bluuebunny/crossref_metadata_2025 huggingface dataset:
Linear stability of circular micro- and nanowires with facets
Authors: Du Ping , Wong Harris
Published: June 2012

Micro- and nanowires are commonly used in biological sciences, micro- and nanoelectronics, and optoelectronics, and their morphological stability needs to be understood and controlled. We study the linear stability of equilibrium circular wires with length to diameter ratio of 1, 2, 3.5, 6, and 11, assuming that the wire surface can deform by capillarity-driven surface diffusion. The facetted equilibrium wire shape is modeled by the Dirac delta function and is perturbed by an infinitesimal axisymmetric disturbance, leading to an eigenvalue problem for the growth rate, which is solved by a finite-difference method. Numerical accuracy is checked by grid refinement. All converged eigenvalues are negative, indicating that the wires are linearly stable. The first six eigenvalues are listed for all the wires which show that, for the same eigenmode, the eigenvalue decreases in magnitude as the wire length increases. The eigenfunctions for the longest wire studied are plotted and reveal how a non-equilibrium wire finally approaches the equilibrium state. The linear-stability formulation is then extended to an infinitely-long circular wire. The wire is stable for all wavelengths if its surface coincides with a facet plane. Hence, Rayleigh’s instability is completely suppressed in faceted circular wires.
Production mechanism of atomic nitrogen in atmospheric pressure pulsed corona discharge measured using two-photon absorption laser-induced fluorescence
Authors: Teramoto Yoshiyuki , Ono Ryo , Oda Tetsuji
Published: June 2012

To study the production mechanism of atomic nitrogen, the temporal profile and spatial distribution of atomic nitrogen are measured in atmospheric pressure pulsed positive corona discharge using two-photon absorption laser-induced fluorescence. The absolute atomic nitrogen density in the streamer filaments is estimated from decay rate of atomic nitrogen in N2 discharge. The results indicate that the absolute atomic nitrogen density is approximately constant against discharge energy. When the discharge voltage is 21.5 kV, production yield of atomic nitrogen produced by an N2 discharge pulse is estimated to be 2.9 − 9.8 × 1013 atoms and the energy efficiency of atomic nitrogen production is estimated to be about 1.8 − 6.1 × 1016 atoms/J. The energy efficiency of atomic nitrogen production in N2 discharge is constant against the discharge energy, while that in N2/O2 discharge increases with discharge energy. In the N2/O2 discharge, two-step process of N2 dissociation plays significant role for atomic nitrogen production.
Suppression of a glassy magnetic state and emergence of a Griffiths-like phase on size reduction in Nd0.8Sr0.2MnO3
Authors: Kundu S. , Nath T. K.
Published: June 2012

A detailed study of the effect of grain size reduction on the spin glass like phase in Nd0.8Sr0.2MnO3 has been carried out. A rigorous measurement of linear and non-linear ac magnetic susceptibility in the bulk-like Nd0.8Sr0.2MnO3 confirms the existence of a glassy phase in the low temperature regime. The effect of size reduction on this glassy state is addressed here. This glassy phase is found to strongly destabilize on reduction of grain size down to a value of 42 nm. Based on our experimental results, the glassy phase has been attributed to the phase separation effect and interaction between the ferromagnetic clusters. The destabilization of this glassy phase has been argued to be due to the modification of the phase separated state on size reduction. Furthermore, the lowest grain size sample displays a Griffiths-like phase. The evidence of the emergence of this phase has been obtained from detailed dc and ac magnetization studies. We have explained our results through a phenomenological model.
Layer confinement effect on charge migration in polycarbonate/poly(vinylidene fluorid-co-hexafluoropropylene) multilayered films
Authors: Mackey Matthew , Schuele Donald E. , Zhu Lei , Baer Eric
Published: June 2012

Forced assembly microlayer coextrusion was used to produce polycarbonate/poly(vinylidene fluoride-co-hexafluoropropylene) [PC/P(VDF-HFP)] layered films for dielectric capacitor applications. Low field dielectric spectroscopy was systematically carried out on the layered films and controls. A low frequency relaxation was found that shifted to higher frequency and decreased in intensity as the P(VDF-HFP) layer thickness was reduced. The interfacial Maxwell-Wagner polarization, being layer thickness independent, could not account for this reduced low frequency relaxation behavior as the layer thickness decreased. Charge diffusion models by Sawada and Coelho, however, satisfactorily predicted the observed layer thickness effect, indicating that the migration of impurity ions in the P(VDF-HFP) layer caused the low frequency relaxation. A new, convenient fitting procedure was developed for the Sawada model yielding an ion concentration and diffusion coefficient of 2 × 1021 ions/m3 and 2 × 10−13 m2/s, respectively, for films with layer thicknesses of 430 to 50 nm. Thicker layers of 7000 nm had significantly different diffusion parameters, which were attributed to differing crystal orientations in the P(VDF-HFP) layers. These findings show that low ion concentrations, whether from catalyst residue and processing or intentionally added, significantly affect the dielectric properties and can play a vital role in many applications (i.e., LCD displays, solar cells, light-emitting electrochemical cells, capacitors).
Nano-domain engineering in ultrashort-period ferroelectric superlattices
Authors: Choi Taekjib , Ho Park Bae , Shin Hyunjung , Lee Jaichan
Published: June 2012

