bluuebunny/crossref_metadata_2025_split huggingface dataset:
Nanoporous Organosilicate Films Prepared in Acidic Conditions Using Tetraalkylammonium Bromide Porogens
Authors: Eslava Salvador , Baklanov Mikhail R. , Urrutia Jone , Kirschhock Christine E. A. , Maex Karen , Martens Johan A. 
Published: October 2008

AbstractOrganosilicate films with narrow pore size distribution tunable in the range of 1–3.4 nm were prepared by spin‐coating of silicon wafers with sols prepared in acidic conditions using tetraethyl orthosilicate, methyltrimethoxysilane, and tetraalkylammonium bromide (TAABr) porogen. The pore size was defined by the alkyl chain length of the quaternary ammonium molecule and the porogen concentration. The pore network in the films and the hydrophobicity of the pore surfaces were characterized using ellipsometric porosimetry with toluene and water adsorbates. In the absence of TAABr, the pore volume was 9 vol% and the pore size 1 nm. By using TAABr porogens, monomodal pore size distributions were obtained in the range of 1.2–3.5 nm. The pore volume was in the range from 18 vol% at 1.2 nm pore diameter up to 54 vol% at 3.5 nm diameter. The hydrophobicity of the pores was dependent on the pore diameter, with smaller pores being the least hydrophobic. The increase of hydrophobicity with pore size was explained by an increased distance between silanol groups on the curved pore surfaces. The mechanical properties and dielectric constant of these films were comparable to reference materials prepared using more sophisticated porogens reported in the literature.
Laterally Ordered Bulk Heterojunction of Conjugated Polymers: Nanoskiving a Jelly Roll
Authors: Lipomi Darren J. , Chiechi Ryan C. , Reus William F. , Whitesides George M. 
Published: October 2008

AbstractThis paper describes the fabrication of a nanostructured heterojunction of two conjugated polymers by a three‐step process: i) spin‐coating a multilayered film of the two polymers, ii) rolling the film into a cylinder (a “jelly roll”) and iii) sectioning the film perpendicular to the axis of the roll with an ultramicrotome (nanoskiving). The conjugated polymers are poly(benzimidazobenzophenanthroline ladder) (BBL, n‐type) and poly(2‐methoxy‐5‐(2′‐ethylhexyloxy)‐1,4‐phenylenevinylene) (MEH‐PPV, p‐type). The procedure produces sections with an interdigitated junction of the two polymers. The spacing between the phases is determined by spin‐coating (∼15 nm to 100 nm) and the thickness of each section is determined by the ultramicrotome (100 to 1000 nm). The minimum width of the MEH‐PPV layers accessible with this technique (∼15 nm) is close to reported exciton diffusion lengths for the polymer. When placed in a junction between two electrodes with asymmetric work functions (tin‐doped indium oxide (ITO) coated with poly(3,4‐ethylenedioxythiophene:poly(styrenesulfonate) (PEDOT:PSS), and eutectic gallium‐indium, EGaIn) the heterostructures exhibit a photovoltaic response under white light, although the efficiency of conversion of optical to electrical energy is low. Selective excitation of BBL with red light confirms that the photovoltaic effect is the result of photoinduced charge transfer between BBL and MEH‐PPV.
Reusable Cobalt(III)‐Salen Complex Supported on Activated Carbon as an Efficient Heterogeneous Catalyst for Synthesis of 2‐Arylbenzimidazole Derivatives
Authors: Sharghi Hashem , Aberi Mahdi , Doroodmand Mohammad Mahdi 
Published: October 2008

AbstractVarious 2‐arylbenzimidazoles were synthesized from phenylenediamines and aromatic aldehydes via a one‐step process in the presence of a catalytic amount of a cobalt‐salen complex supported on activated carbon [CoxO‐Co(salen) 11] at room temperature. The salient features of this method include mild conditions, short reaction times, high yields, easy purification, recyclable catalyst, large‐scale synthesis and simple procedure. The reactions were performed in ethanol and the catalyst could be reused for several cycles without a decrease in activity. The heterogeneous catalyst was characterized by powder X‐ray diffraction (XRD), scanning electron microscopy (SEM), atomic forced microscopy (AFM), thermogravimetric (TG) methods for analysis of nitrogen adsorption and FT‐IR spectroscopy. Leaching experiments showed that the catalyst is most strongly anchored to the activated support after 10 cycles of reuse.
Efficient and Versatile Sol‐Gel Immobilized Copper Catalyst for Ullmann Arylation of Phenols
Authors: Benyahya Sofia , Monnier Florian , Taillefer Marc , Man Michel Wong Chi , Bied Catherine , Ouazzani Fouad 
Published: October 2008

