bluuebunny/crossref_metadata_2025 huggingface dataset:
Divergent response of homologous ATP sites to stereospecific ligand fluorination for selectivity enhancement
Authors: Patel Alpesh Ramanlal , Hardianto Ari , Ranganathan Shoba , Liu Fei
Published: January 2017

Enhanced selectivity for homologous ATP sites by composite chemical and conformational perturbation by stereospecific fluorination.
Synthesis of tri-functionalized MMP2 FRET probes using a chemo-selective and late-stage modification of unprotected peptides
Authors: Oriana Sean , Cai Ye , Bode Jeffrey W. , Yamakoshi Yoko
Published: January 2017

A polymeric FRET probe for the detection of MMP2 was prepared using a new N-hydroxylamine derivative of lysine, which was successfully incorporated into the natural peptide sequence by solid phase peptide synthesis, allowing dual orthogonal ligations of the fully unprotected peptides.
Developing laboratory skills by incorporating peer-review and digital badges
Authors: Seery Michael K. , Agustian Hendra Y. , Doidge Euan D. , Kucharski Maciej M. , O’Connor Helen M. , Price Amy
Published: January 2017

Laboratory work is at the core of any chemistry curriculum but literature on the assessment of laboratory skills is scant. In this study we report the use of a peer-observation protocol underpinned by exemplar videos. Students are required to watch exemplar videos for three techniques (titrations, distillations, preparation of standard solutions) in advance of their practical session, and demonstrate the technique to their peer, while being reviewed. For two of the techniques (titrations and distillations), the demonstration was videoed on a mobile phone, which provide evidence that the student has successfully completed the technique. In order to develop digital literacy skills, students are required to upload their videos to a video sharing site for instructor review. The activity facilitated the issuing of digital badges to students who had successfully demonstrated competency. Students’ rating of their knowledge, experience, and confidence of a range of aspects associated with each technique significantly increased as a result of the activity. This work, along with student responses to questions, video access, and observations from implementation are reported in order to demonstrate a novel and useful way to incorporate peer-assessment of laboratory skills into a laboratory programme, as well as the use of digital badges as a means of incorporating and documenting transferable skills on the basis of student generated evidence.
A soft non-porous separator and its effectiveness in stabilizing Li metal anodes cycling at 10 mA cm−2 observed in situ in a capillary cell
Authors: Liu Kai , Bai Peng , Bazant Martin Z. , Wang Chang-An , Li Ju
Published: January 2017

While lithium metal anodes have the highest theoretical capacity for rechargeable batteries, they are plagued by the growth of lithium dendrites, side reactions, and a moving contact interface with the electrolyte during cycling.
Serum microRNAs are non-invasive biomarkers for the presence and progression of subarachnoid haemorrhage
Authors: Lai Nian-sheng , Zhang Jia-qi , Qin Fei-yun , Sheng Bin , Fang Xing-gen , Li Zhen-bao
Published: January 2017

miRNAs are important regulators of translation and have been associated with the pathogenesis of a number of cardiovascular diseases including stroke and may be possible prognostic biomarkers. The purpose of the present study was to determine the expression levels of miRNAs in the sera of subarachnoid haemorrhage (SAH) patients and to evaluate their relationships with the severity and clinical outcome of SAH. Serum samples on day 3 after the onset of SAH were subjected to microarray analysis with Exqion miRCURYTM LNA array and quantitative PCR analysis. Serum samples from SAH patients (n=60) and healthy controls (n=10) were subjected to quantitative PCR analysis. The severities and clinical outcomes of the SAH patients were evaluated with the WFNS grade and the Modified Rankin Scale (mRS). Three miRNAs, miR-502-5p, miR-1297 and miR-4320 were significantly up-regulated in the sera of SAH patients when compared with the healthy controls. The serum miR-502-5p and miR-1297 levels were significantly higher in the patients with severe SAH and a poor outcome than in those with mild SAH and a good outcome (P<0.05). The areas under the receiver operating characteristic (ROC) curves (AUCs) of miR-502-5p, miR-1297 and miR-4320 to distinguish the SAH patients from the healthy controls were 0.958 (P<0.001), 0.950 (P<0.001) and 0.843 (P<0.001) respectively. Taken together, these results indicate that miR-502-5p and miR-1297 are potentially valuable indicators of the diagnosis, severity and prognosis of SAH, and miR-4320 was a potentially valuable indicator of the diagnosis of SAH.
Interference cancellation and signal detection technique based on QRD‐M algorithm for FTN signalling
Authors: Baek M.‐S. , Yun J. , Hur N. , Lim H.
Published: January 2017

This Letter presents interference cancellation and signal detection technique for faster‐than‐Nyquist (FTN) signalling. The proposed scheme uses QR decomposition (QRD)‐M algorithm to execute interference cancellation and signal detection. Based on the Toeplitz structure of the inter‐symbol interference coefficient matrix, the QRD‐M algorithm is adopted to detect the transmitted symbols from an FTN signal. The computational complexity comparisons and numerical results demonstrate that the proposed technique can achieve the complexity <10% of Bahl–Cocke–Jelinek–Raviv (BCJR) algorithm while maintaining BER performance similar to that of BCJR algorithm.
Picosecond precision time‐of‐flight digital converter
Authors: Wieczorek G. , Oliwa W.
Published: January 2017

