bluuebunny/crossref_metadata_2025 huggingface dataset:
Enhancement and extinction effects in surface-enhanced stimulated Raman spectroscopy
Authors: Chng B. X. K. , van Dijk T. , Bhargava R. , Carney P. S.
Published: March 2015

We address the optical physics of surface-enhanced stimulated Raman spectroscopy (SESRS) from the microscopic to macroscopic scales to provide experimental design criteria in colloidal-suspension SESRS.
Investigation on the conductivity-dependent performance in low voltage cathodoluminescence
Authors: Shang Chunyu , Zhao Jinxian , Wang Xiuqin , Xia Hongyang , Kang Hui
Published: March 2015

With the increase of applied current density in low voltage cathodoluminescence, the exciting power tends to saturate, causing the saturation of electron–hole generation rate in the phosphor layer.
Ion specific effects: decoupling ion–ion and ion–water interactions
Authors: Song Jinsuk , Kang Tae Hui , Kim Mahn Won , Han Songi
Published: March 2015

Ion-specific effects in aqueous solution, known as the Hofmeister effect, are prevalent in diverse systems. The objective of this paper is to explicitly demonstrate how complex ion–ion and ion–water interactions manifest themselves in the Hofmeister effect based on a series of recent experimental observations.
Adsorption of insoluble polysulfides Li2Sx (x = 1, 2) on Li2S surfaces
Authors: Liu Zhixiao , Hubble Dion , Balbuena Perla B. , Mukherjee Partha P.
Published: March 2015

The growth of Li2S film is predominated by direct Li2S deposition during the Li–S battery discharge process.
Conversion of saccharides into formic acid using hydrogen peroxide and a recyclable palladium(ii) catalyst in aqueous alkaline media at ambient temperatures
Authors: Zargari N. , Kim Y. , Jung K. W.
Published: March 2015

We have developed an effective method that converts a variety of mono- and disaccharides into formic acid predominantly.
Development of hybrid composites for automotive applications: effect of addition of SEBS on the morphology, mechanical, viscoelastic, crystallization and thermal degradation properties of PP/PS–xGnP composites
Authors: Parameswaranpillai Jyotishkumar , Joseph George , Shinu K. P. , Jose Seno , Salim Nisa V. , Hameed Nishar
Published: March 2015

The presence of SEBS and xGnP in PP/PS blend allows better stress transfer between the phases.
Recent developments in electrode materials for sodium-ion batteries
Authors: Wang Luyuan Paul , Yu Linghui , Wang Xin , Srinivasan Madhavi , Xu Zhichuan J.
Published: March 2015

The most recent developments on Na-ion battery electrode materials are introduced and reviewed in this article.
Transparent free-standing film of 1-D rutile/anatase TiO2 nanorod arrays by a one-step hydrothermal process
Authors: Kao Li Cheng , Lin Chin Jung , Dong Chung Li , Chen Chi Liang , Liou Sofia Ya Hsuan
Published: March 2015

A large-scale, transparent, and free-standing film of 1-D rutile/anatase TiO2 nanorod arrays can be fabricated by a one-step hydrothermal process.
A Br-substituted phenanthroimidazole derivative with aggregation induced emission from intermolecular halogen–hydrogen interactions
Authors: Zhang Ying , Wang Jun-Hao , Zheng Ji , Li Dan
Published: March 2015

A unique aggregation induced emission (AIE) active emitter based on a Br-substituted phenanthroimidazole derivative was reported.
A paper-based skin patch for the diagnostic screening of cystic fibrosis
Authors: Mu Xuan , Xin Xiaolei , Fan Chengyan , Li Xue , Tian Xinlun , Xu Kai-Feng , Zheng Zhi
Published: March 2015

A band-aid like paper-based skin patch for the quantitative and colorimetric detection of sweat anions that is valuable for the diagnostic screening of cystic fibrosis.
Frustrated Lewis pair-like reactions of nucleophilic palladium carbenes with B(C6F5)3
Authors: Cui Peng , Comanescu Cezar C. , Iluc Vlad M.
Published: March 2015

Nucleophilic palladium carbenes react with the strong Lewis acid B(C6F5)3via remote nucleophilic attack at the para-carbon of the supporting ligand or C–F activation of B(C6F5)3; these reactions indicate frustrated Lewis pair-like behaviour given the steric inaccessibility of the nucleophilic carbene center.
Reaction-diffusion degradation model for delayed erosion of cross-linked polyanhydride biomaterials
Authors: Domanskyi Sergii , Poetz Katie L. , Shipp Devon A. , Privman Vladimir
Published: March 2015

Delayed erosion of highly cross-linked polyanhydrides is attributable to the nonlinear dependence of the degradation rates on water concentration.
Solvent-dependent structure of molecular iodine probed by picosecond X-ray solution scattering
Authors: Kim Kyung Hwan , Ki Hosung , Lee Jae Hyuk , Park Sungjun , Kong Qingyu , Kim Jeongho , Kim Joonghan , Wulff Michael , Ihee Hyotcherl
Published: March 2015

Time-resolved X-ray liquidography reveals the molecular origin of the solvent-dependent bond length of iodine in solution.
Vanadyl calix[6]arene complexes: synthesis, structural studies and ethylene homo-(co-)polymerization capability
Authors: Redshaw Carl , Walton Mark , Michiue Kenji , Chao Yimin , Walton Alex , Elo Pertti , Sumerin Victor , Jiang Chengying , Elsegood Mark R. J.
Published: March 2015

