bluuebunny/crossref_metadata_2025 huggingface dataset:
TMEM166/EVA1A interacts with ATG16L1 and induces autophagosome formation and cell death
Authors: Hu Jia , Li Ge , Qu Liujing , Li Ning , Liu Wei , xia Dan , Hongdu Beiqi , Lin Xin , Xu Chentong , Lou Yaxin , He Qihua , Ma Dalong , Chen Yingyu
Published: August 2016

The formation of the autophagosome is controlled by an orderly action of ATG proteins. However, how these proteins are recruited to autophagic membranes remain poorly clarified. In this study, we have provided a line of evidence confirming that EVA1A (eva-1 homolog A)/TMEM166 (transmembrane protein 166) is associated with autophagosomal membrane development. This notion is based on dotted EVA1A structures that colocalize with ZFYVE1, ATG9, LC3B, ATG16L1, ATG5, STX17, RAB7 and LAMP1, which represent different stages of the autophagic process. It is required for autophagosome formation as this phenotype was significantly decreased in EVA1A-silenced cells and Eva1a KO MEFs. EVA1A-induced autophagy is independent of the BECN1-PIK3C3 (phosphatidylinositol 3-kinase, catalytic subunit type 3) complex but requires ATG7 activity and the ATG12–ATG5/ATG16L1 complex. Here, we present a molecular mechanism by which EVA1A interacts with the WD repeats of ATG16L1 through its C-terminal and promotes ATG12–ATG5/ATG16L1 complex recruitment to the autophagic membrane and enhances the formation of the autophagosome. We also found that both autophagic and apoptotic mechanisms contributed to EVA1A-induced cell death while inhibition of autophagy and apoptosis attenuated EVA1A-induced cell death. Overall, these findings provide a comprehensive view to our understanding of the pathways involved in the role of EVA1A in autophagy and programmed cell death.
Australian human and parrot Chlamydia psittaci strains cluster within the highly virulent 6BC clade of this important zoonotic pathogen
Authors: Branley James , Bachmann Nathan L. , Jelocnik Martina , Myers Garry S. A. , Polkinghorne Adam
Published: August 2016

Chlamydia psittaci is an avian pathogen and zoonotic agent of atypical pneumonia. The most pathogenic C. psittaci strains cluster into the 6BC clade, predicted to have recently emerged globally. Exposure to infected parrots is a risk factor with limited evidence also of an indirect exposure risk. Genome sequencing was performed on six Australian human and a single avian C. psittaci strain isolated over a 9 year period. Only one of the five human patients had explicit psittacine contact. Genomics analyses revealed that the Australian C. psittaci strains are remarkably similar, clustering tightly within the C. psittaci 6BC clade suggested to have been disseminated by South America parrot importation. Molecular clock analysis using the newly sequenced C. psittaci genomes predicted the emergence of the 6BC clade occurring approximately 2,000 years ago. These findings reveal the potential for an Australian natural reservoir of C. psittaci 6BC strains. These strains can also be isolated from seriously ill patients without explicit psittacine contact. The apparent recent and global spread of C. psittaci 6BC strains raises important questions over how this happened. Further studies may reveal whether the dissemination of this important zoonotic pathogen is linked to Australian parrot importation rather than parrots from elsewhere.
HDL subfractions and very early CAD: novel findings from untreated patients in a Chinese cohort
Authors: Zhang Yan , Zhu Cheng-Gang , Xu Rui-Xia , Li Sha , Li Xiao-Lin , Guo Yuan-Lin , Wu Na-Qiong , Gao Ying , Qing Ping , Cui Chuan-Jue , Sun Jing , Li Jian-Jun
Published: August 2016

Coronary artery disease (CAD) in very young individuals is a rare disease associated with poor prognosis. However, the role of specific lipoprotein subfractions in very young CAD patients (≤45 years) is not established yet. A total of 734 consecutive CAD subjects were enrolled and were classified as very early (n = 81, ≤45), early (n = 304, male: 45–55; female: 45–65) and late (n = 349, male: >55; female: >65) groups. Meanwhile, a group of non-CAD subjects were also enrolled as controls (n = 56, ≤45). The lipoprotein separation was performed using Lipoprint System. As a result, the very early CAD patients have lower large high-density lipoprotein (HDL) subfraction and higher small low-density lipoprotein (LDL) subfraction (p < 0.05). Although body mass index was inversely related to large HDL subfraction, overweight did not influence its association with very early CAD. In the logistic regression analysis, large HDL was inversely [OR 95% CI: 0.872 (0.825–0.922)] while small LDL was positively [1.038 (1.008–1.069)] related to very early CAD. However, after adjusting potential confounders, the association was only significant for large HDL [0.899 (0.848–0.954)]. This study firstly demonstrated that large HDL subfraction was negatively related to very early CAD suggestive of its important role in very early CAD incidence.
Boron isotope fractionation in magma via crustal carbonate dissolution
Authors: Deegan Frances M. , Troll Valentin R. , Whitehouse Martin J. , Jolis Ester M. , Freda Carmela
Published: August 2016

