bluuebunny/crossref_metadata_2025 huggingface dataset:
How can we better use Twitter to find a person who got lost due to dementia?
Authors: Tsoi Kelvin K. F. , Chan Nicholas B. , Chan Felix C. H. , Zhang Lingling , Lee Annisa C. H. , Meng Helen M. L.
Published: April 2018

Twitter is a social media platform for online message sharing. The aim of this study is to evaluate the effectiveness of using Twitter to search for people who got lost due to dementia. The online messages on Twitter, i.e., tweets, were collected through an Application Programming Interface. Contents of the tweets were analysed. The personal characteristics, features of tweets and types of Twitter users were collected to investigate their associations with whether a person can be found within a month. Logistic regression was used to identify the features that were useful in finding the missing people. Results showed that the young age of the persons with dementia who got lost, having tweets posted by police departments, and having tweets with photos can increase the chance of being found. Social media is reshaping the human communication pathway, which may lead to future needs on a new patient-care model.
Enhanced thylakoid photoprotection can increase yield and canopy radiation use efficiency in rice
Authors: Hubbart Stella , Smillie Ian R. A. , Heatley Matthew , Swarup Ranjan , Foo Chuan Ching , Zhao Liang , Murchie Erik H.
Published: April 2018

High sunlight can raise plant growth rates but can potentially cause cellular damage. The likelihood of deleterious effects is lowered by a sophisticated set of photoprotective mechanisms, one of the most important being the controlled dissipation of energy from chlorophyll within photosystem II (PSII) measured as non-photochemical quenching (NPQ). Although ubiquitous, the role of NPQ in plant productivity remains uncertain because it momentarily reduces the quantum efficiency of photosynthesis. Here we used plants overexpressing the gene encoding a central regulator of NPQ, the protein PsbS, within a major crop species (rice)  to assess the effect of photoprotection at the whole canopy scale. We accounted for canopy light interception, to our knowledge for the first time in this context. We show that in comparison to wild-type plants,psbSoverexpressors increased canopy radiation use efficiency and grain yield in fluctuating light, demonstrating that photoprotective mechanisms should be altered to improve rice crop productivity.
Correction: Corrigendum: Arabidopsis aldehyde dehydrogenase 10 family members confer salt tolerance through putrescine-derived 4-aminobutyrate (GABA) production
Authors: Zarei Adel , Trobacher Christopher P. , Shelp Barry J.
Published: April 2018

Scientific Reports 6: Article number: 35115; published online: 11 October 2016; updated: 04 April 2018. This Article contains errors. One of the T-DNA insertion lines was mislabelled. aldh10A8-2 mutant line used in the study was incorrectly labelled as Salk 079882. The correct line number is Salk 079892.
Study of the electronic structure of electron accepting cyano-films: TCNQversusTCNE
Authors: Capitán Maria J. , Álvarez Jesús , Navio Cristina
Published: April 2018

A comparative study of the electronic structure of two closely related electron-acceptor molecules when they are grown on a Cu substrate.
Protein environment affects the water–tryptophan binding mode. MD, QM/MM, and NMR studies of engrailed homeodomain mutants
Authors: Špačková Nad'a , Trošanová Zuzana , Šebesta Filip , Jansen Séverine , Burda Jaroslav V. , Srb Pavel , Zachrdla Milan , Žídek Lukáš , Kozelka Jiří
Published: April 2018

Water molecules can interact with the π-face of tryptophan either forming an O–H⋯π hydrogen bond or by a lone-pair⋯π interaction. Surrounding amino acids can favor the one or the other interaction type.
A luminescent zinc(ii) coordination polymer with unusual (3,4,4)-coordinated self-catenated 3D network for selective detection of nitroaromatics and ferric and chromate ions: a versatile luminescent sensor
Authors: Zhang Ya-Qian , Blatov Vladislav A. , Zheng Tian-Rui , Yang Chang-Hao , Qian Lin-Lu , Li Ke , Li Bao-Long , Wu Bing
Published: April 2018

A zinc coordination polymer is a sensor for detection of TNP, Fe3+, Cr2O72− and CrO42−.
A novel aptasensor for malathion blood samples detection based on DNA–silver nanocluster
Authors: Chen Ceng , Shi Jian , Guo Yadong , Zha Lagabaiyla , Lan Lingmei , Chang Yunfeng , Ding Yanjun
Published: April 2018

A sensitive and selective aptasensor based on DNA–silver nanocluster probes has been proposed for the simple and efficient detection of malathion in biological samples.
A non-enzymatic nanoceria electrode for non-invasive glucose monitoring
Authors: Jiang Lei , Xue Qi , Jiao Chuanjie , Liu Hanyun , Zhou Yan , Ma Hongchao , Yang Qingli
Published: April 2018

A novel non-enzyme electrochemical sensor was constructed based on nanoceria and gold nanoparticle for non-invasive glucose monitoring.
A highly concentrated phosphate-based electrolyte for high-safety rechargeable lithium batteries
Authors: Shi Pengcheng , Zheng Hao , Liang Xin , Sun Yi , Cheng Sheng , Chen Chunhua , Xiang Hongfa
Published: April 2018

A highly concentrated phosphate-based electrolyte with nonflammable and dendrite-suppressing properties enables safe rechargeable lithium batteries.
Interfacial functional terminals enhance the heterogeneous nucleation of lysozyme crystals
Authors: Tong Xinmeng , Kang Junjie , Zhang Jinli , Jia Xin , Li Wei
Published: April 2018

