bluuebunny/crossref_metadata_2025 huggingface dataset:
Electrosprayed Enzyme Coatings as Bioinspired Alternatives to Bioceramic Coatings for Orthopedic and Oral Implants
Authors: de Jonge Lise T. , Leeuwenburgh Sander C. G. , van den Beucken Jeroen J. J. P. , Wolke Joop G. C. , Jansen John A.
Published: February 2009

The biological performance of orthopedic and oral implants can be significantly improved by functionalizing the non‐physiological metallic implant surface through the application of biologically active coatings. In this paper, a cost‐effective alternative to traditional biomedical coatings for bone substitution through exploitation of the specific advantages of the electrospray deposition technique for the immobilization of the enzyme alkaline phosphatase (ALP) onto the implant surface is presented. Since ALP increases the local inorganic phosphate concentration required for physiological mineralization of hard tissues, ALP coatings will enable enzyme‐mediated mineralization onto titanium surfaces. To evaluate the bone‐bioactive capacity of the ALP‐coated titanium surface, soaking experiments are performed. Although the purely inorganic so‐called simulated body fluid is the standard in vitro procedure for predictive studies on potential bone bonding in vivo, an alternative testing solution is proposed that also contains organic phosphates (cell culture medium supplemented with the organic β‐b;‐glycerophosphate (β‐b;‐GP) and serum proteins), thereby resembling the in vivo conditions more closely. Under these physiological conditions, the electrosprayed ALP coatings accelerated mineralization onto the titanium surface as compared to noncoated implant material by means of enzymatic pathways. Therefore, this novel approach toward implant fixation holds significant promise.
Synthesis, Characterization, and Field‐Effect Transistor Performance of Thieno[3,2‐b]thieno[2′,3′:4,5]thieno[2,3‐d]thiophene Derivatives
Authors: Liu Ying , Wang Ying , Wu Weiping , Liu Yunqi , Xi Hongxia , Wang Limin , Qiu Wenfeng , Lu Kun , Du Chunyan , Yu Gui
Published: February 2009

The synthesis, characterization, and field‐effect transistor (FET) properties of a new class of thieno[3,2‐b]thieno[2′,3′:4,5]thieno[2,3‐d]thiophene derivatives are described. The optical spectra of their films show the presence of stronger interactions between molecules in the solid state. Thermal analyses reveal that the three materials are thermally stable and have no phase transitions at low temperature. The crystal structures are determined, and show π‐stacked structures and intermolecular S···S contacts. These organic materials exhibit p‐type FET behavior with hole mobilities as high as 0.14 cm2 V−1 s−1 and an on/off current ratio of 106. These results indicate that thieno[3,2‐b]thieno [2′,3′:4,5]thieno[2,3‐d]thiophene, as a linear π‐conjugated system, is an effective building block for developing high‐performance organic semiconductors.
Luminescence of Nanocrystalline Erbium‐Doped Yttria
Authors: Mao Yuanbing , Tran Thai , Guo Xia , Huang Jian Y. , Shih C. Ken , Wang Kang L. , Chang Jane P.
Published: February 2009

In this paper, the luminescence, including photoluminescence, upconversion and cathodoluminescence, from single‐crystalline erbium‐doped yttria nanoparticles with an average diameter of 80 nm, synthesized by a molten salt method, is reported. Outstanding luminescent properties, including sharp and well‐resolved photoluminescent lines in the infrared region, outstanding green and red upconversion emissions, and excellent cathodoluminescence, are observed from the nanocrystalline erbium‐doped yttria. Moreover, annealing by the high power laser results in a relatively large increase in photoluminescent emission intensity without causing spectral line shift. These desirable properties make these nanocrystals promising for applications in display, bioanalysis and telecommunications.
Light‐Emitting Rubrene Nanowire Arrays: A Comparison with Rubrene Single Crystals
Authors: Lee Jin Woo , Kim Kihyun , Park Dong Hyuk , Cho Mi Yeon , Lee Yong Baek , Jung Jin Sun , Kim Dae‐Chul , Kim Jeongyong , Joo Jinsoo
Published: February 2009

This is a report on a new method of growth of a light‐emitting rubrene nanowires array with diameters of 200 ± 10 nm by using organic vapor transport through Al2O3 nanoporous templates. Nanometer‐scale laser confocal microscope (LCM) photoluminescence (PL) spectra and crystalline structures of the rubrene nanowires are compared with those of rubrene single crystals prepared with the same experimental conditions without the template. In the LCM PL spectra it is observed that the PL spectra and intensity varies with the detecting positions because of the crystal growth characteristics of the rubrene molecules. A single rubrene nanowire has a wider LCM PL band width than that of the rubrene single crystal. This may originate from the light emissions of the mixed polarized bands due to additional new crystallinity in the formation of the nanowires. From the current–voltage characteristic curves, the semiconducting nature of both the rubrene nanowires and single crystals is observed.
Material Solubility‐Photovoltaic Performance Relationship in the Design of Novel Fullerene Derivatives for Bulk Heterojunction Solar Cells
Authors: Troshin Pavel A. , Hoppe Harald , Renz Joachim , Egginger Martin , Mayorova Julia Yu. , Goryachev Andrey E. , Peregudov Alexander S. , Lyubovskaya Rimma N. , Gobsch Gerhard , Sariciftci N. Serdar , Razumov Vladimir F.
Published: February 2009

