bluuebunny/crossref_metadata_2025 huggingface dataset:
Characterization of Defects in Severely Deformed Iron by Mechanical Spectroscopy
Authors: Akaki T. , Morimoto H. , Numakura Hiroshi , Terada Daisuke , Tsuji Nobuhiro
Published: January 2012

We have studied the crystal defects in severely deformed pure iron, by combining mechanical spectroscopy with measurements of Vickers hardness and electrical resistivity. Iron of 99.99% purity and a material in which the C content is further reduced to below 1 at. ppm were deformed to strains up to 5.6 by accumulated roll-bonding. Mechanical loss and dynamic shear modulus of as-deformed samples were measured over the temperature range from –195°C to 800°C. Effects due to dislocations and grain boundaries have been identified. Thermal stabilities of the defects have been examined through variations in the mechanical loss during heating-run and cooling-run measurements. It is found that the small difference in the carbon content influences the densities of defects and microstructure, as well as the thermal stability. They are consistent with the recovery behaviour observed through hardness and resistivity in isochronal annealing experiments.
Stress Relaxation Behavior of Cu-Ni-P Alloys Evaluated from Amplitude-Dependent Internal Friction
Authors: Aruga Yasuhiro , Morikawa Yoshiki , Tamaoka Satoshi , Nishino Yoichi
Published: January 2012

The strain-amplitude dependence of internal friction in Cu-0.41Ni-0.11P (mass%) alloys has been evaluated to reveal the relation between the amplitude-dependent internal friction and the stress relaxation performance. Annealing at 250°C after cold rolling causes a suppression of the strain-amplitude dependence with increasing annealing time in the range between 10 s and 104 s. Analysis of the amplitude-dependent internal friction reveals the plastic strain of the order of 10-9 as a function of effective stress on dislocation motion. It is found that the microflow stress at a constant level of plastic strain increases with increasing annealing time. This result is in line with the improvement in the stress relaxation performance but disagrees with a decrease in the tensile strength and yield stress after annealing. We believe that the increase in the microflow stress after annealing is caused by inhibition of dislocation motion due to Ni-P clusters, which were revealed by three-dimensional atom probe (3DAP) experiments.
Micro- and Macro-Plastic Properties of Be Polycrystals
Authors: Kardashev B.K. , Kupriyanov I.B.
Published: January 2012

The Young’s modulus and internal friction of Be polycrystals (grain sizes 6-60 μm) prepared with a powder metallurgy technique were studied acoustically in both amplitude independent and-dependent damping ranges. The measurements were made by composite oscillator at resonant frequencies of longitudinal vibrations of about 100 kHz in the temperature range of 100-873 K. The data were used to get information about micro-flow properties at vibration stresses of 0,2-30 MPa. It was found that the micro-flow diagrams became non-linear at amplitudes higher than 5 MPa. Mechanical properties (acoustic micro-flow stress σy, yield point σ0.2 and ultimate strength σВ) as functions of grain size have shown clearly a correlation in the framework of Hall and Petch law at room temperature but this similarity is not complete: stresses σ0.2 and σВ are one order of magnitude higher and change more steeply with grain size as compared to σy. The similarity is not observed for the temperature dependences. The values of σ0.2(Т) and σВ(T) decrease smoothly at higher temperatures but σу(Т) demonstrates an unusual minimum at ~400 K. The different behavior of the acoustic and mechanical stresses proves, evidently, that the ultrasonic energy losses and the flow stress level are due to the different nature of obstacles for the vibration (near equilibrium positions) and translation movement of dislocations in beryllium.
High Temperature Mechanical Spectroscopy Study of 3 mol% Yttria Stabilized Tetragonal Zirconia Reinforced with Carbon Nanotubes
Authors: Mazaheri Mehdi , Mari Daniele , Schaller Robert , Fantozzi Gilbert
Published: January 2012

Composites containing 3 mol% yttria stabilized tetragonal zirconia (3Y-TZP) reinforced with multiwalled carbon nanotubes (CNTs) with various amounts of CNTs (3Y-TZP / X wt% CNT, X= 0, 0.5, 1.5, 3 and 5) were processed by spark plasma sintering. Microscopic analysis proves that CNTs were well dispersed and embedded in grain boundaries of the sintered body. High temperature mechanical properties have been investigated using mechanical spectroscopy and low stress (6 MPa) creep. The isothermal spectrum (measured at 1600 K) consists of a mechanical loss peak at a frequency of about 0.1 Hz, which is superimposed on an exponential increase at low frequency. The absence of a well-marked peak in monolithic 3Y-TZP is justified considering that restoring force decreases at low frequencies or high temperatures due to the elasticity of neighboring grains. Therefore, strain is no more restricted and the mechanical loss increases exponentially, which is correlated to macroscopic creep. However, with CNT additions the mechanical loss decreases and a better resolved peak was observed. In parallel, the results have shown that the creep rate drastically decreases with CNT additions. These results can be interpreted by the pinning effect of CNTs which can hinder grain boundary sliding at high temperatures, resulting in a creep resistance improvement.
The Effect of Annealing on the Internal Friction in ECAP-Modified Ultrafine Grained Copper
Authors: Golovin Igor S. , Pal-Val P.P. , Pal-Val L.N. , Vatazhuk E.N. , Estrin Yuri
Published: January 2012

