bluuebunny/crossref_metadata_2025 huggingface dataset:
The c-Jun N-terminal kinase prevents oxidative stress induced by UV and thermal stresses in corals and human cells
Authors: Courtial Lucile , Picco Vincent , Grover Renaud , Cormerais Yann , Rottier Cécile , Labbe Antoine , Pagès Gilles , Ferrier-Pagès Christine
Published: April 2017

Coral reefs are of major ecological and socio-economic interest. They are threatened by global warming and natural pressures such as solar ultraviolet radiation. While great efforts have been made to understand the physiological response of corals to these stresses, the signalling pathways involved in the immediate cellular response exhibited by corals remain largely unknown. Here, we demonstrate that c-Jun N-terminal kinase (JNK) activation is involved in the early response of corals to thermal and UV stress. Furthermore, we found that JNK activity is required to repress stress-induced reactive oxygen species (ROS) accumulation in both the coral Stylophora pistillata and human skin cells. We also show that inhibiting JNK activation under stress conditions leads to ROS accumulation, subsequent coral bleaching and cell death. Taken together, our results suggest that an ancestral response, involving the JNK pathway, is remarkably conserved from corals to human, protecting cells from the adverse environmental effects.
Reprogramming MHC specificity by CRISPR-Cas9-assisted cassette exchange
Authors: Kelton William , Waindok Ann Cathrin , Pesch Theresa , Pogson Mark , Ford Kyle , Parola Cristina , Reddy Sai T.
Published: April 2017

The development of programmable nucleases has enabled the application of new genome engineering strategies for cellular immunotherapy. While targeted nucleases have mostly been used to knock-out or knock-in genes in immune cells, the scarless exchange of entire immunogenomic alleles would be of great interest. In particular, reprogramming the polymorphic MHC locus could enable the creation of matched donors for allogeneic cellular transplantation. Here we show a proof-of-concept for reprogramming MHC-specificity by performing CRISPR-Cas9-assisted cassette exchange. Using murine antigen presenting cell lines (RAW264.7 macrophages), we demonstrate that the generation of Cas9-induced double-stranded breaks flanking the native MHC-I H2-Kd locus led to exchange of an orthogonal H2-Kb allele. MHC surface expression allowed for easy selection of reprogrammed cells by flow cytometry, thus obviating the need for additional selection markers. MHC-reprogrammed cells were fully functional as they could present H2-Kd-restricted peptide and activate cognate T cells. Finally, we investigated the role of various donor template formats on exchange efficiency, discovering that templates that underwent in situ linearization resulted in the highest MHC-reprogramming efficiency. These findings highlight a potential new approach for the correcting of MHC mismatches in cellular transplantation.
In search of evidence for the experience of pain in honeybees: A self-administration study
Authors: Groening Julia , Venini Dustin , Srinivasan Mandyam V.
Published: April 2017

Despite their common use as model organisms in scientific experiments, pain and suffering in insects remains controversial and poorly understood. Here we explore potential pain experience in honeybees (Apis mellifera) by testing the self-administration of an analgesic drug. Foragers were subjected to two different types of injuries: (i) a clip that applied continuous pressure to one leg and (ii) amputation of one tarsus. The bees were given a choice between two feeders, one offering pure sucrose solution, the other sucrose solution plus morphine. We found that sustained pinching had no effect on the amount of morphine consumed, and hence is unlikely to be experienced as painful. The amputated bees did not shift their relative preference towards the analgesic either, but consumed more morphine and more solution in total compared to intact controls. While our data do not provide evidence for the self-administration of morphine in response to pain, they suggest that injured bees increase their overall food intake, presumably to meet the increased energy requirements for an immune response caused by wounding. We conclude that further experiments are required to gain insights into potential pain-like states in honeybees and other insects.
Sexually-trimorphic interactions with colour polymorphism determine nectar quality in a herbaceous perennial
Authors: Varga Sandra , Soulsbury Carl D.
Published: April 2017

Amongst gynodioecious plant breeding systems, there can exist intermediate morphs with a reduction in their male function (i.e. reduced number of functional anthers). Along with this sexual trimorphism, plants can also show floral colour polymorphism. Such intricate mixtures of phenotypes within a species may have complex effects on floral rewards. Floral rewards are known to vary between sexually dimorphic species and to a lesser extent between colour morphs. However, the interactive effect of sexual trimorphism and colour polymorphism is unexplored. We measured nectar’s sugar content in the sexually trimorphic Geranium sylvaticum, a gynodioecious plant with a light/dark floral polymorphism. We found that nectar reward differed across genders and colour morphs. Results were not however consistent within the three genders; dark female and hermaphrodite flowers had higher sugar content than light morphs, whereas intermediate flowers did not. As expected, females and hermaphrodites had different nectar reward, with intermediate morphs being midway between the other genders. In intermediates, the sugar content was not related to the number of functional stamens. We show for the first time the existence of sex-specific differences between flower gender and colour morphs in nectar rewards. Our results demonstrate the importance of considering multiple and conflicting selection pressures to explain rewards.
Dynamic Wavelength-Tunable Photodetector Using Subwavelength Graphene Field-Effect Transistors
Authors: Léonard François , Spataru Catalin D. , Goldflam Michael , Peters David W. , Beechem Thomas E.
Published: April 2017

