bluuebunny/crossref_metadata_2025 huggingface dataset:
Spectral properties of the Dirichlet operator $\sum _{i=1}^{d}(-\partial _i^2)^{s}$∑i=1d(−∂i2)s on domains in d-dimensional Euclidean space
Authors: Hatzinikitas Agapitos N.
Published: October 2013

In this article, we investigate the distribution of eigenvalues of the Dirichlet pseudo-differential operator \documentclass[12pt]{minimal}\begin{document}$\sum _{i=1}^{d}(-\partial _i^2)^{s}, \, s\in (0,1]$\end{document}∑i=1d(−∂i2)s,s∈(0,1] on an open and bounded subdomain \documentclass[12pt]{minimal}\begin{document}$\Omega \subset \mathbb {R}^d$\end{document}Ω⊂Rd and predict bounds on the sum of the first N eigenvalues, the counting function, the Riesz means, and the trace of the heat kernel. Moreover, utilizing the connection of coherent states to the semi-classical approach of quantum mechanics, we determine the sum for moments of eigenvalues of the associated Schrödinger operator.
The molecular structure of and interconversion tunneling in the argon-cis-1,2-difluoroethylene complex
Authors: Leung Helen O. , Marshall Mark D. , Mueller Jessica L. , Amberger Brent K.
Published: October 2013

Guided by ab initio predictions, the structure of the gas-phase complex formed between cis-1,2-difluoroethylene and an argon atom in a pulsed molecular jet is determined using microwave spectroscopy in the 5.7–21.5 GHz region of the spectrum. This is a non-planar, symmetric species, with the argon atom located in the FCCF cavity of the difluoroethylene. The transitions in the microwave spectrum are observed to be split by an interconversion tunneling motion between the two equivalent configurations for the complex with the argon atom located either above or below the difluoroethylene molecular plane. Both one- and two-dimensional discrete variable representation calculations of the tunneling splitting using the ab initio interaction potential for the complex suggest that the barrier to interconversion is overestimated by theory.
One-dimensional potential of mean force underestimates activation barrier for transport across flexible lipid membranes
Authors: Kopelevich Dmitry I.
Published: October 2013

Transport of a fullerene-like nanoparticle across a lipid bilayer is investigated by coarse-grained molecular dynamics (MD) simulations. Potentials of mean force (PMF) acting on the nanoparticle in a flexible bilayer suspended in water and a bilayer restrained to a flat surface are computed by constrained MD simulations. The rate of the nanoparticle transport into the bilayer interior is predicted using one-dimensional Langevin models based on these PMFs. The predictions are compared with the transport rates obtained from a series of direct (unconstrained) MD simulations of the solute transport into the flexible bilayer. It is observed that the PMF acting on the solute in the flexible membrane underestimates the transport rate by more than an order of magnitude while the PMF acting on the solute in the restrained membrane yields an accurate estimate of the activation energy for transport into the flexible membrane. This paradox is explained by a coexistence of metastable membrane configurations for a range of the solute positions inside and near the flexible membrane. This leads to a significant reduction of the contribution of the transition state to the mean force acting on the solute. Restraining the membrane shape ensures that there is only one stable membrane configuration corresponding to each solute position and thus the transition state is adequately represented in the PMF. This mechanism is quite general and thus this phenomenon is expected to occur in a wide range of interfacial systems. A simple model for the free energy landscape of the coupled solute-membrane system is proposed and validated. This model explicitly accounts for effects of the membrane deformations on the solute transport and yields an accurate prediction of the activation energy for the solute transport.
Quantum molecular dynamics simulations of the thermophysical properties of shocked liquid ammonia for pressures up to 1.3 TPa
Authors: Li Dafang , Zhang Ping , Yan Jun
Published: October 2013

We investigate via quantum molecular-dynamics simulations the thermophysical properties of shocked liquid ammonia up to the pressure 1.3 TPa and temperature 120 000 K. The principal Hugoniot is predicted from the wide-range equation of state, which agrees well with the available experimental measurements up to 64 GPa. Our systematic study of the structural properties demonstrates that the liquid ammonia undergoes a gradual phase transition along the Hugoniot. At about 4800 K, the system transforms into a metallic, complex mixture state consisting of NH3, N2, H2, N, and H. Furthermore, we discuss the implications for the interiors of Uranus and Neptune.
Enhanced 2.0 μm emission from Ho3+ bridged by Yb3+ in Nd3+/Yb3+/Ho3+ triply doped tungsten tellurite glasses for a diode-pump 2.0 μm laser
Authors: Yuan J. , Shen S. X. , Wang W. C. , Peng M. Y. , Zhang Q. Y. , Jiang Z. H.
Published: October 2013

Enhanced 2.0 μm emission from Ho3+ bridged by Yb3+ in Nd3+/Yb3+/Ho3+ triply doped tungsten tellurite glasses has been demonstrated upon excitation with an 808 nm laser diode. Nd3+ with high absorption cross section near 808 nm plays an important role in 2.0 μm emission by transferring pump energy to Ho3+:5I5 level. The introduction of Yb3+ could greatly enhance the 2.0 μm emission. The energy transfer efficiency from Nd3+ to Ho3+ and Yb3+ increases from 36.4% to 89.5% with the addition of 5 mol. % Yb2O3, and the energy transfer coefficient from Nd3+ to Yb3+ (29.65 × 10−40 cm6/s) is larger than that from Nd3+ to Ho3+ (3.87 × 10−40 cm6/s). The underlying mechanism is analyzed by means of photoemission spectroscopy and lifetime measurement. The combination of Nd3+/Yb3+/Ho3+ could open up a possibility to realize high efficient 2.0 μm lasing from Ho3+, which could operate at an 808 nm diode laser pump.
Switching of spin-state complexes induced by the interaction of a laser beam with their host matrix
Authors: Hellel W. , Ould Hamouda A. , Degert J. , Létard J. F. , Freysz E.
Published: October 2013