A detailed study of anelastic effects in submicrocrystalline copper using resonance (~70 kHz, 2 K to 320 K) and sub-resonance (0.05-100 Hz, 300 K to 675 K) techniques was carried out. Several relaxation processes were found in the temperature range of 2 K - 675 K: the relaxation loss peaks (Q-1) near 35 (P1) and 90K (P2) with the activation energy and the pre-exponential factor (H1≈ 0.02 eV,το1≈ 10-9s andH2≈ 0.09 eV,το2≈ 10-11s) similar to those of the Bordoni and the Niblett-Wilks peaks in coarse-grained Cu. This suggests that the peaks are due to the thermally activated motion of dislocation kinks in the primary and secondary Peierls relief. The mean values of activation parameters (H3≈1.4-1.6 eV,το3≈10-17s) of a third thermally activated peak (P3), which was significantly broadened, can be interpreted as a grain boundary peak with uncoupled activation parametersH3*≈0.45 eV andτο3*≈10-14s. A pseudo peak PRis associated with irreversible recrystallization processes. The influence of annealing on the observed effects is also discussed.
Mechanical Spectroscopy of Annealing Effects in Electrodeposited Nickel/Ceramic Nanocomposites
Authors: Sinning H.R. , Vidrich G. , Riehemann Werner
Published: January 2012

The annealing behaviour of temperature-dependent mechanical spectra (vibrating-reed technique) was studied on electrodeposited ultrafine-grained nickel as well as on Ni nanocomposites with small (7 nm) SiO2or larger (25 nm) Al2O3nanoparticles. From the response of the different phenomena involved – Young’s modulus, high-temperature damping background, dislocation-and hydrogen-induced low-temperature loss peaks, and magnetomechanical effects – information is obtained on processes such as recovery, grain growth, hydrogen trapping, and dislocation generation by thermal stresses, which are influenced by both kinds of nanoparticles in different ways.
Simulation of Mechanical Response in Nanoparticles
Authors: Kogure Yoshiaki , Kosugi T. , Nozaki T.
Published: January 2012

Morphology and mechanical resonse of copper nanoparticles with defects have been simulated by means of molecular dynamics simulation. The embedded atom method potential for copper was used to express the interaction of atoms. Four types of model samples were prepared and about 37,000 atoms were contained in each sample. Two of them are cubic shape with {100} surfaces, in which vacancies or interstitials are introduced. The other two samples are once melted and solidified particles with nearly spherical surfaces. The atomic structure is controlled by cooling rate, and crystalline and amorphous structures are realized. Shear and tetragonal strains are applied to the samples and stress-strain relations for the samples are derived. Mechanical damping and internal friction were evaluated from the free decaying oscillations by releasing static strains.
An Ultra-High Q Silicon Cantilever Resonator for Thin Film Internal Friction and Young's Modulus Measurements
Authors: Metcalf Thomas H. , Liu Xiao
Published: January 2012

An audiofrequency (8.5 kHz) cantilever resonator with an extremely low background internal friction (Q-1≈2×10-8) at liquid helium temperatures has been developed. Above 30 K, theQof the resonator is dominated by thermoelastic loss;Q-1is nearly exactly described by Zener’s formula for thermoelastic damping. Below 30 K,Q-1decreases monotonically with decreasing temperature, reaching a typical baseline ofQ-1=1.5×10-8at 400 mK.
Recent Investigations on Grain Boundary Relaxation
Authors: Kong Q.P. , Jiang W.B. , Cui P. , Fang Qian Feng
Published: January 2012

In recent years, we have investigated the grain boundary (GB) internal friction in high-purity Al bicrystals with a wide variety of misorientations of tilt and twist GBs. The main results are reviewed and divided into the following sections: (1) the origin of the GB internal friction peak; (2) the individual behaviors of different types of GBs; and (3) the coupling effect and compensation effect involved in GB relaxation.
Rhombohedral and Monoclinic Phases of PZT near the Antiferroelectric and the Morphotropic Boundaries
Authors: Cordero Francesco , Trequattrini Francesco , Craciun Floriana , Galassi Carmen
Published: January 2012

Anelastic and dielectric spectroscopy measurements are presented, which, together with previous measurements [1], clarify some controversial aspects of the phase diagram of PbZr1xTixO3close to the border with the antiferroelectric (AFE) phase, and at the morphotropic phase boundary (MPB). No evidence is found of a border separating monoclinic (M) from rhombohedral (R) phases, supporting recent structural studies according to which the two phases coexist, with the fraction of M prevailing near the MPB. A large frequency independent softening at the MPB indicates a genuine M phase over only finely twinned R phase. A new phase transition is found in both the anelastic and dielectric spectra atx= 0.1, at a temperatureTITbetween the Curie temperatureTCand the boundaryTTto the phases with tilted octahedra. Such a diffuse transition is interpreted as onset of disordered tilts, which finally become ordered belowTT. In this manner, the phase diagram of PZT is rationalised with respect to the common tendency of perovskites to undergo tilting when the mismatch between the cation sizes exceeds a threshold.
Phase Diagram of the Ferroelectric Perovskite (Na0.5Bi0.5)1−xBaxTiO3 by Anelastic and Dielectric Relaxation Measurements
Authors: Trequattrini Francesco , Cordero Francesco , Craciun Floriana , Mercadelli Elisa , Galassi Carmen
Published: January 2012

