bluuebunny/crossref_metadata_2025 huggingface dataset:
Evaluation of voltage-dependent calcium channel γ gene families identified several novel potential susceptible genes to schizophrenia
Authors: Guan Fanglin , Zhang Tianxiao , Liu Xinshe , Han Wei , Lin Huali , Li Lu , Chen Gang , Li Tao
Published: April 2016

Voltage-gated L-type calcium channels (VLCC) are distributed widely throughout the brain. Among the genes involved in schizophrenia (SCZ), genes encoding VLCC subunits have attracted widespread attention. Among the four subunits comprising the VLCC (α − 1, α −2/δ, β and γ), the γ subunit that comprises an eight-member protein family is the least well understood. In our study, to further investigate the risk susceptibility by the γ subunit gene family to SCZ, we conducted a large-scale association study in Han Chinese individuals. The SNP rs17645023 located in the intergenic region of CACNG4 and CACNG5 was identified to be significantly associated with SCZ (OR = 0.856, P = 5.43 × 10−5). Similar results were obtained in the meta-analysis with the current SCZ PGC data (OR = 0.8853). We also identified a two-SNP haplotype (rs10420331-rs11084307, P = 1.4 × 10−6) covering the intronic region of CACNG8 to be significantly associated with SCZ. Epistasis analyses were conducted and significant statistical interaction (OR = 0.622, P = 2.93 × 10−6, Pperm < 0.001) was observed between rs192808 (CACNG6) and rs2048137 (CACNG5). Our results indicate that CACNG4, CACNG5, CACNG6 and CACNG8 may contribute to the risk of SCZ. The statistical epistasis identified between CACNG5 and CACNG6 suggests that there may be an underlying biological interaction between the two genes.
Metabolomic Profiling of Infectious Parapneumonic Effusions Reveals Biomarkers for Guiding Management of Children with Streptococcus pneumoniae Pneumonia
Authors: Chiu Chih-Yung , Lin Gigin , Cheng Mei-Ling , Chiang Meng-Han , Tsai Ming-Han , Lai Shen-Hao , Wong Kin-Sun , Hsieh Sen-Yung
Published: April 2016

Metabolic markers in biofluids represent an attractive tool for guiding clinical management. The aim of this study was to identify metabolic mechanisms during the progress of pleural infection in children with Streptococcus pneumoniae pneumonia. Forty children diagnosed with pneumococcal pneumonia were enrolled and analysis of pleural fluid metabolites categorized by complicated parapneumonic effusions (CPE) and non-CPE was assessed by using 1H-NMR spectroscopy. Multivariate statistical analysis including principal components analysis (PCA) and partial least-squares discriminant analysis (PLS-DA) were performed. Metabolites identified were studied in relation to subsequent intervention procedures by receiver operating characteristic (ROC) curve analysis. Ten metabolites significantly different between CPE and non-CPE were identified. A significantly lower level of glucose for glycolysis was found in CPE compared to non-CPE. Six metabolites involving bacterial biosynthesis and three metabolites involving bacterial fermentation were significantly higher in CPE compared to non-CPE. Glucose and 3-hydroxybutyric acid were the metabolites found to be useful in discriminating from receiving intervention procedures. Metabolic profiling of pleural fluid using 1H-NMR spectroscopy provides direct observation of bacterial metabolism in the progress of pneumococcal pneumonia. An increase in the metabolism of butyric acid fermentation of glucose could potentially lead to the need of aggressive pleural drainage.
Noise and the Perceptual Filling-in effect
Authors: Zomet Ativ , Polat Uri , Levi Dennis M.
Published: April 2016

Nearby collinear flankers increase the false alarm rate (reports of the target being present when it is not) in a Yes-No experiment. This effect has been attributed to “filling-in” of the target location due to increased activity induced by the flankers. According to signal detection theory, false alarms are attributed to noise in the visual nervous system. Here we investigated the effect of external noise on the filling-in effect by adding white noise to a low contrast Gabor target presented between two collinear Gabor flankers at a range of target-flanker separations. External noise modulates the filling-in effect, reducing visual sensitivity (d′) and increasing the filling-in effect (False Alarm rate). We estimated the amount of external noise at which the false alarm rate increases by the √2 (which we refer to as NFA). Across flank distances, both the false alarm rate and d′ (with no external noise) are correlated with NFA. These results are consistent with the notion that nearby collinear flankers add both signal and noise to the target location. The increased signal results in higher d′ values; the increased noise to higher false alarm rates (the filling effect).
Aortic Arch Calcification Predicts Patency Loss of Arteriovenous Fistula in End-Stage Renal Disease Patients
Authors: Yap Yit-Sheung , Ting Kai-Ting , Chi Wen-Che , Lin Cheng-Hao , Liu Yi-Chun , Chuang Wan-Long
Published: April 2016

Aortic arch calcification (AAC) is recognized as an important cardiovascular risk factor in patients with end-stage renal disease (ESRD). The aim of the study was to evaluate the impact of AAC grade on patency rates of arteriovenous fistula (AVF) in this specific population. The data of 286 ESRD patients who had an initial AVF placed were reviewed. The extent of AAC identified on chest radiography was divided into four grades (0–3). The association between AAC grade, other clinical factors, and primary patency of AVF was then analyzed by Cox proportional hazard analysis. The multivariate analysis demonstrated that the presence of AAC grade 2 (hazard ratio (95% confidence interval): 1.80 (1.15–2.84); p = 0.011) and grade 3 (3.03 (1.88–4.91); p < 0.001), and higher level of intact-parathyroid hormone (p = 0.047) were associated with primary patency loss of AVF. In subgroup analysis, which included AVF created by a surgeon assisted with preoperative vascular mapping, only AAC grade 3 (2.41 (1.45–4.00); p = 0.001), and higher intact-parathyroid hormone (p = 0.025) level were correlated with AVF patency loss. In conclusion, higher AAC grade and intact-parathyroid hormone level predicted primary patency loss of AVF in an ESRD population.
Systematic Analysis of Adverse Event Reports for Sex Differences in Adverse Drug Events
Authors: Yu Yue , Chen Jun , Li Dingcheng , Wang Liwei , Wang Wei , Liu Hongfang
Published: April 2016

