bluuebunny/crossref_metadata_2025 huggingface dataset:
ChemInform Abstract: New Methods for Stereochemical Determination of Complex Polyketides: Configurational Assignment of Novel Metabolites from Myxobacteria
Authors: Menche Dirk
Published: December 2008

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform Abstract: ESR Microscopy and Nanoscopy with “Induction” Detection
Authors: Blank Aharon , Freed Jack H.
Published: December 2008

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
A Life Cycle Comparison of Alternative Cheese Packages
Authors: Banar Müfide , Çokaygil Zerrin
Published: December 2008

A comparative life cycle assessment (LCA) between three different cheese packages (P1: completely polypropylene (PP), P2: tin and polyethylene (PE), and P3: carton and PE) has been carried out for the production, distribution and waste disposal (100% landfill) phase. A package for 1 kg of cheese was selected as the functional unit. SimaPro7 software (PRèConsultants, The Netherlands) was used for the LCA study. The EcoIndicator 99 method was selected for comparison of the packages. The comparisons show that the total environmental performance of the cheese package types in order from worst to best is P2, P1, and P3. This conclusion was supported by a sensitivity analysis, which was conducted by using different impact assessment methods.
Temperature Trends and Changes in Rize, Turkey, for the Period 1975 to 2007
Authors: Tecer Lokman Hakan , Cerit Orhan
Published: December 2008

There is increasing evidence that the global climate is changing as a result of anthropogenic activity. Short‐term mean, maximum, and minimum temperatures of the city Rize located at the Eastern Black Sea Coast of Turkey were analyzed to reveal trends, change points, significant warming (cooling) periods, and trend rates per year. An increasing trend of approximately 1.27°C/33 years (α = 0.001) in the annual mean temperatures is found during the period from 1975 to 2007. Two periods, averaging 13.78 and 14.66°C, respectively, were detected from fluctuation in the annual mean temperatures. The trend of the first period (1975–1993) is towards a cooler climate, whereas the trend of the second period (1994–2007) is towards a warmer climate. Summer, autumn and, particularly, the spring mean temperatures have tended to increase strongly, whereas the winter mean temperatures have increased slightly over the whole period. For the winter mean temperature, the trend rate indicates a slight increase, which is insignificant. Maximum temperatures have dramatically increased with 1.61°C (α = 0.001) over the last 33 years. However, annual minimum temperatures have increased by 0.99°C (α = 0.01) over the same period.
Similarity‐Based Virtual Screening with a Bayesian Inference Network
Authors: Abdo Ammar , Salim Naomie
Published: December 2008

An inference network model for molecular similarity searching: The similarity search problem is modeled using inference or evidential reasoning under uncertainty. The inference network model treats similarity searching as an evidential reasoning process in which multiple sources of evidence about compounds and reference structures are combined to estimate resemblance probabilities.

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Many methods have been developed to capture the biological similarity between two compounds for use in drug discovery. A variety of similarity metrics have been introduced, the Tanimoto coefficient being the most prominent. Many of the approaches assume that molecular features or descriptors that do not relate to the biological activity carry the same weight as the important aspects in terms of biological similarity. Herein, a novel similarity searching approach using a Bayesian inference network is discussed. Similarity searching is regarded as an inference or evidential reasoning process in which the probability that a given compound has biological similarity with the query is estimated and used as evidence. Our experiments demonstrate that the similarity approach based on Bayesian inference networks is likely to outperform the Tanimoto similarity search and offer a promising alternative to existing similarity search approaches.
A new method for the aqueous functionalization of superparamagnetic Fe2O3 nanoparticles
Authors: Herranz Fernando , Morales Mª. Puerto , Roca Alejandro G. , Vilar Ramón , Ruiz‐Cabello Jesús
Published: December 2008

A new methodology for the synthesis of hydrophilic iron oxide nanoparticles has been developed. This new method is based on the direct chemical modification of the nanoparticles' surfactant molecules. Using this methodology both USPIO (ultrasmall super paramagnetic iron oxide) (hydrodynamic size smaller than 50 nm) and SPIO (super paramagnetic iron oxide) (hydrodynamic size bigger than 50 nm) were obtained. In addition, we also show that it is possible to further functionalize the hydrophilic nanoparticles via covalent chemistry in water. The magnetic properties of these nanoparticles were also studied, showing their potential as MRI contrast agents. Copyright © 2008 John Wiley & Sons, Ltd.
New synthesis of a high molecular weight ligand derived from dota; thermodynamic stability of the MRI contrast agent formed with gadolinium
Authors: Pierrard Jean‐Claude , Rimbault Jean , Aplincourt Michel , Le Greneur Soizic , Port Marc
Published: December 2008

The new total synthesis in four steps of the compound P1041 is reported. This compound is a high molecular mass ligand (MW 6.32 kDa) derived from dota in which the four substituents are hydroxylated and contain amidic groups. The attribution of the nine protonation constants of P1041 is based on the comparison with the behaviour of the precursor ligands dota and tced, a tetracarboxylated derivative of dota. From these results, the studies of the systems P1041/Na+ and P1041/Gd3+ lead to the determination of the stability constants corresponding to the three species Na(P1041)Hh (h = 0, 2 or 4) and to the five complexes Gd(P1041)Hh (h = 0, 2, 3, 4 or 5). The complexing ability of P1041 towards Gd3+ is compared with those of dota and tced. At physiological pH = 7.4, the very stable species Gd(P1041)H (currently named P792 in the literature) of this rapid clearance blood pool agent is predominant. Copyright © 2008 John Wiley & Sons, Ltd.
Imaging Local Proton Fluxes through a Polycarbonate Membrane by Using Scanning Electrochemical Microscopy and Functionalized Alkanethiols
Authors: Baltes Norman , Heinze Jürgen
Published: December 2008

