bluuebunny/crossref_metadata_2025 huggingface dataset:
Development of microsatellite markers at the National Agrobiodiversity Center in Korea for the genetic assessment of underutilized crops
Authors: Lee Gi-An , Lee Sok-Young , Lee Ho-Sun , Ma Kyung-Ho , Gwag Jae-Gyun , Kim Yeon-Gyu , Lee Jung-Ro
Published: July 2014

The RDA Genebank at the National Agrobiodiversity Center (NAAS, RDA, Republic of Korea) has conserved about 182,000 accessions in 1777 species and is working at preserving agricultural genetic resources for the conservation and sustainable utilization of genetic diversity. The detection of genetic variability in conserved resources is important for germplasm management, but the molecular evaluation tools providing genetic information are insufficient for underutilized crops, unlike those for major crops. In this regard, the Korean National Agrobiodiversity Center has been developing microsatellite markers for several underutilized crops. We designed 3640 primer pairs flanking simple sequence repeat (SSR) motifs for 6310 SSR clones in 21 crop species. Polymorphic loci were revealed in each species (7–36), and the mean ratio of polymorphic loci to all the loci tested was 12%. The average allele number was 5.1 (2.8–10.3) and the expected heterozygosity 0.51 (0.31–0.74). Some SSRs were transferable to closely related species, such as within the generaFagopyrumandAllium. These SSR markers might be used for studying the genetic diversity of conserved underutilized crops.
Genetic diversity and variation analysis of mutant lines derived from γ-ray and chemical mutagen treatments in blackberry (Rubus fruticosus)
Authors: Ryu Jaihyunk , Ha Bo-Keun , Kim Dong Sub , Kim Jin-Baek , Kim Sang Hoon , Ahn Joon-Woo , Jeong Il Yun , Jo Han-Jik , Kim Ee-Yup , Kang Si-Yong
Published: July 2014

Blackberry is a fruiting berry species with very high nutrient contents. With the recent increasing consumer demand for blackberries, new sources of germplasm and breeding techniques are required to improve blackberry production. This study was carried out to evaluate the genetic diversity (GD) and relationship among 55 blackberry (Rubus fruticosus) mutants derived from γ-ray treatment (52 lines) and N-methyl-N′-nitrosourea (MNU) treatment (three lines) using an inter-simple sequence repeat marker. A total of 18 bands were amplified with an average of 3.6 bands per primer. Among them, eight bands were identified to be polymorphic with a rate of 44.4%. In addition, the GD information content values were highest in the 60 Gy treatment population and the GD values were higher in the γ-ray treatment populations than in the MNU treatment population. According to a cluster analysis, all the mutant lines can be classified into five categories, and the genetic distance was greatest between the 80 Gy-irradiated population and other populations. These results indicate that mutant lines have high GD and can be effectively utilized for improving blackberry breeding.
Identification of platelet function defects by multi-parameter assessment of thrombus formation
Authors: de Witt Susanne M. , Swieringa Frauke , Cavill Rachel , Lamers Moniek M. E. , van Kruchten Roger , Mastenbroek Tom , Baaten Constance , Coort Susan , Pugh Nicholas , Schulz Ansgar , Scharrer Inge , Jurk Kerstin , Zieger Barbara , Clemetson Kenneth J. , Farndale Richard W. , Heemskerk Johan W. M. , Cosemans Judith M.E.M.
Published: July 2014

Assays measuring platelet aggregation (thrombus formation) at arterial shear rate mostly use collagen as only platelet-adhesive surface. Here we report a multi-surface and multi-parameter flow assay to characterize thrombus formation in whole blood from healthy subjects and patients with platelet function deficiencies. A systematic comparison is made of 52 adhesive surfaces with components activating the main platelet-adhesive receptors, and of eight output parameters reflecting distinct stages of thrombus formation. Three types of thrombus formation can be identified with a predicted hierarchy of the following receptors: glycoprotein (GP)VI, C-type lectin-like receptor-2 (CLEC-2)>GPIb>α6β1, αIIbβ3>α2β1>CD36, α5β1, αvβ3. Application with patient blood reveals distinct abnormalities in thrombus formation in patients with severe combined immune deficiency, Glanzmann’s thrombasthenia, Hermansky–Pudlak syndrome, May–Hegglin anomaly or grey platelet syndrome. We suggest this test may be useful for the diagnosis of patients with suspected bleeding disorders or a pro-thrombotic tendency.
Impact of residues remote from the catalytic centre on enzyme catalysis of copper nitrite reductase
Authors: Leferink Nicole G. H. , Antonyuk Svetlana V. , Houwman Joseline A. , Scrutton Nigel S. , Eady Robert R. , Hasnain S. Samar
Published: July 2014

Enzyme mechanisms are often probed by structure-informed point mutations and measurement of their effects on enzymatic properties to test mechanistic hypotheses. In many cases, the challenge is to report on complex, often inter-linked elements of catalysis. Evidence for long-range effects on enzyme mechanism resulting from mutations remains sparse, limiting the design/redesign of synthetic catalysts in a predictable way. Here we show that improving the accessibility of the active site pocket of copper nitrite reductase by mutation of a surface-exposed phenylalanine residue (Phe306), located 12 Å away from the catalytic site type-2 Cu (T2Cu), profoundly affects intra-molecular electron transfer, substrate-binding and catalytic activity. Structures and kinetic studies provide an explanation for the lower affinity for the substrate and the alteration of the rate-limiting step in the reaction. Our results demonstrate that distant residues remote from the active site can have marked effects on enzyme catalysis, by driving mechanistic change through relatively minor structural perturbations.
Long-term changes in the ghrelin-CB1R axis associated with the maintenance of lower body weight after sleeve gastrectomy
Authors: Fedonidis C , Alexakis N , Koliou X , Asimaki O , Tsirimonaki E , Mangoura D
Published: July 2014

Objectives:

In the hypothalamus, the molecular actions of receptors for growth hormone secretagogue (ghrelin) receptor-GHSR, leptin receptor-b (LEPRb), Melanocortin-4 receptor (MC4R) and Cannabinoid-1 receptor (CB1R) regulate energy homeostasis and body weight. We hypothesized that the acute loss of stomach tissue upon sleeve gastrectomy (SG), performed to treat obesity, imposes modulations on the expression of these receptors in the brain to sustain weight loss.

