bluuebunny/crossref_metadata_2025 huggingface dataset:
Multiplexity versus correlation: the role of local constraints in real multiplexes
Authors: Gemmetto V. , Garlaschelli D.
Published: March 2015

Several systems can be represented as multiplex networks, i.e. in terms of a superposition of various graphs, each related to a different mode of connection between nodes. Hence, the definition of proper mathematical quantities aiming at capturing the added level of complexity of those systems is required. Various steps in this direction have been made. In the simplest case, dependencies between layers are measured via correlation-based metrics, a procedure that we show to be equivalent to the use of completely homogeneous benchmarks specifying only global constraints. However, this approach does not take into account the heterogeneity in the degree and strength distributions, which is instead a fundamental feature of real-world multiplexes. In this work, we compare the observed dependencies between layers with the expected values obtained from maximum-entropy reference models that appropriately control for the observed heterogeneity in the degree and strength distributions. This information-theoretic approach results in the introduction of novel and improved multiplexity measures that we test on different datasets, i.e. the International Trade Network and the European Airport Network. Our findings confirm that the use of homogeneous benchmarks can lead to misleading results and highlight the important role played by the distribution of hubs across layers.
On the role of gold nanoparticles in the selective photooxidation of 2-propanol over Au/TiO2
Authors: Lüken Alexander , Muhler Martin , Strunk Jennifer
Published: March 2015

Partial insight into the reaction mechanism of the photooxidation of 2-propanol over Au/TiO2. 2-Propanol is activated by hole capture and converted to acetone requiring the presence of O2 as an electron acceptor. The deposited Au nanoparticles are assumed to facilitate the electron transfer from the TiO2 conduction band to adsorbed O2.
On the origin and variation of colors in lobster carapace
Authors: Begum Shamima , Cianci Michele , Durbeej Bo , Falklöf Olle , Hädener Alfons , Helliwell John R. , Helliwell Madeleine , Regan Andrew C. , Ian F. Watt C.
Published: March 2015

We present evidence that astaxanthin enolate may form in a protein complex environment, and is associated with a large bathochromic absorption shift to give the blue–black color of lobsters.
Glutathione-triggered release of model drug molecules from mesoporous silica nanoparticles via a non-redox process
Authors: Huang Xiaoxi , Zhang Tao , Goswami Anandarup , Luo Feixiang , Asefa Tewodros
Published: March 2015

Model drug-loaded mesoporous silica nanoparticles (MSNs) that are responsive to the pH rather than the redox changes related to glutathione (GSH) are prepared using surfactant-free MSNs as a precursor.
From 1D to 3D: a new route to fabricate tridimensional structures via photo-generation of silver networks
Authors: Shen Huaizhong , Wu Yuxin , Fang Liping , Ye Shunsheng , Wang Zhaoyi , Liu Wendong , Cheng Zhongkai , Zhang Junhu , Wang Zhanhua , Yang Bai
Published: March 2015

A time-saving and low-cost method is established to construct stacked 3D structures through the combination of bottom-up and top-down techniques which enables us to create building blocks freely and to precisely adjust the matrix feature.
In situ growth of FeS microsheet networks with enhanced electrochemical performance for lithium-ion batteries
Authors: Xing Chengcheng , Zhang Dan , Cao Ke , Zhao Shumin , Wang Xin , Qin Haiying , Liu Jiabin , Jiang Yinzhu , Meng Liang
Published: March 2015

FeS microsheet networks on iron foil were preparedviaa facile solution-based approach. The networks exhibited notably improved capacity performance for LIBs, benefiting from their layered structure and unique morphology.
Hexamethylene diisocyanate as an electrolyte additive for high-energy density lithium ion batteries
Authors: Liu Yang , Qin Yinping , Peng Zhe , Zhou Jingjing , Wan Changjin , Wang Deyu
Published: March 2015

Hexamethylene diisocyanate can chemically react with the onium ion produced by the oxidation of propylene carbonate andin situgenerate a novel interfacial layer that is stable at high potential.
Layered double hydroxide nanoparticles to enhance organ-specific targeting and the anti-proliferative effect of cisplatin
Authors: Kuo Yue-Ming , Kuthati Yaswanth , Kankala Ranjith Kumar , Wei Pei-Ru , Weng Ching-Feng , Liu Chen-Lun , Sung Ping-Jyun , Mou Chung-Yuan , Lee Chia-Hung
Published: March 2015

The role of nanoparticle charge in biodistribution is evaluated by modifying the external surface of layered double hydroxides with various charges and a fluorescent dye (Cy5.5) is doped to assess the biodistribution.
Quantum dot display enhances activity of a phosphotriesterase trimer
Authors: Breger Joyce C. , Walper Scott A. , Oh Eunkeu , Susumu Kimihiro , Stewart Michael H. , Deschamps Jeffrey R. , Medintz Igor L.
Published: March 2015

Phosphotrisomerase trimer assembled on a quantum dot. This construct displays enhanced catalytic over freely diffusing enzyme and has potential to be spun into a fiber.
Measurements of the effect of membrane asymmetry on the mechanical properties of lipid bilayers
Authors: Elani Yuval , Purushothaman Sowmya , Booth Paula J. , Seddon John M. , Brooks Nicholas J. , Law Robert V. , Ces Oscar
Published: March 2015

We detail an approach for constructing asymmetric membranes and characterising their mechanical properties, leading to the first measurement of the effect of asymmetry on lipid bilayer mechanics.
Role of synergistic π–π stacking and X–H⋯Cl (X = C, N, O) H-bonding interactions in gelation and gel phase crystallization
Authors: Bhattacharjee Subham , Bhattacharya Santanu
Published: March 2015

