bluuebunny/crossref_metadata_2025 huggingface dataset:
Mapping molecular binding by means of conformational dynamics measurements
Authors: do Nascimento Noelle M. , Juste-Dolz Augusto , Bueno Paulo R. , Monzó Isidro , Tejero Roberto , Lopez-Paz José L. , Maquieira Angel , Morais Sergi , Gimenez-Romero David
Published: January 2018

Protein–protein interactions are key in virtually all biological processes.
Wear and corrosion resistance of Co–P coatings: the effects of current modes
Authors: Li Ruiqian , Hou Yuanyuan , Dong Qiujing , Su Peibo , Ju Pengfei , Liang Jun
Published: January 2018

The P content in the Co–P coatings increased in the sequence of DC, PC and PRC methods. The PRC Co–P coating has better wear and corrosion resistance than DC and PC Co–P coatings.
Experimental and theoretical calculation investigation of 2,4-dichlorophenoxyacetic acid adsorption onto core–shell carbon microspheres@layered double hydroxide composites
Authors: Zhang Bo , Yuan Shiling , Sun Dejun , Li Yujiang , Wu Tao
Published: January 2018

The core–shell CMS@LDH composites were successfully synthesized and exhibited an excellent adsorption performance for 2,4-D.
PEGylated dendrimer-entrapped gold nanoparticles with low immunogenicity for targeted gene delivery
Authors: Xu Bei , Li Aijun , Hao Xinxin , Guo Rui , Shi Xiangyang , Cao Xueyan
Published: January 2018

The designed Au DENPs-PEG-FA compacts pDNA into cells to enhance gene transfection efficiency.
Changing molecular conjugation with a phenazine acceptor for improvement of small molecule-based organic electronic memory performance
Authors: Liu Quan , Zhao Caibin , Tian Guanghui , Ge Hongguang
Published: January 2018

Two small molecules with electron-accepting azobenzene or phenazine blocks, were synthesized. The experimental findings suggest that the molecule with larger conjugation may promote the memory performance by an enhanced strong charge transfer effect.
Graphene oxide as an additive to improve perovskite film crystallization and morphology for high-efficiency solar cells
Authors: Zhang Xiaonan , Ji Gengwu , Xiong Dongbin , Su Zhenhuang , Zhao Bin , Shen Kongchao , Yang Yingguo , Gao Xingyu
Published: January 2018

The quality of perovskite film has a great impact on its light absorption and carrier transport, which is vital to improve high-efficiency perovskite solar cells (PSCs).
The use of S2O82− and H2O2 as novel specific masking agents for highly selective “turn-on” fluorescent switching recognition of CN− and I− based on Hg2+–graphene quantum dots
Authors: Nuengmatcha Prawit , Sricharoen Phitchan , Limchoowong Nunticha , Mahachai Ratana , Chanthai Saksit
Published: January 2018

In this study, we report that both CN− and I− can enhance the fluorescent intensity of Hg2+–graphene quantum dots (Hg2+–GQDs).
Catalytic reactivity of an iridium complex with a proton responsive N-donor ligand in CO2hydrogenation to formate
Authors: Gunasekar Gunniya Hariyanandam , Yoon Yeahsel , Baek Il-hyun , Yoon Sungho
Published: January 2018

A bibenzimidazole ligated half-sandwich Ir complex [Cp*Ir(BiBzImH2)Cl]Cl shows superior activity than that of its bipyridine counterpart. Owing to the structural instability, the initial excellent activity of [Cp*Ir(BiBzImH2)Cl]Cl was reduced when catalytic cycle proceeds.
Evaluating students' abilities to construct mathematical models from data using latent class analysis
Authors: Brandriet Alexandra , Rupp Charlie A. , Lazenby Katherine , Becker Nicole M.
Published: January 2018

Analyzing and interpreting data is an important science practice that contributes toward the construction of models from data; yet, there is evidence that students may struggle with making meaning of data. The study reported here focused on characterizing students’ approaches to analyzing rate and concentration data in the context of method of initial rates tasks, a type of task used to construct a rate law, which is a mathematical model that relates the reactant concentration to the rate. Here, we present a large-scale analysis (n= 768) of second-semester introductory chemistry students’ responses to three open-ended questions about how to construct rate laws from initial concentration and rate data. Students’ responses were coded based on the level of sophistication in their responses, and latent class analysis was then used to identify groups (i.e.classes) of students with similar response patterns across tasks. Here, we present evidence for a five-class model that included qualitatively distinct and increasingly sophisticated approaches to reasoning about the data. We compared the results from our latent class model to the correctness of students’ answers (i.e.reaction orders) and to a less familiar task, in which students were unable to use the control of variables strategy. The results showed that many students struggled to engage meaningfully with the data when constructing their rate laws. The students’ strategies may provide insight into how to scaffold students’ abilities to analyze data.
A Janus MoSSe monolayer: a potential wide solar-spectrum water-splitting photocatalyst with a low carrier recombination rate
Authors: Ma Xiangchao , Wu Xin , Wang Haoda , Wang Yucheng
Published: January 2018

A Janus MoSSe monolayer is theoretically predicted to be a wide solar-spectrum water-splitting photocatalyst with a low carrier recombination rate.
Mannan-based conjugates as a multimodal imaging platform for lymph nodes
Authors: Rabyk M. , Galisova A. , Jiratova M. , Patsula V. , Srbova L. , Loukotova L. , Parnica J. , Jirak D. , Stepanek P. , Hruby M.
Published: January 2018

