bluuebunny/crossref_metadata_2025 huggingface dataset:
Detergency and Detergents
Authors: Lynn Jesse L.
Published: April 2009

The cleaning of a solid object, ie, the removal of unwanted foreign matter from its surface, is done by methods ranging from simple mechanical separation such as blotting or abrasion to removal by solution or selective chemical action. The term detergency is limited to systems in which a liquid bath is present and is the main cleaning component of the system. The cleaning is enhanced by the presence in the bath of a special solute, the surfactant, which alters interfacial effects at the various boundries within the system. Thus, a typical detersive system consists of a solid object to be cleaned, called the substrate; soil or dirt attached to it, which is to be removed; and a liquid bath.

A meaningful discussion of detergency requires a definition of clean.This article gives details on the mechanisms of detergency, how clean is determined, and the factors influencing detergency. Components of a detergent consist of surfactants, builders (zeolites has been used to replace phosphates, which are not environmentally neutral), bleaching agents, enzymes, antimicrobial agents, etc. Detergency is measured for laundry, metal cleaning, hard surface, glassware and dishwashing, and organic surfaces procedures.Detergent manufacture includes processes for spray‐dried products, nontower applications, agglomeration, and tableting. Health and safety as well as environmental impacts are considered, As a class, surfactants and detergent products are the most widely used and under most conditions, detergents are not hazardous to their users. Product types are listed.
Information Storage Materials
Authors: Kleinefeld Theo , Mergel Dieter
Published: April 2009

This article deals with the principles and technologies of mass storage in thin films. This includes optical recording, magnetic recording and magneto‐optical recording. Sometimes we follow the historical development and discuss alternative concepts, eg, magneto‐optical versus phase‐change recording as rewrite principle or the competition between HD‐DVD and BD as an optical system for blue recording.

For optical recording, we try to give a more comprehensive overview that also includes the main aspects of production technology and how this in intertwined with optical principles, materials science and industrial standards.
Personality traits and endocrine response as possible asymmetry factors of agonistic outcome in karate athletes
Authors: Parmigiani Stefano , Dadomo Harold , Bartolomucci Alessandro , Brain Paul F. , Carbucicchio Andrea , Costantino Cosimo , Ferrari Pier F. , Palanza Paola , Volpi Riccardo
Published: April 2009

Individual variations of plasma levels of hormones testosterone (T) and cortisol (C), before (pre) and after (post) Kumite (real fight) and Kata (ritualized fight) were measured in male karate athletes and analyzed in relation with the agonistic outcome (i.e. winning or losing the fight) and personality trait measures. T and C increased only during Kumite contest and pre‐ and post‐competition C levels were higher in losers than winners. Losers showed higher levels of harm avoidance and anxiety as well as lower level of novelty seeking than winners. Importantly, novelty seeking negatively correlates with pre C and the higher the level of risk assessment, emotionality and insecurity indexes the higher the pre C level. In conclusion, personality traits might be an important factor asymmetry between athletes influencing both the probability of winning or losing an agonistic interaction and the different anticipatory endocrine response to the incipient fight. Aggr. Behav. 35:324–333, 2009. © 2009 Wiley‐Liss, Inc.
Stereoselectivity in the Rhodium‐Catalysed Reductions of Non‐Conjugated Dienes
Authors: Nguyen Bao , Brown John M.
Published: April 2009

magnified image

The stereochemical course of rhodium‐catalysed addition of hydrogen and catecholborane to bicyclo[2.2.1]heptadiene, and of hydrogen to a range of cyclic dienes has been analysed. For hydroboration, the overall catalytic reaction possesses exo‐selectivity, but the initial step is endo‐selective. For hydrogenation (deuteration), the first step may occur with either exo‐ or endo‐ selectivity, depending on the structure of the diene. This enables a distinction to be made between pathways involving prior dissociation of the diene, and direct addition to the complexed diene without full dissociation. The relative ease of hydrogenation of the first and second double bonds varies markedly with reactant structure, and also depends on the choice of catalyst ligands. For dicyclopentadiene, hydrogenation of the cyclopentene double bond is accompanied by rapid alkene isomerisation, as revealed by deuterium addition. The asymmetric hydrogenation of acyclic skipped meso‐dienes is reported, demonstrating control of relative rates of the two sequential steps, with ees of up to 53% after the first reduction.
Highly Enantioselective Construction of the α‐Chiral Center of Amides via Iridium‐Catalyzed Hydrogenation of α,β‐Unsaturated Amides
Authors: Lu Wei‐Jing , Hou Xue‐Long
Published: April 2009

magnified image

The chiral center at the α‐position of amides is installed in excellent enantioselectivity via the iridium‐catalyzed asymmetric hydrogenation of α,β‐unsaturated amides under mild conditions. Even aliphatic amides are suitable substrates. The presence of a hydrogen atom on the nitrogen of the amide is important for the enantioselectivity of the reaction.
Genome‐wide association studies and the genetic dissection of complex traits
Authors: Sebastiani Paola , Timofeev Nadia , Dworkis Daniel A. , Perls Thomas T. , Steinberg Martin H.
Published: April 2009

The availability of affordable high throughput technology for parallel genotyping has opened the field of genetics to genome‐wide association studies (GWAS), and in the last few years hundreds of articles reporting results of GWAS for a variety of heritable traits have been published. What do these results tell us? Although GWAS have discovered a few hundred reproducible associations, this number is underwhelming in relation to the huge amount of data produced, and challenges the conjecture that common variants may be the genetic causes of common diseases. We argue that the massive amount of genetic data that result from these studies remains largely unexplored and unexploited because of the challenge of mining and modeling enormous data sets, the difficulty of using nontraditional computational techniques and the focus of accepted statistical analyses on controlling the false positive rate rather than limiting the false negative rate. In this article, we will review the common approach to analysis of GWAS data and then discuss options to learn more from these data. We will use examples from our ongoing studies of sickle cell anemia and also GWAS in multigenic traits. Am. J. Hematol., 2009. © 2009 Wiley‐Liss, Inc.
Successful behavioral strategy to unite mother and infant rhesus monkeys (Macaca mulatta) after cesarean delivery
Authors: Ruggiero Angela M. , Novak Matthew F.S.X. , Woodward Ruth A. , Suomi Stephen J.
Published: April 2009

