bluuebunny/crossref_metadata_2025 huggingface dataset:
Nazarov cyclization of 1,4-pentadien-3-ols: preparation of cyclopenta[b]indoles and spiro[indene-1,4′-quinoline]s
Authors: Wang Zhiming , Xu Xingzhu , Gu Zhanshou , Feng Wei , Qian Houjun , Li Zhengyi , Sun Xiaoqiang , Kwon Ohyun
Published: December 2015

The first Lewis acid-catalyzed intramolecular interrupted Nazarov cyclization of 1,4-pentadien-3-ols is described.
Switchable supramolecular catalysis using DNA-templated scaffolds
Authors: Aleman Garcia Miguel Angel , Hu Yuwei , Willner Itamar
Published: December 2015

Switchable processes catalyzed by β-cyclodextrin and hemin/G-quadruplex proceed in the presence of supramolecular DNA-templated scaffolds.
Dynamics of formation of Ru, Os, Ir and Au metal nanocrystals on doped graphitic surfaces
Authors: Pitto-Barry Anaïs , Sadler Peter J. , Barry Nicolas P. E.
Published: December 2015

The fabrication of precious metal (ruthenium, osmium, gold, and iridium) nanocrystals from single atoms has been studied in real-time.
A T-shaped triazatruxene probe for the naked-eye detection of HCl gas with high sensitivity and selectivity
Authors: Li Xiang-Chun , Wang Chun-Yu , Wan Yi , Lai Wen-Yong , Zhao Li , Yin Meng-Fei , Huang Wei
Published: December 2015

A T-shaped Schiff-base triazatruxene derivative (TATNFF) was designed, synthesized, and explored as a sensitive probe to detect HCl gas by the naked eye.
Chemically-modified cellulose paper as smart sensor device for colorimetric and optical detection of hydrogen sulfate in water
Authors: Rull-Barrull Jordi , d'Halluin Martin , Le Grognec Erwan , Felpin François-Xavier
Published: December 2015

The first portable, recyclable and highly selective paper-based sensor device for the colorimetric and optical detection of hydrogen sulfate anions in water has been developed.
Hierarchical mesoporous silica nanoparticles as superb light scattering materials
Authors: Ryu Jaehoon , Yun Juyoung , Lee Jungsup , Lee Kisu , Jang Jyongsik
Published: December 2015

A novel approach to enhance the light scattering effect was explored by applying hierarchical mesoporous silica nanoparticles with a radial wrinkle structure (WSNs) in DSSCs as scattering layers. The WSNs were evaluated as outstanding light scattering materials providing large surface area as well as multiple scattering.
A robust comparison of dynamical scenarios in a glass-forming liquid
Authors: Vispa Alessandro , Busch Sebastian , Tamarit Josep Lluis , Unruh Tobias , Fernandez-Alonso Felix , Pardo Luis Carlos
Published: December 2015

We use Bayesian inference methods to provide fresh insights into the sub-nanosecond dynamics of glycerol, a prototypical glass-forming liquid.
Probing the early stages of solvation of cis-pinate dianions by water, acetonitrile, and methanol: a photoelectron spectroscopy and theoretical study
Authors: Hou Gao-Lei , Kong Xiang-Tao , Valiev Marat , Jiang Ling , Wang Xue-Bin
Published: December 2015

Photoelectron spectroscopy and theoretical studies indicate the coexistence of symmetric and asymmetric solvated clusters forcis-pinate dianions.
Cyclodextrin induced controlled delivery of a biological photosensitizer from a nanocarrier to DNA
Authors: Kundu Pronab , Ghosh Saptarshi , Das Sinjan , Chattopadhyay Nitin
Published: December 2015

Addition of β-cyclodextrin to the micelle bound phenosafranin in the presence of ctDNA leads to quantitative transfer of the fluorophore from the micelle to the DNA.
Theoretical insights into the photo-protective mechanisms of natural biological sunscreens: building blocks of eumelanin and pheomelanin
Authors: Marchetti Barbara , Karsili Tolga N. V.
Published: December 2015

Electron-driven proton-transfer and proton-transfer coupled ring-opening could be viable paths by which photoexcited building blocks of natural melanins non-radiatively decay.
Charge distribution and Fermi level in bimetallic nanoparticles
Authors: Holmberg Nico , Laasonen Kari , Peljo Pekka
Published: December 2015

Fermi level equilibration driven charge redistribution and electric dipole formation was quantified using a simple nanocapacitor model for bimetallic nanoparticles.
Electronic structure modification and Fermi level shifting in niobium-doped anatase titanium dioxide thin films: a comparative study of NEXAFS, work function and stiffening of phonons
Authors: Gautam Subodh K. , Das Arkaprava , Ojha S. , Shukla D. K. , Phase D. M. , Singh Fouran
Published: December 2015

The electronic structure and tuning of work function (WF) by electronic excitations (EEs) induced by swift heavy ions (SHIs) in anatase niobium-doped titanium dioxide (NTO) thin films is reported.
Urea hydration from dielectric relaxation spectroscopy: old findings confirmed, new insights gained
Authors: Agieienko Vira , Buchner Richard
Published: December 2015

In aqueous solutions urea significantly impedes rotational relaxation of 1–2 water molecules per solute.
Electrochemical silver dissolution and recovery as a potential method to disinfect drinking water for underprivileged societies
Authors: Parr Jeffrey M. P. , Kim Younggy
Published: December 2015

