bluuebunny/crossref_metadata_2025 huggingface dataset:
A study of temperature-related non-linearity at the metal-silicon interface
Authors: Gammon P. M. , Donchev E. , Pérez-Tomás A. , Shah V. A. , Pang J. S. , Petrov P. K. , Jennings M. R. , Fisher C. A. , Mawby P. A. , Leadley D. R. , McN. Alford N.
Published: December 2012

In this paper, we investigate the temperature dependencies of metal-semiconductor interfaces in an effort to better reproduce the current-voltage-temperature (IVT) characteristics of any Schottky diode, regardless of homogeneity. Four silicon Schottky diodes were fabricated for this work, each displaying different degrees of inhomogeneity; a relatively homogeneous NiV/Si diode, a Ti/Si and Cr/Si diode with double bumps at only the lowest temperatures, and a Nb/Si diode displaying extensive non-linearity. The 77–300 K IVT responses are modelled using a semi-automated implementation of Tung's electron transport model, and each of the diodes are well reproduced. However, in achieving this, it is revealed that each of the three key fitting parameters within the model display a significant temperature dependency. In analysing these dependencies, we reveal how a rise in thermal energy “activates” exponentially more interfacial patches, the activation rate being dependent on the carrier concentration at the patch saddle point (the patch's maximum barrier height), which in turn is linked to the relative homogeneity of each diode. Finally, in a review of Tung's model, problems in the divergence of the current paths at low temperature are explained to be inherent due to the simplification of an interface that will contain competing defects and inhomogeneities.
First principles study of oxygen vacancy states in monoclinic ZrO2: Interpretation of conduction characteristics
Authors: Hur Ji-Hyun , Park Seongjun , Chung U-In
Published: December 2012

We perform first-principles calculation of monoclinic ZrO2 with oxygen vacancies by using a hybrid functional method to obtain band gap and corresponding energy levels of vacancy states with different charges or coordination numbers. The result agrees well with experimentally measured value. Based on the calculations, explanation for the conduction characteristics which is dependent on applied electric field in monoclinic ZrO2 volume is given.
Horseshoes of periodically kicked van der Pol oscillators
Authors: Ryals Brian , Young Lai-Sang
Published: December 2012

This paper contains a numerical study of the periodically forced van der Pol system. Our aim is to determine the extent to which chaotic behavior occurs in this system as well as the nature of the chaos. Unlike previous studies, which used continuous forcing, we work with instantaneous kicks, for which the geometry is simpler. Our study covers a range of parameters describing nonlinearity, kick sizes, and kick periods. We show that horseshoes are abundant whenever the limit cycle is kicked to a specific region of the phase space and offer a geometric explanation for the stretch-and-fold behavior which ensues.
Supercharges in the hyper-Kähler with torsion supersymmetric sigma models
Authors: Smilga A. V.
Published: December 2012

We construct explicitly classical and quantum supercharges satisfying the standard ${\cal N} = 4$N=4 supersymmetry algebra in the supersymmetric sigma models describing the motion over hyper-Kähler with torsion manifolds. One member of the family of superalgebras thus obtained is equivalent to the superalgebra derived and formulated earlier in purely mathematical framework.
An effective structure prediction method for layered materials based on 2D particle swarm optimization algorithm
Authors: Wang Yanchao , Miao Maosheng , Lv Jian , Zhu Li , Yin Ketao , Liu Hanyu , Ma Yanming
Published: December 2012

A structure prediction method for layered materials based on two-dimensional (2D) particle swarm optimization algorithm is developed. The relaxation of atoms in the perpendicular direction within a given range is allowed. Additional techniques including structural similarity determination, symmetry constraint enforcement, and discretization of structure constructions based on space gridding are implemented and demonstrated to significantly improve the global structural search efficiency. Our method is successful in predicting the structures of known 2D materials, including single layer and multi-layer graphene, 2D boron nitride (BN) compounds, and some quasi-2D group 6 metals(VIB) chalcogenides. Furthermore, by use of this method, we predict a new family of mono-layered boron nitride structures with different chemical compositions. The first-principles electronic structure calculations reveal that the band gap of these N-rich BN systems can be tuned from 5.40 eV to 2.20 eV by adjusting the composition.
Auger decay of molecular double core-hole and its satellite states: Comparison of experiment and calculation
Authors: Tashiro Motomichi , Nakano Motoyoshi , Ehara Masahiro , Penent Francis , Andric Lidija , Palaudoux Jérôme , Ito Kenji , Hikosaka Yasumasa , Kouchi Noriyuki , Lablanquie Pascal
Published: December 2012

Auger decay of the C2H2 double core-hole (DCH) states, including the single-site DCH (C1s−2), two-site DCH (C1s−1C1s−1), and satellite (C1s−2π−1π*+1) states, has been investigated experimentally using synchrotron radiation combined with multi-electron coincidence method, and theoretically with the assumption of the two-step sequential model for Auger decay of the DCH states. The theoretical calculations can reproduce the experimental two-dimensional Auger spectra of the C2H2 single-site DCH and satellite decays, and allow to assign the peaks appearing in the spectra in terms of sequential two-electron vacancy creations in the occupied valence orbitals. In case of the one-dimensional Auger spectrum of the C2H2 two-site DCH decay, the experimental and calculated results agree well, but assignment of peaks is difficult because the first and second Auger components overlap each other. The theoretical calculations on the Auger decay of the N2 single-site DCH state, approximately considering the effect of nuclear motion, suggest that the nuclear motion, together with the highly repulsive potential energy curves of the final states, makes an important effect on the energy distribution of the Auger electrons emitted in the second Auger decay.
Rubber elasticity for incomplete polymer networks
Authors: Nishi Kengo , Chijiishi Masashi , Katsumoto Yukiteru , Nakao Toshio , Fujii Kenta , Chung Ung-il , Noguchi Hiroshi , Sakai Takamasa , Shibayama Mitsuhiro
Published: December 2012

