bluuebunny/crossref_metadata_2025 huggingface dataset:
Multi-GeV electron-positron beam generation from laser-electron scattering
Authors: Vranic Marija , Klimo Ondrej , Korn Georg , Weber Stefan
Published: March 2018

The new generation of laser facilities is expected to deliver short (10 fs–100 fs) laser pulses with 10–100 PW of peak power. This opens an opportunity to study matter at extreme intensities in the laboratory and provides access to new physics. Here we propose to scatter GeV-class electron beams from laser-plasma accelerators with a multi-PW laser at normal incidence. In this configuration, one can both create and accelerate electron-positron pairs. The new particles are generated in the laser focus and gain relativistic momentum in the direction of laser propagation. Short focal length is an advantage, as it allows the particles to be ejected from the focal region with a net energy gain in vacuum. Electron-positron beams obtained in this setup have a low divergence, are quasi-neutral and spatially separated from the initial electron beam. The pairs attain multi-GeV energies which are not limited by the maximum energy of the initial electron beam. We present an analytical model for the expected energy cutoff, supported by 2D and 3D particle-in-cell simulations. The experimental implications, such as the sensitivity to temporal synchronisation and laser duration is assessed to provide guidance for the future experiments.
Non-invasive Estimation of the Intracranial Pressure Waveform from the Central Arterial Blood Pressure Waveform in Idiopathic Normal Pressure Hydrocephalus Patients
Authors: Evensen Karen Brastad , O’Rourke Michael , Prieur Fabrice , Holm Sverre , Eide Per Kristian
Published: March 2018

This study explored the hypothesis that the central aortic blood pressure (BP) waveform may be used for non-invasive estimation of the intracranial pressure (ICP) waveform. Simultaneous invasive ICP and radial artery BP waveforms were measured in 29 individuals with idiopathic normal pressure hydrocephalus (iNPH). The central aortic BP waveforms were estimated from the radial artery BP waveforms using the SphygmoCor system. For each individual, a transfer function estimate between the central aortic BP and the invasive ICP waveforms was found (Intra-patient approach). Thereafter, the transfer function estimate that gave the best fit was chosen and applied to the other individuals (Inter-patient approach). To validate the results, ICP waveform parameters were calculated for the estimates and the measured golden standard. For the Intra-patient approach, the mean absolute difference in invasive versus non-invasive mean ICP wave amplitude was 1.9 ± 1.0 mmHg among the 29 individuals. Correspondingly, the Inter-patient approach resulted in a mean absolute difference of 1.6 ± 1.0 mmHg for the 29 individuals. This method gave a fairly good estimate of the wave for about a third of the individuals, but the variability is quite large. This approach is therefore not a reliable method for use in clinical patient management.
The relation between global palm distribution and climate
Authors: Reichgelt Tammo , West Christopher K. , Greenwood David R.
Published: March 2018

Fossil palms provide qualitative evidence of (sub-) tropical conditions and frost-free winters in the geological past, including modern cold climate regions (e.g., boreal, or polar climates). The freeze intolerance of palms varies across different organs and life stages, with seedlings in particular less tolerant of sub-zero temperatures than adult plants, limiting successful establishment of populations while permitting adult palms to survive in cultivation outside their natural ranges. Quantitatively, palms indicate minimum cold month mean temperature (CMMT) at 2–8 °C in palaeoclimate reconstructions. These data have accentuated model-proxy mismatches for high latitudes during Paleogene hyperthermals when palms expanded poleward in both hemispheres. We constructed a manually filtered dataset of >20,000 georeferenced Arecaceae records, by eliminating cultivars. Statistically derived mean annual temperature, mean annual temperature range, and CMMT thresholds for the Arecaceae and lower rank subfamilies and tribes reveal large differences in temperature sensitivity depending on lower taxonomic classification. Cold tolerant tribes such as the Trachycarpeae produce thresholds as low as CMMT ≥ 2.2 °C. However, within the palm family, CMMT < 5 °C is anomalous. Moreover, palm expansion into temperate biomes is likely a post-Palaeogene event. We recognize a CMMT ≥ 5.2 °C threshold for the palm family, unless a lower taxonomic rank can be assigned.
Characterization of the pgf operon involved in the posttranslational modification of Streptococcus mutans surface proteins
Authors: Avilés-Reyes Alejandro , Freires Irlan Almeida , Besingi Richard , Purushotham Sangeetha , Deivanayagam Champion , Brady L. Jeannine , Abranches Jacqueline , Lemos José A.
Published: March 2018

Protein glycosylation has been described as the most abundant and complex post-translational modification occurring in nature. Recent studies have enhanced our view of how this modification occurs in bacteria highlighting the role of protein glycosylation in various processes such as biofilm formation, virulence and host-microbe interactions. We recently showed that the collagen- and laminin-binding adhesin Cnm of the dental pathogen Streptococcus mutans is post-translationally modified by the PgfS glycosyltransferase. Following this initial identification of Cnm as a glycoprotein, we have now identified additional genes (pgfM1, pgfE and pgfM2) that are also involved in the posttranslational modification of Cnm. Similar to the previously characterized ΔpgfS strain, inactivation of pgfM1, pgfE or pgfM2 directly impacts Cnm by altering its migration pattern, proteolytic stability and function. In addition, we identified the wall-associated protein A (WapA) as an additional substrate of Pgf-dependent modification. We conclude that the pgS-pgfM1-pgfE-pgfM2 operon encodes for a protein machinery that can modify, likely through the addition of glycans, both core and non-core gene products in S. mutans.
Cationic ionene as an n-dopant agent of poly(3,4-ethylenedioxythiophene)
Authors: Saborío Maricruz G. , Bertran Oscar , Lanzalaco Sonia , Häring Marleen , Díaz Díaz David , Estrany Francesc , Alemán Carlos
Published: March 2018