We demonstrate that the interaction of a CO2 laser with a host matrix, in which spin-crossover compounds are diluted, makes it possible to induce a low-spin-to-high-spin transition. The phenomenon is demonstrated for two different compounds diluted in a commercial polymer. The photo-induced transition is due to laser-induced heating of the host-matrix, which results in a localized modification of the properties of the sample. This phenomenon is reversible, and its kinetics are well accounted for by a simple model. This process makes it possible to write optical information at a high speed and to erase it in such materials.
On the role of Ta cap in the recrystallization process of CoFeB layers
Authors: Bouchikhaoui H. , Stender P. , Akemeier D. , Baither D. , Hono K. , Hütten A. , Schmitz G.
Published: October 2013

To understand the role of Ta capping on the tunneling magnetoresistance of CoFeB/MgO/CoFeB tunnel junctions, we performed an atom probe study on model CoFeB/Ta junctions. In as-prepared state, CoFeB exhibits chemically and structurally homogeneous amorphous structure. The nanoanalysis demonstrates that B segregation to the Ta cap enforces crystallization to start at the opposite interface towards the MgO barrier and so warrants the correct orientation relation. Carrying out isothermal and isochronal heat treatments, the diffusion coefficient of Boron in amorphous CoFeB could be determined.
Room-temperature ferromagnetism in nanocrystalline Cu/Cu2O core-shell structures prepared by magnetron sputtering
Authors: Li Hao-Bo , Xie Xinjian , Wang Weichao , Cheng Yahui , Wang Wei-Hua , Li Luyan , Liu Hui , Wen Gehui , Zheng Rongkun
Published: October 2013

Cu/Cu2O core-shell nanoparticles with diameters around 8–9 nm have been fabricated by magnetron sputtering pure Cu targets with subsequent annealing in oxygen. Room-temperature ferromagnetism (FM) was observed in the samples annealed at 150 °C for 10–120 min. The maximum of saturated magnetization is as high as 19.8 emu/cc. The photoluminescence spectra show solid evidence that the FM originates from Cu vacancies in the Cu2O shell of the Cu/Cu2O core-shell nanoparticles. Furthermore, the FM can be modulated by the amount of Cu vacancies through the Cu/Cu2O core-shell interface engineering. Fundamentally, the FM can be understood by the charge-transfer ferromagnetism model based on Stoner theory.
The beat in laser-accelerated ion beams
Authors: Schnürer M. , Andreev A. A. , Abicht F. , Bränzel J. , Koschitzki Ch. , Platonov K. Yu. , Priebe G. , Sandner W.
Published: October 2013

Regular modulation in the ion velocity distribution becomes detectable if intense femtosecond laser pulses with very high temporal contrast are used for target normal sheath acceleration of ions. Analytical and numerical analysis of the experimental observation associates the modulation with the half-cycle of the driving laser field period. In processes like ion acceleration, the collective and laser-frequency determined electron dynamics creates strong fields in plasma to accelerate the ions. Even the oscillatory motion of electrons and its influence on the acceleration field can dominate over smoothing effects in plasma if a high temporal contrast of the driving laser pulse is given. Acceleration parameters can be directly concluded out of the experimentally observed modulation period in ion velocity spectra. The appearance of the phenomenon at a temporal contrast of ten orders between the intensity of the pulse peak and the spontaneous amplified emission background as well as remaining intensity wings at picosecond time-scale might trigger further parameter studies with even higher contrast.
Strain-domain structure and stability diagrams for single-domain magnetic thin films
Authors: Wang J. J. , Hu Jia-Mian , Chen Long-Qing , Nan Ce-Wen
Published: October 2013

Strain effects on domain structures and thermal stability in single-domain magnetic thin films were studied using thermodynamic analysis. The strain-domain structure and stability diagrams were established and compared to several existing experimental results. The structure diagram displays various stable single-domain states under in-plane normal and/or in-plane shear strains by minimizing the free energy density whereas the stability diagram takes into account possible thermal excitations and hence illustrate the thermally stable magnetic single-domain states. The results improve the understanding of strain-magnetization correlation in magnetic thin films and provide useful insight for the development of strain-engineered magnetic nanostructures with novel functionalities.
The impact of gross well width fluctuations on the efficiency of GaN-based light emitting diodes
Authors: Oliver R. A. , Massabuau F. C.-P. , Kappers M. J. , Phillips W. A. , Thrush E. J. , Tartan C. C. , Blenkhorn W. E. , Badcock T. J. , Dawson P. , Hopkins M. A. , Allsopp D. W. E. , Humphreys C. J.
Published: October 2013

Photoluminescence and electroluminescence measurements on InGaN/GaN quantum well (QW) structures and light emitting diodes suggest that QWs with gross fluctuations in width (formed when, during growth, the InGaN is exposed unprotected to high temperatures) give higher room temperature quantum efficiencies than continuous QWs. The efficiency does not depend on the growth temperature of the GaN barriers. Temperature-dependent electroluminescence measurements suggest that the higher efficiency results from higher activation energies for defect-related non-radiative recombination in QW samples with gaps. At high currents the maximum quantum efficiency is similar for all samples, indicating the droop term is not dependent on QW morphology.
Planar superconducting whispering gallery mode resonators
Authors: Minev Z. K. , Pop I. M. , Devoret M. H.
Published: October 2013