Dynamic wavelength tunability has long been the holy grail of photodetector technology. Because of its atomic thickness and unique properties, graphene opens up new paradigms to realize this concept, but so far this has been elusive experimentally. Here we employ detailed quantum transport modeling of photocurrent in graphene field-effect transistors (including realistic electromagnetic fields) to show that wavelength tunability is possible by dynamically changing the gate voltage. We reveal the phenomena that govern the behavior of this type of device and show significant departure from the simple expectations based on vertical transitions. We find strong focusing of the electromagnetic fields at the contact edges over the same length scale as the band-bending. Both of these spatially-varying potentials lead to an enhancement of non-vertical optical transitions, which dominate even in the absence of phonon or impurity scattering. We also show that the vanishing density of states near the Dirac point leads to contact blocking and a gate-dependent modulation of the photocurrent. Several of the effects discussed here should be applicable to a broad range of one- and two-dimensional materials and devices.
Acute effects of LSD on amygdala activity during processing of fearful stimuli in healthy subjects
Authors: Mueller F , Lenz C , Dolder P C , Harder S , Schmid Y , Lang U E , Liechti M E , Borgwardt S
Published: April 2017

Lysergic acid diethylamide (LSD) induces profound changes in various mental domains, including perception, self-awareness and emotions. We used functional magnetic resonance imaging (fMRI) to investigate the acute effects of LSD on the neural substrate of emotional processing in humans. Using a double-blind, randomised, cross-over study design, placebo or 100 μg LSD were orally administered to 20 healthy subjects before the fMRI scan, taking into account the subjective and pharmacological peak effects of LSD. The plasma levels of LSD were determined immediately before and after the scan. The study (including the a priori-defined study end point) was registered at ClinicalTrials.gov before study start (NCT02308969). The administration of LSD reduced reactivity of the left amygdala and the right medial prefrontal cortex relative to placebo during the presentation of fearful faces (P<0.05, family-wise error). Notably, there was a significant negative correlation between LSD-induced amygdala response to fearful stimuli and the LSD-induced subjective drug effects (P<0.05). These data suggest that acute administration of LSD modulates the engagement of brain regions that mediate emotional processing.
Chemo-enzymatic synthesis of equisetin
Authors: Li Xiaojun , Zheng Qingfei , Yin Jun , Liu Wen , Gao Shuanhu
Published: April 2017

A chemo-enzymatic synthesis of equisetin was developed, in which the Diels–Alderase Fsa2 is used for catalyzing the key IMDA reaction stereoselectively.
Potassium complexes supported by monoanionic tetradentate amino-phenolate ligands: synthesis, structure and catalysis in the ring-opening polymerization of rac-lactide
Authors: Yao Chenhui , Yang Yang , Xu Shaoan , Ma Haiyan
Published: April 2017

A series of potassium complexes bearing monoanionic tetradentate amino-phenolate ligands show versatile coordination chemistry and high activity in the ROP of rac-lactide.
Research highlights: investigating the role of nanoparticle surface charge in nano–bio interactions
Authors: Allen Caley , Qiu Tian A. , Pramanik Sunipa , Buchman Joseph T. , Krause Miriam O. P. , Murphy Catherine J.
Published: April 2017

This highlight outlines the complexity of nanoparticle surface charge-dependent interactions across a variety of biological systems.
Graph colouring based fractional frequency reuse for enterprise femtocell networks
Authors: Kim Se‐Jin , Cho IlKwon , Sok Chhorn , Bae Sang‐Hyun
Published: April 2017

In this study, the authors propose a novel dynamic channel assignment scheme called graph colouring based fractional frequency reuse (GC‐FFR) to improve system performance for the downlink of enterprise femtocell networks based on orthogonal frequency division multiple access with frequency division duplex. In order to mitigate co‐tier interference from neighbour femtocell access points, the proposed GC‐FFR scheme uses a heuristic method that consists of two steps: multiple femtocell user equipment (FUE) clustering step and dynamic subchannel assignment step. Simulation results show that the proposed GC‐FFR scheme outperforms other schemes in terms of the mean FUE capacity and unsatisfied FUE probability.
On the internal stability of non‐linear dynamic inversion: application to flight control
Authors: Alam Mushfiqul , Celikovsky Sergej
Published: April 2017

Aircraft are highly non‐linear systems, but flight control laws are traditionally designed from a set of linearised models. Due to the application of linear control laws on a non‐linear system, the real performance ability of the aircraft is not fully utilised. In addition, in adverse situations like near stall, the aircraft develops significant non‐linearities, and linear control laws do not perform well. This study therefore considers the design of a longitudinal flight controller for a fixed‐wing aircraft using non‐linear dynamic inversion technique or, in terms of control theory, partial exact feedback linearisation. A novel contribution of this study is the proposed combination of three different automatic flight controllers that provide complete 3‐DOF longitudinal control. A detailed analysis of the internal dynamics for each controller is also presented. It has been shown that for each controller the internal dynamics are stable. This makes the controller suitable for various flight conditions. The aims of these flight controllers are threefold. First, to provide control of the flight path angle by tracking the pitch angle and the angle of attack. Second, to provide high attitude (pitch up or down) manoeuvrability. Finally, to provide automatic adverse attitude recovery of the aircraft in situations like stall, the switching strategy between the controllers are also discussed. A simulation carried out on a non‐linear model of a multi‐role fighter aircraft verified the proposed theoretical results confirming the suitability of the controllers.
Two faces of competition: target‐mediated reverse signalling in microRNA and mitogen‐activated protein kinase regulatory networks
Authors: Jang Yongjin , Kim Min A , Kim Yoosik
Published: April 2017

