bluuebunny/crossref_metadata_2025_split huggingface dataset:
Synthesis and Enzymatic Deprotection of Fully Protected 2′‐5′ Oligoadenylates (2‐5A): Towards a Prodrug Strategy for Short 2‐5A
Authors: Kiuru Emilia , Ora Mikko , Beigelman Leonid , Blatt Lawrence , Lönnberg Harri 
Published: April 2012

AbstractFully protected pA2′p5′A2′p5′A trimers 1a and 1b have been prepared as prodrug candidates for a short 2′‐5′ oligoadenylate, 2‐5A, and its 3′‐O‐Me analog, respectively. The kinetics of hog liver carboxyesterase (HLE)‐triggered deprotection in HEPES buffer (pH 7.5) at 37° has been studied. The deprotection of 1a turned out to be very slow, and 2‐5A never appeared in a fully deprotected form. By contrast, a considerable proportion of 1b was converted to the desired 2‐5A trimer, although partial removal of the 3′‐O‐[(acetyloxy)methyl] group prior to exposure of the adjacent phosphodiester linkage resulted in 2′,5′→3′,5′ phosphate migration and release of adenosine as side reactions.
Chemical Composition and Antimicrobial Activity of Essential Oils from Scabiosa arenariaForssk. Growing Wild in Tunisia
Authors: Besbes Malek , Omri Amel , Cheraif Imed , Daami Mejda , Jannet Hichem Ben , Mastouri Maha , Aouni Mahjoub , Selmi Boulbaba 
Published: April 2012

AbstractThe essential oils isolated from three organs, i.e., fruits, stems and leaves, and flowers, of the endemic North African plant Scabiosa arenaria Forssk. were screened for their chemical composition, as well as their possible antibacterial, anticandidal, and antifungal properties. According to the GC‐FID and GC/MS analyses, 61 (99.26% of the total oil composition), 79 (98.43%), and 51 compounds (99.9%) were identified in the three oils, respectively. While α‐thujone (34.39%), camphor (17.48%), and β‐thujone (15.29%) constituted the major compounds of the fruit oil, chrysanthenone (23.43%), together with camphor (12.98%) and α‐thujone (10.7%), were the main constituents of the stem and leaf oil. In the case of the flower oil, also chrysanthenone (38.52%), camphor (11.75%), and α‐thujone (9.5%) were identified as the major compounds.Furthermore, the isolated oils were tested against 16 Gram‐positive and Gram‐negative bacteria, four Candida species, and nine phytopathogenic fungal strains. It was found that the oils exhibited interesting antibacterial and anticandidal activities, comparable to those of thymol, which was used as positive control, but no activity against the phytopathogenic fungal strains was observed.
Chemical Composition and Intraspecific Variability of the Essential Oils of Five Populations of Hypericum triquetrifoliumTurra Growing in North Tunisia
Authors: Rouis Zyed , Elaissi Ameur , Abid Nabil Ben Salem , Lassoued Mohamed Ali , Cioni Pier Luigi , Flamini Guido , Aouni Mahjoub 
Published: April 2012

AbstractThe chemical composition of the essential oils of five populations of Hypericum triquetrifolium Turra from Tunisia and their intraspecific variability were analyzed in detail by GC/MS. One hundred seventy‐four compounds were identified, representing averages of 87.9 to 98.7% of the oil composition. The components are represented here by homologous series of monoterpene hydrocarbons, oxygenated monoterpenes, sesquiterpenes hydrocarbons, oxygenated sesquiterpenes, non‐terpenic hydrocarbons, and others. Sesquiterpene hydrocarbons were the most abundant chemical compounds. Multivariate chemometric techniques, such as cluster analysis (CA) and principal‐component analysis (PCA), were used to characterize the samples according to the geographical origin. By statistical analysis, the analyzed populations were classified into four chemotype groups.
Synthesis and Immunostimulating Properties of Novel Adamant‐1‐yl Tripeptides
Authors: Ribić Rosana , Habjanec Lidija , Vranešić Branka , Frkanec Ruža , Tomić Srđanka 
Published: April 2012