We show that mannan-based conjugates possess exceptional features for multimodal imaging because of their biocompatibility, biodegradability and self-targeting properties.
Novel dendritic large molecules as solution-processable thermally activated delayed fluorescent emitters for simple structured non-doped organic light emitting diodes
Authors: Godumala Mallesham , Choi Suna , Kim Hyung Jong , Lee Chiho , Park Sungnam , Moon Ji Su , Si Woo Kim , Kwon Jang Hyuk , Cho Min Ju , Choi Dong Hoon
Published: January 2018

The structural optimization of a TADF emissive core with suitable dendrons leads to simple structured solution processable non-doped OLEDs with superior performances.
Intermetallic Ca3Pb: a topological zero-dimensional electride material
Authors: Zhang Xiaoming , Guo Ruikang , Jin Lei , Dai Xuefang , Liu Guodong
Published: January 2018

We propose for the first time the concept and properties of topological electride materials.
A Friedländer route to 5,7-diazapentacenes
Authors: Lunchev Andrey V. , Hendrata Vincent C. , Jaggi Aparna , Morris Samuel A. , Ganguly Rakesh , Chen Xiaoxuan , Sun Handong , Grimsdale Andrew C.
Published: January 2018

New 5,7-diazapentacene-based materials have been made by means of a Friedländer reaction, which could be promising candidates for optoelectronic applications.
Synthesis of n-AlGaN nanoflowers by MOCVD for high-performance ultraviolet-C photodetectors
Authors: Kang San , Nandi R. , Kim Hyeeun , Jeong Kwang-Un , Lee Cheul-Ro
Published: January 2018

Compositionally uniform high crystalline quality Al0.45Ga0.55N nanoflowers have been synthesized by MOCVD for application in high-performance ultraviolet-C photodetectors. The photodetectors fabricated with nanoflowers displayed a photoresponsivity of ∼0.72 A W−1 along with a sensitivity of ∼40% at 2 V bias in the ultraviolet-C region.
Synergistic drug combination GC7/DFMO suppresses hypusine/spermidine-dependent eIF5A activation and induces apoptotic cell death in neuroblastoma
Authors: Schultz Chad R. , Geerts Dirk , Mooney Marie , El-Khawaja Raid , Koster Jan , Bachmann André S.
Published: January 2018

The eukaryotic initiation factor 5A (eIF5A), which contributes to several crucial processes during protein translation, is the only protein that requires activation by a unique post-translational hypusine modification. eIF5A hypusination controls cell proliferation and has been linked to cancer. eIF5A hypusination requires the enzymes deoxyhypusine synthase (DHPS) and deoxyhypusine hydroxylase and uniquely depends on the polyamine (PA) spermidine as the sole substrate. Ornithine decarboxylase (ODC) is the rate-limiting enzyme in PA biosynthesis. Both ODC and PAs control cell proliferation and are frequently dysregulated in cancer. Since only spermidine can activate eIF5A, we chose the hypusine–PA nexus as a rational target to identify new drug combinations with synergistic antiproliferative effects. We show that elevated mRNA levels of the two target enzymes DHPS and ODC correlate with poor prognosis in a large cohort of neuroblastoma (NB) tumors. The DHPS inhibitor GC7 (N1-guanyl-1,7-diaminoheptane) and the ODC inhibitor α-difluoromethylornithine (DFMO) are target-specific and in combination induced synergistic effects in NB at concentrations that were not individually cytotoxic. Strikingly, while each drug alone at higher concentrations is known to induce p21/Rb- or p27/Rb-mediated G1 cell cycle arrest, we found that the drug combination induced caspase 3/7/9, but not caspase 8-mediated apoptosis, in NB cells. Hypusinated eIF5A levels and intracellular spermidine levels correlated directly with drug treatments, signifying specific drug targeting effects. This two-pronged GC7/DFMO combination approach specifically inhibits both spermidine biosynthesis and post-translational, spermidine-dependent hypusine-eIF5A activation, offering an exciting clue for improved NB drug therapy.
160 MS/s 20 MHz bandwidth third‐order noise shaping SAR ADC
Authors: Ghaedrahmati Hanie , Zhou Jianjun
Published: January 2018

This Letter proposes an operational‐amplifier free with an embedded passive gain technique to implement an oversampling, noise shaping successive approximation register (SAR) ADCs. In the proposed scheme, the comparator noise, quantisation noise, settling errors and DAC thermal noise are alleviated. A third‐order noise shaping SAR ADC with inserted passive gain design in 40 nm CMOS technology is well suited for low power application because of using passive elements like capacitors and switches. Due to the oversampling and shaping scheme, the structure can be used for high‐speed and high‐resolution operation.
Modelling of supercapacitors based on SVM and PSO algorithms
Authors: Ding Shichuan , Hang Jun , Wei Baolei , Wang Qunjing
Published: January 2018

