogen Enhanced Crack Propagation of Low Alloy Steel
Authors: Kondo Yoshiyuki , Mizobe Koshiro , Kubota Masanobu
Published: January 2011

Crack propagation of SCM440H low alloy steel under varying load is enhanced by absorbed hydrogen. Substantial acceleration of crack propagation rate up to 1000 times was observed compared with that of uncharged material. The role of factors affecting enhanced acceleration was investigated by changing hydrogen concentration absorbed in metal, specimen thickness and loading frequency. Results are as follows. (1) 0.2 mass ppm diffusible hydrogen in metal was enough to cause enhanced acceleration. The predominant fracture mode showing acceleration was quasi cleavage. (2) In the case of thin specimen thinner than 0.8mm, the tri-axiality of stress is weak, and the enhanced crack propagation did not appear. However, the introduction of side-groove to 0.8mm specimen in order to increase the tri-axiality resulted in enhanced acceleration. (3) Lower loading frequency resulted in higher crack propagation rate in cycle domain. The crack propagation rate in time domain was almost constant irrespective of loading frequency. Enough concentration of hydrogen, tri-axiality and low loading frequency resulted in enhanced acceleration of fatigue crack propagation.
Progressive Fracture Evaluation in Composite Materials by Acoustic Emission Technique
Authors: Hajikhani Milad , Oskouei Amir Refahi , Ahmadi Najaf Abadi Mehdi , Sharifi Amir , Heidari Mohammad
Published: January 2011

Glass/polyester and glass/epoxy laminated composites widely used in structures and have very near properties. These composite laminates have poor inter-laminar fracture resistance and suffer extensive damage by delamination cracking when subjected to out of plane loading and hence are vulnerable to delamination. The presence of delamination in the composite material may reduce the overall stiffness. Structural design and nondestructive test techniques have evolved as increased emphasis has been placed on the durability and damage tolerance of these materials. There are several methods used to investigate damages of composite materials. Acoustic emission is one of these. In this work the effect of delamination propagation on acoustic emission (AE) events in glass/polyester and glass/epoxy composites is obtained also Fracture surface examinations were conducted using a scanning electron microscope (SEM) and results in these two common composites compared. Consequently, revealed that the AE technique is a practicable and effective tool for identifying and separating kinds of cracks in these composites.
Fatigue Testing of Thin Films
Authors: Burger Sofie , Rupp Benjamin , Ludwig Alfred , Kraft Oliver , Eberl Christoph
Published: January 2011

Thin film processing has been a driving technology in microelectronics and mechanics for years. The reliability of such devices is often limited by the failure of thin films. Therefore a deeper understanding of fatigue mechanisms of thin films through experiments is necessary to develop physical based lifetime models. Thus, this paper focuses on a novel setup for micro beam bending of thin metal films on Si cantilever substrate and first results will be presented.
Crack Behaviour in Polymeric Composites: The Influence of Particle Shape
Authors: Majer Zdeněk , Hutař Pavel , Knésl Zdeněk
Published: January 2011

In this paper polymeric particulate composites are studied (especially polypropylene (PP) matrix stuffed by rigid mineral fillers). Presently, polymeric particulate composites are frequently used in many engineering applications. The composite was modeled as a three-phase continuum – matrix, interphase and particle. The properties of the particles (size, shape) have a significant effect on the global behaviour of the composite. On the basis of fracture mechanics methodology the interaction of micro-crack propagation in the matrix filled by rigid particles covered by the interphase was analyzed. The effect of the composite structure on their mechanical properties is studied here from the theoretical point of view.
Transformation Paths in Transition-Metal Disilicides
Authors: Káňa T. , Šob Mojmír , Vitek V.
Published: January 2011