The preparation of 27 different derivatives of C60 and C70 fullerenes possessing various aryl (heteroaryl) and/or alkyl groups that are appended to the fullerene cage via a cyclopropane moiety and their use in bulk heterojunction polymer solar cells is reported. It is shown that even slight variations in the molecular structure of a compound can cause a significant change in its physical properties, in particular its solubility in organic solvents. Furthermore, the solubility of a fullerene derivative strongly affects the morphology of its composite with poly(3‐hexylthiophene), which is commonly used as active material in bulk heterojunction organic solar cells. As a consequence, the solar cell parameters strongly depend on the structure and the properties of the fullerene‐based material. The power conversion efficiencies for solar cells comprising these fullerene derivatives range from negligibly low (0.02%) to considerably high (4.1%) values. The analysis of extensive sets of experimental data reveals a general dependence of all solar cell parameters on the solubility of the fullerene derivative used as acceptor component in the photoactive layer of an organic solar cell. It is concluded that the best material combinations are those where donor and acceptor components are of similar and sufficiently high solubility in the solvent used for the deposition of the active layer.
Metathesis in Pure Water Mediated by Supramolecular Additives
Authors: Brendgen Thomas , Fahlbusch Tilmann , Frank Markus , Schühle Daniel T. , Seßler Miriam , Schatz Jürgen
Published: February 2009

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Supramolecular, water‐soluble additives based on calix[n]arenes exhibit a beneficial influence on the ring‐closing and cross metathesis of non‐polar substrates in pure aqueous medium using standard Grubbs‐II and Hoveyda‐II catalysts. The catalytic activity observed in water is virtually the same as that in pure methanol. Quantitative yields of metathesis product can be achieved under mild aerobic conditions in/on water by (micro)solubilization of both the catalyst and starting materials by the macrocycles.
Development of a Supported Ionic Liquid Phase (SILP) Catalyst for Slurry‐Phase Friedel–Crafts Alkylations of Cumene
Authors: Joni J. , Haumann M. , Wasserscheid P.
Published: February 2009

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A supported ionic liquid phase (SILP) catalyst material has been developed based on a silica support coated with an acidic chloroaluminate ionic liquid. Compared to the results in a liquid‐liquid biphasic reaction these materials showed in the isopropylation of cumene a clearly different selectivity which was found to be related to a reduction of the ionic liquid’s acidity by the untreated silica support. By pretreating the support with a defined amount of ionic liquid for neutralization and removal of surface hydroxy groups, a well defined, very active and also very selective SILP catalyst for slurry phase Friedel–Crafts alkylation was obtained.
Synthesis of 2,6‐Dioxo‐1,2,3,4,5,6‐hexahydroindoles by Acid‐ Catalyzed Cyclization of Acetal‐Protected (2,4‐Dioxocyclohex‐1‐yl)acetamides and their Transformation into 5,8,9,10‐Tetrahydro‐6H‐indolo[2,1‐a]isoquinolin‐9‐ones
Authors: Juma Benard , Adeel Muhammad , Villinger Alexander , Reinke Helmut , Spannenberg Anke , Fischer Christine , Langer Peter
Published: February 2009

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Acetal‐protected (2,4‐dioxocyclohex‐1‐yl)acetic acids were prepared by allylation of dilithiated 1,3‐cyclohexane‐1,3‐diones, protection of the carbonyl groups and oxidation of the alkene moiety. Their reaction with amines afforded the corresponding amides which were transformed, by acid‐catalyzed cyclization, into various 2,6‐dioxo‐1,2,3,4,5,6‐hexahydroindoles. The reaction of the latter with triflic acid resulted in the formation of novel 5,8,9,10‐tetrahydro‐6H‐indolo[2,1‐a]isoquinolin‐9‐ones.
A Mild and Efficient Iron‐Catalyzed Synthesis of Alkenyl Halides via Direct Addition of Benzyl Halides to Arylalkynes
Authors: Liu Zhongquan , Wang Jianguo , Zhao Yankai , Zhou Bo
Published: February 2009

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An efficient and mild iron‐catalyzed synthesis of alkenyl halides has been developed via direct carbon‐carbon bond formation by using benzyl halides and arylalkynes.
Mechanism studies on CVD of boron carbide from a gas mixture of BCL3, CH4, and H2 in a dual impinging‐jet reactor
Authors: Karaman Mustafa , Sezgi Naime Aslı , Doğu Timur , Özbelge Hilmi Önder
Published: February 2009

Nearly pure boron carbide free from impurities was produced on a tungsten substrate in a dual impinging‐jet chemical vapor deposition reactor from a BCl3, CH4, and H2 mixture. The Fourier Transform Infrared (FTIR) analysis proved the formation of reaction intermediate BHCl2, which is proposed to occur mainly in the gaseous boundary layer next to the substrate surface. Among a large number of reaction mechanisms proposed only the ones considering the molecular adsorption of boron carbide on the substrate surface gave reasonable fits. In the proposed mechanism dichloroborane is formed in the gas phase only as a by‐product. Boron carbide, on the other hand, is formed through a series of surface reactions involving adsorbed boron trichloride, adsorbed methane and gas phase hydrogen. The simultaneous fit of the experimental rate data to the model expressions gave correlation coefficient values of 0.977 and 0.948, in predicting the B4C and BHCl2 formation rates, respectively. © 2009 American Institute of Chemical Engineers AIChE J, 2009
Blood pressure and lifestyle on Saba, Netherlands Antilles
Authors: Soloway Laura E. , Demerath Ellen W. , Ochs Natalie , James Gary D. , Little Michael A. , Bindon James R. , Garruto Ralph M.
Published: February 2009

