bluuebunny/crossref_metadata_2025 huggingface dataset:
Low temperature structural anomalies arising from competing exchange interactions in pyrochlore Nd2Ru2O7 probed by XRD and EXAFS
Authors: Chen Shi-Wei , Fu Shao-Wei , Pao Chih-Wen , Lee Jenn-Min , Chen Shin-An , Haw Shu-Chih , Lee Jyh-Fu , Liu Chun-Hsia , Chang Chung-Kai , Chuang Yu-Chun , Sheu Hwo-Shuenn , Lu Kueih-Tzu , Ku Szu-Tu , Chang Lieh-Jeng , Chen Jin-Ming
Published: August 2015

Quantitative structural parameters of pyrochlore Nd2Ru2O7, with temperature dependence, have been derived upon fitting XRD and EXAFS data.
Optimization of the GAFF force field to describe liquid crystal molecules: the path to a dramatic improvement in transition temperature predictions
Authors: Boyd Nicola Jane , Wilson Mark R.
Published: August 2015

Systematic optimization of the General Amber Force Field (GAFF) for mesogenic fragments leads to a dramatic improvement in the modelling of liquid crystal clearing points.
Solution concentration controlled self-assembling structure with host–guest recognition at the liquid–solid interface
Authors: Zhang Siqi , Zhang Junyong , Deng Ke , Xie Jingli , Duan Wubiao , Zeng Qingdao
Published: August 2015

This work describes structural variety in the co-assembly of H3TTCA/COR controlled by the solution concentration of COR at the 1-heptanoic acid/HOPG interface.
Ru/TiO2-catalysed hydrogenation of xylose: the role of the crystal structure of the support
Authors: Hernandez-Mejia Carlos , Gnanakumar Edwin S. , Olivos-Suarez Alma , Gascon Jorge , Greer Heather F. , Zhou Wuzong , Rothenberg Gadi , Raveendran Shiju N.
Published: August 2015

Lattice matching holds the secret to the Ru-catalysed hydrogenation of xylose to xylitol, a key reaction in practical biomass conversion.
Synthesis and post-synthetic modification of amine-, alkyne-, azide- and nitro-functionalized metal–organic frameworks based on DUT-5
Authors: Gotthardt Meike A. , Grosjean Sylvain , Brunner Tobias S. , Kotzel Johannes , Gänzler Andreas M. , Wolf Silke , Bräse Stefan , Kleist Wolfgang
Published: August 2015

Various functionalized 4,4′-biphenlydicarboxylic acids were prepared and applied in the synthesis of single- and mixed-linker DUT-5 frameworks. The NH2-containing materials were used for post-synthetic modification.
Synthesis and behavior of novel sulfonated water-soluble N-heterocyclic carbene (η4-diene) platinum(0) complexes
Authors: Ruiz-Varilla Andrea M. , Baquero Edwin A. , Silbestri Gustavo F. , Gonzalez-Arellano Camino , de Jesús Ernesto , Flores Juan C.
Published: August 2015

Novel water-soluble (NHC)Pt(0)(1,6-diene) complexes are presented, along with details of their preparation, stability, and use as catalysts for the hydrosilylation of acetylenes in water.
Morphology evolution and gas adsorption of porous metal–organic framework microcrystals
Authors: Qi Zhao-Peng , Yang Ji-Min , Kang Yan-Shang , Sun Wei-Yin
Published: August 2015

The morphology and size of MOF microcrystals are tuned by volume ratios of DMF and H2O, and their sorption properties are morphology-dependent.
Oligomeric-Schiff bases as negative electrodes for sodium ion batteries: unveiling the nature of their active redox centers
Authors: López-Herraiz María , Castillo-Martínez Elizabeth , Carretero-González Javier , Carrasco Javier , Rojo Teófilo , Armand Michel
Published: August 2015

Novel hybrids between carboxylate and aromatic Schiff base show reversible sodium insertion below 1.2 V vs. Na+. Identifying the redox active units leads to sustainable and low cost anode materials beyond 250 mA h g−1.
Transformation of atrazine, bisphenol A and chlorendic acid by electrochemically produced oxidants using a lead dioxide electrode
Authors: Hermes N. , Knupp G.
Published: August 2015

A novel microscale ozonation apparatus based on electrocatalytical decomposition of water proved to be effective for treatment of contaminated water.
Reductive amination of furfural to furfurylamine using aqueous ammonia solution and molecular hydrogen: an environmentally friendly approach
Authors: Chatterjee Maya , Ishizaka Takayuki , Kawanami Hajime
Published: August 2015

An efficient process was developed to obtain furfurylamine with very high yield (∼92%) through the reductive amination of furfural under a mild reaction condition.
Epitaxial 1D electron transport layers for high-performance perovskite solar cells
Authors: Han Gill Sang , Chung Hyun Suk , Kim Dong Hoe , Kim Byeong Jo , Lee Jin-Wook , Park Nam-Gyu , Cho In Sun , Lee Jung-Kun , Lee Sangwook , Jung Hyun Suk
Published: August 2015

1-D core–shell structure, composed of SnO2nanowire and epitaxial TiO2nanoshell, is a promising electron transport layer for perovskite solar cells.
Two-dimensional nanosheets of MoS2: a promising material with high dielectric properties and microwave absorption performance
Authors: Ning Ming-Qiang , Lu Ming-Ming , Li Jing-Bo , Chen Zhuo , Dou Yan-Kun , Wang Cheng-Zhi , Rehman Fida , Cao Mao-Sheng , Jin Hai-Bo
Published: August 2015

