bluuebunny/crossref_metadata_2025 huggingface dataset:
Synthesis, Photophysical Properties and Near Infrared Electroluminescence of 1(4),8(11),15(18),22(25)‐Tetra‐(methoxy‐phenoxy)phthalocyanine
Authors: Bai Qinglong , Zhang Chunhua , Cheng Chuanhui , Li Wancheng , Wang Jin , Du Guotong
Published: February 2012

A new soluble phthalocyaine 1(4),8(11),15(18),22(25)‐tetra‐(methoxy‐phenoxy)phthalocyanine (MPPc) was synthesized and verified by mass spectrum (MS), 1H NMR, IR and elemental analysis. The methoxy‐phenoxy groups were introduced in order to enhance the solubility of the phthalocyanine. The photophysical and electroluminescent properties were investigated. The organic light‐emitting diodes (OLEDs) with the structure of ITO/PVK:MPPc(40 nm)/BCP(20 nm)/Alq3(30 nm)/Al were fabricated. Room‐temperature near infrared (NIR) electroluminescence (EL) was observed near 891 nm that effectively covered the ?rst optical communication window near 850 nm.
One Pot Synthesis of Medicinally Important cis‐2‐Methyl‐4‐amino substituted‐1,2,3,4‐tetrahydroquinolines
Authors: Kiran Kumar H. C. , Mahadevan K. M. , Prabhakara Varma P. , Srinivasa A.
Published: February 2012

A simple synthesis of medicinally important cis‐2‐methyl‐4‐azapan‐2‐one‐1,2,3,4‐tetrahydroquinolines/cis‐9‐(2‐methyl‐1,2,3,4‐tetrahydroquinolin‐4‐yl)‐9H‐carbazole was reported. Multicomponent one pot synthesis with anilines and N‐vinylcaprolactam/N‐vinyl carbazole via imino Diels‐Alder reaction by using antimony trichloride as catalyst and acetonitrile as solvent was employed. NMR technique (2D) was used to study the regio‐ and stereo‐chemistry of newly synthesized compounds. The cis diastereo‐selectivity of the products was predicted by COSY and NOESY studies.
Synthesis, Structure and Thermodynamic Property of a New Lithium Borate: Li4[B8O13(OH)2]·3H2O
Authors: Li Ping , Liu Zhihong
Published: February 2012

A new hydrated lithium borate, Li4[B8O13(OH)2]·3H2O, has been hydrothermally synthesized and characterized by single crystal X‐ray diffraction, FT‐IR spectroscopy, simultaneous TGA‐DTA and chemical analysis. It crystallizes in the triclinic, space group $ P {\bar 1} $, a=8.4578(5) Å, b=8.7877(5) Å, c=10.8058(7) Å, α=87.740(3)°, β=71.819(3)°, γ=61.569(3)°, Z=2, V=665.26(7) Å3, Dc=2.043 g/cm3. Its crystal structure features polyborate anionic layers with the larger odd 13‐membered boron rings constructed by [B8O13(OH)2]4− FBBs. Through designing the thermochemical cycle, the standard molar enthalpy of formation of this borate was determined to be −(7953.8±6.6) kJ·mol−1 by using a heat conduction microcalorimeter.
Environmentally Benign Synthesis of Sugar Orthoesters Promoted by Anhydrous Sodium Acetate and Ultrasound
Authors: Zhao Jinzhong , Wei Shanqiao , Yue Aiqin , Shao Huawu
Published: February 2012

A convenient and alternative procedure for the synthesis of sugar orthoesters from glycosyl bromides with anhydrous sodium acetate as base under ultrasound irradiation is described. Various sugar and sugar‐sugar orthoesters were prepared in 70%–91% isolated yields.
Fluorescent Properties of the Amidinophenylporphyrins Interacting with DNA
Authors: Wang Kai , Li Tian , Yu Faquan , Zheng Yunman , Wong Wai‐Kwok , Kwong Daniel W. J. , Li Zaoying
Published: February 2012

5,10,15,20‐Tetrakis(4‐amidinolphenyl)porphyrin, its Zn complex and amidinolphenyl bispophyrin interacting with calf thymus DNA were investigated by fluorescence emission spectra and fluorescence life time measurements were also shown. The binding modes of these compounds were recorded and lifetimes of luminescence were measured as a function of the nature to understand the interaction with DNA. The results suggest those amidinoporphyrins are promising new photodynamic therapeutic agents.
Synthesis of Small Molecules Targeting Multiple DNA Structures using Click Chemistry
Authors: Howell Lesley A. , Bowater Richard A. , O'Connell Maria A. , Reszka Anthony P. , Neidle Stephen , Searcey Mark
Published: February 2012

The ability of small molecules to target DNA forms the basis of many clinically used antitumour agents. This study examines the effects of novel 9‐aminoacridine carboxamides, synthesised by click chemistry based upon the reactions of either 9‐(2‐azidoethyl)amino or 9‐propargylaminoacridine compounds, on various types of DNA tertiary structures. This gave either monomeric or dimeric compounds, the dimeric derivatives being the first unsymmetrical acridine dimers to be described. The compounds were assayed for duplex DNA, quadruplex DNA and four‐way junction DNA binding. Their antiproliferative activity in the Human promyelocytic leukaemia cell line, HL60, was also assessed. Although for some of the compounds, notably the acridine 4‐carboxamides, activity correlated with DNA binding affinity, for others it did not, with the rigidly linked dimers in particular showing a complicated relationship between 3‐ and 4‐carboxamide structure and biological activity. The monomeric 3‐carboxamides were more effective at stabilising G‐quadruplex structures and also gave more hits in the four‐way junction stabilisation assay. There is clear evidence from the binding of the 3‐carboxamides that these compounds destabilise the open X form of the junction at lower concentrations and stabilise the X‐stacked at higher concentrations. This might have implications for the biological activity of these compounds against proteins that bind to the Holliday junction (HJ).
A genetic algorithm tuned optimal controller for glucose regulation in type 1 diabetic subjects
Authors: Ghosh Subhojit , Gude Srihari
Published: February 2012