Poly(3,4-ethylenedioxythiophene) has been n-doped using a cationic 1,4-diazabicyclo[2.2.2]octane-based ionene bearing N,N′-(meta-phenylene)dibenzamide linkages.
Modelling molecular adsorption on charged or polarized surfaces: a critical flaw in common approaches
Authors: Bal Kristof M. , Neyts Erik C.
Published: March 2018

Many theoretical predictions of charge- or external field-enhanced adsorption are in severe error due to inconsiderate treatment of periodicity.
High-resolution synchrotron terahertz investigation of the large-amplitude hydrogen bond librational band of (HCN)2
Authors: Mihrin D. , Jakobsen P. W. , Voute A. , Manceron L. , Wugt Larsen R.
Published: March 2018

The high-resolution terahertz absorption spectrum of the large-amplitude intermolecular donor librational band ν18 of the homodimer (HCN)2 has been recorded by means of long-path static gas-phase Fourier transform spectroscopy at 207 K employing a highly brilliant electron storage ring source.
Anti-tumour active gold(i), palladium(ii) and ruthenium(ii) complexes with thio- and selenoureato ligands: a comparative study
Authors: Molter Anja , Kathrein Stefanie , Kircher Brigitte , Mohr Fabian
Published: March 2018

A comparative study of biological activity (cytotoxicity, apoptosis induction, ROS production) of gold(i), palladium(ii) and ruthenium(ii) complexes with chalcogenourea ligands.
Colloidal and chemical stabilities of iron oxide nanoparticles in aqueous solutions: the interplay of structural, chemical and environmental drivers
Authors: Demangeat E. , Pédrot M. , Dia A. , Bouhnik-le-Coz M. , Grasset F. , Hanna K. , Kamagate M. , Cabello-Hurtado F.
Published: March 2018

The behaviour of nanoparticles in aqueous solution resulting from a complex balancing between pH, surficial and intrinsic properties of nanoparticles.
Bidirectional light-induced conductance switching in molecular wires containing a dimethyldihydropyrene unit
Authors: Bakkar A. , Lafolet F. , Roldan D. , Puyoo E. , Jouvenot D. , Royal G. , Saint-Aman E. , Cobo S.
Published: March 2018

Photochromic coordination polymers, based on zinc(ii) bis-terpyridine-appended dimethyldihydropyrene building blocks, have been synthesized following stepwise synthesis on a surface yielding photo-switchable molecular junctions.
RGD-presenting peptides in amphiphilic and anionic β-sheet hydrogels for improved interactions with cells
Authors: Green Hodaya , Ochbaum Guy , Gitelman-Povimonsky Anna , Bitton Ronit , Rapaport Hanna
Published: March 2018

Schematic presentation of 25% mol FD-RGD in FD anionic β-sheet peptide assemblies (left) that form fibrils (middle). Hydrogels composed of this coassembled peptide system improved cell density compared to FD only hydrogels.
Yixin-Shu facilitated cardiac-like differentiation of mesenchymal stem cells in vitro
Authors: Zhang Jingjing , Guo Feifei , Wu Hongwei , Wei Junying , Xian Minghua , Fan Fangfang , Tang Shihuan , Zhao Ye , Zhang Yi , Li Defeng , Yang Hongjun
Published: March 2018

A network pharmacology analysis indicated intestinal absorption liquid of Yixin-Shu capsules had an effect on cell differentiation, which was verified by its effect on cardiac-like differentiation of mesenchymal stem cells and the potential mechanism was also predicted.
A chemometric study in the area of feasible solution of an acid–base titration ofN-methyl-6-oxyquinolone
Authors: Sawall Mathias , Schmode Stella , Schröder Henning , Ludwig Ralf , Neymeyr Klaus
Published: March 2018

Multivariate curve resolution methods aim at recovering the underlying chemical components from spectroscopic data on chemical reaction systems.
In silico identification of protein targets for chemical neurotoxins using ToxCast in vitro data and read-across within the QSAR toolbox
Authors: Chushak Y. G. , Shows H. W. , Gearhart J. M. , Pangburn H. A.
Published: March 2018

This study evaluates the application of QSAR Toolbox and ToxCast screening data to identify neurological targets for pyrethroids.
Fabrication and assessment of an electrospun polymeric microfiber-based platform under bulk flow conditions with rapid and efficient antigen capture
Authors: Hoy Carlton F. O. , Kushiro Keiichiro , Takai Madoka
Published: March 2018

Correction for ‘Fabrication and assessment of an electrospun polymeric microfiber-based platform under bulk flow conditions with rapid and efficient antigen capture’ by Carlton F. O. Hoy et al., Analyst, 2018, 143, 865–873.
Catalytically active nanorotor reversibly self-assembled by chemical signaling within an eight-component network
Authors: Goswami Abir , Pramanik Susnata , Schmittel Michael
Published: March 2018

As an example of advanced molecular cybernetics eight components work together through chemical signaling reversibly setting up multifunctional nanomachinery.
Mitochondria-localising DNA-binding biscyclometalated phenyltriazole iridium(iii) dipyridophenazene complexes: syntheses and cellular imaging properties
Authors: Sreedharan Sreejesh , Sinopoli Alessandro , Jarman Paul. J. , Robinson Darren , Clemmet Christopher , Scattergood Paul A. , Rice Craig R. , Smythe Carl. G. W. , Thomas James A. , Elliott Paul I. P.
Published: March 2018

New DNA-binding iridium(iii) complexes are presented.
Microporous carbons derived from organosilica-containing carbon dots with outstanding supercapacitance
Authors: Wu Dan , Liu Yuchuan , Wu Yue , Tan Bin , Xie Zailai
Published: March 2018