We suggest and investigate three possible displacive transformation paths between the ideal C11b, C40 and C54 structures in MoSi2, VSi2 and TiSi2 by calculating ab initio total energies along these paths. An estimate of transition temperatures based on the calculated energy barriers leads to values comparable with the melting temperatures of the disilicides studied. This confirms their high temperature stability and indicates that if a phase transformation between C11b, C40 and C54 structures of the disilicides takes place, then its prevailing mechanism should be diffusional rather than martensitic like. During the transformations studied, atoms come as close together as, for example, in configurations with interstitials. Hence, the present ab initio results can also help in fitting adjustable parameters of semi-empirical interatomic potentials for the transition-metal disilicides, in particular of the repulsion at short separations of atoms.
Microstructural Analysis during the Hydration of Cement-in-Polymer Coatings
Authors: Weichold Oliver , Hojczyk Markus , Adams Alina , Olaru Alexandra , Stanjek Helge
Published: January 2011

Cement-in-polymer (c/p) dispersions allow the full utilisation of the reinforcing abilities of multifilament rovings in concrete. In this work the role of the polymer properties on the performance of the c/p dispersions is investigated and discussed. Two model polymers are chosen and c/p dispersions made with these are investigated regarding the water ingress velocity (NMR), the phase development during cement hydration (XRD), and the microstructure after cement hydration (SEM). Best mechanical performance is achieved with the hydrophobic poly(vinyl acetate) which regulates the water ingress and causes a slow hydration of the cement.
Innovative Coating Technology for Textile Reinforcements of Concrete Applications
Authors: Glowania Michael , Gries Thomas , Schoene Jens , Schleser Markus , Reisgen Uwe
Published: January 2011

In the 60ties engineers started to combine short glass fibers with a concrete matrix. Today engineers combine endless fibers with the concrete matrix. Hence, the so called textile-reinforced concrete offers more and more opportunities to manufacture consumer goods like desks or chairs and to build face elements for houses and even load-bearing structures. This revolution is only feasible because a lot of research work has been done - into textile, into concrete, into the combination and the bonding. One big challenge still is to have a high bond between the fibers and the concrete to achieve high tensile strength. At the same time the reinforcement should be flexible to open a wide range of applications. The Institut für Textiltechnik and the Welding and Joining Institute of the RWTH Aachen University have spotted an innovative coating technology to achieve both – high tensile strength and drapability for textile-reinforcements for concrete applications.
Review on Indium Zinc Oxide Films: Material Properties and Preparation Techniques
Authors: Shyju G.J. , Dawn Dharma Roy S. , Sanjeeviraja C.
Published: January 2011

Thin films have become important for basic studies in physics and in many other fields. The immense interest in basic properties of thin films is due to considerable variations in their properties compared to those of the bulk material. Studies of the optical, electrical and magnetic properties, investigations of structural disorder and phase transition and of various surface phenomena are very much interest in research areas. The results obtained by research on basic studies are useful for the technical application of thin films. Thin films have greater deviations in their behavior corresponding to their original bulk materials. Because of small thickness certain physical features are observed such as optical interference, electronic tunneling through an insulating layer, high resistivity, low temperature coefficient of resistance, increase in optical magnetic fields and optical temperatures of superconductors. Material properties of indium zinc oxide thin films and all the techniques used to deposit thin films are summarized with an elaborative account along with our results.
Current Trends in the Application of Powder Injection Moulding
Authors: Ter Maat Johan , Cristea Claudia , Cojocaru Ovidiu
Published: January 2011

Powder Injection Moulding (PIM) is a fast-growing manufacturing method, providing a cost efficient production route to complicated steel parts in highly stressed mechanical applications, but also to polished steel and ceramic parts fulfilling the most stringent aesthetical demands of design-dominated consumer products. The marriage between the two technologies plastic injection moulding and powder sintering is providing a valuable synergy, leading to a very efficient production of high density sintered steel and ceramic parts with a complex geometry. Reliable sources for PIM granulate; the use of standard injection moulding machines and the availability of mature furnace technology have each contributed to the credibility of in particular the Metal Injection Moulding (MIM) technology and have enabled in recent years the launch of mobile phone and automotive mass productions. While typical MIM parts in mobile phones are small and weigh around 1 g, the number of parts required is impressive and may reach several millions of parts per month. MIM parts in engineering applications, including automotive, are typically 5 - 50 g and have the advantage of long-lasting production runs, in some cases already approaching 10 years. Ceramic Injection Moulding (CIM) is not yet in the same stage of development as MIM due to the niche character of ceramic materials. Complex ceramic parts are not yet very common, but are also starting to appear in all segments.
Milling Effects on Hybrid Collagen / Inorganic Phase Composites
Authors: Dindelegan George , Popa Cătălin , Brie Ioana , Magyari Karla , Simon Viorica
Published: January 2011