A series of functional terminals were designed to interact with the flexible loop residues of lysozymes, aiming to produce quality protein crystalsviaintensified heterogeneous nucleation.
Preferential incorporation of sulfate into calcite polymorphs during calcium carbonate precipitation: an experimental approach
Authors: Kartnaller V. , Ribeiro E. M. , Venancio F. , Rosario F. F. , Cajaiba J.
Published: April 2018

Experimental validation was given to molecular dynamics calculations regarding the preferential retention of sulfate ions in the calcite polymorph of calcium carbonate.
Halogen-like properties of the Al13 cluster mimicking astatine
Authors: Molina B. , Soto J. R. , Castro J. J.
Published: April 2018

The Al13 cluster mimics the chemistry of astatine and might help in streamlining the processes of 211At radiolabeling in targeted alpha therapy (TAT) in cancer treatment.
Homogeneous polymetallic ruthenium(ii)^zinc(ii) complexes: robust catalysts for the efficient hydrogenation of levulinic acid to γ-valerolactone
Authors: Amenuvor Gershon , Darkwa James , Makhubela Banothile C. E.
Published: April 2018

New Ru(ii) complexes (1 and 2) have been synthesized and reacted with Zn(OAc)2 to form hexanuclear complexes (3 and 4) containing four Ru(ii) and two Zn(ii) centres. The latter are highly active and recyclable catalyst for the conversion of levulinic acid to GVL.
Photoluminescence properties of tetrahedral zinc(ii) complexes supported by calix[4]arene-based salicylaldiminato ligands
Authors: Ullmann Steve , Schnorr René , Laube Christian , Abel Bernd , Kersting Berthold
Published: April 2018

The photophysical properties of zinc salicylaldiminato calix[4]arene complexes can be fine-tuned by the salicylaldiminato substituents and the calix[4]arene conformation.
Impregnated palladium on magnetite as a water compatible catalyst for the cycloisomerization of alkynoic acid derivatives
Authors: Saavedra Beatriz , Pérez Juana M. , Rodríguez-Álvarez María J. , García-Álvarez Joaquín , Ramón Diego J.
Published: April 2018

This work describes the catalytic activity of palladium(ii) species in the cycloisomerization of alkynoic acids and their derivatives in aqueous media as well as in Deep Eutectic Solvents (DESs), with one of the lowest metal catalyst loadings reported so far in the literature.
Synthesis and biological evaluation of new 3-amino-2-azetidinone derivatives as anti-colorectal cancer agents
Authors: Tripodi Farida , Dapiaggi Federico , Orsini Fulvia , Pagliarin Roberto , Sello Guido , Coccetti Paola
Published: April 2018

Several synthetic combretastatin A4 (CA-4) derivatives were recently prepared to increase the drug efficacy and stability of the natural product isolated from the South African tree Combretum caffrum.
Parallelized biocatalytic scanning probe lithography for the additive fabrication of conjugated polymer structures
Authors: Hosford Joseph , Valles Morgane , Krainer Florian W. , Glieder Anton , Wong Lu Shin
Published: April 2018

Multiplexed scanning probes functionalized with a peroxidase enables large area constructive lithography of polyanilines.
Synthesis of highly functionalized 1,6-dihydropyridines via the Zn(OTf)2-catalyzed three-component cascade reaction of aldimines and two alkynes (IA2-coupling)
Authors: Shehzadi Syeda Aaliya , Vande Velde Christophe M. L. , Saeed Aamer , Abbaspour Tehrani Kourosch
Published: April 2018

One pot Zn(ii)-catalyzed imine–alkyne–alkyne coupling.
Super electron donor-mediated reductive transformation of nitrobenzenes: a novel strategy to synthesize azobenzenes and phenazines
Authors: Nozawa-Kumada Kanako , Abe Erina , Ito Shungo , Shigeno Masanori , Kondo Yoshinori
Published: April 2018

The transformation of nitrobenzenes into azobenzenes by pyridine-derived super electron donor 2 is described.
Relevance of the deletion of the Tatri4 gene in the secondary metabolome of Trichoderma arundinaceum
Authors: Izquierdo-Bueno Inmaculada , Moraga Javier , Cardoza Rosa E. , Lindo Laura , Hanson James R. , Gutiérrez Santiago , Collado Isidro G.
Published: April 2018

A study of the secondary metabolome of single culture of the mutant TaΔTri4, and of a co-culture with B. cinerea, was carried out. The results shed a light on the chemical cross-talk and ecological interactions between these fungi.
Palladium-catalyzed carbonylation of benzylic ammonium salts to amides and esters via C–N bond activation
Authors: Yu Weijie , Yang Shuwu , Xiong Fei , Fan Tianxiang , Feng Yan , Huang Yuanyuan , Fu Junkai , Wang Tao
Published: April 2018

An efficient palladium-catalyzed carbonylation reaction of readily available quaternary ammonium salts with CO is reported for the first time to afford arylacetamides and arylacetic acid esters via benzylic C–N bond cleavage.
Total synthesis of (±)-tanshinol B, tanshinone I, and (±)-tanshindiol B and C
Authors: Wang Fan , Yang Hong , Yu Shujuan , Xue Yu , Fan Zhoulong , Liang Gaolin , Geng Meiyu , Zhang Ao , Ding Chunyong
Published: April 2018

A concise and efficient approach was established for the divergent total synthesis of (±)-tanshinol B, (±)-tanshindiol B, (±)-tanshindiol C, and tanshinone I in 17–50% overall yield over 3–6 steps.
Gold(i)- and rhodium(iii)-catalyzed formal regiodivergent C–H alkynylation of 1-arylpyrazolones
Authors: Wang Xueli , Li Xingwei , Zhang Yao , Xia Lixin
Published: April 2018

