bluuebunny/crossref_metadata_2025 huggingface dataset:
Chemoselectivity as a Delineator of Cuprate Structure in Catalytic 1,4‐Addition of Diorganozinc Reagents to Michael Acceptors
Authors: Welker Matthias , Woodward Simon , Veiros Luis F. , Calhorda Maria José
Published: April 2010

Reaction of the cyclic thioacetal (RS)2CHCHO [R=1/2×(CH2)3] with HCCCOMe, followed by treatment with TsCl/DABCO (Ts=tosyl, DABCO=1,4‐diazabicyclo[2.2.2]octane) affords the mono‐protected 1,4‐benzoquinone dithioacetal. The reactivity of this SR‐protected 1,4‐benzoquinone has been compared with the behavior of the analogous OR‐protected acetal in copper‐catalyzed additions of ZnMe2 by using chiral phosphoramidite ligands. The activation energy for 1,4‐methylation of the latter OR‐acetals with ZnMe2 (>95 % ee) has been determined for two CuX2 pre‐catalysts (X=OAc, 12.2 kcal mol−1; X=OTf, 6.7 kcal mol−1; Tf=triflate). The dithioacetal SR aromatizes in the presence of CuI/ZnMe2 giving 1,4‐HOC6H4S(CH2)3SMe through CS bond formation. The disparate behavior of these two very closely related substrates is in accordance with the formation of closely related cuprate intermediates that were optimized by DFT calculations, supporting the synthetic and kinetic studies and thus defining the mechanisms of both pathways.
Complex–Surfactant‐Assisted Hydrothermal Synthesis and Properties of Hierarchical Worm‐Like Cobalt Sulfide Microtubes Assembled by Hexagonal Nanoplates
Authors: Liu Bo , Wei Shuang , Xing Yan , Liu Dan , Shi Zhan , Liu Xianchun , Sun Xiujuan , Hou Suying , Su Zhongmin
Published: April 2010

The preparation of exquisite hierarchical worm‐like Co1−xS (x=0.75) microtubes by a one‐pot complex–surfactant‐assisted hydrothermal method is successfully achieved for the first time. The hierarchical structures of the microtube wall are assembled from numerous interleaving hexagonal nanoplates. X‐ray diffraction, X‐ray photoelectron spectroscopy, scanning electron microscopy, transmission electron microscopy, and high‐resolution transmission electron microscopy were used to characterize the samples. The experimental results indicate that the “soft template” surfactant cetyltrimethylammonium bromide and the chelating ethylenediamine both play important roles for the formation of hierarchical Co1−xS microtubes. A possible formation mechanism for the growth processes is proposed. Additionally, the electrochemical and magnetic properties of Co1−xS microtubes were systematically studied.
Reaction of 1,1′‐Divinyl Ferrocene with One‐Electron Oxidants: Entry into Functionalised [4]Ferrocenophanes and Observation of an Isotope‐Dependent Chemoselectivity Effect
Authors: Gleixner Renate M. , Joly Kévin M. , Tremayne MaryJane , Kariuki Benson M. , Male Louise , Coe Diane M. , Cox Liam R.
Published: April 2010

1,1′‐Divinyl ferrocene (2) reacts with K3[Fe(CN)6] under basic biphasic conditions to give a [4]ferrocenophane (4) in good yield. Incorporating deuterium labels into the internal positions of the vinyl groups of 2 affects the chemoselectivity of the reaction; thus under identical reaction conditions, [D2]‐2 reacts to provide a diol‐functionalised [4]ferrocenophane, [D2]‐D/L‐6 in addition to the expected keto‐alcohol, [D1]‐4. Variants on this one‐electron oxidative cyclisation methodology can be used to give other [4]ferrocenophanes; thus, the reaction of 2 with CuCl2 in MeOH or iPrOH leads to dialkoxy [4]ferrocenophanes 19 and 20, respectively, whereas the reaction of 2 with benzyl carbamate in the presence of tBuOCl gives a bis(carbamate)[4]ferrocenophane, 21. Mechanisms to account for the formation of the products, the stereoselectivity, and the unusual isotope‐dependent chemoselectivity in the reaction of 2 and [D2]‐2 with K3[Fe(CN)6] are proposed.
Polymer Covalent Functionalization of Carbon Nanohorns Using Bulk Free Radical Polymerization
Authors: Mountrichas Grigoris , Pispas Stergios , Ichihasi Toshinari , Yudasaka Masako , Iijima Sumio , Tagmatarchis Nikos
Published: April 2010

Herein, we report on a facile approach for the covalent functionalization of carbon nanohorns, using in situ bulk free radical polymerization of methacrylic acid. The obtained material is soluble in aqueous media, facilitating its processability and has been fully characterized by means of complementary spectroscopic techniques, electron microscopy, thermogravimetric analysis, and light scattering. Simultaneously, the material has been used as a template for the synthesis of gold nanoparticles on the surface of the polymer‐decorated carbon nanohorns.
Photochromic Organometallics with a Dithienylethene (DTE) Bridge, [YCCDTECCY] (Y={MCp*(dppe)}): Photoswitchable Molecular Wire (M=Fe) versus Dual Photo‐ and Electrochromism (M=Ru)
Authors: Tanaka Yuya , Ishisaka Takuya , Inagaki Akiko , Koike Takashi , Lapinte Claude , Akita Munetaka
Published: April 2010