Use of various combinations of [VOCl3], LiOt-Bu andp-tert-butylcalix[6]areneH6affords vanadyl complexes capable of ethylene homo-(co-)polymerization.
The establishment of preliminary safety threshold values for cyanobacteria based on periodic variations in different microcystin congeners in Lake Chaohu, China
Authors: Shang Lixia , Feng Muhua , Liu Feifei , Xu Xiangen , Ke Fan , Chen Xiangchao , Li Wenchao
Published: March 2015

It is necessary to establish periodic safety threshold values for cyanobacteria referring to the main MC congeners rather than MC-LR.
Facile synthesis of spirooxindole-pyrazolines and spirobenzofuranone-pyrazolines and their fungicidal activity
Authors: Yang Changjiang , Li Juanjuan , Zhou Rong , Chen Xiangyu , Gao Yunpeng , He Zhengjie
Published: March 2015

A new and facile synthetic method is developed for biologically important spirooxindole-pyrazolines and spirobenzofuranone-pyrazolines.
Core cross-linked polyphosphoester micelles with folate-targeted and acid-cleavable features for pH-triggered drug delivery
Authors: Hu Jian , He Jinlin , Cao Dongling , Zhang Mingzu , Ni Peihong
Published: March 2015

Novel folate-conjugated acid-cleavable core cross-linked polyphosphoester micelles have been prepared and used for pH and enzyme-triggered delivery of doxorubicin.
Synthesis of 1,5-regioregular polytriazoles by efficient NMe4OH-mediated azide–alkyne click polymerization
Authors: Liu Yong , Wang Jia , Huang Die , Zhang Jie , Guo Shang , Hu Ronrong , Zhao Zujin , Qin Anjun , Tang Ben Zhong
Published: March 2015

The efficient and regioselective NMe4OH-mediated aromatic azide and alkyne click polymerization to generate 1,5-regioregular polytriazoles was successfully established.
Control of Microcystis aeruginosa growth and associated microcystin cyanotoxin remediation by electron beam irradiation (EBI)
Authors: Liu Shuyu , Zhao Yueping , Ma Fang , Ma Liyan , O'shea Kevin , Zhao Cen , Hu Xiaohui , Wu Minghong
Published: March 2015

EBI treatment of microcystin in the cell and free in the solution. High dose of EBI leads to high removal percentage of MC in the cell and free in the solution. Correlation between Chl-a and MC concentration was studied under EBI.
Synthesis of ferrocene-containing six-membered cyclic ureas via α-ferrocenyl carbocations
Authors: Minić Aleksandra , Stevanović Dragana , Damljanović Ivan , Pejović Anka , Vukićević Mirjana , Bogdanović Goran A. , Radulović Niko S. , Vukićević Rastko D.
Published: March 2015

A convenient method for the synthesis of ferrocene-containing six membered cyclic ureas was developed.
Prevention of doxorubicin sorptive losses in drug delivery studies using polyethylene glycol
Authors: Curry Dennis , Scheller Hope , Lu Mingsheng , Mkandawire Martin , Servos Mark R. , Cui Shufen , Zhang Xu , Oakes Ken D.
Published: March 2015

Polyethylene glycol enhances the accuracy of drug delivery system evaluations by preventing sorptive losses of hydrophobic drugs to plastic reaction vessels.
Beckmann rearrangement reaction of cyclohexanone oxime in sub/supercritical water: byproduct and selectivity
Authors: Li Yang , Wang Kai , Qin Kang , Wang Tao
Published: March 2015

The byproduct acetamide was proposed for the Beckmann rearrangement reaction of cyclohexanone oxime in subcritical and supercritical water.
The structural and magnetic properties of the compound Tm5Ge4
Authors: Zou Junding , Yan Mi , Yao Jinlei
Published: March 2015

The structural and magnetic properties of the compound Tm5Ge4 have been studied in detail as functions of temperature and magnetic field.
Fabrication and evaluation of adhesion enhanced flexible carbon nanotube transparent conducting films
Authors: Wang Yan , Yang Hai-Jie , Geng Hong-Zhang , Zhang Ze-Chen , Ding Er-Xiong , Meng Yan , Luo Zhi-Jia , Wang Jing , Su Xiao-Mei , Da Shi-Xun
Published: March 2015

The addition of polyacrylic acid to SWCNT dispersion improved the film adhesion obviously without decreasing its electrical conductivity.
Conversion of non-adipogenic fibroblasts into adipocytes by a defined hormone mixture
Authors: Nie Tao , Hui Xiaoyan , Gao Xuefei , Nie Baoming , Mao Liufeng , Tang Xiaofeng , Yuan Ran , Li Kuai , Li Peng , Xu Aimin , Liu Pengtao , Ding Sheng , Han Weiping , Cooper Garth J. S. , Wu Donghai
Published: March 2015

Obesity is accompanied by an increase in the size and the number of adipocytes. As adipocytes are thought to differentiate from pre-adipocytes, we postulate that non-adipogenic fibroblasts contribute to adipocyte formation under certain conditions such as obesity. We report for the first time that NIH-3T3 fibroblasts, which are generally considered to be non-adipogenic, can be converted into mature adipocytes by treatment with a defined hormone mixture comprising EGF (epidermal growth factor), HGF (hepatocyte growth factor), Dex (dexamethasone) and insulin. Furthermore, NIH-3T3 cells transplanted into obese immunodeficient NOD/SCID (non-obese diabetic/severe combined immunodeficient) mice formed adipocytes in vivo. Interestingly, the mixture elicited conversion of NIH-3T3 cells directly into adipocytes without a preceding pre-adipocyte stage. Functional analysis revealed that each component of the mixture was necessary for the induction of adipogenesis, including Dex which inhibited the cell proliferation stimulated by EGF. Upon profiling the signalling pathways employed by EGF and HGF, we found STAT5 (signal transducer and activator of transcription 5) signalling to be activated, predominantly at the levels of both transcription and post-translational modification. Inhibition of the STAT5 pathway, either by genetic knockdown or a specific pharmacological agent, blocked adipogenesis in NIH-3T3 cells. Taken together, these data not only establish a newly recognized grouping of factors that can induce trans-differentiation of non-adipogenic fibroblasts into adipocytes, but also give us a greater understanding of obesity.
A novel chemical footprinting approach identifies critical lysine residues involved in the binding of receptor-associated protein to cluster II of LDL receptor-related protein
Authors: Bloem Esther , Ebberink Eduard H.T.M. , van den Biggelaar Maartje , van der Zwaan Carmen , Mertens Koen , Meijer Alexander B.
Published: March 2015

