bluuebunny/crossref_metadata_2025 huggingface dataset:
Thermoelectric properties of PbTe with encapsulated bismuth secondary phase
Authors: Bali Ashoka , Royanian Esmaeil , Bauer Ernst , Rogl Peter , Chandra Mallik Ramesh
Published: March 2013

Lead Telluride (PbTe) with bismuth secondary phase embedded in the bulk has been prepared by matrix encapsulation technique. X-Ray Diffraction results indicated crystalline PbTe, while Rietveld analysis showed that Bi did not substitute at either Pb or Te site, which was further confirmed by Raman and X-Ray Photoelectron Spectroscopy. Scanning Electron Microscopy showed the expected presence of a secondary phase, while Energy Dispersive Spectroscopy results showed a slight deficiency of tellurium in the PbTe matrix, which might have occurred during synthesis due to higher vapor pressure of Te. Transmission Electron Microscopy results did not show any nanometer sized Bi phase. Seebeck coefficient (S) and electrical conductivity (σ) were measured from room temperature to 725 K. A decrease in S and σ with increasing Bi content showed an increased scattering of electrons from PbTe-Bi interfaces, along with a possible electron acceptor role of Bi secondary phase. An overall decrease in the power factor was thus observed. Thermal conductivity, measured from 400 K to 725 K, was smaller at starting temperature with increasing Bi concentration, and almost comparable to that of PbTe at higher temperatures, indicating a more important role of electrons as compared to phonons at PbTe-Bi interfaces. Still, a reasonable zT of 0.8 at 725 K was achieved for undoped PbTe, but no improvement was found for bismuth added samples with micrometer inclusions.
Power and heat-work conversion efficiency analyses for the irreversible Carnot engines by entransy and entropy
Authors: Zhou Bing , Cheng XueTao , Liang XinGang
Published: March 2013

The concepts of entransy and entropy are applied to the analyses of the irreversible Carnot engines based on the finite time thermodynamics. Taking the maximum output power and the maximum heat-work conversion efficiency (HWCE) as objectives, the applicability of the entransy theory and the entropy generation minimization method to the optimizations is investigated. For the entransy theory, the results show that the maximum entransy loss rate always relates to the maximum output power, while the maximum entransy loss coefficient always leads to the maximum HWCE for all the cases discussed in this paper. For the concept of entropy generation, the maximum entropy generation rate corresponds to the maximum output power when the Carnot engine works between infinite heat reservoirs, while the entropy generation number cannot be defined in this case. When the Carnot engine works between the finite heat reservoirs provided by streams, the minimum entropy generation rate corresponds to the maximum output power with prescribed heat flow capacity rates and inlet temperatures of the streams, while the minimum entropy generation number corresponds to the maximum HWCE. When the heat capacity flow rate of the hot stream is not prescribed, the entropy generation rate increases with increasing output power, while the entropy generation number decreases with increasing HWCE. When the inlet temperature of the hot stream is not prescribed, the entropy generation rate increases with increasing output power, and the entropy generation number also increases with increasing HWCE.
Topology of classical molecular optimal control landscapes in phase space
Authors: Joe-Wong Carlee , Ho Tak-San , Long Ruixing , Rabitz Herschel , Wu Rebing
Published: March 2013

Optimal control of molecular dynamics is commonly expressed from a quantum mechanical perspective. However, in most contexts the preponderance of molecular dynamics studies utilize classical mechanical models. This paper treats laser-driven optimal control of molecular dynamics in a classical framework. We consider the objective of steering a molecular system from an initial point in phase space to a target point, subject to the dynamic constraint of Hamilton's equations. The classical control landscape corresponding to this objective is a functional of the control field, and the topology of the landscape is analyzed through its gradient and Hessian with respect to the control. Under specific assumptions on the regularity of the control fields, the classical control landscape is found to be free of traps that could hinder reaching the objective. The Hessian associated with an optimal control field is shown to have finite rank, indicating the presence of an inherent degree of robustness to control noise. Extensive numerical simulations are performed to illustrate the theoretical principles on (a) a model diatomic molecule, (b) two coupled Morse oscillators, and (c) a chaotic system with a coupled quartic oscillator, confirming the absence of traps in the classical control landscape. We compare the classical formulation with the mathematically analogous quantum state-to-state transition probability control landscape.
Variations of composition and dielectric properties of Pb(In1/2Nb1/2)O3-Pb(Mg1/3Nb2/3)O3-PbTiO3 single crystal along growth direction
Authors: Wan Yuhui , Li Zhenrong , Chen Hongbing , Li Fei , Xu Zhuo , Fan Shiji , Yao Xi
Published: March 2013

The compositional dependent dielectric properties of [001]-poled Pb(In1/2Nb1/2)O3-Pb(Mg1/3Nb2/3)O3-PbTiO3 single crystal are investigated along the [011] growth direction. The variation of Pb(In1/2Nb1/2)O3, Pb(Mg1/3Nb2/3)O3, and PbTiO3 content of crystal boule with a length of 70 mm are found to be around 1.3%, 10.5%, and 9.9%, respectively. The rhombohedral-to-cubic or rhombohedral-to-tetragonal phase transition temperature is more than 120 °C for the composition with rhombohedral phase far away from the morphotropic phase boundary. The phase transition temperature of rhombohedral-to-tetragonal, rhombohedral-to-monoclinic/orthorhombic, and monoclinic/orthorhombic-to-tetragonal move to lower temperature and the tetragonal-to-cubic move to higher temperature along crystal growth direction. The tetragonal phase induced by [001]-poling, composition, and temperature can help to improve the piezoelectric properties and the induced monoclinic/orthorhombic phase can further improve and mainly contribute to the high piezoelectric properties. The phase diagram was established based on the composition and dielectric properties. At room temperature, the rhombohedral-monoclinic/orthorhombic phase boundary was found to be nearly PIN-PMN-0.34PT.
An air flow sensor for neonatal mechanical ventilation applications based on a novel fiber-optic sensing technique
Authors: Battista L. , Sciuto S. A. , Scorza A.
Published: March 2013

