bluuebunny/crossref_metadata_2025 huggingface dataset:
Luminescence of SiO2 and GeO2 crystals with rutile structure. Comparison with α-quartz crystals and relevant glasses (Review Article)
Authors: Trukhin A. N.
Published: September 2016

Luminescence properties of SiO2 in different structural states are compared. Similar comparison is made for GeO2. Rutile and α-quartz structures as well as glassy state of these materials are considered. Main results are that for α-quartz crystals the luminescence of self-trapped exciton is the general phenomenon that is absent in the crystal with rutile structure. In rutile structured SiO2 (stishovite) and GeO2 (argutite) the main luminescence is due to a host material defect existing in as-received (as-grown) samples. The defect luminescence possesses specific two bands, one of which has a slow decay (for SiO2 in the blue and for GeO2, in green range) and another, a fast ultraviolet (UV) band (4.75 eV in SiO2 and at 3 eV in GeO2). In silica and germania glasses, the luminescence of self-trapped exciton coexists with defect luminescence. The latter also contains two bands: one in the visible range and another in the UV range. The defect luminescence of glasses was studied in details during last 60–70 years and is ascribed to oxygen deficient defects. Analogous defect luminescence in the corresponding pure nonirradiated crystals with α-quartz structure is absent. Only irradiation of a α-quartz crystal by energetic electron beam, γ-rays and neutrons provides defect luminescence analogous to glasses and crystals with rutile structure. Therefore, in glassy state the structure containing tetrahedron motifs is responsible for existence of self-trapped excitons and defects in octahedral motifs are responsible for oxygen deficient defects.
The specifics of radiative annihilation of self-trapped excitons in a KI–Tl crystal under low-temperature deformation
Authors: Shunkeyev K. Sh. , Zhanturina N. N. , Aimaganbetova Z. K. , Barmina A. A. , Myasnikova L. N. , Sagymbaeva Sh. Zh. , Sergeyev D. M.
Published: September 2016

The effect of low-temperature uniaxial deformation on the self-trapping-limited mean free path of excitons in a KI–Tl crystal was revealed from x-ray luminescence spectra. The analysis of the dependence of the intensity ratio of the Tl-center emission (2.85 eV) and the luminescence of self-trapped excitons (π-component; 3.3 eV) on the extent of low-temperature deformation showed that in the KI–Tl crystal (3 × 10−3 mol. %) the self-trapping-limited mean free path of excitons is comparable with the distance between Tl atoms (20–27)a under a deformation ε = 2%. As the compression increases to ε ≥ 2%–5%, the mean free path drops to (27-5.35)a. The results of modeling based on the continuum approximation showed that with increasing temperature and the degree of low-temperature deformation the height of the potential barrier for the exciton self-trapping drops, which is consistent with the reduction of the mean free path of excitons in the KI–Tl crystal.
X-ray backlighting of imploding aluminium liners on PTS facility
Authors: Yang Qingguo , Liu Dongbing , Mu Jian , Huang Xianbin , Dan Jiakun , Xie Xudong , Deng Wu , Feng Shuping , Wang Meng , Ye Yan , Peng Qixian , Li Zeren
Published: September 2016

The x-ray backlighting systems, including a 1.865 keV (Si Heα line) spherically bent crystal imaging system and an ∼8.3 keV (Cu Heα line) point-projection imaging system, newly fielded on the Primary Test Stand facility are introduced and its preliminary experimental results in radiography of the aluminium (Al) liners with seeded sinusoidal perturbations are presented. The x-ray backlighter source is created using a 1 TW, 1 kJ Nd: glass high power laser, kilo-joule laser system, recently constructed at China Academy of Engineering Physics. The ablation melt and instability of the imploding Al liner outer edge under the driving current of ∼7.5 MA are successfully observed using these two backlighting systems, respectively.
A high spatio-temporal resolution optical pyrometer at the ORION laser facility
Authors: Floyd Emma , Gumbrell Edward T. , Fyrth Jim , Luis James D. , Skidmore Jonathan W. , Patankar Siddharth , Giltrap Samuel , Smith Roland
Published: September 2016

A streaked pyrometer has been designed to measure the temperature of ≈100 μm diameter heated targets in the warm dense matter region. The diagnostic has picosecond time resolution. Spatial resolution is limited by the streak camera to 4 μm in one dimension; the imaging system has superior resolution of 1 μm. High light collection efficiency means that the diagnostic can transmit a measurable quantity of thermal emission at temperatures as low as 1 eV to the detector. This is achieved through the use of an f/1.4 objective, and a minimum number of reflecting and refracting surfaces to relay the image over 8 m with no vignetting over a 0.4 mm field of view with 12.5× magnification. All the system optics are highly corrected, to allow imaging with minimal aberrations over a broad spectral range. The detector is a highly sensitive Axis Photonique streak camera with a P820PSU streak tube. For the first time, two of these cameras have been absolutely calibrated at 1 ns and 2 ns sweep speeds under full operational conditions and over 8 spectral bands between 425 nm and 650 nm using a high-stability picosecond white light source. Over this range the cameras had a response which varied between 47 ± 8 and 14 ± 4 photons/count. The calibration of the optical imaging system makes absolute temperature measurements possible. Color temperature measurements are also possible due to the wide spectral range over which the system is calibrated; two different spectral bands can be imaged onto different parts of the photocathode of the same streak camera.
Characterization of x-ray framing cameras for the National Ignition Facility using single photon pulse height analysis
Authors: Holder J. P. , Benedetti L. R. , Bradley D. K.
Published: September 2016