Tandem mass tags (TMTs) were utilized in a novel chemical footprinting approach to identify lysine residues that mediate the interaction of receptor-associated protein (RAP) with cluster II of LDL (low-density lipoprotein) receptor (LDLR)-related protein (LRP). The isolated RAP D3 domain was modified with TMT-126 and the D3 domain–cluster II complex with TMT-127. Nano-LC–MS analysis revealed reduced modification with TMT-127 of peptides including Lys256, Lys270 and Lys305-Lys306 suggesting that these residues contribute to cluster II binding. This agrees with previous findings that Lys256 and Lys270 are critical for binding cluster II sub-domains [Fisher, Beglova and Blacklow (2006) Mol. Cell 22, 277–283]. Cluster II-binding studies utilizing D3 domain variants K256A, K305A and K306A now showed that Lys306 contributes to cluster II binding as well. For full-length RAP, we observed that peptides including Lys60, Lys191, Lys256, Lys270 and Lys305-Lys306 exhibited reduced modification with TMT in the RAP–cluster II complex. Notably, Lys60 has previously been implicated to mediate D1 domain interaction with cluster II. Our results suggest that also Lys191 of the D2 domain contributes to cluster II binding. Binding studies employing the RAP variants K191A, K256A, K305A and K306A, however, revealed a modest reduction in cluster II binding for the K256A variant only. This suggests that the other lysine residues can compensate for the absence of a single lysine residue for effective complex assembly. Collectively, novel insight has been obtained into the contribution of lysine residues of RAP to cluster II binding. In addition, we propose that TMTs can be utilized to identify lysine residues critical for protein complex formation.
Role and structural characterization of plant aldehyde dehydrogenases from family 2 and family 7
Authors: Končitíková Radka , Vigouroux Armelle , Kopečná Martina , Andree Tomáš , Bartoš Jan , Šebela Marek , Moréra Solange , Kopečný David
Published: March 2015

Aldehyde dehydrogenases (ALDHs) are responsible for oxidation of biogenic aldehyde intermediates as well as for cell detoxification of aldehydes generated during lipid peroxidation. So far, 13 ALDH families have been described in plants. In the present study, we provide a detailed biochemical characterization of plant ALDH2 and ALDH7 families by analysing maize and pea ALDH7 (ZmALDH7 and PsALDH7) and four maize cytosolic ALDH(cALDH)2 isoforms RF2C, RF2D, RF2E and RF2F [the first maize ALDH2 was discovered as a fertility restorer (RF2A)]. We report the crystal structures of ZmALDH7, RF2C and RF2F at high resolution. The ZmALDH7 structure shows that the three conserved residues Glu120, Arg300 and Thr302 in the ALDH7 family are located in the substrate-binding site and are specific to this family. Our kinetic analysis demonstrates that α-aminoadipic semialdehyde, a lysine catabolism intermediate, is the preferred substrate for plant ALDH7. In contrast, aromatic aldehydes including benzaldehyde, anisaldehyde, cinnamaldehyde, coniferaldehyde and sinapaldehyde are the best substrates for cALDH2. In line with these results, the crystal structures of RF2C and RF2F reveal that their substrate-binding sites are similar and are formed by an aromatic cluster mainly composed of phenylalanine residues and several nonpolar residues. Gene expression studies indicate that the RF2C gene, which is strongly expressed in all organs, appears essential, suggesting that the crucial role of the enzyme would certainly be linked to the cell wall formation using aldehydes from phenylpropanoid pathway as substrates. Finally, plant ALDH7 may significantly contribute to osmoprotection because it oxidizes several aminoaldehydes leading to products known as osmolytes.
Implementation of high‐speed–low‐power adaptive finite impulse response filter with novel architecture
Authors: Jaiswal Manish , Sharma Sandeep , Sharma Anuj
Published: March 2015

An energy efficient high‐speed adaptive finite impulse response filter with novel architecture is developed. Synthesis results along with novel architecture on different complementary metal–oxide semiconductor (CMOS) families are presented. Analysis is performed using Artix‐7, Spartan‐6 and Virtex‐4 for most popular adaptive least mean square filter for different orders such as N = 8, 16, 32. The presented work is done using MATLAB (2013b) and Xilinx (14.2). From the synthesis results, it can be found that CMOS (28 nm) achieves the lowest power and critical path delay compared to others, and thus proves its efficiency in terms of energy. Different parameters are considered such as look up tables and input–output blocks, along with their optimised results.
Improving resistance uniformity and endurance of resistive switching memory by accurately controlling the stress time of pulse program operation
Authors: Wang Guoming , Long Shibing , Yu Zhaoan , Zhang Meiyun , Ye Tianchun , Li Yang , Xu Dinglin , Lv Hangbing , Liu Qi , Wang Ming , Xu Xiaoxin , Liu Hongtao , Yang Baohe , Suñé Jordi , Liu Ming
Published: March 2015

