bluuebunny/crossref_metadata_2025 huggingface dataset:
Elimination of strength degrading effects caused by surface microdefect: A prevention achieved by silicon nanotexturing to avoid catastrophic brittle fracture
Authors: Kashyap Kunal , Kumar Amarendra , Huang Chuan-Torng , Lin Yu-Yun , Hou Max T. , Andrew Yeh J.
Published: June 2015

The unavoidable occurrence of microdefects in silicon wafers increase the probability of catastrophic fracture of silicon-based devices, thus highlighting the need for a strengthening mechanism to minimize fractures resulting from defects. In this study, a novel mechanism for manufacturing silicon wafers was engineered based on nanoscale reinforcement through surface nanotexturing. Because of nanotexturing, different defect depths synthetically emulated as V-notches, demonstrated a bending strength enhancement by factors of 2.5, 3.2 and 6 for 2-, 7- and 14-μm-deep V-notches, respectively. A very large increase in the number of fragments observed during silicon fracturing was also indicative of the strengthening effect. Nanotextures surrounding the V-notch reduced the stress concentration factor at the notch tip and saturated as the nanotexture depth approached 1.5 times the V-notch depth. The stress reduction at the V-notch tip measured by micro-Raman spectroscopy revealed that nanotextures reduced the effective depth of the defect. Therefore, the nanotextured samples were able to sustain a larger fracture force. The enhancement in Weibull modulus, along with an increase in bending strength in the nanotextured samples compared to polished single-crystal silicon samples, demonstrated the reliability of the strengthening method. These results suggest that this method may be suitable for industrial implementation.
Structural ensembles reveal intrinsic disorder for the multi-stimuli responsive bio-mimetic protein Rec1-resilin
Authors: Balu Rajkamal , Knott Robert , Cowieson Nathan P. , Elvin Christopher M. , Hill Anita J. , Choudhury Namita R. , Dutta Naba K.
Published: June 2015

Rec1-resilin is the first recombinant resilin-mimetic protein polymer, synthesized from exon-1 of the Drosophila melanogaster gene CG15920 that has demonstrated unusual multi-stimuli responsiveness in aqueous solution. Crosslinked hydrogels of Rec1-resilin have also displayed remarkable mechanical properties including near-perfect rubber-like elasticity. The structural basis of these extraordinary properties is not clearly understood. Here we combine a computational and experimental investigation to examine structural ensembles of Rec1-resilin in aqueous solution. The structure of Rec1-resilin in aqueous solutions is investigated experimentally using circular dichroism (CD) spectroscopy and small angle X-ray scattering (SAXS). Both bench-top and synchrotron SAXS are employed to extract structural data sets of Rec1-resilin and to confirm their validity. Computational approaches have been applied to these experimental data sets in order to extract quantitative information about structural ensembles including radius of gyration, pair-distance distribution function and the fractal dimension. The present work confirms that Rec1-resilin is an intrinsically disordered protein (IDP) that displays equilibrium structural qualities between those of a structured globular protein and a denatured protein. The ensemble optimization method (EOM) analysis reveals a single conformational population with partial compactness. This work provides new insight into the structural ensembles of Rec1-resilin in solution.
Three-dimensional virtual surgery models for percutaneous coronary intervention (PCI) optimization strategies
Authors: Wang Hujun , Liu Jinghua , Zheng Xu , Rong Xiaohui , Zheng Xuwei , Peng Hongyu , Silber-Li Zhanghua , Li Mujun , Liu Liyu
Published: June 2015

Percutaneous coronary intervention (PCI), especially coronary stent implantation, has been shown to be an effective treatment for coronary artery disease. However, in-stent restenosis is one of the longstanding unsolvable problems following PCI. Although stents implanted inside narrowed vessels recover normal flux of blood flows, they instantaneously change the wall shear stress (WSS) distribution on the vessel surface. Improper stent implantation positions bring high possibilities of restenosis as it enlarges the low WSS regions and subsequently stimulates more epithelial cell outgrowth on vessel walls. To optimize the stent position for lowering the risk of restenosis, we successfully established a digital three-dimensional (3-D) model based on a real clinical coronary artery and analysed the optimal stenting strategies by computational simulation. Via microfabrication and 3-D printing technology, the digital model was also converted intoin vitromicrofluidic models with 3-D micro channels. Simultaneously, physicians placed real stents inside them; i.e., they performed “virtual surgeries”. The hydrodynamic experimental results showed that the microfluidic models highly inosculated the simulations. Therefore, our study not only demonstrated that the half-cross stenting strategy could maximally reduce restenosis risks but also indicated that 3-D printing combined with clinical image reconstruction is a promising method for future angiocardiopathy research.
The first X-ray photoelectron spectroscopy surface analysis of 4-methyl-2-phenyl-imidazole adsorbed on copper
Authors: Finšgar Matjaž
Published: June 2015

4-Methyl-2-phenyl-imidazole is a new compound that can effectively inhibit copper corrosion in chloride solution.
Acrylate formation from CO2 and ethylene: catalysis with palladium and mechanistic insight
Authors: Stieber S. Chantal E. , Huguet Núria , Kageyama Takeharu , Jevtovikj Ivana , Ariyananda Piyal , Gordillo Alvaro , Schunk Stephan A. , Rominger Frank , Hofmann Peter , Limbach Michael
Published: June 2015

