bluuebunny/crossref_metadata_2025 huggingface dataset:
Deposition of platinum nanoparticles on p‐type macroporous silicon wall
Authors: Wang Mei , Wang Xiaohong , Ghoshal Sarmishtha
Published: August 2013

A novel thermochemical technique of depositing platinum nanoparticles (PtNPs) on a porous silicon (PS) substrate is demonstrated. Self‐arranged macroporous structures, appearing as microtest tubes, are first formed on p‐type, boron doped, 100 orientation silicon wafers, by the electrochemical etching method in hydrofluoric acid and N, N ‐dimethyl formamide solution. The macroPS substrate is then coated with PtNPs by a novel thermochemical procedure. It was observed that PtNPs deposited on the pore walls are able to arrive even at the bottom of the pores without blocking their openings. Such PtNPs‐coated macroPS chips have potential biomedical applications as silicon and platinum are biocompatible.
Hydroxyapatite nanoparticle‐strengthened bioactive glass nanofibres
Authors: Tan Chengfang , Hong Youliang , Zhang Xingdong
Published: August 2013

In this reported study, hydroxyapatite (HA) nanoparticle‐contained bioactive glass (BG) nanofibres with an average diameter of 500 nm have been prepared by combining a sol–gel method and an electrospinning technique. The mechanical property of the as‐prepared fibres demonstrated that the HA‐BG nanofibres had far higher mechanical strength than pure BG nanofibres, and the in vitro simulated body fluid immersion experiment verified that the growth rate of the hydroxycarbonate apatite nanocrystals on HA‐BG nanofibre surfaces was the same with pure BG nanofibres.
Submicron‐grooved culture surface extends myotube length by forming parallel and elongated motif
Authors: Yuan Chen‐Ching , Ma Kuang‐Jen , Li Kuei‐Chi , Chien Hsi‐Hsin , Lu Huai‐En , Tseng Ching‐Ping , Hwang Shiaw‐Min
Published: August 2013

During skeletal muscle development, correct cellular orientation is vital to generate desired longitudinal contraction for functional muscle fibres. In this reported study, submicron‐imprint lithography was used to generate submicron‐grooved surfaces on polystyrene plates to induce striated myotubes in vitro. Mouse muscle myoblast cells cultured on a submicron‐grooved surface migrated faster in a directionally uniform fashion; in comparison, cells cultured on a flat surface grew and migrated slower in indiscriminate directions. Subsequent maturation of the myoblast cells formed along the submicron‐groove surface resulted in a tandem of parallel myotubes that were both longer and greater in circumference than in the case of the flat surface. In a functional test, the co‐culture submicron‐groove‐grown myotubes with neurotransmitter secreting cells further demonstrated contraction abilities, suggesting submicron‐groove‐guided growth served to enhance myotube formation while retaining striated motifs and physiological functionality for muscle tissue engineering.
Dual‐side nanostructured surface for enhancement of broadband light transmission
Authors: Park Yong Min , Kim Byeong Hee , Seo Young Ho
Published: August 2013

Presented is a surface nanostructuring technology for enhancing the broadband light transmittance of polymethyl methacrylate sheets. Single‐side and dual‐side nanostructured sheets were fabricated by a hot embossing process using nanoporous alumina moulds. The fabricated nanostructured surfaces showed appreciable broadband light transmission characteristics because of the size distribution of their nanostructures. Single‐side and dual‐side nanostructured sheets showed a maximum light transmittance of 96.11 and 98.74%, respectively, whereas a pristine sheet showed a light transmittance of 93.54%.
Fabrication of thin film potentiometric CO2 sensors on differentiate substrate surfaces and their characteristics
Authors: Li Peng , Sun Guoliang , Wang Hairong , Jiang Zhuangde
Published: August 2013

Two kinds of planar‐type potentiometric CO2 gas sensors using thermal evaporated Li3PO4 thin film as solid electrolyte were fabricated. Alumina plates with rough and smooth surfaces were used as the substrates of the sensors. X‐ray diffraction analysis, atomic force microscopy and scanning electron microscopy were used to characterise the Li3PO4 films. The sensing properties were investigated in the range of 500–5000 ppm CO2 concentrations at 480°C. Both the rough substrate‐based sensor (r‐sensor) and the smooth substrate‐based sensor (s‐sensor) were sensitive to CO2 gas and showed a good Nernst behaviour. The output electromotive force (EMF) of the s‐sensor showed a more stable signal than the r‐senor. The ΔEMF/decade values obtained from the r‐sensor and the s‐sensor were 45 and 55 mV/decade, respectively. The response and recovery time were not primarily influenced by the electrolyte film. It was found that the sensitivity of the s‐sensor was closer to the theoretical value. The results revealed that the substrate surface roughness may influence the characteristics of Li3PO4 film and the response properties of the sensors to CO2.
Reactable ionic liquid‐assisted solvothermal synthesis of flower‐like bismuth oxybromide microspheres with highly visible‐light photocatalytic performances
Authors: He Minqiang , Sun Kaiyong , Xia Jiexiang , Li Huaming , Xu Li , Di Jun , Xu Hui , Shu Huoming
Published: August 2013