In this letter, the impact of stress time of pulse program operation on the resistance uniformity and endurance of resistive random access memory (RRAM) is investigated. A width-adjusting pulse operation (WAPO) method which can accurately setup and measure switching time is proposed for improving the uniformity and endurance of RRAM. Different from the traditional single pulse operation (TSPO) method in which only one wide pulse is applied in each switching cycle, WAPO method utilizes a series of pulses with the width increased gradually until a set or reset switching process is completely finished and no excessive stress is produced. Our program/erase (P/E) method can exactly control the switching time and the final resistance and can significantly improve the uniformity, stability, and endurance of RRAM device. Improving resistance uniformity by WAPO compared with TSPO method is explained through the interdependence between resistance state and switching time. The endurance improvement by WAPO operation stems from the effective avoidance of the overstress-induced progressive-breakdown and even hard-breakdown to the conductive soft-breakdown path.
Quantum confinement in self-assembled two-dimensional nanoporous honeycomb networks at close-packed metal surfaces
Authors: Kepčija N. , Huang T.-J. , Klappenberger F. , Barth J. V.
Published: March 2015

Quantum confinement of a two-dimensional electron gas by supramolecular nanoporous networks is investigated using the boundary elements method based on Green’s functions for finite geometries and electron plane wave expansion for periodic systems. The “particle in a box” picture was analyzed for cases with selected symmetries that model previously reported architectures constructed from organic and metal-organic scattering centers confining surface state electrons of Ag(111) and Cu(111). First, by analyzing a series of cases with systematically defined parameters (scattering geometry, potentials, and effective broadening), we demonstrate how the scattering processes affect the properties of the confined electrons. For the features of the local density of states reported by scanning tunneling spectroscopy (STS), we disentangle the contributions of lifetime broadening and splitting of quantum well states due to coupling of neighboring quantum dots. For each system, we analyze the local electron density distribution and relate it to the corresponding band structure as calculated within the plane-wave expansion framework. Then, we address two experimental investigations, where in one case only STS data and in the other case mainly angle-resolved photoemission spectroscopy (ARPES) data were reported. In both cases, the experimental findings can be successfully simulated. Furthermore, the missing information can be complemented because our approach allows to correlate the information obtained by STS with that of ARPES. The combined analysis of several observations suggests that the scattering potentials created by the network originate primarily from the adsorbate-induced changes of the local surface dipole barrier.
Exact milestoning
Authors: Bello-Rivas Juan M. , Elber Ron
Published: March 2015

A new theory and an exact computer algorithm for calculating kinetics and thermodynamic properties of a particle system are described. The algorithm avoids trapping in metastable states, which are typical challenges for Molecular Dynamics (MD) simulations on rough energy landscapes. It is based on the division of the full space into Voronoi cells. Prior knowledge or coarse sampling of space points provides the centers of the Voronoi cells. Short time trajectories are computed between the boundaries of the cells that we call milestones and are used to determine fluxes at the milestones. The flux function, an essential component of the new theory, provides a complete description of the statistical mechanics of the system at the resolution of the milestones. We illustrate the accuracy and efficiency of the exact Milestoning approach by comparing numerical results obtained on a model system using exact Milestoning with the results of long trajectories and with a solution of the corresponding Fokker-Planck equation. The theory uses an equation that resembles the approximate Milestoning method that was introduced in 2004 [A. K. Faradjian and R. Elber, J. Chem. Phys. 120(23), 10880-10889 (2004)]. However, the current formulation is exact and is still significantly more efficient than straightforward MD simulations on the system studied.
Conduction of molecular electronic devices: Qualitative insights through atom-atom polarizabilities
Authors: Stuyver T. , Fias S. , De Proft F. , Fowler P. W. , Geerlings P.
Published: March 2015

The atom-atom polarizability and the transmission probability at the Fermi level, as obtained through the source-and-sink-potential method for every possible configuration of contacts simultaneously, are compared for polycyclic aromatic compounds. This comparison leads to the conjecture that a positive atom-atom polarizability is a necessary condition for transmission to take place in alternant hydrocarbons without non-bonding orbitals and that the relative transmission probability for different configurations of the contacts can be predicted by analyzing the corresponding atom-atom polarizability. A theoretical link between the two considered properties is derived, leading to a mathematical explanation for the observed trends for transmission based on the atom-atom polarizability.
Influence of leaching on surface composition, microstructure, and valence band of single grain icosahedral Al-Cu-Fe quasicrystal
Authors: Lowe M. , Yadav T. P. , Fournée V. , Ledieu J. , McGrath R. , Sharma H. R.
Published: March 2015

The use of quasicrystals as precursors to catalysts for the steam reforming of methanol is potentially one of the most important applications of these new materials. To develop application as a technology requires a detailed understanding of the microscopic behavior of the catalyst. Here, we report the effect of leaching treatments on the surface microstructure, chemical composition, and valence band of the icosahedral (i-) Al-Cu-Fe quasicrystal in an attempt to prepare a model catalyst. The high symmetry fivefold surface of a single grain i-Al-Cu-Fe quasicrystal was leached with NaOH solution for varying times, and the resulting surface was characterized by x-ray photoelectron spectroscopy (XPS), ultraviolet photoelectron spectroscopy (UPS), scanning electron microscopy (SEM), and atomic force microscopy (AFM). The leaching treatments preferentially remove Al producing a capping layer consisting of Fe and Cu oxides. The subsurface layer contains elemental Fe and Cu in addition to the oxides. The quasicrystalline bulk structure beneath remains unchanged. The subsurface gradually becomes Fe3O4 rich with increasing leaching time. The surface after leaching exhibits micron sized dodecahedral cavities due to preferential leaching along the fivefold axis. Nanoparticles of the transition metals and their oxides are precipitated on the surface after leaching. The size of the nanoparticles is estimated by high resolution transmission microscopy to be 5-20 nm, which is in agreement with the AFM results. Selected area electron diffraction (SAED) confirms the crystalline nature of the nanoparticles. SAED further reveals the formation of an interface between the high atomic density lattice planes of nanoparticles and the quasicrystal. These results provide an important insight into the preparation of model catalysts of nanoparticles for steam reforming of methanol.
Unusual solvation through both p-orbital lobes of a carbene carbon
Authors: Hadad C. Z. , Jenkins Samantha , Flórez Elizabeth
Published: March 2015