Time‐of‐flight (TOF) digital converter implemented in field programmable gate array has been introduced. The operation is based on train of pulses transmission and counting received pulses in bank of counters. The bank of counters clock signal and the transmitted pulses clock signal are slightly different in frequency. This small difference is a key factor for the measurement method and is achieved by phase locked loop. TOF for the transmitted pulses is directly calculated upon counters counts. Time interval resolution for the prototype instrument is 10.4 ps and average RMS uncertainty value is 12.3 ps. There is no need for special calibration. TOF digital converter requires minimum amount of resources and is suitable for low‐cost applications.
Area‐priority‐based sensor deployment optimisation with priority estimation using K‐means
Authors: Ateş Enes , Kalayci Tahir Emre , Uğur Aybars
Published: January 2017

Deployment in wireless sensor networks (WSN) addresses maximising the coverage of sensors and reducing the total cost of deployment. The area‐priority concept for WSN deployment that the authors contributed to the literature recently allows environments with regions that have different importance or priority levels. In this study, the authors propose the first priority‐estimation method for area‐priority‐based WSN deployments. First, a satellite image of the environment that will be used in the deployment of the sensors is clustered by a K‐means algorithm using the colour features of the regions. In the sensor deployment phase, this cluster information is used to determine the priorities of the sensor coverage areas on positions of the image. Sensors are initially deployed quickly using a priority queue‐based technique. Then, a simulated annealing algorithm is used to maximise the total covered area priority and to minimise the gaps between the sensors. Various experiments are performed for different scenarios (land, sea, and forest) on images captured from Google Maps using different parameter values. The experiments confirm that the proposed approach performs well and outperforms the random deployment of sensors.
Echo state network‐based Q‐learning method for optimal battery control of offices combined with renewable energy
Authors: Shi Guang , Liu Derong , Wei Qinglai
Published: January 2017

An echo state network (ESN)‐based Q‐learning method is developed for optimal energy management of an office, where the solar energy is introduced as the renewable source, and a battery is installed with a control unit. The energy consumption in the office, also considered as the energy demand, is separated into those from sockets, lights and air‐conditioners. First, ESNs, well known for their excellent modelling performance for time series, are employed to model the time series of the real‐time electricity rate, renewable energy and energy demand as periodic functions. Second, given the periodic models of the electricity rate, renewable energy and energy demand, an ESN‐based Q‐learning method with the Q‐function approximated by an ESN is developed and implemented to determine the optimal charging/discharging/idle strategies for the battery in the office, so that the total cost of electricity from the grid can be reduced. Finally, numerical analysis is conducted to illustrate the performance of the developed method.
Multi‐group particle swarm optimisation for transmission expansion planning solution based on LU decomposition
Authors: Huang Shengjun , Dinavahi Venkata
Published: January 2017

As power systems are being highly stressed with the boost of loading levels and the introduction of new generation sources, transmission expansion planning (TEP) has regained its significance as a pivotal problem to be solved. To ameliorate the performance on both efficiency and accuracy for the solution of TEP from the aspect of algorithm design, a static DC TEP without generation redispatch is investigated by the proposed multi‐group particle swarm optimisation (MGPSO) algorithm. MGPSO is based on the discrete PSO framework with several beneficial enhancements involved, such as Sobol sequence initialisation method, multi‐group co‐evolution strategy, and mutation mechanism. For the solution of linear programming subproblem within the framework of MGPSO, a linear equation system is extracted and then addressed with efficient LU decomposition approach. Case studies have been implemented on five classical benchmarks, ranging from 6‐bus to 118‐bus, between the MGPSO and commercial software Lingo 11.0 to validate the superiority of MGPSO. Speedup analysis as well as performance evaluation of different acceleration strategy involved in MGPSO are implemented and discussed.
Robust allocation of reserves considering different reserve types and the flexibility from HVDC
Authors: Bucher Matthias A. , Ortega‐Vazquez Miguel A. , Kirschen Daniel S. , Andersson Göran
Published: January 2017

Since the production of electric power from renewable resources is intrinsically variable and uncertain, it creates difficulties in balancing demand and generation. On the one hand, the ensemble of dispatchable resources is being required to provide larger and more frequent ramping capabilities. On the other hand, the transmission grid is operated closer to its limits on a more frequent basis. These two factors require a reassessment of the techniques used to provide and ensure the deliverability of reserves and flexibility. In this study the authors present an adjustable robust approach for the procurement of reserve, as well as for the repartition of this reserve between manual and policy‐based automatic reserves. This approach takes into consideration the location and temporal evolution of the uncertainty on the generation sources and the flexibility offered by high voltage direct current (HVDC) interconnections. The resulting problem is solved iteratively. Case studies compare policy and non‐policy based reserves, the allocation of ramping capacity and the resulting operational cost.
Gender diversity on corporate boards: an empirical investigation of Italian listed companies
Authors: Solimene Silvia , Coluccia Daniela , Fontana Stefano
Published: January 2017