During the 20th century, infectious disease morbidity and mortality generally waned whereas chronic degenerative diseases posed a growing burden at the global level. The population on Saba, Netherlands Antilles has recently experienced such an epidemiologic transition, and hypertension was reported to be extraordinarily high, although no prevalences have been reported and relationships with lifestyle factors associated with rapid modernization have not been explored. In this study, a medical and demographic questionnaires, as well as body composition and blood pressure measures were collected from 278 Saban men and women aged 18–91 years. When age and sex adjusted, 48% of the population was hypertensive. Age, BMI, and Afro‐Caribbean descent were all associated with higher blood pressures. In a second phase, 124 individuals of the 278 were invited to receive a longer questionnaire on individual exposure to modernizing influences such as travel and education. Higher blood pressure was associated with having lived in fewer different places in the past; those who stayed only on Saba or Statia had higher blood pressures than those who had also lived in more modernized areas. However, this was no longer statistically significant after adjustment for age and BMI. Lifestyle incongruity was positively associated with higher blood pressure in that those with more discord between material wealth and income were more likely to be hypertensive, and this remained statistically significant after adjustment for age and adiposity. In summary, hypertension is highly prevalent on Saba and tended to be associated with greater age, adiposity, Afro‐Caribbean ancestry, and lifestyle incongruity. Am. J. Hum. Biol., 2009. © 2009 Wiley‐Liss, Inc.
Growth in root length of the mandibular canine and premolars in a mixed‐longitudinal orthodontic sample
Authors: Smith Shelley L. , Buschang Peter H.
Published: February 2009

Numerous studies of dental development focusing on eruption (clinical emergence) exist in the literature, but fewer studies examine dental development as a process extending across years or decades, and root development is commonly assessed using fractional root lengths. Here, we examine the growth of mandibular canine and premolar roots in a mixed‐longitudinal sample of orthodontic patients (77 females and 74 males) from north central Texas. Multilevel models are generated for root lengths as a percentage of total tooth lengths (within films) as well as for absolute root lengths (across films). As a percentage of tooth length, roots grow with decreasing velocity through time between 7 and 14 years of age. More complex patterns appear for absolute growth in root length, with girls showing an earlier maximum growth rate for the canine than for the premolars. Substitution of dental age for chronological age reduces between‐subject variation (assessed at age 11), especially for boys. A better understanding of dental maturation, including root length growth, should allow improved prediction models. Am. J. Hum. Biol., 2009. © 2009 Wiley‐Liss, Inc.
Why men have shorter lives than women: Effects of resource availability, infectious disease, and senescence
Authors: Møller A.P. , Fincher C.L. , Thornhill R.
Published: February 2009

Senescence arises from age‐specific deterioration of the soma as a consequence of optimization of life history, and such effects of senescence should appear when comparing species that differ in intensity of sexual selection, as well as when comparing, within a species, the two sexes that often differ in intensity of sexual selection. However, any extrinsic cause of mortality that reduces life expectancy will reduce the possibility of detecting sex‐specific differences in senescence. We investigated geographical variation in human sex differences in longevity across 121 countries to test whether differences in sexual competition for limiting resources, reflecting intensity of sexual selection, affected sex differences in longevity. Men on average lived 5 years shorter than women. High rates of childhood morbidity and mortality reduced the sex difference in longevity, while increased overall longevity increased the sex difference in longevity. Increased resource availability estimated from gross domestic product per capita reduced the sex difference in longevity, accounting for 10% of the variance, while there was no additional effect of income inequality as reflected by the Gini coefficient. In a separate analysis of sex differences in longevity among the states of the US, there was a strong effect of the Gini coefficient on sex difference in longevity, with the negative effect on male longevity being stronger than that on female longevity. In contrast, there was only a marginal effect of average household income. Thus, there was evidence of increased competition for resources contributing to increased sex differences in longevity within a single nation. Am. J. Hum. Biol., 2009. © 2009 Wiley‐Liss, Inc.
Long sleep duration and childhood overweight/obesity and body fat
Authors: Padez Cristina , Mourao Isabel , Moreira Pedro , Rosado Vitor
Published: February 2009

To assess the association between short sleep duration and overweight/obesity and body fat (BF) and to identify correlates of short sleep duration in a sample of Portuguese children. A cross‐sectional study of children 7–9 years (n = 4511) was performed between October 2002 and June 2003. Weight, height, and skinfolds were measured, and parents filled out a questionnaire about family characteristics as well as sleep duration. The prevalence of overweight/obesity and BF (%) both decreased by long sleep duration. After adjusted for confounders, the odds ratio (OR) for overweight/obesity and sleep duration were as follows: reference >11 h/d; 10–11 h/d, OR: 1.3; confidence interval (CI):1.26, 1.33; 9–10 h/d, OR: 1.16; CI: 1.13, 1.19; and <9 h, OR: 3.22; CI: 3.11, 3.32. Children whose parents' had a low educational level slept less time during each night than children whose parents' had a higher educational level; children who spent more time watching television slept less time than those who watched less television, and those children engaged in physical activity slept more time each night than sedentary children. Our results showed an inverse relationship between long sleep duration and overweight/obesity prevalence as well as with body fat, and these findings are important because sleep duration is a potentially modifiable risk factor that could be important to consider in the prevention and treatment of childhood obesity. Am. J. Hum. Biol., 2009. © 2009 Wiley‐Liss, Inc.
Risk factors for serious injury in Finnish agriculture
Authors: Rautiainen Risto H. , Ledolter Johannes , Donham Kelley J. , Ohsfeldt Robert L. , Zwerling Craig
Published: February 2009

Background

Previous studies indicate 20% of injuries represent 80% of injury costs in agriculture. To help prevent the most costly injuries, we aimed to identify characteristics and risk factors associated with serious injuries.