Ultrashort-period PbZrO3/PbTiO3 (PTO/PZO) ferroelectric/antiferroelectric superlattices are proposed for nano-domain engineering. They behaved like single ferroelectric metamaterials with monodomain excluding a 90° domain boundary, irrespective of their total thicknesses. Further, nanosized 180° domains, as small as ∼12 nm, were achieved by applying a short pulse voltage. Such domain structures of superlattices result from the lowering of the symmetry of supercell by specific atomic stacking in superlattices, contrary to the domain structures of ferroelectric thin films developed by the strain-induced ferroelectric instability. We suggest that ferroelectric superlattices with an ultrashort-period have a clear advantage for nano-domain engineering with greatly enhanced long term stability of the domains.
B-site ordering induced suppression of magnetic cluster glass and dielectric anomaly in La2−xBixCoMnO6
Authors: Bai Yijia , Liu Xiaojuan , Xia Yanjie , Li Hongping , Deng Xiaolong , Han Lin , Liang Qingshuang , Wu Xiaojie , Wang Zhongchang , Meng Jian
Published: June 2012

We report the heat, magnetic, and dielectric properties of La2−xBixCoMnO6 with a series of Bi doping concentrations, focusing especially on the impact of A-site doping on B-site ordering. We demonstrate that the B-site ordering is enhanced via the Bi doping, resulting in a suppressed cluster-glass behavior, larger dielectric constant, and smaller tangent loss. Surprisingly, a pronounced step-like dielectric anomaly turns up near the spin-freezing temperature in the Bi-free oxide, which is suppressed significantly after Bi doping. We attribute the suppression of anomaly to the lessened amount of antisite defects at the B sites and the associated strengthened electronic localization.
Solidification of Au-Cu-Si alloys investigated by a combinatorial approach
Authors: Ding Shiyan , Gregoire John , Vlassak Joost J. , Schroers Jan
Published: June 2012

Composition libraries of Au-Cu-Si films comprising 800 composition patches were fabricated through co-sputtering deposition from elemental targets. The gold composition varies between 47% (compositions are in atomic percentage) and 81%, copper between 8% and 40%, and silicon between 6% and 36% within the library. We designed and used a high-throughput optical characterization method to detect melting and solidification based on changes in the film’s contrast; further microscopy characterization reveals the microstructure. This approach reveals the composition dependence of the nucleation temperature and primary phase, which allows us to draw conclusions about glass forming ability and to identify bulk metallic glass forming compositions. Our solidification results suggest that the best glass forming composition coincides with the composition at which a transition from one primary phase to another occurs. We show that in general this transition is not at the eutectic composition but at the lowest nucleation temperature.
Ultra-broadband near-infrared emission in praseodymium ion doped germanium tellurite glasses for optical fiber amplifier operating at E-, S-, C-, and L-band
Authors: Liu X. , Chen B. J. , Pun E. Y. B. , Lin H.
Published: June 2012

An efficient method for achieving ultra-broadband near-infrared signal amplification is proposed employing potential Pr3+ doped UV-sensitive germanium tellurite (NZPGT) glass fiber. The corresponding 1D2 → 1G4 transition emission covers from 1280 to 1680 nm with a full-width at half-maximum of 140 nm, and the associated emission cross-sections at 1390 and 1485 nm are derived to be 2.62 × 10−21 and 7.41 × 10−21 cm2, respectively. Large emission cross-section profile of Pr3+ in NZPGT glasses reveals that effective broadband amplification, especially at E- and S-band, is reasonable to be expected. Practicable operating mechanism of potential Pr3+ doped NZPGT glass fiber offers favorable prospects for rare-earth ion single-doped ultra-broadband signal amplifier.
Single-cell adhesion probed in-situ using optical tweezers: A case study with Saccharomyces cerevisiae
Authors: Castelain Mickaël , Rouxhet Paul G. , Pignon Frédéric , Magnin Albert , Piau Jean-Michel
Published: June 2012

A facile method of using optical trapping to measure cell adhesion forces is presented and applied to the adhesion of Saccharomyces cerevisiae on glass, in contact with solutions of different compositions. Trapping yeast cells with optical tweezers (OT) is not perturbed by cell wall deformation or cell deviation from a spherical shape. The trapping force calibration requires correction not only for the hydrodynamic effect of the neighboring wall but also for spherical aberrations affecting the focal volume and the trap stiffness. Yeast cells trapped for up to 5 h were still able to undergo budding but showed an increase of doubling time. The proportion of adhering cells showed the expected variation according to the solution composition. The detachment force varied in the same way. This observation and the fact that the detachment stress was exerted parallel to the substrate surface point to the role of interactions involving solvated macromolecules. Both the proportion of adhering cells and the removal force showed a distribution which, in our experimental conditions, must be attributed to a heterogeneity of surface properties at the cell level or at the subcellular scale. As compared with magnetic tweezers, atomic force microscopy, and more conventional ways of studying cell adhesion (shear-flow cells), OT present several advantages that are emphasized in this paper.
ZnO/(ZnMg)O single quantum wells with high Mg content graded barriers
Authors: Laumer Bernhard , Schuster Fabian , Wassner Thomas A. , Stutzmann Martin , Rohnke Marcus , Schörmann Jörg , Eickhoff Martin
Published: June 2012