Limited access to disinfected drinking water is a critical challenge in developing countries. This new water disinfection method can be operated by a minimal amount of electric energy that can be supplied by bicycle generators or photovoltaic solar panels.
From synthetic DNA to PCR product: detection of fungal infections using SERS
Authors: Mabbott Samuel , Thompson David , Sirimuthu Narayana , McNay Graeme , Faulds Karen , Graham Duncan
Published: December 2015

We report the use of silver hydroxylamine nanoparticles functionalised with single stranded monothiolated DNA for the detection of fungal infections. The four different species of fungi that were targeted wereCandida albicans,Candida glabrata,Candida kruseiandAspergillus fumigatus. Rational design of synthetic targets and probes was carried out by carefully analysing the 2-D folding of the DNA and then by global alignment of the sequences to ensure specificity. The effects of varying the concentrations of the DNA and dye surrounding the nanoparticles on the resultant surface enhanced Raman scattering (SERS) signal were also investigated to ensure compatibility of the probes in a multiplexed environment. Using principal components analysis (PCA) it was possible to detect the individual presence of each target and group them accordingly. The move to detect theC. kruseisingle stranded PCR product (ssPCR) was significant to demonstrate that the methodology could be employed for the detection and diagnosis of invasive fungal infections (IFDs) within a clinical setting. Initially the PCR product was subjected to an alkali shock method in order to separate the strands ready for detection using the nanoparticle probes system. This time 18 base probes were employed to enhance hybridisation efficiency and dextran sulfate was found to have a vital role in ensuring that detection of theC. kruseitarget was achieved. This demonstrated the use of DNA functionalised silver nanoparticle for the detection of clinically relevant DNA relating to a specific fungal infection and offers significant promise for future diagnostic applications.
An integrated paper-based sample-to-answer biosensor for nucleic acid testing at the point of care
Authors: Choi Jane Ru , Hu Jie , Tang Ruihua , Gong Yan , Feng Shangsheng , Ren Hui , Wen Ting , Li XiuJun , Wan Abas Wan Abu Bakar , Pingguan-Murphy Belinda , Xu Feng
Published: December 2015

An integrated paper-based sample-to-answer biosensor is proposed, which enables simple paper-based nucleic acid extraction, amplification and detection for point-of-care testing.
Thermodynamics of Pb(ii) and Zn(ii) binding to MT-3, a neurologically important metallothionein
Authors: Carpenter M. C. , Shami Shah A. , DeSilva S. , Gleaton A. , Su A. , Goundie B. , Croteau M. L. , Stevenson M. J. , Wilcox D. E. , Austin R. N.
Published: December 2015

The first quantification of Pb(ii) binding to MT-3 using ITC shows that lead binds more tightly than zinc to this brain-specific metallothionein.
The application of design of experiments (DoE) reaction optimisation and solvent selection in the development of new synthetic chemistry
Authors: Murray Paul M. , Bellany Fiona , Benhamou Laure , Bučar Dejan-Krešimir , Tabor Alethea B. , Sheppard Tom D.
Published: December 2015

This article outlines the benefits of using ‘Design of Experiments’ (DoE) for optimisation and solvent selection during the development of new synthetic methodology.
Asymmetric dearomatization of phenols
Authors: Sun Wangsheng , Li Guofeng , Hong Liang , Wang Rui
Published: December 2015

This review summarizes the recent advances in the field of asymmetric dearomatization of phenols and their applications in the total synthesis of some complex natural products.
Development of a stable phosphoarginine analog for producing phosphoarginine antibodies
Authors: Ouyang Han , Fu Chuan , Fu Songsen , Ji Zhe , Sun Ying , Deng Peiran , Zhao Yufen
Published: December 2015

pAIE is designed and synthesized as a stable analog and bioisostere of acid-labile pArg, to produce pArg specific antibodies, facilitating the detection of protein arginine phosphorylation.
A facile way to prepare nanoporous PbI2 films and their application in fast conversion to CH3NH3PbI3
Authors: Zheng Huifeng , Wang Weiqi , Yang Songwang , Liu Yangqiao , Sun Jing
Published: December 2015

Nanoporous PbI2 films, prepared in a facile way, are applied to accelerate the reaction in the two-step deposition of CH3NH3PbI3.
A nano zinc oxide doped electrospun scaffold improves wound healing in a rodent model
Authors: Chhabra Hemlata , Deshpande Rucha , Kanitkar Meghana , Jaiswal Amit , Kale Vaijayanti P. , Bellare Jayesh R.
Published: December 2015

Development of new and effective wound dressing materials continues to be an area of intense research in wound care management. ​Fabricated ZnO doped nanofibrous scaffold exhibited proficiency in EPCs enrichment and wound healing.
Capillary flow control in nanochannels via hybrid surface
Authors: Ye Ziran , Li Shunbo , Wang Cong , Shen Rong , Wen Weijia
Published: December 2015

We report a simple and effective approach to control the speed of capillary flow in nanochannels in a quantitative manner.
Optimizing molecule-like gold clusters for light energy conversion
Authors: Stamplecoskie Kevin G. , Swint Abigail
Published: December 2015

As light harvesting materials, Au18SR14 metal clusters are highlighted for their favourable excited-state properties leading to better photovoltaic performance.
Concave Bi2WO6nanoplates with oxygen vacancies achieving enhanced electrocatalytic oxygen evolution in near-neutral water
Authors: Nie Zhu-Ping , Ma De-Kun , Fang Guo-Yong , Chen Wei , Huang Shao-Ming
Published: December 2015