The first palladium catalyst for the reaction of CO2, alkenes and a base to acrylates is reported (TON up to 50).
Amine grafted silica supported CrAuPd alloy nanoparticles: superb heterogeneous catalysts for the room temperature dehydrogenation of formic acid
Authors: Yurderi Mehmet , Bulut Ahmet , Caner Nurdan , Celebi Metin , Kaya Murat , Zahmakiran Mehmet
Published: June 2015

The CrAuPd/N-SiO2 catalyst generates H2 from formic acid solution with unprecedented activity even at room temperature and in the absence of additives.
A zig-zag uranyl(v)–Mn(ii) single chain magnet with a high relaxation barrier
Authors: Chatelain Lucile , Tuna Floriana , Pécaut Jacques , Mazzanti Marinella
Published: June 2015

A 1D zig-zag coordination polymer based on a cation–cation [(UVO2)MnII] repeated unit shows single chain magnet (SCM) behaviour with a high energy barrier of 122 K.
Low temperature oxidative desulfurization with hierarchically mesoporous titaniumsilicate Ti-SBA-2 single crystals
Authors: Shi Chengxiang , Wang Wenxuan , Liu Ni , Xu Xueyan , Wang Danhong , Zhang Minghui , Sun Pingchuan , Chen Tiehong
Published: June 2015

Hierarchically porous Ti-SBA-2 with high framework Ti content was firstly synthesized and exhibited excellent performance in low temperature oxidative desulfurization.
Exploration of CH⋯π interactions involving the π-system of pseudohalide coligands in metal complexes of a Schiff-base ligand
Authors: Chakraborty Prateeti , Purkait Suranjana , Mondal Sandip , Bauzá Antonio , Frontera Antonio , Massera Chiara , Das Debasis
Published: June 2015

The role of non-covalent interactions in the self-assembly of Schiff-base complexes of ZnII, CuII and NiII has been investigated experimentally and theoretically with especial attention to unconventional C–H⋯π interactions involving pseudohalide coligands.
The self- and foreign-absorption continua of water vapor by cavity ring-down spectroscopy near 2.35 μm
Authors: Mondelain D. , Vasilchenko S. , Čermák P. , Kassi S. , Campargue A.
Published: June 2015

Water vapor self and foreign continuum absorption cross sections are measured with unprecedented accuracy around 2.35 μm using high sensitivity CRDS.
Vibrational spectroscopy and theory of Fe2+(CH4)n (n = 1–3)
Authors: Ashraf Muhammad Affawn , Copeland Christopher W. , Kocak Abdulkadir , McEnroe Alexandra R. , Metz Ricardo B.
Published: June 2015

Vibrational spectroscopy of size selected clusters reveals the extent to which interactions with Fe2+ weaken proximate C–H bonds in methane ligands.
Adsorption-assisted photocatalytic activity of nitrogen and sulfur codoped TiO2 under visible light irradiation
Authors: Chung Junho , Chung Jae Woo , Kwak Seung-Yeop
Published: June 2015

Herein, we synthesized the N- and S-codoped TiO2 (NSTs) with an anatase phase using a simple solvothermal treatment and investigated their visible light photocatalytic activity associated with the thermal behavior of dopants in NSTs.
Gd(iii)–Gd(iii) EPR distance measurements – the range of accessible distances and the impact of zero field splitting
Authors: Dalaloyan Arina , Qi Mian , Ruthstein Sharon , Vega Shimon , Godt Adelheid , Feintuch Akiva , Goldfarb Daniella
Published: June 2015

Gd rulers were designed in the 2–8 nm range for in-depth evaluation of Gd(iii) complexes as spin labels for EPR distance measurements.
From lime to silica and alumina: systematic modeling of cement clinkers using a general force-field
Authors: Freitas A. A. , Santos R. L. , Colaço R. , Bayão Horta R. , Canongia Lopes J. N.
Published: June 2015

Probing the lime–silica–alumina diagram using a simple and systematic force-field and MD simulations: from crystalline to amorphous phases.
Ethylene formation by methane dehydrogenation and C–C coupling reaction on a stoichiometric IrO2 (110) surface – a density functional theory investigation
Authors: Pham T. L. M. , Leggesse E. G. , Jiang J. C.
Published: June 2015

The capability to activate methane at mild temperature and facilitate all elementary reactions on the catalyst surface is a defining characteristic of an efficient catalyst especially for the direct conversion of methane to ethylene.
Stereoselective formation and catalytic activity of hydrido(acylphosphane)(chlorido)(pyrazole)rhodium(iii) complexes. Experimental and DFT studies
Authors: San Nacianceno Virginia , Azpeitia Susan , Ibarlucea Lourdes , Mendicute-Fierro Claudio , Rodríguez-Diéguez Antonio , Seco José M. , San Sebastian Eider , Garralda María A.
Published: June 2015

Stereoselectivity assisted by hydrogen bond formation, inhibited by steric hindrance, predicted by DFT calculations.
Synthesis and characterization of manganese triple-decker complexes
Authors: Heinl Sebastian , Balázs Gábor , Bodensteiner Michael , Scheer Manfred
Published: June 2015

The synthesis and characterization (experimental and DFT) of sterically encumbered triple-decker complexes of the very rare class of Pn ligand complexes of manganese is reported.
Urban soil exploration through multi-receiver electromagnetic induction and stepped-frequency ground penetrating radar
Authors: Van De Vijver Ellen , Van Meirvenne Marc , Vandenhaute Laura , Delefortrie Samuël , De Smedt Philippe , Saey Timothy , Seuntjens Piet
Published: June 2015