We introduce a microwave circuit architecture for quantum signal processing combining design principles borrowed from high-Q 3D resonators in the quantum regime and from planar structures fabricated with standard lithography. The resulting “2.5D” whispering-gallery mode resonators store 98% of their energy in vacuum. We have measured internal quality factors above 3 × 106 at the single photon level and have used the device as a materials’ characterization platform to place an upper bound on the surface resistance of thin film aluminum of less than 250 nΩ.
Stable few-layer MoS2 rectifying diodes formed by plasma-assisted doping
Authors: Chen Mikai , Nam Hongsuk , Wi Sungjin , Ji Lian , Ren Xin , Bian Lifeng , Lu Shulong , Liang Xiaogan
Published: October 2013

We present a method for making stable MoS2 rectifying diodes using selected-area plasma treatment. The transport and X-ray photoelectron spectroscopic characterizations of MoS2 transistors treated with different plasmas confirm that the rectifying characteristics of MoS2 diodes are attributed to plasma-induced p-doping and p-n junctions in MoS2. Such plasma-doped diodes exhibit high forward/reverse current ratios (∼104 for SF6-treated diodes) and a superior long-term stability. They can play an important role in the development of nanoelectronic devices. In addition, the presented plasma-assisted doping process could be also used for making ambipolar MoS2 transistors and functionalizing other emerging two-dimensional materials.
Luminescence thermometry with Zn2SiO4:Mn2+ powder
Authors: Lojpur V. , Nikolić M. G. , Jovanović D. , Medić M. , Antić Ž. , Dramićanin M. D.
Published: October 2013

Herein, temperature dependencies of emission and emission decay of Zn2SiO4:Mn2+ powder in the range from room temperature to 300 °C is reported. These dependencies allow temperature sensing from luminescence measurements, since Mn2+ emission intensity, emission band spectral position, and emission decay are rapidly changing over the entire temperature range. For fluorescence intensity ratio method, measurement that relays on emission intensity changes with temperature, sensitivity of 12.2% is found. In the case of lifetime thermometry, method that relays on emission decay changes with temperature, sensitivity of 0.48% is determined. Both sensitivity values are among the highest ever recorded for inorganic materials.
Investigation of Ge-Sn-Te alloy for long data retention and high speed phase change memory application
Authors: Zhang Zhonghua , Song Sannian , Song Zhitang , Cheng Yan , Rao Feng , Wu Liangcai , Liu Bo , Chen Bomy , Lu Yegang
Published: October 2013

Ge44Sn14Te42 phase change material exhibits a higher crystallization temperature (∼221 °C), a larger crystallization activation energy (∼2.88 eV) and a better data retention ability (∼126 °C for 10 years) in comparison with those of Ge2Sb2Te5. A reversible switching between set and reset can be realized by an electric pulse as short as 10 ns for Ge44Sn14Te42 based phase change memory (PCM) cell. In addition, PCM based on Ge44Sn14Te42 shows endurance up to 2.7 × 103 cycles with a resistance of about two orders of magnitude on/off ratio.
Underdamped Josephson junction as a switching current detector
Authors: Oelsner G. , Revin L. S. , Il'ichev E. , Pankratov A. L. , Meyer H.-G. , Grönberg L. , Hassel J. , Kuzmin L. S.
Published: October 2013

We demonstrate the narrow switching distribution of an underdamped Josephson junction from the zero to the finite voltage state at millikelvin temperatures. We argue that such junctions can be used as ultrasensitive detectors of the single photons in the GHz range, operating close to the quantum limit: a given initial (zero voltage) state can be driven by an incoming signal to the finite voltage state. The width of the switching distribution at a nominal temperature of about T = 10 mK was 4.5 nA, which corresponds to an effective noise temperature of the device below 60 mK.
Eddy current pulsed phase thermography for subsurface defect quantitatively evaluation
Authors: He Yunze , Pan Mengchun , Tian GuiYun , Chen Dixiang , Tang Ying , Zhang Hong
Published: October 2013

This Letter verified eddy current pulse phase thermography through numerical and experimental studies. During the numerical studies, two characteristic features, blind frequency and min phase, were extracted from differential phase spectra, and their monotonic relationships with defects' depth under different heating time were compared. According to the numerical studies, 100 ms was employed as heating time during the improved experimental studies. The experimental results agreed with the numerical results. Based on their linear relationship with defects' depths, both features can be used to measure the defect's depth.
Significant thermal conductivity enhancement in graphene oxide papers modified with alkaline earth metal ions
Authors: Yu Wei , Xie Huaqing , Li Fengxian , Zhao Junchang , Zhang Zhenhai
Published: October 2013

The thermal conductivities of graphene oxide paper (GOP) and the alkaline earth metal ions (Mg2+, Ca2+) modified analogues, prepared by a facile vacuum filtration method, were measured by a laser flash method. The thermal conductivities of GOP, Mg-modified GOP, and Ca-modified GOP are 3.91 W/(m × K), 32.05 W/(m × K), and 61.38 W/(m × K), respectively, which indicate the modification of GOP with metal ions has resulted in significant enhancement in thermal conduction properties compared with unmodified GOP. The crosslink between graphene oxide sheet and metal ions, the neat stacking of graphene oxide sheets in modified GOP, together with the intercalation of metal ions into the gallery spaces between the graphene oxide sheet basal planes, result in a decrease of thermal resistance of the boundary and an increase of contact surface, thus increases the thermal conductivity of modified graphene oxide paper.
Strain reduction and crystal improvement of an InGaN/GaN quantum-well light-emitting diode on patterned Si (110) substrate
Authors: Chen Chih-Yen , Hui Liu Zhan , Lin Chun-Han , Su Chia-Ying , Chang Ta-Wei , Shih Pei-Ying , Chen Horng-Shyang , Liao Che-Hao , Hsieh Chieh , Chou Wang-Hsien , Shen Chen-Hung , Kiang Yean-Woei , Yang C. C.
Published: October 2013

