bluuebunny/crossref_metadata_2025 huggingface dataset:
Multi-channel ground-penetrating radar to explore spatial variations in thaw depth and moisture content in the active layer of a permafrost site
Authors: Wollschläger U. , Gerhards H. , Yu Q. , Roth K.
Published: August 2010

Abstract. Multi-channel ground-penetrating radar (GPR) was applied at a permafrost site on the Tibetan Plateau to investigate the influence of surface properties and soil texture on the late-summer thaw depth and average soil moisture content of the active layer. Measurements were conducted on an approximately 85 × 60 m2 sized area with surface and soil textural properties that ranged from medium to coarse textured bare soil to finer textured, sparsely vegetated areas covered with fine, wind blown sand, and it included the bed of a gravel road. The survey allowed a clear differentiation of the various units. It showed (i) a shallow thaw depth and low average soil moisture content below the sand-covered, vegetated area, (ii) an intermediate thaw depth and high average soil moisture content along the gravel road, and (iii) an intermediate to deep thaw depth and low to intermediate average soil moisture content in the bare soil terrain. From our measurements, we found hypotheses for the permafrost processes at this site leading to the observed late-summer thaw depth and soil moisture conditions. The study clearly indicates the complicated interactions between surface and subsurface state variables and processes in this environment. Multi-channel GPR is an operational technology to efficiently study such a system at scales varying from a few meters to a few kilometers.
Production of Very Fine Grained Mg–3%Al–1%Zn Alloy by Continuous Extrusion Forming (CONFORM)
Authors: He Youliang , Gao Fei , Song Baoyun , Li Jian , Fu Rong , Wu Guiming
Published: August 2010

Very fine grained (∼2 µm) Mg–3%Al–1%Zn alloy rods are produced using an industrial continuous extrusion forming (CONFORM) machine. Cast rods (grain size ∼150 µm) are utilized as the feedstock and significant grain refinement is achieved in a single extrusion process. Tensile elongation of about 200% is achieved at 473 K using the extruded sample. This demonstrates the potential application of CONFORM as a continuous severe plastic deformation process to produce very fine grained metals to attain superplastic properties.
Toughness Measurement of Cemented Carbides with Chevron‐Notched Three‐Point Bend Test
Authors: Deng Xin , Bitler Jon , Chawla Krishan K. , Patterson Burton R.
Published: August 2010

Plane‐strain fracture toughness is a critical property of metal matrix composites, especially for cemented carbides, ceramics, and tool materials. In this study, we have investigated, numerically and experimentally, the method involving three‐point bend test of a chevron‐notched specimen to evaluate fracture toughness of cemented carbides. A comprehensive formula is presented for a wide range of test dimensions and chevron notch angles. Cemented carbides with different toughness levels were tested. The proposed formula provides a more accurate and valid expression compared with existing methods. It offers an accurate, convenient, and practical method for toughness testing of cemented carbide, ceramics, tool materials, and other metal matrix composites.
Titanium Containing γ‐MnO2 (TM) Hollow Spheres: One‐Step Synthesis and Catalytic Activities in Li/Air Batteries and Oxidative Chemical Reactions
Authors: Jin Lei , Xu Linping , Morein Christine , Chen Chun‐hu , Lai Monique , Dharmarathna Saminda , Dobley Arthur , Suib Steven L.
Published: August 2010

Titanium containing γ‐MnO2 octahedral molecular sieves having hollow sphere structures are successfully prepared for the first time using a one‐step synthesis method. Titanium cations are used as structure‐directing agents in the synthesis process. The assembly of the hollow spheres is carried out at the beginning of the process. Various techniques including XRD, N2 adsorption, SEM, EDX, RAMAN, TEM, XPS, and TGA are employed for the materials characterization. Ti is incorporated into the MnO2 framework in isolated sites, and TiO2 phases (anatase and rutile) are not observed. When introduced in medium‐sized lithium‐air batteries, the materials give very high specific capacity (up to 2.3 A h g−1). These materials are also catalytically tested in the oxidation of toluene with molecular oxygen at atmospheric pressure, showing significant oxidative catalytic activities in this difficult chemical reaction.
Organic Electronics: High Tg Cyclic Olefin Copolymer Gate Dielectrics for N,N′‐Ditridecyl Perylene Diimide Based Field‐Effect Transistors: Improving Performance and Stability with Thermal Treatment (Adv. Funct. Mater. 16/2010)
Authors: Jang Jaeyoung , Nam Sooji , Chung Dae Sung , Kim Se Hyun , Yun Won Min , Park Chan Eon
Published: August 2010

A novel application of ethylene‐norbornene cyclic olefin copolymers (COC) as gate dielectric layers in organic field‐effect transistors (OFETs) that require thermal annealing as a strategy for improving the OFET performance and stability is reported. The thermally‐treated N,N′‐ditridecyl perylene diimide (PTCDI‐C13)‐based n‐type FETs using a COC/SiO2 gate dielectric show remarkably enhanced atmospheric performance and stability. The COC gate dielectric layer displays a hydrophobic surface (water contact angle = 95° ± 1°) and high thermal stability (glass transition temperature = 181 °C) without producing crosslinking. After thermal annealing, the crystallinity improves and the grain size of PTCDI‐C13 domains grown on the COC/SiO2 gate dielectric increases significantly. The resulting n‐type FETs exhibit high atmospheric field‐effect mobilities, up to 0.90 cm2 V−1 s−1 in the 20 V saturation regime and long‐term stability with respect to H2O/O2 degradation, hysteresis, or sweep‐stress over 110 days. By integrating the n‐type FETs with p‐type pentacene‐based FETs in a single device, high performance organic complementary inverters that exhibit high gain (exceeding 45 in ambient air) are realized.
Nanoarrays: Cooperative Near‐Field Surface Plasmon Enhanced Quantum Dot Nanoarrays (Adv. Funct. Mater. 16/2010)
Authors: Leong Kirsty , Chen Yeechi , Masiello David J. , Zin Melvin T. , Hnilova Marketa , Ma Hong , Tamerler Candan , Sarikaya Mehmet , Ginger David S. , Jen Alex K.‐Y.
Published: August 2010

