bluuebunny/crossref_metadata_2025 huggingface dataset:
Plasmonics on the slope of enlightenment: the role of transition metal nitrides
Authors: Guler Urcan , Kildishev Alexander V. , Boltasseva Alexandra , Shalaev Vladimir M.
Published: November 2014

The key problem currently faced by plasmonics is related to material limitations. After almost two decades of extreme excitement and research largely based on the use of noble metals, scientists have come to a consensus on the importance of exploring alternative plasmonic materials to address application-specific challenges to enable the development of new functional devices. Such a change in motivation will undoubtedly lead to significant advancements in plasmonics technology transfer and could have a revolutionary impact on nanophotonic technologies in general. Here, we report on one of the approaches that, together with other new material platforms, mark an insightful technology-driven era for plasmonics. Our study focuses on transition metal nitrides as refractory plasmonic materials that exhibit appealing optical properties in the visible and near infrared regions, along with high temperature durability. We take heat-assisted magnetic recording as a case study for plasmonic technology and show that a titanium nitride antenna satisfies the requirements for an optically efficient, durable near field transducer paving the way to the next-generation data recording systems.
Fixation of CO2into cyclic carbonates catalyzed by ionic liquids: a multi-scale approach
Authors: Xu Bao-Hua , Wang Jin-Quan , Sun Jian , Huang Ying , Zhang Jun-Ping , Zhang Xiang-Ping , Zhang Suo-Jiang
Published: November 2014

The fixation of CO2into cyclic carbonates using the emerging ionic liquid (IL) technology is reviewed from a multi-scale viewpoint.
Electrospun TiO2 nanofiber integrated lab-on-a-disc for ultrasensitive protein detection from whole blood
Authors: Lee Won Seok , Sunkara Vijaya , Han Ja-Ryoung , Park Yang-Seok , Cho Yoon-Kyoung
Published: November 2014

From 10 μL of whole blood, full steps of an ELISA are automated to achieve femtomolar- and picomolar-level detection for C-reactive proteins and cardiac troponin I, respectively.
An electrokinetic study on tunable 3D nanochannel networks constructed by spatially controlled nanoparticle assembly
Authors: Choi Eunpyo , Kwon Kilsung , Kim Daejoong , Park Jungyul
Published: November 2014

We present a thorough experimental and theoretical analysis of nanoscale electrokinetics using ion-selective nanochannel networks formed by geometrically controlledin situself-assembled nanoparticles.
A sensitive photoelectrochemical immunoassay based on mesoporous carbon/core–shell quantum dots as donor–acceptor light-harvesting architectures
Authors: Li Rongxia , Gao Jian , Gao Picheng , Zhang Sen , Liu Yixin , Du Bin , Wei Qin
Published: November 2014

A label-free PEC biosensor based on the amplification of mesoporous conductive material and core–shell QDs as light-harvesting architecture.
Nonlinear optical behaviour of indium-phthalocyanine tethered to magnetite or silica nanoparticles
Authors: Sanusi Kayode , Stone Justin M. , Nyokong Tebello
Published: November 2014

Enhanced nonlinear optical properties (NLO) were observed for an indium phthalocyanine–magnetite nanocomposite at 532 nm compared to the performance of the bare phthalocyanine and its silica nanoparticle dyad.
Microwave-assisted preparation of 4-amino-3-cyano-5-methoxycarbonyl-N-arylpyrazoles as building blocks for the diversity-oriented synthesis of pyrazole-based polycyclic scaffolds
Authors: Corre Laurent Le , Tak-Tak Lotfi , Guillard Arthur , Prestat Guillaume , Gravier-Pelletier Christine , Busca Patricia
Published: November 2014

The obtention of 4-amino-3-cyano-N-arylpyrazoles via a μW mediated cyclization allowed the diversity oriented syntheses of various heteroyclic scaffolds.
Novel sulfonated poly(arylene ether sulfone) containing hydroxyl groups for enhanced proton exchange membrane properties
Authors: Kwon Yeonhye , Lee So Young , Hong Sukjae , Jang Jong Hyun , Henkensmeier Dirk , Yoo Sung Jong , Kim Hyoung-Juhn , Kim Sung-Hyun
Published: November 2014

We here report a new sulfonated poly(arylene ether sulfone) modified with hydroxyl side groups for a proton exchange membrane fuel cell (PEMFC).
Graft polymer growth using tandem photoinduced photoinitiator-free CuAAC/ATRP
Authors: Doran Sean , Yagci Yusuf
Published: November 2014

In this work, we describe the use of a one-pot, photoinduced but photoinitiator-free combined copper-catalyzed azide–alkyne cycloaddition (CuAAC) and atom-transfer radical polymerization (ATRP) protocol to provide a graft copolymer of polystyrene-g-poly(methyl methacrylate) (PS-g-PMMA) in good conversion and polydispersity.
Amphiphilic diselenide-containing supramolecular polymers
Authors: Tan Xinxin , Yang Liulin , Huang Zehuan , Yu Ying , Wang Zhiqiang , Zhang Xi
Published: November 2014

This communication describes the fabrication of diselenide-containing supramolecular polymers.
Wettability of graphene nanoribbon/single-walled carbon nanotube hybrid film
Authors: Fan Xiaokun , Tao Li , Deng Ya , Wang Gang , Zhang Jian , Zhao Yun , Huang Wenbin , Zhao Huiyou , Sun Lianfeng
Published: November 2014

