bluuebunny/crossref_metadata_2025 huggingface dataset:
Public and Professional Understandings of Genetics
Authors: Cunningham‐Burley Sarah
Published: December 2008

Knowledge generated by human genetic research is understood and interpreted differently by different population groups and a range of concerns about developments is also raised. Public and professional understandings are both relevant in the context of the social issues that genetics raises for human health and for clinical practice.
Glycosyltransferases in Plant Cell Wall Synthesis
Authors: Perrin Robyn M
Published: December 2008

Through their influence on plant cell wall polysaccharide structure, plant cell wall glycosyltransferases influence growth, development, cell division and environmental responses as well as plant‐derived food products, biofuels, textiles, paper and timber. Plant cell wall synthesizing enzymes can be processive (glycan synthases) or nonprocessive, and are integral membrane proteins with single or multiple transmembrane domains. Plant cell wall glycosyltransferases can be challenging to study biochemically, as they tend to be labile, present in multimeric complexes and encoded by large gene families whose members may have overlapping function. Candidate proteins may be identified by homology, but their function must be confirmed with biochemical evidence. Strategies for confirmation include expression in heterologous systems followed by assays of enzymatic activity or detection of carbohydrate products. Loss of function or gain‐of‐function techniques may be useful. Despite challenges, numerous plant cell wall glycosyltransferases have been identified; hundreds more, however, await further characterization.

Key concepts

Plant cell walls are critical for both biological processes and plant‐derived products, and are formed largely of polysaccharides synthesized by glycosyltransferases.

Plant cell wall glycosyltransferases use sugar nucleotides (NDP‐sugars) as donors, and transfer the sugar residue to acceptors to form glycosidic bonds.

These enzymes may transfer a single sugar molecule in nonprocessive fashion, or may transfer molecules iteratively to elongate a polymer. Processive glycosyltransferases are termed synthases whereas nonprocessive enzymes are simply termed glycosyltransferases.

Cellulose synthesis and callose synthesis occurs at the plasma membrane. All other plant cell wall polymers are synthesized within the Golgi and secreted to the cell wall in vesicles.

Nonprocessive glycosyltransferases tend to have a single transmembrane domain, whereas processive glycan synthases tend to have multiple transmembrane domains. There are exceptions to this rule, however.

Glycosyltransferases and glycan synthases tend to be highly specific for each donor and acceptor, and are specialized for formation of one type of carbohydrate linkage.

Numerous strategies exist for biochemical characterization of glycosyltransferases and glycan synthases, including heterologous expression and use of loss of function and gain‐of‐function genetic methods.

Plant cell wall glycosyltransferases and glycan synthases tend to be encoded by genes that are members of large multigene families.

Plant cell wall glycosyltransferases and glycan synthases often function in multimeric complexes.

Numerous enzymes involved in synthesis of plant cell wall biosynthesis have been identified. These include cellulose synthase, callose synthase, xyloglucan biosynthetic enzymes, pectin biosynthetic enzymes, mixed‐linkage glycan synthase and enzymes synthesizing mannans. However, many hundreds of enzymes remain to be identified at the biochemical level.
Ecological Genetics
Authors: Urban Mark C
Published: December 2008

Ecological genetics is the study of how ecologically relevant traits evolve in natural populations. Early research in ecological genetics demonstrated that natural selection often is strong enough to generate rapid adaptive changes in nature. Modern ecological geneticists combine field observations, laboratory experiments and rapidly improving laboratory techniques to further our understanding about how traits evolve in nature and also to identify which genes are evolving. Ecological geneticists increasingly explore how evolutionary dynamics shape ecological properties. As a consequence, ecological genetics is highly relevant to practical questions that lie at the interface of ecology and evolution.

Key concepts

Definition of ecological genetics.

How ecological genetics differs from similar fields?

Why ecologists need to know evolutionary biology and evolutionary biologists need to know ecology?

Major explanations of phenotypic variation in natural populations.

How experiments can discern among these explanations?

The importance of identifying the genes underlying adaptive trait variation.

Constraints to adaptive evolution.

How gene flow affects the evolution of interconnected populations?

How a consideration of multiple adapting species can alter evolutionary predictions?
Nonconsumptive Effects of Predators and Trait‐Mediated Indirect Effects
Authors: Peacor Scott D , Werner Earl E
Published: December 2008

Phenotypic plasticity in species’ traits is ubiquitous across taxa and habitats. This plasticity can affect the qualitative and quantitative nature of species interactions and thereby affect food webs. Empirical work has focused on predator–prey interactions, in part because most prey respond to predator presence through a suite of traits that reduce risk. These responses can incur costs in fitness correlates (e.g. growth and survival) of the prey, i.e. are nonconsumptive effects (NCEs) of predators. Further, these responses can lead to indirect effects transmitted through the prey to other species in the food web, termed trait‐mediated indirect effects (TMIEs). NCEs and TMIEs have been demonstrated in a wide range of communities and across diverse taxa. These effects can contribute substantially to the influence of predators (including through competition, trophic cascades and keystone predation), and therefore can play a critical role in the dynamics and structure of ecological communities.

Key concepts

Phenotypic plasticity in species traits is widespread and represented across diverse taxa and ecosystems.

To reduce predation risk, organisms respond to predator (including herbivore) presence by modifying traits, including developmental, morphological, physiological, life historical and behavioural characteristics.

Phenotypic responses to predators often incur a cost to prey fitness correlates such as growth rate and survival. These costs to fitness are termed nonconsumptive effects (NCEs) of the predator on its prey, to distinguish them from the consumptive effects (CEs) due to predation.

Phenotypic responses by prey to predators alter the nature of the interactions between prey and
other
(third) species. The predator is said to have a trait‐mediated indirect effect (TMIE) on the third species through induced changes in the intermediate species’ (prey's) traits.