Supercapacitors present an attractive energy storage alternative for high‐performance applications due to their compact size and high‐power density. Therefore, the supercapacitors have broad prospects for the development in the field of electric vehicles and renewable energy. To describe the output characteristics of the supercapacitors with high accuracy for the simulation research and practical application, a dynamic modelling method is proposed for the supercapacitors based on support vector machine (SVM) and particle swarm optimisation (PSO) algorithm. In this study, the SVM is used to predict the output voltage of the supercapacitors with the key parameters (temperature, current and initial voltage). The PSO algorithm is adopted to optimise the parameters of the SVM to improve the performance of the dynamic modelling. An experimental platform is established, where an electric machine drive system powered by the supercapacitors is controlled to operate at frequent acceleration and deceleration modes, thus leading to the frequent charging and discharging of the supercapacitors. The experimental data is collected to validate the effectiveness of the proposed method. The results show that the proposed method can effectively predict the output voltage of the supercapacitors.
Secondary voltage control in islanded microgrids using event‐triggered control
Authors: Chen Meng , Xiao Xiangning
Published: January 2018

This study proposes a cooperative secondary voltage control scheme in islanded microgrids, which can be seen as multi‐agent systems with distributed generators being agents. Therefore, the voltage deviation caused by the primary control level can be compensated autonomously in a microgrid using a directed communication graph. An auxiliary centralised event‐triggered controller is designed to deal with feedback control law. In this scheme, the estimates of agents are used to replace their actual values for feedback control. All agents receive the same event‐triggered time from the auxiliary centralised controller. Thus, communication between agents is only needed when events are triggered, which highly reduces the burden of the communication network to make the control structure be more reliable. The stability analysis is also presented here. Simulation results based on an islanded microgrid test system in PSCAD/EMTDC are provided to validate the effectiveness of the proposed control strategy.
Synthesis of coupled antenna arrays using digital phase control via integer programming
Authors: Echeveste José Ignacio , González de Aza Miguel Á. , Rubio Jesús , Zapata Juan
Published: January 2018

A pattern synthesis technique for real and coupled antenna arrays by using digital phase‐only excitation weights is introduced here. The method is formulated as an integer linear programming problem incorporating a fast full‐wave analysis of the array, based on the finite element method and spherical mode expansions. The method achieves radiation patterns with specified pointing directions, main lobe widths, minimum sidelobe level, and prescribed nulls, controlled by digital phase shifters.
Modulation, control, and performance analysis of asymmetric modular multilevel converter (A‐MMC)
Authors: Srivastav Kundan , Sahoo Ashish Kumar , Iyer Kartik V. , Mohan Ned
Published: January 2018

Modular multilevel converters (MMC) have proven to be a viable candidate for high‐voltage direct current transmission systems. Here, asymmetric modular multilevel converters (A‐MMC) are introduced wherein each series connected module has two half‐bridge (HB) submodules, with asymmetric voltage rating. Compared to conventional symmetric MMCs, such systems offer the following benefits: (i) generation of four distinct voltage levels using one module; (ii) 33% lesser semiconductor and gate drive requirement; (iii) higher system efficiency; (iv) reduction in overall cost and size. A hybrid pulse‐width modulation technique generates optimised switching pulses of the A‐MMC. A novel voltage balancing algorithm is proposed to stabilise each asymmetric HB submodule at the rated voltage. Circulating current control is implemented to suppress the dominant second harmonic in the arm currents of the A‐MMC. Detailed simulations in MATLAB/Simulink are performed to validate the operation and control. A quantitative and qualitative comparison with conventional MMCs is also presented in terms of the converter losses, output voltage/current total harmonic distortion, capacitor ripple voltages, circulating currents etc.
Single‐phase multilevel inverter topologies with self‐voltage balancing capabilities
Authors: Gautam Shivam Prakash , Kumar Lalit , Gupta Shubhrata
Published: January 2018

In this study, two new structures of single‐phase hybrid multilevel inverter are proposed for both symmetrical and asymmetrical configurations that can be employed in drives and control of electrical machines and connection of renewable energy sources. The proposed configuration uses a less number of semiconductor devices and DC sources as compared with conventional and newly developed topologies which lead to a reduction in cost and installation area. The proposed topology poses a vital advantage of self‐voltage balancing of its capacitor voltage regardless of load type, load dynamics and modulation index. Also, the proposed topology is expanded in a cascaded fashion which reduces the complexity and improves the performance significantly. A wide range of comparison is done with conventional and newly developed topologies to show the superior performance of proposed topologies regarding a total number of switches and DC sources. The multi‐carrier pulse‐width modulation strategy is adopted for generating switching pulses for respective switches. A laboratory prototype is developed for testing the performance of the proposed topology for 9‐level and 17‐level inverters.
Controllable powers range and control method of DFIG for transient stability of power system
Authors: Zheng Di , Ouyang Jinxin , Xiong Xiaofu
Published: January 2018

Wind generation is increasing rapidly in the grid, which has greater impacts on the power system than ever. The impacts are more serious under grid fault. The low‐voltage ride through (LVRT) controls of doubly fed induction generators (DFIGs) may change characteristics of synchronous generators (SGs) and threaten the transient stability of power system. However, the influence on the transient stability and even the controllable powers of a DFIG has not been considered in the existing LVRT method. The contributions of the reactive power supplied by a DFIG in the oscillation process of power angle of SG were analysed. The controllable range of powers of a DFIG was researched with consideration of the rotor speed limit. An LVRT control method of a DFIG based on the controllable range was proposed to improve the transient stability of power system. Simulations show that the proposed method could enhance the power angle stability of power system under the condition of avoiding overspeed and out of service of DFIG.
Analysis of controllable capacity for electric vehicle battery swapping stations
Authors: Xie Pingping , Zhu Jizhong , Xuan Peizheng
Published: January 2018

