bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of HMGB1 on the Paracrine Action of EPC Promotes Post-Ischemic Neovascularization in Mice
Authors: Chen Chao , Lin Xiaojie , Wang Jixian , Tang Guanghui , Mu Zhihao , Chen Xiaoyan , Xu Jin , Wang Yongting , Zhang Zhijun , Yang Guo-Yuan
Published: May 2014

Transplantation of endothelial progenitor cells (EPCs) leads to better outcomes in experimental stroke, but the mechanism remains unclear. It was reported that astrocytic-high mobility group box1 (HMGB1) promoted endogenous EPC-mediated neurovascular remodeling during stroke recovery. It is unclear whether HMGB1 involves in exogenous EPC-mediated stroke recovery. In this study, we aim to explore whether microglial HMGB1 contributes to human peripheral blood-derived (hPB)-EPCs-mediated neurovascular remodeling by modulating the paracrine function of exogenous hPB-EPCs. Coculturing hPB-EPCs with lipopolysaccharides stimulated BV2 cells upregulated Interleukin-8 expression in hPB-EPCs; this was blocked by treating BV2 cells with HMGB1 inhibitor Glycyrrhizin. Conditioned medium (CM) of hPB-EPCs cocultured with BV2 cells promoted the viability and tube formation of human umbilical cord vein cells. Inhibiting either HMGB1 or IL-8 could block the effect of hPB-EPCs CM. In vivo study showed hPB-EPCs transplantation improved neurobehavioral outcomes, reduced brain atrophy volume, and enhanced neovascularization in transient middle cerebral artery occlusion (tMCAO) mice. Intraperitoneally administration of HMGB1 inhibitor glycyrrhizin blocked the beneficial effect of hPB-EPC transplantation. We did not observe the integration of green fluorescent protein-labeled hPB-EPCs with microvessels in peri-infarct areas at day-14 after tMCAO. In summary, the result suggested that HMGB1 upregulation in postischemic brain could promote exogenous hPB-EPC-mediated stroke recovery by modulating paracrine function of hPB-EPCs. Stem Cells  2014;32:2679–2689
Multidisciplinary design modeling and optimizationfor satellite with maneuver capability
Authors: Huang Hai , An Haichao , Wu Wenrui , Zhang Lingyan , Wu Beibei , Li Weipeng
Published: May 2014

According to the mission of a satellite with maneuver capability, the collaborative optimization (CO) method was introduced for the satellite system design, and the related multidisciplinary design optimization (MDO) model was established. The possessing and needed velocity increments Δv and Δv

n
e
e
d
were taken as the measurement of maneuvering capability of the studied satellite, which were then combined with total mass of the satellite to form the optimization objective in the systematic level of the MDO problem. The design variables and constraints of the MDO problem dealt with disciplines or subsystems as guidance, navigation and control (GNC), power, and structure, and corresponding engineering analysis models were also built. A program system to solve the MDO problem wasdeveloped by integrating a non-nested CO method, the commercial and user-supplied codes on framework software iSIGHT. The result showed that the satellite performance could be obviously improved, which also indicates MDO technique is feasible and effective for the spacecraft design problem. The modeling and optimization procedure of the work can be referred for further research and engineering design.
Temporary sterilization behavior of mutualistic partner ants in a Southeast Asian myrmecophyte
Authors: Fiala Brigitte , Meyer Ute , bin Hashim Rosli , Maschwitz Ulrich
Published: May 2014

Obligate ant–plant interactions are known to be mutualistic but plant‐ants that destroy flowers of their hosts have been reported. They were regarded as parasites in myrmecophytic systems. The mechanisms that lead to flower damage (sterilization) by plant‐ants are not easy to understand as most sterilizing ants are actually regular colonizers of their plants and normally offer protection against herbivores and/or plant competition. It is difficult to find general patterns of ant or plant traits even in the few yet known associations of flower sterilization. We here present the first study from Southeast Asia where flower sterilizing occurs in the complex mutualistic Macaranga–Crematogaster system that differs from other cases. Flowers of M. hullettii in the Gombak Valley were destroyed by all three associated specific and otherwise protective Crematogaster species. The hypotheses that limitation of nesting space or food are main proximate factors for flower destruction were not strongly supported in our study system. Ants are even attracted to flowers by special food bodies produced by the plants. Only younger, not yet reproductive colonies were found to destroy flowers but not colonies with alates, indicating that flower sterilization behavior may only occur when the onset of host reproduction precedes ant reproduction, perhaps leading to a change in ant behavior. Fruit set always occurred in larger trees, and saplings for colonizing ant queens were therefore always present in the local population, stabilizing the association.
Hypercholesterolemia Increases Plasma Saturated and n‐6 Fatty Acids Altering Prostaglandin Homeostasis and Promotes Endothelial Dysfunction in Rabbits
Authors: Medina M. , Alberto M. R. , Sierra L. , Van Nieuwenhove C. , Saad S. , Isla M. I. , Jerez S.
Published: May 2014