MoS2 nanosheets (MoS2-NS) exhibit a minimum reflection loss of −38.42 dB and a wide bandwidth with effective attenuation (<−10 dB) up to 4.1 GHz at a thickness of 2.4 mm.
A dual optical and nuclear imaging reagent for peptide labelling via disulfide bridging
Authors: Fletcher Sally A. , Sin Pak Kwan Brian , Nobles Muriel , Årstad Erik , Tinker Andrew , Baker James R.
Published: August 2015

We report a concise approach to a multimodal imaging reagent for peptide labelling via disulfide bridging. The reagent is constructed using a one pot, three component, [3 + 2] cycloaddition of a fluorescent azide with a dithiomaleimide-alkyne, with concomitant incorporation of 125I.
Synthesis and applications of secondary amine derivatives of (+)-dehydroabietylamine in chiral molecular recognition
Authors: Laaksonen Tiina , Heikkinen Sami , Wähälä Kristiina
Published: August 2015

(+)-Dehydroabietylamine (1a), the novel derivatives (2a–6a) and their NTf2 salts (1b–6b) were tested as chiral NMR solvating agents for the resolution of enantiomers of Mosher's acid and other carboxylic acids, and their n-Bu4N salts.
Metallopolymers for energy production, storage and conservation
Authors: Xiang Jing , Ho Cheuk-Lam , Wong Wai-Yeung
Published: August 2015

In this review, we explore the recent advances of using metallopolymers in organic solar cells, white organic light-emitting diodes and lithium-ion batteries. The structure–property relationship of these polymers and their device performances are discussed.
Adsorption of quinoline from liquid hydrocarbons on graphite oxide and activated carbons
Authors: Feng Xiao , Ma Xiaoliang , Li Na , Shang Chao , Yang Xiaoming , Chen Xiao Dong
Published: August 2015

Graphite oxide might be a promising adsorbent for adsorption denitrogenation due to its significant amount of oxygen functional groups.
Evaluation of the efficiency of brackish desalination ion exchange membranes using electrodialysis process
Authors: Venugopal Krishnaveni , Dharmalingam Sangeetha
Published: August 2015

Polysulfone (PSu) was functionalized and modified using resin and fiber reinforcements and then the prepared IEMs were analyzed using the fabricated BPMED unit.
Unique norbornene based triazole molecule for selective Fe(ii) sensing
Authors: Bhattacharya Sourav , Shunmugam Raja
Published: August 2015

A triazole functionalized norbornene monomer (NFTZ) and its corresponding homopolymer (NFTZH) are synthesized for selective Fe(ii) sensing.
Fluorescence sensing and intracellular imaging of Al3+ions by using naphthalene based sulfonamide chemosensor: structure, computation and biological studies
Authors: Mondal Sudipa , Bhanja Anup Kumar , Ojha Durbadal , Mondal Tapan Kumar , Chattopadhyay Debprasad , Sinha Chittaranjan
Published: August 2015

Naphthyl appended sulfonamide Schiff base (HL), an antimicrobial nontoxic agent, serves as a fluorogenic sensor to Al3+, LOD 33.2 nM and is used for living cell imaging.
Chemical fractionation of a terrestrial humic acid upon sorption on alumina by high resolution mass spectrometry
Authors: Galindo Catherine , Del Nero Mirella
Published: August 2015

Using mass spectrometry provided molecular-level insights into the chemical fractionation, and identity of adsorbed compounds, for a terrestrial humic acid rich in condensed aromatics, in alumina-solution systems.
SERS-active silver nanoparticle trimers for sub-attomolar detection of alpha fetoprotein
Authors: Wu Xiaoling , Fu Pan , Ma Wei , Xu Liguang , Kuang Hua , Xu Chuanlai
Published: August 2015

SERS-active silver nanoparticle trimers were assembled in this study for the first time, through the aptamer of a cancer biomarker, alpha fetoprotein (AFP).
Validated stability-indicating RP-LC method for the determination of pemirolast potassium investigation of kinetic behavior
Authors: El-Fatah Weshahy Soheir Abd , Yaaqob Maissa Salem , Morcos Marianne Nebsen , Hassan Dina Wahba , Youssef Nadia Fayek
Published: August 2015

The stability of the anti-asthmatic drug pemirolast potassium was investigated under different stress conditions, including hydrolysis (acid and alkali), heat, light and oxidation as recommended by the ICH guidelines.
Electronic structure and ultrafast charge transfer dynamics of phosphorous doped graphene layers on a copper substrate: a combined spectroscopic study
Authors: Larrude Dunieskys Gonzalez , Garcia-Basabe Yunier , Freire Junior Fernando Lázaro , Rocco Maria Luiza M.
Published: August 2015

Spectroscopy characterization on a phosphorous doped graphene layer suggests p-type doping governed by an electron transfer mechanism with a cupper substrate.
Facile synthesis of submillimeter sized graphene oxide by a novel method
Authors: Xu Tao , Meng Qinghan , Shen Tianze , Cao Bing
Published: August 2015

The lateral size of single layer GO that was synthesized by an electrochemically assisted improved Hummers method reached 300 μm.
Low temperature sputtered TiO2 nano sheaths on electrospun PES fibers as high porosity photoactive material
Authors: Alberti A. , Bongiorno C. , Pellegrino G. , Sanzaro S. , Smecca E. , Condorelli G. G. , Giuffrida A. E. , Cicala G. , Latteri A. , Ognibene G. , Cassano A. , Figoli A. , Spinella C. , La Magna A.
Published: August 2015