The wettability of a GNR/SWNT hybrid film is modified when the surface part of the SWNT film is unzipped by a Zn/HCl sputtering process.
Investigation of stainless steel pickling liquor as a precursor for high Capacity battery electrode materials
Authors: Sanghvi Sheel , Pereira Nathalie , Halajko Anna , Amatucci Glenn G.
Published: November 2014

Stainless steel and battery manufacturing industries can be united for mutual economic and environmental benefits by utilizing stainless steel pickling liquor waste as a precursor for high energy iron fluoride based positive electrode materials in batteries.
Optical nanothermometer based on the calibration of the Stokes and upconverted green emissions of Er3+ ions in Y3Ga5O12 nano-garnets
Authors: León-Luis S. F. , Monteseguro V. , Rodríguez-Mendoza U. R. , Rathaiah M. , Venkatramu V. , Lozano-Gorrín A. D. , Valiente R. , Muñoz A. , Lavín V.
Published: November 2014

The temperature-dependent green luminescence of Y3Ga5O12 nano-garnets doped with different concentrations of Er3+ ions has been measured from 300 to 850 K and, in more detail, in the biological range from 292 to 335 K.
Reversible photo-induced trap formation in mixed-halide hybrid perovskites for photovoltaics
Authors: Hoke Eric T. , Slotcavage Daniel J. , Dohner Emma R. , Bowring Andrea R. , Karunadasa Hemamala I. , McGehee Michael D.
Published: November 2014

A reversible photo-induced instability has been found in mixed-halide photovoltaic perovskites that limits the open circuit voltage in solar cells.
Improving the electrochemical performance of the LiNi0.5Mn1.5O4spinel by polypyrrole coating as a cathode material for the lithium-ion battery
Authors: Gao Xuan-Wen , Deng Yuan-Fu , Wexler David , Chen Guo-Hua , Chou Shu-Lei , Liu Hua-Kun , Shi Zhi-Cong , Wang Jia-Zhao
Published: November 2014

Conductive polypyrrole (PPy)-coated LiNi0.5Mn1.5O4(LNMO) composites are applied as cathode materials in Li-ion batteries, and their electrochemical properties are explored at both room and elevated temperature.
A polymer–metal–polymer–metal heterostructure for enhanced photocatalytic hydrogen production
Authors: Zhang Yifeng , Mao Fang , Yan Hongjian , Liu Kewei , Cao Hongmei , Wu Jiagang , Xiao Dingquan
Published: November 2014

The tightly coupled heterostructure g-C3N4/Au/poly(3-hexylthiophene) (P3HT)/Pt was successfully prepared by a self-assembling method.
One-pot fabrication of multifunctional superparamagnetic attapulgite/Fe3O4/polyaniline nanocomposites served as an adsorbent and catalyst support
Authors: Mu Bin , Wang Aiqin
Published: November 2014

Multifunctional superparamagnetic attapulgite/Fe3O4/polyaniline (APT/Fe3O4/PANI) nanocomposites have been fabricated by a one-pot process using Fe(iii) as the oxidant for aniline and the precursor of Fe3O4 in the presence of attapulgite.
Novel recyclable dual-heterostructured Fe3O4@CeO2/M (M = Pt, Pd and Pt–Pd) catalysts: synergetic and redox effects for superior catalytic performance
Authors: Wang Qin , Li Yingjun , Liu Baocang , Dong Qing , Xu Guangran , Zhang Li , Zhang Jun
Published: November 2014

Catalyzed reduction of 4-nitrophenol with NaBH4 and oxidation of methanol, the Fe3O4@CeO2/M (M = Pt and Pd) dual-heterostructural catalysts manifest superior catalytic efficiency and electrocatalytic reactivity and reusability.
Interlayer dependent polarity of magnetoresistance in graphene spin valves
Authors: Iqbal M. Z. , Iqbal M. W. , Jin Xiaozhan , Hwang Changyong , Eom Jonghwa
Published: November 2014

We have studied the polarity of magnetoresistance (MR) in three types of magnetic junctions. While the NiFe/single layer graphene (SLG)/Co and NiFe/Al2O3/Co junctions showed spin valve signals with positive MR, the NiFe/Al2O3/SLG/Co junction revealed negative MR values.
Block‐wise equaliser in fast fading channels
Authors: Huang Min , Li Bing‐bing
Published: November 2014

In fast fading channel, for reducing detection complexity, a nearly banded channel is adopted in many literatures. For the sake of designing a nearly banded channel perfectly, the authors deduce the relationship between the bandwidth of the nearly banded channel matrix and normalised Doppler frequency shift under certain power of negligible intercarrier interference (ICI) coefficients. Then, in order to take account of all the ICI coefficients when the nearly banded channel matrix is divided into N blocks, a new structure of nearly banded channel matrix is proposed. On the basis of the new proposed structure, sequential detection with successive cancellation and sequential detection with optimal ordering are applied to detect the orthogonal frequency division multiplexing signals in each block. Simulation results show that although a little more computational complexity is costly, the detection methods using the proposed structure can achieve better performance than the detection methods using the original blocks.
Joint sensing and power allocation for hybrid spectrum sharing in fading channels
Authors: Zhang Yalin , Zhang Qinyu , Cao Bin
Published: November 2014