Fluorescence from quantum dots (QDs) sandwiched between colloidal gold nanoparticles and lithographically created metal nanoarrays is studied using engineered peptides as binding agents. For optimized structures, a 15‐fold increase is observed in the brightness of the QDs due to plasmon‐enhanced fluorescence. This enhanced brightness is achieved by systematically tuning the vertical distance of the QD from the gold nanoparticles using solid‐specific peptide linkers and by optimizing the localized surface plasmon resonance by varying the geometric arrangement of the patterned gold nanoarray. The size and pitch of the patterned array affect the observed enhancement, and sandwiching the QDs between the patterned features and colloidal gold nanoparticles yields even larger enhancements due to the increase in local electromagnetic hot spots induced by the increased surface roughness. The use of bifunctional biomolecular linkers to control the formation of hot spots in sandwich structures provides new ways to fabricate hybrid nanomaterials of architecturally induced functionality for biotechnology and photonics.
Chemiluminescence‐Generating Nanoreactor Formulation for Near‐Infrared Imaging of Hydrogen Peroxide and Glucose Level in vivo
Authors: Lim Chang‐Keun , Lee Yong‐Deok , Na Jinhee , Oh Jung Min , Her Song , Kim Kwangmeyung , Choi Kuiwon , Kim Sehoon , Kwon Ick Chan
Published: August 2010

Water‐dispersed all‐in‐one nanoprobes composed of densely integrated peroxyoxalate fuel and a cyanine dye are formulated to optimize the nanoscopic chemiluminescence reaction. It is demonstrated that the chemiluminescent nanoformulation can generate bright near‐infrared signal in response to external hydrogen peroxide that is biologically implicated with cell signaling and diseases. Successful imaging of endogenously overproduces hydrogen peroxide and indirect determination of glucose level in vivo with the chemiluminescent nanoprobes offers an opportunity for early diagnosis of diseases.
One‐Pot Suzuki/Heck Sequence for the Synthesis of (E)‐Stilbenes Featuring a Recyclable Silica‐Supported Palladium Catalyst via a Multi‐Component Reaction in 1,3‐Propanediol
Authors: Joucla Lionel , Cusati Giuseppe , Pinel Catherine , Djakovitch Laurent
Published: August 2010

The synthesis of (E)‐stilbenes was performed following a one‐pot Suzuki/Heck sequence through the use of potassium vinyltrifluoroborate. The combination of heterogeneous palladium/silica (Pd/SiO2) catalyst with potassium phosphate monohydrate (K3PO4⋅H2O) as base resulted in useful to good isolated yields regardless of the ortho‐, meta‐ or para‐substitution of the aryl halides employed. In a sustainable approach, we found that bio‐sourced 1,3‐propanediol could advantageously replace N‐methylpyrrolidone (NMP) as similar yields were obtained. Moreover, the reactivity gap between aryl iodides and bromides resulting from the use of 1,3‐propanediol allowed an efficient multi‐component approach toward the synthesis of (E)‐stilbenes. Furthermore, this heterogeneous catalyst was found to be extremely robust despite the use of aerobic conditions and was successfully re‐used over several cycles.
Iridium‐Catalyzed Highly Enantioselective Hydrogenation of Exocyclic α,β‐Unsaturated Carbonyl Compounds
Authors: Tian Fengtao , Yao Dongmei , Liu Yuanyuan , Xie Fang , Zhang Wanbin
Published: August 2010

By using the iridium complex of a phosphine‐oxazoline ligand with an axis‐unfixed biphenyl backbone, a highly enantioselective hydrogenation of the CC bond of exocyclic α,β‐unsaturated carbonyl compounds to afford α‐chiral cyclic ketones, lactones and lactams was developed.
Enantioselective Synthesis of Spirocyclic Oxindole‐β‐lactones via N‐Heterocyclic Carbene‐Catalyzed Cycloaddition of Ketenes and Isatins
Authors: Wang Xiao‐Na , Zhang Yan‐Yong , Ye Song
Published: August 2010

Chiral N‐heterocyclic carbenes were found to be efficient catalysts for the formal [2+2] cycloaddition reaction of disubstituted ketenes and isatins to give the corresponding spirocyclic oxindole‐β‐lactones in good yields with good diastereoselectivities and excellent enantioselectivities. Ring opening with Grignard reagents or decarboxylation of the oxindole spirocyclic‐β‐lactone gave the corresponding 3‐hydroxy‐ or 3‐alkylenyloxindoles in good yields.
Palladium‐Catalyzed Transformation of Renewable Oils into Diesel Components
Authors: Han Junxing , Sun Hui , Duan Jinzhao , Ding Yuqi , Lou Hui , Zheng Xiaoming
Published: August 2010

A size‐controlled palladium nanoparticle catalyst prepared by adsorption of colloidal palladium nanoparticles on barium sulfate is efficient and highly selective in transforming vegetable oils into diesel‐like fuel. Preliminary kinetic investigations using model compounds indicated that decarboxylation of aliphatic esters on palladium in a hydrogen‐rich atmosphere showed a zero‐order rate. Hydrogen temperature‐programmed desorption measurements revealed that the high‐temperature desorption of hydrogen species might be the rate‐determining step.
Mixed Isobutylphobane/N‐Heterocyclic Carbene Ruthenium‐ Indenylidene Complexes: Synthesis and Catalytic Evaluation in Olefin Metathesis Reactions
Authors: Sauvage Xavier , Zaragoza Guillermo , Demonceau Albert , Delaude Lionel
Published: August 2010