ZnO/Zn1−xMgxO single quantum wells (SQWs) were grown by plasma-assisted molecular beam epitaxy on c-plane sapphire substrates. Compositional grading allows the application of optimized growth conditions for the fabrication of Zn1−xMgxO barriers with high crystalline quality and a maximum Mg content of x = 0.23. High resolution x-ray diffraction reveals partial relaxation of the graded barriers. Due to exciton localization, the SQW emission is found to consist of contributions from donor-bound and free excitons. While for narrow SQWs with well width dW≤2.5nm, the observed increase of the exciton binding energy is caused by quantum confinement, the drop of the photoluminescence emission below the ZnO bulk value found for wide SQWs is attributed to the quantum-confined Stark effect. For a Mg content of x = 0.23, a built-in electric field of 630 kV/cm is extracted, giving rise to a decrease of the exciton binding energy and rapid thermal quenching of the SQW emission characterized by an activation energy of (24 ± 4) meV for dW = 8.3 nm.
Coherent averaging in the frequency domain
Authors: Khitrin A. K. , Xu Jiadi , Ramamoorthy Ayyalusamy
Published: June 2012

Quantum-mechanical evolution of systems with periodic time-modulated Hamiltonians is often described by effective interactions. Such average Hamiltonians, calculated as few terms of an expansion in powers of the interaction, are sometimes difficult to relate to experimental observations. We propose a frequency-domain approach to this problem, which offers certain advantages and produces an approximate solution for the density matrix, better linked to measurable quantities. The formalism is suitable for calculating the intensities of narrowed spectral peaks. Fast magic-angle-spinning NMR spectra of solids are used to experimentally illustrate the method.
Third-order electric-field-induced dipolar resonances from patterned barium-strontium-titanate thin-films
Authors: Toonen Ryan C. , Cole M. W.
Published: June 2012

Using microwave reflection spectroscopy, the complex permittivities of etch defined, 240 nm thick, (Ba0.6Sr0.4)TiO3, thin films have been measured over the frequency range of (1 to 4) GHz. Anomalous electric-field-induced electro-acoustic resonances were observed and characterized as a function of extrinsic electric field magnitude, ambient temperature, and sample diameter. The real and imaginary parts of the measured permittivities were fit to frequency-dependent functions derived from the Lorentz oscillator model. From these functions, extracted static dielectric constants were found to display excellent agreement with a closed-form expression derived by calculating third-order nonlinear susceptibility from the Landau-Devonshire-Ginzberg model.
A linear helicon plasma device with controllable magnetic field gradient
Authors: Barada Kshitish K. , Chattopadhyay P. K. , Ghosh J. , Kumar Sunil , Saxena Y. C.
Published: June 2012

Current free double layers (CFDLs) are localized potential structures having spatial dimensions – Debye lengths and potential drops of more than local electron temperature across them. CFDLs do not need a current for them to be sustained and hence they differ from the current driven double layers. Helicon antenna produced plasmas in an expanded chamber along with an expanding magnetic field have shown the existence of CFDL near the expansion region. A helicon plasma device has been designed, fabricated, and installed in the Institute for Plasma Research, India to study the role of maximum magnetic field gradient as well as its location with respect to the geometrical expansion region of the chamber in CFDL formation. The special feature of this machine consisting of two chambers of different radii is its capability of producing different magnetic field gradients near the physical boundary between the two chambers either by changing current in one particular coil in the direction opposite to that in other coils and/or by varying the position of this particular coil. Although, the machine is primarily designed for CFDL experiments, it is also capable of carrying out many basic plasma physics experiments such as wave propagation, wave coupling, and plasma instabilities in a varying magnetic field topology. In this paper, we will present the details of the machine construction, its specialties, and some preliminary results about the production and characterization of helicon plasma in this machine.
Magnetic bucket for rotating unmagnetized plasma
Authors: Katz Noam , Collins Cami , Wallace John , Clark Mike , Weisberg David , Jara-Almonte Jon , Reese Ingrid , Wahl Carl , Forest Cary
Published: June 2012

A new experiment is described which generates flow in unmagnetized plasma. Confinement is provided by a cage of permanent magnets, arranged to form an axisymmetric, high-order, multipolar magnetic field. This field configuration—sometimes called a “magnetic bucket”—has a vanishingly small field in the core of the experiment. Toroidal rotation is driven by J × B forces applied in the magnetized edge. The cross-field current that is required for this forcing flows from anodes to thermionic cathodes, which are inserted between the magnet rings. The rotation at the edge reaches 3 km/s and is viscously coupled to the unmagnetized core plasma. We describe the conditions necessary for rotation, as well as a 0-dimensional power balance used to understand plasma confinement in the experiment.
Low magnetisation alloys for in-plane spin transfer torque devices
Authors: Oguz K. , Ozdemir M. , Dur O. , Coey J. M. D.
Published: June 2012

Magnetic properties of thin films of three in-plane alloy systems, namely, Co40Ni40−xCrxB20, Co40Fe40−xNixB20, and Co40Fe40−xCrxB20 are investigated with a view to reducing the critical current density (jc) for spin transfer torque switching in MgO barrier magnetic tunnel junction nanopillars. In all three systems, the saturation magnetisation, Ms, decreases with increasing Cr or Ni substitution. The Co40Fe40−xCrxB20 alloy system is found to be the best in terms of reducing Ms, while maintaining a high tunnel magnetoresistance ratio. Ferromagnetic resonance experiments revealed that the damping coefficient of CoFeCrB alloy remains unchanged with increasing Cr content, but jc is reduced by a factor of four to 4.9 × 105 A/cm2 by using a Co40Fe32.7Cr7.3B20 free layer while maintaining a magnetoresistance of around 60 %.
Ion induced spinodal dewetting of thin solid films
Authors: Repetto Luca , Šetina Batič Barbara , Firpo Giuseppe , Piano Emanuele , Valbusa Ugo
Published: June 2012