Concave Bi2WO6nanoplates with oxygen vacancies firstly achieved enhanced electrocatalytic oxygen evolution in near-neutral water.
An electrochemical immunosensor for simultaneous point-of-care cancer markers based on the host–guest inclusion of β-cyclodextrin–graphene oxide
Authors: Feng Taotao , Qiao Xiuwen , Wang Haining , Sun Zhao , Qi Yu , Hong Chenglin
Published: December 2015

An electrochemical immunosensor was developed using GO–AuNPs as substrates, Cu2O–GO–CD and GO–CD–Fc as probes, which exhibited excellent electrochemical performances.
A molecularly imprinted polymer as an antibody mimic with affinity for lysine acetylated peptides
Authors: Yang Xu , Dong Xiangchao , Zhang Kai , Yang Fangfang , Guo Zhenchang
Published: December 2015

Molecularly imprinted polymer with affinity for acetylated lysines prepared by the combination of epitope and surface-confined imprinting strategy.
The p-type Mg2LixSi0.4Sn0.6 thermoelectric materials synthesized by a B2O3 encapsulation method using Li2CO3 as the doping agent
Authors: Gao Peng , Davis Joshua D. , Poltavets Viktor V. , Hogan Timothy P.
Published: December 2015

The p-type Mg2LixSi0.4Sn0.6 were synthesized by a B2O3-encapsulation method using Li2CO3 as doping agent and showed significant improvement in ZT.
Electrostatics and N-glycan-mediated membrane tethering of SCUBE1 is critical for promoting bone morphogenetic protein signalling
Authors: Liao Wei-Ju , Tsao Ku-Chi , Yang Ruey-Bing
Published: December 2015

SCUBE1 (S1), a secreted and membrane-bound glycoprotein, has a modular protein structure composed of an N-terminal signal peptide sequence followed by nine epidermal growth factor (EGF)-like repeats, a spacer region and three cysteine-rich (CR) motifs with multiple potential N-linked glycosylation sites, and one CUB domain at the C-terminus. Soluble S1 is a biomarker of platelet activation but an active participant of thrombosis via its adhesive EGF-like repeats, whereas its membrane-associated form acts as a bone morphogenetic protein (BMP) co-receptor in promoting BMP signal activity. However, the mechanism responsible for the membrane tethering and the biological importance of N-glycosylation of S1 remain largely unknown. In the present study, molecular mapping analysis identified a polycationic segment (amino acids 501–550) in the spacer region required for its membrane tethering via electrostatic interactions possibly with the anionic heparan sulfate proteoglycans. Furthermore, deglycosylation by peptide N-glycosidase F treatment revealed that N-glycans within the CR motif are essential for membrane recruitment through lectin-mediated surface retention. Injection of mRNA encoding zebrafish wild-type but not N-glycan-deficient scube1 restores the expression of haematopoietic and erythroid markers (scl and gata1) in scube1-knockdown embryos. We describe novel mechanisms in targeting S1 to the plasma membrane and demonstrate that N-glycans are required for S1 functions during primitive haematopoiesis in zebrafish.
Insights into ascorbate regeneration in plants: investigating the redox and structural properties of dehydroascorbate reductases fromPopulus trichocarpa
Authors: Lallement Pierre-Alexandre , Roret Thomas , Tsan Pascale , Gualberto José M. , Girardet Jean-Michel , Didierjean Claude , Rouhier Nicolas , Hecker Arnaud
Published: December 2015

Dehydroascorbate reductases (DHARs), enzymes belonging to the GST superfamily, catalyse the GSH-dependent reduction of dehydroascorbate into ascorbate in plants. By maintaining a reduced ascorbate pool, they notably participate to H2O2 detoxification catalysed by ascorbate peroxidases (APXs). Despite this central role, the catalytic mechanism used by DHARs is still not well understood and there is no supportive 3D structure. In this context, we have performed a thorough biochemical and structural analysis of the three poplar DHARs and coupled this to the analysis of their transcript expression patterns and subcellular localizations. The transcripts for these genes are mainly detected in reproductive and green organs and the corresponding proteins are expressed in plastids, in the cytosol and in the nucleus, but not in mitochondria and peroxisomes where ascorbate regeneration is obviously necessary. Comparing the kinetic properties and the sensitivity to GSSG-mediated oxidation of DHAR2 and DHAR3A, exhibiting 1 or 3 cysteinyl residues respectively, we observed that the presence of additional cysteines in DHAR3A modifies the regeneration mechanism of the catalytic cysteine by forming different redox states. Finally, from the 3D structure of DHAR3A solved by NMR, we were able to map the residues important for the binding of both substrates (GSH and DHA), showing that DHAR active site is very selective for DHA recognition and providing further insights into the catalytic mechanism and the roles of the additional cysteines found in some DHARs.
A Cultural Bases to Develop Strong Advocates for Client and Family Involvement In the Speech-Generated Device Evaluation and Funding Process
Authors: Harris Ovetta
Published: December 2015

This article describes information that speech-language pathologists (SLPs) should be aware of in order to serve as strong advocates in assisting families with users of augmentative and alternative Communication to obtain evaluations and funding for SGDs. Cultural knowledge and awareness is important in providing competent service delivery. Awareness of concerns of many culturally diverse individuals seeking an SGD is discussed, as well as conditions that necessitate the SLP serving as a strong advocate for families with funding needs.
Speech-Generating Device Funding and Patterns of Acquisition for Persons With Amyotrophic Lateral Sclerosis
Authors: Ball Laura J. , Pattee Gary L. , Golinker Lewis , Beukelman David R.
Published: December 2015

