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Imran Hanif, Osmane Camara, Matheus Araújo Tunes, Robert William Harrison, Graeme Greaves, Stephen E Donnelly, Jonathan A Hinks
The miniaturization of technology increasingly requires the development of both new structures as well as novel techniques for their manufacture and modification. Semiconductor nanowires (NWs) are a prime example of this and as such have been the subject of intense scientific research for applications ranging from microelectronics to nano-electromechanical devices. Ion irradiation has long been a key processing step for semiconductors and the natural extension of this technique to the modification of semiconductor NWs has led to the discovery of ion-beam-induced deformation effects...
May 21, 2018: Nanotechnology
Luca Giannessi, Enrico Allaria, Kevin C Prince, Carlo Callegari, Giuseppe Sansone, Kiyoshi Ueda, Toru Morishita, Chien Nan Liu, Alexei N Grum-Grzhimailo, Elena V Gryzlova, Nicolas Douguet, Klaus Bartschat
The seeded Free-Electron Laser (FEL) FERMI is the first source of short-wavelength light possessing the full coherence of optical lasers, together with the extreme power available from FELs. FERMI provides longitudinally coherent radiation in the Extreme Ultraviolet and soft x-ray spectral regions, and therefore opens up wide new fields of investigation in physics. We first propose experiments exploiting this property to provide coherent control of the photoionization of neon and helium, carry out numerical calculations to find optimum experimental parameters, and then describe how these experiments may be realized...
May 17, 2018: Scientific Reports
T Inaniwa, N Kanematsu
The microdosimetric kinetic (MK) model underestimates the cell-survival fractions for high linear energy transfer (LET) and high dose irradiations. To address the issue, some researchers previously extended the MK model to the stochastic microdosimetric kinetic (SMK) model. In the SMK model, the radiation induced cell-survival fractions were estimated from the specific energies z d and z n absorbed by a microscopic subnuclear structure domain and a cell nucleus, respectively. By taking the stochastic nature of z n as well as that of z d into account, the SMK model could reproduce the measured cell-survival fractions for radiations with wide LET and dose ranges...
May 4, 2018: Physics in Medicine and Biology
Jen-Iu Lo, Sheng-Lung Chou, Yu-Chain Peng, Hsiao-Chi Lu, J F Ogilvie, Bing-Ming Cheng
Irradiation of O2 dispersed in solid Ne with ultraviolet light produced infrared absorption lines of O3 and emission lines from atomic O (1D2 → 3P1,2), molecular O2 (A' 3Δu → X 3Σg) and radical OH (A 2Σ+ → X 2ΠI) in the visible and near-ultraviolet regions. The threshold wavelength for the formation of O3 was determined to be 200 ± 4 nm, corresponding to energy 6.20 ± 0.12 eV, which is hence the threshold for dissociation of O2. The thresholds of emission from excited O (1D2), O2 (A' 3Δu) and OH (A 2Σ+) were all observed to be 200 ± 4 nm, the same as for the formation of O3 in this photochemical system...
May 2, 2018: Physical Chemistry Chemical Physics: PCCP
R Kronholm, T Kalvas, H Koivisto, O Tarvainen
The results of optical emission spectroscopy experiments probing the cold electron population of a 14 GHz Electron Cyclotron Resonance Ion Source (ECRIS) are reported. The study has been conducted with a high resolution spectrometer and data acquisition setup developed specifically for the diagnostics of weak emission line characteristic to ECRIS plasmas. The optical emission lines of low charge state ions and neutral atoms of neon have been measured and analyzed with the line-ratio method. The aforementioned electron population temperature of the cold electron population (Te < 100 eV) is determined for Maxwell-Boltzmann and Druyvesteyn energy distributions to demonstrate the applicability of the method...
April 2018: Review of Scientific Instruments
Junwen Zou, Sean D S Gordon, Silvia Tanteri, Andreas Osterwalder
Stereodynamics experiments of Ne(3 P2 ) reacting with Ar, Kr, Xe, and N2 leading to Penning and associative ionization have been performed in a crossed molecular beam apparatus. A curved magnetic hexapole was used to state-select and polarize Ne(3 P2 ) atoms which were then oriented in a rotatable magnetic field and crossed with a beam of Ar, Kr, Xe, or N2 . The ratio of associative to Penning ionization was recorded as a function of the magnetic field direction for collision energies between 320 cm-1 and 500 cm-1 ...