AbstractThe aim of this work was to prepare L‐ and D‐(adamant‐1‐yl)‐Gly‐L‐Ala‐D‐isoGln peptides in order to study their adjuvant (immunostimulating) activities. Adjuvant activity of adamant‐1‐yl tripeptides was tested in the mouse model using ovalbumin as an antigen and in comparison to the peptidoglycan monomer (PGM; β‐D‐GlcNAc‐(1→4)‐D‐MurNAc‐L‐Ala‐D‐isoGln‐mesoDAP(εNH2)‐D‐Ala‐D‐Ala) and structurally related adamant‐2‐yl tripeptides.
Chemical and Genetic Study of Ligularia duciformis and Related Species in Sichuan and Yunnan Provinces of China
Authors: Nagano Hajime , Hanai Ryo , Yamada Hiroka , Matsushima Mika , Miura Yui , Hoya Takanori , Ozawa Masaaki , Fujiwara Miho , Kodama Hikari , Torihata Atsushi , Onuki Hiroyuki , Nezu Yoko , Kawai Satoru , Yamazaki Mizue , Hirota Hiroshi , Saito Yoshinori , Tori Motoo , Ohsaki Ayumi , Gong Xun , Kuroda Chiaki 
Published: April 2012

AbstractThe chemical constituents of the root extracts and the evolutionarily neutral DNA base sequences were studied for 28 samples of Ligularia duciformis, L. kongkalingensis, and L. nelumbifolia collected in Sichuan and Yunnan Provinces of China. The samples could be classified into four chemotypes (1–4). Sesquiterpenoids having eremophilane and oplopane skeletons were isolated from two (Chemotype 1) and three (Chemotype 2) samples, respectively. Two new oplopane derivatives were isolated and their structures were determined. In 18 samples, phenylpropenoids were the major components (Chemotype 3). In five samples, neither phenylpropenoids nor sesquiterpenoids were found (Chemotype 4). Despite this large chemical variety, no correlation was found between the chemotype and the morphological criteria of species identification. The analysis of the evolutionarily neutral DNA regions also indicated that the samples were not separated into distinct clades and that introgression was extensive.
Site‐Specific Protein Modification Using Lipoic Acid Ligase and Bis‐Aryl Hydrazone Formation
Authors: Cohen Justin D. , Zou Peng , Ting Alice Y. 
Published: April 2012

AbstractA screen of Trp37 mutants of Escherichia coli lipoic acid ligase (LplA) revealed enzymes capable of ligating an aryl‐aldehyde or aryl‐hydrazine substrate to LplA's 13‐residue acceptor peptide. Once site‐specifically attached to recombinant proteins fused to this peptide, aryl‐aldehydes could be chemoselectively derivatized with hydrazine‐probe conjugates, and aryl‐hydrazines could be derivatized in an analogous manner with aldehyde‐probe conjugates. Such two‐step labeling was demonstrated for AlexaFluor568 targeting to monovalent streptavidin in vitro, and to neurexin‐1β on the surface of living mammalian cells. To further highlight this technique, we labeled the low‐density lipoprotein receptor on the surface of live cells with fluorescent phycoerythrin protein to allow single‐molecule imaging and tracking over time.
Chain Elongation and Cyclization in Type III PKS DpgA
Authors: Wu Hai‐Chen , Li Yi‐San , Liu Yu‐Chen , Lyu Syue‐Yi , Wu Chang‐Jer , Li Tsung‐Lin 
Published: April 2012

AbstractChain elongation and cyclization of precursors of dihydroxyphenylacetyl‐CoA (DPA‐CoA) catalyzed by the bacterial type III polyketide synthase DpgA were studied. Two labile intermediates, di‐ and tri‐ketidyl‐CoA (DK‐ and TK‐CoA), were proposed and chemically synthesized. In the presence of DpgABD, each of these with [13C3]malonyl‐CoA (MA‐CoA) was able to form partially 13C‐enriched DPA‐CoA. By NMR and MS analysis, the distribution of 13C atoms in the partially 13C‐enriched DPA‐CoA shed light on how the polyketide chain elongates and cyclizes in the DpgA‐catalyzed reaction. Polyketone intermediates elongate in a manner different from that which had been believed: two molecules of DK‐CoA, or one DK‐CoA plus one acetoacetyl‐CoA (AA‐CoA), but not two molecules of AA‐CoA can form one molecule of DPA‐CoA. As a result, polyketidyl‐CoA serves as both the starter and extender, whereas polyketone‐CoA without the terminal carboxyl group can only act as an extender. The terminal carboxyl group is crucial for the cyclization that likely takes place on CoA.
Recovery of Ionic Substances from Wastewater by Seeded Reaction Crystallization
Authors: Shimizu Y. , Hirasawa I. 
Published: April 2012