People with such severe and complex communication needs that they require speech-generating devices (SGDs) to meet daily communication needs come from all age groups and socioeconomic backgrounds (Beukelman & Mirenda, 2013). Among this group are people eligible for Medicare, which will provide payment for a percentage (typically 80 percent) of covered health care costs, including SGDs. Medicare eligibility extends to people age 65 and older and younger people who became disabled from non-work related causes. In this article, the authors first review Medicare coverage for augmentative and alternative communication (AAC) devices beginning in the 1980s and subsequently document the SGD acquisition and access of 64 people with amyotrophic lateral sclerosis (ALS) whose speech became so severely limited that they required an SGD to support functional communication.
Development of a 20 kV damped oscillating voltage generator
Authors: Hou Zhe , Yu Peixiang , Li Hongjie , Ji Shengchang , Zhang Wei , Zhou Hua , Xu Fei
Published: December 2015

This study describes the design and development of a 20 kV rated damped oscillating voltage (DOV) generator that can detect the partial discharge (PD) condition in 6/10 kV power cables. A complete system using a novel high‐voltage switch consisting of a series of connected insulated gate bipolar transistors (IGBTs) is designed and tested. The switch consists of ten identical IGBT switch units, a multiple output isolated power supply system and a trigger unit. Physically, it is a 60 cm diameter fan‐shaped printed circuit board. To coordinate the various tested objects and to comply with the IEC 60060‐3 standards, an air‐core inductor is calculated to precisely fit the most general application conditions using the magnetic vector potentials method. A laboratory prototype is assembled and tested. Waveforms illustrating the performance of the IGBT switch and the output of the DOV are presented. Finally, an application‐oriented test demonstrates that the scheme can successfully complete the PD test and PD location test for a cable sample.
Analysis and implementation of wide zero‐voltage switching dual full‐bridge converters
Authors: Lin Bor‐Ren
Published: December 2015

A new full‐bridge converter is presented to have the advantages of low conduction loss and wide zero‐voltage switching (ZVS) range. The proposed converter includes two dc–dc converters connected in parallel to reduce the current stresses of power components. Each dc–dc converter integrates a phase‐shift pulse‐width modulation full‐bridge circuit and an un‐regulated half‐bridge circuit sharing the lagging‐leg switches in order to reduce the switch counts. The un‐regulated half‐bridge circuit is adopted to extend the ZVS range of the lagging‐leg switches to improve the drawback of the narrow ZVS range in conventional full‐bridge converter. Two dc–dc converters share the lagging‐leg switches so that the switch counts in the proposed converter are less than the switches in conventional parallel full‐bridge converters. The resonant capacitors are used on the primary side of full‐bridge converters to reduce the primary current to zero at the freewheeling state. The secondary windings of full‐bridge and half‐bridge converters are connected in series to generate two positive voltage levels at the secondary rectified voltage. Therefore, the output inductor voltage at the freewheeling state is decreased and the output inductor size is reduced. Finally, the effectiveness of the proposed converter is verified by the experiments.
Modeling of dissociation and energy transfer in shock-heated nitrogen flows
Authors: Munafò A. , Liu Y. , Panesi M.
Published: December 2015

This work addresses the modeling of dissociation and energy transfer processes in shock heated nitrogen flows by means of the maximum entropy linear model and a newly proposed hybrid bin vibrational collisional model. Both models aim at overcoming two of the main limitations of the state of the art non-equilibrium models: (i) the assumption of equilibrium between rotational and translational energy modes of the molecules and (ii) the reliance on the quasi-steady-state distribution for the description of the population of the internal levels. The formulation of the coarse-grained models is based on grouping the energy levels into bins, where the population is assumed to follow a Maxwell-Boltzmann distribution at its own temperature. Different grouping strategies are investigated. Following the maximum entropy principle, the governing equations are obtained by taking the zeroth and first-order moments of the rovibrational master equations. The accuracy of the proposed models is tested against the rovibrational master equation solution for both flow quantities and population distributions. Calculations performed for free-stream velocities ranging from 5 km/s to 10 km/s demonstrate that dissociation can be accurately predicted by using only 2-3 bins. It is also shown that a multi-temperature approach leads to an under-prediction of dissociation, due to the inability of the former to account for the faster excitation of high-lying vibrational states.
Dynamics of viscous coalescing droplets in a saturated vapor phase
Authors: Baroudi Lina , Nagel Sidney R. , Morris Jeffrey F. , Lee Taehun
Published: December 2015

The dynamics of two liquid droplets coalescing in their saturated vapor phase are investigated by Lattice Boltzmann numerical simulations. Attention is paid to the effect of the vapor phase on the formation and growth dynamics of the liquid bridge in the viscous regime. We observe that the onset of the coalescence occurs earlier and the expansion of the bridge initially proceeds faster when the coalescence takes place in a saturated vapor compared to the coalescence in a non-condensable gas. We argue that the initially faster evolution of the coalescence in the saturated vapor is caused by the vapor transport through condensation during the early stages of the coalescence.
Hydrodynamic interactions of sheets vs filaments: Synchronization, attraction, and alignment
Authors: Olson Sarah D. , Fauci Lisa J.
Published: December 2015