Increasing evidence has shown that sex differences exist in Adverse Drug Events (ADEs). Identifying those sex differences in ADEs could reduce the experience of ADEs for patients and could be conducive to the development of personalized medicine. In this study, we analyzed a normalized US Food and Drug Administration Adverse Event Reporting System (FAERS). Chi-squared test was conducted to discover which treatment regimens or drugs had sex differences in adverse events. Moreover, reporting odds ratio (ROR) and P value were calculated to quantify the signals of sex differences for specific drug-event combinations. Logistic regression was applied to remove the confounding effect from the baseline sex difference of the events. We detected among 668 drugs of the most frequent 20 treatment regimens in the United States, 307 drugs have sex differences in ADEs. In addition, we identified 736 unique drug-event combinations with significant sex differences. After removing the confounding effect from the baseline sex difference of the events, there are 266 combinations remained. Drug labels or previous studies verified some of them while others warrant further investigation.
Comment on ‘A photoelectron spectroscopy study of lava stones’ by D. A. Cristaldi, C. G. Fortuna and A. Gulino, Anal. Methods, 2013, 5, 3458
Authors: Nicoletti Alessandra , Zappia Mario
Published: April 2016

Exposure to high levels of manganese can cause a form of parkinsonism known as manganism. A higher concentration of MnOOH species on the surface of lapilli from Mount Etna likely results in a high concentration of Mn in groundwater from Etna wells. A possible increased local risk of manganism has been hypothesized. Photograph © Salvatore Giammanco.
Benzoic hydroxamate-based iron complexes as model compounds for humic substances: synthesis, characterization and algal growth experiments
Authors: Orlowska Ewelina , Roller Alexander , Wiesinger Hubert , Pignitter Marc , Jirsa Franz , Krachler Regina , Kandioller Wolfgang , Keppler Bernhard K.
Published: April 2016

Benzoic hydroxamate-based monomeric and dimeric Fe(iii) complexes has been investigated as humic acid models. The stability in pure water and seawater was monitored and the ability to release iron has been examined with the algae feeding trials.
Highly stable SERS pH nanoprobes produced by co-solvent controlled AuNP aggregation
Authors: Wei Haoran , Willner Marjorie R. , Marr Linsey C. , Vikesland Peter J.
Published: April 2016

Production of gold nanoparticle (AuNP) surface-enhanced Raman spectroscopy (SERS) nanoprobes requires replicable aggregation to produce multimers with high signal intensity.
Multiwalled carbon nanotubes–poly(vinyl alcohol) composite cryogel used in microcolumn liquid chromatography to separate various herbicides
Authors: Siritham C. , Thammakhet C. , Thavarungkul P. , Kanatharana P.
Published: April 2016

A simple liquid chromatography system using a MWCNTs–PVA composite cryogel microcolumn was successfully developed for the separation of herbicides.
Transition metal-free generation of the acceptor/acceptor-carbene via α-elimination: synthesis of fluoroacetyl cyclopropanes
Authors: Wang Yongdong , Han Jing , Chen Jie , Cao Weiguo
Published: April 2016

An efficient transition metal-free approach for the generation of acceptor/acceptor-carbene followed by trapping with alkenes to provide fluoroacetyl cyclopropanes has been described. The resulting cyclopropanes could be further converted into the fluoromethyl dihydrofurans or fluorodihydropyrroles through ring-expansion processes.
The methyl- and aza-substituent effects on nonradiative decay mechanisms of uracil in water: a transient absorption study in the UV region
Authors: Hua XinZhong , Hua LinQiang , Liu XiaoJun
Published: April 2016

The C5, C6 methyl- and aza-substituent effects on the decay mechanism of uracil and vibrational cooling dynamics are investigated using a continuous UV probe.
Identification of effective exciton–exciton annihilation in squaraine–squaraine copolymers
Authors: Hader Kilian , May Volkhard , Lambert Christoph , Engel Volker
Published: April 2016

Within a microscopic model, exciton annihilation processes in squaraine–squaraine copolymers are identified and the unusual time-dependence of transient absorption time traces is explained.
Energy redistribution dynamics in triarylamine–triarylborane containing hexaarylbenzenes
Authors: Steeger M. , Holzapfel M. , Schmiedel A. , Lambert C.
Published: April 2016

Hexaarylbenzenes with triarylamine donors and triarylborane acceptors show rapid energy transfer (∼3 ps) as proved by pump–probe spectroscopy with fs-time resolution.
Electrosynthesis of diphenyl carbonate by homogeneous Pd electrocatalysts using Au nanoparticles on graphene as efficient anodes
Authors: Kanega Ryoichi , Ogihara Hitoshi , Yamanaka Ichiro
Published: April 2016