The present study evaluated the plasma fatty acid levels and the vascular prostaglandin (PG) release in a rabbit model of early hypercholesterolemia with endothelial dysfunction. Rabbits were fed either a control diet (CD) or a diet containing 1 % cholesterol (HD) for 5–6 weeks. The level of fatty acids was measured in plasma. The levels of PG and nitric oxide (NO) released from the aorta were also determined. Vascular morphology of the aorta was characterized by intima and media thickness measurements. The rabbits fed with HD had higher levels of arachidonic acid (ARA) and lower levels of oleic acid. The linoleic acid level was unchanged. PGI2 and NO were diminished and PGF2α levels, the PGI2/TXA2 ratio and the intima/media ratio were increased in rabbits fed with HD. In conclusion, feeding HD for a short period increased ARA plasma levels and unbalanced release of vasodilator/vasoconstrictor PG redirected the pathway to vasoconstrictor metabolite release. These lipid metabolism alterations in addition to the reduced NO levels and the moderate changes in the vascular morphology contributed to the endothelial dysfunction in this animal model. Therefore, the present findings support the importance of early correction or prevention of high cholesterol levels to disrupt the endothelial dysfunction process that leads to cardiovascular disease.
Peri-operative complications in pediatric and adolescent shoulder arthroscopy
Authors: Edmonds Eric W. , Lewallen Laura W. , Murphy Michael , Dahm Diane , McIntosh Amy L.
Published: May 2014

Background

Shoulder arthroscopy is not common in the pediatric and adolescent population, but the frequency may be on the rise. The purpose of the study was to determine the incidence of acute complications of arthroscopic shoulder surgery in children and adolescents.

Methods

A retrospective, cross-sectional review was performed identifying patients aged 18 years or less who underwent an arthroscopic shoulder procedure from 1997 to 2009 at Institution 1 and 2007 to 2010 at Institution 2. Exclusion criteria included open procedures and missing records. Demographic and surgical data were collected, including intra-operative and post-operative complications during the first 6 months. The complications were divided into minor (no secondary treatment) and major (secondary treatment rendered).

Results

Two hundred children, mean age 15.9 years, met criteria and 73 % were boys. All procedures were performed under general anesthesia, but 51 % included inter-scalene regional anesthesia. There were 16 (8.0 %) total complications recorded. Major complications occurred in five (2.5 %) patients, including two tendinitis/bursitis requiring injections, one broken pain pump catheter requiring an accessory incision to retrieve, one pain control readmission, and one laceration of the cephalic vein requiring ligation. Minor complications occurred in 11 (5.5 %) patients, including allergic reactions, transient dysesthesias, headaches, bronchitis, syncope, transient hypotension, and uvula swelling.

Conclusion

Although we found no seriously deleterious outcomes, it is important to recognize that an additional service was rendered for 2.5 % of children undergoing shoulder arthroscopy. The events that did occur may be preventable and this study should serve as a baseline to improve quality and safety of shoulder arthroscopy in the pediatric population.
The prevalence of bifid iliopsoas tendon on MRI in children
Authors: Crompton Thomas , Lloyd Claire , Kokkinakis Michail , Norman-Taylor Fabian
Published: May 2014

Objective

The variation in the anatomy of the iliopsoas tendon is important information for orthopaedic surgeons operating around the hip. The aim of this study was to identify the prevalence of bifid iliopsoas tendons in children on magnetic resonance imaging (MRI).

Methods

MRI hip and pelvis images of 50 sequential children aged 7–15 years were retrieved from our radiology database at the Evelina London Children's Hospital from 2007 to 2013. Included were 37 children with imaging of both hips and 13 children with imaging of one hip only. Therefore, our study was based on a total of 87 hips.

Results

At least 1 bifid tendon was noted in 13 children (26 %). Five children from a total of 37 (14 %) with both hips adequately imaged had bilateral bifid tendons. Among all 87 adequately imaged hips, 18 (21 %) were found to have two discrete distal iliopsoas tendons.

Conclusions

Bifid iliopsoas tendon is noted anecdotally by surgeons but was only reported in scattered case reports and a few anatomical studies until very recently. Our finding is that a bifid iliopsoas tendon with two distinct tendinous components at the level of the hip joint is quite common. This has clinical significance, particularly in children's orthopaedic surgery when an adequate iliopsoas release is important.
Commentaries and Rejoinder on
Authors: Monin Benoît , Oppenheimer Daniel M. , Ferguson Melissa J. , Carter Travis J. , Hassin Ran R. , Crisp Richard J. , Miles Eleanor , Husnu Shenel , Schwarz Norbert , Strack Fritz , Klein Richard A. , Ratliff Kate A. , Vianello Michelangelo , Adams Reginald B. , Bahník Štěpán , Bernstein Michael J. , Bocian Konrad , Brandt Mark J. , Brooks Beach , Chloe Brumbaugh Claudia , Cemalcilar Zeynep , Chandler Jesse , Cheong Winnee , Davis William E. , Devos Thierry , Eisner Matthew , Frankowska Natalia , Furrow David , Maria Galliani Elisa , Hasselman Fred , Hicks Joshua A. , Hovermale James F. , Jane Hunt S. , Huntsinger Jeffrey R. , IJzerman Hans , John Melissa-Sue , Joy-Gaba Jennifer A. , Barry Kappes Heather , Krueger Lacy E. , Kurtz Jaime , Levitan Carmel A. , Mallett Robyn K. , Morris Wendy L. , Nelson Anthony J. , Nier Jason A. , Packard Grant , Pilati Ronaldo , Rutchick Abraham M. , Schmidt Kathleen , Skorinko Jeanine L. , Smith Robert , Steiner Troy G. , Storbeck Justin , Van Swol Lyn M. , Thompson Donna , van ‘t Veer A. E. , Ann Vaughn Leigh , Vranka Marek , Wichman Aaron L. , Woodzicka Julie A. , Nosek Brian A. , Kahneman Daniel
Published: May 2014