The comparisons of the morphology, material property, and optical characteristics of a crack-free InGaN/GaN quantum-well light-emitting diode (LED) structure of completely coalesced overgrowth on an a-axis-oriented one-dimensional trench-patterned Si (110) substrate with the other two samples grown on flat Si (110) and Si (111) substrates are demonstrated. This sample on patterned Si (110) substrate shows the highest crystal quality, weakest tensile strain, largest internal quantum efficiency, strongest LED output intensity, lowest device resistance, and smallest spectral shift range in increasing injection current. The small spectral shift range indicates the weak quantum-confined Stark effect. The advantages of this sample are attributed to the small lattice mismatch between Si and GaN along the m-axis, the reduced thermal stress along the m-axis, and the minimized upward-propagating dislocation density.
Accurate dispensing system for single oocytes using air ejection
Authors: Feng Lin , Sun Yiling , Ohsumi Chisato , Arai Fumihito
Published: October 2013

In this study, we propose a new approach to increase the success rate of single-oocyte dispensing and investigate the subsequent viability of the dispensed oocytes. We used a pair of capacitance sensors placed in a microfluidic chip to detect the oocyte, and custom-designed a special buffer zone in the microchannel to decelerate the flow velocity and reduce the hydraulic pressure acting on the oocyte. In the buffer zone, a semicircular bay, formed by equally spaced micro-pillars, is used to stop the oocyte at the dispensing nozzle hole. Finally, the oocyte is ejected by airflow to the culture array. The novel feature of the developed microfluidic system is that the extraordinary improvement in success rate is accompanied by a lack of change in oocyte survival rate (as assessed by a comparison of survival rates before and after the dispensing procedure). By using this device, we achieved a highly accurate single-oocyte dispensing process with a success rate of 100%. The oocyte survival rate is approximately 70%, regardless of whether or not the oocyte is dispensed. The newly proposed system has the advantages of high operation speed and potential usage for two-dimensional micropatterning.
Dual wavelength magneto-optical imaging of magnetic thin films
Authors: von Hofe Thomas , Onur Urs Necdet , Mozooni Babak , Jansen Thomas , Kirchhof Christine , Bürgler Daniel E. , Quandt Eckhard , McCord Jeffrey
Published: October 2013

A magneto-optical imaging approach for the simultaneous imaging of multiple magnetization components is demonstrated. The method is applied to investigate complex magnetization reversal processes in single crystal iron and patterned amorphous magnetostrictive ferromagnetic structures. The use of a splitted optical illumination and observation path allows for the direct extraction of different complementary magnetic information. Real-time in-plane vector magnetization imaging reveals complicated domain arrangement processes in magnetostrictive films due to locally varying stress induced magnetic anisotropy. Magnetic domain features concealed by standard domain imaging techniques are directly exposed.
Pumping of water through carbon nanotubes by rotating electric field and rotating magnetic field
Authors: Li Xiao-Peng , Kong Gao-Pan , Zhang Xing , He Guo-Wei
Published: October 2013

Using molecular dynamics simulations, we demonstrate pumping of water through a carbon nanotube by applying the combination of a rotating electric field and a rotating magnetic field. The driving force is a Lorentz force generated from the motion of charges in the magnetic field, and the motion is caused by the rotation of the electric field. We find that there exits a linear relationship between the average pumping velocity v and magnetic field strength B, which can be used to control the flux of the continuous unidirectional water flow. This approach is expected to be used in liquid circulation without a pressure gradient.
Determination of the distribution of transverse magnetic anisotropy in thin films from the second harmonic of Kerr signal
Authors: García-Arribas A. , Fernández E. , Orue I. , Barandiaran J. M.
Published: October 2013

We describe a method to determine the magnetic anisotropy distribution in thin films based on Kerr magnetometry, well adapted for single micro- and nanostructures. When the sample is excited by an ac field of small amplitude, for each value of a longitudinal dc field H, the second harmonic of the Kerr signal gives the contribution of the corresponding transverse anisotropy field Hk=H to the anisotropy distribution. The method is tested on a Permalloy-based multilayer microstructure, revealing two anisotropy contributions, one of them deviated from the perfect transverse direction. This confirms and extends a previous characterization performed by far more sophisticated methods.
Characterisation of novel perennial ryegrass host–Neotyphodium endophyte associations
Authors: Tian P. , Le T.-N. , Ludlow E. J. , Smith K. F. , Forster J. W. , Guthridge K. M. , Spangenberg G. C.
Published: October 2013

The temperate pasture grass Lolium perenne L. is commonly found in symbiotic association with the asexual fungal endophyte Neotyphodium lolii. Levels of endophyte colonisation and alkaloid content were evaluated in associations formed by plant genotypes from cv. Bronsyn with the standard endophyte (SE) and five distinct commercial endophyte strains. Bronsyn–SE produced all of the measured alkaloids (lolitrem B, peramine, and ergovaline). Bronsyn–AR1 produced only peramine, while Bronsyn–AR37 produced none of the tested alkaloids. Bronsyn–NEA2, Bronsyn–NEA3, and Bronsyn–NEA6 produced both ergovaline and peramine. Both endophyte strain and host genotype exerted significant effects on alkaloid production. Analysis of endophyte colonisation using qPCR revealed differences between each association. With the exception of Bronsyn–AR1 and Bronsyn–NEA3, host genotype also significantly affected colonisation levels. Phenotypic performance of each association was also assessed, based on measurement of morphological traits under glasshouse conditions in hydroponic culture. Significant variation due to different endophyte and host genotypes was observed. Collectively, these studies confirm that differences in both endophyte and host genotypes contribute to host–endophyte performance in a complex interactive manner.
Leaf growth and senescence rates of three pasture grasses and wheat
Authors: Daily Helen G. , Lane Peter A. , Lisson Shaun N. , Bridle Kerry L. , Anderson Stuart A. J. , Corkrey Ross
Published: October 2013