Microporous carbons with outstanding supercapacitance were synthesized from hydrothermally-synthesized organosilica-modified carbon dots.
Currently used organophosphate flame retardants determined in the settled dust of masjids and hotels of Saudi Arabia, a new insight into human health implications of dust exposure
Authors: Ali Nadeem , Ibrahim Ismail Iqbal Mohammad , Kadi Mohammad W. , Salem Ali Albar Hussain Mohammed
Published: March 2018

Indoor settled dust particles are considered as an important source of human exposure to chemicals such as organophosphate flame retardants (PFRs).
Spiers Memorial Lecture : Introductory lecture: the impact of structure on photoinduced processes in nucleic acids and proteins
Authors: Domratcheva Tatiana , Schlichting Ilme
Published: March 2018

This review gives an overview of the impact of structure on the understanding of photoinduced processes in macromolecules, focusing on systems presented at this Faraday Discussion meeting.
CdII/ZnIIdiscrimination using 2,5-diphenyl[1,3,4]oxadiazole based fluorescent chemosensors
Authors: Formica Mauro , Ambrosi Gianluca , Fusi Vieri , Giorgi Luca , Arca Massimiliano , Garau Alessandra , Pintus Anna , Lippolis Vito
Published: March 2018

Two ditopic PPD based ligands are able to discriminate CdIIover ZnIIin aqueous solution based on the difference in their ionic radii, acting as OFF–ON fluorescent probes.
Cyanine dyes: synergistic action of hydrogen, halogen and chalcogen bonds allows discrete I42− anions in crystals
Authors: Konidaris Konstantis F. , Pilati Tullio , Terraneo Giancarlo , Politzer Peter , Murray Jane S. , Scilabra Patrick , Resnati Giuseppe
Published: March 2018

Discrete tetraiodide dianions (I42−) are formed in crystals via halogen bond coordination of I2 by iodide anions which are pinned in their positions by a network of hydrogen bonds involving a benzoselenazole cyanine dye.
How do plants see the world? – UV imaging with a TiO2nanowire array by artificial photosynthesis
Authors: Kang Ji-Hoon , Leportier Thibault , Park Min-Chul , Han Sung Gyu , Song Jin-Dong , Ju Hyunsu , Hwang Yun Jeong , Ju Byeong-Kwon , Poon Ting-Chung
Published: March 2018

We have exploited the properties of TiO2nanowires as a UV sensor to simulate the phenomenon of photosynthesis in order to come one step closer to understanding how plants see the world.
Enhanced solar water-splitting activity of novel nanostructured Fe2TiO5 photoanode by electrospray and surface F-modification
Authors: Wang Meng , Wu Xiaofeng , Huang Keke , Sun Yu , Zhang Yuan , Zhang Hua , He Jingjing , Chen Huanwen , Ding Jianhua , Feng Shouhua
Published: March 2018

Solar water-splitting activity of novel nanostructured Fe2TiO5 photoanode prepared by the electrospray technique can be enhanced by surface F-modification.
“Design of novel WO3/CB nanohybrids” An affordable and efficient electrochemical sensor for the detection of multifunctional flavonoid rutin
Authors: Kubendhiran Subbiramaniyan , Sakthivel Rajalakshmi , Chen Shen-Ming , Yeah Qin-Jin , Mutharani Bhuvanenthiran , Thirumalraj Balamurugan
Published: March 2018

A CB/WO3nanohybrid-modified SPCE was applied for the electrochemical determination of rutin.
Facile fabrication of CuS microflower as a highly durable sodium-ion battery anode
Authors: An Cuihua , Ni Yang , Wang Zhifeng , Li Xudong , Liu Xizheng
Published: March 2018

CuS micro-flower was synthesized by dealloying and adopted as an anode in SIB with high rate and stable cycle performances.
Heteroatom dopings and hierarchical pores of graphene for synergistic improvement of lithium–sulfur battery performance
Authors: Li Jiahui , Xue Caining , Xi Baojuan , Mao Hongzhi , Qian Yitai , Xiong Shenglin
Published: March 2018

Lithium–sulfur batteries: Both the cycling stability and rate capability are adequately enhanced due to the synergistic effect of heteroatom dopings and hierarchical pores of carbon matrix, guiding the design of advanced scaffolds towards high-performance lithium–sulfur batteries.
The renaissance of nitric oxide: from improvement of stability to enhancement of endocytosis
Authors: Jia Fan , Deng Yongyan , Ji Jian
Published: March 2018

The local generation and intracellular release of NO is no less vital than improving the stability of carriers.
Near-complete photoluminescence retention and improved stability of InP quantum dots after silica embedding for their application to on-chip-packaged light-emitting diodes
Authors: Jang Eun-Pyo , Jo Jung-Ho , Kim Min-Seok , Yoon Suk-Young , Lim Seung-Won , Kim Jiwan , Yang Heesun
Published: March 2018

Silica embedding strategy enabling a nearly full PL retention of the original QY of InP QDs is proposed for the realization of a highly efficient, robust QD-LED platform.
Improved cycling performance and rate stability of ITO-compounded Li2MnSiO4 for lithium-ion batteries
Authors: Liu Jingya , Li Yonghu , Yang Shuai , Ai Jinjin , Lai Chunyan , Xu Qunjie
Published: March 2018

Li2MnSiO4 compounded with indium tin oxide (ITO) was successfully synthesized through a sol–gel method.
Hexagonal VO2 particles: synthesis, mechanism and thermochromic properties
Authors: Xu Hui Yan , Xu Ke Wei , Ma Fei , Chu Paul K.
Published: March 2018