Developmental studies of pre‐ to postnatal continuities in rhesus monkeys sometimes require infants be reared with their mothers. However, complications during pregnancy or experimental designs may require cesarean delivery. Owing to lack of published information on this subject, strategies are needed to introduce mothers to their infants following cesarean delivery. Using positive and negative reinforcement techniques we attempted to unite six infant rhesus macaques, Macaca mulatta, to their mothers following c‐sections. For our seventh subject, we attempted to cross‐foster an infant onto an unrelated female after she had undergone a cesarean surgery for a late‐term spontaneous abortion. The mothers varied in age, parity, previous postnatal mothering experience with infants, housing earlier to delivery, and housing subsequent to introduction. Although there were large individual differences among the mother–infant pairs, all seven introductions were successful. The mothers learned to accept and care for their infants from the continuous application of operant conditioning techniques. These data suggest that mother‐rearing following cesarean section is a realistic possibility whether required for clinical reasons or for proper experimental control. Furthermore, the ability to successfully mother‐rear infants produced from cesarean delivery lessens the impact this potential confound of not being reared by their mothers exerts on many types of developmental studies. Am. J. Primatol. 71:510–522, 2009. © 2009 Wiley‐Liss, Inc.
Signals of female reproductive quality and fertility in colony‐living baboons (Papio h. anubis) in relation to ensuring paternal investment
Authors: Daspre Agnès , Heistermann Michael , Hodges J. Keith , Lee Phyllis C. , Rosetta Lyliane
Published: April 2009

The fitness of a female's offspring depends cruicially on the traits, genetic and paternal, that the father contributes. As such, females may either have an interest in behaviorally choosing the highest‐quality male, or in reliably signaling their fertility status to males. Combining hormonal data on a female's ovulatory fertile window with a behavioral context, we suggest that captive female olive baboons (Papio h. anubis) provide fathers with reliable signals of their fertile period. One signal, the maximum anogenital swelling (AGA), typically coincided with a 4‐day fertile window of ovulation, which occurred 2–3 days prior to deturgescence. As expected from previous studies, AGA swelling indicated general attractiveness to males, and males attended to the relative attractiveness of females. Males approached and copulated with females significantly more often during the 4‐day window around ovulation, irrespective of the absolute swelling stage. The two adult males present in the group were both able to copulate with consistent partners as at least two cycling females were available in most months; the dominant male was more selective about the timing of his copulations close to ovulation during the maximal swelling phase. Females with ovulatory but nonconceptive cycles were less attractive to males, especially during their maximal AGA swelling phase. Am. J. Primatol. 71:529–538, 2009. © 2009 Wiley‐Liss, Inc.
Behavioral responses to tooth loss in wild ring‐tailed lemurs (Lemur catta) at the Beza Mahafaly Special Reserve, Madagascar
Authors: Millette James B. , Sauther Michelle L. , Cuozzo Frank P.
Published: April 2009

Severe dental wear and tooth loss is often assumed to impede the processing, breakdown, and energetic conversion of food items, thereby negatively impacting individual health, reproduction, and survival. Ring‐tailed lemurs at the Beza Mahafaly Special Reserve demonstrate exceptionally high frequencies of severe dental wear and antemortem tooth loss, yet often survive multiple years with these impairments. To test the hypothesis that these lemurs mitigate tooth loss through behavioral adjustments, we collected 191 h of observational data from 16 focal subjects, eight without tooth loss and eight with between 3% and 44% loss. These data indicate dentally‐impaired ring‐tailed lemurs show compensatory behaviors consistent with the demands of living in a social group. During early afternoon (12:00–14:30 h) individuals with loss showed trends towards higher frequencies of foraging and grooming, while individuals without loss rested significantly more often. Individuals with >10% loss (n = 7) showed higher frequencies of feeding, foraging, and grooming, and lower frequencies of resting during this period than individuals with <10% loss (n = 9). Individuals with tooth loss maintained relatively higher levels of feeding and foraging throughout the day. These individuals licked tamarind fruit at higher frequencies, likely spending more time softening it before ingestion. These individuals did not demonstrate longer feeding bouts overall, although bouts involving tamarinds were significantly longer. Individuals with marked toothcomb wear engaged in higher rates of certain types of allogrooming, demonstrating that social behaviors are used to compensate for reduced grooming efficiency. These data have implications for interpreting behavioral responses to dental impairment in the fossil record. Am J Phys Anthropol, 2009. © 2009 Wiley‐Liss, Inc.
Stature estimation in an early medieval (XI‐XII c.) Polish population: Testing the accuracy of regression equations in a bioarcheological sample
Authors: Vercellotti Giuseppe , Agnew Amanda M. , Justus Hedy M. , Sciulli Paul W.
Published: April 2009

Accurate stature estimation from skeletal remains can foster useful information on health and microevolutionary trends in past human populations. Stature can be estimated through the anatomical method and regression equations. The anatomical method (Fully: Ann Med Leg 36 [1956] 266–273; Raxter et al.: Am J Phys Anthropol 130 [2006] 374–384) is preferable because it takes into account total skeletal height and thus provides more accurate estimates, but it cannot be applied to incomplete remains. In such circumstances, regression equations allow estimates of living stature from the length of one or few skeletal elements. However, the accuracy of stature estimates from regression equations depends on similarity in body proportions between the population under examination and those used to calibrate the equations. Since genetic affinity and body proportions similarity are not always clearly known in bioarcheological populations, the criteria for selection of appropriate formulae are not always straightforward. This may lead to inaccurate stature estimates and imprecise accounts of past life conditions. Prompted by such practical and theoretical concerns this study aimed at (1) estimating living stature in an early medieval (XI‐XII c.) Polish sample (40 male; 20 female) through the anatomical method and developing population‐specific regression formulae; and (2) evaluating the accuracy of estimates obtained with regression methods commonly employed in European populations. Results indicate that when applied to the skeletal remains from Giecz, our formulae provide accurate estimates, with non‐age‐corrected formulae performing better than age‐corrected ones. Our formulae provide better estimates than those calibrated on recent populations and their use in medieval Polish populations is preferable. Am J Phys Anthropol, 2009. © 2009 Wiley‐Liss, Inc.
Brief communication: Evaluating grandmother effects
Authors: Hawkes Kristen , Smith Ken R.
Published: April 2009