Predator‐induced changes in prey traits can lead to TMIEs of the predator on prey resources (resulting in trait‐mediated trophic cascades), prey competitors and other predators of the prey.

NCEs and TMIEs can qualitatively change the nature of species interactions. For example, predator‐induced changes in prey traits can reverse competitive interactions, and lead to increases in prey growth rates due to strong TMIEs on prey resources.

NCEs and TMIEs can contribute strongly, and even dominate, the net effect of predators on prey and net indirect effect of the predator on species the prey interacts with. Thus, they can strongly affect prey population growth rates, community structure and ecosystem processes.

Factors, such as temperature, resource growth rates, prey density and prey–competitor density, can strongly influence the magnitude of NCEs and TMIEs.

It will be necessary to formally incorporate phenotypic responses of prey to predators into the conceptual foundations of ecology and strategies for the management of ecological systems.
Conservation and Behaviour
Authors: Buchholz Richard , Yamnik Patrick , Pulaski Cassan N , Campbell Chelsea A
Published: December 2008

Conservation behaviour is an area of conservation biology particularly suited to investigate problems of species endangerment associated with managing animals in fragmented habitats and isolated parks. It employs a theoretical framework that examines the mechanisms, development, function and phylogeny of behavioural variation in order to develop practical tools for preventing extinction. This framework can be used to attract animals to suitable habitat, restore migratory movements, identify individual reproductive strategies affecting conservation and focus protection on species most susceptible to extinction. The future success of conservation behaviour requires that behaviourists link individual variation in behaviour to processes that determine population viability.

Key concepts

Animal conservation will require active management.

Behavioural problems must be examined from four perspectives (mechanisms, ontogeny, adaptive function, phylogeny) simultaneously.

Behavioural strategies of individual animals change as habitat and populations are altered, and those changes could harm population viability.

Animal behaviourists must participate in conservation planning to protect the future of biodiversity.
Biological Stoichiometry
Authors: Frost Paul C , Elser James J
Published: December 2008

Biological stoichiometry is the study of the balance of energy and multiple chemical elements in living systems. This biological perspective compares the elemental requirements of organisms for growth, reproduction and maintenance with that provided by their nutritional resources. It has found a relatively greater flexibility in the elemental composition of primary producers compared to consumers, which leads to elemental imbalances between adjacent trophic levels. For individual organisms, the relatively low supply of an element can alter physiological processes underlying its acquisition, incorporation and release. When sustained, elemental imbalances slow growth and limit reproduction of organisms, particularly those with relatively high elemental requirements. Elemental imbalances have been documented in diverse ecosystems and at multiple trophic levels and have been shown to affect key ecological and evolutionary processes underlying population dynamics, trophic interactions and ecosystem function.
Identification of Improvised Inorganic Explosive Devices by Analysis of Postblast Residues Using Ion Chromatography and Capillary Electrophoresis
Authors: Hutchinson Joseph P. , Johns Cameron , Dicinoski Greg W. , Haddad Paul R.
Published: December 2008

Chemical analysis of the residues from improvised explosive devices (IEDs) has become a topical subject as a result of increased frequency of terrorist bomb attacks. There is a need to identify the type of explosive device and its composition, which in turn can assist in the identification of the perpetrators.

IEDs can either be organic based (high explosives) or the more easily produced inorganic‐based low explosives. Analysis of residues remaining after the deflagration of an inorganic IEDs presents several problems. A wide variety of ionic species may be present (such as unconsumed starting products, ionic species formed as part of the reaction) along with environmental or background species. Therefore, it is important that the target ions used to identify the device can be separated from other background ions present in the sample. The instrumental techniques of capillary electrophoresis (CE) and ion chromatography (IC) are proving to be ideally suited to this task. Both techniques have fundamental advantages, with CE offering highly efficient separations within a short run time, and IC offering high selectivity, sensitivity, and reproducibility.

In this article, an outline of the analytical methods used in this area is presented, with particular focus on the application of CE and IC. A brief literature review of published methods is provided, along with background information on inorganic explosives, sampling techniques, portable instrumentation, and recent developments.
In Vivo Evaluation of Leukemic Stem Cells through the Xenotransplantation Model
Authors: Bonnet Dominique
Published: December 2008

The xenotransplantation model has been instrumental for the identification and characterization of human leukemic stem cells. This unit describes our current method for the engraftment of human leukemic patients' samples in the xenotransplanted mouse model. We concentrate uniquely on the model of acute myeloid leukemia, as it was the first type of leukemia for which the xenotransplantation model was developed. Nevertheless, the Basic Protocol could be applied to other sorts of blood disorders. Curr. Protoc. Stem Cell Biol. 7:3.2.1‐3.2.11. © 2008 by John Wiley & Sons, Inc.
The relationship between socio‐sexual behavior and salivary cortisol in bonobos: tests of the tension regulation hypothesis
Authors: Hohmann Gottfried , Mundry Roger , Deschner Tobias
Published: December 2008

Bonobos are known for their pacifistic behavior and their large repertoire of behaviors that are thought to serve conflict resolution. One is an unusual form of ventro‐ventral mounting that facilitates genital contacts (GC). Various hypotheses have been proposed to explain its function. In this study we tested predictions of the tension regulation hypothesis using salivary cortisol as a marker for social stress. The results indicate a temporal relationship between GC and cortisol levels. Compared with baseline data and matched samples of unrestricted food access, rates of GC increased when access to food sources was restricted. Cortisol levels were highest when access to food was constrained. However, because the behavioral and hormonal responses occurred when viewing the stimulus at a distance and preceded the physical presence of the stimulus, we conclude that the anticipation of a competitive situation was sufficient to induce social stress. Contrary to our prediction, targets of aggression did not have higher rates of GC nor did they solicit GC more often than others. Furthermore, higher GC rates did not correlate with a more pronounced decrease in cortisol levels. Not all results obtained in this study supported the predictions concerning the regulatory function of GC on social tension and further research is needed to explore this question. However, the results indicate that the anticipation of competition may be sufficient to induce a costly physiological response, and that high levels of resource competition may have lasting effects on physical stress and stress management. Am. J. Primatol. 71:223–232, 2009. © 2008 Wiley‐Liss, Inc.
New Insights into the Neuromuscular Anatomy of the Ileocecal Valve
Authors: Cserni Tamas , Paran Sri , Kanyari Zsolt , O'Donnell Anne‐Marie , Kutasy Balazs , Nemeth Norbert , Puri Prem
Published: December 2008

