bluuebunny/crossref_metadata_2025_split huggingface dataset:
Prestrain‐Free Dielectric Elastomers Based on Acrylic Thermoplastic Elastomer Gels: A Morphological and (Electro)Mechanical Property Study
Authors: Vargantwar Pruthesh H. , Özçam A. Evren , Ghosh Tushar K. , Spontak Richard J. 
Published: February 2012

AbstractRecent efforts have established that thermoplastic elastomer gels (TPEGs) composed of styrenic triblock copolymers swollen with a midblock‐selective solvent exhibit remarkable electromechanical properties as high‐performance dielectric elastomers. This class of electroactive polymers typically requires high electric fields for actuation, and a shortcoming that continues to thwart the widespread commercialization of such materials in general is the need to apply mechanical prestrain prior to electroactuation to decrease film thickness and, thus, the electric potential required to promote actuation. To alleviate this requirement, TPEGs consisting of acrylic triblock copolymers differing in molecular weight and composition, and swollen with a high dielectric, midblock‐selective solvent are investigated. Synchrotron small‐angle x‐ray scattering is used to probe the nanoscale morphologies of the resultant materials, and analysis of quasi‐static and cyclic tensile properties provides additional insight into both blend morphologies and electroactuation efficacy. Actuation strains measured in the absence of mechanical prestrain exceed 100% on an area basis, and electric fields capable of inducing actuation are as low as ∼20 kV/mm. Failure occurs by either electromechanical instability or dielectric breakdown, depending on the copolymer and TPEG composition employed. The electromechanical properties of these acrylic‐based TPEGs match or exceed those of skeletal muscle, in which case they constitute an attractive and unexplored alternative to existing dielectric elastomers.
The Origin of Magnetism in Mn‐Doped SrTiO3
Authors: Valant Matjaz , Kolodiazhnyi Taras , Arčon Iztok , Aguesse Frederic , Axelsson Anna‐Karin , Alford Neil M. 
Published: February 2012

AbstractAn analysis of Mn substitution in SrTiO3 is performed in order to understand the origin of reported spin coupling in lightly Mn‐doped SrTiO3. The spin glass state magnetoelectrically coupled to the dipolar glass state has previously been reported for SrTiO3 substituted with only 2% of Mn on the B‐site. An analysis of the substitution mechanism for A‐ and B‐site doping shows a strong influence of processing conditions, such as processing temperature, oxygen partial pressure, and off‐stoichiometry. The required conditions for a site‐selective substitution are defined, which yield a single‐phase and almost defect‐free perovskite. Magnetic measurements show no magnetic anomalies resulting from spin coupling and only a simple paramagnetic behavior. Magnetic anomalies are observed only for the samples in which Mn is misplaced within the cation sublattice of the SrTiO3 perovskite. This occurs due to improper material processing, which causes initially unpredicted changes in the valence state of the Mn and results in the formation of structural defects and irregularities associated with segregation and nucleation of the magnetic species. Previously reported spin coupling in Mn‐doped SrTiO3 is not an intrinsic phenomenon and cannot be treated as a spin glass.
Chemometric methods to classify stationary phases for achiral packed column supercritical fluid chromatography
Authors: West Caroline , Lesellier Eric 
Published: February 2012

SUMMARYThis paper investigates classification models for packed columns used in supercritical fluid chromatography (SFC). Forty‐eight columns of varied stationary phase chemistries available on the market are evaluated. The retention factors of 134 selected test compounds are used to compute hierarchical cluster analysis (HCA), principal component analysis (PCA), and quantitative structure–retention relationships (QSRRs). The use of HCA in conjunction with either PCA of QSRRs provides a classification of columns that is consistent with the experience of the SFC chromatographer. Besides, different coefficients, namely, Pearson correlation coefficient (r), selectivity difference (s2), distance (L), and angle (θ), were calculated between all couples of columns to identify a ranking index, which would provide meaningful information whenever two columns need to be compared on an objective basis. This can be the case either when an equivalent is sought for replacement of a reference column or when an orthogonal column is desired to achieve complementary selectivity. It is concluded that the θ angle and the normalized distance L/u are the best coefficients, allowing for a meaningful comparison between two columns. Copyright © 2012 John Wiley & Sons, Ltd.
Dihydrogen Generation from Amine/Boranes: Synthesis, FT‐ICR, and Computational Studies
Authors: Abboud José‐Luis M. , Németh Balázs , Guillemin Jean‐Claude , Burk Peeter , Adamson Aiko , Nerut Eva Roos 
Published: February 2012