Gel phase crystallization in a transparent gel via synergistic non-covalent interactions has been reported along with various remarkable features.
Improved selectivity for partial oxidation of methane to methanol in the presence of nitrite ions and BiVO4 photocatalyst
Authors: Murcia-López S. , Villa K. , Andreu T. , Morante J. R.
Published: March 2015

Nitrite ions are shown to significantly improve the selectivity of the photocatalytic oxidation of methane to methanol.
An intuitional hierarchical assembly of cluster–organic frameworks with a thickness of 1.97 nm from a discrete Co14 cluster
Authors: Huang Fu-Ping , Yao Peng-Fei , Li Hai-Ye , Yu Qing , Bian He-Dong , Liang Hong
Published: March 2015

An intuitional hierarchical assembly, metaphorically referred to as a “blossom and yield fruit” process, from a discrete cluster {[Co14(CH3O)4(dpbt)6Cl12]·14CH3OH, (1)} to 2D cluster organic frameworks {[Co14(CH3O)10(dpbt)6 Cl6]·12CH3OH, (2)}, has been established.
Visible light promoted carbodifluoroalkylation of allylic alcohols via concomitant 1,2-aryl migration
Authors: Xu Pan , Hu Kaidong , Gu Zhangxi , Cheng Yixiang , Zhu Chengjian
Published: March 2015

A novel visible light promoted carbodifluoroalkylation of allylic alcohols is disclosed.
Phosphazenes: efficient organocatalysts for the catalytic hydrosilylation of carbon dioxide
Authors: Courtemanche Marc-André , Légaré Marc-André , Rochette Étienne , Fontaine Frédéric-Georges
Published: March 2015

Phosphazene are organocatalysts for the metal-free hydrosilylation of CO2 (TOF 32 h−1; TON 759). It was shown that N,N-dimethylformamide can reduce CO2 in the absence of catalyst.
Direct observation of the dealloying process of a platinum–yttrium nanoparticle fuel cell cathode and its oxygenated species during the oxygen reduction reaction
Authors: Malacrida Paolo , Sanchez Casalongue Hernan G. , Masini Federico , Kaya Sarp , Hernández-Fernández Patricia , Deiana Davide , Ogasawara Hirohito , Stephens Ifan E. L. , Nilsson Anders , Chorkendorff Ib
Published: March 2015

Size-selected 9 nm PtxY nanoparticles have recently shown an outstanding catalytic activity for the oxygen reduction reaction, representing a promising cathode catalyst for proton exchange membrane fuel cells (PEMFCs).
Vacancy-induced initial decomposition of condensed phase NTO via bimolecular hydrogen transfer mechanisms at high pressure: a DFT-D study
Authors: Liu Zhichao , Wu Qiong , Zhu Weihua , Xiao Heming
Published: March 2015

The vacancy defects induce initial decomposition of condensed phase NTO via bimolecular hydrogen transfer mechanisms at high pressure.
Guanidine sulfate-assisted synthesis of hexagonal WO3 nanoparticles with enhanced adsorption properties
Authors: Mu Wanjun , Li Mei , Li Xingliang , Ma Zongping , Zhang Rui , Yu Qianhong , Lv Kai , Xie Xiang , He Jiaheng , Wei Hongyuan , Jian Yuan
Published: March 2015

The hexagonal WO3 nanowires prepared with the assistance of C2H10N·H2SO4 possess a large specific surface area and numerous adsorption functional groups, consequently improving the Sr2+ adsorption capacity considerably.
Alkali metal-mediated dehydrocoupling of Me2NH·BH3
Authors: Bellham Peter , Hill Michael S. , Kociok-Köhn Gabriele
Published: March 2015

Bis(trimethylsilyl)amide derivatives of the group 1 elements (Li, Na, K) are competent pre-catalysts for the dehydrocoupling of Me2NH·BH3via the formation of intermediates containing [H3BNMe2BH2Me2N]− anions.
Silver intercalation in SPS dense TiS2: staging and thermoelectric properties
Authors: Barbier Tristan , Lebedev Oleg I. , Roddatis Vladimir , Bréard Yohann , Maignan Antoine , Guilmeau Emmanuel
Published: March 2015

Polycrystalline samples in the series AgxTiS2 with x varying from 0 to 0.2 were prepared using solid–liquid–vapor reaction and spark plasma sintering.
Dynamic formation of a microchannel array enabling kinesin-driven microtubule transport between separate compartments on a chip
Authors: Fujimoto Kazuya , Nagai Moeto , Shintaku Hirofumi , Kotera Hidetoshi , Yokokawa Ryuji
Published: March 2015

Here, we propose a microtubule-based transport system between separate compartments in a microfluidic device, which dynamically forms single-micrometre-scale channels.
Understanding thio-effects in simple phosphoryl systems: role of solvent effects and nucleophile charge
Authors: Carvalho Alexandra T. P. , O'Donoghue AnnMarie C. , Hodgson David R. W. , Kamerlin Shina C. L.
Published: March 2015

Detailed quantum chemical calculations provide insight on the origin of large differences in experimental thio-effects for the hydrolysis of (thio)phosphodichloridates by water and hydroxide nucleophiles.
In situ study of the annealing process of a polyethylene cast film with a row-nucleated crystalline structure by SAXS
Authors: Xu R. J. , Chen X. D. , Cai Q. , Chen C. B. , Lin Y. F. , Lei C. H. , Li L. B.
Published: March 2015