A new application of scanning electrochemical microscopy (SECM) to probe the transport of protons through membranes is described. Herein, a probe ultramicroelectrode (UME) is modified with a self‐assembled monolayer (SAM) of 11‐mercaptoundecanoic acid to qualitatively image areas within different pH regions above a track‐etched membrane. The current response of the modified electrode in the presence of potassium hexacyanoferrate as electroactive component is different in acidic and alkaline solutions. Depending on the pH value of the solution, the SAM‐covered electrode exposes either a neutral or a negatively charged insulating monolayer at pH 3 or 7, respectively, which leads to an increase/decrease in the faradaic current due to electrostatic interactions between the neutral/charged surface and the charged redox mediator. Therefore, local pH changes in the close vicinity of a membrane‐like substrate lead to different current responses recorded at the tip electrode when scanning above the surface.
A new organic‐inorganic molybdenum arsenate complex based on [(CuO6)(As3O3)2Mo6O18]4‐ cluster as secondary building units
Authors: Su Fangyong , Zhou Baibin , Zhao Zhifeng , Su Zhanhua , Zhu Chuncheng
Published: December 2008

A new molybdenum arsenate, [Cu(imi)2]2[(CuO6)(As3O3)2Mo6O18][Cu(imi)2]2 (1) (imi = C3N2H4), has been synthesized under mild hydrothermal conditions, and characterized by elemental analysis, IR, thermogravimetric analyses, and single‐crystal X‐ray diffraction analysis. The polyanion framework derives from the Anderson structure in which the central octahedron is filled up by a copper (II), and is capped on both sides by two cyclic As3O6 groups. The countercations contain bisupported [Cu(imi)2]+ complex cations and two free [Cu(imi)2]+ complex cations. The electrochemical behavior of 1‐modified carbon paste electrode (1‐CPE) has been studied in detail. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Pressure Broadening of Lyman‐Lines in Dense Li2+ Plasmas
Authors: Lorenzen S. , Wierling A. , Reinholz H. , Röpke G.
Published: December 2008

Pressure broadening of Lyman‐lines of hydrogen‐like lithium is studied using a quantum statistical approach to the line shape in dense plasmas. We report line widths (FWHM) and shifts for Lα , Lβ , and Lγ in a wide range of densities and temperatures relevant for laser‐produced lithium plasmas. We estimate the influence of ion dynamics and strong collisions. The results are applied to measured spectra of lithium irradiated by a nanosecond laser pulse of moderate intensities (I ≈ 1011 – 1013 W/cm2), see G. Schriever et al. [1, 2]. By matching synthetic spectra to the experimental ones, density and temperature conditions are inferred assuming the model of a one‐dimensional uniform plasma slab. This allows for a more precise estimate of the density compared to the results reported earlier. Self‐absorption is accounted for and found to be important for Lα . (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Attention‐Deficit Hyperactivity Disorder in the context of a high intellectual quotient/giftedness
Authors: Antshel Kevin M.
Published: December 2008

The diagnosis of Attention‐Deficit Hyperactivity Disorder (ADHD) in children with a high intellectual quotient (IQ) and/or giftedness is controversial with many opinions existing on both sides of the debate. Relationships between IQ and cognitive vulnerabilities frequently described in the ADHD population vary in strength. Data asserting the validity of ADHD in the high IQ/giftedness population are discussed with comparisons made to average IQ ADHD. Educational implications of having ADHD in thecontext of a high IQ/giftedness are presented. © 2008 Wiley‐Liss, Inc. Dev Disabil Res Rev 2008;14:293–299.
Peer problems in Attention Deficit Hyperactivity Disorder: Current status and future directions
Authors: McQuade Julia D. , Hoza Betsy
Published: December 2008

This article extends previous reviews regarding the peer problems of children with Attention Deficit Hyperactivity Disorder (ADHD) in several ways. In addition to summarizing past and current literature regarding the social behaviors of children with ADHD, these behaviors are discussed in terms of subtype and gender differences and treatment implications. Given limited effectiveness of treatment options, whether it be medication, behavioral modification, or social skills training, there is a need to examine additional factors that may contribute to the social impairment of children with ADHD. Therefore, this review focuses on potential neuropsychological deficits, biased perceptions of social ability, and deficits in encoding and processing social information that may contribute to the social impairment of children with ADHD. These topics are discussed both in terms of their contribution to our understanding of the peer problems of children with ADHD and as potential avenues for future research. © 2008 Wiley‐Liss, Inc. Dev Disabil Res Rev 2008;14:320–324.
Psychosocial treatments for preschool‐aged children with Attention‐Deficit Hyperactivity Disorder
Authors: LaForett Doré R. , Murray Desiree W. , Kollins Scott H.
Published: December 2008