A high-resolution survey with two state-of-the-art geophysical sensors was performed to investigate an urban soil including various anthropogenic disturbances.
Human health risk associated with direct potable reuse – evaluation through quantitative relative risk assessment case studies
Authors: Soller J. A. , Nellor M. H. , Cruz C. J. , McDonald E.
Published: June 2015

Two hypothetical quantitative relative risk assessment (QRRA) case study evaluations illustrate how QRRA can inform risk management decisions for direct potable reuse.
Towards lignin consolidated bioprocessing: simultaneous lignin depolymerization and product generation by bacteria
Authors: Salvachúa Davinia , Karp Eric M. , Nimlos Claire T. , Vardon Derek R. , Beckham Gregg T.
Published: June 2015

Lignin Consolidated Bioprocessing utilizes microbes that simultaneously depolymerize lignin and convert the resulting aromatic compounds to fuel and chemical precursors.
Systems biology of neurodegenerative diseases
Authors: Wood Levi B. , Winslow Ashley R. , Strasser Samantha Dale
Published: June 2015

Systems biology is a powerful tool for deciphering complex mechanisms driving neurodegenerative diseases.
Direct preparation and conversion of copper hydroxide-based monolithic xerogels with hierarchical pores
Authors: Fukumoto Shotaro , Nakanishi Kazuki , Kanamori Kazuyoshi
Published: June 2015

Copper hydroxide-based xerogels with hierarchical pores were prepared directly and converted to porous materials with a different valency of copper by heat treatment.
Valine-derived carbon dots with colour-tunable fluorescence for the detection of Hg2+ with high sensitivity and selectivity
Authors: Zhang Chunfang , Hu Zhongbo , Song Li , Cui Yanyan , Liu Xiangfeng
Published: June 2015

Green and yellow fluorescent carbon dots with high sensitivity and selectivity for Hg2+ were synthesized from H3PO4 oxidation of valine.
Sulfonated carbon/nano-metal oxide composites: a novel and recyclable solid acid catalyst for organic synthesis in benign reaction media
Authors: Kour Manmeet , Paul Satya
Published: June 2015

A novel catalytic system based on the use of nano-metal oxides and carbon has been designed and exhibits excellent catalytic activity for acid catalyzed organic reactions.
A discrete self-assembled palladium nano-cage catalyses Suzuki–Miyaura coupling heterogeneously and Heck–Mizoroki coupling homogeneously
Authors: Pradhan Subhashis , John Rohith P.
Published: June 2015

A coordination driven Pd2L4 nano-cage heterogeneously catalysed Suzuki–Miyaura coupling and homogeneously catalysed Heck–Mizoroki coupling under aerobic phosphine free conditions without significant loss of activity.
Preparation of biodegradable PEGylated pH/reduction dual-stimuli responsive nanohydrogels for controlled release of an anti-cancer drug
Authors: Zhou Tingting , Zhao Xubo , Liu Lei , Liu Peng
Published: June 2015

Monodisperse biodegradable PEGylated pH and reduction dual-stimuli sensitive PMPB nanohydrogels were prepared as a drug delivery system for controlled release anti-cancer drugs.
Benziporphyrins, a unique platform for exploring the aromatic characteristics of porphyrinoid systems
Authors: Lash Timothy D.
Published: June 2015

Benziporphyrins and related systems exhibit a wide range of properties and may possess nonaromatic, strongly aromatic or even antiaromatic characteristics.
Enantioselective alkynylation of benzo[e][1,2,3]-oxathiazine 2,2-dioxides catalysed by (R)-VAPOL-Zn complexes: synthesis of chiral propargylic cyclic sulfamidates
Authors: De Munck Lode , Monleón Alicia , Vila Carlos , Muñoz M. Carmen , Pedro José R.
Published: June 2015

An enantioselective alkynylation of cyclic benzoxathiazine 2,2-dioxides catalysed by (R)-VAPOL-Zn(ii) complexes is described.
A pH-sensitive and biodegradable supramolecular hydrogel constructed from a PEGylated polyphosphoester-doxorubicin prodrug and α-cyclodextrin
Authors: Li Fei , He Jinlin , Zhang Mingzu , Ni Peihong
Published: June 2015

Fabrication of in situ forming supramolecular hydrogels based on an acid-labile and PEGylated polyphosphoester-doxorubicin prodrug for injectable drug delivery carriers.
Magnetic iron/carbon nanorods derived from a metal organic framework as an efficient heterogeneous catalyst for the chemical oxidation process in water
Authors: Andrew Lin Kun-Yi , Hsu Fu-Kong
Published: June 2015

By one-step carbonization, metal organic frameworks (MOFs) can be conveniently turned into hierarchical hybrid materials which exhibit versatile functionalities.
Facile protocol for reduction of nitroarenes using magnetically recoverable CoM0.2Fe1.8O4 (M = Co, Ni, Cu and Zn) ferrite nanocatalysts
Authors: Goyal Ankita , Kapoor Surbhi , Samuel Pankaj , Kumar Vinod , Singhal Sonal
Published: June 2015

Cu ions occupy the octahedral sites of the ferrite sub-lattice and present a synergistic effect due to the formation of Cu–Co and Cu–Fe ion pairs which triggers the catalytic performance of CoCu0.2Fe1.8O4 ferrite nanoparticles.
Synthesis of exfoliated titanium dioxide nanosheets/nickel–aluminum layered double hydroxide as a novel electrode for supercapacitors
Authors: Zhu Huimin , Liu Qi , Li Zhanshuang , Liu Jingyuan , Jing Xiaoyan , Zhang Hongsen , Wang Jun
Published: June 2015