AbstractA new hybrid silica with urea‐based bipyridyl bridging units has been synthesized by a sol‐gel process. The copper‐complexed hybrid silica is an efficient heterogeneous catalyst for the Ullmann coupling of aryl halides with phenols. It is easily withdrawn and recovered from the reaction media by filtration. It is also a versatile catalyst for subsequent reactions with several substrates yielding products with the same efficiency even after ten re‐uses and with minimal leaching. This is the first example of the use of a copper‐complexed bridged silsesquioxane for the preparation of a recoverable catalyst in modern Ullmann chemistry. This may represent a promising route to the reduction of waste while maintaining economic viability.
Diazo Reagents in Copper(I)‐Catalyzed Olefination of Aldehydes
Authors: Lebel Hélène , Davi Michaël 
Published: October 2008

AbstractThe olefination of aldehydes to synthesize unsaturated ketones, esters, amides and phosphonates using diazo reagents and triphenylphosphine in the presence of copper(I) iodide as catalyst, is described. Good to excellent E:Z selectivities as well as yields were obtained for a large variety of aliphatic, aromatic and heteroaromatic aldehydes. The reaction showed also an excellent functional group compatibility and aldehydes were selectively reacted in the presence of ketone, nitro, amine, ether, acetal, thioether and halide groups. The use of a cost‐effective copper salt as a catalyst is advantageous compared to previously reported expensive transition metal complexes. The method was used in the total synthesis of the scutifoliamide A, a biologically active compound that exhibits antifungal activity.
Efficient Synthesis of γ,δ‐Alkynyl‐β‐amino Acid Derivatives by a New Copper‐Catalyzed Amine‐Alkyne‐Alkyne Addition Reaction
Authors: Zhou Lei , Jiang Huan‐feng , Li Chao‐Jun 
Published: October 2008

AbstractA simple and efficient method for the synthesis of γ,δ‐alkynyl‐β‐amino acid derivatives by a new copper‐catalyzed amines‐alkynes‐alkynes addition was developed. Various γ,δ‐alkynyl‐β‐amino acid derivatives were obtained in moderate to good yields in one step.
Exponential observers for distributed tubular (bio)reactors
Authors: García Míriam R. , Vilas Carlos , Banga Julio R. , Alonso Antonio A. 
Published: October 2008

AbstractThe dissipative nature of spatially distributed process systems is exploited to develop efficient exponential state observers based on a low‐dimensional dynamic representation of the original set of partial differential equations. The suggested approach combines standard observer design techniques for reactors, where the reaction rates are unknown with efficient model reduction methodologies based on projection of the original concentration and temperature fields on low‐dimensional subspaces capturing the slow dynamics of the process. The global exponential stability of the resulting observer is derived combining classical Lyapunov analysis with a transformation that allows us to obtain a diffusion system from a diffusion‐convection system. In addition, aspects related to the location of sensors and their influence on the ability to reconstruct the necessary fields to feed the observer will also be considered. © 2008 American Institute of Chemical Engineers AIChE J, 2008
Der seltsame Fall des Botulinum‐Neurotoxins: chemische und biologische Modulierung des tödlichsten aller Gifte
Authors: Willis Bert , Eubanks Lisa M. , Dickerson Tobin J. , Janda Kim D. 
Published: October 2008

AbstractIn seiner klassischen Erzählung “Der Seltsame Fall des Dr. Jekyll und Mr. Hide” beschreibt Robert Louis Stevenson einen gespaltenen Menschen zwischen Gut und Böse. Botulinum‐Neurotoxin (BoNT), der wirksamste bekannte Giftstoff, ist von ähnlich zwiespältiger Natur: BoNT zeigt einerseits eine ausgeprägte Morbidität und Mortalität, kommt andererseits aber – wenn auch in viel geringeren Dosen – in einem breiten Spektrum klinischer Szenarien zum Einsatz. In jüngerer Zeit sind enorme Fortschritte beim Verständnis der Struktur und Funktion von BoNT erzielt worden, die eine intensive Erforschung von biomakromolekularen und niedermolekularen Modulatoren der BoNT‐Aktivität nach sich zogen. Ein Schwerpunkt dieser Projekte lag auf der Identifizierung von Inhibitoren, die einer BoNT‐Exposition, z. B. im Falle eines bioterroristischen Anschlags, entgegenwirken können. Dieser Aufsatz fasst die aktuellen Fortschritte bei der Entwicklung von Therapeutika zur Prävention und Behandlung von Botulismus zusammen, mit einem Schwerpunkt auf Impfstoffen sowie peptidischen und niedermolekularen Inhibitoren.
The Strange Case of the Botulinum Neurotoxin: Using Chemistry and Biology to Modulate the Most Deadly Poison
Authors: Willis Bert , Eubanks Lisa M. , Dickerson Tobin J. , Janda Kim D. 
Published: October 2008