Single hit pulse height analysis is applied to National Ignition Facility x-ray framing cameras to quantify gain and gain variation in a single micro-channel plate-based instrument. This method allows the separation of gain from detectability in these photon-detecting devices. While pulse heights measured by standard-DC calibration methods follow the expected exponential distribution at the limit of a compound-Poisson process, gain-gated pulse heights follow a more complex distribution that may be approximated as a weighted sum of a few exponentials. We can reproduce this behavior with a simple statistical-sampling model.
Equilibrium fluctuations of liquid state static properties in a subvolume by molecular dynamics
Authors: Heyes D. M. , Dini D. , Smith E. R.
Published: September 2016

System property fluctuations increasingly dominate a physical process as the sampling volume decreases. The purpose of this work is to explore how the fluctuation statistics of various thermodynamic properties depend on the sampling volume, using molecular dynamics (MD) simulations. First an examination of various expressions for calculating the bulk pressure of a bulk liquid is made, which includes a decomposition of the virial expression into two terms, one of which is the Method of Planes (MOP) applied to the faces of the cubic simulation cell. Then an analysis is made of the fluctuations of local density, temperature, pressure, and shear stress as a function of sampling volume (SV). Cubic and spherical shaped SVs were used within a spatially homogeneous LJ liquid at a state point along the melting curve. It is shown that the MD-generated probability distribution functions (PDFs) of all of these properties are to a good approximation Gaussian even for SV containing only a few molecules (∼10), with the variances being inversely proportional to the SV volume, Ω. For small subvolumes the shear stress PDF fits better to a Gaussian than the pressure PDF. A new stochastic sampling technique to implement the volume averaging definition of the pressure tensor is presented, which is employed for cubic, spherical, thin cubic, and spherical shell SV. This method is more efficient for less symmetric SV shapes.
Crystal nucleation as the ordering of multiple order parameters
Authors: Russo John , Tanaka Hajime
Published: September 2016

Nucleation is an activated process in which the system has to overcome a free energy barrier in order for a first-order phase transition between the metastable and the stable phases to take place. In the liquid-to-solid transition, the process occurs between phases of different symmetry, and it is thus inherently a multi-dimensional process, in which all symmetries are broken at the transition. In this Focus Article, we consider some recent studies which highlight the multi-dimensional nature of the nucleation process. Even for a single-component system, the formation of solid crystals from the metastable melt involves fluctuations of two (or more) order parameters, often associated with the decoupling of positional and orientational symmetry breaking. In other words, we need at least two order parameters to describe the free-energy of a system including its liquid and crystalline states. This decoupling occurs naturally for asymmetric particles or directional interactions, focusing here on the case of water, but we will show that it also affects spherically symmetric interacting particles, such as the hard-sphere system. We will show how the treatment of nucleation as a multi-dimensional process has shed new light on the process of polymorph selection, on the effect of external fields on the nucleation process and on glass-forming ability.
Polarity dependent thermochemical E-model for describing time dependent dielectric breakdown in metal-oxide-semiconductor devices with hyper-thin gate dielectrics
Authors: McPherson J. W.
Published: September 2016

The Lorentz factor L, which is used for describing the local electric fields in hyper-thin (<3.0 nm) gate dielectrics, is found to be polarity dependent for an inversion and accumulation-mode testing of Metal-Oxide-Semiconductor Field Effect Transistors. L is strongly impacted by the dipole layers that are induced in the depletion regions in the poly and silicon-substrate electrodes. While time dependent dielectric breakdown (TDDB) results are much improved with the inversion-mode testing, the reason for this is due to a smaller Lorentz factor (thus smaller Eloc). In fact, when compared at the same local electric field Eloc, there is no difference in TDDB between the inversion and accumulation mode testing. Thus, when properly corrected for the depletion effects in the MOS electrodes, the Thermochemical E-Model becomes polarity dependent and describes well both the inversion and accumulation-mode TDDB testing of the hyper-thin gate dielectrics.
Ballistic effects on the copper precipitation and re-dissolution kinetics in an ion irradiated and thermally annealed Fe–Cu alloy
Authors: Xu Donghua , Certain Alicia , Lee Voigt Hyon-Jee , Allen Todd , Wirth Brian D.
Published: September 2016

Studies of solute precipitation and precipitate phase stability in nuclear structural materials under concurrent irradiation and heat often lead to contradictory results due to the complex nature of the phenomena which is far from well understood. Here, we present a comprehensive atomistically based continuum model for the copper precipitation and re-dissolution kinetics in an ion irradiated and thermally annealed Fe-0.78 at. % Cu alloy. Our model incorporates thermal and irradiation enhanced diffusion of atomic Cu, clustering of Cu into sub-nanometer and nanometer sized precipitates, thermal dissociation of the precipitates and, in particular, a cascade re-dissolution parameter that has been made available by recent molecular dynamics simulations. Our model suggests that the Cu precipitates may form, re-dissolve, or coarsen under different irradiation and thermal conditions depending on the competition between the thermal and the ballistic effects. The quantitative predictions of our model are compared with available experiments including limited atom probe tomography data acquired in this study. The work highlights the importance of combining thermal and ballistic effects in the understanding of phase stability in extreme nuclear environments.
Improving the accuracy of ground-state correlation energies within a plane-wave basis set: The electron-hole exchange kernel
Authors: Dixit Anant , Ángyán János G. , Rocca Dario
Published: September 2016