A facile composite of titanium dioxide nanosheets/nickel–aluminum layered double hydroxide (TiO2/Ni–Al LDH) is fabricated successfully as the electrode material for supercapacitors.
Solid-state thermal conversion of a nanoporous metal–organic framework to a nonporous coordination polymer
Authors: Shirazi Fatemeh Shahangi , Akhbari Kamran
Published: June 2015

A nanoporous metal–organic framework with pillared 2D square-grid network, converts to a nonporous three-dimensional coordination polymer of upon thermal treatment at 350 °C.
Ultrasensitive determination of carcinoembryonic antigens using a magnetoimpedance immunosensor
Authors: Wang Tao , Guo Lei , Lei Chong , Zhou Yong
Published: June 2015

The schematics of the experimental setup for quantitative and ultrasensitive detection of CEA.
Bioadhesive giant vesicles for monitoring hydroperoxidation in lipid membranes
Authors: Aoki P. H. B. , Schroder A. P. , Constantino C. J. L. , Marques C. M.
Published: June 2015

Osmotic stresses, protein insertion or lipid oxidation lead to area increase of self-assembled lipid membranes.
Bio-inspired terpolymers containing dopamine, cations and MPC: a versatile platform to construct a recycle antibacterial and antifouling surface
Authors: Wang B. L. , Jin T. W. , Han Y. M. , Shen C. H. , Li Q. , Lin Q. K. , Chen H.
Published: June 2015

A new kind of bio-inspired terpolymer was synthesized by a conventional free radical terpolymerization of dopamine methacrylamide (DMA), 2-(dimethylamino)-ethyl methacrylate (DMAEMA) and 2-methacryloyloxyethyl phosphorylcholine (MPC) with azobisisobutyronitrile (AIBN) as an initiator.
Facile synthesis of folic acid-functionalized iron oxide nanoparticles with ultrahigh relaxivity for targeted tumor MR imaging
Authors: Li Jingchao , Hu Yong , Yang Jia , Sun Wenjie , Cai Hongdong , Wei Ping , Sun Yaping , Zhang Guixiang , Shi Xiangyang , Shen Mingwu
Published: June 2015

Folic acid-functionalized iron oxide nanoparticles with an ultrahigh r2 relaxivity can be formed for targeted MR imaging of tumors.
Application of memetic algorithm for selective harmonic elimination in multi‐level inverters
Authors: Niknam Kumle Alireza , Fathi Seyed Hamid , Jabbarvaziri Faramarz , Jamshidi Mehdi , Heidari Yazdi Seyed Saeed
Published: June 2015

Multi‐level inverter (MLI) is a promising technology, able to generate high‐quality power with lower switching frequency. Therefore it leads to high conversion efficiency and low switching losses. Selective harmonic elimination is a fundamental frequency switching strategy that theoretically provides desirable output waveform for MLIs by elimination of low order harmonics. Unfortunately, complexity, non‐linearity and solvability features attached to this method have limited its industrial application. In this study, a particle swarm optimisation (PSO)‐based memetic algorithm (MA) guided by mesh adaptive direct search is introduced as a suitable choice for the harmonic optimisation problem. This algorithm is precise and applicable to any MLI. The results show that MA converges to the exact solution for feasible modulation index. When the problem has no exact solution, the algorithm finds a relatively proper solution to regulate the fundamental component of the voltage. Furthermore, the comparison between MA and other methods shows that the probability of convergence of MA is higher than others. For 48% of the analysed data MA reaches to a fitness value lower than 10−30 whereas this probability is 5% for PSO and almost zero for genetic algorithm and bee algorithm. The proposed method has been implemented on a cascade seven‐level inverter.
Energy yields of small grid connected photovoltaic system: effects of component reliability and maintenance
Authors: Perdue Michael , Gottschalg Ralph
Published: June 2015

The likelihood of system failure of small systems is investigated in order to establish the risk associated for the investment into a photovoltaic (PV) system for small domestic applications. This is achieved by reviewing existing literature on PV system failure rates and using these as an input for a statistical PV system yield simulation tool that considers failure and repair. It is typically assumed that these systems do not require any maintenance, but it is shown that this will have near catastrophic impact on the energy production of PV systems. The no maintenance is not a likely scenario, as small systems have to register their generation to achieve a feed‐in‐tariff. In a later stage, when PV is used for self‐consumption only, this may change but in the present market most users are forced to carry out a quarterly check and thus this catastrophic failure is avoided by the need of having to apply for the feed‐in‐tariff. Minimum maintenance strategies for ensuring profitable system operation are investigated and their cost‐effectiveness is discussed. It is shown that the present situation where many systems are neither monitored nor is any maintenance carried out results in a high probability of unsuccessful system operation as failure detection may take a very long time. Successful system operation here is defined as not recovering the financial investment. It would be advisable to carry out at least monthly performance checks as otherwise it is likely to have more than 10% energy lost because of system downtime. This requires, however, availability of irradiance data as otherwise it is not possible to identify whether low yields are due to resource issues or really system yield issues.
Identify asthma genes across three phases based on protein–protein interaction network
Authors: Yang Fengyong , Yu Xianling , Wang Liping , Liu Lili , Xu Xiaorong , Zheng Xingfeng , Wei Guangchen
Published: June 2015