Battery swapping is an effective way for the energy fast recharge of electric vehicles (EVs). The batteries stored in the battery swapping stations (BSSs) might be an emerging form of energy storage that can be used in the future power systems. Unlike traditional battery storage, the application of BSSs storage needs to consider the behaviour of EV users and the charging process in the BSSs. The calculation of controllable capacity (CC) plays a key role in the application of BSSs storage. This study proposes a Monte Carlo stochastic simulation method (MCSS) to estimate the CC of BSSs. The queuing problems in EV batteries swapping are simulated by the proposed MCSS method. The CC then can be obtained from the queues analysis. Simulation results demonstrate the availability of the proposed method.
Substoichiometric FeCl3 Activation of Propargyl Glycosides for the Synthesis of Disaccharides and Glycoconjugates
Authors: Zhang Jianbo , Sun Guosheng , Wu Yue , Liu Anqi , Qiu Saifeng , Zhang Wan , Wang Zhongfu
Published: January 2018

Glycosides as glycosyl donors using FeCl3 have been described. Under optimal reaction conditions, three kinds of propargyl glycosides were found to react with steroids and sugar-derived glycosyl acceptors to afford the corresponding disaccharides and glycoconjugates in good to excellent yields (66–91%). Meanwhile, the method can also realize one-pot synthesis of disaccharides, making it an effective, affordable, and green glycosylation procedure.
C-Glycosylation of Substituted β-Naphthols with Trichloroacet­imidate Glycosyl Donors
Authors: Mal Dipakranjan , Chakraborty Soumen
Published: January 2018

Several glycosyl donors have been systematically investigated for C-glycosylation of substituted β-naphthols to delineate the effect of the substituents. Whereas glycosylations of the parent 2-naphthol are smoothly achievable, those of differently substituted 2-naphthols are cumbersome. Efficiency of the glycosylation depends on the nature of both the glycosyl donors and the substituents of the arene ring. Among various glycosyl donors, trichloroacetimidate glycosyl donors are found to be superior for glycosylation with substituted 2-naphthols.
Facts zum Management der Klinischen Ernährung – eine Online-Befragung
Authors: Aubry Emilie , Mareschal Julie , Gschweitl Michaela , Zvingelis Maris , Schuetz Philipp , Stanga Zeno
Published: January 2018

Die krankheitsassoziierte Mangelernährung (KAM) stellt ein relevantes Problem dar und wird bei 20 – 60 % der hospitalisierten internistischen, geriatrischen oder chirurgischen Patienten beobachtet. Die KAM ist assoziiert mit einer Erhöhung der Morbiditäts-, der Mortalitäts- und der Komplikationsrate sowie mit einer Verschlechterung der Lebensqualität. Die frühzeitige Identifikation von Risikopatienten mittels eines validierten Screenings und die anschließende Erfassung des Ernährungsstatus sind entscheidende initiale Schritte für ein erfolgreiches Ernährungsmanagement. Anhand dieser Informationen kann ein Ernährungsplan ausgearbeitet und eine entsprechend adäquate Ernährungstherapie rasch eingeleitet werden. Die Behandlung muss überwacht, evaluiert und regelmäßig adaptiert werden, um die ernährungsmedizinischen Ziele schnellstmöglich erreichen zu können.

Das Ziel der hier vorliegenden Untersuchung ist es, die Situation der Ernährung in Schweizer Institutionen besser zu verstehen und potenzielle Barrieren aufzuzeigen, welche die Entwicklung bzw. Durchführung eines optimalen Ernährungsmanagements verhindern. Anhand dieser Ergebnisse können geeignete und gezielte Konzepte für eine potenzielle Optimierung erarbeitet werden.

Fünfzig Pflegedienstleitungen (72 % Krankenhäuser, 28 % Pflegeheime) haben eine Online-Befragung zu Funktion und Verantwortlichkeit, Erfassung und Monitoring des Ernährungszustands und zugehörigen Problemen in ihrer Institution ausgefüllt. Aus den Ergebnissen lässt sich schließen, dass schweizweite Leitlinien und Standards für das Screening, das Assessment sowie das Monitoring des Ernährungszustands sowie zu ernährungstherapeutischen Interventionen und zur Bearbeitung von Behandlungszielen bei der KAM entwickelt werden müssen.

Kontinuierliche ernährungsspezifische Aus- und Weiterbildung vom medizinischen Personal muss stattfinden und kontinuierliche Aufklärungs- und Sensibilisierungsarbeit muss bei Patienten geleistet werden, um das Bewusstsein für die Ernährung zu stärken. Zudem muss die Kommunikation zwischen den interdisziplinären und multiprofessionellen Betreuungs- und Behandlungsteams zur Bekämpfung der KAM verbessert werden.
Squid pen-inspired chitinous functional materials: Hierarchical chitin fibers by centrifugal jet-spinning and transparent chitin fiber-reinforced composite
Authors: Jeong Seung-Hwan , Kim Joong-Kwon , Lim Young-Woo , Hwang Hyun-Bin , Kwon Hee-Young , Bae Byeong-Soo , Jin Jungho
Published: January 2018