An optimal state feedback controller is designed with the objective of minimizing the elevated glucose levels caused by meal intake in Type 1 diabetic subjects, by the minimal infusion of insulin. The states for the controller based on linear quadratic regulator theory are estimated from noisy data using Kalman filter. The controller designed for a physiological relevant mathematical model is coupled with another model for simulating meal dynamics, which converts meal intake into glucose appearance rate in the plasma. The tuning parameters (weighting matrices) of the controller and the design parameters (noise covariance matrices) of the Kalman filter are optimized using genetic algorithm. The controller based on the combined framework of evolutionary computing and state estimated linear quadratic regulator is found to maintain normoglycemia for meal intakes of varying carbohydrate content. The proposed approach addresses noisy output measurement, modeling error and delay in sensor measurement. Copyright © 2012 John Wiley & Sons, Ltd.
Polarization‐Dependent SERS at Differently Oriented Single Gold Nanorods
Authors: Jiao Jiqing , Wang Xiao , Wackenhut Frank , Horneber Anke , Chen Liuping , Failla Antonio Virgilio , Meixner Alfred J. , Zhang Dai
Published: February 2012

We investigated the influence of the orientation of individual gold nanorods on the polarization‐dependent single‐particle surface‐enhanced Raman spectroscopy (SERS) of adenine. Higher‐order laser beams (radial and azimuthal polarizations) have been used in combination with a parabolic mirror‐assisted confocal optical microscope. Based on the photoluminescence (PL) patterns of the single gold nanorods and the simulated electric‐field distribution in the focus, we distinguished between isolated gold rods and clusters as well as single nanorods with different orientations. We found that for single gold nanorods lying flat on the substrate, the longitudinal particle plasmon resonance (PPR) mode can be excited more efficiently with the in‐plane field component in the focus of an azimuthally polarized laser beam, which enables the observation of stronger enhanced adenine Raman spectra from the single gold nanorods compared to the case of a radially polarized beam.
Li2 Trapped inside Tubiform [n] Boron Nitride Clusters (n=4–8): Structures and First Hyperpolarizability
Authors: Ma Fang , Zhou Zhong‐Jun , Liu Ying‐Tao
Published: February 2012

The geometries and electronic properties of tubiform [n] boron nitride clusters entrapping Li2 (Li2@BN‐cluster(n,0); n=4–8), obtained by doping BN‐cluster(n,0) with Li2 molecules, are investigated by means of DFT. The effects of tube diameter n on the dipole moment μ0, static polarizability α0, and first hyperpolarizability β0 are elucidated. Both the dipole moment and polarizability increase with increasing tube diameter, whereas variation of the static first hyperpolarizability with tube diameter is not monotonic; β0 follows the order 1612 (n=4)<3112 (n=5)<5534 (n=7)<8244 (n=6)<12 282 a.u. (n=8). In addition, the natural bond orbital (NBO) charges show that charge transfer takes place from the Li2 molecule to the BN cluster, except for BN‐cluster(8,0) with larger tube diameter. Since the large‐diameter tubular BN‐cluster(8,0) can trap the excess electrons of the Li2 molecule, Li2@BN‐cluster(8,0) can be considered to be a novel electride compound.
Structures and Reactivity of Oxygen‐Rich Scandium Cluster Anions ScO3–5−
Authors: Tian Li‐Hua , Zhao Yan‐Xia , Wu Xiao‐Nan , Ding Xun‐Lei , He Sheng‐Gui , Ma Tong‐Mei
Published: February 2012

Oxygen‐rich scandium cluster anions ScO3–5− are prepared by laser ablation and allowed to react with n‐butane in a fast‐flow reactor. A time‐of‐flight mass spectrometer is used to detect the cluster distribution before and after the reactions. The ScO3− and ScO4− clusters can react with n‐butane to produce ScO3H−, ScO3H2−, and ScO4H−, while the more oxygen‐rich cluster ScO5− is inert. The experiment suggests that unreactive cluster isomers of ScO3− and ScO4− are also present in the cluster source. Density functional theory and ab initio methods are used to calculate the structures and reaction mechanisms of the clusters. The theoretical results indicate that the unreactive and reactive cluster isomers of ScO3,4− contain peroxides (O22−) and oxygen‐centered radicals (O.−), respectively. The mechanisms and energetics for conversion of unreactive O22− to reactive O.− species are also theoretically studied.
Microheterogeneities in Ionic‐Liquid–Methanol Solutions Studied by FTIR Spectroscopy, DFT Calculations and Molecular Dynamics Simulations
Authors: Roth Christian , Appelhagen Andreas , Jobst Niels , Ludwig Ralf
Published: February 2012