Asthma is a common inflammatory disease that is generally caused by genetic mutations or environmental factors. Recently, the emerging of omics data provides an alternative way to understand asthma. In this study, the authors present a new framework to detect asthma disease genes based on protein–protein interaction network (PPIN) and gene expression. Specifically, they construct PPINs for different stages of asthma, and detect those interactions occurred in the specific stages. By investigating the proteins in these stage‐specific interactions, they find they are more likely related to asthma, and the functional enrichment analysis indicate that the pathways enriched in the differential interactions are related to the progress of asthma. Moreover, some proteins in the differential interactions have been previously reported to be related to asthma in the literature, implying the usefulness of the proposed approach.
Quantum treatment of protons with the reduced explicitly correlated Hartree-Fock approach
Authors: Sirjoosingh Andrew , Pak Michael V. , Brorsen Kurt R. , Hammes-Schiffer Sharon
Published: June 2015

The nuclear-electronic orbital (NEO) approach treats select nuclei quantum mechanically on the same level as the electrons and includes nonadiabatic effects between the electrons and the quantum nuclei. The practical implementation of this approach is challenging due to the significance of electron-nucleus dynamical correlation. Herein, we present a general extension of the previously developed reduced NEO explicitly correlated Hartree-Fock (RXCHF) approach, in which only select electronic orbitals are explicitly correlated to each quantum nuclear orbital via Gaussian-type geminal functions. Approximations of the electronic exchange between the geminal-coupled electronic orbitals and the other electronic orbitals are also explored. This general approach enables computationally tractable yet accurate calculations on molecular systems with quantum protons. The RXCHF method is applied to the hydrogen cyanide (HCN) and FHF− systems, where the proton and all electrons are treated quantum mechanically. For the HCN system, only the two electronic orbitals associated with the CH covalent bond are geminal-coupled to the proton orbital. For the FHF− system, only the four electronic orbitals associated with the two FH covalent bonds are geminal-coupled to the proton orbital. For both systems, the RXCHF method produces qualitatively accurate nuclear densities, in contrast to mean field-based NEO approaches. The development and implementation of the RXCHF method provide the framework to perform calculations on systems such as proton-coupled electron transfer reactions, where electron-proton nonadiabatic effects are important.
Nuclear-electronic orbital reduced explicitly correlated Hartree-Fock approach: Restricted basis sets and open-shell systems
Authors: Brorsen Kurt R. , Sirjoosingh Andrew , Pak Michael V. , Hammes-Schiffer Sharon
Published: June 2015

The nuclear electronic orbital (NEO) reduced explicitly correlated Hartree-Fock (RXCHF) approach couples select electronic orbitals to the nuclear orbital via Gaussian-type geminal functions. This approach is extended to enable the use of a restricted basis set for the explicitly correlated electronic orbitals and an open-shell treatment for the other electronic orbitals. The working equations are derived and the implementation is discussed for both extensions. The RXCHF method with a restricted basis set is applied to HCN and FHF− and is shown to agree quantitatively with results from RXCHF calculations with a full basis set. The number of many-particle integrals that must be calculated for these two molecules is reduced by over an order of magnitude with essentially no loss in accuracy, and the reduction factor will increase substantially for larger systems. Typically, the computational cost of RXCHF calculations with restricted basis sets will scale in terms of the number of basis functions centered on the quantum nucleus and the covalently bonded neighbor(s). In addition, the RXCHF method with an odd number of electrons that are not explicitly correlated to the nuclear orbital is implemented using a restricted open-shell formalism for these electrons. This method is applied to HCN+, and the nuclear densities are in qualitative agreement with grid-based calculations. Future work will focus on the significance of nonadiabatic effects in molecular systems and the further enhancement of the NEO-RXCHF approach to accurately describe such effects.
Impact of secondary structure and hydration water on the dielectric spectrum of poly-alanine and possible relation to the debate on slaved versus slaving water
Authors: Rinne Klaus F. , Schulz Julius C. F. , Netz Roland R.
Published: June 2015

Using extensive molecular dynamics simulations of a single eight-residue alanine polypeptide in explicit water, we investigate the influence of α-helix formation on the dielectric spectrum. For this, we project long equilibrium trajectories into folded and unfolded states and thereby obtain dielectric spectra representative for disordered as well α-helical conformations without the need to change any other system parameter such as pH or temperature. The absorption spectrum in the α-helical state exhibits a feature in the sub-GHz range that is significantly stronger than in the unfolded state. As we show by an additional decomposition into peptide and water contributions, this slow dielectric mode, the relaxation time of which matches the independently determined peptide rotational relaxation time, is mostly caused by peptide polarization correlations, but also contains considerable contributions from peptide-water correlations. In contrast, the peptide spectral contribution shows no features in the GHz range where bulk water absorbs, not even in the peptide-water correlation part, we conclude that hydration water around Ala8 is more influenced by peptide polarization relaxation effects than the other way around. A further decomposition into water-self and water-collective polarization correlations shows that the dielectric response of hydration water is, in contrast to electrolyte solutions, retarded and that this retardation is mostly due to collective effects, the self relaxation of hydration water molecules is only slightly slowed down compared to bulk water. We find the dynamic peptide-water polarization cross correlations to be rather long-ranged and to extend more than one nanometer away from the peptide-water interface into the water hydration shell, in qualitative agreement with previous simulation studies and recent THz absorption experiments.
Optical properties of alkali halide crystals from all-electron hybrid TD-DFT calculations
Authors: Webster R. , Bernasconi L. , Harrison N. M.
Published: June 2015