Here, inspired by the fibrous composite structure of a squid pen, we introduce hierarchical chitin fibers (herein, termed “Chiber”) and their transparent composites and demonstrate the potential of these chitinous functional materials as a sustainable separation-membrane and reinforcing filler for composites. We employ a centrifugal jet-spinning process to fabricate Chiber with aligned chitin nanofibrillar architectures, for which we discuss the processing-morphology relationship. A nonwoven fiber-mat made of Chiber exhibits excellent adsorbing performance for a toxic ionic dye (Congo Red), and has a low coefficient of thermal expansion comparable to that of glass fibers. Finally, we demonstrate a squid pen-mimetic transparent composite using Chiber and investigate its optical property.
A transportable Paul-trap for levitation and accurate positioning of micron-scale particles in vacuum for laser-plasma experiments
Authors: Ostermayr T. M. , Gebhard J. , Haffa D. , Kiefer D. , Kreuzer C. , Allinger K. , Bömer C. , Braenzel J. , Schnürer M. , Cermak I. , Schreiber J. , Hilz P.
Published: January 2018

We report on a Paul-trap system with large access angles that allows positioning of fully isolated micrometer-scale particles with micrometer precision as targets in high-intensity laser-plasma interactions. This paper summarizes theoretical and experimental concepts of the apparatus as well as supporting measurements that were performed for the trapping process of single particles.
Memory-induced acceleration and slowdown of barrier crossing
Authors: Kappler Julian , Daldrop Jan O. , Brünig Florian N. , Boehle Moritz D. , Netz Roland R.
Published: January 2018

We study the mean first-passage time τMFP for the barrier crossing of a single massive particle with non-Markovian memory by Langevin simulations in one dimension. In the Markovian limit of short memory time τΓ, the expected Kramers turnover between the overdamped (high-friction) and the inertial (low-friction) limits is recovered. Compared to the Markovian case, we find barrier crossing to be accelerated for intermediate memory time, while for long memory time, barrier crossing is slowed down and τMFP increases with τΓ as a power law τMFP∼τΓ2. Both effects are derived from an asymptotic propagator analysis: while barrier crossing acceleration at intermediate memory can be understood as an effective particle mass reduction, slowing down for long memory is caused by the slow kinetics of energy diffusion. A simple and globally accurate heuristic formula for τMFP in terms of all relevant time scales of the system is presented and used to establish a scaling diagram featuring the Markovian overdamped and the Markovian inertial regimes, as well as the non-Markovian intermediate memory time regime where barrier crossing is accelerated and the non-Markovian long memory time regime where barrier crossing is slowed down.
Electrical and impedance spectroscopy analysis of sol-gel derived spin coated Cu2ZnSnS4 solar cell
Authors: Gupta Goutam Kumar , Garg Ashish , Dixit Ambesh
Published: January 2018

We carried out electrical and impedance studies on solution derived Al:ZnO/ZnO/CdS/Cu2ZnSnS4/Mo/Glass multilayered solar cell structures to understand their impact on photovoltaic performance. The Cu2ZnSnS4 layer is synthesized on a molybdenum (Mo) coated soda lime glass substrate as an absorber and characterized intensively to optimize the absorber physical properties. The optimized Cu2ZnSnS4 is p-type with 5.8 × 1017 cm−3 hole carrier concentration. The depletion width of the junction is around 20.5 nm and the diffusion capacitance is ∼35.5 nF for these devices. We observed relatively large minority carrier life time ∼23 μs for these structures using open voltage decay analysis. The measured Cu2ZnSnS4/MoS2 and Cu2ZnSnS4/CdS interface resistances are 7.6 kΩ and 12.5 kΩ, respectively. The spatial inhomogeneities are considered and the corresponding resistance is ∼11.4 kΩ. The impedance measurements suggest that in conjunction with series resistance ∼350 Ω, the interface and spatial inhomogeneity resistances also give a significant contribution to the photovoltaic performance.
First principles centroid molecular dynamics simulation of high pressure ices
Authors: Ikeda Takashi
Published: January 2018

The nuclear quantum effects (NQEs) on the structural, elastic, electronic, and vibrational properties of high pressure ices (HPIs) VIII, VII, and X at 270 K were investigated via first principles centroid molecular dynamics (CMD). Our simulations clearly show that even at relatively high temperature of 270 K, the NQEs play a definite role in the pressure-induced proton order (ice VIII)-disorder (ice VII) transition occurring at ∼30 GPa in our H2O ice and the subsequent transition to the symmetric phase ice X suggested to occur at ∼80 GPa. The internal pressure computed at constant NVT conditions shows that the NQEs manifest themselves in the equation of state of HPIs. Our employed approach based on first principles CMD for computing vibrational spectra is proved to be able to reproduce well the overall features of the measured infrared and Raman spectra.
Note: Contrast enhancement and artifact suppression in computed tomography using sinogram normalization
Authors: Kwon Ik-Hwan , Hong Chung-Ki , Lim Jun
Published: January 2018

The intensity and direction of the incident beam at the sample position in synchrotron full-field transmission X-ray microscopy is subject to change. Incident-beam fluctuation in computed tomography results in significant contrast degradation of the reconstructed image. In the present study, we devised a simple method by which that problem could be corrected using sinogram normalization. According to our results, the image contrast was improved by 13%, and the artifacts were suppressed.
Research on the honeycomb restrain layer application to the high power microwave dielectric window
Authors: Zhang Qingyuan , Shao Hao , Huang Wenhua , Guo Letian
Published: January 2018