This article reviews the research literature on psychosocial treatments for preschool‐aged children with Attention‐Deficit Hyperactivity Disorder (ADHD) in the context of the developmental and contextual needs of this population (e.g., increased parenting demands, differences in classroom structure, and the child's emerging developmental capacities). Discussion of the findings and limitations of existing studies is provided for parent‐training approaches, classroom management strategies, and multimodal treatments. Although the empirical base is quite small for ADHD‐specific samples, parent‐training interventions have the greatest overall support for improving behavioral outcomes, with a variety of different approaches having shown effectiveness. Very few studies of classroom management and multimodal interventions have been conducted in this age group; however, initial data show promising results for teacher training and consultation interventions. The body of research suggests that the most effective treatments for clinical samples of preschoolers with ADHD and their families may be individually delivered, developmentally appropriate, and multimodal. © 2008 Wiley‐Liss, Inc. Dev Disabil Res Rev 2008;14:300–310.
Inhibitory functioning across ADHD subtypes: Recent findings, clinical implications, and future directions
Authors: Adams Zachary W. , Derefinko Karen J. , Milich Richard , Fillmore Mark T.
Published: December 2008

Although growing consensus supports the role of deficient behavioral inhibition as a central feature of the combined subtype of ADHD (ADHD/C; Barkley 1997 Psychol Bull 121:65–94; Nigg 2001 Psychol Bull 127:571–598), little research has focused on how this finding generalizes to the primarily inattentive subtype (ADHD/I). This question holds particular relevance in light of recent work suggesting that ADHD/I might be better characterized as a disorder separate from ADHD/C (Diamond 2005 Dev Psychopathol 17:807–825; Milich et al. 2001 Clin Psychol Sci Pract 8:463–488). This article describes major findings in the area of inhibitory performance in ADHD and highlights recent research suggesting important areas of divergence between the subtypes. In particular, preliminary findings point to potential differences between the subtypes with respect to how children process important contextual information from the environment, such as preparatory cues that precede responses and rewarding or punishing feedback following behavior. These suggestive findings are discussed in the context of treatment implications, which could involve differential intervention approaches for each subtype targeted to the specific deficit profiles that characterize each group of children. Future research avenues aimed toward building a sound theoretical model of ADHD/I and a better understanding of its relation to ADHD/C are also presented. Specifically, investigators are encouraged to continue studying the complex interplay between inhibitory and attentional processes, as this area seems particularly promising in its ability to improve our understanding of the potentially distinct pathologies underlying the ADHD subtypes. © 2008 Wiley‐Liss, Inc. Dev Disabil Res Rev 2008;14:268–275.
ADHD in college students: Developmental findings
Authors: Weyandt Lisa L. , DuPaul George J.
Published: December 2008

According to the American Psychiatric Association [DSM‐IV‐TR, 2000], Attention‐Deficit Hyperactivity Disorder (ADHD) affects ∼3–7% of the school aged population and 2–4% of the adult population. Recently, college students with ADHD have begun to receive more attention, largely due to the increase in numbers of high school students with ADHD pursuing higher education, as well as reports of prescription stimulant misuse on college campuses. The purpose of the present article is to summarize major research findings concerning developmental issues facing college students with ADHD. Overall, findings suggest that relative to the general college population, college students with ADHD are at greater risk for academic and psychological difficulties, and misuse of prescription stimulants is indeed a problem on many campuses. Primary treatment strategies include psychostimulant medication, coaching, and educational accommodations; however, very little controlled treatment outcome research has been conducted with this population. These findings are preliminary and are tempered by methodological limitations as well as the small number of studies that have been conducted. Future research using larger sample sizes, rigorous assessment criteria, and employing longitudinal designs is needed to better understand the developmental issues facing college students with ADHD. © 2008 Wiley‐Liss, Inc. Dev Disabil Res Rev 2008;14:311–319.
Enhancing academic achievement for children with Attention‐Deficit Hyperactivity Disorder: Evidence from school‐based intervention research
Authors: Jitendra Asha K. , DuPaul George J. , Someki Fumio , Tresco Katy E.
Published: December 2008

Although children with Attention‐Deficit Hyperactivity Disorder (ADHD) exhibit significant academic difficulties in school settings, considerably less attention is devoted to remediating their academic problems when compared to behavioral and social difficulties. The purpose of this article is to review empirically supported academic interventions for children with ADHD. Specific evidence‐based academic interventions are described under the categories of reading and mathematics, with examples that illustrate teacher‐mediated interventions focusing on basic skills (e.g., phonological awareness in reading, mathematics computation) and higher‐level cognitive skills (e.g., collaborative strategic reading, CSR; schema‐based instruction, SBI). Finally, implications for educational practice and directions for future research on school‐based academic interventions for students with ADHD are discussed. © 2008 Wiley‐Liss, Inc. Dev Disabil Res Rev 2008; 14:325–330.
Attention deficits, Attention‐Deficit Hyperactivity Disorder, and intellectual disabilities
Authors: Deutsch Curtis K. , Dube William V. , McIlvane William J.
Published: December 2008