The neuroanatomy of the ileocecal valve (ICV) is poorly understood. A better understanding of this important functional component of the gastrointestinal tract would enable surgeons to reconstruct an effective valve following surgical resection of the ICV. ICVs were examined in young pigs (N = 5) using frontal and transverse paraffin embedded and frozen sections. Hematoxylin+Eosin (H+E) staining, acetylcholinesterase (AchE), and NADPH‐diaphorase (NADPH‐d) histochemistry and protein gene product 9.5 (PGP 9.5) and C‐kit immunohistochemistry were performed. The H+E staining revealed that the ICV consists of three muscle layers: an external circular muscle layer continuous with that of the ileal circular muscle layer, an inner circular muscle layer continuous with that of the cecal circular muscle layer, and a single longitudinal muscle layer, which appears to be secondary to a fusion of the ileal and cecal longitudinal muscle layers. The AchE, NADPH‐d, and PGP 9.5 staining revealed two distinct coaxial myenteric plexuses, together with superficial and deep submucosal plexuses. The C‐kit immunostaining showed a continuous myenteric ICC network within the ICV. The structure of the neuromuscular components within the ICV suggests that the valve is a result of a simple intussusception of the terminal ileum into the cecum. This knowledge may help surgeons in their future attempts at reconstructing more anatomically and functionally suitable ICVs following surgical resection of native ICVs. Anat Rec 2009. © 2008 Wiley‐Liss, Inc.
Lineare Wärmebrücken in vakuumgedämmten Konstruktionen
Authors: Willems Wolfgang , Skottke Tanja
Published: December 2008

Die konsequent ansteigenden Anforderungen an den baulichen Wärmeschutz beheizter Gebäude führen unter bestimmten Randbedingungen zum Einsatz hochleistungsfähiger Wärmedämmelemente, deren Leistungsfähigkeit auf dem Einsatz der Vakuumtechnologie basiert. Das in den Elementen erzeugte Feinvakuum muss dauerhaft erhalten bleiben, um die exzellenten Wärmedämmeigenschaften gewährleisten zu können. Die dazu erforderliche permeationsdichte Einhüllung des Stützkernmaterials führt naturgemäß im Bereich der Elementkanten – und hier besonders im Bereich der bei größeren gedämmten Flächen erforderlichen Elementstöße – zu erhöhten Wärmeverlusten. Die vorliegende Arbeit quantifiziert diese zusätzlichen Wärmeverluste für unterschiedliche Konstruktionen auf der Basis von Messungen.
Brandschutz – Dokumentation einer Entwicklung
Authors: Schneider Ulrich , Kersken‐Bradley Marita , Kirchberger Hubert
Published: December 2008

Bis Ende der 1970er Jahre spielte sich der bauliche Brandschutz in den Materialprüfämtern ab und die Praxis war bemüht, die richtigen Tabellenwerte für die Feuerwiderstandsdauer zu finden. Mit den Beiträgen von Bub et al. wurde in Deutschland und Europa eine Entwicklung eingeleitet, die zunächst in internationalen technisch‐wissenschaftlichen Gremien wie dem CIB und dem JCSS aufgegriffen wurde und einen wesentlichen Grundstein für die Brandschutzteile der Eurocodes bildete. Weiterentwicklungen, wie im vfdb‐Leitfaden, wurden unter nicht unerheblicher Beteiligung von Hosser vorangebracht. Zu diesen Entwicklungen trug auch Gertis bei, indem an der Universität Stuttgart im Rahmen der Bauphysik als eine der ersten deutschen Universitäten, Brandschutz zumindest als Wahlpflichtfach angeboten wurde. Zwischenzeitlich sind europaweit eigenständige Masterstudiengänge entstanden. Dieser Beitrag ist eine Dokumentation der Anfänge, der Entwicklung und der wesentlichen Ergänzungen der letzten Jahre.
Salt solution flows in walls of monumental buildings
Authors: Kubik Jan , Kucharczyk Andrzej
Published: December 2008

The main cause of the degradation of monumental buildings' walls is capillary transport of moisture with dissolved salts. These processes are cyclic and lead to salt crystallization in the external parts of walls. In the present work the moisture measurements, which were made on the walls of a 13th Century church in Opole/Poland, are presented. It is also the superficial model for salt solution flows proposed.
Change of thermal conductivity of concrete caused by brittle damage evolution
Authors: Perkowski Zbigniew
Published: December 2008

A change of thermal conductivity caused by brittle damage evolution in concrete subjected to mechanical load is analysed in the paper. Considerations are illustrated by own experiment in which thermal conductivity of high performance concrete is compered for the loaded and not loaded laboratory‐samples. A quantitative assessment of the experiment is made on the basis of reciprocity theorem formulated for the heat transfer problem. To simplify the considerations it is assumed that damage in material is described by the scalar dimensionless parameter ω.
Effect of cracks on hygric and thermal characteristics of concrete
Authors: Vejmelková Eva , Padevět Pavel , Černý Robert
Published: December 2008