Electrochemical carbonylation of phenol (PhOH) with CO (1 atm) to form diphenyl carbonate (DPC) was studied by using a Pd-(in situ NHC) electrocatalyst and graphene-supported Au nanoparticle (Au NPs/GR) anodes.
A substrate-binding-state mimic of H2O2-dependent cytochrome P450 produced by one-point mutagenesis and peroxygenation of non-native substrates
Authors: Shoji Osami , Fujishiro Takashi , Nishio Kousuke , Kano Yukiko , Kimoto Hiroshi , Chien Shih-Cheng , Onoda Hiroki , Muramatsu Atsushi , Tanaka Shota , Hori Ayumi , Sugimoto Hiroshi , Shiro Yoshitsugu , Watanabe Yoshihito
Published: April 2016

H2O2-dependent cytochrome P450s that can catalyze monooxygenation of nonnative substrates were constructed by one-point mutagenesis.
Enhanced field emission properties of ZnO–Ag2S core–shell heterojunction nanowires
Authors: Wang Guojing , Li Mingyang , Chen Chienhua , Lv Shasha , Liao Jiecui , Li Zhengcao
Published: April 2016

A simple approach to Ag2S quantum dot modification was used to tune the field emission properties of ZnO nanowire arrays.
Expanding the family of bis-cyclometalated chiral-at-metal rhodium(iii) catalysts with a benzothiazole derivative
Authors: Ma Jiajia , Shen Xiaodong , Harms Klaus , Meggers Eric
Published: April 2016

An auxiliary-mediated synthesis provides a new chiral-at-metal rhodium(iii) complex in an enantiomerically pure fashion, which serves as an excellent chiral Lewis acid catalyst.
From near hard spheres to colloidal surfboards
Authors: Palangetic Ljiljana , Feldman Kirill , Schaller Raphael , Kalt Romana , Caseri Walter R. , Vermant Jan
Published: April 2016

This work revisits the synthesis of the colloidal particles most commonly used for making model near hard suspensions or as building blocks of model colloidal gels, i.e. sterically stabilised poly(methyl methacrylate) (PMMA) particles. The synthesis of these particles is notoriously hard to control and generally the problems are ascribed to the difficulty in synthesising the graft stabiliser (PMMA-g-PHSA). In the present work, it is shown that for improving the reliability of the synthesis as a whole, control over the polycondensation of the 12-polyhydroxystearic acid is the key. By changing the catalyst and performing the polycondensation in the melt, the chain length of the 12-polyhydroxystearic acid is better controlled, as confirmed by 1H-NMR spectroscopy. Control over the graft copolymer now enables us to make small variations of near hard sphere colloids, for example spherical PMMA particles with essentially the same core size and different stabilising layer thicknesses can now be readily produced, imparting controlled particle softness. The PMMA spheres can be further employed to create, in gram scale quantities, colloidal building blocks having geometrical and/or chemical anisotropy by using a range of mechanical deformation methods. The versatility of the latter methods is demonstrated for polystyrene latex particles as well.
A tyrosine-reactive irreversible inhibitor for glutathione S-transferase Pi (GSTP1)
Authors: Crawford L. A. , Weerapana E.
Published: April 2016

GlutathioneS-transferase Pi (GSTP1) mediates cellular defense against reactive electrophiles.
Structural features of mildly fractionated lignin carbohydrate complexes (LCC) from spruce
Authors: Giummarella Nicola , Zhang Liming , Henriksson Gunnar , Lawoko Martin
Published: April 2016

Characterization of novel lignin carbohydrate complexes (LCC) unveils structural differences of relevance to fundamental and applied science.
Performance of FTO-free conductive graphene-based counter electrodes for dye-sensitized solar cells
Authors: Pang Beili , Dong Lifeng , Ma Shuai , Dong Hongzhou , Yu Liyan
Published: April 2016

Network structure graphene is used as an efficient counter electrode for DSSCs which is made from modified graphene after UV irradiation. The DSSCs with FTO-free graphene-based counter electrode exhibit an energy conversion efficiency of 9.33%.
Effect of metal alloying on morphology and catalytic activity of platinum-based nanostructured thin films in methanol oxidation reaction
Authors: Hoseini S. Jafar , Bahrami Mehrangiz , Zanganeh Mahboobeh , Roushani Mahmoud , Rashidi Mehdi
Published: April 2016

In this paper, alloy thin films with a high degree of alloying were synthesized through a liquid–liquid interface method showing remarkable electrocatalytic activity for the methanol oxidation reaction.
Engineering the microstructure of milk fat by blending binary and ternary mixtures of its fractions
Authors: Ramel Pere R. , Marangoni Alejandro G.
Published: April 2016

The microstructure and crystallization kinetics of binary and ternary mixtures of milk fat fractions during isothermal crystallization at 5, 15, and 20 °C were characterized using polarized light microscopy and the Avrami model.
A N,N′-dioxide/Mg(OTf)2 complex catalyzed enantioselective α-addition of isocyanides to alkylidene malonates
Authors: Luo Weiwei , Yuan Xiao , Lin Lili , Zhou Pengfei , Liu Xiaohua , Feng Xiaoming
Published: April 2016

A simple and efficient catalytic asymmetric α-addition of isocyanides to alkylidene malonates was realized using a chiral N,N′-dioxide/MgII catalyst. A variety of 2-alkyl-5-aminoxazoles were obtained in up to 99% yield and 96% ee, and could be converted to imides and dipeptides.
AKAP18:PKA-RIIα structure reveals crucial anchor points for recognition of regulatory subunits of PKA
Authors: Götz Frank , Roske Yvette , Schulz Maike Svenja , Autenrieth Karolin , Bertinetti Daniela , Faelber Katja , Zühlke Kerstin , Kreuchwig Annika , Kennedy Eileen J. , Krause Gerd , Daumke Oliver , Herberg Friedrich W. , Heinemann Udo , Klussmann Enno
Published: April 2016