A new formalism was recently proposed to improve random phase approximation (RPA) correlation energies by including approximate exchange effects [B. Mussard et al., J. Chem. Theory Comput. 12, 2191 (2016)]. Within this framework, by keeping only the electron-hole contributions to the exchange kernel, two approximations can be obtained: An adiabatic connection analog of the second order screened exchange (AC-SOSEX) and an approximate electron-hole time-dependent Hartree-Fock (eh-TDHF). Here we show how this formalism is suitable for an efficient implementation within the plane-wave basis set. The response functions involved in the AC-SOSEX and eh-TDHF equations can indeed be compactly represented by an auxiliary basis set obtained from the diagonalization of an approximate dielectric matrix. Additionally, the explicit calculation of unoccupied states can be avoided by using density functional perturbation theory techniques and the matrix elements of dynamical response functions can be efficiently computed by applying the Lanczos algorithm. As shown by several applications to reaction energies and weakly bound dimers, the inclusion of the electron-hole kernel significantly improves the accuracy of ground-state correlation energies with respect to RPA and semi-local functionals.
Ionization potential optimized double-hybrid density functional approximations
Authors: Margraf Johannes T. , Verma Prakash , Bartlett Rodney J.
Published: September 2016

Double-hybrid density functional approximations (DH-DFAs) provide an accurate description of the electronic structure of molecules by semiempirically mixing density functional and wavefunction theory. In this paper, we investigate the properties of the potential used in such approximations. By using the optimized effective potential approach, the consistent Kohn-Sham (KS) potential for a double-hybrid functional (including the second-order perturbational contribution) can be generated. This potential is shown to provide an improved description of orbital energies as vertical ionization potentials (IPs), relative to the perturbation-free KS potential typically used. Based on this observation, we suggest that DH-DFAs should be constructed in such a way that the potential provides accurate orbital energies. As a proof of principle, the B2-PLYP functional is reparameterized to obtain the IP-optimized B2IP-PLYP functional, using a small set of vertical IPs and atomization energies as reference data. This functional is shown to outperform B2-PLYP in a wide range of benchmarks and is en par with the related B2GP-PLYP. In particular, it is shown to be the most reliable choice in electronically difficult and multireference cases.
In-situ surface and interface study of atomic oxygen modified carbon containing porous low-κ dielectric films for barrier layer applications
Authors: Bogan J. , Lundy R. , P. McCoy A. , O'Connor R. , Byrne C. , Walsh L. , Casey P. , Hughes G.
Published: September 2016

The surface treatment of ultralow-κ dielectric layers by exposure to atomic oxygen is presented as a potential mechanism to modify the chemical composition of the dielectric surface to facilitate copper diffusion barrier layer formation. High carbon content, low-κ dielectric films of varying porosity were exposed to atomic oxygen treatments at room temperature, and x-ray photoelectron spectroscopy studies reveal both the depletion of carbon and the incorporation of oxygen at the surface. Subsequent dynamic water contact angle measurements show that the chemically modified surfaces become more hydrophilic after treatment, suggesting that the substrates have become more “SiO2-like” at the near surface region. This treatment is shown to be thermally stable up to 400 °C. High resolution electron energy loss spectroscopy elemental profiles confirm the localised removal of carbon from the surface region. Manganese (≈1 nm) was subsequently deposited on the modified substrates and thermally annealed to form surface localized MnSiO3 based barrier layers. The energy-dispersive X-ray spectroscopy elemental maps show that the atomic oxygen treatments facilitate the formation of a continuous manganese silicate barrier within dense low-k films, but significant manganese diffusion is observed in the case of porous substrates, negatively impacting the formation of a discrete barrier layer. Ultimately, the atomic oxygen treatment proves effective in modifying the surface of non-porous dielectrics while continuing to facilitate barrier formation. However, in the case of high porosity films, diffusion of manganese into the bulk film remains a critical issue.
Delocalization of vortex in SmBa2Cu3O7−δ superconducting films with BaHfO3 nano-rods
Authors: Tsuchiya Yuji , Awaji Satoshi , Watanabe Kazuo , Miura Shun , Ichino Yusuke , Yoshida Yutaka , Matsumoto Kaname
Published: September 2016

Transport measurements revealed flux pinning properties and vortex phases in SmBa2Cu3O7−δ (Sm123) superconducting films with BaHfO3 nano-rods on LaAlO3 substrates. The films have large matching fields BΦ up to 9.9 T, nano-rod diameters of ∼6 nm, and a slight Tc degradation with Tc ∼ 91.8 K by using the low temperature growth technique. According to the transport results, a small critical exponent ∼4 indicates the presence of a Bose-glass phase in the films. Double peaks of the flux pinning force density are unexpectedly observed at high temperatures over 80 K, which is accompanied by steep drops of the crossover magnetic fields between the single vortex pinning and the collective pinning states. The drops are explained by the delocalization of the vortex where the vortex is pinned by many nano-rods in the single vortex pinning state. From the viewpoint of the vortex delocalization, we conclude that BΦ should be less than 11 T for applications at liquid nitrogen temperature.
4D x-ray phase contrast tomography for repeatable motion of biological samples
Authors: Hoshino Masato , Uesugi Kentaro , Yagi Naoto
Published: September 2016