The secondary crystallization has more effect on polyethylene crystal thickening than melt recrystallization during the annealing process.
2-(2-Nitrophenyl) propyl: a rapidly released photolabile COOH-protecting group for solid-phase peptide synthesis
Authors: Wang Gang , Peng Tao , Zhang Shouguo , Wang Junyi , Wen Xiaoxue , Yan Haiyan , Hu Liming , Wang Lin
Published: March 2015

We developed a new efficient photolabile protecting group, 2-(2-nitrophenyl) propyl (Npp) that blocks the carboxyl group in peptide synthesis.
Anionic polymerization by an electron transfer process from a CdSe quantum dot–perylenediimide (PDI) system
Authors: Rusen Edina , Mocanu Alexandra , Nistor Leona Cristina , Hudhomme Piétrick , Diacon Aurel
Published: March 2015

Reversible physical interactions between CdSe quantum dots (QDs) and perylenediimide (PDI) derivatives have been investigated.
The impact of polymer structure on the adsorption of ionic polyamino acid homopolymers and their diblock copolymers on colloidal chromium(iii) oxide
Authors: Ostolska Iwona , Wiśniewska Małgorzata
Published: March 2015

The aim of the presented study was to investigate the influence of the structure and ionic nature of polymers on the adsorption layer architecture.
CoFe2O4 and NiFe2O4@graphene adsorbents for heavy metal ions – kinetic and thermodynamic analysis
Authors: Santhosh Chella , Kollu Pratap , Felix Sathiyanathan , Velmurugan Venugopal , Jeong Soon Kwan , Grace Andrews Nirmala
Published: March 2015

Magnetic cobalt and nickel ferrites with graphene nanocomposites (GCF & GNF) were tested for removal of Pb2+ and Cd2+ ions. A highest adsorption was achieved for Pb2+viz. 142.8 and 111.1 mg g−1 and for Cd2+ 105.26 and 74.62 mg g−1 for GCF and GNF.
Iron(ii)-catalyzed asymmetric intramolecular olefin aminochlorination using chloride ion
Authors: Zhu Cheng-Liang , Tian Jun-Shan , Gu Zhen-Yuan , Xing Guo-Wen , Xu Hao
Published: March 2015

We report an iron-catalyzed asymmetric aminochlorination method for internal olefins; it tolerates valuable olefins that are incompatible with existing methods.
Single-ion dominantly conducting polyborates towards high performance electrolytes in lithium batteries
Authors: Qin Bingsheng , Liu Zhihong , Zheng Jie , Hu Pu , Ding Guoliang , Zhang Chuanjian , Zhao Jianghui , Kong Desheng , Cui Guanglei
Published: March 2015

The ionic transporting mechanism of single ion dominantly polyborate lithium salts and their superior performances.
Ru0.01Ti0.99Nb2O7 as an intercalation-type anode material with a large capacity and high rate performance for lithium-ion batteries
Authors: Lin Chunfu , Yu Shu , Wu Shunqing , Lin Shiwei , Zhu Zi-Zhong , Li Jianbao , Lu Li
Published: March 2015

Ru0.01Ti0.99Nb2O7, with a much larger capacity than Li4Ti5O12, fulfils the requirements of high power and energy density for electric vehicles.
Nonvolatile chlorinated additives adversely influence CH3NH3PbI3based planar solar cells
Authors: Chen Yani , Zhao Yixin , Liang Ziqi
Published: March 2015

Nonvolatile chlorinated additives can significantly improve the perovskite film morphology, yet adversely influencing CH3NH3PbI3based planar solar cells.
Improved environmental stability of organic lead trihalide perovskite-based photoactive-layers in the presence of mesoporous TiO2
Authors: O'Mahony Flannan T. F. , Lee Yong Hui , Jellett Cameron , Dmitrov Stoichko , Bryant Daniel T. J. , Durrant James R. , O'Regan Brian C. , Graetzel Michael , Nazeeruddin Mohammad K. , Haque Saif A.
Published: March 2015

Transient absorption spectroscopy is used to study the charge transfer processes in methyl ammonium lead triiodide based photoactive layers under ambient and inert conditions.
A facile fabrication of large-scale reduced graphene oxide–silver nanoparticle hybrid film as a highly active surface-enhanced Raman scattering substrate
Authors: Li Yang , Zhao Xiaojia , Zhang Panpan , Ning Jing , Li Jingfeng , Su Zhiqiang , Wei Gang
Published: March 2015

Larger-scale reduced graphene oxide–silver nanoparticle hybrid film can serve as a novel SERS-active substrate for detecting R6G and MA.
Mechanisms of biofilm inhibition and degradation by antimicrobial peptides
Authors: Segev-Zarko L. , Saar-Dover Ron , Brumfeld Vlad , Mangoni Maria Luisa , Shai Yechiel
Published: March 2015