In this work, a simple and low-cost air flow sensor, based on a novel fiber-optic sensing technique has been developed for monitoring air flows rates supplied by a neonatal ventilator to support infants in intensive care units. The device is based on a fiber optic sensing technique allowing (a) the immunity to light intensity variations independent by measurand and (b) the reduction of typical shortcomings affecting all biomedical fields (electromagnetic interference and patient electrical safety). The sensing principle is based on the measurement of transversal displacement of an emitting fiber-optic cantilever due to action of air flow acting on it; the fiber tip displacement is measured by means of a photodiode linear array, placed in front of the entrance face of the emitting optical fiber in order to detect its light intensity profile. As the measurement system is based on a detection of the illumination pattern, and not on an intensity modulation technique, it results less sensitive to light intensity fluctuation independent by measurand than intensity-based sensors. The considered technique is here adopted in order to develop two different configurations for an air flow sensor suitable for the measurement of air flow rates typically occurring during mechanical ventilation of newborns: a mono-directional and a bi-directional transducer have been proposed. A mathematical model for the air flow sensor is here proposed and a static calibration of two different arrangements has been performed: a measurement range up to 3.00 × 10−4 m3/s (18.0 l/min) for the mono-directional sensor and a measurement range of ±3.00 × 10−4 m3/s (±18.0 l/min) for the bi-directional sensor are experimentally evaluated, according to the air flow rates normally encountered during tidal breathing of infants with a mass lower than 10 kg. Experimental data of static calibration result in accordance with the proposed theoretical model: for the mono-directional configuration, the coefficient of determination r2 is equal to 0.997; for the bi-directional configuration, the coefficient of determination r2 is equal to 0.990 for positive flows (inspiration) and 0.988 for negative flows (expiration). Measurement uncertainty δQ of air flow rate has been evaluated by means of the propagation of distributions and the percentage error in the arrangement of bi-directional sensor ranges from a minimum of about 0.5% at −18.0 l/min to a maximum of about 9% at −12.0 l/min.
Microwave probe for intrinsic parameters in a hybrid spin-nanoresonator system
Authors: Bin Wen , Zhu Ka-Di
Published: March 2013

Hybrid spin-mechanical systems are at present being actively explored for potential quantum-computing applications. In combination with the pump-probe techniques, we theoretically propose a scheme to measure the resonator frequency and coupling strength in a hybrid spin-mechanical resonator system which has a strong coherent coupling of an electronic spin of a single nitrogen vacancy center in diamond with a nanomechanical resonator. The probe absorption spectrum which exhibits new features such as mechanically induced three-photon resonance and ac Stark effect is obtained. Simultaneously, the coherent coupling strength between the quantized motion of a mechanical resonator and an isolated spin can also be detected from Rabi-splitting like peak in the probe spectrum. The microwave probe technique presented here will offer potential applications in spin-based quantum devices and quantum information processing.
Study of non-Markovian dynamics of a charged particle in presence of a magnetic field in a simple way
Authors: Baura Alendu , Ray Somrita , Kumar Sen Monoj , Chandra Bag Bidhan
Published: March 2013

In this paper, we have investigated the dynamics of a Brownian particle in the presence of a magnetic field. The present investigation is generalized considering different kinds of force fields, magnetic field, and non-Markovian thermal bath. The properties of the Brownian particle have been calculated based on the multi-dimensional Fokker-Planck description of stochastic processes. It leads to the study of non-Markovian dynamics of a Brownian particle in the presence of a magnetic field in a simple way. Using the present simple method, we have identified several important signatures of magnetic field and non-Markovian thermal bath in the dynamics.
Evaluation of InGaPN and GaAsPN materials lattice-matched to Si for multi-junction solar cells
Authors: Almosni S. , Robert C. , Nguyen Thanh T. , Cornet C. , Létoublon A. , Quinci T. , Levallois C. , Perrin M. , Kuyyalil J. , Pedesseau L. , Balocchi A. , Barate P. , Even J. , Jancu J. M. , Bertru N. , Marie X. , Durand O. , Le Corre A.
Published: March 2013

We compare the potentiality of bulk InGaPN and GaAsPN materials quasi-lattice-matched to silicon (Si), for multi-junction solar cells application. Bandgaps of both bulk alloys are first studied by a tight-binding model modified for nitrogen incorporation in diluted regimes. The critical thicknesses of those alloys are then calculated for various compositions. For the same lattice-mismatch and nitrogen amount, the bandgap of bulk GaAsPN is found to be closer to the targeted gap value of 1.7 eV for high efficiency tandem solar cell. GaPN and GaAsPN epilayers are then grown by molecular beam epitaxy on GaP substrate and studied by photoluminescence and X-ray diffraction. A GaAsPN bulk alloy emitting light at 1.77 eV at room temperature is obtained, demonstrating promising properties for further use in III-V/Si photovoltaic multijunction solar cells.
Neutron structural characterization and transport properties of oxidized and reduced La0.5Sr0.5M0.5Ti0.5O3 (M = Mn, Fe) perovskites: Possible electrode materials in solid-oxide fuel cells
Authors: Martínez-Coronado R. , Alonso J. A. , Aguadero A. , Perez-Coll D. , Fernández-Díaz M. T.
Published: March 2013