Bismuth oxybromide (BiOBr) flower‐like microspheres have been successfully synthesised via a polyethylene glycol 600‐assisted solvothermal process in the presence of reactable ionic liquid (IL) 1‐hexadecyl‐3‐methylimidazolium bromide. The morphology and compositional characteristics of BiOBr were investigated by X‐ray diffraction, scanning electron microscopy, energy‐dispersive X‐ray spectroscopy and diffuse reﬂectance spectroscopy. During the reactive process, IL not only acted as a Br source but also as a template for fabrication of BiOBr flower‐like microspheres. Photocatalytic activities of flower‐like microspheres were evaluated by degradation of rhodamine B under visible‐light irradiation. Compared with the BiOBr nanoplates, BiOBr hollow microspheres and TiO2 (Degussa, P25), BiOBr flower‐like microspheres exhibited excellent performance in visible‐light‐driven photocatalysis.
Fabrication of polyvinyl alcohol/multi‐walled carbon nanotubes composite electrospun nanofibres and their application as microwave absorbing material
Authors: Salimbeygi Golestan , Nasouri Komeil , Shoushtari Ahmad Mousavi , Malek Reza , Mazaheri Firoozmehr
Published: August 2013

Polyvinyl alcohol (PVA)/sodium dodecyl sulphate (SDS)/multi‐walled carbon nanotubes (MWCNTs) composite nanofibres with various MWCNT contents (up to 10 wt%) were fabricated by electrospinning process and their microwave absorption properties were evaluated by a vector network analyser in the frequency range of 8–12 GHz (X‐band) at room temperature. Scanning electron microscopy analysis of the nanofibre samples revealed that the deformation of the nanofibres increases with increasing MWCNT concentration. Very smooth surfaces of the composite electrospun nanofibres even for nanofibres with concentration of 10 wt% MWCNT have been successfully prepared because of the high stability dispersion of MWCNTs. It was observed that the absorption microwave properties improved by increasing the loading levels of MWCNTs. Finally, the PVA/SDS/MWCNT composite nanofibres sample with 10 wt% content of MWCNT has shown a reflection loss of 15 dB at a frequency of 8 GHz.
Theoretical determination of anisotropic thermal conductivity for crystalline 1,3,5-triamino-2,4,6-trinitrobenzene (TATB)
Authors: Kroonblawd Matthew P. , Sewell Thomas D.
Published: August 2013

Bond stretching and three-center angle bending potentials have been developed to extend an existing rigid-bond 1,3,5-triamino-2,4,6-trinitrobenzene molecular dynamics force field [D. Bedrov, O. Borodin, G. D. Smith, T. D. Sewell, D. M. Dattelbaum, and L. L. Stevens, J. Chem. Phys. 131, 224703 (2009)10.1063/1.3264972] for simulations requiring fully flexible molecules. The potentials were fit to experimental vibrational spectra and electronic structure predictions of vibrational normal modes using a combination of zero kelvin eigenmode analysis for the isolated molecule and power spectra for the isolated molecule and crystal. A reverse non-equilibrium molecular dynamics method [F. Müller-Plathe, J. Chem. Phys. 106, 6082 (1997)10.1063/1.473271] was used to obtain the room temperature, atmospheric pressure thermal conductivity along three directions in a well-defined, non-orthogonal basis. The thermal conductivity was found to be significantly anisotropic with values 1.13 ± 0.07, 1.07 ± 0.07, and 0.65 ± 0.03 W m−1 K−1 for directions nominally parallel to the a, b, and c lattice vectors, respectively.
Highly-efficient thermoelectronic conversion of solar energy and heat into electric power
Authors: Meir S. , Stephanos C. , Geballe T. H. , Mannhart J.
Published: August 2013

Electric power may, in principle, be generated in a highly efficient manner from heat created by focused solar irradiation, chemical combustion, or nuclear decay by means of thermionic energy conversion. As the conversion efficiency of the thermionic process tends to be degraded by electron space charges, the efficiencies of thermionic generators have amounted to only a fraction of those fundamentally possible. We show that this space-charge problem can be resolved by shaping the electric potential distribution of the converter such that the static electron space-charge clouds are transformed into an output current. Although the technical development of such thermoelectronic generators will require further substantial efforts, we conclude that a highly efficient transformation of heat to electric power may well be achieved.
Improved charge amplifier using hybrid hysteresis compensation
Authors: Amin-Shahidi Darya , Trumper David L.
Published: August 2013

We present a novel charge amplifier, with a robust feedback circuit and a method for compensating piezoelectric actuator's hysteresis at low frequencies. The amplifier uses a modified feedback circuit which improves robustness to the addition of series load impedance such as in cabling. We also describe a hybrid hysteresis compensation method for enabling the charge amplifier to reduce hysteresis at low frequencies. Experimental results demonstrate the utility of the new amplifier design.
Chemistry at molecular junctions: Rotation and dissociation of O2 on the Ag(110) surface induced by a scanning tunneling microscope
Authors: Roy Sharani , Mujica Vladimiro , Ratner Mark A.
Published: August 2013

The scanning tunneling microscope (STM) is a fascinating tool used to perform chemical processes at the single-molecule level, including bond formation, bond breaking, and even chemical reactions. Hahn and Ho [J. Chem. Phys. 123, 214702 (2005)10.1063/1.2131064] performed controlled rotations and dissociations of single O2 molecules chemisorbed on the Ag(110) surface at precise bias voltages using STM. These threshold voltages were dependent on the direction of the bias voltage and the initial orientation of the chemisorbed molecule. They also observed an interesting voltage-direction-dependent and orientation-dependent pathway selectivity suggestive of mode-selective chemistry at molecular junctions, such that in one case the molecule underwent direct dissociation, whereas in the other case it underwent rotation-mediated dissociation. We present a detailed, first-principles-based theoretical study to investigate the mechanism of the tunneling-induced O2 dynamics, including the origin of the observed threshold voltages, the pathway dependence, and the rate of O2 dissociation. Results show a direct correspondence between the observed threshold voltage for a process and the activation energy for that process. The pathway selectivity arises from a competition between the voltage-modified barrier heights for rotation and dissociation, and the coupling strength of the tunneling electrons to the rotational and vibrational modes of the adsorbed molecule. Finally, we explore the “dipole” and “resonance” mechanisms of inelastic electron tunneling to elucidate the energy transfer between the tunneling electrons and chemisorbed O2.
In situ Brillouin study of sodium alumino silicate glasses under pressure
Authors: Sonneville C. , De Ligny D. , Mermet A. , Champagnon B. , Martinet C. , Henderson G. H. , Deschamps T. , Margueritat J. , Barthel E.
Published: August 2013