A transition-metal-catalyzed formal regiodivergent C–H alkynylation of 1-aryl-5-pyrazolones is described.
Total synthesis of incargranine A
Authors: Brown Patrick D. , Lawrence Andrew L.
Published: April 2018

Synthetic studies into the origins of the alkaloid incargranine A have resulted in the development of a four-step (longest linear sequence) total synthesis.
Cardanol-based polymer latex by radical aqueous miniemulsion polymerization
Authors: Li W. S. J. , Negrell C. , Ladmiral V. , Lai-Kee-Him J. , Bron P. , Lacroix-Desmazes P. , Joly-Duhamel C. , Caillol S.
Published: April 2018

The facile one-pot, two-step synthesis of a new bio-sourced monomer derived from cardanol and its radical aqueous miniemulsion polymerization are presented.
Long distance ion–water interactions in aqueous sulfate nanodrops persist to ambient temperatures in the upper atmosphere
Authors: DiTucci Matthew J. , Stachl Christiane N. , Williams Evan R.
Published: April 2018

The effect of temperature on the patterning of water molecules located remotely from a single SO42− ion in aqueous nanodrops was investigated for nanodrops containing between 30 and 55 water molecules using instrument temperatures between 135 and 360 K.
Optimizing the defect chemistry of Na1/2Bi1/2TiO3-based materials: paving the way for excellent high temperature capacitors
Authors: Höfling Marion , Steiner Sebastian , Hoang An-Phuc , Seo In-Tae , Frömling Till
Published: April 2018

Lead free ceramic based high temperature capacitor materials have been identified as a highly promising solution considering the fulfillment of recent temperature and power requirements from automotive, aviation and renewable energy industry.
Fabrication and modal characterisation of large‐area polymer membranes for acoustic micro‐electromechanical systems devices
Authors: Camellini Luca , Torin Alberto , Al‐mashaal Asaad K. , Wood Graham S. , Newton Michael J. , Cheung Rebecca , Mastropaolo Enrico
Published: April 2018

Bilayer polymer/metal suspended membranes made of poly(methyl methacrylate) (PMMA) and aluminium (Al) have been fabricated using a wet transfer technique where a polyelectrolyte (polydiallyldimethylammonium chloride – PDAC) has been employed as sacrificial layer to facilitate the detachment of the thin PMMA/Al layers from the substrate holders. In this way, free‐standing PMMA/Al membranes with outstanding diameter (3.5 mm) to thickness (400 nm) ratios of ∼104 have been obtained. The membranes have been actuated mechanically and electrothermally and their modal behaviour characterised using laser Doppler vibrometry. The first five modes of vibrations have been detected in the range of 2–25 kHz. The second and fifth degenerate modes have been seen to split, probably due to non‐uniform tension or mass density. The membranes can achieve vibration amplitudes in the order of few tens of microns. When performing electro‐thermal actuation, it has been observed that the amplitude of a single mode can be tuned by controlling the path of the electric current across the membrane.
Das mittlere Fingergelenk
Authors: Corts Magga
Published: April 2018

Das mittlere Fingergelenk ist ein Scharniergelenk, mit dem nur einfache Beuge- und Streckbewegungen möglich sind. Durch Ringbänder fixierte Sehnenscheiden halten die Sehnen dicht am Gelenk und eine Sehnenkreuzung ermöglicht eine optimale Kraftübertragung auf die Finger.
Synthesis of Chromeno[4′,3′:4,5]pyrido[1,2-a]pyrazines and -diazepines by the Reaction of Substituted 2-(3-Acetyl-2-oxo-2H-chromen-4-yl)fumarates with 1,n-Diamines
Authors: Alizadeh Abdolali , Jamal Parinaz
Published: April 2018

A two-step sequence was developed for the synthesis of chromeno[4′,3′:4,5]pyrido[1,2-a]pyrazine-13-carboxylates and -diazepine-14-carboxylates by the reaction of substituted dimethyl 2-(3-acetyl-2-oxo-2H-chromen-4-yl)fumarates with 1,n-diamines at room temperature. Advantages of this protocol include ease of handling and the absence of a metal catalyst.
Diels–Alder Reactions of 1,2-Dihydropyridines: An Efficient Tool for the Synthesis of Isoquinuclidines
Authors: Silva Eduarda , Silva Artur , Rocha Djenisa
Published: April 2018

The Diels–Alder reaction of 1,2-dihydropyridines with different dienophiles is a well-established and straightforward method for the synthesis of isoquinuclidines. Nevertheless, the enantioselective preparation of isoquinuclidines using organocatalysts or organometallic catalysts is rather unexplored. This succinct review offers readers an overall perspective of the most important recent developments and concepts related to this topic.