Dinuclear acetylide‐type complexes bridged by a photochromic dithienylethene unit (DTE), [YCCDTECCY] 1 (Y={MCp*(dppe)}; Cp*=pentamethylcyclopentadienyl, M=Fe (1Fe), Ru (1Ru)), have been prepared, and their wirelike and switching behavior, as well as their oxidation chemistry has been investigated. The DTE complexes 1 exhibit photochromic behavior in a manner similar to organic DTE derivatives; UV irradiation causes ring closure of the open isomer 1O to form the closed isomer 1C and visible‐light irradiation of the resultant 1C causes reverse ring opening to regenerate 1O. But the performance is dependent on the metals. With respect to the interconversion rates and the 1C content at the photostationary state under UV irradiation, the ruthenium complex 1Ru is superior to the iron analogue 1Fe. The wirelike performance is associated with the photochromic processes, and the efficient switching performance has been verified for 1Fe as characterized by the Vab values [Vab is the electronic coupling derived from intervalence charge‐transfer (IVCT) bands: Vab(1FeC; ON)=0.047 eV versus Vab(1FeO; OFF)=0 eV], and are also supported by the large switching factor (SF=KC(C; ON)/KC(O; OFF)=39; KC=comproportionation constant). SF for 1Ru is determined to be 4.2. The remarkable switching behavior arises from the different π‐conjugated systems in the two isomeric forms, that is, cross‐conjugated (1O) and fully conjugated π‐systems (1C). It was also found that, in contrast to the reversible redox behavior of the iron complex 1Fe, the ruthenium complex 1RuO undergoes oxidative ring closure to form the dicationic species of the closed isomer 1RuC2+ and, thus, the ruthenium system 1Ru shows dual photo‐ and electrochromism. The distinct oxidation behavior of 1Fe and 1Ru can be ascribed to the spin distribution on the diradical intermediates 1FeO2+ and 1RuO2+, as supported by DFT calculations.
Sterically Less‐Hindered Half‐Titanocene(IV) Phenoxides: Ancillary‐Ligand Effect on Mono‐, Bis‐, and Tris(2‐Alkyl‐/arylphenoxy) Titanium(IV) Chloride Complexes
Authors: Kim Tae‐Jin , Kim Sung‐Kwan , Kim Beom‐Jun , Son Ho‐Jin , Hahn Jong Sok , Cheong Minserk , Mitoraj Mariusz , Srebro Monika , Piękoś Łukasz , Michalak Artur , Kang Sang Ook
Published: April 2010

A series of mono‐, bis‐, and tris(phenoxy)–titanium(IV) chlorides of the type [Cp*Ti(2‐RPhO)nCl3−n] (n=1–3; Cp*=pentamethylcyclopentadienyl) was prepared, in which R=Me, iPr, tBu, and Ph. The formation of each mono‐, bis‐, and tris(2‐alkyl‐/arylphenoxy) series was authenticated by structural studies on representative examples of the phenyl series including [Cp*Ti(2‐PhPhO)Cl2] (1 PhCl2), [Cp*Ti(2‐PhPhO)2Cl] (2 PhCl), and [Cp*Ti(2‐PhPhO)3] (3 Ph). The metal‐coordination geometry of each compound is best described as pseudotetrahedral with the Cp* ring and the 2‐PhPhO and chloride ligands occupying three leg positions in a piano‐stool geometry. The mean TiO distances, observed with an increasing number of 2‐PhPhO groups, are 1.784(3), 1.802(4), and 1.799(3) Å for 1 PhCl2, 2 PhCl, and 3 Ph, respectively. All four alkyl/aryl series with Me, iPr, tBu, and Ph substituents were tested for ethylene homopolymerization after activation with Ph3C+[B(C6F5)4]− and modified methyaluminoxane (7% aluminum in isopar E; mMAO‐7) at 140 °C. The phenyl series showed much higher catalytic activity, which ranged from 43.2 and 65.4 kg (mmol of Ti⋅h)−1, than the Me, iPr, and tBu series (19.2 and 36.6 kg (mmol of Ti⋅h)−1). Among the phenyl series, the bis(phenoxide) complex of 2 PhCl showed the highest activity of 65.4 kg (mmol of Ti⋅h)−1. Therefore, the catalyst precursors of the phenyl series were examined by treating them with a variety of alkylating reagents, such as trimethylaluminum (TMA), triisobutylaluminum (TIBA), and methylaluminoxane (MAO). In all cases, 2 PhCl produced the most catalytically active alkylated species, [Cp*Ti(2‐PhPhO)MeCl]. This enhancement was further supported by DFT calculations based on the simplified model with TMA.
Photochemistry in Photonic Crystal Fiber Nanoreactors
Authors: Chen Jocelyn S. Y. , Euser Tijmen G. , Farrer Nicola J. , Sadler Peter J. , Scharrer Michael , Russell Philip St. J.
Published: April 2010

We report the use of a liquid‐filled hollow‐core photonic crystal fiber (PCF) as a highly controlled photochemical reactor. Hollow‐core PCFs have several major advantages over conventional sample cells: the sample volume per optical path length is very small (2.8 nL cm−1 in the fiber used), long optical path lengths are possible as a result of very low intrinsic waveguide loss, and furthermore the light travels in a diffractionless single mode with a constant transverse intensity profile. As a proof of principle, the (very low) quantum yield of the photochemical conversion of vitamin B12, cyanocobalamin (CNCbl) to hydroxocobalamin ([H2OCbl]+) in aqueous solution was measured for several pH values from 2.5 to 7.5. The dynamics of the actively induced reaction were monitored in real‐time by broadband absorption spectroscopy. The PCF nanoreactor required ten thousand times less sample volume compared to conventional techniques. Furthermore, the enhanced sensitivity and optical pump intensity implied that even systems with very small quantum yields can be measured very quickly—in our experiments one thousand times faster than in a conventional cuvette.
Theoretical study on the asymmetric Michael addition of cyclohexanone with trans‐β‐nitrostyrene catalyzed by a pyrrolidine‐type chiral ionic liquid
Authors: Sun Hui , Zhang Dongju , Zhang Changqiao , Liu Chengbu
Published: April 2010