Methods

We analyzed insurance records of 93,550 self‐employed Finnish farmers. We ranked injury causes by claim cost and used multiple logistic regressions to identify risk factors for (any) injury and serious injury (injuries exceeding claim costs of €2000).

Results

A total of 5,507 compensated injuries occurred in 2002 (rate 5.9/100 person‐years), and 1,167 or 21% of them (rate 1.25/100 person‐years) were serious. The causes/sources resulting in highest average claim costs were motor vehicles; stairs, scaffoldings, and ladders; trailers and wagons; floors, walkways, and steps; other structures and obstacles; augers, mills, and grain handling equipment; horses; combines and harvesting equipment; tractor steps; and uneven and slippery terrain. Older age, male gender, higher income level, greater field size, residing on the farm, Finnish language (vs. Swedish), occupational health service (OHS) membership, and animal production were risk factors for injury. The risk factors for serious injury were similar; however, the effects of age, income level, and the raising of horses were more prominent. Language, residence, ownership status, and OHS membership were not risk factors for serious injury.

Conclusions

Cost‐effective prevention efforts should address the following risk factors: older age, male gender, larger income and operation size, livestock production (particularly dairy, swine, and horses), motor vehicle incidents, falls from elevation, and slips, trips and falls. Am. J. Ind. Med. 52:419–428, 2009. © 2009 Wiley‐Liss, Inc.
Entwicklung von Inhibitoren der Tau‐Aggregation bei Morbus Alzheimer
Authors: Bulic Bruno , Pickhardt Marcus , Schmidt Boris , Mandelkow Eva‐Maria , Waldmann Herbert , Mandelkow Eckhard
Published: February 2009

Mit kleinen Molekülen gegen Alzheimer: Die pathologische Aggregation des Tau‐Proteins ist ein Hauptmerkmal bei neurodegenerativen Erkrankungen wie der Alzheimerkrankheit und anderen Tauopathien. Die Inhibierung oder gar die Umkehr der Tau‐Aggregation sind potenzielle therapeutische Strategien, die sich derzeit in der klinischen Prüfung befinden. Das Bild zeigt charakteristische pathologische Fibrillen aus Tau‐Proteinen (paarige helikale Filamente), die die Hauptkomponente der bei Alzheimer auftretenden neurofibrillären Bündel sind.

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Eine Vielzahl humaner Erkrankungen steht vermutlich in direkter Verbindung mit der Fehlfaltung von Proteinen. Hierbei werden typischerweise hochorganisierte Proteinaggregate, so genannte Amyloidfibrillen, sowie deren Aggregationsintermediate beobachtet. Diese gelten allgemein als Vermittler der Zytotoxizität und stehen demzufolge im Fokus der Forschung. Die pathologische Aggregation des Tau‐Proteins ist ein Hauptmerkmal einiger neurodegenerativer Erkrankungen wie der Alzheimerkrankheit. Im vergangenen Jahrzehnt hat man sich daher verstärkt der Suche nach Inhibitoren der Tau‐Aggregation als potenzielle krankheitsmodifizierende Wirkstoffe bei Morbus Alzheimer und anderen “Tauopathien” gewidmet. Der jüngste Bericht einer klinischen Phase‐II‐Studie des Tau‐Aggregationsinhibitors MTC stellt eine Validierung des Konzepts in Aussicht. In diesem Aufsatz fassen wir die verfügbaren Daten über niedermolekulare Inhibitoren der Tau‐Aggregation von einem medizinisch‐chemischen Standpunkt heraus zusammen.
Duplex Stabilization and Energy Transfer in Zipper Porphyrin–DNA
Authors: Nguyen ThaoNguyen , Brewer Ashley , Stulz Eugen
Published: February 2009

An der DNA ausgerichtet: Das Anbringen von Porphyrinen an komplementären DNA‐Strängen führt zu Reißverschluss‐artigen Porphyrinanordnungen und erhöht, wenn elf Modifikationen vorliegen, die Schmelztemperatur der Doppelstränge. In Doppelsträngen mit gemischten Anordnungen findet ein Energietransfer von Zinkporphyrinen auf freie Porphyrine statt, nicht aber in der denaturierten Form (siehe Schema). Dadurch werden potenzielle photonische Drähte reversibel aufgebaut.

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Synthesis and Characterization of [Ar′GaC(Ph)CH]2 and K2[Ar′GaC(Ph)CH]2⋅OEt2: From Digallene to Digallacyclohexadiene to Digallatabenzene
Authors: Zhu Zhongliang , Wang Xinping , Olmstead Marilyn M. , Power Philip P.
Published: February 2009

Platt gemacht: Die Addition von PhCCH an Ar′GaGaAr′ (Ar′=2,6‐(2,6‐iPr2C6H3)2C6H3) führt zu dem 1,4‐Digallacyclohexadien [{Ar′GaC(Ph)CH}2] (1), das bei der Reduktion mit Kalium in das 1,4‐Digallatabenzol‐Dianion [Ar′GaC(Ph)CH]22− (2) übergeht (siehe Schema; C grau, Ga grün, K blau). Strukturparameter, Dichtefunktionalrechnungen und 1H‐NMR‐spektroskopische Daten belegen den aromatischen Charakter von 2.