Methods:

Rats, induced to obesity with high-fat diet were randomized to SG- or sham-operation groups and killed at 30 or 90 days post surgery, when the expression of Ghrl, Mboat4 and Cnr1 in the stomach, and Ghsr, Leprb, Mc4r and Cnr1 in distinct brain areas was assessed by reverse transcription-PCR and western blotting.

Results:

SG acutely reduced body weight and fat mass and suppressed the remnant stomach mRNA levels of preproghrelin and ghrelin O-acyltransferase, which correlated well with long-term decreases in CB1R mRNA. In the hypothalamus, increases in GHSR and decreases in CB1R and LEPRb by 30 days were followed by further downregulation of CB1R and an increase in MC4R by 90 days.

Conclusions:

Post SG, acyl-ghrelin initiates a temporal hierarchy of molecular events in the gut-brain axis that may both explain the sustained lower body weight and suggest intervention into the cannabinoid pathways for additional therapeutic benefits.
A unique fluorescence biosensor for selective detection of tryptophan and histidine
Authors: Sutariya Pinkesh G. , Pandya Alok , Lodha Anand , Menon Shobhana K.
Published: July 2014

A novel photoinduced electron transfer (PET) based substituted calix[4]arene fluoroionophore has been used for the selective recognition of tryptophan (l-Trp) and histidine (l-His) by emission spectra.
Application of Fourier transform near-infrared spectroscopy to the quantification and monitoring of carbonyl value in frying oils
Authors: Wang Yage , Yu Xiuzhu , Chen Xiumei , Yang Yandie , Zhang Jingya
Published: July 2014

FT-NIR method towards carbonyl value (CV) has been developed and applied in monitoring CV changes in frying process.
Stereodefined acyclic trisubstituted metal enolates towards the asymmetric formation of quaternary carbon stereocentres
Authors: Minko Yury , Marek Ilan
Published: July 2014

Formation of highly diastereo- and enantiomerically enriched quaternary stereocentres from stereodefined acyclic trisubstituted metal enolates.
Proteolytic stability of amphipathic peptide hydrogels composed of self-assembled pleated β-sheet or coassembled rippled β-sheet fibrils
Authors: Swanekamp Ria J. , Welch Jade J. , Nilsson Bradley L.
Published: July 2014

Hydrogel networks composed of rippled β-sheet fibrils of coassembled d- and l-Ac-(FKFE)2-NH2 amphipathic peptides exhibit proteolytic stability and increased rheological strength compared to networks of self-assembled l-Ac-(FKFE)2-NH2 pleated β-sheet fibrils.
Fabrication of both the photoactive layer and the electrode by electrochemical assembly: towards a fully solution-processable device
Authors: Gao Yixing , Qi Ji , Zhang Jian , Kang Shusen , Qiao Wenqiang , Li Mao , Sun Haizhu , Zhang Jingping , Ariga Katsuhiko
Published: July 2014

We report an economical route to achieve an all-solution and vacuum-deposition free device under normal atmospheric pressure for fabrication of both the photoactive layer and the electrode.
Ab initio studies of propene epoxidation on oxidized silver surfaces
Authors: Molina L. M. , López M. J. , Alonso J. A.
Published: July 2014

Pathways for propene oxide, acrolein and propanone formation on oxidized silver surfaces are studied using DFT simulations.
DFT studies of oxygen dissociation on the 116-atom platinum truncated octahedron particle
Authors: Jennings Paul C. , Aleksandrov Hristiyan A. , Neyman Konstantin M. , Johnston Roy L.
Published: July 2014

Oxygen dissociation studies performed on Pt116 nanoparticles highlight the importance of surface flexibility for fast reaction kinetics.
Structural and electronic properties of the Ptn–PAH complex (n = 1, 2) from density functional calculations
Authors: Mahmoodinia Mehdi , Ebadi Mahsa , Åstrand Per-Olof , Chen De , Cheng Hong-Ye , Zhu Yi-An
Published: July 2014

The catalytic activity of the Pt atom and dimer can be changed by modifying its chemical surroundings and single layers of Pt atoms have a different catalytic activity as compared to Pt clusters on a carbon surface.
Reactive molecular simulations of protonation of water clusters and depletion of acidity in H-ZSM-5 zeolite
Authors: Joshi Kaushik L. , Psofogiannakis George , van Duin Adri C. T. , Raman Sumathy
Published: July 2014

Protonation of water inside H-ZSM-5 zeolite using the ReaxFF reactive force field method.
Anion controlled structural and magnetic diversity in unusual mixed-bridged polynuclear NiII complexes with a versatile bis(2-methoxy phenol)diamine hexadentate ligand. An experimental and theoretical magneto-structural study
Authors: Botana Luis , Ruiz José , Mota Antonio J. , Rodríguez-Diéguez Antonio , Seco José M. , Oyarzabal Itziar , Colacio Enrique
Published: July 2014