In a sensing‐based hybrid spectrum sharing paradigm, cognitive radio first performs spectrum sensing to identify primary users’ states (idle/busy) and then adapts its transmit power according to sensing outcomes and channel conditions. To investigate the capacity of such systems in fading channels, existing works modelled fading channel in transmission phase while additive white Gaussian noise channel in spectrum sensing; however, sensing channels also exhibit fading characteristics in practice. Therefore a more realistic system model with channel fading in both sensing and transmission is considered in this study. Under the new system model, spectrum sensing and power allocation are coupled in the ergodic capacity and an equivalent decoupling processing is proposed via mathematical manipulations. Further, joint sensing and power allocation over Rayleigh fading is studied under average interference and transmit power constraints. The optimal and suboptimal schemes are obtained by alternating optimisation and Lagrangian dual method. Finally, system performance is evaluated via extensive numerical simulations.
Indoor free space optics link under the weak turbulence regime: measurements and model validation
Authors: Pernice Riccardo , Andò Andrea , Cardinale Marzia , Curcio Luciano , Stivala Salvatore , Parisi Antonino , Busacca Alessandro C. , Ghassemlooy Z. , Perez Joaquin
Published: November 2014

In this study, the authors present the measurements performed on a free space optics (FSO) communications link using an indoor atmospheric chamber. In particular, the authors have generated several different optical turbulence conditions, demonstrating how even the weak turbulence regime can strongly affect the FSO link performance. The authors have carried out an in‐depth analysis of the data collected during the measurements, and calculated the turbulence strength (i.e. scintillation index and Rytov variance) and the important performance metrics (i.e. the Q‐factor and bit error rate) to evaluate the FSO link quality. Moreover, the authors have tested, for the first time, an appositely developed temporally‐correlated gamma–gamma channel model to generate the temporal irradiance fluctuations observed at the receiver. This has been accomplished by using a complete analysis tool that enables the authors to fully simulate the experimental FSO link. Finally, the authors compare the generated time‐series with the collected experimental data, showing a good agreement and thus proving the effectiveness of the model.
Swarm stability of linear time‐invariant descriptor compartmental networks
Authors: Cai Ning , Khan M. Junaid
Published: November 2014

Swarm stability is studied for descriptor compartmental networks with linear time‐invariant protocol. Compartmental network is a specific type of dynamical multi‐agent system. Necessary and sufficient conditions for both consensus and marginal swarm stability are presented, which require a joint matching between the interactive dynamics of nearest neighbouring vertices and the Laplacian spectrum of the overall network topology. Three numerical instances are provided to verify the theoretical results.
Topology optimisation‐based distributed estimation in relay assisted wireless sensor networks
Authors: Yan Jing , Chen Cailian , Luo Xiaoyuan , Liang Hao , Guan Xinping , Yang Xian
Published: November 2014

This study studies a distributed estimation problem in relay assisted wireless sensor networks (WSNs). Different from most existing works, the network consists of two kinds of nodes, that is, sensor nodes (SNs) which is capable of sensing and computing and relay nodes (RNs), which is only capable of simple data aggregation. The problem of how to coordinate two kinds of nodes to facilitate distributed estimation is challenging because of their heterogeneous capability. The authors first develop a min‐weighted rigid graph‐based topology optimisation scheme to reduce the redundancy of communication links such that the energy consumption in the relay assisted WSN can be reduced. With the optimised topology, a consensus‐based estimation algorithm is proposed for SNs and RNs, respectively. The asymptotic unbiasedness and consistency of the estimation algorithm are analysed in the presence of measurement and communication noises. The proposed method is applied to estimate the distribution of slab temperature in the hot rolling process. It is demonstrated that the topology optimisation reduces communication energy consumption, while the deployment of RNs improves temperature estimation accuracy as compared to a homogeneous WSN with SNs only.
Comparison of simplified models for voltage‐source‐inverter‐fed adjustable‐speed drive during voltage sags when the during‐event continue mode of operation is active
Authors: Bogarra Santiago , Monjo Lluis , Saura Jaume , Córcoles Felipe , Pedra Joaquin
Published: November 2014

Three simplified models for adjustable‐speed drives are compared with measurements on an actual drive where the inverter control strategy remains unaltered during the event (also known as continue mode of operation) to assess drive behaviour prediction during balanced and unbalanced sags. In particular, the models calculate the dc‐link voltage and ac line current dynamic evolution, assuming that neither the drive nor the system protection will trip. The comparison reveals minor differences in behaviour between the three models and the actual drive, although the constant current model exhibits slightly a better agreement. To verify whether differences in the simplified models remain small, extensive ranges of sags are simulated, and drive sensitivity to sag type and depth is illustrated. As the straightforward models studied predict the measured drive dynamic behaviour in severe network conditions with similar accuracy to other unnecessarily complicated models, they are very useful to reduce computational burden and overall complexity for sag immunity as well as dynamic and steady‐state network studies. On the other hand, laboratory measurements on the actual drive when the inertia ride‐through mode of operation is active illustrate that the simplified models are not valid when the inverter control strategy is modified during the sag.
Image segmentation framework based on multiple feature spaces
Authors: Liu Cong , Zhou Aimin , Wu Chunxue , Zhang Guixu
Published: November 2014

Image segmentation plays a key role in many fields such as image processing and recognition. Although various segmentation methods have been proposed in recent decades, most of these methods are based on only a single feature space. How to combine various features to image segmentation is a challenge problem. To address this problem, the authors propose to combine different features based on evolutionary multiobjective optimisation. Two optimisation objectives, which are based on colour and texture features, respectively, are therefore designed for image segmentation. The experiments show that the author's method is able to combine multiple features for image segmentation successfully.
Design of injection‐locked oscillator circuits using an HBT X‐parameters™‐based model
Authors: Rodríguez‐Testera Alejandro , Pelaez‐Perez Ana , Fernandez‐Barciela Monica , Tasker Paul J
Published: November 2014