While direct replications such as the “Many Labs” project are extremely valuable in testing the reliability of published findings across laboratories, they reflect the common reliance in psychology on single vignettes or stimuli, which limits the scope of the conclusions that can be reached. New experimental tools and statistical techniques make it easier to routinely sample stimuli, and to appropriately treat them as random factors. We encourage researchers to get into the habit of including multiple versions of the content (e.g., stimuli or vignettes) in their designs, to increase confidence in cross-stimulus generalization and to yield more realistic estimates of effect size. We call on editors to be aware of the challenges inherent in such stimulus sampling, to expect and tolerate unexplained variability in observed effect size between stimuli, and to encourage stimulus sampling instead of the deceptively cleaner picture offered by the current reliance on single stimuli.
Commentaries and Rejoinder on
Authors: Gong Han , Medin Douglas L. , Eyal Tal , Liberman Nira , Trope Yaacov , Žeželj Iris L. , Jokić Biljana R.
Published: May 2014

In the hope to resolve the two sets of opposing results concerning the effects of psychological distance and construal levels on moral judgment, Žeželj and Jokić (2014) conducted a series of four direct replications, which yielded divergent patterns of results. In our commentary, we first revisit the consistent findings that lower-level construals induced by How/Why manipulation lead to harsher moral condemnation than higher-level construals. We then speculate on the puzzling patterns of results regarding the role of temporal distance in shaping moral judgment. And we conclude by discussing the complexity of morality and propose that it may be important to incorporate cultural systems into the study of moral cognition.
Fast recovery of free energy landscapes via diffusion-map-directed molecular dynamics
Authors: Preto Jordane , Clementi Cecilia
Published: May 2014

An adaptive sampling algorithm is proposed to rapidly reconstruct free-energy landscapes of macromolecular systems.
Star block-copolymers: enzyme-inspired catalysts for oxidation of alcohols in water
Authors: Mugemana Clément , Chen Ba-Tian , Bukhryakov Konstantin V. , Rodionov Valentin
Published: May 2014

We describe a family of star block-copolymers rationally designed for enzyme-inspired catalysis of alcohol oxidation in water.
Attenuated migration by green tea extract (−)-epigallocatechin gallate (EGCG): involvement of 67 kDa laminin receptor internalization in macrophagic cells
Authors: Ren Xuezhi , Guo Xingzhi , Chen Li , Guo Minxia , Peng Ning , Li Rui
Published: May 2014

Inhibition of macrophagic cell migration induced by green tea polyphenol EGCG may be linked to the internalization of 67 kDa laminin receptor.
Magnetic gold nanocatalyst (nanocat-Fe–Au): catalytic applications for the oxidative esterification and hydrogen transfer reactions
Authors: Gawande Manoj B. , Rathi Anuj K. , Tucek Jiri , Safarova Klara , Bundaleski Nenad , Teodoro Orlando M. N. D. , Kvitek Libor , Varma Rajender S. , Zboril Radek
Published: May 2014

Maghemite-supported gold (nanocat-Fe–Au) nanocatalyst enables the oxidative esterification of aldehydes and reduction of aromatic nitro compounds in benign medium.
Exploring the meaning of sugar configuration in a supramolecular environment: comparison of six octyl glycoside micelles by ITC and NMR spectroscopy
Authors: Schmidt-Lassen Jörn , Lindhorst Thisbe K.
Published: May 2014

To promote understanding of sugar configuration in a supramolecular context, glycomicelles were compared and a “trinity projection” of glycosides proposed.
Multivalent amino sugars to recognize different TAR RNA conformations
Authors: Kellish Patrick C. , Kumar Sunil , Mack Todd S. , Spano Meredith Newby , Hennig Mirko , Arya Dev P.
Published: May 2014

Neomycin dimers synthesized using “click chemistry” with varying functionality and length in the linker region have been shown to be effective in targeting the HIV-1 TAR RNA region of the HIV virus.
Structural, spectroscopic and theoretical studies on dixanthogens: (ROC(S)S)2, with R = n-propyl and isopropyl
Authors: Juncal Luciana C. , Tobón Yeny A. , Piro Oscar E. , Della Védova Carlos O. , Romano Rosana M.
Published: May 2014

The properties of the two dixanthogens were interpreted in terms of the conformational flexibility of the n-propyl group compared with the isopropyl one.
Organic synthetic transformations using organic dyes as photoredox catalysts
Authors: Fukuzumi Shunichi , Ohkubo Kei
Published: May 2014

This review article presents various photocatalytic transformation such as oxygenation, halogenation and C–C bond formation with organic photoredox catalysts.
Phosphazene-catalyzed ring-opening polymerization of ε-caprolactone: influence of solvents and initiators
Authors: Alamri Haleema , Zhao Junpeng , Pahovnik David , Hadjichristidis Nikos
Published: May 2014

Metal-free ring-opening polymerization of ε-caprolactone was conducted using a relatively mild phosphazene base catalyst. The influence of solvents and protic initiators on the polymerization rate and control was demonstrated.
Unprecedented cucurbituril-based ternary host–guest supramolecular polymers mediated through included alkyl chains
Authors: Xiao Xin , Sun Nana , Qi Dongdong , Jiang Jianzhuang
Published: May 2014

Novel ternary host–guest supramolecular polymers constructed from Q[8] and 1′,1′′-(alkylene-1,4-diyl)bis(1-butyl)-4,4′-(bipyridine-1,1′-diium)bromide with included alkyl chains as the mediating functional groups have been fabricated and structurally characterized for the first time.
Intercalated polyfluorinated Pd complexes in α-zirconium phosphate for Sonogashira and Heck reactions
Authors: Lu Norman , Lin Kwan-Yu , Kung Chih-Chieh , Jhuo Jyun-Wei , Zhou Yingjie , Liu Jingjing , Sun Luyi
Published: May 2014