Carbon dioxide released by arc volcanoes is widely considered to originate from the mantle and from subducted sediments. Fluids released from upper arc carbonates, however, have recently been proposed to help modulate arc CO2 fluxes. Here we use boron as a tracer, which substitutes for carbon in limestone, to further investigate crustal carbonate degassing in volcanic arcs. We performed laboratory experiments replicating limestone assimilation into magma at crustal pressure-temperature conditions and analysed boron isotope ratios in the resulting experimental glasses. Limestone dissolution and assimilation generates CaO-enriched glass near the reaction site and a CO2-dominated vapour phase. The CaO-rich glasses have extremely low δ11B values down to −41.5‰, reflecting preferential partitioning of 10B into the assimilating melt. Loss of 11B from the reaction site occurs via the CO2 vapour phase generated during carbonate dissolution, which transports 11B away from the reaction site as a boron-rich fluid phase. Our results demonstrate the efficacy of boron isotope fractionation during crustal carbonate assimilation and suggest that low δ11B melt values in arc magmas could flag shallow-level additions to the subduction cycle.
Asymmetry-induced resistive switching in Ag-Ag2S-Ag memristors enabling a simplified atomic-scale memory design
Authors: Gubicza Agnes , Manrique Dávid Zs. , Pósa László , Lambert Colin J. , Mihály György , Csontos Miklós , Halbritter András
Published: August 2016

Prevailing models of resistive switching arising from electrochemical formation of conducting filaments across solid state ionic conductors commonly attribute the observed polarity of the voltage-biased switching to the sequence of the active and inert electrodes confining the resistive switching memory cell. Here we demonstrate stable switching behaviour in metallic Ag-Ag2S-Ag nanojunctions at room temperature exhibiting similar characteristics. Our experimental results and numerical simulations reveal that the polarity of the switchings is solely determined by the geometrical asymmetry of the electrode surfaces. By the lithographical design of a proof of principle device we demonstrate the merits of simplified fabrication of atomic-scale, robust planar Ag2S memory cells.
The environmental carcinogen benzo[a]pyrene induces a Warburg-like metabolic reprogramming dependent on NHE1 and associated with cell survival
Authors: Hardonnière Kévin , Saunier Elise , Lemarié Anthony , Fernier Morgane , Gallais Isabelle , Héliès-Toussaint Cécile , Mograbi Baharia , Antonio Samantha , Bénit Paule , Rustin Pierre , Janin Maxime , Habarou Florence , Ottolenghi Chris , Lavault Marie-Thérèse , Benelli Chantal , Sergent Odile , Huc Laurence , Bortoli Sylvie , Lagadic-Gossmann Dominique
Published: August 2016

Cancer cells display alterations in many cellular processes. One core hallmark of cancer is the Warburg effect which is a glycolytic reprogramming that allows cells to survive and proliferate. Although the contributions of environmental contaminants to cancer development are widely accepted, the underlying mechanisms have to be clarified. Benzo[a]pyrene (B[a]P), the prototype of polycyclic aromatic hydrocarbons, exhibits genotoxic and carcinogenic effects and it is a human carcinogen according to the International Agency for Research on Cancer. In addition to triggering apoptotic signals, B[a]P may induce survival signals, both of which are likely to be involved in cancer promotion. We previously suggested that B[a]P-induced mitochondrial dysfunctions, especially membrane hyperpolarization, might trigger cell survival signaling in rat hepatic epithelial F258 cells. Here, we further characterized these dysfunctions by focusing on energy metabolism. We found that B[a]P promoted a metabolic reprogramming. Cell respiration decreased and lactate production increased. These changes were associated with alterations in the tricarboxylic acid cycle which likely involve a dysfunction of the mitochondrial complex II. The glycolytic shift relied on activation of the Na+/H+ exchanger 1 (NHE1) and appeared to be a key feature in B[a]P-induced cell survival related to changes in cell phenotype (epithelial-to-mesenchymal transition and cell migration).
Wrinkled silica/titania nanoparticles with tunable interwrinkle distances for efficient utilization of photons in dye-sensitized solar cells
Authors: Kang Jin Soo , Lim Joohyun , Rho Won-Yeop , Kim Jin , Moon Doo-Sik , Jeong Juwon , Jung Dongwook , Choi Jung-Woo , Lee Jin-Kyu , Sung Yung-Eun
Published: August 2016

Efficient light harvesting is essential for the realization of high energy conversion efficiency in dye-sensitized solar cells (DSCs). State-of-the-art mesoporous TiO2 photoanodes fall short for collection of long-wavelength visible light photons, and thus there have been efforts on introduction of scattering nanoparticles. Herein, we report the synthesis of wrinkled silica/titania nanoparticles with tunable interwrinkle distances as scattering materials for enhanced light harvesting in DSCs. These particles with more than 20 times larger specific surface area (>400 m2/g) compared to the spherical scattering particles (<20 m2/g) of the similar sizes gave rise to the dye-loading amounts, causing significant improvements in photocurrent density and efficiency. Moreover, dependence of spectral scattering properties of wrinkled particles on interwrinkle distances, which was originated from difference in overall refractive indices, was observed.
Evolutionary dynamics of selfish DNA explains the abundance distribution of genomic subsequences
Authors: Sheinman Michael , Ramisch Anna , Massip Florian , Arndt Peter F.
Published: August 2016