Many bacteria live as biofilms to cope with unfavourable surroundings. Biofilms start from (i) a planktonic stage, (ii) initial adhesion to surfaces and (iii) formation of sessile micro-colonies that secrete extracellular polymeric substance (EPS), leading to bacterial resistance to antibiotics. Antimicrobial peptides (AMPs) are extensively studied with regard to planktonic bacteria but much less so with regard to biofilm formation. In the present study, we investigated how the above three steps are affected by the properties of the AMPs using a series of peptides composed of six lysines and nine leucines, which differ in their sequences and hence their biophysical properties. Treatment with bactericidal peptides at non-inhibitory concentrations resulted in reduced biofilm growth, for some starting from 25 nM which is 0.2 and 0.4% of their minimum inhibitory concentration (MIC 6.3 and 12.5 μM, respectively), continuing in a dose-dependent manner. We suggest that reduced bacterial adhesion to surfaces and decreased biofilm growth are due to the peptide's ability to coat either the biomaterial surface or the bacterium itself. Degradation of established biofilms by bactericidal and non-bactericidal peptides, within 1 h of incubation, occurs by either killing of embedded bacteria or detachment of live ones. In addition to shedding light on the mechanism of biofilm inhibition and degradation, these data may assist in the design of anti-biofilm AMPs.
Speech Recognition Across the Life Span: Longitudinal Changes From Middle-Age to Older Adults
Authors: Dubno Judy R.
Published: March 2015

Purpose

The purpose of this article is to provide an overview of evidence of age-related declines in speech recognition in middle age to older adulthood; to review contributions of pure-tone thresholds, age, and gender; and to report preliminary results from a longitudinal study.

Method

Pure-tone thresholds and word recognition in quiet and babble are being measured in a large sample of adults yearly or every 2 to 3 years. Analyses included >16,000 audiograms and speech recognition scores from >1,200 adults whose ages ranged from the 40s to the 90s. A multivariable generalized linear repeated mixed model assessed changes in thresholds and speech recognition over time.

Results

Word recognition in quiet declined significantly while controlling for threshold increases, and declines appeared to accelerate near ages 65 to 70 years. Scores for men were poorer than those for women even after controlling for gender differences in thresholds, but rates of decline did not differ by gender. Smaller declines in key word recognition in babble were observed, and declines appeared to accelerate near ages 75 to 80 years.

Conclusions

Additional evidence is needed from large-scale longitudinal cohort studies to determine rates of change of auditory function across the life span. These studies can identify associations with modifiable risk factors and potential mechanisms to reduce, to prevent, or to delay the onset of age-related hearing loss.
Chip implementation of high‐efficient light‐emitting diode dimming driver for high‐power light‐emitting diode lighting system
Authors: Hsia Shih‐Chang , Sheu Ming‐Hwa , Lai Sheng‐Yueh
Published: March 2015

This study presents a novel high‐power light‐emitting diode (LED) driver based on chip‐level design. We propose a multi‐level current approach to LED dimming, rather than pulsed current. The LED driving current can be controlled directly using a digital interface, making it more user‐friendly. An analysis of output impedance and driving current demonstrates how the driver can be realised on a single chip. A prototype chip was designed using the second generation TSMC 0.25 μm high‐voltage technology. The chip area, including I/O pads and power driver, is only 0.89 mm2. The proposed chip is able to drive a 60 W LED panel at maximum output by regulating current in 16 steps for LED dimming. Measurement results indicate that driving efficiency reaches 96% and lighting efficiency is 20% higher than that achieved using pulsed‐width modulation. Furthermore, the proposed chip is able to reduce interference, improve lighting efficiency, and prolong the lifespan of LED devices.
Interference suppression with flat gain constraint for satellite navigation systems
Authors: Wang Wenyi , Du Qingrong , Wu Renbiao , Liang Junli
Published: March 2015

Power minimisation approach is an effective interference suppression algorithm for satellite navigation systems. It forms automatically deep nulls in the direction‐of‐arrival (DOA) of interferences without prior information about the DOAs of satellite signals and interferences. However, it cannot provide flat gains for other directions. Thus, the desired satellite signals may be partly suppressed when they locate in the shallow nulls. By combining eigenvalue thresholding method and l1‐norm constraint, a new interference suppression algorithm is proposed for satellite navigation systems that would provide approximately flat gains in all directions except that of interferences. However, the l1‐norm constraint leads to a non‐smooth optimisation problem which cannot be solved by the conventional gradient‐based algorithm. After that, by utilising the proximal operator, an iterative algorithm is proposed. The simulations demonstrate the effectiveness of the proposed algorithm.
New records of Chironomidae (Diptera) of Tuvalu
Authors: Ueno Ryuhei , Satake Kiyoshi , Yamano Hiroya
Published: March 2015

Here we report the chironomid fauna of Tuvalu for the first time. Four species belonging to two subfamilies were collected on Fongafale Island. At least one species inhabited a freshwater environment. We describe male imagines of Compterosmittia longipalpis sp. n., Pseudosmittia tuvaluensis sp. n. and Pseudosmittia amplexivirga sp. n. We also describe the morphology of Chironomus sp. larvae inhabiting a wet taro swamp.
Food, substrate or both? Decomposition of reed leaves (Phragmites australis) by aquatic macroinvertebrates in a large shallow lake (Lake Balaton, Hungary)
Authors: Karádi-Kovács Kata , Selmeczy Géza Balázs , Padisák Judit , Schmera Dénes
Published: March 2015

The aim of this study was to investigate the use and decomposition of reed leaves (Phragmites australis) by aquatic macroinvertebrates in a lake environment (Lake Balaton, Hungary). Natural and artificial leaves were exposed to separate the use of leaves as substrate and as food at different vertical positions. Although we recorded a low density of macroinvertebrates, mixed-effect models showed that natural leaves were colonized by a higher number of taxa and individuals than artificial leaves. Moreover, indicator species analysis identified two detritivorous species (Dikerogammarus villosus and Asellus aquaticus) as indicators of natural leaves. The obtained results suggest that macroinvertebrates use the leaves of reed not only as substrate but also as food. Leaf decay experiment showed that macroinvertebrates contribute to 87.5% of the total leaf litter decay. Leaf bags positioned at the surface were found to host less individuals but the decay rate was faster. The vertical position did not have an impact on the number of taxa or taxa composition. According to these results, macroinvertebrates represent an important component of detritus-based food webs in reed-vegetated littoral areas of the lake.
Evaluation of hydrology, suspended sediment and Nickel loads in a small watershed in Basque Country (Northern Spain) using eco-hydrological SWAT model
Authors: Peraza-Castro M. , Ruiz-Romera E. , Montoya-Armenta L.H. , Sánchez-Pérez J.M. , Sauvage S.
Published: March 2015