The Michael addition of cyclohexanone with trans‐β‐nitrostyrene catalyzed by a chiral ionic liquid (CIL) pyrrolidine‐imidazolium bromide, which represents a prototype of CIL‐promoted asymmetric syntheses, has been investigated by performing density functional theory calculations. We show the details of the mechanism and energetics, the influence of the acid additive on the reactivity, and the functional role of the CIL in the asymmetric addition. It is found that the reaction proceeds via two stages, i.e., the initial enamine formation, where the imine complex is first created and then isomerizes into the enamine intermediate, and the subsequent Michael addition involving a three‐step mechanism. The calculations show that the presence of the acid additive changes the imine formation mechanism and lowers the reaction barrier, as well as, more importantly, makes the reaction become highly thermodynamically favored. It is also suggested that both the anion and cation of the CIL synergically facilitate the reaction, which act as the proton acceptor in the imine‐enamine tautomerism and the stabilizer of the negative charge in the CC bond formation process, respectively. The present theoretical study rationalizes the early experimental findings well and provides aid to some extent for the rational design of efficient CIL catalysts. Chirality 2010. © 2010 Wiley‐Liss, Inc.
Concept Mapping – Learning Strategy is Something You Must Learn
Authors: Sumfleth Elke , Neuroth Jasmin , Leutner Detlev
Published: April 2010

Concept Mapping Verfahren werden nicht nur zur Wissensdiagnose eingesetzt, sondern zunehmend auch als Lernstrategien im Chemieunterricht. Es handelt sich hierbei um eine anspruchsvolle Strategie, die noch nicht zum Standardrepertoire gehört und deshalb für Lernende eine hohe kognitive Anforderung darstellt. Um die kognitive Belastung beim Inhaltslernen zu reduzieren, ist es sinnvoll, die Strategie zunächst zu üben. Zu diesem Zweck ist ein Trainingsprogramm zum Concept Mapping entwickelt und seine Wirksamkeit überprüft worden.
The Phlogiston Theory from Georg Ernst Stahl – Catalyst in the Development of Modern Scientific Chemistry
Authors: Remane Horst
Published: April 2010

Der deutsche Arzt und Naturforscher Georg Ernst Stahl (1659 – 1734) formulierte 1697 seine Phlogistontheorie. Damit hat er erstmals in der Entwicklung der Chemie eine chemische Umwandlung, den Redox‐Prozess, theoretisch erfasst und erklärt. Er konnte weiter den Zusammenhang und die Bedingtheit von Oxidation und Reduktion aufzeigen. Obwohl die Phlogistontheorie falsch war, sie erklärte den Redox‐Prozess genau umgekehrt, wurde sie für ca. 90 Jahre als die dominierende chemische Theorie zu einem Katalysator für die Herausbildung der modernen wissenschaftlichen Chemie.
Clinical outcome of children and adults with localized Ewing sarcoma
Authors: Gupta Abha A. , Pappo Alberto , Saunders Natasha , Hopyan Sevan , Ferguson Peter , Wunder Jay , O'Sullivan Brian , Catton Charles , Greenberg Mark , Blackstein Martin
Published: April 2010

BACKGROUND:

As Ewing sarcoma (EWS) can affect children and adults, these patients can be treated at either a pediatric or an adult institution. This study investigated whether differences in therapeutic strategy undertaken in pediatric and adult specialty sarcoma centers correlated with clinical outcome.

METHODS:

Data from patients with localized EWS treated between 1990 and 2005 at tertiary care pediatric and adult institutions were reviewed.

RESULTS:

Fifty‐three patients (24 adult and 29 pediatric) were treated. Pediatric patients received a median of 16 cycles of chemotherapy comprised of doxorubicin, vincristine, cyclophosphamide, ifosfamide, and etoposide. Adult patients received a median of 10 cycles of treatment, and a significantly lower total cumulative dose of ifosfamide and cyclophosphamide (P < .0001). There was no difference noted with regard to the total dose of doxorubicin, or in the type of local therapy offered (surgery or radiotherapy, vs both). However, local therapy occurred earlier in pediatric patients compared with adults (3.7 months vs 7.4 months; P = .0003). The 3‐year event‐free survival (EFS) rate in pediatric and adult patients was 70% ± 9% and 43% ± 13% (P = 0.1), respectively. The 3‐year overall survival rate was 81% ± 7.7% and 59% ± 12% (P = .02) for pediatric and adult patients, respectively. Factors found to be significantly associated with EFS on univariate analysis included pelvic site, cyclophosphamide dose, and time to local therapy. On multivariate analysis, only pelvic disease (hazard ratio [HR] 4.26; P = .018) and time to local therapy (HR, 1.19; P = .002) were found to be significant.

CONCLUSIONS:

Adults with localized EWS have an inferior outcome compared with pediatric patients. This difference may be related to lower doses of alkylating agents and the timing of local therapy. Cancer 2010. © 2010 American Cancer Society.
Synthetic Biology of Protein Folding
Authors: Moroder Luis , Budisa Nediljko
Published: April 2010

In protein evolution amino acid replacements occur more frequently between similar than dissimilar amino acids. Accordingly, the mutations obey a simple ‘similar replaces similar’ rule as disruption of the resulting protein structure is minimized by the modest alterations in the amino acid side chains. At laboratory level such non‐destructive modifications have to be incorporated in a controlled manner by integrating the chemical diversity achieved in synthetic chemistry into proteins. For this purpose the most straightforward route is generation of the synthetic proteins by the cellular translational apparatus via insertion of isosteric synthetic amino acid analogs during gene expression. This leads to target proteins with chemical diversity not found in nature. Such genetic code engineering does not require any DNA mutagenesis step as it produces extensive sequence variations at the level of protein translation. It is generally achieved either by expansion of the existing amino acid repertoire or by introduction of novel coding units. Here we highlight the concept of using isosteric noncanonical amino acid analogs for in vivo protein synthesis as a useful tool to dissect, study and manipulate protein folding and conformational stability with two examples, the prion protein and green fluorescent protein. In the first example, we show how alternative translation of the single gene sequence by different synthetic amino acids enables the protein to fold into stable, but differing conformations. In particular, replacement of methionine by the isosteric analogs norleucine/metoxinine provide a chemical model to dissect the role of hydrophilicity/hydrophobicity in the α→β conversion of the prion protein structure. In the second example, proline residues in green fluorescent protein are replaced with (4S)‐fluoroproline which improves folding and overall stability of the protein. Indeed, fluorination of the protein matrix creates a network of favorable local interactions absent in the parent (i.e. natural) protein. The generation of these novel properties is the first demonstration of a structural preogranisation principle in one complex globular protein molecule.
ESC: Estimation of selecting core for reducing multicast delay variation under delay constraints
Authors: Kim Moonseong , Mutka Matt W. , Kim Hye‐Young
Published: April 2010