In recent years, there has been a growing consensus that gender diversity could improve the economic and social performance of companies—although progress has been painfully slow. In Italy, Law n. 120/2011 has required that since 2012 the composition of corporate boards must comprise at least 1/5 women and, from 2015, 1/3 women. Here, our primary aim was to study the proportion and the progression of female directors on the boards of Italian companies over the period between 2009–2014, among a sample of 60 companies listed on the Milan Stock Exchange. We additionally studied the characteristics of the women on the companies’ boards, in order to assemble a typical profile. To do this, we verified the boards’ compositions, the number of female directors, women’s power on the boards and their levels of education. Our results confirm that Italian law has produced significant effects on the composition of corporate boards. Moreover, we found that female directors are generally of Italian ethnic origin and have high levels of education, with a master’s, and sometimes, post-master’s degree. Furthermore, female directors are more likely to be professional figures with experience—the percentages of female directors with professional qualifications as well as the percentage of female directors on boards of other companies have consistently increased during the period mentioned. Our findings provide a descriptive analysis of female directors during the period between 2009–2014, thereby presenting a picture of gender equality in the Italian context. To our knowledge, this is the first study that has focused on examining gender equality among Italian-listed companies over such a long period. Future development of this research could examine in more depth the differences between male and female presence, behaviour and characteristics on boards, as well as how these issues affect the performance of firms. This article is published as part of a collection on the role of women in management and the workplace.
Diffusive-to-ballistic transition of the modulated heat transport in a rarefied air chamber
Authors: Gomez-Heredia C. L. , Macias J. , Ordonez-Miranda J. , Ares O. , Alvarado-Gil J. J.
Published: January 2017

Modulated heat transfer in air subject to pressures from 760 Torr to 10-4 Torr is experimentally studied by means of a thermal-wave resonant cavity placed in a vacuum chamber. This is done through the analysis of the amplitude and phase delay of the photothermal signal as a function of the cavity length and pressure through of the Knudsen’s number. The viscous, transitional, and free molecular regimes of heat transport are observed for pressures P>1.5 Torr, 25 mTorr<P<1.5 Torr, and P<25 mTorr; respectively. It is shown that the fingerprint of each regime is determined by the concavity of the amplitude decay in a length scan, which is concave upward for the viscous regime and concave downward in the free molecular one. Furthermore, the increase of the radiative contribution on both the amplitude and phase is also observed as the pressure reduces. The obtained results show that the proposed methodology can be used to study the molecular dynamics in gases supporting diffusive and ballistic heat transport.
Photodissociation of acetone from 266 to 312 nm: Dynamics of CH3 + CH3CO channels on the S and T1 states
Authors: Lee Kin Long Kelvin , Nauta Klaas , Kable Scott H.
Published: January 2017

The photodissociation dynamics of acetone (CH3)2CO, cooled in a molecular beam, have been explored over the wavelength range 266–312 nm. Nascent CH3 fragments were detected by resonance-enhanced multiphoton ionization, followed by mass-selected ion imaging. For photolysis at λ = 306 nm, the image shows a sharp ring, which, when converted to a translational energy distribution, reveals a narrow Gaussian peak with a maximum at 90% of the available energy. As the photolysis energy is increased, the distribution slowly broadens and shifts to higher recoil translational energy. The fraction of available energy in translation energy decreases in favour of internal energy of the CH3CO fragment. These observations are consistent with a dynamical model in which the energy of the exit channel barrier on the T1 surface evolves mostly into relative translational energy. Energy in excess of the barrier is partitioned statistically into all degrees of freedom. No evidence was found for any other dynamical pathway producing CH3 fragments, including reaction on S0 or S1, for dissociation between 306 and 266 nm. For λ > 306 nm, a diffuse, slow recoil component to the image appears. The translational energy distribution for this component is fit well by a statistical prior distribution of energy. We attribute this component to dissociation on the S0, ground state surface; to our knowledge, this is the first direct observation of this channel. The appearance of S0 dynamics and the disappearance of the T1 component are consistent with previously inferred barrier height on T1 for the production of CH3CO + CH3. The possible atmospheric implications of our findings are discussed.
DSMC study of oxygen shockwaves based on high-fidelity vibrational relaxation and dissociation models
Authors: Borges Sebastião Israel , Kulakhmetov Marat , Alexeenko Alina
Published: January 2017

This work evaluates high-fidelity vibrational-translational (VT) energy relaxation and dissociation models for pure O2 normal shockwave simulations with the direct simulation Monte Carlo (DSMC) method. The O2–O collisions are described using ab initio state-specific relaxation and dissociation models. The Macheret-Fridman (MF) dissociation model is adapted to the DSMC framework by modifying the standard implementation of the total collision energy (TCE) model. The O2–O2 dissociation is modeled with this TCE+MF approach, which is calibrated with O2–O ab initio data and experimental equilibrium dissociation rates. The O2–O2 vibrational relaxation is modeled via the Larsen-Borgnakke model, calibrated to experimental VT rates. All the present results are compared to experimental data and previous calculations available in the literature. It is found that, in general, the ab initio dissociation model is better than the TCE model at matching the shock experiments. Therefore, when available, efficient ab initio models are preferred over phenomenological models. We also show that the proposed TCE + MF formulation can be used to improve the standard TCE model results when ab initio data are not available or limited.
Analytic asymptotic solution to spherical relativistic shock breakout
Authors: Yalinewich Almog , Sari Re’em
Published: January 2017