We investigated the relationship between the elastic modulus, G and the reaction probability, p for polymer networks. First, we pointed out that the elastic modulus is expressed by G = {(fp/2 − 1) + O((p − 1)2)} NkBT/V (percolated network law), which does not depend on the local topology of the network structure or the existence of the loops. Here, N is the number of lattice point, V is the system volume, f is the functionality of the cross-link, kB is the Boltzmann constant, and T is the absolute temperature. We also conducted simulations for polymer networks with triangular and diamond lattices, and mechanical testing experiments on tetra-poly(ethylene glycol) (PEG) gel with systematically tuning the reaction probability. Here, the tetra-PEG gel was confirmed to be a potential candidate for ideal polymer networks consisting of unimodal strands free from defects and entanglements. From the results of simulations and experiments, it was revealed, for the first time, that the elastic modulus obeys this law in the wide range of p (pc ≪ p ≤ 1), where pc is the reaction probability at gelation threshold.
Dynamic correlation length growth in superspin glass: Bridging experiments and simulations
Authors: Nakamae S. , Crauste-Thibierge C. , L'Hôte D. , Vincent E. , Dubois E. , Dupuis V. , Perzynski R.
Published: December 2012

Interacting magnetic nanoparticles display a wide variety of magnetic behaviors that are now being gathered in the emerging field of “supermagnetism.” We have investigated how the out-of-equilibrium dynamics in the disordered superspin glass (SSG) state of a frozen ferrofluid sample is affected by texturation. Via magnetization relaxation experiments at low temperatures, we were able to estimate superspin correlation lengths for both textured and non-textured samples. The comparison with simulations and experiments on atomic spin glasses shows that the dynamic correlations in SSG's appear to develop in a way reminiscent to those in atomic spin glasses at intermediate time/length scales.
Stable n-channel metal-semiconductor field effect transistors on ZnO films deposited using a filtered cathodic vacuum arc
Authors: Elzwawi S. , Kim H-S. , Lynam M. , Mayes E. L. H. , McCulloch D. G. , Allen M. W. , Partridge J. G.
Published: December 2012

We report on the properties of metal-semiconductor-field-effect-transistors (MESFETs) on ZnO films grown using the filtered cathodic vacuum arc (FCVA) technique. FCVA ZnO films deposited on a-plane sapphire at 200 °C showed good structural and electrical properties that improved further on annealing at 800 °C in oxygen, due to the formation of larger grains with lower inter-grain transport barriers. MESFETs with silver oxide and iridium oxide Schottky gates on these annealed films showed excellent long-term stability with low ideality factors (<1.3), low gate leakage, and channel mobilities up to 50 cm2/Vs that were unchanged with both age and stress testing.
Indentation device for in situ Raman spectroscopic and optical studies
Authors: Gerbig Y. B. , Michaels C. A. , Forster A. M. , Hettenhouser J. W. , Byrd W. E. , Morris D. J. , Cook R. F.
Published: December 2012

Instrumented indentation is a widely used technique to study the mechanical behavior of materials at small length scales. Mechanical tests of bulk materials, microscopic, and spectroscopic studies may be conducted to complement indentation and enable the determination of the kinetics and physics involved in the mechanical deformation of materials at the crystallographic and molecular level, e.g., strain build-up in crystal lattices, phase transformations, and changes in crystallinity or orientation. However, many of these phenomena occurring during indentation can only be observed in their entirety and analyzed in depth under in situ conditions. This paper describes the design, calibration, and operation of an indentation device that is coupled with a Raman microscope to conduct in situ spectroscopic and optical analysis of mechanically deformed regions of Raman-active, transparent bulk material, thin films or fibers under contact loading. The capabilities of the presented device are demonstrated by in situ studies of the indentation-induced phase transformations of Si thin films and modifications of molecular conformations in high density polyethylene films.
Nonrelativistic quantum dynamics on a cone with and without a constraining potential
Authors: Filgueiras C. , Silva E. O. , Andrade F. M.
Published: December 2012

In this paper we investigate the bound state problem of nonrelativistic quantum particles on a conical surface. This kind of surface appears as a topological defect in ordinary semiconductors as well as in graphene sheets. Specifically, we compare and discuss the results stemming from two different approaches. In the first one, it is assumed that the charge carriers are bound to the surface by a constraining potential, while the second one is based on the Klein-Gordon type equation on surfaces, without the constraining potential. The main difference between both theories is the presence/absence of a potential which contains the mean curvature of a given surface. This fact changes the dependence of the bound states on the angular momentum l. Moreover, there are bound states that are absent in the Klein-Gordon theory, which instead appear in the Schrödinger one.
Combined cross sectional scanning tunneling microscopy and high resolution x-ray diffraction study for quantitative structural descriptions of type-II superlattice infrared detectors
Authors: Yakes M. K. , Qadri S. B. , Mahadik N. A. , Yi C. , Lubyshev D. , Fastenau J. M. , Liu A. W. K. , Aifer E. H.
Published: December 2012