Monoclinic vanadium dioxide VO2 (M) with hexagonal structure is synthesized by hydrothermal method, and the phase evolution is evidenced.
The effect of alcohols as the third component on diffusion in mixtures of aromatics and ketones
Authors: Janzen Tatjana , Gaponenko Yuri , Mialdun Aliaksandr , Guevara-Carrion Gabriela , Vrabec Jadran , Shevtsova Valentina
Published: March 2018

The Fick diffusion coefficient matrix of three ternary mixtures composed of an aromatic (benzene), a ketone (acetone) and one of three different alcohols (methanol, ethanol or 2-propanol) is investigated with laboratory and numerical work.
Interface-rich mixed P2 + T phase NaxCo0.1Mn0.9O2 (0.44 ≤ x ≤ 0.7) toward fast and high capacity sodium storage
Authors: Gao Guofeng , Tie Da , Ma Hao , Yu Haijun , Shi Shanshan , Wang Bo , Xu Shengming , Wang Linlin , Zhao Yufeng
Published: March 2018

This work reports a novel design of mixed P2 + T phase NaxCo0.1Mn0.9O2 for high performance sodium storage, whereby the T phase offers fast Na ion diffusivity and excellent structural stability, and the P2–T phase interface offers additional channels and extra sites for charge transfer and charge storage.
Fine-tuning of nano-traps in a stable metal–organic framework for highly efficient removal of propyne from propylene
Authors: Wen Hui-Min , Li Libo , Lin Rui-Biao , Li Bin , Hu Bin , Zhou Wei , Hu Jun , Chen Banglin
Published: March 2018

A stable MOF material (ZJUT-1) with fine-tuned nanocages, exhibiting the desired size, shape, and functionalities for trapping a single C3H4molecule, can efficiently separate trace amounts of C3H4from a 1/99 C3H4/C3H6mixture.
An outflow in the Seyfert ESO 362-G18 revealed by Gemini-GMOS/IFU observations
Authors: Humire Pedro K. , Nagar Neil M. , Finlez Carolina , Firpo Verónica , Slater Roy , Lena Davide , Soto-Pinto Pamela , Muñoz-Vergara Dania , Riffel Rogemar A. , Schmitt Henrique R. , Kraemer Steven B. , Schnorr-Müller Allan , Fischer Travis C. , Robinson Andrew , Storchi-Bergmann Thaisa , Crenshaw Mike , Elvis Martin S.
Published: March 2018

We present two-dimensional stellar and gaseous kinematics of the inner 0.7 × 1.2 kpc2 of the Seyfert 1.5 galaxy ESO 362-G18, derived from optical (4092–7338 Å) spectra obtained with the GMOS integral field spectrograph on the Gemini South telescope at a spatial resolution of ≈170 pc and spectral resolution of 36 km s−1. ESO 362-G18 is a strongly perturbed galaxy of morphological type Sa or S0/a, with a minor merger approaching along the NE direction. Previous studies have shown that the [O III] emission shows a fan-shaped extension of ≈10′′ to the SE. We detect the [O III] doublet, [N II] and Hα emission lines throughout our field of view.

The stellar kinematics is dominated by circular motions in the galaxy plane, with a kinematic position angle of ≈137° and is centred approximately on the continuum peak. The gas kinematics is also dominated by rotation, with kinematic position angles ranging from 122° to 139°, projected velocity amplitudes of the order of 100 km s−1, and a mean velocity dispersion of 100 km s−1. A double-Gaussian fit to the [O III]λ5007 and Hα lines, which have the highest signal to noise ratios of the emission lines, reveal two kinematic components: (1) a component at lower radial velocities which we interpret as gas rotating in the galactic disk; and (2) a component with line of sight velocities 100–250 km s−1 higher than the systemic velocity, interpreted as originating in the outflowing gas within the AGN ionization cone. We estimate a mass outflow rate of 7.4 × 10−2 M⊙ yr−1 in the SE ionization cone (this rate doubles if we assume a biconical configuration), and a mass accretion rate on the supermassive black hole (SMBH) of 2.2 × 10−2 M⊙ yr−1. The total ionized gas mass within ~84 pc of the nucleus is 3.3 × 105 M⊙; infall velocities of ~34 km s−1 in this gas would be required to feed both the outflow and SMBH accretion.
Les années italiennes du jeune Einstein
Authors: Bracco Christian , Provost Jean-Pierre
Published: March 2018

Une meilleure compréhension de la genèse des idées d’Einstein de 1905 passe par une reconstruction de l’environnement scientifique et des modes et lieux de travail du jeune Albert en Italie, à Pavie et à Milan, entre 1895 à l’âge de seize ans et 1901.

Nous portons notre attention dans cet article sur l’année 1901 et la thèse sur les forces moléculaires qu’il abandonne, avant de se tourner vers la thermodynamique statistique en 1902.
Gallensteine und „Leberverstopfung“ in den medizinischen Fachschriften der Antike
Authors: Ursin Frank , Steger Florian
Published: March 2018

Einleitung Gallensteine werden in den medizinischen Fachschriften der Antike selten erwähnt. Der Arzt Alexander von Tralleis nennt erstmals Steine in der Gallenblase als mögliche Ursache für einen obstruktiven Ikterus. Diese Nennung findet sich in seinem Lehrbuch der Heilkunde unter der Überschrift „Leberverstopfung“. Ausgehend von dieser Beobachtung beschreiben wir die antike Geschichte der Leberverstopfung und untersuchen den Zusammenhang mit der seltenen Erwähnung von Gallensteinen in den medizinischen Fachschriften der Antike.