We present a study of the electronic and optical properties of a series of alkali halide crystals AX, with A = Li, Na, K, Rb and X = F, Cl, Br based on a recent implementation of hybrid-exchange time-dependent density functional theory (TD-DFT) (TD-B3LYP) in the all-electron Gaussian basis set code CRYSTAL. We examine, in particular, the impact of basis set size and quality on the prediction of the optical gap and exciton binding energy. The formation of bound excitons by photoexcitation is observed in all the studied systems and this is shown to be correlated to specific features of the Hartree-Fock exchange component of the TD-DFT response kernel. All computed optical gaps and exciton binding energies are however markedly below estimated experimental and, where available, 2-particle Green’s function (GW-Bethe-Salpeter equation, GW-BSE) values. We attribute this reduced exciton binding to the incorrect asymptotics of the B3LYP exchange correlation ground state functional and of the TD-B3LYP response kernel, which lead to a large underestimation of the Coulomb interaction between the excited electron and hole wavefunctions. Considering LiF as an example, we correlate the asymptotic behaviour of the TD-B3LYP kernel to the fraction of Fock exchange admixed in the ground state functional cHF and show that there exists one value of cHF (∼0.32) that reproduces at least semi-quantitatively the optical gap of this material.
Novel method for estimating the dynamic characteristics of pressure sensor in shock tube calibration test
Authors: Li Qiang , Wang Zhongyu , Wang Zhuoran , Yan Hu
Published: June 2015

A shock tube is usually used to excite the dynamic characteristics of the pressure sensor used in an aircraft. This paper proposes a novel estimation method for determining the dynamic characteristic parameters of the pressure sensor. A preprocessing operation based on Grey Model [GM(1,1)] and bootstrap method (BM) is employed to analyze the output of a calibrated pressure sensor under step excitation. Three sequences, which include the estimated value sequence, upper boundary, and lower boundary, are obtained. The processing methods on filtering and modeling are used to explore the three sequences independently. The optimal estimated, upper boundary, and lower boundary models are then established. The three models are solved, and a group of dynamic characteristic parameters corresponding to the estimated intervals are obtained. A shock tube calibration test consisting of two experiments is performed to validate the performance of the proposed method. The results show that the relative errors of the dynamic characteristic parameters of time and frequency domains do not exceed 9% and 10%, respectively. Moreover, the nominal and estimated values of the parameters fall into the estimated intervals limited by the upper and lower values.
Design of a MEMS piezoresistive differential pressure sensor with small thermal hysteresis for air data modules
Authors: Song Jin Woo , Lee Jang-Sub , An Jun-Eon , Park Chan Gook
Published: June 2015

The design, fabrication, and evaluation results of a MEMS piezoresistive differential pressure sensor fabricated by the dry etching process are described in this paper. The proposed sensor is designed to have optimal performances in mid-pressure range from 0 psi to 20 psi suitable for a precision air data module. The piezoresistors with a Wheatstone bridge structure are implanted where the thermal effects are minimized subject to sustainment of the sensitivity. The rectangular-shaped silicon diaphragm is adopted and its dimension is analyzed for improving pressure sensitivity and linearity. The bridge resistors are driven by constant current to compensate temperature effects on sensitivity. The designed differential pressure sensor is fabricated by using MEMS dry etching techniques, and the fabricated sensing element is attached and packaged in a Kovar package in consideration of leakage and temperature hysteresis. The implemented sensors are tested and evaluated as well. The evaluation results show the static RSS (root sum square) accuracy including nonlinearity, non-repeatability, and pressure hysteresis before temperature compensation is about 0.09%, and the total error band which includes the RSS accuracy, the thermal hysteresis, and other thermal effects is about 0.11%, which confirm the validity of the proposed design process.
True orbit simulation of piecewise linear and linear fractional maps of arbitrary dimension using algebraic numbers
Authors: Saito Asaki , Yasutomi Shin-ichi , Tamura Jun-ichi , Ito Shunji
Published: June 2015

We introduce a true orbit generation method enabling exact simulations of dynamical systems defined by arbitrary-dimensional piecewise linear fractional maps, including piecewise linear maps, with rational coefficients. This method can generate sufficiently long true orbits which reproduce typical behaviors (inherent behaviors) of these systems, by properly selecting algebraic numbers in accordance with the dimension of the target system, and involving only integer arithmetic. By applying our method to three dynamical systems—that is, the baker's transformation, the map associated with a modified Jacobi-Perron algorithm, and an open flow system—we demonstrate that it can reproduce their typical behaviors that have been very difficult to reproduce with conventional simulation methods. In particular, for the first two maps, we show that we can generate true orbits displaying the same statistical properties as typical orbits, by estimating the marginal densities of their invariant measures. For the open flow system, we show that an obtained true orbit correctly converges to the stable period-1 orbit, which is inherently possessed by the system.
Understanding the stable boron clusters: A bond model and first-principles calculations based on high-throughput screening
Authors: Xu Shao-Gang , Zhao Yu-Jun , Liao Ji-Hai , Yang Xiao-Bao
Published: June 2015