A load independent X‐parameters‐based heterojunction bipolar transistor (HBT) model has been used for the first time in the design and behaviour prediction of injection‐locked oscillator circuits. This model has been extracted from load‐pull measurements with a large‐signal network analyser and, in order to obtain a high oscillator RF power, targeting a load impedance close to the optimum one for HBT maximum output power. A methodology is given to obtain robust injection‐locked oscillator circuits with a high‐synchronisation bandwidth. Several injection‐locked oscillator prototypes have been designed and fabricated, and their measurements compared with the simulations obtained using the X‐parameters model. Satisfactory results were obtained when the prototypes were operated as free‐running and synchronised oscillators.
Stacked microstrip antenna fed by an L‐probe for quadruple band operation
Authors: Fujimoto Takafumi , Yoshitake Yuta
Published: November 2014

A stacked patch microstrip antenna combined with a stacked ring microstrip antenna is proposed for quadruple band operation. The two antennas (a stacked patch microstrip antenna and a stacked ring microstrip antenna) are excited by an L‐probe feed. The impedance bandwidth is enhanced by using double resonance at all frequency bands. With simulations, the relationships between the antenna's geometrical parameters and operational frequencies are clarified. The operational principle for quadruple band is explained by the simulated electric currents. The antenna is designed for Wi‐Fi (2.45/5.25/5.6 GHz bands) and mobile WiMAX (3.5 GHz band).
Flat band slow light in silicon photonic crystal waveguide with large delay bandwidth product and low group velocity dispersion
Authors: Sharma Ankita , Kumar Mukesh
Published: November 2014

Flat band slow light is achieved in a silicon photonic crystal waveguide with large normalised delay bandwidth product (NDBP) while maintaining smaller values of group velocity dispersion. By altering the waveguide width through shifting the position of two rows of air holes adjacent to the waveguide, it is possible to achieve a high NDBP value. The NDBP values of 0.40, 0.41 and 0.43 over bandwidths of 11, 14 and 18 nm are, respectively, reported. Towards the applicability of the proposed slow light waveguide for buffering applications on silicon, buffering capacity as high as 140 bits can be achieved with the proposed design approach.z
Characterisation of large disturbance rotor angle and voltage stability in interconnected power networks with distributed wind generation
Authors: Meegahapola Lasantha , Littler Tim
Published: November 2014

Wind generation in highly interconnected power networks creates local and centralised stability issues based on their proximity to conventional synchronous generators and load centres. This study examines the large disturbance stability issues (i.e. rotor angle and voltage stability) in power networks with geographically distributed wind resources in the context of a number of dispatch scenarios based on profiles of historical wind generation for a real power network. Stability issues have been analysed using novel stability indices developed from dynamic characteristics of wind generation. The results of this study show that localised stability issues worsen when significant penetration of both conventional and wind generation is present because of their non‐complementary characteristics. In contrast, network stability improves when either high penetration of wind and synchronous generation is present in the network. Therefore network regions can be clustered into two distinct stability groups (i.e. superior stability and inferior stability regions). Network stability improves when a voltage control strategy is implemented at wind farms, however both stability clusters remain unchanged irrespective of change in the control strategy. Moreover, this study has shown that the enhanced fault ride‐through strategy for wind farms can improve both voltage and rotor angle stability locally, but only a marginal improvement is evident in neighbouring regions.
Sliding mode regulator for maximum power tracking and copper loss minimisation of a doubly fed induction generator
Authors: Weng Yung‐Tsai , Hsu Yuan‐Yih
Published: November 2014

Maximum power tracking and copper loss minimisation of a doubly fed induction generator (DFIG) can be achieved through the control of rotor currents. In this study, a sliding mode regulator (SMR) is presented to regulate the rotor current of a DFIG. The purpose of the SMR is to regulate the rotor current to the target commands of maximum power tracking and copper loss minimisation with stator flux orientation. The robustness to parameter variations can be accomplished by the proposed SMR when the wind turbine is subject to changing wind speed. Simulation results of the DFIG system on a 2.5 MW generator are provided and compared with a fixed‐gain proportional–integral (PI) regulator. It is observed from the simulation results that the dynamic responses achieved by the proposed SMR are more robust than those by the fixed‐gain PI regulator. The chattering effect caused by the switching function of the SMR can be reduced by an integral type SMR.
Immune Control in Hepatocellular Carcinoma Development and Progression: Role of Stromal Cells
Authors: Sprinzl Martin F. , Galle Peter R.
Published: November 2014

Immune control of hepatocellular carcinoma (HCC) is executed by effector immune cells, which efficiently eliminate malignant transformed cells. However, progression of HCC clearly documents failure of tumor immune control, which led to the concept of immune subversion by the tumor environment.