Oxygen-stoichiometric La0.5Sr0.5M0.5Ti0.5O3 (M = Mn, Fe) perovskites and the corresponding reduced specimens, of La0.5Sr0.5M0.5Ti0.5O3-δ composition, have been prepared and characterized by x-ray diffraction and neutron powder diffraction (NPD), in complement with thermal analysis, electrical conductivity, and thermal expansion measurements. NPD data show that these perovskites are all orthorhombic, space group Pbnm (No. 62). The total reduction of M3+ to M2+ in the reduced phases is accompanied with the occurrence of oxygen vacancies, which was confirmed by thermogravimetric analysis (TGA). Above room-temperature, these phases undergo two structural phase transitions studied in situ from NPD data; the former to a tetragonal (I4/mcm) structure, and the second one to a cubic (Pm-3m) phase. All the oxides display a semiconductor-like behavior with a maximum conductivity value of 15 S·cm−1 for the oxidized La0.5Sr0.5Mn0.5Ti0.5O3 phase at 850 °C. The measured thermal expansion coefficients perfectly match with the values usually displayed by solid-oxide fuel cell (SOFC) electrolytes. The obtained results present these perovskites as alternative electrodes for SOFCs.
Effect of growth temperature on ordering of two-dimensional square spin ice
Authors: John Greaves Simon , Muraoka Hiroaki
Published: March 2013

The growth of two-dimensional square spin ices at various temperatures was simulated. Slower growth rates and higher growth temperatures both increased the degree of ordering. Slightly better ordering was achieved by gradually increasing the temperature during growth, expanding the range of thicknesses over which thermal activation was able to reduce the energy of the island arrays.
Copper quantum dots on TiO2: A high-performance, low-cost, and nontoxic photovoltaic material
Authors: Sun Qiong , Sun Xianmiao , Dong Hongzhou , Zhang Qian , Dong Lifeng
Published: March 2013

The surface decoration of TiO2 with Cu quantum dots (QDs) was carried out through a simple chemical redox deposition method. The QDs in the form of Cu(I)/(II)-O-Ti(IV) network were attached tightly and highly dispersed onto the pre-sintered TiO2 surface, and no obvious change could be detected from the lattice and surface morphology of TiO2 after the modification. Quantum size effect was evidenced by diffuse reflectance spectra (DRS), from which the absorption spectrum extended from 380 nm to 440 nm. The concentration of Cu measured by energy-dispersive X-ray spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS) was higher than its theoretical value, a result which suggested that the QDs resided on the TiO2 surface and that the QD sensitization was primarily a surface process. In comparison to pure TiO2, the introduction of 1.0 wt. % Cu QDs increased the photocurrent density from 3.1 to 17.0 μA/cm2. Even a trace amount of Cu (only about 0.25 wt. %) can strongly enhance the photoelectric activity of TiO2. When excessive Cu was coated onto the TiO2 surface, the recombination of the photo-induced charges would be aggravated by the aggregation of QDs, and the growth of Cu grains made the bandgap of the QDs and TiO2 unmatched so that the photovoltaic conversion was restrained. Besides Cu QDs, the photoelectrical properties of TiO2 nanoparticles can be enhanced by the incorporation of other copper-based QDs (e.g., CuO, Cu2O, CuS, and Cu2S); the elementary Cu QDs demonstrated the best characteristics among them.
Plug-in electric vehicles as dispersed energy storage interactions with a smart office building
Authors: Dai Qian , Duan Shanxu , Cai Tao , Chen Changsong
Published: March 2013

Renewable energy resources (RESs) with plug-in electric vehicles (PEVs) are being gradually accepted by society for their low carbon emission merits. However, reverse power from the RES will result in the grid node's voltage rise and cause protection malfunction. As large amount of PEVs plug in the grid, their overall charging power tends to be uncertain due to their complex charging behavior. At the same time, if the renewable energy is integrated into the same grid, the gird will face a great technological challenge. In this paper, a smart building energy management system (SBEMS) is proposed to mitigate negative impact of RES and PEVs to power grid and optimize the operation of the building. The proposed SBEMS is also capable with PEVs system integration, photovoltaic (PV) power forecasting, optimization algorithm implementation, and environmental evaluation criteria. Since PV's output is sensitive to the meteorology, a 1-day-ahead power forecasting model is needed and presented. The economic system of PEVs is particularly complex, because it needs optimization across multiple time steps and is strongly influenced by tariff structures. Furthermore, the optimization problem to minimize the total building operational cost including PEVs charging cost is formulated while satisfying the supply and demand balance and complicated operating constraints of every energy supply equipment and devices. The simulation results have shown that the SBEMS can effectively reduce the PEVs charging cost, building operation cost, and the environment punishment fee. It is also important for the SBEMS to be responsible for the power grid operational indices. So the trade-off between economic consideration and load factor should be made. It is verified that the SBEMS is beneficial to the PEVs owners, building operator, environment, and grid.
Solar radiation on vertical surfaces for building application in different climate zones across China
Authors: Long Zhen , Li Huashan , Bu Xianbiao , Ma Weibin , Zhao Liang
Published: March 2013