Anelastic and dielectric relaxation measurements have been carried out on poled and unpoled samples of the ferroelectric perovskite (Na0.5Bi0.5)1−xBaxTiO3(NBT-xBT), with composition in the range between pure NBT and the morphotropic phase boundary, 0 ≤x≤ 0.08. The complex elastic compliance spectra contain clear indications of both the rhombohedral/tetragonal and tetragonal/cubic transitions, allowing the determination of the phase diagram, which is difficult to obtain by diffraction techniques due to the very low distortions in both the tetragonal and rhombohedral phases and to the structural disorder in the Na/Bi sublattice. An extensive study is made for concentrations in the region of the morphotropic boundary (x∼ 0.06) in order to find possible signatures of monoclinic phase, as for the case of PbZr1-xTixO3(PZT). The main features in the anelastic curves are compared with those in the dielectric spectra and are tentatively related to different modes of octahedral rotations and polar cation shifts.
Ultrasonic Relaxation in Phase Transition Region in Ferroelectric Semiconductors of Sn2P2S6 Family
Authors: Samulionis Vytautas , Banys Juras , Vysochanskii Yulian
Published: January 2012

The paper presents recent results of ultrasonic investigation of Sn2P2S6 family ferroelectric crystals and their solid solutions in the temperature range 100-300 K. It was shown that in Sn2P2(S,Se)6 crystals the critical ultrasonic velocity slowing down for longitudinal waves propagating along main crystallographic directions is quite sharp and large. The relative change of longitudinal ultrasonic velocity along z-axis at the phase transition gradually increased from 10 % in pure Sn2P2S6 till 25 % for sample with 0.4 content of Se. Such large velocity change causes the large ultrasonic attenuation anomaly. The increase of relaxation time: τ=τ0/(TC-T) leads to the increase of attenuation. Prefactor τ0 was shown to be very small and the critical attenuation anomaly arises in the narrow temperature range close to phase transition. In the 0.4 Se sample the phase transition is of the first order because small thermal hysteresis exists. The ultrasonic velocity behaviour in the ferroelectric phase was described using Landau theory and free energy expansion including sixth order terms. For (Sn,Pb)2P2S6 system the critical ultrasonic anomalies were smaller and the phase transition temperature substantially decreased (for 0.45 Pb sample the phase transition point was at Tc =140 K). The ultrasonic anomalies at phase transition in (PbxSn1-x)2P2S6 have large hysteresis showing that transition is of the first order, far from the critical point.
Phase Transitions in Polymers for Lithium Batteries
Authors: Paolone Annalisa , Palumbo O. , Teocoli F. , Cantelli Rosario , Hassoun J.
Published: January 2012

The Young’s modulus and the elastic energy dissipation of polyethylene oxide (PEO)-based lithium battery electrolyte membranes have been studied in this work. The membranes, formed by pure PEO and doped by LiCF3SO3, Li2S and ZrO2, were studied within a 90 K - 400 K temperature range. We observed the glass transition around 230 K and the first-order phase transformation from the crystalline to the amorphous phase around 330 K on heating. We also measured the isothermal kinetics of the transition from the amorphous to the crystalline state and found that it is slower in doped PEO. Moreover, we showed that for both samples the transformation becomes slower as the temperature increases between 319 and 331 K. The experimental results suggest that the amorphous state is stable at 331 K for a few hours before the transformation takes place. Finally, the moisture effects on the mechanical properties of pure and doped PEO membranes are reported.
The Investigation of Internal Friction on Antiferromagnetic Transition and Martensitic Transformation in Mn-Fe(Cu) Alloys
Authors: Guo Zheng Hong , Rong Yong Hua , Gu S.Y. , Zhang Ji Hua
Published: January 2012

The internal friction and elastic modulus variations caused by the structural rearrangement fcc↔fct in Mn-Fe (Cu) antiferromagnetic alloys were studied in this paper. Antiferromagnetic transition exhibits weak first-order features due to the formation of microtwins by modulus softening mechanism. Antiferromagnetic transition also assists subsequent transformation to form twinned martensite. The small hysteresis between direct and reveres martensitic transformations indicates the thermoelastic feature. Both the martensitic and its reverse transformations also depend on the modulus softening mechanism.
Non-Affine Deformations at a Concentration Transition in Cross-Linked Elastomers in the Light of the 3D XY Spin Glass Model
Authors: Elnikova L.V.
Published: January 2012

X-ray and mechanical spectroscopy on liquid-crystalline elastomers give evidence of rubber elasticity, which depends upon the crosslink concentration. After applied macroscopic deformations, mesoscale non-affine deformations in these systems might lead to long relaxation times. Basing on the example of the crosslink-dependent smectic A − nematic (SmA−N) transition in polysiloxanes, we propose to use the three-dimensional Villain spin glass model and reduce it to the lattice version of the three-dimensionalXYspin-glass model. By using the Monte Carlo loop algorithm in this model, we found a percolation threshold depending on the crosslink concentration.
Mechanical Response of Bulk Metallic Glasses: Investigation by Mechanical Spectroscopy and Compression Tests - Elastic, Viscoelastic and Viscoplastic Components
Authors: Pelletier Jean Marc , Gauthier C. , Blandin J.J. , Gravier S.
Published: January 2012