The effect of cracks on the moisture and heat transport and storage properties, basic physical properties and compressive strength of six different types of high performance concrete is analyzed in the paper. The cracks in the material specimens are randomly distributed, imposed by thermal treatment. Experimental results show that the presence of cracks affects all hygric and thermal parameters except for the specific heat capacity in quite a significant way. Also, the effects of microsilica addition and of the size and presence of aggregates are important. The liquid water transport is influenced by cracks, microsilica and aggregates in the most remarkable way, together with the compressive strength. Water vapor transport parameters, water sorption parameters, thermal conductivity and open porosity are also subject of significant changes and can indicate the damage induced by cracks with a sufficient sensitivity.
Einfluss des Verlustfaktors auf die Schalldämmung von Lochsteinmauerwerk
Authors: Schneider Martin , Fischer Heinz‐Martin
Published: December 2008

Bekanntlich hängt die Schalldämmung auch vom Verlustfaktor ab. Bei massiven Bauteilen wird dieser maßgeblich durch die Energieableitung über die Bauteilränder auf benachbarte Bauteile bestimmt, so dass die aktuellen Einbaubedingungen die Schalldämmung beeinflussen. Dieser Effekt wird in den Berechnungsmodellen der EN 12354 durch die sogenannte In‐situ‐Korrektur berücksichtigt. Dabei wird der bei einer Laborprüfung vorhandene Gesamtverlustfaktor des geprüften Bauteils auf den im realen Gebäude zu erwartenden Verlustfaktor umgerechnet. Für Hochlochziegel mit möglichen Steinresonanzen ab etwa 800 Hz wird dargestellt, wie hierfür die Verlustfaktor‐Korrektur anzuwenden ist. Es zeigt sich, dass die Korrektur im Prinzip gleich durchgeführt werden kann wie bei homogenem Mauerwerk, allerdings nur bis in den Bereich der ersten Steinresonanz. Im darüber liegenden Frequenzbereich erweist sich die Schalldämmung als von den Einbaubedingungen unabhängig, so dass dort keine Verlustfaktorkorrektur mehr durchgeführt werden darf.
Development of genetic approaches for the methane‐producing archaebacterium Methanococcus maripaludis
Authors: Whitman William B. , Tumbula Debra L. , Yu Jae‐Pil , Kim Wonduck
Published: December 2008

Methanococcus maripaludis is a strict anaerobe that utilizes H2 or formate as an electron donor for CO2 reduction to methane. Recent progress in development of genetic systems in this archaebacterium makes it an excellent model system for molecular and biochemical studies. This progress includes development of methods for growth on solid medium, enriching auxotrophic mutants, efficient transformation, and random insertional inactivation of genes. Genetic markers for both puromycin and neomycin resistance are available. Lastly, a shuttle vector has been constructed from a cryptic methanococcal plasmid. These technical advances made it possible to utilize genetic approaches for the study of autotrophic CO2 assimilation in methanococci.
Microbial and plant metabolism of NO
Authors: Payne W. J. , Liu M.‐Y. , Bursakov S. A. , Le Gall J.
Published: December 2008

During microbial denitrification, NO is produced by reduction of nitrite by either the reduced high spin d1 hemes in a unique reductase (NIR) or at the expense of a blue copper protein that transfers electrons that move first to a type I copper and then to a type II copper in a unique trimeric NIR. This latter type of NIR is also produced by several denitrifying filamentous fungi. Reduction of NO is then carried out by either a specific cytochrome bc complex NOR in denitrifying bacteria or a unique cytochrome P‐450 in denitrifying filamentous fungi. NO is also produced by an anomalous reaction of a molybdoprotein, nitrate reductase (NAR), acting on an odd substrate, NO2−. NO is also reduced by a multiheme NIR that serves physiologically for reduction of NO2− to NH3. This type NIR reduces NO to either N2O, if only partially reduced, or NH3, if fully reduced, when it encounters NO. This multiheme NIR is very sensitive to cyanide. Transcription of the genes for NIR and NOR production in a denitrifier is activated by NO, a process that also requires the presence of the gene product, a transcriptional activator, NnrR.
The Biochemistry of Drug Metabolism – An Introduction
Authors: Krämer Stefanie D. , Testa Bernard
Published: December 2008

This review is part of a series of review articles on the metabolism of drugs and other xenobiotics published inChemistry & Biodiversity.After a thorough discussion of metabolic reactions and their enzymes, this article focuses on genetically determined differences in drug and xenobiotic metabolism. After a short introduction on the causes for genetic differences, the first focus is on species differences in drug and xenobiotic metabolism. A major chapter is then dedicated to clinically relevant genetic polymorphisms in human drug metabolism and resultant ethnic differences. The last two chapters deal with sex‐dependent differences in drug metabolism and personalized pharmacotherapy related to inter‐individual differences in drug metabolism.
Intraspecific Variation of the Cephalic Labial Gland Secretions in Bombus terrestris (L.) (Hymenoptera: Apidae)
Authors: Coppée Audrey , Terzo Michaël , Valterova Irena , Rasmont Pierre
Published: December 2008

Variations of secretions of the cephalic part of the labial glands from four different subspecies of Bombus terrestris, B. t. terrestris, B. t. lusitanicus, B. t. sassaricus, and B. t. dalmatinus, were investigated. 95 compounds were detected in the whole data set: 54 in B. t. terrestris, 54 in B. t. lusitanicus, 48 in B. t. sassaricus, and 44 in B. t. dalmatinus. The (E)‐2,3‐dihydrofarnesol is the main compound in B. t. dalmatinus and B. t. sassaricus, while it is dihydrofarnesyl dodecanoate in B. t. terrestris and B. t. lusitanicus. A principal component analysis produced a pattern showing three well distinct groups corresponding to dalmatinus, sassaricus, and terrestris+lusitanicus.
Two New Antioxidant Phenylpropanoids from Lindelofia stylosa
Authors: Choudhary M. Iqbal , Begum Afshan , Abbaskhan Ahmed , Musharraf Syed Ghulam , Ejaz Asma , Atta‐ur‐Rahman
Published: December 2008