Particularly tumor-associated stromal cells cooperate within an inflammatory network, which is responsible for immune privilege. The stromal cell composition matures during tumor growth and is derived from surrounding noncancerous tissue or from circulating cells recruited to the tumor site. Therefore, immunosuppressive stromal cells represent heterogeneous cell lineages, including myeloid cells, lymphocytes, endothelial cells, and fibroblasts, which interact by direct cell contact, secretion of soluble factors, or production of extracellular matrix. As the stromal cells determine tumor immune control and clinical outcome of HCC, they represent a promising target for cancer immunotherapy.
Hepatocellular Carcinoma Screening and Diagnosis
Authors: Sherman Morris , Colombo Massimo
Published: November 2014

All the major liver disease societies have recommended screening for hepatocellular carcinoma (HCC). The target population for HCC screening has been defined by cost-efficacy analyses and by risk scores. Risk scores have been developed for patients with hepatitis B, regardless of the presence of cirrhosis, and for other patients with cirrhosis. Screening is with ultrasound; however, in Asia biomarkers are also used. The additional value of biomarkers has not been demonstrated. The ideal screening interval is 6 months; in Japan shorter intervals are used. Screening detects small lesions that require confirmation of HCC. There are radiological criteria that help determine whether a biopsy is necessary. Special stains can determine whether a lesion that closely resembles normal or dysplastic tissue is HCC. All these tools should be used in the management of patients undergoing HCC screening.
Early Hepatocellular Carcinoma on the Procrustean Bed of Ablation, Resection, and Transplantation
Authors: Lencioni Riccardo , Majno Pietro , Mazzaferro Vincenzo
Published: November 2014

In the treatment of early hepatocellular carcinoma (HCC), resection ablation and transplantation have had excellent initial success. Choices have to be based on a broad and long-term vision integrating—besides patients' interests—the community's needs and resources. In this scenario, guidelines such as the Barcelona Clinic Liver Cancer (BCLC) staging system can be viewed as a hideous frame (symbolized by the myth of Procrustes, Poseidon's son who stretched or maimed travelers to fit into his bed), or as a useful structure against which personalized or innovative treatments must be reality checked. In this article, the latter view is taken: For resection, portal hypertension must still represent a powerful caveat, particularly because of poor long-term results. Expansion of the criteria may instead be explored for multiple tumors and vascular invasion, where good indications can consistently be selected in expert surgical centers. For ablation, competitive results can be obtained although a small, but appreciable proportion of patients with early vascular invasion (∼ 10%), as they could probably benefit from anatomical resections. Conversely, ablative techniques overcoming the location and size limitations are developing and may prove competitive. For transplantation, several equivalent careful expansions of Milan's Criteria can be accepted, but as more patients have access to the waiting list—often prioritized on non-HCC indications—current allocation models prove to be insufficient, if not plainly inequitable, and should be revised.
Influence of stress on optical transitions in GaN nanorods containing a single InGaN/GaN quantum disk
Authors: Zhuang Y. D. , Bruckbauer J. , Shields P. A. , Edwards P. R. , Martin R. W. , Allsopp D. W. E.
Published: November 2014

Cathodoluminescence (CL) hyperspectral imaging has been performed on GaN nanorods containing a single InGaN quantum disk (SQD) with controlled variations in excitation conditions. Two different nanorod diameters (200 and 280 nm) have been considered. Systematic changes in the CL spectra from the SQD were observed as the accelerating voltage of the electron beam and its position of incidence are varied. It is shown that the dominant optical transition in the SQD varies across the nanorod as a result of interplay between the contributions of the deformation potential and the quantum-confined Stark effect to the transition energy as consequence of radial variation in the pseudomorphic strain.
Observations of Dicke narrowing and speed dependence in air-broadened CO2 lineshapes near 2.06 μm
Authors: Bui Thinh Q. , Long David A. , Cygan Agata , Sironneau Vincent T. , Hogan Daniel W. , Rupasinghe Priyanka M. , Ciuryło Roman , Lisak Daniel , Okumura Mitchio
Published: November 2014

Frequency-stabilized cavity ring-down spectroscopy was used to study CO2 lineshapes in the (20013) ← (00001) band centered near 2.06 μm. Two rovibrational transitions were chosen for this study to measure non-Voigt collisional effects for air-broadened lines over the pressure range of 7 kPa–28 kPa. Lineshape analysis for both lines revealed evidence of simultaneous Dicke (collisional) narrowing and speed-dependent effects that would introduce biases exceeding 2% in the retrieved air-broadening parameters if not incorporated in the modeling of CO2 lineshapes. Additionally, correlations between velocity- and phase/state changing collisions greatly reduced the observed Dicke narrowing effect. As a result, it was concluded that the most appropriate line profile for modeling CO2 lineshapes near 2.06 μm was the correlated speed-dependent Nelkin-Ghatak profile, which includes all of the physical effects mentioned above and leads to a consistent set of line shape parameters that are linear with gas pressure.
Strong-field ionization rates of linear polyenes simulated with time-dependent configuration interaction with an absorbing potential
Authors: Krause Pascal , Schlegel H. Bernhard
Published: November 2014

The strong field ionization rates for ethylene, trans 1,3-butadiene, and trans,trans 1,3,5-hexatriene have been calculated using time-dependent configuration interaction with single excitations and a complex absorbing potential (TDCIS-CAP). The calculations used the aug-cc-pVTZ basis set with a large set of diffuse functions (3 s, 2 p, 3 d, and 1 f) on each atom. The absorbing boundary was placed 3.5 times the van der Waals radius from each atom. The simulations employed a seven-cycle cosine squared pulse with a wavelength of 800 nm. Ionization rates were calculated for intensities ranging from 0.3 × 1014 W/cm2 to 3.5 × 1014 W/cm2. Ionization rates along the molecular axis increased markedly with increasing conjugation length. By contrast, ionization rates perpendicular to the molecular axis were almost independent of the conjugation length.
High-precision two-way optic-fiber time transfer using an improved time code
Authors: Wu Guiling , Hu Liang , Zhang Hao , Chen Jianping
Published: November 2014