Women who have outlived child‐bearing have long been described as postreproductive. But contributions they make to the survival or fertility of their descendants enhance the reproduction of their genes. Consequently, natural selection affects this characteristic stage of human life history. Grandmother effects can be measured in data sets that include births and deaths over several generations, but unmeasured covariates complicate the task. Here we focus on two complications: cohort shifts in mortality and fertility, and maternal age at death. We use the Utah Population Database to show that longevity of grandmothers may be associated with fewer grandchildren, as reported by Madrigal and Melendez‐Obando (Am J Phys Anthropol 136 (2008) 223–229) for a Costa Rican sample, even when grandmother effects are actually positive. Am J Phys Anthropol 2009. © 2009 Wiley‐Liss, Inc.
Historiography and forensic analysis of the Fort King George “skull”: Craniometric assessment using the specific population approach
Authors: Stojanowski Christopher M. , Duncan William N.
Published: April 2009

In this article, we evaluate the association between the Fort King George “skull” and two Franciscans who were killed during a Guale revolt in 1597 and whose remains were never recovered (Pedro de Corpa and Francisco de Veráscola). The history and historiography of the revolt is summarized to generate a forensic profile for the individuals. The calvaria is described in terms of preservation, taphonomy, possible trauma, age, and sex. Because these factors are consistent with the individuals in question, population affinity is assessed using comparative craniometric analysis. In response to recent criticism of the typological nature of forensic population affinity assessment, we use a population specific approach, as advocated by Alice Brues (1992). Archaeological and historical data inform the occupation history of the site, and data from those specific populations are used in the comparative analysis. Results of linear discriminant function analysis indicate a low probability that the calvaria is a Guale (the precontact inhabitants of southeastern Georgia) or an individual of African descent. Comparison among European and Euro‐American populations indicated poor discriminatory resolution; however, the closest match suggests a New World affinity rather than an Old World English, Scottish, or Iberian affinity for the specimen. Future analyses that will provide greater resolution about the identity of the calvaria are outlined. The case highlights the unique challenges of historical forensics cases relative to those of traditional jurisprudence, as well as the potential for using historiography to overcome those challenges in future analyses. Am J Phys Anthropol, 2009. © 2009 Wiley‐Liss, Inc.
Limb‐girdle muscular dystrophy type 2D gene therapy restores α‐sarcoglycan and associated proteins
Authors: Mendell Jerry R. , Rodino‐Klapac Louise R. , Rosales‐Quintero Xiomara , Kota Janaiah , Coley Brian D. , Galloway Gloria , Craenen Josepha M. , Lewis Sarah , Malik Vinod , Shilling Christopher , Byrne Barry J. , Conlon Thomas , Campbell Katherine J. , Bremer William G. , Viollet Laurence , Walker Christopher M. , Sahenk Zarife , Clark K. Reed
Published: April 2009

Objective

α‐Sarcoglycan deficiency results in a severe form of muscular dystrophy (limb‐girdle muscular dystrophy type 2D [LGMD2D]) without treatment. Gene replacement represents a strategy for correcting the underlying defect. Questions related to this approach were addressed in this clinical trial, particularly the need for immunotherapy and persistence of gene expression.

Methods

A double‐blind, randomized controlled trial using rAAV1.tMCK.hSGCA injected into the extensor digitorum brevis muscle was conducted. Control sides received saline. A 3‐day course of methylprednisolone accompanied gene transfer without further immune suppression.

Results

No adverse events were encountered. SGCA gene expression increased 4–5‐fold over control sides when examined at 6 weeks (2 subjects) and 3 months (1 subject). The full sarcoglycan complex was restored in all subjects, and muscle fiber size was increased in the 3‐month subject. Adeno‐associated virus serotype 1 (AAV1)‐neutralizing antibodies were seen as early as 2 weeks. Neither CD4+ nor CD8+ cells were increased over contralateral sides. Scattered foci of inflammation could be found, but showed features of programmed cell death. Enzyme‐linked immunospot (ELISpot) showed no interferon‐γ response to α‐SG or AAV1 capsid peptide pools, with the exception of a minimal capsid response in 1 subject. Restimulation to detect low‐frequency capsid‐specific T cells by ELISpot assays was negative. Results of the first 3 subjects successfully achieved study aims, precluding the need for additional enrollment.

Interpretation

The finding of this gene replacement study in LGMD2D has important implications for muscular dystrophy. Sustained gene expression was seen, but studies over longer time periods without immunotherapy will be required for design of vascular delivery gene therapy trials. Ann Neurol 2009;66:290–297
The Nature of Halogen⋅⋅⋅Halogen Interactions: A Model Derived from Experimental Charge‐Density Analysis
Authors: Bui Thai Thanh Thu , Dahaoui Slimane , Lecomte Claude , Desiraju Gautam R. , Espinosa Enrique
Published: April 2009

Ein bisschen anziehend: Dass die Cl‐Cl‐Wechselwirkung in C6Cl6anziehend und anisotrop ist, wurde experimentell anhand der Expansion der Elektronendichteρ(r) um die Chlorkerne gezeigt. Die Wechselwirkung wird mit einem Modell erklärt, in dem eine bindende Wechselwirkung zwischen elektronenarmen (blau im Bild) und ‐reichen Bereichen (rot) benachbarter Cl‐Atome besteht.

magnified image
Effiziente katalytische Promiskuität für chemisch unterschiedliche Reaktionen
Authors: Babtie Ann C. , Bandyopadhyay Subhajit , Olguin Luis F. , Hollfelder Florian
Published: April 2009