AbstractA Fourier transform ion cyclotron resonance spectrometry (FT‐ICR) study of the gas‐phase protonation of ammonia‐borane and sixteen amine/boranes R1R2R3NBH3(including six compounds synthesized for the first time) has shown that, without exception, the protonation of amine/boranes leads to the formation of dihydrogen. The structural effects on the experimental energetic thresholds of this reaction were determined experimentally. The most likely intermediate and the observed final species (besides H2) are R1R2R3NBH4+and R1R2R3NBH2+, respectively. Isotopic substitution allowed the reaction mechanism to be ascertained. Computational analyses ([MP2/6‐311+G(d,p)] level) of the thermodynamic stabilities of the R1R2R3NBH3adducts, the acidities of the proton sources required for dihydrogen formation, and the structural effects on these processes were performed. It was further found that the family of R1R2R3NBH4+ions is characterized by a three‐center, two‐electron bond between B and a loosely bound H2molecule. Unexpected features of some R1R2R3NBH4+ions were found. This information allowed the properties of amine/boranes most suitable for dihydrogen generation and storage to be determined.
Tetrachlorinated Tetraazaperopyrenes (TAPPs): Highly Fluorescent Dyes and Semiconductors for Air‐Stable Organic n‐Channel Transistors and Complementary Circuits
Authors: Martens Susanne C. , Zschieschang Ute , Wadepohl Hubert , Klauk Hagen , Gade Lutz H. 
Published: February 2012

AbstractA range of 2,9‐perfluoroalkyl‐substituted tetraazaperopyrene (TAPP) derivatives (1–5) was synthesised by reacting 4,9‐diamino‐3,10‐perylenequinone diimine (DPDI) with the corresponding carboxylic acid chloride or anhydride in the presence of a base. The reaction of compounds 1–4 with dichloroisocyanuric acid (DIC) in concentrated sulphuric acid resulted in the fourfold substitution of the tetraazaperopyrene core, yielding the 2,9‐bisperfluoroalkyl‐4,7,11,14‐tetrachloro‐1,3,8,10‐tetraazaperopyrenes 6–9, respectively. The optical and electrochemical data demonstrate the drastic influence of the core substitution on the properties. All compounds are highly luminescent (fluorescence quantum yields of up to Φ=0.8). The LUMO energies of the tetrachlorinated TAPP derivatives (determined by cyclic voltammetry and computed by DFT calulations) were found to be below −4 eV. In the course of this work the performance of TAPP derivatives in organic thin‐film transistors (TFTs) was investigated, and their n‐channel characteristics with field‐effect mobilities of up to 0.14 cm2 V−1 s−1 and an on/off current ratio of >106 were confirmed. Long‐term stabilities of 3–4 months under ambient conditions of the devices were established. Complementary inverters and ring oscillators with n‐channel TFTs based on compound 8 and p‐channel TFTs based on dinaphtho‐[2,3‐b:2′,3′‐f]thieno[3,2‐b]thiophene (DNTT) were fabricated on a glass substrate.
Silver(I)‐Catalyzed Tandem 1,3‐Acyloxy Migration/Mannich‐type Addition/Elimination of the Sulfonyl Group of N‐Sulfonylhydrazone‐propargylic Esters to 5,6‐Dihydropyridazin‐4‐one Derivatives
Authors: Zhang Zhen , Shi Min 
Published: February 2012

AbstractThe addition of nucleophiles to CN bonds offers a highly efficient synthetic strategy for accessing nitrogen‐containing molecules.1 Among the well‐developed addition reactions, such as the highly efficient Mannich reaction, various CH bond‐activated compounds including carboxylic acid derivatives, nitroalkanes, and terminal alkynes have been applied as nucleophiles to achieve different classes of amines.2 However, employing new nucleophiles without activated CH bonds, such as internal alkynes and allenic esters are limited when using metal catalysts.3 Herein, we wish to report a new addition of allenic esters to CN bonds initiated by a silver‐catalyzed 1,3‐migration of propargylic esters.
Fully Automated Weighing of Liquid Substances with a Laboratory Robot
Authors: Werner Albert , Blaschke Tim , von Harbou Erik , Hasse Hans 
Published: February 2012

AbstractIm Labor ist die Einwaage eine Routineoperation, die bei der Durchführung von Messreihen häufig wiederholt wird. Sie erfolgt in der chemischen Industrie noch überwiegend manuell. In dieser Arbeit wird ein Verfahren zur vollautomatischen Einwaage von flüssigen Substanzen in Probengefäße mit einem Laborroboter vorgestellt. Als Anwendungsbeispiel wird die Herstellung von Proben für die Kalibrierung eines Gaschromatographen diskutiert. Die erreichten Genauigkeiten übertreffen die einer sorgfältigen manuellen Einwaage. Mit der vorgestellten Methode lassen sich die meisten im Laborbetrieb gängigen Flüssigkeiten handhaben.
Formation of an endoplasmic reticulum ring associated with acetylated microtubules in the angiosperm preprophase band
Authors: Giannoutsou Eleni , Galatis Basil , Zachariadis Michael , Apostolakos Panagiotis 
Published: February 2012