Dielectric window breakdown is an important problem of high power microwave radiation. A honeycomb layer can suppress the multipactor in two directions to restrain dielectric window breakdown. This paper studies the effect of the honeycomb restrain layer on improving the dielectric window power capability. It also studies the multipactor suppression mechanism by using the electromagnetic particle-in-cell software, gives the design method, and accomplishes the test experiment. The experimental results indicated that the honeycomb restrain layer can effectively improve the power capability twice.
Theoretical investigations on diamondoids (CnHm, n = 10–41): Nomenclature, structural stabilities, and gap distributions
Authors: Wang Ya-Ting , Zhao Yu-Jun , Liao Ji-Hai , Yang Xiao-Bao
Published: January 2018

Combining the congruence check and the first-principles calculations, we have systematically investigated the structural stabilities and gap distributions of possible diamondoids (CnHm) with the carbon numbers (n) from 10 to 41. A simple method for the nomenclature is proposed, which can be used to distinguish and screen the candidates with high efficiency. Different from previous theoretical studies, the possible diamondoids can be enumerated according to our nomenclature, without any pre-determination from experiments. The structural stabilities and electronic properties have been studied by density functional based tight binding and first-principles methods, where a nearly linear correlation is found between the energy gaps obtained by these two methods. According to the formation energy of structures, we have determined the stable configurations as a function of chemical potential. The maximum and minimum energy gaps are found to be dominated by the shape of diamondoids for clusters with a given number of carbon atoms, while the gap decreases in general as the size increases due to the quantum confinement.
Reinterpreting the infrared spectrum of H + HCN: Methylene amidogen radical and its coproducts
Authors: Wiens Avery E. , Copan Andreas V. , Rossomme Elliot C. , Aroeira Gustavo J. R. , Bernstein Olivia M. , Agarwal Jay , Schaefer Henry F.
Published: January 2018

The methylene amidogen radical (H2CN) plays a role in high-energy material combustion and extraterresterial atmospheres. Recent theoretical work has struggled to match experimental assignments for its CN and antisymmetric CH2 stretching frequencies (ν2 and ν5), which were reported to occur at 1725 and 3103 cm−1. Herein, we compute the vibrational energy levels of this molecule by extrapolating quadruples-level coupled-cluster theory to the complete basis limit and adding corrections for vibrational anharmonicity. This level of theory predicts that ν2 and ν5 should occur at 1646 and 2892 cm−1, at odds with the experimental assignments. To investigate the possibility of defects in our theoretical treatment, we analyze the sensitivity of our approach to each of its contributing approximations. Our analysis suggests that the observed deviation from experiment is too large to be explained as an accumulation of errors, leading us to conclude that these transitions were misassigned. To help resolve this discrepancy, we investigate possible byproducts of the H + HCN reaction, which was the source of H2CN in the original experiment. In particular, we predict vibrational spectra for cis-HCNH, trans-HCNH, and H2CNH using high-level coupled-cluster computations. Based on these results, we reassign the transition at 1725 cm−1 to ν3 of trans-HCNH, yielding excellent agreement. Supporting this identification, we assign a known contaminant peak at 886 cm−1 to ν5 of the same conformer. Our computations suggest that the peak observed at 3103 cm−1, however, does not belong to any of the aforementioned species. To facilitate further investigation, we use structure and bonding arguments to narrow the range of possible candidates. These arguments lead us to tentatively put forth formaldazine [(H2CN)2] as a suggestion for further study, which we support with additional computations.
Nonlinear stage of Benjamin-Feir instability in forced/damped deep-water waves
Authors: Armaroli Andrea , Eeltink Debbie , Brunetti Maura , Kasparian Jérôme
Published: January 2018

We study a three-wave truncation of a recently proposed damped/forced high-order nonlinear Schrödinger equation for deep-water gravity waves under the effect of wind and viscosity. The evolution of the norm (wave-action) and spectral mean of the full model are well captured by the reduced dynamics. Three regimes are found for the wind-viscosity balance: we classify them according to the attractor in the phase-plane of the truncated system and to the shift of the spectral mean. A downshift can coexist with both net forcing and damping, i.e., attraction to period-1 or period-2 solutions. Upshift is associated with stronger winds, i.e., to a net forcing where the attractor is always a period-1 solution. The applicability of our classification to experiments in long wave-tanks is verified.
Effect of porosity and tortuosity of electrodes on carbon polymer soft actuators
Authors: S Sunjai Nakshatharan , Punning Andres , Johanson Urmas , Aabloo Alvo
Published: January 2018

This work presents an electro-mechanical model and simulation of ionic electroactive polymer soft actuators with a porous carbon electrode, polymer membrane, and ionic liquid electrolyte. An attempt is made to understand the effects of specific properties of the porous electrodes such as porosity and tortuosity on the charge dynamics and mechanical performance of the actuator. The model uses porous electrode theory to study the electrochemical response of the system. The mechanical response of the whole laminate is attributed to the evolution of local stresses caused by diffusion of ions (diffusion-induced stresses or chemical stresses). The model indicates that in actuators with porous electrode, the diffusion coefficient of ions, conductivity of the electrodes, and ionic conductivity in both electrodes and separator are altered significantly. In addition, the model leads to an obvious deduction that the ions that are highly active in terms of mobility will dominate the whole system in terms of resulting mechanical deformation direction and rate of deformation. Finally, to validate the model, simulations are conducted using the finite element method, and the outcomes are compared with the experimental data. Significant effort has been put forward to experimentally measure the key parameters essential for the validation of the model. The results show that the model developed is able to well predict the behavior of the actuator, providing a comprehensive understanding of charge dynamics in ionic polymer actuator with porous electrodes.
Time-domain theory of low-Q gyrotrons with frequency-dependent reflections of output radiation
Authors: Zotova I. V. , Denisov G. G. , Ginzburg N. S. , Sergeev A. S. , Rozental R. M.
Published: January 2018