X-ray phase contrast tomography based on a grating interferometer was applied to fast and dynamic measurements of biological samples. To achieve this, the scanning procedure in the tomographic scan was improved. A triangle-shaped voltage signal from a waveform generator to a Piezo stage was used for the fast phase stepping in the grating interferometer. In addition, an optical fiber coupled x-ray scientific CMOS camera was used to achieve fast and highly efficient image acquisitions. These optimizations made it possible to perform an x-ray phase contrast tomographic measurement within an 8 min scan with density resolution of 2.4 mg/cm3. A maximum volume size of 13 × 13 × 6 mm3 was obtained with a single tomographic measurement with a voxel size of 6.5 μm. The scanning procedure using the triangle wave was applied to four-dimensional measurements in which highly sensitive three-dimensional x-ray imaging and a time-resolved dynamic measurement of biological samples were combined. A fresh tendon in the tail of a rat was measured under a uniaxial stretching and releasing condition. To maintain the freshness of the sample during four-dimensional phase contrast tomography, the temperature of the bathing liquid of the sample was kept below 10° using a simple cooling system. The time-resolved deformation of the tendon and each fascicle was measured with a temporal resolution of 5.7 Hz. Evaluations of cross-sectional area size, length of the axis, and mass density in the fascicle during a stretching process provided a basis for quantitative analysis of the deformation of tendon fascicle.
Tuned polarity and enhanced optoelectronic performances of few-layer Nb0.125Re0.875Se2 flakes
Authors: Liu Sijie , Huang Le , Wu Kedi , Wei Zhongming , Huang Beiju , Meng Xiuqing , Tongay Sefaattin , Liu Jian , Li Jingbo , Chen Hongda
Published: September 2016

Both N-type and P-type semiconducting materials are essential in the integrated circuit and optoelectronic industry. Herein, the intrinsic P-type ReSe2 is converted to N-type by Nb-alloying. Despite the efficient carrier type conversion, we also measured the electric characteristics and photo-response of few-layer Nb0.125Re0.875Se2 based field-effect transistors under different lasers. The devices showed comparable mobility with pristine ReSe2 (on the order of 0.1 cm2 V−1 s−1). Moreover, such Nb0.125Re0.875Se2 shows high sensitivity to different visible lasers and has a light-improved mobility up to 1 cm2 V−1 s−1. The highest photoresponsivity reaches 11.7 A/W and external quantum efficiency reaches 2730% under 532 nm laser.
Light-trapping design for thin-film silicon-perovskite tandem solar cells
Authors: Foster Stephen , John Sajeev
Published: September 2016

Using finite-difference time-domain simulations, we investigate the optical properties of tandem silicon/perovskite solar cells with a photonic crystal architecture, consisting of a square-lattice array of inverted pyramids with a center-to-center spacing of 2.5 μm. We demonstrate that near-perfect light-trapping and absorption can be achieved over the 300–1100 nm wavelength range with this architecture, using less than 10 μm (equivalent bulk thickness) of crystalline silicon. Using a one-diode model, we obtain projected efficiencies of over 30% for the two-terminal tandem cell under a current-matching condition, well beyond the current record for single-junction silicon solar cells. The architecture is amenable to mass fabrication through wet-etching and uses a fraction of the silicon of traditional designs, making it an attractive alternative to other silicon-perovskite tandem designs.
Invariability of rate dependences of normalized flow stress in niobium and molybdenum under conditions of shock compression
Authors: Zaretsky E. B. , Kanel G. I.
Published: September 2016

The evolution of elastic-plastic shock waves has been studied in pure molybdenum and niobium at normal and elevated temperatures over propagation distances ranging from 0.03 to 5 mm. The experiments revealed that annealing of the metals substantially increases their Hugoniot elastic limits and, to a lesser degree, their spall strengths. Variations in the resistance of both the metals to fracture in tension with the test temperature can be described as modest. Measuring the decay of the elastic precursor waves with a propagation distance in the two metals has allowed a determining of the relationships between a flow stress τ and an initial plastic strain rate γ̇p. It was found that, at the plastic strain rates greater than 3÷4×104s−1, the temperature sensitivity of the transient values of τ is much lower than that at the strain rates below this range. The τ(γ̇p) data normalized on shear moduli of the metals have been approximated by simple functions that, despite substantial differences between the moduli and yield stresses, were found to be virtually identical for the two metals.
A concept of heat dissipation coefficient for thermal cloak based on entropy generation approach
Authors: Xu Guoqiang , Zhang Haochun
Published: September 2016

In this paper, we design a 3D spherical thermal cloak with eight material layers based on transformation thermodynamics and it worked at steady state before approaching ‘static limit’. Different from the present research, we introduce local entropy generation to present the randomness in the cloaking system and propose the concept of a heat dissipation coefficient which is used to describe the capacity of heat diffusion in the ‘cloaking’ and ‘protected’ region to characterize the cloaking performance on the basis of non-equilibrium thermodynamics. We indicate the ability of heat dissipation for the thermal cloak responds to changes in anisotropy (caused by the change in the number of layers) and differential temperatures. In addition, we obtain a comparison of results of different cloaks and believe that the concept of a heat dissipation coefficient can be an evaluation criterion for the thermal cloak.
Experimental study of the thermoacoustic effect in magnetoacoustic tomography
Authors: Zhou Xiaoqing , Ma Ren , Zhang Wei , Zhang Shunqi , Li Junlin , Yin Tao , Liu Zhipeng
Published: September 2016