Low temperature approach based on combining electrospinning and reactive sputtering processes to realise a porous mesh of PES fibers wrapped by TiO2 nano-sheaths, active under UV illumination.
Modelling the interaction of graphene oxide using an atomistic-continuum model
Authors: Dyer Tom , Thamwattana Ngamta , Jalili Rouhollah
Published: August 2015

The interaction between layers of graphene oxide is mathematically modelled and optimal interlayer distances are found and supported by MD simulation.
Facile synthesis of oleylamine-capped silver nanowires and their application in transparent conductive electrodes
Authors: Zhu Jun , Xu Xiufang , Liu Jinglei , Zheng Yiqun , Hou Shifeng
Published: August 2015

Silver nanowires capped with oleylamine molecules have been prepared in high purity for the first time.
Interaction between dislocation mechanics on diffusion induced stress and electrochemical reaction in a spherical lithium ion battery electrode
Authors: Liu Zhijun , Zhou Jianqiu , Chen Bingbing , Zhu Jianwei
Published: August 2015

The effect of coupling dislocation induced stress with electrochemical reaction in a spherical battery electrode is investigated.
Preparation and enhanced catalytic activity of amphiphilic rambutan-like micro-reactors
Authors: Li Dongzhi , Zhao Bin , Long Yue , Yang Guoqiang , Tung Chen-Ho , Song Kai
Published: August 2015

The catalytic activity of amphiphilic rambutan-like micro-reactors in biphasic environments is shown.
Effect of grafted amine groups on in-plane tensile properties and high temperature structural stability of borophene nanoribbons
Authors: Yuan Jianhui , Zhang L. W. , Liew K. M.
Published: August 2015

The effects of grafted amine groups on in-plane tensile properties and structural stability of armchair and zigzag borophene nanoribbons (ABNRs and ZBNRs) are investigated by using molecular dynamics.
Greener saponin induced morphologically controlled various polymorphs of nanostructured iron oxide materials for biosensor applications
Authors: Sundar Sasikala , Piraman Shakkthivel
Published: August 2015

Biological synthesis of three different polymorphs of iron oxide nanostructures in one-pot reaction through greener saponin have been fabricated for biomolecules determination.
Switchable 3D liquid crystal grating generated by periodic photo-alignment on both substrates
Authors: Nys I. , Beeckman J. , Neyts K.
Published: August 2015

A planar liquid crystal (LC) cell is developed in which two photo-alignment layers have been illuminated with respectively a horizontal and a vertical diffraction pattern of interfering left- and right-handed circularly polarized light.
Anti-aggregation and intra-type Förster resonance energy transfer in bulky indoline sensitizers for dye-sensitized solar cells: a combined DFT/TDDFT and molecular dynamics study
Authors: Ding Wei-Lu , Li Quan-Song , Li Ze-Sheng
Published: August 2015

We have performed a theoretical investigation using a combination of DFT/TDDFT and molecular dynamics simulations to explain the relationship between bulky donor groups and higher efficiencies for a recent indoline sensitizer YA422 derived from its counterparts IQ4 and YA421.
Ball milling as an effective route for the preparation of doped bornite: synthesis, stability and thermoelectric properties
Authors: Guélou G. , Powell A. V. , Vaqueiro P.
Published: August 2015

Ball milling has been exploited for the preparation of Cu5Fe1−xMnxS4. These materials, which are p-type semiconductors, exhibit a figure of merit greater than 0.5 at moderate temperatures.
AAC Supports for Individuals With Rett Syndrome Across the Lifespan
Authors: Grether Sandra M.
Published: August 2015

Individuals with Rett syndrome (RS) present with a complex profile. They benefit from a multidisciplinary approach for diagnosis, treatment, and follow-up. In our clinic, the Communication Matrix©(Rowland, 1990/1996/2004) is used to collect data about the communication skills and modalities used by those with RS across the lifespan. Preliminary analysis of this data supports the expected changes in communication behaviors as the individual with RS ages and motor deficits have a greater impact.
Robust H2 /H∞ control for periodic stochastic difference systems with mutiplicative noise
Authors: Li Gang , Zhang Weihai , Chen Ming
Published: August 2015

The aim of this study is to investigate the discrete‐time periodic stochastic mixed H2 /H∞ control problem with state and external disturbance dependent noises. Under the assumption of 𝒦N ‐exact observability, the authors present a sufficient condition for the existence of mixed H2 /H∞ control for stochastic periodic difference systems, which transforms the H2 /H∞ controller design into solving four coupled matrix‐valued equations.
Cooperative optimisation with inseparable cost functions
Authors: Li Tai‐Fang , Lin Hai , Zhao Jun
Published: August 2015

Cooperative optimisation problems over multi‐agent systems have attracted a lot of attention. Most of existing results have been developed for the case when a cost function is given as a summation of local utilities. Instead, this study focuses on a more general case when the cost function is not given as a summation form or cannot be readily changed into a summation form. The authors call this case as the cooperative optimisation with inseparable cost functions. The authors’ basic idea is to decompose the inseparable cost function into local utilities based on geometric theory. Each of the decomposed agent optimisation problems only contains its own variable and constraints, and a gradient projection algorithm is proposed to solve the obtained distributed optimisation problem. It is further shown that the proposed algorithm converges and its solution coincides with the globally optimal solution under certain conditions, such as convexity of the cost function. Finally, two examples are given to illustrate the method.
Decentralised coordinated control of microgrid based on multi‐agent system
Authors: Dou Chunxia , Lv Mengfei , Zhao Tianyu , Ji Yeping , Li Heng
Published: August 2015