Biomolecular regulatory networks are organised around hubs, which can interact with a large number of targets. These targets compete with each other for access to their common hubs, but whether the effect of this competition would be significant in magnitude and in function is not clear. In this review, the authors discuss recent in vivo studies that analysed the system level retroactive effects induced by target competition in microRNA and mitogen‐activated protein kinase regulatory networks. The results of these studies suggest that downstream targets can regulate the overall state of their upstream regulators, and thus cannot be ignored in analysing biomolecular networks.
Economies of scope in two-stage production systems: A data envelopment analysis approach
Authors: Ahranjani Leila Zeinalzadeh , Matin Reza Kazemi , Saen Reza Farzipoor
Published: April 2017

Traditional data envelopment analysis (DEA) models consider a production system as a black-box without taking into consideration its internal linked activities. In recent years, a number of DEA studies have been presented to estimate efficiency score of two-stage network production systems in which all outputs of the first stage (intermediate products) are used as inputs of the second stage to produce final outputs. This paper aims to develop a two-stage network DEA model to study economic notion of economies of scope (ES) between two products. It intends to determine profitability of joint production of two products by one firm. Numerical illustrations are presented to show applicability of proposed methods.
How Long Does It Take for Clopidogrel and Ticagrelor to Inhibit Platelets in Patients Undergoing Primary Percutaneous Coronary Intervention? A Detailed Pharmacodynamic Analysis: Time Course of Platelet Reactivity in STEMI (TOPS)
Authors: Bergmeijer Thomas , Godschalk Thea , Janssen Paul , Berge Kim , Breet Nicoline , Kelder Johannes , Hackeng Christian , Ten Berg Jurriën
Published: April 2017

Antiplatelet therapy plays a pivotal role in patients with an ST-segment elevation myocardial infarction (STEMI) to prevent further atherothrombotic events, such as stent thrombosis. Although the risk of stent thrombosis is highest in the first hours after primary percutaneous coronary intervention (pPCI), little is known about when an adequate level of platelet inhibition is achieved following a clopidogrel or ticagrelor loading dose in STEMI patients. Patients presenting with STEMI in whom pPCI was performed and who were loaded with 600 mg clopidogrel or 180 mg ticagrelor were eligible for enrolment in this nonrandomized, open label, single-center study. Platelet reactivity was measured before PCI, 6 and 24 hours after loading dose and after 2, 7, and 14 days, using the VerifyNow P2Y12 assay as well as 20 µmol/L adenosine diphosphate stimulated light transmittance aggregometry (LTA). We analyzed the time until a VerifyNow result of < 236 P2Y12 reaction units or LTA maximum platelet aggregation of < 64.5% was reached. A total of 28 patients were participated in this study. Platelet reactivity dropped below the high platelet reactivity cutoff level after 11.4 (VerifyNow) and 5.7 (LTA) hours in patients who were loaded with clopidogrel, and after 2.4 (VerifyNow) and 3.9 (LTA) hours in patients who were loaded with ticagrelor. Despite the administration of a clopidogrel or ticagrelor loading dose, it still takes multiple hours (2–11) to reach adequate platelet inhibition in STEMI patients. This might indicate the need for additional antiplatelet therapy in the first hours after loading in patients undergoing pPCI with stenting.
Effect of an Educational Presentation about Extremely Preterm Infants on Knowledge and Attitudes of Health Care Providers
Authors: Doucette Stefani , Lemyre Brigitte , Daboval Thierry , Dunn Sandra , Akiki Salwa , Barrowman Nick , Moore Gregory
Published: April 2017

Objective To determine healthcare providers' knowledge (HCP) about survival rates of extremely preterm infants (EPI) and attitudes toward resuscitation before and after an educational presentation and, to examine the relationship between knowledge and attitudes toward resuscitation.

Study Design Participants completed a survey before and after attending a presentation detailing evidence-based estimates of survival rates and surrounding ethical issues. Respondents included neonatologists, obstetricians, pediatricians, maternal-fetal medicine specialists, trainees in pediatrics, obstetrics, neonatal-perinatal medicine and neonatal and obstetrical nurses.

Results In total, 166 participants attended an educational presentation and 130 participants completed both pre- and postsurveys (response rate 78%). Prepresentation, for all gestations, ≤ 50% of respondents correctly identified survival/intact survival rates. Postpresentation, correct responses regarding survival/intact survival rates ranged from 49 to 86% (p < 0.001) and attitudes shifted toward being more likely to resuscitate at all gestations regardless of parental wishes. There was a weak-to-modest relationship (Spearman's coefficient 0.24–0.40, p < 0.001–0.004) between knowledge responses and attitudes.

Conclusion Attendance at an educational presentation did improve HCP knowledge about survival and long term outcomes for EPI, but HCP still underestimated survival and were not always willing to resuscitate in accordance with parental wishes. These findings may represent barriers to some experts' recommendation to use shared decision-making with parents when considering the resuscitation options for their EPI.
Association of Nursing Overtime, Nurse Staffing, and Unit Occupancy with Health Care–Associated Infections in the NICU
Authors: Blais Régis , Lacroix Guy , Cabot Michèle , Piedboeuf Bruno , Beltempo Marc
Published: April 2017

Objective This study aims to assess the association of nursing overtime, nurse staffing, and unit occupancy with health care–associated infections (HCAIs) in the neonatal intensive care unit (NICU).