We present a novel high-precision two-way optic-fiber time transfer scheme. The Inter-Range Instrumentation Group (IRIG-B) time code is modified by increasing bit rate and defining new fields. The modified time code can be transmitted directly using commercial optical transceivers and is able to efficiently suppress the effect of the Rayleigh backscattering in the optical fiber. A dedicated codec (encoder and decoder) with low delay fluctuation is developed. The synchronization issue is addressed by adopting a mask technique and combinational logic circuit. Its delay fluctuation is less than 27 ps in terms of the standard deviation. The two-way optic-fiber time transfer using the improved codec scheme is verified experimentally over 2 m to100 km fiber links. The results show that the stability over 100 km fiber link is always less than 35 ps with the minimum value of about 2 ps at the averaging time around 1000 s. The uncertainty of time difference induced by the chromatic dispersion over 100 km is less than 22 ps.
Green (In,Ga,Al)P-GaP light-emitting diodes grown on high-index GaAs surfaces
Authors: Ledentsov N. N. , Shchukin V. A. , Lyytikäinen J. , Okhotnikov O. , Shernyakov Yu. M. , Payusov A. S. , Gordeev N. Yu. , Maximov M. V. , Schlichting S. , Nippert F. , Hoffmann A.
Published: November 2014

We report on green (550–560 nm) electroluminescence (EL) from (Al0.5Ga0.5)0.5In0.5P-(Al0.8Ga0.2)0.5In0.5P double p-i-n heterostructures with monolayer-scale GaP insertions in the cladding layers and light-emitting diodes based thereupon. The structures are grown side-by-side on high-index and (100) GaAs substrates by molecular beam epitaxy. At moderate current densities (∼500 A/cm2), the EL intensity of the structures is comparable for all substrate orientations. Opposite to the (100)-grown strictures, the EL spectra of (211) and (311)-grown devices are shifted towards shorter wavelengths (∼550 nm at room temperature). At high current densities (>1 kA/cm2), a much higher EL intensity is achieved for the devices grown on high-index substrates. The integrated intensity of (311)-grown structures gradually saturates at current densities above 4 kA/cm2, whereas no saturation is revealed for (211)-grown structures up to the current densities above 14 kA/cm2. We attribute the effect to the surface orientation-dependent engineering of the GaP band structure, which prevents the escape of the nonequilibrium electrons into the indirect conduction band minima of the p-doped (Al0.8Ga0.2)0.5In0.5P cladding layers.
The structural and optical properties of black silicon by inductively coupled plasma reactive ion etching
Authors: Steglich Martin , Käsebier Thomas , Zilk Matthias , Pertsch Thomas , Kley Ernst-Bernhard , Tünnermann Andreas
Published: November 2014

Black Silicon nanostructures are fabricated by Inductively Coupled Plasma Reactive Ion Etching (ICP-RIE) in a gas mixture of SF6 and O2 at non-cryogenic temperatures. The structure evolution and the dependency of final structure geometry on the main processing parameters gas composition and working pressure are investigated and explained comprehensively. The optical properties of the produced Black Silicon structures, a distinct antireflection and light trapping effect, are resolved by optical spectroscopy and conclusively illustrated by optical simulations of accurate models of the real nanostructures. By that the structure sidewall roughness is found to be critical for an elevated reflectance of Black Silicon resulting from non-optimized etching processes. By analysis of a multitude of structures fabricated under different conditions, approximate limits for the range of feasible nanostructure geometries are derived. Finally, the technological applicability of Black Silicon fabrication by ICP-RIE is discussed.
Role of oxygen vacancies in resistive switching in Pt/Nb-doped SrTiO3
Authors: Park Jinho , Kwon Deok-Hwang , Park Hongwoo , Jung C. U. , Kim M.
Published: November 2014

Oxygen vacancies at the metal/oxide interface, driven by an electric field, have been considered responsible for the switching to the low-resistance state. We studied the electrical properties, along with microscopic observations, of the Pt/Nb-doped SrTiO3 (001) single-crystal system. Electron energy loss spectroscopy revealed highly accumulated oxygen vacancies at the interface in the high-resistance state, contrasting to common explanation. Higher resistance state by more oxygen vacancies was further confirmed in Pt/H2-annealed SrTiO3. These results suggest the presence of an interfacial state which dominantly determined the resistivity by changing the barrier height at the interface.
Omnidirectional and polarization insensitive nearly perfect absorber in one dimensional meta-structure
Authors: Feng Rui , Qiu Jun , Cao Yongyin , Liu Linhua , Ding Weiqiang , Chen Lixue
Published: November 2014

We design and numerically investigate an omnidirectional and polarization insensitive nearly perfect absorber in the mid-infrared regime, which is just a one dimensional metallic grating with a pair of metal–dielectric bilayer on the grating ridge. Absorption peaks of over 99% are simultaneously achieved around the wavelength of 5.73 μm for both TM and TE polarizations, and they also remain very high over a wide range of incident angle for both polarizations. According to the analysis of the electromagnetic field distributions, we attribute the nearly perfect absorption to the magnetic resonances and the cavity modes for the TM and TE polarizations, respectively, which are further confirmed by inductor-capacitor (LC) circuit model and cavity resonance condition, respectively. This simple and flexible one dimensional nearly perfect absorber is particularly desirable for various potential applications including micro-bolometers, band-stop filters and selective thermal emitters.
Observation of Rashba zero-field spin splitting in a strained germanium 2D hole gas
Authors: Morrison C. , Wiśniewski P. , Rhead S. D. , Foronda J. , Leadley D. R. , Myronov M.
Published: November 2014