Two new second generation ruthenium(II) dichloride‐indenylidene complexes [RuCl2(9‐isobutylphosphabicyclo[3.3.1]nonane)(NHC)(3‐phenyl‐1‐indenylidene)], where NHC=1,3‐bis(2,4,6‐trimethylphenyl)imidazolin‐2‐ylidene (SIMes) or its unsaturated imidazol‐2‐ylidene analogue (IMes), were isolated in high yields upon heating a tetrahydrofuran (THF) solution of the diphosphane complex [RuCl2(isobutylphobane)2(3‐phenyl‐1‐indenylidene)] with a two‐fold excess of the corresponding imidazol(in)ium‐2‐carboxylate zwitterions. Both products were characterized by 1H, 13C, and 31P NMR spectroscopy, and the molecular structure of [RuCl2(isobutylphobane)(SIMes)(3‐phenyl‐1‐indenylidene)] was determined by X‐ray diffraction analysis. A close inspection of the packing structure revealed the presence of different types of intra‐ and intermolecular interactions that enhanced the global stability of the crystals, while low temperature NMR experiments showed the existence of two distinct rotational isomers due to the unsymmetrical nature of the phobane ligand. The catalytic activity of both compounds was assessed in olefin metathesis using benchmark ring‐opening metathesis polymerization, ring‐closing metathesis (RCM), and cross‐metathesis reactions, and compared with those of related first and second generation ruthenium‐benzylidene and indenylidene catalyst precursors. Kinetic studies confirmed the high thermal stability of the mixed isobutylphobane/N‐heterocyclic carbene complexes, which suffered from a slow initiation efficiency compared to other catalytic systems based on the tricyclohexylphosphane ligand. However, the remarkable robustness of [RuCl2(isobutylphobane)(SIMes)(3‐phenyl‐1‐indenylidene)] was beneficial for performing the RCM of diethyl 2,2‐bis(2‐methylallyl)malonate. Monitoring the formation of the ruthenium‐methylidene active species [RuCl2(isobutylphobane)(SIMes)(CH2)] derived from this precursor further demonstrated its ability to sustain long reaction times and high temperatures required to carry out the RCM of tetrasubstituted olefins.
One‐Step Surface Decoration of Poly(propyleneimines) (PPIs) with the Glyceryl Moiety: New Way for Recycling Homogeneous Dendrimer‐Based Catalysts
Authors: Balieu Sébastien , El Zein Anji , De Sousa Rodolphe , Jérôme François , Tatibouët Arnaud , Gatard Sylvain , Pouilloux Yannick , Barrault Joël , Rollin Patrick , Bouquillon Sandrine
Published: August 2010

First to fifth generations of poly(propyleneimines) (PPIs) were reacted with glycerol carbonate yielding a new family of glycerol‐decorated PPIs (GD‐PPI). Owing to the presence of glyceryl units surrounding the PPI core, the high generation GD‐PPI‐5 can be successfully immobilized in a glycerol phase, thus offering a convenient route for possible utilization as a recyclable homogeneous catalyst. In this context, we show here that GD‐PPI‐5 can be used as a basic catalyst in the ring opening of epoxides with carboxylic acids in glycerol. The high affinity of GD‐PPI‐5 for the glycerol phase allowed us to (i) selectively extract the reaction products from the glycerol/GD‐PPI‐5 mixture and (ii) recycle the GD‐PPI‐5 catalyst. More generally, this work offers new tools for the convenient recycling of valuable but expensive dendrimers.
Efficient Catalytic Corey–Chaykovsky Reactions Involving Ketone Substrates
Authors: Kavanagh Sarah A. , Piccinini Alessandro , Connon Stephen J.
Published: August 2010

It has been demonstrated for the first time that a sulfide catalyst, utilised at 20 mol% loading, can promote methylene transfer to ketones in the presence of methyl triflate and an organic base. This metal‐free methodology is of broad scope – both aliphatic and aromatic ketones (including trifluoromethyl ketones) can be converted to synthetically useful terminal epoxides in excellent yields at room temperature.
Direct Synthesis of Pyrazolo[5,1‐a]isoindoles via Intramolecular Palladium‐Catalyzed CH Bond Activation
Authors: Choi Young Lok , Lee Hyuk , Kim Bum Tae , Choi Kihang , Heo Jung‐Nyoung
Published: August 2010

An efficient, direct synthesis of pyrazolo[5,1‐a]isoindoles employing a palladium‐catalyzed intramolecular CH bond activation of 1‐(2‐halobenzyl)pyrazoles has been developed. The use of lithium chloride (LiCl) was found to be essential in these reactions, to suppress further CH bond activation at the C‐3 position of pyrazolo[5,1‐a]isoindole, when C‐3 is unsubstituted. This protocol can be applied to the synthesis of a pyrazolo[5,1‐a]isoquinoline possessing a six‐membered central ring system and a fully substituted pyrazolo[5,1‐a]isoindole using sequential intra‐ and intermolecular CH bond activation.
Polystyrene‐Supported Amino Acids as Efficient Catalyst for Chemical Fixation of Carbon Dioxide
Authors: Qi Chaorong , Ye Jinwu , Zeng Wei , Jiang Huanfeng
Published: August 2010

Four new polystyrene‐supported amino acids have been synthesized and applied to the chemical fixation of carbon dioxide for the first time. Two series of experiments with polystyrene‐supported threonine (PS‐Thr) and polystyrene‐supported tyrosine (PS‐Tyr) as catalyst, respectively, were conducted to study the effect of the reaction conditions on the carboxylation of propylene oxide/carbon dioxide. There was no considerable decrease in the yield of propylene carbonate after the polystyrene‐supported amino acids were used five times, indicating that these catalysts are very stable. It was demonstrated that these catalysts were very efficient in the carboxylation of various epoxides and aziridines with carbon dioxide under mild conditions without any solvents. The mechanism for this carboxylation is also discussed.
Asymmetric Organocatalytic Tandem Reaction to Chiral Pyrimidinone Derivatives using Urea as Dinitrogen Source
Authors: He Zhao‐Quan , Zhou Quan , Wu Li , Chen Ying‐Chun
Published: August 2010