Six new polynuclear NiII complexes with uncommon structures have been magneto-structural studied.
Hemi- and holo-directed lead(ii) complexes in a soft ligand environment
Authors: Imran Muhammad , Mix Andreas , Neumann Beate , Stammler Hans-Georg , Monkowius Uwe , Gründlinger Petra , Mitzel Norbert W.
Published: July 2014

Structures and stereochemical activity of the lone pairs at the lead ion were investigated by synthetic, spectroscopic and structural studies of ten lead(ii) complexes with heterocyclic soft ligands. The majority of the complexes exhibited a hemi-directed environment around the lead ions.
Half-sandwich scandium boryl complexes bearing a silylene-linked cyclopentadienyl-amido ligand
Authors: Wang Baoli , Nishiura Masayoshi , Cheng Jianhua , Hou Zhaomin
Published: July 2014

A boryl scandium complex supported by the silylene-linked cyclopentadienyl-amido ligand was synthesized for the first time.
The use of metabolomics in the study of metals in biological systems
Authors: Jones Oliver A. H. , Dias Daniel A. , Callahan Damien L. , Kouremenos Konstantinos A. , Beale David J. , Roessner Ute
Published: July 2014

Metabolomics and systems biology/toxicology can elucidate novel pathways and mechanistic networks of metals and metalloids in biological systems, as well as providing useful biomarkers of the metal status of organisms.
Functional α,ω-dienes via thiol-Michael chemistry: synthesis, oxidative protection, acyclic diene metathesis (ADMET) polymerization and radical thiol–ene modification
Authors: van Hensbergen Johannes A. , Gaines Taylor W. , Wagener Kenneth B. , Burford Robert P. , Lowe Andrew B.
Published: July 2014

The synthesis of the novel α,ω-diene 2-(undec-10-en-1-yl)tridec-12-en-1-yl acrylate is described.
Synthesis and characterization of polypyrrole/H-Beta zeolite nanocomposites
Authors: Yu Kai , Kumar Narendra , Roine Jorma , Pesonen Markus , Ivaska Ari
Published: July 2014

Transmission electron micrographs of (a) H-Beta-25, (b), (c) and (d) 1 ml PPy/H-Beta-25 composite.
Anisotropic wave propagation in nematic liquid crystals
Authors: Biscari Paolo , DiCarlo Antonio , Turzi Stefano S.
Published: July 2014

We show that elastic anisotropy and relaxation are at the origin of the main experimental features of nematoacoustics.
Ultra high-yield one-step synthesis of conductive and superhydrophobic three-dimensional mats of carbon nanofibers via full catalysis of unconstrained thin films
Authors: Shawat Efrat , Perelshtein Ilana , Westover Andrew , Pint Cary L. , Nessim Gilbert D.
Published: July 2014

We directly synthesized large conductive and superhydrophobic 3D mats of entangled carbon nanofibers (CNFs). The mechanism is based on thin film delamination and bi-directional catalytic CNF growth.
Fabrication of titanium phosphate@graphene oxide nanocomposite and its super performance on Eu3+ recycling
Authors: Li Chaoran , Huang Yang , Lin Zhang
Published: July 2014

Titanium phosphate@graphene oxide nanocomposites exhibit enhanced hydrophilicity, adsorption capacity and efficiency for Eu3+ enrichment.
Prion-induced and spontaneous formation of transmissible toxicity in PrP transgenic Drosophila
Authors: Thackray Alana M. , Di Ying , Zhang Chang , Wolf Hanna , Pradl Lydia , Vorberg Ina , Andréoletti Olivier , Bujdoso Raymond
Published: July 2014

Prion diseases are fatal transmissible neurodegenerative diseases of various mammalian species. Central to these conditions is the conversion of the normal host prion protein PrPC into the abnormal prion conformer PrPSc. Mature PrPC is attached to the plasma membrane by a glycosylphosphatidylinositol anchor, whereas during biosynthesis and metabolism cytosolic and secreted forms of the protein may arise. The role of topological PrPC variants in the mechanism of prion formation and prion-induced neurotoxicity during prion disease remains undefined. In the present study we investigated whether Drosophila transgenic for ovine PrP targeted to the plasma membrane, to the cytosol or for secretion, could produce transmissible toxicity following exposure to exogenous ovine prions. Although all three topological variants of PrP were efficiently expressed in Drosophila, cytosolic PrP was conformationally distinct and required denaturation before recognition by immunobiochemical methods. Adult Drosophila transgenic for pan neuronally expressed ovine PrP targeted to the plasma membrane, to the cytosol or for secretion exhibited a decreased locomotor activity after exposure at the larval stage to ovine prions. Proteinase K-resistant PrPSc was detected by protein misfolding cyclic amplification in prion-exposed Drosophila transgenic for membrane-targeted PrP. Significantly, head homogenate from all three variants of prion-exposed PrP transgenic Drosophila induced a decreased locomotor activity when transmitted to PrP recipient flies. Drosophila transgenic for PrP targeted for secretion exhibited a spontaneous locomotor defect in the absence of prion exposure that was transmissible in PrP transgenic flies. Our data are consistent with the formation of transmissible prions in PrP transgenic Drosophila.
Effects of metformin and other biguanides on oxidative phosphorylation in mitochondria
Authors: Bridges Hannah R. , Jones Andrew J. Y. , Pollak Michael N. , Hirst Judy
Published: July 2014