In this study, a two‐hierarchical decentralised coordinated control scheme based on the multi‐agent system (MAS) is proposed to improve the security and the stability of the microgrid. The coordinated switching control strategies are constructed in upper level agent to ensure the microgrid security. The making process of the coordinated switching control strategies is regarded as searching the optimal switching operation mode by means of designing constraint violation function and colour Petri‐net, so that the operation mode of the microgrid can be switched during larger power unbalance. The decentralised continuous control is designed by integrating the outer loop droop controller with the inner loop prescribed performance controller in the lower level unit agents to guarantee its unit system stability. Finally, the simulation results demonstrate the effectiveness of the decentralised coordination control based on MAS.
Quantum-mechanical approach to predissociation of water dimers in the vibrational adiabatic representation: Importance of channel interactions
Authors: Mineo H. , Niu Y. L. , Kuo J. L. , Lin S. H. , Fujimura Y.
Published: August 2015

The results of application of the quantum-mechanical adiabatic theory to vibrational predissociation (VPD) of water dimers, (H2O)2 and (D2O)2, are presented. We consider the VPD processes including the totally symmetric OH mode of the dimer and the bending mode of the fragment. The VPD in the adiabatic representation is induced by breakdown of the vibrational adiabatic approximation, and two types of nonadiabatic coupling matrix elements are involved: one provides the VPD induced by the low-frequency dissociation mode and the other provides the VPD through channel interactions induced by the low-frequency modes. The VPD rate constants were calculated using the Fermi golden rule expression. A closed form for the nonadiabatic transition matrix element between the discrete and continuum states was derived in the Morse potential model. All of the parameters used were obtained from the potential surfaces of the water dimers, which were calculated by the density functional theory procedures. The VPD rate constants for the two processes were calculated in the non-Condon scheme beyond the so-called Condon approximation. The channel interactions in and between the initial and final states were taken into account, and those are found to increase the VPD rates by 3(1) orders of magnitude for the VPD processes in (H2O)2 ((D2O)2). The fraction of the bending-excited donor fragments is larger than that of the bending-excited acceptor fragments. The results obtained by quantum-mechanical approach are compared with both experimental and quasi-classical trajectory calculation results.
Microscopic theory of cooperative spin crossover: Interaction of molecular modes with phonons
Authors: Palii Andrew , Ostrovsky Serghei , Reu Oleg , Tsukerblat Boris , Decurtins Silvio , Liu Shi-Xia , Klokishner Sophia
Published: August 2015

In this article, we present a new microscopic theoretical approach to the description of spin crossover in molecular crystals. The spin crossover crystals under consideration are composed of molecular fragments formed by the spin-crossover metal ion and its nearest ligand surrounding and exhibiting well defined localized (molecular) vibrations. As distinguished from the previous models of this phenomenon, the developed approach takes into account the interaction of spin-crossover ions not only with the phonons but also a strong coupling of the electronic shells with molecular modes. This leads to an effective coupling of the local modes with phonons which is shown to be responsible for the cooperative spin transition accompanied by the structural reorganization. The transition is characterized by the two order parameters representing the mean values of the products of electronic diagonal matrices and the coordinates of the local modes for the high- and low-spin states of the spin crossover complex. Finally, we demonstrate that the approach provides a reasonable explanation of the observed spin transition in the [Fe(ptz)6](BF4)2 crystal. The theory well reproduces the observed abrupt low-spin → high-spin transition and the temperature dependence of the high-spin fraction in a wide temperature range as well as the pronounced hysteresis loop. At the same time within the limiting approximations adopted in the developed model, the evaluated high-spin fraction vs. T shows that the cooperative spin-lattice transition proves to be incomplete in the sense that the high-spin fraction does not reach its maximum value at high temperature.
Report on the Program “Fluid-mediated particle transport in geophysical flows” at the Kavli Institute for Theoretical Physics, UC Santa Barbara, September 23 to December 12, 2013
Authors: Jenkins James T. , Meiburg Eckart , Valance Alexandre
Published: August 2015

The Kavli Institute of Theoretical Physics (KITP) program held at UC Santa Barbara in the fall of 2013 addressed the dynamics of dispersed particulate flows in the environment. By focusing on the prototypes of aeolian transport and turbidity currents, it aimed to establish the current state of our understanding of such two-phase flows, to identify key open questions, and to develop collaborative research strategies for addressing these questions. Here, we provide a brief summary of the program outcome.
The breaks and the hidden components in the power-law spectra of synchrotron radiation of the self-consistent current structures
Authors: Kocharovsky V. V. , Kocharovsky VI. V. , Martyanov V. Ju. , Tarasov S. V.
Published: August 2015

Widespread use of a broken-power-law description of the spectra of synchrotron emission of various plasma objects requires an analysis of origin and a proper interpretation of spectral components. We show that, for a self-consistent magnetic configuration in a collisionless plasma, these components may be angle-dependent according to an anisotropic particle momentum distribution and may have no counterparts in a particle energy distribution. That has never been studied analytically and is in contrast to a usual model of synchrotron radiation, assuming an external magnetic field and a particle ensemble with isotropic momentum distribution. We demonstrate that for the wide intervals of observation angle the power-law spectra and, in particular, the positions and number of spectral breaks may be essentially different for the cases of the self-consistent and not-self-consistent magnetic fields in current structures responsible for the synchrotron radiation of the ensembles of relativistic particles with the multi-power-law energy distributions.
Cosmic ray transport in astrophysical plasmas
Authors: Schlickeiser R.
Published: August 2015