The unique electronic property induced diversified structure of boron (B) cluster has attracted much interest from experimentalists and theorists. B30–40 were reported to be planar fragments of triangular lattice with proper concentrations of vacancies recently. Here, we have performed high-throughput screening for possible B clusters through the first-principles calculations, including various shapes and distributions of vacancies. As a result, we have determined the structures of Bn clusters with n = 30–51 and found a stable planar cluster of B49 with a double-hexagon vacancy. Considering the 8-electron rule and the electron delocalization, a concise model for the distribution of the 2c–2e and 3c–2e bonds has been proposed to explain the stability of B planar clusters, as well as the reported B cages.
Enhanced magnetic reconnection in the presence of pressure gradients
Authors: Pueschel M. J. , Terry P. W. , Told D. , Jenko F.
Published: June 2015

Magnetic reconnection in the presence of background pressure gradients is studied, with special attention to parallel (compressional) magnetic fluctuations. A process is reported that reconnects fields through coupling of drift-wave-type instabilities with current sheets. Its time scale is set not by the reconnecting field but by inhomogeneities of the background density or temperature. The observed features can be attributed to a pressure-gradient-driven linear instability which interacts with the reconnecting system but is fundamentally different from microtearing. In particular, this mode relies on parallel magnetic fluctuations and the associated drift. For turbulent reconnection, similar or even stronger enhancements are reported. In the solar corona, this yields a critical pressure gradient scale length of about 200 km below which this new process becomes dominant over the tearing instability.
Memristor-based Willshaw network: Capacity and robustness to noise in the presence of defects
Authors: Dias C. , Guerra L. M. , Ventura J. , Aguiar P.
Published: June 2015

The recent realization of memristors, nanodevices remarkably similar to biological synapses, opened the possibility to fabricate highly scalable artificial neural networks. While the physical implementation of such networks is still emerging, it is useful to perform simulations to determine the impact of non-ideal devices or device faults in the performance of memory networks. Here, we numerically evaluate a memristor-based Willshaw associative memory network, studying its capacity and robustness to noise as a function of defects probability and device parameter variations. Two types of defective memristors are addressed (stuck-at-0 and stuck-at-1) and Gaussian distributions are imposed to their threshold voltages, ON and OFF resistances. We conclude that the type and number of defects strongly determine how the network should be operated. The reading current threshold also plays a key role in determining the network's capacity and robustness to noise. Furthermore, there is a maximum defect percentage above which the network can no longer reliably store information. We also found that the memristor-based Willshaw network is more sensitive to resistance variance than to threshold voltage variance.
High efficiency heterojunction solar cells on n-type kerfless mono crystalline silicon wafers by epitaxial growth
Authors: Kobayashi Eiji , Watabe Yoshimi , Hao Ruiying , Ravi T. S.
Published: June 2015

We present a heterojunction (HJ) solar cell on n-type epitaxially grown kerfless crystalline-silicon (c-Si) with a conversion efficiency of 22.5%. The total cell area is 243.4 cm2. The cell has a short-circuit current density of 38.6 mA/cm2, an open-circuit voltage of 735 mV, and a fill factor of 0.791. The key advantages and technological tasks of epitaxial wafers for HJ solar cells are discussed, in comparison with conventional n-type Czockralski c-Si wafers. The combination of HJ and kerfless technology can lead to high conversion efficiency with a potential at low cost.
Fluorinated graphene oxide for enhanced S and X-band microwave absorption
Authors: Sudeep P. M. , Vinayasree S. , Mohanan P. , Ajayan P. M. , Narayanan T. N. , Anantharaman M. R.
Published: June 2015

Here we report the microwave absorbing properties of three graphene derivatives, namely, graphene oxide (GO), fluorinated GO (FGO, containing 5.6 at. % Fluorine (F)), and highly FGO (HFGO, containing 23 at. % F). FGO is known to be exhibiting improved electrochemical and electronic properties when compared to GO. Fluorination modifies the dielectric properties of GO and hence thought of as a good microwave absorber. The dielectric permittivities of GO, FGO, and HFGO were estimated in the S (2 GHz to 4 GHz) and X (8 GHz to 12 GHz) bands by employing cavity perturbation technique. For this, suspensions containing GO/FGO/HFGO were made in N-Methyl Pyrrolidone (NMP) and were subjected to cavity perturbation. The reflection loss was then estimated and it was found that −37 dB (at 3.2 GHz with 6.5 mm thickness) and −31 dB (at 2.8 GHz with 6 mm thickness) in the S band and a reflection loss of −18 dB (at 8.4 GHz with 2.5 mm thickness) and −10 dB (at 11 GHz with 2 mm thickness) in the X band were achieved for 0.01 wt. % of FGO and HFGO in NMP, respectively, suggesting that these materials can serve as efficient microwave absorbers even at low concentrations.
Nonmonotonic fracture behavior of polymer nanocomposites
Authors: de Castro J. G. , Zargar R. , Habibi M. , Varol S. H. , Parekh S. H. , Hosseinkhani B. , Adda-Bedia M. , Bonn D.
Published: June 2015

Polymer composite materials are widely used for their exceptional mechanical properties, notably their ability to resist large deformations. Here, we examine the failure stress and strain of rubbers reinforced by varying amounts of nano-sized silica particles. We find that small amounts of silica increase the fracture stress and strain, but too much filler makes the material become brittle and consequently fracture happens at small deformations. We thus find that as a function of the amount of filler there is an optimum in the breaking resistance at intermediate filler concentrations. We use a modified Griffith theory to establish a direct relation between the material properties and the fracture behavior that agrees with the experiment.
Limitations and potential for individualised feeding of concentrate supplements to grazing dairy cows
Authors: Hills J. L. , García S. C. , Dela Rue B. , Clark C. E. F.
Published: June 2015