A direct method was used to effectively intercalate the short fluorous-ponytailed Pd complexes into the ZrP gallery, and the resulting Pd intercalated ZrP could be used as a recoverable catalyst for Sonogashira and Heck reactions.
Biomimetic graphene oxide–hydroxyapatite composites via in situ mineralization and hierarchical assembly
Authors: Li Yaling , Liu Cuilian , Zhai Halei , Zhu Genxing , Pan Haihua , Xu Xurong , Tang Ruikang
Published: May 2014

A graphene oxide (GO)–hydroxyapatite (HAP) hybrid with excellent mechanical properties and biocompatibility is synthesizedvia in situmineralization and hierarchical assembly.
Adding ethanol can effectively enhance the graphene concentration in water–surfactant solutions
Authors: Wang Shuai , Yi Min , Shen Zhigang , Zhang Xiaojing , Ma Shulin
Published: May 2014

Adding a suitable amount of ethanol into a water–surfactant dispersion can enhance the graphene concentration up to 3 times. The combination of water and ethanol can decrease the exfoliation energy while the surfactant acts as a stabilizer preventing graphene sheets from agglomeration.
Environmentally friendly solution route to kesterite Cu2ZnSn(S,Se)4thin films for solar cell applications
Authors: Li Zhenggang , Ho John C. W. , Lee Kian Keat , Zeng Xin , Zhang Tianliang , Wong Lydia Helena , Lam Yeng Ming
Published: May 2014

Solar cells were made from Cu2ZnSn(S,Se)4thin films prepared using an ink consisting of CuS, ZnS and SnS2nanoparticles dispersed in water.
Shear-driven aggregation of SU-8 microrods in suspension
Authors: Kumar Pramukta , Gold David , Blair Daniel L. , Baskaran Aparna , Urbach Jeffrey S.
Published: May 2014

A non-Brownian suspension of micron scale rods exhibits reversible shear-driven formation of disordered aggregates resulting in dramatic viscosity enhancement at low shear rates.
Micro and macrorheology at fluid–fluid interfaces
Authors: Samaniuk Joseph R. , Vermant Jan
Published: May 2014

Interfacial transport phenomena play an important role in the dynamics of liquid interfaces found in emulsions, foams, and membranes.
Invertible vesicles and micelles formed by dually-responsive diblock random copolymers in aqueous solutions
Authors: Savoji Mohammad T. , Strandman Satu , Zhu X. X.
Published: May 2014

Dually responsive diblock random copolymers poly(nPA0.8-co-DEAEMA0.2)-block-poly(nPA0.8-co-EA0.2) were made from random blocks of N-n-propylacrylamide (nPA), 2-(diethylamino)ethyl methacrylate (DEAEMA) and N-ethylacrylamide (EA) via reversible addition–fragmentation chain transfer (RAFT) polymerization.
Three-dimensional hierarchical pompon-like Co3O4 porous spheres for high-performance lithium-ion batteries
Authors: Hao Wenjun , Chen Shimou , Cai Yingjun , Zhang Lan , Li Zengxi , Zhang Suojiang
Published: May 2014

3D hierarchical pompon-like Co3O4 porous spheres were produced by a simple hydrothermal method. The 3D structure is composed of many nanowires which gathered as a ring in the centre and fanned out via a special self-assembly fashion, resulting in good lithium ion battery performance.
Toxicity of arsenite and thio-DMAV after long-term (21 days) incubation of human urothelial cells: cytotoxicity, genotoxicity and epigenetics
Authors: Unterberg Marlies , Leffers Larissa , Hübner Florian , Humpf Hans-Ulrich , Lepikhov Konstantin , Walter Jörn , Ebert Franziska , Schwerdtle Tanja
Published: May 2014

This study aims to further mechanistically understand toxic modes of action after chronic arsenic species exposure.
Aerodynamic force by Lamb vector integrals in compressible flow
Authors: Mele Benedetto , Tognaccini Renato
Published: May 2014

A new exact expression of the aerodynamic force acting on a body in steady high Reynolds number (laminar and turbulent) compressible flow is proposed. The aerodynamic force is obtained by integration of the Lamb vector field given by the cross product of vorticity times velocity. The result is obtained extending a theory developed for the incompressible case. A decomposition in lift and drag contribution is obtained in the two-dimensional case. The theory links the force generation to local flow properties, in particular to the Lamb vector field and to the kinetic energy. The theoretical results are confirmed analyzing numerical solutions obtained by a standard Reynolds Averaged Navier-Stokes solver. Results are discussed for the case of a two-dimensional airfoil in subsonic, transonic, and supersonic free stream conditions.
A general model for estimating the ordering of mesoporous film by grazing incidence small angle X-ray scattering
Authors: Zhao Nie , Yang Chunming , Zhang Qian , Lu Xueming , Wang Yuzhu , Wang Jie
Published: May 2014

The ability to quantifiably characterize the structure of mesoporous membranes over a large sample surface area is inherently crucial to the preparation of well-controlled and functional mesoporous silica films. To estimate the degree of ordering in silica films on a statistical level, grazing incidence small angle x-ray scattering (GISAXS) was used to analyze the nanostructure of silica films with high-ordered mesochannel arrays, and a general analysis model was developed for interpreting the resulting GISAXS patterns. Structural information on the films, including the mesochannel size, orientation, positional distribution factor, subunit number in coherent region, and mesochannel length distribution, were obtained by fitting the model to the experimental data. The GISAXS analysis results showed the gradually decreasing ordering of silica film, which can be attributed to two aspects: the positional deviation from ideal lattice sites in the plane perpendicular to the substrate surface, and the wide length distribution of the mesochannels. The proposed model is expected to be successfully extendable to the analysis of several other types of mesoporous film with different pore morphologies.
Symmetry and relaxation dynamics of spin s = 1 magnets
Authors: Kovalevsky M. Y. , Glushchenko A. V.
Published: June 2014