The interest in ionic liquids (ILs) is steadily increasing because of their fascinating physicochemical properties and because of their broad range of applications in synthesis, separation, catalysis and electrochemistry. However, the multiplicity of their uses strongly depends on a molecular understanding of their exceptional properties. One key to a better understanding of their unique properties are spectroscopic studies of ionic liquids in conventional organic solvents in combination with DFT calculations and molecular dynamics simulations. Therefore we investigated the mixtures of the imidazolium‐based ionic liquid [C2mim][NTf2] with methanol. Caused by the amphiphilic character of methanol both liquids are miscible over the whole mixture range. The scope of this work is to study the changes in the IL network upon dilution and to investigate the formation of methanol clusters embedded in the IL matrix. The mixtures were studied by FTIR spectroscopy in the mid‐infrared region. The formation of methanol clusters was studied from the OD stretching vibrational bands between 2300 and 2800 cm−1. The cluster populations of methanol could be derived from molecular dynamics simulations for the same mixtures. Weighting the DFT calculated frequencies by the cluster populations we could reproduce the measured spectra in the OD stretching region up to XMeOH=0.5. Above XMeOH=0.8, strong formation of self‐methanol clusters takes place resulting in increasing diffusion coefficients related to decreasing dynamical heterogeneities. Thus we obtained a deep understanding of the solute–solvent and solute–solute interactions as well as information about the presence of microheterogeneities in the mixtures.
An MD Study of the Applicability of the Walden Rule and the Nernst–Einstein Model for Ionic Liquids
Authors: Liu Hongjun , Maginn Edward
Published: February 2012

Six different ionic liquids containing imidazolium, pyrrolidinium and ammonium cations paired with bis[(trifluoromethyl)sulfonyl]imide and bis[(perfluoroethyl)sulfonyl]imide anions were studied using molecular dynamics simulations. Ionic conductivities, shear viscosities and self‐diffusivities were computed and compared to see what relationships exist between these three transport properties. The simulations suggest that these ionic liquids follow closely the Walden rule, which relates ionic conductivity to fluidity. The computed ionic conductivities agree well with those predicted from the Nernst–Einstein model, suggesting that long‐time correlation among ion velocities is small, or that the “ionicity” of these ionic liquids is high.
Heterostructured TiO2 Nanoparticles/Nanotube Arrays: In Situ Formation from Amorphous TiO2 Nanotube Arrays in Water and Enhanced Photocatalytic Activity
Authors: Huo Kaifu , Wang Hairong , Zhang Xuming , Cao Yue , Chu Paul K.
Published: February 2012

Heterostructured TiO2 nanoparticles/nanotube arrays (NPs/NTAs) are produced from as‐anodized amorphous TiO2 nanotube arrays in water at a temperature as low as 90 °C. The phase and morphology transformation of the as‐anodized amorphous TiO2 nanotube in water can be attributed to a water‐induced dissolution and recrystallization mechanism in which the as‐anodized amorphous TiO2 NTAs are gradually self‐sacrificed, and then spontaneously morphing into the composite NPs/NTAs structure consisting of anatase NPs and thinner amorphous NTs. The composite can be further crystallized into anatase TiO2 NPs/NTAs consisting of anatase NT and anatase NPs by annealing in air at 450 °C for 3 hours. The composite anatase TiO2 NPs/NTAs have a surface area that is 1.4 times larger than that of the anatase TiO2 NTAs and possess enhanced photocatalytic activity in the photodecomposition of organic pollutants and water splitting. The photodecomposition rate of the organic pollutant rhodamine B by the anatase TiO2 NPs/NTAs photocatalyst is two times higher than that by the annealed anatase TiO2 NTAs. The enhanced photocatalytic activity of the hererostructured TiO2 NPs/NTAs arises from the large surface area of the TiO2 NPs and superior electron transport in anatase TiO2 NT. The in situ hydrothermal conversion of the microstructure from amorphous TiO2 NTAs into hererostructured TiO2 NPs/NTAs in water is very simple thereby enabling the design and fabrication of highly photoactive one‐dimensional TiO2‐based functional materials applicable to photocatalysis and solar energy conversion.
Resin‐Derived Hierarchical Porous Carbon Spheres with High Catalytic Performance in the Oxidative Dehydrogenation of Ethylbenzene
Authors: Wang Lifeng , Delgado Juan J. , Frank Benjamin , Zhang Zhe , Shan Zhichao , Su Dang Sheng , Xiao Feng‐Shou
Published: February 2012

Pre‐shaped hierarchical porous carbon (HPC) spheres have been synthesized through a facile anion exchanged route. An industrial polymeric anion‐exchange resin with a hierarchical pore structure was used as the carbon precursor. Its high porosity was conserved using an aluminate/silicate precursor forming a hard support to prevent the structural collapse during the carbonization process. Physicochemical bulk and surface properties of the obtained HPC spheres were characterized by X‐ray diffraction, scanning and transmission electron microscopy, N2 physisorption, and X‐ray photoemission spectroscopy. Results obtained indicate that HPC keeps the abundant hierarchical porosity including meso‐ and macropores as well as the high surface area of the resin precursor. The as‐synthesized HPC spheres were tested as a catalyst for oxidative dehydrogenation of ethylbenzene to styrene. The oxygen‐rich catalyst surface formed under reaction conditions shows a high catalytic performance and stability, making HPC to a potential catalyst for this type of reaction.
Adsorption and Separation of Light Gases on an Amino‐Functionalized Metal–Organic Framework: An Adsorption and In Situ XRD Study
Authors: Couck Sarah , Gobechiya Elena , Kirschhock Christine E. A. , Serra‐Crespo Pablo , Juan‐Alcañiz Jana , Martinez Joaristi Alberto , Stavitski Eli , Gascon Jorge , Kapteijn Freek , Baron Gino V. , Denayer Joeri F. M.
Published: February 2012