Für die native und die promiske Reaktion der Arylsulfatase aus Pseudomonas aeruginosa (PAS) wurden gleichermaßen hohe katalytische Leistungen beobachtet, was dafür spricht, dass die enge Beziehung zwischen hoher Aktivität und enger Spezifität deutlich gelockert werden kann (Bild: Übergangszustände der beiden Substrate mit zugehörigen Bindungskonstanten Ktx).

magnified image
Silver Nanoparticle Formation in Different Sizes Induced by Peptides Identified within Split‐and‐Mix Libraries
Authors: Belser Kirsten , Vig Slenters Tünde , Pfumbidzai Conelious , Upert Grégory , Mirolo Laurent , Fromm Katharina M. , Wennemers Helma
Published: April 2009

Split‐and‐mix‐Bibliotheken sind ein ausgezeichnetes Hilfsmittel zur Identifizierung von Peptiden, die die Bildung von Ag‐Nanopartikeln aus Ag+‐Ionen unter Bestrahlung oder in Gegenwart von Natriumascorbat als Reduktionsmittel vermitteln. In kolorimetrischen Screenings wurden strukturell unterschiedliche Peptide identifiziert, die die Bildung von unterschiedlich großen Ag‐Nanopartikeln induzieren, was durch SEM‐Studien und Röntgenpulverbeugungsexperimente bestätigt wurde.

magnified image
Solvent‐Slaved Protein Motions Accompany Proton but Not Hydride Tunneling in Light‐Activated Protochlorophyllide Oxidoreductase
Authors: Heyes Derren J. , Sakuma Michiyo , Scrutton Nigel S.
Published: April 2009

H+ nicht H−: Die durch Protochlorophyllid‐Oxidoreduktase katalysierte Reduktion von Protochlorophyllid weist lösungsmittelvermittelte Bewegungen auf, die Protonen‐, nicht aber Hydridtunneln steuern. Diese Bewegungen erfordern ein ausgedehntes dynamisches Netzwerk zwischen Lösungsmittel und aktivem Zentrum des Enzyms und erleichtern den Protonentransfer (links im Bild). Mit dem Hydridtransfer verbundene Bewegungen sind lokalisierter und nicht durch das Lösungsmittel vermittelt (rechts im Bild).

magnified image
Diastereoselective Synthesis of Pentasubstituted γ‐Butyrolactones from Silyl Glyoxylates and Ketones through a Double Reformatsky Reaction
Authors: Greszler Stephen N. , Johnson Jeffrey S.
Published: April 2009

Drei benachbarte Stereozentrenwerden in einer bemerkenswert diastereoselektiven doppelten Reformatsky‐Sequenz erzeugt. Dieser Ansatz, bei dem ein Keton als abschließendes Elektrophil dient, lieferte sehr rasch hoch funktionalisierte γ‐Butyrolactone (siehe Schema), die für zahlreiche Folgereaktionen geeignet sind. R1=Me, H; R2=Alkyl, Aryl, CF3; Bn=Benzyl, TBS=tert‐Butyldimethylsilyl.

magnified image
Cross Dehydrogenative Arylation (CDA) of a Benzylic CH Bond with Arenes by Iron Catalysis
Authors: Li Yi‐Zhou , Li Bi‐Jie , Lu Xing‐Yu , Lin Song , Shi Zhang‐Jie
Published: April 2009

Oxidative Kupplung: FeCl2 katalysiert die effiziente dehydrierende Arylierung von Substraten mit benzylischen C‐H‐Bindungen (siehe Schema). Die Kreuzkupplungen zwischen Verbindungen mit aromatischen C(sp2)‐H‐Bindungen und benzylischen C(sp3)‐H‐Bindungen verliefen hoch regioselektiv. Die Reaktion könnte über eine Einelektronenoxidation mit anschließender Friedel‐Crafts‐Alkylierung ablaufen.

magnified image
Methandiide Complexes (R2CM2) of the Heavier Alkali Metals (M=Potassium, Rubidium, Cesium): Reaching the Limit?
Authors: Orzechowski Lars , Jansen Georg , Harder Sjoerd
Published: April 2009

Größe ist wichtig: Geminale Bis(amidophosphorano)methandiid‐Dimetallkomplexe der schweren Alkalimetalle K und Rb sind relativ stabil, doch der von Cs, dem größten und elektropositivsten Alkalimetall, zersetzt sich zu einem cyclischen Produkt, das mit Benzylcaesium kokristallisiert.

magnified image
Chirality in Transition Metal Chemistry. Molecules, Supramolecular Assemblies and Materials. Von Hani Amouri und Michel Gruselle.
Authors: Albrecht Markus
Published: April 2009

John Wiley & Sons, Hoboken 2008. 260 S., Broschur, 47.90 €.—ISBN 978‐0470060544

magnified image
Hyperbranched: A Universal Conjugated Polymer Platform
Authors: Tolosa Juan , Kub Chris , Bunz Uwe H. F.
Published: April 2009

Ein wandelbares Polymer: Die Sonogashira‐Kupplung eines AB2‐Monomers mit zwei Iodsubstituenten und einer Alkinfunktion führt zu einem hochverzweigten konjugierten Polymer mit Iod‐Endgruppen (kleine violette Quader im Bild). Die Iodsubstituenten sind ein hervorragender Angriffspunkt für die effiziente Funktionalisierung nach der Polymerisation, um durch den Austausch von Endgruppen hochverzweigte fluoreszierende Poly(phenylenethinylene) zu erhalten.

magnified image
Coordination and Activation of the BF Molecule
Authors: Vidovic Dragoslav , Aldridge Simon
Published: April 2009

Kein CO: Das mit CO und N2 isoelektronische Fluorborylen (BF) lässt sich mit einem Übergangsmetall abfangen. Im strukturell charakterisierten Komplex [{CpRu(CO)2}2(μ‐BF)] liegt ein nicht unterstützter BF‐Brückenligand vor, was man in der Strukturchemie von CO nicht kennt. Mit AlCl3 koordiniert metallgebundenes CO über das O‐Atom, ohne dass eine Bindung gebrochen wird, während der polare und weniger π‐gebundene BF‐Ligand heterolytisch gespalten wird (siehe Bild).