The present paper addresses the mechanical behaviour of several bulk metallic glasses (BMG). Both small and large deformations are investigated, using mechanical spectroscopy and compression tests, respectively. In the case of a given BMG, the influence of temperature and strain rate (or frequency) on the mechanical response exhibits an attractive similarity when either small or large deformations are applied. Equivalence between temperature and time is clearly evidenced. The same behaviour is observed in many BMG, whatever their chemical composition, and therefore whatever their glass transition temperature. This behaviour is also very similar to that reported in other amorphous materials: polymers or oxide glasses. The same physical model enables a good description of this behaviour. It is based on atomic mobility and localized deformation in “soft” zones. nanocrystallization hinders strongly the atomic mobility and induces a drastic hardening at high temperature.
Alpha (Vitrea) Transition in Vulcanized Natural Rubber/Styrene Butadiene Rubber Blends Prepared by Mechanical and Solution Mixing
Authors: Mansilla M. A. , Ghilarducchi A.A. , Salva H.R. , Marzocca A. J.
Published: January 2012

The preparation method of an elastomeric blend can influence the mechanical properties of the vulcanized compound. In this research elastomeric blends composed by natural rubber and styrene butadiene rubber were mixed using two different methods: by mixing in a roll mill and by dissolution of both elastomers in toluene, mixing of both solutions with the curatives and the evaporation of the solvent. Samples with different Natural Rubber/Styrene Butadiene Rubber relation were prepared by both methods and vulcanized at 433K with a system based on sulphur and accelerator (N-t-butyl-2-benzothiazole sulfenamide) up to the time of optimum cure. The blend composition and the preparation methods have a strong influence in the mechanical dynamic properties. Scanning Electron Microscopy observations indicate that, in the blends prepared by the dissolution method, the samples show better miscibility of the constitutive phases than those prepared by the roll milling method. The temperature dependence of the internal friction was studied for each sample using a subresonant forced pendulum at 1 Hz between 190K and 250K. Depending on the blend composition, one or two glass transition temperatures (Tg) associated to the α-relaxation were measured. In the last case each Tgcorresponds to each elastomeric phase of the compound. The loss tangent data for each compound was analyzed using a mixture law of two phases in the frame of the Rouse theory. The adjustment of the data to the proposed model was very good for both preparation method and the whole composition range of the compounds. Then it was possible to obtain the Tg, the main relaxation time and the activation energy values of each compound and, in some samples, the respective values for each elastomeric phase.
Mechanical Spectroscopy Study on the Light Soaking Effect on Hydrogenated Amorphous Silicon
Authors: Mizubayashi H. , Sakata I. , Tanimoto H.
Published: January 2012

For hydrogenated amorphous silicon (a-Si:H) films deposited at temperatures between 423 K and 623 K (a-Si:H423Kand so on), the light-induced changes in the internal friction between 80 K and 400 K were studied. The internal friction is associated with H2motion in microvoid networks, and shows the mild temperature dependence between about 80 K and 300 K (Q-180-300K) and the almost linear increase above 300 K (Q-1>300K). BothQ-180-300KandQ-1>300Kdecrease with increasing the deposition temperature, and show the mild temperature dependence ina-Si:H623K. The white light soaking with 100 mW/cm2(WLS100and so on) below 300 K caused a change inQ-180-300Kand no changes inQ-1>300K, respectively, and the light-induced changes inQ-180-300Krecovered after annealing at 423 K. The wide distribution of activation energies for H2motions between microvoids indicate that most of neighboring microvoids are connected through windows, i.e., the microvoid networks are existing ina-Si:H, and the spatially loose or solid structures are responsible for the low or high activation energies for the H2motion between microvoids, respectively. Furthermore, the light-induced hydrogen evolution (LIHE) was observed for WLS200to WLS400in a vacuum between 400 and 500 K, resulting in the disappearance of the internal friction due to the H2motion in the microvoid network.
Mechanical Spectroscopy of Nanocrystalline Metals and Nanometer-Thick Films: Characteristic Properties Originated in Nanostructures
Authors: Tanimoto H.
Published: January 2012

Nanocrystalline (n-) Au shows a large internal friction accompanied with the modulus defects above ~200 K. After the creep test, the strong <111> preferred texture changed to rather random one but the mean grain size was unchanged.In situSTM observation indicated that the crystallites can independently move during the creep deformation. Quasi-two phase state composed of solid crystallites and anelastic/viscoelastic grain boundaries (GBs) is proposed to explain these characteristic mechanical properties ofn-Au. Further, GBs show the glass-transition-like change at around 200 K, anelastic/viscoelastic transition at ~30 MPa and dynamical state change above ~200 MPa. The high vacancy-type-defect concentration plays an important role on stabilization of the quasi-two phase state inn-Au.
Fluidized States of Vibrated Granular Media Studied by Mechanical Spectroscopy
Authors: Sellerio Alessandro L. , Mari Daniele , Gremaud Gérard
Published: January 2012

We investigate the jamming transition observed in vibrated granular systems composed of millimeter size glass beads. When a granular system is submitted to vibrations with decreasing intensity, it evolves in a way similar to glass-forming liquids: from a low viscosity, liquid-like state, it evolves into an amorphous jammed state. This evolution is observed by the means of an immersed oscillator acting as a torsion pendulum in forced mode. The complex susceptibility of the oscillator is measured as a function of the probe forcing frequency and of the vibration intensity. Focusing on the strongly vibrated states, we observe that there are two different dynamic regions. The first is a high fluidization regime, where the internal friction is found to be proportional to the ratio between the pulsation and the vibration intensity: . In this region, the system shows an apparent viscous friction . In the second, low fluidization, regime, we observe a more complex behavior, and the measured internal friction appears to be well described by a relation of the form: . In this second case, the key role is played by a critical breakaway stress, σcr, needed to break the network of chains of forces that form between the grains. Finally, if vibration intensities are still reduced, we also observe that onset of jamming is clearly distinguishable: we observe a sharp increase in the apparent dynamic modulus together with a peak in internal friction. This transition presents important similarities to those observed in glasses, and it leads to the second (low vibrations) regime, where the key role is played by the square root of the vibration intensity.
Nd60Fe30Al10 Glass Forming Magnetic Alloys: A Mechanical Spectroscopy Study at the 300-560 K Temperature Range
Authors: Salva H.R. , Ghilarducchi A.A. , Urreta S.E. , Fabietti L.M. , Levingston J.M.
Published: January 2012