Methoden In einem ersten Schritt haben wir die seit 1900 erschienene medizinhistorische Forschungsliteratur zu Gallensteinen und Leberverstopfung in der Antike ausgewertet. Die dadurch ermittelten antiken Originaltexte haben wir hinsichtlich Ätiologie, Diagnostik und Therapie analysiert. In einem zweiten Schritt haben wir mit einer kombinierten Stichwortsuche in griechischen und lateinischen Textdatenbanken weitere Originaltexte gesucht. Mit den Ergebnissen haben wir die aus der Forschungsliteratur bekannten Erwähnungen von Gallensteinen und Leberverstopfung auf ihre Vollständigkeit hin überprüft.

Ergebnisse Es sind zwei Erwähnungen von Steinen in Leber und Gallenblase belegbar: Aristoteles beschreibt wahrscheinlich Steine in der Leber geschlachteter Opfertiere und der spätantike Arzt Alexander von Tralleis in der Gallenblase eines Menschen. Die mechanische Obstruktion der Gallenwege als Ursache für einen Ikterus ist seit Diokles von Karystos (4. Jh. v. Chr.) bekannt. Das Krankheitsbild einer Leberverstopfung beschreibt erstmals Galen von Pergamon (2. Jh. n. Chr.). Er führte es auf die Koagulation der gelben Galle zurück, eines der vier Säfte der antiken Humoralpathologie.

Schlussfolgerung Obwohl Gallensteine selten genannt wurden, war den antiken Autoren medizinischer Fachschriften das klinische Bild von Gallensteinleiden bekannt und wurde als Leberverstopfung bezeichnet.
Tunable magnetic and transport properties of Mn3Ga thin films on Ta/Ru seed layer
Authors: Hu Fang , Xu Guizhou , You Yurong , Zhang Zhi , Xu Zhan , Gong Yuanyuan , Liu Er , Zhang Hongguo , Liu Enke , Wang Wenhong , Xu Feng
Published: March 2018

Hexagonal D019-type Mn3Z alloys that possess large anomalous and topological-like Hall effects have attracted much attention due to their great potential in antiferromagnetic spintronic devices. Herein, we report the preparation of Mn3Ga films in both tetragonal and hexagonal phases with a tuned Ta/Ru seed layer on a thermally oxidized Si substrate. Large coercivity together with large anomalous Hall resistivity is found in the Ta-only sample with a mixed tetragonal phase. By increasing the thickness of the Ru layer, the tetragonal phase gradually disappears and a relatively pure hexagonal phase is obtained in the Ta(5)/Ru(30) buffered sample. Further magnetic and transport measurements revealed that the anomalous Hall conductivity nearly vanishes in the pure hexagonal sample, while an abnormal asymmetric hump structure emerges in the low field region. The extracted additional Hall term is robust in a large temperature range and presents a sign reversal above 200 K. The abnormal Hall properties are proposed to be closely related to the frustrated spin structure of D019 Mn3Ga.
Dynamics of small unilamellar vesicles
Authors: Hoffmann Ingo , Hoffmann Claudia , Farago Bela , Prévost Sylvain , Gradzielski Michael
Published: March 2018

In this paper, we investigate the dynamics of small unilamellar vesicles with the aid of neutron spin-echo spectroscopy. The purpose of this investigation is twofold. On the one hand, we investigate the influence of solubilised cosurfactant on the dynamics of the vesicle’s surfactant bilayer. On the other hand, the small unilamellar vesicles used here have a size between larger vesicles, with dynamics being well described by the Zilman-Granek model and smaller microemulsion droplets which can be described by the Milner-Safran model. Therefore, we want to elucidate the question, which model is more suitable for the description of the membrane dynamics of small vesicles, where the finite curvature of the bilayer is felt by the contained amphiphilic molecules. This question is of substantial relevance for our understanding of membranes and how their dynamics is affected by curvature, a problem that is also of key importance in a number of biological questions. Our results indicate the even down to vesicle radii of 20 nm the Zilman-Granek model appears to be the more suitable one.
The quantum distribution functions for many-component plasmas
Authors: Eisa D. A.
Published: March 2018

In the present paper, we used the Bogoliubov-Born-Green-Kirkwood-Yvon hierarchy to obtain the s-particle distribution functions for thermal equilibrium many-component plasmas. The analytical forms of the quantum binary and triplet distribution functions were calculated for a neutral electron-positron plasma until Ο(μab4) (μab is the plasma parameter). Also, we calculate the first, second, and third quantum corrections to the binary and triplet distribution functions.
Analysis and synthesis of bianisotropic metasurfaces by using analytical approach based on equivalent parameters
Authors: Danaeifar Mohammad , Granpayeh Nosrat
Published: March 2018

An analytical method is presented to analyze and synthesize bianisotropic metasurfaces. The equivalent parameters of metasurfaces in terms of meta-atom properties and other specifications of metasurfaces are derived. These parameters are related to electric, magnetic, and electromagnetic/magnetoelectric dipole moments of the bianisotropic media, and they can simplify the analysis of complicated and multilayer structures. A metasurface of split ring resonators is studied as an example demonstrating the proposed method. The optical properties of the meta-atom are explored, and the calculated polarizabilities are applied to find the reflection coefficient and the equivalent parameters of the metasurface. Finally, a structure consisting of two metasurfaces of the split ring resonators is provided, and the proposed analytical method is applied to derive the reflection coefficient. The validity of this analytical approach is verified by full-wave simulations which demonstrate good accuracy of the equivalent parameter method. This method can be used in the analysis and synthesis of bianisotropic metasurfaces with different materials and in different frequency ranges by considering electric, magnetic, and electromagnetic/magnetoelectric dipole moments.
Degradation effects of the active region in UV-C light-emitting diodes
Authors: Glaab Johannes , Haefke Joscha , Ruschel Jan , Brendel Moritz , Rass Jens , Kolbe Tim , Knauer Arne , Weyers Markus , Einfeldt Sven , Guttmann Martin , Kuhn Christian , Enslin Johannes , Wernicke Tim , Kneissl Michael
Published: March 2018