magnified image
Formaldehyde Formation on Vanadium Oxide Surfaces V2O3(0001) and V2O5(001): How does the Stable Methoxy Intermediate Form?
Authors: Göbke Daniel , Romanyshyn Yuriy , Guimond Sébastien , Sturm Jacobus Marinus , Kuhlenbeck Helmut , Döbler Jens , Reinhardt Ulrike , Ganduglia‐Pirovano Maria Veronica , Sauer Joachim , Freund Hans‐Joachim
Published: April 2009

Hydroxy‐mediated methoxy formation or stabilization is probably an important process in many methanol adsorption systems. Hydrogen atoms originating from the scission of the methanol OH bond react with the substrate and form water. This process may result 1) in the production of additional surface defects as reactive centers for methoxy formation and 2) in the stabilization of methoxy groups by suppression of methanol formation.

magnified image
Efficient Catalytic Promiscuity for Chemically Distinct Reactions
Authors: Babtie Ann C. , Bandyopadhyay Subhajit , Olguin Luis F. , Hollfelder Florian
Published: April 2009

High catalytic proficiencies observed for the native and promiscuous reaction of the Pseudomonas aeruginosa arylsulfatase (PAS; the picture shows transition states of the two substrates with corresponding binding constants Ktx) suggest that the trade‐off between high activity and tight specificity can be substantially relaxed.

magnified image
Silver Nanoparticle Formation in Different Sizes Induced by Peptides Identified within Split‐and‐Mix Libraries
Authors: Belser Kirsten , Vig Slenters Tünde , Pfumbidzai Conelious , Upert Grégory , Mirolo Laurent , Fromm Katharina M. , Wennemers Helma
Published: April 2009

Split‐and‐mix libraries are an excellent tool for the identification of peptides that induce the formation of Ag nanoparticles in the presence of either light or sodium ascorbate to reduce Ag+ ions. Structurally diverse peptides were detected in colorimetric on‐bead screenings that generate Ag nanoparticles of different sizes, as confirmed by SEM and X‐ray powder diffraction studies.

magnified image
Ionic‐Liquid‐Assisted Formation of Silver Nanowires
Authors: Kim Tae Young , Kim Won Jung , Hong Seung Hyun , Kim Jong Eun , Suh Kwang S.
Published: April 2009

Down to the wire: A simple and effective method to synthesize silver nanowires through an ionic‐liquid‐assisted polyol process is developed (see scheme; scale bar=5 nm). The ionic liquids are tuned to provide the anisotropic growth of silver nanoparticles into nanowires.

magnified image
Solvent‐Slaved Protein Motions Accompany Proton but Not Hydride Tunneling in Light‐Activated Protochlorophyllide Oxidoreductase
Authors: Heyes Derren J. , Sakuma Michiyo , Scrutton Nigel S.
Published: April 2009

H+ but not H−: The reduction reaction of protochlorophyllide catalyzed by protochlorophyllide oxidoreductase features solvent‐slaved motions that control the proton‐ but not the hydride‐tunneling mechanism. These motions imply a long‐range dynamic network from the solvent to the enzyme active site that facilitate proton transfer (see picture, left). Motions for hydride transfer are more localized and are not slaved by the solvent (see picture, right).

magnified image
Nanoparticle Missiles from Exploding Polyelectrolyte Capsules
Authors: Dähne Lars
Published: April 2009

Out with a bang! Microcapsules have been prepared which, as a result of an explosion triggered by an external stimulus, distribute nanoparticles throughout the local environment both efficiently and rapidly (see picture). In this way a principle found in nature for the dispersal of seeds and defensive materials has now been realized in nanotechnology and might be utilized, for example, for the better distribution of drugs in organs.

magnified image
Cross Dehydrogenative Arylation (CDA) of a Benzylic CH Bond with Arenes by Iron Catalysis
Authors: Li Yi‐Zhou , Li Bi‐Jie , Lu Xing‐Yu , Lin Song , Shi Zhang‐Jie
Published: April 2009

Hooking up: FeCl2 catalyzes the efficient cross dehydrogenative arylation of substrates having benzylic CH bonds (see scheme). High regioselectivity was observed during the cross‐coupling between compounds containing aromatic C(sp2)H bonds and benzylic C(sp3)H bonds. This process is proposed to proceed by single‐electron‐transfer oxidation and Friedel–Crafts alkylation.

magnified image
A Cyclic Hexanuclear Heterometalladithiolene Cluster [{(Cp*Rh)2Mo(μ‐CO)2(CO)}2(S2C6H2S2)2] with Two π‐Conjugated S2C6S2 Bridges: Synthesis, Crystal Structure, and Properties
Authors: Zhu Bao‐Hua , Shibata Yusuke , Muratsugu Satoshi , Yamanoi Yoshinori , Nishihara Hiroshi
Published: April 2009

Two dragons playing ball: Direct metal–metal bond formation using a π‐conjugated dinuclear metalladithiolene complex with two electron‐deficient metal centers as building blocks led to a cyclic double trinuclear heterometalladithiolene cluster with two parallel plane bridges (see structure; Rh pink, Mo green, S yellow, C gray, O red).

magnified image
Methandiide Complexes (R2CM2) of the Heavier Alkali Metals (M=Potassium, Rubidium, Cesium): Reaching the Limit?
Authors: Orzechowski Lars , Jansen Georg , Harder Sjoerd
Published: April 2009

Size does matter: Whereas geminal bimetallic bis(amidophosphorano)methandiide complexes of the heavy alkali metals K and Rb are relatively stable, that of Cs, the largest and most electropositive of the alkali metals, decomposes to form a cyclic product, which cocrystallizes with benzylcesium.

magnified image
A Synthetic High‐Spin Oxoiron(IV) Complex: Generation, Spectroscopic Characterization, and Reactivity
Authors: England Jason , Martinho Marlène , Farquhar Erik R. , Frisch Jonathan R. , Bominaar Emile L. , Münck Eckard , Que Lawrence
Published: April 2009