The global concerns about energy consumption and environmental sustainability elevate the aspiration of applying solar energy to buildings. The information of solar radiation on the building envelope is important in designing the solar devices for building application. In this study, the solar radiation on the vertical surfaces in five major climate zones of China, viz. hot summer and warm winter, mild, hot summer and cold winter, cold, and severe cold, is investigated using the Klein and Theilacker's model with monthly average solar radiation measurements on a horizontal surface during 1971–2000. Guangzhou, Kunming, Wuhan, Beijing, and Harbin are selected as the representative cities in the five climate zones. The results show that the peak values of the total solar radiation on the vertical surface in each month occur at different orientations with the azimuth angles during ±90°. For annual utilization, the vertical surface due south is best for the five representative cities, and the deviation in azimuth angles within 45° can assure the reduction of the solar gain will never exceed 10%.
Probing polarization modes of Ag nanowires with hot electron detection on Au/TiO2 nanodiodes
Authors: Keun Lee Young , Lee Jaemin , Lee Hyosun , Lee Jung-Yong , Young Park Jeong
Published: March 2013

We report the effect of surface plasmons of silver nanowires (AgNWs) on the generation of hot electrons. The AgNWs were deposited on ultra-thin Au/TiO2 Schottky nanodiodes using a spraying method. As surface coverage of the AgNWs on the thin gold film increased, the short-circuit current under illumination increased, showing the effect of the AgNWs on the energy conversion efficiency. Detection of the hot electron flow enhanced by the AgNWs on the Au/TiO2 nanodiodes provides evidence of transverse (3.28 eV) and bulk silver (3.52 eV) plasmon modes that were confirmed by the measurement of the absorbance spectra of the AgNWs.
Doping for higher thermoelectric properties in p-type BiCuSeO oxyselenide
Authors: Lan Jin-Le , Zhan Bin , Liu Yao-Chun , Zheng Bin , Liu Yong , Lin Yuan-Hua , Nan Ce-Wen
Published: March 2013

The low power factor (PF) of BiCuSeO oxyselenide inhibits further improvement on thermoelectric figure of merit in the moderate temperature range. In this Letter, we show that the electron transport properties of doped BiCuSeO oxyselenide can be accurately described in acoustic phonon scattering assumption within the framework of single parabolic band model. It is further found that the doping elements alter the electron transport properties by tuning the effective mass and deformation potential. Based on these understandings, we argue that the higher power factor can be achieved by choosing the doping element based on reducing deformation potential coefficient and decreasing effective mass.
Molecular dynamics of ion transport through the open conformation of a bacterial voltage-gated sodium channel
Authors: Ulmschneider Martin B. , Bagnéris Claire , McCusker Emily C. , DeCaen Paul G. , Delling Markus , Clapham David E. , Ulmschneider Jakob P. , Wallace B. A.
Published: March 2013

The crystal structure of the open conformation of a bacterial voltage-gated sodium channel pore from
Magnetococcus sp
. (NaVMs) has provided the basis for a molecular dynamics study defining the channel’s full ion translocation pathway and conductance process, selectivity, electrophysiological characteristics, and ion-binding sites. Microsecond molecular dynamics simulations permitted a complete time-course characterization of the protein in a membrane system, capturing the plethora of conductance events and revealing a complex mixture of single and multi-ion phenomena with decoupled rapid bidirectional water transport. The simulations suggest specific localization sites for the sodium ions, which correspond with experimentally determined electron density found in the selectivity filter of the crystal structure. These studies have also allowed us to identify the ion conductance mechanism and its relation to water movement for the NavMs channel pore and to make realistic predictions of its conductance properties. The calculated single-channel conductance and selectivity ratio correspond closely with the electrophysiology measurements of the NavMs channel expressed in HEK 293 cells. The ion translocation process seen in this voltage-gated sodium channel is clearly different from that exhibited by members of the closely related family of voltage-gated potassium channels and also differs considerably from existing proposals for the conductance process in sodium channels. These studies simulate sodium channel conductance based on an experimentally determined structure of a sodium channel pore that has a completely open transmembrane pathway and activation gate.
Increased axonal bouton dynamics in the aging mouse cortex
Authors: Grillo Federico W. , Song Sen , Teles-Grilo Ruivo Leonor M. , Huang Lieven , Gao Ge , Knott Graham W. , Maco Bohumil , Ferretti Valentina , Thompson Dawn , Little Graham E. , De Paola Vincenzo
Published: March 2013

Significance

Synaptic plasticity is considered an essential process for the formation and maintenance of memory. It had been assumed for decades that cognitive deficits within the aging brain result from reduced synaptic density and plasticity. By imaging axonal arbors and boutons in the aged brain, we surprisingly find the opposite, i.e., dramatically increased rates of synapse formation, elimination, and destabilization in specific cortical circuits. This observation suggests that learning and memory deficits in the aged brain may arise not through an inability to form new synapses but rather through decreased synaptic tenacity.
Social Connection and Seeing Human
Authors: Waytz Adam
Published: April 2013