We investigate the relativistic breakout of a shock wave from the surface of a star. In this process, each fluid shell is endowed with some kinetic and thermal energy by the shock, and then continues to accelerate adiabatically by converting thermal energy into kinetic energy. This problem has been previously studied for a mildly relativistic breakout, where the acceleration ends close to the surface of the star. The current work focuses on the case where the acceleration ends at distances much greater than the radius of the star. We derive an analytic description for the hydrodynamic evolution of the ejecta in this regime and validate it using a numerical simulation. We also provide predictions for the expected light curves and spectra from such an explosion. The relevance to astrophysical explosions is discussed, and it is shown that such events require more energy than is currently believed to result from astrophysical explosions.
Nitrogen doped nanographene structures; study on the adsorption of nucleobases, nucleotides, and their triphosphate derivatives using mixed docking, MD, and QM/MM approaches
Authors: Ghadari Rahim
Published: January 2017

The interactions of the nucleobases, nucleotides, and their triphosphate derivatives in both neutral and anionic forms with the nitrogen doped graphenes (NG) were studied using docking and molecular dynamic simulation methods. In docking studies, based on binding energy results, the anionic species and nucleobases were showing the most and the least tendency toward the surface of the NG, respectively. The molecular mechanic/Poisson−Boltzmann surface area results revealed similar results, except for the anionic species; in these studies, the anionic species showed a lesser affinity toward the NG. The time−dependent density functional theory studies were carried out to investigate the effects of the NG on the electronic nature of the investigated ligands; a red−shift in all of the cases was observed. The results of binding energy decomposition and atoms in molecules studies showed that the interactions are van der Waals in nature. The graphitic, pyridinic, and pyrrolic nitrogen atoms which were considered in this study behaved similar to each other.
A magnetometer for estimating the magnetic moment of magnetic micro-particles
Authors: Punyabrahma P. , Jayanth G. R.
Published: January 2017

Magnetic micro-particles find a variety of applications as actuators at the micrometer and nanometer length scales. While the actuation gain is directly proportional to their magnetic moment, there are relatively few technologies available to estimate the magnetic moment of individual magnetic particles. This paper proposes a magnetometer for direct measurement of the magnetic moment of ferromagnetic micro-particles. The magnetometer comprises a novel micro-scale force sensor capable of interacting with magnetic particles and deflecting in response to the force of interaction. It also comprises a high-resolution measurement system, a source of magnetizing field, and a nanopositioner. The principle of operation of the magnetometer is discussed and is shown to enable the determination of the magnetic moment even of the buried magnetic particles, and those of irregular geometry. Subsequently, the force sensor, the measurement system, and the magnetic field sources are designed, fabricated, and calibrated. Finally, the magnetometer is employed to measure the magnetic moments of both fixed and untethered permanent magnetic particles and also of a fixed soft ferromagnetic particle. In all cases, the estimated magnetic moment is shown to agree with the theoretical estimate with an average error of about 16%.
Numerical investigation of plasma-wall interaction during burst of ELMs in a tokamak device
Authors: Ou Jing , Lin Binbin , Zhao Xiaoyun
Published: January 2017

In the tokamak high confinement mode (H-mode), the transient heat fluxes caused by edge localized modes (ELMs) will eventually irradiate the plasma-facing components and may erode, even melt them. To study the performance of the plasma-wall interaction during ELMs, interactions among heat flux from plasma, surface temperature, and electron emission are simulated by considering self-consistency among plasma transport in the sheath, deposited heat at the wall, and material thermal response for carbon (C) and tungsten (W) walls. It is found that the sheath structure determines the surface temperature, which may in turn influence on the sheath. A large amount of electron emission can change the heat load from the plasma to the material surface due to the variation of the ELMs-induced electron temperature and the surface temperature. During the burst of ELMs, the surface temperature rises rapidly at first and then reaches a saturation state with a certain range of fluctuation. The development of these processes depends strongly on the characteristic of ELMs, deposited heat at the wall, and material properties. Simulation results also show that the erosion of the Experimental Advanced Superconducting Tokamak (EAST) divertor target is of no concern in H-mode operation with ELMs for the current and possible future operation parameters.
Near atomically smooth alkali antimonide photocathode thin films
Authors: Feng Jun , Karkare Siddharth , Nasiatka James , Schubert Susanne , Smedley John , Padmore Howard
Published: January 2017