A-kinase anchoring proteins (AKAPs) interact with the dimerization/docking (D/D) domains of regulatory subunits of the ubiquitous protein kinase A (PKA). AKAPs tether PKA to defined cellular compartments establishing distinct pools to increase the specificity of PKA signalling. Here, we elucidated the structure of an extended PKA-binding domain of AKAP18β bound to the D/D domain of the regulatory RIIα subunits of PKA. We identified three hydrophilic anchor points in AKAP18β outside the core PKA-binding domain, which mediate contacts with the D/D domain. Such anchor points are conserved within AKAPs that bind regulatory RII subunits of PKA. We derived a different set of anchor points in AKAPs binding regulatory RI subunits of PKA. In vitro and cell-based experiments confirm the relevance of these sites for the interaction of RII subunits with AKAP18 and of RI subunits with the RI-specific smAKAP. Thus we report a novel mechanism governing interactions of AKAPs with PKA. The sequence specificity of each AKAP around the anchor points and the requirement of these points for the tight binding of PKA allow the development of selective inhibitors to unequivocally ascribe cellular functions to the AKAP18-PKA and other AKAP-PKA interactions.
Colchicine therapy in acute coronary syndrome patients acts on caspase-1 to suppress NLRP3 inflammasome monocyte activation
Authors: Robertson Stacy , Martínez Gonzalo J. , Payet Cloe A. , Barraclough Jennifer Y. , Celermajer David S. , Bursill Christina , Patel Sanjay
Published: April 2016

Inflammasome activation, with subsequent release of pro-inflammatory cytokines interleukin-1β (IL-1β) and IL-18, has recently been implicated in atherosclerosis-associated inflammation. This study aims to assess in acute coronary syndrome (ACS) patients (1) inflammasome activation in circulating monocytes and (2) whether short-term oral colchicine, a recognized anti-inflammatory agent that has been shown to be cardio-protective in clinical studies, might acutely suppress inflammasome-dependent inflammation. ACS patients (n=21) were randomized to oral colchicine (1 mg followed by 0.5 mg 1 h later) or no treatment, and compared with untreated healthy controls (n=9). Peripheral venous blood was sampled pre- (day 1) and 24 h post- (day 2) treatment. Monocytes were cultured and stimulated with ATP. Analysis of key inflammasome markers was performed by ELISA. IL-1β secretion increased by 580.4% (P<0.01) in ACS patients compared with controls but only with ATP stimulation. Untreated ACS patients secreted significantly higher levels of IL-18 compared with healthy controls independent of ATP stimulation (P<0.05). Colchicine treatment in ACS patients markedly reduced intracellular and secreted levels of IL-1β compared with pre-treatment levels (P<0.05 for both), as well as significantly reducing pro-caspase-1 mRNA levels by 57.7% and secreted caspase-1 protein levels by 30.2% compared with untreated patients (P<0.05 for both). Monocytes from ACS patients are ‘primed’ to secrete inflammasome-related cytokines and short-term colchicine acutely and markedly suppresses monocyte caspase-1 activity, thereby reducing monocyte secretion of IL-1β.
Parameter‐adaptive nighttime image enhancement with multi‐scale decomposition
Authors: Wang Shuhang , Zheng Jin , Li Bo
Published: April 2016

As a challenging problem, image enhancement plays an important role in computer vision applications and has been widely studied. As one of the most difficult issues of image enhancement, outdoor nighttime image enhancement suffers from noise amplification easily. To solve this problem, this study proposes a parameter‐adaptive nighttime image enhancement method with multi‐scale decomposition. The main contributions of this work are threefold. First, the authors find out that noises in different scales are various, and their method decomposes an input image into three high‐frequency layers and a background layer accordingly. Second, the authors’ method enhances each high‐frequency layer using adaptive parameters based on the characteristics of noises. Third, the proposed method maps the background layer to make it suitable to present details. Experiment results demonstrate that the proposed method can suppress noises as well as improve details effectively.
Compact wideband circularly polarised resonant cavity antenna using a single dielectric superstrate
Authors: Hung Tran Huy , Park Ikmo
Published: April 2016

A wideband resonant cavity antenna (RCA) with circular polarisation (CP) and high‐gain characteristics is presented. A crossed bowtie dipole is used as a primary wideband CP radiator for the RCA. A half‐wavelength planar partially reflecting surface is utilised to achieve high‐gain broadside radiation and wide axial ratio (AR) as well as gain bandwidths. The final design yields measured −10 dB impedance and 3 dB AR bandwidths ranging from 5.6 to 8.4 GHz and from 6.3 to 8.15 GHz, respectively. Experimental results also showed an average gain of 14.5 dBic over the CP operating bandwidth and a 3 dB gain bandwidth of 42.7% (5.7–8.8 GHz).
Analytical geolocation and three‐dimensional localisation by time difference of arrival
Authors: Naus Henricus Wilhelmus Léon
Published: April 2016

Geolocation based on time differences of arrival measured by three sensors is studied. Closed‐form analytical solutions are derived, even for the cases where one or more sensors are not located on the earth. Exploiting four sensors, full three‐dimensional localisation is achieved as well. These numbers of sensors are minimal. The analytical results have been implemented in algorithms and tested by Monte Carlo simulations. The results are unbiased and comply with the theoretical Cramer–Rao lower bound.
Polarization charge: Theory and applications to aqueous interfaces
Authors: Shi Bobo , Agnihotri Mithila V. , Chen Si-Han , Black Richie , Singer Sherwin J.
Published: April 2016