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Insertion of Amides into a Polyoxometalate
Authors: Li Joaquim , Huth Inga , Chamoreau Lise‐Marie , Hasenknopf Bernold , Lacôte Emmanuel , Thorimbert Serge , Malacria Max
Published: February 2009

Der Einbau eines Amid‐Sauerstoffatoms in das Gerüst des Dawson‐Polyoxometallat(POM)‐Clusters [P2V3W15O62]9− (siehe Bild) ermöglicht elektronische Wechselwirkungen zwischen den organischen und anorganischen Teilen des Moleküls: Die Redoxeigenschaften des gesamten Hybrid‐POM lassen sich mithilfe der organischen Komponenten einstellen, und die Elektronen anziehenden Eigenschaften des POM können auf den organischen Teil übertragen werden.

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Titelbild: A Spin‐Crossover Cluster of Iron(II) Exhibiting a Mixed‐Spin Structure and Synergy between Spin Transition and Magnetic Interaction (Angew. Chem. 8/2009)
Authors: Wu Da‐Yu , Sato Osamu , Einaga Yasuaki , Duan Chun‐Ying
Published: February 2009

Ein Spin‐Crossover‐Cluster mit {FeII4O4}‐Kern wird von D. Y. Wu, O. Sato et al. in ihrer Zuschrift auf S. 1503 ff. vorgestellt. Der selbstorganisierte Cluster nimmt zwei High‐spin‐ und zwei Low‐spin‐Zustände ein und zeichnet sich durch einen abrupten Spinübergang sowie durch ein vollständiges lichtinduziertes Einfangen eines angeregten Spinzustands aus. Dies wird durch das Zusammenspiel von magnetischen Wechselwirkungen und Spinübergängen im Cluster ermöglicht.

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Hydride‐Donor Abilities of 1,4‐Dihydropyridines: A Comparison with π Nucleophiles and Borohydride Anions
Authors: Richter Dorothea , Mayr Herbert
Published: February 2009

How are dihydropyridines like indoles? Both groups of compounds have similar nucleophilicity parameters N and are therefore suitable substrates for iminium‐catalyzed reactions of α,β‐unsaturated aldehydes. The N parameters of 1,4‐dihydropyridines were derived from the rates of hydride transfer reactions to benzhydrylium ions (see scheme).

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Duplex Stabilization and Energy Transfer in Zipper Porphyrin–DNA
Authors: Nguyen ThaoNguyen , Brewer Ashley , Stulz Eugen
Published: February 2009

Zip it up: Attachment of porphyrins onto complementary DNA strands leads to zipper‐porphyrin arrays and, in the presence of eleven modifications, an increase in the melting temperature of the duplex. Mixed zinc and free‐base porphyrin arrays undergo energy transfer from the zinc porphyrin to the free‐base porphyrin in the annealed duplex but not in the denatured form (see scheme), giving access to reversible formation of potential photonic wires.

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Radical Polymerization of the Silene (Me3Si)2SiCR2 by Hydrogen Transfer from a Trimethylsilyl Group
Authors: Bravo‐Zhivotovskii Dmitry , Melamed Semyon , Molev Victoria , Sigal Nadejda , Tumanskii Boris , Botoshansky Mark , Molev Gregory , Apeloig Yitzhak
Published: February 2009

The silene (Me3Si)2SiAd is polymerized to produce a polycarbosilane with an unusual SiSiC repeating backbone, rather than the SiC or SiSiCC units expected for olefinic radical polymerization. The polymer structure and the polymerization mechanism (see scheme) were studied by GPC, EPR, and NMR spectroscopy and by trapping experiments.

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Insertion of Amides into a Polyoxometalate
Authors: Li Joaquim , Huth Inga , Chamoreau Lise‐Marie , Hasenknopf Bernold , Lacôte Emmanuel , Thorimbert Serge , Malacria Max
Published: February 2009

POM alert: The incorporation of an amide oxygen atom into the framework of the Dawson‐type polyoxometalate (POM) cluster [P2V3W15O62]9− (see picture) allows the communication of electronic effects between the organic and the inorganic parts of the molecule, including fine‐tuning of the redox properties of the entire hybrid POM by the organic components, and transmission of the POM's electron‐attracting properties to the organic moiety.

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Clay modeling as a method to learn human muscles: A community college study
Authors: Motoike Howard K. , O'Kane Robyn L. , Lenchner Erez , Haspel Carol
Published: February 2009

The efficacy of clay modeling compared with cat dissection for human muscle identification was examined over two semesters at LaGuardia Community College in Queens, NY. The 181 students in 10 sections in this study were randomly distributed into control (cat dissection) and experimental (clay modeling) groups, and the results of the muscle practical examination were analyzed. The clay‐modeling group was significantly better at identifying human muscles on human models than the cat‐dissection group, and was as good at identifying muscles on their self‐made clay mannequins as the cat‐dissection group was at identifying cat muscle on their specimens. This study demonstrated that clay modeling is more effective than cat dissection for learning human muscles at the community college level. Anat Sci Ed 2:19–23, 2009. © 2009 American Association of Anatomists.
A novel approach to the dissection of the human knee
Authors: Clemente F. Richard , Fabrizio Philip A. , Shumaker Michael
Published: February 2009

