bluuebunny/crossref_metadata_2025 huggingface dataset:
Numerical and Experimental Investigation on a Combined Sensible and Latent Heat Storage Unit Integrated With Solar Water Heating System
Authors: Nallusamy N. , Velraj R.
Published: October 2009

The present work investigates, theoretically and experimentally, the thermal performance of a packed bed combined sensible and latent heat storage unit, integrated with the solar water heating system. A one-dimensional porous medium approach with the finite difference technique is used to develop the numerical model to obtain the temperature profiles of both the phase change material (PCM) and heat transfer fluid (HTF), and the molten mass fraction of the PCM at any axial location of the cylindrical storage tank during the charging process. The model also incorporates the effect of the varying fluid inlet temperature to accommodate the actual conditions that prevails in the solar collector. Experimental apparatus utilizing paraffin as PCM, which is filled in high-density polyethylene spherical capsules, is constructed and integrated with a solar flat plate collector to conduct the experiments. The water used as HTF to transfer heat from the solar collector to the storage tank also acts as a sensible heat storage (SHS) material. The results of the numerical model are compared into the experimental results of the temperature profile for various porosities and HTF flow rates. It is found that the results of the numerical model are in good agreement with the experimental results. The performance parameters, such as instantaneous heat stored, cumulative heat stored, and charging rate are also studied in detail.
Development of PCM Storage for Process Heat and Power Generation
Authors: Steinmann Wolf-Dieter , Laing Doerte , Tamme Rainer
Published: October 2009

The increased interest in solar thermal systems using steam as a working medium either for power generation or process heat applications gave rise to a growing demand for latent heat storage units. Essential for the development of cost-effective latent heat storage systems is the achievement of a sufficient power level in spite of the characteristic low thermal diffusivities of latent heat storage materials. The sandwich concept using fins made either from graphite or aluminum has been identified as the most promising option for latent heat storage systems. The feasibility of this approach has been demonstrated by three prototypes using graphite and one prototype using aluminum fins. The prototype with aluminum fins was filled with sodium nitrate and was operated for more than 4000 h without degradation of power. The volume specific average power density is in the range 10–25 kW/m3, so it is proven that the major problem of phase change material (PCM) storage of low heat transfer rates has been overcome and high-temperature PCM storage with large capacity factor is possible.
Phase Change Material Sandwich Panels for Managing Solar Gain in Buildings
Authors: Konuklu Yeliz , Paksoy Halime Ö.
Published: October 2009

In this study, a phase change material (PCM) sandwich panel was developed and tested to evaluate the resulting decrease in heating and cooling loads of a test cabin in Adana, Turkey, where Mediterranean climate prevails. The panel was formed by a macropackage of microencapsulated PCM layer together with an insulation panel. Two different PCMs, with melting points 26°C and 23°C, were used in the panel. Temperature distribution in the cabin was measured for four different cases. In summer, the maximum average temperature reduction achieved in the cabin was 2.5°C when only the PCM was used. This corresponded to a summer cooling load reduction of 7%. In winter, the maximum average temperature increase achieved in the cabin was 2.2°C with the PCM sandwich panel. The winter heating load was decreased by 17%. Energies conserved in cooling and heating were calculated as 186 kWh/year and 206 kWh/year, respectively.
Compact Heat Storage for Solar Heating Systems
Authors: Martin Viktoria , Setterwall Fredrik
Published: October 2009

Energy and cost efficient solar hot water systems require some sort of integrated storage, with high energy density and high power capacity for charging and discharging being desirable properties of the storage. This paper presents the results and conclusions from the design, and experimental performance evaluation of high capacity thermal energy storage using so-called phase change materials (PCMs) as the storage media. A 140 l 15 kW  h storage prototype was designed, built, and experimentally evaluated. The storage tank was directly filled with the PCM having its phase change temperature at 58°C. A tube heat exchanger for charging and discharging with water was submerged in the PCM. Results from the experimental evaluation showed that hot water can be provided with a temperature of 40°C for more than 2 h at an average power of 3 kW. The experimental results also show that it is possible to charge the 140 l storage with close to the theoretically calculated value of 15 kW h. Hence, this is a PCM storage solution with a storage capacity of over 100 kW h/m3, and an average power capacity during discharging of over 20 kW/m3. However, it is desirable to increase the heat transfer rate within the prototype. A predesign of using a finned-tube coil instead of an unfinned coil show that by using finned tube, the power capacity for discharging can be at least doubled, if not tripled.
Test Results of Concrete Thermal Energy Storage for Parabolic Trough Power Plants
Authors: Laing Doerte , Lehmann Dorothea , Fiß Michael , Bahl Carsten
Published: October 2009

Efficient energy storage is vital to the success of solar thermal power generation and industrial waste heat recovery. A sensible heat storage system using concrete as the storage material has been developed by the German building company Ed. Züblin AG and the German Aerospace Center (DLR). A major focus was the cost reduction in the heat exchanger and the high temperature concrete storage material. For live tests and further improvements, a 20 m3 solid media storage test module connected to an electrically heated thermal oil loop was built in Stuttgart. The design of the test module and the test results are described in this paper. By the end of November 2008, the second generation solid media storage test module had accumulated five months of operation in the temperature range between 300°C and 400°C and almost 100 thermal cycles with a temperature difference of 40 K. The tests will be continued in 2009.
Characterization of MgSO4 Hydrate for Thermochemical Seasonal Heat Storage
Authors: van Essen V. M. , Zondag H. A. , Gores J. Cot , Bleijendaal L. P. J. , Bakker M. , Schuitema R. , van Helden W. G. J. , He Z. , Rindt C. C. M.
Published: October 2009