As a result of a configurational space search done to explain the experimental evidence of transient specific solvation of singlet fluorocarbene amide with tetrahydrofuran, we found that the most stable structures consist in a group in which each oxygen of two tetrahydrofuran molecules act as electron donor to its respective empty p-orbital lobe of the carbene carbon atom, located at each side of the carbene molecular plane. This kind of species, which to our knowledge has not been reported before, explains very well the particular experimental characteristics observed for the transient solvation of this system. We postulate that the simultaneous interaction to both p-orbital lobes seems to confer a special stability to the solvation complexes, because this situation moves away the systems from the proximity of the corresponding transition states for the ylide products. Additionally, we present an analysis of other solvation complexes and a study of the nature of the involved interactions.
Geometrical influence on vortex shedding in turbulent axisymmetric wakes
Authors: Nedić J. , Supponen O. , Ganapathisubramani B. , Vassilicos J. C.
Published: March 2015

We investigate the structures generated by the vortex shedding mechanism in turbulent axisymmetric wakes of non-axisymmetric plates, including a square plate and a series of fractal plates, and compare the results to a disk. For a given characteristic length ℓ, all plates have the same frontal area A, since ℓ = A0.5, but the length of the perimeter and the irregularity of the perimeter were varied in a fractal manner thus allowing us to investigate the effect of boundary conditions. Measurements were taken over a large range of downstream and radial distances in order to obtain a more robust measure for the vortex shedding energy. It was found that the fractal plates are able to reduce the vortex shedding energy by as much as 60% compared to the disk and square plates. It was also found that the frequency at which the vortex shedding structures are generated and the manner in which they organise themselves in the wake are independent of the boundary conditions of the wake generator. The results suggest that the main function of the multi-scale segments around the perimeter of the plates is to re-distribute the energy to a broader range of scales in the flow, which could explain the previously observed increase in drag coefficient for the fractal edged plates.
Communication: On the competition between adiabatic and nonadiabatic dynamics in vibrationally mediated ammonia photodissociation in its A band
Authors: Xie Changjian , Zhu Xiaolei , Ma Jianyi , Yarkony David R. , Xie Daiqian , Guo Hua
Published: March 2015

Non-adiabatic processes play an important role in photochemistry, but the mechanism for conversion of electronic energy to chemical energy is still poorly understood. To explore the possibility of vibrational control of non-adiabatic dynamics in a prototypical photoreaction, namely, the A-band photodissociation of NH3(X̃1A1), full-dimensional state-to-state quantum dynamics of symmetric or antisymmetric stretch excited NH3(X̃1A1) is investigated on recently developed coupled diabatic potential energy surfaces. The experimentally observed H atom kinetic energy distributions are reproduced. However, contrary to previous inferences, the NH2(Ã2A1)/NH2(X̃2B1) branching ratio is found to be small regardless of the initial preparation of NH3(X̃1A1), while the internal state distribution of the preeminent fragment, NH2(X̃2B1), is found to depend strongly on the initial vibrational excitation of NH3(X̃1A1). The slow H atoms in photodissociation mediated by the antisymmetric stretch fundamental state are due to energy sequestered in the internally excited NH2(X̃2B1) fragment, rather than in NH2(Ã2A1) as previously proposed. The high internal excitation of the NH2(X̃2B1) fragment is attributed to the torques exerted on the molecule as it passes through the conical intersection seam to the ground electronic state of NH3. Thus in this system, contrary to previous assertions, the control of electronic state branching by selective excitation of ground state vibrational modes is concluded to be ineffective. The juxtaposition of precise quantum mechanical results with complementary results based on quasi-classical surface hopping trajectories provides significant insights into the non-adiabatic process.
Magnetic particle detection in unshielded environment using orthogonal fluxgate gradiometer
Authors: Elrefai Ahmed L. , Sasada Ichiro
Published: March 2015

A new detection system for magnetic particles, which can operate in an unshielded environment, is developed using a fundamental mode orthogonal fluxgate gradiometer. The proposed detection system offers the advantages of cost, size, and weight reduction as compared to contamination detection systems using superconducting quantum interference device sensor. The detection system can be used to detect metallic contamination in foods or lithium ion battery production lines. The system has been investigated numerically to optimize various design parameters of the system. Experimental setup has been developed to evaluate some of the numerically predicted results. Steel balls were successfully detected down to the diameter of 50 μm.
Origin of ‘in-plane’ and ‘out-of-plane’ magnetic anisotropies in as-deposited and annealed CoFeB ferromagnetic thin films
Authors: Swamy G. Venkat , Rakshit R. K. , Pant R. P. , Basheed G. A.
Published: March 2015