Thorough structural analysis is critical to understanding the effects of device design and modeling on type II superlattice (T2SL) based devices. In this work, structural parameters of T2SL infrared devices were uniquely determined by combining local structural parameters obtained by cross-sectional scanning tunneling microscopy (XSTM) with high resolution x-ray diffraction (HRXRD) spectra. The XSTM results were used to initialize and set tolerances for full dynamical simulation and simultaneous fitting of multiple HRXRD spectra. Using this method, we obtain unique, quantitative description of the superlattice structure, composition, and strain which can be used to evaluate the material effects on device performance.
Atomically resolved study of the morphology change of InAs/GaAs quantum dot layers induced by rapid thermal annealing
Authors: Keizer J. G. , Henriques A. B. , Maia A. D. B. , Quivy A. A. , Koenraad P. M.
Published: December 2012

The optoelectronic properties of InAs/GaAs quantum dots can be tuned by rapid thermal annealing. In this study, the morphology change of InAs/GaAs quantum dots layers induced by rapid thermal annealing was investigated at the atomic-scale by cross-sectional scanning tunneling microscopy. Finite elements calculations that model the outward relaxation of the cleaved surface were used to determine the indium composition profile of the wetting layer and the quantum dots prior and post rapid thermal annealing. The results show that the wetting layer is broadened upon annealing. This broadening could be modeled by assuming a random walk of indium atoms. Furthermore, we show that the stronger strain gradient at the location of the quantum dots enhances the intermixing. Photoluminescence measurements show a blueshift and narrowing of the photoluminescence peak. Temperature dependent photoluminescence measurements show a lower activation energy for the annealed sample. These results are in agreement with the observed change in morphology.
Photoresponse from noble metal nanoparticles-multi walled carbon nanotube composites
Authors: Scarselli M. , Camilli L. , Matthes L. , Pulci O. , Castrucci P. , Gatto E. , Venanzi M. , De Crescenzi M.
Published: December 2012

In this Letter, we investigated the photo-response of multi wall carbon nanotube-based composites obtained from in situ thermal evaporation of noble metals (Au, Ag, and Cu) on the nanotube films. The metal deposition process produced discrete nanoparticles on the nanotube outer walls. The nanoparticle-carbon nanotube films were characterized by photo-electrochemical measurements in a standard three electrode cell. The photocurrent from the decorated carbon nanotubes remarkably increased with respect to that of bare multiwall tubes. With the aid of first-principle calculations, these results are discussed in terms of metal nanoparticle–nanotube interactions and electronic charge transfer at the interface.
Bacterial aggregation and biofilm formation in a vortical flow
Authors: Yazdi Shahrzad , Ardekani Arezoo M.
Published: December 2012

Bacterial aggregation and patchiness play an important role in a variety of ecological processes such as competition, adaptation, epidemics, and succession. Here, we demonstrate that hydrodynamics of their environment can lead to their aggregation. This is specially important since microbial habitats are rarely at rest (e.g., ocean, blood stream, flow in porous media, and flow through membrane filtration processes). In order to study the dynamics of bacterial collection in a vortical flow, we utilize a microfluidic system to mimic some of the important microbial conditions at ecologically relevant spatiotemporal scales. We experimentally demonstrate the formation of “ring”-shaped bacterial collection patterns and subsequently the formation of biofilm streamers in a microfluidic system. Acoustic streaming of a microbubble is used to generate a vortical flow in a microchannel. Due to bacteria's finite-size, the microorganisms are directed to closed streamlines and trapped in the vortical flow. The collection of bacteria in the vortices occurs in a matter of seconds, and unexpectedly, triggers the formation of biofilm streamers within minutes. Swimming bacteria have a competitive advantage to respond to their environmental conditions. In order to investigate the role of bacterial motility on the rate of collection, two strains of Escherichia coli bacteria with different motilities are used. We show that the bacterial collection in a vortical flow is strongly pronounced for high motile bacteria.
Dynamics of quasi-spherical Z-pinch implosions with mass redistribution and displacement modification
Authors: Zhang Yang , Ding Ning , Li Zheng-Hong , Sun Shun-Kai , Xue Chuang , Ning Cheng , Xiao De-Long , Huang Jun
Published: December 2012

Implosions of (quasi-)spherical loads with mass redistribution and displacement modification are investigated numerically. Both methods can theoretically counterbalance the nonuniformity of magnetic pressure along the load surface and realize quasi-spherical Z-pinch implosions. Mass redistribution is feasible for spherical loads with large radius and weight, while the displacement modification is more suitable for light loads, such as those composed of wire arrays. Simulation results suggest that, for mass redistributed spherical loads, wall instabilities induced by polar mass flows will deform the imploding shell. For prolate spherical loads, in which the wall instability cannot develop, the kinetic energy distribution is disturbed at high latitude. These passive behaviors and their possible mitigation methods, such as reshaping the electrode, are investigated numerically in this paper.
Practical considerations in realizing a magnetic centrifugal mass filter
Authors: Gueroult Renaud , Fisch Nathaniel J.
Published: December 2012