An extensive analysis of the degradation characteristics of AlGaN-based ultraviolet light-emitting diodes emitting around 265 nm is presented. The optical power of LEDs stressed at a constant dc current of 100 mA (current density = 67 A/cm2 and heatsink temperature = 20 °C) decreased to about 58% of its initial value after 250 h of operation. The origin of this degradation effect has been studied using capacitance-voltage and photocurrent spectroscopy measurements conducted before and after aging. The overall device capacitance decreased, which indicates a reduction of the net charges within the space-charge region of the pn-junction during operation. In parallel, the photocurrent at excitation energies between 3.8 eV and 4.5 eV and the photocurrent induced by band-to-band absorption in the quantum barriers at 5.25 eV increased during operation. The latter effect can be explained by a reduction of the donor concentration in the active region of the device. This effect could be attributed to the compensation of donors by the activation or diffusion of acceptors, such as magnesium dopants or group-III vacancies, in the pn-junction space-charge region. The results are consistent with the observed reduction in optical power since deep level acceptors can also act as non-radiative recombination centers.
A plasma amplifier to combine multiple beams at NIF
Authors: Kirkwood R. K. , Turnbull D. P. , Chapman T. , Wilks S. C. , Rosen M. D. , London R. A. , Pickworth L. A. , Colaitis A. , Dunlop W. H. , Poole P. , Moody J. D. , Strozzi D. J. , Michel P. A. , Divol L. , Landen O. L. , MacGowan B. J. , Van Wonterghem B. M. , Fournier K. B. , Blue B. E.
Published: March 2018

Combining laser beams in a plasma is enabled by seeded stimulated Brillouin scattering which allows cross-beam energy transfer (CBET) to occur and re-distributes the energy between beams that cross with different incident angles and small differences in wavelength [Kirkwood et al. Phys. Plasmas 4, 1800 (1997)]. Indirect-drive implosions at the National Ignition Facility (NIF) [Haynam et al. Appl. Opt. 46, 3276–3303 (2007)] have controlled drive symmetry by using plasma amplifiers to transfer energy between beams [Kirkwood et al., Plasma Phys. Controlled Fusion 55, 103001 (2013); Lindl et al., Phys. Plasmas 21, 020501 (2014); and Hurricane et al. Nature 506, 343–348 (2014)]. In this work, we show that the existing models are well enough validated by experiments to allow a design of a plasma beam combiner that, once optimized, is expected to produce a pulse of light in a single beam with the energy greatly enhanced over existing sources. The scheme combines up to 61 NIF beams with 120 kJ of available energy into a single f/20 beam with a 1 ns pulse duration and a 351 nm wavelength by both resonant and off-resonance CBET. Initial experiments are also described that have already succeeded in producing a 4 kJ, 1 ns pulse in a single beam by combination of up to eight incident pump beams containing <1.1 kJ/beam, which are maintained near resonance for CBET in a plasma that is formed by 60 pre-heating beams [Kirkwood et al., Nat. Phys. 14, 80 (2018)].
Vibrational sum-frequency generation spectroscopy of lipid bilayers at repetition rates up to 100 kHz
Authors: Yesudas Freeda , Mero Mark , Kneipp Janina , Heiner Zsuzsanna
Published: March 2018

Broadband vibrational sum-frequency generation (BB-VSFG) spectroscopy has become a well-established surface analytical tool capable of identifying the orientation and structure of molecular layers. A straightforward way to boost the sensitivity of the technique could be to increase the laser repetition rate beyond that of standard BB-VSFG spectrometers, which rely on Ti:sapphire lasers operating at repetition rates of 1-5 kHz. Nevertheless, possible thermally induced artifacts in the vibrational spectra due to higher laser average powers are unexplored. Here, we discuss laser power induced temperature accumulation effects that distort the BB-VSFG spectra of 1,2-diacyl-sn-glycero-3-phosphocholine at an interface between two transparent phases at repetition rates of 5, 10, 50, and 100 kHz at constant pulse energy. No heat-induced distortions were found in the spectra, suggesting that the increase in the laser repetition rate provides a feasible route to an improved signal-to-noise ratio or shorter data acquisition times in BB-VSFG spectroscopy for thin films on transparent substrates. The results have implications for future BB-VSFG spectrometers pushing the detection limit for molecular layers with low surface coverage.
The effects of secondary emission on the sheath structure in an electrostatic dusty plasma containing energetic electrons and charged nanoparticles
Authors: Jalilpour P. , Foroutan G.
Published: March 2018

Multi-fluid numerical simulations are utilized to explore the effects of secondary emission by nanosize dust particles on the structure of a dusty plasma sheath in the presence of a beam of fast, mono-energetic electrons. It was found that the sheath dynamics depends strongly on the magnitude of the secondary emission yield δm. For δm smaller than unity, the secondary emission is weak, and the sheath width always increases with increasing beam flux, such that it experiences a sharp transition from the regime of thin sheath to the regime of thick sheath, at a given beam flux. For δm larger than unity, the secondary emission dominates the dust dynamics, and the sheath width always decreases with increasing beam flux. The sheath thickness decreases very quickly with the secondary emission yield, but increases with Em, the characteristic energy corresponding to the maximum secondary emission. As δm is increased, the absolute dust charge and hence the accelerating ion drag force are reduced. Then, the dust is decelerated and as a result the dust number density is enhanced. Increasing the dust radius and/or the dust number density leads to an enhanced secondary emission effect and thus to a narrower sheath width.
Implications of tristability in pattern-forming ecosystems
Authors: Zelnik Yuval R. , Gandhi Punit , Knobloch Edgar , Meron Ehud
Published: March 2018