Magnetoacoustic tomography (MAT) is an emerging noninvasive electrical conductivity imaging that combines the high dielectric contrast of tissues and excellent resolutions of ultrasonography. In this paper, we have found the thermoacoustic (TA) effect in the measurement of MAT. Several materials with different conductivities have been measured by a MAT system with and without a static magnetic field. The acoustic signals have been analyzed and compared in the time domain and the frequency domain, respectively. It is found that the TA effect is related to the material characteristics. For the tissue-like materials with low conductivities, the TA signals caused by the TA effect are observable and cannot be ignored in the time and frequency domains. It means that the TA effect of biological tissues should be considered in MAT system in the future.
Multi-parameter sensor based on random fiber lasers
Authors: Xu Yanping , Zhang Mingjiang , Lu Ping , Mihailov Stephen , Bao Xiaoyi
Published: September 2016

We demonstrate a concept of utilizing random fiber lasers to achieve multi-parameter sensing. The proposed random fiber ring laser consists of an erbium-doped fiber as the gain medium and a random fiber grating as the feedback. The random feedback is effectively realized by a large number of reflections from around 50000 femtosecond laser induced refractive index modulation regions over a 10cm standard single mode fiber. Numerous polarization-dependent spectral filters are formed and superimposed to provide multiple lasing lines with high signal-to-noise ratio up to 40dB, which gives an access for a high-fidelity multi-parameter sensing scheme. The number of sensing parameters can be controlled by the number of the lasing lines via input polarizations and wavelength shifts of each peak can be explored for the simultaneous multi-parameter sensing with one sensing probe. In addition, the random grating induced coupling between core and cladding modes can be potentially used for liquid medical sample sensing in medical diagnostics, biology and remote sensing in hostile environments.
Room temperature fabrication of 1D carbon-copper composite nanostructures directly on Cu substrate and their field emission properties
Authors: Rosmi Mohamad Saufi , Yaakob Yazid , Mohd Yusop Mohd Zamri , Sharma Subash , Zulkifli Zurita , Supee Aizuddin , Kalita Golap , Tanemura Masaki
Published: September 2016

This paper demonstrates a carbon-copper (C-Cu) composite nanostructure directly fabricated on a copper (Cu) substrate using the Ar+ ion irradiation method at room temperature. The morphology of C-Cu composite was controlled by a simultaneous carbon supply during ion irradiation. Conical protrusions formed on the surface of the Cu substrate with the low carbon supply rate (RC), whereas high RC area prominently produced nanoneedle structures. The field electron emission (FEE) tests demonstrated significant improvement between conical protrusions and nanoneedle structures, where the emission current increase from 5.70 μAcm−2 to 4.37 mAcm-2, while the turn-on field reduced from 5.90 to 2.00 Vμm−1.
Digestible tryptophan to lysine ratios for weaned piglets at 26 days of age
Authors: Oliveira G. M. , Ferreira A. S. , Campos P. F. , Rodrigues V. V. , Silva F. C. O. , Santos W. G. , Lima A. L. , Rodrigues P. G. , Lopes C. C.
Published: September 2016

With the objective of determining the optimal digestible tryptophan to lysine ratios (Trp : Lys) in feed, 192 crossbred piglets were weaned at 26.3 ± 2.0 days, with initial weights of 8 ± 0.360 kg. The piglets were blocked by bodyweight and randomly allotted into six treatments, eight repetitions and four piglets per experimental unit. The treatments included five ratios of digestible Trp : Lys of 0.15, 0.17, 0.19, 0.21 and 0.23 with 1.26% digestible lysine and one positive control treatment (C+) with a Trp : Lys ratio of 0.19 and digestible lysine of 1.33%. The piglet’s performance and other characteristics were evaluated in phases: Phase I lasted from weaning up to Day 14 of the experiment, and Phase II lasted from weaning up to Day 21 of the experiment. The feed intake during Phase I, including the protein and fat deposition rates, the kidney relative weights and carcass yield were not influenced by the Trp : Lys ratios (P > 0.05). The Trp : Lys ratios had a linear effect on the liver and kidney absolute weights (P < 0.05). The ratio also had a linear effect (P < 0.01) on the bodyweight, the average daily gain, the gain : feed ratio of the piglets during Phases I and II and on the feed intake during Phase II (P < 0.05). The effect of the Trp : Lys ratios on the digestible lysine level (P = 0.04) demonstrated that digestible lysine was a limiting factor. The Linear Response Plateau model indicated that the best Trp : Lys ratio (P = 0.04) was 0.20 during Phase I and 0.22 (P < 0.01) during Phase II. Thus, the optimal digestible Trp : Lys ratio for piglets during the initial growth phase (from 26 to 47 days of age) is 0.22.
Connectivity rescues genetic diversity after a demographic bottleneck in a butterfly population network
Authors: Jangjoo Maryam , Matter Stephen F. , Roland Jens , Keyghobadi Nusha
Published: September 2016