Given that the motivation to affiliate with others is one of the most fundamental and important motivations, humans have developed a variety of strategies to cope with lack of affiliation following experiences of social exclusion. One strategy is anthropomorphism, whereby people create social connection by treating nonhumans as human-like agents capable of social support. This chapter reviews evidence that social exclusion increases the tendencies to anthropomorphize and to seek social connection with nonhumans. It also addresses three questions that follow from people’s tendency to anthropomorphize as a means to attain social connection: (1) Is social connection with nonhumans effective? (2) Does connection with nonhumans diminish interest in connections with humans? (3) Could increases in social connection in fact increase dehumanization of other people? In attempting to answer these questions, this chapter provides avenues for future research on the relationship between social connection and seeing human.
Development of Primers and Probes for Genus and Species Specific Detection of ‘Candidatus Liberibacter Species’ by Real-Time PCR
Authors: Ananthakrishnan G. , Choudhary N. , Roy Avijit , Sengoda V. G. , Postnikova E. , Hartung J. S. , Stone A. L. , Damsteegt V. D. , Schneider W. L. , Munyaneza J. E. , Brlansky R. H.
Published: April 2013

Huanglongbing (HLB), also known as citrus greening, is currently the most devastating disease impacting citrus production. The disease is associated with three different ‘Candidatus Liberibacter species’, ‘Ca. Liberibacter asiaticus’, ‘Ca. Liberibacter americanus’, and ‘Ca. Liberibacter africanus’, which induce similar and overlapping symptoms. When HLB-symptomatic trees are tested, one of the Candidatus Liberibacters is normally detected by conventional or real-time PCR (qPCR). The most widely used assays use primers and probes based on the 16S ribosomal RNA (rRNA) gene. The 16S rRNA-based assays to detect the three species are species-specific and must be performed sequentially. We describe a single assay that detected all species of ‘Ca. Liberibacter’ at the genus level, providing increased convenience. Recent molecular analyses of ‘Ca. Liberibacter species’ and other bacteria suggest that the rpoB gene (encoding the β-subunit of RNA polymerase) provides an alternative target for bacterial identification. We report here the design of a single pair of degenerate primers and a hybridization probe corresponding to the rpoB region and their application for the detection of all three citrus ‘Ca. Liberibacter species’, enabling detection of ‘Ca. Liberibacter’ at the genus level. In addition, species-specific primers and probes based on the rplJ/rplK genes were designed and used for detection at the species level in a multiplexed format. Both the genus- and species-specific assays were validated in both SYBR Green I and TaqMan formats, and with both plant and insect extracts that contained the pathogen. These one-step qPCR diagnostic methods are useful for the detection of all species of Liberibacter infecting citrus. In addition, the degenerate genus-specific primers and probe successfully detected ‘Ca. Liberibacter solanacearum’, a psyllid-transmitted pathogen associated with disease in tomato, carrot, and potato.
Highly comparative time-series analysis: the empirical structure of time series and their methods
Authors: Fulcher Ben D. , Little Max A. , Jones Nick S.
Published: April 2013

The process of collecting and organizing sets of observations represents a common theme throughout the history of science. However, despite the ubiquity of scientists measuring, recording and analysing the dynamics of different processes, an extensive organization of scientific time-series data and analysis methods has never been performed. Addressing this, annotated collections of over 35 000 real-world and model-generated time series, and over 9000 time-series analysis algorithms are analysed in this work. We introduce reduced representations of both time series, in terms of their properties measured by diverse scientific methods, and of time-series analysis methods, in terms of their behaviour on empirical time series, and use them to organize these interdisciplinary resources. This new approach to comparing across diverse scientific data and methods allows us to organize time-series datasets automatically according to their properties, retrieve alternatives to particular analysis methods developed in other scientific disciplines and automate the selection of useful methods for time-series classification and regression tasks. The broad scientific utility of these tools is demonstrated on datasets of electroencephalograms, self-affine time series, heartbeat intervals, speech signals and others, in each case contributing novel analysis techniques to the existing literature. Highly comparative techniques that compare across an interdisciplinary literature can thus be used to guide more focused research in time-series analysis for applications across the scientific disciplines.
Polymorphisms at the innate immune receptorTLR2are associated withBorreliainfection in a wild rodent population
Authors: Tschirren Barbara , Andersson Martin , Scherman Kristin , Westerdahl Helena , Mittl Peer R. E. , Råberg Lars
Published: April 2013

The discovery of the key role of Toll-like receptors (TLRs) in initiating innate immune responses and modulating adaptive immunity has revolutionized our understanding of vertebrate defence against pathogens. Yet, despite their central role in pathogen recognition and defence initiation, there is little information on how variation inTLRsinfluences disease susceptibility in natural populations. Here, we assessed the extent of naturally occurring polymorphisms atTLR2in wild bank voles (Myodes glareolus) and tested for associations betweenTLR2variants and infection withBorrelia afzelii, a common tick-transmitted pathogen in rodents and one of the causative agents of human Lyme disease. Bank voles in our population had 15 differentTLR2haplotypes (10 different haplotypes at the amino acid level), which grouped in three well-separated clusters. In a large-scale capture–mark–recapture study, we show that voles carryingTLR2haplotypes of one particular cluster (TLR2c2) were almost three times less likely to beBorreliainfected than animals carrying other haplotypes.Moreover, neutrality tests suggested thatTLR2has been under positive selection. This is, to our knowledge, the first demonstration of an association betweenTLRpolymorphism and parasitism in wildlife, and a striking example that genetic variation at innate immune receptors can have a large impact on host resistance.
Marinoscillum luteum sp. nov., isolated from marine sediment
Authors: Cha In-Tae , Park Soo-Je , Kim So-Jeong , Kim Jong-Geol , Jung Man-Young , Shin Kee-Sun , Kwon Kae Kyoung , Yang Sung-Hyun , Seo Yong-Seok , Rhee Sung-Keun
Published: March 2013