Many ecosystems show both self-organized spatial patterns and multistability of possible states. The combination of these two phenomena in different forms has a significant impact on the behavior of ecosystems in changing environments. One notable case is connected to tristability of two distinct uniform states together with patterned states, which has recently been found in model studies of dryland ecosystems. Using a simple model, we determine the extent of tristability in parameter space, explore its effects on the system dynamics, and consider its implications for state transitions or regime shifts. We analyze the bifurcation structure of model solutions that describe uniform states, periodic patterns, and hybrid states between the former two. We map out the parameter space where these states exist, and note how the different states interact with each other. We further focus on two special implications with ecological significance, breakdown of the snaking range and complex fronts. We find that the organization of the hybrid states within a homoclinic snaking structure breaks down as it meets a Maxwell point where simple fronts are stationary. We also discover a new series of complex fronts between the uniform states, each with its own velocity. We conclude with a brief discussion of the significance of these findings for the dynamics of regime shifts and their potential control.
New Formulation for the Viscosity of n-Butane
Authors: Herrmann Sebastian , Vogel Eckhard
Published: March 2018

A new viscosity formulation for n-butane, based on the residual quantity concept, uses the reference equation of state by Bücker and Wagner [J. Phys. Chem. Ref. Data 35, 929 (2006)] and is valid in the fluid region from the triple point to 650 K and to 100 MPa. The contributions for the zero-density viscosity and for the initial-density dependence were separately developed, whereas those for the critical enhancement and for the higher-density terms were pretreated. All contributions were given as a function of the reciprocal reduced temperature τ, while the last two contributions were correlated as a function of τ and of the reduced density δ. The different contributions were based on specific primary data sets, whose evaluation and choice were discussed in detail. The final formulation incorporates 13 coefficients derived employing a state-of-the-art linear optimization algorithm. The viscosity at low pressures p ≤ 0.2 MPa is described with an expanded uncertainty of 0.5% (coverage factor k = 2) for temperatures 293 ≤ T/K ≤ 626. The expanded uncertainty in the vapor phase at subcritical temperatures T ≥ 298 K as well as in the supercritical thermodynamic region T ≤ 448 K at pressures p ≤ 30 MPa is estimated to be 1.5%. It is raised to 4.0% in regions where only less reliable primary data sets are available and to 6.0% in ranges without any primary data, but in which the equation of state is valid. A weakness of the reference equation of state in the near-critical region prevents estimation of the expanded uncertainty in this region. Viscosity tables for the new formulation are presented in Appendix B for the single-phase region, for the vapor–liquid phase boundary, and for the near-critical region.
Filtering peripheral high temperature electrons in a cylindrical rf-driven plasmas by an axisymmetric radial magnetic field
Authors: Akahoshi Hikaru , Takahashi Kazunori , Ando Akira
Published: March 2018

High temperature electrons generated near a radial wall of a cylindrical source tube in a radiofrequency (rf) inductively-coupled plasma is filtered by an axisymmetric radial magnetic field formed near the source exit by locating annular permanent magnets, where the axial magnetic field strength in the radially central region is fairly uniform inside the source tube and is close to zero near the source exit. The source is operated at 3 mTorr in argon and the rf antenna is powered by a 13.56 MHz and 400 W rf generator. Measurement of electron energy probability functions shows the presence of the peripheral high temperature electrons inside the source, while the temperature of the peripheral electrons downstream of the source is observed to be reduced.
Band gap characteristics of radial wave in a two-dimensional cylindrical shell with radial and circumferential periodicities
Authors: An Shuowei , Shu Haisheng , Liang Shanjun , Shi Xiaona , Zhao Lei
Published: March 2018

A two-dimensional cylindrical shell (2DCS) structure with radial and circumferential periodicities is proposed in this paper. The band gap characteristics of radial wave propagating radically from the inner circle of the structure are investigated numerically. According to the calculation and discussion of wave transmission behavior, radial wave in the structure is found to show distinct attenuation in certain frequency region, i.e. wave band gap. The internal mechanism of the band gap is then investigated and the Bragg scattering effect is illustrated. Furthermore, the detailed behaviors of radial wave within the band gap are studied, especially for the transmission peaks. Special localization phenomenon is observed where the mechanical energy localizes strongly in a certain circle of scatterers. Consistency is then found by comparing these localization modes of the whole 2DCS with those of corresponding single scatterers, which indicates that the localization phenomenon is essentially resulted from the local resonance behavior of certain scatterers.
High fruit sets in a rewardless orchid: a case study of obligate agamospermy in Habenaria
Authors: Zhang Wenliu , Gao Jiangyun
Published: March 2018

Low fruit set and pollination limitation are common characteristics of non-autogamous orchids, especially in rewardless species. The flowers of many Habenaria species are often characterised by long spurs and are mostly pollinated by long-tongued hawkmoths or butterflies. Unlike the flowers of other Habenaria species, the flowers of Habenaria malintana (Blanco) Merr. have very short spurs with no nectar or scent; however, this species is able to maintain high fecundity in south-west China. Breeding system experiments suggested that H. malintana is an obligate agamospermous orchid. Seed set did not need to be triggered by pollen grain deposition on stigmas, and ~100% fruit set was found in different populations and years. In pollen germination experiments, hand-deposited pollen failed to germinate on stigmas. The flowers of H. malintana failed to attract any pollinators, as we did not observe any floral visitors, and no pollinia removal or deposition occurred in both 2013 and 2014 at two study sites. These results strongly suggested that H. malintana has completely abandoned sexual reproduction and has adopted obligate agamospermy to achieve high reproductive output. We suggest that this strategy may have evolved to provide reproductive assurance and reduce the cost of flowers in response to unreliable pollinator service.
Short-term effect of FSH on gene expression in bovine granulosa cells in vitro
Authors: Nivet Anne-Laure , Dufort Isabelle , Gilbert Isabelle , Sirard Marc-André
Published: March 2018