The magnetic centrifugal mass filter concept represents a variation on the plasma centrifuge, with applications that are particularly promising for high-throughput separation of ions with large mass differences. A number of considerations, however, constrain the parameter space in which this device operates best. The rotation speed, magnetic field intensity, and ion temperature are constrained by the ion confinement requirements. Collisions must also be large enough to eject ions, but small enough not to eject them too quickly. The existence of favorable regimes meeting these constraints is demonstrated by a single-particle orbit code. As an example of interest, it is shown that separation factors of about 2.3 are achievable in a single pass when separating Aluminum from Strontium ions.
Multi-function microsystem for cells migration analysis and evaluation of photodynamic therapy procedure in coculture
Authors: Jastrzebska (Jedrych) Elzbieta , Grabowska-Jadach Ilona , Chudy Michal , Dybko Artur , Brzozka Zbigniew
Published: December 2012

Cell migration is an important physiological process, which is involved in cancer metastasis. Therefore, the investigation of cell migration may lead to the development of novel therapeutic approaches. In this study, we have successfully developed a microsystem for culture of two cell types (non-malignant and carcinoma) and for analysis of cell migration dependence on distance between them. Finally, we studied quantitatively the influence of photodynamic therapy (PDT) procedures on the viability of pairs of non-malignant (MRC5 or Balb/3T3) and carcinoma (A549) cells coculture. The proposed geometry of the microsystem allowed for separate introduction of two cell lines and analysis of cells migration dependence on distance between the cells. We found that a length of connecting microchannel has an influence on cell migration and viability of non-malignant cells after PDT procedure. Summarizing, the developed microsystem can constitute a new tool for carrying out experiments, which offers a few functions: cell migration analysis, carcinoma and non-malignant cells coculture, and evaluation of PDT procedure in the various steps of cell migration.
Selective cell capture and analysis using shallow antibody-coated microchannels
Authors: Jang Kihoon , Tanaka Yo , Wakabayashi Jun , Ishii Reina , Sato Kae , Mawatari Kazuma , Nilsson Mats , Kitamori Takehiko
Published: December 2012

Demand for analysis of rare cells such as circulating tumor cells in blood at the single molecule level has recently grown. For this purpose, several cell separation methods based on antibody-coated micropillars have been developed (e.g., Nagrath et al., Nature 450, 1235–1239 (2007)). However, it is difficult to ensure capture of targeted cells by these methods because capture depends on the probability of cell-micropillar collisions. We developed a new structure that actively exploits cellular flexibility for more efficient capture of a small number of cells in a target area. The depth of the sandwiching channel was slightly smaller than the diameter of the cells to ensure contact with the channel wall. For cell selection, we used anti-epithelial cell adhesion molecule antibodies, which specifically bind epithelial cells. First, we demonstrated cell capture with human promyelocytic leukemia (HL-60) cells, which are relatively homogeneous in size; in situ single molecule analysis was verified by our rolling circle amplification (RCA) method. Then, we used breast cancer cells (SK-BR-3) in blood, and demonstrated selective capture and cancer marker (HER2) detection by RCA. Cell capture by antibody-coated microchannels was greater than with negative control cells (RPMI-1788 lymphocytes) and non-coated microchannels. This system can be used to analyze small numbers of target cells in large quantities of mixed samples.
Quantum-memory-assisted entropic uncertainty relation with a single nitrogen-vacancy center in diamond
Authors: Xu Z. Y. , Zhu S. Q. , Yang W. L.
Published: December 2012

The limitation of simultaneous measurements of noncommuting observables can be eliminated when the measured particle is maximally entangled with a quantum memory. We present a proposal for testing this quantum-memory-assisted entropic uncertainty relation in a single nitrogen-vacancy (N-V) center in diamond only by local electronic measurements. As an application, this entropic uncertainty relation is used to witness entanglement between the electron and nuclear spins of the N-V center, which is close to reach the currently available technology.
High performance broadband absorber in the visible band by engineered dispersion and geometry of a metal-dielectric-metal stack
Authors: Zhu Peng , Jay Guo L.
Published: December 2012

We propose a nanostructured broadband absorber in the visible regime through designing the dispersion and geometry of a Cu/Si3N4/Cu stack. Two examples with nearly perfect absorption at different spectral ranges are designed based on the special dispersion relationship and fabricated using nanoimprint lithography. Experiments confirm an ultra flat average absorption greater than 80% from 400 nm to 700 nm. The robustness of the design with angle insensitive absorption characteristic is desirable for the applications in thin-film thermal emitters and photovoltaic cells.
Blur suppression in holographic imaging with use of surface plasmons
Authors: Ozaki M. , Kato J. , Kawata S.
Published: December 2012

Although holography has been used in a variety of fields, three-dimensional display application is still in the research and development stage. Extended sources, such as natural light, bulbs, and light-emitting diodes blur the reconstructed objects owing to the angular spread in light illumination onto a hologram. In this Letter, we discuss the suppression of image blur with the use of surface plasmons. Surface plasmons couple to a hologram only at a narrow angular range (∼0.68°) of extended-source illumination. Experimental results of the reconstruction of a rose pendant are shown to compare the blurring effect between plasmon and nonplasmon holograms.
Transformation volume strain in Ni-Mn-Ga thin films
Authors: Aseguinolaza I. R. , Reyes-Salazar I. , Svalov A. V. , Wilson K. , Knowlton W. B. , Müllner P. , Barandiarán J. M. , Villa E. , Chernenko V. A.
Published: December 2012