The in situ elastic and plastic behaviors of sodium aluminosilicate glasses with different degrees of depolymerization were analyzed using Brillouin spectroscopy. The observed elastic anomaly progressively vanished with depolymerization. The densification process appears to be different from that observed in pure silica glass. In the plastic regime of densified glasses hysteresis loops were observed and related to modification of the local silicon environment facilitated by the addition of sodium.
Effect of growth induced (non)stoichiometry on the thermal conductivity, permittivity, and dielectric loss of LaAlO3 films
Authors: Breckenfeld E. , Wilson R. B. , Martin L. W.
Published: August 2013

The effect of growth-induced non-stoichiometry on the thermal and dielectric properties of pulsed-laser deposited LaAlO3 thin films is explored. The composition of the LaAlO3 films was characterized via X-ray photoelectron spectroscopy and Rutherford backscattering spectrometry and it is revealed that small deviations in laser fluence result in deviations of cation stoichiometry as large as a few atomic percent. The thermal conductivity is also found to be especially sensitive to non-stoichiometry, with 3%-5% La-excess and La-deficiency resulting in 60%-80% reduction in thermal conductivity. The dielectric constant decreases and the loss tangent increases with increasing non-stoichiometry with differences between La-excess and La-deficiency.
Communication: An approximation to Bader's topological atom
Authors: Salvador Pedro , Ramos-Cordoba Eloy
Published: August 2013

A new, more flexible definition of fuzzy Voronoi cells is proposed as a computationally efficient alternative to Bader's Quantum Theory of Atoms in Molecules (QTAIM) partitioning of the physical space for large-scale routine calculations. The new fuzzy scheme provides atomic charges, delocalization indices, and molecular energy components very close to those obtained using QTAIM. The method is flexible enough to either ignore the presence of spurious non-nuclear attractors or to readily incorporate them by introducing additional fuzzy Voronoi cells.
Graphene as tunable transparent electrode material on GaN: Layer-number-dependent optical and electrical properties
Authors: Shiu Hung Wei , Yueh Chang Lo , Lee Kai-Hsuan , Chen Hung-Ying , Gwo Shangjr , Chen Chia-Hao
Published: August 2013

Graphene has been regarded as a prospective transparent electrode for a GaN-based light-emitting diode (LED), but fundamental knowledge about the intrinsic properties of the graphene/GaN contact is lacking. We have studied the optical and electronic properties of graphene exfoliated on an n-type GaN surface. The graphene visibility was simulated based on Fresnel's law and confirmed with an optical microscope and micro-Raman spectra. The interfacial electronic property was studied with a scanning photoelectron microscope. We found that the Schottky barrier height of the graphene/n-GaN is decreased with decreasing graphene number of layers, yielding an improved GaN-based LED performance.
Highly localized photothermal conversion in two-dimensional Au nanoparticle arrays
Authors: Namura Kyoko , Suzuki Motofumi , Nakajima Kaoru , Kimura Kenji
Published: August 2013

We have investigated, both theoretically and experimentally, highly localized photothermal conversions in Au nanoparticle array/dielectric layer/Ag mirror sandwiches, namely local plasmon resonators. The depth profile of the optical absorption in the local plasmon resonators was calculated using a simple model comprising homogeneous multilayers. The calculation results show highly localized light absorption in the ∼ 10-nm-thick Au nanoparticles layer (more than 99% of total optical absorption). The photoacoustic measurements, which are sensitive to the surface temperature of the sample, were performed on the fabricated local plasmon resonators. The photoacoustic amplitude of the local plasmon resonator possessing a high optical absorption (A = 0.97) was 15 times larger than the absorbance of the bulk Si wafer (A = 0.67) and 8 times larger than the absorbance of graphite (A = 0.85). These results suggest that the photothermal conversion is localized in the thin Au nanoparticles layer, which enables rapid modulation of the temperature of the surrounding fluid.
Applicability of Langmuir equation to oxygen pressure dependent photoluminescence from β-Ga2O3 nanostructures
Authors: Jangir R. , Ganguli Tapas , Porwal S. , Tiwari Pragya , Rai S. K. , Bhaumik Indranil , Kukreja L. M. , Gupta P. K. , Deb S. K.
Published: August 2013

β-Ga2O3 nanostructures were synthesized via vapor transport method on gold coated Silicon substrate in N2 ambient. The as synthesized products were investigated by grazing incident X-ray diffraction, scanning electron microscopy and photoluminescence (PL) spectroscopy. It is shown that the intensity of photoluminescence from the ensemble of β-Ga2O3 nanostructures in oxygen gas ambience is correlated with the oxygen pressure through the Langmuir equation. This correlation is found to be reversible and reproducible. This phenomenon, which was not observed in the bulk β-Ga2O3 single crystal, is attributed to the oxygen related shallow trap surface states of the nanostructures with energies at about 4.2 eV above the valance band. Based on the changes in the PL intensity with the oxygen pressures, a possible mechanism for the observed photoluminescence is suggested. The present results provide a route for room-temperature response of oxygen in the gallium oxide nanostructures.
Li+ transport properties of W substituted Li7La3Zr2O12 cubic lithium garnets
Authors: Dhivya L. , Janani N. , Palanivel B. , Murugan Ramaswamy
Published: August 2013