The biguanide metformin is widely prescribed for Type II diabetes and has anti-neoplastic activity in laboratory models. Despite evidence that inhibition of mitochondrial respiratory complex I by metformin is the primary cause of its cell-lineage-specific actions and therapeutic effects, the molecular interaction(s) between metformin and complex I remain uncharacterized. In the present paper, we describe the effects of five pharmacologically relevant biguanides on oxidative phosphorylation in mammalian mitochondria. We report that biguanides inhibit complex I by inhibiting ubiquinone reduction (but not competitively) and, independently, stimulate reactive oxygen species production by the complex I flavin. Biguanides also inhibit mitochondrial ATP synthase, and two of them inhibit only ATP hydrolysis, not synthesis. Thus we identify biguanides as a new class of complex I and ATP synthase inhibitor. By comparing biguanide effects on isolated complex I and cultured cells, we distinguish three anti-diabetic and potentially anti-neoplastic biguanides (metformin, buformin and phenformin) from two anti-malarial biguanides (cycloguanil and proguanil): the former are accumulated into mammalian mitochondria and affect oxidative phosphorylation, whereas the latter are excluded so act only on the parasite. Our mechanistic and pharmacokinetic insights are relevant to understanding and developing the role of biguanides in new and existing therapeutic applications, including cancer, diabetes and malaria.
A small molecule that induces reactive oxygen species via cellular glutathione depletion
Authors: Kawamura Tatsuro , Kondoh Yasumitsu , Muroi Makoto , Kawatani Makoto , Osada Hiroyuki
Published: July 2014

Induction of excessive levels of reactive oxygen species (ROS) by small-molecule compounds has been considered a potentially effective therapeutic strategy against cancer cells, which are often subjected to chronic oxidative stress. However, to elucidate the mechanisms of action of bioactive compounds is generally a time-consuming process. We have recently identified NPD926, a small molecule that induces rapid cell death in cancer cells. Using a combination of two comprehensive and complementary approaches, proteomic profiling and affinity purification, together with the subsequent biochemical assays, we have elucidated the mechanism of action underlying NPD926-induced cell death: conjugation with glutathione mediated by GST, depletion of cellular glutathione and subsequent ROS generation. NPD926 preferentially induced effects in KRAS-transformed fibroblast cells, compared with their untransformed counterparts. Furthermore, NPD926 sensitized cells to inhibitors of system xc−, a cystine-glutamate antiporter considered to be a potential therapeutic target in cancers including cancer stem cells. These data show the effectiveness of a newly identified ROS inducer, which targets glutathione metabolism, in cancer treatment.
Endothelial nitric oxide synthase is regulated by ERK phosphorylation at Ser602
Authors: Salerno John C. , Ghosh Dipak K. , Razdan Raj , Helms Katy A. , Brown Christopher C. , McMurry Jonathan L. , Rye Emily A. , Chrestensen Carol A.
Published: July 2014

eNOS (endothelial nitric oxide synthase) contains a MAPK (mitogen-activated protein kinase)-binding site associated with a major eNOS control element. Purified ERK (extracellular-signal-regulated kinase) phosphorylates eNOS with a stoichiometry of 2–3 phosphates per eNOS monomer. Phosphorylation decreases NO synthesis and cytochrome c reductase activity. Three sites of phosphorylation were detected by MS. All sites matched the SP and TP MAPK (mitogen-activated protein kinase) phosphorylation motif. Ser602 lies at the N-terminal edge of the 42-residue eNOS AI (autoinhibitory) element. The pentabasic MAPK-binding site lies at the opposite end of the AI, and other critical regulatory features are between them. Thr46 and Ser58 are located in a flexible region associated with the N terminus of the oxygenase domain. In contrast with PKC (protein kinase C), phosphorylation by ERK did not significantly interfere with CaM (calmodulin) binding as analysed by optical biosensing. Instead, ERK phosphorylation favours a state in which FMN and FAD are in close association and prevents conformational changes that expose reduced FMN to acceptors. The close associations between control sites in a few regions of the molecule suggest that control of signal generation is modulated by multiple inputs interacting directly on the surface of eNOS via overlapping binding domains and tightly grouped targets.
Face-Viewing Patterns in Young Children With Autism Spectrum Disorders: Speaking up for the Role of Language Comprehension
Authors: Åsberg Johnels Jakob , Gillberg Christopher , Falck-Ytter Terje , Miniscalco Carmela
Published: July 2014

Purpose

The aim was to examine whether viewing patterns toward the mouth, eyes, and nonmouth–noneyes areas differed between young children with autism spectrum disorder (ASD) and typically developing (TD) children when viewing a person speaking. The role of language comprehension in such viewing patterns was also examined.

Method

Eleven children with ASD (approximately 4.5 years old) and 29 TD toddlers (approximately 2.5 years old) participated. The groups were matched on language comprehension raw scores from the Reynell Developmental Language Scales III. All children viewed short films of a woman speaking while their eye movements were recorded with eye-tracking equipment.

Results

Children with ASD spent proportionally less time viewing the mouth and more time viewing the nonmouth–noneyes areas. Time viewing the eyes did not differ between groups. Increased mouth viewing was associated with lower language comprehension in the group with ASD.

Conclusion

Variability in language comprehension is an important factor to monitor when interpreting face-viewing patterns in young children with ASD, particularly with regard to mouth viewing. The results may help explain divergent findings in this field of research.
Assessing Pragmatic Language in Autism Spectrum Disorder: The Yale
in vivo
Pragmatic Protocol
Authors: Simmons Elizabeth Schoen , Paul Rhea , Volkmar Fred
Published: July 2014

Purpose

This study compared pragmatic language in youths (9–17 years) with autism spectrum disorder (ASD) and those with typical development (TD) on the Yale
in vivo
Pragmatic Protocol (Y
i
PP), a semistructured, dynamic conversational assessment.