Suspended sediment transportation and associated pollutants from catchment to stream networks are responsible for aquatic habitat degradation, reservoir sedimentation and the transportation of sediment bound pollutants. Quantifying suspended sediment loads from lands to watercourses is essential in controlling soil erosion and in implementing appropriate mitigation practices to reduce stream sediment and associated pollutant loads, and hence improve surface water quality downstream.The main objective of this study is to evaluate the temporal variability of hydrology, sediment and nickel loads using Soil and Water Assessment Tool in Oka watershed located in north Spain. Model simulation was completed using 11 years historical records (2001–2009 for validation and 2009–2012 for calibration) of streamflow and suspended sediment concentration (SSC). Thestreamflow, SSC and sediment load estimated from the model were compared with observed data using statistical parameters, which indicates a successful simulation. The annual production of simulated sediments shows variability between 662 and 1515 t, with a mean specific yield of 33 t km−2 y−1. The annual load of nickel simulated ranged from 32 to 72 kg, representing a mean specific of 1.63 kg km−2 year−1. The information obtained from this research is of interest to understand long term interannual variability of suspended sediment and nickel yield.
Description of spin–orbit coupling in excited states with two-component methods based on approximate coupled-cluster theory
Authors: Krause Katharina , Klopper Wim
Published: March 2015

A generalization of the approximated coupled-cluster singles and doubles method and the algebraic diagrammatic construction scheme up to second order to two-component spinors obtained from a relativistic Hartree–Fock calculation is reported. Computational results for zero-field splittings of atoms and monoatomic cations, triplet lifetimes of two organic molecules, and the spin-forbidden part of the UV/Vis absorption spectrum of tris(ethylenediamine)cobalt(III) are presented.
Rotation-vibration interactions in the spectra of polycyclic aromatic hydrocarbons: Quinoline as a test-case species
Authors: Pirali O. , Kisiel Z. , Goubet M. , Gruet S. , Martin-Drumel M. A. , Cuisset A. , Hindle F. , Mouret G.
Published: March 2015

Polycyclic aromatic hydrocarbons (PAHs) are highly relevant for astrophysics as possible, though controversial, carriers of the unidentified infrared emission bands that are observed in a number of different astronomical objects. In support of radio-astronomical observations, high resolution laboratory spectroscopy has already provided the rotational spectra in the vibrational ground state of several molecules of this type, although the rotational study of their dense infrared (IR) bands has only recently become possible using a limited number of experimental set-ups. To date, all of the rotationally resolved data have concerned unperturbed spectra. We presently report the results of a high resolution study of the three lowest vibrational states of quinoline C9H7N, an N-bearing naphthalene derivative. While the pure rotational ground state spectrum of quinoline is unperturbed, severe complications appear in the spectra of the ν45 and ν44 vibrational modes (located at about 168 cm−1 and 178 cm−1, respectively). In order to study these effects in detail, we employed three different and complementary experimental techniques: Fourier-transform microwave spectroscopy, millimeter-wave spectroscopy, and Fourier-transform far-infrared spectroscopy with a synchrotron radiation source. Due to the high density of states in the IR spectra of molecules as large as PAHs, perturbations in the rotational spectra of excited states should be ubiquitous. Our study identifies for the first time this effect and provides some insights into an appropriate treatment of such perturbations.
Context-invariant quasi hidden variable (qHV) modelling of all joint von Neumann measurements for an arbitrary Hilbert space
Authors: Loubenets Elena R.
Published: March 2015

We prove the existence for each Hilbert space of the two new quasi hidden variable (qHV) models, statistically noncontextual and context-invariant, reproducing all the von Neumann joint probabilities via non-negative values of real-valued measures and all the quantum product expectations—via the qHV (classical-like) average of the product of the corresponding random variables. In a context-invariant model, a quantum observable X can be represented by a variety of random variables satisfying the functional condition required in quantum foundations but each of these random variables equivalently models X under all joint von Neumann measurements, regardless of their contexts. The proved existence of this model negates the general opinion that, in terms of random variables, the Hilbert space description of all the joint von Neumann measurements for dimH≥3 can be reproduced only contextually. The existence of a statistically noncontextual qHV model, in particular, implies that every N-partite quantum state admits a local quasi hidden variable model introduced in Loubenets [J. Math. Phys. 53, 022201 (2012)]. The new results of the present paper point also to the generality of the quasi-classical probability model proposed in Loubenets [J. Phys. A: Math. Theor. 45, 185306 (2012)].
Ab initio O(N) elongation-counterpoise method for BSSE-corrected interaction energy analyses in biosystems
Authors: Orimoto Yuuichi , Yamamoto Ryohei , Xie Peng , Liu Kai , Imamura Akira , Aoki Yuriko
Published: March 2015