Two new phenylpropanoids were isolated from Lindelofia stylosa (Kar. and Kir.) and characterized as 4‐hydroxy‐N‐{4‐[(E)‐3‐(4‐hydroxy‐3‐methoxyphenyl)prop‐2‐enamido]butyl}benzamide (1) and 2‐[3‐hydroxy‐4‐(4‐hydroxyphenoxy)phenyl]‐1‐(methoxycarbonyl)ethyl (E)‐3‐(3,4‐dihydroxyphenyl)prop‐2‐enoate (2). Four known compounds, i.e. two phenylpropanoids, p‐coumaric acid (=(E)‐3‐(4‐hydroxyphenyl)prop‐2‐enoic acid; 3) and ferulic acid (=(E)‐3‐(4‐hydroxy‐3‐methoxyphenyl)prop‐2‐enoic acid; 4), and two naphthalene glycosides, 8‐O‐β‐D‐glucopyranosyltorachrysone (5) and 8‐O‐β‐D‐glucopyranosyl‐6‐demethoxytorachrysone (6), were also isolated for the first time from the plant. Compounds 1–6 were subjected to various antioxidant assays, including DPPH radical‐ and superoxide anion‐scavenging, and Fe2+‐chelation assays. Compound 2 was found to be most active in all assays with potency nearly similar to that of propyl gallate. Besides 2, compounds 1 and 5 were also found to be active in DPPH radical‐scavenging standard assay.
Polyprenylated Xanthones from Garcinia lancilimba Showing Apoptotic Effects against HeLa‐C3 Cells
Authors: Han Quan‐Bing , Tian Hong‐Lei , Yang Nian‐Yun , Qiao Chun‐Feng , Song Jing‐Zheng , Chang Donald C. , Luo Kathy Q. , Xu Hong‐Xi
Published: December 2008

Three new prenylated xanthones, 1–3, along with ten known compounds, were isolated from the stem bark of Garcinia lancilimba. Their structures were elucidated by extensive spectroscopic analysis, including 1D‐ and 2D‐NMR spectra, as well as HR‐MS experiments. Some of these compounds showed apoptotic effects or growth‐inhibition effects against HeLa cells expressing a caspase sensor protein.
Coating of Highly Porous Fiber Matrices by Atomic Layer Deposition
Authors: Kemell Marianna , Ritala Mikko , Leskelä Markku , Groenen Roland , Lindfors Sven
Published: December 2008

The potential of atomic layer deposition (ALD) in the coating of highly porous, 0.5 mm thick, metal fiber matrices is explored. Three different reactor types are compared for ALD of Al2O3 thin films from trimethylaluminum and water. Both an evacuation‐type and a flow‐type process are successful in forming conformal Al2O3 coatings on the fibers. The coatings are able to protect the fibers against electrochemical corrosion and thermal oxidation. In addition, a metallic Ir thin film is deposited by ALD on one of the Al2O3‐coated fiber matrices. This kind of a structure could be used, for example, as a catalytic filter.
Freestanding Ge/SiO2 Core/Shell Nanoparticles Formed via Metastable SiO2 Hollow Nanospheres on a Si Wafer
Authors: Park Kwang‐Tae , Um Han‐Don , Jee Sang‐Won , Jung Jin‐Young , Park Yun Chang , Yang Jun Mo , Lee Jung‐Ho
Published: December 2008

Communication: Freestanding Ge/SiO2 core/shell nanoparticles were synthesized via metastable SiO2 hollow nanospheres by atmospheric‐pressure thermal chemical vapor deposition (APCVD) using SiCl4 and GeCl4 source gases. The Ge‐core and SiO2‐shell thicknesses could be controlled by adjusting the annealing time and the source gas ratio. These nanoparticles might be useful as labeling markers for fluorescent applications.
Wide‐area estimates of saltcedar (Tamarix spp.) evapotranspiration on the lower Colorado River measured by heat balance and remote sensing methods
Authors: Nagler Pamela L. , Morino Kiyomi , Didan Kamel , Erker Joseph , Osterberg John , Hultine Kevin R. , Glenn Edward P.
Published: December 2008

In many places along the lower Colorado River, saltcedar (Tamarix spp) has replaced the native shrubs and trees, including arrowweed, mesquite, cottonwood and willows. Some have advocated that by removing saltcedar, we could save water and create environments more favourable to these native species. To test these assumptions we compared sap flux measurements of water used by native species in contrast to saltcedar, and compared soil salinity, ground water depth and soil moisture across a gradient of 200–1500 m from the river's edge on a floodplain terrace at Cibola National Wildlife Refuge (CNWR). We found that the fraction of land covered (fc) with vegetation in 2005–2007 was similar to that occupied by native vegetation in 1938 using satellite‐derived estimates and reprocessed aerial photographs scaled to comparable spatial resolutions (3–4 m). We converted fc to estimates of leaf area index (LAI) through point sampling and destructive analyses (r2 = 0·82). Saltcedar LAI averaged 2·54 with an fc of 0·80, and reached a maximum of 3·7 with an fc of 0·95. The ranges in fc and LAI are similar to those reported for native vegetation elsewhere and from the 1938 photographs over the study site. On‐site measurements of water use and soil and aquifer properties confirmed that although saltcedar grows in areas where salinity has increased much better than native shrubs and trees, rates of transpiration are similar. Annual water use over CNWR was about 1·15 m year−1. Copyright © 2008 John Wiley & Sons, Ltd.
Anion Coordination Effect on the Nuclearity of CoII, NiII, CuII, and ZnII Complexes with a Benzimidazole Pendant‐Armed Crown
Authors: Vaiana Lea , Esteban‐Gómez David , Mato‐Iglesias Marta , Platas‐Iglesias Carlos , de Blas Andrés , Rodríguez‐Blas Teresa
Published: December 2008