Method

Participants (
n
= 118) were divided into groups based on age and diagnosis. Each completed the Y
i
PP, which included 4 pragmatic domains (discourse management, communicative functions, conversational repair, presupposition). The participant's response to each probe was scored correct or incorrect; incorrect scores elicited cues from the examiner, and level of cue required for a correction was also scored.

Results

The Y
i
PP showed high reliability and internal consistency, with moderate concurrent validity, sensitivity, and specificity. The group with ASD performed worse overall on Y
i
PP probes compared to their TD counterparts on both error (
d
= 0.96) and cue (
d
= 0.91) scores. Item analyses revealed greater gaps between older students with ASD and their TD peers than between the 2 younger groups.

Conclusions

These data suggest that a probe measure designed to assess pragmatic abilities in children with ASD within a conversational context has some validity for contributing to diagnostic classification and can identify specific areas of pragmatic vulnerabilities as part of a clinical assessment.

Supplemental Material

https://doi.org/10.23641/asha.6170480
Probabilistic load flow computation using Copula and Latin hypercube sampling
Authors: Cai Defu , Shi Dongyuan , Chen Jinfu
Published: July 2014

A probabilistic load flow (PLF) method using Copula and improved Latin hypercube sampling is proposed. The stochastic dependence between input random variables is considered. Copula theory is adopted to establish the probability distribution of correlated input random variables. Based on discrete data, an improved Latin hypercube sampling is proposed. The accuracy of probability distribution of correlated input random variables established by Copula theory is evaluated by adopting the power output of wind farms located at New Jersey. The performance of the proposed PLF method is investigated using IEEE 14‐bus and IEEE 118‐bus test systems.
Optimised adaptive power on‐demand routing protocol for mobile ad hoc wireless network
Authors: Bello Lawal , Bakalis Panos , Rapajic Predrag , Anang Kwashie A.
Published: July 2014

A technique is developed for ad hoc on‐demand routing protocol. The protocol is based on the conventional on‐demand ad hoc routing protocols with the addition of power model. The algorithm design and development is aimed to incorporate the transmitted power consumption function in such a manner that mobile nodes are able to evaluate their power status to decide if they are fit for packet forwarding and reception. This is illustrated through analytical approach supported by computer simulations over mobile ad hoc wireless network containing 80 mobile nodes. The results showed that power savings of 50% were achieved with no delay in the network and increased throughput performance by 60%, as compared to a network with conventional ad hoc on‐demand distance vector and dynamic source routing protocols.
Simulation analysis and experimentation study on sea clutter spectrum for high‐frequency hybrid sky‐surface wave propagation mode
Authors: Ya‐jun Li , Yin‐sheng Wei , Rong‐qing Xu , Chao Shang
Published: July 2014

This study simulated the broadening first‐order sea clutter spectrum and analysed the influence of ionosphere and bistatic angle on sea clutter spectrum for high‐frequency (HF) hybrid sky‐surface wave radar based on the mechanism of sea clutter broadening. Firstly, according to the propagation characteristics of HF waves in the ionosphere and the mechanism of the ionosphere contamination, a method of dynamic ionospheric phase contamination simulation is introduced. Secondly, the formula of the Bragg frequency of first‐order sea clutter is presented derived from the system configuration, and a simulation method of broadening sea clutter is given. The influence of bistatic angle and different ionosphere state on the first‐order sea clutter spectrum is further analysed. Finally, the results of theoretic analysis are examined with the experimental results based on the newly developed integrated HF sky‐surface wave radar experimental system, and the dominant factor of sea clutter broadening is studied. Simulation results show that the results of experiment consist with that of theoretic analysis, simulated broadening sea clutter can better describe the characteristics of measured sea clutter.
Analysis and classification of DNA‐binding sites in single‐stranded and double‐stranded DNA‐binding proteins using protein information
Authors: Wang Wei , Liu Juan , Xiong Yi , Zhu Lida , zhou Xionghui
Published: July 2014

Single‐stranded DNA‐binding proteins (SSBs) and double‐stranded DNA‐binding proteins (DSBs) play different roles in biological processes when they bind to single‐stranded DNA (ssDNA) or double‐stranded DNA (dsDNA). However, the underlying binding mechanisms of SSBs and DSBs have not yet been fully understood. Here, the authors firstly constructed two groups of ssDNA and dsDNA specific binding sites from two non‐redundant sets of SSBs and DSBs. They further analysed the relationship between the two classes of binding sites and a newly proposed set of features (residue charge distribution, secondary structure and spatial shape). To assess and utilise the predictive power of these features, they trained a classification model using support vector machine to make predictions about the ssDNA and the dsDNA binding sites. The author's analysis and prediction results indicated that the two classes of binding sites can be distinguishable by the three types of features, and the final classifier using all the features achieved satisfactory performance. In conclusion, the proposed features will deepen their understanding of the specificity of proteins which bind to ssDNA or dsDNA.
Improvement in the statistical operation of a Blumlein pulse forming line in bipolar pulse mode
Authors: Pushkarev A. I. , Isakova Y. I. , Khaylov I. P.
Published: July 2014