Since the development of satellite space technology about 50 years ago the solar heliosphere is explored almost routinely by several spacecrafts carrying detectors for measuring the properties of the interplanetary medium including energetic charged particles (cosmic rays), solar wind particle densities, and electromagnetic fields. In 2012, the Voyager 1 spacecraft has even left what could be described as the heliospheric modulation region, as indicated by the sudden disappearance of low energy heliospheric cosmic ray particles. With the available in-situ measurements of interplanetary turbulent electromagnetic fields and of the momentum spectra of different cosmic ray species in different interplanetary environments, the heliosphere is the best cosmic laboratory to test our understanding of the transport and acceleration of cosmic rays in space plasmas. I review both the historical development and the current state of various cosmic ray transport equations. Similarities and differences to transport theories for terrestrial fusion plasmas are highlighted. Any progress in cosmic ray transport requires a detailed understanding of the electromagnetic turbulence that is responsible for the scattering and acceleration of these particles.
Anisotropy of heat conduction in Mo/Si multilayers
Authors: Medvedev V. V. , Yang J. , Schmidt A. J. , Yakshin A. E. , van de Kruijs R. W. E. , Zoethout E. , Bijkerk F.
Published: August 2015

This paper reports on the studies of anisotropic heat conduction phenomena in Mo/Si multilayers with individual layer thicknesses selected to be smaller than the mean free path of heat carriers. We applied the frequency-domain thermoreflectance technique to characterize the thermal conductivity tensor. While the mechanisms of the cross-plane heat conduction were studied in detail previously, here we focus on the in-plane heat conduction. To analyze the relative contribution of electron transport to the in-plane heat conduction, we applied sheet-resistance measurements. Results of Mo/Si multilayers with variable thickness of the Mo layers indicate that the net in-plane thermal conductivity depends on the microstructure of the Mo layers.
Characterization of complexity in the electroencephalograph activity of Alzheimer's disease based on fuzzy entropy
Authors: Cao Yuzhen , Cai Lihui , Wang Jiang , Wang Ruofan , Yu Haitao , Cao Yibin , Liu Jing
Published: August 2015

In this paper, experimental neurophysiologic recording and statistical analysis are combined to investigate the nonlinear characteristic and the cognitive function of the brain. Fuzzy approximate entropy and fuzzy sample entropy are applied to characterize the model-based simulated series and electroencephalograph (EEG) series of Alzheimer's disease (AD). The effectiveness and advantages of these two kinds of fuzzy entropy are first verified through the simulated EEG series generated by the alpha rhythm model, including stronger relative consistency and robustness. Furthermore, in order to detect the abnormality of irregularity and chaotic behavior in the AD brain, the complexity features based on these two fuzzy entropies are extracted in the delta, theta, alpha, and beta bands. It is demonstrated that, due to the introduction of fuzzy set theory, the fuzzy entropies could better distinguish EEG signals of AD from that of the normal than the approximate entropy and sample entropy. Moreover, the entropy values of AD are significantly decreased in the alpha band, particularly in the temporal brain region, such as electrode T3 and T4. In addition, fuzzy sample entropy could achieve higher group differences in different brain regions and higher average classification accuracy of 88.1% by support vector machine classifier. The obtained results prove that fuzzy sample entropy may be a powerful tool to characterize the complexity abnormalities of AD, which could be helpful in further understanding of the disease.
Full-dimensional, high-level ab initio potential energy surfaces for H2(H2O) and H2(H2O)2 with application to hydrogen clathrate hydrates
Authors: Homayoon Zahra , Conte Riccardo , Qu Chen , Bowman Joel M.
Published: August 2015

New, full-dimensional potential energy surfaces (PESs), obtained using precise least-squares fitting of high-level electronic energy databases, are reported for intrinsic H2(H2O) two-body and H2(H2O)2 three-body potentials. The database for H2(H2O) consists of approximately 44 000 energies at the coupled cluster singles and doubles plus perturbative triples (CCSD(T))-F12a/haQZ (aug-cc-pVQZ for O and cc-pVQZ for H) level of theory, while the database for the three-body interaction consists of more than 36 000 energies at the CCSD(T)-F12a/haTZ (aug-cc-pVTZ for O, cc-pVTZ for H) level of theory. Two precise potentials are based on the invariant-polynomial technique and are compared to computationally faster ones obtained via “purified” symmetrization. All fits use reduced permutational symmetry appropriate for these non-covalent interactions. These intrinsic potentials are employed together with existing ones for H2, H2O, and (H2O)2, to obtain full PESs for H2(H2O) and H2(H2O)2. Properties of these full PESs are presented, including a diffusion Monte Carlo calculation of the zero-point energy and wavefunction, and dissociation energy of the H2(H2O) dimer. These PESs together with an existing one for water clusters are used in a many-body representation of the PES of hydrogen clathrate hydrates, illustrated for H2@(H2O)20. An analysis of this hydrate is presented, including the electronic dissociation energy to remove H2 from the calculated equilibrium structure.
Second harmonic generation spectroscopy in the Reststrahl band of SiC using an infrared free-electron laser
Authors: Paarmann Alexander , Razdolski Ilya , Melnikov Alexey , Gewinner Sandy , Schöllkopf Wieland , Wolf Martin
Published: August 2015

The Reststrahl spectral region of silicon carbide has recently attracted much attention owing to its potential for mid-infrared nanophotonic applications based on surface phonon polaritons (SPhPs). Studies of optical phonon resonances responsible for surface polariton formation, however, have so far been limited to linear optics. In this Letter, we report the first nonlinear optical investigation of the Reststrahl region of SiC, employing an infrared free-electron laser to perform second harmonic generation (SHG) spectroscopy. We observe two distinct resonance features in the SHG spectra, one attributed to resonant enhancement of the nonlinear susceptibility χ(2) and the other due to a resonance in the Fresnel transmission. Our work clearly demonstrates high sensitivity of mid-infrared SHG to phonon-driven phenomena and opens a route to studying nonlinear effects in nanophotonic structures based on SPhPs.
Microphase separation in polydisperse rod-rod diblock copolymer melt
Authors: Aliev M. A. , Kuzminyh N. Yu.
Published: August 2015