Lithium garnet Li7La3Zr2O12 (LLZ) sintered at 1230 °C has received considerable importance in recent times as result of its high total (bulk + grain boundary) ionic conductivity of 5 × 10−4 S cm−1 at room temperature. In this work we report Li+ transport process of Li7−2xLa3Zr2−xWxO12 (x = 0.3, 0.5) cubic lithium garnets. Among the investigated compounds, Li6.4La3Zr1.7W0.3O12 sintered relatively at lower temperature 1100 °C exhibits highest room temperature (30 °C) total (bulk + grain boundary) ionic conductivity of 7.89 × 10−4 S cm−1. The temperature dependencies of the bulk conductivity and relaxation frequency in the bulk are governed by the same activation energy. Scaling the conductivity spectra for both Li6.4La3Zr1.7W0.3O12 and Li6La3Zr1.5W0.5O12 sample at different temperatures merges on a single curve, which implies that the relaxation dynamics of charge carriers is independent of temperature. The shape of the imaginary part of the modulus spectra suggests that the relaxation processes are non-Debye in nature. The present studies supports the prediction of optimum Li+ concentration required for the highest room temperature Li+ conductivity in LixLa3M2O12 is around x = 6.4 ± 0.1.
Effective scattering cross-section in lattice thermal conductivity calculation with differential effective medium method
Authors: Wu Di , Petersen A. S. , Poon S. J.
Published: August 2013

To further reduce the lattice thermal conductivity of thermoelectric materials, the technique of embedding nano-inclusions into bulk matrix materials, in addition to point defect scattering via alloying, was widely applied. Differential Effective Medium (DEM) method was employed to calculate two-phase heterogeneous systems. However, in most effective medium treatment, the interface scattering of matrix phonons by embedded nanoparticle was underestimated by adopting particle's projected area as scattering cross-section. Herein, modified cross-section calculations, as well as grain sizes dispersions, are applied in DEM, with the calculations then validated by comparing with Monte-Carlo simulations and existing experimental data. Predictions of lattice thermal conductivity reduction on in-situ formed Full Heusler (FH)/Half Heusler (HH) nano/matrix system are discussed.
Broadband polarization rotator based on multi-order plasmon resonances and high impedance surfaces
Authors: Feng Mingde , Wang Jiafu , Ma Hua , Mo Weidong , Ye Hongjun , Qu Shaobo
Published: August 2013

We experimentally investigate the electromagnetic (EM) responses of a broadband reflective polarization rotator under normal incidence. It is found that the rotator can generate multi-order plasmon resonances at three neighboring frequencies. At each frequency, the rotator behaves as a high impedance surface along one axis while as a metallic reflective surface along the other axis. Thus, a 180° phase difference is generated between the two orthogonal components of reflected waves. When the incident wave is polarized by 45° with respect to the symmetry axis of the rotator, the polarization of reflected waves is rotated by 90°. The designed rotator presents broadband properties. It can perform perfect 90° polarization rotation at three frequencies and maintains a polarization conversion efficiency greater than 56% in 2.0–3.5 GHz. The rotator provides a route to broadband polarization rotation and has application values in polarization control.
Climate change and broadacre livestock production across southern Australia. 3. Adaptation options via livestock genetic improvement
Authors: Moore Andrew D. , Ghahramani Afshin
Published: August 2013

Climate change is predicted to reduce the productivity of the broadacre livestock industries across southern Australia; to date there has been no formal evaluation of the potential of genetic improvement in cattle or sheep to ameliorate the impacts of changing climates. We used the GRAZPLAN simulation models to assess selection of five traits of sheep and cattle as adaptation options under the SRES A2 global change scenario. Analysis of the breeding strategies was carried out for 25 representative locations, five livestock enterprises and three future years (2030, 2050, 2070). Uncertainty in future climates was taken into account by considering projected climates from four global circulation models. For three sheep enterprises, breeding for greater fleece growth (at constant body size) was predicted to produce the greatest improvements in forage conversion efficiency, and so it was the most effective genetic adaptation option. For beef cow and steer enterprises, breeding for larger body size was most effective; for beef cows, however, this conclusion relied on per-animal costs (including provision of bulls) remaining stable as body size increases. Increased conception rates proved to be less effective but potentially viable as an adaptation in beef cow and crossbred ewe enterprises. In the southern Australian environments that were analysed, our modelling suggests that breeding for tolerance to heat stress is unlikely to improve the performance of livestock production systems even at 2070. Genetic improvement of livestock was able to recover much less of the impact of climate change on profitability at drier locations where the need for adaptation is likely to be greatest. Combinations of feedbase and livestock genetic adaptations are likely to complement one another as the former alter the amount of forage that can be consumed, while the latter affect the efficiency with which consumed forage is converted to animal products. Climate change impacts on pasture production across southern Australia are likely to have only small effects on methane emissions intensity, as are a range of candidate genetic and feedbase adaptations to climate change; methane emissions per hectare in future climates will therefore be driven mainly by changes in livestock numbers due to alterations in pasture productivity.
Mapping quantitative trait loci for pre-harvest sprouting resistance in white-grained winter wheat line CA 0431
Authors: Miao X. L. , Zhang Y. J. , Xia X. C. , He Z. H. , Zhang Y. , Yan J. , Chen X. M.
Published: August 2013