The knee is one of the most frequently injured joints of the human body with injuries affecting the general population and the athletic population of many age groups. Dissection procedures for the knee joint typically do not allow unobstructed visualization of the anterior cruciate or posterior cruciate ligaments without sacrificing the collateral ligaments. In many cases, the relationships of the intraarticular structures are lost as dissection systematically removes superficial structures to gain access to deeper structures. The authors present an alternative technique for dissection of the human knee joint that allows maximal visualization of intraarticular structures such as the cruciate ligaments and menisci with minimal disturbance to the tibial and fibular collateral ligaments, thus preserving the relationships of the ligamentous and intraarticular structures. Anat Sci Ed 2:41–46, 2009. © 2009 American Association of Anatomists.
Patterns and dynamics of users' behavior and interaction: Network analysis of an online community
Authors: Panzarasa Pietro , Opsahl Tore , Carley Kathleen M.
Published: February 2009

This research draws on longitudinal network data from an online community to examine patterns of users' behavior and social interaction, and infer the processes underpinning dynamics of system use. The online community represents a prototypical example of a complex evolving social network in which connections between users are established over time by online messages. We study the evolution of a variety of properties since the inception of the system, including how users create, reciprocate, and deepen relationships with one another, variations in users' gregariousness and popularity, reachability and typical distances among users, and the degree of local redundancy in the system. Results indicate that the system is a “small world” characterized by the emergence, in its early stages, of a hub‐dominated structure with heterogeneity in users' behavior. We investigate whether hubs are responsible for holding the system together and facilitating information flow, examine first‐mover advantages underpinning users' ability to rise to system prominence, and uncover gender differences in users' gregariousness, popularity, and local redundancy. We discuss the implications of the results for research on system use and evolving social networks, and for a host of applications, including information diffusion, communities of practice, and the security and robustness of information systems.
Do we need the h index and its variants in addition to standard bibliometric measures?
Authors: Bornmann Lutz , Mutz Rüdiger , Daniel Hans‐Dieter
Published: February 2009

In this study, we investigate whether there is a need for the h index and its variants in addition to standard bibliometric measures (SBMs). Results from our recent study (L. Bornmann, R. Mutz, & H.‐D. Daniel, 2008) have indicated that there are two types of indices: One type of indices (e.g., h index) describes the most productive core of a scientist's output and informs about the number of papers in the core. The other type of indices (e.g., a index) depicts the impact of the papers in the core. In evaluative bibliometric studies, the two dimensions quantity and quality of output are usually assessed using the SBMs “number of publications” (for the quantity dimension) and “total citation counts” (for the impact dimension). We additionally included the SBMs into the factor analysis. The results of the newly calculated analysis indicate that there is a high intercorrelation between “number of publications” and the indices that load substantially on the factor Quantity of the Productive Core as well as between “total citation counts” and the indices that load substantially on the factor Impact of the Productive Core. The high‐loading indices and SBMs within one performance dimension could be called redundant in empirical application, as high intercorrelations between different indicators are a sign for measuring something similar (or the same). Based on our findings, we propose the use of any pair of indicators (one relating to the number of papers in a researcher's productive core and one relating to the impact of these core papers) as a meaningful approach for comparing scientists.
Definition and identification of journals as bibliographic and subject entities: Librarianship versus ISIJournal Citation Reportsmethods and their effect on citation measures
Authors: Bensman Stephen J. , Leydesdorff Loet
Published: February 2009

This paper explores the ISIJournal Citation Reports(JCR) bibliographic and subject structures through Library of Congress (LC) and American research libraries cataloging and classification methodology. The 2006Science Citation Index JCRBehavioral Sciences subject category journals are used as an example. From the library perspective, the main fault of theJCRbibliographic structure is that theJCRmistakenly identifies journal title segments as journal bibliographic entities, seriously affecting journal rankings by total cites and the impact factor. In respect toJCRsubject structure, the title segment, which constitutes theJCRbibliographic basis, is posited as the best bibliographic entity for the citation measurement of journal subject relationships. Through factor analysis and other methods, theJCRsubject categorization of journals is tested against their LC subject headings and classification. The finding is thatJCRand library journal subject analyses corroborate, clarify, and correct each other.
Ambiguity measure feature‐selection algorithm
Authors: Mengle Saket S.R. , Goharian Nazli
Published: February 2009

With the increasing number of digital documents, the ability to automatically classify those documents both efficiently and accurately is becoming more critical and difficult. One of the major problems in text classification is the high dimensionality of feature space. We present the ambiguity measure (AM) feature‐selection algorithm, which selects the most unambiguous features from the feature set. Unambiguous features are those features whose presence in a document indicate a strong degree of confidence that a document belongs to only one specific category. We apply AM feature selection on a naïve Bayes text classifier. We favorably show the effectiveness of our approach in outperforming eight existing feature‐selection methods, using five benchmark datasets with a statistical significance of at least 95% confidence. The support vector machine (SVM) text classifier is shown to perform consistently better than the naïve Bayes text classifier. The drawback, however, is the time complexity in training a model. We further explore the effect of using the AM feature‐selection method on an SVM text classifier. Our results indicate that the training time for the SVM algorithm can be reduced by more than 50%, while still improving the accuracy of the text classifier. We favorably show the effectiveness of our approach by demonstrating that it statistically significantly (99% confidence) outperforms eight existing feature‐selection methods using four standard benchmark datasets.
How are new citation‐based journal indicators adding to the bibliometric toolbox?
Authors: Leydesdorff Loet
Published: February 2009