A detailed comparative Ferromagnetic resonance study of pulsed laser deposited Co40Fe40B20 thin films, before and after annealing, was under taken. The dependence of resonance field (Hres) and peak-to-peak linewidth (ΔHpp) on film thickness, annealing temperature, and magnetic field orientation is examined. ‘In-plane’ (IP) and ‘out-of-plane’ (OP) angular dependence of the resonance fields, (IP:Hres(ψ); OP:Hres(α)), were measured at T = 150 and 295 K for the as deposited (as-) to annealed (an-) thin film samples to determine IP (HK∥) and OP (HK⊥) uniaxial anisotropy fields. Variation of Hres(ψ) and Hres(α) on sample geometry demonstrate that the uniaxial magnetic anisotropy is present in as- and an-thin films of Co40Fe40B20. The effective magnetic anisotropy (Kueff) increases after nanocrystallization in CoFeB films indicates that the exchange interactions are unable to average out the local-magnetocrystalline anisotropy of the nanocrystalline grains and thereby lead to magnetic hardening in the early stages of crystallization.
Laser frequency stabilization using bichromatic crossover spectroscopy
Authors: Jeong Taek , Seb Moon Han
Published: March 2015

We propose a Doppler-free spectroscopic method named bichromatic crossover spectroscopy (BCS), which we then use for the frequency stabilization of an off-resonant frequency that does not correspond to an atomic transition. The observed BCS in the 5S1/2 → 5P1/2 transition of 87Rb is related to the hyperfine structure of the conventional saturated absorption spectrum of this transition. Furthermore, the Doppler-free BCS is numerically calculated by considering all of the degenerate magnetic sublevels of the 5S1/2 → 5P1/2 transition in an atomic vapor cell, and is found to be in good agreement with the experimental results. Finally, we successfully achieve modulation-free off-resonant locking at the center frequency between the two 5S1/2(F = 1 and 2) → 5P1/2(F′ = 1) transitions using a polarization rotation of the BCS. The laser frequency stability was estimated to be the Allan variance of 2.1 × 10−10 at 1 s.
Ferroelectric switching of poly(vinylidene difluoride-trifluoroethylene) in metal-ferroelectric-semiconductor non-volatile memories with an amorphous oxide semiconductor
Authors: Gelinck G. H. , van Breemen A. J. J. M. , Cobb B.
Published: March 2015

Ferroelectric polarization switching of poly(vinylidene difluoride-trifluoroethylene) is investigated in different thin-film device structures, ranging from simple capacitors to dual-gate thin-film transistors (TFT). Indium gallium zinc oxide, a high mobility amorphous oxide material, is used as semiconductor. We find that the ferroelectric can be polarized in both directions in the metal-ferroelectric-semiconductor (MFS) structure and in the dual-gate TFT under certain biasing conditions, but not in the single-gate thin-film transistors. These results disprove the common belief that MFS structures serve as a good model system for ferroelectric polarization switching in thin-film transistors.
Optical-resolution photoacoustic imaging through thick tissue with a thin capillary as a dual optical-in acoustic-out waveguide
Authors: Simandoux Olivier , Stasio Nicolino , Gateau Jérome , Huignard Jean-Pierre , Moser Christophe , Psaltis Demetri , Bossy Emmanuel
Published: March 2015

We demonstrate the ability to guide high-frequency photoacoustic waves through thick tissue with a water-filled silica-capillary (150 μm inner diameter and 30 mm long). An optical-resolution photoacoustic image of a 30 μm diameter absorbing nylon thread was obtained by guiding the acoustic waves in the capillary through a 3 cm thick fat layer. The transmission loss through the capillary was about −20 dB, much lower than the −120 dB acoustic attenuation through the fat layer. The overwhelming acoustic attenuation of high-frequency acoustic waves by biological tissue can therefore be avoided by the use of a small footprint capillary acoustic waveguide for remote detection. We finally demonstrate that the capillary can be used as a dual optical-in acoustic-out waveguide, paving the way for the development of minimally invasive optical-resolution photoacoustic endoscopes free of any acoustic or optical elements at their imaging tip.
Terahertz probes of magnetic field induced spin reorientation in YFeO3 single crystal
Authors: Lin Xian , Jiang Junjie , Jin Zuanming , Wang Dongyang , Tian Zhen , Han Jiaguang , Cheng Zhenxiang , Ma Guohong
Published: March 2015

Using the terahertz time-domain spectroscopy, we demonstrate the spin reorientation of a canted antiferromagnetic YFeO3 single crystal, by evaluating the temperature and magnetic field dependence of resonant frequency and amplitude for the quasi-ferromagnetic (FM) and quasi-antiferromagnetic modes (AFM), a deeper insight into the dynamics of spin reorientation in rare-earth orthoferrites is established. Due to the absence of 4f-electrons in Y ion, the spin reorientation of Fe sublattices can only be induced by the applied magnetic field, rather than temperature. In agreement with the theoretical predication, the frequency of FM mode decreases with magnetic field. In addition, an obvious step of spin reorientation phase transition occurs with a relatively large applied magnetic field of 4 T. By comparison with the family members of RFeO3 (R = Y3+ or rare-earth ions), our results suggest that the chosen of R would tailor the dynamical rotation properties of Fe ions, leading to the designable spin switching in the orthoferrite antiferromagnetic systems.
A robust soliton ratchet using combined antiferromagnetic and ferromagnetic interlayer couplings
Authors: Mansell R. , Lavrijsen R. , Fernández-Pacheco A. , Petit D. C. M. C. , Lee J. H. , Koopmans B. , Swagten H. J. M. , Cowburn R. P.
Published: March 2015