Pre-harvest sprouting (PHS) in wheat severely reduces yield and end-use quality, resulting in substantial economic losses. The Chinese winter wheat line CA 0431, with white grain, showed high PHS resistance for many years. To identify quantitative trait loci (QTLs) of PHS resistance in this line, 220 F2 plants and the corresponding F2 : 3 lines derived from a cross between CA 0431 and the PHS-susceptible cultivar Zhongyou 206 were used for PHS testing and QTL analysis. Field trials were conducted in Beijing during the 2010–11 and 2011–12 cropping seasons, and in Anyang during 2011–12. PHS resistance was evaluated by assessing the sprouting responses of intact spikes. In total, 1444 molecular markers were used to screen the parents, and 31 markers with polymorphisms between the resistant and susceptible bulks were used to genotype the entire F2 population. Broad-sense heritability of sprouting rate was 0.71 across environments. Inclusive composite interval mapping identified four QTLs, QPhs.caas-2BL, QPhs.caas-3AS.1, QPhs.caas-3AS.2, and QPhs.caas-3AL, each explaining 2.8–27.7% of the phenotypic variance across environments. The QTLs QPhs.caas-3AS.1, QPhs.caas-3AS.2, and QPhs.caas-3AL were located at similar positions to QTLs reported previously, whereas QPhs.caas-2BL is likely a new QTL flanked by markers Xbarc1042 and Xmag3319. Line CA 0431 and the identified markers can be used in breeding programs targeting improvement of PHS resistance for white-kernel wheat.
Beliefs about willpower determine the impact of glucose on self-control
Authors: Job Veronika , Walton Gregory M. , Bernecker Katharina , Dweck Carol S.
Published: August 2013

Significance

The present research provides critical new findings about the role of glucose ingestion in self-control and cognitive performance. It argues against the popular view that self-control depends on a limited physiological resource (blood glucose) that is depleted by even brief acts of self-control and is restored by glucose consumption. Instead, the results highlight the critical role of beliefs about willpower in self-control performance.
Borel conjecture and dual Borel conjecture
Authors: Goldstern Martin , Kellner Jakob , Shelah Saharon , Wohofsky Wolfgang
Published: August 2013

We show that it is consistent that the Borel Conjecture and the dual Borel Conjecture hold simultaneously.
Oxidative stress in response to natural and experimentally elevated reproductive effort is tissue dependent
Authors: Xu Yan‐Chao , Yang Deng‐Bao , Speakman John R. , Wang De‐Hua
Published: August 2013

Oxidative stress is a potential proximal physiological cost of reproduction. Detecting this cost may be performed in several different ways – manipulating reproductive status, correlating natural variations in effort to oxidative stress or manipulating reproductive effort. Here, we manipulated reproductive status and studied oxidative stress due to natural and experimental variation in reproductive effort in Brandt's voles (Lasiopodomys brandtii), using a variety of markers and tissues.

We measured markers of oxidative stress in lactating (raising 6 to 8 offspring) and non‐reproductive voles (Experiment I) and found that a marker of oxidative protection [serum total‐superoxide dismutase (SOD) activity] was reduced, and a marker of oxidative damage (protein carbonyls) was increased, in the serum, in lactating compared with non‐reproductive voles. However, protein carbonyls in the liver were lower in lactating compared with non‐reproductive voles, consistent with increased liver SOD activity. Lipid damage [malonaldehyde (MDA)] in both serum and liver was unrelated to reproductive status.

We compared these markers of oxidative stress between natural large (n ≥ 9) and small litter sizes (n ≤ 5; Experiment II), and between manipulated large (11–13) and small litter sizes (2–3; Experiment III) and found that liver MDA and SOD activity was higher in voles with natural large compared with natural small litter sizes, but there were no differences in other markers. There was no effect of litter size on all measures when it was experimentally manipulated.

The effects of reproductive status on oxidative stress were critically dependent on the exact markers and tissues used. The effects of natural variation in reproductive effort suggested that there might be an oxidative stress cost associated with large litter sizes, but this effect was not replicated in the experimentally manipulated litters.
Floral symmetry is associated with flower size and pollen production but not insect visitation rates in Geranium robertianum (Geraniaceae)
Authors: Frey Frank M. , Bukoski Michael
Published: August 2013

The degree to which fine‐scaled variation in floral symmetry is associated with variation in plant fitness remains unresolved, as does the question of whether floral symmetry is in itself a target of pollinator‐mediated selection. Geranium robertianum (Geraniaceae) is a broadly distributed species whose five‐petaled flowers vary widely with respect to their degree of rotational asymmetry. In this study, we used a naturally occurring population of plants to investigate whether floral rotational asymmetry and leaf bilateral symmetry were phenotypically correlated with a series of fitness‐related traits, and also used an experimental array with model flowers to investigate the preference of insect visitors for varying degrees of floral size and symmetry. We found that leaf asymmetry was not associated with any of the phenotypic traits measured, and that the degree of floral rotational asymmetry was strongly associated with decreased flower size and decreased pollen production. Our experimental arrays showed that insect visitors did not discriminate among model flowers on the basis of size or symmetry alone; however, insect visitors preferentially visited smaller, symmetric model flowers over larger, severely asymmetric model flowers. Taken together, our results suggest that floral and leaf symmetry in G. robertianum are not likely strong indicators of phenotypic quality, and that floral symmetry is unlikely to be a target of pollinator‐mediated selection. However, the relationship between floral asymmetry and pollen production may provide a role for fecundity selection on symmetry in this species. These data importantly add to the growing literature on the adaptive nature of floral symmetry in the wild.
A novel role for antibiotic resistance plasmids in facilitating Salmonella adaptation to non‐host environments
Authors: Paytubi Sonia , Aznar Sonia , Madrid Cristina , Balsalobre Carlos , Dillon Shane C. , Dorman Charles J. , Juárez Antonio
Published: August 2013