A time-domain theory of a low-Q gyrotron operating under the influence of the frequency-dependent reflections of the output radiation has been developed. The theory is based on the description of the wave propagation by a parabolic equation taking into account the reflected signal by proper modification of the boundary conditions. The developed model was applied to simulations of frequency stabilization in gyrotrons due to partial reflections of the output radiation from a resonant remote load. For the case of low-Q powerful gyrotrons, the reflected signal can significantly influence the axial field profile inside the interaction space and, correspondingly, the value of the electron orbital efficiency.
Sensitivity manipulation on micro-machined resonant electrometer toward high resolution and large dynamic range
Authors: Chen Dongyang , Zhao Jiuxuan , Wang Yong , Xu Zhonggui , Xie Jin
Published: January 2018

A micro-resonant electrometer with the scheme of sensitivity manipulation is proposed to realize the high resolution and large dynamic range based on a mechanical resonator and actuator. As the key sensing element, the double-ended tuning fork resonator has a quality factor close to 10 000 and low motional resistance below 0.5 MΩ. Electrical and mechanical nonlinear features of the resonator are investigated. The charge sensing functionality based on the axial strain modulation scheme is calibrated with a high resolution of 2.6 fC under 0.46 ppm frequency fluctuation. With the manipulation, the sensitivity is linearized from quadratic and further decreased to extend the dynamic range by 358.47% up to 12.38 pC. Meanwhile, the frequency fluctuation is also stabilized under 70 mHz to enhance the short-term stability of the sensor.
Thermoelasticity and anomalies in the pressure dependence of phonon velocities in niobium
Authors: Zou Yongtao , Li Ying , Chen Haiyan , Welch David , Zhao Yusheng , Li Baosheng
Published: January 2018

Compressional and shear wave velocities of polycrystalline niobium have been measured at simultaneously high pressures and temperatures up to 5.8 GPa and 1073 K, respectively, using ultrasonic interferometry in conjunction with synchrotron x-ray techniques. An anomalous pressure-induced softening behavior in the phonon velocities, probably owing to the topological change in the Fermi surface, has been observed at ∼4.8 GPa during cold compression, which is supported by the elasticity data from our first-principles calculations. In contrast, both the bulk (BS) and shear (G) moduli increase with pressures but decrease with temperatures upon compression at extreme P-T up to 5.8 GPa and 1073 K. Using finite strain equation-of-state approaches, the elasticity of bulk and shear moduli and their pressure and temperature dependences are derived from the directly measured velocities and densities, yielding BS0 = 174.9(3.2) GPa, G0 = 37.1(3) GPa, ∂BS/∂P = 3.97(9), ∂G/∂P = 0.83(5), ∂BS/∂T = −0.064(7) GPa/K, and ∂G/∂T = −0.012(3) GPa/K. On the basis of the current thermoelasticity data, Debye temperature and the high-pressure melting curve of Nb are derived. The origin of the anomalies in shear behavior at high pressure might be attributed to the progressive s-d electron-transfer-induced topological changes of the Fermi surface upon compression.
Fast thermometry with a proximity Josephson junction
Authors: Wang L. B. , Saira O.-P. , Pekola J. P.
Published: January 2018

We couple a proximity Josephson junction to a Joule-heated normal metal film and measure its electron temperature under steady state and nonequilibrium conditions. With a timed sequence of heating and temperature probing pulses, we are able to monitor its electron temperature in nonequilibrium with effectively zero back-action from the temperature measurement in the form of additional dissipation or thermal conductance. The experiments demonstrate the possibility of using a fast proximity Josephson junction thermometer for studying thermal transport in mesoscopic systems and for calorimetry.
Imaging spectroscopy of the missing REMPI bands of methyl radicals: Final touches on all vibrational frequencies of the 3p Rydberg states
Authors: Pan Huilin , Liu Kopin
Published: January 2018

(2 + 1) resonance-enhanced multiphoton ionization (REMPI) detection of methyl radicals, in particular that via the intermediate 3p Rydberg states, has shown to be a powerful method and thus enjoyed a wide range of applications. Methyl has six vibrational modes. Among them—including partially and fully deuterated isotopologs—four out of twenty vibrational frequencies in the intermediate 3p states have so far eluded direct spectroscopic determination. Here, by exploiting the imaging spectroscopy approach to a few judiciously selected chemical reactions, the four long-sought REMPI bands—CHD2(611), CH2D(311), CH2D(511), and CH2D(611)—are discovered, which complete the REMPI identification for probing any vibrational mode of excitation of methyl radical and its isotopologs. These results, in conjunction with those previously reported yet scattered in the literature, are summarized here for ready reference, which should provide all necessary information for further spectral assignments and future studies of chemical dynamics using this versatile REMPI scheme.
Impact of He and H relative depth distributions on the result of sequential He+ and H+ ion implantation and annealing in silicon
Authors: Cherkashin N. , Daghbouj N. , Seine G. , Claverie A.
Published: January 2018