Study Design A 2-year retrospective cohort study was conducted for 2,236 infants admitted in a Canadian tertiary care, 51-bed NICU. Daily administrative data were obtained from the database “Logibec” and combined to the patient outcomes database. Median values for the nursing overtime hours/total hours worked ratio, the available to recommended nurse staffing ratio, and the unit occupancy rate over 3-day periods before HCAI were compared with days that did not precede infections. Adjusted odds ratios (aOR) that control for the latter factors and unit risk factors were also computed.

Results A total of 122 (5%) infants developed a HCAI. The odds of having HCAI were higher on days that were preceded by a high nursing overtime ratio (aOR, 1.70; 95% confidence interval [95% CI], 1.05–2.75, quartile [Q]4 vs. Q1). High unit occupancy rates were not associated with increased odds of infection (aOR, 0.85; 95% CI, 0.47–1.51, Q4 vs. Q1) nor were higher available/recommended nurse ratios (aOR, 1.16; 95% CI, 0.67–1.99, Q4 vs. Q1).

Conclusion Nursing overtime is associated with higher odds of HCAI in the NICU.
Retinaler Venenverschluss – wann, womit und wie therapieren?
Authors: Bajor A. , Pielen A. , Danzmann L.
Published: April 2017

Nach neuesten Erkenntnissen ist ein Makulaödem infolge eines retinalen Venenverschlusses am besten mit einer zeitnahen intravitrealen Anti-VEGF-Therapie (Aflibercept, Bevacizumab [off label], Ranibizumab) sicher und effektiv behandelbar. Nach einem anfänglichen Upload von monatlich 3 Injektionen Anti-VEGF sollte in regelmäßigen Kontrollen vor allem OCT-basiert (bevorzugt gegenüber visusbasiert) über eine erneute Injektion entschieden werden. Nach anfänglichen monatlichen Injektionen haben sich derzeit vor allem das „Pro-re-nata“- (PRN) und das „Treat-and-Extend“-Schema in Bezug auf den weiteren Therapieverlauf durchgesetzt. Unter Beachtung des Nebenwirkungsspektrums (insbesondere Kataraktprogression, Augeninnendruckerhöhung) kann auch eine intravitreale Therapie mit einem Dexamethason-Implantat sinnvoll sein. Die Prognose bez. Visus und Rückgang des Makulaödems hängt von einem frühen Behandlungsbeginn mit konsequenter Therapiefortführung ab. Vor Behandlungsbeginn sowie im Verlauf ist eine Fluoresceinangiografie nötig, um ischämische Netzhautareale zu detektieren. Es gibt Hinweise, dass eine frühe gezielte Laserkoagulation ischämischer Netzhautareale die Frequenz der nötigen Injektionen senkt und zu einem besseren Ansprechen des Ödems auf die Therapie führt. Bei signifikanter retinaler Ischämie, die in der Folge zu Proliferationen, Rubeosis iridis und einem Sekundärglaukom führen kann, ist eine Laserbehandlung unumgänglich.
Time-resolved multi-mass ion imaging: Femtosecond UV-VUV pump-probe spectroscopy with the PImMS camera
Authors: Forbes Ruaridh , Makhija Varun , Veyrinas Kévin , Stolow Albert , Lee Jason W. L. , Burt Michael , Brouard Mark , Vallance Claire , Wilkinson Iain , Lausten Rune , Hockett Paul
Published: April 2017

The Pixel-Imaging Mass Spectrometry (PImMS) camera allows for 3D charged particle imaging measurements, in which the particle time-of-flight is recorded along with (x, y) position. Coupling the PImMS camera to an ultrafast pump-probe velocity-map imaging spectroscopy apparatus therefore provides a route to time-resolved multi-mass ion imaging, with both high count rates and large dynamic range, thus allowing for rapid measurements of complex photofragmentation dynamics. Furthermore, the use of vacuum ultraviolet wavelengths for the probe pulse allows for an enhanced observation window for the study of excited state molecular dynamics in small polyatomic molecules having relatively high ionization potentials. Herein, preliminary time-resolved multi-mass imaging results from C2F3I photolysis are presented. The experiments utilized femtosecond VUV and UV (160.8 nm and 267 nm) pump and probe laser pulses in order to demonstrate and explore this new time-resolved experimental ion imaging configuration. The data indicate the depth and power of this measurement modality, with a range of photofragments readily observed, and many indications of complex underlying wavepacket dynamics on the excited state(s) prepared.
A direct differential method for measuring thermal conductivity of thin films
Authors: Zeng Yuqiang , Marconnet Amy
Published: April 2017