AbstractCrystallization is a suitable process for selective separation of a target ion since ions can be removed and recovered as purified and stable materials. Methods of recovery and recycling of phosphate and fluoride ions have been investigated to determine the optimum crystallization conditions like supersaturation, temperature, pH, impurities, and kind of solvents. As a result, by selecting the optimum crystal operation conditions for each wastewater composition, spherical‐shape crystals with desired purity and size are obtained and generation of sludge is minimized.
Algorithm combination strategy to obtain the second‐order advantage: simultaneous determination of target analytes in plasma using three‐dimensional fluorescence spectroscopy
Authors: Yu Yong‐Jie , Wu Hai‐Long , Kang Chao , Wang Yu , Zhao Juan , Li Yuan‐Na , Liu Ya‐Juan , Yu Ru‐Qin 
Published: April 2012

ABSTRACTAlthough a number of algorithms have established to obtain the well‐known second‐order advantage that quantifies analytes of interest in the presence of interferents, each has associated problems. In this work, for the first time, the optimization procedure of trilinear decomposition has been divided into three subparts, and a novel strategy is developed for assembling the advantages of the alternating trilinear decomposition (ATLD) algorithm, the self‐weighted alternating trilinear decomposition (SWATLD) algorithm, and the parallel factor analysis (PARAFAC) algorithm. The performance of the proposed strategy was evaluated using a simulated data set, a published fluorescence data set together with a new fluorescence data set that simultaneously quantifies procaine and tetracaine in plasma. Results show that the novel method can accurately and effectively estimate the qualitative and quantitative information of analytes of interest. Besides, the resolved profiles are very stable with respect to the number of components as long as the employed number is chosen to be equal or larger than the underlying one. Additionally, the study confirms that better prediction can be obtained by the new strategy when compared with ATLD, SWATLD, and PARAFAC as well as the strategy that employs direct trilinear decomposition method as initial values for PARAFAC. Moreover, the strategy can be directly extended to third‐order or higher‐order data analysis. Copyright © 2012 John Wiley & Sons, Ltd.
A New Ammine Dual‐Cation (Li, Mg) Borohydride: Synthesis, Structure, and Dehydrogenation Enhancement
Authors: Sun Weiwei , Chen Xiaowei , Gu Qinfen , Wallwork Kia S. , Tan Yingbin , Tang Ziwei , Yu Xuebin 
Published: April 2012

AbstractA new ammine dual‐cation borohydride, LiMg(BH4)3(NH3)2, has been successfully synthesized simply by ball‐milling of Mg(BH4)2 and LiBH4⋅NH3. Structure analysis of the synthesized LiMg(BH4)3(NH3)2 revealed that it crystallized in the space group P63 (no. 173) with lattice parameters of a=b=8.0002(1) Å, c=8.4276(1) Å, α=β=90°, and γ=120° at 50 °C. A three‐dimensional architecture is built up through corner‐connecting BH4 units. Strong NH⋅⋅⋅HB dihydrogen bonds exist between the NH3 and BH4 units, enabling LiMg(BH4)3(NH3)2 to undergo dehydrogenation at a much lower temperature. Dehydrogenation studies have revealed that the LiMg(BH4)3(NH3)2/LiBH4 composite is able to release over 8 wt % hydrogen below 200 °C, which is comparable to that released by Mg(BH4)3(NH3)2. More importantly, it was found that release of the byproduct NH3 in this system can be completely suppressed by adjusting the ratio of Mg(BH4)2 and LiBH4⋅NH3. This chemical control route highlights a potential method for modifying the dehydrogenation properties of other ammine borohydride systems.
Deciphering the Activation Sequence of Ferrociphenol Anticancer Drug Candidates
Authors: Messina Pierluca , Labbé Eric , Buriez Olivier , Hillard Elizabeth A. , Vessières Anne , Hamels Didier , Top Siden , Jaouen Gérard , Frapart Yves Michel , Mansuy Daniel , Amatore Christian 
Published: April 2012