The temperature dependences of the lattice parameters and residual stress have been measured for a fine-grained Ni52.2Mn26.8Ga21.0 (at. %) thin film fabricated by sputter deposition onto a heated silicon wafer with SiNx buffer layer. The transformation volume strain in the film was found to be a lattice expansion during the forward martensitic transformation which is opposite to a volume contraction exhibited by bulk Ni-Mn-Ga alloys. This unusual effect can be explained by the substrate-induced residual stresses in the film and the difference in the elastic modulus of austenite and martensite.
Effects produced by iodine irradiation on high resistivity silicon
Authors: Lazanu S. , Slav A. , Lepadatu A.-M. , Stavarache I. , Palade C. , Iordache G. , Ciurea M. L.
Published: December 2012

The effects of 5 × 1011 cm−2 6+I127 ions of 28 MeV kinetic energy on high resistivity (100) Si were studied. The profile of primary defects was simulated. The defects produced by irradiation which act as traps were investigated. Thermally stimulated current measurements without externally applied bias were used, and for this the traps were charged by illuminating samples with 1000, 800, and 400 nm wavelengths. The discharge currents were recorded and modeled, and therefore the parameters of the traps were determined. The presence of I ions, heavier than Si, stopped into the target was modeled as a temperature independent electric field.
The effect of hydrogen desorption kinetics on thermionic emission from polycrystalline chemical vapor deposited diamond
Authors: Paxton W. F. , Steigerwald A. , Howell M. , Tolk N. , Kang W. P. , Davidson J. L.
Published: December 2012

Hydrogen influences many properties of diamond films, such as invoking negative electron affinity, inducing increased electron emission from diamond thermionic emitters. However, the thermionic emission diminishes at temperatures exceeding 750 °C. In this work, we observed the isothermal thermionic emission decrease followed first-order rate kinetics. Arrhenius examination indicated an activation energy consistent with values for the H-C bond at the surface derived from other works. Results obtained in this study establish a direct link between the presence of hydrogen and the degree of thermionic emission from diamond and is information relevant to the development of higher thermal emission from diamond.
Development of integrated habitat indices for bigeye tuna, Thunnus obesus, in waters near Palau
Authors: Li Yuwei , Song Liming , Nishida Tom , Gao Panfeng
Published: December 2012

A survey was conducted in waters near Palau in 2005, to improve our understanding of the relationship between environmental variables and the spatial distributions of Thunnus obesus. Catch rates and environmental variables (water temperature, salinity and dissolved oxygen) at six depth strata between 40 and 280 m were collected at 77 sampling stations in the survey. Models were developed to estimate an integrated habitat index (IHI) for T. obesus on the basis of quantile regression. The findings of the present study were as follows: (1) the performance of IHI models in predicting habitat utilisation by T. obesus was good, (2) the impacts of the weighted average temperature and dissolved oxygen were significant on the spatial distribution of T. obesus, (3) the influence of the environmental variables on T. obesus distribution differed among different depth strata, (4) the present study provides an effective approach to predict the spatial distribution of the pelagic fishes caught by longline and (5) the weighted average temperature and dissolved oxygen should be included in the T. obesus catch per unit effort (CPUE) standardisations.
Pluripotent cells in farm animals: state of the art and future perspectives
Authors: Nowak-Imialek Monika , Niemann Heiner
Published: December 2012

Pluripotent cells, such as embryonic stem (ES) cells, embryonic germ cells and embryonic carcinoma cells are a unique type of cell because they remain undifferentiated indefinitely in in vitro culture, show self-renewal and possess the ability to differentiate into derivatives of the three germ layers. These capabilities make them a unique in vitro model for studying development, differentiation and for targeted modification of the genome. True pluripotent ESCs have only been described in the laboratory mouse and rat. However, rodent physiology and anatomy differ substantially from that of humans, detracting from the value of the rodent model for studies of human diseases and the development of cellular therapies in regenerative medicine. Recently, progress in the isolation of pluripotent cells in farm animals has been made and new technologies for reprogramming of somatic cells into a pluripotent state have been developed. Prior to clinical application of therapeutic cells differentiated from pluripotent stem cells in human patients, their survival and the absence of tumourigenic potential must be assessed in suitable preclinical large animal models. The establishment of pluripotent cell lines in farm animals may provide new opportunities for the production of transgenic animals, would facilitate development and validation of large animal models for evaluating ESC-based therapies and would thus contribute to the improvement of human and animal health. This review summarises the recent progress in the derivation of pluripotent and reprogrammed cells from farm animals. We refer to our recent review on this area, to which this article is complementary.
Regulation of anti-Müllerian hormone production in domestic animals
Authors: Monniaux Danielle , Drouilhet Laurence , Rico Charlène , Estienne Anthony , Jarrier Peggy , Touzé Jean-Luc , Sapa Jean , Phocas Florence , Dupont Joëlle , Dalbiès-Tran Rozenn , Fabre Stéphane
Published: December 2012

In mammals, anti-Müllerian hormone (AMH) expression is detected in the granulosa cells of all growing follicles and is highest in healthy small antral follicles, which contribute most significantly to AMH endocrine levels. AMH is a reliable endocrine marker of this population of gonadotrophin-responsive follicles in ruminants and, over the longer term, plasma AMH concentrations are characteristic of individual animals. In the cow, plasma AMH concentrations follow specific dynamic profiles throughout the prepubertal period, the oestrous cycle and the change from gestation to the post partum period, with the alterations most likely reflecting numerical changes in the population of high AMH-producing follicles. In granulosa cells, bone morphogenetic proteins (BMP) enhance AMH gene expression and AMH synthesis, with these effects antagonised by FSH. BMP could both support follicular growth and contribute significantly to the induction and/or maintenance of AMH expression in small growing follicles. AMH expression decreases sharply in large follicles when they become oestrogenic, suggesting a role for FSH and/or oestradiol in these changes, but the underlying mechanisms remain hypothetical. A better understanding of the factors and mechanisms regulating AMH production is needed to propose new strategies for managing the reserve of primordial and small growing follicles, as well as for improving embryo production.
Associations between lipid metabolism and fertility in the dairy cow
Authors: Wathes D. Claire , Clempson Andrew M. , Pollott Geoff E.
Published: December 2012