AbstractIn the classic novella “The Strange Case of Dr. Jekyll and Mr. Hyde”, Robert Louis Stevenson paints a stark picture of the duality of good and evil within a single man. Botulinum neurotoxin (BoNT), the most potent known toxin, possesses an analogous dichotomous nature: It shows a pronounced morbidity and mortality, but it is used with great effect in much lower doses in a wide range of clinical scenarios. Recently, tremendous strides have been made in the basic understanding of the structure and function of BoNT, which have translated into widespread efforts towards the discovery of biomacromolecules and small molecules that specifically modulate BoNT activity. Particular emphasis has been placed on the identification of inhibitors that can counteract BoNT exposure in the event of a bioterrorist attack. This Review summarizes the current advances in the development of therapeutics, including vaccines, peptides, and small‐molecule inhibitors, for the prevention and treatment of botulism.
Detecting changes in simulated events using partial‐interval recording and momentary time sampling
Authors: Rapp John T. , Colby‐Dirksen Amanda M. , Michalski Dara N. , Carroll Regina A. , Lindenberg Ally M. 
Published: October 2008

AbstractIn a series of three studies, we evaluated simulated data with reversal designs to determine whether partial‐interval recording (PIR) and momentary time sampling (MTS) detected changes that were evident with continuous measures. The results from Study 1 showed that MTS with interval sizes up to 30 s detected most of the moderate and large changes in duration events and MTS with interval sizes up to 1 min detected most large changes in duration events. By comparison, PIR with 10‐s intervals detected approximately half of all changes in duration events. The results of Study 2 showed that only 10‐s PIR reliably detected most small, moderate, and large changes in frequency events. The results of Study 3 showed that PIR with 10‐s intervals generated a relatively high percentage of false positives for duration events, whereas MTS did not. As a whole, the results support previous findings, but also provide new guidelines for the use of PIR and MTS. Copyright © 2008 John Wiley & Sons, Ltd.
Selektive, am Substrat bindende Proteaseinhibitoren
Authors: Hille‐Rehfeld Annette 
Published: October 2008

AbstractViele Enzymaktivitäten lassen sich durch Effektoren regulieren, die an das katalytische Zentrum oder ein allosterisches Zentrum des Enzyms binden. Jetzt kamen Wissenschaftler einem neuartigen Typ von Proteaseinhibitoren auf die Spur, die spezifisch an Proteinsubstrate binden und so deren proteolytische Spaltung hemmen.
Mainz und Freiburg
Authors: Schwedt Georg 
Published: October 2008

AbstractVon der Gesellschaft Deutscher Chemiker (GDCh) wird an Wirkungsstätten bedeutender Chemiker durch Gedenktafeln und an die Forschung der Wissenschaftler durch die Herausgabe einer Broschüre erinnert. Auf diese Weise werden einer breiteren Öffentlichkeit historische Wurzeln und das kulturelle Erbe der Chemie bekannt gemacht.
Stream Temperature Trends in Turkey
Authors: Albek Mine , Albek Erdem 
Published: October 2008

AbstractStream temperature is an important property of water and affects most other water quality constituents. It is also a property which is very much influenced by exogenous factors like air temperature and stream flow. This study investigates long‐term trends in stream temperatures measured at various stream monitoring stations in Turkey to better understand links with climate change. It was found by statistical trend analysis that more streams have experienced decreasing trends than increasing ones. Moreover, stream temperatures show a rising tendency in most stations over Turkey. Flow‐adjusted temperatures were computed to eliminate flow dependency and these show more positive than negative trends. Management plans of streams and watersheds need to take this into account and incorporate the implications into plans.
Prognostic factors and a scoring system for survival after radiotherapy for metastases to the spinal column
Authors: Mizumoto Masashi , Harada Hideyuki , Asakura Hirofumi , Hashimoto Takayuki , Furutani Kazuhisa , Hashii Haruko , Takagi Tatsuya , Katagiri Hirohisa , Takahashi Mitsuru , Nishimura Tetsuo 
Published: October 2008