The study presented in this paper provides a rare example of a macrocyclic receptor allowing the formation of mono‐ or binuclear complexes on the same first‐row transition‐metal guest cation depending on the nature of the counterion present. Reaction of N,N′‐bis(benzimidazol‐2‐ylmethyl)‐4,13‐diaza‐18‐crown‐6 (L4) with CoII, NiII, CuII, or ZnII perchlorates leads to the formation of the expected mononuclear complexes with the metal ion showing a distorted octahedral coordination environment. In these complexes, the metal ion is placed at one end of the macrocyclic cavity, and two of the oxygen atoms of the crown ether moiety remain uncoordinated. 1H and 13C NMR spectroscopic studies on the diamagnetic [Zn(L4)]2+ complex indicate that the asymmetric coordination of the metal ion inside the macrocyclic cavity is maintained in acetonitrile solution, but translocation of the ZnII ion from one end of the macrobicyclic cavity to the second one occurs. However, reaction of L4 with CoII, NiII, or CuII perchlorates in the presence of chloride anions results in the formation of binuclear complexes where the metal ion is either five‐coordinate in a distorted trigonal bipyramidal coordination environment (Co or Cu) or six‐coordinate in a distorted octahedral geometry (Ni), and a chloride anion coordinates to each of the two metal ions in all cases. The ZnII ion behaves in a different way, and addition of chloride anions to the ZnII perchlorate in the presence of L4 does not lead to the formation of a binuclear complex. The formation of these binuclear systems was followed by spectrophotometric titrations of the mononuclear [M(L4)](ClO4)2 complexes with [nBu4N]Cl in acetonitrile solution indicating the formation of a [M2(L4)(Cl)]2+ intermediate species, followed by the formation of the binuclear complex [M2(L4)(Cl)2]2+ (M = Co, Ni, or Cu). (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)
Ligand Effects on the Mechanisms of Thermal Bond Activation in the Gas‐Phase Reactions NiX+/CH4→Ni(CH3)+/HX (X=H, CH3, OH, F). Short Communication
Authors: Schlangen Maria , Schwarz Helmut
Published: December 2008

The thermal ion‐molecule reactions NiX++CH4→Ni(CH3)++HX (X=H, CH3, OH, F) have been studied by mass spectrometric methods, and the experimental data are complemented by density functional theory (DFT)‐based computations. With regard to mechanistic aspects, a rather coherent picture emerges such that, for none of the systems studied, oxidative addition/reductive elimination pathways are involved. Rather, the energetically most favored variant corresponds to a σ‐complex‐assisted metathesis (σ‐CAM). For X=H and CH3, the ligand exchange follows a ‘two‐state reactivity (TSR)’ scenario such that, in the course of the thermal reaction, a twofold spin inversion, i.e., triplet→singlet→triplet, is involved. This TSR feature bypasses the energetically high‐lying transition state of the adiabatic ground‐state triplet surface. In contrast, for X=F, the exothermic ligand exchange proceeds adiabatically on the triplet ground state, and some arguments are proposed to account for the different behavior of NiX+/Ni(CH3)+ (X=H, CH3) vs. NiF+. While the couple Ni(OH)+/CH4 does not undergo a thermal ligand switch, the DFT computations suggest a potential‐energy surface that is mechanistically comparable to the NiF+/CH4 system. Obviously, the ligands X act as a mechanistic distributor to switch between single vs. two‐state reactivity patterns.
Photocycloaddition Reactions of 2‐(Alk‐3‐en‐1‐ynyl)cyclohex‐2‐enones
Authors: Möbius Janne , Margaretha Paul
Published: December 2008

The newly synthesized 2‐(alk‐3‐en‐1‐ynyl)cyclohex‐2‐enones 4 undergo photodimerization (chemo‐ and regio‐)selectively at the exocyclic CC bond to give diastereoisomeric mixtures of 1,2‐dialkynyl‐1,2‐dimethylcyclobutanes. On irradiation of 4 in the presence of 2‐chloroacrylonitrile, cyclobutane formation occurs again (chemo‐ and regio‐)selectively at the exocyclic CC bond to afford diastereoisomeric mixtures of 2‐alkynyl‐1‐chloro‐2‐methylcyclobutanecarbonitriles. Similarly, compounds 4 undergo photoaddition to 2,3‐dimethylbuta‐1,3‐diene exclusively at the exocyclic CC bond to afford mixtures of [2+2] and [4+2] cycloadducts.
Dimeric Diterpenes from the Roots of the Mangrove Plant Ceriops tagal
Authors: Chen Jun‐De , Qiu Yan , Yang Zhi‐Wei , Lin Peng , Lin Yi‐Ming
Published: December 2008

Three new dimeric diterpenes, tagalsin L (1), tagalsin M (2), and tagalsin N (3) were isolated from the roots of the mangrove plant Ceriops tagal. Their structures and relative configurations were elucidated by means of extensive IR, NMR, and MS analyses.
New Verticillane‐Type Diterpenoids from the Taiwanese Soft Coral Cespitularia hypotentaculata
Authors: Cheng Yuan‐Bin , Lo Kuang‐Liang , Chen Ching‐Yeu , Khalil Ashraf Taha , Shen Ya‐Ching
Published: December 2008