It is believed that the main role of plasmids that encode multiple antibiotic resistance is to confer their hosts the ability to survive in the presence of antimicrobial compounds. In the pathogenic bacterium Salmonella, plasmids of the incompatibility group HI1 account for a significant proportion of antibiotic resistance phenotypes. In this work, we show that plasmid R27 has a strong impact on the global transcriptome of Salmonella Typhimurium strain SL1344 when cells grow at low temperature and enter the stationary phase. Down‐regulated genes include pathogenicity islands, anaerobic respiration and metabolism determinants. Up‐regulated genes include factors involved in the response to nutrient starvation, antimicrobial resistance, iron metabolism and the heat shock response. Accordingly, cells harbouring R27 are more resistant to heat shock than plasmid‐free cells. The use of a different IncHI1 plasmid, pHCM1, provided evidence that these plasmids facilitate adaptation of Salmonella to environmental conditions outside their host(s). This is consistent with the fact that conjugative transfer of IncHI1 plasmids only occurs at low temperature. A significant number of the R27‐dependent alterations in gene expression could be correlated with expression of a plasmid‐encoded orthologue of the global modulator H‐NS, which is up‐regulated when cells grow at low temperature.
Detection of Vibrio parahaemolyticus, Vibrio vulnificus and Vibrio cholerae with respect to seasonal fluctuations in temperature and plankton abundance
Authors: Turner Jeffrey W. , Malayil Leena , Guadagnoli Dominic , Cole D. , Lipp Erin K.
Published: August 2013

Over a 1‐year period, bi‐monthly estuarine surface water and plankton samples (63–200 and > 200 μm fractions) were assayed by polymerase chain reaction for the prevalence of total Vibrio parahaemolyticus, V. vulnificus and V. cholerae and select genes associated with clinical strains found in each species. Neither temperature nor plankton abundance was a significant correlate of total V. parahaemolyticus; however, the prevalence of genes commonly associated with clinical strains (trh, tdh, ORF8) increased with temperature and copepod abundance (P < 0.05). The prevalence of total V. vulnificus and the siderophore‐related viuB gene also increased with temperature and copepod and decapod abundance (P < 0.001). Temperature and copepod abundance also covaried with the prevalence of V. cholerae (P < 0.05), but there was no significant relationship with ctxA or other genes commonly found in clinical strains. Results show that genes commonly associated with clinical Vibrio strains were more frequently detected in association with chitinous plankton. We conclude that V. parahaemolyticus, V. vulnificus, V. cholerae and subpopulations that harbour genes common to clinical strains respond distinctly to seasonal changes in temperature as well as shifts in the taxonomic composition of discrete plankton fractions.
Rare earth metals are essential for methanotrophic life in volcanic mudpots
Authors: Pol Arjan , Barends Thomas R. M. , Dietl Andreas , Khadem Ahmad F. , Eygensteyn Jelle , Jetten Mike S. M. , Op den Camp Huub J. M.
Published: August 2013

Growth of Methylacidiphilum fumariolicum SolV, an extremely acidophilic methanotrophic microbe isolated from an Italian volcanic mudpot, is shown to be strictly dependent on the presence of lanthanides, a group of rare earth elements (REEs) such as lanthanum (Ln), cerium (Ce), praseodymium (Pr) and neodymium (Nd). After fractionation of the bacterial cells and crystallization of the methanol dehydrogenase (MDH), it was shown that lanthanides were essential as cofactor in a homodimeric MDH comparable with one of the MDHs of Methylobacterium extorquens AM1. We hypothesize that the lanthanides provide superior catalytic properties to pyrroloquinoline quinone (PQQ)‐dependent MDH, which is a key enzyme for both methanotrophs and methylotrophs. Thus far, all isolated MxaF‐type MDHs contain calcium as a catalytic cofactor. The gene encoding the MDH of strain SolV was identified to be a xoxF‐ortholog, phylogenetically closely related to mxaF. Analysis of the protein structure and alignment of amino acids showed potential REE‐binding motifs in XoxF enzymes of many methylotrophs, suggesting that these may also be lanthanide‐dependent MDHs. Our findings will have major environmental implications as metagenome studies showed (lanthanide‐containing) XoxF‐type MDH is much more prominent in nature than MxaF‐type enzymes.
Metagenomic 16S rDNA Illumina tags are a powerful alternative to amplicon sequencing to explore diversity and structure of microbial communities
Authors: Logares Ramiro , Sunagawa Shinichi , Salazar Guillem , Cornejo‐Castillo Francisco M. , Ferrera Isabel , Sarmento Hugo , Hingamp Pascal , Ogata Hiroyuki , de Vargas Colomban , Lima‐Mendez Gipsi , Raes Jeroen , Poulain Julie , Jaillon Olivier , Wincker Patrick , Kandels‐Lewis Stefanie , Karsenti Eric , Bork Peer , Acinas Silvia G.
Published: August 2013