The ferromagnetic amorphous phase in rapidly solidified Nd60Fe30Al10 glass forming alloys is investigated in melt spun ribbons (100 µm thick) and in chill cast cylinders (2 mm diameter). The amorphous resulting for these two different quenching rates were characterized by their room temperature hysteresis loops, magnetization and differential calorimetric measurements in the temperature range 300K-900K. The mechanical damping was explored in the 300-560 K temperature range, by measuring the internal friction and the shear modulus in a forced inverted pendulum operating in the frequency range 0.1-10Hz. Simultaneously, the electrical resistance of the samples was measured. The internal friction spectra of both, ribbons and a cylinder, exhibit a local maximum at about 500K, arising in a relaxation mechanism. After some thermal cycles the peak parameters stabilize reaching an apparent activation enthalpy of 1.5 eV and a limit relaxation time τ0 ≈ 0.4-2.5 . 10-17s. In both samples, the electrical resistance largely decreases during the first heating run to 560K and remains unchanged during subsequent thermal cycles. No changes in the elastic modulus or in the damping properties are detected at the Curie temperature of the alloys.
Mechanical Spectroscopy of Silicon as a Low Loss Material for High Precision Mechanical and Optical Experiments
Authors: Schwarz C. , Heinert D. , Haughian K. , Hofmann G. , Komma J. , Martin I. W. , Murray P. , Rowan S. , Seidel P. , Nawrodt R.
Published: January 2012

The paper summarises systematic studies of the mechanical loss of crystalline silicon at low temperatures from 300 to 5 K. Thermo-elastic loss is discussed as a main contribution in thin samples. A numerical method based on a finite element analysis is presented to determine the thermo-elastic loss of arbitrarily shaped samples. Additionally, mechanical loss associated with oxygen is investigated in Czochralski grown silicon bulk samples. The process has the activation energy of about 168 meV. An orientation dependency of the loss is observed. The lowest loss reported in this paper was achieved with a cylindrical bulk sample having a diameter of 110 mm and a length of 200 mm at around 5 K and a resonant frequency of about 22.3 kHz.
Magnetic Field Dependent Damping of Magnetic Particle Filled Polypropylene
Authors: Lambri O.A. , Gargicevich D. , Tarditti F. , Bonifacich F.G. , Riehemann Werner , Anhalt M. , Weidenfeller B.
Published: January 2012

The behavior of internal friction Q-1 and dynamic shear modulus has been studied in polypropylene charged with either different volume fraction or size of magnetite (Fe3O4) particles, as a function of the applied magnetic field at 318 K. An increase of the alternating (AC) magnetic field oscillating with 50 Hz, leads to an increase of the internal friction. In addition, during the subsequently decreasing alternating magnetic field, the internal friction decreases, but a hysteretic behavior appeared. In fact, the internal friction of the decreasing part of magnetic field amplitude is found to be smaller than during the previously increasing amplitude part of the treatment with the alternating magnetic field. Subsequent magnetic treatment cycles, lead to successively decreasing internal friction. In contrast, during the increase of a direct (DC) magnetic field, the internal friction decreases and the elastic modulus increases. The behavior of the internal friction and the elastic modulus during the application of an oscillating magnetic field (AC) is discussed on the basis of the development of both, a new zone with different rheological characteristics than the matrix but of the same material (self-inclusion), and/or a deteriorated or damaged zone (chain’s cuts) of the polymer matrix in the neighborhood of the magnetite inclusion. These effects are promoted by the movement or small relative rotation of the magnetite particles related to the surrounding matrix controlled by the oscillating field. The behavior of the internal friction and elastic modulus during the application of a direct (DC) magnetic field is discussed on the basis of the increase of the internal stresses into the polymer matrix due to the promotion of the magnetomechanical stresses.
Anelastic Phenomena in Human Dentin below Room Temperature
Authors: Amadori Stefano , Bonetti E. , Cappelloni Ilaria , Montanari Roberto
Published: January 2012

The work describes the anelastic behaviour of human dentin below room temperature. Human molars, extracted from individuals as part of their dental treatment, were cut to obtain bar-shaped samples for mechanical spectroscopy (MS) experiments. Repeated cooling-heating cycles in the range 300-100 K have been carried out on the same samples. In the cooling stage of the first cycle Q-1 exhibits a very broad maximum due to a series of phase transformations involving water present in the pores, in the interstices between fibres, between fibrils and inside collagen triple helix. The formation of ice Ih produces permanent damages to the dentin structure (rupture of fibres and fibrils) leading to a decrease of maximum intensity in the following cycles. In the heating stage of all the cycles two maxima, M1 and M2, have been observed around 155 K and 178 K. M1 is due to the transformation of low-density amorphous (LDA) ice into ice IC while M2 to that of ice IC to ice Ih. Above 200 K, Q-1 progressively increases with lower damping values in the cycles after the first one. Dehydrated samples do not exhibit the aforesaid anelastic phenomena confirming that their origin is connected to water and its transformations.
Effects of Alloying Elements on the Oxygen Snoek-Type Relaxation in Ti-Nb Alloys
Authors: Lu H. , Li Chun Xia , Yin Fu Xing , Fang Qian Feng , Umezawa Osamu
Published: January 2012