We report the observation, through Shubnikov-de Haas oscillations in the magnetoresistance, of spin splitting caused by the Rashba spin-orbit interaction in a strained Ge quantum well epitaxially grown on a standard Si(001) substrate. The Shubnikov-de Haas oscillations display a beating pattern due to the spin split Landau levels. The spin-orbit parameter and Rashba spin-splitting energy are found to be 1.0 × 10−28  eVm3 and 1.4 meV, respectively. This energy is comparable to 2D electron gases in III-V semiconductors, but substantially larger than in Si, and illustrates the suitability of Ge for modulated hole spin transport devices.
The migration behaviour of European silver eels (Anguilla anguilla) released in open ocean conditions
Authors: Wysujack K. , Westerberg H. , Aarestrup K. , Trautner J. , Kurwie T. , Nagel F. , Hanel R.
Published: November 2014

Despite some recent progress, there are still large gaps of knowledge about migration routes and behaviour of European eels, Anguilla anguilla, during their long-distance oceanic migration. To achieve a better understanding of the migration behaviour, 28 large female silver eels were equipped with pop-up satellite transmitters and released at three different locations in the north-eastern Atlantic Ocean and in the Sargasso Sea. The study covers tracking periods between 7 and 92 days. The distance between release point and estimated pop-up position ranged from 40 to 1000km, the mean minimum migration speeds from 1.5 to 17.0km day–1. The eels consistently conducted distinct diel vertical movements (DVM) with daily amplitudes of more than 300m and maximum diving depths of more than 1000m. Eels released in the Sargasso Sea used greater depths and a broader temperature range than individuals released in the Atlantic Ocean closer to the European continent. At least two eels were clearly preyed upon. The transmitters ascended in a considerable range of directions from the release points. Hence, the results of the study did not allow clear conclusions about the detailed location of the spawning site and on the routes of the eels to the spawning grounds.
Deciding whether follow-up studies have replicated findings in a preliminary large-scale omics study
Authors: Heller Ruth , Bogomolov Marina , Benjamini Yoav
Published: November 2014

Significance

The use of big data is becoming a central way of discovering knowledge in modern science. Large amounts of potential findings are screened to discover the few real ones. To verify these discoveries a follow-up study is often conducted, wherein only the promising discoveries are followed up. Such follow-up studies are common in genomics, in proteomics, and in other areas where high-throughput methods are used. We show how to decide whether promising findings from the preliminary study are replicated by the follow-up study, keeping in mind that the preliminary study involved an extensive search for rare true signal in a vast amount of noise. The proposal computes a number, thervalue, to quantify the strength of replication.
Isotopic signals of summer denitrification in a northern hardwood forested catchment
Authors: Wexler Sarah K. , Goodale Christine L. , McGuire Kevin J. , Bailey Scott W. , Groffman Peter M.
Published: November 2014

Significance

Denitrification is the most poorly understood process in the terrestrial N cycle. As a result, terrestrial N budgets are wildly unbalanced and our ability to address global nitrogen pollution is fundamentally constrained. Denitrification is controlled by multiple factors, often exhibiting extraordinary variation in time and space, especially in terrestrial environments. Temperate forests regularly receive much larger inputs of precipitation N than they export in streamwater. The fate of the rest has been elusive. We present stable isotope measurements revealing extensive evidence of denitrification from temperate-forest shallow groundwater in midsummer, even as concurrent measurements of streamwater show little sign of denitrification. These measurements support the importance of a disputed nitrogen removal process and its occurrence at a previously missed time and location.
Acceleration of evolutionary spread by long-range dispersal
Authors: Hallatschek Oskar , Fisher Daniel S.
Published: November 2014

Significance

Pathogens, invasive species, rumors, or innovations spread much more quickly around the world nowadays than in previous centuries. The speedup is caused by more frequent long-range dispersal, for example via air traffic. These jumps are crucial because they can generate satellite “outbreaks” at many distant locations, thus rapidly increasing the total rate of spread. We present a simple intuitive argument that captures the resulting spreading patterns. We show that even rare long-range jumps can transform the spread of simple epidemics from wave-like to a very fast type of “metastatic” growth. More generally, our approach can be used to describe how new evolutionary variants spread and thus improves our predictive understanding of the speed of Darwinian adaptation.
Molecular insights into DNA interference by CRISPR-associated nuclease-helicase Cas3
Authors: Gong Bei , Shin Minsang , Sun Jiali , Jung Che-Hun , Bolt Edward L. , van der Oost John , Kim Jeong-Sun
Published: November 2014

Significance

Bacteria can repel invader DNA and RNA molecules by using an adaptive immunity mechanism called clustered regularly interspaced short palindromic repeats (CRISPRs)-Cas. CRISPR loci in a host genome are a repository of DNA fragments obtained from previous encounters with an invader, which can be transcribed and activated into short RNA molecules (crRNA) with sequences complementary to invader DNA or RNA. In some CRISPR-Cas systems, crRNA is assembled into a targeting complex called “Cascade” that seeks invader DNA to form an R-loop that triggers recruitment of a nuclease-helicase, Cas3, to destroy invader DNA. In this study, we show atomic resolution structures of a full-length Cas3, revealing how Cas3 coordinates binding, ATP-dependent translocation, and nuclease digestion of invader DNA.
Late Miocene episodic lakes in the arid Tarim Basin, western China
Authors: Liu Weiguo , Liu Zhonghui , An Zhisheng , Sun Jimin , Chang Hong , Wang Ning , Dong Jibao , Wang Huanye
Published: November 2014