In reproduction, FSH is one of the most important hormones, especially in females, because it controls the number of follicles and the rate of follicular growth. Although several studies have examined the follicular response at the transcriptome level, it is difficult to obtain a clear and complete picture of the genes responding to an increase in FSH in an in vivo context because follicles undergo rapid morphological and physical changes during their growth. To help define the transcriptome downstream response to FSH, an in vitro model was used in the present study to observe the short-term (4 h) cellular response. Gene expression analysis highlighted a set of novel transcripts that had not been reported previously as being part of the FSH response. Moreover, the results of the present study indicate that the epithelial to mesenchymal transition pathway is inhibited by short-term FSH stimuli, maintaining follicles in a growth phase and preventing differentiation. Modulating gene expression in vitro has physiological limitations, but it can help assess the potential downstream response and begin the mapping of the granulosa cell transcriptome in relation to FSH. This information is a key feature to help discriminate between the effects of FSH and LH, or to elucidate the overlapping of insulin-like growth factor 1 and FSH in the granulosa mitogenic response.
Ecological responses of Stipa steppe in Inner Mongolia to experimentally increased temperature and precipitation. 2. Plant species diversity and sward characteristics
Authors: Wan Zhiqiang , Yan Yulong , Chen Yali , Gu Rui , Gao Qingzhu , Yang Jie
Published: March 2018

The responses of plant community diversity and sward characteristics to temperature and moisture changes on the Stipa steppe in Inner Mongolia were investigated in the growing season from 2013 to 2015. Warming significantly (P < 0.05) increased biomass and density. Highest biomass and density were achieved with warming and precipitation combined, whereas increased precipitation alone had no significant effect. Warming increased the Shannon–Weiner diversity index, which was significantly correlated with both air temperature (R2 = 0.45, P < 0.05) and soil temperature (R2 = 0.255 P < 0.05), and it was further increased by the combination of warming and increased precipitation. The Simpson index, an alternative measure of diversity that is not as sensitive to species richness, was less responsive to either warming or increased precipitation. Overall, warming had a more substantial effect than increased precipitation on the characteristics of the Stipa steppe community. However, its impact was complex, with significant variance among the 3 years of the study. The impacts of future changes in precipitation are also likely to be complex and warrant further research.
Stabilized supralinear network can give rise to bistable, oscillatory, and persistent activity
Authors: Kraynyukova Nataliya , Tchumatchenko Tatjana
Published: March 2018

Significance

Many fundamental neural computations from normalization to rhythm generation emerge from the same cortical hardware, but they often require dedicated models to explain each phenomenon. Recently, the stabilized supralinear network (SSN) model has been used to explain a variety of nonlinear integration phenomena such as normalization, surround suppression, and contrast invariance. However, cortical circuits are also capable of implementing working memory and oscillations which are often associated with distinct model classes. Here, we show that the SSN motif can serve as a universal circuit model that is sufficient to support not only stimulus integration phenomena but also persistent states, self-sustained network-wide oscillations along with two coexisting stable states that have been linked with working memory.
Is science really facing a reproducibility crisis, and do we need it to?
Authors: Fanelli Daniele
Published: March 2018

Efforts to improve the reproducibility and integrity of science are typically justified by a narrative of crisis, according to which most published results are unreliable due to growing problems with research and publication practices. This article provides an overview of recent evidence suggesting that this narrative is mistaken, and argues that a narrative of epochal changes and empowerment of scientists would be more accurate, inspiring, and compelling.
Scientific progress despite irreproducibility: A seeming paradox
Authors: Shiffrin Richard M. , Börner Katy , Stigler Stephen M.
Published: March 2018

It appears paradoxical that science is producing outstanding new results and theories at a rapid rate at the same time that researchers are identifying serious problems in the practice of science that cause many reports to be irreproducible and invalid. Certainly, the practice of science needs to be improved, and scientists are now pursuing this goal. However, in this perspective, we argue that this seeming paradox is not new, has always been part of the way science works, and likely will remain so. We first introduce the paradox. We then review a wide range of challenges that appear to make scientific success difficult. Next, we describe the factors that make science work—in the past, present, and presumably also in the future. We then suggest that remedies for the present practice of science need to be applied selectively so as not to slow progress and illustrate with a few examples. We conclude with arguments that communication of science needs to emphasize not just problems but the enormous successes and benefits that science has brought and is now bringing to all elements of modern society.
Structural insights into the sequence-specific recognition of Piwi by
Drosophila
Papi
Authors: Zhang Yuhan , Liu Weiwei , Li Ronghong , Gu Jiaqi , Wu Ping , Peng Chao , Ma Jinbiao , Wu Ligang , Yu Yang , Huang Ying
Published: March 2018

Significance

In this study, we identified the direct interaction region between
Drosophila
Piwi and Papi. We further determined the crystal structures of Papi-eTud in the apo form, in complex with unmethylated Piwi peptide, and in complex with symmetrically dimethylated Piwi peptide at arginine-10, which demonstrated that Papi interacts with an RGRRR motif on the N terminus of Piwi in a sequence-specific manner both in vitro and in vivo. This recognition sequence, which determines the specificity of Papi–Piwi interactions, is different from all previously reported (G/A)R repeats. Our studies provide mechanistic insights into the important role of Papi–Piwi interactions in the 3′ end-trimming process of PIWI-interacting RNA biogenesis and facilitate the identification of new PIWI-interacting partners of Tudor domain-containing proteins.