The effect of ternary alloying elements on the oxygen Snoek-type relaxation in the Ti-24Nb-2X-1.7O alloys (X = Al, Sn, Cr, Mn, Fe) was investigated. The dipole shape factor (δλ) of the Snoek-type relaxation was figured out for each ternary alloy based on the measured damping peak with the variable temperature. The value ofδλin the Ti-Nb-Al alloy was the highest among the present ternary alloys. It was found thatδλincreased with the decreasing lattice constant as well as the decreasing valence electron number per atom (e/a) and came to a maximum value when the e/a value was around 4.24, which defined the β phase boundary. Therefore, decreasing the lattice constants and the e/a value as largely as possible with alloying elements in the β-Ti alloys is one of the feasible ways to increaseδλand to design the high damping Ti alloys.
Internal Friction Study of Vacancy Hardening in B2 Fe Al Alloys
Authors: Nishino Yoichi , Ogawa Kazuya , Tanaka H.
Published: January 2012

nternal friction behaviour of B2 FeAl alloys has been examined to reveal the correlation of the microplasticity and thermal vacancies. The internal friction peak for Fe60Al40 appears at around 550 K, and the peak height increases with increasing quenching temperature. The curves of internal friction against the strain amplitude shift to larger strain amplitude as the quenching temperature increases. Analysis of the amplitude-dependent internal friction provides the plastic strain of the order of 10-9 as a function of effective stress on dislocation motion. It is found that the microflow stress at the plastic strain of 1×10-9 increases linearly with the square root of the net peak height. Remarkably, the microflow stress decreases with rising temperature but turns to increase above 500 K when measured after holding for 1 h at test temperatures. The anomalous increase in the microflow stress is caused by the creation of thermal vacancies at intermediate temperatures.
Quantitative Analysis of Carbon in Ferrite in Dual-Phase Steels by Mechanical Loss Measurements
Authors: Honda K. , Nakano K. , Numakura Hiroshi , Yokoi T. , Maeda D. , Yoshinaga Naoki , Ushioda Kohsaku
Published: January 2012

To establish the method for determining the amount of carbon in the ferrite phase in ferrite + martensite dual-phase low-alloy steels, mechanical loss measurements have been performed on a series of Fe–C alloys with varying constitution. The observed mechanical loss spectra of two-phase alloys turned out to be simple superposition of those of single phase alloys, of ferrite and of martensite. The concentrations of carbon in solution evaluated from the magnitude of the Snoek relaxation in the two-phase alloys agree well with those expected from the Fe–C phase diagram. It is thus possible to selectively analyse the carbon dissolved in the ferrite phase in the complex structure, at least in simple binary alloys.
Anelastic Relaxation Measurements in Nb-46wt%Ti Alloys with Interstitial Solutes in Solid Solution
Authors: Grandini Carlos Roberto , Florêncio Odila , Filho Walter José Botta
Published: January 2012

Anelastic relaxation measurements were performed in a Nb-46wt%Ti alloy, in the temperature range of 300 to 700 K, using a torsion pendulum operating at an oscillating frequency near 2.0 Hz. The samples were measured in different conditions: cold worked, annealed in ultra-high vacuum and doped with several quantities of nitrogen. The relaxation spectra obtained were resolved into their component peaks, corresponding to the different kinds of interaction of the interstitial solutes with the metallic matrix. The relaxation parameters of each process were calculated using Debye’s elementary peaks.
Oxygen Vacancy Relaxation in Ca3Co4O9+δ Ceramics
Authors: Lin G.C. , Liu H. , Zhang J.X.
Published: January 2012

Ca3Co4O9+δceramic powders were synthesized by the polymerized complex (PC) method. The same Ca3Co4O9+δceramic bar were treated in turn with three different processes of oxygen treatment: with no treatment, with oxydol (H2O2) treatment, and with N2treatment. Dynamic mechanical analysis (DMA) was performed from 123 to 623 K at rate of 1 K/min while the measuring frequencies are 0.05, 0.1, 0.25, 0.5, 1, 2, and 5 Hz. Two internal friction peaks are observed: one at the temperature range from 360 to 400 K (a broad peak, peak 1) and the other at around 390 K (a sharp peak, peak 2). Peak 2 is in correspondence with sudden metal-semiconductor transition (MST) near 400 K. Peak 1 is a kind of internal friction relaxation peak. For the sample with H2O2treatment and with no treatment, the activation energyHare 1.24 eV and 1.04 eV, respectively, and the preexponential factor τ0are 2.54×10-17sec and 7.82×10-15sec, respectively. We speculate that the mechanical relaxation process occurs in the Ca2CoO3subsystem of Ca3Co4O9+δ. The relaxation process for sample with no treatment is associated with the migration of OVs clusters in Ca2CoO3subsystem, and the relaxation process for the sample with H2O2treatment is associated with the migration of isolated OVs in Ca2CoO3subsystem.
Granting wishes beyond medical care
Authors: Wijeratne Nishardi Tharu
Published: January 2012