AbstractWe investigated the organization of the cortical endoplasmic reticulum (ER) in prophase cells of the angiosperms Zea mays, Triticum turgidum, and Vigna sinensis. In both symmetrically and asymmetrically dividing protodermal leaf cells, cortical ER was enriched in the preprophase band and colocalized there with microtubules, forming a ring‐like structure (ER ring). In contrast, ER ring was absent from prophase root‐tip cells of the same plants, suggesting that ER ring formation in the preprophase band is organ specific. Immunolabeling of the protodermal leaf cells revealed the presence of acetylated microtubules, which are more stable than the nonacetylated ones. In contrast, neither this post‐translational modification of tubulin nor an accumulation of ER in the preprophase band was detected in root‐tip cells. Experimentally delaying the maturation/disassembly of the microtubule ring of the preprophase band by taxol or cyclopiazonic acid treatment led to the appearance of ER ring and acetylated microtubules in the preprophase band. Together, our data show that in dividing cells of angiosperms, an ER ring associated with acetylated microtubules forms in the preprophase band. © 2012 Wiley Periodicals, Inc
Psychometric validation of the female sexual function index (FSFI) in cancer survivors
Authors: Baser Raymond E. , Li Yuelin , Carter Jeanne 
Published: February 2012

AbstractBACKGROUND:The Female Sexual Function Index (FSFI) is the most commonly used self‐report instrument to measure sexual functioning among women cancer survivors. Despite this, the validity and reliability of the FSFI for use in cancer populations has not been established.METHODS:Data were combined from 3 separate institutional review board‐approved studies of the psychosexual adjustment of women cancer survivors conducted at Memorial Sloan‐Kettering Cancer Center. Psychometric analysis was applied to the FSFI responses from 181 women comprising 4 cohorts, including survivors of: gynecologic cancer (all types; 2 cohorts), malignancies requiring bone‐marrow/stem cell transplantation, and early stage cervical cancer.RESULTS:A factor analysis supported the subscale structure of the FSFI, yielding results nearly identical to those from the original FSFI validation study. Internal consistency reliability was 0.94 for the FSFI total score and ranged from 0.85 to 0.94 for the domain scores. Corrected item‐total correlations ranged from 0.44 to 0.79 for the total score and from 0.62 to 0.88 for the domain scores. FSFI scores were correlated negatively with measures of depression, distress, and menopausal symptoms and were correlated positively with quality of life. FSFI scores exhibited a preliminary ability to discriminate between women based on whether or not they received chemotherapy and/or radiation.CONCLUSIONS:The FSFI demonstrated strong psychometric properties in this study, supporting its continued use for monitoring sexual function and cancer‐related dysfunction among sexually active women who are cancer survivors. Cancer 2012. © 2012 American Cancer Society.
Multimodal treatment, including interferon beta, of nasopharyngeal carcinoma in children and young adults
Authors: Buehrlen Martina , Zwaan Christian Michel , Granzen Bernd , Lassay Lisa , Deutz Peter , Vorwerk Peter , Staatz Gundula , Gademann Günther , Christiansen Hans , Oldenburger Foppe , Tamm Miriam , Mertens Rolf 
Published: February 2012