When an electric field is applied across an interface, a dielectric will acquire a polarization charge layer, assumed infinitely thin in the theory of macroscopic dielectrics and also in most treatments of electrokinetic phenomena in nanoscale structures. In this work we explore the polarization charge layer in molecular detail. Various formal relations and a linear response theory for the polarization charge are presented. Properties of the polarization charge layer are studied for three aqueous interfaces: air-water, a crystalline silica surface with water, and an amorphous silica surface with water. The polarization charge is calculated from equilibrium simulations via linear response theory and from non-equilibrium simulations, and the results are within statistical error. The polarization charge is found to be distributed within a region whose width is on the order of a nanometer.
Time-optimal excitation of maximum quantum coherence: Physical limits and pulse sequences
Authors: Köcher S. S. , Heydenreich T. , Zhang Y. , Reddy G. N. M. , Caldarelli S. , Yuan H. , Glaser S. J.
Published: April 2016

Here we study the optimum efficiency of the excitation of maximum quantum (MaxQ) coherence using analytical and numerical methods based on optimal control theory. The theoretical limit of the achievable MaxQ amplitude and the minimum time to achieve this limit are explored for a set of model systems consisting of up to five coupled spins. In addition to arbitrary pulse shapes, two simple pulse sequence families of practical interest are considered in the optimizations. Compared to conventional approaches, substantial gains were found both in terms of the achieved MaxQ amplitude and in pulse sequence durations. For a model system, theoretically predicted gains of a factor of three compared to the conventional pulse sequence were experimentally demonstrated. Motivated by the numerical results, also two novel analytical transfer schemes were found: Compared to conventional approaches based on non-selective pulses and delays, double-quantum coherence in two-spin systems can be created twice as fast using isotropic mixing and hard spin-selective pulses. Also it is proved that in a chain of three weakly coupled spins with the same coupling constants, triple-quantum coherence can be created in a time-optimal fashion using so-called geodesic pulses.
Measurement of the thermoelectric power factor of films over the 10-400 K range
Authors: Hossain Mohammad Abir , Alaie Seyedhamidreza , Tehrani Mehran
Published: April 2016

The design and development of a novel apparatus for the simultaneous measurement of electrical resistivity and Seebeck coefficient of films is reported here. Mounting stage is integrated inside a cryostat chamber enabling measurements over the 10-400 K temperature range, intended for organic thermoelectrics. Finite element method was used to analyze the thermo-mechanical response of the sample holder. The apparatus was validated against high purity nickel film, and a very good agreement was found.
Dual chain perturbation theory: A new equation of state for polyatomic molecules
Authors: Marshall Bennett D.
Published: April 2016

In the development of equations of state for polyatomic molecules, thermodynamic perturbation theory (TPT) is widely used to calculate the change in free energy due to chain formation. TPT is a simplification of a more general and exact multi-density cluster expansion for associating fluids. In TPT, all contributions to the cluster expansion which contain chain–chain interactions are neglected. That is, all inter-chain interactions are treated at the reference fluid level. This allows for the summation of the cluster theory in terms of reference system correlation functions only. The resulting theory has been shown to be accurate and has been widely employed as the basis of many engineering equations of state. While highly successful, TPT has many handicaps which result from the neglect of chain–chain contributions. The subject of this document is to move beyond the limitations of TPT and include chain–chain contributions to the equation of state.
Contributed Review: A review of the investigation of rare-earth dopant profiles in optical fibers
Authors: Sidiroglou F. , Roberts A. , Baxter G.
Published: April 2016

Rare-earth doped optical fibers have captivated the interest of many researchers around the world across the past three decades. The growth of this research field has been stimulated primarily through their application in optical communications as fiber lasers and amplifiers, although rare-earth doped optical fiber based devices are now finding important uses in many other scientific and industrial areas (for example, medicine, sensing, the military, and material processing). Such wide commercial interest has provided a strong incentive for innovative fiber designs, alternative glass compositions, and novel fabrication processes. A prerequisite for the ongoing progress of this research field is developing the capacity to provide high resolution information about the rare-earth dopant distribution profiles within the optical fibers. This paper constitutes a comprehensive review of the imaging techniques that have been utilized in the analysis of the distribution of the rare-earth ion erbium within the core of optical fibers.
Understanding the many-body expansion for large systems. II. Accuracy considerations
Authors: Lao Ka Un , Liu Kuan-Yu , Richard Ryan M. , Herbert John M.
Published: April 2016