Quality end of life care requires more than Intensive Care Units and life support machines. Sometimes, we need to spare a little love and understanding for our patients. If we take the time to ask our patients what they most wish during their last days or at least allow them the opportunity to tell us of these dying needs beforehand, end of life care would be more satisfactory for our patients and perhaps for ourselves.DOI: http://dx.doi.org/10.4038/sljcc.v2i1.1549 Sri Lanka Journal of Critical Care Vol.2(1) 2011 33-34
Thyroid Emergencies
Authors: Bondugulapati Laxmi , Adlan Mohamed , Premawardhana Lakdasa
Published: January 2012

Thyroid emergencies though rare, are associated with a high mortality rate. They usually occur in subjects known to have thyroid dysfunction and are precipitated often by recognisable events. A high index of suspicion, early diagnosis and appropriate management in an intensive care setting may help reduce mortality and morbidity. We describe the diagnosis, investigation and managment of thyrotoxic crisis and myxoedema coma in detail below.DOI: http://dx.doi.org/10.4038/sljcc.v2i1.1782 Sri Lanka Journal of Critical Care Vol.2(1) 2011 1-12
Mycobacterium tuberculosis Genotypes in patients developing pulmonary tuberculosis related acute respiratory distress syndrome
Authors: Salahuddin Nawal , Tanveer Mahnaz , Rao Nisar , Akram Saeed , Hasan Zahra , Hasan Rumina
Published: January 2012

Background: Acute Respiratory Distress Syndrome is an uncommon but frequently fatal presentation of pulmonary TB. We attempted to identify whether a specific M. tuberculosis genotype occurs more commonly in patients who develop ARDS. Methods: An observational study carried out at the Aga Khan University Hospital, Karachi, Pakistan enrolled all ARDS patients with tuberculosis. MTB isolates were spoligotyped for strain identification. Results: 725 patients were admitted with pulmonary tuberculosis during the study period. Only 2.5% (18 patients) developed ARDS. Inpatient mortality rate was 58% (7 patients). Genotypes of M. tuberculosis isolates were predominantly CAS I (58.3%) and Unique strains (25%). Beijing and CAS subfamilies were less common; with each genotype identified in 8.3% patients respectively. All except one of the isolated strains were sensitive to usual first line anti-­tubercular drugs. Conclusion: Our results indicate that the CAS1 strains are the most common genotypic strains causing severe respiratory disease in patients with ARDS. DOI: http://dx.doi.org/10.4038/sljcc.v2i1.2370 Sri Lanka Journal of Critical Care Vol.2(1) 2011 20-24Background:AcuteRespiratoryDistressSyndromeisanuncommonbutfrequentlyfatalpresentationofpulmonaryTB.WeattemptedtoidentifywhetheraspecificM.tuberculosisgenotypeoccursmorecommonlyinpatientswhodevelopARDS.Methods:AnobservationalstudycarriedoutattheAgaKhanUniversityHospital,Karachi,PakistanenrolledallARDSpatientswithtuberculosis.MTBisolateswerespoligotypedforstrainidentification.Results:725patientswereadmittedwithpulmonarytuberculosisduringthestudyperiod.Only2.5%(18patients)developedARDS.Inpatientmortalityratewas58%(7patients).GenotypesofM.tuberculosisisolateswerepredominantlyCASI(58.3%)andUniquestrains(25%).BeijingandCASsubfamilieswerelesscommon;witheachgenotypeidentifiedin8.3%patientsrespectively.Allexceptoneoftheisolatedstrainsweresensitivetousualfirstlineanti-­tuberculardrugs.Conclusion:OurresultsindicatethattheCAS1strainsarethemostcommongenotypicstrainscausingsevererespiratorydiseaseinpatientswithARDS.
Recurrent spontaneous pneumothorax in a child
Authors: Bendre Pradnya Suhas , Nagargoje Ramdas Dagdu , Thakur Madhavi Vinayak
Published: January 2012

A 3 year old female child presented with three episodes of left sided pneumothorax in last four months. Patient has minimal respiratory distress in each admission with low grade fever in first two admissions. Intercostal drain was put in first two episodes and VATS with thoracoscopic lung biopsy was done in third episode from left upper lobe with no further episodes of pneumothorax. DOI: http://dx.doi.org/10.4038/sljcc.v2i1.3013   Sri Lanka Journal of Critical Care Vol.2(1) 2011 29-32
ShortCommunication: Enhanced distillers dried grains with solubles (DDGS) has greater concentration of digestible and metabolizable energy than DDGS when fed to growing and finishing pigs
Authors: Soares J. A. , Singh V. , Stein H. H. , Srinavasan R. , Pettigrew J. E.
Published: January 2012