Attention‐Deficit Hyperactivity Disorder (ADHD) and its earlier nosologic classifications have been extensively investigated since the 1960s, with PubMed listings alone exceeding 13,000 entries. Strides have been made in the diagnosis and treatment of ADHD in individuals with intellectual function in the normal range, as described in companion reviews in this special issue. In contrast, comparatively little is known about ADHD in intellectual developmental disabilities (IDD) despite the possibility that ADHD is statistically overrepresented among individuals with IDD (Pearson et al. 1997 Attention‐deficit/hyperactivity disorder in mental retardation: nature of attention deficits. In: Burack J, Enns J, editors. Attention, development, and psychopathology. New York: Guilford Press. p 205–229; Pearson et al. 2000 Am. J. Ment. Retard. 105:236–251). Here, we provide a review of diagnostic controversies in ADHD with IDD, and discuss several topics that are currently attracting research efforts in the field. These include behavioral phenotyping and attempts to come to grips with problems of behavioral and etiological heterogeneity. Additionally, we consider issues relating to methodologically sound assessment of attention disorders and evidence‐based intervention procedures that may clarify and/or ameliorate attention deficits in individuals with IDD. © 2008 Wiley‐Liss, Inc. Dev Disabil Res Rev 2008;14:285–292.
Neue Bemessungsregeln für aufgeklebte Verstärkungen mit CFK‐Lamellen
Authors: Breitschaft Gerhard , Wittig Katrin , Alex Rolf
Published: December 2008

1. Kurzer Rückblick der Entwicklung der Bemessungsmodelle

2. Umsetzung der Nachweiskonzepte

2.1 Querkraftkonzept nach DIN 1045‐1

2.2 Verbundnachweis bei Stützmomentenverstärkung

3. Beispielrechnung eines durch aufgeklebte CFK‐Lamellen verstärkten Zweifeldbalkens nach den geltenden Zulassungen auf Basis von DIN 1045‐1:2008‐08
Mixed Valency at the Nearly Delocalized Limit: Fundamentals and Forecast
Authors: Glover Starla D. , Goeltz John C. , Lear Benjamin J. , Kubiak Clifford P.
Published: December 2008

Mixed valency is important in many areas of chemistry, from synthetic to biological systems, from the simplest systems to the most highly complex. The purpose of our research is to understand the principles of mixed valency in localized, nearly delocalized, and delocalized systems, and to apply our knowledge to the rational design of molecular devices. This microreview discusses our group's research over the last ten years. It reviews methods of estimating picosecond electron‐transfer lifetimes from infrared spectral lineshapes, studies of the localized‐to‐delocalized transition and the effects of frozen solvents, charge gating by non‐covalent interactions, electron‐transfer‐gated electron transfer, and the distribution of charge within a molecule probed and controlled by an applied electric field. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)
Synthesis and Structure of Aminopyridinato‐Stabilized Yttrium and Lanthanum Amides and Their Reactivity towards Alkylaluminium Compounds
Authors: Döring Christian , Kempe Rhett
Published: December 2008

A series of aminopyridinato‐stabilized (amido)lanthanide complexes has been synthesized and characterized. The bulky aminopyridines (2,6‐diisopropylphenyl)[6‐(2,4,6‐triisopropylphenyl)pyridin‐2‐yl]amine (1a) and [6‐(2,4,6‐triisopropylphenyl)pyridin‐2‐yl](2,4,6‐trimethylphenyl)amine (1b) were introduced by amine elimination reaction with [Ln{N(SiHMe2)2}3(thf)2] (Ln = Y, La, thf = tetrahydrofuran, Me = methyl) to obtain the corresponding mono(aminopyridinato) complexes. Single‐crystal X‐ray analyses were carried out for the yttrium derivatives. The complexes are not able to undergo coordinative chain transfer polymerization with ethylene in the presence of alkylaluminium compounds as the corresponding dialkyl complexes do. Investigations of the reactions of the lanthanide aminopyridinato complexes with triethylaluminium or diisobutylaluminium hydride reveal a fast transfer of the aminopyridinato ligand to the aluminium atom. The products of this transfer reaction are aminopyridinato‐stabilized dialkylaluminium compounds. One example of these aluminium complexes was characterized by X‐ray crystal structure analysis. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)
Self‐Assembled Transition‐Metal Macrocycles and Two‐Dimensional Coordination Polymers Derived from Flexible C2Co2 Cluster‐Bridged Bipyridine Ligands [(4‐C5H4NCO2CH2)2C2Co2(CO)6] and [(3‐C5H4NCO2CH2)2C2Co2(CO)6]
Authors: Song Li‐Cheng , Jin Guo‐Xia , Zhao Li‐Qun , Wang Hu‐Ting , Zhang Wen‐Xiong , Hu Qing‐Mei
Published: December 2008

Reactions of the tetrahedral C2Co2 cluster‐bridged bipyridine ligand [(4‐C5H4NCO2CH2)2C2Co2(CO)6] (La) with [{M(dppb)(H2O)2}(OTf)2] (M = Pd, Pt; dppb = 1,4‐bis(diphenylphosphanyl)butane; OTf = SO3CF3) and AgX (X = NO3, SbF6) gave cationic metallamacrocycles [{M(dppb)La}2(OTf)4] (1, M = Pd; 2, M = Pt) and [(AgLa)2X2] (3, X = NO3; 4, X = SbF6). Furthermore, the isomeric C2Co2 cluster‐bridged bipyridine ligand [(3‐C5H4NCO2CH2)2C2Co2(CO)6] (Lb) reacted with ZnCl2 and AgX (X = PF6, ClO4) to afford cationic macrocycle [(ZnLbCl2)2] (5) and coordination polymers [(AgLbX)n] (6, X = PF6; 7, X = ClO4), respectively. Whereas flexible ligand La is known, Lb is new and could be prepared by reaction of but‐2‐yne‐1,4‐diyl dipyridine‐3‐carboxylate with [Co2(CO)8]. New self‐assembled products 1–7 and ligand Lb were characterized by elemental analysis and spectroscopy, and 1, 3–7, and Lb were additionally characterized by X‐ray crystallography. In addition, the electrochemistry of Lb and 5 were studied by cyclic voltammetry. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)
Analysis of biomarkers from lipid peroxidation: A comparative study
Authors: Guichardant Michel , Lagarde Michel
Published: December 2008