A glasshouse study was conducted under ideal conditions to determine leaf appearance, elongation, and senescence rates along with life span and leaf length characteristics of four grass species: wheat (Triticum aestivum L.), brown back wallaby grass (Rytidosperma duttonianum (Cashmore) Connor and Edgar), phalaris (Phalaris aquatica L.), and annual ryegrass (Lolium rigidum Gaud.). This study provided a comprehensive characterisation of leaf turnover rates for the entire life cycle of these grasses, some of which are poorly characterised. Importantly, leaf senescence rate has been captured in the same conditions as the other leaf rates of the life cycle. Leaf position proved to be a significant explanatory variable in each of the leaf turnover rates. The relationships between leaf position and the components of leaf turnover were most commonly represented by non-linear models. Further studies may be necessary to validate these statistical models to field situations. However, this information will be useful to calibrate the senescence algorithms of plant growth models in agricultural decision support tools, which may then be applied to simulation studies including the assessment of grass curing for planning activities such as resource allocation, wildfire suppression, and execution of prescribed burning programs by fire management agencies.
The other side of the coin: the downside of Norway's savings of petroleum rents
Authors: Hannesson Rögnvaldur
Published: October 2013

The Norwegian government gets a substantial income from oil and gas extraction, both through taxes and partnerships with oil companies. In recent years (2009–2011), this has amounted to about 25% of government revenues. The Norwegian parliament has endorsed a savings guideline aimed at preserving petroleum wealth. Actual savings of petroleum revenues are compared with what this guideline stipulates, and the guideline itself is compared to the Hicksian permanent income rule for wealth preservation. While the Norwegian savings policy has been successful from a macroeconomic perspective it has been less so from a microeconomic perspective. Over the last 15 years expenditure on disability and sick leave has increased rapidly while expenditure on transportation infrastructure has stagnated. These trends are compared with the trends in similar expenditures in Sweden and Denmark. On the basis of the Norwegian experience, I discuss to what extent institutional design can guard against misinformation or misaligned incentives and to what extent the Norwegian petroleum fund design could be useful for underdeveloped but resource rich countries.
Microenzymatic Evaluation of Oat (Avena sativa L.) β‐Glucan for High‐Throughput Phenotyping
Authors: Newell Mark A. , Kim Hyun Jung , Asoro Franco G. , Lauter Adrienne Moran , White Pamela J. , Scott M. Paul , Jannink Jean‐Luc
Published: October 2013

Oats (Avena sativa L.) have received significant attention for their positive and consistent health benefits when consumed as a whole grain food, attributed in part to mixed‐linkage (1‐3,1‐4)‐β‐d‐glucan (referred to as β‐glucan). Unfortunately, the standard enzymatic method of measurement for oat β‐glucan is costly and does not provide the high‐throughput capability needed for plant breeding in which thousands of samples are measured over a short period of time. The objective of this research was to test a microenzymatic approach for high‐throughput phenotyping of oat β‐glucan. Fifty North American elite lines were chosen to span the range of possible values encountered in elite oats. Pearson and Spearman correlations (r) ranged from 0.81 to 0.86 between the two methods. Although the microenzymatic method did contain bias compared with the results for the standard streamlined method, this bias did not substantially decrease its ability to determine β‐glucan content. In addition to a substantial decrease in cost, the microenzymatic approach took as little as 6% of the time compared with the streamlined method. Therefore, the microenzymatic method for β‐glucan evaluation is an alternative method that can enhance high‐throughput phenotyping in oat breeding programs.
First Report on Natural Infection of Paeonia tenuifolia by ‘Candidatus Phytoplasma solani’ in Serbia
Authors: Adamovic D. , Djalovic I. , Mitrovic P. , Kojic S. , Pivic R. , Josic D.
Published: October 2013

Peony (Paeonia tenuifolia L.) is a herbaceous perennial plant known for its beautiful and showy flowers. In Serbia it is native to the Deliblato Sands and is used as an ornamental and medicinal plant in folk medicine. This plant species has become a rarity and for that reason peony was introduced into a botanical collection near Backi Petrovac (northern Serbia), where it has been maintained since 1988. Reddening of lower leaves observed on 10% of plants (5 of 50) in the collection at flowering in May 2012 gradually progressed throughout affected plants by the seed maturation stage. Five leaves from each of three reddened and three symptomless plants were sampled at the end of July 2012. Total nucleic acid was extracted separately from individual leaves (30 samples) using the CTAB (cetyltrimethylammonium bromide) method (2). A nested PCR assay using universal primer pairs P1/P7, followed by R16F2n/R16R2 (4), amplified 16S rDNA fragments of 1.8 and 1.2 kb, respectively. DNA from all three reddened plants (15 samples) yielded 1.2-kb amplicons after nested PCRs. Restriction fragment length polymorphism (RFLP) patterns obtained by digestion of nested products with endonucleases AluI, TruI, HpaII, or HhaI (Thermo Scientific, Lithuania) (4) were identical to those of the STOL reference strain included for comparative purposes, indicating that symptoms were consistently associated with plant infection by ‘Ca. Phytoplasma solani’ (Stolbur) phytoplasma. The 16S rDNA amplicons from two peony plants (1.2 kb from B15 and 1.8 from B18) were sequenced (GenBank Accession No. KC960487 and KF614623, respectively). BLAST analysis revealed a 100% identity between the sequences and GenBank sequences of Stolbur phytoplasma, subgroup 16SrXII-A phytoplasma, previously detected in maize (JQ730750) in Serbia and red clover (EU814644.1) in the Czech Republic. Phytoplasma associated diseases of other species of the genus Paeonia (P. lactiflora Pall. and P. suffruticosa Andrews) have been described elsewhere. Disease symptoms on P. lactiflora from Chile were associated with the phytoplasma that belongs to the ribosomal subgroup 16SrVII-A (‘Ca. Phytoplasma fraxini’) (1). Also, Stolbur phytoplasma from the 16SrXII group was detected on P. suffruticosa plants in China, manifesting yellowing symptoms (3). To our knowledge, this is the first report of naturally occurring Stolbur phytoplasma disease of P. tenuifolia L. in Serbia.