A facile method for the asymmetric synthesis of pyrimidinone derivatives was developed via an organocatalytic tandem aza‐Michael addition–hemiaminal formation–dehydroxylation reaction, using N,N′‐dialkyloxyurea as dinitrogen source (up to 97% ee). The transformations of hemiaminal intermediates to pyrimidinones with more complex structures have been also investigated.
Copper‐Catalyzed Asymmetric 1,4‐Hydroboration of Coumarins with Pinacolborane: Asymmetric Synthesis of Dihydrocoumarins
Authors: Kim Hyohyun , Yun Jaesook
Published: August 2010

An efficient asymmetric addition of pinacolborane to 4‐substituted coumarins proceeded with high enantioselectivity in the presence of a copper(I)‐QuinoxP complex as a catalyst to produce the corresponding 1,4‐hydroboration products. Treatment of the intermediates with electrophiles, without isolation, resulted in enantioenriched dihydrocoumarins. The utility of this protocol was demonstrated in the formal synthesis of biologically active molecules.
Laboratory Evolution of Stereoselective Enzymes: A Prolific Source of Catalysts for Asymmetric Reactions
Authors: Reetz Manfred T.
Published: August 2010

Asymmetric catalysis plays a key role in modern synthetic organic chemistry, with synthetic catalysts and enzymes being the two available options. During the latter part of the last century the use of enzymes in organic chemistry and biotechnology experienced a period of rapid growth. However, these biocatalysts have traditionally suffered from several limitations, including in many cases limited substrate scope, poor enantioselectivity, insufficient stability, and sometimes product inhibition. During the last 15 years, the genetic technique of directed evolution has been developed to such an extent that all of these long‐standing problems can be addressed and solved. It is based on repeated cycles of gene mutagenesis, expression, and screening (or selection). This Review focuses on the directed evolution of enantioselective enzymes, which constitutes a fundamentally new approach to asymmetric catalysis. Emphasis is placed on the development of methods to make laboratory evolution faster and more efficient, thus providing chemists and biotechnologists with a rich and non‐ending source of robust and selective catalysts for a variety of useful applications.
Highly Regioselective Synthesis of Bis‐Aziridino[60]fullerene with Sulfilimine
Authors: Okada Mitsunori , Nakahodo Tsukasa , Ishitsuka Midori O. , Nikawa Hidefumi , Tsuchiya Takahiro , Akasaka Takeshi , Fujie Tetsuo , Yoshimura Toshiaki , Slanina Zdenek , Nagase Shigeru
Published: August 2010

In the course of our study of the development of a synthetic methodology for the aziridination of fullerenes, we recently reported the photochemical [2+1] cycloaddition reaction of nitrene onto C60 generated from sulfilimine. Sulfilimines with an electron‐donating group on the N atom are well known to undergo Michael‐type reactions, followed by concomitant elimination of sulfide to afford the corresponding aziridines. In these reactions, sulfilimines act as a nucleophile to the electrophilic olefins. Furthermore, C60 has characteristic features of a low LUMO level and electron‐accepting properties. Therefore, it can be an electrophilic olefin. In this context, sulfilimines might react with C60 to afford the corresponding aziridinofullerenes. We have studied the thermal reaction of (S,S)‐diphenylsulfilimines with C60 and regioselectively synthesized bis‐ and tris‐aziridinated fullerenes. These structures were determined through spectroscopic analyses. Among these, the structure of bis‐aziridinated[60]fullerene, C60(NCH3)2, was determined using single‐crystal X‐ray analysis. Results show that the multi‐aziridination occurs exclusively at the same six‐membered ring of C60 to afford one isomer of the bis‐adduct and tris‐adduct.
Abandoning “the Other”: Statistical Enumeration of Swedish Sami, 1700 to 1945 and Beyond
Authors: Axelsson Per
Published: August 2010

“Das Andere” aufgeben: Zur statistischen Erfassung der schwedischen Sami, 1700 bis 1945 und später. Schweden verfügt über eine weltweit herausragende, umfassende Sammlung statistischer Bevölkerungsdaten. Bereits im 18. Jahrhundert wurden im ganzen Land ethnische Daten in Pfarrregistern erfasst, und im frühen 19. Jahrhundert wurde eine eigene Kategorie für die Sami‐Bevölkerung in die Formulare eingefügt, mit denen Informationen für das Tabellverket (Nationale Bevölkerungsstatistik) gesammelt wurden. Ab 1860 wurden die Sami außerdem in der staatlichen Volkszählung erfasst. Dennoch fehlen Schweden heute (im Gegensatz zu vielen anderen Ländern) eigene statistische Informationen über ethnische Gruppen – nicht nur über die Sami als einzig anerkannter indigener Bevölkerungsgruppe. Der Beitrag untersucht Schwedens Bemühungen vor dem Zweiten Weltkrieg, die Sami‐Bevölkerung zu erfassen sowie die Gründe für die Abkehr von diesem Vorhaben nach dem Krieg. Er analysiert, wie die Sami bestimmt und gezählt wurden, wie die Konstruktion statistischer Kategorien vor sich ging, und wie sich diese Kategorien im Laufe der Zeit veränderten. Ziel des Aufsatzes ist es nicht, die objektive Verlässlichkeit demografischer Quellen zu bewerten. Vielmehr geht es darum, die historischen, sozialen und kulturellen Faktoren zu betrachten, welche die Position der staatlichen Verwaltung in Hinblick auf die statistische Konstruktion einer indigenen Bevölkerung beeinflussten.