A novel strain, designated SJP7T, was isolated from sediment of the Tofua Arc of the Tonga Trench. The 16S rRNA gene sequence of the isolate showed the highest similarity to that ofMarinoscillum pacificumKCCM 42325T(95.9 %). Phylogenetic analysis revealed that the isolate formed a distinct phyletic line withMarinoscillum pacificumKCCM 42325TandMarinoscillum furvescensLMG 13023Twithin the familyCytophagaceae. Cells of strain SJP7Twere Gram-stain-negative and appeared as long rods that were motile by gliding. Growth was observed at 15–40 °C (optimum, 30 °C), at pH 5.5–9.0 (optimum, pH 7.5–8.0) and in the presence of 0.5–7.0 % (w/v) NaCl (optimum, 2.5–3 %). The major respiratory quinone was MK-7. The dominant fatty acids were summed feature 3 (comprising C16 : 1ω7cand/or C16 : 1ω6c), iso-C15 : 0and C16 : 1ω5c. The DNA G+C content was 43.5 mol%. These properties support the affiliation of strain SJP7Twith the genusMarinoscillum. Further phenotypic differentiation of strain SJP7Tfrom other species of the genusMarinoscillumwas indicated by the results of physiological and biochemical tests. On the basis of evidence from our polyphasic taxonomic study, strain SJP7Trepresents a novel species of the genusMarinoscillum, for which the nameMarinoscillumluteumsp. nov. is proposed. The type strain ofMarinoscillumluteumis SJP7T( = KCTC 23939T = NCAIM B02491T).
Algibacter

agarivorans sp. nov. and

Algibacter

agarilyticus sp. nov., isolated from seawater, reclassification of

Marinivirga aestuarii

as

Algibacter

aestuarii comb. nov. and emended description of the genus

Algibacter
Authors: Park Seong Chan , Hwang Yeoung Min , Lee Ji Hee , Baik Keun Sik , Seong Chi Nam
Published: March 2013

Two yellow-pigmented, rod-shaped, non-motile, Gram-reaction-negative and aerobic bacterial strains, designated KYW560T and KYW563T, were isolated from seawater collected from Gwangyang Bay, Republic of Korea. The isolates required sea salts for growth. Flexirubin-type pigments were absent. The common major cellular fatty acids (>5 % of total) of the two strains were C16 : 0, C18 : 0, iso-C15 : 0, anteiso-C15 : 0, iso-C15 : 1 G, iso-C17 : 0 3-OH and summed feature 3 (C16 : 1ω6c and/or C16 : 1ω7c). Strain KYW560T also contained iso-C15 : 0 3-OH and C20 : 1ω9c as major fatty acids. The main polar lipids were phosphatidylethanolamine, an unidentified aminolipid and two unidentified lipids. The predominant isoprenoid quinone was MK-6. The DNA G+C contents of strains KYW560T and KYW563T were 41.0±0.7 and 38.3±0.4 mol% (mean±sd of three determinations), respectively. Phylogenetic analysis based on 16S rRNA gene sequences indicated that the isolates belonged to the family

Flavobacteriaceae

, and were related to the genus

Algibacter

. Based on data from this taxonomic study using a polyphasic approach, it is proposed that the isolates represent novel species of the genus

Algibacter

, for which the names

Algibacter

agarivorans sp. nov. (type strain, KYW560T = KCTC 23855T = JCM 18285T) and

Algibacter

agarilyticus sp. nov. (type strain, KYW563T = KCTC 23857T = JCM 18275T) are proposed. Reclassification of

Marinivirga aestuarii

as

Algibacter

aestuarii comb. nov. and emended description of the genus

Algibacter

are also proposed.
Interlocking Feedback Loops Govern the Dynamic Behavior of the Floral Transition inArabidopsis
Authors: Jaeger Katja E. , Pullen Nick , Lamzin Sergey , Morris Richard J. , Wigge Philip A.
Published: March 2013

During flowering, primordia on the flanks of the shoot apical meristem are specified to form flowers instead of leaves. Like many plants, Arabidopsis thaliana integrates environmental and endogenous signals to control the timing of reproduction. To study the underlying regulatory logic of the floral transition, we used a combination of modeling and experiments to define a core gene regulatory network. We show that FLOWERING LOCUS T (FT) and TERMINAL FLOWER1 (TFL1) act through FD and FD PARALOG to regulate the transition. The major floral meristem identity gene LEAFY (LFY) directly activates FD, creating a positive feedback loop. This network predicts flowering behavior for different genotypes and displays key properties of the floral transition, such as signal integration and irreversibility. Furthermore, modeling suggests that the control of TFL1 is important to flexibly counterbalance incoming FT signals, allowing a pool of undifferentiated cells to be maintained despite strong differentiation signals in nearby cells. This regulatory system requires TFL1 expression to rise in proportion to the strength of the floral inductive signal. In this network, low initial levels of LFY or TFL1 expression are sufficient to tip the system into either a stable flowering or vegetative state upon floral induction.
Hypoxia‐inducible factor and signal transducer and activators of transcription 3: two central regulators meet to regulate kidney pathophysiology
Authors: Nakayama Koh , Nangaku Masaomi
Published: March 2013

See original article on page 262
Do intravenous and subcutaneous angiotensin II increase blood pressure by different mechanisms?
Authors: Campbell Duncan J
Published: March 2013

Angiotensin (Ang) II plays a key role in blood pressure regulation. Mechanisms of the pressor effect of chronic intravenous AngII administration include vasoconstriction, stimulation of the sympathetic nervous system and aldosterone production, as well as direct effects on renal excretion of sodium and water.