Water vapor sorption in salt hydrates is one of the most promising means for compact, low loss, and long-term storage of solar heat in the built environment. One of the most interesting salt hydrates for compact seasonal heat storage is magnesium sulfate heptahydrate (MgSO4⋅7H2O). This paper describes the characterization of MgSO4⋅7H2O to examine its suitability for application in a seasonal heat storage system for the built environment. Both charging (dehydration) and discharging (hydration) behaviors of the material were studied using thermogravimetric differential scanning calorimetry, X-ray diffraction, particle distribution measurements, and scanning electron microscope. The experimental results show that MgSO4⋅7H2O can be dehydrated at temperatures below 150°C, which can be reached by a medium temperature (vacuum tube) collector. Additionally, the material was able to store 2.2 GJ/m3, almost nine times more energy than can be stored in water as sensible heat. On the other hand, the experimental results indicate that the release of the stored heat is more difficult. The amount of water taken up and the energy released by the material turned out to be strongly dependent on the water vapor pressure, temperature, and the total system pressure. The results of this study indicate that the application of MgSO4⋅7H2O at atmospheric pressure is problematic for a heat storage system where heat is released above 40°C using a water vapor pressure of 1.3 kPa. However, first experiments performed in a closed system at low pressure indicate that a small amount of heat can be released at 50°C and a water vapor pressure of 1.3 kPa. If a heat storage system has to operate at atmospheric pressure, then the application of MgSO4⋅7H2O for seasonal heat storage is possible for space heating operating at 25°C and a water vapor pressure of 2.1 kPa.
PTPσ Is a Receptor for Chondroitin Sulfate Proteoglycan, an Inhibitor of Neural Regeneration
Authors: Shen Yingjie , Tenney Alan P. , Busch Sarah A. , Horn Kevin P. , Cuascut Fernando X. , Liu Kai , He Zhigang , Silver Jerry , Flanagan John G.
Published: October 2009

Toward Neuronal Regeneration

Neurons in the central nervous system that are severed or crushed do not regenerate well. Part of the problem derives from the glial scars left behind after such damage. The scar tissue contains sulfated proteoglycans that seem to inhibit axon regeneration.

Shen
et al.

(p.
592
, published online 15 October) have now identified a protein tyrosine phosphatase (PTP) in mouse neuronal membranes that functions as a receptor for the proteoglycans. Neurons that lacked this particular PTP showed improved regeneration. Regeneration remained incomplete, presumably due to other inhibitory factors in the way of complete axon regeneration.
The Crystal Structure of the Ribosome Bound to EF-Tu and Aminoacyl-tRNA
Authors: Schmeing T. Martin , Voorhees Rebecca M. , Kelley Ann C. , Gao Yong-Gui , Murphy Frank V. , Weir John R. , Ramakrishnan V.
Published: October 2009

Ribosomes Caught in Translation

To synthesize proteins, the ribosome must select cognate transfer RNAs (tRNAs) based on base-pairing with the messenger RNA (mRNA) template (a process known as decoding), form a peptide bond, and then move the mRNA:tRNA assembly relative to the ribosome (a process known as translocation). Decoding and translocation require protein guanosine triphosphatases (GTPases), and, while high-resolution structures of the ribosome have greatly furthered our understanding of ribosome function, the detailed mechanism of these GTPases during the elongation cycle remains unclear. Two Research Articles now give a clearer view of these steps in bacterial protein synthesis (see the Perspective by

Liljas

).

Schmeing
et al.

(p.
688
, published online 15 October) present the crystal structure of the ribosome bound to Elongation factor-Tu (EF-Tu) and amino-acyl tRNA that gives insight into how EF-Tu contributes to accurate decoding.

Gao
et al.

(p.
694
, published online 15 October) describe the crystal structure of the ribosome bound to Elongation factor-G (EF-G) trapped in a posttranslocation state by the antibiotic fusidic acid that gives insight into how EF-G functions in translocation.
The Structure of the Ribosome with Elongation Factor G Trapped in the Posttranslocational State
Authors: Gao Yong-Gui , Selmer Maria , Dunham Christine M. , Weixlbaumer Albert , Kelley Ann C. , Ramakrishnan V.
Published: October 2009

Ribosomes Caught in Translation

To synthesize proteins, the ribosome must select cognate transfer RNAs (tRNAs) based on base-pairing with the messenger RNA (mRNA) template (a process known as decoding), form a peptide bond, and then move the mRNA:tRNA assembly relative to the ribosome (a process known as translocation). Decoding and translocation require protein guanosine triphosphatases (GTPases), and, while high-resolution structures of the ribosome have greatly furthered our understanding of ribosome function, the detailed mechanism of these GTPases during the elongation cycle remains unclear. Two Research Articles now give a clearer view of these steps in bacterial protein synthesis (see the Perspective by

Liljas

).

Schmeing
et al.

(p.
688
, published online 15 October) present the crystal structure of the ribosome bound to Elongation factor-Tu (EF-Tu) and amino-acyl tRNA that gives insight into how EF-Tu contributes to accurate decoding.

Gao
et al.