Nano-roughness is one of the major factors degrading the emittance of electron beams that can be generated by high efficiency photocathodes, such as the thermally reacted alkali antimonide thin films. In this paper, we demonstrate a co-deposition based method for producing alkali antimonide cathodes that produce near atomic smoothness with high reproducibility. We calculate the effect of the surface roughness on the emittance and show that such smooth cathode surfaces are essential for operation of alkali antimonide cathodes in high field, low emittance radio frequency electron guns and to obtain ultracold electrons for ultrafast electron diffraction applications.
The influence of hydrostatic pressure on the magnetic and magnetocaloric properties of DyRu2Si2
Authors: Saleheen Ahmad Us , Samanta Tapas , Khan Mojammel , Adams Philip W. , Young David P. , Dubenko Igor , Ali Naushad , Stadler Shane
Published: January 2017

We report the magnetic and magnetocaloric properties of the tetragonal rare-earth compound DyRu2Si2 under applied hydrostatic pressure. The isothermal entropy change (ΔS) and the adiabatic temperature change (ΔTad) were calculated from magnetization data collected at different applied pressures and from heat capacity measurements conducted at atmospheric pressure, respectively. The application of hydrostatic pressure significantly modified the multi-step magnetization curve and the saturation magnetization. A suppression of the magnetization was observed for P = 0.588 GPa and P = 0.654 GPa whereas, at about P ≈1 GPa, the saturation magnetization increased and the magnetization isotherms again resembled the curves measured at atmospheric pressure. A small thermal hysteresis was observed between the heating and cooling M(T) curves at Tt=3.4 K, with an applied magnetic field of H = 0.1 T. This thermal hysteresis indicates a first-order like transition which was also supported by the Arrott plot analysis. The volume magnetostriction was estimated from the pressure-dependent magnetization measurements using a Maxwell relation.
An analysis of electric double layers near comb electrodes using the linearized Poisson-Nernst-Planck theory
Authors: Zhang Chunli , Lu Shuting , Mao Renwei , Chen Weiqiu , Tan Li , Zhou Qin , Yang Jiashi
Published: January 2017

A theoretical analysis on electric double layers formed near corners and neighboring branches of a comb electrode with a prescribed electric potential in an ionic conductor was performed using the linearized Poisson-Nernst-Planck theory which is closely related to the linearized Gouy-Chapman theory in static (time-independent) problems. Analytical solutions were obtained for two problems relevant to ionic capacitance applications defined over rectangular domains. The electric potential and ion distributions were calculated which are new, useful, and fundamental to the understanding and design of devices with comb electrodes. The basic behaviors of the distributions are presented and examined. For a positively charged electrode, the distribution of the negative ions was found to be qualitatively similar to that of the electric potential, and the behavior of the positive ions is the opposite. At an electrode corner, the electric double layer is relatively thicker than along a line electrode. When the distance between two positively charged parallel electrode branches is about twice the Debye length, the region between the two electrode branches is nearly uniformly filled by negative ions.
On the influence of environmental parameters on mixing and reconnection caused by the Kelvin-Helmholtz instability at the magnetopause
Authors: Leroy M. H. J. , Keppens R.
Published: January 2017

The process feeding the development of a large boundary layer at the interface between the solar wind and the magnetosphere during northward interplanetary magnetic field is still not fully understood, though the Kelvin-Helmholtz instability (KHI) being the major actor is in good agreement with the observations so far. In this article, we study the different configurations than can occur in the KHI scenario in a three-dimensional Hall-MHD setting, where the double mid-latitude reconnection (DMLR) process exposed by Faganello et al. [Europhys. Lett. 100, 69001 (2012)] is triggered by the equatorial roll-ups. Their previous work is extended here with, in particular, a larger simulation box and the addition of a density contrast. The influence of various parameters on the growth rate of the KHI and thus the efficiency of the DMLR is assessed. In the scope of assessing the effect of the Hall term on the physical processes, the simulations are also performed in the MHD frame. These different configurations may have discernible signatures that can be identified by spacecraft diagnostics; therefore the data that would be recorded by spacecrafts during such an event are simulated.
What happens to full-f gyrokinetic transport and turbulence in a toroidal wedge simulation?
Authors: Kim Kyuho , Chang C. S. , Seo Janghoon , Ku S. , Choe W.
Published: January 2017

In order to save the computing time or to fit the simulation size into a limited computing hardware in a gyrokinetic turbulence simulation of a tokamak plasma, a toroidal wedge simulation may be utilized in which only a partial toroidal section is modeled with a periodic boundary condition in the toroidal direction. The most severe restriction in the wedge simulation is expected to be in the longest wavelength turbulence, i.e., ion temperature gradient (ITG) driven turbulence. The global full-f gyrokinetic code XGC1 is used to compare the transport and turbulence properties from a toroidal wedge simulation against the full torus simulation in an ITG unstable plasma in a model toroidal geometry. It is found that (1) the convergence study in the wedge number needs to be conducted all the way down to the full torus in order to avoid a false convergence, (2) a reasonably accurate simulation can be performed if the correct wedge number N can be identified, (3) the validity of a wedge simulation may be checked by performing a wave-number spectral analysis of the turbulence amplitude |δΦ| and assuring that the variation of δΦ between the discrete kθ values is less than 25% compared to the peak |δΦ|, and (4) a frequency spectrum may not be used for the validity check of a wedge simulation.
Decoupling interface effect on the phase stability of CdS thin films by van der Waals heteroepitaxy
Authors: Sun Xin , Wang Yiping , Seewald Lucas J. , Chen Zhizhong , Shi Jian , Washington Morris A. , Lu Toh-Ming
Published: January 2017