Since the sequencing of large genomes, many statistical features of their sequences have been found. One intriguing feature is that certain subsequences are much more abundant than others. In fact, abundances of subsequences of a given length are distributed with a scale-free power-law tail, resembling properties of human texts, such as Zipf’s law. Despite recent efforts, the understanding of this phenomenon is still lacking. Here we find that selfish DNA elements, such as those belonging to the Alu family of repeats, dominate the power-law tail. Interestingly, for the Alu elements the power-law exponent increases with the length of the considered subsequences. Motivated by these observations, we develop a model of selfish DNA expansion. The predictions of this model qualitatively and quantitatively agree with the empirical observations. This allows us to estimate parameters for the process of selfish DNA spreading in a genome during its evolution. The obtained results shed light on how evolution of selfish DNA elements shapes non-trivial statistical properties of genomes.
Sound tuning of amygdala plasticity in auditory fear conditioning
Authors: Park Sungmo , Lee Junuk , Park Kyungjoon , Kim Jeongyeon , Song Beomjong , Hong Ingie , Kim Jieun , Lee Sukwon , Choi Sukwoo
Published: August 2016

Various auditory tones have been used as conditioned stimuli (CS) for fear conditioning, but researchers have largely neglected the effect that different types of auditory tones may have on fear memory processing. Here, we report that at lateral amygdala (LA) synapses (a storage site for fear memory), conditioning with different types of auditory CSs (2.8 kHz tone, white noise, FM tone) recruits distinct forms of long-term potentiation (LTP) and inserts calcium permeable AMPA receptor (CP-AMPAR) for variable periods. White noise or FM tone conditioning produced brief insertion (<6 hr after conditioning) of CP-AMPARs, whereas 2.8 kHz tone conditioning induced more persistent insertion (≥6 hr). Consistently, conditioned fear to 2.8 kHz tone but not to white noise or FM tones was erased by reconsolidation-update (which depends on the insertion of CP-AMPARs at LA synapses) when it was performed 6 hr after conditioning. Our data suggest that conditioning with different auditory CSs recruits distinct forms of LA synaptic plasticity, resulting in more malleable fear memory to some tones than to others.
Polarization-dependent fluorescence correlation spectroscopy for studying structural properties of proteins in living cell
Authors: Oura Makoto , Yamamoto Johtaro , Ishikawa Hideto , Mikuni Shintaro , Fukushima Ryousuke , Kinjo Masataka
Published: August 2016

Rotational diffusion measurement is predicted as an important method in cell biology because the rotational properties directly reflect molecular interactions and environment in the cell. To prove this concept, polarization-dependent fluorescence correlation spectroscopy (pol-FCS) measurements of purified fluorescent proteins were conducted in viscous solution. With the comparison between the translational and rotational diffusion coefficients obtained from pol-FCS measurements, the hydrodynamic radius of an enhanced green fluorescent protein (EGFP) was estimated as a control measurement. The orientation of oligomer EGFP in living cells was also estimated by pol-FCS and compared with Monte Carlo simulations. The results of this pol-FCS experiment indicate that this method allows an estimation of the molecular orientation using the characteristics of rotational diffusion. Further, it can be applied to analyze the degree of molecular orientation and multimerization or detection of tiny aggregation of aggregate-prone proteins.
Electronic Properties of Metal Halide Perovskites
Authors: Even Jacky , Pedesseau Laurent , Sapori Daniel , Rolland Alain , Kepenekian Mikaël , Katan Claudine
Published: August 2016

This chapter summarizes our current understanding of the electronic properties and related excitations of metal-halide perovskites with particular reference to concept and tools already well deployed in the field of conventional semiconductors and optoelectronics, including the intensive use of group theory. This helps to bring out the most distinctive features that make hybrid, and to a less extend all-inorganic metal-halide perovskites, a new and distinct class of semiconductors. The pseudocubic phase serves as a reference structure and many effects, such as strain, phase transitions, relativistic effects, local distortions due to the organic cations, loss of inversion symmetry, etc., can be considered as perturbations to this reference. Brillouin zone folding is shown to afford a simple yet effective tool to unravel the apparent complexity of electronic properties. The importance of spin–orbit coupling is particularly emphasized as it has a dramatic influence not only through its strength but also by alteration of the symmetry selection rules. Issues related to the nature of electronic excitation and charge carriers, as well as their possible coupling to atomic collective (phonons) or localized (polaron) modes are discussed, as well as non-radiative Auger effects.
First Principles Modeling of Perovskite Solar Cells: Interplay of Structural, Electronic and Dynamical Effects
Authors: Mosconi Edoardo , Quarti Claudio , De Angelis Filippo
Published: August 2016

The impressive surge of perovskite solar cells has been accompanied by a comparable effort to unveil the basics properties of this class of materials. Theoretical and computational modeling is playing a major role in providing scientists an in depth atomistic view of the intimate perovskite properties contributing to the success of this class of materials. In this chapter we discuss recent advances in our understanding of organohalide perovskites based on first principles calculations and molecular dynamics simulations. Emphasis is placed on the interplay of electronic and structural features and on the important role of the organic cation and of its dynamics in dictating the peculiar material’s properties. The role of chlorine doping in methylammonium lead iodide and of interfaces with TiO2 in solar cells models are finally described.
An experimental study on the influence of trace impurities on ionization of atmospheric noble gas dielectric barrier discharges
Authors: Klute F. D. , Schütz A. , Michels A. , Vadla C. , Veza D. , Horvatic V. , Franzke J.
Published: August 2016

Penning Ionisation of N2+ by collisions with of N2 with HeM and [C3H8]+ by collisions of C3H8 with ArM.
Why metal–oxos react with dihydroanthracene and cyclohexadiene at comparable rates, despite having different C–H bond strengths. A computational study
Authors: Klein Johannes E. M. N. , Dereli Büsra , Que Lawrence , Cramer Christopher J.
Published: August 2016