The stability limits of the isotropic state of melt of rod-rod AB polydisperse diblock copolymer have been studied within weak segregation theory. The number of units in A block is assumed to be a random variable distributed by the Schulz-Zimm distribution. Inspection of the spinodal curves shows that the copolymer melt with polydisperse rigid blocks is less stable with respect to formation of the nematic and microphase separated states than the monodisperse melt. The values of ratios between strengths of isotropic and anisotropic interactions in the system strongly influences the forms of isotropic-nematic boundary curves.
Electron scattering times in ZnO based polar heterostructures
Authors: Falson J. , Kozuka Y. , Smet J. H. , Arima T. , Tsukazaki A. , Kawasaki M.
Published: August 2015

The remarkable historic advances experienced in condensed matter physics have been enabled through the continued exploration and proliferation of increasingly richer and cleaner material systems. In this work, we report on the scattering times of charge carriers confined in state-of-the-art MgZnO/ZnO heterostructures displaying electron mobilities in excess of 106 cm2/V s. Through an examination of low field quantum oscillations, we obtain the effective mass of charge carriers, along with the transport and quantum scattering times. These times compare favorably with high mobility AlGaAs/GaAs heterostructures, suggesting the quality of MgZnO/ZnO heterostructures now rivals that of traditional semiconductors.
Carrier dynamics and transient photobleaching in thin layers of black phosphorus
Authors: Suess Ryan J. , Jadidi Mohammad M. , Murphy Thomas E. , Mittendorff Martin
Published: August 2015

We present polarization-resolved transient transmission measurements on multi-layer black phosphorus. Background free two-color pump-probe spectroscopy measurements are carried out on mechanically exfoliated black phosphorus flakes that have been transferred to a large-bandgap, silicon carbide substrate. The blue-shifted pump pulse (780 nm) induces an increased transmission of the probe pulse (1560 nm) over a time scale commensurate with the measurement resolution (hundreds of fs). After the initial pump-induced transparency, the sign of the transient flips and a slower enhanced absorption is observed. This extended absorption is characterized by two relaxation time scales of 180 ps and 1.3 ns. The saturation peak is attributed to Pauli blocking while the extended absorption is ascribed to a Drude response of the pump-induced carriers. The anisotropic carrier mobility in the black phosphorus leads to different weights of the Drude absorption, depending on the probe polarization, which is readily observed in the amplitude of the pump-probe signals.
Phospholipid—polymer amphiphile hybrid assemblies and their interaction with macrophages
Authors: Panneerselvam Karthiga , Lynge Martin E. , Riber Camilla Frich , Mena-Hernando Sofia , Smith Anton A. A. , Goldie Kenneth N. , Zelikin Alexander N. , Städler Brigitte
Published: August 2015

Recently, the combination of lipids and block copolymers has become an alternative to liposomes and polymersomes as nano-sized drug carriers. We synthesize novel block copolymers consisting of poly(cholesteryl acrylate) as the hydrophobic core and poly(N-isopropylacrylamide) (PNIPAAm) as the hydrophilic extensions. Their successful phospholipid-assisted assembly into vesicles is demonstrated using the evaporation-hydration method. The preserved thermo-responsive property of the lipid-polymer hybrids is shown by a temperature dependent adsorption behaviour of the vesicles to poly(l lysine) coated surfaces. As expected, the vesicle adsorption is found to be higher at elevated temperatures. The cellular uptake efficiency of hybrids is assessed using macrophages with applied shear stress. The amount of adhering macrophages is affected by the time and level of applied shear stress. Further, it is found that shorter PNIPAAm extensions lead to higher uptake of the assemblies by the macrophages with applied shear stress. No inherent cytotoxicity is observed at the tested conditions. Taken together, this first example of responsive lipid-polymer hybrids, and their positive biological evaluation makes them promising nano-sized drug carrier candidates.
Photocurrent-voltage relation of resonant tunneling diode photodetectors
Authors: Pfenning Andreas , Hartmann Fabian , Rebello Sousa Dias Mariama , Langer Fabian , Kamp Martin , Castelano Leonardo Kleber , Lopez-Richard Victor , Marques Gilmar Eugenio , Höfling Sven , Worschech Lukas
Published: August 2015

We have investigated photodetectors based on an AlGaAs/GaAs double barrier structure with a nearby lattice-matched GaInNAs absorption layer. Photons with the telecommunication wavelength λ=1.3 μm lead to hole accumulation close to the double barrier inducing a voltage shift ΔV(V) of the current-voltage curve, which depends strongly on the bias voltage V. A model is proposed describing ΔV(V) and the photocurrent response in excellent agreement with the experimental observations. According to the model, an interplay of the resonant tunneling diode (RTD) quantum efficiency η(V), the lifetime of photogenerated and accumulated charge carriers τ(V), and the RTD current-voltage relation in the dark determines best working parameters of RTD photodetectors. Limitations and voltage dependencies of the photoresponse are discussed.
Near-infrared multi-wavelengths long persistent luminescence of Nd3+ ion through persistent energy transfer in Ce3+, Cr3+ co-doped Y3Al2Ga3O12 for the first and second bio-imaging windows
Authors: Xu Jian , Tanabe Setsuhisa , Sontakke Atul D. , Ueda Jumpei
Published: August 2015