Over the past two decades, significant progress in the thermal metrology for thin films and wires has enabled new understanding of the thermal conductivity of nanostructures. However, a large variation in the measured thermal conductivity of similar nanostructured samples has been observed. In addition to potential differences from sample-to-sample, measurement uncertainty contributes to the observed variation in measured properties. Many now standard micro/nanoscale thermal measurement techniques require extensive calibration of the properties of the substrate and support structures and this calibration contributes to uncertainty. Within this work, we develop a simple, direct differential electrothermal measurement of thermal conductivity of micro/nanoscale sample films by extending conventional steady state electrothermal approaches. Specifically, we leverage a cross-beam measurement structure consisting of a suspended, composite heater beam (metal on silicon) with the sample structure (silicon) extending at a right angle from the center of the heater beam, in a configuration similar to the T-type measurements used for fibers and nanotubes. To accurately resolve the thermal conductivity of the sample, the steady-state Joule heating response of the cross-beam structure is measured. Then, the sample is detached from the heater beam with a Focused Ion Beam (FIB) tool enabling direct characterization of the composite heater beam thermal properties. The differential measurement of the structure before and after FIB cut enables direct extraction of the sample thermal conductivity. The effectiveness of this differential measurement technique is demonstrated by measuring thermal conductivity of a 200 nm silicon layer. Additionally, this new method enables investigation of the accuracy of conventional approaches for extracting sample thermal conductivity with the composite beam structure and conventional comparative approaches. The results highlight the benefits of the direct differential method for accurate measurements with minimal assumptions.
The gas-phase structure of the asymmetric, trans-dinitrogen tetroxide (N2O4), formed by dimerization of nitrogen dioxide (NO2), from rotational spectroscopy and ab initio quantum chemistry
Authors: Seifert Nathan A. , Zaleski Daniel P. , Fehnel Robert , Goswami Mausumi , Pate Brooks H. , Lehmann Kevin K. , Leung Helen O. , Marshall Mark D. , Stanton John F.
Published: April 2017

We report the first experimental gas-phase observation of an asymmetric, trans-N2O4 formed by the dimerization of NO2. In additional to the dominant 14N216O4 species, rotational transitions have been observed for all species with single 15N and 18O substitutions as well as several multiply substituted isotopologues. These transitions were used to determine a complete substitution structure as well as an r0 structure from the fitted zero-point averaged rotational constants. The determined structure is found to be that of an ON–O–NO2 linkage with the shared oxygen atom closer to the NO2 than the NO (1.42 vs 1.61 Å). The structure is found to be nearly planar with a trans O–N–O–N linkage. From the spectra of the 14N15NO4 species, we were able to determine the nuclear quadrupole coupling constants for each specific nitrogen atom. The equilibrium structure determined by ab initio quantum chemistry calculations is in excellent agreement with the experimentally determined structure. No spectral evidence of the predicted asymmetric, cis-N2O4 was found in the spectra.
A multichannel visible spectroscopy system for the ITER-like W divertor on EAST
Authors: Mao Hongmin , Ding Fang , Luo Guang-Nan , Hu Zhenhua , Chen Xiahua , Xu Feng , Yang Zhongshi , Chen Jingbo , Wang Liang , Ding Rui , Zhang Ling , Gao Wei , Xu Jichan , Wu Chengrui
Published: April 2017

To facilitate long-pulse high power operation, an ITER-like actively cooled tungsten (W) divertor was installed in Experimental Advanced Superconducting Tokamak (EAST) to replace the original upper graphite divertor in 2014. A dedicated multichannel visible spectroscopic diagnostic system has been accordingly developed for the characterization of the plasma and impurities in the W divertor. An array of 22 lines-of-sight (LOSs) provides a profile measurement of the light emitted from the plasma along upper outer divertor, and the other 17 vertical LOSs view the upper inner divertor, achieving a 13 mm poloidal resolution in both regions. The light emitted from the plasma is collected by a specially designed optical lens assembly and then transferred to a Czerny-Turner spectrometer via 40 m quartz fibers. At the end, the spectra dispersed by the spectrometer are recorded with an Electron-Multiplying Charge Coupled Device (EMCCD). The optical throughput and quantum efficiency of the system are optimized in the wavelength range 350-700 nm. The spectral resolution/coverage can be adjusted from 0.01 nm/3 nm to 0.41 nm/140 nm by switching the grating with suitable groove density. The frame rate depends on the setting of LOS number in EMCCD and can reach nearly 2 kHz for single LOS detection. The light collected by the front optical lens can also be divided and partly transferred to a photomultiplier tube array with specified bandpass filter, which can provide faster sampling rates by up to 200 kHz. The spectroscopic diagnostic is routinely operated in EAST discharges with absolute optical calibrations applied before and after each campaign, monitoring photon fluxes from impurities and H recycling in the upper divertor. This paper presents the technical details of the diagnostic and typical measurements during EAST discharges.
Optimal design of nanoporous materials for electrochemical devices
Authors: Zhang Xuan , Tartakovsky Daniel M.
Published: April 2017

Unique macroscopic properties of nanoporous metamaterials stem from their microscopic structure. Optimal design of such materials is facilitated by mapping a material's pore-network topology onto its macroscopic characteristics. This is in contrast to both trial-and-error experimental design and design based on empirical relations between macroscopic properties, such as the often-used Bruggeman formula that relates a material's effective diffusion coefficient to its porosity. We use homogenization to construct such a map in the context of materials design that maximizes energy/power density performance in electrochemical devices. For example, effective diffusion coefficients and specific surface area, key macroscopic characteristics of ion transport in a hierarchical nanoporous material, are expressed in terms of the material's pore structure and, equally important, ion concentrations in the electrolyte and externally applied electric potential. Using these microscopic characteristics as decision variables, we optimize the macroscopic properties for two two-dimensional material-assembly templates and several operating conditions. The latter affect the material's performance through formation of an electrical double layer at the fluid-solid interfaces, which restricts the pore space available for ion transport.
Coupled-cluster method for open-shell heavy-element systems with spin-orbit coupling
Authors: Cao Zhanli , Wang Fan , Yang Mingli
Published: April 2017