Sequencing of 16S rDNA polymerase chain reaction (PCR) amplicons is the most common approach for investigating environmental prokaryotic diversity, despite the known biases introduced during PCR. Here we show that 16S rDNA fragments derived from Illumina‐sequenced environmental metagenomes (mitags) are a powerful alternative to 16S rDNA amplicons for investigating the taxonomic diversity and structure of prokaryotic communities. As part of the Tara Oceans global expedition, marine plankton was sampled in three locations, resulting in 29 subsamples for which metagenomes were produced by shotgun Illumina sequencing (ca. 700 Gb). For comparative analyses, a subset of samples was also selected for Roche‐454 sequencing using both shotgun (m454tags; 13 metagenomes, ca. 2.4 Gb) and 16S rDNA amplicon (454tags; ca. 0.075 Gb) approaches. Our results indicate that by overcoming PCR biases related to amplification and primer mismatch, mitags may provide more realistic estimates of community richness and evenness than amplicon 454tags. In addition, mitags can capture expected beta diversity patterns. Using mitags is now economically feasible given the dramatic reduction in high‐throughput sequencing costs, having the advantage of retrieving simultaneously both taxonomic (Bacteria, Archaea and Eukarya) and functional information from the same microbial community.
Influence of Yeasts on the Oil Quality Indexes of Table Olives
Authors: Rodríguez‐Gómez Francisco , Bautista‐Gallego Joaquín , Romero‐Gil Verónica , Arroyo‐López Francisco Noé , Garrido‐Fernández Antonio
Published: August 2013

After moisture, fat is the major constituent of table olives. However, scarce studies have been carried out to determine the influence of microorganisms and type of processing on the modification of their quality indexes. The present survey studies the influence of lipolytic (Candida boidinii TOMC Y5 and Wickerhamomyces anomalus TOMC Y10) and nonlipolytic (Debaryomyces etchellsii TOMC Y9 and Pichia galeiformis TOMC Y27) yeasts on the oil quality indexes of Manzanilla and Hojiblanca green fruits processed as directly brined and lye‐treated table olives. Overall, the inocula scarcely used available sugars, except the lipolytic C. boidinii strain in lye‐treated olives. Acetic acid production was limited in all conditions, except for the D. etchellsii strain in directly brined Manzanilla fruits. Ethanol formation was also reduced, although the W. anomalus (in both types of elaboration) and the C. boidinii (in lye‐treated olives) strains produced significantly higher proportions. Apparently, changes in the oil quality indexes of processed olives were not related to the presence of yeasts, and hence, could have been caused by the endogenous activity of the fruits. A principal component analysis using the microbiological, physicochemical, and oil quality data supported this hypothesis, grouping treatments according to olive variety and type of elaboration, while segregation due to yeast inocula was not observed.
Effect of Breed on Fatty Acid Composition and Lipogenic Enzyme Abundance in the Subcutaneous Adipose Tissue of Pigs
Authors: Marriott Duncan T. , Chevillon Patrick , Spencer‐Phillips Peter T. N. , Doran Olena
Published: August 2013

This study investigated the role of lipogenic enzyme expression in breed‐specific fat deposition in pigs. Objectives: (i) determine effect of breed on the relative abundance of the key lipogenic enzymes stearoyl‐CoA desaturase (SCD), delta‐6 desaturase (Δ6D), and fatty acid synthase (FAS) in pig subcutaneous adipose tissue. (ii) Investigate breed‐specific relationships between lipogenic enzyme abundance and fatty acid composition. Large White × Piétrain, Piétrain, and Duroc × Piétrain pigs were used. Expression of SCD, Δ6D, and FAS was analyzed by Western blotting. Fatty acid composition was determined by gas chromatography. FAS protein in Large White × Piétrain pigs was similar to the Piétrain breed, but was significantly higher than Duroc × Piétrain. A positive relationship was found between FAS abundance and the saturated fatty acids (SFAs), for Large White × Piétrain pigs, but not for the other breeds. Δ6D was significantly higher in Large White × Piétrain compared with Duroc × Piétrain and Piétrain. This was accompanied by significantly higher total n−3 poly‐unsaturated fatty acids (PUFAs) in the Large White × Piétrain when compared to the other breeds. Conclusions: (i) increased subcutaneous adipose tissue SFA content in Large White × Piétrain pigs (but not Piétrain and Duroc × Piétrain) is related to increased abundance of FAS protein; (ii) high n−3 PUFA content in Large White × Piétrain pigs is related to activation of Δ6D protein synthesis; (iii) SCD and Δ6D abundance does not contribute to between‐breed differences in MUFA and n−6 PUFA content of pig subcutaneous adipose tissue.
Predominant Bacteria Diversity in Chinese Traditional Sourdough
Authors: Zhang Guohua , He Guoqing
Published: August 2013

The purpose of this study was to identify the major bacteria in Chinese traditional sourdough (CTS). Five CTS samples (Hn‐87, Sx‐91, Gs‐107, Hf‐112, and Hr‐122) were collected from different Chinese steamed breads shops or private households. The total bacterial DNA was extracted from sourdough samples and sequenced using Illumina Hiseq 2000 system. Illumina tags were assigned to BLASTN server based on 16S rRNA libraries to reveal a genetic profile. Phylogenetic analysis revealed that the bacteria in traditional sourdough samples were dominated by the genera Leuconostoc and Lactobacillus. Beta diversity analysis, principal component analysis, and cluster analysis compared the bacterial differences in traditional sourdough samples. The results showed that Leuconostoc, Lactobacillus, and Weissella were the predominant genera among the 5 samples. This differentiated the sourdoughs into 3 typologies, namely, 1) Gs‐107 and Sx‐91, 2) Hr‐122 and Hn‐87, and 3) Hf‐112. This study identified 3 unique major bacteria genus in CTS bread ecosystems.
Physicochemical Characterization and Antioxidant Activity of Commercial Portuguese Honeys
Authors: Aazza Smail , Lyoussi Badiaa , Antunes Dulce , Miguel Maria Graça
Published: August 2013