Oxidative stress is associated with an increase of reactive oxygen species and is now recognized to be a prominent feature of many acute and chronic diseases, as well as of the normal aging process. Many biomarkers are now available to assess oxidative stress. We discuss here the most commonly used in terms of specificity and sensitivity. Some data regarding their validation and measurement are also provided. In addition, we propose new biomarkers deriving from lipid peroxidation, namely 4‐hydroxy‐alkenals and their oxidized derivatives, which can be measured in urine. The main advantages of those markers are that 4‐hydroxy‐hexenal and 4‐hydroxy‐nonenal as well as their oxidized derivatives can be determined in one run, providing information on the global peroxidation of n‐3 and n‐6 polyunsaturated fatty acids, respectively. Moreover, 4‐hydroxy‐hexaenoic and 4‐hydroxy‐nonenoic acids, measurable in urine, are non‐invasive biomarkers that give an indication of the oxidative stress. In conclusion, taking into account the limitations of the different biomarkers available, more than one biomarker should be measured in a particular sample to obtain an overview on the oxidative stress.
Esters of Feist's Acid: Some Insights into the Electronic Structure and Reactivity of Methylenecyclopropanes Ring‐Substituted with Acceptor Groups
Authors: Diev Vyacheslav V. , Tung Tran Q. , Molchanov Alexander P.
Published: December 2008

1,3‐Dipolar cycloaddition of C‐aryl‐N‐aryl‐ or N‐methylnitrones with esters of Feist's acid (3‐methylenecyclopropane‐trans‐1,2‐dicarboxylic acid) occurs with the formation of the corresponding spiro[cyclopropane‐1,4‐isoxazolidine] cycloadducts as single isomer with yields in the range of 17–59 %. The reaction proceeds with inverse regiochemical outcome compared to cycloadditions with unsubstituted methylenecyclopropane. Feist's esters are significantly less active towards cycloaddition with nitrones than methylenecyclopropane and reactions require prolonged heating at elevated temperature. The electronic structures of Feist's esters were investigated by means of molecular photoelectron spectroscopy and theoretical calculations (HF/6‐31G*, B3LYP/6‐31G*). Both, measured photoelectron HeI spectrum and ground state calculations (HF/6‐31G*) of Feist's esters, indicate considerable lowering of the methylenecyclopropane π‐HOMO energies by substitution with an acceptor group. B3LYP calculations of addends and transition states forthe interaction of methylenecyclopropane with C,N‐diphenylnitrone correctly predict regiochemical outcome. However, B3LYP calculations do not account for the observed regiochemical outcome and diminished reactivity in reactions of Feist's esters with C,N‐diphenylnitrone.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)
Cyclam‐Functionalized Silica‐Modified Electrodes for Selective Determination of Cu(II)
Authors: Goubert‐Renaudin Stéphanie , Etienne Mathieu , Rousselin Yoann , Denat Franck , Lebeau Bénédicte , Walcarius Alain
Published: December 2008

Cyclam derivatives have been grafted via 1, 2 or 4 silylated arms to the surface of mesoporous silica and the resulting materials have been incorporated into carbon paste electrodes and applied to the preconcentration electroanalysis of Cu(II). Sensitive and selective detection of the target analyte was achieved owing to the attractive binding properties of this macrocyclic ligand towards Cu(II) species. Various parameters likely to affect the preconcentration and detection steps have been studied, including pH of the accumulation medium, composition of the detection solution, structure and composition of the adsorbent, accumulation time, or presence of potentially interfering species. In particular, the effect of the number of silylated groups linking the macrocycle to the silica network on the sensor performance was discussed. After optimization, Cu(II) can be determined in a linear concentration range extending from 2 nM to 100 μM. The method was validated by reliable Cu(II) determination in tap water.
The Heterogeneity of Multiwalled and Single‐Walled Carbon Nanotubes: Iron Oxide Impurities Can Catalyze the Electrochemical Oxidation of Glucose
Authors: Siegert Laurent , Kampouris Dimitrios K. , Kruusma Jaanus , Sammelselg Väino , Banks Craig E.
Published: December 2008

It is well established that the heterogeneity of carbon nanotubes must be determined before the origin of the electrochemical performance can be attributed. Recently it has been diligently reported that for the case of multiwalled carbon nanotube modified electrodes, copper oxide impurities are responsible for the electrochemical activity facilitating a nonenzymatic sensing strategy towards glucose. We have explored both commercially available multiwalled and single‐walled carbon nanotubes for the sensing of glucose and find that iron oxide impurities remaining from the fabrication process are the electroactive sites facilitating the nonenzymatic detection of glucose. Given that the multiwalled carbon nanotubes in this work are purchased from the same leading supplier as that used recently, discrepancies in the fabrication process exist which clearly has implications in the commercialization of electrochemical sensors based on multiwalled carbon nanotubes.
Simultaneous Voltammetry Determination of Dihydroxybenzene Isomers by Nanogold Modified Electrode
Authors: Han Lu , Zhang Xiaoli
Published: December 2008