Wurtzite (W) and zinc-blende (ZB) polytypism has long been observed in epitaxial CdS thin films. The present work, based on van der Waals epitaxial CdS thin films, is an attempt to explain which crystal modification, W or ZB, is favored under different growth conditions. In this van der Waals epitaxy system where the substrate influence is considered weak, it is found that the substrate temperature plays a crucial role in determining the crystal modification of CdS, that is, W and ZB CdS are more stable at low and high ends of substrate temperature, respectively. We attribute this temperature effect to the entropy difference (SW < SZB), a conclusion well supported by the thermodynamic hard sphere model formulation of the entropy difference between hexagonal close-packed and face-centered cubic structures. By summarizing other works, we find that the entropy difference model can also be applied to large mismatched (≳3%) CdS-substrate chemical epitaxy systems but not for small mismatched (≲3%) ones. In the latter case, the energy benefit in terms of high density of bonding contributed by the substrate-film interface is believed to be too overwhelming for the intrinsic entropy difference to overcome. Furthermore, the deposition rate is found to affect the crystalline quality and strain level in CdS films but not the crystal modification of the CdS films. Last, Raman and photoluminescence spectroscopies reveal the strain behaviors in the films. The phase change from W to ZB CdS is well-correlated with the observed peak shifts in Raman and photoluminescence spectroscopies.
Seed layer impact on structural and magnetic properties of [Co/Ni] multilayers with perpendicular magnetic anisotropy
Authors: Liu Enlong , Swerts J. , Devolder T. , Couet S. , Mertens S. , Lin T. , Spampinato V. , Franquet A. , Conard T. , Van Elshocht S. , Furnemont A. , De Boeck J. , Kar G.
Published: January 2017

[Co/Ni] multilayers with perpendicular magnetic anisotropy (PMA) have been researched and applied in various spintronic applications. Typically, the seed layer material is studied to provide the desired face-centered cubic (fcc) texture to the [Co/Ni] to obtain PMA. The integration of [Co/Ni] in back-end-of-line processes also requires the PMA to survive post-annealing. In this paper, the impact of NiCr, Pt, Ru, and Ta seed layers on the structural and magnetic properties of [Co(0.3 nm)/Ni(0.6 nm)] multilayers is investigated before and after annealing. The multilayers were deposited in-situ on different seeds via physical vapor deposition at room temperature. The as-deposited [Co/Ni] films show the required fcc(111) texture on all seeds, but PMA is only observed on Pt and Ru. In-plane magnetic anisotropy is obtained on NiCr and Ta seeds, which is attributed to strain-induced PMA loss. PMA is maintained on all seeds after post-annealing up to 400 °C. The largest effective perpendicular anisotropy energy (KUeff≈2×105 J/m3) after annealing is achieved on the NiCr seed. The evolution of PMA upon annealing cannot be explained by further crystallization during annealing or strain-induced PMA, nor can the observed magnetization loss and the increased damping after annealing. Here, we identify the diffusion of the non-magnetic materials from the seed into [Co/Ni] as the major driver of the changes in the magnetic properties. By selecting the seed and post-annealing temperature, the [Co/Ni] can be tuned in a broad range for both PMA and damping.
Graphene-based magnetoresistance device utilizing strip pattern geometry
Authors: El-Ahmar S. , Koczorowski W. , Poźniak A. A. , Kuświk P. , Strupiński W. , Czajka R.
Published: January 2017

The idea of a raster pattern magnetoresistor made of thin films of III–V compounds and a metallic layer has been known for over fifty years. Based on this knowledge, we present the construction of a magnetoresistor made of combined graphene and metallic strip patterns. The presented device is implemented using a monolayer of graphene epitaxially grown on a semi-insulating substrate. A graphene strip pattern magnetoresistor gives a promising wide range of practical applications due to its very high sensitivity combined with the mono-atomic thickness of the sensitive layer, the simplicity of realization, and a very convenient principle of sensor operation assuming only the usage of two electrical terminals.
Effect of anatomical variability in brain on transcranial magnetic stimulation treatment
Authors: Syeda F. , Magsood H. , Lee E. G. , El-Gendy A. A. , Jiles D. C. , Hadimani R. L.
Published: January 2017