The NH2‐MIL‐53(Al) metal–organic framework was studied for its use in the separation of CO2 from CH4, H2, N2 C2H6 and C3H8 mixtures. Isotherms of methane, ethane, propane, hydrogen, nitrogen, and CO2 were measured. The atypical shape of these isotherms is attributed to the breathing properties of the material, in which a transition from a very narrow pore form to a narrow pore form and from a narrow pore form to a large pore form occurs, depending on the total pressure and the nature of the adsorbate, as demonstrated by in situ XRD patterns measured during adsorption. Apart from CO2, all tested gases interacted weakly with the adsorbent. As a result, they are excluded from adsorption in the narrow pore form of the material at low pressure. CO2 interacted much more strongly and was adsorbed in significant amounts at low pressure. This gives the material excellent properties to separate CO2 from other gases. The separation of CO2 from methane, nitrogen, hydrogen, or a combination of these gases has been demonstrated by breakthrough experiments using pellets of NH2‐MIL‐53(Al). The effect of total pressure (1–30 bar), gas composition, temperature (303–403 K) and contact time has been examined. In all cases, CO2 was selectively adsorbed, whereas methane, nitrogen, and hydrogen nearly did not adsorb at all. Regeneration of the adsorbent by thermal treatment, inert purge gas stripping, and pressure swing has been demonstrated. The NH2‐MIL‐53(Al) pellets retained their selectivity and capacity for more than two years.
Edge‐Enriched, Porous Carbon‐Based, High Energy Density Supercapacitors for Hybrid Electric Vehicles
Authors: Kim Yong Jung , Yang Cheol‐Min , Park Ki Chul , Kaneko Katsumi , Kim Yoong Ahm , Noguchi Minoru , Fujino Takeshi , Oyama Shigeki , Endo Morinobu
Published: February 2012

Supercapacitors can store and deliver energy by a simple charge separation, and thus they could be an attractive option to meet transient high energy density in operating fuel cells and in electric and hybrid electric vehicles. To achieve such requirements, intensive studies have been carried out to improve the volumetric capacitance in supercapacitors using various types and forms of carbons including carbon nanotubes and graphenes. However, conventional porous carbons are not suitable for use as electrode material in supercapacitors for such high energy density applications. Here, we show that edge‐enriched porous carbons are the best electrode material for high energy density supercapacitors to be used in vehicles as an auxiliary powertrain. Molten potassium hydroxide penetrates well‐aligned graphene layers vertically and consequently generates both suitable pores that are easily accessible to the electrolyte and a large fraction of electrochemically active edge sites. We expect that our findings will motivate further research related to energy storage devices and also environmentally friendly electric vehicles.
Hydrogen Production from Glucose and Sorbitol by Sorption‐Enhanced Steam Reforming: Challenges and Promises
Authors: He Li , Chen De
Published: February 2012

Concerning energy and environmental sustainability, it is appealing to produce hydrogen from sugars or sugar alcohols that are readily obtained from the hydrolysis of cellulosic biomass. Nevertheless, the conversion of such compounds for hydrogen production poses great technical challenges. In this paper, we report that hydrogen purity and yield can be significantly improved by integrating in situ CO2 capture into the steam reforming reaction of the model compounds—glucose and sorbitol. The experimental assessment was conducted at a steam‐to‐carbon ratio of 1.8 for sorbitol and 6 for glucose from 450–625 °C. As predicted by thermodynamic analysis, combining CO2 capture and reforming reactions at favorable operating conditions yielded very high purity hydrogen, for instance, 98.8 mol % from sorbitol and 99.9 mol % from glucose. However, there are trade‐offs between hydrogen purity and yield in practice. The lower operating temperatures in the examined range helped to increase the hydrogen purity and reduce the CO content in the gas product, whereas a high hydrogen yield was more likely to be obtained at higher temperatures. Coupling CO2 capture lowered the risk of coke formation during the steam reforming of glucose. Coke accumulated in the reactor for the sorption‐enhanced steam reforming of glucose was mostly from the slow pyrolysis of glucose before it came into contact with the catalyst–acceptor bed. This problem may be solved by improving heat transfer or reconstructing the reactor, for instance, by using a fluidized‐bed reactor.
A hierarchical mobile‐agent‐based security operation center
Authors: Li Jung‐Shian , Hsieh Che‐Jen , Lin Husan‐Yeh
Published: February 2012

The continuous evolvement of the e‐domain has led to a significant increase in the amount of sensitive personal information stored on networked hosts. These hosts are invariably protected by security mechanisms such as intrusion detection systems, Intrusion Prevention System (IPS), antivirus software, firewalls, and so forth. However, they still remain vulnerable to the threat of malicious attacks, theft and intrusion. The high false positive alarm rate of such mechanisms is particularly troublesome because false alarms greatly degrade the efficiency of the security framework. Security operation centers (SOCs) provide an automated solution for analyzing the threat to a network such that appropriate protective measures can be put in place. This paper proposes a novel hierarchical mobile‐agent‐based SOC to overcome the vulnerability of traditional static SOCs to single point of failure attacks. In addition, the network is partitioned into multiple divisions, each with its own alert detection and aggregation methodology to improve the computational efficiency of the data collection and fusion process. The data acquired in the various divisions are fused and correlated in an efficient manner via intrusion detection message exchange format, XML, session and timer methods The experimental results confirm the effectiveness and efficiency of the proposed hierarchical mobile‐agent‐based SOC framework. Copyright © 2012 John Wiley & Sons, Ltd.
Performance analysis of decision directed maximum likelihood MIMO channel tracking algorithm
Authors: Karami Ebrahim
Published: February 2012