We present experimental data and numerical simulations in order to show that the mechanism of spinodal dewetting is active during ion beam irradiation of thin solid films. The expected scaling law for the characteristic wavelengths versus the initial film thickness is modified by the presence of sputtering. The conclusion is fully supported by model simulation which shows a square law dependence for null sputtering yield and a bimodal trend when sputtering is included. This result is in contrast to earlier studies and opens the possibility to control and use ion induced dewetting for the fabrication of functional nanostructures.
Evidence of space charge limited flow in the gate current of AlGaN/GaN high electron mobility transistors
Authors: Xu Weikai , Rao Hemant , Bosman Gijs
Published: June 2012

Room temperature gate leakage current measurements as a function of gate bias voltage are reported for different AlGaN/GaN high electron mobility transistors and interpreted in terms of space charge limited flow in the presence of shallow traps through very small area conductive leakage paths already present or formed under electrical stress in the gate stack device area. Transport parameters for electrons following these paths are extracted, and the observation of gate electron velocity saturation in stressed devices indicates that newly created leakage paths form predominantly in high electric field gate edge regions.
Graphene/ZnO nanowire/graphene vertical structure based fast-response ultraviolet photodetector
Authors: Fu Xue-Wen , Liao Zhi-Min , Zhou Yang-Bo , Wu Han-Chun , Bie Ya-Qing , Xu Jun , Yu Da-Peng
Published: June 2012

We report the high performance vertical ultraviolet (UV) photodetectors based on single ZnO nanowire (NW) sandwiched between two graphene sheets. The photocurrent on-off ratio, rising time, and recovery speed of our UV detectors are 8 × 102, 0.7 s, and 0.5 s, respectively, which are significantly improved compared to the conventional ZnO NWs photodetectors. The improved performance is attributed to the existence of Schottky barriers between ZnO NW and graphene electrodes. The graphene/ZnO NW/graphene vertical sandwiched structures may be promising candidates for integrated optoelectronic sensor devices.
Triple-point-type morphotropic phase boundary based large piezoelectric Pb-free material—Ba(Ti0.8Hf0.2)O3-(Ba0.7Ca0.3)TiO3
Authors: Zhou Chao , Liu Wenfeng , Xue Dezhen , Ren Xiaobing , Bao Huixin , Gao Jinghui , Zhang Lixue
Published: June 2012

We report a large piezoelectric Pb-free system—Ba(Ti0.8Hf0.2)O3-(Ba0.7Ca0.3)TiO3, designed upon a triple-point morphotropic phase boundary (TMPB) idea. The system shows anomalies of both ac (dielectric and piezoelectric) and dc (P-E hysteresis) properties around TMPB, especially the d33 achieving ∼550 pC/N at room temperature. Moreover, the detected non-zero thermal hysteresis around triple point shows a first order transition nature and non-isotropic polarization state, as well as verified by our theoretical Landau-type deduction, thus being considered as an important factor to influence the piezoelectricity along TMPB. Our work may stimulate the study on triple-point-related critical phenomena in other ferroic systems.
Transparent conducting ZnO nanorods for nanoelectrodes as a reverse tunnel junction of GaN light emitting diode applications
Authors: Jin An Sung
Published: June 2012

We demonstrated transparent vertical aligned ZnO nanorod arrays for nanoelectrodes as a reverse-tunnel junction of GaN LEDs. GaN LEDs with ZnO nanorod arrays for nanoelectrodes demonstrated three times enhanced light output power compared with that of GaN LEDs with tunnel junction ZnO thin film, resulting from increased light extraction efficiency. Tunnel junction ZnO nanorod arrays for nanoelectrodes offer both high transparent current spreading layer for uniform current injection and easy method for high extraction efficiency.
Surface plasmon polariton-controlled tunable quantum-dot emission
Authors: Moerland R. J. , Rekola H. T. , Sharma G. , Eskelinen A.-P. , Väkeväinen A. I. , Törmä P.
Published: June 2012

The unique properties of surface plasmon polaritons, such as strong field confinement and local field enhancement effects, make them ideal candidates to enhance and shape the emission of luminescent nanoparticles. Of these nanoparticles, quantum dots are highly versatile, suitable for vastly different applications due to their size and material tunability. In many cases however, the emission wavelength of the quantum dots is fixed after manufacturing, allowing no control over the in situ emission properties. Here, we show fully optical, in situ tunability of the emission wavelength of quantum dots, with shifts of over 30 nm, employing surface plasmon polaritons to control the emission wavelength.
Tuning structural, electrical, and optical properties of oxide alloys: ZnO1−xSex
Authors: Mayer Marie A. , Yu Kin Man , Haller Eugene E. , Walukiewicz Wladek
Published: June 2012

Previously we showed that it is possible to narrow the band gap of zinc oxide from 3.3 to ∼2 eV through the addition of Se. Here, we use thin film samples of ZnO1−xSex grown by pulsed laser deposition to describe in detail the effect of growth parameters (temperature, pressure, and fluence) on the chemistry, structure, and optoelectronic properties of oxide alloys. We analyze the influences of temperature, laser fluence, and pressure during growth on the structure and composition of the films and define the parameter space in which homogeneous ZnO1−xSex alloy films can in fact be synthesized. Electronic transport in films grown under different conditions was characterized by resistivity, thermopower, and Hall effect measurements. We discuss how the electron affinity and native defects in polycrystalline oxide alloys enable reasonable mobilities (∼15 cm2/Vs) relative to their single crystalline counterparts. Finally, we elaborate on the model of optical structure in ZnO1−xSex and discuss the dependence of optical properties on growth temperature and fluence.
BioMercator V3: an upgrade of genetic map compilation and quantitative trait loci meta-analysis algorithms
Authors: Sosnowski Olivier , Charcosset Alain , Joets Johann
Published: June 2012

Summary: Compilation of genetic maps combined to quantitative trait loci (QTL) meta-analysis has proven to be a powerful approach contributing to the identification of candidate genes underlying quantitative traits. BioMercator was the first software offering a complete set of algorithms and visualization tool covering all steps required to perform QTL meta-analysis. Despite several limitations, the software is still widely used. We developed a new version proposing additional up to date methods and improving graphical representation and exploration of large datasets.