Significance

With climate change and associated climatic instability, populations are expected to experience more frequent and severe fluctuations in size. These population size fluctuations erode genetic diversity, which is a central concern for conservation. Connectivity among habitats should, in theory, protect against the erosion of genetic diversity because immigration of individuals into populations can counteract genetic diversity loss. Our study provides the first evidence in a natural system for a direct effect of connectivity in recovery of genetic diversity following a demographic bottleneck, highlighting the importance of maintaining connectivity in the face of climate change. Our results suggest an important potential interaction between the two global change factors of habitat fragmentation and climate change on genetic diversity of natural populations.
Twenty-million-year relationship between mammalian diversity and primary productivity
Authors: Fritz Susanne A. , Eronen Jussi T. , Schnitzler Jan , Hof Christian , Janis Christine M. , Mulch Andreas , Böhning-Gaese Katrin , Graham Catherine H.
Published: September 2016

Significance

Our study links diversity dynamics of fossil large mammals through time to primary productivity, i.e. net production of plant biomass. Spatial diversity patterns of extant terrestrial animals are often correlated with present-day primary productivity, but it is unclear whether the relationship holds throughout the geological past. Here we show that higher primary productivity was consistently associated with higher mammalian diversity throughout the geological period of the Neogene, supporting the hypothesis that energy flow from plants to consumers is a key factor determining the level of biodiversity. Our comparison of the fossil diversity–productivity relationship with present-day data suggests that human activity and Pleistocene climate change have conspired to dissolve the relationship that has characterized our planet over 20 My.
Chromatin-modifying genetic interventions suppress age-associated transposable element activation and extend life span in
Drosophila
Authors: Wood Jason G. , Jones Brian C. , Jiang Nan , Chang Chengyi , Hosier Suzanne , Wickremesinghe Priyan , Garcia Meyrolin , Hartnett Davis A. , Burhenn Lucas , Neretti Nicola , Helfand Stephen L.
Published: September 2016

Significance

Most eukaryotic genomes contain abundant transposable elements (TEs), mobile DNA elements that can replicate and move within the genome. Because of the deleterious nature of active TEs, cells have mechanisms to suppress and prevent TE activation, including formation of repressive heterochromatin. In this report, we show that many TEs become activated with age in
Drosophila
, and this activation is prevented by dietary restriction, an intervention known to extend life span. We also show TE activation is blocked by genetic manipulations that stabilize heterochromatin and increase life span. This study provides evidence that a breakdown in TE silencing and repression may be a contributing factor to aging, and preventing TE activation may be a significant method of ameliorating the diseases of aging.
Aβ42 assembles into specific β-barrel pore-forming oligomers in membrane-mimicking environments
Authors: Serra-Batiste Montserrat , Ninot-Pedrosa Martí , Bayoumi Mariam , Gairí Margarida , Maglia Giovanni , Carulla Natàlia
Published: September 2016

Significance

Numerous reports indicate that amyloid-β peptide (Aβ) oligomers, considered the pathogenic molecular form of Aβ in Alzheimer´s disease (AD), exert their neurotoxicity within the membrane. Therefore, it is critical to characterize them in such an environment. Here, we worked with two major Aβ variants and handled them as if they were membrane proteins. By doing so, we found that the Aβ variant most strongly linked to AD assembled into stable Aβ oligomers that adopted a specific structure and incorporated into membranes as pores, a feature linked to neurotoxicity. Having access to pore-forming Aβ oligomers with such a specific structure offers unique opportunities to fully characterize them and establish their involvement in AD.
A C-terminal amphipathic helix is necessary for the in vivo tubule-shaping function of a plant reticulon
Authors: Breeze Emily , Dzimitrowicz Natasha , Kriechbaumer Verena , Brooks Rhiannon , Botchway Stanley W. , Brady Jacob P. , Hawes Chris , Dixon Ann M. , Schnell Jason R. , Fricker Mark D. , Frigerio Lorenzo
Published: September 2016

Significance

This study demonstrates, in vivo, that reticulon (RTN) proteins, responsible for the shaping and maintenance of endoplasmic reticulum (ER) membrane tubules, rely on a highly conserved C-terminal amphipathic helix (APH) for their morphogenic function. Previously it was thought that RTN could bend the ER membrane both by assuming a wedge-like topology and by forming oligomeric arcs. We show here that deleting or mutating the APH region abolishes the function of a plant RTN but does not affect its capacity to oligomerize. These findings indicate that proteins of the RTN family use an APH to affect membrane curvature: a mechanism that is shared by several other membrane-shaping protein families.
Elevated vitamin E content improves all-
trans
β-carotene accumulation and stability in biofortified sorghum
Authors: Che Ping , Zhao Zuo-Yu , Glassman Kimberly , Dolde David , Hu Tiger X. , Jones Todd J. , Gruis Darren Fred , Obukosia Silas , Wambugu Florence , Albertsen Marc C.
Published: September 2016