Dairy cows mobilise body tissues to support milk production and, because glucose supplies are limited, lipids are used preferentially for energy production. Lipogenic activity is switched off and lipolytic mechanisms in adipose tissue increase through changes in the expression of several key enzymes. This results in a loss of body condition, together with high circulating concentrations of non-esterified fatty acids. Changes in the synthesis, secretion and signalling pathways of somatotrophic hormones (insulin, growth hormone, insulin-like growth factor 1) and adipokines (e.g. leptin) are central to the regulation of these processes. A high reliance on fatty acids as an energy source in the peripartum period causes oxidative damage to mitochondria in metabolically active tissues, including the liver and reproductive tract. The expression of genes involved in insulin resistance (PDK4, AHSG) is increased, together with expression of TIEG1, a transcription factor that can induce apoptosis via the mitochondrial pathway. Polymorphisms in TFAM and UCP2, two autosomal mitochondrial genes, have been associated with longevity in dairy cows. Polymorphisms in many other genes that affect lipid metabolism also show some associations with fertility traits. These include DGAT1, SCD1, DECR1, CRH, CBFA2T1, GH, LEP and NPY. Excess lipid accumulation in oocytes and the regenerating endometrium reduces fertility via reductions in embryo survival and increased inflammatory changes, respectively.
101 AMNIOTIC FLUID STEM SELLS IN BUFFALO (BUBALUS BUBALIS): IDENTIFICATION OF PLURIPOTENCY MARKERS, CHARACTERIZATION, AND GUIDED DIFFERENTIATION INTO NEUROGENIC, ADIPOGENIC, AND OSTEOGENIC LINEAGES
Authors: Gautam S. K. , Dev K. , Giri S. K. , Yadav A. , Singh B.
Published: December 2012

Amniotic fluid (AF) holds great promise as a stem-cell source. We report expression of various pluripotency molecular and immunocytochemical markers and chemically induced differentiation of bubaline (Bubalus bubalis) AF cells into neurogenic, adipogenic, and osteogenic lineages. Expression of pluripotecy-related markers, namely Oct-4 (also known as POU5F1), Sox-2, nestin, fibroblast growth factor (FGF-5), Nanog, alkaline phosphatase (AP), 18S rRNA, stem cell factor (SCF), cyclin A, β-actin, glyceraldehyde 3-phosphate dehydrogenase (GAPDH), and GATA-4, was observed in the cells, with amplicons of 314, 277, 307, 210, 317, 180, 162, 216, 421, 178, 180, and 334 bp, respectively. A semiquantitative real-time PCR analysis revealed the overexpression of Oct-4, Nanog, Sox-2, SCF, nestin, and FGF-5. Furthermore, the immunocytochemical staining confirmed the expression of Oct-4, Nanog, Sox-2, SSEA-1, SSEA-4, tumor rejection antigens (TRA-1-60 and TRA-1-81), and AP in AF cells. The undifferentiated cells were found to have a normal karyotype before and after their cryopreservation. We conclude that AF cells may contribute toward establishing nonembryonic pluripotent mesenchymal stem cells for various therapeutic and reproductive biotechnological applications in this species, and possibly in other livestock species.
119 QUANTITATIVE PROTEOME ANALYSIS OF ENDOMETRIUM FROM PREGNANT AND NONPREGNANT PIGS
Authors: Fröhlich T. , Kösters M. , Bauersachs S. , Samborski A. , Kessler B. , Wolf E. , Arnold G. J.
Published: December 2012

In mammals, an efficient exchange of molecular signals between the embryo and the maternal environment plays a crucial role for the implantation and development of early embryos as well as for recognition and maintenance of pregnancy. So far, only a few molecular signals involved in this process have been identified. To address the underlying biochemical processes in pigs at the protein level, we performed a quantitative proteome study with endometrial tissue samples from non-pregnant and pregnant (Day 14) sows. Endometrium samples (lamina epithelialis, lamina propria and tela submucosa; n = 4 per group) were taken from sites of embryonic attachment and from comparable locations in nonpregnant animals. Proteome data were generated by iTRAQ labelling and nano-LC-MS/MS measurements of tryptic endometrium peptides on a high-resolution Orbitrap XL mass spectrometer. To further address and visualize protein isoforms, LC-MS/MS experiments were complemented by 2D gel-based analyses. To enhance the accuracy of protein quantification, the 2D fluorescence difference gel electrophoresis (2D-DIGE) technique was used, including internal pooled standards for inter-gel matching and normalization. The statistical and bioinformatics analysis of 2D-DIGE and iTRAQ data revealed 14 proteins being significantly altered in abundance (fold-change values >1.5, maximum fold-change 13; P < 0.05) between the endometrium proteomes of pregnant and non-pregnant animals. Several of the affected proteins are already known to play an important role in embryo-maternal communication in other species; for example, signal transducer and activator of transcription 1 (STAT1), a protein mediating the cellular response of cells to interferons (IFN) or aldose reductase (AKR1B1), for which a key role in the synthesis of endometrial prostaglandin F is supposed. Several other proteins showing alterations in abundance between pregnant and nonpregnant endometrial tissues were not described previously and represent new and interesting targets for further functional studies addressing their role during early pregnancy.
12 PROGESTERONE SUPPLEMENTATION DAY 3 TO 5 POST-OVULATION IN AI-BRED MARES
Authors: Richard H. , Appleton P. , Kesler D. J. , Ferguson C. E.
Published: December 2012