(p.
694
, published online 15 October) describe the crystal structure of the ribosome bound to Elongation factor-G (EF-G) trapped in a posttranslocation state by the antibiotic fusidic acid that gives insight into how EF-G functions in translocation.
Direct Observations of Interstellar H, He, and O by the Interstellar Boundary Explorer
Authors: Möbius E. , Bochsler P. , Bzowski M. , Crew G. B. , Funsten H. O. , Fuselier S. A. , Ghielmetti A. , Heirtzler D. , Izmodenov V. V. , Kubiak M. , Kucharek H. , Lee M. A. , Leonard T. , McComas D. J. , Petersen L. , Saul L. , Scheer J. A. , Schwadron N. , Witte M. , Wurz P.
Published: October 2009

What's Happening in the Heliosphere

The influence of the Sun is felt well beyond the orbits of the planets. The solar wind is a stream of charged particles emanating from the Sun that carves a bubble in interstellar space known as the heliosphere and shrouds the entire solar system. The edge of the heliosphere, the region where the solar wind interacts with interstellar space, is largely unexplored. Voyager 1 and 2 crossed this boundary in 2004 and 2007, respectively, providing detailed but only localized information. In this issue (see the cover),

McComas
et al.

(p.
959
, published online 15 October),

Fuselier
et al.

(p.
962
, published online 15 October),

Funsten
et al.

(p.
964
, published online 15 October), and

Möbius
et al.

(p.
969
, published online 15 October) present data taken by NASA's Interstellar Boundary Explorer (IBEX). Since early 2009, IBEX has been building all-sky maps of the emissions of energetic neutral atoms produced at the boundary between the heliosphere and the interstellar medium. These maps have unexpectedly revealed a narrow band of emission that bisects the two Voyager locations at energies ranging from 0.2 to 6 kiloelectron volts. Emissions from the band are two- to threefold brighter than outside the band, in contrast to current models that predict much smaller variations across the sky. By comparing the IBEX observations with models of the heliosphere,

Schwadron
et al.

(p.
966
, published online 15 October) show that to date no model fully explains the observations. The model they have developed suggests that the interstellar magnetic field plays a stronger role than previously thought. In addition to the all-sky maps, IBEX measured the signatures of H, He, and O flowing into the heliosphere from the interstellar medium. In a related report,

Krimigis
et al.

(p.
971
, published online 15 October) present an all-sky image of energetic neutral atoms with energies ranging between 6 and 13 kiloelectron volts obtained with the Ion and Neutral Camera onboard the Cassini spacecraft orbiting Saturn. It shows that parts of the structure observed by IBEX extend to high energies. These data indicate that the shape of the heliosphere is not consistent with that of a comet aligned in the direction of the Sun's travel through the galaxy as was previously thought.
Width and Variation of the ENA Flux Ribbon Observed by the Interstellar Boundary Explorer
Authors: Fuselier S. A. , Allegrini F. , Funsten H. O. , Ghielmetti A. G. , Heirtzler D. , Kucharek H. , Lennartsson O. W. , McComas D. J. , Möbius E. , Moore T. E. , Petrinec S. M. , Saul L. A. , Scheer J. A. , Schwadron N. , Wurz P.
Published: October 2009

What's Happening in the Heliosphere

The influence of the Sun is felt well beyond the orbits of the planets. The solar wind is a stream of charged particles emanating from the Sun that carves a bubble in interstellar space known as the heliosphere and shrouds the entire solar system. The edge of the heliosphere, the region where the solar wind interacts with interstellar space, is largely unexplored. Voyager 1 and 2 crossed this boundary in 2004 and 2007, respectively, providing detailed but only localized information. In this issue (see the cover),

McComas
et al.

(p.
959
, published online 15 October),

Fuselier
et al.

(p.
962
, published online 15 October),

Funsten
et al.

(p.
964
, published online 15 October), and

Möbius
et al.

(p.
969
, published online 15 October) present data taken by NASA's Interstellar Boundary Explorer (IBEX). Since early 2009, IBEX has been building all-sky maps of the emissions of energetic neutral atoms produced at the boundary between the heliosphere and the interstellar medium. These maps have unexpectedly revealed a narrow band of emission that bisects the two Voyager locations at energies ranging from 0.2 to 6 kiloelectron volts. Emissions from the band are two- to threefold brighter than outside the band, in contrast to current models that predict much smaller variations across the sky. By comparing the IBEX observations with models of the heliosphere,

Schwadron
et al.

(p.
966
, published online 15 October) show that to date no model fully explains the observations. The model they have developed suggests that the interstellar magnetic field plays a stronger role than previously thought. In addition to the all-sky maps, IBEX measured the signatures of H, He, and O flowing into the heliosphere from the interstellar medium. In a related report,

Krimigis
et al.

(p.
971
, published online 15 October) present an all-sky image of energetic neutral atoms with energies ranging between 6 and 13 kiloelectron volts obtained with the Ion and Neutral Camera onboard the Cassini spacecraft orbiting Saturn. It shows that parts of the structure observed by IBEX extend to high energies. These data indicate that the shape of the heliosphere is not consistent with that of a comet aligned in the direction of the Sun's travel through the galaxy as was previously thought.
Imaging the Interaction of the Heliosphere with the Interstellar Medium from Saturn with Cassini
Authors: Krimigis S. M. , Mitchell D. G. , Roelof E. C. , Hsieh K. C. , McComas D. J.
Published: October 2009