The increasing availability and installation of computerised feeding and milk-monitoring technology in Australia and New Zealand has led to an increased interest in feeding individual cows different amounts and types of supplements over lactation. However, there is confusion about the potential benefits of individualised feeding strategies compared with feeding the same amount of supplement to all cows in the herd on any given day. The majority of bail feeding research conducted over the past 30 years has identified little difference in cow response between flat-rate feeding and more complicated approaches of split feeding or feeding to individual cow milk yield. However, it must be noted that many of these experiments involved animals with ad libitum access to a forage supply. This is an important distinction as individual cows receiving high-quality forage ad libitum would be able to compensate, at least partially, for any shortage in concentrate. Large variability in response to supplements among individual cows within the herd implies that there should be a benefit from individualised bail feeding practices. This review examines the potential for individualised bail feeding in pasture-based dairy systems, considering both system (pasture allowance and type) and cow-level parameters (e.g. dry matter intake, milk yield, genotype, bodyweight, stage of lactation) that could affect the individual cow response to a particular supplement, and discusses the current limitations and future challenges for implementing this technology on farm. Recommendations for future research are made to address any knowledge gaps.
Integrated 3D view of postmating responses by the
Drosophila melanogaster
female reproductive tract, obtained by micro-computed tomography scanning
Authors: Mattei Alexandra L. , Riccio Mark L. , Avila Frank W. , Wolfner Mariana F.
Published: June 2015

Significance

Our high-resolution, multiscale micro-computed tomography scans of
Drosophila
provide the first 3D view, to our knowledge, of the in situ morphological changes that occur in a female insect’s reproductive tract (RT) during and after mating. By means of this holistic analysis, we determined how the postmating reproductive events of ovulation, egg movement, sperm storage, sperm release, and fertilization are coordinated. We observed and quantified phenomena not detected in prior studies of dissected materials. These phenomena included coordinated looping and unlooping of the uterus and oviducts, and a potential mating-induced trauma in the female RT. This new perspective allowed us to revisit experimentally, and newly define, the effects of male- and female-secreted molecules on female postmating physiology.
A Tool Supporting the Extraction of Angling Effort Data from Remote Camera Images
Authors: Greenberg Saul , Godin Theresa
Published: June 2015

Estimating angling effort on more than a few lakes can be prohibitively expensive using creel surveys and often requires finer-scale angler distribution data than aerial surveys can provide. An alternate method uses remote cameras to capture images of lakes at hourly intervals over long time periods. Technicians then visually analyze the thousands of generated images for features of interest (e.g., angler counts and environmental conditions) and use those data to estimate angling effort. The problem is that the visual analysis step is time-consuming, expensive, and difficult to validate. Consequently, we elicited the strategies and best practices technicians used when analyzing images and identified bottlenecks. We then designed software, called Timelapse to better support image analysis. In use for several years, Timelapse has proven a cost-effective method of estimating angling effort in British Columbia's small lakes fisheries; it significantly eases a technician's workflow and doubles the number of images one can process per hour.

La estimación del esfuerzo de pesca con anzuelo que se realiza en varios lagos mediante muestreos en puerto, puede llegar a tener costos prohibitivos y suele requerir una información más fina sobre la distribución del esfuerzo que la que proveen los muestreos aéreos. Un método alternativo se basa en la captura de imágenes de los lagos usando cámaras remotas, tomadas cada hora durante largos periodos. Posteriormente, los cientos de imágenes generadas son analizadas visualmente por los técnicos con el fin de detectar características de interés (v.g. conteo de pescadores y condiciones ambientales) y esta información se usa para estimar el esfuerzo de pesca. El problema es que el análisis visual consume mucho tiempo, es caro y difícil de validar. En consecuencia, en este trabajo se elucidan las estrategias y mejores prácticas que el personal técnico utiliza al analizar las imágenes e identificar cuellos de botella. Posteriormente se diseña un programa llamado Timelapse, como apoyo para el análisis de imágenes. Habiendo sido utilizado por varios años, Timelapse ha mostrado ser un método efectivo en cuanto a costos para estimar el esfuerzo en pesquerías de pequeños lagos en la Columbia Británica; alivia de forma importante el flujo de trabajo del personal técnico y duplica el número de imágenes que pueden procesarse en una hora.
Gauss-compatible Galerkin schemes for time-dependent Maxwell equations
Authors: Campos Pinto Martin , Sonnendrücker Eric
Published: June 2015

In this article we propose a unified analysis for conforming and non-conforming finite element methods that provides a partial answer to the problem of preserving discrete divergence constraints when computing numerical solutions to the time-dependent Maxwell system. In particular, we formulate a compatibility condition relative to the preservation of genuinely oscillating modes that takes the form of a generalized commuting diagram, and we show that compatible schemes satisfy convergence estimates leading to long-time stability with respect to stationary solutions. These findings are applied by specifying compatible formulations for several classes of Galerkin methods, such as the usual curl-conforming finite elements and the centered discontinuous Galerkin (DG) scheme. We also propose a new conforming/non-conforming Galerkin (Conga) method where fully discontinuous solutions are computed by embedding the general structure of curl-conforming finite elements into larger DG spaces. In addition to naturally preserving one of the Gauss laws in a strong sense, the Conga method is both spectrally correct and energy conserving, unlike existing DG discretizations where the introduction of a dissipative penalty term is needed to avoid the presence of spurious modes.