1 Introduction

2 Asymmetric Diels–Alder Reaction of 1,2-Dihydropyridines

2.1 Transition-Metal-Catalyzed Reactions

2.2 Organocatalyzed Reactions

3 Diels–Alder Reaction of 1,2-Dihydropyridines in the Synthesis of Biologically Valuable Compounds

4 Conclusion
An Efficient Oxidation of Sulfides to Sulfones with Urea–Hydrogen Peroxide in the Presence of Phthalic Anhydride in Ethyl Acetate
Authors: Likhotvorik Igor , Lutz Marlon , Wenzler Marta
Published: April 2018

A metal-free, environmentally benign oxidation of substituted sulfides directly to their corresponding sulfones is described. Using urea-hydrogen peroxide and phthalic anhydride in ethyl acetate clean conversion into the sulfone was achieved without observation of the possible sulfoxide oxidation product.
An Interesting and Unique Case of 8p23.3p23.1 Deletion and 8p23.1p11.1 Interstitial Duplication Syndrome
Authors: Roy Shuvendu , Kumar Gaurav , Kumar Vivek
Published: April 2018

We report an interesting case of a male toddler with global developmental delay, dysmorphic facies, seizures, and acyanotic heart disease. Detailed evaluation revealed absent corpus callosum with large doubly committed ventricular septal defect (VSD) and 8p23.3p23.1 deletion and 8p23.1p11.1 interstitial duplication syndrome. In comparison to similar reports of 8p deletion and inverted duplication syndrome, the uniqueness of this report lies in the fact that the congenital heart defect occurred without the GATA4 gene involvement, and the nervous system involvement was more extensive.
Ankle and Hindfoot Symptoms after Medial Open Wedge High Tibial Osteotomy
Authors: Roberts Jason , Picard Frederic , Shah Siddharth
Published: April 2018

Medial open wedge high tibial osteotomy (MOWHTO) is a commonly performed procedure for symptomatic medial compartment osteoarthritis (OA). However, little is known about its effects on ipsilateral ankle or hindfoot. The aim of our study was to determine the incidence of ankle or hindfoot problems after MOWHTO and examine its association with radiological indices. Thirty-five knees (32 patients) undergoing navigated MOWHTO were evaluated for the presence of new-onset ankle or hindfoot symptoms after surgery. Pre- and postoperative hip-knee-ankle (HKA) angle, medial proximal tibial angle (MPTA), and tibial plafond inclination (TPI) were measured and compared on standing lower limb alignment radiographs. The mean postoperative change in HKA angle, MPTA, and TPI was 8.8°, 7.0°, and 8.4°, respectively. New-onset unexplained ankle or hindfoot symptoms were seen in 20% of the cases after surgery. Postoperative change in TPI was significantly greater in symptomatic patients as compared with asymptomatic ones (12.8° ± 4.9° vs. 8.1° ± 4.8°, p = 0.03). The odds ratio (OR) for developing ankle or hindfoot symptoms in cases with ≥ 10° change in TPI postoperatively was 10.8 (p = 0.04). Ankle or hindfoot symptoms were successfully managed with conservative treatment in all cases.
Comparison of the Leg-Length Change between Opening- and Closing-Wedge High Tibial Osteotomy: A Systematic Review and Meta-Analysis
Authors: Lee O-Sung , Ahn Soyeon , Lee Yong
Published: April 2018

The aim of this meta-analysis was to compare the effects of closing-wedge (CW) and opening-wedge (OW) high tibial osteotomies (HTOs) on the change in leg length. Our hypotheses were that leg length will increase after OW HTO and decrease after CW HTO, and the magnitude of the change in leg length would be negligible in both techniques. Multiple databases including MEDLINE, Embase, and Cochrane were searched for studies comparing the change in leg length after HTO with that before HTO. After testing for publication bias and heterogeneity, we aggregated variables by using the random-effects model. The weighted mean differences of leg length were estimated before and after OW and CW HTOs with 95% confidence intervals (CIs). Four studies that analyzed 127 OW HTOs and 175 CW HTOs were included in this meta-analysis. Leg length increased by 6.96 mm after OW HTO (95% CI: –3.43 to 17.36) and decreased by 1.95 mm after CW HTO (95% CI: –10.89 to 7). Additionally, the change in leg length after OW HTO had a positive correlation with the degree of correction. The leg length increased after OW HTO, and the increase was sufficiently large to cause clinical concerns. The change in leg length after CW HTO was negligible despite the decrease in length. Therefore, CW HTO seems to be a better treatment option than OW HTO if a large correction is required.
Transient isomers in the photodissociation of bromoiodomethane
Authors: Marcellini Moreno , Nasedkin Alexandr , Zietz Burkhard , Petersson Jonas , Vincent Jonathan , Palazzetti Federico , Malmerberg Erik , Kong Qingyu , Wulff Michael , van der Spoel David , Neutze Richard , Davidsson Jan
Published: April 2018

The photochemistry of halomethanes is fascinating for the complex cascade reactions toward either the parent or newly synthesized molecules. Here, we address the structural rearrangement of photodissociated CH2IBr in methanol and cyclohexane, probed by time-resolved X-ray scattering in liquid solution. Upon selective laser cleavage of the C–I bond, we follow the reaction cascade of the two geminate geometrical isomers, CH2I–Br and CH2Br–I. Both meta-stable isomers decay on different time scales, mediated by solvent interaction, toward the original parent molecule. We observe the internal rearrangement of CH2Br–I to CH2I–Br in cyclohexane by extending the time window up to 3 μs. We track the photoproduct kinetics of CH2Br–I in methanol solution where only one isomer is observed. The effect of the polarity of solvent on the geminate recombination pathways is discussed.
Contribution of the backstreaming ions to the self-magnetic pinch (SMP) diode current
Authors: Mazarakis Michael G. , Bennett Nichelle , Cuneo Michael E. , Fournier Sean D. , Johnston Mark D. , Kiefer Mark L. , Leckbee Joshua J. , Nielsen Dan S. , Oliver Bryan V. , Sceiford Matthew E. , Simpson Sean C. , Renk Timothy J. , Ruiz Carlos L. , Webb Timothy J. , Ziska Derek , Droemer Darryl W. , Gignac Raymond E. , Obregon Robert J. , Wilkins Frank L. , Welch Dale R.
Published: April 2018