High versus low: The high‐yield generation of a synthetic high‐spin oxoiron(IV) complex, [FeIV(O)(TMG3tren)]2+ (see picture, TMG3tren = 1,1,1‐tris{2‐[N2‐(1,1,3,3‐tetramethylguanidino)]ethyl}amine), has been achieved by using the very bulky tetradentate TMG3tren ligand, in order to both sterically protect the oxoiron(IV) moiety and enforce a trigonal bipyramidal geometry at the iron center, for which an S=2 ground state is favored.

magnified image
Chirality in Transition Metal Chemistry.Molecules, Supramolecular Assemblies and Materials. By Hani Amouri and Michel Gruselle.
Authors: Albrecht Markus
Published: April 2009

John Wiley & Sons, Hoboken 2008. 260 pp., softcover € 47.90.—ISBN 978‐0470060544

magnified image
Cosolvent‐promoted electrophilic amination of organozinc reagents
Authors: Daşkapan Tahir , Yeşilbağ Ferhat , Koca Selçuk
Published: April 2009

In this study, we aimed to develop a simple and efficient method for the electrophilic amination of organozinc reagents. For this reason, 12 cosolvents were screened in the electrophilic amination of ordinary organozinc reagents. By the use of a cosolvent, an easily applicable and high‐yielding method for the preparation of arylamines by electrophilic amination of arylzinc reagents was developed. Copyright © 2009 John Wiley & Sons, Ltd.
Evaluating advanced search interfaces using established information‐seeking models
Authors: Wilson Max L. , schraefel m.c. , White Ryen W.
Published: April 2009

When users have poorly defined or complex goals, search interfaces that offer only keyword‐searching facilities provide inadequate support to help them reach their information‐seeking objectives. The emergence of interfaces with more advanced capabilities, such as faceted browsing and result clustering, can go some way toward addressing such problems. The evaluation of these interfaces, however, is challenging because they generally offer diverse and versatile search environments that introduce overwhelming amounts of independent variables to user studies; choosing the interface object as the only independent variable in a study would reveal very little about why one design outperforms another. Nonetheless, if we could effectively compare these interfaces, then we would have a way to determine which was best for a given scenario and begin to learn why. In this article, we present a formative inspection framework for the evaluation of advanced search interfaces through the quantification of the strengths and weaknesses of the interfaces in supporting user tactics and varying user conditions. This framework combines established models of users and their needs and behaviors to achieve this. The framework is applied to evaluate three search interfaces and demonstrates the potential value of this approach to interactive information retrieval evaluation.
Brand and its effect on user perception of search engine performance
Authors: Jansen Bernard J. , Zhang Mimi , Schultz Carsten D.
Published: April 2009

In this research we investigate the effect of search engine brand on the evaluation of searching performance. Our research is motivated by the large amount of search traffic directed to a handful of Web search engines, even though many have similar interfaces and performance. We conducted a laboratory experiment with 32 participants using a 42 factorial design confounded in four blocks to measure the effect of four search engine brands (Google, MSN, Yahoo!, and a locally developed search engine) while controlling for the quality and presentation of search engine results. We found brand indeed played a role in the searching process. Brand effect varied in different domains. Users seemed to place a high degree of trust in major search engine brands; however, they were more engaged in the searching process when using lesser‐known search engines. It appears that branding affects overall Web search at four stages: (a) search engine selection, (b) search engine results page evaluation, (c) individual link evaluation, and (d) evaluation of the landing page. We discuss the implications for search engine marketing and the design of empirical studies measuring search engine performance.
Combining competencies and competitiveness for the European life sciences
Authors: Rindoks Aimee
Published: April 2009

The Youth Conference on European Life Science Careers

News from academia: Women in Science Award for structural biologist
New Energetic Materials: Functionalized 1‐Ethyl‐5‐aminotetrazoles and 1‐Ethyl‐5‐nitriminotetrazoles
Authors: Stierstorfer Jörg , Tarantik Karina R. , Klapötke Thomas M.
Published: April 2009

A new way to make a bang: Several functionalized 1‐ethyl‐5‐aminotetrazoles, 1‐ethyl‐5‐nitrimino‐tetrazoles, and copper complexes have been synthesized and their chemical and energetic properties have been comprehensively characterized. The compounds belong to all classes of “energetic materials”: explosives, propellants, and pyrotechnics.