What's Happening in the Heliosphere

The influence of the Sun is felt well beyond the orbits of the planets. The solar wind is a stream of charged particles emanating from the Sun that carves a bubble in interstellar space known as the heliosphere and shrouds the entire solar system. The edge of the heliosphere, the region where the solar wind interacts with interstellar space, is largely unexplored. Voyager 1 and 2 crossed this boundary in 2004 and 2007, respectively, providing detailed but only localized information. In this issue (see the cover),McComaset al.(p.959, published online 15 October),Fuselieret al.(p.962, published online 15 October),Funstenet al.(p.964, published online 15 October), andMöbiuset al.(p.969, published online 15 October) present data taken by NASA's Interstellar Boundary Explorer (IBEX). Since early 2009, IBEX has been building all-sky maps of the emissions of energetic neutral atoms produced at the boundary between the heliosphere and the interstellar medium. These maps have unexpectedly revealed a narrow band of emission that bisects the two Voyager locations at energies ranging from 0.2 to 6 kiloelectron volts. Emissions from the band are two- to threefold brighter than outside the band, in contrast to current models that predict much smaller variations across the sky. By comparing the IBEX observations with models of the heliosphere,Schwadronet al.(p.966, published online 15 October) show that to date no model fully explains the observations. The model they have developed suggests that the interstellar magnetic field plays a stronger role than previously thought. In addition to the all-sky maps, IBEX measured the signatures of H, He, and O flowing into the heliosphere from the interstellar medium. In a related report,Krimigiset al.(p.971, published online 15 October) present an all-sky image of energetic neutral atoms with energies ranging between 6 and 13 kiloelectron volts obtained with the Ion and Neutral Camera onboard the Cassini spacecraft orbiting Saturn. It shows that parts of the structure observed by IBEX extend to high energies. These data indicate that the shape of the heliosphere is not consistent with that of a comet aligned in the direction of the Sun's travel through the galaxy as was previously thought.
Leaps in Translational Elongation
Authors: Liljas Anders
Published: October 2009

Electron microscopic and crystallographic studies shed light on key steps in the protein synthesis process in ribosomes.
Confidentiality, disclosure and doping in sports medicine
Authors: McNamee M , Phillips N
Published: October 2009

The manner in which healthcare and medical professionals serve their athlete patients is governed by a variety of relevant codes of conduct. A range of codified rules is presented that refer both the welfare of the patient and the maintaining of confidentiality, which is at the heart of trustworthy relations. The 2009 version of the World Anti-Doping Code (WADC), however, appears to oblige all healthcare professionals not to assist athletes if they are known to be engaged in doping behaviours under fear of removal from working with athletes from the respective sports. In contrast, serving the best interests of their athlete patients may oblige healthcare professionals to give advice and guidance, not least in terms of harm minimisation. In so far as the professional conduct of a healthcare professional is guided both by professional code and World Anti-Doping Code, they are obliged to fall foul of one or the other. We call for urgent and pressing inter-professional dialogue with the World Anti-Doping Agency to clarify this situation.
THE SOLUTION OF DIRAC EQUATION IN QUASI-EXTREME REISSNER–NORDSTRÖM DE SITTER SPACE
Authors: LYU YAN , CUI SONG , LIU LING
Published: October 2009

The radial parts of Dirac equation between the outer black hole horizon and the cosmological horizon in quasi-extreme Reissner–Nordström de Sitter (RNdS) geometry is solved numerically. We use an accurate polynomial approximation to mimic the modified tortoise coordinate [Formula: see text], for obtaining the inverse function [Formula: see text] and [Formula: see text]. We then use a quantum mechanical method to solve the wave equation and give the reflection and transmission coefficients. We concentrate on two limiting cases. The first case is when the two horizons are close to each other, and the second case is when the horizons are far apart.
COMMENTS ON THE TETRAD (VIELBEINS)
Authors: FUKUYAMA TAKESHI
Published: October 2009

We want to correct the misunderstandings on the tetrad (or vielbeins in general) appeared in many textbooks or review articles. The tetrad should be defined without any condition. eμa = ∂μXa with local Lorentz coordinates Xa is wrong in many senses: it gives the condition ∂μeνa = ∂νeμa, which leads us to the trivial result that the cyclic coefficients vanish identically and to the null Riemannian tensor. Also [Formula: see text] is not scalar under the local Lorentz transformation etc. We show how these deficits are remedied by the correct definition, eμa = DμZa with local (anti) de Sitter coordinates ZA.
NEW TECHNIQUES IN THE SEARCH FOR Z′ BOSONS AND OTHER NEUTRAL RESONANCES
Authors: HAYS CHRISTOPHER , KOTWAL ASHUTOSH , STELZER-CHILTON OLIVER
Published: October 2009

The search for neutral resonances at the energy frontier has a long and illustrious history, resulting in multiple discoveries. The canonical search scans the reconstructed invariant mass distribution of identified fermion pairs. Two recent analyses from the CDF experiment at the Fermilab Tevatron have applied novel methods to resonance searches. One analysis uses simulated templates to fit the inverse mass distribution of muon pairs, a quantity with approximately constant resolution for momenta measured with a tracking detector. The other analysis measures the angular distribution of electron pairs as a function of dielectron mass, gaining sensitivity over a probe of the mass spectrum alone. After reviewing several models that predict new neutral resonances, we discuss these CDF analyses and potential future applications.
INVESTIGATION OF BIAXIAL ELASTIC MODULUS AND CTE OF BaTiO3 FILMS
Authors: HUANG GUI-FANG , HUANG WEI-QING , WANG LING-LING , XIE ZHONG , ZOU BING-SUO , ZHANG JIAN-HUI
Published: October 2009

To develop high-quality film device with good reliability, it is often essential to be able to evaluate the parameters such as stress, the biaxial elastic modulus, and coefficient of thermal expansion (CTE) of film. Based on the stress measurement in situ during the thermal cycle by laser scanning method, two techniques were used to measure the biaxial elastic modulus and CTE of BaTiO 3 films deposited on substrate. The value of the biaxial elastic modulus and CTE for BaTiO 3 films determined from two methods is close, in which the biaxial elastic modulus of BaTiO 3 films is higher than that of corresponding bulk while the CTE of BaTiO 3 films is a little smaller than that of bulk material.
SPECTRAL RADIUS ANALYSIS OF MATRICES AND THE ASSOCIATED WITH INTEGRABLE SYSTEMS
Authors: TAM HONWAH , ZHANG YUFENG
Published: October 2009