The results presented here were obtained with a self-magnetic pinch (SMP) diode mounted at the front high voltage end of the RITS accelerator. RITS is a Self-Magnetically Insulated Transmission Line (MITL) voltage adder that adds the voltage pulse of six 1.3 MV inductively insulated cavities. The RITS driver together with the SMP diode has produced x-ray spots of the order of 1 mm in diameter and doses adequate for the radiographic imaging of high area density objects. Although, through the years, a number of different types of radiographic electron diodes have been utilized with SABER, HERMES III and RITS accelerators, the SMP diode appears to be the most successful and simplest diode for the radiographic investigation of various objects. Our experiments had two objectives: first to measure the contribution of the back-streaming ion currents emitted from the anode target and second to try to evaluate the energy of those ions and hence the Anode-Cathode (A-K) gap actual voltage. In any very high voltage inductive voltage adder utilizing MITLs to transmit the power to the diode load, the precise knowledge of the accelerating voltage applied on the A-K gap is problematic. This is even more difficult in an SMP diode where the A-K gap is very small (∼1 cm) and the diode region very hostile. The accelerating voltage quoted in the literature is from estimates based on the measurements of the anode and cathode currents of the MITL far upstream from the diode and utilizing the para-potential flow theories and inductive corrections. Thus, it would be interesting to have another independent measurement to evaluate the A-K voltage. The diode's anode is made of a number of high-Z metals in order to produce copious and energetic flash x-rays. It was established experimentally that the back-streaming ion currents are a strong function of the anode materials and their stage of cleanness. We have measured the back-streaming ion currents emitted from the anode and propagating through a hollow cathode tip for various diode configurations and different techniques of target cleaning treatment: namely, heating at very high temperatures with DC and pulsed current, with RF plasma cleaning, and with both plasma cleaning and heating. We have also evaluated the A-K gap voltage by energy filtering technique. Experimental results in comparison with LSP simulations are presented.
Investigation of in-situ co-doping by Sb and P of germanium films grown on Si(001) by molecular beam epitaxy
Authors: Zrir M. A. , Alek B. , Hussein A. , Shaker S. A.
Published: April 2018

Heavily n-type doping of Germanium was the key parameter in recent breakthroughs of Si-compatible infrared emitting devices. We investigate an in-situ co-doping technique using Phosphorus (P) and Antimony (Sb) to fabricate smooth and heavily n-type doped Ge films epitaxially grown on Si(001) using molecular beam epitaxy. The role of the rapid thermal annealing process in the dopants activation and in the significant annihilation of the threading dislocations is presented. Hall effect measurements reveal a free electron concentration of 4.2 × 1019 cm−3 at room temperature. The accumulated strain in the Ge films is studied using X-ray diffraction (XRD) data for P, Sb and co-doping, before and after annealing. A correlation between XRD and Hall effect results revealed a synergistic mechanism associated with the presence of Sb that improves the substitutional incorporation of P atoms. Atom Probe Tomography was implemented to investigate the effect of annealing on the distribution and clustering of dopants. Clustering and inhomogeneity in the density of Sb atoms are observed before annealing, while the density of P atoms was found to be homogeneous. After annealing, the clustering of P becomes more prominent. We show that the clustering is a limiting factor for the activation efficiency of Phosphorus in heavily doped Germanium.

The referenced publication has been retracted by the authors because of the use of unauthorized data represented by Figs. 8, 9, 10, 11, 12, 13, and 14. These figures were obtained with the help of other scientists in IM2NP Laboratory (Marseille, France) and have been only authorized for publication in the Ph.D. thesis of M. A. Zrir. The authors recognize that the publication of data that have been obtained with substantial help from other scientists can only be with their prior authorization. The authors sincerely apologize for this and recognize that the use of unauthorized data does not comply with the ethical standards of AIP Publishing and Journal of Applied Physics.
The vertical growth of MoS2 layers at the initial stage of CVD from first-principles
Authors: Xue Xiong-Xiong , Feng Yexin , Chen Keqiu , Zhang Lixin
Published: April 2018

Chemical vapor deposition (CVD) is the highly preferred method for mass production of transition metal dichalcogenide (TMD) layers, yet the atomic-scale knowledge is still lacking about the nucleation and growth. In this study, by using first-principles calculations, we show that, on Au(111) surface, one-dimensional (1D) MoxSy chains are first formed by coalescing of smaller feeding species and are energetically favored at the early stage of nucleation. Two-dimensional (2D) layers can be stabilized only after the number of Mo atoms exceeds ∼12. A vertical growth mode is revealed which accomplishes the structural transformation from the 1D chains to the 2D layers for the clusters while growing. The competition between intralayer and interlayer interactions is the key. These findings serve as new insights for better understanding the atomistic mechanism of the nucleation and growth of TMDs on the surface.
Bounding the first exit from the basin: Independence times and finite-time basin stability
Authors: Schultz Paul , Hellmann Frank , Webster Kevin N. , Kurths Jürgen
Published: April 2018