In this paper, the performance of decision directed (DD) maximum likelihood (ML) channel tracking algorithm is analyzed. The ML channel tracking algorithm presents efficient performance especially in the decision directed mode of the operation. In this paper, after introducing the method for analysis of DD algorithms, the performance of ML MIMO channel tracking algorithm in the DD mode of operation is analyzed. In this method channel tracking error is evaluated for a given decision error rate. Then, the decision error rate is approximated for a given channel tracking error. By solving these two derived equations jointly, both the decision error rate and the channel tracking error are computed. The presented analysis is compared with simulation results for different channel ranks, Doppler frequency shifts, and signal‐to‐noise ratios, and it is shown that the analysis is a good match for simulation results especially in high rank MIMO channels and high Doppler shifts. Copyright © 2012 John Wiley & Sons, Ltd.
Localized role of CRMP1 and CRMP2 in neurite outgrowth and growth cone steering
Authors: Higurashi Masakazu , Iketani Masumi , Takei Kohtaro , Yamashita Naoya , Aoki Reina , Kawahara Nobutaka , Goshima Yoshio
Published: February 2012

Collapsin response mediator protein 1 (CRMP1) and CRMP2 have been known as mediators of extracellular guidance cues such as semaphorin 3A and contribute to cytoskeletal reorganization in the axonal pathfinding process. To date, how CRMP1 and CRMP2 focally regulate axonal pathfinding in the growth cone has not been elucidated. To delineate the local functions of these CRMPs, we carried out microscale‐chromophore‐assisted light inactivation (micro‐CALI), which enables investigation of localized molecular functions with highly spatial and temporal resolutions. Inactivation of either CRMP1 or CRMP2 in the neurite shaft led to arrested neurite outgrowth. Micro‐CALI of CRMP2 in the central domain of the growth cones consistently arrested neurite outgrowth, whereas micro‐CALI of CRMP1 in the same region caused significant lamellipodial retraction, followed by retardation of neurite outgrowth. Focal inactivation of CRMP1 in its half region of the growth cone resulted in the growth cone turning away from the irradiated site. Conversely, focal inactivation of CRMP2 resulted in the growth cone turning toward the irradiated site. These findings suggest different functions for CRMP1 and CRMP2 in growth cone behavior and neurite outgrowth. © 2012 Wiley Periodicals, Inc. Develop Neurobiol, 2012
EuLiGe2 and YbLiGe2 – A Divalent and an Intermediate‐Valent Compound with CaLiSi2‐Type Structures
Authors: Iyer Abishek K. , Peter Sebastian C.
Published: February 2012

Single‐phase EuLiGe2 and YbLiGe2 compounds were synthesized using a high frequency heating method. The crystal structure of EuLiGe2 was determined; it is an orthorhombic system, in space group Pnma, which crystallizes with aCaLiSi2‐type structure: a = 7.7880(10) Å, b = 3.9385(10) Å, c = 10.6436(10) Å. RELiGe2 (RE = Eu, Yb) is made up of lithium and germanium atoms forming a ten‐membered ring with channels occupied by two rare earth atoms. The Ge atoms are arranged in a zigzag manner and form the backbone of the structure. The magnetic susceptibility of EuLiGe2 obeys the Curie–Weiss law above 40 K (Eu2+) and shows antiferromagnetic ordering at 29 K followed by spin reordering at 23 K. Electrical resistivity measurements revealed the metallic nature of EuLiGe2 and confirmed the two magnetic orderings at low temperature. The divalent nature of Eu was confirmed by X‐ray absorption near edge spectroscopy (XANES). Magnetic measurements of YbLiGe2 showed that it is paramagnetic without long‐range magnetic ordering down to 2 K. The magnetic susceptibility deviates from the Curie–Weiss law below 100 K, presumably because of crystal field effects from Yb3+ ions. Magnetic susceptibility measurements of YbLiGe2 show a mixed‐valent ytterbium atom, and a magnetic moment within the linear region (<100 K) of 2.16 μB/Yb is very well supported by XANES.
Robust optimization approach for synthesis of integrated biorefineries with supply and demand uncertainties
Authors: Tay Douglas H.S. , Ng Denny K.S. , Tan Raymond R.
Published: February 2012

This work presents a robust optimization approach for the synthesis of integrated biorefineries that deals with uncertainties in raw material supply and product demand. This approach makes use of a single‐step mixed integer nonlinear programming formulation, which is generated and solved with data from multiple biomass supply and product demand scenarios. Based on the optimized result, detailed allocation of biomass, intermediates, and final products can be determined. The optimal capacity of each process technology can also be found. An illustrative case study is then used to demonstrate the effectiveness of the robust optimization approach to determine the optimum integrated biorefinery configuration and capacity with consideration of uncertainties. © 2012 American Institute of Chemical Engineers Environ Prog, 32: 384‐389, 2013
Vertical flame spread on charring materials at different ambient temperatures
Authors: Mangs Johan , Hostikka Simo
Published: February 2012

A new flame spread apparatus for the measurement of flame spread rates at different ambient temperatures is presented. A 2‐m long sample is pre‐heated with air to the desired temperature and ignited from its lower end with a small propane burner. The flame spread is traced with thermocouples in contact with the sample surface. The features and function of the new apparatus are described, as well as series of vertical flame spread experiments on cylindrical birch rods and electrical cables made of polyvinylchloride (PVC) and flame retardant non‐corrosive (FRNC) materials. Vertical flame spread rates 6–62 mm/s (temperature range 22–271 °C) were determined for birch samples, 3–24 mm/s (22–190 °C) for PVC cable samples, and 0–4 mm/s (22–293 °C) for FRNC cable samples. Small‐scale experiments with thermogravimetric analysis and cone calorimeter were performed to characterize the sample materials in terms of their thermal and fire behaviour. Copyright © 2012 John Wiley & Sons, Ltd.
Experimental Investigation of Air Relative Humidity (RH) Cycling Tests on MEA/Cell Aging in PEMFC Part II: Study of Low RH Cycling Test with Air RH at 62%/0%
Authors: Huang B. T. , Chatillon Y. , Bonnet C. , Lapicque F. , Leclerc S. , Hinaje M. , Raël S.
Published: February 2012