Pure and mixed quantum states of spin s = 1 magnets are examined by introducing a polarization density matrix. Uniaxial and biaxial quadrupole orderings corresponding to pure magnetic states are found and the degrees of polarization are calculated. The types of normal and degenerate magnetic states associated with subalgebras of Poisson brackets of the magnetic degrees of freedom are established. The spectra of collective magnetic excitations are calculated taking damping in the normal and degenerate states into account.
More stable hybrid organic solar cells deposited on amorphous Si electron transfer layer
Authors: Samiee Mehran , Modtland Brian , Aidarkhanov Damir , Dalal Vikram L.
Published: May 2014

We report on defect densities, performance, and stability of organic/inorganic hybrid solar cells produced using n-doped inorganic amorphous silicon-carbide layers as the electron transport layer (ETL). The organic material was poly-3-hexyl-thiophene (P3HT) and heterojunction was formed using phenyl-C71-Butyric-Acid-Methyl Ester (PCBM). For comparison, inverted solar cells fabricated using Cs2CO3 as ETL were fabricated. Defect densities and subgap quantum efficiency curves were found to be nearly identical for both types of cells. The cells were subjected to 2xsun illumination and it was found that the cells produced using doped a-Si as ETL were much more stable than the cells produced using Cs2CO3.
Effect of particle adsorption rates on the disproportionation process in pickering stabilised bubbles
Authors: Ettelaie Rammile , Murray Brent
Published: May 2014

The degree of shrinkage of particle stabilised bubbles of various sizes, in a polydisperse bubble dispersion, has been investigated in the light of the finite adsorption times for the particles and the disproportionation kinetics of the bubbles. For the case where the system contains an abundance of particles we find a threshold radius, above which bubbles are stabilised without any significant reduction in their size. Bubbles with an initial radius below this threshold on the other hand undergo a large degree of shrinkage prior to stabilisation. As the ratio of the available particles to the bubbles is reduced, it is shown that the final bubble size, for the larger bubbles in the distribution, becomes increasingly governed by the number of particles, rather than their adsorption time per se. For systems with “adsorption controlled” shrinkage ratio, the final bubble distribution is found to be wider than the initial one, while for a “particle number controlled” case it is actually narrower. Starting from a unimodal bubble size distribution, we predict that at intermediate times, prior to the full stabilisation of all bubbles, the distribution breaks up into a bimodal one. However, the effect is transient and a unimodal final bubble size distribution is recovered, when all the bubbles are stabilised by the particles.
Origin of ejecta in the water impact problem
Authors: Krechetnikov R.
Published: May 2014

This work presents the analysis of the flow resulting from the flat plate impact on the surface of an incompressible viscous liquid at zero deadrise angle—of particular interest is the flow structure near the plate edge, r → 0, evolving at early times, t → 0. The deduced mathematical formulation proves to be of a singular perturbation type with the underlying governing equations having a linear structure. The key goals here are to elucidate the effects of viscosity and surface tension, which turn out to contribute to the solution at the leading order, and to resolve both t → 0 and r → 0 limit singularities in the classical pressure-impulse theory. In the course of construction of the solution, first the standard assumptions behind the existence of the inviscid approximation are revisited, which leads to correcting the previously known interpretation of the self-similarity of the classical inviscid solution near the plate edge. Second, new scalings of the solution structure near the plate edge are determined, with which the viscous solution near the edge is constructed analytically and matched to the inviscid one. Finally, the analysis of both the Stokes and inviscid limits of this uniformly valid solution allows us to uncover the scalings for the early time-evolution of ejecta—a jet forming during the impact—as well as to clarify the applicability of the Kutta-Joukowsky condition used in previous studies.
Structural, electronic, mechanical, and dynamical properties of graphene oxides: A first principles study
Authors: Dabhi Shweta D. , Gupta Sanjay D. , Jha Prafulla K.
Published: May 2014

We report the results of a theoretical study on the structural, electronic, mechanical, and vibrational properties of some graphene oxide models (GDO, a-GMO, z-GMO, ep-GMO and mix-GMO) at ambient pressure. The calculations are based on the ab-initio plane-wave pseudo potential density functional theory, within the generalized gradient approximations for the exchange and correlation functional. The calculated values of lattice parameters, bulk modulus, and its first order pressure derivative are in good agreement with other reports. A linear response approach to the density functional theory is used to derive the phonon frequencies. We discuss the contribution of the phonons in the dynamical stability of graphene oxides and detailed analysis of zone centre phonon modes in all the above mentioned models. Our study demonstrates a wide range of energy gap available in the considered models of graphene oxide and hence the possibility of their use in nanodevices.
Phase transitions in K-doped MoO2
Authors: Alves L. M. S. , de Lima B. S. , dos Santos C. A. M. , Rebello A. , Masunaga S. H. , Neumeier J. J. , Leão J. B.
Published: May 2014

K0.05MoO2 has been studied by x-ray and neutron diffractometry, electrical resistivity, magnetization, heat capacity, and thermal expansion measurements. The compound displays two phase transitions, a first-order phase transition near room temperature and a second-order transition near 54 K. Below the transition at 54 K, a weak magnetic anomaly is observed and the electrical resistivity is well described by a power-law temperature dependence with exponent near 0.5. The phase transitions in the K-doped MoO2 compound have been discussed for the first time using neutron diffraction, high resolution thermal expansion, and heat capacity measurements as a function of temperature.
A cavity ring-down spectroscopy sensor for real-time Hall thruster erosion measurements
Authors: Lee B. C. , Huang W. , Tao L. , Yamamoto N. , Gallimore A. D. , Yalin A. P.
Published: May 2014