Availability and implementation: BioMercator V3 is implemented in JAVA and freely available (http://moulon.inra.fr/biomercator)

Contact:  joets@moulon.inra.fr
POOL server: machine learning application for functional site prediction in proteins
Authors: Somarowthu Srinivas , Ondrechen Mary Jo
Published: June 2012

Summary: We present an automated web server for partial order optimum likelihood (POOL), a machine learning application that combines computed electrostatic and geometric information for high-performance prediction of catalytic residues from 3D structures. Input features consist of THEMATICS electrostatics data and pocket information from ConCavity. THEMATICS measures deviation from typical, sigmoidal titration behavior to identify functionally important residues and ConCavity identifies binding pockets by analyzing the surface geometry of protein structures. Both THEMATICS and ConCavity (structure only) do not require the query protein to have any sequence or structure similarity to other proteins. Hence, POOL is applicable to proteins with novel folds and engineered proteins. As an additional option for cases where sequence homologues are available, users can include evolutionary information from INTREPID for enhanced accuracy in site prediction.

Availability: The web site is free and open to all users with no login requirements at http://www.pool.neu.edu.

Contact:  m.ondrechen@neu.edu

Supplementary Information:  Supplementary data are available at Bioinformatics online.
MobiDB: a comprehensive database of intrinsic protein disorder annotations
Authors: Di Domenico Tomás , Walsh Ian , Martin Alberto J.M. , Tosatto Silvio C.E.
Published: June 2012

Motivation: Disordered protein regions are key to the function of numerous processes within an organism and to the determination of a protein's biological role. The most common source for protein disorder annotations, DisProt, covers only a fraction of the available sequences. Alternatively, the Protein Data Bank (PDB) has been mined for missing residues in X-ray crystallographic structures. Herein, we provide a centralized source for data on different flavours of disorder in protein structures, MobiDB, building on and expanding the content provided by already existing sources. In addition to the DisProt and PDB X-ray structures, we have added experimental information from NMR structures and five different flavours of two disorder predictors (ESpritz and IUpred). These are combined into a weighted consensus disorder used to classify disordered regions into flexible and constrained disorder. Users are encouraged to submit manual annotations through a submission form. MobiDB features experimental annotations for 17 285 proteins, covering the entire PDB and predictions for the SwissProt database, with 565 200 annotated sequences. Depending on the disorder flavour, 6–20% of the residues are predicted as disordered.

Availability: The database is freely available at http://mobidb.bio.unipd.it/.

Contact:  silvio.tosatto@unipd.it
Functions of DNA methyltransferase 3‐like in germ cells and beyond
Authors: Liao Hung‐Fu , Tai Kang‐Yu , Chen Wendy S.‐C. , Cheng Luca C.W. , Ho Hong‐Nerng , Lin Shau‐Ping
Published: June 2012

DNA methyltransferase 3‐like (DNMT3L) is one of the key players in de novo DNA methylation of imprinting control elements and retrotransposons, which occurs after genome‐wide epigenetic erasure during germ cell development. In this review, we summarise the biochemical properties of DNMT3L and discuss the possible mechanisms behind DNMT3L‐mediated imprinting establishment and retrotransposon silencing in germ cells. We also discuss possible connections between DNMT3L and non‐coding RNA‐mediated epigenetic remodelling, the roles of DNMT3L in germ cell development and the implications in stem cell and cancer research.
Nitrogen dynamics in grain crop and legume pasture systems under elevated atmospheric carbon dioxide concentration: A meta‐analysis
Authors: Lam Shu K. , Chen Deli , Norton Rob , Armstrong Roger , Mosier Arvin R.
Published: June 2012

Understanding nitrogen (N) removal and replenishment is crucial to crop sustainability under rising atmospheric carbon dioxide concentration ([CO2]). While a significant portion of N is removed in grains, the soil N taken from agroecosystems can be replenished by fertilizer application and N2 fixation by legumes. The effects of elevated [CO2] on N dynamics in grain crop and legume pasture systems were evaluated using meta‐analytic techniques (366 observations from 127 studies). The information analysed for non‐legume crops included grain N removal, residue C : N ratio, fertilizer N recovery and nitrous oxide (N2O) emission. In addition to these parameters, nodule number and mass, nitrogenase activity, the percentage and amount of N fixed from the atmosphere were also assessed in legumes. Elevated [CO2] increased grain N removal of C3 non‐legumes (11%), legumes (36%) and C4 crops (14%). The C : N ratio of residues from C3 non‐legumes and legumes increased under elevated [CO2] by 16% and 8%, respectively, but the increase for C4 crops (9%) was not statistically significant. Under elevated [CO2], there was a 38% increase in the amount of N fixed from the atmosphere by legumes, which was accompanied by greater whole plant nodule number (33%), nodule mass (39%), nitrogenase activity (37%) and %N derived from the atmosphere (10%; non‐significant). Elevated [CO2] increased the plant uptake of fertilizer N by 17%, and N2O emission by 27%. These results suggest that N demand and removal in grain cropping systems will increase under future CO2‐enriched environments, and that current N management practices (fertilizer application and legume incorporation) will need to be revised.
The fraction of recombinant factor VIII:Ag unable to bind von Willebrand factor has no FVIII coagulant activity: studies in vitro
Authors: Ofosu F. A. , Tse H. , Naqvi A. , Bhakta H. , Song Y.
Published: June 2012