Transcranial Magnetic Stimulation is a non-invasive clinical therapy used to treat depression and migraine, and shows further promise as treatment for Parkinson’s disease, Alzheimer’s disease, and other neurological disorders. However, it is yet unclear as to how anatomical differences may affect stimulation from this treatment. We use finite element analysis to model and analyze the results of Transcranial Magnetic Stimulation in various head models. A number of heterogeneous head models have been developed using MRI data of real patients, including healthy individuals as well as patients of Parkinson’s disease. Simulations of Transcranial Magnetic Stimulation performed on 22 anatomically different models highlight the differences in induced stimulation. A standard Figure of 8 coil is used with frequency 2.5 kHz, placed 5 mm above the head. We compare cortical stimulation, volume of brain tissue stimulated, specificity, and maximum E-field induced in the brain for models ranging from ages 20 to 60. Results show that stimulation varies drastically between patients of the same age and health status depending upon brain-scalp distance, which is not necessarily a linear progression with age.
Soot particle sizing based on analytical formula derived from laser-induced incandescence decay signals
Authors: Wu Jian , Chen Linghong , Yan Mingming , Wu Xuecheng , Gréhan Gérard , Cen Kefa
Published: January 2017

The laser-induced incandescence (LII) signal during a heat-conduction-dominated cooling process was used to derive an analytical formula to describe the relationship between the soot particle size and the LII signal decay time by exponential fitting. The formula was used to determine particle sizes based on the experimental LII signals at different detection wavelengths for an atmospheric C2H4/air diffusion flame. The results agree with those obtained from temporal temperature measurements. The measurements and numerical calculations demonstrate that particle sizing depends weakly on the maximum temperature in the formula within a typical heat-up temperature range. The results show that based on this formula, a compact single-color LII detection system can be used for particle sizing with low uncertainty under most practical combustion conditions, at least in cases where heat conduction is dominant and occurs in a free molecular regime during particle cooling.
Death of family members as an overlooked source of racial disadvantage in the United States
Authors: Umberson Debra , Olson Julie Skalamera , Crosnoe Robert , Liu Hui , Pudrovska Tetyana , Donnelly Rachel
Published: January 2017

Significance

Due to historical racial inequalities in the United States, including poverty, inadequate health care, and criminal victimization, black Americans die at much higher rates than white Americans. How the consequences of these elevated rates reverberate across family networks warrants attention. If blacks die at higher rates and earlier in the life course than whites, then blacks lose more loved ones from childhood through adulthood. Through the damaging effects of grief and other mechanisms, such losses are likely to undermine multiple life course outcomes. By analyzing nationally representative datasets to compare black and white Americans on the likelihood of losing family members over the life course, this study documents an intergenerational process with corrosive effects on black families and communities.
How jet lag impairs Major League Baseball performance
Authors: Song Alex , Severini Thomas , Allada Ravi
Published: January 2017

Significance

Although circadian clocks have been studied extensively in controlled laboratory settings, examining the function and misalignment of these biological clocks in natural settings has been more challenging. Here, we examined data from Major League Baseball (MLB) where players frequently travel long distances in the east–west direction. By using 20 years of MLB data, we found the effect of jet lag to be context dependent and remarkably specific. Overall, our findings demonstrate how circadian misalignment can impact specific features of human performance in natural settings.
Mechanism of catalysis, E2 recognition, and autoinhibition for the IpaH family of bacterial E3 ubiquitin ligases
Authors: Keszei Alexander F. A. , Sicheri Frank
Published: January 2017

Significance

Gram-negative pathogens use a specialized secretion system to inject effector proteins into host cells to facilitate infection. Members of the IpaH family are a conserved group of effector proteins that function in the host cell as novel E3 ubiquitin ligases. How these ligases carry out their enzymatic function and how they autoregulate remain unclear. Using targeted mutagenesis, we uncover the specific function of IpaH conserved residues in E3 Ub ligase activity, either directly in the catalytic mechanism or in the recruitment of the upstream E2 enzyme. Comparison of autoinhibitory properties between IpaH members and the HECT-class E3 ligase Smurf2 reveals that IpaH enzymes short circuit the levels of charged E2 in vitro, which has the potential to subvert host ubiquitination during pathogenesis.
Transient climate and ambient health impacts due to national solid fuel cookstove emissions
Authors: Lacey Forrest G. , Henze Daven K. , Lee Colin J. , van Donkelaar Aaron , Martin Randall V.
Published: January 2017

Significance

Widespread use of solid fuels for cooking results in a significant source of anthropogenic emissions. Of foremost concern for indoor air quality, reductions to these emissions could also impact both climate and ambient air quality. These potential cobenefits are appealing to efforts aimed at reducing cookstove emissions on national to urban scales, but have yet to be comprehensively evaluated at these scales. We thus estimate the per cookstove impacts on ambient air quality and global mean surface temperature for every individual country with significant cookstove use, considering reductions to both aerosols and long-lived greenhouse gases over the next century. This estimation provides information for policy makers evaluating climate and ambient air quality cobenefits of cookstove intervention programs worldwide.
Endosperm-based hybridization barriers explain the pattern of gene flow between
Arabidopsis lyrata
and
Arabidopsis arenosa
in Central Europe
Authors: Lafon-Placette Clément , Johannessen Ida M. , Hornslien Karina S. , Ali Mohammad F. , Bjerkan Katrine N. , Bramsiepe Jonathan , Glöckle Barbara M. , Rebernig Carolin A. , Brysting Anne K. , Grini Paul E. , Köhler Claudia
Published: January 2017