April 28, 2018: Journal of Chemical Physics
Moritz Ueffing, Simon Reiger, Martin Kaumanns, Vladimir Pervak, Michael Trubetskov, Thomas Nubbemeyer, Ferenc Krausz
We present an efficient method for compressing sub-picosecond pulses at 200 W average power with 2 mJ pulse energy in a multipass cell filled with different gases. We demonstrate spectral broadening by more than a factor of five using neon, argon, and nitrogen as nonlinear media. The 210 fs input pulses are compressed down to 37 fs and 35 GW peak power with a beam quality factor of 1.3×1.5 at a power throughput of >93%. This concept represents an excellent alternative to hollow-core fiber-based compression schemes and optical parametric amplifiers (OPAs)...
May 1, 2018: Optics Letters
Alejandro Gutiérrez-Quintanilla, Michèle Chevalier, Rasa Platakyte, Justinas Ceponkus, Germán A Rojas-Lorenzo, Claudine Crépin
The chelated enol isomer of 2-chloromalonaldehyde (2-ClMA) is experimentally characterized for the first time by IR and Raman spectroscopies. The spectra are obtained by trapping the molecule in cryogenic matrices and analyzed with the assistance of theoretical calculations. Experiments were performed in argon, neon and para-hydrogen matrices. The results highlight puzzling matrix effects, beyond site effects, which are interpreted as due to a tunneling splitting of the vibrational levels related to the proton transfer along the internal hydrogen bond (IHB)...
April 27, 2018: Physical Chemistry Chemical Physics: PCCP
Pankaj Bhowmik, Evan Ellison, Brittany Polley, Venkatesh Bollina, Manoj Kulkarni, Kaveh Ghanbarnia, Halim Song, Caixia Gao, Daniel F Voytas, Sateesh Kagale
CRISPR/Cas9 genome editing is a transformative technology that will facilitate the development of crops to meet future demands. However, application of gene editing is hindered by the long life cycle of many crop species and because desired genotypes generally require multiple generations to achieve. Single-celled microspores are haploid cells that can develop into double haploid plants and have been widely used as a breeding tool to generate homozygous plants within a generation. In this study, we combined the CRISPR/Cas9 system with microspore technology and developed an optimized haploid mutagenesis system to induce genetic modifications in the wheat genome...
April 25, 2018: Scientific Reports
Christof Gaiser, Bernd Fellmuth
With dielectric-constant gas thermometry, the molar polarizability of helium, neon, and argon has been determined with relative standard uncertainties of about 2 parts per million. A series of isotherms measured with the three noble gases and two different experimental setups led to this unprecedented level of uncertainty. These data are crucial for scientists in the field of gas metrology, working on pressure and temperature standards. Furthermore, with the new benchmark values for neon and argon, theoretical calculations, today about 3 orders of magnitude larger in uncertainty, can be checked and improved...
March 23, 2018: Physical Review Letters
Josué J López, Antonio Ambrosio, Siyuan Dai, Chuong Huynh, David C Bell, Xiao Lin, Nicholas Rivera, Shengxi Huang, Qiong Ma, Soeren Eyhusen, Ido E Kaminer, Kenji Watanabe, Takashi Taniguchi, Jing Kong, Dimitri N Basov, Pablo Jarillo-Herrero, Marin Soljačić
The controlled nanoscale patterning of 2D materials is a promising approach for engineering the optoelectronic, thermal, and mechanical properties of these materials to achieve novel functionalities and devices. Herein, high-resolution patterning of hexagonal boron nitride (h-BN) is demonstrated via both helium and neon ion beams and an optimal dosage range for both ions that serve as a baseline for insulating 2D materials is identified. Through this nanofabrication approach, a grating with a 35 nm pitch, individual structure sizes down to 20 nm, and additional nanostructures created by patterning crystal step edges are demonstrated...
April 24, 2018: Small
Luisa Prasetyo, Quang K Loi, Shiliang Johnathan Tan, D D Do, D Nicholson
We have carried out an extensive grand canonical Monte Carlo simulation to investigate the adsorption of neon and xenon on graphite. The adsorbate collision diameters of neon and xenon are smaller and greater respectively, than the commensurate graphite lattice spacing λ=3×3R300 of 0.426 nm. Simulated isotherms and isosteric heats were obtained using a graphite model that has been shown to describe successfully the adsorbate transitions for krypton, methane and nitrogen by Prasetyo et al. (2017), which have collision diameters close to λ...
April 10, 2018: Journal of Colloid and Interface Science
Lester Andrews, Han-Gook Cho, Zongtang Fang, Monica Vasiliu, David A Dixon
Laser ablation of tungsten metal provides W atoms which react with phosphine and arsine during condensation in excess argon and neon, leading to major new infrared (IR) absorptions. Annealing, UV irradiation, and deuterium substitution experiments coupled with electronic structure calculations at the density functional theory level led to the assignment of the observed IR absorptions to the E≡WH3 and HE═WH2 molecules for E = P and As. The potential energy surfaces for hydrogen transfer from PH3 to the W were calculated at the coupled-cluster CCSD(T)/complete basis set level...