 Chronic AngII administration by subcutaneous minipump at doses higher than required to increase blood pressure by the intravenous route has identified additional pressor mechanisms, including the immune system, cytokines and matrix metalloproteinases. However, pressor doses of subcutaneous AngII may exceed the angiotensinogen synthesis rate and produce inflammation, fibrosis and necrosis of skin overlying the minipump.

 Evidence that chronic subcutaneous and intravenous AngII increase blood pressure by different mechanisms includes the prevention of the pressor effects of subcutaneous, but not intravenous, AngII by angiotensin‐converting enzyme inhibition. Furthermore, low doses of subcutaneous AngII reduce blood pressure of female, but not male, rodents and higher doses are less pressor in females than in males, whereas intravenous AngII is equally pressor in males and females.

 Pressor doses of chronic subcutaneous AngII produce greater weight loss, anorexia and reduced kidney weight and cause greater vascular, cardiac and renal pathology than equally pressor doses of chronic intravenous AngII.

 The different effects of chronic intravenous and subcutaneous AngII suggest that these two models of hypertension give different information and may differ in their relevance to blood pressure regulation in physiological and pathological states such as hypertension in humans.
Presence of Oxytocin, Vasopressin and Atrial Natriuretic Peptide and Their Modification in Rat Hypothalamic Paraventricular Nucleus During Resistance Training
Authors: Farina E. V. , Cappello F. , Lipari L. , Valentino A. , Di Felice V. , Valentino B.
Published: April 2013

Many studies have demonstrated the physiological effects of oxytocin (OT), atrial natriuretic peptide (ANP) and vasopressin (VP) in the homoeostasis of body fluids during physical exercise. However, a little information is available about the related immunohistochemical changes in hypothalamic magnocellular neurosecretory system during and after the training. The aim of the present work was to study the immunohistochemical changes in OT, ANP and VP levels in the hypothalamic paraventricular nucleus during and after resistance exercise protocol. Three groups of Wistar rats were trained by a rung ladder protocol for 15, 30 and 45 days, respectively; a fourth group was left to rest for 15 days after the training. Finally, four sedentary groups were used as controls. The results show that resistance training induces a significant reduction in the percentage of OT‐positive neurons, compared with sedentary controls. In contrast, this protocol did not induce any change in VP levels, and ANP levels did not change significantly. However, VP increased after the resting period of 15 days. Our work shows that neurons of the paraventricular nucleus are involved in body fluid homoeostasis during and after resistance exercise. The functional significance of these changes in OT and VP levels, during and after the protocol, needs to be further investigated.
Soil biota of different size classes change the impact of soil compaction on a plant community
Authors: Beck Mara E. , Wurst Susanne
Published: March 2013

Question

Does a reduction in size class of soil biota aggravate the impacts of soil compaction on plant communities?

Location

Controlled mesocosm study with a European ruderal plant community exposed to soil compaction and soil biota communities of different size classes.

Methods

We evaluated the individual and combined effects of soil compaction and soil biota communities of different size classes (<2000, <212, <20 μm, natural control) on the structure and productivity of a ruderal plant community, and the establishment of a neophyte (Lupinus polyphyllus) in a full‐factorial mesocosm study.

Results

Soil compaction reduced the productivity of the plant community, but the negative effect decreased in magnitude as the size class of the soil biota community was reduced. Consistently, shoot growth of the dominant grasses was most reduced by soil compaction when bigger soil biota were present; the shoot growth of forbs showed an opposite pattern. In contrast, legumes seem to profit from soil compaction independent of the size class of the soil biota community, and were detrimentally affected only in the natural control soil. Establishment of the neophyte L. polyphyllus was best under natural soil conditions and was not affected by soil compaction.

Conclusions

A reduction in soil biota size due to intensified management may change the impacts of soil compaction on plant communities. The results indicate that soil compaction has the most detrimental effect on primary productivity in soil communities where a range of size classes of soil biota is present and the functional complexity of the soil biota community is therefore high.
A randomized and controlled clinical trial of two different compositions of deproteinized bovine bone and autogenous bone used for lateral ridge augmentation
Authors: Mordenfeld Arne , Johansson Carina B. , Albrektsson Tomas , Hallman Mats
Published: April 2013

Objective

The aim of the study was to radiologically and histologically evaluate the graft healing and volumetric changes after lateral augmentation with two different compositions of deproteinized bovine bone (DPBB) and autogenous bone (AB).