magnified image

Alkylation of 5‐aminotetrazole (1) with 2‐chloroethanol leads to a mixture of the N‐1 and N‐2 isomers of (2‐hydroxyethyl)‐5‐aminotetrazole. Treatment of 1‐(2‐hydroxyethyl)‐5‐aminotetrazole (2) with SOCl2 yielded 1‐(2‐chlorethyl)‐5‐aminotetrazole (3). 1‐(2‐Azidoethyl)‐5‐aminotetrazole (4) was generated by the reaction of 3 with sodium azide. Nitration of 2, 3, and 4 with HNO3 (100 %) yielded in the case of 2 and 3 1‐(2‐hydroxyethyl)‐5‐nitriminotetrazole (5) and 1‐(2‐chloroethyl)‐5‐nitriminotetrazole (6). In the case of 4, 1‐(2‐nitratoethyl)‐5‐nitriminotetrazole monohydrate (7) was obtained. 1‐(2‐Azidoethyl)‐5‐nitriminotetrazole (8) could be obtained by nitration of 4 with NO2BF4 via the formation of potassium 1‐(2‐azidoethyl)‐5‐nitriminotetrazolate (9). The reaction of 6 with NaN3 resulted in the formation of the salt sodium 1‐(2‐chloroethyl)‐5‐nitriminotetrazolate (10 a). The deprotonation reaction of 6 was further investigated by the formation of the ammonium salt (10 b). The protonation of 2 and 4 with dilute nitric acid led to 1‐(2‐hydroxyethyl)‐5‐aminotetrazolium nitrate (11) and 1‐(2‐azidoethyl)‐5‐aminotetrazolium nitrate (12), respectively. Similarly, protonation of 4 with perchloric acid led to 1‐(2‐azidoethyl)‐5‐aminotetrazolium perchlorate monohydrate (13). Since 5‐nitrimino‐tetrazoles can be used as bidentate ligands, the coordination abilities of 5, 6, and 8 were tested by the reaction with copper nitrate trihydrate, yielding the copper complexes trans‐[diaquabis{1‐(2‐hydroxyethyl)‐5‐nitriminotetrazolato‐κ2N4,O5}copper(II)] (14), trans‐[diaquabis{1‐(2‐chloroethyl)‐5‐nitriminotetrazolato‐κ2N4,O5}copper(II)] dihydrate (15), and [diaquabis{1‐(2‐azidoethyl)‐5‐nitriminotetrazolato‐κ2N4,O5}copper(II)] (16). All compounds were characterized by low‐temperature single‐crystal X‐ray diffraction. In addition, comprehensive characterization (IR, Raman, and multinuclear NMR spectroscopy (1H, 13C), elemental analysis, mass spectrometry, DSC) was performed. The heats of formation of selected compounds were computed by using heats of combustion obtained by bomb calorimetry or calculated by the atomization method. With these values and the densities determined from X‐ray crystallography, several detonation parameter were calculated by the EXPLO5 program. Finally, the sensitivities towards impact and friction were determined using a BAM drop hammer and friction tester.
Peptide‐Coated Silver Nanoparticles: Synthesis, Surface Chemistry, and pH‐Triggered, Reversible Assembly into Particle Assemblies
Authors: Graf Philipp , Mantion Alexandre , Foelske Annette , Shkilnyy Andriy , Mašić Admir , Thünemann Andreas F. , Taubert Andreas
Published: April 2009

The degree of aggregation of silver nanoparticles can be controlled via a pH sensitive peptide coating (see figure). As the peptide not only controls the colloidal properties, but also influences the crystal structure of the individual nanoparticles, peptide/silver particle hybrid materials can be viewed as flexible and simple building blocks for the construction of new meta‐materials with tunable properties.

magnified image

Simple tripeptides are scaffolds for the synthesis and further assembly of peptide/silver nanoparticle composites. Herein, we further explore peptide‐controlled silver nanoparticle assembly processes. Silver nanoparticles with a pH‐responsive peptide coating have been synthesized by using a one‐step precipitation/coating route. The nature of the peptide/silver interaction and the effect of the peptide on the formation of the silver particles have been studied via UV/Vis, X‐ray photoelectron, and surface‐enhanced Raman spectroscopies as well as through electron microscopy, small angle X‐ray scattering and powder X‐ray diffraction with Rietveld refinement. The particles reversibly form aggregates of different sizes in aqueous solution. The state of aggregation can be controlled by the solution pH value. At low pH values, individual particles are present. At neutral pH values, small clusters form and at high pH values, large precipitates are observed.
The Diversity of Difluoroacetylene Coordination Modes Obtained by Coupling Fluorocarbyne Ligands on Binuclear Manganese Carbonyl Sites
Authors: Liu Xian‐mei , Wang Chao‐yang , Li Qian‐shu , Xie Yaoming , King R. Bruce , Schaefer Henry F.
Published: April 2009

One Mn or two? The fluorocarbyne manganese carbonyl complexes [Mn(CF)(CO)n] (n=3, 4) and [Mn2(CF)2(CO)n] (n=4–7; see picture) have been investigated by density functional theory. In mononuclear complexes the CF ligand behaves very much like the NO ligand in terms of π‐acceptor strength. In binuclear complexes the two CF ligands couple in many of the low‐energy structures to form a bridging C2F2 ligand derived from difluoroacetylene.

magnified image

Recent work has shown that the fluorocarbyne ligand CF, isoelectronic with the NO ligand, can be generated by the defluorination of CF3 metal complexes, as illustrated by the 2006 synthesis by Hughes et al. of [C5H5Mo(CF)(CO)2] in good yield by the defluorination of [C5H5Mo(CF3)(CO)3]. The fluorocarbyne ligand has now been investigated as a ligand in the manganese carbonyl complexes [Mn(CF)(CO)n] (n=3, 4) and [Mn2(CF)2(CO)n] (n=4–7) by using density functional theory. In mononuclear complexes, such as [Mn(CF)(CO)4], the CF ligand behaves very much like the NO ligand in terms of π‐acceptor strength. However, in the binuclear complexes the two CF ligands couple in many of the low‐energy structures to form a bridging C2F2 ligand derived, at least formally, from difluoroacetylene, FCCF. The geometries of such [Mn2(C2F2)(CO)n] complexes suggest several different bonding modes of the bridging C2F2 unit. These include bonding through the orthogonal π bonds of FCCF, similar to the well‐known [R2C2Co2(CO)6] complexes, or bonding of the C2F2 unit as a symmetrical or unsymmetrical biscarbene. This research suggests that fluorocarbyne metal chemistry can serve as a means for obtaining a variety of difluoroacetylene metal complexes, thereby avoiding the need for synthesizing and handling the very unstable difluoroacetylene.
Structural and Reactivity Studies of “Pincer” Pyridine Dicarbene Complexes of Fe0: Experimental and Computational Comparison of the Phosphine and NHC Donors
Authors: Danopoulos Andreas A. , Pugh David , Smith Hayley , Saßmannshausen Jörg
Published: April 2009

Pincer carbene complexes: Comparison of the electronic structures of “pincer” Fe0pyridine bis(imidazol‐2‐ylidene) and pyridine diphosphine dicarbonyl complexes (see figure) show subtle differences that account for observed spectroscopic trends. Intermolecular CH activation has been observed in Fe pyridine dicarbene complexes.