Phospho-silicate glass powder consisting of particles sized up to 60 micrometers was incorporated into insoluble collagen by mechanical milling. After 8 hours milling at 180 rpm, the two phases are still separated. Increasing of mill frequency at 1800 rpm led to glass particles encapsulation in the collagen matrix after 90 minutes. The collagen structural properties after mechanical bonding to glass powder particles are investigated by vibrational spectroscopy in order to emphasize the milling effects upon the protein secondary structure.
Metallic Foams Obtained from Nickel Based Superalloy Hollow Spheres
Authors: Vida-Simiti Ioan , Jumate Nicolaie , Bruj Emil , Sechel Niculina , Thalmaier György , Nemeş Dorel , Nicoară Mircea
Published: January 2011

In this work, hollow spherical nickel based superalloy powders obtained by liquid phase atomization were used. The obtained powder was divided into six size particle ranges between 200 µm and 630 µm using a shatter box. Samples from all six ranges were obtained by spreading the powder into the sintering die and consolidating them by sintering at 900°C and 1000°C for 30 minutes in vacuum (10-4 Torr). The metallic foams obtained by sintering hollow particles presents high porosity, and can be used as thermal barriers, catalyst support, shock absorbers or lightweight structural elements.
Studies Concerning the Microhardness of Sintered Carbon Steels Obtained from Fe and Fe3C Nanopowders
Authors: Ciobanu Mariana , Nicolicescu Claudiu , Bejan Simona , Batin Gabriel , Mercioniu Ionel
Published: January 2011

Replacing the graphite with carbides in the mixture with Fe powder may be an alternative technological process, by the fact that as carbides decompose when heated, the carbon is set free and diffuses into the Fe network ensuring chemical and structural homogeneity corresponding to sintered steels. Using cementite nanopowder mix with Fe powder is to ensure a better compaction by pressing, less time to decompose and C diffusion into the Fe network in a remarkably chemical homogeneity. The obtaining procedure for Fe3C consists in direct carburation of Fe powder in a special chamber.
Research on the Way of Obtaining the Parts of Sintered Powders by Injection Moulding
Authors: Brânduşan Liviu
Published: January 2011

For obtaining small parts with complex shape, for which a finishing operation cannot be applied easily, injection forming can be used. For a successful applying of this procedure not only the conditions of the injection process deployment must be taken into consideration, but also the conditions of the binder removal. These conditions impose, in a big measure, the feedstock characteristics, especially the ones of the binder used. The characteristics of the binder mixed with powder influence the injection process, the debinding process and the quality of the injected and sintered parts. Regarding that the binders used are formed from many components, it is very important to know the measure that each of them determines the rheological characteristics of the mixture. In the research made, a binder was used formed from polyethylene, paraffin and stearic acid, a binder which is often used to obtain mixtures for injection. It was watched how these components influence the binder characteristics, the injection process deployment and the effect they have on the quality of the debinded parts.
Improvement of Mechanical Properties of Fe-Cr-Mo-[Cu-Ni]-C Sintered Sintered Steels by Sinter Hardening
Authors: Dudrová Eva , Grande Marco Actis , Rosso Mario , Kabátová Margita , Bidulský Róbert , Hryha Eduard
Published: January 2011