We study the stability of deterministic systems, given sequences of large, jump-like perturbations. Our main result is the derivation of a lower bound for the probability of the system to remain in the basin, given that perturbations are rare enough. This bound is efficient to evaluate numerically. To quantify rare enough, we define the notion of the independence time of such a system. This is the time after which a perturbed state has probably returned close to the attractor, meaning that subsequent perturbations can be considered separately. The effect of jump-like perturbations that occur at least the independence time apart is thus well described by a fixed probability to exit the basin at each jump, allowing us to obtain the bound. To determine the independence time, we introduce the concept of finite-time basin stability, which corresponds to the probability that a perturbed trajectory returns to an attractor within a given time. The independence time can then be determined as the time scale at which the finite-time basin stability reaches its asymptotic value. Besides that, finite-time basin stability is a novel probabilistic stability measure on its own, with potential broad applications in complex systems.
Increasing ion and fusion yield in a dense plasma focus by combination of pre-ionization and heavy ion gas admixture
Authors: Farmanfarmaei B. , Yousefi H. R. , Salem M. K. , Sari A. H.
Published: April 2018

The results of an experimental study of pre-ionization and heavy gas introduced into driven gas in a plasma focus device are reported. To achieve this purpose, we made use of two methods: first, the pre-ionization method by applying the shunt resistor and second, the admixture of heavy ions. We applied the different shunt resistors and found the optimum amount to be 200 MΩ at an optimum pressure of 0.5 Torr. Ion yield that was measured by array of Faraday cups and the energy of fast ions that was calculated by using the time-of-flight method were raised up to 22% and 45%, and the impurity caused by anode's erosion was reduced approximately by 67% in comparison to when there was no pre-ionization. Also, we have used the admixture of 5% argon ions with nitrogen (working gas) to improve the ion yield up to 45% in comparison with pure nitrogen. Finally, for the first time, we have utilized the combination of these methods together and have, consequently, reached the maximum ion yield and fusion yield. With this new method, ion yield raised up to 70% greater than that of the previous condition, i.e., without pre-ionization and heavy ion admixture.
Single frequency thermal wave radar: A next-generation dynamic thermography for quantitative non-destructive imaging over wide modulation frequency ranges
Authors: Melnikov Alexander , Chen Liangjie , Ramirez Venegas Diego , Sivagurunathan Koneswaran , Sun Qiming , Mandelis Andreas , Rodriguez Ignacio Rojas
Published: April 2018

Single-Frequency Thermal Wave Radar Imaging (SF-TWRI) was introduced and used to obtain quantitative thickness images of coatings on an aluminum block and on polyetherketone, and to image blind subsurface holes in a steel block. In SF-TWR, the starting and ending frequencies of a linear frequency modulation sweep are chosen to coincide. Using the highest available camera frame rate, SF-TWRI leads to a higher number of sampled points along the modulation waveform than conventional lock-in thermography imaging because it is not limited by conventional undersampling at high frequencies due to camera frame-rate limitations. This property leads to large reduction in measurement time, better quality of images, and higher signal-noise-ratio across wide frequency ranges. For quantitative thin-coating imaging applications, a two-layer photothermal model with lumped parameters was used to reconstruct the layer thickness from multi-frequency SF-TWR images. SF-TWRI represents a next-generation thermography method with superior features for imaging important classes of thin layers, materials, and components that require high-frequency thermal-wave probing well above today’s available infrared camera technology frame rates.
A position-dependent mass harmonic oscillator and deformed space
Authors: da Costa Bruno G. , Borges Ernesto P.
Published: April 2018

We consider canonically conjugated generalized space and linear momentum operators x^q and p^q in quantum mechanics, associated with a generalized translation operator which produces infinitesimal deformed displacements controlled by a deformation parameter q. A canonical transformation (x^,p^)→(x^q,p^q) leads the Hamiltonian of a position-dependent mass particle in usual space to another Hamiltonian of a particle with constant mass in a conservative force field of the deformed space. The equation of motion for the classical phase space (x, p) may be expressed in terms of the deformed (dual) q-derivative. We revisit the problem of a q-deformed oscillator in both classical and quantum formalisms. Particularly, this canonical transformation leads a particle with position-dependent mass in a harmonic potential to a particle with constant mass in a Morse potential. The trajectories in phase spaces (x, p) and (xq, pq) are analyzed for different values of the deformation parameter. Finally, we compare the results of the problem in classical and quantum formalisms through the principle of correspondence and the WKB approximation.
Change in magnetization of ferromagnetic Pd(001) ultrathin films induced by the strain effect of BaTiO3
Authors: Ban Yusuke , Komatsu Katsuyoshi , Sakuragi Shunsuke , Taniyama Tomoyasu , Kageshima Hiroyuki , Sato Tetsuya
Published: April 2018

We demonstrate changes in the saturation magnetization of Pd(001) ultrathin films exhibiting ferromagnetism in Pd/SrTiO3/BaTiO3 heterostructures due to the strain effect caused by the structural phase transition of BaTiO3 substrates. When a BaTiO3 substrate with a single domain formed by voltage application transitioned from the orthorhombic phase to the tetragonal phase, the saturation magnetization of Pd decreased by about 5%. The first-principles calculations, which assumed the distortion accompanied by the orthorhombic to the tetragonal structural phase transition, indicated a decrease by 3%–4% in the magnetization, which was consistent with the experimental results.
Pulse-coupled Belousov-Zhabotinsky oscillators with frequency modulation
Authors: Horvath Viktor , Epstein Irving R.
Published: April 2018