An Elongation-counterpoise (ELG-CP) method was developed for performing accurate and efficient interaction energy analysis and correcting the basis set superposition error (BSSE) in biosystems. The method was achieved by combining our developed ab initio O(N) elongation method with the conventional counterpoise method proposed for solving the BSSE problem. As a test, the ELG-CP method was applied to the analysis of the DNAs’ inter-strands interaction energies with respect to the alkylation-induced base pair mismatch phenomenon that causes a transition from G⋯C to A⋯T. It was found that the ELG-CP method showed high efficiency (nearly linear-scaling) and high accuracy with a negligibly small energy error in the total energy calculations (in the order of 10−7–10−8 hartree/atom) as compared with the conventional method during the counterpoise treatment. Furthermore, the magnitude of the BSSE was found to be ca. −290 kcal/mol for the calculation of a DNA model with 21 base pairs. This emphasizes the importance of BSSE correction when a limited size basis set is used to study the DNA models and compare small energy differences between them. In this work, we quantitatively estimated the inter-strands interaction energy for each possible step in the transition process from G⋯C to A⋯T by the ELG-CP method. It was found that the base pair replacement in the process only affects the interaction energy for a limited area around the mismatch position with a few adjacent base pairs. From the interaction energy point of view, our results showed that a base pair sliding mechanism possibly occurs after the alkylation of guanine to gain the maximum possible number of hydrogen bonds between the bases. In addition, the steps leading to the A⋯T replacement accompanied with replications were found to be unfavorable processes corresponding to ca. 10 kcal/mol loss in stabilization energy. The present study indicated that the ELG-CP method is promising for performing effective interaction energy analyses in biosystems.
Shape-independent model (SHIM) approach for studying aggregation by NMR diffusometry
Authors: Hernandez Santiago Adrian A. , Buchelnikov Anatoly S. , Rubinson Maria A. , Yesylevskyy Semen O. , Parkinson John A. , Evstigneev Maxim P.
Published: March 2015

NMR diffusometry has been gaining wide popularity in various areas of applied chemistry for investigating diffusion and complexation processes in solid and aqueous phases. To date, the application of this method to study aggregation phenomena proceeding beyond the dimer stage of assembly has been restricted by the need for a priori knowledge of the aggregates’ shape, commonly difficult to know in practice. We describe here a comprehensive analysis of aggregation parameter-dependency on the type and shape selected for modeling assembly processes, and report for the first time a shape-independent model (designated the SHIM approach), which may be used as an alternative in cases when information on aggregates’ shapes is unavailable. The model can be used for determining equilibrium aggregation parameters from self-diffusion NMR data including equilibrium self-association constant and changes in enthalpy, ΔH, and entropy, ΔS.
Ultrasonic power transfer from a spherical acoustic wave source to a free-free piezoelectric receiver: Modeling and experiment
Authors: Shahab S. , Gray M. , Erturk A.
Published: March 2015

Contactless powering of small electronic components has lately received growing attention for wireless applications in which battery replacement or tethered charging is undesired or simply impossible, and ambient energy harvesting is not a viable solution. As an alternative to well-studied methods of contactless energy transfer, such as the inductive coupling method, the use of ultrasonic waves transmitted and received by piezoelectric devices enables larger power transmission distances, which is critical especially for deep-implanted electronic devices. Moreover, energy transfer by means of acoustic waves is well suited in situations where no electromagnetic fields are allowed. The limited literature of ultrasonic acoustic energy transfer is mainly centered on proof-of-concept experiments demonstrating the feasibility of this method, lacking experimentally validated modeling efforts for the resulting multiphysics problem that couples the source and receiver dynamics with domain acoustics. In this work, we present fully coupled analytical, numerical, and experimental multiphysics investigations for ultrasonic acoustic energy transfer from a spherical wave source to a piezoelectric receiver bar that operates in the 33-mode of piezoelectricity. The fluid-loaded piezoelectric receiver under free-free mechanical boundary conditions is shunted to an electrical load for quantifying the electrical power output for a given acoustic source strength of the transmitter. The analytical acoustic-piezoelectric structure interaction modeling framework is validated experimentally, and the effects of system parameters are reported along with optimal electrical loading and frequency conditions of the receiver.
Solutes at the liquid:liquid phase boundary—Solubility and solvent conformational response alter interfacial microsolvation
Authors: Ghadar Yasaman , Parmar Payal , Samuels Alex C. , Clark Aurora E.
Published: March 2015

A detailed understanding of solvent structure and dynamics at liquid:liquid interfaces is a necessary precursor for control and manipulation of these phase boundaries. Experimentally, amphiphilic solutes are often used to alter transport properties across water:organic interfaces; however, a fundamental model for the mechanism of this action has not been determined. This work compares the solvation profiles of ampiphilic solutes that traverse the phase boundary in binary water:n-hexane, and the individual microsolvation processes for interfacial water and hexane molecules therein. Microsolvation is defined as the rare event where one solvent molecule temporarily penetrates the co-solvent phases and is fully solvated therein. The solutes tri-butyl phosphate (TBP), hydrogen di-butyl phosphate, and di-hydrogen mono-butyl phosphate have been examined as they exhibit a systematic increase in aqueous solubility and selectively partition to the interfacial region at the infinite dilution limit. The relationship between adopted configurations of the solute, orientation of the solvent, and the ability of the solute to enhance microsolvation, specifically the ability of n-hexane to penetrate the aqueous phase, is demonstrated within a 20 Å radius of TBP.
Preparation of state purified beams of He, Ne, C, N, and O atoms
Authors: Jankunas Justin , Reisyan Kevin S. , Osterwalder Andreas
Published: March 2015