The effect of high temperature sintering and high cooling rate on shifting the microstructural composition to the favourably of martensite-bainite structures and thus effective improvement of mechanical properties of sintered steels based on Astaloy CrL powder with an addition of 1 and 2% Cu or 50% Distaloy AB powder and 0.65% C was investigated. All the systems were processed by both sinter-hardening and conventional sintering. The vacuum sintering at high-temperature of 1240 0C and at common temperature of 1180 0C were integrated with high (6 0C/s), medium (3 0C/s) and slow (0.1 0C/s) cooling rates; conventional sintering at 1180 0C with cooling rate of ~0.17 0C/s was carried out in a N2+10%H2 atmosphere. In dependence on chemical composition, the yield and tensile strengths of 890-1150 MPa and 913-1230 MPa respectively and impact energy of 10-15 J were achieved by sinter-hardening. The yield and tensile strengths are approximately double than those resulting from conventional sintering.
Multiphysics Study of Structural Impact to Fluidic Media
Authors: Vesenjak Matej , Ren Zoran , Moatamedi Mojtaba
Published: January 2011

The paper presents a fluid structure interaction based numerical study of impact loading for a hemispherical structure upon water and a space capsule water landing. The study has a strong relevance in the determination of the crashworthiness of aerospace structures upon water impact loading. Finite element based numerical techniques have been used for the analysis of the underlying transient dynamic and fluid-structure interaction. Smoothed Particle Hydrodynamics (SPH) and Arbitrary Lagrange-Eulerian (ALE) methods have been used to simulate the behaviour of the fluid (water) under impact conditions. The accelerations and velocities of the impacting objects have been validated with by experimental measurements and analytical results. Numerical analyses showed a strong potential for the use of developed computational fluid structure interaction models for analyses of water impact loading related problems.
Newly Developed Unsteady Wave Sensing System for Polycarbonate
Authors: Hamashima Hideki , Hokamoto Kazuyuki , Yamashita Minoru , Sato Yasuhisa , Furukawa Takeo
Published: January 2011

Stress-strain relationships of polycarbonate (PC) were determined over a very wide range of strain rates including shock wave regime. High-velocity plate impact tests, drop-weight tests, and quasi-static tests using universal and Instron testing machines were used for the high strain rate (107 s-1), medium strain rate (102 s-1) and low strain rate (10-4 s-1) tests, respectively. The revised unsteady wave sensing system (UWSS) for plate impact tests was newly developed to determine the stress-strain relationships and Hugoniot linear relation of PC. The system consists of a powder gun for plate impact tests and three polyvenylidene fluoride (PVDF) gauges embedded in the PC utilizing a newly developed nanosecond UWSS. As originally proposed, UWSS is aimed in obtaining experimental inputs for the Lagrangian analysis used to determine the dynamic behavior of materials. The new method to determine also the shock Hugoniot stress-strain curves is proposed for PC at medium particle velocities up to about 1 km/s. The revised, unsteady wave sensing system (M-UWSS, which we proposed before) using plate impact experiment with three PVDF gauges embedded is applied to construct stress-strain curves under shock loading up to Hugoniot stress σH and Hugoniot strain εH. Linear relationship between shock velocity Us and particle velocity Up: Us = C0 + S x Up, where C0 and S are material constants, is used to determine the constant S, since the constant C0 is determined as bulk sound velocity at ambient pressure. By using the momentum conservation and the mass conservation relations, S = (1 - C0 / CH) /εH, is derived from the linear relationship described above, where , ρ is density and CH ≈ Us.
Generation of Ultrahigh Pressure and Application of Ultrahigh Pressure to Formation of Diamond from Graphite Powder
Authors: Kira Akio , Tsutsumi Yoshiaki , Tasaka Akio , Tomoshige Ryuichi , Hokamoto Kazuyuki , Fujita Masahiro
Published: January 2011