An isospectral problem is introduced, a spectral radius of the corresponding spectral matrix is obtained, which enlightens us to set up an isospectral problem whose compatibility condition gives rise to a zero curvature equation in formalism, from which a Lax integrable soliton equation hierarchy with constraints of potential functions is generated along with 5 parameters, whose reduced cases present three integrable systems, i.e., AKNS hierarchy, Levi hierarchy and D-AKNS hierarchy. Enlarging the above Lie algebra into two bigger ones, the two integrable couplings of the hierarchy are derived, one of them has Hamiltonian structure by employing the quadratic-form identity or variational identity. The corresponding integrable couplings of the reduced systems are obtained, respectively. Finally, as comparing study for generating expanding integrable systems, a Lie algebra of antisymmetric matrices and its corresponding loop algebra are constructed, from which a great number of enlarging integrable systems could be generated, especially their Hamiltonian structure could be computed by the trace identity.
MICROSTRUCTURAL, MAGNETIC, MAGNETO-TRANSPORT, AND COMPLEX IMPEDANCE SPECTROSCOPY OF xLa0.7Sr0.3MnO3–(1-x)ErMnO3 MULTIFERROIC (0≤x≤1) COMPOSITES
Authors: DEY P. , NATH T. K. , MANDAL S. K. , DAS A.
Published: October 2009

We have investigated magnetization, magneto-transport, and complex impedance spectroscopy of structurally characterized multiferroic composites x La 0.7 Sr 0.3 MnO 3 (LSMO)–(1-x) ErMnO 3 (EMO) (0≤x≤1). Para- to ferromagnetic Curie temperatures for this series of composites indicate almost complete immiscibility within the mixture of those two compounds of LSMO and EMO having nearly identical chemical formula. Magnetization as a function of magnetic field curves at T=300 K exhibit an appreciable enhancement of coercive field of LSMO in the composites with increase in EMO content. This feature has been attributed to the increasing grain boundary pinning center of LSMO grains at their interfaces in the composites. Magneto-transport measurements reveal a considerable decrease in spin polarized tunneling transport with increase in EMO content in the composites. This feature is understood as a consequence of increasing grain boundary pinning centers of magnetic domains of LSMO grains in the composites. Room temperature complex impedance spectroscopy studies, i.e., -Z′′ versus Z′ curves (Nyquist plots) for EMO, x=0.1, x=0.2, and LSMO samples reveal that relaxation time of both bulk and grain boundary increases with increase in EMO content in the composites. Slow relaxation processes of conduction electrons at both bulk and grain boundary occurs due to the proximity of highly resistive insulating EMO in the composites.
PHASE TRANSITIONS OF THE MIXED-SPIN ISING MODEL ON A DECORATED LATTICE WITH THE NEAREST-NEIGHBOR INTERACTION BETWEEN DECORATING SPINS
Authors: BENYOUSSEF A. , EL KENZ A. , EL YADARI M. , LOULIDI M.
Published: October 2009

A mean-field approximation is developed for a decorated ferrimagnetic Ising model, in which the two magnetic atoms A and B have spins σ=1/2 and S=1, respectively. In this system, the exchange interaction between nearest-neighbors of atom B is taken into account. Some interesting phenomena, such as the appearance of three types of phase diagrams and the existence of one and two compensation points are found. Phase diagrams and temperature dependence of the magnetizations of the system are investigated in detail.
PHOTON IN THE FRAME OF THE CURRENT LOOP MODEL
Authors: SAGLAM M. , SAHIN G.
Published: October 2009

We show that the electron–positron annihilation process ending with the creation of two gamma photons (with right- and left-hand circular helicity) can be explained in terms of the current loop model. We first show that both electron and positron (which are spin 1/2 particles) carry an intrinsic flux quantum of ±Φ0/2 even in the absence of an external magnetic field. By using the conservation of the magnetic flux quanta for collisions, we then argue that photon also carries a magnetic flux quantum of ±Φ0 = ±(hc/e) with itself along the propagation direction, where the (+) sign corresponds to the right-hand helicity and (-) one to the left-hand one.
EFFECTS OF Cr2O3 ON STRUCTURAL, DIELECTRIC, AND ELECTRICAL PROPERTIES OF (Pb0.95Sr0.05)(Zr0.53Ti0.47)O3 CERAMICS
Authors: COSTA MARRERO J. , SUÁREZ-GÓMEZ A. , SANIGER BLESA J. M. , MALFATTI C. , CALDECALDERÓN-PIÑAR F.
Published: October 2009

Compositions with x=0.1, 0.2, 0.4, and 0.5 in the system ( Pb 0.95 Sr 0.05)·( Zr 0.53 Ti 0.47) O 3+x wt % Cr 2 O 3 (PSZTC) were synthesized using conventional ceramic method. Addition of Cr 2 O 3 stabilized the tetragonal phase against the rhombohedral one. Scanning electron microscopy (SEM) showed a decrease of the mean grain size when increasing the doping level. The permittivity and electrical conductivities of the PSZTC compounds have been investigated and the activation energies were calculated.
A JASTROW CORRELATION FACTOR FOR TWO-DIMENSIONAL PARABOLIC QUANTUM DOTS
Authors: CIFTJA ORION
Published: October 2009