A sharp magnetic soliton can be created and propagated in a vertical ratchet structure based on magnetic layers with out-of-plane anisotropy using a combination of antiferromagnetic and ferromagnetic interlayer couplings. This allows the use of identical magnetic layers in the stack, which simplifies the implementation of the ratchet compared to schemes which use alternating layer thicknesses. The ratchet behavior is analyzed using an Ising-macrospin approximation and conditions are derived for the propagation of a soliton, which is demonstrated experimentally. Values extracted from the experimental data for the coercivities and interlayer couplings show significant variation, which demonstrates the robustness of the soliton propagation.
Big data in reciprocal space: Sliding fast Fourier transforms for determining periodicity
Authors: Vasudevan Rama K. , Belianinov Alex , Gianfrancesco Anthony G. , Baddorf Arthur P. , Tselev Alexander , Kalinin Sergei V. , Jesse S.
Published: March 2015

Significant advances in atomically resolved imaging of crystals and surfaces have occurred in the last decade allowing unprecedented insight into local crystal structures and periodicity. Yet, the analysis of the long-range periodicity from the local imaging data, critical to correlation of functional properties and chemistry to the local crystallography, remains a challenge. Here, we introduce a Sliding Fast Fourier Transform (FFT) filter to analyze atomically resolved images of in-situ grown La5/8Ca3/8MnO3 (LCMO) films. We demonstrate the ability of sliding FFT algorithm to differentiate two sub-lattices, resulting from a mixed-terminated surface. Principal Component Analysis and Independent Component Analysis of the Sliding FFT dataset reveal the distinct changes in crystallography, step edges, and boundaries between the multiple sub-lattices. The implications for the LCMO system are discussed. The method is universal for images with any periodicity, and is especially amenable to atomically resolved probe and electron-microscopy data for rapid identification of the sub-lattices present.
Photoluminescence transient study of surface defects in ZnO nanorods grown by chemical bath deposition
Authors: Barbagiovanni E. G. , Strano V. , Franzò G. , Crupi I. , Mirabella S.
Published: March 2015

Two deep level defects (2.25 and 2.03 eV) associated with oxygen vacancies (Vo) were identified in ZnO nanorods (NRs) grown by low cost chemical bath deposition. A transient behaviour in the photoluminescence (PL) intensity of the two Vo states was found to be sensitive to the ambient environment and to NR post-growth treatment. The largest transient was found in samples dried on a hot plate with a PL intensity decay time, in air only, of 23 and 80 s for the 2.25 and 2.03 eV peaks, respectively. Resistance measurements under UV exposure exhibited a transient behaviour in full agreement with the PL transient, indicating a clear role of atmospheric O2 on the surface defect states. A model for surface defect transient behaviour due to band bending with respect to the Fermi level is proposed. The results have implications for a variety of sensing and photovoltaic applications of ZnO NRs.
Particle in cell simulation of a radiofrequency plasma jet expanding in vacuum
Authors: Charles C. , Hawkins R. , Boswell R. W.
Published: March 2015

The effect of a pressure gradient (∼133 Pa–0.133 Pa) on electron and ion energy distributions in a radiofrequency (rf at 13.56 MHz) argon plasma jet is studied using a 1D-3v Particle In Cell (PIC) simulation. The PIC domain is three times that of the 0.018 m long plasma cavity and the total simulation time is 1 ms. Ion heating and acceleration up to a drift velocity about 2000 m s−1 are measured along the jet's main expansion axis. Elastic and charge exchange ion-neutral collisions histograms computed at equilibrium during 0.74 ms show that charge exchange collisions act as the main neutral heating mechanism.
Highly efficient ultrathin-film amorphous silicon solar cells on top of imprinted periodic nanodot arrays
Authors: Yan Wensheng , Tao Zhikuo , Ong Thiam Min Brian , Gu Min
Published: March 2015

The addressing of the light absorption and conversion efficiency is critical to the ultrathin-film hydrogenated amorphous silicon (a-Si:H) solar cells. We systematically investigate ultrathin a-Si:H solar cells with a 100 nm absorber on top of imprinted hexagonal nanodot arrays. Experimental evidences are demonstrated for not only notable silver nanodot arrays but also lower-cost ITO and Al:ZnO nanodot arrays. The measured external quantum efficiency is explained by the simulation results. The Jsc values are 12.1, 13.0, and 14.3 mA/cm2 and efficiencies are 6.6%, 7.5%, and 8.3% for ITO, Al:ZnO, and silver nanodot arrays, respectively. Simulated optical absorption distribution shows high light trapping within amorphous silicon layer.
Postcolonial Perspectives on Global Production Networks: Insights from Flower Valley in South Africa
Authors: Hughes Alex , McEwan Cheryl , Bek David
Published: March 2015

This paper proposes dialogue between postcolonial theory and the analytical frameworks of global value chains (GVCs) and global production networks (GPNs). It does so in order to open up more culturally sensitive accounts of global supply networks and exporting localities than those provided by prevailing political-economic approaches. Particular focus is placed on Zein-Elabdin's postcolonial notion of economic hybridity to advance understanding of the institutional contexts shaping production networks. The value of applying this concept to GVC/GPN studies is illustrated in the case of a sustainable wildflower harvesting supply network in South Africa's Western Cape, which supplies ethically promoted bouquets to domestic and European markets. Transnational cultural politics, including those associated with colonial encounters, are shown to shape the hybrid institutional context of this production network. It is suggested that such a perspective on institutional hybridity offers just one fruitful conversation between postcolonial approaches and GVC/GPN frameworks.
Re-Representing the City: Waste and Public Space in Buenos Aires, Argentina in the Late 2000s
Authors: Parizeau Kate
Published: March 2015