The purpose of our research is to generate the ultrahigh pressure by using high explosive and to transform a phase of a material. The extremely high impulsive pressure generator that has been developed by us uses the head-on collision between metal jets. Because the velocity of the metal jet is very high, the ultrahigh pressure will generate. If a powdered material is mixed to metal jets, it is expected that the material is transformed to a high pressure phase by this ultrahigh pressure. A graphite powder was used to synthesize a diamond. The existence of the diamond was confirmed by X-ray diffraction (XRD). In this paper, the mechanism of the generation of the ultrahigh pressure is explained and the results of the observation of the powder by using scanning transmission electron microscope (STEM) are reported.
Hot Explosive Compaction of Zinc Sulfide Based Electroluminescent by Double Cylinder Implosion Technique
Authors: Kennedy Greg , Tanaka Shigeru , Hayashi Y. , Kurihara M. , Hokamoto Kazuyuki , Itoh S.
Published: January 2011

Zinc sulfide is inorganic material for electroluminescent applications. This work examines the possibility of obtaining good luminescent properties of the zinc sulfide mixture by double implosion experiment at elevated temperature.
Modeling a Supersonic Solid State Detonation in an Overdriven Porous Mixture of Aluminum and Teflon
Authors: Yoo Sun Hee , Stewart Scott D. , Lambert David E.
Published: January 2011

In this paper, we demonstrate that an engineering device can be carefully designed in such a way that an overdriven solid state detonation can be initiated and propagated supersonically in a highly porous mixture of aluminum and Teflon. The equation of state and kinetics for the porous mixture are phenomenological models that were developed in our previous work [1]. This demonstration can be regarded as a good verification that the models which were used mainly in 1-D simulation are practically applicable and consistent to higher dimensional simulation of a shock dynamics in practical engineering devices.
The Opportunistic PathogenListeria monocytogenes: Pathogenicity and Interaction with the Mucosal Immune System
Authors: Schuppler Markus , Loessner Martin J.
Published: January 2011

Listeria monocytogenesis an opportunistic foodborne pathogen causing listeriosis, an often fatal infection leading to meningitis, sepsis, or infection of the fetus and abortion in susceptible individuals. It was recently found that the bacterium can also cause acute, self-limiting febrile gastroenteritis in healthy individuals. In the intestinal tract,L. monocytogenespenetrates the mucosa directly via enterocytes, or indirectly via invasion of Peyer’s patches. Animal models forL. monocytogenesinfection have provided many insights into the mechanisms of pathogenesis, and the development of new model systems has allowed the investigation of factors that influence adaptation to the gastrointestinal environment as well as adhesion to and invasion of the intestinal mucosa. The mucosal surfaces of the gastrointestinal tract are permanently exposed to an enormous antigenic load derived from the gastrointestinal microbiota present in the human bowel. The integrity of the important epithelial barrier is maintained by the mucosal immune system and its interaction with the commensal flora via pattern recognition receptors (PRRs). Here, we discuss recent advances in our understanding of the interaction ofL. monocytogeneswith the host immune system that triggers the antibacterial immune responses on the mucosal surfaces of the human gastrointestinal tract.
Formation of the 42-mer Amyloid Radical and the Therapeutic Role of Superoxide Dismutase in Alzheimer's Disease
Authors: Murakami Kazuma , Shimizu Takahiko , Irie Kazuhiro
Published: January 2011

Oxidative stress is closely involved in age-related diseases and ageing itself. There is evidence of the leading contribution of oxidative damage to neurodegenerative disease, in contrast to other diseases where oxidative stress plays a secondary role. The 42-mer amyloidβ(Aβ42) peptide is thought to be a culprit in the pathogenesis of Alzheimer's disease (AD). Aβ42 aggregates form the oligomeric assembly and show neurotoxicity, causing synaptic dysfunction. Aβ42 also induces tissue oxidation (DNA/RNA, proteins, and lipids) through trace metals (Cu, Zn, and Fe), which can be protected by antioxidant enzymes, vitamin C, and vitamin E. Superoxide dismutase catalyzes the conversion of toxic superoxide radical to less reactive hydrogen peroxide, contributing to protection from AD. Here we review the involvement of oxidative stress in AD progression induced from an imbalance between the radical formation of Aβ42itselftogether with unique turn structure at positions Glu22 and Asp23 and several defense systems.
Mitochondrial Dysfunction: The Road to Alpha-Synuclein Oligomerization in PD
Authors: Esteves A. R. , Arduíno D. M. , Silva D. F. F. , Oliveira C. R. , Cardoso S. M.
Published: January 2011