Abandoning “the Other”: Statistical Enumeration of Swedish Sami, 1700 to 1945 and Beyond. Sweden has one of the world's most eminent and exhaustive records of statistical information on its population. As early as the eighteenth century, ethnic notations were being made in parish registers throughout the country, and by the early nineteenth century a specific category for the Sami population had been added to the forms used to collect data for the Tabellverket (National Population Statistics). Beginning in 1860, the Sami were also counted in the first official census of the Swedish state. Nonetheless – and in contrast to many other countries – Sweden today lacks separate statistical information not only about its sole recognized indigenous population but also about other ethnic groups. The present paper investigates Sweden's attempts to enumerate its indigenous Sami population prior to World War II and the cessation of ethnic enumeration after the war. How have the Sami been identified and enumerated? How have statistical categories been constructed, and how have they changed over time? The aim of this essay is not to assess the validity of the demographic sources. Instead the paper will explore the historical, social, and cultural factors that have had a bearing on how a dominant administrative structure has dealt with the statistical construct of an indigenous population.
Verhütung als Mittel gegen Bevölkerungswachstum. Expertendiskussion und öffentliche Debatten in Westdeutschland in den 1960er Jahren
Authors: Silies Eva‐Maria
Published: August 2010

Contraception as an Instrument Against Population Growth: Expert Discussions and the Public Sphere in 1960s West Germany.Theoretically, the introduction of the contraceptive pill in the 1960s created new possibilities to control population growth on a global scale. Several of those involved in developing the pill belonged to the transnational population control movement. In the Federal Republic, demographic and medical experts in the 1960s debated the advantages and dangers of the new contraceptive, and they argued about whether it could be of benefit in West Germany and/or in developing countries. The paper examines the contemporary debate about the pill and the role it was awarded in the effort to solve what was considered a global population problem.
The enemy within: An epigenetic role of retrotransposons in cancer initiation
Authors: Wilkins Adam S.
Published: August 2010

This article proposes that cancers can be initiated by retrotransposon (RTN) activation through changes in the transcriptional regulation of nearby genes. I first detail the hypothesis and then discuss the nature of physiological stress(es) in RTN activation; the role of DNA demethylation in the initiation and propagation of new RTN states; the connection between ageing and cancer incidence and the involvement of activated RTNs in the chromosomal aberrations that feature in cancer progression. The hypothesis neither replaces nor invalidates other theories of cancer, in particular the somatic mutation theory, but helps clarify and unify much of the hitherto poorly integrated, complex phenomenology of cancer.
Hepatic transcription response to high‐fat treatment in mice: Microarray comparison of individual vs. pooled RNA samples
Authors: Do Gyeong‐Min , Kwon Eun‐Young , Kim Eunjung , Kim Hyeng‐Soo , Choi Myung‐Sook
Published: August 2010

Microarray analysis is an important tool in studying gene expression profiles in genomic research. Despite many concerns raised, mRNA samples are often pooled in microarray experiments to reduce the cost and complexity of analysis of transcript profiling. This study reports the results of microarray experiments designed to compare effects of pooling RNA samples and its impact on identifying profiles of mRNA transcripts and differentially expressed genes (DEGs) in the liver of C57BL/6J mice fed normal and high‐fat diet. Pearson's correlation coefficient of transcripts between pooled and non‐pooled RNA samples was 0.98 to 1.0. The impact of pooled vs. non‐pooled RNA samples was also compared by number of transcripts or DEGs. Agreement of significant genes between pooled and non‐pooled sets was fairly desirable based on t‐test <0.05 and/or signal intensity ≥2‐fold. Biological process profile and the correlation coefficiency of fold change in the hepatic gene transcripts between pooled and non‐pooled samples were also higher than 0.97. This suggests that pooling hepatic RNA samples can reflect the expression pattern of individual samples, and that properly constructed pools can provide nearly identical measures of transcription response to individual RNA sample.
An introduction to fault diagnosis of permanent magnet synchronous machines in master's degree courses
Authors: Ruiz Jordi‐Roger Riba , Garcia Espinosa Antonio , Romeral Luís , Ortega Juan Antonio
Published: August 2010

Early fault detection and diagnosis of high‐performance electric motors has been an active area of research for the past two decades. This work presents a practical session that facilitates instructing students in this field. To meet this objective, fault diagnostic methods based on the Fourier transform and the wavelet transform are successfully applied by means of processing and examining the frequency content of the stator currents acquired from healthy and faulty permanent magnet synchronous machines (PMSMs). The goal of this practical lab is to introduce Master's degree students to the topic of fault detection by covering both stationary and nonstationary operating conditions of the motor under study. The Technical University of Catalonia (UPC) has successfully incorporated the learning methodology proposed in this paper in a practical session of an electronic engineering course. The effectiveness of the proposed practical lab has been assessed using the results of a satisfaction questionnaire answered by students involved in the course. © 2010 Wiley Periodicals, Inc. Comput Appl Eng Educ 21: 349–359, 2013
Interactivity in education: An experience in the automatic control field
Authors: Guzman J. L. , Dormido S. , Berenguel M.
Published: August 2010

Looking back 30 years ago, the advances in teaching have accompanied the technology evolution. As soon as the technology progressed, new teaching tools began to appear. This work describes one of these technological advances, Interactivity. Several definitions of Interactivity are presented from different points of view. Afterwards, the influence of Interactivity on teaching is discussed presenting the advantages and drawbacks of this information methodology on education. The Automatic Control education field is one of the areas where Interactivity has had a major influence. Hence, this works also describes why Interactivity is very important in engineering education, focusing in the Automatic Control field and presenting some interactive tools as examples of this fact. © 2010 Wiley Periodicals, Inc. Comput Appl Eng Educ 21: 360–371, 2013
Solution Structure of the Leader Sequence of the Patellamide Precursor Peptide, PatE1–34
Authors: Houssen Wael E. , Wright Stephen H. , Kalverda Arnout P. , Thompson Gary S. , Kelly Sharon M. , Jaspars Marcel
Published: August 2010