A convenient electrochemical deposition method to prepare nanogold/glassy carbon modified electrode (nano‐Au/GCE) is adopted. In 0.1 mol/L HAc‐NaAc buffer solution (pH 4.61), the nano‐Au/GCE shows an excellent electrocatalytical behavior for the redox of dihydroxybenzene. A simple, rapid and highly selective voltammetry for simultaneous determination of dihydroxybenzene isomers, hydroquinone, catechol, and resorcinol, is developed using the nano‐Au/GCE. This method has been applied to the direct determination of the three dihydroxybenzene isomers in artificial wastewater.
Electrochemical Properties of a Boron‐Doped Diamond Electrode Modified with Gold/Polyelectrolyte Hollow Spheres
Authors: Wei Min , Xie Zhuoying , Sun Liguo , Gu Zhong‐Ze
Published: December 2008

Oppositely charged polyelectrolyte (poly(allyamine hydrochloride) (PAH) and poly(sodium 4‐styrene‐sulfonate) (PSS)), and negatively charged gold nanoparticles (Au) were assembled alternately on polystyrene (PS) spheres via layer‐by‐layer technique, and the different PAH/(PSS/PAH)n/(Au/PAH)m/Au composite hollow spheres were derived by dissolving PS core. These hollow spheres were used to modify boron‐doped diamond (BDD) electrodes for electrochemical sensors. The cyclic voltammetric results for dopamine (DA) detection demonstrated that hollow‐sphere‐modified BDD exhibited better electrocatalytic activity than did bare BDD. Influence of the wall thickness and composition of hollow spheres on electrochemical properties were investigated. The results showed that the oxidative peak potential of DA and the peak current varied with different PSS/PAH and Au/PAH layers. The optimized wall structure of hollows spheres was PAH/(PSS/PAH)7/(Au/PAH)5/Au.
Chemical Adsorption onto an ITO Substrate of Single‐Wall Carbon Nanotube Functionalized by Carboxylic Groups as an Efficient Support for Electrocatalyst
Authors: Sone Koji , Yagi Masayuki
Published: December 2008

A single‐wall carbon nanotube functionalized by carboxylic groups (SWNT‐CA) was found to be adsorbed on an indium tin oxide (ITO) electrode by chemical interaction between carboxylic groups and the ITO surface. The adsorption experiments indicated that the narrow pH conditions (around pH 3.0) exist for its adsorption which is restricted by preparation of stable fluid dispersion (favorable at higher pH) and by the chemical interaction (favorable at lower pH). Atomic force microscopic (AFM) measurements suggest that fragmented SWNT‐CA are adsorbed, primarily lying on the surface. Electrochemical impedance analysis indicated that an electrochemical double layer capacitance of the SWNT‐CA/ITO electrode is considerably higher than that for the ITO electrode, suggesting that the interfacial area between the electrode surface and the electrolyte solution is enlarged by the SWNT‐CA layer. Pt particles were deposited as a catalyst on the bare ITO and SWNT‐CA‐coated ITO (SWNT‐CA/ITO) electrodes to give respective Pt‐modified electrodes (denoted as a Pt/ITO electrode and a Pt/SWNT‐CA/ITO electrode, respectively). The cathodic current for the Pt/SWNT‐CA/ITO electrode was 1.7 times higher than that for the Pt/ITO electrode at 0.0 V, showing that the Pt/SWNT‐CA/ITO electrode works more efficiently for O2 reduction at 0.0 V due to the SWNT‐CA layer. The enhancement by the SWNT‐CA layer is also effective for electrocatalytic proton reduction. It could be ascribable to the enlarged interfacial area between the electrode surface and the electrolyte solution.
The back and forth nudging algorithm applied to a shallow water model, comparison and hybridization with the 4D‐VAR
Authors: Auroux D.
Published: December 2008

We study in this paper a new data assimilation algorithm, called the back and forth nudging (BFN). This scheme has been very recently introduced for simplicity reasons, as it does not require any linearization, or adjoint equation, or minimization process in comparison with variational schemes, but nevertheless it provides a new estimation of the initial condition at each iteration. We study its convergence properties as well as efficiency on a 2D shallow water model. All along the numerical experiments, comparisons with the standard variational algorithm (called 4D‐VAR) are performed. Finally, a hybrid method is introduced, by considering a few iterations of the BFN algorithm as a preprocessing tool for the 4D‐VAR algorithm. We show that the BFN algorithm is extremely powerful in the very first iterations and also that the hybrid method can both improve notably the quality of the identified initial condition by the 4D‐VAR scheme and reduce the number of iterations needed to achieve convergence. Copyright © 2008 John Wiley & Sons, Ltd.
Application of Electrochemical Impedance Spectroscopy for Fuel Cell Characterization: PEFC and Oxygen Reduction Reaction in Alkaline Solution
Authors: Wagner N. , Friedrich K. A.
Published: December 2008

The most common method used to characterise the electrochemical performance of fuel cells is the recording of current/voltage U(i) curves. Separation of electrochemical and ohmic contributions to the U(i) characteristics requires additional experimental techniques like electrochemical impedance spectroscopy (EIS). The application of EIS is an approach to determine parameters which have proved to be indispensable for the characterisation and development of all types of fuel cell electrodes and electrolyte electrode assemblies [1]. In addition to EIS semi‐empirical approaches based on simplified mathematical models can be used to fit experimental U(i) curves [2].