The synchronization of nearby sperm flagella as they swim in a viscous fluid was observed nearly a century ago. In the early 1950s, in an effort to shed light on this intriguing phenomenon, Taylor initiated the mathematical analysis of the fluid dynamics of microorganism motility. Since then, models have investigated sperm hydrodynamics where the flagellum is treated as a waving sheet (2D) or as a slender waving filament (3D). Here, we study the interactions of two finite length, flexible filaments confined to a plane in a 3D fluid and compare these to the interactions of the analogous pair of finite, flexible sheets in a 2D fluid. Within our computational framework using regularized Stokeslets, this comparison is easily achieved by choosing either the 2D or 3D regularized kernel to compute fluid velocities induced by the actuated structures. We find, as expected, that two flagella swimming with a symmetric beatform will synchronize (phase-lock) on a fast time scale and attract towards each other on a longer time scale in both 2D and 3D. For a symmetric beatform, synchronization occurs faster in 2D than 3D for sufficiently stiff swimmers. In 3D, a greater enhancement in efficiency and swimming velocity is observed for attracted swimmers relative to the 2D case. We also demonstrate the tendency of two asymmetrically beating filaments in a 3D fluid to align — in tandem — exhibiting an efficiency boost for the duration of their sustained alignment.
Non-isothermal rimming flow with the effects of surface shear and droplet impact
Authors: Kay E. D. , Hibberd S. , Power H.
Published: December 2015

We present a mathematical model for the flow and temperature in a thin liquid film flow coating the inside of a cylinder driven at the surface by an air shear and distributed flux of liquid droplets with liquid removal through a region of the cylinder wall. Modelling is motivated by the industrial application of droplet-cooling of thin oil films in aero-engine bearing chambers where films may be fast-moving which involve significant inertia and heat convection. To account for these effects, we allow the Reynolds and Péclet numbers of the film to be sufficiently large that they persist at leading-order in the thin-film limit. We adopt a Karman–Pohlhausen integral approach of boundary layer theory to extend previous studies to include surface droplet impact and cooling. Example numerical results are presented to illustrate how inertial effects and the impacting droplets influence film dynamics. Thermal characteristics of a selection of flows subject to droplet cooling are investigated.
Mechanism of shock unsteadiness in separated shock/boundary-layer interactions
Authors: Agostini L. , Larchevêque L. , Dupont P.
Published: December 2015

A large-eddy simulation-based study is presented and focuses on different unsteadiness-source features in a Mach 2.3 shock reflection with separation. The sources of unsteadiness are localized and the path taken by disturbance as it spreads out to the whole field is defined. It is shown that the phenomena arising inside the recirculation bubble govern the whole interaction, at both low and intermediate frequencies. Indeed, the shock motion appears to mirror phenomena found in the separated zone. Moreover, features of separated-flow unsteadiness bear some resemblance to those occurring in incompressible flows. An equivalent inviscid scheme of the unsteady interaction is established in order to describe the whole shock-system unsteadiness at low and intermediate frequencies and the downstream unsteady-pressure field.
Threshold for plasma phase transition of aluminum single crystal induced by hypervelocity impact
Authors: Ju Yuanyuan , Zhang Qingming
Published: December 2015

Molecular dynamics method is used to study the threshold for plasma phase transition of aluminum single crystal induced by hypervelocity impact. Two effective simulation methods, piston-driven method and multi-scale shock technique, are used to simulate the shock wave. The simulation results from the two methods agree well with the experimental data, indicating that the shock wave velocity is linearly dependent on the particle velocity. The atom is considered to be ionized if the increase of its internal energy is larger than the first ionization energy. The critical impact velocity for plasma phase transition is about 13.0 km/s, corresponding to the threshold of pressure and temperature which is about 220 GPa and 11.0 × 103 K on the shock Hugoniot, respectively.
Confinement effects on the liquid-liquid phase transition and anomalous properties of a monatomic water-like liquid
Authors: Sun Gang , Giovambattista Nicolas , Xu Limei
Published: December 2015

We use molecular dynamics simulations to study the effects of confinement on the phase behavior of a water-like monatomic liquid that exhibits a liquid-liquid phase transition (LLPT) and a liquid-liquid critical point (LLCP). The liquid is confined between parallel walls and we focus on the effects of wall separation and surface chemistry (solvophobicity/solvophilicity) on the location of the LLCP, temperature of maximum density (TMD) line, and loci of compressibility maxima (CM). It is found that, independently of the surface solvophobicity/solvophilicity, the LLCP, TMD, and CM lines shift rapidly towards higher pressures and lower temperatures as the wall separation is reduced. It follows that the effects of confinement on the TMD and CM lines are indicative of the confinement effects on the LLCP/LLPT. Confinement effects are observable already when the liquid particles form ≈15 layers between the walls. For the case of water, this corresponds to a separation of ≈4–5 nm between the surfaces, larger than the confining dimension of the nanopores commonly used to study the hypothesized LLPT in confined water. Hence, our results suggest that such experiments should not be interpreted in terms of the phase diagrams proposed for bulk water.
Loss of efficiency of polymeric drag reducers induced by high Reynolds number flows in tubes with imposed pressure
Authors: Soares Edson J. , Sandoval Gustavo A. B. , Silveira Lucas , Pereira Anselmo S. , Trevelin Renata , Thomaz Fabricio
Published: December 2015