The coupled-cluster approach with spin-orbit coupling (SOC) included in post-self-consistent field treatment (SOC-CC) using relativistic effective core potentials is extended to spatially non-degenerate open-shell systems in this work. The unrestricted Hartree-Fock determinant corresponding to the scalar relativistic Hamiltonian is employed as the reference and the open-shell SOC-CC approach is implemented at the CC singles and doubles (CCSD) level as well as at the CCSD level augmented by a perturbative treatment of triple excitations (CCSD(T)). Due to the breaking of time-reversal symmetry and spatial symmetry, this open-shell SOC-CC approach is rather expensive compared with the closed-shell SOC-CC approach. The open-shell SOC-CC approach is applied to some open-shell atoms and diatomic molecules with s1, p3, σ1, or π2 configuration. Our results indicate that rather accurate results can be achieved with the open-shell SOC-CCSD(T) approach for these systems. Dissociation energies for some closed-shell molecules containing heavy IIIA or VIIA atoms are also calculated using the closed-shell SOC-CC approach, where energies of the IIIA or VIIA atoms are obtained from those of the closed-shell ions and experimental ionization potentials or electron affinities. SOC-CCSD(T) approach affords reliable dissociation energies for these molecules. Furthermore, scalar-relativistic CCSD(T) approach with the same strategy can also provide reasonable dissociation energies for the 5th row IIIA or VIIA molecules, while the error becomes pronounced for the 6th row elements.
Electron transfer from the perspective of electron transmission: Biased non-adiabatic intermolecular reactions in the single-particle picture
Authors: Bevan Kirk H.
Published: April 2017

In this work, we revisit Hopfield’s formulation of non-adiabatic electron transfer between uncorrelated redox species within the single-particle picture description of electron transmission commonly applied in solid-state systems. The formulation is applied to a model system, similar to that often found in solid-state electron tunneling studies, consisting of redox species separated by an insulating tunneling barrier. Redox tunneling across such an insulator is predicted to demonstrate a marked asymmetry, ranging from one to three orders of magnitude between forward and reverse bias electron transfer rates, when reactants possess dissimilar reorganization energies. This significant asymmetry is shown to arise from trapezoidal reshaping of the integrated Gamow tunneling barrier and corresponding transmission probability under an applied bias. In general, this work aims to further bridge concepts between the electron transfer and transport communities.
Atomic polarizations necessary for coherent infrared intensity modeling with theoretical calculations
Authors: Richter Wagner E. , Silva Arnaldo F. , Bruns Roy E.
Published: April 2017

The inclusion of atomic polarizations for describing molecular electronic structure changes on vibration is shown to be necessary for coherent infrared intensity modeling. Atomic charges from the ChelpG partition scheme and atomic charges and dipoles from Quantum Theory of Atoms in Molecules (QTAIM) were employed within two different models to describe the stretching and bending vibrational intensities of the C–H, C–F, and C=O groups. The model employing the QTAIM parameters was the Charge–Charge Transfer and Dipolar Polarization model (QTAIM/CCTDP), and the model employing the ChelpG charges was the Equilibrium Charge–Charge Flux (ChelpG/ECCF). The QTAIM/CCTDP models result in characteristic proportions of the charge–charge transfer–dipolar polarization contributions even though their sums giving the total intensities do not discriminate between these vibrations. According to the QTAIM/CCTDP model, the carbon monoxide intensity has electronic structure changes similar to those of the carbonyl stretches whereas they resemble those of the CH stretches for the ChelpG/ECCF model.
Laser-induced persistent photovoltage on the surface of a ternary topological insulator at room temperature
Authors: Sánchez-Barriga J. , Battiato M. , Golias E. , Varykhalov A. , Yashina L. V. , Kornilov O. , Rader O.
Published: April 2017

Using time- and angle-resolved photoemission, we investigate the ultrafast response of excited electrons in the ternary topological insulator (Bi1-xSbx)2Te3 to fs-infrared pulses. We demonstrate that at the critical concentration x = 0.55, where the system becomes bulk insulating, a surface voltage can be driven at room temperature through the topological surface state solely by optical means. We further show that such a photovoltage persists over a time scale that exceeds ∼6 μs, i.e, much longer than the characteristic relaxation times of bulk states. We attribute the origin of the photovoltage to a laser-induced band-bending effect which emerges near the surface region on ultrafast time scales. The photovoltage is also accompanied by a remarkable increase in the relaxation times of excited states as compared to undoped topological insulators. Our findings are relevant in the context of applications of topological surface states in future optical devices.
Poly (ethylene imine)-modulated transport behaviors of graphene field effect transistors with double Dirac points
Authors: Sun Yilin , Xie Dan , Zhang Cheng , Li Xinming , Xu Jianlong , Sun Mengxing , Teng Changjiu , Li Xian , Zhu Hongwei
Published: April 2017