AbstractBACKGROUND:The authors report preliminary results from a prospective multicenter study (Nasopharyngeal Carcinoma [NPC] 2003 German Society of Pediatric Oncology and Hematology/German Children's Oncology Group [NPC‐2003‐GPOH/DCOG]).METHODS:From 2003 to 2010, 45 patients (ages 8‐20 years), including 1 patient with stage II NPC and 44 patients with stage III/IV NPC, were recruited to the study. The patient with stage II disease received radiotherapy (59.4 grays [Gy]). The patients with stage III/IV disease received 3 courses of neoadjuvant chemotherapy with cisplatin, 5‐fluorouracil, and folinic acid. The cumulative irradiation dose was 54 Gy in 5 patients, who achieved complete remission after neoadjuvant chemotherapy, and 59.4 Gy in the remaining 40 patients. All patients received concomitant cisplatin during the first week and last week of irradiation. After irradiation, all patients received interferon beta for 6 months. Tumor response was evaluated by magnetic resonance imaging studies and positron emission tomography scans.RESULTS:After the completion of treatment, 43 of 45 patients were in complete remission. In 2 patients, only a partial response was achieved, followed by distant metastases (1 patient) or local progression and distant metastases (1 patient), 6 months and 10 months after diagnosis, respectively. Another patient developed a solitary pelvic bone metastasis 21 months after diagnosis. After a median follow‐up of 30 months (range, 6‐95 months), the event‐free survival rate was 92.4%, and the overall survival was 97.1%. Acute toxicity consisted mainly of leucopenia, mucositis, and nausea; and late toxicity consisted of hearing loss and hypothyroidism.CONCLUSIONS:Combined therapy with neoadjuvant chemotherapy, radiochemotherapy, and interferon beta was well tolerated and resulted in a very good outcome that was superior to the outcomes of published results from all other pediatric NPC study groups. Cancer 2012. © 2012 American Cancer Society.
O6‐methylguanine‐DNA methyltransferase (MGMT) promoter methylation and low MGMT‐encoded protein expression as prognostic markers in glioblastoma patients treated with biodegradable carmustine wafer implants after initial surgery followed by radiotherapy with concomitant and adjuvant temozolomide
Authors: Lechapt‐Zalcman Emmanuèle , Levallet Guénaëlle , Dugué Audrey Emmanuelle , Vital Anne , Diebold Marie‐Danièle , Menei Philippe , Colin Philippe , Peruzzy Philippe , Emery Evelyne , Bernaudin Myriam , Chapon Françoise , Guillamo Jean‐Sébastien 
Published: February 2012

AbstractBACKGROUND:O6‐methylguanine‐DNA methyltransferase (MGMT) promoter methylation status was proposed as a prognostic biomarker for patients with glioblastoma. However, the prognostic impact of MGMT in patients with newly diagnosed glioblastoma who receive carmustine‐releasing wafers (Gliadel) along with temozolomide (TMZ) is still unknown.METHODS:MGMT promoter methylation status and protein expression were analyzed in formalin‐fixed, paraffin‐embedded tumor specimens obtained from 111 French patients with newly diagnosed glioblastoma. Patients received the Gliadel wafers followed by radiotherapy plus concomitant and adjuvant TMZ chemotherapy while they were enrolled in a French multicenter prospective study.RESULTS:For the whole cohort, the median overall survival (OS) was 17.5 months, and the progression‐free survival was 10.3 months. Patients with tumors that harbored MGMT methylation had a significantly longer OS compared with patients who had wild‐type MGMT (21.7 months vs 15.1 months; P = .025). Similarly, patients who had low MGMT protein expression (≤15%) had a significantly improved OS compared with patients who had high MGMT expression (27.0 months vs 15.1 months; P = .021). The extent of resection was the strongest clinical predictor of outcome. In multivariate Cox models that were adjusted for sex, performance status, and extent of surgery, both MGMT methylation and protein expression were identified as independent prognosticators, and the finding was validated internally using a bootstrap resampling technique. Discrepancies were identified between protein expression and MGMT methylation status, thus suggesting that the 2 assays probably assess different biologic features.CONCLUSIONS:MGMT promoter methylation status and low MGMT expression both were identified as positive prognosticators in patients with newly diagnosed glioblastoma who underwent surgical resection and received Gliadel wafer implants followed by adjuvant radiotherapy and concomitant oral TMZ chemotherapy (the Stupp protocol). Cancer 2012. © 2012 American Cancer Society.
Primary pulmonary lymphoepithelioma‐like carcinoma
Authors: Liang Ying , Wang Liang , Zhu Yujia , Lin Yongbin , Liu Hui , Rao Huilan , Xu Guangchuan , Rong Tiehua 
Published: February 2012