The production and guiding of ground state and metastable C, N, and O atoms in a two-meter-long, bent magnetic guide are described. Pure beams of metastable He(3S1) and Ne(3P2), and of ground state N(4S3/2) and O(3P2) are obtained using an Even-Lavie valve paired with a dielectric barrier discharge or electron bombardment source. Under these conditions no electronically excited C, N, or O atoms are observed at the exit of the guide. A general valve with electron impact excitation creates, in addition to ground state atoms, electronically excited C(3P2; 1D2) and N(2D5/2; 2P3/2) species. The two experimental conditions are complimentary, demonstrating the usefulness of a magnetic guide in crossed or merged beam experiments such as those described in Henson et al. [Science 338, 234 (2012)] and Jankunas et al. [J. Chem. Phys. 140, 244302 (2014)].
Cross-circularly polarized two-exciton states in one to three dimensions
Authors: Ajiki Hiroshi
Published: March 2015

Biexciton and two-exciton dissociated states of Frenkel-type excitons are studied theoretically using an exciton tight-binding (TB) model including a polarization degree of freedom. Because the biexciton consists of two cross-circularly polarized excitons, an on-site interaction (V) between the two excitons should be considered in addition to a nearest-neighbor two-exciton attractive interaction (δ). Although there are an infinitely large number of combinations of V and δ providing the observed binding energy of a biexciton, the wave function of the biexciton and two-exciton dissociated states is nearly independent of these parameter sets. This means that all the two-exciton states are uniquely determined from the exciton TB model. There are a spatially symmetric and an antisymmetric biexciton state for a one-dimensional (1D) lattice and two symmetric and one antisymmetric biexciton states at most for two- (2D) and three-dimensional (3D) lattices. In contrast, when the polarization degree of freedom is ignored, there is one biexciton state for 1D, 2D, and 3D lattices. For this study, a rapid and memory-saving calculation method for two-exciton states is extended to include the polarization degree of freedom.
Cylindrical radial superlattice conductors for low loss microwave components
Authors: Rahimi Arian , Wu Jiyu , Cheng Xiaoyu , Yoon Yong-Kyu ‘YK’
Published: March 2015

Theory and experimental demonstration of a cylindrical radial superlattice (CRS) conductor composed of alternating nanoscopic non-ferromagnetic/ferromagnetic metal layers are presented with focus on low conductor loss in a K-band microwave spectrum. The dynamic frequency response of the ferromagnetic thin films has been extracted using the Landau-Lifshitz-Gilbert equation which shows a negative magnetic permeability value in the frequencies above its ferromagnetic resonance. The reduction of the conductor loss results from the eddy current canceling (ECC) effect in the CRS conductors, where the negative-permeability ferromagnetic and positive-permeability non-ferromagnetic metal layers produce a zero effective permeability, resulting in virtually infinite skin depth at the targeted frequency. The closed and uniform boundary conditions inherent in the radial shape conductors preclude discontinuity effects occurring at the edges of the planar superlattice conductor and end up with a more effective ECC effect in practice. The design aspects with regards to the CRS materials and structural configuration are discussed. Simulations using a full-wave finite element method high frequency structure simulator are performed to show the ECC effect inside the CRS conductors. An air-lifted inductor made of the CRS conductor has been implemented to prove the effectiveness of the conductor loss reduction with the CRS conductor. The inductor shows an inductance value of 1–2 nH and a Q-factor of 45 at 18 GHz, which is the highest value reported at the frequency by now.
Field dependent thermoelectric properties of organic semiconductors—A tool to determine the nature of charge transport in materials exhibiting thermally activated transport
Authors: Mendels Dan , Tessler Nir
Published: March 2015

By implementing Monte Carlo simulations and employing the concept of effective temperature, we explore the effects of an applied field bias on the charge carrier statistics and Peltier coefficient in hopping systems subject to the parameter range applicable to disordered organic semiconductors. Distinct differences are found between the observed field dependences as obtained from systems in which energetic disorder is spatially correlated and those in which it is not. Considerable differences are also found between the charge carrier statistics and the Peltier coefficient's field dependence in systems in which charge is transported by bare charge carriers and systems in which it is propagated by polarons. Peltier coefficient field dependence investigations are, hence, proposed as a new tool for studying charge transport and thermoelectricity in disordered organic semiconductors and systems which exhibit thermally activated transport in general.
Charge transport in amorphous Hf0.5Zr0.5O2
Authors: Islamov D. R. , Perevalov T. V. , Gritsenko V. A. , Cheng C. H. , Chin A.
Published: March 2015

In this study, we demonstrated experimentally and theoretically that the charge transport mechanism in amorphous Hf0.5Zr0.5O2 is phonon-assisted tunneling between traps like in HfO2 and ZrO2. The thermal trap energy of 1.25 eV and optical trap energy of 2.5 eV in Hf0.5Zr0.5O2 were determined based on comparison of experimental data on transport with different theories of charge transfer in dielectrics. A hypothesis that oxygen vacancies are responsible for the charge transport in Hf0.5Zr0.5O2 was discussed.
Dynamics of neutrals and ions in an ultrafast laser produced Zn plasma
Authors: Smijesh N. , Rao Kavya H. , Philip Reji
Published: March 2015