The bottom-gated graphene field-effect transistors (GFETs) with HfO2 as the dielectric layer are fabricated and the transport behaviors with double Dirac points defined as the right conductance minima (VDirac+) and the left one (VDirac-) are obtained, which exhibit the unique W-shaped transform characteristics rather than the typical V-shape. This observation indicates that the graphene in the channel region shows the different doping behaviors from that underlying the metal contact region. The W-shaped characteristics of GFETs are affected by the ambient environment and the time-dependence of double Dirac points has been also found. After being treated by Poly (ethylene imine) (PEI), the transport behaviors of GFETs could be modulated, especially for VDirac+ showing more obvious negative shift, indicating that PEI has a remarkable n-doping effect on the graphene in the channel region. PEI also screens the environmental influence and could protect the graphene from being p-doped to some extent. At the same time, the annealing effect has been also studied and it is found that the proper annealing process could contribute to the recovery of the graphene properties.
Three dimensional metafilms with dual channel unit cells
Authors: Burckel D. Bruce , Campione Salvatore , Davids Paul S. , Sinclair Michael B.
Published: April 2017

Three-dimensional (3D) metafilms composed of periodic arrays of silicon unit cells containing single and multiple micrometer-scale vertical split ring resonators (SRRs) per unit cell were fabricated. In contrast to planar and stacked planar structures, these 3D metafilms have a thickness t ∼ λd/4, allowing for classical thin film effects in the long wavelength limit. The infrared specular far-field scattering response was measured for metafilms containing one and two resonators per unit cell and compared to numerical simulations. Excellent agreement in the frequency region below the onset of diffractive scattering was obtained. For dense arrays of unit cells containing single SRRs, normally incident linearly polarized plane waves which do not excite a resonant response result in thin film interference fringes in the reflected spectra and are virtually indistinguishable from the scattering response of an undecorated array of unit cells. For the resonant linear polarization, the specular reflection for arrays is highly dependent on the SRR orientation on the vertical face for gap-up, gap-down, and gap-right orientations. For dense arrays of unit cells containing two SRRs per unit cell positioned on adjacent faces, the specular reflection spectra are slightly modified due to near-field coupling between the orthogonally oriented SRRs but otherwise exhibit reflection spectra largely representative of the corresponding single-SRR unit cell structures. The ability to pack the unit cell with multiple inclusions which can be independently excited by choice of incident polarization suggests the construction of dual-channel films where the scattering response is selected by altering the incident polarization.
Patterning the two dimensional electron gas at the LaAlO3/SrTiO3 interface by structured Al capping
Authors: Zhou Y. , Wang P. , Luan Z. Z. , Shi Y. J. , Jiang S. W. , Ding H. F. , Wu D.
Published: April 2017

We demonstrate an approach for patterning a quasi-two dimensional electron gas (q-2DEG) at the interface of LaAlO3 (LAO) and SrTiO3 (STO) utilizing a structured Al capping layer. The capping of Al enables the formation of q-2DEG at the interface of 1–3 unit cells (uc) of LAO on STO, which was originally insulating before capping. The properties of the q-2DEG induced by the Al capping layer are essentially the same as those of q-2DEG without Al. Therefore, we can pattern q-2DEG by simply patterning the Al film on LAO (2 or 3 uc)/STO using a one-step liftoff process. Our approach circumvents the difficulty of direct patterning of oxide materials and provides a simple and robust patterning method for future device applications based on complex oxide interfaces.
Passive cooling doesn’t cost the planet
Authors: Miller Johanna L.
Published: April 2017

Inexpensive ingredients and scalable processes yield a material that can emit more energy than it absorbs, even under direct sunlight.
Magnetic trap snares methyl radicals
Authors: Smart Ashley G.
Published: April 2017

The ability to isolate the important reaction intermediates at subkelvin temperatures could be a boon to cold chemistry.
Why the ocean’s carbon sink has gotten stronger
Authors: Chang Sung
Published: April 2017

The past decade's slowdown of overturning boosted the ocean's ability to take up carbon dioxide, but the enforcement may not last.
Undergraduate labs lag in science and technology
Authors: Feder Toni
Published: April 2017

Grants, prizes, and new experiments aim to bolster the status and stature of lab instruction.
Biology leads the race to turn sunlight into fuels
Authors: Kramer David
Published: April 2017

A bacterium can be harnessed to do the job, but can that process be scaled up?
Theory institute opens residence hall for visitors
Authors: Feder Toni
Published: April 2017

The aim is for informal interactions to stimulate creativity and collaborations.
From sound to meaning
Authors: Myers Emily B.
Published: April 2017

Culture and experience contribute to the process that translates a complex acoustic stimulus into an intelligible message.
The secret of the Soviet hydrogen bomb
Authors: Wellerstein Alex , Geist Edward
Published: April 2017

Was the first Soviet thermonuclear device really a step in the wrong direction?
Sakharov, Gorbachev, and nuclear reductions
Authors: von Hippel Frank N.
Published: April 2017

Two years before his death in 1989, Andrei Sakharov’s comments at a scientists’ forum helped set the stage for the elimination of thousands of nuclear ballistic missiles from the US and Soviet arsenals.
Supernovae, supercomputers, and galactic evolution
Authors: Hopkins Philip F.
Published: April 2017