One of the standard approaches to calculate the ground-state properties of strongly correlated electronic systems is to use a Jastrow–Slater wavefunction as a starting point. When considering confined electrons in a two-dimensional parabolic quantum dot, one chooses the Slater determinant to be the ground-state wavefunction of confined independent electrons and then determines the form of the Jastrow correlation factor in a way that incorporates accurately the spatial correlations of the system. One way to choose a quality Jastrow correlation factor is to consider the two-body problem and search the best possible yet simple approximative solution to such a problem. To achieve this goal, we consider the two-body problem of confined electrons interacting with a Coulomb repulsive potential in zero magnetic field and focus on their relative motion. Based on straightforward theoretical considerations, we suggest a simple two-body Jastrow correlation factor that optimizes very well the overall trial energy. We test the quality of the proposed Jastrow correlation factor by comparing the results to exact numerical diagonalization solutions.
CHARACTERIZATION OF Ni-RICH INTERMETALLIC COMPOUND Ni3Al FILMS WITH SLOW POSITRON BEAM
Authors: LIU JIANDANG , WENG HUIMIN , CHEN XIANGLEI , DU HUAIJIANG , YE BANGJIAO , LI WENJUAN , ZHOU JICHENG
Published: October 2009

Ni -rich intermetallic compound Ni 3 Al films were deposited using the dual-target magnetron co-sputtering method. The grain-boundary and grain-size characteristics of the as-deposited and post-annealed Ni 3 Al films were investigated using a slow positron beam. The results demonstrate a distinct change of S-parameter and positron effective diffusion length L eff values as samples were annealed at different ambient atmospheres and temperatures. It shows that the positron trapping center is mainly associated with intergranular vacancies, and changes to either the vacancy cluster size or the grain size have been invoked to explain the changes of the values of the S-parameter and L eff . Ni -rich oxygen- Ni 3 Al films were also studied. All films were identified using X-ray diffraction and the results confirm the conclusion obtained by the slow positron beam.
UNUSUAL MAGNETIC HYSTERESIS AND ELECTRICAL TRANSPORT BEHAVIOR IN La0.67Ca0.33MnO3/xCuO COMPOSITE
Authors: MIAO J. H. , YUAN S. L.
Published: October 2009

Temperature dependence of magnetization for the composite La 0.67 Ca 0.33 MnO 3 ( LCMO )/x CuO (x = 20%) has been measured in the cooling and warming process under magnetic fields of 0.5 T and 5.0 T. Unusual magnetic hysteresis behavior was observed, which is different from the spin glass behavior usually observed in perovskite manganites. It is interesting to note that in the same temperature region, the sample shows substantial magnetoresistance effect, and a relaxation behavior of resistivity has also been observed. Moreover, the ρ–T curve for the sample fits well to the phenomenological percolation model based on phase segregation. This result confirms the coexistence of ferromagnetic clusters and paramagnetic regions near T c .
NANOMECHANICAL BEHAVIOR OF HUMAN MOLARS SOAKED IN SLIGHT ACID SOLUTIONS
Authors: FANG TE-HUA , CHANG WIN-JIN , KANG SHAO-HUI , CHU CHIA-CHUN
Published: October 2009

This paper studied the mechanical and chemical properties of hydroxyl apatite (HA) crystal structure in the teeth when human molars were soaked in slight acid solution. First, we soaked the ground and polished molars respectively in the liquor of 30 wt.% H 2 CO 3 and the liquor of 30 wt.% H 2 O 2 for 10, 20, or 60 minutes. Next, we used a nanoindenter to measure the hardness and Young's modulus. Finally, we used a scanning electron microscope (SEM) coupled with energy dispersive spectroscopy (EDS) to analyze the variation of Ca , P and Na in teeth, a high resolution transmitting electron microscope (HRTEM) to observe the arrangement of crystallization phase of HA, and X-ray diffraction (XRD) to analyze the crystallinity of the hexagonal phase of HA. The results showed that the demineralization phenomenon of the calcium–phosphorous compound in teeth made the teeth reduce sharply in hardness and Young's modulus after they were soaked in the two slight acid solutions for 10 minutes, but the re-mineralization phenomenon made the hardness and Young's modulus ascend gradually when the time lasted longer. With the same period of time, the teeth soaked in H 2 CO 3 were lower in the hardness and Young's modulus than that in H 2 O 2.
EFFECT OF EXTERNAL MAGNETIC FIELD ON AFM ORDER PARAMETER AND NEEL TEMPERATURE IN ELECTRON DOPED CUPRATE SUPERCONDUCTORS
Authors: PANDA B. N. , SAHOO B. K.
Published: October 2009

A theoretical model is presented to study the effect of an external magnetic field on antiferromagnetic (AFM) order parameter and Neel temperature in electron doped high TC cuprates in normal state. The expression for the antiferromagnetic order parameter is derived by using double time electron Green function of Zubarev type and studied numerically. It is found that the magnetic field up to a certain parametric value considerably enhances the Neel temperature. Above this value, the Neel temperature decreases on increasing the field. The trend of field dependence of the AFM order parameter at 30 K is quite similar to that of Neel temperature. This parametric study of external magnetic field is in good agreement with experimental findings.
OPTICAL SWITCHING OF ERYTHROSINE B BASED POLY (METHACRYLATE) FILMS
Authors: HASSAN QUSAY MOHAMMED ALI
Published: October 2009