The solution structure of the leader sequence of the patellamide precursor peptide was analysed by using CD and determined with NOE‐restrained molecular dynamics calculations. This leader sequence is highly conserved in the precursor peptides of some other cyanobactins harbouring heterocycles, and is assumed to play a role in targeting the precursor peptide to the post‐translational machinery. The sequence was observed to form an α‐helix spanning residues 13–28 with a hydrophobic surface on one side of the helix. This hydrophobic surface is proposed to be the site of the initial binding with modifying enzymes.
Membrane‐Surface Anchoring of Charged Diacylglycerol‐Lactones Correlates with Biological Activities
Authors: Raifman Or , Kolusheva Sofiya , El Kazzouli Said , Sigano Dina M. , Kedei Noemi , Lewin Nancy E. , Lopez‐Nicolas Ruben , Ortiz‐Espin Ana , Gomez‐Fernandez Juan C. , Blumberg Peter M. , Marquez Victor E. , Corbalan‐Garcia Senena , Jelinek Raz
Published: August 2010

Synthetic diacylglycerol‐lactones (DAG‐lactones) are effective modulators of critical cellular signaling pathways, downstream of the lipophilic second messenger diacylglycerol, that activate a host of protein kinase C (PKC) isozymes and other nonkinase proteins that share similar C1 membrane‐targeting domains with PKC. A fundamental determinant of the biological activity of these amphiphilic molecules is the nature of their interactions with cellular membranes. This study examines the biological properties of charged DAG‐lactones exhibiting different alkyl groups attached to the heterocyclic nitrogen of an α‐pyridylalkylidene chain, and particularly the relationship between membrane interactions of the substituted DAG‐lactones and their respective biological activities. Our results suggest that bilayer interface localization of the N‐alkyl chain in the R2 position of the DAG‐lactones inhibits translocation of PKC isoenzymes onto the cellular membrane. However, the orientation of a branched alkyl chain at the bilayer surface facilitates PKC binding and translocation. This investigation emphasizes that bilayer localization of the aromatic side residues of positively charged DAG‐lactone derivatives play a central role in determining biological activity, and that this factor contributes to the diversity of biological actions of these synthetic biomimetic ligands.
Highlights of Transition Metal‐Catalyzed Asymmetric Hydrogenation of Imines
Authors: Fleury‐Brégeot Nicolas , de la Fuente Verónica , Castillón Sergio , Claver Carmen
Published: August 2010

This Review deals with the asymmetric hydrogenation and asymmetric transfer hydrogenation of imines and some nitrogen‐containing heteroaromatic compounds to afford amines. Hydrogenation and transfer hydrogenation are covered in separate sections. Particular attention is devoted to the substrates, since this reaction is highly substrate dependent. In this way the general structural trends in imine hydrogenation are presented, highlighting the more challenging substrates. Since hydrogenation of acyclic and cyclic (including heteroaromatic) imines have some different features they are also presented separately. The catalytic systems are classified according to the metal, and focus on the most successful catalytic systems and metal–ligand combinations. The catalytic cycles for these hydrogenation processes are also proposed.
Secondary Phosphane Oxides as Preligands in Rhodium‐Catalyzed Hydroformylation
Authors: Christiansen Andrea , Li Chuanzhao , Garland Marc , Selent Detlef , Ludwig Ralf , Franke Robert , Börner Armin
Published: August 2010

Four aryl‐substituted secondary phosphane oxides (SPOs) were tested as preligands in the rhodium catalyzed hydroformylation of cyclohexene and 1‐octene. Three of them form active hydroformylation catalysts through their phosphinous acid tautomers. n‐Regioselectivities of up to 56 % were achieved in the reaction with the linear olefin. The catalytic system with the electron‐poor SPO showed exceptional behavior. In situ high‐pressure IR spectroscopic investigations accompanied by DFT calculations provide an explanation of the observed inhibition of the catalytic reaction. Furthermore, proof is given that noncoordinated SPOs readily react with product aldehydes at room temperature to form α‐hydroxyphosphinic acids. In contrast Rh‐catalyzed hydrophosphination did not take place.
Acceleration of the Rate of the Heck Reaction through UV‐ and Visible‐Light‐Induced Palladium(II) Reduction
Authors: Fredricks Margaret Anne , Drees Markus , Köhler Klaus
Published: August 2010

Irradiation with light (UV and visible) increases the rate of the Heck reaction using homogeneous (palladium(II) acetate) and heterogeneous (Pd/Al2O3 and Pd/TiO2) catalysts. The rate of the coupling of bromobenzene, chlorobenzene, and 4‐chloroacetophenone with styrene was increased under light irradiation at temperatures between 90 and 160 °C. Detailed investigations showed that light irradiation accelerates the reduction of the PdII precursor, as confirmed by 31P NMR spectroscopy, in which the in situ reduction of [Pd(OAc)2(PPh3)2] to [Pd(PPh3)n] (n=2–4) in the presence of PPh3 took only minutes under visible light irradiation and several hours in the dark. The role of light is, however, complex since it also influences other PdII reduction steps in conjunction with catalyst deactivation (Pd black formation). 31P NMR spectroscopy showed the same active species, anionic palladium halide complexes, in both irradiated and unirradiated reactions. UV/Vis absorption spectroscopy of Pd(OAc)2 and DFT calculations, theoretical UV/Vis spectra, and orbital calculations of [PdI4]2−, [PdBr4]2−, and [PdCl4]2−, showed that ligand‐to‐metal charge transfer (LMCT) is responsible for the accelerated reduction of PdII to Pd0 under light irradiation.
A Mathematical Model for Predicting Release Rate from Multiple Emulsions and Micro/Nanospheres
Authors: Dluska E. , Markowska‐Radomska A.
Published: August 2010