This paper studies the loss of efficiency of polymeric drag reducers induced by high Reynolds number flows in tubes. The overall pressure was fixed and the apparatus was built so as to minimize the polymer degradation. We used three kinds of polymers: two flexible and one rigid. We conducted our tests to take into account the drag reduction (DR) for a wide range of concentrations of each polymer. The main results are displayed for the DR as a function of the number of passes through the apparatus. The mechanism of the loss of efficiency for the Xanthan Gum (XG) solutions (the rigid one) seems to be completely different from that observed for Poly (ethylene oxide) (PEO) and Polyacrylamide (PAM) (the flexible materials). While the PEO and PAM mechanically degrade by the action of the turbulent flow, the XG seems to remain intact, even after many passes through the pipe flow apparatus. From the practical point of view, it is worth noting that the PAM solutions are clearly more efficient than the PEO and XG. Another practical point that deserves attention is concerned with the asymptotic drag reduction found for XG. Although its maximum DR was significantly smaller than that found for PEO, the final value for both polymers were quite the same, which is obviously related to the intensified mechanical molecule scission in the PEO solutions. Our results for the relative drag reduction (the current value of DR divided by its maximum obtained at the first pass) was quite well fitted by the decay function proposed in our previous paper [A. S. Pereira and E. J. Soares, “Polymer degradation of dilute solutions in turbulent drag reducing flows in a cylindrical double gap rheometer device,” J. Non-Newtonian Fluid Mech. 179, 9–22 (2012)], in which a rotating apparatus was used. This strongly suggests that the physical mechanism that governs the degradation phenomenon is independent of the geometry. We also used a degradation model for PEO proposed by Vonlanthen and Monkewitz [“Grid turbulence in dilute polymer solution: Peo in water,” J. Fluid Mech. 730, 76–98 (2013)] to fit our data of relative drag reduction for PEO and PAM.
Sequence heterogeneity accelerates protein search for targets on DNA
Authors: Shvets Alexey A. , Kolomeisky Anatoly B.
Published: December 2015

The process of protein search for specific binding sites on DNA is fundamentally important since it marks the beginning of all major biological processes. We present a theoretical investigation that probes the role of DNA sequence symmetry, heterogeneity, and chemical composition in the protein search dynamics. Using a discrete-state stochastic approach with a first-passage events analysis, which takes into account the most relevant physical-chemical processes, a full analytical description of the search dynamics is obtained. It is found that, contrary to existing views, the protein search is generally faster on DNA with more heterogeneous sequences. In addition, the search dynamics might be affected by the chemical composition near the target site. The physical origins of these phenomena are discussed. Our results suggest that biological processes might be effectively regulated by modifying chemical composition, symmetry, and heterogeneity of a genome.
Matrix elements and duality for type 2 unitary representations of the Lie superalgebra gl(m|n)
Authors: Werry Jason L. , Gould Mark D. , Isaac Phillip S.
Published: December 2015

The characteristic identity formalism discussed in our recent articles is further utilized to derive matrix elements of type 2 unitary irreducible gl(m|n) modules. In particular, we give matrix element formulae for all gl(m|n) generators, including the non-elementary generators, together with their phases on finite dimensional type 2 unitary irreducible representations which include the contravariant tensor representations and an additional class of essentially typical representations. Remarkably, we find that the type 2 unitary matrix element equations coincide with the type 1 unitary matrix element equations for non-vanishing matrix elements up to a phase.
Giant electrocaloric effect in lead-free Ba0.94Ca0.06Ti1−xSnxO3 ceramics with tunable Curie temperature
Authors: Wang Xiangjian , Tian Fang , Zhao Chunlin , Wu Jiagang , Liu Yang , Dkhil Brahim , Zhang Ming , Gao Zhipeng , Lou Xiaojie
Published: December 2015

Electrocaloric effect in lead-free Ba0.94Ca0.06Ti1−xSnxO3 ceramics is studied using an indirect method. The Ba0.94Ca0.06Ti0.875Sn0.125O3 ceramic located near a multi-phase point shows best electrocaloric performance, which provides further experimental evidence for optimizing electrocaloric properties through constructing multiphase coexistence. Giant electrocaloric efficiency (∼0.4 K mm/kV) is achieved in this ceramic at about room temperature at a low electric field of 6 kV/cm. While large electrocaloric temperature (∼0.63 K) is obtained by further enhancing electric field (20 kV/cm), a decrease in electrocaloric efficiency (0.32 K mm/kV) is simultaneously observed, which is attributed to phase transition from first-order to more diffusive second-order under higher electric field.
Edge multi-energy soft x-ray diagnostic in Experimental Advanced Superconducting Tokamak
Authors: Li Y. L. , Xu G. S. , Tritz K. , Zhu Y. B. , Wan B. N. , Lan H. , Liu Y. L. , Wei J. , Zhang W. , Hu G. H. , Wang H. Q. , Duan Y. M. , Zhao J. L. , Wang L. , Liu S. C. , Ye Y. , Li J. , Lin X. , Li X. L.
Published: December 2015

A multi-energy soft x-ray (ME-SXR) diagnostic has been built for electron temperature profile in the edge plasma region in Experimental Advanced Superconducting Tokamak (EAST) after two rounds of campaigns. Originally, five preamplifiers were mounted inside the EAST vacuum vessel chamber attached to five vertically stacked compact diode arrays. A custom mechanical structure was designed to protect the detectors and electronics under constraints of the tangential field of view for plasma edge and the allocation of space. In the next experiment, the mechanical structure was redesigned with a barrel structure to absolutely isolate it from the vacuum vessel. Multiple shielding structures were mounted at the pinhole head to protect the metal foils from lithium coating. The pre-amplifiers were moved to the outside of the vacuum chamber to avoid introducing interference. Twisted copper cooling tube was embedded into the back-shell near the diode to limit the temperature of the preamplifiers and diode arrays during vacuum vessel baking when the temperature reached 150 °C. Electron temperature profiles were reconstructed from ME-SXR measurements using neural networks.
Study and application of a high-pressure water jet multi-functional flow test system
Authors: Shi Huaizhong , Li Gensheng , Huang Zhongwei , Li Jingbin , Zhang Yi
Published: December 2015