AbstractBACKGROUND:Pulmonary lymphoepithelioma‐like carcinoma (LELC) is a rare kind of cancer.METHODS:In this study, the authors evaluated 52 patients with pulmonary LELC who had long‐term follow‐up. Clinical characteristics, tumor markers, epidermal growth factor receptor (EGFR) mutation status, treatments, and outcomes were analyzed.RESULTS:Pulmonary LELC mostly affected young, nonsmoking patients. Most patients were in early or locally advanced stages and received multimodality treatment. Serum levels of neuron‐specific enolase and cytokeratin 19 fragment 21‐1 were elevated in 11 of 20 patients and 10 of 16 patients, respectively. Mutational analysis of EGFR was done in 11 patients, and all were wild type. The median overall survival (OS) for all the patients was not reached, and the 2‐year and 5‐year OS rate was 88% and 62%, respectively. The patients with early tumor stage, normal serum lactate dehydrogenase level, normal serum albumin level, without lymph node metastasis, and those who underwent complete resection had significantly better OS (P < .05); and the serum albumin level was an independent prognostic factor in a Cox regression model (P = .005). For all patients who underwent complete resection, whether or not they received adjuvant chemotherapy did not affect OS (P > .05); whereas, for patients with stage IIIA disease who underwent complete resection, adjuvant chemotherapy was correlated with a significantly better prognosis (P < .05).CONCLUSIONS:Pulmonary LELC obviously is a distinct entity of lung cancer that has a better prognosis, because patients with LELC can receive multimodality treatment, and LELC has biologic behavior similar to that of nasopharyngeal carcinoma. The current results indicated that future collaborative efforts are needed to determine the optimal treatment methods for this uncommon malignancy. Cancer 2012. © 2012 American Cancer Society.
Coke Formation and Carbon Atom Economy of Methanol‐to‐Olefins Reaction
Authors: Wei Yingxu , Yuan Cuiyu , Li Jinzhe , Xu Shutao , Zhou You , Chen Jingrun , Wang Quanyi , Xu Lei , Qi Yue , Zhang Qing , Liu Zhongmin 
Published: February 2012

AbstractThe methanol‐to‐olefins (MTO) process is becoming the most important non‐petrochemical route for the production of light olefins from coal or natural gas. Maximizing the generation of the target products, ethene and propene, and minimizing the production of byproducts and coke, are major considerations in the efficient utilization of the carbon resource of methanol. In the present work, the heterogeneous catalytic conversion of methanol was evaluated by performing simultaneous measurements of the volatile products generated in the gas phase and the confined coke deposition in the catalyst phase. Real‐time and complete reaction profiles were plotted to allow the comparison of carbon atom economy of methanol conversion over the catalyst SAPO‐34 at varied reaction temperatures. The difference in carbon atom economy was closely related with the coke formation in the SAPO‐34 catalyst. The confined coke compounds were determined. A new type of confined organics was found, and these accounted for the quick deactivation and low carbon atom economy under low‐reaction‐temperature conditions. Based on the carbon atom economy evaluation and coke species determination, optimized operating conditions for the MTO process are suggested; these conditions guarantee high conversion efficiency of methanol.
The First Molecular Level Monitoring of Carbohydrate Conversion to 5‐Hydroxymethylfurfural in Ionic Liquids. B2O3—An Efficient Dual‐Function Metal‐Free Promoter for Environmentally Benign Applications
Authors: Khokhlova Elena A. , Kachala Vadim V. , Ananikov Valentine P. 
Published: February 2012

AbstractThe mechanistic nature of the conversion of carbohydrates to the sustainable platform chemical 5‐hydroxymethylfurfural (5‐HMF) was revealed at the molecular level. A detailed study of the key sugar units involved in the biomass conversion process has shown that the simple dissolution of fructose in the ionic liquid 1‐butyl‐3‐methylimidazolium chloride significantly changes the anomeric composition and favors the formation of the open fructoketose form. A special NMR approach was developed for the determination of molecular structures and monitoring of chemical reactions directly in ionic liquids. The transformation of glucose to 5‐HMF has been followed in situ through the detection of intermediate species. A new environmentally benign, easily available, metal‐free promoter with a dual functionality (B2O3) was developed for carbohydrate conversion to 5‐HMF.
Soluble Polymer‐Supported Flow Synthesis: A Green Process for the Preparation of Heterocycles
Authors: Prosa Nicolò , Turgis Raphaël , Piccardi Riccardo , Scherrmann Marie‐Christine 
Published: February 2012

AbstractPEG‐supported aqueous flow synthesis coupled with ultrafiltration as the separation technique has been investigated for the first time. This strategy was applied to the preparation of new 3,4‐dihydropyrimidin‐2(1H)‐ones, tetrazoles and tetrahydro‐1,3‐oxazines from the same PEG‐linked aldehyde as case studies. Dihydropyrimidinones were prepared by a copper(II)‐catalysed Biginelli reaction whereas a new tetrazole‐containing compound was obtained by Baylis–Hillman reaction followed by reduction and 1,3‐dipolar cycloaddition. Finally, various new tetrahydro‐1,3‐oxazines were prepared by a four‐step synthesis, that is, Baylis–Hillman reaction, Michael addition of amines, cyclization with formaldehyde and hydrolysis of the linkage to PEG. The use of water during the synthesis and most of the purification steps, as well as the benefits of the flow process in terms of improved safety and heat transfer agree with the principles of green chemistry.