Although 1,4-cyclohexadiene has a C–H bond ∼3.5 kcal mol−1 weaker than that of 9,10-dihydroanthracene, they react with metal–oxo oxidants at comparable rates due to favorable non-covalent interactions for the latter.
Analyte-directed formation of emissive excimers for the selective detection of polyamines
Authors: Kim Tae-Il , Kim Youngmi
Published: August 2016

A convenient and selective method for the sensing of polyamines, which are important biomarkers for cancers, has been developed. The fluorescence light-up mechanism utilizes the analyte-induced formation of emissive excimers of a sulfonated probe. Detection is achieved in aqueous media and artificial urine samples, as indicated by an excellent fluorescence turn-on signal with a large spectral shift.
Correction: DNA-catalyzed glycosylation using aryl glycoside donors
Authors: Hesser Anthony R. , Brandsen Benjamin M. , Walsh Shannon M. , Wang Puzhou , Silverman Scott K.
Published: August 2016

Correction for ‘DNA-catalyzed glycosylation using aryl glycoside donors’ by Anthony R. Hesser et al., Chem. Commun., 2016, 52, 9259–9262.
Correction: A narrow amide I vibrational band observed by sum frequency generation spectroscopy reveals highly ordered structures of a biofilm protein at the air/water interface
Authors: Wang Zhuguang , Morales-Acosta M. Daniela , Li Shanghao , Liu Wei , Kanai Tapan , Liu Yuting , Chen Ya-Na , Walker Frederick J. , Ahn Charles H. , Leblanc Roger M. , Yan Elsa C. Y.
Published: August 2016

Correction for ‘A narrow amide I vibrational band observed by sum frequency generation spectroscopy reveals highly ordered structures of a biofilm protein at the air/water interface’ by Zhuguang Wang et al., Chem. Commun., 2016, 52, 2956–2959.
Revisiting AgCrSe2as a promising thermoelectric material
Authors: Wu Di , Huang Sizhao , Feng Dan , Li Bing , Chen Yuexing , Zhang Jian , He Jiaqing
Published: August 2016

Superionic AgCrSe2shows a “non-superionic” specific heat and a reversible decomposition process above 723 K.
Peptide self-assembly: thermodynamics and kinetics
Authors: Wang Juan , Liu Kai , Xing Ruirui , Yan Xuehai
Published: August 2016

This review is focused on thermodynamic and kinetic contributions to the self-assembly and structural regulation of representative peptide building blocks.
A rapid, instrument-free, sample-to-result nucleic acid amplification test
Authors: Lafleur Lisa K. , Bishop Joshua D. , Heiniger Erin K. , Gallagher Ryan P. , Wheeler Maxwell D. , Kauffman Peter , Zhang Xiaohong , Kline Enos C. , Buser Joshua R. , Kumar Sujatha , Byrnes Samantha A. , Vermeulen Nicolaas M. J. , Scarr Noah K. , Belousov Yevgeniy , Mahoney Walt , Toley Bhushan J. , Ladd Paula D. , Lutz Barry R. , Yager Paul
Published: August 2016

This diagnostic system prototype is the first demonstration of a fully integrated, simple-to-use nucleic acid amplification test device.
One-step solvothermal synthesis of carbon doped TiO2–MoS2heterostructure composites with improved visible light catalytic activity
Authors: Ali Mohamed Mukthar , Sandhya Karunakaran Nair Yesodha
Published: August 2016

TiO2–MoS2composites are prepared from a novel molybdenum–sulphur cluster, (NH4)2Mo3S13·2H2O, and TiOP. A composite with 0.7% loaded MoS2showed enhanced visible light photodegradation properties.
Microwave-assisted hydrothermal synthesis of UV-emitting carbon dots from tannic acid
Authors: Joseph Julin , Anappara Aji A.
Published: August 2016

UV-photoluminescent carbon dots were synthesized through a facile process and were used as fluorophores for the highly selective and sensitive detection of picric acid.
A new glass-forming molecule having a fluorene skeleton: synthesis and conversion to the polymer with a low dielectric constant, high hydrophobicity and thermostability
Authors: Wang Yuanqiang , Wang Jiajia , Jin Kaikai , Sun Jing , Fang Qiang
Published: August 2016

A new glass-forming molecule having a fluorene skeleton and thermally cross-linkable trifluorovinyl-ether side chains is reported here.
Efficient biodiesel production via solid superacid catalysis: a critical review on recent breakthrough
Authors: Alaba Peter Adeniyi , Sani Yahaya Muhammad , Ashri Wan Daud Wan Mohd
Published: August 2016

Biodiesel produced from triglycerides and/or free fatty acids (FFAs) by transesterification and esterification has attracted immense attention during the past decades as a biodegradable, renewable and sustainable fuel.
Low variability of single-molecule conductance assisted by bulky metal–molecule contacts
Authors: Ferradás Rubén R. , Marqués-González Santiago , Osorio Henrry M. , Ferrer Jaime , Cea Pilar , Milan David C. , Vezzoli Andrea , Higgins Simon J. , Nichols Richard J. , Low Paul J. , García-Suárez Víctor M. , Martín Santiago
Published: August 2016

A detailed study of the trimethylsilylethynyl moiety, –CCSiMe3 (TMSE), as an anchoring group, using a combination of experiment and DFT is presented.
Graphene oxide nanohybrid that photoreleases nitric oxide
Authors: Marino Nino , Petralia Salvatore , Perez-Lloret Marta , Mosinger Jiri , Conoci Sabrina , Sortino Salvatore
Published: August 2016