The paper presents the results of studies on shot-to-shot performance of a water Blumlein pulse forming line of 1–1.2 kJ of stored energy. The experiments were carried using the TEMP-4M pulsed ion beam accelerator during its operation in both unipolar pulse mode (150 ns, 250–300 kV) and bipolar-pulse mode with the first negative (300–600 ns, 100–150 kV) followed by a second positive (120 ns, 250–300 kV) pulse. The analysis was carried out for two cases when the Blumlein was terminated with a resistive load and with a self-magnetically insulated ion diode. It was found that in bipolar pulse mode the shot-to-shot variation in breakdown voltage of a preliminary spark gap is small, the standard deviation (1σ) does not exceed 2%. At the same time, the shot-to-shot variation in the breakdown voltage of the main spark gap in both bipolar-pulse and unipolar pulse mode is 3–4 times higher than that for the preliminary spark gap. To improve the statistical performance of the main spark gap we changed the regime of its operation from a self-triggered mode to an externally triggered mode. In the new arrangement the first voltage pulse at the output of Blumlein was used to trigger the main spark gap. The new trigatron-type regime of the main spark gap operation showed a good stability of breakdown voltage and thus allowed to stabilize the duration of the first pulse. The standard deviation of the breakdown voltage and duration of the first pulse did not exceed 2% for a set of 50 pulses. The externally triggered mode of the main gap operation also allowed for a decrease in the charging voltage of the Blumlein to a 0.9–0.95 of self-breakdown voltage of the main spark gap while the energy stored in Marx generator was decreased from 4 kJ to 2.5 kJ. At the same time the energy stored in Blumlein remained the same.
Phase contrast portal imaging using synchrotron radiation
Authors: Umetani K. , Kondoh T.
Published: July 2014

Microbeam radiation therapy is an experimental form of radiation treatment with great potential to improve the treatment of many types of cancer. We applied a synchrotron radiation phase contrast technique to portal imaging to improve targeting accuracy for microbeam radiation therapy in experiments using small animals. An X-ray imaging detector was installed 6.0 m downstream from an object to produce a high-contrast edge enhancement effect in propagation-based phase contrast imaging. Images of a mouse head sample were obtained using therapeutic white synchrotron radiation with a mean beam energy of 130 keV. Compared to conventional portal images, remarkably clear images of bones surrounding the cerebrum were acquired in an air environment for positioning brain lesions with respect to the skull structure without confusion with overlapping surface structures.
Method for characterizing the contact resistance of metal-vanadium dioxide thin film interfaces
Authors: Percy R. , Kittiwatanakul S. , Lu J. , Stan M. , Wolf S. , Weikle R. M.
Published: July 2014

The standard method for determining the contact resistance of planar metal-semiconductor interfaces can underestimate the true contact resistance under normal operating conditions, as it relies on the resistivity of the semiconductor material remaining constant during measurement. However, the strong temperature dependence of the resistivity of VO2 requires a modified approach that maintains a constant power density dissipated within the film to account for Joule heating. We develop a method for measuring contact resistance in semiconductors with a high thermal coefficient of resistivity, demonstrate this method with an example, and compare the results with the standard technique.
Influence of Au nanoparticles on the photoluminescent and electrical properties of Bi3.6Eu0.4Ti3O12 ferroelectric thin films
Authors: Su Li , Qin Ni , Xie Wei , Fu Jianhui , Bao Dinghua
Published: July 2014

Au-doped Bi3.6Eu0.4Ti3O12 (BET) thin films were prepared on fused silica and Pt/Ti/SiO2/Si substrates by a chemical solution deposition method. The existence of Au nanoparticles (NPs) has been confirmed by X-ray diffraction, X-ray photoelectron spectroscopy, and transmission electron microscope analysis. Enhanced photoluminescence (PL) of Eu3+ ions was obtained in a wide range of Au doping level. Role of the Au NPs in the PL enhancement was investigated by means of optical absorption, excitation, and emission spectra, as well as decay lifetime measurements. The results indicated that the intra-4f transition of Eu3+ ions can be intensively activated by the coupling of the charge transfer band of BET with the 5D0 state of Eu3+ ions. The influence of Au NPs on the PL properties of Eu3+ ions in the present thin films was attributed to the band bending at Au/BET interface and the localized surface plasma resonance absorption of Au NPs in the visible light region. The dielectric and ferroelectric properties of Au-doped BET thin films were investigated as well.
Investigation into the dynamics of laser-cut foil X-pinches and their potential use for high repetition rate operation
Authors: Collins G. W. , Valdivia M. P. , Zick T. O. , Kim J. , Haas D. M. , Forsman A. C. , Stephens R. B. , Beg F. N.
Published: July 2014

We report on results from experiments using laser-cut X shaped foils (or foil X-pinches) driven by the 250 kA, 150 ns rise-time GenASIS Linear Transformer Driver. Optical probing of the laser-cut foil X-pinches shows considerable dynamic and qualitative similarity with the more traditional wire X-pinches. Results demonstrate excellent quality X-ray emission flux, timing, and source size. The foil X-pinches offer advantages such as improved, reproducible cross-point symmetry, and the opportunity for rep-rated operation, which is not possible with conventional X-pinches using wires.
Diffusion of oxygen in amorphous Al2O3, Ta2O5, and Nb2O5
Authors: Nakamura R. , Toda T. , Tsukui S. , Tane M. , Ishimaru M. , Suzuki T. , Nakajima H.
Published: July 2014