A fraction of FVIII:Ag in commercial recombinant FVIII (rFVIII) cannot bind VWF whereas all the FVIII:Ag in plasma‐derived FVIII (pd‐FVIII) concentrates does. To compare the FVIII:C activities of the fractions of rFVIII:Ag that can and cannot bind VWF. The FVIII:Ag contents of the rFVIII Kogenate, and Advate and a pd‐FVIII‐pd‐VWF (Fanhdi) were measured by ELISA. The FX activation was initiated by adding 1.0 IU of FVIII:C of each FVIII‐containing product to a coagulant phospholipids suspension containing 1.0 nm FIXa, 100 nm FX, 1 μm hirudin and 2 mm calcium chloride and measured after 1, 5 and 10 min. The same approach was followed after adding 2.0 IU of pd‐VWF to1.0 IU of FVIII:C of Kogenate or Advate. The FVIII:Ag content/IU of FVIII:C of Kogenate, Advate and Fanhdi were 1.80 ± 0.05, 1.31 ± 0.9 and 0.84 ± 1.5 IU respectively. Only Kogenate and Advate effectively enhanced FX activation 1 min after adding each FVIII:C to the coagulant suspension containing FIXa and FX. Thus, the FXa initially generated by FIXa readily activated FVIII:C in control Kogenate and Advate to thereby effectively enhance FX activation while the VWF in Fanhdi continued to suppress FX activation for up to 10 min. Addition of pd‐VWF to Kogenate or Advate effectively decreased their enhancements of FX activation to the same level as Fanhdi over 10 min. The FVIII:Ag fraction in Kogenate and Advate that cannot bind VWF appears to be inactive as it has no measureable FVIII:C activity in the presence of added VWF in vitro.
Bone histomorphometry using free and commonly available software
Authors: Egan Kevin P , Brennan Tracy A , Pignolo Robert J
Published: June 2012

Egan K P, Brennan T A & Pignolo R J  (2012) Histopathology Bone histomorphometry using free and commonly available software

Aims:  Histomorphometric analysis is a widely used technique to assess changes in tissue structure and function. Commercially available programs that measure histomorphometric parameters can be cost‐prohibitive. In this study, we compared an inexpensive method of histomorphometry to a current proprietary software program.

Methods and results:  Image J and Adobe Photoshop® were used to measure static and kinetic bone histomorphometric parameters. Photomicrographs of Goldner’s trichrome‐stained femurs were used to generate black‐and‐white image masks, representing bone and non‐bone tissue, respectively, in Adobe Photoshop®. The masks were used to quantify histomorphometric parameters (bone volume, tissue volume, osteoid volume, mineralizing surface and interlabel width) in Image J. The resultant values obtained using Image J and the proprietary software were compared and differences found to be statistically non‐significant.

Conclusions:  The wide‐ranging use of histomorphometric analysis for assessing the basic morphology of tissue components makes it important to have affordable and accurate measurement options available for a diverse range of applications. Here we have developed and validated an approach to histomorphometry using commonly and freely available software that is comparable to a much more costly, commercially available software program.
β‐Catenin and E‐cadherin expression in stage I adult‐type granulosa cell tumour of the ovary: correlation with tumour morphology and clinical outcome
Authors: Stewart Colin J R , Doherty Dorota , Guppy Rowan , Louwen Katherine , Leung Yee C
Published: June 2012

Aims:  To study E‐cadherin and β‐catenin expression in stage I adult‐type granulosa cell tumours (AGCTs) and correlate the findings with tumour morphology and clinical outcome.

Methods and results:  The study group comprised 62 FIGO stage I AGCTs, including 48 stage IA and 14 stage IC cases. Fifty patients (80.6%) had negative clinical follow‐up over periods from 3.0 to 19.2 years (median 6.4 years), and 12 patients (19.4%) developed metastases at intervals of 3.6–16.2 years (median 8.6 years). β‐Catenin and E‐cadherin were expressed in 62 (100%) and 53 (85%) primary tumours, respectively, and staining was more consistent and intense in areas showing sex cord‐like morphology. In contrast, diffuse tumour areas often showed weak or moderate staining (β‐catenin) or were negative (E‐cadherin), and there was reduced expression of both proteins in luteinized cells. Reduced β‐catenin expression in primary tumours correlated with increased risk of recurrence (P = 0.002) and a shorter time interval to recurrence, whereas there was no correlation between E‐cadherin staining and the risk of metastases.

Conclusions:  Localized variations in adhesion protein expression may partly explain the diverse morphological patterns exhibited by AGCT, and reduced β‐catenin staining in primary tumours may have value as an adverse prognostic factor.
Large‐scale bone mineral histomorphometry – report of a simplified technique
Authors: Karantzoulis Vasilis , Liapi Charis , Papaggelopoulos Panagiotis
Published: June 2012

Karantzoulis V, Liapi C & Papaggelopoulos P  (2012) Histopathology Large‐scale bone mineral histomorphometry – report of a simplified technique

Aims:  The aim of this study was the development of a simplified technique for bone mineral histomorphology on large undecalcified bone samples. Established techniques, such as undecalcified bone thin sectioning, ultrathin grinding, surface‐stained block grinding and micro‐computerized tomography (CT), are expensive, time‐consuming and put very high demands on equipment, safety standards, personnel and laboratory facilities.