Significance

The relative roles of the two plausible causes, Cenozoic global cooling and Tibetan Plateau uplift, for the Asian interior aridification/desertification are often difficult to disentangle. High-quality terrestrial records from the Tarim Basin document how enhanced aridification occurred over the last 7 my, from episodic lacustrine environments to the currently prevailing desert environments. During the Late Miocene–Early Pliocene period, episodic occurrences of great lakes and thus wetter climate closely corresponded to periods of high eccentricity and possibly high obliquity, suggesting that the uplifted plateau by then did not effectively block the moisture availability at optimum climatic conditions. The finally irreversible drying up of great lakes at ∼4.9 Ma could be attributed to the plateau uplift.
Directed evolution of an ultrastable carbonic anhydrase for highly efficient carbon capture from flue gas
Authors: Alvizo Oscar , Nguyen Luan J. , Savile Christopher K. , Bresson Jamie A. , Lakhapatri Satish L. , Solis Earl O. P. , Fox Richard J. , Broering James M. , Benoit Michael R. , Zimmerman Sabrina A. , Novick Scott J. , Liang Jack , Lalonde James J.
Published: November 2014

Significance

It is clear that to address climate change, the amount of CO2released into the atmosphere by industrial processes has to be reduced. Carbonic anhydrase regulates CO2in nearly every single living organism and is one of the most efficient enzymes in nature. To leverage that efficiency, a β-class carbonic anhydrase was engineered using directed evolution to withstand some of the harshest conditions associated with an industrial carbon capture process. The approach laid out can be generally applied in the development of natural enzymes for their use in industrial applications.
Asymmetrical integration of sensory information during mating decisions in grasshoppers
Authors: Clemens Jan , Krämer Stefanie , Ronacher Bernhard
Published: November 2014

Significance

Decision-making involves integrating different pieces of sensory information over time. Looking at how sensory information is weighted and integrated during a natural behavior can yield insight into the evolutionary forces shaping that behavior. Here, we investigated how female grasshoppers of the species
Chorthippus biguttulus
integrate information provided by male calling songs. Fitting a drift-diffusion model to behavioral data, we find that integration is highly asymmetrical: an unattractive song subunit far outweighs an attractive subunit. This asymmetrical integration is consistent with theories of sexual selection because it helps females avoid potentially costly interactions with unsuitable mating partners if the song belongs to another species or indicates a low-quality male; moreover, it suggests that song-based decision-making in grasshoppers is optimized by evolution.
Negamycin induces translational stalling and miscoding by binding to the small subunit head domain of the
Escherichia coli
ribosome
Authors: Olivier Nelson B. , Altman Roger B. , Noeske Jonas , Basarab Gregory S. , Code Erin , Ferguson Andrew D. , Gao Ning , Huang Jian , Juette Manuel F. , Livchak Stephania , Miller Matthew D. , Prince D. Bryan , Cate Jamie H. D. , Buurman Ed T. , Blanchard Scott C.
Published: November 2014

Significance

The identification of negamycin’s binding site within helix 34 of the small subunit head domain and the elucidation of its mechanism of action during messenger RNA decoding provide a physical framework for exploring structure–activity relationships of this largely unexplored antibiotic class. These findings lay the foundation for the rational design of improved negamycin analogs that may one day serve as potent antibacterial agents in the clinic.
Genetic activation of pyruvate dehydrogenase alters oxidative substrate selection to induce skeletal muscle insulin resistance
Authors: Rahimi Yasmeen , Camporez João-Paulo G. , Petersen Max C. , Pesta Dominik , Perry Rachel J. , Jurczak Michael J. , Cline Gary W. , Shulman Gerald I.
Published: November 2014

Significance

Defects in mitochondrial substrate selection, mediated by inhibition of the pyruvate dehydrogenase complex (PDH), have been proposed to be a major contributor to lipid-induced muscle insulin resistance. To examine this hypothesis, we assessed insulin action in a genetic mouse model of constitutive PDH activation. Surprisingly, we found that preferential glucose oxidation in skeletal muscle in this mouse was accompanied by muscle insulin resistance. Muscle insulin resistance could be attributed to increased glucose oxidation at the expense of reduced fatty acid oxidation, leading to increased intramyocellular lipid accumulation and diacylglycerol-PKC-θ–mediated reductions in proximal insulin signaling. These findings have important clinical implications for novel antidiabetic therapies currently in development that activate PDH and enhance glucose oxidation in muscle.
Basal and β-adrenergic regulation of the cardiac calcium channel Ca
V
1.2 requires phosphorylation of serine 1700
Authors: Fu Ying , Westenbroek Ruth E. , Scheuer Todd , Catterall William A.
Published: November 2014

Significance

The heart contracts more forcefully in response to fear, stress, or exercise through the fight-or-flight response. This physiological process is mediated by β-adrenergic receptors acting through adenylyl cyclase, cAMP, and cAMP-dependent protein kinase (PKA), which phosphorylates the cardiac calcium channel Ca
V
1.2 and increases its activity. We show that mutation of a single amino acid residue, Ser-1700, in a PKA phosphorylation site at the interface between the distal and proximal C-terminal domains substantially disrupts this regulatory mechanism in mice. Basal and β-adrenergic–stimulated calcium currents, myocyte contractility, and stress-induced exercise capacity are all reduced. Moreover, these mice develop cardiac hypertrophy, an indication of failure of cardiac homeostasis in vivo. Evidently, phosphorylation of Ser-1700 is a primary event in cardiovascular regulation.