As the exploration and development of oil and gas focus more and more on deeper formation, hydraulic issues such as high-pressure water jet rock breaking, wellbore multiphase flow law, cuttings carrying efficiency, and hydraulic fracturing technique during the drilling and completion process have become the key points. To accomplish related researches, a high-pressure water jet multi-functional flow test system was designed. The following novel researches are carried out: study of high-pressure water jet characteristics under confining pressure, wellbore multiphase flow regime, hydraulic pressure properties of down hole tools during jet fracturing and pulsed cavitation jet drilling, and deflector’s friction in radial jet drilling. The validity and feasibility of the experimental results provided by the system with various test modules have proved its importance in the research of the high-pressure water jet and well completion technology.
Different scenarios for hyperbolicity breakdown in quasiperiodic area preserving twist maps
Authors: Figueras Jordi-Lluís , Haro Àlex
Published: December 2015

We present a computer-assisted numerical study of different bifurcations of saddle invariant tori in quasiperiodic area preserving twist maps. We detect three bifurcation scenarios. In the first scenario, the smooth bifurcation, the regularity of the invariant torus is preserved, and the stable and unstable invariant bundles collide smoothly. In the other scenarios, the spiky and folding breakdowns, the invariant torus looses smoothness, and the invariant bundles collide non-smoothly. In the former, the C1 seminorm of the torus does not blow up while in the latter it does. Numerics suggest that after the breakdowns non-uniformly hyperbolic invariant objects persist. These are qualitatively different depending on the type of breakdown. Finally, using anti-integrable limit theory, we provide a proof of existence of non-uniformly hyperbolic invariant objects for systems very far from the integrable regime.
Sound velocities in highly oriented pyrolytic graphite shocked to 18 GPa: Orientational order dependence and elastic instability
Authors: Lucas Marcel , Winey J. M. , Gupta Y. M.
Published: December 2015

Previous reports of rapid phase transformation above 18 GPa [Erskine and Nellis, Nature 349, 317 (1991)] and large elastic waves below 18 GPa [Lucas et al., J. Appl. Phys. 114, 093515 (2013)] for shock-compressed ZYB-grade highly oriented pyrolytic graphite (HOPG), but not for less oriented ZYH-grade HOPG, indicated a link between the orientational order dependence of the HOPG response above and below the phase transformation stress. To gain insight into this link and into the mechanical response of HOPG shocked to peak stresses approaching the phase transformation onset, the compressibility of ZYB- and ZYH-grade HOPG in the shocked state was examined using front surface impact experiments. Particle velocity histories and sound velocities were measured for peak stresses reaching 18 GPa. Although the locus of the measured peak stress-particle velocity states is indistinguishable for the two grades of HOPG, the measured sound velocities in the peak state reveal significant differences between the two grades. Specifically (1) the measured sound velocities are somewhat higher for ZYH-grade HOPG compared with ZYB-grade HOPG; (2) the measured sound velocities for ZYH-grade HOPG increase smoothly with compression, whereas those for ZYB-grade HOPG exhibit a significant reduction in the compression dependence from 12 GPa to 17 GPa and an abrupt increase from 17 GPa to 18 GPa; and (3) the longitudinal moduli, determined from the measured sound velocities, are smaller than the calculated bulk moduli for ZYB-grade HOPG shocked to peak stresses above 15 GPa, indicating the onset of an elastic instability. The present findings demonstrate that the softening of the longitudinal modulus (or elastic instability) presented here is linked to the large elastic waves and the rapid phase transformation reported previously—all observed only for shocked ZYB-grade HOPG. The elastic instability in shocked ZYB-grade HOPG is likely a precursor to the rapid phase transformation observed above 18 GPa for this HOPG grade.
Dust grains potential variation in a Vasyliunas Cairns-distributed plasmas with negative ions
Authors: Abid A. A. , Khan M. Z. , Wong C. S. , Yap S. L.
Published: December 2015

Dust grains' potential variation is presented by using a non-equilibrium complex (dusty) plasma following the Vasyliunas Cairns (VC)-distribution, in which the components such as the electrons, ions [positive and negative], and dust grains have negative charge. For this reason, mathematical statement of currents is solved for dust grains having negatively charge to accomplish the equilibrium state value (viz., qd = constant) in the presence of VC-distributed plasmas. Indeed, the current balance equations are modified due to the streaming/nonequilibrium distributed negative ions. Numerically, it is assessed that the important plasma variable, for example, spectral index α, spectral index κ, negative ions streaming velocity (U0), and negative ions number density (ρ), significantly influences the dust grain surface potential (|ψd|) by: (i) increasing the value of spectral index kappa (κ) and negative ions density (ρ), the magnitude of dust surface potential (|ψd|) decreases and (ii) increasing the values of spectral index α and negative ions streaming velocity (U0), dust grains surface potential (|ψd|) increases. The relevance to low-temperature research center in a non-equilibrium dusty (complex) plasma is precisely discussed by associating oxygen ions (negative and positive) species.
Ro-vibrational averaging of the isotropic hyperfine coupling constant for the methyl radical
Authors: Adam Ahmad Y. , Yachmenev Andrey , Yurchenko Sergei N. , Jensen Per
Published: December 2015