With the spread of multimedia group applications, the construction of multicast trees satisfying the Quality of Service (QoS) requirements becomes a problem of prime importance. A principal factor of these real‐time applications is to optimize the delay‐ and delay variation‐bounded multicast tree (DVBMT) problem. This problem is to satisfy the minimum delay variation and the end‐to‐end delay within an upper bound. The DVBMT problem is known as an NP‐complete problem. The representative algorithms are the DVMA, the DDVCA, and the ECS algorithm. In this paper, we show that the proposed ESC algorithm outperforms the DDVCA and the ECS algorithm. The efficiency of our algorithm is verified through performance evaluation and the enhancement is up to about 19.6% in terms of normalized surcharge for multicast delay variation. The time complexity of our algorithm isO(mn2), which is comparable to the well‐known DDVCA. Copyright © 2010 John Wiley & Sons, Ltd.
Aktuelles aus dem Bereich Metallbau
Authors: Kathage Karsten
Published: April 2010

Der Beitrag enthält aktuelle Informationen zu neuen Bereichen für europäische technische Zulassungen, zu Stahlregalen sowie zur Normenreihe EN 1090.
Caenorhabditis elegans as a model for stem cell biology
Authors: Joshi Pradeep M. , Riddle Misty R. , Djabrayan Nareg J.V. , Rothman Joel H.
Published: April 2010

We review the application of Caenorhabditis elegans as a model system to understand key aspects of stem cell biology. The only bona fide stem cells in C. elegans are those of the germline, which serves as a valuable paradigm for understanding how stem‐cell niches influence maintenance and differentiation of stem cells and how somatic differentiation is repressed during germline development. Somatic cells that share stem cell–like characteristics also provide insights into principles in stem‐cell biology. The epidermal seam cell lineages lend clues to conserved mechanisms of self‐renewal and expansion divisions. Principles of developmental plasticity and reprogramming relevant to stem‐cell biology arise from studies of natural transdifferentiation and from analysis of early embryonic progenitors, which undergo a dramatic transition from a pluripotent, reprogrammable condition to a state of committed differentiation. The relevance of these developmental processes to our understanding of stem‐cell biology in other organisms is discussed. Developmental Dynamics 239:1539–1554, 2010. © 2010 Wiley‐Liss, Inc.
Gfi1‐Cre knock‐in mouse line: A tool for inner ear hair cell‐specific gene deletion
Authors: Yang Hua , Gan Jean , Xie Xiaoling , Deng Min , Feng Liang , Chen Xiaowei , Gao Zhiqiang , Gan Lin
Published: April 2010

Gfi1 encodes a zinc‐finger transcription factor essential for the development and maintenance of haematopoiesis and the inner ear. In mouse inner ear, Gfi1 expression is confined to hair cells during development and in adulthood. To construct a genetic tool for inner ear hair cell‐specific gene deletion, we generated a Gfi1‐Cre mouse line by knocking‐in Cre coding sequences into the Gfi1 locus and inactivating the endogenous Gfi1. The specificity and efficiency of Gfi1‐Cre recombinase‐mediated recombination in the developing inner ear was revealed through the expression of the conditional R26R‐lacZ reporter gene. The onset of lacZ expression in the Gfi1Cre/+ inner ear was first detected at E13.5 in the vestibule and at E15.5 in the cochlea, coinciding with the generation of hair cells. Throughout inner ear development, lacZ expression was detected only in hair cells. Thus, Gfi1‐Cre knock‐in mouse line provides a useful tool for gene manipulations specifically in inner ear hair cells. genesis 48:400–406, 2010. © 2010 Wiley‐Liss, Inc.
Ectoderm, endoderm, and the evolution of heterodont dentitions
Authors: Ohazama Atsushi , Haworth Kim E. , Ota Masato S. , Khonsari Roman H. , Sharpe Paul T.
Published: April 2010

Mammalian dentitions consist of different shapes/types of teeth that are positioned in different regions of the jaw (heterodont) whereas in many fish and reptiles all teeth are of similar type (homodont). The process by which heterodont dentitions have evolved in mammals is not understood. In many teleosts teeth develop in the pharynx from endoderm (endodermal teeth), whereas mammalian teeth develop from the oral ectoderm indicating that teeth can develop (and thus possibly evolve) via different mechanisms. In this article, we compare the molecular characteristics of pharyngeal/foregut endoderm with the molecular characteristics of oral ectoderm during mouse development. The expression domains of Claudin6, Hnf3β, α‐fetoprotein, Rbm35a, and Sox2 in the embryonic endoderm have boundaries overlapping the molar tooth‐forming region, but not the incisor region in the oral ectoderm. These results suggest that molar teeth (but not incisors) develop from epithelium that shares molecular characteristics with pharyngeal endoderm. This opens the possibility that the two different theories proposed for the evolution of teeth may both be correct. Multicuspid (eg. molars) having evolved from the externalization of endodermal teeth into the oral cavity and monocuspid (eg. incisors) having evolved from internalization of ectodermal armour odontodes of ancient fishes. The two different mechanisms of tooth development may have provided the developmental and genetic diversity on which evolution has acted to produce heterodont dentitions in mammals. genesis 48:382–389, 2010. © 2010 Wiley‐Liss, Inc.
Basic characteristics for PEN film surface modification using atmospheric‐pressure nonequilibrium microwave plasma jet
Authors: Yuji Toshifumi , Urayama Takuya , Fujii Shuitsu , Iijima Yoshitoki , Suzaki Yoshifumi , Akatsuka Hiroshi
Published: April 2010