This paper presents mass transfer models of the release process from hierarchical dispersed systems such as multiple emulsions and micro/nanospheres. The models were validated by experimental data of an active component released from multiple emulsions and microspheres obtained via multiple emulsion thermal cross‐linking. The simulations of release profiles confirmed the importance of the internal structure of multiple emulsions/microspheres, as well as the intensity of external mixing in the modeling of the controlled release process. The models presented allowed the mass released to be determined within satisfactory agreement with experimental data after optimization of parameters that describe internal emulsion/microsphere structure. The model proposed for describing the release process from microspheres can simulate release profiles that exhibit phasic behavior (primary/lag and continuous release). The model simulations were extended to nanoscale particles with satisfactory results.
Expanded Pyridiniums: Bis‐cyclization of Branched Pyridiniums into Their Fused Polycyclic and Positively Charged Derivatives—Assessing the Impact of Pericondensation on Structural, Electrochemical, Electronic, and Photophysical Features
Authors: Fortage Jérôme , Tuyèras Fabien , Ochsenbein Philippe , Puntoriero Fausto , Nastasi Francesco , Campagna Sebastiano , Griveau Sophie , Bedioui Fethi , Ciofini Ilaria , Lainé Philippe P.
Published: August 2010

This study evaluates the impact of the extension of the π‐conjugated system of pyridiniums on their various properties. The molecular scaffold of aryl‐substituted expanded pyridiniums (referred to as branched species) can be photochemically bis‐cyclized into the corresponding fused polycyclic derivatives (referred to as pericondensed species). The representative 1,2,4,6‐tetraphenylpyridinium (1H) and 1,2,3,5,6‐pentaphenyl‐4‐(p‐tolyl)pyridinium (2Me) tetra‐ and hexa‐branched pyridiniums are herein compared with their corresponding pericondensed derivatives, the fully fused 9‐phenylbenzo[1,2]quinolizino[3,4,5,6‐def]phenanthridinium (1Hf) and the hitherto unknown hemifused 9‐methyl‐1,2,3‐triphenylbenzo[h]phenanthro[9,10,1‐def]isoquinolinium (2Mef). Combined solid‐state X‐ray crystallography and solution NMR experiments showed that stacking interactions are barely efficient when the pericondensed pyridiniums are not appropriately substituted. The electrochemical study revealed that the first reduction process of all the expanded pyridiniums occurs at around −1 V vs. SCE, which indicates that the lowest unoccupied molecular orbital (LUMO) remains essentially localized on the pyridinium core regardless of pericondensation. In contrast, the electronic and photophysical properties are significantly affected on going from branched to pericondensed pyridiniums. Typically, the number of absorption bands increases with extended activity towards the visible region (down to ca. 450 nm in MeCN), whereas emission quantum yields are increased by three orders of magnitude (at ca. 0.25 on average). A relationship is established between the observed differential impact of the pericondensation and the importance of the localized LUMO on the properties considered: predominant for the first reduction process compared with secondary for the optical and photophysical properties.
Photolysis and Thermolysis of Platinum(IV) 2,2′‐Bipyridine Complexes Lead to Identical Platinum(II)–DNA Adducts
Authors: Loup Christophe , Tesouro Vallina Ana , Coppel Yannick , Létinois Ulla , Nakabayashi Yasuo , Meunier Bernard , Lippert Bernhard , Pratviel Geneviève
Published: August 2010

Two PtIV and two PtII complexes containing a 2,2′‐bipyridine ligand were treated with a short DNA oligonucleotide under light irradiation at 37 °C or in the dark at 37 and 50 °C. Photolysis and thermolysis of the PtIV complexes led to spontaneous reduction of the PtIV to the corresponding PtII complexes and to binding of PtII 2,2′‐bipyridine complexes to N7 of guanine. When the reduction product was [Pt(bpy)Cl2], formation of bis‐oligonucleotide adducts was observed, whereas [Pt(bpy)(MeNH2)Cl]+ gave monoadducts, with chloride ligands substituted in both cases. Neither in the dark nor under light irradiation was the reductive elimination process of these PtIV complexes accompanied by oxidative DNA damage. This work raises the question of the stability of photoactivatable PtIV complexes toward moderate heating conditions.
Trifluoromethyl‐Substituted Conjugated Oligoelectrolytes
Authors: Ren Yan , Bazan Guillermo C.
Published: August 2010

Conjugated oligoelectrolytes (COEs) are being introduced into a variety of optical and electronic technologies, yet the dependence of their properties as a function of molecular structure remains poorly understood. In response, we designed, synthesized, and examined a new tetracationic COE, namely, 1,4‐bis{9′,9′‐bis[6′′‐(N,N,N‐trimethylammonium)hexyl]‐2′‐fluorenyl}‐2,5‐bis(trifluoromethyl)benzene tetrabromide (FPF‐F6), which contains bulky electron‐withdrawing trifluoromethyl groups, and compared its properties with the unsubstituted counterpart 1,4‐bis{9′,9′‐bis[6′′‐(N,N,N‐trimethylammonium)hexyl]‐2′‐fluorenyl}benzene tetrabromide (FPF). The ground‐state geometry of FPF‐F6 is primarily twisted with little electronic communication between the aromatic units, as confirmed by single‐crystal X‐ray diffraction studies of the neutral precursor. However, absorption and photoluminescence spectroscopies reveal that the excited state of FPF‐F6 displays strong intramolecular charge‐transfer characteristics. Solution AFM in aqueous media shows that introduction of trifluoromethyl groups changes the size and aspect ratio of supramolecular aggregates that are brought together as a result of hydrophobic interactions. Furthermore, addition of ssDNA to FPF‐F6 leads to interoligoelectrolyte complexes wherein the backbone is more planar; the environment the chromophore experiences under these conditions is also considerably less polar. These findings provide considerable insight into the complex photophysics of electronically conjugated materials in aqueous media.
An Atomic‐Level Strategy for Unraveling Gold Nanocatalysis from the Perspective of Aun(SR)m Nanoclusters
Authors: Zhu Yan , Qian Huifeng , Jin Rongchao
Published: August 2010