The effect of low relative humidity (RH) cycling (RHC 62%/0%) on the degradation mechanisms of a single proton exchange membrane fuel cell (5 × 5 cm2) was investigated and compared to a cell operated at constant humidification (RHC = 62%). The overall cell performance loss was near 33 μV h–1, which is greater than the voltage decay under constant RH condition near 3 μV h–1. The electroactive surface was reduced but to an acceptable level. Impedance spectroscopy revealed that the ohmic and charge transfer resistances were reduced by the likely improved hydration of the ionomeric layer at the catalyst due to hydrogen crossover. This was so important that H2 starvation was finally responsible for the collapse of the cell after 650 h. Transmission electron microscopy showed occurrence of various phenomena, e.g., bubbles and pinholes formation in the membrane due to local overheat from hydrogen combustion at the cathode, and thickness reduction of catalytic layers. The water up take obtained by 1H NMR within the membrane electrode assembly (MEA) after low RH cycling reduced by 24% compared to a fresh MEA. Observations are also compared to those obtained at high RH cycling (RHC 62%/100%) presented in Part I of this study [1].
Heterogeneities of Aging within a PEMFC MEA
Authors: Dubau L. , Durst J. , Maillard F. , Chatenet M. , André J. , Rossinot E.
Published: February 2012

In this study, we investigated the long‐term morphological and chemical changes of PEMFC cathode materials, with a special focus on the homogeneity of aging in different operating conditions (stationary or intermittent). The spatially‐resolved physico‐chemical analyses, performed at the cathode inlet/outlet region of the membrane electrode assembly, put in evidence that the cathode inlet ages much more rapidly than the cathode outlet in counter‐flow mode, this effect being exacerbated at high cell current. The rationale for such observation is the existence of heterogeneities of local current density, essentially caused by the depletion in air partial pressure and the increase in water content along the gas‐channel. We also evidenced heterogeneities of aging through the catalytic layer (CL). These heterogeneities are explained by the fact that Ptz+ ions produced by the corrosion of the Pt–Co/C nanoparticles are evacuated by the produced water exiting the CL [at the gas‐diffusion layer (GDL)|CL interface] or consumed by H2 crossing‐over from the anode through the cathode [at the CL|proton‐exchange membrane (PEM) interface], resulting in the formation of the so‐called “platinum‐band” in the PEM.
Effects of pH Value on Composition Structure and Catalytic Activity of Pt‐SnOx/C Prepared by Ethylene Glycol Method
Authors: Liu Y. H. , Wu F. , Wu C.
Published: February 2012

Pt‐SnOx nanoparticles were synthesized by the ethylene glycol (EG) method in solution of H2PtCl6 and SnCl2, with the same concentrations of Pt and Sn, but different pH values. The pH value after the end of platinum reduction reaction was not changed any more, except that a certain amount of water was added to deposit the Pt‐SnOx nanoparticles on the carbon support. The pre‐nanocatalysts were characterized by X‐ray photoelectron spectroscopy (XPS) to investigate the contents of Pt and Sn, and their catalytic activities for ethanol electrooxidation were tested by cyclic voltammetry (CV). The result was that the Sn contents were increasing as the Pt/Sn atomic ratios of 2.2, 2.6, 5.1, 7.4, 8.7, with the decreasing end pH values of 4.5, 5.0, 5.5, 6.5, 7.5, and the Pt contents became less than the addition in the preparation solution while the end pH values were <5.5, but the catalytic activities for ethanol electrooxidation were not so much regularly changed. Besides, from the end pH value of 5.5 to the increasing 9.0, all the platinum nanoparticles could be completely deposited on the carbon support, under the condition that only a certain amount of water was added.
A Three Dimensional Electrical Model of PEMFC Stack
Authors: Le Ny M. , Chadebec O. , Cauffet G. , Dedulle J. M. , Bultel Y.
Published: February 2012

Mathematical modeling is an essential tool in the design of fuel cell systems, as it is important to understand the response of a stack under different conditions. This paper proposes a three dimensional electrical model of PEMFC stack. Such approach highlights the phenomena that occur at the macroscopic scale which are the electrical interactions taking place within the stack. At this scale, the microscopic phenomena are taken into account by averaging them over all the thickness of the membrane electrode assembly (MEA). This model consists of solving the charge transport equation in three dimensions. In order to avoid interfacial issues with the potential jump that occurs in the MEAs, a special source term is added in the transport equation. It makes the model robust, reliable, and helpful for understanding the effect of anomalies on the electric behavior of a PEMFC stack. After describing the equations and the numerical method used for the model, the paper shows some electrical phenomena such as cells interactions, non‐equipotential bipolar plate, higher cell voltages and internal loop of current.
Dynamic Response of a Subsaturated Polymer Electrolyte Fuel Cell in Counterflow Mode
Authors: Bayer M. H. , Schneider I. A.
Published: February 2012

This work demonstrates that the operation of a subsaturated polymer electrolyte fuel cell in counterflow mode results in a significantly elongated relaxation time after a load change, if compared to coflow mode. This effect is investigated here by using combined dynamic locally resolved measurements of the current density, the high frequency resistance, and the relative humidity. It is shown that the elongated relaxation time is a consequence of slow membrane hydration in the region of the cell, downstream the anode flow field, where the diffusive flux of water across the membrane occurs from the anode to the cathode. Here, the anode gas stream, which is humidified upstream the anode flow field via back diffusion of water from the cathode to the anode, is the only source of water for both membrane hydration and the internal humidification of the cathode gas stream, which passes the cell in opposite direction.
Neural integration of speech and gesture in schizophrenia: Evidence for differential processing of metaphoric gestures
Authors: Straube Benjamin , Green Antonia , Sass Katharina , Kirner‐Veselinovic André , Kircher Tilo
Published: February 2012