By varying the operating conditions of the fuel cell and by the simulation of the measured EIS with an appropriate equivalent circuit, it is possible to split the cell impedance into electrode impedances and electrolyte resistance. Integration in the current density domain of the individual impedance elements enables the calculation of the individual overpotentials in the fuel cell (PEFC) and the assignment of voltage loss to the different processes. In case of using a three electrode cell configuration with a reference electrode, one can directly determine the corresponding overvoltage. For the evaluation of the measured impedance spectra the porous electrode model of Göhr [3] was used. This porous electrode model includes different impedance contributions like impedance of the interface porous layer/pore, interface porous layer/electrolyte, interface porous layer/bulk, impedance of the porous layer and impedance of the pores filled by electrolyte.
Tunnelkette Perschling – Reiserbergtunnel and Stierschweiffeldtunnel: TBM Success under Difficult Ground Conditions
Authors: Bach Dietmar , Fuchs Werner , Lehner Wolfgang , Obermeier Oskar
Published: December 2008

Due to the very difficult geological conditions and the partly low overburden the TBM drives of the “Tunnelkette Perschling” have been a challenge for the persons involved in the project. This paper is a report on the experiences and conclusions gained from two of the three driven tunnels. It deals with the unexpected major occurrences and the related solutions as well as with the adjustment of the concept for backfilling the annular gap in order to achieve sufficient stabilization of the segmental tunnel lining under all conditions encountered.
Extension Hieflau HEP – Economical Solutions for the Headrace Tunnel
Authors: Walter Andreas , Weber Wolfgang , Gappmaier Franz
Published: December 2008

The expansion project for the Hieflau hydropower plant involves the construction of a second headrace tunnel to enhance the capacity from 60 up to 90 m3/s. The second tunnel, located between the weir system Gstatterboden and storage reservoir Wag, is seen as the highlight of the enhancement scheme. The breakthrough of the 4,9 km long TBM‐drive is expected by end of this year.
Technical Challenges During Construction of Alborz Service Tunnel, Iran
Authors: Wenner Dieter , Wannenmacher Helmut
Published: December 2008

The Tehran Shomal Motorway project is one the major infrastructure projects currently ongoing in Iran. The line will connect the capital of Iran, Tehran with the Caspian Sea. The traffic volume is very high and the conditions of the actual roads, especially in the winter and holiday times are dangerous. The Alborz tunnel system, with the actual ongoing excavation of its service tunnel, is the outstanding lot of the Tehran Shomal Motorway project. The project is facing severe and adverse geological conditions like various dangerous gases, water and material inrush and blocked TBM. Depending on the conditions at the remaining length the breakthrough is anticipated by early 2009.
Heading‐vector navigation based on head‐direction cells and path integration
Authors: Kubie John L. , Fenton André A.
Published: December 2008

Insect navigation is guided by heading vectors that are computed by path integration. Mammalian navigation models, on the other hand, are typically based on map‐like place representations provided by hippocampal place cells. Such models compute optimal routes as a continuous series of locations that connect the current location to a goal. We propose a “heading‐vector” model in which head‐direction cells or their derivatives serve both as key elements in constructing the optimal route and as the straight‐line guidance during route execution. The model is based on a memory structure termed the “shortcut matrix,” which is constructed during the initial exploration of an environment when a set of shortcut vectors between sequential pairs of visited waypoint locations is stored. A mechanism is proposed for calculating and storing these vectors that relies on a hypothesized cell type termed an “accumulating head‐direction cell.” Following exploration, shortcut vectors connecting all pairs of waypoint locations are computed by vector arithmetic and stored in the shortcut matrix. On re‐entry, when local view or place representations query the shortcut matrix with a current waypoint and goal, a shortcut trajectory is retrieved. Since the trajectory direction is in head‐direction compass coordinates, navigation is accomplished by tracking the firing of head‐direction cells that are tuned to the heading angle. Section 1 of the manuscript describes the properties of accumulating head‐direction cells. It then shows how accumulating head‐direction cells can store local vectors and perform vector arithmetic to perform path‐integration‐based homing. Section 2 describes the construction and use of the shortcut matrix for computing direct paths between any pair of locations that have been registered in the shortcut matrix. In the discussion, we analyze the advantages of heading‐based navigation over map‐based navigation. Finally, we survey behavioral evidence that nonhippocampal, heading‐based navigation is used in small mammals and humans. © 2008 Wiley‐Liss, Inc.
Long‐term deficits on a foraging task after bilateral vestibular deafferentation in rats
Authors: Zheng Yiwen , Goddard Matthew , Darlington Cynthia L. , Smith Paul F.
Published: December 2008