April 16, 2018: Inorganic Chemistry
Paloma A Matis, Jennifer M Donelson, Stephen Bush, Rebecca J Fox, David J Booth
Climate change is expected to pose a significant risk to species that exhibit strong behavioural preferences for specific habitat types, with generalist species assumed to be less vulnerable. In this study, we conducted habitat choice experiments to determine how water temperature influences habitat preference for three common species of coral reef damselfish (Pomacentridae) that differ in their levels of habitat specialisation. The lemon damselfish Pomacentrus moluccensis, a habitat specialist, consistently selected complex coral habitat across all temperature treatments (selected based on local average seasonal temperatures naturally experienced in situ: ambient winter 22°C; ambient summer 28°C; and elevated 31°C)...
April 15, 2018: Global Change Biology
Christopher J Fassnidge, Elliot D Freeman
Some people hear what they see: car indicator lights, flashing neon shop signs, and people's movements as they walk may all trigger an auditory sensation, which we call the visual-evoked auditory response (vEAR or 'visual ear'). We have conducted the first large-scale online survey (N > 4000) of this little-known phenomenon. We analysed the prevalence of vEAR, what induces it, and what other traits are associated with it. We assessed prevalence by asking whether respondents had previously experienced vEAR...
March 9, 2018: Cortex; a Journal Devoted to the Study of the Nervous System and Behavior
Idoia Berges, Jesus Bermúdez, Arantza Illarramendi
BACKGROUND: Single-Subject Design is used in several areas such as education and biomedicine. However, no suited formal vocabulary exists for annotating the detailed configuration and the results of this type of research studies with the appropriate granularity for looking for information about them. Therefore, the search for those study designs relies heavily on a syntactical search on the abstract, keywords or full text of the publications about the study, which entails some limitations...
February 2018: Methods of Information in Medicine
Luis M Sesé
The problem of the equilibrium triplet structures in fluids with quantum behavior is discussed. Theoretical questions of interest to the real space structures are addressed by studying the three types of structures that can be determined via path integrals (instantaneous, centroid, and total thermalized-continuous linear response). The cases of liquid para-H2 and liquid neon on their crystallization lines are examined with path-integral Monte Carlo simulations, the focus being on the instantaneous and the centroid triplet functions (equilateral and isosceles configurations)...
March 14, 2018: Journal of Chemical Physics
Michael M Linden, J Philipp Wagner, Bastian Bernhardt, Marcus A Bartlett, Wesley D Allen, Peter R Schreiner
Disentangling internal and external effects is a key requirement for understanding conformational tunneling processes. Here we report the s- trans/ s- cis tunneling rotamerization of carbonic acid monomethyl ester (1) under matrix isolation conditions and make comparisons to its parent carbonic acid (3). The observed tunneling rate of 1 is temperature-independent in the 3-20 K range and accelerates when using argon instead of neon as the matrix material. The methyl group increases the effective half life (τeff ) of the energetically disfavored s- trans-conformer from 3-5 h for 3 to 11-13 h for 1...
April 5, 2018: Journal of Physical Chemistry Letters
Javier Vicente-Tejedor, Miguel Marchena, Laura Ramírez, Diego García-Ayuso, Violeta Gómez-Vicente, Celia Sánchez-Ramos, Pedro de la Villa, Francisco Germain
Light causes damage to the retina (phototoxicity) and decreases photoreceptor responses to light. The most harmful component of visible light is the blue wavelength (400-500 nm). Different filters have been tested, but so far all of them allow passing a lot of this wavelength (70%). The aim of this work has been to prove that a filter that removes 94% of the blue component may protect the function and morphology of the retina significantly. Three experimental groups were designed. The first group was unexposed to light, the second one was exposed and the third one was exposed and protected by a blue-blocking filter...
2018: PloS One
Vikram Sundar, David Gelbwaser-Klimovsky, Alán Aspuru-Guzik
Modeling nuclear quantum effects is required for accurate molecular dynamics (MD) simulations of molecules. The community has paid special attention to water and other biomolecules that show hydrogen bonding. Standard methods of modeling nuclear quantum effects like Ring Polymer Molecular Dynamics (RPMD) are computationally costlier than running classical trajectories. A force-field functor (FFF) is an alternative method that computes an effective force field that replicates quantum properties of the original force field...
April 5, 2018: Journal of Physical Chemistry Letters
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