References: (1) N. Arismendi et al. Bull. Insectol. 64:S95, 2011. (2) X. Daire et al. Eur. J. Plant Pathol. 103:507, 1997. (3) Y. Gao et al. J. Phytopathol. 161:197, 2013. (4) I. M. Lee et al. Int. J. Syst. Bacteriol. 48:1153, 1998.
Development of Multilocus PCR Assays for Raffaelea lauricola, Causal Agent of Laurel Wilt Disease
Authors: Dreaden Tyler J. , Davis John M. , Harmon Carrie L. , Ploetz Randy C. , Palmateer Aaron J. , Soltis Pamela S. , Smith Jason A.
Published: October 2013

Laurel wilt, caused by the fungus Raffaelea lauricola, is an exotic disease that affects members of the Lauraceae plant family in the southeastern United States. The disease is spreading rapidly in native forests and is now found in commercial avocado groves in south Florida, where an accurate diagnostic method would improve disease management. A polymerase chain reaction (PCR) method based on amplifying the ribosomal small-subunit DNA, with a detection limit of 0.0001 ng, was found to be suitable for some quantitative PCR applications; however, it was not taxon specific. Genomic sequencing of R. lauricola was used to identify and develop primers to amplify two taxon-specific simple-sequence repeat (SSR) loci, which did not amplify from related taxa or host DNA. The new SSR loci PCR assay has a detection limit of 0.1 ng of R. lauricola DNA, is compatible with traditional and real-time PCR, was tested in four labs to confirm consistency, and reduces diagnostic time from 1 week to 1 day. Our work illustrates pitfalls to designing taxon-specific assays for new pathogens and that undescribed fungi can limit specificity.
Exploitation of FTA Cartridges for the Sampling, Long-Term Storage, and DNA-Based Analyses of Plant-Parasitic Nematodes
Authors: Marek Martin , Zouhar Miloslav , Douda Ondřej , Maňasová Marie , Ryšánek Pavel
Published: October 2013

The use of DNA-based analyses in molecular plant nematology research has dramatically increased over recent decades. Therefore, the development and adaptation of simple, robust, and cost-effective DNA purification procedures are required to address these contemporary challenges. The solid-phase-based approach developed by Flinders Technology Associates (FTA) has been shown to be a powerful technology for the preparation of DNA from different biological materials, including blood, saliva, plant tissues, and various human and plant microbial pathogens. In this work, we demonstrate, for the first time, that this FTA-based technology is a valuable, low-cost, and time-saving approach for the sampling, long-term archiving, and molecular analysis of plant-parasitic nematodes. Despite the complex structure and anatomical organization of the multicellular bodies of nematodes, we report the successful and reliable DNA-based analysis of nematode high-copy and low-copy genes using the FTA technology. This was achieved by applying nematodes to the FTA cards either in the form of a suspension of individuals, as intact or pestle-crushed nematodes, or by the direct mechanical printing of nematode-infested plant tissues. We further demonstrate that the FTA method is also suitable for the so-called “one-nematode-assay”, in which the target DNA is typically analyzed from a single individual nematode. More surprisingly, a time-course experiment showed that nematode DNA can be detected specifically in the FTA-captured samples many years after initial sampling occurs. Collectively, our data clearly demonstrate the applicability and the robustness of this FTA-based approach for molecular research and diagnostics concerning phytonematodes; this research includes economically important species such as the stem nematode (Ditylenchus dipsaci), the sugar beet nematode (Heterodera schachtii), and the Northern root-knot nematode (Meloidogyne hapla).
Evaluation of the DNA-dependent RNA polymerase β-subunit gene (rpoB) for phytoplasma classification and phylogeny
Authors: Valiunas Deividas , Jomantiene Rasa , Davis Robert Edward
Published: October 2013

Phytoplasmas are classified into 16Sr groups and subgroups and ‘Candidatus

Phytoplasma
’ species, largely or entirely based on analysis of 16S rRNA gene sequences. Yet, distinctions among closely related ‘Ca.

Phytoplasma
’ species and strains based on 16S rRNA genes alone have limitations imposed by the high degree of rRNA nucleotide sequence conservation across diverse phytoplasma lineages and by the presence in a phytoplasma genome of two, sometimes sequence-heterogeneous, copies of the 16S rRNA gene. Since the DNA-dependent RNA polymerase (DpRp) β-subunit gene (rpoB) exists as a single copy in the phytoplasma genome, we explored the use of rpoB for phytoplasma classification and phylogenetic analysis. We sequenced a clover phyllody (CPh) phytoplasma genetic locus containing ribosomal protein genes, a complete rpoB gene and a partial rpoC gene encoding the β′-subunit of DpRp. Primers and reaction conditions were designed for PCR-mediated amplification of rpoB gene fragments from diverse phytoplasmas. The rpoB gene sequences from phytoplasmas classified in groups 16SrI, 16SrII, 16SrIII, 16SrX and 16SrXII were subjected to sequence similarity and phylogenetic analyses. The rpoB gene sequences were more variable than 16S rRNA gene sequences, more clearly distinguishing among phytoplasma lineages. Phylogenetic trees based on 16S rRNA and rpoB gene sequences had similar topologies, and branch lengths in the rpoB tree facilitated distinctions among closely related phytoplasmas. Virtual RFLP analysis of rpoB gene sequences also improved distinctions among closely related lineages. The results indicate that the rpoB gene provides a useful additional marker for phytoplasma classification that should facilitate studies of disease aetiology and epidemiology.
Genome sequence analyses show that