Soares, J. A., Singh, V., Stein, H. H., Srinavasan, R. and Pettigrew, J. E. 2011. SHORT COMMUNICATION: Enhanced distillers dried grains with solubles (DDGS) has greater concentration of digestible and metabolizable energy than DDGS when fed to growing and finishing pigs. Can. J. Anim. Sci. 91: 663–667. To better use distillers dried grains with solubles (DDGS) for non-ruminants, some of the fiber may be removed. The “elusieve” process removes approximately 10% of DDGS material, mostly fiber, yielding enhanced DDGS (E-DDGS). An experiment was conducted to compare the DE and ME in E-DDGS to those in DDGS when fed to growing and finishing pigs. Overall, E-DDGS has greater DE, ME and MEnthan DDGS.
Genetic parameters of the linear body conformation traits and genetic correlations with udder traits, milk yield and composition, and somatic cell count in dairy ewes
Authors: Fernando de la Fuente L. , Gonzalo Carlos , Sánchez Juan , Rodríguez Roberto , Carriedo Juan , Primitivo Fermín
Published: January 2012

de la Fuente, L. F., Gonzalo, C., Sánchez, J. P., Rodríguez, R., Carriedo, J. A. and San Primitivo, F. 2011. Genetic parameters of the linear body conformation traits and genetic correlations with udder traits, milk yield and composition, and somatic cell count in dairy ewes. Can. J. Anim. Sci. 91: 585–591. This study was designed to estimate the inheritance of linear body conformation traits and their genetic correlations with linear udder traits, milk yield and composition, and somatic cell count (SCC) in dairy sheep. A total of 10 189 records of five body conformation traits, five linear udder traits, milk yield, protein and fat content, and SCC were obtained from 3977 adult ewes that were daughters of 268 sires belonging to 23 commercial flocks enrolled in the Churra breed selection nucleus. All type traits were scored on a nine-point linear scale. Genetic correlations and heritabilities were estimated using a repeatability multitrait animal model. Body conformation (stature, rear leg-rear view, feet angle, rump width, and general body score) had heritabilities (0.19, 0.18, 0.24, 0.14 and 0.17) and repeatabilities (0.34, 0.42, 0.42, 0.36, and 0.35), which indicate good potential for selection. For udder traits (udder depth, udder attachment, teat placement, teat length and udder shape) heritabilities varied between 0.09 and 0.26, and repeatabilities between 0.35 and 0.53. General body score (composite trait) had high phenotypic and genetic correlations with rear leg-rear view (0.64 and 0.80) and rump width (0.42 and 0.58). The phenotypic and genetic correlation between general body score and udder shape (composite trait) was 0.23 and 0.44, respectively. In addition, phenotypic and genetic correlations between body conformation traits and milk yield, protein and fat percentages, and SCC were low in most cases; therefore, no significant correlated genetic response is expected in body conformation traits when selecting for milk yield, protein and fat percentages, and SCC variables, in Churra breed. In conclusion, the heritability and repeatability values found in this study for body conformation traits, combined with the ease of recording by linear scale, make improvement by selection possible in dairy sheep.
Short Communication: Associations of BoLA alleles DRB3.2*16 and DRB3.2*23 with health-related traits in Holstein bulls
Authors: Sharma B. S. , Verschoor C. P. , Karrow N. A.
Published: January 2012

Sharma, B. S., Verschoor, C. P. and Karrow, N. A. 2011. Short communication:Associations of BoLA alleles DRB3.2*16 and DRB3.2*23 with health-related traits in Holstein bulls. Can. J. Anim. Sci. 91: 597–600. The relationships between bovine leukocyte antigen (BoLA) DRB3.2 alleles and health and fertility traits were investigated. A group of 548 Canadian and American Holstein bulls was genotyped for the presence of DRB3.2*16 and DRB3.2*23 alleles using the multi-primer target polymerase chain reaction technique. The traits of interest included somatic cell score (SCS), lactation persistency, daughter fertility (DF), and herd life (HL). Higher frequencies were observed for alleles DRB3.2*16 and DRB3.2*23 in this bull population compared with previous reports. In a comparison-wise level, some significant contrasts were detected; however, no association was detected between the DRB3.2 alleles and SCS. Allele DRB3.2*16 had a favorable effect on HL compared with allele DRB3.2*23. On the other hand, these two alleles had a favorable influence on DF, additionally, individuals carrying both of these two alleles performed better than the individuals carrying either allele. Further investigation is warranted to examine the effects of these alleles on HL and reproduction performance.
Temperament in beef cattle: Methods of measurement and their relationship to production
Authors: Sebastian Thomas , Watts Jon , Stookey Joseph , Buchanan Fiona , Waldner Cheryl
Published: January 2012

Sebastian, T., Watts, J. M., Stookey, J. M., Buchanan, F. and Waldner, C. 2011. Temperament in beef cattle: methods of measurement and their relationship to production. Can. J. Anim. Sci. 91: 557–565. Temperament is an individual trait influencing an animal's behavioural response to handling. This characteristic likely modulates the response of the animal to environments and social situations, and is perhaps best viewed as a component of its personality. We assessed temperament using three objective measuring tools, to determine if correlations exist between these and a traditional subjective evaluation. The tools used were strain gauges, a “movement measuring device” (MMD), and a chute exit timer. Four hundred steers were used. Exit time was correlated with values recorded with the MMD and absolute strain forces, and MMD values were related to absolute strain forces. When the animals were classified as “calm” or “wild” based on their subjective scoring, these two groups differed in their mean exit times, MMD values and absolute strain forces. The three objective measures yielded statistically correlated results between tests and across repetitions, and therefore may quantify correlated aspects of a personality trait (i.e., temperament). The objective scores were related to the traditional subjective score, but they provide the advantage of eliminating observer bias and may offer better tools for temperament selection. Significant positive relationships of daily gain with subjective score and MMD values indicate that traditional subjective scoring techniques can be replaced with more repeatable objective measures when temperaments are assessed for performance studies.