To understand the mechanism of surface processing using an atmospheric‐pressure nonequilibrium microwave discharge plasma jet, we used optical emission spectroscopy to measure the vibrational and rotational temperatures of plasma. A microwave (2.45 GHz) power supply was used to excite the plasma. The vibrational and rotational temperatures in the plasma were measured at approximately 0.18 and 0.22 eV. We also conducted plasma surface processing of polyethylene naphthalate (PEN) film to measure changes in the water contact angle before and after the PEN film was processed and as the rotational temperature of the plasma increased. Analysis of all the results from XPS and surface free energy as calculated from the contact angle confirmed that an improvement in hydrophilic properties of the PEN film surface was produced by the microwave discharge plasma jet. We conclude that the hydrophilicity of the PEN film surface improves as the rotational temperature of the plasma increases. © 2010 Wiley Periodicals, Inc. Electron Comm Jpn, 93(5): 42–49, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecj.10207
Hydrogen‐ and carbon‐related defects in heavily carbon‐doped GaAs induced degradation under minority‐carrier injection
Authors: Fushimi Hiroshi , Wada Kazumi
Published: April 2010

GaAs/AlGaAs heterojunction bipolar transistors (HBTs) have attracted much attention because of their high‐speed performance. However, long‐term operation seriously degrades the device characteristics: the current gain decreases and the low‐bias‐leakage current increases. This degradation has long been an issue in GaAs‐based devices operated under minority‐carrier injection, such as laser diodes. The cause of degradation is thought to lie in the carbon‐doped base, but this is not yet certain. In this paper the degradation of HBTs is described, especially that of GaAs/AlGaAs HBTs with a heavily carbon‐doped base layer. Two types of device degradation are found, namely, hydrogen‐related degradation and carbon‐related degradation. The mechanisms governing the degradation are discussed in the framework of the recombination‐enhanced defect reaction (REDR) and charge state effect (CSE). © 2010 Wiley Periodicals, Inc. Electron Comm Jpn, 93(5): 33–41, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecj.10208
Basic study of dropout by phase jump characteristic modeling of distributed generators in secondary system for trunk transmission system analysis
Authors: Kobayashi Hideyuki , Kataoka Yoshihiko , Suzuki Mamoru , Naoi Shinya , Kudo Kazuhiko , Noro Yasuhiro , Omata Kazuya
Published: April 2010

The secondary systems are expressed by a reduced model in trunk transmission system analysis. Thus, multiple distributed generators in the secondary system are expressed by the reduced model. But by representing distributed generators by the reduced model, partial dropout of distributed generators cannot be expressed, and therefore there is a possibility that we cannot perform an accurate analysis. Consequently, we studied a method of dropout characteristics in which distributed generators are expressed by the reduced model. To obtain the dropout characteristic, we performed parameter studies by the detailed model and the reduced model on a secondary system under the same conditions. The parameter study indicated that in the dropout characteristic the remaining voltage in the primary system is correlated with the percentage of induction machines in the secondary system. Thus, we derived a dropout characteristic in which the above two quantities were taken as parameters. To confirm the validity of this dropout characteristic, we calculated the dropout magnitudes of the distributed generator for two or more conditions with both the detailed model and the reduced model. © 2010 Wiley Periodicals, Inc. Electr Eng Jpn, 172(1): 27–37, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.20869
Task learning of a task robot in real space by using a learning system in virtual space
Authors: Tsubone Tadashi , Kurimoto Kenichi , Sugiyama Koichi , Wada Yasuhiro
Published: April 2010

Reinforced learning by which a robot acquires control rules by trial and error has attracted considerable attention. However, it is quite difficult for robots to acquire control rules by reinforcement learning in the real space because many learning trials are needed to arrive at the control rules; the robot itself may lose control, or there may be safety problems with the control objects. In this paper we propose a method in which a robot in the real space learns a virtual task, after which the task is transferred from the virtual to the real space. The robot eventually acquires the task in a real environment. We show that a real robot can acquire a task in a virtual space with an input device, using the example of an inverted pendulum. Next, we verify that the acquired task in the virtual space can be applied to a real‐world task. We emphasize the utilization of the virtual space to effectively obtain the real‐world task. © 2010 Wiley Periodicals, Inc. Electr Eng Jpn, 172(1): 38–47, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.20968
Bromide‐Induced Formation of a Highly Symmetric Silver Thiolate Cluster Containing 36 Silver Atoms from an Infinite Polymeric Silver Thiolate
Authors: Liu Xiaomin , Yang Huayan , Zheng Nanfeng , Zheng Lansun
Published: April 2010

Owing to its good affinity with Ag+, Br– is able to truncate a silver thiolate polymer and induce the formation of a high‐nuclearity silver thiolate nanocluster, [Br@Ag36(SC6H4tBu‐4)36]–. The nanocluster has a disc‐like structure with one Br– anion trapped at the center of the cluster in an octahedral coordination.
Systematic Structural Coordination Chemistry of p‐tert‐Butyltetrathiacalix[4]arene: Further Complexes of Lanthanide Metal Ions
Authors: Bilyk Alexander , Dunlop John W. , Fuller Rebecca O. , Hall Annegret K. , Harrowfield Jack M. , Hosseini M. Wais , Koutsantonis George A. , Murray Ian W. , Skelton Brian W. , Sobolev Alexandre N. , Stamps Robert L. , White Allan H.
Published: April 2010