Neisseria oralis

is the same species as ‘

Neisseria mucosa

var. heidelbergensis’
Authors: Bennett Julia S. , Jolley Keith A. , Maiden Martin C. J.
Published: October 2013

Phylogenies generated from whole genome sequence (WGS) data provide definitive means of bacterial isolate characterization for typing and taxonomy. The species status of strains recently defined with conventional taxonomic approaches as representing

Neisseria oralis

was examined by the analysis of sequences derived from WGS data, specifically: (i) 53

Neisseria

ribosomal protein subunit (rps) genes (ribosomal multi-locus sequence typing, rMLST); and (ii) 246

Neisseria

core genes (core genome MLST, cgMLST). These data were compared with phylogenies derived from 16S and 23S rRNA gene sequences, demonstrating that the

N. oralis

strains were monophyletic with strains described previously as representing ‘

Neisseria mucosa

var. heidelbergensis’ and that this group was of equivalent taxonomic status to other well-described species of the genus

Neisseria

. Phylogenetic analyses also indicated that

Neisseria sicca

and

Neisseria macacae

should be considered the same species as

Neisseria mucosa

and that

Neisseria flavescens

should be considered the same species as

Neisseria subflava

. Analyses using rMLST showed that some strains currently defined as belonging to the genus

Neisseria

were more closely related to species belonging to other genera within the family; however, whole genome analysis of a more comprehensive selection of strains from within the family

Neisseriaceae

would be necessary to confirm this. We suggest that strains previously identified as representing ‘

N. mucosa

var. heidelbergensis’ and deposited in culture collections should be renamed

N. oralis

. Finally, one of the strains of

N. oralis

was able to ferment lactose, due to the presence of β-galactosidase and lactose permease genes, a characteristic previously thought to be unique to

Neisseria lactamica

, which therefore cannot be thought of as diagnostic for this species; however, the rMLST and cgMLST analyses confirm that

N. oralis

is most closely related to

N. mucosa

.
A single amino acid in the F2 subunit of respiratory syncytial virus fusion protein alters growth and fusogenicity
Authors: Lawlor Heather A. , Schickli Jeanne H. , Tang Roderick S.
Published: October 2013

Respiratory syncytial virus (RSV) causes severe lower respiratory tract infection in children, especially in infants less than 1 year of age. There are currently no licensed vaccines against RSV. rA2ΔM2-2 is a promising live-attenuated vaccine candidate that is currently being evaluated in the clinic. Attenuation of rA2ΔM2-2 is achieved by a single deletion of the M2-2 gene, which disrupts the balance between viral transcription and replication. Whilst performing a manufacturing feasibility study in a serum-free adapted Vero cell line, differences in growth kinetics and cytopathic effect (CPE) were identified between two rA2ΔM2-2 vaccine candidates. Comparative sequence analysis identified four amino acid differences between the two vaccine viruses. Recombinant rA2ΔM2-2 viruses carrying each of the four amino acid differences identified a K66E mutation in the F2 fragment of the fusion (F) protein as the cause of the growth and CPE differences. Syncytium-formation experiments with RSV F protein carrying mutations at aa 66 suggested that a change in charge at this residue within the F2 fragment can have a significant impact on fusion.
Development of chimaeric West Nile virus attenuated vaccine candidate based on the Japanese encephalitis vaccine strain SA14-14-2
Authors: Li Xiao-Feng , Zhao Wei , Lin Fang , Ye Qing , Wang Hong-Jiang , Yang Dong , Li Shi-Hua , Zhao Hui , Xu Yan-Peng , Ma Jie , Deng Yong-Qiang , Zhang Yu , Qin E-De , Qin Cheng-Feng
Published: October 2013

Mosquito-borne flaviviruses include a large group of important human medical pathogens. Several chimaeric flaviviruses have been constructed, and show potential for vaccine development. Although Japanese encephalitis virus (JEV) live vaccine SA14-14-2 has been widely used with ideal safety and efficacy profiles, no chimaeric flavivirus based on the JEV vaccine has been described to date. Based on the reverse genetic system of the JEV vaccine SA14-14-2, a novel live chimaeric flavivirus carrying the protective antigens of West Nile virus (WNV) was constructed and recovered in this study. The resulting chimaera (ChinWNV) replicated efficiently in both mammalian and mosquito cells and possessed genetic stability after in vitro serial passaging. ChinWNV exhibited a small-plaque phenotype, and its replication was significantly restricted in mouse peripheral blood and brain compared with parental WNV. Importantly, ChinWNV was highly attenuated with regard to both neurovirulence and neuroinvasiveness in mice. Furthermore, a single ChinWNV immunization stimulated robust WNV-specific adaptive immune responses in mice, conferring significant protection against lethal WNV infection. Our results demonstrate that chimaeric flaviviruses based on the JEV vaccine can serve as a powerful platform for vaccine development, and that ChinWNV represents a potential WNV vaccine candidate that merits further development.
N-[2-(Pyridin-2-yl)ethyl]-derivatives of methane-, benzene- and toluenesulfonamide: prospective ligands for metal coordination
Authors: Jacobs Danielle L. , Chan Benny C. , O'Connor Abby R.
Published: October 2013