This paper investigates a moment of shift in urban neoliberal governance strategies under the purview of a new municipal Chief of Government of Buenos Aires at the end of the 2000s: the introduction of a regime of public space that has had implications for the waste management sector (and particularly informal recyclers or cartoneros). I document government attempts to re-represent the city as a modern, hygienic centre that is receptive to investment and tourism, drawing on discursive framings of public space that seek to redefine legitimate users and uses of the city. Such framings are exclusionary of cartoneros and other marginalized urbanites. As with most forms of actually existing neoliberalism, this regime is contradictory and unstable, both containing and provoking challenges to its coherence. This case study of ‘actually existing neoliberalism’ in Buenos Aires encourages analytical focus on moments of shift and renewal in urban processes of neoliberalization. In this case the shift marked by the introduction of the regime of public space reveals the priorities and agendas of urban elites as championed by municipal governments, makes visible the paradoxes and contradictions inherent to neoliberal urbanisms, and also exposes openings for resistance, opposition, and renegotiation of urban neoliberal agendas (including protest, discursive reframings of the city and its uses, and the forging of indeterminate alliances).
Mobilizing Risk: Explaining Policy Transfer in Food and Occupational Safety Regulation in the UK
Authors: Demeritt David , Rothstein Henry , Beaussier Anne-Laure , Howard Michael
Published: March 2015

Using comparative methods of policy analysis, this paper explores the institutional factors shaping the transfer and adaptation of risk-based approaches to regulation within and between the regimes for occupational health and safety (OHS) and food safety in the UK. Over the past two decades successive governments have enthusiastically promoted risk as a key concept for regulatory reform and ‘better regulation’. Rather than trying to prevent all possible harms, ‘risk-based’ approaches promise to make regulation more proportionate and effective by using various risk-based metrics and policy instruments to focus regulatory standard-setting and enforcement activity on the highest priority risks, as determined through formal assessments of their probability and consequences. But despite facing similar external pressures and sharing many historical and structural features as OHS, food safety regulation has proven much less receptive to risk-based reforms of its organizing principles and practices. To explain that anomaly, we consider a range of explanations highlighted in the policy transfer and mobilities literatures. We find that coercive drivers for the adoption of risk, in the form of top-down political pressure for deregulation or hard EU mandates, are much less influential than voluntary ones, which reflect both normative (ie, shared commitments to proportionality, resource prioritization, and blame deflection) and mimetic (ie, imitation of private sector corporate governance models) isomorphism. We conclude with wider reflections about the significance of our cases for policy transfer and mobilities research and for the limits to risk as a universal principle for organizing, and accounting for, governance activity.
Pigeons trade efficiency for stability in response to level of challenge during confined flight
Authors: Williams C. David , Biewener Andrew A.
Published: March 2015

Significance

The real world is a cluttered environment and animals traversing it are faced with innumerable obstacles in their normal locomotion. During normal flight, birds have to avoid hitting trees, lampposts, and other members of flocks. To investigate flight strategies used in these circumstances, we presented pigeons with a simplified challenge, a series of vertical gaps with variable spacings. The pigeons used two discrete postures. One posture granted them greater flight efficiency but was more disrupted when they collided with obstacles, and was used for traversing larger gaps. An alternate flight posture was less efficient but more stable when slight collisions occurred, and was used for traversing smaller gaps. To our knowledge, this is the first time we have seen flight strategies tuned during use in cluttered environments.
KCC2 activity is critical in limiting the onset and severity of status epilepticus
Authors: Silayeva Liliya , Deeb Tarek Z. , Hines Rochelle M. , Kelley Matt R. , Munoz Michaelanne B. , Lee Henry H. C. , Brandon Nicholas J. , Dunlop John , Maguire Jaime , Davies Paul A. , Moss Stephen J.
Published: March 2015

Significance

Status epilepticus (SE) is defined as a state of continuous unremitting seizures that often exhibits underlying deficits in neuronal inhibition mediated by GABA
A
receptors. The efficacy of neuronal inhibition is critically dependent on the activity of the K
+
/Cl
–
cotransporter KCC2, which allows neurons to maintain low intracellular Cl
–
levels. KCC2 activity is enhanced by phosphorylation of residue serine 940, and here we show that SE leads to rapid dephosphorylation of this key regulatory residue. Moreover, we demonstrate that deficits in S940 phosphorylation directly contribute to the onset and severity of SE. Collectively, our results suggest that deficits in KCC2 activity directly contribute to the pathophysiology of SE.
Proteome-wide analysis of mutant p53 targets in breast cancer identifies new levels of gain-of-function that influence PARP, PCNA, and MCM4
Authors: Polotskaia Alla , Xiao Gu , Reynoso Katherine , Martin Che , Qiu Wei-Gang , Hendrickson Ronald C. , Bargonetti Jill
Published: March 2015

Significance

Mutant p53 (mtp53) is a driver oncogene of breast cancer. Here, for the first time, to our knowledge, using an inducible endogenous knockdown system, we explore the mtp53 driven proteome. We report this key data set that highlights mtp53-driven proteome diversity at the level of protein localization, as well as changes in protein levels without corresponding changes in transcription. We validated two protein pathways that include increased chromatin association of poly(ADP ribose) polymerase 1, and the increase of nuclear replication proteins minichromosome maintenance 4 and proliferating cell nuclear antigen. The addition of mtp53 proteomic targets to the previously identified transcriptional targets suggests that effective treatment of mtp53-driven breast cancers may be facilitated by new combination protocols blocking proteins of the metabolic pathways of cholesterol biosynthesis, DNA replication, and DNA repair.