Inhibitory perturbations to the ferroin-catalyzed Belousov-Zhabotinsky (BZ) chemical oscillator operated in a continuously fed stirred tank reactor cause long term changes to the limit cycle: the lengths of the cycles subsequent to the perturbation are longer than that of the unperturbed cycle, and the unperturbed limit cycle is recovered only after several cycles. The frequency of the BZ reaction strongly depends on the acid concentration of the medium. By adding strong acid or base to the perturbing solutions, the magnitude and the direction of the frequency changes concomitant to excitatory or inhibitory perturbations can be controlled independently of the coupling strength. The dynamics of two BZ oscillators coupled through perturbations carrying a coupling agent (activator or inhibitor) and a frequency modulator (strong acid or base) was explored using a numerical model of the system. Here, we report new complex temporal patterns: higher order, partially synchronized modes that develop when inhibitory coupling is combined with positive frequency modulation (FM), and complex bursting patterns when excitatory coupling is combined with negative FM. The role of time delay between the peak and perturbation (the analog of synaptic delays in networks of neurons) has also been studied. The complex patterns found under inhibitory coupling and positive FM vanish when the delay is significant, whereas a sufficiently long time delay is required for the complex temporal dynamics to occur when coupling is excitatory and FM is negative.
Structure and dynamics of propylammonium nitrate-acetonitrile mixtures: An intricate multi-scale system probed with experimental and theoretical techniques
Authors: Campetella Marco , Mariani Alessandro , Sadun Claudia , Wu Boning , Castner Edward W. , Gontrani Lorenzo
Published: April 2018

In this article, we report the study of structural and dynamical properties for a series of acetonitrile/propylammonium nitrate mixtures as a function of their composition. These systems display an unusual increase in intensity in their X-ray diffraction patterns in the low-q regime, and their 1H-NMR diffusion-ordered NMR spectroscopy (DOSY) spectra display unusual diffusivities. However, the magnitude of both phenomena for mixtures of propylammonium nitrate is smaller than those observed for ethylammonium nitrate mixtures with the same cosolvent, suggesting that the cation alkyl tail plays an important role in these observations. The experimental X-ray scattering data are compared with the results of molecular dynamics simulations, including both ab initio studies used to interpret short-range interactions and classical simulations to describe longer range interactions. The higher level calculations highlight the presence of a strong hydrogen bond network within the ionic liquid, only slightly perturbed even at high acetonitrile concentration. These strong interactions lead to the symmetry breaking of the NO3− vibrations, with a splitting of about 88 cm−1 in the ν3 antisymmetric stretch. The classical force field simulations use a greater number of ion pairs, but are not capable of fully describing the longest range interactions, although they do successfully account for the observed concentration trend, and the analysis of the models confirms the nano-inhomogeneity of these kinds of samples.
Ion beams in multi-species plasmas
Authors: Aguirre E. M. , Scime E. E. , Good T. N.
Published: April 2018

Argon and xenon ion velocity distribution functions are measured in Ar-He, Ar-Xe, and Xe-He expanding helicon plasmas to determine if ion beam velocity is enhanced by the presence of lighter ions. Contrary to observations in mixed gas sheath experiments, we find that adding a lighter ion does not increase the ion beam speed. The predominant effect is a reduction of ion beam velocity consistent with increased drag arising from increased gas pressure under all conditions: constant total gas pressure, equal plasma densities of different ions, and very different plasma densities of different ions. These results suggest that the physics responsible for the acceleration of multiple ion species in simple sheaths is not responsible for the ion acceleration observed in expanding helicon plasmas.
Chaos controls of a duffing system with impacts
Authors: Feng Jinqian
Published: April 2018

The chaos controls of a Duffing system with impacts are investigated using appropriate random phase. Based on the discontinuous map and Wedig’s algorithm, a procedure of calculating top Lyapunov exponent is presented for stochastic Duffing system with impacts. As the random phase changes, two kinds of chaos control are achieved for Duffing system with impacts by the criterion of the top Lyapunov exponent: one is chaos suppression, and the other is chaos generation. In addition, the obtained results are verified by numerical simulations including the phase portrait, Poincare surface of section and time history.
Field-emission from parabolic tips: Current distributions, the net current, and effective emission area
Authors: Biswas Debabrata
Published: April 2018

Field emission from nano-structured emitters primarily takes place from the tips. Using recent results on the variation of the enhancement factor around the apex [Biswas et al., Ultramicroscopy 185, 1–4 (2018)], analytical expressions for the surface distribution of net emitted electrons, as well as the total and normal energy distributions are derived in terms of the apex radius Ra and the local electric field at the apex Ea. Formulae for the net emitted current and effective emission area in terms of these quantities are also obtained.
Nonlinear dielectric spectroscopy of propylene carbonate derivatives
Authors: Casalini R. , Roland C. M.
Published: April 2018

Nonlinear dielectric measurements were carried out on two strongly polar liquids, 4-vinyl-1,3-dioxolan-2-one (VPC) and 4-ethyl-1,3-dioxolan-2-one (EPC), having chemical structures differing from propylene carbonate (PC) only by the presence of a pendant group. Despite their polarity, the compounds are all non-associated, “simple” liquids. From the linear component of the dielectric response, the α relaxation peak breadth was found to be invariant at a fixed value of the relaxation time, τα. From spectra from the nonlinear component, the number of dynamically correlated molecules was determined; it was also constant at fixed τα. Thus, two manifestations of dynamic heterogeneity depend only on the time constant for structural reorientation. More broadly, the cooperativity of molecular motions for non-associated glass-forming materials is connected to (i.e., reciprocally governs) the time scale. The equation of state for the two liquids was also obtained from density measurements made over a broad range of pressures and temperatures. Using these data, it was determined that the relaxation times of both liquids conform to density scaling. The effect of density, relative to thermal effects, on the α relaxation increases going from PC < VPC < EPC.
Computational prediction of muon stopping sites using ab initio random structure searching (AIRSS)
Authors: Liborio Leandro , Sturniolo Simone , Jochym Dominik
Published: April 2018