Extension of previous work on the lanthanide(III) ion complexes of p‐tert‐butyltetrathiacalix[4]arene has led to a variety of structurally characterised species containing oxo‐, hydroxo‐ and aqua‐ligands presumably derived from water present in the preparative medium, along with the thiacalixarene in various stages of deprotonation. The overall stoichiometry of some species is remarkably complicated due to the presence of simple anions and multiple solvents. Simplest is the binuclear complex [(μ‐H2O){Ln(O‐dmf)2}2(HL·dmf)2]·nS (dmf = dimethylformamide) [1Ln, Ln = Sm (nS = 2dmf), Eu (nS = 1.5dmf·2MeCN)], also the best‐defined of all the arrays studied. The heaviest lanthanides give trinuclear Ln(OH)3·2Ln(LH)·xdmf·yH2O (2Ln, Ln = Yb, Lu), while both oxo and hydroxo species are isolable with Eu: trinuclear Eu3O(L)(LH)(LH4)·13dmf (3) and tetranuclear Eu4O(OH)2(L)(LH2)2(LH4)·12dmf (9), both somewhat atypical species containing uncoordinated thiacalixarene molecules within the lattice. Anion (NO3, ClO4) coordination, as in the tri‐ and tetranuclear species, 4–6Ln, 9, 10Ln, 11Ln, 12, seems especially favoured for the lighter lanthanides. In these arrays, the Ln3 and Ln4 aggregates are triangular or (quasi‐)square‐planar, except for Gd4O2(LH2)4·2H2O·2MeOH·2dmf·3.375CH2Cl2 (12), where there is a Z‐disposition. Most common is an Ln3O core, which spans the gamut of Ln in three sets of crystal forms with cells of similar dimensions: for Ln = La...Nd, Ln3(OH)(NO3)4(LH2)2·4.5dmf (5Ln) (space group C2/m), and Sm...Lu, Ln3O(NO3)(LH)2·4H2O·2dmso·2MeCN·3py (6Ln) (space group P21/n), conformity with crystallographic symmetryentails disorder of the Ln atoms; in a further form of lowersymmetry Pn, (pyH)Ln3O(NO3)2(LH)2·2MeCN·xH2O·ydmso·1.5py·MeOH (7Ln, Ln = La, Ce), with no imposed crystallographic symmetry, some disorder persists, but none is found in the crystallographically unrelated form of 8Pr, Pr3O(NO3)(LH)2·16H2O·2MeCN·5py. Ln4(OH)(NO3)3(L)2·8dmf·2dmso·3H2O (10Ln, Ln = Pr...Gd, previously defined for Nd) has a square‐planar Ln4O array sandwiched between a pair of L ligands, with a similar form found for Ln4O(ClO4)2(L2)·xdmf·yH2O (11Ln, Ln = La...Nd).
Origin of CO32– Shortage in MgAl Layered Double Hydroxides with Mg/Al < 2
Authors: Ma Shulan , Fan Cuihong , Huang Gailing , Li Yumei , Yang Xiaojing , Ooi Kenta
Published: April 2010

A carbonate shortage phenomenon (CO32–/Al < 0.5) was found in MgAl layered double hydroxides (LDHs) withMg/Al < 2 synthesized by the homogeneous precipitation (urea hydrolysis) method. To explain the phenomenon, a “gibbsite‐layer based substitution–filling” model containing octahedral vacancies with formula [Mgy□0.5–y][MgxAl1–x](OH)3(CO32–)y–x/2·mH2O is proposed on the basis of the detailed composition analysis and ordered distribution of Mg and Al in the layer.
Synthesis and Characterization of Heteroscorpionate Rare‐Earth Metal Dialkyl Complexes and Catalysis on MMA Polymerization
Authors: Zhang Zhichao , Cui Dongmei , Trifonov Alexander A.
Published: April 2010

A series of rare‐earth metal alkyl complexes supported by a heteroscorpionate ligand were prepared and structurally characterized. X‐ray diffraction analysis revealed that the heteroscorpionate ligand is face‐capping on the rare‐earth metal in k3 mode, making the configuration of the afforded dialkyl metal complexes similar to that of half‐metallocenes. These complexes are capable of polymerizing methyl methacrylate, with the lutetium complex displaying the highest activity even at low temperature. The poly(methyl methacrylate) obtained is syndiotactically enriched with narrow molecular weight distribution.
Electrochemiluminescence Based on Solid State Tri(4,7‐diphenyl‐1,10‐phenanthroline) Ruthenium(II) Ditetrakis(4‐chlorophenyl) Borate Immobilized on Carbon Fibers
Authors: Liu Chunhua , Dai Jianyuan , Yang Li , Jiang Ping , Chen Ying , Xiao Dan
Published: April 2010

A simple method for immobilization of tri(4,7‐diphenyl‐1,10‐phenanthroline) ruthenium(II) ditetrakis(4‐chlorophenyl) borate ([Ru(dpp)3][(4‐Clph)4B]2) on carbon fiber electrodes was developed. Excellent electrochemical activity and electrochemiluminescence (ECL) signal of the coated carbon fiber electrodes were observed using oxalate as the co‐reactant. In addition, the effects of pH, scan rate, nitrogen and oxygen on ECL intensity were also studied. To demonstrate the reliability, the coated carbon fiber electrodes were used as ECL detectors and very low concentration of phenol was detectable (5.0×10−8 M).
Development of Quercetin Biosensor Through Immobilizing Laccase in a Modified β‐Cyclodextrin Matrix Containing Ag Nanoparticles in Ionic Liquid
Authors: Franzoi Ana Cristina , Cruz Vieira Iolanda , Weber Scheeren Carla , Dupont Jairton
Published: April 2010

A biosensor containing Ag nanoparticles in ionic liquid (IL) 1‐butyl‐3‐methylimidazolium bis(trifluoromethylsulfonyl)imide (BMI.Tf2N) and laccase (Lac) immobilized on β‐cyclodextrin modified with epichlorohydrin (β‐CDEpi) was developed for quercetin determination. Lac catalyses the oxidation of quercetin to quinone, which is then reduced on the biosensor surface and the resulting current was investigated by square‐wave voltammetry. The β‐CDEpi support was analyzed by scanning electron microscopy and Ag‐BMI.Tf2N by transmission electron microscopy and X‐ray diffraction. The linear range (0.499–7.407 μM) and low detection limit (0.037±0.004 μM) show that the proposed biosensor is suitable for quercetin determination in real samples.
Amperometric Determination of Glucose at Conventional vs. Nanostructured Gold Electrodes in Neutral Solutions
Authors: Wooten Marilyn , Shim Jun Ho , Gorski Waldemar
Published: April 2010