Sequential He++H+ ion implantation, being more effective than the sole implantation of H+ or He+, is used by many to transfer thin layers of silicon onto different substrates. However, due to the poor understanding of the basic mechanisms involved in such a process, the implantation parameters to be used for the efficient delamination of a superficial layer are still subject to debate. In this work, by using various experimental techniques, we have studied the influence of the He and H relative depth-distributions imposed by the ion energies onto the result of the sequential implantation and annealing of the same fluence of He and H ions. Analyzing the characteristics of the blister populations observed after annealing and deducing the composition of the gas they contain from FEM simulations, we show that the trapping efficiency of He atoms in platelets and blisters during annealing depends on the behavior of the vacancies generated by the two implants within the H-rich region before and after annealing. Maximum efficiency of the sequential ion implantation is obtained when the H-rich region is able to trap all implanted He ions, while the vacancies it generated are not available to favor the formation of V-rich complexes after implantation then He-filled nano-bubbles after annealing. A technological option is to implant He+ ions first at such an energy that the damage it generates is located on the deeper side of the H profile.
Single charging events on colloidal particles in a nonpolar liquid with surfactant
Authors: Schreuer Caspar , Vandewiele Stijn , Brans Toon , Strubbe Filip , Neyts Kristiaan , Beunis Filip
Published: January 2018

Electrical charging of colloidal particles in nonpolar liquids due to surfactant additives is investigated intensively, motivated by its importance in a variety of applications. Most methods rely on average electrophoretic mobility measurements of many particles, which provide only indirect information on the charging mechanism. In the present work, we present a method that allows us to obtain direct information on the charging mechanism, by measuring the charge fluctuations on individual particles with a precision higher than the elementary charge using optical trapping electrophoresis. We demonstrate the capabilities of the method by studying the influence of added surfactant OLOA 11000 on the charging of single colloidal PMMA particles in dodecane. The particle charge and the frequency of charging events are investigated both below and above the critical micelle concentration (CMC) and with or without applying a DC offset voltage. It is found that at least two separate charging mechanisms are present below the critical micelle concentration. One mechanism is a process where the particle is stripped from negatively charged ionic molecules. An increase in the charging frequency with increased surfactant concentration suggests a second mechanism that involves single surfactant molecules. Above the CMC, neutral inverse micelles can also be involved in the charging process.
Slow domain reconfiguration causes power-law kinetics in a two-state enzyme
Authors: Grossman-Haham Iris , Rosenblum Gabriel , Namani Trishool , Hofmann Hagen
Published: January 2018

Significance

Dynamic disorder in enzyme catalysis due to conformational heterogeneity is widespread in nature. However, the structural origin for such conformational multiplicity is often elusive. Our results show that the opening and closing of two domains in the redox enzyme QSOX is hampered by a broad ensemble of slowly exchanging open conformations. This heterogeneity is a direct result of the disordered interdomain linker paired with interactions between the domains. Since the effective domain concentration in natural fusions of distinct modules such as in QSOX is very high, interdomain interactions can be persistent, thus resulting in slow sampling. We therefore expect that multidomain enzymes are particularly prone to catalytic disorder such as memory effects.
Cross-genus rebooting of custom-made, synthetic bacteriophage genomes in L-form bacteria
Authors: Kilcher Samuel , Studer Patrick , Muessner Christina , Klumpp Jochen , Loessner Martin J.
Published: January 2018

Significance

The unique host specificity and antimicrobial activity of bacterial viruses have inspired many diagnostic and antibacterial applications in industry, agriculture, and medicine. Because of the rise in antibiotic-resistant infections, phage therapy is a reemerging field of interest. Many restrictions that are associated with the use of native, isolated phages can be overcome by genetic engineering. Thus, efficient genome-editing tools are needed to unleash the full potential of phage therapy and biotechnology. In vitro assembly of synthetic virus genomes and the rapid isolation of corresponding phages is an important step in this direction. By using L-form bacteria as rebooting compartments of synthetic genomes, we report a simple, highly efficient, and broadly applicable technology that enables engineering of diverse phage families.
Naming, Identity, and Social Positioning in Teenagers’ Everyday Mobile Phone Interaction
Authors: Aldrin Emilia
Published: January 2018

This article analyzes how a small group of Swedish teenagers handle onomastic choices of self- and other-referencing as part of their everyday mobile phone interaction. It further discusses how the teenagers explained their views regarding online names during interviews. The data are analyzed qualitatively using theories of identity and social positioning. Results show considerable differences between onomastic strategies used for self- and other-referencing. Self-referencing names were often practical, coherent, and authentic to the offline self, while other-referencing names were more flexible, creative, and socially positioned. However, the teenagers also displayed varying individual onomastic strategies and different folk-onomastic views on the function of usernames.
Microstructure–mechanical property relationship in an Al–Mg alloy processed by constrained groove pressing-cross route
Authors: Moradpour M. , Khodabakhshi F. , Eskandari H.
Published: January 2018

The constrained groove pressing-cross route process was implemented on a commercially annealed AA5052 alloy at room temperature, with up to two passes (strain of ∼4.64) along the rolling direction and transverse direction. The results showed the formation of an ultrafine-grained structure with an average sub-grain/cell size in the 300–500 nm range. The indentation hardness and tensile strength increased significantly, up to ∼75 and 105%, respectively, and became more homogenous with a uniform and isotropic trend, as compared to the annealed alloy. According to the Hall–Petch and Taylor models used, grain refinement and increasing dislocation density were proposed as the main strengthening mechanisms. Fractographic studies revealed a ductile-fracture behaviour, with a dimpled structure proportional to the UFG structure.