Significance

Studies on the importance of vitamin A for human health continue to draw significant worldwide attention. However, the instability of provitamin A in crops resulted in a significant reduction of the potential nutrition values of these food crops. Our work demonstrates that provitamin A can be stabilized in sorghum by the coexpression of vitamin E through ectopic expression of homogentisate geranylgeranyltransferase (
HGGT
) and that vitamin E can enhance the stability of provitamin A
in planta
. This research has the potential to impact directly the lives of the millions of people who suffer from vitamin A deficiency, and we believe that these results will be applicable to enhancing provitamin A stability in many food crops.
Host–pathogen evolutionary signatures reveal dynamics and future invasions of vampire bat rabies
Authors: Streicker Daniel G. , Winternitz Jamie C. , Satterfield Dara A. , Condori-Condori Rene Edgar , Broos Alice , Tello Carlos , Recuenco Sergio , Velasco-Villa Andrés , Altizer Sonia , Valderrama William
Published: September 2016

Significance

In Latin America, vampire bat rabies constrains livestock production and is the main cause of lethal human rabies outbreaks. Despite knowledge that bat dispersal prevents viral extinction and compromises control campaigns, the movement patterns of infected bats are unknown. Using large host and virus datasets, we illustrate a genetic approach to link population level patterns of host dispersal to pathogen spatial spread that overcomes logistical limitations of tracking animal movement in the wild. The results implicate male vampire bats as contributing disproportionately to rabies spatial spread and offer opportunities to forecast and prevent rabies. The ubiquity of sex-biased dispersal in animals suggests sex-biased pathogen spread could widely influence the distribution and invasion dynamics of emerging diseases.
Pollen dispersal slows geographical range shift and accelerates ecological niche shift under climate change
Authors: Aguilée Robin , Raoul Gaël , Rousset François , Ronce Ophélie
Published: September 2016

Significance

Will plants species survive climate warming? By which mechanisms? Ignoring pollen dispersal, previous models have predicted that species may escape extinction by tracking in space the climatic conditions to which they were previously adapted. Using quantitative genetics models, we demonstrate that plants dispersing their pollen could survive under a faster climate change than expected: pollen dispersal slows the range shift in space but facilitates the evolution of new climatic niche limits, such that the species becomes adapted to warmer conditions. Therefore, current predictions of the future spatial distribution of plants, as well as current assessments of the extinction risk due to climate warming, could be significantly altered for plants, especially those dispersing pollen far compared with seeds.
Real-time 3D imaging of microstructure growth in battery cells using indirect MRI
Authors: Ilott Andrew J. , Mohammadi Mohaddese , Chang Hee Jung , Grey Clare P. , Jerschow Alexej
Published: September 2016

Significance

Lithium metal is an ideal anode material for rechargeable Li-ion batteries, but its use is prevented by the growth of lithium deposits, or “dendrites,” during charging that can cause performance loss and serious safety concerns. Understanding the growth of dendrites in situ is crucial for the progress of this technology. MRI has been limited to directly studying the lithium signal until now, resulting in low sensitivity, limited resolution, and long experiment times. We present here an approach that detects the “shadows” of dendrites growing through the electrolyte, allowing the dendrites’ growth to be imaged very quickly in 3D with high resolution. This technique can also be applied to other electrodes, such as those based on sodium, zinc, and magnesium.
Tunable shear thickening in suspensions
Authors: Lin Neil Y.C. , Ness Christopher , Cates Michael E. , Sun Jin , Cohen Itai
Published: September 2016

Significance

When a concentrated suspension is strained, its viscosity can increase radically. This behavior, known as shear thickening, can be very useful to technological applications or highly problematic in industrial processes. Suspension flow properties are typically specified at the formulation stage, meaning that they are fixed in advance rather than controlled in situ during application. Here, we report a biaxial shear strategy eradicating the flow-induced structures responsible for thickening and tuning the suspension viscosity on demand during flow. This protocol enables us to regulate the thickening viscosity over 2 orders of magnitude. The tuning capability is a foundational step toward using dense suspensions in 3D printing, energy storage, and robotics.
Illusory Late Heavy Bombardments
Authors: Boehnke Patrick , Harrison T. Mark
Published: September 2016

Significance

The vast majority of evidence marshaled for the Late Heavy Bombardment comes from40Ar/39Ar age spectra of Apollo samples, interpreted through “plateau” ages, which show an apparent cluster at ∼3.9 Ga. Whether such data can be uniquely inverted to constrain impact histories in the Earth−Moon system has never been tested. We show that diffusive loss of40Ar from a monotonically declining impactor flux coupled with the early and episodic nature of lunar crust formation tends to create clustered distributions of apparent40Ar/39Ar ages atca.3.9 Ga. Instead, these40Ar/39Ar data can be reconciled with a continuously decreasing bollide flux. Thus, impacts may have played a minimal role in terrestrial habitability, early Earth dynamics, and the formation of Hadean zircons.
Differential structured illumination microendoscopy for in vivo imaging of molecular contrast agents
Authors: Keahey Pelham , Ramalingam Preetha , Schmeler Kathleen , Richards-Kortum Rebecca R.
Published: September 2016

Significance

Advances in molecular-targeted optical imaging probes offer the opportunity to identify and monitor pathophysiologic processes; to achieve this promise, there is an important need to develop devices capable of imaging probes in vivo at the cellular level. The challenge is to build devices that overcome the many optical and mechanical challenges associated with imaging soft tissue inside the body. Fiber optic microendoscopy has shown promise for in vivo imaging, but image contrast in highly scattering tissue is severely limited by out-of-focus light. In this paper, we demonstrate differential structured illumination microendoscopy (DSIMe) to image molecular contrast agents in vivo. We demonstrate improved image contrast of DSIMe when imaging patients with cervical adenocarcinoma in situ to detect atypia associated with neoplasia.
Talking in a Variety of Creative Languages ‒ A Fresh Approach to Art-Based Supervision
Authors: Berger Ronen
Published: September 2016