The stopping site of the muon in a muon-spin relaxation experiment is in general unknown. There are some techniques that can be used to guess the muon stopping site, but they often rely on approximations and are not generally applicable to all cases. In this work, we propose a purely theoretical method to predict muon stopping sites in crystalline materials from first principles. The method is based on a combination of ab initio calculations, random structure searching, and machine learning, and it has successfully predicted the MuT and MuBC stopping sites of muonium in Si, diamond, and Ge, as well as the muonium stopping site in LiF, without any recourse to experimental results. The method makes use of Soprano, a Python library developed to aid ab initio computational crystallography, that was publicly released and contains all the software tools necessary to reproduce our analysis.
MCTDH on-the-fly: Efficient grid-based quantum dynamics without pre-computed potential energy surfaces
Authors: Richings Gareth W. , Habershon Scott
Published: April 2018

We present significant algorithmic improvements to a recently proposed direct quantum dynamics method, based upon combining well established grid-based quantum dynamics approaches and expansions of the potential energy operator in terms of a weighted sum of Gaussian functions. Specifically, using a sum of low-dimensional Gaussian functions to represent the potential energy surface (PES), combined with a secondary fitting of the PES using singular value decomposition, we show how standard grid-based quantum dynamics methods can be dramatically accelerated without loss of accuracy. This is demonstrated by on-the-fly simulations (using both standard grid-based methods and multi-configuration time-dependent Hartree) of both proton transfer on the electronic ground state of salicylaldimine and the non-adiabatic dynamics of pyrazine.
Full three-dimensional morphology evolution of amorphous thin films for atomic layer deposition
Authors: Jin Lingpeng , Li Yawei , Hu Zhigao , Chu Junhao
Published: April 2018

We introduce a Monte Carlo model based on random deposition and diffusion limited aggregation in order to study the morphological evolution of deposition of nanofilm, which is difficult to carry out by the experimental methods. The instantaneous evolution of morphology and the corresponding parameters are observed when employing a novel perspective, modeling the aggregation of nanoscale units. Despite simplifying the chemical details, the simulation results qualitatively describe experiments with bulky precursors, and the strong dependence of growth rate on steric hindrance is obtained. Moreover, the well know behavior that the delay before steady growth is accurately predicted and analyzed based solely on modeling. Through this work, the great influence of steric hindrance on the initial stage of ALD is described.
Attainable superheating of liquid n-butane
Authors: Baidakov V. G. , Kaverin A. M. , Pankov A. S.
Published: April 2018

Temperatures of the attainable superheating of liquid n-butane have been determined at pressures from 0.4 to 2.0 MPa in the range of nucleation rates J = 104–108 s−1 m−3. The data obtained have been compared with classical nucleation theory (CNT). At J > 106 s−1 m−3, satisfactory agreement between theory and experiment has been noted in both the value of the limiting superheating and the slope of the temperature dependence of the nucleation rate. It is shown that temperatures of the attainable superheatings of hydrocarbons of the methane series satisfy the one-parameter similarity. The possibility of manifestation of heterogeneous nucleation in experiment is discussed.
Towards an M5-brane model I: A 6d superconformal field theory
Authors: Sämann Christian , Schmidt Lennart
Published: April 2018

We present an action for a six-dimensional superconformal field theory containing a non-abelian tensor multiplet. All of the ingredients of this action have been available in the literature. We bring these pieces together by choosing the string Lie 2-algebra as a gauge structure, which we motivated in previous work. The kinematical data contains a connection on a categorified principal bundle, which is the appropriate mathematical description of the parallel transport of self-dual strings. Our action can be written down for each of the simply laced Dynkin diagrams, and each case reduces to a four-dimensional supersymmetric Yang–Mills theory with corresponding gauge Lie algebra. Our action also reduces nicely to an M2-brane model which is a deformation of the Aharony-Bergman-Jafferis-Maldacena (ABJM) model. While this action is certainly not the desired M5-brane model, we regard it as a key stepping stone towards a potential construction of the (2, 0)-theory.
Physician Attitudes, Beliefs and Barriers towards the Management and Treatment of Adult Obesity: A Literature Review
Authors: Dixon J.B , Hayden M.J , O'Brien P.E , Piterman L.
Published: April 2018

The objective of this study was to review physician attitudes, beliefs, knowledge and barriers towards adult patients who are overweight and obese. Electronic searches were carried out on PubMed, Medline and Embase up to July 2007. The search terms were built around 'obesity', 'physicians', and 'attitudes'. Only peer-reviewed full papers in English were included. Each paper had to directly investigate the attitudes, beliefs or barriers towards overweight and/or obese adults by physicians only. Forty-three studies met the inclusion criteria. Studies meeting inclusion criteria were reviewed by two authors. Evidence was fairly consistent across studies indicating that, in general, physicians feel qualified and well-equipped to manage and treat overweight and obese patients, yet overall do not feel successful. Knowledge about obesity is poor, with a lack of understanding of minimum BMI for obesity and the use of waist circumferences as a measure of obesity evident. There also appears to be a lack of knowledge about the treatment options available when treating obesity and their effectiveness. Furthermore, negative attitudes towards overweight and obese individuals are present, with many physicians categorising overweight and obese individuals as lazy, and that a key barrier in successfully treating obesity being lack of patient compliance and motivation. The study indicates additional training is necessary to educate physicians in regard to treatment options for obesity and to address the persistent negative attitudes towards obese patients.