Methods and results:  The method is based on the surface‐stained block‐grinding principle; however, its novelty lies in the selection of user‐friendly, safe and low‐cost materials, equipment and digitization techniques. We describe in detail the relevant steps, as well as many practical tips for their successful implementation: accurate bone cutting in thin sections with a customized arrangement on a commercial bandsaw, defatting with sodium hypochlorite, embedding in epoxy resin blocks at room temperature, silicon carbide paper grinding, von Kossa staining, flatbed scanner digitization and image processing.

Conclusion:  We believe that the proposed methodology could contribute to the expansion of the study of bone tissue, as it enables the rapid examination of bone specimens on a large scale with minimal laboratory requirements and consumables costs.
Current concepts in hypophosphatasia: case report and literature review
Authors: HOLLIS AMY , ARUNDEL PAUL , HIGH ALEC , BALMER RICHARD
Published: June 2012

International Journal of Paediatric Dentistry 2013; 23: 153–159

Background.  Hypophosphatasia (HP) is characterized by defective mineralization of bone and teeth because of deficient alkaline phosphatase activity. There are generally six recognized clinical forms, of which the most severe is often lethal prenatally or early in life. In milder forms, such as odontohypophosphatasia (OHP), premature exfoliation of primary teeth may be the only clinical manifestation.

Case Report.  A 20‐month‐old girl was referred to the Specialist Paediatric Salaried Dental Service within the Harrogate and District NHS Foundation Trust with mobility of tooth numbers 71 and 81. Clinical examination revealed grade III mobile 71 and 81, with minimal gingival inflammation and plaque deposits. There were no other dental findings and no significant medical history. Tooth numbers 71 and 81 exfoliated prematurely with no evidence of root resorption, shortly after presentation. Haematological and urinary investigations showed no abnormalities. Histological examination showed a complete absence of cementum. A diagnosis of OHP was made. After 10 months of dental follow‐up, no further teeth have increased mobility.

Conclusion.  Odontohypophosphatasia should be included as a differential diagnosis in children presenting with early loss of primary teeth. The dentist may be the first health care professional to whom the patient presents.
Information‐searching behaviors of main and allied health professionals: a nationwide survey in Taiwan
Authors: Weng Yi‐Hao , Kuo Ken N. , Yang Chun‐Yuh , Lo Heng‐Lien , Shih Ya‐Hui , Chiu Ya‐Wen
Published: June 2012

Rationale, aims and objectives  There are a variety of resources to obtain health information, but few studies have examined if main and allied health professionals prefer different methods. The current study was to investigate their information‐searching behaviours.

Methods  A constructed questionnaire survey was conducted from January through April 2011 in nationwide regional hospitals of Taiwan. Questionnaires were mailed to main professionals (physicians and nurses) and allied professionals (pharmacists, physical therapists, technicians and others), with 6160 valid returns collected.

Results  Among all professional groups, the most commonly used resource for seeking health information was a Web portal, followed by colleague consultations and continuing education. Physicians more often accessed Internet‐based professional resources (online databases, electronic journals and electronic books) than the other groups (P < 0.05). In contrast, physical therapists more often accessed printed resources (printed journals and textbooks) than the other specialists (P < 0.05). And nurses, physical therapists and technicians more often asked colleagues and used continuing education than the other groups (P < 0.01). The most commonly used online database was Micromedex for pharmacists and MEDLINE for physicians, technicians and physical therapists. Nurses more often accessed Chinese‐language databases rather than English‐language databases (P < 0.001).

Conclusions  This national survey depicts the information‐searching pattern of various health professionals. There were significant differences between and within main and allied health professionals in their information searching. The data provide clinical implications for strategies to promote the accessing of evidence‐based information.
Electromyographic power spectrum of jaw muscles during clenching in unilateral temporomandibular joint osteoarthritis patients
Authors: PARK I. H. , McCALL W. D. , CHUNG J. W.
Published: June 2012

Summary  The relationship between temporomandibular joints (TMJ) osteoarthritis and masticatory muscle disorders is poorly understood. The data are sparse, the results are conflicting, and electromyographic (EMG) power spectrum analysis has not been used. The aims of this study were to compare the differences in EMG power spectrum during, and pressure pain thresholds (PPTs) before and after, sustained clenching in patients with unilateral TMJ osteoarthritis and healthy control subjects. Nineteen patients with unilateral TMJ osteoarthritis without masticatory muscle pain and 20 control subjects were evaluated. We measured EMG amplitudes at maximum voluntary contraction, median frequency from the EMG power spectrum during sustained clenching at 70% and PPTs before and after the clenching in both temporalis and masseter muscles. There were no significant differences in PPT decrease between muscles or between groups during sustained clenching. There were no significant differences in maximum voluntary contraction EMG activity ratios of affected to unaffected sides between groups, or of masseter to temporalis muscles between affected and unaffected side of patients with TMJ osteoarthritis. Median frequencies decreased from the beginning to the end of the sustained clench, and the interaction between group and clench was significant: the median frequency decrease was larger in the osteoarthritis group. Our results suggested that masticatory muscles of patients with unilateral TMJ osteoarthritis are more easily fatigued during sustained clenching than normal subjects.
Effect of veneering technique on the fracture resistance of zirconia fixed dental prostheses
Authors: CHAAR M. S. , WITKOWSKI S. , STRUB J. R. , ATT W.
Published: June 2012