A continuous-wave cavity ring-down spectroscopy sensor for real-time measurements of sputtered boron from Hall thrusters has been developed. The sensor uses a continuous-wave frequency-quadrupled diode laser at 250 nm to probe ground state atomic boron sputtered from the boron nitride insulating channel. Validation results from a controlled setup using an ion beam and target showed good agreement with a simple finite-element model. Application of the sensor for measurements of two Hall thrusters, the H6 and SPT-70, is described. The H6 was tested at power levels ranging from 1.5 to 10 kW. Peak boron densities of 10 ± 2 × 1014 m−3 were measured in the thruster plume, and the estimated eroded channel volume agreed within a factor of 2 of profilometry. The SPT-70 was tested at 600 and 660 W, yielding peak boron densities of 7.2 ± 1.1 × 1014 m−3, and the estimated erosion rate agreed within ∼20% of profilometry. Technical challenges associated with operating a high-finesse cavity in the presence of energetic plasma are also discussed.
Turbulent dispersion via fan-generated flows
Authors: Halloran Siobhan K. , Wexler Anthony S. , Ristenpart William D.
Published: May 2014

Turbulent dispersion of passive scalar quantities has been extensively studied in wind tunnel settings, where the flow is carefully conditioned using flow straighteners and grids. Much less is known about turbulent dispersion in the “unconditioned” flows generated by fans that are ubiquitous in indoor environments, despite the importance of these flows to pathogen and contaminant transport. Here, we demonstrate that a point source of scalars released into an airflow generated by an axial fan yields a plume whose width is invariant with respect to the fan speed. The results point toward a useful simplification in modeling of disease and pollution spread via fan-generated flows.
Mechanical constitutive behavior and exceptional blocking force of lead-free BZT-xBCT piezoceramics
Authors: Brandt David R. J. , Acosta Matias , Koruza Jurij , Webber Kyle G.
Published: May 2014

The free strain during unipolar electrical activation and the blocking stress are important figures of merit for actuator applications. The lead-free (1 − x)Ba(Zr0.2Ti0.8)O3−x(Ba0.7Ca0.3)TiO3 (BZT-xBCT) system has been shown to display exceptional unipolar strain at room temperature, making it very attractive as an electroactive material for large displacement, low frequency actuation systems. In this work, the temperature- and composition-dependent blocking stress is measured with the proportional loading method. It was found that BZT-xBCT outperformed Pb(Zr1−xTix)O3 and Bi1/2Na1/2TiO3–based ceramics for electric fields up to 2 kV/mm.
Physisorption of molecular hydrogen on carbon nanotube with vacant defects
Authors: Sun Gang , Tangpanitanon Jirawat , Shen Huaze , Wen Bo , Xue Jianming , Wang Enge , Xu Limei
Published: May 2014

Physisorption of molecular hydrogen on single-walled carbon nanotubes (SWCNTs) is important for its engineering applications and hydrogen energy storage. Using molecular dynamics simulation, we study the physisorption of molecular hydrogen on a SWCNT with a vacant defect, focusing on the effect of the vacant defect size and external parameters such as temperature and pressure. We find that hydrogen can be physisorbed inside a SWCNT through a vacant defect when the defect size is above a threshold. By controlling the size of the defects, we are able to extract hydrogen molecules from a gas mixture and store them inside the SWCNT. We also find that external parameters, such as low temperature and high pressure, enhance the physisorption of hydrogen molecules inside the SWCNT. In addition, the storage efficiency can be improved by introducing more defects, i.e., reducing the number of carbon atoms on the SWCNT.
Ionization satellites of the ArHe dimer
Authors: Miteva Tsveta , Klaiman Shachar , Gromov Evgeniy V. , Gokhberg Kirill
Published: May 2014

Ionization satellites are key ingredients in the control of post ionization processes such as molecular dissociation and interatomic Coulombic decay. Here, using the high-level ab initio method of multi-reference configuration interaction up to triple excitations, we study the potential energy curves (PECs) of the ionization satellites of the ArHe dimer. With this model system, we demonstrate that the simple model used in alkaline earth metal and rare gas complexes to describe the satellites as a Rydberg electron moving on top of a dicationic core does not fully hold for the rare gas clusters. The more complex valence structure in the rare gas atom leads to the mixing of different electronic configurations of the dimer. This prevents one from assigning a single dicationic parent state to some of the ionization satellites. We further analyze the structure of the different PECs, demonstrating how the density of the Rydberg electron is reflected in the structure of the PEC wherever the simple model is applicable.
First principles investigations on the electronic structure of anchor groups on ZnO nanowires and surfaces
Authors: Dominguez A. , Lorke M. , Schoenhalz A. L. , Rosa A. L. , Frauenheim Th. , Rocha A. R. , Dalpian G. M.
Published: May 2014

We report on density functional theory investigations of the electronic properties of monofunctional ligands adsorbed on ZnO-(1010) surfaces and ZnO nanowires using semi-local and hybrid exchange-correlation functionals. We consider three anchor groups, namely thiol, amino, and carboxyl groups. Our results indicate that neither the carboxyl nor the amino group modify the transport and conductivity properties of ZnO. In contrast, the modification of the ZnO surface and nanostructure with thiol leads to insertion of molecular states in the band gap, thus suggesting that functionalization with this moiety may customize the optical properties of ZnO nanomaterials.
Dispersion relations for the dust-acoustic wave under experimental conditions
Authors: Suranga Ruhunusiri W. D. , Goree J.
Published: May 2014