While the etiology of Parkinson's disease remains largely elusive, there is accumulating evidence suggesting that mitochondrial dysfunction occurs prior to the onset of symptoms in Parkinson's disease. Mitochondria are remarkably primed to play a vital role in neuronal cell survival since they are key regulators of energy metabolism (as ATP producers), of intracellular calcium homeostasis, of NAD+/NADH ratio, and of endogenous reactive oxygen species production and programmed cell death. In this paper, we focus on mitochondrial dysfunction-mediated alpha-synuclein aggregation. We highlight some of the findings that provide proof of evidence for a mitochondrial metabolism control in Parkinson's disease, namely, mitochondrial regulation of microtubule-dependent cellular traffic and autophagic lysosomal pathway. The knowledge that microtubule alterations may lead to autophagic deficiency and may compromise the cellular degradation mechanisms that culminate in the progressive accumulation of aberrant protein aggregates shields new insights to the way we address Parkinson's disease. In line with this knowledge, an innovative window for new therapeutic strategies aimed to restore microtubule network may be unlocked.
Aldosteronism and Resistant Hypertension
Authors: Acelajado Maria Czarina , Calhoun David A.
Published: January 2011

Resistant hypertension (RHTN) is defined as blood pressure (BP) that remains uncontrolled in spite of intake of ≥3 antihypertensive medications, ideally prescribed at optimal doses and one of which is a diuretic. The incidence of primary aldosteronism (PA) in patients with RHTN is estimated in prospective studies to be 14 to 23%, which is higher than in the general hypertensive population. Patients with PA are at an increased cardiovascular risk, as shown by higher rates of stroke, myocardial infarction, and arrhythmias compared to hypertensive individuals without PA. Likewise, RHTN is associated with adverse cardiovascular outcomes, and the contribution of PA to this increased risk is undetermined. Similar to PA, obstructive sleep apnea (OSA) is closely associated with RHTN, and a causal link between PA, OSA, and RHTN remains to be elucidated. The addition of MR antagonists to the antihypertensive regimen in patients with RHTN produces a profound BP-lowering effect, and this effect is seen in patients with or without biochemical evidence of PA, highlighting the role of relative aldosterone excess in driving treatment resistance in this group of patients.
Physical Inactivity and Mortality Risk
Authors: Kokkinos Peter , Sheriff Helen , Kheirbek Raya
Published: January 2011

In recent years a plethora of epidemiologic evidence accumulated supports a strong, independent and inverse, association between physical activity and the fitness status of an individual and mortality in apparently healthy individuals and diseased populations. These health benefits are realized at relatively low fitness levels and increase with higher physical activity patterns or fitness status in a dose-response fashion. The risk reduction is at least in part attributed to the favorable effect of exercise or physical activity on the cardiovascular risk factors, namely, blood pressure, diabetes mellitus and obesity. In this review, we examine evidence from epidemiologic and interventional studies in support of the association between exercise and physical activity and health. In addition, we present the exercise effects on the aforementioned risk factors. Finally, we include select dietary approaches and their impact on risk factors and overall mortality risk.
Formation water and gas analyses of the Beaufort-Mackenzie Basin
Authors: Grasby S E , Chen Z
Published: January 2011

Formation waters of the Beaufort-Mackenzie Basin, Arctic Canada, show a broad range of salinity and water chemistry. Three main water types are defined: freshwaters related to a gravity-driven flow system, original trapped seawater with minor diagenetic
alteration, and low TDS - high alkalinity waters. High alkalinity waters are isolated in overpressured fault blocks characterized by rapid sedimentation and burial. The high alkalinities (up to 9000 mg/l) are interpreted to be related to in situ CO2 generation through anaerobic methanogenesis
during burial.
Hydrocarbon potential of the Paleozoic succession of Hudson Bay / James Bay: preliminary conceptual synthesis of background data
Authors: Hamblin A P
Published: January 2011