AbstractBACKGROUND.To optimize selection of a radiotherapy schedule for patients with spinal metastases, the authors analyzed prognostic factors and developed a scoring system to predict survival in such patients.METHODS.Five‐hundred forty‐four patients with spinal metastases received radiotherapy at Shizuoka Cancer Center Hospital between September 2002 and November 2006. Prognostic factors for survival were studied using a Cox proportional hazards model, and a scoring system was developed based on regression coefficients: Three points were given for an unfavorable tumor type and bad performance status (≥3); 2 points were given for hypercalcemia, visceral metastases, and previous chemotherapy; and 1 point was given for multiple bone metastases and age ≥71 years.RESULTS.The overall survival rates after 6 months, 12 months, and 24 months were 49%, 32%, and 19%, respectively, and the median survival was 5.9 months (95% confidence interval, 4.9‐6.8 months). In total, 503 patients (93%) were followed for ≥12 months or until death. These patients were separated into Groups A, B, and C based on scores of 0 to 4, 5 to 9, and 10 to 14, respectively. These groups included 24%, 57%, and 19% of patients, respectively; and the mean median survival for Groups A, B, and C was 27.1 months, 5.4 months, and 1.8 months, respectively. Overall survival rates after 6 months, 12 months, and 24 months were 89%, 77%, and 54% in Group A; 46%, 22%, and 9% in Group B; and 7%, 4%, and 0% in Group C, respectively (P < .001).CONCLUSIONS.The scoring system was able to predict the survival of patients with spinal metastases and may be useful for selecting an optimal radiotherapy schedule. Cancer 2008. © 2008 American Cancer Society.
Evaluation of second‐order derivative of potential on boundary by discontinuous boundary element with exact integrations
Authors: Zhang Xiaosong , Zhang Xiaoxian 
Published: October 2008

AbstractExact integration of discontinuous quartic boundary element for evaluation of potential, its first‐order and second‐order derivative is presented. A patch test problem with three kinds of boundary conditions is implemented to show that the discontinuous boundary element with exact integration can evaluate the potential, its first‐order and second‐order derivative on boundary with high accuracy. Copyright © 2008 John Wiley & Sons, Ltd.
Effect of methamphetamine exposure and cross‐fostering on sensorimotor development of male and female rat pups
Authors: Hrubá Lenka , Schutová Barbora , Šlamberová Romana , Pometlová Marie , Rokyta Richard 
Published: October 2008

AbstractThe present study tested the hypothesis that cross‐fostering influences the development of rat pups. Mothers were exposed daily to injection of methamphetamine (M) (5 mg/kg) or saline for 9 weeks: 3 weeks prior to impregnation, throughout gestation and lactation periods. Control females animals without any injections were used. On postnatal day (PD) 1, pups were cross‐fostered so that each mother received four pups of her own and eight pups from the mothers with the other two treatments. Offspring were tested for sensorimotor development in preweaning period by using tests of: negative geotaxis, tail pull, righting reflexes, rotarod and bar‐holding. Further, the pups were weighed daily. Our results showed that birth weight in prenatally M‐exposed pups was lower than in control or saline‐exposed pups. Prenatally M‐exposed pups gained less weight than control or saline‐exposed pups regardless of postnatal treatment and sex. Further, our data demonstrated that prenatal and postnatal M exposure impairs sensorimotor functions in most of the tests. On the other hand, the negative effect of prenatal M exposure was partially suppressed in prenatally M‐exposed pups by cross‐fostering to control dams. Our hypothesis that cross‐fostering may affect postnatal development of pups was confirmed. © 2008 Wiley Periodicals, Inc. Dev Psychobiol 51: 73–83, 2009
Spin Canting in a Cobalt(II) Radical Complex with an Acentric Counter Anion
Authors: Mitsumoto Kiyotaka , Shiga Takuya , Nakano Motohiro , Nihei Masayuki , Nishikawa Hiroyuki , Oshio Hiroki 
Published: October 2008

AbstractCobalt(II) radical complexes with centric and acentric counter anions, [CoCl(bisimpy)(MeOH)2]X [bisimpy = 2,6‐bis(4′,4′,5′,5′‐tetramethyl‐4′,5′‐dihydro‐1′H‐imidazol‐1′‐oxyl‐2′‐yl)pyridine; X = PF6 (1), and ClO4 (2)], crystallize in the centrosymmetric and polar space groups, respectively. Compound 1 is paramagnetic, whereas spin canting in 2 leads to a metamagnetic transition with a critical field of 1300 Oe at 1.8 K. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
Chemical and enzymatic interesterification of tristearin/ triolein‐rich blends: Chemical composition, solid fat content and thermal properties
Authors: Ahmadi Latifeh , Wright Amanda J. , Marangoni Alejandro G. 
Published: October 2008