To complement our study of the role of finite precision in electronic structure calculations based on a truncated many-body expansion (MBE, or “n-body expansion”), we examine the accuracy of such methods in the present work. Accuracy may be defined either with respect to a supersystem calculation computed at the same level of theory as the n-body calculations, or alternatively with respect to high-quality benchmarks. Both metrics are considered here. In applications to a sequence of water clusters, (H2O)N=6−55 described at the B3LYP/cc-pVDZ level, we obtain mean absolute errors (MAEs) per H2O monomer of ∼1.0 kcal/mol for two-body expansions, where the benchmark is a B3LYP/cc-pVDZ calculation on the entire cluster. Three- and four-body expansions exhibit MAEs of 0.5 and 0.1 kcal/mol/monomer, respectively, without resort to charge embedding. A generalized many-body expansion truncated at two-body terms [GMBE(2)], using 3–4 H2O molecules per fragment, outperforms all of these methods and affords a MAE of ∼0.02 kcal/mol/monomer, also without charge embedding. GMBE(2) requires significantly fewer (although somewhat larger) subsystem calculations as compared to MBE(4), reducing problems associated with floating-point roundoff errors. When compared to high-quality benchmarks, we find that error cancellation often plays a critical role in the success of MBE(n) calculations, even at the four-body level, as basis-set superposition error can compensate for higher-order polarization interactions. A many-body counterpoise correction is introduced for the GMBE, and its two-body truncation [GMBCP(2)] is found to afford good results without error cancellation. Together with a method such as ωB97X-V/aug-cc-pVTZ that can describe both covalent and non-covalent interactions, the GMBE(2)+GMBCP(2) approach provides an accurate, stable, and tractable approach for large systems.
Method for material characterization in a non-anechoic environment
Authors: Pometcu L. , Sharaiha A. , Benzerga R. , Tamas R. D. , Pouliguen P.
Published: April 2016

This paper presents a characterization method for extracting the reflection coefficient of materials and the real part of their permittivity. The characterization is performed in a real environment, as opposed to the classical measurement methods that require an anechoic chamber. In order to reduce the effects of the multipath propagation, a free space bistatic measurement was performed at different distances material-antennas in far field. By using a Teflon sample and a commercial absorbing material sample, measurements have been performed in order to validate the characterization technique.
Revisiting argon cluster formation in a planar gas jet for high-intensity laser matter interaction
Authors: Tao Y. , Hagmeijer R. , van der Weide E. T. A. , Bastiaens H. M. J. , Boller K.-J.
Published: April 2016

We determine the size of argon clusters generated with a planar nozzle, based on the optical measurements in conjunction with theoretical modelling. Using a quasi-one dimensional model for the moments of the cluster size distribution, we determine the influence of critical physical assumptions. These refer to the surface tension depending on the presence of thermal equilibrium, the mass density of clusters, and different methods to model the growth rate of the cluster radius. We show that, despite strong variation in the predicted cluster size, 〈N〉, the liquid mass ratio, g, can be determined with high trustworthiness, because g is predicted as being almost independent of the specific model assumptions. Exploiting this observation, we use the calculated value for g to retrieve the cluster size from optical measurements, i.e., calibrated Rayleigh scattering and interferometry. Based on the measurements of the cluster size vs. the nozzle stagnation pressure, we provide a new power law for the prediction of the cluster size in experiments with higher values of the Hagena parameter (Γ*>104). This range is of relevance for experiments on high-intensity laser matter interactions.
Intrinsic rotation drive by collisionless trapped electron mode turbulence
Authors: Wang Lu , Peng Shuitao , Diamond P. H.
Published: April 2016

Both the parallel residual stress and parallel turbulent acceleration driven by electrostatic collisionless trapped electron mode (CTEM) turbulence are calculated analytically using gyrokinetic theory. Quasilinear results show that the parallel residual stress contributes an outward flux of co-current rotation for normal magnetic shear and turbulence intensity profile increasing outward. This may induce intrinsic counter-current rotation or flattening of the co-current rotation profile. The parallel turbulent acceleration driven by CTEM turbulence vanishes, due to the absence of a phase shift between density fluctuation and ion pressure fluctuation. This is different from the case of ion temperature gradient turbulence, for which the turbulent acceleration can provide co-current drive for normal magnetic shear and turbulence intensity profile increasing outward. Its order of magnitude is predicted to be the same as that of the divergence of the residual stress [L. Wang and P. H. Diamond, Phys. Rev. Lett. 110, 265006 (2013)]. A possible connection of these theoretical results to experimental observations of electron cyclotron heating effects on toroidal rotation is discussed.
Extended application of Kohn-Sham first-principles molecular dynamics method with plane wave approximation at high energy—From cold materials to hot dense plasmas
Authors: Zhang Shen , Wang Hongwei , Kang Wei , Zhang Ping , He X. T.
Published: April 2016

An extended first-principles molecular dynamics (FPMD) method based on Kohn-Sham scheme is proposed to elevate the temperature limit of the FPMD method in the calculation of dense plasmas. The extended method treats the wave functions of high energy electrons as plane waves analytically and thus expands the application of the FPMD method to the region of hot dense plasmas without suffering from the formidable computational costs. In addition, the extended method inherits the high accuracy of the Kohn-Sham scheme and keeps the information of electronic structures. This gives an edge to the extended method in the calculation of mixtures of plasmas composed of heterogeneous ions, high-Z dense plasmas, lowering of ionization potentials, X-ray absorption/emission spectra, and opacities, which are of particular interest to astrophysics, inertial confinement fusion engineering, and laboratory astrophysics.
Evolution of nano-rheological properties of Nafion® thin films during pH modification by strong base treatment: A static and dynamic force spectroscopy study
Authors: Eslami Babak , López-Guerra Enrique A. , Raftari Maryam , Solares Santiago D.
Published: April 2016