Covalent functionalization of graphene oxide with a suitable NO photodonor leads to a nanohybrid material that releases NO under visible light and has potential applications in biomedical research.
Doxorubicin impairs cardiomyocyte viability by suppressing transcription factor EB expression and disrupting autophagy
Authors: Bartlett Jordan J. , Trivedi Purvi C. , Yeung Pollen , Kienesberger Petra C. , Pulinilkunnil Thomas
Published: August 2016

Doxorubicin (DOX) is an effective anti-cancer agent. However, DOX treatment increases patient susceptibility to dilated cardiomyopathy. DOX predisposes cardiomyocytes to insult by suppressing mitochondrial energy metabolism, altering calcium flux, and disrupting proteolysis and proteostasis. Prior studies have assessed the role of macroautophagy in DOX cardiotoxicity; however, limited studies have examined whether DOX mediates cardiac injury through dysfunctions in inter- and/or intra-lysosomal signaling events. Lysosomal signaling and function is governed by transcription factor EB (TFEB). In the present study, we hypothesized that DOX caused myocyte injury by impairing lysosomal function and signaling through negative regulation of TFEB. Indeed, we found that DOX repressed cellular TFEB expression, which was associated with impaired cathepsin proteolytic activity across in vivo, ex vivo, and in vitro models of DOX cardiotoxicity. Furthermore, we observed that loss of TFEB was associated with reduction in macroautophagy protein expression, inhibition of autophagic flux, impairments in lysosomal cathepsin B activity, and activation of cell death. Restoration and/or activation of TFEB in DOX-treated cardiomyocytes prevented DOX-induced suppression of cathepsin B activity, reduced DOX-mediated reactive oxygen species (ROS) overproduction, attenuated activation of caspase-3, and improved cellular viability. Collectively, loss of TFEB inhibits lysosomal autophagy, rendering cardiomyocytes susceptible to DOX-induced proteotoxicity and injury. Our data reveal a novel mechanism wherein DOX primes cardiomyocytes for cell death by depleting cellular TFEB.
Adaptive busbar differential relaying scheme during saturation period of current transformers based on alienation concept
Authors: Allah Ragab Abd
Published: August 2016

This study presents an advanced technique provided with adaptive differential relay characteristics for avoiding current transformer (CT) saturation effects. The proposed technique uses the alienation and differential protection principles to make adaptive logic; if no CT saturation is detected, the differential principle alone is capable of tripping the busbar. If CT saturation is detected, both the alienation and differential principles must pickup in order to trip. The alienation coefficient is useful in CT saturation detection, evaluation of CT saturation degree and adapting the differential relay characteristics during saturation period of CTs to avoid false operation in the event of external faults. The differential current and alienation coefficient are calculated from two terminal currents of the busbar. The proposed protective scheme has several attractive features, including the simplicity of on‐line implementation, not affected by the remanent flux in the CT core, and it is independent of the CT parameters/characteristics and secondary burden. A real 19.57 kV busbar is simulated using Alternate Transients Program/Electro‐Magnetic Transient Program and MATLAB packages to examine the suggested scheme under different types of faults. Under normal operating conditions and external faults, the scheme remains stable and it operates only for the case of internal faults. Moreover, it is unaffected by CT saturation.
Introduction to PRO for energy conversion applications including an electric equivalent circuit
Authors: Maisonneuve Jonathan , Pillay Pragasen
Published: August 2016

Pressure retarded osmosis (PRO) is a renewable energy conversion process with potential for sustainable power production. This study introduces this resource to the electrical engineering community and presents the first electric equivalent circuit of the process. This provides a useful tool for integrated osmotic power plant analysis and design. The model illustrates the influence of several important non‐ideal effects on power output including concentration polarisation, spatial variation, and pressure drop. The dynamic influence of salt storage by water is also considered. The influence of feed and draw input currents and hydraulic load on power output are investigated and suggest that there is some operating point that will yield maximum power. This illustrates the need for maximum power point tracking in PRO energy conversion.
Synchronizing noisy nonidentical oscillators by transient uncoupling
Authors: Tandon Aditya , Schröder Malte , Mannattil Manu , Timme Marc , Chakraborty Sagar
Published: August 2016

Synchronization is the process of achieving identical dynamics among coupled identical units. If the units are different from each other, their dynamics cannot become identical; yet, after transients, there may emerge a functional relationship between them—a phenomenon termed “generalized synchronization.” Here, we show that the concept of transient uncoupling, recently introduced for synchronizing identical units, also supports generalized synchronization among nonidentical chaotic units. Generalized synchronization can be achieved by transient uncoupling even when it is impossible by regular coupling. We furthermore demonstrate that transient uncoupling stabilizes synchronization in the presence of common noise. Transient uncoupling works best if the units stay uncoupled whenever the driven orbit visits regions that are locally diverging in its phase space. Thus, to select a favorable uncoupling region, we propose an intuitive method that measures the local divergence at the phase points of the driven unit's trajectory by linearizing the flow and subsequently suppresses the divergence by uncoupling.
Assessment of multireference approaches to explicitly correlated full configuration interaction quantum Monte Carlo
Authors: Kersten J. A. F. , Booth George H. , Alavi Ali
Published: August 2016