We present the first variational calculation of the isotropic hyperfine coupling constant of the carbon-13 atom in the CH3 radical for temperatures T = 0, 96, and 300 K. It is based on a newly calculated high level ab initio potential energy surface and hyperfine coupling constant surface of CH3 in the ground electronic state. The ro-vibrational energy levels, expectation values for the coupling constant, and its temperature dependence were calculated variationally by using the methods implemented in the computer program TROVE. Vibrational energies and vibrational and temperature effects for coupling constant are found to be in very good agreement with the available experimental data. We found, in agreement with previous studies, that the vibrational effects constitute about 44% of the constant’s equilibrium value, originating mainly from the large amplitude out-of-plane bending motion and that the temperature effects play a minor role.
Numerical experiment of thermal conductivity in two-dimensional Yukawa liquids
Authors: Shahzad Aamir , He Mao-Gang
Published: December 2015

A newly improved homogenous nonequilibrium molecular dynamics simulation (HNEMDS) method, proposed by the Evans, has been used to compute the thermal conductivity of two-dimensional (2D) strongly coupled complex (dusty) plasma liquids (SCCDPLs), for the first time. The effects of equilibrium external field strength along with different system sizes and plasma states (Γ, κ) on the thermal conductivity of SCCDPLs have been calculated using an enhanced HNEMDS method. A simple analytical temperature representation of Yukawa 2D thermal conductivity with appropriate normalized frequencies (plasma and Einstein) has also been calculated. The new HNEMDS algorithm shows that the present method provides more accurate results with fast convergence and small size effects over a wide range of plasma states. The presented thermal conductivity obtained from HNEMDS method is found to be in very good agreement with that obtained through the previously known numerical simulations and experimental results for 2D Yukawa liquids (SCCDPLs) and with the three-dimensional nonequilibrium molecular dynamics simulation (MDS) and equilibrium MDS calculations. It is shown that the HNEMDS algorithm is a powerful tool, making the calculations very efficient and can be used to predict the thermal conductivity in 2D Yukawa liquid systems.
The effects of insulating coatings and current prepulse on tungsten planar wire array Z-pinches
Authors: Li M. , Sheng L. , Wang L. P. , Li Y. , Zhao C. , Yuan Y. , Zhang X. J. , Zhang M. , Peng B. D. , Zhang J. H. , Zhang S. G. , Qiu M. T. , Li X. W.
Published: December 2015

This paper presents experimental results on the effects of insulating coatings and current prepulse on tungsten planar wire array Z-pinches on ∼100 ns main current facility. Optical framing images indicated that without a current prepulse the wire ablation process was asymmetrical and the implosion was zippered. The x-ray peak power was ∼320 GW. By using insulating coatings on the wire surface the asymmetry remained, and the processes of ablation and implosion were delayed by ∼30 ns. The x-ray burst was narrow and decreased to ∼200 GW. When current prepulses were used on both standard and insulated wire arrays, implosion symmetry was improved and the x-ray burst was improved (to ∼520 GW peak power). In addition, there was a strong emitting precursor column for insulated loads with the current prepulse.
Modeling of coherent ultrafast magneto-optical experiments: Light-induced molecular mean-field model
Authors: Hinschberger Y. , Hervieux P.-A.
Published: December 2015

We present calculations which aim to describe coherent ultrafast magneto-optical effects observed in time-resolved pump-probe experiments. Our approach is based on a nonlinear semi-classical Drude-Voigt model and is used to interpret experiments performed on nickel ferromagnetic thin film. Within this framework, a phenomenological light-induced coherent molecular mean-field depending on the polarizations of the pump and probe pulses is proposed whose microscopic origin is related to a spin-orbit coupling involving the electron spins of the material sample and the electric field of the laser pulses. Theoretical predictions are compared to available experimental data. The model successfully reproduces the observed experimental trends and gives meaningful insight into the understanding of magneto-optical rotation behavior in the ultrafast regime. Theoretical predictions for further experimental studies are also proposed.
Impurity-limited resistance and phase interference of localized impurities under quasi-one dimensional nano-structures
Authors: Sano Nobuyuki
Published: December 2015

The impurity-limited resistance and the effect of the phase interference among localized multiple impurities in the quasi-one dimensional (quasi-1D) nanowire structures are systematically investigated under the framework of the scattering theory. We derive theoretical expressions of the impurity-limited resistance in the nanowire under the linear response regime from the Landauer formula and from the Boltzmann transport equation (BTE) with the relaxation time approximation. We show that the formula from the BTE exactly coincides with that from the Landauer approach with the weak-scattering limit when the energy spectrum of the in-coming electrons from the reservoirs is narrow and, thus, point out a possibility that the distinction of the impurity-limited resistances derived from the Landauer formula and that of the BTE could be made clear. The derived formulas are applied to the quasi-1D nanowires doped with multiple localized impurities with short-range scattering potential and the validity of various approximations on the resistance are discussed. It is shown that impurity scattering becomes so strong under the nanowire structures that the weak-scattering limit breaks down in most cases. Thus, both phase interference and phase randomization simultaneously play a crucial role in determining the impurity-limited resistance even under the fully coherent framework. When the impurity separation along the wire axis direction is small, the constructive phase interference dominates and the resistance is much greater than the average resistance. As the separation becomes larger, however, it approaches the series resistance of the single-impurity resistance due to the phase randomization. Furthermore, under the uniform configuration of impurities, the space-average resistance of multiple impurities at room temperature is very close to the series resistance of the single-impurity resistance, and thus, each impurity could be regarded as an independent scattering center. The physical origin of this “self-averaging” under the fully coherent environments is attributed to the broadness of the energy spectrum of the in-coming electrons from the reservoirs.