The dust acoustic wave dispersion relation is tested to quantify its sensitivity to many physical processes that are important in laboratory dusty plasmas. It is found that inverse Landau damping and ion-neutral collisions contribute about equally to the growth rate ωi, pointing to the advantage of using a kinetic model for the instability. The growth rate ωi increases the most with an increase of dust number density, followed by an increase in ion-drift speed. The quantities that cause ωi to decrease the most when they are increased are the dust-neutral collision rate followed by the ion-neutral collision rate, ion collection current onto dust particles, and the ion thermal speed. In general, ωi is affected more than ωr by the choice of processes that are included. Strong Coulomb-coupling effects can be included in a compressibility term. The susceptibilities derived here can be combined in various ways in a dispersion relation to account for different combinations of physical processes.
Interdiffusion across solid electrolyte-electrode interface
Authors: Hu Jia-Mian , Liang Linyun , Ji Yanzhou , Hong Liang , Gerdes Kirk , Chen Long-Qing
Published: May 2014

A phase-field model is developed for studying the cation interdiffusion across electrolyte-electrode interfaces in solid oxide fuel cell (SOFC) that can be contributing to long timescale performance degradation. Demonstrated on an interface between an 8%molY2O3-stabilized ZrO2 and a La0.65Sr0.3MnO3−x typically used in SOFC, time-dependent evolution of the cation interdiffusion profiles are predicted by linking the phase-field model to a diffusion equation. The simulated interdiffusion profiles agree with independent experimental data in both time and space domains at different temperatures.
Influence of gridded gate structure on gas sensing behavior of hydrogen
Authors: Kumar Vinod , Mishra Sunny, V. N. , Dwivedi R. , Das R. R.
Published: May 2014

A gridded Pt/SiO2/Si MOS sensor for hydrogen detection has been fabricated on p-type ⟨100⟩ Si wafer having resistivity (1–6 Ω cm). The SiO2 and Platinum (Pt) gate thickness were kept about 10 nm and 35 nm. The performance of Pt gate MOS sensor was evaluated through C-V characteristics (capacitance vs voltage) upon exposure to H2 (250 ppm–4000ppm) at different frequencies (25 kHz and 50 kHz) in a closed chamber at air ambient atmosphere. The capacitance of the sensor decreases with increase in frequency as well as H2 gas concentration. The flat band voltage characteristics have been evaluated at different frequencies and concentrations. It decreases as the frequency and concentration of gas both increases. The maximum flat band voltage change was observed −0.6 V at 25 kHz. The sensor exhibits better sensitivity (∼88%) at low frequency (25 kHz). The high response of sensor is attributed to the side wall diffusion, increase in surface area caused by inner side wall and increase in porosity, increase in fixed surface state density, spill-over mechanism and change in interface state density on exposure of gas along with the formation of dipole layer.
Structure–performance relationships for cantilever-type piezoelectric energy harvesters
Authors: Cho Kyung-Hoon , Park Hwi-Yeol , Heo Jin S. , Priya Shashank
Published: May 2014

This study provides comprehensive analysis of the structure–performance relationships in cantilever-type piezoelectric energy harvesters. It provides full understanding of the effect of all the practical global control variables on the harvester performance. The control variables considered for the analysis were material parameters, areal and volumetric dimensions, and configuration of the inactive and active layers. Experimentally, the output power density of the harvester was maximum when the shape of the beam was close to a square for a constant bending stiffness and a fixed beam area. Through analytical modeling of the effective stiffness for the piezoelectric bimorph, the conditions for enhancing the bending stiffness within the same beam volume as that of a conventional bimorph were identified. The harvester configuration with beam aspect ratio of 0.86 utilizing distributed inactive layers exhibited an giant output power of 52.5 mW and power density of 28.5 mW cm−3 at 30 Hz under 6.9 m s−2 excitation. The analysis further indicates that the trend in the output power with varying damping ratio is dissimilar to that of the efficiency. In order to realize best performance, the harvester should be designed with respect to maximizing the magnitude of output power.
Physics of the multi-functionality of lanthanum ferrite ceramics
Authors: Bhargav K. K. , Ram S. , Majumder S. B.
Published: May 2014

In the present work, we have illustrated the physics of the multifunctional characteristics of nano-crystalline LaFeO3 powder prepared using auto-combustion synthesis. The synthesized powders were phase pure and crystallized into centro-symmetric Pnma space group. The temperature dependence of dielectric constant of pure LaFeO3 exhibits dielectric maxima similar to that observed in ferroelectric ceramics with non-centrosymmetric point group. The dielectric relaxation of LaFeO3 correlates well with small polaron conduction. The occurrence of polarization hysteresis in LaFeO3 (with centro-symmetric Pnma space group) is thought to be spin current induced type. The canting of the Fe3+ spins induce weak ferromagnetism in nano-crystalline LaFeO3. Room temperature saturation magnetization of pure LaFeO3 is reported to be 3.0 emu/g. Due to the presence of both ferromagnetic as well as polarization ordering, LaFeO3 behaves like a single phase multiferroic ceramics. The magneto-electric coupling in this system has been demonstrated through the magneto-dielectric measurements which yield about 0.8% dielectric tuning (at 10 kHz) with the application of 2 T magnetic field. As a typical application of the synthesized nano-crystalline LaFeO3 powder, we have studied its butane sensing characteristics. The efficient butane sensing characteristics have been correlated to their catalytic activity towards oxidation of butane. Through X-ray photoelectron spectroscopy analyses, we detect the surface adsorbed oxygen species on LaFeO3 surface. Surface adsorbed oxygen species play major role in their low temperature butane sensing. Finally, we have hypothesized that the desorbed H2O and O2 (originate from surface adsorbed hydroxyl and oxygen) initiate the catalytic oxidative dehydrogenation of n-butane resulting in weakening of the electrostatics of the gas molecules.
High and low frequency instabilities driven by counter-streaming electron beams in space plasmas
Authors: Mbuli L. N. , Maharaj S. K. , Bharuthram R.
Published: May 2014