Material and methods

Thirteen patients with a mean age of 59.6 ± 12.1 years (six men and seven women) were included in this randomized and controlled trial, designed as a split‐mouth study. Ten edentulous and four partially edentulous jaws with an alveolar ridge width of ≤4 mm were laterally augmented with a graft composition of 60 : 40 (DPBB/AB) on one side and 90 : 10 (DPBB/AB) on the contralateral side. Cone beam computed tomography (CB/CT) was obtained immediately postoperatively and after a healing period of 7.5 months. Width changes were measured on CB/CT scans. After a mean healing period of 8.1 months (range, 7.9–8.3), biopsies were retrieved perpendicular to the crest from each graft by means of a trephine bur. Histomorphometry was performed, and the following variables were recorded: Ingrowth of new bone (percentage of total graft width), percentage of DPBB, bone and soft tissue, and percentage of DPBB particles in contact with bone.

Results

The mean gained width of the alveolar crest after 7.5 months was significantly more for the 60 : 40 mixture compared with the 90 : 10 mixture, 3.5 (±1.3) mm and 2.9 (±1.3) mm, respectively. There was a significant difference in graft width reduction between 60 : 40 and 90 : 10 after 7.5 months, 37 (±19.9)% and 46.9 (±23.5)%, respectively. New bone ingrowth had occurred in 82.1 (±23.3)% and 82.3 (±26.6)% of the graft, respectively. There were no statistical differences between fractions of different tissues between the 90 : 10 and 60 : 40 compositions. However, there were significantly more soft tissue and less new bone formation closer to the periosteum compared with the graft portion closer to the residual bone in both 60 : 40 and 90 : 10 compositions.

Conclusions

There was significantly less graft width reduction with a mixture of 60 : 40 (DPBB/AB) compared with a mixture of 90 : 10 composition, but the results from the histomorphometry showed no statistical differences comparing the groups.
Histological, radiological and histomorphometric evaluation of immediate vs. non‐immediate loading of a zirconia implant with surface treatment in a dog model
Authors: Calvo‐Guirado Jose L. , Aguilar‐Salvatierra Antonio , Gomez‐Moreno Gerardo , Guardia Javier , Delgado‐Ruiz Rafael A. , Mate‐Sanchez de Val Jose Eduardo
Published: April 2013

Objective

The aim of this study was to assess the performance of zirconia implants under immediate loading compared with delayed loading in dogs over 30–90 days.

Materials and Methods

Tooth extractions were made for the subsequent placement of dental implants at premolars P2, P3, P4 and molars M1 bilaterally in the dog mandible. Forty eight zirconia implants, 4 mm in diameter and 10 mm in length, were inserted, whose neck and body surfaces had been treated with femtosecond laser texturing; 24 implants were loaded immediately and 24 remained unloaded during the osseointegration period. Final radiographs were taken recording stability values before sacrifice at 30 or 90 days when sample removal for histological and histomorphometric analysis was performed. Bone‐to‐implant contact, crestal bone loss and implant stability were evaluated at these two study times.

Results

Bone‐to‐implant contact values after 30 days were 38.9% for immediately loaded implants and 32% for non‐loaded implants. After 90 days, values increased to 65% for immediately loaded and 57.6% for non‐loaded implants. After 30 days, there was more crestal bone lost in the non‐loaded group (0.58 ± 0.28 mm) compared with the immediately loaded group (0.5 ± 0.3 mm). After 90 days, there was improved stability in both groups, but was lower in the immediately loaded group (0.5 ± 0.23 mm) compared with the non‐loaded group (0.56 ± 0.28 mm). Initial implant stability values were −3.5 PTV at the moment of implant placement. Stability values after the first 30 days were −4 for immediately loaded implants and −3 for non‐loaded. At 90 days, non‐loaded implants showed −4.9, whereas immediately loaded showed −7.1.

Conclusions

For the different parameters studied, zirconia implants treated with femtosecond laser and subjected to immediate loading showed better results compared with non‐loaded implants in terms of BIC, crestal bone loss and implant stability.
The effect of hydrofluoric acid treatment of titanium and titanium dioxide surface on primary human osteoblasts
Authors: Pham Maria H. , Landin Maria A. , Tiainen Hanna , Reseland Janne E. , Ellingsen Jan Eirik , Haugen Håvard J.
Published: April 2013

Objective

The aim of the study was to investigate solely the effect of fluoride on the surface chemistry of polycrystalline ceramic titanium dioxide (TiO2) and metallic titanium (Ti) and its effect on proliferation and differentiation of primary human osteoblasts (NHO).

Materials and methods

The NHO cells were exposed to fluoride‐modified and unmodified samples for 1, 3, 7, 14 and 21 days. The fluoride effect on the mRNA expression was quantified and measured. The secretion of cytokines and interleukins in the cell culture medium was measured by Luminex, gene expression by RT‐PCR, and compared with untreated controls. The effect on cell growth after 1 and 3 days in culture was measured using [3H]‐thymidine incorporation. Fluoride release was measured using an ion‐selective electrode. The surfaces were examined by X‐ray photoelectron spectroscopy and profilometry.

Results

The fluoride release study detected that fluoride content easily washed off in TiO2 coins when compared with Ti coins. No increase in cell proliferation was found among fluoride‐modified TiO2 surfaces compared with controls, except for washed Ti coins with fluoride modification. The cell differentiation with regard to gene expression showed no significant differences in both fluoride‐modified and unmodified samples and less effect on protein release for all groups.

Conclusions

The fluoride from hydrofluoric acid treatment on Ti and TiO2 surfaces gave no specific effect on primary human osteoblast cells. The study indicates that the released fluoride is not the unique factor for the bioactivity of Ti and TiO2 surfaces.