Optical time of flight dynamics of neutrals and ions in an ultrafast laser produced zinc plasma generated by irradiating a solid zinc target using 100 fs laser pulses is investigated. An acceleration of ions is observed which arises from internal Coulomb forces acting between charged species in the plasma. Some of the fast ions recombine with electrons in the plasma and generate fast neutrals. Plasma plume imaging performed at various ambient pressures indicates adiabatic expansion at lower pressures and plume front deceleration at higher pressures: at lower pressures the plume front-time (R-t) plot displays a linear expansion, shock wave model fits to the data at 5 Torr and at higher pressures the data fits better to the drag model. Furthermore, around an intermediate pressure of 10 Torr, the R-t plot fits to the shock wave model at earlier stages of plasma expansion, while it fits to the drag model at the later stages. These investigations provide relevant information on the acceleration of ions and neutrals in an expanding zinc plasma plume produced by ultrafast laser pulses.
Linking the micro and macro: L-H transition dynamics and threshold physics
Authors: Malkov M. A. , Diamond P. H. , Miki K. , Rice J. E. , Tynan G. R.
Published: March 2015

The links between the microscopic dynamics and macroscopic threshold physics of the L → H transition are elucidated. Emphasis is placed on understanding the physics of power threshold scalings, and especially on understanding the minimum in the power threshold as a function of density Pthr (n). By extending a numerical 1D model to evolve both electron and ion temperatures, including collisional coupling, we find that the decrease in Pthr (n) along the low-density branch is due to the combination of an increase in collisional electron-to-ion energy transfer and an increase in the heating fraction coupled to the ions. Both processes strengthen the edge diamagnetic electric field needed to lock in the mean electric field shear for the L→H transition. The increase in Pthr (n) along the high-density branch is due to the increase with ion collisionality of damping of turbulence-driven shear flows. Turbulence driven shear flows are needed to trigger the transition by extracting energy from the turbulence. Thus, we identify the critical transition physics components of the separatrix ion heat flux and the zonal flow excitation. The model reveals a power threshold minimum in density scans as a crossover between the threshold decrease supported by an increase in heat fraction received by ions (directly or indirectly, from electrons) and a threshold increase, supported by the rise in shear flow damping. The electron/ion heating mix emerges as important to the transition, in that it, together with electron-ion coupling, regulates the edge diamagnetic electric field shear. The importance of possible collisionless electron-ion heat transfer processes is explained.
Gate controlled electronic transport in monolayer MoS2 field effect transistor
Authors: Zhou Y. F. , Xian H. M. , Wang B. , Yu Y. J. , Wei Y. D. , Wang J.
Published: March 2015

The electronic spin and valley transport properties of a monolayer MoS2 are investigated using the non-equilibrium Green's function formalism combined with density functional theory. Due to the presence of strong Rashba spin orbit interaction (RSOI), the electronic valence bands of monolayer MoS2 are split into spin up and spin down Zeeman-like texture near the two inequivalent vertices K and K′ of the first Brillouin zone. When the gate voltage is applied in the scattering region, an additional strong RSOI is induced which generates an effective magnetic field. As a result, electron spin precession occurs along the effective magnetic field, which is controlled by the gate voltage. This, in turn, causes the oscillation of conductance as a function of the magnitude of the gate voltage and the length of the gate region. This current modulation due to the spin precession shows the essential feature of the long sought Datta-Das field effect transistor (FET). From our results, the oscillation periods for the gate voltage and gate length are found to be approximately 2.2 V and 20.03aB (aB is Bohr radius), respectively. These observations can be understood by a simple spin precessing model and indicate that the electron behaviors in monolayer MoS2 FET are both spin and valley related and can easily be controlled by the gate.
Charge trapping at the MoS2-SiO2 interface and its effects on the characteristics of MoS2 metal-oxide-semiconductor field effect transistors
Authors: Guo Yao , Wei Xianlong , Shu Jiapei , Liu Bo , Yin Jianbo , Guan Changrong , Han Yuxiang , Gao Song , Chen Qing
Published: March 2015

The field effect transistors (FETs) based on thin layer MoS2 often have large hysteresis and unstable threshold voltage in their transfer curves, mainly due to the charge trapping at the oxide-semiconductor interface. In this paper, the charge trapping and de-trapping processes at the SiO2-MoS2 interface are studied. The trapping charge density and time constant at different temperatures are extracted. Making use of the trapped charges, the threshold voltage of the MoS2 based metal-oxide-semiconductor FETs is adjusted from 4 V to −45 V. Furthermore, the impact of the trapped charges on the carrier transport is evaluated. The trapped charges are suggested to give rise to the unscreened Coulomb scattering and/or the variable range hopping in the carrier transport of the MoS2 sheet.
Statistical variability study of random dopant fluctuation on gate-all-around inversion-mode silicon nanowire field-effect transistors
Authors: Yoon Jun-Sik , Rim Taiuk , Kim Jungsik , Kim Kihyun , Baek Chang-Ki , Jeong Yoon-Ha
Published: March 2015

Random dopant fluctuation effects of gate-all-around inversion-mode silicon nanowire field-effect transistors (FETs) with different diameters and extension lengths are investigated. The nanowire FETs with smaller diameter and longer extension length reduce average values and variations of subthreshold swing and drain-induced barrier lowering, thus improving short channel immunity. Relative variations of the drain currents increase as the diameter decreases because of decreased current drivability from narrower channel cross-sections. Absolute variations of the drain currents decrease critically as the extension length increases due to decreasing the number of arsenic dopants penetrating into the channel region. To understand variability origins of the drain currents, variations of source/drain series resistance and low-field mobility are investigated. All these two parameters affect the variations of the drain currents concurrently. The nanowire FETs having extension lengths sufficient to prevent dopant penetration into the channel regions and maintaining relatively large cross-sections are suggested to achieve suitable short channel immunity and small variations of the drain currents.