The hydrocarbon potential of the lower Paleozoic succession of Hudson Bay region is currently poorly constrained and the area must be viewed as a frontier prospect. However, the location nearer to main markets than many frontiers is a significant positive
factor. Aside from a few wells and seismic in the 1970s, and concerted coal exploration in James Bay Lowlands, almost no serious oil and gas exploration has occurred in this region. Yet, in geological terms, the prospectivity is good. Oil and gas could reside in a wide variety of carbonate and
clastic plays of many different ages and styles: simple lack of knowledge makes petroleum system analysis very difficult until further data are generated. Many units in this under-studied succession are comparable to known productive zones in southwestern Ontario, but have had little testing of
play concepts or modern stratigraphic/sedimentological analysis. New geological study of stratigraphic architecture and correlation, lateral predictability of reservoir geometry, source, seals, maturation and migration, trap mechanisms, and generation of new play concepts would likely result in
significant potential for exploration success and economic impact.
Geological Survey of Canada paleontological age determinations in the Kananaskis west-half map area (NTS 82J), British Columbia and Alberta
Authors: McMechan M E , Norford B S , Bamber E W , MacDonald L
E , Uyeno T T , Nowlan G S
Published: January 2011

Paleontological age determinations for all known fossil collections (1348) identified by or collected by members of the Geological Survey of Canada in the Kananaskis west-half map area(NTS 82J) of British Columbia and Alberta are summarized in this GIS enabled
report. Age assignment, stratigraphic assignment and the location of the collections have been updated where necessary and feasible. Sample GIS enabled maps showing the distribution of fossil collections for 11 different geological periods are included. Paleontological age assignments of units with
economic interest can be easily searched and GIS maps generated from the data provided.
Holocene coastal reconstruction, Naikoon peninsula, Queen Charlotte Islands, British Columbia
Authors: Wolfe S A , Walker I J , Huntley D J
Published: January 2011

The Holocene coastal landscape of northeastern Graham Island, British Columbia is reconstructed from ca. 9.5 ka to present based on surfi cial geology and geomorphic mapping using light detection and ranging techniques, high-resolution aerial photographs and
ground truthing, and dating of coastal deposits using optical and radiocarbon dating methods. Six evolutionary phases are defi ned over the Holocene. A predominantly erosional shoreline, initially featuring steep, bluff-backed shorelines and river inlets, evolved into an increasingly depositional
coastal landscape with raised marine terraces, a northward-extending spit complex, and prograding lowland foredune and beach ridge systems. The modern system hosts an eroding shoreline backed by landward-migrating parabolic dunes and foredunes with localized erosional bluffs.

Shoreline reconstructions indicate a Holocene marine highstand of about 15.5 m a.m.s.l. at ca. 9.5 ka. By 5 ka, a deep embayment, acting as a depositional sink, was formed when Tow Hill joined the mainland which, in turn, initiated rapid progradation of North Beach. Since about 2.7 ka, rapid and
possibly accelerating rates of beach ridge and foredune progradation have occurred, coupled with extension of the Rose Spit complex. During this period, the 'East beach' shoreline eroded, removing evidence of past shorelines and older geomorphic features. Nearshore sediment transport has occurred
along both North Beach and East beach coupled with high eolian activity. West of Tow Hill, geoarcheological evidence dating to ca. 3.1 ka from atop a high bluff promontory may indicate a possible Haida occupation site at that time. Beach progradation has also occurred along this section of shoreline
in the last 3.0 ka, with Yakan Point becoming attached to the mainland by about 1.2 ka.
Structurally controlled iron oxide mineralization in the Iron Range Mountain and Mount Thompson region, British Columbia
Authors: Staples R D , Marshall D , Fecova K , Downie C C , Thorkelson D J , Loughrey L
Published: January 2011