magnified image

Reduction of [Fe(C‐N‐C)(Br)2] or [Fe(C‐NMe‐C)(I)2] with Na/Hg under N2gave the Fe0complexes [Fe(C‐N‐C)(N2)2] and [Fe(C‐NMe‐C)(N2)2] for which C‐N‐C=2,6‐bis(arylimidazol‐2‐ylidene)‐pyridine, C‐NMe‐C=2,6‐bis(arylimidazol‐2‐ylidene)‐3,5‐dimethyl‐pyridine and aryl=2,6‐iPr2C6H3. Substitution of the coordinated N2by CO or CN(2,6‐xyl), xyl=2,6‐dimethylphenyl, took place readily to afford [Fe(C‐N‐C)(L)2] and [Fe(C‐NMe‐C)(L)2], L=CO or CN(2,6‐xyl). The electronic characteristics of the N‐heterocyclic carbene and phosphine donors in the complexes [Fe(C‐N‐C)(CO)2], [Fe(C‐NMe‐C)(CO)2] and [Fe(P‐N‐P)(CO)2], P‐N‐P=2,6‐bis(di‐tert‐butylphosphinomethyl)‐pyridine, have been evaluated by spectroscopic, structural and computational methods. The unexpected reduced Fe0to CO backbonding in [Fe(C‐N‐C)(CO)2] and [Fe(C‐NMe‐C)(CO)2] compared to [Fe(P‐N‐P)(CO)2] is accounted for by backbonding from the FeNpyridinebond in the imidazol‐2‐ylidene complexes. Reduction of [Fe(C‐N‐C)(Br)2] under Ar gave mixtures from which a complex with a metalated pyridine and a dangling imidazolium group was isolated. Photolysis of [Fe(C‐N‐C)(N2)2] in the presence of benzaldehyde phenylimine gave anortho‐metalated benzaldehyde phenylimine. The FeIIcomplex [Fe(C‐N‐C)(CO)(Br)2] was prepared by the reaction of [Fe(C‐N‐C)(Br)2] with CO or reduction of CO2with [Fe(C‐N‐C)(N2)2].
Hydrogen‐Release Mechanisms in Lithium Amidoboranes
Authors: Kim Dong Young , Singh N. Jiten , Lee Han Myoung , Kim Kwang S.
Published: April 2009

Hydrogen storage: In lithium amidoboranes an initial molecule of H2 is released by the formation of LiH, followed by a redox reaction of the dihydrogen bond formed between LiHδ− and NHδ+. In this dehydrogenation process, an intermolecular NB bond forms through the catalytic effect of a Li cation. After releasing the first molecule of H2, a Li cation binds to a nitrogen atom, lowering the energy barrier for the second H2 loss per lithium amidoborane dimer (see figure).

magnified image

Alkali‐metal amidoboranes have been recently highlighted as materials that satisfy many of the criteria required to make hydrogen‐storage media. It is, therefore, crucial for us to understand the dehydrogenation mechanism of these materials for further development towards making successful hydrogen‐storage media. In the present study, we attempt to shed light on the mechanisms involved in the loss of one molar equivalent of H2 from solid lithium amidoboranes by using high‐level ab initio calculations of monomeric and dimeric compounds in the gas phase. In the lithium amidoborane dimer, H2 is released by the formation of LiH, which is followed by a redox reaction of the dihydrogen bond formed between the strongly basic H− in LiH and Hδ+ bonded to N. In the dehydrogenation process, the Li cation catalyzes the intermolecular NB bond formation; this could lead to new pathways for NB polymerization. After the release of the first molecule of H2, a Li cation binds to a nitrogen atom, resulting in a lowering of the energy barrier for the second dehydrogenation process per dimer. These results will be useful for the design of future hydrogen‐storage media.
Stable Electroenzymatic Processes by Catalyst Separation
Authors: Hildebrand Falk , Lütz Stephan
Published: April 2009

Division of labour: The rapid enzyme inactivation in the electroenzymatic synthesis of chiral alcohols has been the main obstacle for synthetic applications during the last two decades. The reasons for this inactivation have now been elucidated. The development of a water‐soluble polymeric mediator and the spatial separation of enzyme and mediator led to the first stable process and significantly improved catalyst utilisations (see picture).

magnified image
Low‐Temperature Synthesis of LiBH4 by Gas–Solid Reaction
Authors: Friedrichs Oliver , Borgschulte Andreas , Kato Shunsuke , Buchter Florian , Gremaud Robin , Remhof Arndt , Züttel Andreas
Published: April 2009

Strikingly simple: The low‐temperature and solvent‐free synthesis of LiBH4 from LiH in a borane atmosphere at ambient pressures is reported. The results indicate that the formation of BH bonds is the limiting step for the formation of LiBH4 from the elements. Therefore, the use of diborane as a starting reactant allows one to circumvent the reaction barrier for the BB bond dissociation and explains the rather moderate synthesis conditions.

magnified image

The solvent‐free synthesis of LiBH4 from LiH in a borane atmosphere at 120 °C and ambient pressures is demonstrated. The source of borane is a milled LiBH4/ZnCl2 mixture, in which Zn(BH4)2 is generated by a metathesis reaction. The yield of the reaction of about 74 % LiBH4 shows that a bulk reaction is taking place upon borane absorption by LiH. This indicates that the formation of BH bonds is the limiting step for the formation of LiBH4 from the elements. Therefore, the use of diborane as a starting reactant allows one to circumvent the reaction barrier for the BB bond dissociation and explains the rather moderate synthesis conditions.
Alkyne‐Promoted H2Loss in a Metallaborane:Nido‐to‐ClosoCluster Transformation and sp CH Bond Oxidative Addition
Authors: Álvarez Álvaro , Macías Ramón , Bould Jonathan , Cunchillos Carmen , Lahoz Fernando J. , Oro Luis A.
Published: April 2009

A sensitive cluster: The labile rhodathiaborane [(PPh3)2(H)‐nido‐RhSB9H9(NC5H5)] combines the redox and coordinative flexibility of the {(PPh3)2(H)Rh} fragment with the capability of the 11‐vertex rhodathiaborane cluster to undergo oxidativenido‐to‐closotransformations induced by coordination of alkynes to the metal centre, which leads to hydrogenation of the triple bond, dehydrogenation of the cluster and oxidative addition of sp CH bonds.

magnified image