Erythrosine B based poly (methacrylate) films with varying even number of methylene spacers have been prepared by the free radical polymerization method. All optical switching and beam deflection effects of polymer films have been investigated by using Nd :YAG laser (532 nm) as a pump beam and a He – Ne laser (632.8 nm) as a probe beam. The nonlinear refractive indices of polymer films are determined using the Z-scan technique. The optical switching and beam deflection effects are due to the change of the refractive index of polymer under the pump beam. The experimental results show that erythrosine B based poly (methacrylate) films have potential application in optical switching.
CURIE TEMPERATURE OF THE TWO-BAND MODEL FOR DILUTED MAGNETIC SEMICONDUCTORS IN COHERENT POTENTIAL APPROXIMATION
Authors: HOANG ANH-TUAN
Published: October 2009

Coherent potential approximation (CPA) is extended to a two-band model for diluted magnetic semiconductors (DMS). The magnetic transition temperature Tc as a function of magnetic coupling constants, hopping parameters and carrier densities is calculated by minimizing the free energy of the coupled carrier-localized spin system. It is shown that Tc can be substantially raised by considering multiband systems.
INFLUENCE OF CONTINUOUS AND DISCONTINUOUS DEPOSITIONS ON PROPERTIES OF ITO FILMS PREPARED BY DC MAGNETRON SPUTTERING
Authors: AIEMPANAKIT K. , RAKKWAMSUK P. , DUMRONGRATTANA S.
Published: October 2009

Indium tin oxide (ITO) films were deposited on glass substrate without external heating by DC magnetron sputtering with continuous deposition of 800 s (S1) and discontinuous depositions of 400 s × 2 times (S2), 200 s × 4 times (S3) and 100 s × 8 times (S4). The structural, surface morphology, optical transmittance and electrical resistivity of ITO films were measured by X-ray diffraction, atomic force microscope, spectrophotometer and four-point probe, respectively. The deposition process of the S1 condition shows the highest target voltage due to more target poisoning occurrence. The substrate temperature of the S1 condition increases with the saturation curve of the RC charging circuit while other conditions increase and decrease due to deposition steps as DC power turns on and off. Target voltage and substrate temperature of ITO films decrease when changing the deposition conditions from S1 to S2, S3 and S4, respectively. The preferential orientation of ITO films were changed from dominate (222) plane to (400) plane with the increasing number of deposition steps. The ITO film for the S4 condition shows the lowest electrical resistivity of 1.44 × 10-3 Ω· cm with the highest energy gap of 4.09 eV and the highest surface roughness of 3.43 nm. These results were discussed from the point of different oxygen occurring on the surface ITO target between the sputtering processes which affected the properties of ITO films.
THERMAL ENTANGLEMENT FOR DIFFERENT INHOMOGENEOUS MAGNETIC FIELDS IN THE ANISOTROPIC HEISENBERG XY MODEL
Authors: LI DA-CHUANG , CAO ZHUO-LIANG
Published: October 2009

Thermal entanglement is investigated in a two-qubit Heisenberg XY model with different inhomogeneous magnetic fields. It is found that the entanglement is dependent on the magnetic field, and the magnetic fields along different axes have different control efficiencies of entanglement. In addition, no matter in antiferromagnetic model or in ferromagnetic model, according to the relation between spin–spin coupling coefficients, the more efficient control parameters of entanglement can be obtained by adjusting the direction of external magnetic fields.
ELECTRONIC AND OPTICAL PROPERTIES OF BaO, BaS, BaSe, BaTe AND BaPo COMPOUNDS UNDER HYDROSTATIC PRESSURE
Authors: DRABLIA S. , MERADJI H. , GHEMID S. , BOUKHRIS N. , BOUHAFS B. , NOUET G.
Published: October 2009

We have performed first-principle full-potential (linear) augmented plane wave plus local orbital calculations (FP-L/APW + l0) with density functional theory (DFT) in local density approximation (LDA) and generalized gradient approximation (GGA), with the aim to determine and predict the electronic and optical properties of rocksalt BaO , BaS , BaSe , BaTe and BaPo compounds. First we present the main features of the electronic properties of these compounds, where the electronic band structure shows that the fundamental energy gap is indirect (Γ–X) for all compounds except for BaO which is direct (X–X). The different interband transitions have been determined from the imaginary part of the dielectric function. The real and imaginary parts of the dielectric function and the reflectivity are calculated. We have presented the assignment of the different optical transitions existing in these compounds from the imaginary part of the dielectric function spectra with respect to their correspondence in the electronic band. We have also calculated the pressure and volume dependence of the optical properties for these compounds.
Fasting differentially regulates plasma corticosterone-binding globulin, glucocorticoid receptor, and cell cycle in the gastric mucosa of pups and adult rats
Authors: Ogias Daniela , de Andrade Sá Eunice Ribeiro , Kasai Ariane , Moisan Marie-Pierre , Alvares Eliana Parisi , Gama Patrícia
Published: October 2009

The nutritional status influences gastric growth, and interestingly, whereas cell proliferation is stimulated by fasting in suckling rats, it is inhibited in adult animals. Corticosterone takes part in the mechanisms that govern development, and its effects are regulated in particular by corticosterone-binding globulin (CBG) and glucocorticoid receptor (GR). To investigate whether corticosterone activity responds to fasting and how possible changes might control gastric epithelial cell cycle, we evaluated different parameters during the progression of fasting in 18- and 40-day-old rats. Food restriction induced higher corticosterone plasma concentration at both ages, but only in pups did CBG binding increase after short- and long-term treatments. Fasting also increased gastric GR at transcriptional and protein levels, but the effect was more pronounced in 40-day-old animals. Moreover, in pups, GR was observed in the cytoplasm, whereas, in adults, it accumulated in the nucleus after the onset of fasting. Heat shock protein (HSP) 70 and HSP 90 were differentially regulated and might contribute to the stability of GR and to the high cytoplasmic levels in pups and elevated shuttling in adult rats. As for gastric epithelial cell cycle, whereas cyclin D1 and p21 increased during fasting in pups, in adults, cyclin E slowly decreased, concomitant with higher p27. In summary, we demonstrated that corticosterone function is differentially regulated by fasting in 18- and 40-day-old rats, and such variation might attenuate any possible suppressive effects during postnatal development. We suggest that this mechanism could ultimately increase cell proliferation and allow regular gastric growth during adverse nutritional conditions.
Physiological roles of endogenous ouabain in normal rats
Authors: Nesher Maoz , Dvela Moran , Igbokwe Vincent U. , Rosen Haim , Lichtstein David
Published: October 2009