Gestures are an important component of interpersonal communication. Especially, complex multimodal communication is assumed to be disrupted in patients with schizophrenia. In healthy subjects, differential neural integration processes for gestures in the context of concrete [iconic (IC) gestures] and abstract sentence contents [metaphoric (MP) gestures] had been demonstrated. With this study we wanted to investigate neural integration processes for both gesture types in patients with schizophrenia. During functional magnetic resonance imaging‐data acquisition, 16 patients with schizophrenia (P) and a healthy control group (C) were shown videos of an actor performing IC and MP gestures and associated sentences. An isolated gesture (G) and isolated sentence condition (S) were included to separate unimodal from bimodal effects at the neural level. During IC conditions (IC > G ∩ IC > S) we found increased activity in the left posterior middle temporal gyrus (pMTG) in both groups. Whereas in the control group the left pMTG and the inferior frontal gyrus (IFG) were activated for the MP conditions (MP > G ∩ MP > S), no significant activation was found for the identical contrast in patients. The interaction of group (P/C) and gesture condition (MP/IC) revealed activation in the bilateral hippocampus, the left middle/superior temporal and IFG. Activation of the pMTG for the IC condition in both groups indicates intact neural integration of IC gestures in schizophrenia. However, failure to activate the left pMTG and IFG for MP co‐verbal gestures suggests a disturbed integration of gestures embedded in an abstract sentence context. This study provides new insight into the neural integration of co‐verbal gestures in patients with schizophrenia. Hum Brain Mapp, 2013. © 2012 Wiley Periodicals, Inc.
Assessing cortical network properties using TMS–EEG
Authors: Rogasch Nigel C. , Fitzgerald Paul B.
Published: February 2012

The past decade has seen significant developments in the concurrent use of transcranial magnetic stimulation (TMS) and electroencephalography (EEG) to directly assess cortical network properties such as excitability and connectivity in humans. New hardware solutions, improved EEG amplifier technology, and advanced data processing techniques have allowed substantial reduction of the TMS‐induced artifact, which had previously rendered concurrent TMS–EEG impossible. Various physiological artifacts resulting from TMS have also been identified, and methods are being developed to either minimize or remove these sources of artifact. With these developments, TMS–EEG has unlocked regions of the cortex to researchers that were previously inaccessible to TMS. By recording the TMS‐evoked response directly from the cortex, TMS–EEG provides information on the excitability, effective connectivity, and oscillatory tuning of a given cortical area, removing the need to infer such measurements from indirect measures. In the following review, we investigate the different online and offline methods for reducing artifacts in TMS–EEG recordings and the physiological information contained within the TMS‐evoked cortical response. We then address the use of TMS–EEG to assess different cortical mechanisms such as cortical inhibition and neural plasticity, before briefly reviewing studies that have utilized TMS–EEG to explore cortical network properties at rest and during different functional brain states. Hum Brain Mapp, 2013. © 2012 Wiley Periodicals, Inc.
Hydrological analysis of the Upper Tiber River Basin, Central Italy: a watershed modelling approach
Authors: Fiseha B. M. , Setegn S. G. , Melesse A. M. , Volpi E. , Fiori A.
Published: February 2012

The quantification of the various components of hydrological processes in a watershed remains a challenging topic as the hydrological system is altered by internal and external drivers. Watershed models have become essential tools to understand the behaviour of a catchment under dynamic processes. In this study, a physically based watershed model called Soil Water Assessment Tool was used to understand the hydrologic behaviour of the Upper Tiber River Basin, Central Italy. The model was successfully calibrated and validated using observed weather and flow data for the period of 1963–1970 and 1971–1978, respectively. Eighteen parameters were evaluated, and the model showed high relative sensitivity to groundwater flow parameters than the surface flow parameters. An analysis of annual hydrological water balance was performed for the entire upper Tiber watershed and selected subbasins. The overall behaviour of the watershed was represented by three categories of parameters governing surface flow, subsurface flow and whole basin response. The base flow contribution has shown that 60% of the streamflow is from shallow aquifer in the subbasins. The model evaluation statistics that evaluate the agreement between the simulated and the observed streamflow at the outlet of a watershed and other three different subbasins has shown a coefficient of determination (R2) from 0.68 to 0.81 and a Nash–Sutcliffe efficiency (ENS) between 0.51 and 0.8 for the validation period. The components of the hydrologic cycle showed variation for dry and wet periods within the watershed for the same parameter sets. On the basis of the calibrated parameters, the model can be used for the prediction of the impact of climate and land use changes and water resources planning and management. Copyright © 2012 John Wiley & Sons, Ltd.
Parametric calibration of the Hargreaves–Samani equation for use at new locations
Authors: Shahidian S. , Serralheiro R.P. , Serrano J. , Teixeira J.L.
Published: February 2012