The Full Configuration Interaction Quantum Monte Carlo (FCIQMC) method has proved able to provide near-exact solutions to the electronic Schrödinger equation within a finite orbital basis set, without relying on an expansion about a reference state. However, a drawback to the approach is that being based on an expansion of Slater determinants, the FCIQMC method suffers from a basis set incompleteness error that decays very slowly with the size of the employed single particle basis. The FCIQMC results obtained in a small basis set can be improved significantly with explicitly correlated techniques. Here, we present a study that assesses and compares two contrasting “universal” explicitly correlated approaches that fit into the FCIQMC framework: the [2]R12 method of Kong and Valeev [J. Chem. Phys. 135, 214105 (2011)] and the explicitly correlated canonical transcorrelation approach of Yanai and Shiozaki [J. Chem. Phys. 136, 084107 (2012)]. The former is an a posteriori internally contracted perturbative approach, while the latter transforms the Hamiltonian prior to the FCIQMC simulation. These comparisons are made across the 55 molecules of the G1 standard set. We found that both methods consistently reduce the basis set incompleteness, for accurate atomization energies in small basis sets, reducing the error from 28 mEh to 3-4 mEh. While many of the conclusions hold in general for any combination of multireference approaches with these methodologies, we also consider FCIQMC-specific advantages of each approach.
Transitional properties of supersolitons in a two electron temperature warm multi-ion plasma
Authors: Varghese Steffy S. , Ghosh S. S.
Published: August 2016

The existence domain of an ion acoustic supersoliton and its transition to a regular kind of solitary wave have been explored in detail using Sagdeev pseudopotential technique for a two electron temperature warm multi-ion plasma having two species of ions. It was found that both the cold to hot electron temperature ratio and their respective ambient densities play a deterministic role for the existence of a supersoliton, as well as its transitional processes to a regular solitary wave. Analogous to a double layer solution, which often marks the boundary of the existence domain of a regular solitary wave, a “curve of inflection” determines the boundary of the existence domain of a supersoliton. The characteristics of the “curve of inflection,” in turn, depend on the respective concentrations of the two ion species. It is observed that the supersolitons are actually a subset of a more general kind of solutions which are characterized by a fluctuation in the corresponding charge separation which precedes their maximum amplitude. It is also observed that these novel kinds of solitary structures, including supersolitons, occur only for a very narrow range of parameters near constant amplitude beyond which the wave breaks.
Rovibrational states of Wigner molecules in spherically symmetric confining potentials
Authors: Cioslowski Jerzy
Published: August 2016

The strong-localization limit of three-dimensional Wigner molecules, in which repulsively interacting particles are confined by a weak spherically symmetric potential, is investigated. An explicit prescription for computation of rovibrational wavefunctions and energies that are asymptotically exact at this limit is presented. The prescription is valid for systems with arbitrary angularly-independent interparticle and confining potentials, including those involving Coulombic and screened (i.e., Yukawa/Debye) interactions. The necessary derivations are greatly simplified by explicit constructions of the Eckart frame and the parity-adapted primitive wavefunctions. The performance of the new formalism is illustrated with the three- and four-electron harmonium atoms at their strong-correlation limits. In particular, the involvement of vibrational modes with the E symmetry is readily pinpointed as the origin of the “anomalous” weak-confinement behavior of the 1S+ state of the four-electron species that is absent in its 1D+ companion of the strong-confinement regime.
Development of a beam ion velocity detector for the heavy ion beam probe
Authors: Fimognari P. J. , Crowley T. P. , Demers D. R.
Published: August 2016

In an axisymmetric plasma, the conservation of canonical angular momentum constrains heavy ion beam probe (HIBP) trajectories such that measurement of the toroidal velocity component of secondary ions provides a localized determination of the poloidal flux at the volume where they originated. We have developed a prototype detector which is designed to determine the beam angle in one dimension through the detection of ion current landing on two parallel planes of detecting elements. A set of apertures creates a pattern of ion current on wires in the first plane and solid metal plates behind them; the relative amounts detected by the wires and plates determine the angle which beam ions enter the detector, which is used to infer the toroidal velocity component. The design evolved from a series of simulations within which we modeled ion beam velocity changes due to equilibrium and fluctuating magnetic fields, along with the ion beam profile and velocity dispersion, and studied how these and characteristics such as the size, cross section, and spacing of the detector elements affect performance.
Calibration of the OHREX high-resolution imaging crystal spectrometer at the Livermore electron beam ion traps
Authors: Hell N. , Beiersdorfer P. , Magee E. W. , Brown G. V.
Published: August 2016

We report the calibration of the Orion High-Resolution X-ray (OHREX) imaging crystal spectrometer at the EBIT-I electron beam ion trap at Livermore. Two such instruments, dubbed OHREX-1 and OHREX-2, are fielded for plasma diagnostics at the Orion laser facility in the United Kingdom. The OHREX spectrometer can simultaneously house two spherically bent crystals with a radius of curvature of r = 67.2 cm. The focusing properties of the spectrometer allow both for larger distance to the source due to the increase in collected light and for observation of extended sources. OHREX is designed to cover a 2.5°–3° spectral range at Bragg angles around 51.3°. The typically high resolving powers at these large Bragg angles are ideally suited for line shape diagnostics. For instance, the nominal resolving power of the instrument (>10 000) is much higher than the effective resolving power associated with the Doppler broadening due to the temperature of the trapped ions in EBIT-I. The effective resolving power is only around 3000 at typical EBIT-I conditions, which nevertheless is sufficient to set up and test the instrument’s spectral characteristics. We have calibrated the spectral range for a number of crystals using well known reference lines in the first and second order and derived the ion temperatures from these lines. We have also made use of the 50 μm size of the EBIT-I source width to characterize the spatial focusing of the spectrometer.
Optimization of a digital lock-in algorithm with a square-wave reference for frequency-divided multi-channel sensor signal detection
Authors: Zhang Shengzhao , Li Gang , Lin Ling , Zhao Jing
Published: August 2016