Endogenous ouabain (EO)-like compounds are synthesized in and released from the adrenal gland. Although EO has been implicated in several pathological states such as hypertension and heart and kidney failure, its physiological roles in normal animal have not been elucidated. To address this issue, we studied the effects of reduction in plasma EO resulting from antiouabain antibody administration. Normal rats were treated for 28 days with antiouabain antibodies or rabbit IgG as control. Infusions were delivered through a jugular vein cannula by osmotic pumps, and blood pressure was monitored by tail-cuff plethysmography. The animals were housed in metabolic cages to measure water and food consumption and urine excretion. After 28 days, the thoracic aorta was isolated and used to study phenylephrine-induced contraction and atrial natriuretic peptide (ANP)-induced vasorelaxation. The adrenal gland cortex was enlarged in the antiouabain antibody-treated rats. Moreover, on the second day of treatment, there was a significant transient reduction in natriuresis in the antiouabain antibody-treated rats, suggesting that EO is a natriuretic hormone. Reduction in natriuresis was also observed when EO levels were reduced by active immunization resulting from sequential injection of ouabain-albumin. Furthermore, following 28 days of treatment, the response to phenylephrine was significantly lowered and that to ANP was significantly increased in aortic rings from antiouabain antibody-treated rats. These findings show for the first time that circulatory ouabain plausibly originating in the adrenal has physiological roles controlling vasculature tone and sodium homeostasis in normal rats.
Right ventricular free wall pacing improves cardiac pump function in severe pulmonary arterial hypertension: a computer simulation analysis
Authors: Lumens Joost , Arts Theo , Broers Bernard , Boomars Karin A. , van Paassen Pieter , Prinzen Frits W. , Delhaas Tammo
Published: October 2009

In pulmonary arterial hypertension (PAH), duration of myofiber shortening is prolonged in the right ventricular (RV) free wall (RVfw) compared with that in the interventricular septum and left ventricular free wall. This interventricular mechanical asynchrony eventually leads to right heart failure. We investigated by computer simulation whether, in PAH, early RVfw pacing may improve interventricular mechanical synchrony and, hence, cardiac pump function. A mathematical model of the human heart and circulation was used to simulate left ventricular and RV pump mechanics and myofiber mechanics. First, we simulated cardiovascular mechanics of a healthy adult at rest. Size and mass of heart and blood vessels were adapted so that mechanical tissue load was normalized. Second, compensated PAH was simulated by increasing mean pulmonary artery pressure to 32 mmHg while applying load adaptation. Third, decompensated PAH was simulated by increasing mean pulmonary artery pressure further to 79 mmHg without further adaptation. Finally, early RVfw pacing was simulated in severely decompensated PAH. Time courses of circumferential strain in the ventricular walls as simulated were similar to the ones measured in healthy subjects (uniform strain patterns) and in PAH patients (prolonged RVfw shortening). When simulating pacing in decompensated PAH, RV pump function was best upon 40-ms RVfw preexcitation, as evidenced by maximal decrease of RV end-diastolic volume, reduced RVfw myofiber work, and most homogeneous distribution of workload over the ventricular walls. Thus our simulations indicate that, in decompensated PAH, RVfw pacing may improve RV pump function and may homogenize workload over the ventricular walls.
Low-frequency assessment of airway and tissue mechanics in ventilated COPD patients
Authors: Lorx András , Szabó Barna , Hercsuth Magdolna , Pénzes István , Hantos Zoltán
Published: October 2009

Low-frequency forced oscillations have increasingly been employed to characterize airway and tissue mechanics separately in the normal respiratory system and animal models of lung disease; however, few data are available on the use of this method in chronic obstructive pulmonary disease (COPD). We studied 30 intubated and mechanically ventilated patients (COPD, n = 9; acute exacerbation of COPD, n = 21) during short apneic intervals at different levels of positive end-expiratory pressure (PEEP), with small-amplitude forced oscillations between 0.4 and 4.8 Hz. In 16 patients, measurements were made before and after inhalation of fenoterol hydrobromide plus ipratropium bromide (Berodual). Newtonian resistance and coefficients of tissue resistance (G) and elastance (H) were estimated from the respiratory system impedance (Zrs) data by model fitting. Apart from some extremely high Zrs data obtained primarily at relatively low PEEP levels, the model yielded a reasonable partitioning of the airway and tissue parameters, and the inclusion of further parameters did not improve the model performance. With increasing PEEP, Newtonian resistance and the ratio G/H decreased, reflecting the volume dependence of the airway caliber and the improved homogeneity of the lungs, respectively. Bronchodilation after the administration of Berodual was also associated with simultaneous decreases in G and H, indicating recruitment of lung units. In conclusion, the measurement of low-frequency Zrs can be accomplished in ventilated COPD patients during short apneic periods and offers valuable information on the mechanical status of the airways and tissues.