The Hargreaves–Samani (HS) evapotranspiration equation is very useful for the on‐site irrigation management in data‐short situations such as small and midsize farms and landscaped areas. Although much work has been performed to improve the precision of the evapotranspiration (ETo) estimates for use at new locations, the results have not been consistent and many have not been confirmed by other works. The purpose of this study was to review and to evaluate the seven most promising parameters used for the calibration of the HS evapotranspiration equation, using two different regions: California and Bolivia. The results of this study show that annual correlations between HS and Penman–Monteith can be misleading because the correlation is poor in the humid months and improves progressively along the dry season until the first rains. The average monthly wind speed can be used for both spatial and seasonal calibration of the HS equation, especially during the irrigation season. Elevation and precipitation can be used to calibrate the HS equation when no reference ETo values are available at nearby stations. The monthly value of KT calculated from solar radiation follows a parabolic function along the year and should not be used for improving the estimates of the HS equation because the clearness index produces better results than actual solar radiation measurements. The results also indicate that the use of distance to coast, temperature range and temperature parameter does not improve the precision of the HS equation. Copyright © 2012 John Wiley & Sons, Ltd.
Yukon River Basin long‐term (1977–2006) hydrologic and climatic analysis
Authors: Ge Shaoqing , Yang Daqing , Kane Douglas L.
Published: February 2012

In this study, long‐term discharge data and climate records, such as temperature and precipitation during 1977–2006, have been used to define basin climatic and hydrologic regimes and changes. Discharge analyses at four key gauging stations (Eagle, Stevens Village, Nenana, and Pilot Station) in the Yukon River Basin show that the runoff in the cold season (November to April) is low with small variations, whereas it is high (28 500–177 000 ft3/s; 810–5000 m3/s) with high fluctuations in the warm season (May to October). The Stevens Village Station is in the upper basin and has similar changes with the flow near basin outlet. Flow increases in May (61 074 ft3/s; 1729 m3/s) and September (23 325 ft3/s; 660 m3/s); and decreases in July (35 174 ft3/s; 996 m3/s) and August (6809 ft3/s; 193 m3/s). Discharge in May at the Pilot Station (near the basin outlet) shows a positive trend (177 000 ft3/s; 5010 m3/s). Daily flow analyses show high fluctuation during the warm season and very low flow during the cold season; the 10‐year average analyses of daily flow at Pilot Station show a small increase in the peak and its timing shifted to a little earlier date. The annual flow, average of 227 900 ft3/s (6450 m3/s) with high inter‐annual fluctuations, has increased by 18 200 ft3/s (or 8%; 520 m3/s) during 1977–2006. From 1977 to 2006, basin air temperature in June has increased by 3.9 °F (2.2 °C) and decreased by 10.5 °F (5.8 °C) in January. A strong and positive correlation exists between air temperature in April and discharge in May, whereas a strong and negative correlation relates August temperature and September discharge. Negative trend during 1977–2006 is observed for precipitation in June (0.6 in.; 15 mm) with a confidence over 93%. Precipitation in August and September has strong and positive correlations with discharge in September and October at basin outlet; the precipitation in other months has weak correlation with the discharge. The mean annual precipitation during 1977–2006 increased by 1.1 in. (or 8%; 28 mm), which contributes to the annual flow increase during the study period. Copyright © 2012 John Wiley & Sons, Ltd.
GROSS DOMESTIC PRODUCT GROWTH PREDICTIONS THROUGH THE YIELD SPREAD: TIME‐VARIATION AND STRUCTURAL BREAKS
Authors: Pace Pierangelo De
Published: February 2012

We use time‐varying‐parameter models and real‐time data to describe the evolution of the leading properties of the yield spread for output growth in five European economies and in the USA over the last decades and until the third quarter of 2010. We evaluate the predictive performance of benchmark term‐structure models and identify structural breaks in the marginal processes of term spreads and government bond yields to shed light on the dynamic characteristics of the yield curve. Econometric analysis shows that (i) the predictive content of the term spread is not always significant over time and across countries; (ii) the spread significantly contributes to the forecast performance of simple growth regressions in Europe but not in the USA in recent years; and (iii) the variance of the random shocks to the term spreads tends to fall in all countries. This decline is accompanied by vanishing leading properties from the mid‐1990s. Such properties reappear after 2008. Copyright © 2012 John Wiley & Sons, Ltd.
Acquired immunogenicity of human DNA damaged by N‐hydroxy‐N‐acetyl‐4‐aminobiphenyl
Authors: Shahab Uzma , Moinuddin  , Ahmad Saheem , Dixit Kiran , Abidi S.M. Abbas , Alam Khursheed , Ali Asif
Published: February 2012

4‐Aminobiphenyl, a known carcinogen, has many environmental sources like cigarette smoke, industrial waste, and so forth. It can be metabolized to form a potent mutagen, N‐hydroxy‐N‐acetyl‐4‐aminobiphenyl (N‐OH‐AABP) that undergoes further processing to form electrophilic nitrenium ions which interact with DNA‐forming covalent adducts, thereby exerting genotoxic effects. While the mutagenicity of N‐OH‐AABP has been amply reported, no extensive studies have been performed to assess the immunogenicity of N‐OH‐AABP‐modified DNA. In this study, human placental DNA was modified with N‐OH‐AABP, and the structural perturbations in the DNA molecule were evaluated by ultraviolet spectroscopy and nuclease S1 digestion. Native and N‐OH‐AABP‐modified DNA were used as antigens for immunizing female rabbits. The modified DNA was found to be highly immunogenic, eliciting high titer immunogen‐specific antibodies, while the native form was almost nonimmunogenic. The induced antibodies exhibited wide range of heterogeneity in recognizing various nucleic acid conformers and DNA bases. We also detected deposits of immune complex in glomerular basement membrane in rabbits immunized with N‐OH‐AABP‐DNA. Possible role of N‐OH‐AABP‐DNA in the induction of antibodies in cancer patients and the related consequences have been discussed. © 2012 IUBMB Life, 64(4): 340–345, 2012