A digital lock-in detection technique is commonly used to measure the amplitude and phase of a selected frequency signal. A technique that uses a square wave as the reference signal has an advantage over the one using a sinusoidal wave due to its easier implementation and higher computational efficiency. However, demodulating multiple-frequency composite signals using square wave reference may result in interference between channels. To avoid interference between channels and reduce the computational complexity, we modify the calculations and determine the optimal parameter settings of the low-pass filter and carrier frequency, as detailed in this paper. The results of our analysis show that when the length of the average filter and carrier frequencies are properly set, the interference between the channels is removed. This optimization produces the digital lock-in detection suitable for measuring multi-channel sensor signals.
Enhanced proton acceleration by intense laser interaction with an inverse cone target
Authors: Bake Muhammad Ali , Aimidula Aimierding , Xiaerding Fuerkaiti , Rashidin Reyima
Published: August 2016

The generation and control of high-quality proton bunches using focused intense laser pulse on an inverse cone target is investigated with a set of particle-in-cell simulations. The inverse cone is a high atomic number conical frustum with a thin solid top and open base, where the laser impinges onto the top surface directly, not down the open end of the cone. Results are compared with a simple planar target, where the proton angular distribution is very broad because of transverse divergence of the electromagnetic fields behind the target. For a conical target, hot electrons along the cone wall surface induce a transverse focusing sheath field. This field can effectively suppress the spatial spreading of the protons, resulting in a high-quality small-emittance, low-divergence proton beam. A slightly lower proton beam peak energy than that of a conventional planar target was also found.
Single-shot mega-electronvolt ultrafast electron diffraction for structure dynamic studies of warm dense matter
Authors: Mo M. Z. , Shen X. , Chen Z. , Li R. K. , Dunning M. , Sokolowski-Tinten K. , Zheng Q. , Weathersby S. P. , Reid A. H. , Coffee R. , Makasyuk I. , Edstrom S. , McCormick D. , Jobe K. , Hast C. , Glenzer S. H. , Wang X.
Published: August 2016

We have developed a single-shot mega-electronvolt ultrafast-electron-diffraction system to measure the structural dynamics of warm dense matter. The electron probe in this system is featured by a kinetic energy of 3.2 MeV and a total charge of 20 fC, with the FWHM pulse duration and spot size at sample of 350 fs and 120 μm respectively. We demonstrate its unique capability by visualizing the atomic structural changes of warm dense gold formed from a laser-excited 35-nm freestanding single-crystal gold foil. The temporal evolution of the Bragg peak intensity and of the liquid signal during solid-liquid phase transition are quantitatively determined. This experimental capability opens up an exciting opportunity to unravel the atomic dynamics of structural phase transitions in warm dense matter regime.
High-resolution photoelectron imaging spectroscopy of cryogenically cooled Fe4O− and Fe5O−
Authors: Weichman Marissa L. , DeVine Jessalyn A. , Neumark Daniel M.
Published: August 2016

We report high-resolution photodetachment spectra of the cryogenically cooled iron monoxide clusters Fe4O− and Fe5O− obtained with slow photoelectron velocity-map imaging (cryo-SEVI). Well-resolved vibrational progressions are observed in both sets of spectra, and transitions to low-lying excited states of both species are seen. In order to identify the structural isomers, electronic states, and vibrational modes that contribute to the cryo-SEVI spectra of these clusters, experimental results are compared with density functional theory calculations and Franck-Condon simulations. The main bands observed in the SEVI spectra are assigned to the 15A2←16B2 photodetachment transition of Fe4O− and the 17A′←18A″ photodetachment transition of Fe5O−. We report electron affinities of 1.6980(3) eV for Fe4O and 1.8616(3) eV for Fe5O, although there is some uncertainty as to whether the 15A2 state is the true ground state of Fe4O. The iron atoms have a distorted tetrahedral geometry in Fe4O0/− and a distorted trigonal-bipyramidal arrangement in Fe5O0/−. For both neutral and anionic species, the oxygen atom preferably binds in a μ2-oxo configuration along the cluster edge. This finding is in contrast to prior predictions that Fe5O0/− exhibits a μ3 face-bound structure.
Sharp-front wave of strong magnetic field diffusion in solid metal
Authors: Xiao Bo , Gu Zhuo-wei , Kan Ming-xian , Wang Gang-hua , Zhao Jian-heng
Published: August 2016

When a strong magnetic field diffuses into a solid metal, if the metal's resistance possesses an abrupt rise at some critical temperature and the magnetic field strength is above some critical value, the magnetic field will diffuse into the metal in the form of a sharp-front wave. Formulas for the critical conditions under which a sharp-front magnetic diffusion wave emerges and a formula for the wave-front velocity are derived in this work.
Stable radiation pressure acceleration of ions by suppressing transverse Rayleigh-Taylor instability with multiple Gaussian pulses
Authors: Zhou M. L. , Liu B. , Hu R. H. , Shou Y. R. , Lin C. , Lu H. Y. , Lu Y. R. , Gu Y. Q. , Ma W. J. , Yan X. Q.
Published: August 2016