Investigation of the MeOH/CH2Cl2 extract of the soft coral Cespitularia hypotentaculata collected in Taiwan has resulted in the isolation of four new verticillane‐type diterpenoids, cespihypotins M–P (1–4). Compounds 2 and 3 are C(20)‐epimers. Compound 4 with a CO group at C(10) and a methoxycarbonyl group at C(12) may be an important precursor of cespitularins and cespihypotins. The structures of these compounds were determined on the basis of spectroscopic analyses.
The Late Pleistocene clastic deposits in the Romito Cave, southern Italy: a proxy record of environmental changes and human presence
Authors: Ghinassi Massimiliano , Colonese Andrè C. , Giuseppe Zelia Di , Govoni Lisa , Vetro Domenico Lo , Malavasi Giulia , Martini Fabio , Ricciardi Silvia , Sala Benedetto
Published: December 2008

Clastic sediments deposited in caves and rock shelters bear peculiar sedimentological characteristics and have seldom been considered as a high‐resolution proxy record of climatic or environmental changes. The Romito Cave has its entrance at 275 m above sea level, about 25 km from the Tyrrhenian coast of Calabria, southern Italy. New archaeological excavation performed since 2000 has revealed a sedimentary succession spanning the record of Gravettian to Late Epigravettian cultures (Late Pleistocene). The present study focuses on the lower part (2.5 m thick) of the succession, where three main unconformity‐bounded stratigraphic units have been recognised (labelled RM1–3). Each unit consists of water‐lain deposits indicating high‐ to low‐competence flow, capped with anthropogenic deposits. The gradual deactivation and reactivation of the water drainage between 23 475 ± 190 and 16 250 ± 500 cal. a BP is correlated with regional precipitation changes due to the onset of dry climatic conditions of the Last Glacial Maximum. However, the deactivation of cave drainage after the deposition of unit RM3, around 15 400 ± 500 cal. a BP, deviates from the regional hydrological trend of progressively increasing water discharges and is attributed to the drainage cut‐off by probable cave wall collapses. Copyright © 2008 John Wiley & Sons, Ltd.
Core Crosslinking of Biodegradable Block Copolymer Micelles Based on Poly(ester carbonate)
Authors: Hu Xiuli , Chen Xuesi , Wei Jizheng , Liu Shi , Jing Xiabin
Published: December 2008

A biodegradable amphiphilic block copolymer, PEG‐b‐P(LA‐co‐MAC), was used to prepare spherical micelles consisting of a hydrophobic P(LA‐co‐MAC) core and a hydrophilic PEG shell. To improve their stability, the micelles were crosslinked by radical polymerization of the double bonds in the hydrophobic blocks. The crosslinked micelles had similar sizes and a narrow size distribution compared to their uncrosslinked precursor. The improved stability of the crosslinked micelles was confirmed by measurements of the CMC and a thermodynamic investigation. These micelles can internalize into Hela cells in vitro as demonstrated by inverted fluorescence microscopy and CLSM. These stabilized nanoscale micelles have potential use in biomedical applications such as drug delivery and disease diagnosis.

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Polyelectrolyte Coated PLGA Nanoparticles: Templation and Release Behavior
Authors: Zhou Jie , Moya Sergio , Ma Lie , Gao Changyou , Shen Jiacong
Published: December 2008

Poly[(D,L‐lactide)‐co‐glycolide] nanoparticles coated with polyethyleneimine on their surface were prepared by an emulsification‐solvent evaporation method and subsequently surface modified by LBL assembly. The assembly of poly(acrylic acid) and polyethyleneimine on a planar substrate and on the PLGA nanoparticles was monitored by QCM‐D,ζ‐potential, flow cytometry and TEM. Carboxylic and amino groups in the multilayers were crosslinked by carbodiimide condensation, which was also later used to graft poly(ethylene glycol) (PEG). Rhodamine 6G, 5(6)‐carboxyfluorescein and fluorescein were incorporated into the nanoparticles and their release profiles were recorded at 60 °C and at 37 °C for rhodamine 6G, for nanoparticles with a multilayer coating, and those that were crosslinked and grafted with PEG.

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Hybrid Microgels with Antibacterial Properties
Authors: Häntzschel Nadine , Hund Rolf‐Dieter , Hund Heike , Schrinner Marc , Lück Christian , Pich Andrij
Published: December 2008

In the present work, we have used aqueous microgels as containers for the deposition of silver nanoparticles (AgNPs). It has been shown that AgNPs can be effectively incorporated in the microgel interior during the in situ reduction of silver ions. Obtained hybrid microgels with variable AgNPs loading (from 1 to 12 wt.‐%) have been used as antibacterial agents for two bacteria types. The experimental results indicate that porous microgel structure allows the release of the silver ions from the AgNPs surface into an aqueous phase. This ensures effective reduction in the number of bacterial colonies in test plates and complete bacteria killing. The antibacterial efficiency of the microgel particles increases with AgNPs loading.

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Cellulose Derivatives Carrying Triphenylamine (TPA) Moieties: Synthesis and Electro‐Optical Properties
Authors: Qu Jinqing , Liao Wenbo , Chen Huanqin , Masuda Toshio
Published: December 2008

A novel ethyl cellulose derivative [poly(1)] that carries triphenylamine moieties is synthesized with a moderate number‐average molecular weight up to 78 200 in 85% yield by the reaction of 4‐(diphenylamino)benzoic acid with the residual hydroxy group of ethyl cellulose. Poly(1) is soluble in common organic solvents including toluene, CHCl3, CH2Cl2, and tetrahydrofuran while insoluble in hexane, diethyl ether, and methanol. The polymer emits blue–green fluorescence with quantum yields up to 65% in CHCl3 and displays unique solvatochromism. The cyclic voltammograms of poly(1) indicate that the polymer carrying TPA moieties is electrochemically redox active. The onset temperature of weight loss of the poly(1) is about 177 °C according to thermogravimetric analysis in air.

