bluuebunny/crossref_metadata_2025_split huggingface dataset:
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

AbstractThe 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

AbstractConcept 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

AbstractDer 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

AbstractBACKGROUND: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

AbstractIn 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

AbstractWith 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.
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

AbstractWe 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

AbstractGfi1 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

AbstractMammalian 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

AbstractTo 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

AbstractGaAs/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

AbstractThe 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

AbstractReinforced 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

AbstractOwing 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

AbstractExtension 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

AbstractA 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

AbstractA 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

AbstractA 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).