The purpose of this study was to determine the effectiveness of increasing progesterone (P4) concentrations during early pregnancy, by supplementing a low dose of Regu-Mate® (Intervet, Millsboro, DE, USA) on Days 3, 4, and 5, post-ovulation to AI mares. Sixty-three AI-bred mares were randomly allocated to 1 of 2 treatment groups. All mares underwent ovulation induction using 1.5 mg mL–1 of deslorelin acetate (IM) following observation of ≥30-mm follicles and were inseminated with either fresh (n = 57) or cooled (n = 6) semen from fertile stallions approximately 24 h later. Ovulation was verified via ultrasonography in all mares. Mares allocated to the treatment group (n = 29) received altrenogest (Regu-Mate®) orally at a rate of 15 mg per day on Days 3, 4, and 5 following ovulation (d = 0), whereas control mares (n = 34) received no treatment. Blood samples were collected from all mares from Day 0 (ovulation) through Day 6 post-ovulation via jugular venipuncture. Pregnancies were determined via ultrasonography at 18 days post-ovulation. The pregnancy rate for untreated mares (18/34, 53%) was not different (P > 0.05) from altrenogest-treated mares (13/29, 45%). There was no difference (P > 0.50) in pregnancy rates when mares were AI bred 1 (19/39, 49%) or 2 (10/20, 50%) days from ovulation. The mean plasma P4 concentration on Day 5 was higher (P < 0.06) for pregnant control mares (4.75 ± 0.59 ng mL–1) compared with open control mares (3.50 ± 0.25 ng mL–1). There was a greater increase (P < 0.02) in plasma P4 concentrations (Day 5 – Day 1 concentration) in untreated pregnant mares (3.87 ± 0.56 ng mL–1) compared with untreated open mares (2.38 ± 0.22 ng mL–1). In conclusion, it was determined that altrenogest supplementation from Day 3 to 5 post-ovulation was ineffective in improving pregnancy rates. However, it is unknown if this was the result of the dose used or the length of supplementation. Additionally, the timing of altrenogest coincided with a significant increase in P4 in pregnant mares compared with open mares, indicating that the timing may be correct or there was action of an unknown embryonic luteotropin(s), which would describe the differences between P4 concentrations in pregnant versus open mares.
120 EXPRESSION OF TUMOR NECROSIS FACTOR (TNF) AND ITS RECEPTOR TNFR2 IN BOVINE ENDOMETRIUM AND EMBRYOS DURING THE EARLY DEVELOPMENT
Authors: Correia E. , Gómez E. , Caamaño J. N. , Díez C. , Balseiro A. , Martín D. , Carrocera S. , Trigal B. , Muñoz M.
Published: December 2012

Tumor necrosis factor alpha (TNF), a pleiotropic cytokine that could be involved in early embryo-maternal interactions (Muñoz et al. 2012 J. Proteome Res. 11, 751–766), binds to receptors TNFR1 and TNFR2. The TNFR2 mediates apoptotic and survival processes (Fischer et al. 2011 Cell. Signal. 23, 161–170) and its expression is hormonally regulated (Okuda et al. 2010 Mol. Cell. Endocrinol. 330, 41–48). In this work we analyzed the expression of TNFR2 by Western blot (WB) and immunocytochemistry (ICQ) and its co-localization with TNF by ICQ in bovine embryos and endometrium. Heifers that were transferred with multiple in vitro produced (IVP) embryos (n = 3) or sham transferred (n = 3) on Day 5 to horn ipsilateral to the corpus luteum were slaughtered on Day 8. Embryos were flushed and endometrial samples were collected from caruncular and intercaruncular regions in the middle and cranial horn thirds. Endometrial samples and Day 8 IVP embryos were subjected to ICQ, and the immunostaining pattern of TNFR2 and TNF was examined by confocal microscopy. Endometrial samples were also subjected to WB. Expression of TNRF2 was quantified by densitometry (immunoblots) and blind assessment (immunostaining). Data were analyzed using the GLM procedure of SAS Version 9.2 (SAS Institute Inc., Cary, NC, USA) and REGWQ test for means. Trophectoderm (TF) cells from blastocysts and uterine epithelial and stromal cells showed TNFR2 expression. TNF and TNRF2 were predominantly co-localised in embryos and endometrial samples, although occasionally they were detected independently. The presence of embryos increased TNFR2 in the basal glandular epithelia (P ≤ 0.05). Moreover, TNFR2 was higher in the intercaruncular than in the caruncular luminal epithelium (P = 0.07). The presence of embryos did not affect TNFR2 expression between cranial and middle horn thirds. However, the TNFR2 low-molecular-weight isoform (Lmw) in the caruncles and in the middle third of the uterine horn tended to increase in the presence of embryos (P ≤ 0.1). Interestingly, TNFR2 Lmw was more abundant in the middle caruncular region than in other endometrial regions (P < 0.05). Our findings suggest that TNF can mediate embryo-maternal communication in the uterus, acting both in the embryonic and maternal sides. In addition, although implantation does not begin in ruminants until elongation is complete, early bovine embryos seem to show an ability to interact with caruncles.
Project AGL2009-10059 (MICINN). M. Muñoz, A. Balseiro, B. Trigal, and E. Correia are sponsored by RYC08-03454, Contrato de Investigación para Doctores grant from INIA, Cajastur, and FPU (AP2009-5265), respectively.
145 EXTRA LIGHT EXPOSURE DECREASES DEVELOPMENT AND QUALITY OF PORCINE PARTHENOTE EMBRYOS
Authors: Li R. , Liu Y. , Pedersen H. , Kragh P. , Hyttel P. , Callesen H.
Published: December 2012