Structurally controlled iron oxide alteration occurs within and along the Iron Range fault, a steeply west-dipping normal fault. Iron oxide alteration occurs as massive lenses, breccia infilling, and veins in a cataclastic quartz-albite breccia. Textures in thin
section suggest multiple episodes of magnetite, hematite, quartz, and pyrite growth. Fluid-inclusion studies indicate two dominant, twophase fluid-inclusion assemblages within predominantly quartz and albite, i.e. brine + H2O vapour and brine + CO2 vapour. Chlorite thermometry from six microprobe
analyses indicates temperatures of 275 to 325°C. The voluminous early sodic and relatively limited potassic alteration accompanied by ironoxide-rich and sulphide-poor alteration in the Iron Range deposit appears to be consistent with basinal brine fl uid-source models (with no magmatic
component) for iron oxide-copper-gold-type mineralization.
Neoproterozoic-(?)Cambrian lithostratigraphy, northeast Sekwi Mountain map area, Mackenzie Mountains, Northwest Territories: new data from measured sections
Authors: MacNaughton R B , Roots C F , Martel E
Published: January 2011

Three overlapping stratigraphic sections measured through previously undivided Neoproterozoic-Cambrian strata near Godlin River, northeast Sekwi Mountain map area (NTS 105 P) Northwest Territories, permit the succession to be subdivided in terms of established
formations. Strata in the upper Sheepbed Formation record gradational, upward transition from deep-marine mudrock into shallow-marine sandstone and siltstone. The overlying Gametrail Formation (100 m) is gradationally based, dominated by shallow-marine dolostone, and resembles other platformal
expressions of this unit. It is overlain erosionally by the Backbone Ranges Formation, which comprises a sandstone-dominated lower member (70 m), a middle member of thin-bedded carbonate (125 m), and a sandstone-dominated upper member (not measured). Contacts between members are poorly exposed, but
apparently abrupt. The members correspond well with those in the formation's type section in NTS 95 L. Southwestward correlation of these formations to their probable distal equivalents is controversial and remains challenging.
Historical changes in Cow Bay Beach, Halifax County, Nova Scotia
Authors: Taylor R B , Frobel D , Patton E
Published: January 2011

From the early 1900s to the 1950s, Cow Bay Beach, also known as Silver Sands Beach, was one of the largest and most popular recreational beaches near Halifax. As many as 5000 people would use the beach on a hot summer Sunday. Recreational facilities included
canteens, picnic sites, a merry-go -round and a dance hall. Only minor physical changes in the beach were observed during that period. By 1956, a commercial operation began extracting sediment from the beach for construction of the new airstrip at the nearby Shearwater airbase and for other
structures in the Halifax area. Trees were cut down. Power shovels and drag cranes worked along the shore, from west to east, to remove a total of nearly 2 million tons of sediment during the 1950s and 1960s. The resulting collapse of the western beach and expansion of the inlet allowed for the
transfer of large volumes of nearshore sediment into Cow Bay Lake. This lasted until at least 1974, when the inlet was nearly closed off again. Sediment excavation was stopped by the courts in 1971. Since the 1950s the 200 metre (m) wide beach with its multiple beach ridges covered by trees has
switched to a very low, single beach ridge less than 28 m wide. The seaward edge of the beach has migrated landward from 96 m to just over 200 m in fifty years. ln the process, the foundation of a dancehall, once at the back of the beach, is now seaward of it. After the excavations, the fragile
beach began slowly rebuilding until the late1980s. However, it was unable to withstand the impacts of storms during the mid-1990s and so it began migrating rapidly landward. By 2003, waves from Hurricane Juan had cut two channels through the beach, subdividing it into three parts. Since 2005, the
landward migration of the central section of beach has accelerated and will continue to do so unless the beach is flattened and submerged below high tide level by storms. If not, it will migrate and build against Moses Island, in Cow Bay Lake. Cow Bay Beach is a striking example of the long-term
impacts caused by sand and gravel removal from Nova Scotian beaches, during the post-World War Il construction boom. Beaches are the product of sediment accumulation over 100s and possibly 1000s of years. Sediment supply is therefore limited. Cow Bay Beach is also a reminder of the constant clash
between individual property owners rights, and the struggle to protect provincial shorelines for long term public benefits.