AbstractBlends of high‐oleic sunflower oil and fully hydrogenated canola oil were subjected to enzymatic and chemical interesterification using Candida antarctica lipase (5%) and sodium methoxide (0.3%), respectively. The effect of each interesterification process was determined by comparing the triacylglycerol (TAG) composition, solid fat content (SFC) profiles and thermal properties of the blends before and after interesterification. Interesterification resulted in a decrease in the concentration of triunsaturated and trisaturated TAG and an increase in the proportion of mono‐ and disaturated TAG. These alterations in TAG composition and the presence of a greater variety of TAG species upon interesterification was correlated with a broader melting transition by differential scanning calorimetry and, ultimately, a lower melting point for the interesterified blends. Much broader ranges in plasticity were observed for the interesterified blends (chemically and enzymatically) compared to the physical blends. Even though ideal solubility of stearin in oil was observed, the value predicted by the Hildebrand model was higher than the actual amount. Crystallization kinetic parameters (Avrami index and rate constant) were similar for the non‐interesterified, enzymatically interesterified and chemically interesterified blends when compared as a function of SFC. Results from this work will aid in the formulation of more healthy fat and oil products and address a critical industrial demand in terms of formulation options for spreads, margarines and shortenings.
Enrichment of pomace olive oil in triterpenic acids during storage of “Alpeorujo” olive paste
Authors: García Aranzazu , Brenes Manuel , Dobarganes Mª Carmen , Romero Concepción , Ruiz‐Méndez Ma Victoria 
Published: October 2008

AbstractTriterpenic acids are natural compounds present in plants and foods with beneficial properties for human health and thus they are desirable in the food, cosmetics and pharmaceutical industries. Pomace olive is considered a good source of these substances. In this study, oleanolic and maslinic acids were found to be the main triterpenic acids identified in pomace olive oil obtained from stored “Alpeorujo”. Determination of the two acids was achieved by a new procedure that consists of extracting the acids from the oil with a mixture of methanol/ethanol, and then separating and quantifying them by HPLC. Results showed that their concentration increased up to 16 g/kg of oil during storage of the pomace in large ponds for 7 months. The concentration of both triterpenic acids was similar in the pomace olive oil obtained by using the centrifugation system. By contrast, a much lower concentration of maslinic than oleanolic acid was detected in pomace olive oils obtained by solvent extraction from the previously centrifugated “Alpeorujo” paste. These triterpenic acids also contributed to the acidity of the crude oil. Likewise, the oil of the pomace paste was enriched in other substances such as 4‐ethylphenol and aliphatic alcohols during the storage of the paste in large ponds. Consequently, crude pomace olive oil can be considered a good source of triterpenic acids when obtained from a stored olive paste.
Residual Dipolar Couplings (RDCs) in Organic Structure Determination
Authors: Thiele Christina M. 
Published: October 2008

AbstractAfter the huge impact that residual dipolar couplings (RDCs) have had on the structure determination of biological macromolecules by NMR spectroscopy, their utility in the structure determination of small/medium‐sized organic compounds is more and more recognised. This microreview will provide a short overview on how to introduce the anisotropic environment necessary to measure RDCs, the corresponding measurement methods and the applications for the determination of the relative configurations and the assignment of diastereotopic moieties. Their application to rigid compounds will be described, as will their very promising application to more flexible compounds, which is an area in which RDCs are expected to yield information that is not accessible by any other NMR spectroscopic means. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
Cyclic Metalated Nitriles: Stereoselective Cyclizations to cis‐ and trans‐Hydrindanes, Decalins, and Bicyclo[4.3.0]undecanes
Authors: Fleming Fraser F. , Gudipati Subramanyham 
Published: October 2008

AbstractMetalated nitriles are nucleophilic chameleons whose precise identity is determined by the nature of the metal, the solvent, the temperature, and the structure of the nitrile. The review surveys the different structural types and their cyclization trajectories to show how to selectively tune the metalated nitrile geometry for stereoselective cyclizations to a variety of cis or trans hydrindanes, decalins, and bicyclo[4.3.0]undecanes. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)