Addition of a strong base to Nafion® proton exchange membranes is a common practice in industry to increase their overall performance in fuel cells. Here, we investigate the evolution of the nano-rheological properties of Nafion thin films as a function of the casting pH, via characterization with static and dynamic, contact and intermittent-contact atomic force microscopy (AFM) techniques. The addition of KOH causes non-monotonic changes in the viscoelastic properties of the films, which behave as highly dissipative, softer materials near neutral pH values, and as harder, more elastic materials at extreme pH values. We quantify this behavior through calculation of the temporal evolution of the compliance and the glassy compliance under static AFM measurements. We complement these observations with dynamic AFM metrics, including dissipated power and virial (for intermittent-contact-mode measurements), and contact resonance frequency and quality factor (for dynamic contact-mode measurements). We explain the non-monotonic material property behavior in terms of the degree of ionic crosslinking and moisture content of the films, which vary with the addition of KOH. This work focuses on the special case study of the addition of strong bases, but the observed mechanical property changes are broadly related to water plasticizing effects and ionic crosslinking, which are also important in other types of films.
Ab initio modeling of 2D layered organohalide lead perovskites
Authors: Fraccarollo Alberto , Cantatore Valentina , Boschetto Gabriele , Marchese Leonardo , Cossi Maurizio
Published: April 2016

A number of 2D layered perovskites A2PbI4 and BPbI4, with A and B mono- and divalent ammonium and imidazolium cations, have been modeled with different theoretical methods. The periodic structures have been optimized (both in monoclinic and in triclinic systems, corresponding to eclipsed and staggered arrangements of the inorganic layers) at the DFT level, with hybrid functionals, Gaussian-type orbitals and dispersion energy corrections. With the same methods, the various contributions to the solid stabilization energy have been discussed, separating electrostatic and dispersion energies, organic-organic intralayer interactions and H-bonding effects, when applicable. Then the electronic band gaps have been computed with plane waves, at the DFT level with scalar and full relativistic potentials, and including the correlation energy through the GW approximation. Spin orbit coupling and GW effects have been combined in an additive scheme, validated by comparing the computed gap with well known experimental and theoretical results for a model system. Finally, various contributions to the computed band gaps have been discussed on some of the studied systems, by varying some geometrical parameters and by substituting one cation in another’s place.
An on-chip colloidal magneto-optical grating
Authors: Prikockis M. , Wijesinghe H. , Chen A. , VanCourt J. , Roderick D. , Sooryakumar R.
Published: April 2016

Interacting nano- and micro-particles provide opportunities to create a wide range of useful colloidal and soft matter constructs. In this letter, we examine interacting superparamagnetic polymeric particles residing on designed permalloy (Ni0.8 Fe0.2) shapes that are subject to weak time-orbiting magnetic fields. The precessing field and magnetic barriers that ensue along the outer perimeter of the shapes allow for containment concurrent with independent field-tunable ordering of the dipole-coupled particles. These remotely activated arrays with inter-particle spacing comparable to the wavelength of light yield microscopic on-chip surface gratings for beam steering and magnetically regulated light diffraction applications.
Dependence of the photovoltaic performance of pseudomorphic InGaN/GaN multiple-quantum-well solar cells on the active region thickness
Authors: Mukhtarova Anna , Valdueza-Felip Sirona , Redaelli Luca , Durand Christophe , Bougerol Catherine , Monroy Eva , Eymery Joël
Published: April 2016

We investigate the photovoltaic performance of pseudomorphic In0.1Ga0.9N/GaN multiple-quantum well (MQW) solar cells as a function of the total active region thickness. An increase in the number of wells from 5 to 40 improves the short-circuit current and the open-circuit voltage, resulting in a 10-fold enhancement of the overall conversion efficiency. Further increasing the number of wells leads to carrier collection losses due to an incomplete depletion of the active region. Capacitance-voltage measurements point to a hole diffusion length of 48 nm in the MQW region.
Giant electrocaloric effect in PZT bilayer thin films by utilizing the electric field engineering
Authors: Zhang Tiandong , Li Weili , Cao Wenping , Hou Yafei , Yu Yang , Fei Weidong
Published: April 2016

The enhancement of the electrocaloric effect (ECE) was achieved by the amplifying effect of applied electric field through devising the thin films' structure. The PbZr0.95Ti0.05O3/PbZr0.52Ti0.48O3 bilayer structured thin films were fabricated on a Pt(111)/Ti/SiO2/Si substrate using sol-gel method. The ΔS = 20.5 J K−1 kg−1 and ΔT = 24.8 K for bilayer thin films is achieved around 125 °C much below Tc, which is caused by the amplifying electric field induced phase transition of OAFE/RFE in PZr0.95Ti0.05O3 layer. It is also worth mentioning that the films exhibit outstanding ECE at room temperature; ΔS = 11.9 J K−1 kg−1 and ΔT = 10.7 K are observed, which are attributed to the effect of amplifying electric field in PbZr0.95Ti0.05O3 layer and RFE/TFE at morphotropic phase boundaries (MPB) in PbZr0.52Ti0.48O3 layer. This result indicates that to amplify the local electric field engineering and to maximize the number of coexisting phases in heterostructures or multilayer thin films may be an effective way for cooling applications.
Note: All-digital pulse-shrinking time-to-digital converter with improved dynamic range
Authors: Chen Chun-Chi , Hwang Chorng-Sii , Lin Yi , Chen Guan-Hong
Published: April 2016

This paper proposes an all-digital pulse-shrinking time-to-digital converter (TDC) using the offset error cancellation circuitry to widen its dynamic range and to improve its accuracy. Although the TDC based on a pulse-shrinking mechanism can achieve a sub-gate resolution without circuit complexity, it possesses an undesired offset error that results in a nonzero lower bound appeared in its dynamic range and then affects its accuracy. The proposed cancellation circuitry for eliminating the offset error consists of a time adder with a delay line and a time subtractor with an identical delay line. The experimental TDC is implemented on Xilinx field programmable gate arrays and it also functions successfully in improving its dynamic range.
Improved contact resistance in ReSe2 thin film field-effect transistors
Authors: Corbet Chris M. , Sonde Sushant S. , Tutuc Emanuel , Banerjee Sanjay K.
Published: April 2016