A four-component plasma composed of a drifting (parallel to ambient magnetic field) population of warm electrons, drifting (anti-parallel to ambient magnetic field) cool electrons, stationary hot electrons, and thermal ions is studied in an attempt to further our understanding of the excitation mechanisms of broadband electrostatic noise (BEN) in the Earth's magnetospheric regions such as the magnetosheath, plasmasphere, and plasma sheet boundary layer (PSBL). Using kinetic theory, beam-driven electrostatic instabilities such as the ion-acoustic, electron-acoustic instabilities are found to be supported in our multi-component model. The dependence of the instability growth rates and real frequencies on various plasma parameters such as beam speed, number density, temperature, and temperature anisotropy of the counter-streaming (relative to ambient magnetic field) cool electron beam are investigated. It is found that the number density of the anti-field aligned cool electron beam and drift speed play a central role in determining which instability is excited. Using plasma parameters which are closely correlated with the measurements made by the Cluster satellites in the PSBL region, we find that the electron-acoustic and ion-acoustic instabilities could account for the generation of BEN in this region.
Source localization of brain activity using helium-free interferometer
Authors: Dammers Jürgen , Chocholacs Harald , Eich Eberhard , Boers Frank , Faley Michael , Dunin-Borkowski Rafal E. , Jon Shah N.
Published: May 2014

To detect extremely small magnetic fields generated by the human brain, currently all commercial magnetoencephalography (MEG) systems are equipped with low-temperature (low-Tc) superconducting quantum interference device (SQUID) sensors that use liquid helium for cooling. The limited and increasingly expensive supply of helium, which has seen dramatic price increases recently, has become a real problem for such systems and the situation shows no signs of abating. MEG research in the long run is now endangered. In this study, we report a MEG source localization utilizing a single, highly sensitive SQUID cooled with liquid nitrogen only. Our findings confirm that localization of neuromagnetic activity is indeed possible using high-Tc SQUIDs. We believe that our findings secure the future of this exquisitely sensitive technique and have major implications for brain research and the developments of cost-effective multi-channel, high-Tc SQUID-based MEG systems.
Laser wakefield acceleration of electrons with ionization injection in a pure N5+ plasma waveguide
Authors: Goers A. J. , Yoon S. J. , Elle J. A. , Hine G. A. , Milchberg H. M.
Published: May 2014

Ionization injection-assisted laser wakefield acceleration of electrons up to 120 MeV is demonstrated in a 1.5 mm long pure helium-like nitrogen plasma waveguide. The guiding structure stabilizes the high energy electron beam pointing and reduces the beam divergence. Our results are confirmed by 3D particle-in-cell simulations.
Low-temperature sintering for plastic dye-sensitized solar cells using conventional TiO2 paste containing organic binders
Authors: Zen Shungo , Ishibashi Yuta , Ono Ryo
Published: May 2014

Dye-sensitized solar cells (DSSCs) require sintering of TiO2 photoelectrodes at 450 °C to 550 °C. However, high-temperature sintering is unfavorable because it limits the use of materials that cannot withstand high temperatures. In previous papers, we proposed a surface treatment of TiO2 photoelectrodes to reduce the sintering temperature from 500 °C to 250 °C using a dielectric barrier discharge and ultraviolet light from a low-pressure mercury lamp. In this study, we improved the surface treatment of TiO2 photoelectrodes to further reduce the sintering temperature from 250 °C to 150 °C using a conventional TiO2 paste that contains organic binders. The sintering temperature of 150 °C is critical because it is the maximum tolerable temperature of plastic substrates. The improved surface treatment is applied to both glass and plastic substrate DSSCs. The energy conversion efficiency of glass and plastic substrate DSSCs sintered at 150 °C using our improved surface treatment are approximately 110% and 80%, respectively, of that of glass substrate DSSCs fabricated using the conventional method sintered at 500 °C.
Breakdown of ionic character of molecular alkali bromides in inner-valence photoionization
Authors: Karpenko A. , Iablonskyi D. , Urpelainen S. , Kettunen J. A. , Cao W. , Huttula M. , Aksela H.
Published: May 2014

The inner-valence region of alkali bromide XBr (X=Li, Na, K, Rb) vapours has been studied experimentally by means of synchrotron radiation excited photoelectron spectroscopy. Experimental spectra were analyzed by comparing them with available theoretical results and previous experiments. Ionic character of alkali bromides is seen to change in the inner-valence region with increasing atomic number of the alkali atom. A mechanism involving mixing between Br 4s and Rb 4p orbitals has been suggested to account for the fine structure observed in inner-valence ionization region of RbBr.
Direct integration of a supercapacitor into the backside of a silicon photovoltaic device
Authors: Westover Andrew S. , Share Keith , Carter Rachel , Cohn Adam P. , Oakes Landon , Pint Cary L.
Published: May 2014

We demonstrate a route to integrate active material for energy storage directly into a silicon photovoltaic (PV) device, and the synergistic operation of the PV and storage systems for load leveling. Porous silicon supercapacitors with 84% Coulombic efficiency are etched directly into the excess absorbing layer material in a commercially available polycrystalline silicon PV device and coupled with solid-state polymer electrolytes. Our work demonstrates the simple idea both that the PV device can charge the supercapacitor under an external load and that a constant current load can be maintained through periods of intermittent illumination, demonstrating the concept of an all-silicon integrated solar supercapacitor.