In the case of a thin plasma slab accelerated by the radiation pressure of an ultra-intense laser pulse, the development of Rayleigh-Taylor instability (RTI) will destroy the acceleration structure and terminate the acceleration process much sooner than theoretical limit. In this paper, a new scheme using multiple Gaussian pulses for ion acceleration in a radiation pressure acceleration regime is investigated with particle-in-cell simulation. We found that with multiple Gaussian pulses, the instability could be efficiently suppressed and the divergence of the ion bunch is greatly reduced, resulting in a longer acceleration time and much more collimated ion bunch with higher energy than using a single Gaussian pulse. An analytical model is developed to describe the suppression of RTI at the laser-plasma interface. The model shows that the suppression of RTI is due to the introduction of the long wavelength mode RTI by the multiple Gaussian pulses.
Ambipolarity in a tokamak with magnetic field ripple
Authors: Hazeltine R. D.
Published: August 2016

In view of the recognized importance of electrostatic fields regarding turbulent transport, the radial electric field in a tokamak with magnetic field ripple is reconsidered. Terms in the ambipolarity condition involving the radial derivative of the field are derived from an extended drift-kinetic equation, including effects of second order in the gyroradius. Such terms are of interest in part because of their known importance in rotational relaxation equations for the axisymmetric case. The electric field is found to satisfy a nonlinear differential equation that is universal in a certain sense, and that implies spatial relaxation of the potential to its conventionally predicted value.
Experimental investigation on the effect of plasma jet in the triggered discharge process of a gas switch
Authors: Tie W. , Liu S. , Liu X. , Zhang Q.
Published: August 2016

The temporal and spatial evolution of a plasma jet generated by a spark discharge was observed. The electron temperature and density were obtained under different time and gas pressures by optical emission spectroscopy. Moreover, the discharge process of the plasma-jet triggered gas switch was recorded and analyzed at the lowest working coefficient. The results showed that the plasma jet moved forward in a bullet mode, and the advancing velocity increased with the decrease of pressure, and decreased with time growing. At initial time, the maximum velocity of a plasma jet could reach 3.68 × 106 cm/s. The electron temperature decreased from 2.0 eV to 1.3 eV, and the electron density increased from 3.1 × 1015/cm3 to 6.3 × 1015/cm3 at the initial moment as the gas pressure increases from 0.1 MPa to 0.32 MPa. For a two-gap gas switch, the discharge performances were more depended on the second discharge spark gap (gap 2). Because plasma jet promoted the discharge in Gap 2, the gas switch operating in mode II had better triggered discharge characteristics. In the discharge process, the plasma-jet triggering had the effect of non-penetrating inducing, which not only provided initial electrons for reducing statistical lag but also enhanced the local electric field. The discharge was initiated and accelerated from electron avalanche to streamer. Therefore, a fast discharge was occurred in the gas switch.
Note: Real-time monitoring via second-harmonic interferometry of a flow gas cell for laser wakefield acceleration
Authors: Brandi F. , Giammanco F. , Conti F. , Sylla F. , Lambert G. , Gizzi L. A.
Published: August 2016

The use of a gas cell as a target for laser wakefield acceleration (LWFA) offers the possibility to obtain stable and manageable laser-plasma interaction process, a mandatory condition for practical applications of this emerging technique, especially in multi-stage accelerators. In order to obtain full control of the gas particle number density in the interaction region, thus allowing for a long term stable and manageable LWFA, real-time monitoring is necessary. In fact, the ideal gas law cannot be used to estimate the particle density inside the flow cell based on the preset backing pressure and the room temperature because the gas flow depends on several factors like tubing, regulators, and valves in the gas supply system, as well as vacuum chamber volume and vacuum pump speed/throughput. Here, second-harmonic interferometry is applied to measure the particle number density inside a flow gas cell designed for LWFA. The results demonstrate that real-time monitoring is achieved and that using low backing pressure gas (<1 bar) and different cell orifice diameters (<2 mm) it is possible to finely tune the number density up to the 1019 cm−3 range well suited for LWFA.
Anomalous magnetoelastic behaviour near morphotropic phase boundary in ferromagnetic Tb1-xNdxCo2 system
Authors: Murtaza Adil , Yang Sen , Zhou Chao , Chang Tieyan , Chen Kaiyun , Tian Fanghua , Song Xiaoping , Suchomel Matthrew R. , Ren Y.
Published: August 2016

In this work, we report a morphotropic phase boundary (MPB) involved ferromagnetic system Tb1-xNdxCo2 and reveal the corresponding structural and magnetoelastic properties of this system. With high resolution synchrotron X-ray diffractometry, the crystal structure of the TbCo2-rich side is detected to be rhombohedral and that of NdCo2-rich side is tetragonal below their respective Curie temperatures TC. The MPB composition Tb0.35Nd0.65Co2 corresponds to the coexistence of the rhombohedral phase (R-phase) and tetragonal phase (T-phase). Contrary to previously reported MPB involved ferromagnetic systems, the MPB composition of Tb0.35Nd0.65Co2 shows minimum magnetization which can be understood as compensation of sublattice moments between the R-phase and the T-phase. Furthermore, magnetostriction of Tb1-xNdxCo2 decreases with increasing Nd concentration until x = 0.8 and then increases in the negative direction with further increasing Nd concentration; the optimum point for magnetoelastic properties lies towards the rhombohedral phase. Our work not only shows an anomalous type of ferromagnetic MPB but also provides an effective way to design functional materials.