The self-diffusivity of oxygen in amorphous Al2O3 (a-Al2O3), a-Ta2O5, and a-Nb2O5 was investigated along with structural analysis in terms of pair distribution function (PDF). The low activation energy, ∼1.2 eV, for diffusion in the oxides suggests a single atomic jump of oxygen ions mediated via vacancy-like defects. However, the pre-exponential factor for a-Ta2O5 and a-Nb2O5 with lower bond energy was two orders of magnitude larger than that for a-Al2O3 with higher bond energy. PDF analyses revealed that the short-range configuration in a-Ta2O5 and a-Nb2O5 was more broadly distributed than that in a-Al2O3. Due to the larger variety of atomic configurations of a-Ta2O5 and a-Nb2O5, these oxides have a higher activation entropy for diffusion than a-Al2O3. The entropy term for diffusion associated with short-range structures was shown to be a dominant factor for diffusion in amorphous oxides.
Sub-100 ps laser-driven dynamic compression of solid deuterium with a ∼40 μJ laser pulse
Authors: Armstrong Michael R. , Crowhurst Jonathan C. , Bastea Sorin , Zaug Joseph M. , Goncharov Alexander F.
Published: July 2014

We dynamically compress solid deuterium over <100 ps from initial pressures of 22 GPa to 55 GPa, to final pressures as high as 71 GPa, with <40 μJ of pulse energy. At 25 GPa initial pressure, we measure compression wave speeds consistent with quasi-isentropic compression and a 24% increase in density. The laser drive energy per unit density change is 109 times smaller than it is for recent longer (∼30 ns) time scale compression experiments. This suggests that, for a given final density, dynamic compression of hydrogen might be achieved using orders of magnitude lower laser energy than currently used.
Non contact probing of interfacial stiffnesses between two plates by zero-group velocity Lamb modes
Authors: Mezil Sylvain , Laurent Jérôme , Royer Daniel , Prada Claire
Published: July 2014

A non contact technique using zero-group velocity (ZGV) Lamb modes is developed to probe the bonding between two solid plates coupled by a thin layer. The layer thickness is assumed to be negligible compared with the plate thickness and the acoustic wavelength. The coupling layer is modeled by a normal and a tangential spring to take into account the normal and shear interfacial stresses. Theoretical ZGV frequencies are determined for a symmetrical bi-layer structure and the effect of the interfacial stiffnesses on the cut-off and ZGV frequencies are evaluated. Experiments are conducted with two glass plates bonded by a drop of water, oil, or salol, leading to a few micrometer thick layer. An evaluation of normal and shear stiffnesses is obtained using ZGV resonances locally excited and detected with laser ultrasonic techniques.
Boron phosphide under pressure: In situ study by Raman scattering and X-ray diffraction
Authors: Solozhenko Vladimir L. , Kurakevych Oleksandr O. , Le Godec Yann , Kurnosov Aleksandr V. , Oganov Artem R.
Published: July 2014

Cubic boron phosphide, BP, has been studied in situ by X-ray diffraction and Raman scattering up to 55 GPa at 300 K in a diamond anvil cell. The bulk modulus of B0 = 174(2) GPa has been established, which is in excellent agreement with our ab initio calculations. The data on Raman shift as a function of pressure, combined with equation-of-state (EOS) data, allowed us to estimate the Grüneisen parameters of the TO and LO modes of zinc-blende structure, γGTO = 1.26 and γGLO = 1.13, just like in the case of other AIIIBV diamond-like phases, for which γGTO > γGLO ≅ 1. We also established that the pressure dependence of the effective electro-optical constant α is responsible for a strong change in relative intensities of the TO and LO modes from ITO/ILO ∼ 0.25 at 0.1 MPa to ITO/ILO ∼ 2.5 at 45 GPa, for which we also find excellent agreement between experiment and theory.
Effects of the Cu off-stoichiometry on transport properties of wide gap p-type semiconductor, layered oxysulfide LaCuSO
Authors: Goto Yosuke , Tanaki Mai , Okusa Yuki , Shibuya Taizo , Yasuoka Kenji , Matoba Masanori , Kamihara Yoichi
Published: July 2014

Layered oxysulfide LaCu1−xSO (x = 0–0.03) was prepared to elucidate the effect of Cu off-stoichiometry on their electrical and thermal transport properties. Electrical resistivity drastically decreases down from ∼105 Ω·cm to ∼10−1 Ω·cm as a result of Cu deficiency (x = 0.01) at 300 K. Thermal conductivity of the samples at 300 K, which is dominated by lattice components, is estimated to be 2.3(3) Wm−1K−1. Stoichiometric LaCuSO has an optical band gap of 3.1 eV, while broad optical absorption at photon energies of approximately 2.1 eV was observed for Cu-deficient samples. Density functional theory calculation suggests that these broad absorption structures probably originate from the in-gap states generated by the sulfur vacancies created to compensate the charge imbalance due to Cu off-stoichiometry. These results clearly demonstrate that Cu deficiency plays a crucial role in determining the electrical transport properties of Cu-based p-type transparent semiconductors.
Temperature dependent magnetization reversal of exchange biased magnetic vortices in IrMn/Fe microcaps
Authors: Thomas S. , Nissen D. , Albrecht M.
Published: July 2014

We have investigated the magnetization reversal of vortex structures in Fe as well as in IrMn/Fe magnetic caps at elevated temperatures up to 450 K. The caps were formed by film deposition onto dense arrays of self-assembled silica particles of 900 nm diameter. In the investigated temperature range, the magnetization reversal in Fe caps evolves via nucleation and annihilation of magnetic vortices. However, in exchange coupled IrMn/Fe caps, the magnetic vortex at zero magnetic field vanishes as the temperature approaches the blocking temperature of IrMn accompanied by an increase in coercivity. Further increase in temperature, approaching the Néel temperature of IrMn, results in a reduction of coercivity as well as remanence indicating the re-stabilization of a vortex state.
Piezoelectric properties of graphene oxide: A first-principles computational study
Authors: Chang Zhenyue , Yan Wenyi , Shang Jin , Liu Jefferson Zhe
Published: July 2014