During in-vitro handling, oocytes and embryos are always exposed to light. This has been shown to affect embryonic development and quality in different species, i.e. hamster and mouse (Takenaka et al. 2007 PNAS, 104, 14 289–14 293) and human (Tatsuo et al. 2010 J. Assist. Reprod. Genet. 27, 93–96). However, similar experiments have not been made on porcine embryos, so our aim was to test effects of different types of light on the development and quality of porcine parthenote embryos. Cumulus–oocyte complexes from slaughterhouse-derived sow ovaries were aspirated and matured (38.5°C, 5% CO2, maximum humidity, 42 h). Parthenogenetic activation was made (Day 0) first by an electric pulse (1.26 kV cm–1, 80 µs) and then by incubation with 5 µg mL–1 cytochalasin B and 10 µg mL–1 cycloheximide in porcine zygote medium-3 (PZM-3) for 4 h. During these processes, the oocytes would be exposed to ~30 min of light. After activation, the oocytes were either directly cultured in incubator (0 h), or experimentally exposed to two types of light (DAY: near window, no direct sunlight; LAB: app. 40 cm from warm white lamps (12 V, 40 W) in PZM-3 while placed on a heating plate (38.5°C) with the culture dish covered by a crystal plastic foil filled with the appropriate gas (5% O2, 5% CO2) for different periods (1 h, 4 h, 24 h), and then cultured in PZM-3 in incubator. On Day 6, total and good blastocysts were counted. Good blastocysts were defined as blastocysts having expanded to 1.5 times the oocytes’ size, having cells of uniform color and distribution, and having formed a regular blastocyst cavity. The total number of cells and the apoptotic cells were detected on Day 6 blastocysts with TUNEL assay to evaluate embryonic quality. All statistics analysis were performed by ANOVA test (R). The results are summarized in Table 1. The developmental rates were decreased with both types of light: the decrease appeared earlier for good blastocyst rates, only after 1 h exposure; however, a clear adverse effect was also found on total blastocyst rates after 24 h exposure. The total cell number decreased after 4 h light exposure for both types of light. The rate of apoptotic cells tended to increase with both types of light (from approximately 7 to 9.5%) when embryos were exposed during 24 h, but no significant difference was found between groups. We conclude that the blastocyst morphology would be altered already after 1 h extra exposure to both light types, and their quality would further decrease after 4 h exposure. However, under normal working conditions, this should not represent a real problem.

Table 1.Effect of light exposure on development of porcine parthenote embryos
15 THE ADMINISTRATION OF GONADOTROPIN-RELEASING HORMONE AROUND THE FIRST POSTPARTUM MONTH INCREASES SUBSEQUENT REPRODUCTIVE PERFORMANCE IN DAIRY COWS
Authors: Jeong J. K. , Kang H. G. , Hur T. Y. , Kim I. H.
Published: December 2012

Early postpartum cyclicity is related to subsequent fertility. This field study evaluated the effect of gonadotropin-releasing hormone (GnRH) administration around the first postpartum month on subsequent reproductive performance in dairy cows. Holstein dairy cows underwent ultrasonography at 30.0 (±6) days postpartum to determine the existence of ovarian structures including corpus lutea (CL), follicles, or cysts. The cows without CL were divided randomly into 2 treatment groups: GnRH group and control group. Cows in the GnRH group received an injection of 100 µg of GnRH (gonadorelin, Godorel, Uni-Biotech Co. Ltd., Korea; n = 151). Cows in the control group received no GnRH (n = 171). Cows diagnosed with endometritis at the time of ultrasonography were excluded from this study. Cows received the normal herd reproductive management program including estrous detection or synchronization, or synchronization of ovulation in the breeding period. The voluntary waiting period from calving to first AI in this study was 40 days. Pregnancy was determined per rectum 60 days after AI by both ultrasonography and palpation. Reproductive performance data were collected for a minimum of 210 days postpartum. Reproduction data between the GnRH and control groups were evaluated by chi-square test or the Cox proportional hazard model with the PHREG procedure using the SAS program (version 9.1, SAS Institute Inc., Cary, NC, USA). The number of days to first insemination after calving did not differ (P > 0.05) between the control group (80.9 ± 2.2 days) and the GnRH group (82.1 ± 2.3 days), while the pregnancy rate to first insemination tended to be higher (P = 0.1) in the GnRH group (42.3%) than in the control group (33.3%). Furthermore, the pregnancy hazard was higher by 210 days in milk for the GnRH group compared with the control group (hazard ratio = 1.33; P < 0.05), which resulted in a 26-day reduction in the median interval to pregnancy. In conclusion, the administration of GnRH around the first postpartum month improved subsequent reproductive performance in dairy cows.
This work was carried out with the support of the Cooperative Research Program for Agriculture Science & Technology Development (project no. PJ008464) Rural Development Administration, Republic of Korea.