The molecular and supramolecular structures are reported ofN-[2-(pyridin-2-yl)ethyl]methanesulfonamide, C8H12N2O2S, (I),N-[2-(pyridin-2-yl)ethyl]benzenesulfonamide, C13H14N2O2S, (II), andN-[2-(pyridin-2-yl)ethyl]toluenesulfonamide, C14H16N2O2S, (III). Although (II) and (III) are almost structurally identical, the N(amide)—C(ethyl)—C(ethyl)—C(pyridinyl) torsion angles for (I) and (II) are more closely comparable, with magnitudes of 175.37 (15)° for (I) and 169.04 (19)° for (II). This angle decreases dramatically with an additional methyl group in theparaposition of the sulfonamide substituent, resulting in a value of 62.9 (2)° for (III). In each of the three compounds there is an N—H...N hydrogen bond between the sulfonamide of one molecule and the pyridine N atom of a neighbor. Compound (I) forms hydrogen-bonded dimers, (II) uses its hydrogen bonding to connect supramolecular layers, and the hydrogen bonding of (III) connects linear chains to form layers. For arene-substituted (II) and (III), the different conformations afforded by the variable dihedral angles promote intermolecular π–π stacking in the benzene-substituted structure (II), but distorted intramolecular T-shaped π-stacking in the toluene-substituted structure (III), with a centroid-to-centroid distance of 4.9296 (10) Å.
A two-dimensional network containing an –Mn—O—C—O—Mn– chain: poly[diaqua[1,2-bis(pyridin-4-yl)ethylene][μ3-3-carboxy-5-(carboxylatomethoxy)benzoato]manganese(II)]
Authors: Lei Yong-Qian , Wang Guan-Hua
Published: October 2013

In the title compound, [Mn(C10H6O7)(C12H10N2)(H2O)2]nor [Mn(HOABDC)(bpe)(H2O)2]n[H3OABDC is 5-(carboxymethoxy)isophthalic acid and bpe is 1,2-bis(pyridin-4-yl)ethylene], each MnIIcation is at the centre of a distorted octahedron formed by three carboxylate O atoms from three different HOABDC2−ligands, one pyridyl N atom from the terminal bpe ligand and two water molecules. The flexible oxyacetate group bound to a methylene C atom of the HOABDC2−ligand links the MnIIcentres into –Mn—O—C—O—Mn– chains, and the carboxylate group bound directly to the benzene ring extends the chains into two-dimensional layers which lie parallel to the (010) plane and present herringbone patterns. Intermolecular O—H...N and C—H...O hydrogen bonds connect the layers into a three-dimensional supramolecular structure.
The purine–carboxylate-containing coordination polymer poly[[μ4-1-(2-carboxylatoethyl)-6-oxo-6,9-dihydro-1H-purin-9-ido]zinc(II)]
Authors: Ma Wen-Juan , Li Guo-Ting
Published: October 2013

The title compound, [Zn(C8H6N4O3)]nor [Zn(L)]n[H2Lis 3-(6-oxo-6,9-dihydro-1H-purin-1-yl)propionic acid], crystallized as a nonmerohedral twin. The ZnIIcation is four-coordinated, ligated by two carboxylate O atoms from twoLligands and two N atoms from another two ligands. Each ligand bridges four ZnIIcentres, extending the structure into a three-dimensional polymer with a 4-connected (65,41) topological structure containing two-dimensional homochiral layers constructed from one-dimensional metal–organic helices. Investigation of the thermal stability of the compound shows that the network has very high thermostability and is stable up to 720 K.
More about residual values
Authors: Henn Julian , Schönleber Andreas
Published: October 2013

The usual residual values are complemented by expectation values based solely on the experimental data and the number of model parameters. These theoreticalRvalues serve as benchmark values when all of the basic assumptions for a least-squares refinement,i.e.no systematic errors and a fully adequate model capable of describing the data, are fulfilled. The prediction ofRvalues as presented here is applicable to any field where model parameters are fitted to data with known precision. For crystallographic applications,F2-based residual benchmark values are given. They depend on the first and second moments of variance, intensity and significance distributions, 〈σ2〉, 〈Io2〉, 〈Io2/σ2〉. Possible applications of the theoreticalRvalues are, for example, as a data-quality measure or the detection of systematic deviations between experimental data and model predicted data, although the theoreticalRvalues cannot identify the origin of these systematic deviations. The change inRvalues due to application of a weighting scheme is quantified with the theoreticalRvalues.
2-(4-Fluorophenyl)-4-(thiophen-2-yl)-2,3-dihydro-1,5-benzothiazepine
Authors: Manjula M. , Manjunath B. C. , Renuka N. , Ajay Kumar K. , Lokanath N. K.
Published: October 2013

In the title compound, C19H14FNS2, the seven-membered thiazepine ring adopts a slightly distorted twist boat conformation. The dihedral angle between the benzene rings is 53.6 (1)°. The mean plane of the thiazepine ring is twisted by 34.3 (7)° and 36.6 (7)° from the benezene rings. A C—H...F interaction generates stacking of molecules along theabplane.
2,3-Bis(furan-2-yl)pyrazino[2,3-f][1,10]phenanthroline
Authors: Dong Wen-xian , Tong Rong-rong , Zheng Chang-ge
Published: October 2013

The molecule of the title compound, C22H12N4O2, is located on a twofold rotation axis. The dihedral angle between the furan and pyrazine rings is 34.8 (7)°, and that between the furan rings is 46.92 (7)°. A π–π stacking interaction occurs between adjacent pyrazino[2,3-f][1,10]phenanthroline units, with an interplanar distance of 3.5862 (12) Å.