Some highly ordered compounds of graphene oxide (GO), e.g., the so-called clamped and unzipped GO, are shown to have piezoelectric responses via first-principles density functional calculations. By applying an electric field perpendicular to the GO basal plane, the largest value of in-plane strain and strain piezoelectric coefficient, d31 are found to be 0.12% and 0.24 pm/V, respectively, which are comparable with those of some advanced piezoelectric materials. An in-depth molecular structural analysis reveals that the deformation of the oxygen doping regions in the clamped GO dominates its overall strain output, whereas the deformation of the regions without oxygen dopant in the unzipped GO determines its overall piezoelectric strain. This understanding explains the observed dependence of d31 on oxygen doping rate, i.e., higher oxygen concentration giving rise to a larger d31 in the clamped GO whereas leading to a reduced d31 in the unzipped GO. As the thinnest two-dimensional piezoelectric materials, GO has a great potential for a wide range of micro/nano-electromechanical system (MEMS/NEMS) actuators and sensors.
Focal depth measurement of scanning helium ion microscope
Authors: Guo Hongxuan , Itoh Hiroshi , Wang Chunmei , Zhang Han , Fujita Daisuke
Published: July 2014

When facing the challenges of critical dimension measurement of complicated nanostructures, such as of the three dimension integrated circuit, characterization of the focal depth of microscopes is important. In this Letter, we developed a method for characterizing the focal depth of a scanning helium ion microscope (HIM) by using an atomic force microscope tip characterizer (ATC). The ATC was tilted in a sample chamber at an angle to the scanning plan. Secondary electron images (SEIs) were obtained at different positions of the ATC. The edge resolution of the SEIs shows the nominal diameters of the helium ion beam at different focal levels. With this method, the nominal shapes of the helium ion beams were obtained with different apertures. Our results show that a small aperture is necessary to get a high spatial resolution and high depth of field images with HIM. This work provides a method for characterizing and improving the performance of HIM.
Perfect absorption in ultrathin anisotropic ε-near-zero metamaterials
Authors: Zhong Shuomin , Ma Yungui , He Sailing
Published: July 2014

Conventionally, perfect absorption by an ultrathin material usually requires a high material loss. In this paper, this common understanding is challenged. Our analytical solution shows that an anisotropic ε-near-zero thin metamaterial (MM) backed by a metallic substrate can perfectly absorb an incident plane wave at a specific angle while the MM can be arbitrarily thin and arbitrarily low-loss. The counterintuitive phenomenon is due to coherent cancelling. As a proof, we demonstrate a microwave absorber working at 5.35 GHz using low-loss meander-line MMs with a thickness of only λ/56. An absorption peak of 95% at a 60° incidence angle is obtained experimentally, which verifies the analytical results well.
Kinetic model for electric-field induced point defect redistribution near semiconductor surfaces
Authors: Gorai Prashun , Seebauer Edmund G.
Published: July 2014

The spatial distribution of point defects near semiconductor surfaces affects the efficiency of devices. Near-surface band bending generates electric fields that influence the spatial redistribution of charged mobile defects that exchange infrequently with the lattice, as recently demonstrated for pile-up of isotopic oxygen near rutile TiO2 (110). The present work derives a mathematical model to describe such redistribution and establishes its temporal dependence on defect injection rate and band bending. The model shows that band bending of only a few meV induces significant redistribution, and that the direction of the electric field governs formation of either a valley or a pile-up.
Controlled epitaxial graphene growth within removable amorphous carbon corrals
Authors: Palmer James , Kunc Jan , Hu Yike , Hankinson John , Guo Zelei , Berger Claire , de Heer Walt A.
Published: July 2014

We address the question of control of the silicon carbide (SiC) steps and terraces under epitaxial graphene on SiC and demonstrate amorphous carbon (aC) corrals as an ideal method to pin SiC surface steps. aC is compatible with graphene growth, structurally stable at high temperatures, and can be removed after graphene growth. For this, aC is first evaporated and patterned on SiC, then annealed in the graphene growth furnace. There at temperatures above 1200 °C, mobile SiC steps accumulate at the aC corral that provide effective step flow barriers. Aligned step free regions are thereby formed for subsequent graphene growth at temperatures above 1330 °C. Atomic force microscopy imaging supports the formation of step-free terraces on SiC with the step morphology aligned to the aC corrals. Raman spectroscopy indicates the presence of good graphene sheets on the step-free terraces.
A molecular phylogenetic framework for cocksfoot (Dactylis glomerata L.) improvement
Authors: Stewart Alan V. , Ellison Nicholas W.
Published: July 2014

The recently completed molecular phylogenetic analysis of Dactylis germplasm has provided a clear evolutionary history of the diploid Dactylis from which modern tetraploid germplasm and cultivars have evolved. This framework will allow us to use fully a wider range of both diploid and tetraploid germplasm for a more systematic improvement of cocksfoot. Germplasm of many diploid and tetraploid forms is under serious threat from habitat degradation and climate change, and many forms are currently poorly represented in genebanks. It is critical that a wide range of these forms is collected for storage and conservation. It is also critical that core collections are developed and maintained, using molecular phylogenetic and genetic diversity information as the basic framework.
In order to apply molecular resources in an effective and balanced manner, pragmatic field breeding programs need to be continued in all major regions. This is a major concern for cocksfoot, as it is a species with limited international breeding investment. Viable, large-scale, cocksfoot breeding programs must be maintained internationally to allow adequate cultivar development, ongoing germplasm collection, introgression from wild germplasm and application of molecular resources.