The stars in a galaxy emit radiation and solar winds, and they sometimes die in fantastic explosions. Supercomputer simulations are now beginning to assess how those energy releases affect the galaxy’s life.
Influence of Adsorbent Nature on the Dynamic Headspace Study of Insect Semiochemicals
Authors: Rodriguez Sergio A. , Paliza María L. , Nazareno Monica A.
Published: April 2017

In chemical ecology studies (insect–insect, insect–plant relationships), it is important to choose the appropriate sampling methods and the correct optimization of sampling by using dynamic systems. In the present work, different adsorbents were evaluated in a dynamic system that presents a stream of purified air flowing through an aeration chamber containing a mixture of volatile organic compounds, mainly insect semiochemicals such as α-pinene, sulcatone, β-linalool, menthone, isomenthone, methyl salicylate, grandlure I, grandlure II, grandlure III, grandlure IV, eugenol, and α-ionone. Traditional adsorbents such as Tenax TA, Porapak Q, Hayesep Q, and activated charcoal were evaluated; further, alternatives such as Porapak Rxn RP, HLB, SCX, and silica gel, among others were proposed owing to their lower cost. The results demonstrated that Porapak Q and Porapak Rxn RP, despite their different chemical composition, were able to produce similar ratios of compounds to that of the reference solution and, moreover, with the highest recovery yields. However, it is important to emphasize the adsorption selectivity provided by SCX for eugenol and α-ionone. When Porapak Rxn RP was used in the analysis of Eucalyptus globulus volatiles, excellent results were obtained, and these agree with reported data from a hydrodistillation method.
Field trial and modelling of different strategies for remediation of soil salinity and sodicity in the Lower Murray irrigation areas
Authors: Mosley Luke M. , Cook Freeman , Fitzpatrick Rob
Published: April 2017

Rising saline groundwatertables and drought in the Lower Murray Reclaimed Irrigation Area (LMRIA) has created soil salinity and sodicity conditions, which has resulted in a decline in agricultural production. A 2 month field experiment was conducted at Mobilong irrigation area using a randomised block design with trial plots (4m2) in each of the three blocks containing the following six treatments: (1) control (not irrigated), (2) irrigation (River Murray water) only, (3) gypsum application (1.5 kg/m2) and irrigation, (4) limestone application (1.5 kg/m2) and irrigation, (5) seawater (source of dissolved Ca2+) application (100mm depth) and irrigation and (6) acid (pH 3) drainage (to dissolve CaCO3 in soil to release Ca2+) application (100mm irrigation water depth) and irrigation. Soil electrical conductivity (EC), pH, exchangeable cations (Ca2+, Mg2+, Na+, K+), exchangeable sodium percentage (ESP) and saturated hydraulic conductivity were measured. The decrease in EC was greatest in the irrigation only treatment followed by the gypsum and limestone treatments. At the end of the trial, the EC in the irrigation only treatment was about one-quarter of the control, in which the EC increased. The seawater and acid drainage treatments reduced the soil EC relative to the control but the EC was 2–3dS/m higher than the irrigation, gypsum and limestone treatments at the end of the trial. The gypsum, irrigation only and limestone treatments approximately doubled the exchangeable Ca relative to the control and exchangeable Na was reduced. Unsaturated water and solute transport model (HYDRUS-UNSATCHEM) simulations were able to represent the general trends in the field results. The results suggest that only River Murray water irrigation and drainage could be effective for the management of soil salinity and sodicity in the LMRIA but further research is required to establish the threshold electrolyte concentration to prevent soil dispersion.
Estimating the van Genuchten retention curve parameters of undisturbed soil from a single upward infiltration measurement
Authors: Moret-Fernández D. , Peña-Sancho C. , Latorre B. , Pueyo Y. , López M. V.
Published: April 2017

Estimation of the soil–water retention curve, θ(h), on undisturbed soil samples is of paramount importance to characterise the hydraulic behaviour of soils. Although a method of determining parameters of the water retention curve (α, a scale parameter inversely proportional to mean pore diameter and n, a measure of pore size distribution) from saturated hydraulic conductivity (Ks), sorptivity (S) and the β parameter, using S and β calculated from the inverse analysis of upward infiltration (UI) has been satisfactorily applied to sieved soil samples, its applicability to undisturbed soils has not been tested. The aim of the present study was to show that the method can be applied to undisturbed soil cores representing a range of textures and structures. Undisturbed soil cores were collected using stainless steel cylinders (5cm internal diameter×5cm high) from structured soils located in two different places: (1) an agricultural loam soil under conventional, reduced and no tillage systems; and (2) a loam soil under grazed and ungrazed natural shrubland. The α and n values estimated for the different soils using the UI method were compared with those calculated using time domain reflectometry (TDR) pressure cells (PC) for pressure heads of –0.5, –1.5, –3, –5, –10 and –50kPa. To compare the two methods, α values measured with UI were calculated to the drying branch of θ(h). For each treatment, three replicates of UI and PC calculations were performed. The results showed that the 5-cm high cylinders used in all experiments provided accurate estimates of S and β. Overall, the α and n values estimated with UI were larger than those measured with PC. These differences could be attributed, in part, to limitations of the PC method. On average, the n values calculated from the optimised S and β data were 5% larger than those obtained with PC. A relationship with a slope close to 1 fitted the n values estimated using both methods (nPC=0.73 nUI+0.49; R2=0.78, P<0.05). The results show that the UI method is a promising technique to estimate the hydraulic properties of undisturbed soil samples.