Animal studies have shown that bilateral vestibular deafferentation (BVD) causes deficits in spatial memory that may be related to electrophysiological and neurochemical changes in the hippocampus. Recently, human studies have also indicated that human patients can exhibit spatial memory impairment and hippocampal atrophy even 8–10 yr following BVD. Our previous studies have shown that rats with unilateral vestibular deafferentation (UVD) showed an impairment at 3 months after the surgery on a food foraging task that relies on hippocampal integration of egocentric cues, such as vestibular information; however, by 6 months postop, they showed a recovery of function. By contrast, the long‐term effects of BVD on spatial navigation have never been well studied. In this study, we tested BVD or sham rats on a food foraging task at 5 months postop. Under light conditions, BVD rats were able to use visual cues to guide themselves home, but did so with a significantly longer homing time. However, in darkness, BVD rats were severely impaired in the foraging task, as indicated by a significantly longer homing distance and homing time, with more errors and larger heading angles when compared with sham rats. These results suggest that, unlike UVD, BVD causes long‐term deficits in spatial navigation that are unlikely to recover, even with repeated T‐maze training. © 2008 Wiley‐Liss, Inc.
Efficient table lookup without inverse square roots for calculation of pair wise atomic interactions in classical simulations
Authors: Nilsson Lennart
Published: December 2008

A major bottleneck in classical atomistic simulations of biomolecular systems is the calculation of the pair wise nonbonded (Coulomb, van der Waals) interactions. This remains an issue even when methods are used (e.g., lattice summation or spherical cutoffs) in which the number of interactions is reduced from O(N2) to O(NlogN) or O(N). The interaction forces and energies can either be calculated directly each time they are needed or retrieved using precomputed values in a lookup table; the choice between direct calculation and table lookup methods depends on the characteristics of the system studied (total number of particles and the number of particle kinds) as well as the hardware used (CPU speed, size and speed of cache, and main memory). A recently developed lookup table code, implemented in portable and easily maintained FORTRAN 95 in the CHARMM program (www.charmm.org), achieves a 1.5‐ to 2‐fold speedup compared with standard calculations using highly optimized FORTRAN code in real molecular dynamics simulations for a wide range of molecular system sizes. No approximations other than the finite resolution of the tables are introduced, and linear interpolation in a table with the relatively modest density of 100 points/Å2 yields the same accuracy as the standard double precision calculations. For proteins in explicit water a less dense table (10 points/Å2) is 10–20% faster than using the larger table, and only slightly less accurate. The lookup table is even faster than hand coded assembler routines in most cases, mainly due to a significantly smaller operation count inside the inner loop. © 2008 Wiley Periodicals, Inc. J Comput Chem, 2009
Trends in heavy precipitation in the Czech Republic over 1961–2005
Authors: Kyselý Jan
Published: December 2008

Trends in multiple characteristics of heavy precipitation over the area of the Czech Republic are evaluated using a new dataset from 175 rain‐gauge stations covering the period 1961–2005. The temporal changes are generally more pronounced in the western than eastern part of the country. Spatially coherent increasing trends are identified for all indices of heavy precipitation in winter in the western region, the relative trend magnitudes being mostly between 20 and 30% over the 45 years. Increasing but insignificant and spatially less coherent trends in heavy precipitation prevail also in summer. Opposite trends occur in spring (when they are related to declines in seasonal precipitation totals), and the changes are spatially least coherent and insignificant in autumn (in spite of the increase in mean precipitation). The differences between winter and summer on the one hand and the transition seasons on the other highlight the need for involving spring and autumn into studies of temporal changes of climatic variables, to avoid simplified views. It is also shown that trends in heavy precipitation at Prague‐Klementinum, the most frequently analysed long‐term station in the Czech Republic [and the only one available in continental‐scale analyses within the European Climate Assessment (ECA) project and related activities], are particularly unrepresentative for a wider area. The analysis partly supports an emerging global picture of prevailing positive trends in precipitation extremes over the mid‐latitudinal land areas of the Northern Hemisphere in winter. However, the cut‐off between the western and eastern parts of the Czech Republic in many precipitation characteristics, including the trends in wintertime indices of precipitation extremes, may indicate that the pattern of changes is more complex and less coherent in eastern than in western Europe. Copyright © 2008 Royal Meteorological Society
Annual and seasonal mapping of peak intensity, magnitude and duration of extreme precipitation events across a climatic gradient, northeast Spain
Authors: Beguería Santiago , Vicente‐Serrano Sergio M. , López‐Moreno Juan I. , García‐Ruiz José M.
Published: December 2008

Assessing the characteristics of extreme precipitation over large regions has a great interest, mainly due to its applications in hazard analysis. However, most of the analyses are reduced to daily rainfall intensity due to the fact that most long precipitation records were collected on a daily basis. Hazardous situations related to extreme precipitation events, however, can be originated either by very intense rainfall, or by large accumulated precipitation due to the persistence of the rainy conditions over a long period of time. In this paper, we show the use of a methodology based on the extreme‐value theory to obtain continuous maps of quantiles of precipitation event parameters—peak intensity, magnitude and duration—for a large region with contrasted climatic characteristics in the northeastern Iberian Peninsula. Spatial models of the probability distributions parameters were calculated, which allowed constructing the regional probability models. The analysis was based on time series of precipitation events, which were obtained from the original daily series. In addition to the usual annual‐based analysis, seasonal analyses were also performed. This allowed assessing the differences in the spatial distribution of the probability of extreme events at different times of the year. Copyright © 2008 Royal Meteorological Society