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Phenolic Hydroxy Groups Incorporated for the Peroxidase‐Catalyzed Gelation of a Carboxymethylcellulose Support: Cellular Adhesion and Proliferation
Authors: Ogushi Yuko , Sakai Shinji , Kawakami Koei
Published: December 2008

The effect of Ph‐OH group content on gelation time, mechanical properties, hydrophobicity, and cellular adhesiveness of hydrogels produced from carboxymethylcellulose derivatives is investigated. A higher Ph‐OH group content induces faster gelation and yields more brittle and hydrophobic gels. After 4 h of seeding, a larger number of L929 fibroblasts adhere to the hydrogel of the CMC‐Ph that contains 15.4 Ph‐OH groups per 100 repeat units of uronic acid (97% adhesion rate) than to the gel of CMC‐Ph with only 8.4 Ph‐OH groups (62% adhesion rate). The results demonstrate that controlling the Ph‐OH group content is an effective and useful way to control cellular adhesion and proliferation on the hydrogels, as well as gelation time and mechanical properties of the gels.

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Metal dusting in CCR platforming unit
Authors: Dampc J. , Grzesik Z. , Hucińska J.
Published: December 2008

The mechanism of metal dusting of 9Cr‐1Mo steel in CCR platforming unit, based on examinations of a charge heater tube, is presented. The tube operated for 10 years, and the metal skin temperature was about 600 °C. The feed was composed of hydrotreated naphtha and hydrogen gas. The mechanism of the corrosion was elucidated using scanning electron microscopy, electron probe microanalysis and X‐ray diffraction technique. It has been found that the carbon deposition on the steel surface and its inward diffusion into the steel is accompanied by the outward diffusion of carbide forming elements, i.e. chromium and molybdenum. At an advanced stage of the metal dusting process a thin layer of fine chromium‐rich carbides beneath the steel surface exists. The layer is followed by a porous zone composed of big degraded primary carbides and fine carbides instead of alloy ferrite, with chromium and molybdenum content higher than the ferrite inside the tube wall. On the steel surface, a layer of coke composed of graphite, iron and M7C3 carbides is formed and the uniform wastage of the steel takes place. Possible influence of some sulphur additions to the CCR platformer feed during the future service on degradation of the subsurface material has been considered.
Exfoliation corrosion of 7150 Al alloy with various tempers and its electrochemical impedance spectroscopy in EXCO solution
Authors: Li J. F. , Jia Z. Q. , Li C. X. , Birbilis N. , Cai C.
Published: December 2008

The exfoliation corrosion susceptibility and electrochemical impedance spectroscopy (EIS) of 7150 Al alloys with T6, T73, and RRA (retrogression at 175 °C for 3 h) tempers in EXCO solution were investigated. The anodic equilibrium precipitate η(MgZn2) is continuous or closely spaced at the grain boundaries in the 7150‐T6 Al alloy, resulting in its greatest susceptibility to exfoliation corrosion. The grain boundary η precipitates in the RRA and T73 treated 7150 Al alloys are coarsened and show a clear discontinuous nature; they possess similar exfoliation corrosion sensitivity and their exfoliation corrosion resistance is greatly increased. At the beginning of immersion in EXCO solution, the EIS plot of the 7150 Al alloys is composed of a capacitive arc in the high to medium frequency range and an inductive component in the medium to low frequency range. As immersion time is increased, exfoliation corrosion with different corrosion ratings occurs on the surface of the 7150 Al alloy with various tempers, two capacitive arcs appear in the high to medium and medium to low frequency ranges, respectively. The fitted medium to low frequency capacitance C2 of 7150‐T6 Al alloy, corresponding to the new surface caused by the exfoliation corrosion, is much greater than that of the T73 and RRA treated 7150 Al alloy, which is consistent with the greatest exfoliation corrosion susceptibility of the 7150‐T6 Al alloy.
Influence of turbulent flow on the corrosion of Al‐Zn‐Mg galvanic anode in artificial seawater media
Authors: Quevedo M. C. , Genesca J.
Published: December 2008

The effect of hydrodynamics on the corrosion of Al(14 wt%)‐Zn(8 wt%)‐Mg alloy in artificial seawater media at room temperature was studied in a rotating cylinder electrode (RCE) system under turbulent flow conditions. Five different rotation rates were studied: 100, 1000, 3000, 5000, and 7000 rpm. The corrosion rates were measured by electrochemical impedance spectroscopy (EIS). For the system studied, the steady‐state corrosion potential increased with increase in rotation rate. The effect of increasing the rotation rate is to increase the availability of oxygen at the surface, which in turn will polarize the corrosion reaction in the more noble direction. The corrosion rate also increases with increase in RCE rotation rate. This reflects the fact that the rate of corrosion is controlled, at least in part, by the rate of mass transfer. In this case, the effect of increase in the rotation rate on the corrosion rate is to increase the interfacial concentration of the reactant (oxygen).
Polytriarylamines with On‐Chain Crystal Violet Moieties
Authors: Dumsch Ines , Kudla Christof J. , Scherf Ullrich
Published: December 2008

A novel polytriarylamine (PTAA)‐type alternating copolymer with on‐chain crystal violet moieties has been generated which shows the expected strong dependence of its UV‐Vis absorption spectrum from the pH value of the surrounding medium. Starting from the colorless leucocrystal violet form subsequent protonation/water elimination (by trifluoroacetic acid) leads to the formation of a blue colored, cationic copolymer with on‐chain crystal violet units that displays a characteristic Vis absorption band peaking at 627 nm. Further protonation leads to the generation of the corresponding dicationic species which is accompanied by a red shift of the long wavelength absorption maximum to 713 nm. The novel pH‐sensitive polytriarylamine derivatives will be investigated as potential p‐type semiconductors for OFET (gas) sensors.

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