We report the fabrication and device characteristics of exfoliated, few-layer, ReSe2 field effect transistors (FET) and a method to improve contact resistance by up to three orders of magnitude using ultra-high-vacuum annealing (UHV). Many devices were studied in the absence of light and we found an average contact of 750 Ω · cm after UHV treatment. The median FET metrics were similar to other transition metal dichalcogenides: field effect mobility ∼6.7 cm2/V · s, subthreshold swing ∼1.2 V/decade, and Ion/Ioff ∼ 105. In devices with low Rc current saturation was observed and is attributed to injection limited transport.
Normal and inverse bulk spin valve effects in single-crystal ruthenates
Authors: Peng Jin , Hu J. , Gu X. M. , Zhou G. T. , Liu J. Y. , Zhang F. M. , Wu X. S. , Mao Z. Q.
Published: April 2016

The current-perpendicular-to-plane magnetoresistivity (CPP-MR)/ρc(B) is investigated in single crystal ruthenates Ca3(Ru1−xTix)2O7 (x = 0.02). This material is naturally composed of ferromagnetic metallic bilayers (Ru,Ti)O2 separated by nonmagnetic insulating layers of Ca2O2, resulting in tunneling magnetoresistivity. Non-monotonic ρc(B) curves as well as the inverse spin valve effect are observed around the magnetic phase transition associating with the metal-to-insulator transition. A spin dependent tunneling model with alternate distribution of hard and soft magnetic layers [(Ru,Ti)O2] is proposed to explain the exotic CPP-MR behavior. This eccentric CPP-MR behavior highlights the strong spin-charge coupling in double-layered ruthenates and provides a potential material for spintronic devices.
Trap-assisted large gain in Cu2O/C60 hybrid ultraviolet/visible photodetectors
Authors: Liu Lan , Su Zisheng , Xi Qiaoyue , Gao Ge , Yang Wei , Zhao Yongxia , Wu Cunqi , Wang Lidan , Xu Jingwei
Published: April 2016

Photomultiplication-type ultraviolet (UV)/visible photodetectors (PDs) are demonstrated in an electrodeposited Cu2O/C60 hybrid structure. These simple organic/inorganic hybrid PDs exhibit external quantum efficiencies (EQEs) of 1.1 × 104% under illumination of 365 nm UV light at −3 V, indicating a large gain of photocurrent for these devices. Such an EQE is one of the highest values among the reported organic/inorganic hybrid PDs at the same voltage. Cu2O and C60 are found to play different roles in realizing the photomultiplication. Copper vacancies are proposed as the defects in the electrodeposited Cu2O layers, which can trap photogenerated holes. Such trapped holes will trigger the injection of multiple electrons and hence result in the photocurrent gain of the devices while C60 primarily acts as a light absorption media to provide free holes.
Development of attenuation and diffraction corrections for linear and nonlinear Rayleigh surface waves radiating from a uniform line source
Authors: Jeong Hyunjo , Zhang Shuzeng , Cho Sungjong , Li Xiongbing
Published: April 2016

In recent studies with nonlinear Rayleigh surface waves, harmonic generation measurements have been successfully employed to characterize material damage and microstructural changes, and found to be sensitive to early stages of damage process. A nonlinearity parameter of Rayleigh surface waves was derived and frequently measured to quantify the level of damage. The accurate measurement of the nonlinearity parameter generally requires making corrections for beam diffraction and medium attenuation. These effects are not generally known for nonlinear Rayleigh waves, and therefore not properly considered in most of previous studies. In this paper, the nonlinearity parameter for a Rayleigh surface wave is defined from the plane wave displacement solutions. We explicitly define the attenuation and diffraction corrections for fundamental and second harmonic Rayleigh wave beams radiated from a uniform line source. Attenuation corrections are obtained from the quasilinear theory of plane Rayleigh wave equations. To obtain closed-form expressions for diffraction corrections, multi-Gaussian beam (MGB) models are employed to represent the integral solutions derived from the quasilinear theory of the full two-dimensional wave equation without parabolic approximation. Diffraction corrections are presented for a couple of transmitter-receiver geometries, and the effects of making attenuation and diffraction corrections are examined through the simulation of nonlinearity parameter determination in a solid sample.
Influence of nonlinear coordinate transformation on thermal cloaking performances of multilayered cylindrical thermal cloaks
Authors: Yuan Xue Bo , Lin Guo Chang , Wang You Shan
Published: April 2016

Layered discretization is an efficient way of realizing thermal cloaks. The aim of this paper is to investigate the effect of nonlinear coordinate transformation on the thermal cloaking performance of multilayered cylindrical thermal cloak. Two indexes are defined to quantify the thermal cloaking performance. Nonlinear coordinate transformations with different forms are established to design the multilayered structures and the thermal cloaking performances are analyzed by full-wave simulations. The results show that the thermal cloaking performances of multilayered structures are directly influenced by the form of coordinate transformation which determines the distributions of heat flows in the cloak region. Through the active changing of the form of coordinate transformation, the thermal cloaking performance of multilayered structure can be controlled and optimized. In addition, a three-piecewise linear coordinate transformation is designed to concentrate the heat flux into the middle region of the cloak and the corresponding multilayered structure is demonstrated to have near-perfect thermal cloaking performance. These results may provide a beneficial guidance to achieve performance improvements for multilayered structures of thermal cloaks.