The present study evaluated the physicochemical characteristics and antioxidant activity of 13 commercial honeys from diverse floral origin, produced in Portugal. The values of electrical conductivity of cardoon and pennyroyal honeys were superior to the maximum limits defined by European legislation. Citrus, strawberry tree, and 1 sample of lavender honeys had values of diastase activity below those determined by European legislation. Strawberry tree, pennyroyal, and cardoon honeys had the highest amounts of potassium that coincided with the highest electrical conductivity. Strawberry tree honey was the most effective as antioxidant along with cardoon and heather honeys. This ability was strongly correlated with the amounts of phenols and flavonoids and not with the levels of vitamin C or proline.
Peel Effects on Phenolic Composition, Antioxidant Activity, and Making of Pomegranate Juice and Wine
Authors: Wasila Humaira , Li Xuan , Liu Linwei , Ahmad Imran , Ahmad Sajjad
Published: August 2013

Pomegranate peel was used in juicing to find out its effects on the juice products’ (storable juice and wine) sensory property, polyphenols composition, and antioxidant ability. Macroporous resin was used to purify the polyphenols, and 6 different in vitro assays were used to comprehensively determine the antioxidant activity of each. The results showed that juicing with peel made the juice bitter and astringent, but contributed better sensory quality to wine. Peel contributed higher total polyphenols and flavonoids, but lower anthocyanins to the juice products, and caused the phenolics content to fluctuate more dramatically during making wine than the storable juice. Polyphenols purified from the juice products containing peel showed higher total reducing ability and 2,2‐diphenyl‐1‐picrylhydrazyl and 2,2′‐azino‐bis(3‐ethylbenzothiazoline‐6‐sulfonic acid radical elimination abilities, but their clearance activity of hydroxyl radicals was not positive, and their superoxide anion radical elimination ability showed no significant difference when compared to polyphenols purified from juice products without peel.
Microbiological and Fermentative Properties of Baker's Yeast Starter Used in Breadmaking
Authors: Reale A. , Di Renzo T. , Succi M. , Tremonte P. , Coppola R. , Sorrentino E.
Published: August 2013

This study assessed the levels of microbial contaminants in liquid, compressed and dry commercial baker's yeasts used as starters in breadmaking. Eumycetes, Enterobacteriaceae, total and fecal coliforms, Bacillus spp., and lactic acid bacteria (LAB), in particular enterococci, were quantified. Results obtained in this study highlighted that baker's yeast could represent a potential vehicle of spoilage and undesirable microorganisms into the baking environment, even if these do not influence the leavening activity in the dough, as ascertained by rheofermentometer analysis. Different microbial groups, such as spore‐forming bacteria and moulds, were found in baker's yeast starters. Moreover, different species of LAB, which are considered the main contaminants in large‐scale yeast fermentations, were isolated and identified by Denaturing Gradient Gel Electrophoresis (DGGE) and 16S rDNA sequencing. The most recurrent species were Lactobacillus plantarum, Enterococcus faecalis, and Enterococcus durans, isolated from both compressed and dry starters, whereas strains belonging to Leuconostoc and Pediococcus genera were found only in dry ones. Nested‐Polymerase Chain Reaction (Nested‐PCR) and Randomly Amplified Polymorphic DNA–PCR (RAPD‐PCR) were also used to highlight the biodiversity of the different commercial yeast strains, and to ascertain the culture purity.
Impact of Rearing Conditions on the Microbiological Quality of Raw Retail Poultry Meat
Authors: Hardy Bridgshe , Crilly Nate , Pendleton Sean , Andino Ana , Wallis Audra , Zhang Nan , Hanning Irene
Published: August 2013

There is a gap in knowledge of microbiological quality in raw chicken products produced by nonconventional methods and no studies have reported the microbiological quality of turkeys produced under different rearing environments. Thus, the aim of this study was to compare the microbiological quality of conventionally and organically reared whole chicken and turkey carcasses purchased from 3 retail outlets in Knoxville, Tenn., U.S.A. A total of 100 raw broiler chickens organically (n = 50) and 50 raw turkey carcasses consisting of 3 brands reared either conventionally (n = 25) or organically (n = 25) were evaluated. The FDA BAM protocol for rinsing poultry carcasses was used to enumerate of aerobic bacteria, Campylobacter, and Staphylococcus spp., and for qualitative analysis of Salmonella. Organic chickens from one brand had the highest average counts of aerobic bacteria, Staphylococcus spp. and Campylobacter (4.8, 4.8, and 4.7 Log10 CFU/mL rinsate, respectively) while the other organic brand had the lowest average counts (3.4, 3.3, and 3.1, respectively) of all 4 brands evaluated. The organic turkeys had the highest average counts of these same bacteria (4, 3.9, and 3.8, respectively) compared to the 2 brands of conventional turkeys evaluated. Salmonella (5% prevalence) was isolated only from organic chickens and turkeys. From these data, it appears that the microbiological quality of the raw product was not dependent on rearing conditions and, thus, it cannot be assumed that organic raw poultry is safer than conventionally raised poultry in terms of microbiological quality.
Inactivation of Polyphenoloxidase by Pulsed Light
Authors: Manzocco Lara , Panozzo Agnese , Nicoli Maria Cristina
Published: August 2013

The effect of pulsed light on the inactivation of polyphenoloxidase (PPO) in model solutions was investigated focusing on the effect of enzyme concentration and total energy dose of the treatment. PPO inactivation increased with the dose of the treatment. Complete enzyme inactivation was achieved by pulsed light doses higher than 8.75 J cm−2. At low PPO concentrations (4 to 10 U), the enzyme resulted highly inactivated by pulsed light treatment. Further increase in enzyme units determined a progressive decrease in PPO inactivation. The latter was attributed to protein structural modifications including cleavage and unfolding/aggregation phenomena. PPO amounts higher than 10 U probably favoured enzyme conformations that were less prone to intermolecular rearrangements leading to inactivation.