The launching of Scopus and Google Scholar, and methodological developments in social‐network analysis have made many more indicators for evaluating journals available than the traditional impact factor, cited half‐life, and immediacy index of the ISI. In this study, these new indicators are compared with one another and with the older ones. Do the various indicators measure new dimensions of the citation networks, or are they highly correlated among themselves? Are they robust and relatively stable over time? Two main dimensions are distinguished—size and impact—which together shape influence. The h‐index combines the two dimensions and can also be considered as an indicator of reach (like Indegree). PageRank is mainly an indicator of size, but has important interactions with centrality measures. The Scimago Journal Ranking (SJR) indicator provides an alternative to the journal impact factor, but the computation is less easy.
Data fusion according to the principle of polyrepresentation
Authors: Larsen Birger , Ingwersen Peter , Lund Berit
Published: February 2009

We report data fusion experiments carried out on the four best‐performing retrieval models from TREC 5. Three were conceptually/algorithmically very different from one another; one was algorithmically similar to one of the former. The objective of the test was to observe the performance of the 11 logical data fusion combinations compared to the performance of the four individual models and their intermediate fusions when following the principle of polyrepresentation. This principle is based on cognitive IR perspective (Ingwersen & Järvelin, 2005) and implies that each retrieval model is regarded as a representation of a unique interpretation of information retrieval (IR). It predicts that only fusions of very different, but equally good, IR models may outperform each constituent as well as their intermediate fusions. Two kinds of experiments were carried out. One tested restricted fusions, which entails that only the inner disjoint overlap documents between fused models are ranked. The second set of experiments was based on traditional data fusion methods. The experiments involved the 30 TREC 5 topics that contain more than 44 relevant documents. In all tests, the Borda and CombSUM scoring methods were used. Performance was measured by precision and recall, with document cutoff values (DCVs) at 100 and 15 documents, respectively. Results show that restricted fusions made of two, three, or four cognitively/algorithmically very different retrieval models perform significantly better than do the individual models at DCV100. At DCV15, however, the results of polyrepresentative fusion were less predictable. The traditional fusion method based on polyrepresentation principles demonstrates a clear picture of performance at both DCV levels and verifies the polyrepresentation predictions for data fusion in IR. Data fusion improves retrieval performance over their constituent IR models only if the models all are quite conceptually/algorithmically dissimilar and equally and well performing, in that order of importance.
Identifying Web search session patterns using cluster analysis: A comparison of three search environments
Authors: Wolfram Dietmar , Wang Peiling , Zhang Jin
Published: February 2009

Session characteristics taken from large transaction logs of three Web search environments (academic Web site, public search engine, consumer health information portal) were modeled using cluster analysis to determine if coherent session groups emerged for each environment and whether the types of session groups are similar across the three environments. The analysis revealed three distinct clusters of session behaviors common to each environment: “hit and run” sessions on focused topics, relatively brief sessions on popular topics, and sustained sessions using obscure terms with greater query modification. The findings also revealed shifts in session characteristics over time for one of the datasets, away from “hit and run” sessions toward more popular search topics. A better understanding of session characteristics can help system designers to develop more responsive systems to support search features that cater to identifiable groups of searchers based on their search behaviors. For example, the system may identify struggling searchers based on session behaviors that match those identified in the current study to provide context sensitive help.
Synthesis and Structural Characterization of Neutral Hexacoordinate Silicon(IV) Complexes with SiO2N4 Skeletons
Authors: Metz Stefan , Burschka Christian , Tacke Reinhold
Published: February 2009

Surrounded by six: A series of novel neutral hexacoordinate silicon(IV) complexes with SiO2N4 skeletons, containing two bidentate monoanionic O,N ligands and two monoanionic NCX (X = O, S) ligands, was synthesized. The formation of the title compounds involved some unexpected transformations of the bidentate O,N ligands.

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A series of novel neutral hexacoordinate silicon(IV) complexes with SiO2N4 skeletons (compounds 4–8) was synthesized and structurally characterized by single‐crystal X‐ray diffraction and solid‐state NMR spectroscopy (13C, 15N, 29Si). The silicon(IV) complexes each contain two bidentate monoanionic O,N Schiff base ligands and two cyanato‐N or thiocyanato‐N ligands. Compounds 4–8 were prepared from Si(NCO)4 or Si(NCS)4, whereby the complex formation involved some unexpected chemical transformations of the ligands.
Frischbetondruck bei Verwendung von Selbstverdichtendem Beton
Authors: Graubner Carl‐Alexander , Proske Tilo
Published: February 2009

Auf der Grundlage von Untersuchungen zum Reibungs‐ und Verformungsverhalten von Selbstverdichtendem Beton (SVB) in sehr jungem Betonalter wurden analytische Modelle zur Berechnung des Frischbetondrucks auf lotrechte Schalungen entwickelt. Neben einem Modell, welches auf der Silotheorie basiert und zeitlich veränderliche Materialparameter des Frischbetons berücksichtigt, ermöglicht ein vereinfachtes Erstarrungsmodell die rechnerische Abschätzung des Frischbetondrucks. Auf den theoretischen Untersuchungen aufbauend wurde – basierend auf dem Teilsicherheitskonzept – ein praxisrelevanter Berechnungsvorschlag erarbeitet. Es zeigt sich, dass auch bei SVB für die Bemessung von Schalung und Rüstung oftmals eine geringere Belastung als der hydrostatische Betondruck angesetzt werden kann. Die wichtigste Steuerungsmöglichkeit auf der Baustelle stellt dabei die Betoniergeschwindigkeit dar.
Analysis of functional divergence within two structurally related glycoside hydrolase families
Authors: Mertz Blake , Gu Xun , Reilly Peter J.
Published: February 2009