The conventional gold electrodes were compared with recently published electrodes based on gold nanoparticles and gold nanostructured films as amperometric sensors for glucose in pH 7.40 phosphate buffer solutions. The conventional electrodes provided similar electroanalytical benefits while required much simpler and shorter preparation. It is recommended that the future reports on the development of electrochemical sensors based on metal nanoparticles/nanostructures include also the analytical figures of merit obtained at relevant conventional metal electrodes. The voltammetric studies indicated that, in contrast to phosphate buffers, the Tris buffers were not suitable for activation of gold surface toward the direct oxidation of glucose.
Exercise‐induced lipid peroxidation: Implications for deoxyribonucleic acid damage and systemic free radical generation
Authors: Fogarty Mark C. , Hughes Ciara M. , Burke George , Brown John C. , Trinick Tom R. , Duly Ellie , Bailey Damian M. , Davison Gareth W.
Published: April 2010

Exercise‐induced deoxyribonucleic acid (DNA) damage is often associated with an increase in free radicals; however, there is a lack of evidence examining the two in parallel. This study tested the hypothesis that high‐intensity exercise has the ability to produce free radicals that may be capable of causing DNA damage. Twelve apparently healthy male subjects (age: 23 ± 4 years; stature: 181 ± 8 cm; body mass: 80 ± 9 kg; and VO2max: 49 ± 5 ml/kg/min) performed three 5 min consecutive and incremental stages (40, 70, and 100% of VO2max) of aerobic exercise with a 15‐min period separating each stage. Blood was drawn after each bout of exercise for the determination of ex vivo free radicals, DNA damage, protein carbonyls, lipid hydroperoxide (LOOH) concentration, and a range of lipid‐soluble antioxidants. Lipid‐derived oxygen‐centered free radicals (hyperfine coupling constants aNitrogen = 13.7 Gauss (G) and aβHydrogen = 1.8 G) increased as a result of acute moderate and high‐intensity exercise (P < 0.05), while DNA damage was also increased (P < 0.05). Systemic changes were observed in LOOH and for lipid‐soluble antioxidants throughout exercise (P < 0.05); however, there was no observed change in protein carbonyl concentration (P > 0.05). These findings identify lipid‐derived free radical species as possible contributors to peripheral mononuclear cell DNA damage in the human exercising model. This damage occurs in the presence of lipid oxidation but in the absence of any change to protein carbonyl concentration. The significance of these findings may have relevance in terms of immune function, the aging process, and the pathology of carcinogenesis. Environ. Mol. Mutagen. 52:35–42, 2011. © 2010 Wiley‐Liss, Inc.
DNA repair in mammalian mitochondria: Much more than we thought?
Authors: Liu Pingfang , Demple Bruce
Published: April 2010

For many years, the repair of most damage in mitochondrial DNA (mtDNA) was thought limited to short‐patch base excision repair (SP‐BER), which replaces a single nucleotide by the sequential action of DNA glycosylases, an apurinic/apyrimidinic (AP) endonuclease, the mitochondrial DNA polymerase γ, an abasic lyase activity, and mitochondrial DNA ligase. However, the likely array of lesions inflicted on mtDNA by oxygen radicals and the possibility of replication errors and disruptions indicated that such a restricted repair repertoire would be inadequate. Recent studies have considerably expanded our knowledge of mtDNA repair to include long‐patch base excision repair (LP‐BER), mismatch repair, and homologous recombination and nonhomologous end‐joining. In addition, elimination of mutagenic 8‐oxodeoxyguanosine triphosphate (8‐oxodGTP) helps prevent cell death due to the accumulation of this oxidation product in mtDNA. Although it was suspected for many years that irreparably damaged mtDNA might be targeted for degradation, only recently was clear evidence provided for this hypothesis. Therefore, multiple DNA repair pathways and controlled degradation of mtDNA function together to maintain the integrity of mitochondrial genome. Environ. Mol. Mutagen., 2010. © 2010 Wiley‐Liss, Inc.
Effects of in ovo exposure of white leghorn chicken, common pheasant, and Japanese quail to 2,3,7,8-tetrachlorodibenzo-p-dioxin and two chlorinated dibenzofurans on CYP1A induction
Authors: Yang Yinfei , Wiseman Steve , Cohen-Barnhouse Andrew M. , Wan Yi , Jones Paul D. , Newsted John L. , Kay Denise P. , Kennedy Sean W. , Zwiernik Matthew J. , Bursian Steven J. , Giesy John P.
Published: April 2010

In birds, activation of the aryl hydrocarbon receptor (AhR) by some polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) results in induction of cytochrome P4501A (CYP1A) expression. This response has been useful for predicting relative sensitivity of birds to dioxin-like compounds. To further investigate species-sensitivity to dioxins and dioxin-like compounds induction of cytochrome P450 1A4 and 1A5 (CYP1A4 and CYP1A5) mRNA and ethoxyresorufin O-deethylase (EROD) activity were quantified in liver of posthatch white leghorn chicken, common pheasant, and Japanese quail exposed to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), 2,3,4,7,8-pentachlorodibenzofuran (PeCDF), or 2,3,7,8-tetrachlorodibenzofuran (TCDF) via air cell injection. The rank-order of sensitivity of TCDD- and TCDF-exposed birds, based on CYP1A, was chicken > pheasant > quail. Based on CYP1A5 mRNA expression and EROD induction, the order of sensitivity of PeCDF-exposed birds was identical to that for TCDD and TCDF. However, based on CYP1A4 mRNA expression the rank-order was pheasant > chicken > quail. When comparing the potency of the three compounds in each species, based on CYP1A4 mRNA expression, TCDD was the most potent compound in chicken. However, PeCDF was equally potent to TCDD in quail and was more potent than TCDD in pheasant. These results suggest that quantitative real-time polymerase chain reaction (Q-PCR) analysis of CYP1A expression, particularly CYP1A4 mRNA expression, may be a more sensitive biomarker of exposure than analysis of EROD induction, especially in less responsive avian species. Based on these findings future risk assessments should consider the sensitivity of the species inhabiting a site and the congeners of concern that are present. Environ. Toxicol. Chem. 2010;29:1490–1502. © 2010 SETAC
Bioavailability of hexabromocyclododecane to the polychaeteHediste diversicolor: Exposure through sediment and food from a contaminated fjord
Authors: Haukås Marianne , Ruus Anders , Hylland Ketil , Berge John Arthur , Mariussen Espen
Published: April 2010