An atomic‐level strategy is devised to gain insight into the origin of nanogold catalysis by using atomically monodisperse Aun(SR)m nanoclusters as well‐defined catalysts for styrene oxidation. The Aun(SR)m nanoclusters are emerging as a new class of gold nanocatalyst to overcome the polydispersity of conventional nanoparticle catalysts. The unique atom‐packing structure and electronic properties of Aun(SR)m nanoclusters (<2 nm) are rationalized to be responsible for their extraordinary catalytic activity observed in styrene oxidation. An interesting finding is that quantum size effects of Aun(SR)m nanoclusters, rather than the higher specific surface area, play a major role in gold‐catalyzed selective oxidation of styrene. For example, Au25(SR)18 nanoclusters (≈1 nm) are found to be particularly efficient in activating O2, which is a key step in styrene oxidation, and hence, the ultrasmall Au25 catalyst exhibits higher activity than do larger sizes. This atomic‐level strategy has allowed us to obtain an important insight into some fundamental aspects of nanogold catalysis in styrene oxidation. The ultrasmall yet robust Aun(SR)m nanoclusters are particularly promising for studying the mechanistic aspects of nanogold catalysis and for future design of better catalysts with high activity and selectivity for certain chemical processes.
[Pd(Cl)2{P(NC5H10)(C6H11)2}2]—A Highly Effective and Extremely Versatile Palladium‐Based Negishi Catalyst that Efficiently and Reliably Operates at Low Catalyst Loadings
Authors: Bolliger Jeanne L. , Frech Christian M.
Published: August 2010

[Pd(Cl)2{P(NC5H10)(C6H11)2}2] (1) has been prepared in quantitative yield by reacting commercially available [Pd(cod)(Cl)2] (cod=cyclooctadiene) with readily prepared 1‐(dicyclohexylphosphanyl)piperidine in toluene under N2 within a few minutes at room temperature. Complex 1 has proved to be an excellent Negishi catalyst, capable of quantitatively coupling a wide variety of electronically activated, non‐activated, deactivated, sterically hindered, heterocyclic, and functionalized aryl bromides with various (also heterocyclic) arylzinc reagents, typically within a few minutes at 100 °C in the presence of just 0.01 mol % of catalyst. Aryl bromides containing nitro, nitrile, ether, ester, hydroxy, carbonyl, and carboxyl groups, as well as acetals, lactones, amides, anilines, alkenes, carboxylic acids, acetic acids, and pyridines and pyrimidines, have been successfully used as coupling partners. Furthermore, electronic and steric variations are tolerated in both reaction partners. Experimental observations strongly indicate that a molecular mechanism is operative.
3,4‐Dithiaphosphole and 3,3′,4,4′‐Tetrathia‐1,1′‐Biphosphole π‐Conjugated Systems: S Makes the Impact
Authors: Fadhel Omrane , Benkö Zoltán , Gras Michael , Deborde Valérie , Joly Damien , Lescop Christophe , Nyulászi László , Hissler Muriel , Réau Régis
Published: August 2010

Conjugated systems based on phospholes and 1,1′‐biphospholes bearing 3,4‐ethylenedithia bridges have been prepared using the Fagan–Nugent route. The mechanism of this organometallic route leading to intermediate zirconacyclopentadienes has been investigated by using theoretical calculations. This study revealed that the oxidative coupling leading to zirconacyclopentadienes is favored over oxidative addition within the SC≡C bond both thermodynamically and kinetically. The impact of the presence of the S atoms on the optical and electrochemical behavior of the phospholes and 1,1′‐biphospholes has been systematically evaluated both experimentally and theoretically. A comparison with their “all‐carbon” analogues is provided. Of particular interest, this comparative study revealed that the introduction of S atoms has an impact on the electronic properties of phosphole‐based conjugated systems. A decrease of the HOMO–LUMO separation and a stabilization of the LUMO level were observed. These general trends are also observed with 1,1′‐biphospholes exhibiting σ–π conjugation. The P atom of the 3,4‐ethylenedithiaphospholes can be selectively oxidized by S8 or O2. These P modifications result in a lowering of the HOMO–LUMO separation as well as an increase of the reduction and oxidation potentials. The S atoms of the 3,4‐ethylenedithia bridge of the 2,5‐phosphole have been oxidized using m‐chloroperoxybenzoic acid. The resulting 3,4‐ethylenesulfoxide oxophosphole was characterized by an X‐ray diffraction study. Experimental and theoretical studies show that this novel chemical manipulation results in an increase of the HOMO–LUMO separation and an important decrease of the LUMO level. The electropolymerization of 2‐thienyl‐capped 3,4‐ethylenedithiathioxophosphole and 1,1′‐biphosphole is reported. The impact of the S substituents on the polymer properties is discussed.
ChemInform Abstract: Neutron Diffraction Studies of Quadrupled Perovskites Sm2Ba2Cu2Ti1. 5Sn0.5O11, Sm2Ba2Cu2Ti1.55Sn0.2Sc0.25O11, and Gd2Ba2Cu2Ti2O11 and Calcium Doping of Gd2Ba2Cu2Ti2O11.
Authors: GORMEZANO A. , WELLER M. T.
Published: August 2010

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform Abstract: Plasma‐Enhanced Chemical Vapor Deposited Phosphorus Sulfide Films. Characterization by Raman and Solid‐State NMR Spectroscopies and Comparison to Melt‐Quenched Glassy Materials.
Authors: SHIBAO R. K. , XIA Y. , SRDANOV V. I. , ECKERT H.
Published: August 2010

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.