We developed a persistent phosphor of Y3Al2Ga3O12 doped with Nd3+, Ce3+, Cr3+ ions (YAGG:Nd-Ce-Cr) exhibiting long (>10 h) persistent luminescence at multi-wavelengths of around 880, 1064, and 1335 nm due to f-f transitions of Nd3+ and at 505 nm due to Ce3+:5d1→4f transition. The intense near-infrared (NIR) persistent luminescence bands from Nd3+ match well with the first (650–950 nm) and second (1000–1400 nm) bio-imaging windows. The NIR persistent radiance of the YAGG:Nd-Ce-Cr phosphor (0.33 × 10−1 mW/Sr/m2) at 60 min after ceasing blue light illumination was over 2 times higher than that of the widely used ZnGa2O4:Cr3+ red persistent phosphor (0.15 × 10−1 mW/Sr/m2).
InAs/AlAsSb based quantum cascade detector
Authors: Reininger Peter , Zederbauer Tobias , Schwarz Benedikt , Detz Hermann , MacFarland Donald , Andrews Aaron Maxwell , Schrenk Werner , Strasser Gottfried
Published: August 2015

In this letter, we introduce the InAs/AlAsSb material system for quantum cascade detectors (QCDs). InAs/AlAsSb can be grown lattice matched to InAs and exhibits a conduction band offset of approximately 2.1 eV, enabling the design of very short wavelength quantum cascade detectors. Another benefit using this material system is the low effective mass of the well material that improves the total absorption of the detector and decreases the intersubband scattering rates, which increases the device resistance and thus enhances the noise behavior. We have designed, grown, and measured a QCD that detects at a wavelength of λ = 4.84 μm and shows a peak specific detectivity of approximately 2.7 × 107 Jones at T = 300 K.
Localized surface phonon polariton resonances in polar gallium nitride
Authors: Feng Kaijun , Streyer William , Islam S. M. , Verma Jai , Jena Debdeep , Wasserman Daniel , Hoffman Anthony J.
Published: August 2015

We demonstrate the excitation of localized surface phonon polaritons in an array of sub-diffraction pucks fabricated in an epitaxial layer of gallium nitride (GaN) on a silicon carbide (SiC) substrate. The array is characterized via polarization- and angle-dependent reflection spectroscopy in the mid-infrared, and coupling to several localized modes is observed in the GaN Reststrahlen band (13.4–18.0 μm). The same structure is simulated using finite element methods and the charge density of the modes are studied; transverse dipole modes are identified for the transverse electric and magnetic polarizations and a quadrupole mode is identified for the transverse magnetic polarization. The measured mid-infrared spectrum agrees well with numerically simulated spectra. This work could enable optoelectronic structures and devices that support surface modes at mid- and far-infrared wavelengths.
Dielectric properties of semi-insulating silicon at microwave frequencies
Authors: Krupka Jerzy , Kamiński Paweł , Kozłowski Roman , Surma Barbara , Dierlamm Alexander , Kwestarz Michał
Published: August 2015

The permittivity and dielectric loss tangent of high-purity silicon with semi-insulating properties achieved by the irradiation with 23-MeV protons have been measured at frequencies from 1 GHz to 15 GHz. The dielectric losses were separated from the conductor losses on the basis of the total loss tangent measurements versus frequency. The resistivity measurements of the material performed at radio frequencies (RF) by means of the capacitance spectroscopy method have shown the non-uniform resistivity distribution in the direction perpendicular to the surface of the semi-insulating wafer. The excellent agreement between the resistivity measurements results at RF and those obtained by using microwave methods have been achieved. It has been confirmed that high-purity, semi-insulating silicon is practically non-dispersive and possesses extremely low dielectric losses that are constant to within experimental errors in the frequency range from 1 GHz to 350 GHz. In this frequency range, the dielectric loss tangent of semi-insulating silicon is equal to 1.2×10−5.
Re-analysis of wind and slope effects on flame characteristics of Mediterranean shrub fires
Authors: Nelson Ralph M.
Published: August 2015

During the past 20 years, study of wind–slope-aided wildland fire behaviour with experimental burns and physical modelling methods has increased. As part of their continuing study of fires in Mediterranean shrub, F. Morandini and X. Silvani reported experimental temperatures, heat fluxes, flame characteristics and other fire behaviour variables measured on five wind–slope-aided fires. Calculating convection numbers and several convective Froude numbers, the authors concluded that these dimensionless variables for their two wind-dominated fires did not satisfy criteria identified in previous studies for determining mechanisms of heat transfer during fuel preheating. The present paper describes a re-analysis of the data based on a triangular flame model and alternative definitions of flame tilt angle and height. This new analysis has shown that the influence of slope on the fire behaviour was not accounted for; thus, the conclusion of Morandini and Silvani is questionable. Of the five dimensionless variables studied using criteria in the literature, the squared flame height convective Froude number best describes modes of heat transfer to unburned fuels during the experimental fires. Though these results come indirectly from field measurements, they confirm the need to include slope effects in descriptions of wind–slope-aided fire behaviour.
Corrigendum to: Estimates of abundance and apparent survival of coastal dolphins in Port Essington harbour, Northern Territory, Australia
Authors: Palmer Carol , Brooks Lyndon , Parra Guido J. , Rogers Tracey , Glasgow Debra , Woinarski John C. Z.
Published: August 2015

Context
Three dolphin species occur in coastal waters of monsoonal northern Australia: the Australian snubfin (Orcaella heinsohni), humpback (Sousa sp.) and the bottlenose (Tursiops sp.). Their overall population size and trends are poorly known, and their conservation status has been difficult to resolve, but can be expected to deteriorate with likely increased development pressures.