Summary  To compare the fracture resistance of zirconia 3‐unit posterior fixed dental prostheses (FDPs) frameworks veneered with different veneering materials and techniques before and after artificial ageing. Forty‐eight zirconia 3‐unit FDPs, representing a missing first molar, were adhesively cemented on human teeth. The zirconia frameworks were randomly distributed according to the veneering materials and techniques into three groups, each containing 16 samples: group LV (layering technique/Vintage ZR), group LZ (layering technique/ZIROX) and group PP (CAD/CAM and press‐over techniques/PressXZr). Half of each group was artificially aged through dynamic loading and thermocycling to simulate 5 years of clinical service. Afterwards, all specimens were tested for fracture resistance using compressive load. An analysis of variance (anova) was used to assess the effect of veneering ceramic and artificial ageing on fracture resistance (P < 0·05). Except for one minor cohesive chipping in group LV1, all specimens survived artificial ageing. The mean fracture resistance values (in Newton) of different non‐aged (± s.d.)/aged (± s.d.) groups were as follows: LV0 2034 (± 401)/LV1 1625 (± 291); LZ0 2373 (± 718)/LZ1 1769 (± 136); and PP0 1959 (± 453)/PP1 1897 (± 329). Artificial ageing significantly reduced the fracture resistance in groups veneered with the layering technique (P < 0·05), whereas no significant effect was found in specimens veneered with the CAD/CAM and press‐over techniques. All tested systems have the potential to withstand occlusal forces applied in the posterior region. The combination of the CAD/CAM and press‐over techniques for the veneering process improved the overall stability after artificial ageing, relative to the layering technique.
Impact of eLearning course on nurses' professional competence in seclusion and restraint practices: 9‐month follow‐up results of a randomized controlled study (ISRCTN32869544)
Authors: KONTIO R. , HÄTÖNEN H. , JOFFE G. , PITKÄNEN A. , LAHTI M. , VÄLIMÄKI M.
Published: June 2012

Accessible summary

eLearning may facilitate continuing vocational education, but data on the long‐term effects of eLearning course are lacking.

The aim of this study was to explore the long‐term impact of an eLearning course entitled ePsychNurse.Net on psychiatric nurses' professional competence in seclusion and restraint and on their job satisfaction and general self‐efficacy on the 9‐month follow‐up.

The results of 9‐month follow‐up showed that in its current form the ePsychNurse.Net (run 2009) did not boost short‐, nor long‐term competence – at least with the outcome measures used. The ePsychNurse.Net should be further developed and its future modifications will require additional studies, probably with some new outcome measures.

eLearning may facilitate continuing vocational education, but data on the long‐term effects of an eLearning course are lacking. The aim of this study was to explore the long‐term impact of an eLearning course entitled ePsychNurse.Net on psychiatric nurses' professional competence in practicing seclusion and restraint and on their job satisfaction and general self‐efficacy at 9‐month follow‐up. In a randomized controlled study, 12 wards were randomly assigned to the ePsychNurse.Net (intervention) or training as usual (control). Baseline and 9‐month follow‐up data on nurses' knowledge of coercion‐related legislation, physical restraint and seclusion, their attitudes towards physical restraint and seclusion, job satisfaction and general self‐efficacy were analysed for 137 completers (those who participated in the 9‐month follow‐up assessment). No between‐group differences were found on any variable, with the exception of a change in attitude to seclusion in favour of the control group. The findings of the long‐term effects did not differ from the immediate outcomes (3‐month follow‐up) and the improved level of knowledge acquired and further consolidation of that knowledge did not take place in the 6‐month period after the 3‐month ePsychNurse.Net course. The ePsychNurse.Net should be further developed and its future modifications will require additional studies, probably with some new outcome measures.
Mutations associated with occult hepatitis B virus infection result in decreased surface antigen expression in vitro
Authors: Martin C. M. , Welge J. A. , Rouster S. D. , Shata M. T. , Sherman K. E. , Blackard J. T.
Published: June 2012

Summary.  Occult hepatitis B virus (HBV) infection is characterized by the absence of detectable hepatitis B surface antigen (HBsAg) in the serum, despite detectable HBV DNA. Investigations of the mechanisms underlying the development of occult HBV infection are lacking in the current literature, although viral mutations in the surface region, resulting in decreased HBsAg expression or secretion, represent one potential mechanism. Wild‐type HBsAg expression vectors were constructed from genotype‐matched chronic HBV sequences. Site‐directed mutagenesis was then utilized to introduce three genotype A mutations – M103I, K122R and G145A – associated with occult HBV infection in vivo, alone and in combination, into the wild‐type HBsAg vectors. Transfection of Huh7 and HepG2 cell lines was performed, and cell culture supernatants and cell lysates were collected over 7 days to assess the effects of these mutations on extracellular and intracellular HBsAg levels. The G145A mutation resulted in significantly decreased extracellular and intracellular HBsAg expression in vitro. The most pronounced reduction in HBsAg expression was observed when all three mutations were present. The mutations evaluated in vitro in the current study resulted in decreased HBsAg expression and potentially increased hepatic retention and/or decreased hepatic secretion of synthesized HBsAg, which could explain the lack of HBsAg detection that is characteristic of occult HBV infection in vivo.