Two glycoside hydrolase (GH) families were analyzed to detect the presence of functional divergence using the program DIVERGE. These two families, GH7 and GH16, each contain members related by amino acid sequence similarity, retaining hydrolytic mechanisms, and catalytic residue identity. GH7 and GH16 comprise GH Clan B, with a shared β‐jelly roll topology and mechanism. GH7 contains fungal cellobiohydrolases and endoglucanases and is divided into five main subfamilies, four of the former and one of the latter. Cluster comparisons between three of the cellobiohydrolase subfamilies and the endoglucanase subfamily identified specific amino acid residues that play a role in the functional divergence between the two enzyme types. GH16 contains subfamilies of bacterial agarases, xyloglucosyl transferases, 1,3‐β‐D‐glucanases, lichenases, and other enzymes with various substrate specificities and product profiles. Four cluster comparisons between these four main subfamilies again have identified amino acid residues involved in functional divergence between the subfamilies. © 2009 Wiley Periodicals, Inc. Biopolymers 91: 478–495, 2009.

This article was originally published online as an accepted preprint. The “Published Online” date corresponds to the preprint version. You can request a copy of the preprint by emailing the Biopolymers editorial office at biopolymers@wiley.com
On the use of ESI‐QqTOF‐MS/MS for the comparative sequencing of nucleic acids
Authors: Oberacher Herbert , Pitterl Florian
Published: February 2009

The usability of a quadrupole—quadrupole—time‐of‐flight (QqTOF) instrument for the tandem mass spectrometric sequencing of oligodeoxynuleotides was investigated. The sample set consisted of 21 synthetic oligodeoxynucleotides ranging in length from 5 to 42 nucleotides. The sequences were randomly selected. For the majority of tested oligonucleotides, two or three different charge states were selected as precursor ions. Each precursor ion was fragmented applying several different collision voltages. Overall 282 fragment ion mass spectra were acquired. Computer‐aided interpretation of fragment ion mass spectra was accomplished with a recently introduced comparative sequencing algorithm (COMPAS). The applied version of COMPAS was specifically optimized for the interpretation of information‐rich spectra obtained on the QqTOF. Sequences of oligodeoxynucleotides as large as 26‐mers were correctly verified in >94% of cases (182 of 192 spectra acquired). Fragment ion mass spectra of larger oligonucleotides were not specific enough for sequencing. Because of the occurrence of extensive internal fragmentation causing low sequence coverage paired with a high probability of assigning fragment ions to wrong sequences, tandem mass spectra obtained from oligonucleotides consisting of 30 and more nucleotides could not be used for sequence verification neither manually nor with COMPAS. © 2009 Wiley Periodicals, Inc. Biopolymers 91: 401–409, 2009.

This article was originally published online as an accepted preprint. The “Published Online” date corresponds to the preprint version. You can request a copy of the preprint by emailing the Biopolymers editorial office at biopolymers@wiley.com
Rational shape engineering of the filamentous protein γ prefoldin through incremental gene truncation
Authors: Whitehead Timothy A. , Je Elizabeth , Clark Douglas S.
Published: February 2009

An enticing possibility in nanotechnology is to use proteins as templates for the positioning of molecules in regular patterns with nanometer precision over large surface areas. However, the ability to redesign protein quaternary structure to construct new shapes remains underdeveloped. In the present work, we have engineered the dimensions of a filamentous protein, the γ prefoldin (γ PFD) from the hyperthermophile Methanocaldococcus jannaschii, and have achieved controllable attachment of filaments in a specific orientation on a carbon surface. Four different constructs of γ PFD were generated in which the coiled coils extending from the association domain are progressively truncated. Three of the truncation constructs form well‐defined filaments with predictable dimensions according to transmission electron microscopy. Two of these constructs had 2D persistence lengths similar to that of γ PFD at 300–740 nm. In contrast, the 2D persistence length of the shortest truncation mutant was 3500 nm, indicating that the filament adsorbs along a different axis than the other constructs with its two rows of coiled coils facing out from the surface. The elastic moduli of the filaments range from 0.7–2.1 GPa, similar to rigid plastics and within the lower limit for proteins whose primary intermolecular interaction is hydrogen bonding. These results demonstrate a versatile approach for controlling the overall dimensions and surface orientation of protein filaments, and expand the toolbox by which to tune two overall dimensions in protein space for the creation of templated materials over a wide variety of conditions. © 2009 Wiley Periodicals, Inc. Biopolymers 91: 496–503, 2009.

This article was originally published online as an accepted preprint. The “Published Online” date corresponds to the preprint version. You can request a copy of the preprint by emailing the Biopolymers editorial office at biopolymers@wiley.com
Differential Regulation of Protein Subdomain Activity with Caged Bivalent Ligands
Authors: Mayer Günter , Müller Jens , Mack Timo , Freitag Daniel F. , Höver Thomas , Pötzsch Bernd , Heckel Alexander
Published: February 2009

Subtle change: Spatiotemporal modulation of individual protein subdomains with light as the trigger signal becomes possible by using bivalent aptamers and introducing photolabile “caging groups” to switch individual aptamer modules ON or OFF differentially. To the best of our knowledge, this is the first study to show that it is possible to modulate individual domain activity in aptamers, and thus also domain activity in proteins, with light.

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