Significance

Hybrid seed lethality has been recognized and addressed by a long-standing tradition of plant-breeding research. Nevertheless, its role in evolution and speciation has been underestimated. In this study, hybrid seed lethality between
Arabidopsis lyrata
and
Arabidopsis arenosa
, two model species of growing interest in the scientific community, was investigated. This study shows that endosperm defects are sufficient to explain the direction of gene flow between the two wild species, suggesting an important role of this hybridization barrier in plant speciation. In addition, we show that natural polyploidization is involved in breaking down hybridization barriers, not only establishing them, as implied by the traditional “triploid block” concept. Our data suggest that polyploidy-mediated hybrid seed rescue, long known in artificial crosses, could play an important role in plant evolution.
Global warming precipitation accumulation increases above the current-climate cutoff scale
Authors: Neelin J. David , Sahany Sandeep , Stechmann Samuel N. , Bernstein Diana N.
Published: January 2017

Significance

Large accumulations of rainfall over a precipitation event can impact human infrastructure. Unlike precipitation intensity distributions, probability distributions for accumulations at first drop slowly with increasing size. At a certain size—the cutoff scale—the behavior regime changes, and the probabilities drop rapidly. In current climate, every region is protected from excessively large accumulations by this cutoff scale, and human activities are adapted to this. An analysis of how accumulations will change under global warming gives a natural physical interpretation for the atmospheric processes producing this cutoff, but, more importantly, yields a prediction that this cutoff scale will extend in a warmer climate, leading to vastly disproportionate increases in the probabilities of the very largest events.
Independent active and thermodynamic processes govern the nucleolus assembly in vivo
Authors: Falahati Hanieh , Wieschaus Eric
Published: January 2017

Significance

The role of thermodynamically driven processes in inherently active biological systems has daunted scientists for decades. One such conundrum emerges in the formation of membraneless organelles that, according to in vitro studies, assemble via thermodynamically driven phase separation but harbor numerous active processes within themselves. Disentangling the role of thermodynamic and active processes in their formation is, however, impossible in minimal in vitro systems of individual constituent components. In this work, we introduce a microfluidics-based temperature assay to address this question at its full complexity in vivo and use it to study the assembly of six nucleolar proteins in
Drosophila
embryos. Although four of these proteins follow the phase separation model, the recruitment of others to the nucleolus is active.
A semisynthetic organism engineered for the stable expansion of the genetic alphabet
Authors: Zhang Yorke , Lamb Brian M. , Feldman Aaron W. , Zhou Anne Xiaozhou , Lavergne Thomas , Li Lingjun , Romesberg Floyd E.
Published: January 2017

Significance

The genetic alphabet encodes all biological information, but it is limited to four letters that form two base pairs. To expand the alphabet, we developed synthetic nucleotides that pair to form an unnatural base pair (UBP), and used it as the basis of a semisynthetic organism (SSO) that stores increased information. However, the SSO grew poorly and lost the UBP under a variety of standard growth conditions. Here, using chemical and genetic approaches, we report the optimization of the SSO so that it is healthy, more autonomous, and able to store the increased information indefinitely. This SSO constitutes a stable form of semisynthetic life and lays the foundation for efforts to impart life with new forms and functions.
Ecdysone signaling underlies the pea aphid transgenerational wing polyphenism
Authors: Vellichirammal Neetha Nanoth , Gupta Purba , Hall Tannice A. , Brisson Jennifer A.
Published: January 2017

Significance

Phenotypic plasticity is common in nature, yet the mechanisms by which environmental inputs are detected and alter developmental programs are not well understood. Even less explored are the mechanisms underlying transgenerational plasticity. Here we address the problem of how asexual aphids produce winged or wingless offspring in response to external cues. We find that gene expression patterns suggest the importance of the hormone ecdysone in this polyphenism. We show that aphids injected with ecdysone or its analog produce fewer winged offspring, and aphids with inhibited ecdysone signaling produce more winged offspring. Our results provide insight into the hormonal control of alternative aphid morphs, which have long been a textbook example of polyphenism, but whose control mechanisms have long proven elusive.
Global long-range transport and lung cancer risk from polycyclic aromatic hydrocarbons shielded by coatings of organic aerosol
Authors: Shrivastava Manish , Lou Sijia , Zelenyuk Alla , Easter Richard C. , Corley Richard A. , Thrall Brian D. , Rasch Philip J. , Fast Jerome D. , Massey Simonich Staci L. , Shen Huizhong , Tao Shu
Published: January 2017

Significance

Polycyclic aromatic hydrocarbons (PAHs) adversely impact human health and ecosystems and are known to persist in the atmosphere. Despite decades of research, the mechanisms by which these PAHs persist are not well understood. Here, we combine theory and laboratory and field measurements within a global climate model to produce new insights into mechanisms that are responsible for the observed persistence of PAHs. We show that temperature- and humidity-dependent variations in effective viscosity of organic aerosol (OA) shield PAHs from chemical degradation. This OA shielding results in higher PAH concentrations at both near-urban and remote locations, leading to a fourfold increase in global lung cancer risk. Our study represents new research frontiers in terms of connecting climate-relevant OA with health-relevant PAHs.