Aims
We sought to provide an estimate of abundance, and apparent survival, of the three dolphin species at the largely undeveloped harbour of Port Essington (325km2), Northern Territory, with repeated sampling over a 2.9-year period. Given increasing obligations to undertake population assessments for impact studies at proposed development sites, we assess the strengths and limitations of a systematic sampling program.
Development of LC-MS/MS analysis of cyclic dipeptides and its application to tea extract
Authors: Yamamoto Kenji , Hayashi Miki , Murakami Yuka , Araki Yoko , Otsuka Yuuki , Kashiwagi Takehiro , Shimamura Tomoko , Ukeda Hiroyuki
Published: August 2015

2,5-Diketopiperazines (DKPs), also called cyclic dipeptides, have been known to occur in various foods. Recently, DKPs have attracted attentions as bioactive components. There were some reports on analytical methods for DKPs, but the number of analyzed DKPs was only a part of all DKPs and the quantitative performance was not studied in detail. In this study, we selected 31 kinds of DKPs and developed a quantitative and simultaneous analytical method using LC-MS/MS. This method was applied to DKPs determination in Pu-erh tea, post-fermentation tea, and 18 kinds of DKPs were determined at concentration of 0.0017–0.11 ppm. As a result of spiked test, it was concluded that the developed method using LC-MS/MS was useful for estimating DKPs concentration in tea.
Tumebacillus luteolus sp. nov., isolated from soil
Authors: Her Jihee , Srinivasan Sathiyaraj , Lee Sang-Seob
Published: August 2015

Two strains of Gram-stain-positive, aerobic, spore-forming and rod-shaped bacteria, designated U13T and U14, were isolated from soil of the Ukraine. Comparative analysis of the 16S rRNA gene sequences indicated that these strains belong to the genus Tumebacillus, with the highest 16S rRNA gene sequence similarity with Tumebacillus ginsengisoli Gsoil 1105T (95.48 % and 95.49 %, respectively). Strains U13T and U14 had iso-C15 : 0 and summed features 1 and 4 as the main fatty acids, and were able to grow at pH ranging from pH 5.0 to 9.0 (optimum pH 6.0–7.0), temperatures ranging from 25 to 42 °C (optimum 28–37 °C) and with 0–1 % (w/v) NaCl (optimum 0 %, w/v) on R2A agar medium. Chemotaxonomic data revealed that the cell-wall peptidoglycan type of the two strains was type A1γ (meso-diaminopimelic acid). On the basis of the evidence from this study, strains U13T and U14 represent a novel species of the genus Tumebacillus, for which the name Tumebacillus luteolus sp. nov. is proposed. The type strain is U13T ( = KEMB 7305-100T = JCM 19866T) and a second strain is U14 ( = KEMB 7305-101 = JCM 19867).
Local and sex-specific biases in crossover vs. noncrossover outcomes at meiotic recombination hot spots in mice
Authors: de Boer Esther , Jasin Maria , Keeney Scott
Published: August 2015

Meiotic recombination initiated by programmed double-strand breaks (DSBs) yields two types of interhomolog recombination products, crossovers and noncrossovers, but what determines whether a DSB will yield a crossover or noncrossover is not understood. In this study, we analyzed the influence of sex and chromosomal location on mammalian recombination outcomes by constructing fine-scale recombination maps in both males and females at two mouse hot spots located in different regions of the same chromosome. These include the most comprehensive maps of recombination hot spots in oocytes to date. One hot spot, located centrally on chromosome 1, behaved similarly in male and female meiosis: Crossovers and noncrossovers formed at comparable levels and ratios in both sexes. In contrast, at a distal hot spot, crossovers were recovered only in males even though noncrossovers were obtained at similar frequencies in both sexes. These findings reveal an example of extreme sex-specific bias in recombination outcome. We further found that estimates of relative DSB levels are surprisingly poor predictors of relative crossover frequencies between hot spots in males. Our results demonstrate that the outcome of mammalian meiotic recombination can be biased, that this bias can vary depending on location and cellular context, and that DSB frequency is not the only determinant of crossover frequency.
piRNA-guided slicing of transposon transcripts enforces their transcriptional silencing via specifying the nuclear piRNA repertoire
Authors: Senti Kirsten-André , Jurczak Daniel , Sachidanandam Ravi , Brennecke Julius
Published: August 2015

PIWI clade Argonaute proteins silence transposon expression in animal gonads. Their target specificity is defined by bound ∼23- to 30-nucleotide (nt) PIWI-interacting RNAs (piRNAs) that are processed from single-stranded precursor transcripts via two distinct pathways. Primary piRNAs are defined by the endonuclease Zucchini, while biogenesis of secondary piRNAs depends on piRNA-guided transcript cleavage and results in piRNA amplification. Here, we analyze the interdependencies between these piRNA biogenesis pathways in developing Drosophila ovaries. We show that secondary piRNA-guided target slicing is the predominant mechanism that specifies transcripts—including those from piRNA clusters—as primary piRNA precursors and defines the spectrum of Piwi-bound piRNAs in germline cells. Post-transcriptional silencing in the cytoplasm therefore enforces nuclear transcriptional target silencing, which ensures the tight suppression of transposons during oogenesis. As target slicing also defines the nuclear piRNA pool during mouse spermatogenesis, our findings uncover an unexpected conceptual similarity between the mouse and fly piRNA pathways.