Knowledge of the bioavailability of brominated flame retardants for sediment-dwelling organisms is limited. The present study investigated bioaccumulation of hexabromocyclododecane (HBCD) in the ragworm Hediste diversicolor exposed to field-contaminated sediments and food. Sediments and blue mussels (Mytilus edulis) were sampled from a fjord on the Norwegian west coast known to be highly contaminated with the brominated flame retardant HBCD. During a four-week experiment, ragworms were either exposed to sediment containing moderate or high concentrations of HBCD, or they were fed contaminated soft tissue from mussel. Although mean sediment concentrations were as high as 40 µg/g dry weight in the contaminated sediments, no HBCD were detected in the exposed ragworms (detection limit up to 2.0 ng/g wet wt). In contrast, the exposure to contaminated food (mussel) resulted in elevated body concentrations of 9.1 ng HBCD/g wet weight. The partitioning of HBCD in the test-sediments appeared to be influenced by the quantity and quality of the sediment organic matter (up to 15% total organic carbon). The presence of small plastic beads (<2 mm), which were shown to contain a mean of 50 µg/g dry weight of HBCD, could explain the low bioavailability of the flame retardant in the sediment. Hexabromocyclododecane in food appeared to be readily assimilated in the ragworm, however, and the diastereomer pattern indicated a relative increase of α-HBCD from mussel to ragworm. Hence, in the sampled areas of the fjord, trophic transfer appeared to be a more important mechanism for the entry of HBCD into the local benthic food web than sediment-to-biota accumulation. Environ. Toxicol. Chem. 2010; 29:1709–1715. © 2010 SETAC
Autoantibodies against stress‐induced phosphoprotein‐1 as a novel biomarker candidate for ovarian cancer
Authors: Kim Sunghoon , Cho HanByoul , Nam Eun Ji , Kim Sang Wun , Kim Young Tae , Park Yong Won , Kim Bo Wook , Kim Jae‐Hoon
Published: April 2010

Detection of autoantibodies against tumor‐associated antigens (TAA) has recently been shown to be a powerful tool for early detection of various cancers. The aim of this study was to investigate the possibility of using autoantibodies against TAA as novel biomarkers by a proteomics‐based approach in patients with ovarian cancer. We used two‐dimensional differential gel electrophoresis analysis of immuno‐precipitated tumor antigens (2D‐DITA) to compare the levels of autoandibodies in pretreatment and posttreatment sera of patients with ovarian cancers. The identified autoantibodies were validated by SYBR Green real‐time polymerase chain reaction (PCR) and immunohistochemistry (IHC). We further evaluated the level of autoantibody in sera of 68 ovarian cancer patients by an enzyme‐linked immunosorbent assay (ELISA). The autoantibody directed against stress‐induced phosphoprotein‐1 (STIP‐1) emerged as a novel biomarker candidate for ovarian cancer. SYBR Green PCR and IHC confirmed that the STIP‐1 mRNA and protein expression levels were significantly up‐regulated in ovarian cancers compared with normal and benign tumors (P = 0.003 and P < 0.001, respectively). A preliminary ELISA study showed that the serum levels of anti‐STIP‐1 autoantibodies were significantly elevated in ovarian cancer patients compared with healthy controls (P = 0.03). The results suggest that 2D‐DITA is a useful tool to detect autoantibodies and that STIP‐1 is a potential biomarker candidate for ovarian cancers. © 2010 Wiley‐Liss, Inc.
Genome‐wide analysis of allelic imbalances reveals 4q deletions as a poor prognostic factor and MDM4 amplification at 1q32.1 in hepatoblastoma
Authors: Arai Yasuhito , Honda Shohei , Haruta Masayuki , Kasai Fumio , Fujiwara Yuiko , Ohshima Junjiro , Sasaki Fumiaki , Nakagawara Akira , Horie Hiroshi , Yamaoka Hiroyuki , Hiyama Eiso , Kaneko Yasuhiko
Published: April 2010

In a single‐nucleotide polymorphism array‐based analysis of 56 hepatoblastoma (HB) tumors, allelic imbalances were detected in 37 tumors (66%). Chromosome gains were found in 1q (28 tumors), 2q (24), 6p (8), 8q (8), 17q (6), and 20pq (10), and losses in 1p (6), 4q (9), and 16q (4). Fine mapping delineated the shortest overlapping region (SOR) of gains at 1q32.1 (1.3 Mb) and 2q24.2‐q24.3 (4.8 Mb), and losses at 4q34.3‐q35.2 (8.7 Mb) and 4q32.3 (1.6 Mb). Uniparental disomy of 11pter‐11p15.4 (IGF2) and loss of 11pter‐p14.1 were found in 11 and 2 tumors, respectively. Expression of HTATIP2 (11p15.1) was absent in 9 of 20 tumors. Amplification was identified in four tumors at 1q32.1, where the candidate oncogene MDM4 is located. In the 4q32.3‐SRO, ANXA10S, a variant of the candidate tumor suppressor ANXA10, showed no expression in 19 of 24 tumors. Sequence analysis of ANXA10S identified a missense mutation (E36K, c.106G>A) in a HB cell line. Multivariate analysis revealed that both 4q deletion and RASSF1A methylation (relative risks: 4.21 and 7.55, respectively) are independent prognostic factors. Our results indicate that allelic imbalances and gene expression patterns provide possible diagnostic and prognostic markers, as well as therapeutic targets in a subset of HB. © 2010 Wiley‐Liss, Inc.