This article presents a new approach to creative supervision based on Jennings’ EPR and Lahad's BASICPh model, while focusing on the issues of artistic medium and artistic form. It suggests an original way to explore complexities and resistance in arts-based therapy. This approach can be integrated into arts therapy supervision in general, and the work of therapists who combine different arts media. Detailed examples are provided to illustrate the implementation of the approach. The article highlights ways in which creative supervision can expand therapists’ awareness, provide them with creative tools, as well as cultivate belief and inspiration.
Efficacy of reducing agent contacting pattern in Ag-SOEP electroless plating baths
Authors: Kaniganti C. M. , Uppaluri R.
Published: September 2016

Targeting upon the efficacy of bulk and drop wise contacting mode of hydrazine reducing agent, this work addresses Ag-SOEP ELP baths for porous Ag-ceramic composite membrane preparation. The investigations involved the assessment of both membrane and plating characteristics such as conversion, efficiency, PPD, MLI, average plating rate at various values of total plating time. The experimentation inferred that bulk mode of hydrazine contacting Ag-SOEP ELP baths is the optimal choice. Further, cost comparison was also conducted to differentiate the cost of the membranes with those available commercially. It has been found that the electroless fabricated membranes are significantly inexpensive than the available commercial membranes.
The Interplay of Trait Worry and Trait Anxiety in Determining Episodic Retrieval: The Role of Cognitive Control
Authors: Pajkossy Péter , Keresztes Attila , Racsmány Mihály
Published: September 2016

Worrying is a key concept in describing the complex relationship between anxiety and cognitive control. On the one hand, cognitive control processes might underlie the specific tendency to engage in worrying (i.e., trait worry), conceptualized as a future-oriented mental problem-solving activity. On the other hand, the general tendency to experience the signs and symptoms of anxiety (i.e., trait anxiety) is suggested to impair cognitive control because worrisome thoughts interfere with task-relevant processing. Based on these opposing tendencies, we predicted that the effect of the two related constructs, trait anxiety and trait worry, might cancel out one another. In statistics, such instances have been termed suppressor situations. In four experiments, we found evidence for such a suppressor situation: When their shared variance was controlled, trait worry was positively whereas trait anxiety was negatively related to performance in a memory task requiring strategic, effortful retrieval. We also showed that these opposing effects are related to temporal context reinstatement. Our results suggest that trait worry and trait anxiety possess unique sources of variance, which differently relate to performance in memory tasks requiring cognitive control.
Mental Rotation with Egocentric and Object-Based Transformations
Authors: Voyer Daniel , Jansen Petra , Kaltner Sandra
Published: September 2016

Two experiments were conducted to address methodological issues with past studies investigating the influence of egocentric and object-based transformations on performance and sex differences in mental rotation. In previous work, the egocentric and object-based mental rotation tasks confounded the stimulus type (embodied vs. non-embodied) and transformation task (egocentric vs. object-based). In both experiments presented here, the same stimuli were used regardless of the type of transformation but task instructions were modified to induce either egocentric (left–right judgment) or object-based (same–different judgment) processing. Experiment 1 used pairs of letters whereas Experiment 2 presented pairs of line-drawings of human hands. For both experiments, it was hypothesized that the mental rotation slope for response time would be steeper for object-based than for egocentric transformations. This hypothesis was verified in both experiments. Furthermore, Experiment 2 showed a reduced male advantage for egocentric compared to object-based rotations, whereas this pattern was reversed for Experiment 1. In conclusion, the present study showed that the influence of the type of transformation involved in mental rotation can be examined with the same set of stimuli simply by modifying task instructions.
Visualizing the Immaculate Conception: Donatello, Francesco della Rovere, and the High Altar and Choir Screen at the Church of the Santo in Padua
Authors: McHam Sarah Blake
Published: September 2016

This essay contends that Donatello’s High Altar at the Santo in Padua represents the Immaculate Virgin, reflecting a controversial doctrine of burgeoning interest in fifteenth-century Italy that she was exempted from original sin prior to the first moment of her conception. It ties the altar and scenes on the surrounding choir screen to a sermon promoting the Virgin’s immaculacy by Francesco della Rovere (later Sixtus IV), spoken in Padua in 1448 while the altar was being erected. It further connects the liturgical ensemble with bulls by Sixtus IV and liturgical offices sponsored by him after he was elected pope.
Torture and Translation in the Multilingual Courtrooms of Early Modern France
Authors: Cohen Paul
Published: September 2016

This article sketches the history of the mediation of linguistic difference in the context of judicial torture in early modern France. It argues that language represented an important dimension of what took place in the torture chambers of early modern Europe. Embedded within multilingual societies and habitually confronted with linguistic difference, tribunals developed an array of mediation practices. Shaped by officials’ scribal and linguistic practices and their infliction of pain in order to establish judicial facts, their linguistic choices also shed light on how jurists conceived of and set out uncovering the truth.