AbstractThe complete oxidation sequence of a model for ferrociphenols, a new class of anticancer drug candidate, is reported. Cyclic voltammetry was used to monitor the formation of oxidation intermediates on different timescales, thereby allowing the electrochemical characterization of both the short‐lived and stable species obtained from the successive electron‐transfer and deprotonation steps. The electrochemical preparation of the ferrocenium intermediate enabled a stepwise voltammetric determination of the stable oxidation compounds obtained upon addition of a base as well as the electron stoichiometry observed for the overall oxidation process. A mechanism has been established from the electrochemical data, which involves a base‐promoted intramolecular electron transfer between the phenol and the ferrocenium cation. The resulting species is further oxidized then deprotonated to yield a stable quinone methide. To further characterize the transient species successively formed during the two‐electron oxidation of the ferrociphenol to its quinone methide, EPR was used to monitor the fate of the paramagnetic species generated upon addition of imidazole to the electrogenerated ferrocenium. The study revealed the passage from an iron‐centered to a carbon‐centered radical, which is then oxidized to yield the quinone methide, namely, the species that interacts with proteins and so forth under biological conditions.
Medium‐Sized Rings versus Macrocycles through Rhodium‐Catalyzed Ring‐Expansion Reactions of Cyclic Acetals
Authors: Ballesteros‐Garrido Rafael , Rix Diane , Besnard Céline , Lacour Jérôme 
Published: April 2012

Abstractα‐Diazo β‐ketoesters and diketones react with cyclic acetals under RhIIcatalysis to yield unprecedented polyoxygenated 8‐ and 9‐membered rings in one pot. The reactions occur under mild conditions with yields up to 90 %. A perfect regioselectivity is obtained, which can be rationalized through a mechanistic hypothesis that considers 1) the formation of an oxonium ylide, 2) its transformation into an unsaturated acyclic oxocarbenium electrophilic intermediate, and 3) an intramolecular nucleophilic attack in a direct application of Baldwin’s rules.
Gated Photochromism and Acidity Photomodulation of a Diacid Dithienylethene Dye
Authors: Massaad Julie , Micheau Jean‐Claude , Coudret Christophe , Sanchez Rafael , Guirado Gonzalo , Delbaere Stéphanie 
Published: April 2012

AbstractThe present study quantitatively analyses the gated photochromism and the acidity photomodulation properties of a diacid dithienylethene compound. Photoisomerisation between the open and closed isomers was investigated by UV/visible and 1H NMR spectroscopy. It was found that the photocyclisation quantum yield of the diacid form was remarkably high (around 90 %). Partial neutralisation of the open isomer revealed a gated photochromism as the photocyclisation quantum yield of the mono‐ and dianion were 50 and 67 %, respectively. A considerable photomodulation of the acidity was observed: the closed isomer is more acid than the open one by more than one pKa unit. This effect has been shown to be exploitable for a reversible photo‐acid generation. This is the first time that a complete quantitative investigation that allows for the determination of the main photochromic, spectral and thermodynamic parameters of a base‐sensitive photochromic diarylethene has been carried out.
High‐Throughput Bioprocess Development in Shaken Microbioreactors
Authors: Wenk Pamela , Hemmerich Johannes , Müller Carsten , Kensy Frank 
Published: April 2012

AbstractDer effiziente Betrieb von Fermentationsprozessen spielt eine entscheidende Rolle für den Erfolg der modernen Biotechnologie. Neu konzipierte Mikrotiterplatten mit blumenförmigen Wells (Flowerplate) und integrierter Online‐Sensorik bieten Möglichkeiten bereits in einem sehr frühen Stadium der Bioprozessentwicklung ein tieferes Prozessverständnis zu erhalten. Die zusätzliche Automatisierung der Stofftransfer‐optimierten Flowerplates im RoboLector birgt weiteres Potenzial zur systematischen, hochparallelen Untersuchung von Bioprozessen und kann entscheidend zur Verkürzung von Entwicklungszeiten beitragen. Der Artikel liefert eine Übersicht über den Stand der Technik von geschüttelten Mikrobioreaktoren mit Online‐Sensorik und deren Automatisierung.
Metal‐Free and Fluorescent Diketopyrrolopyrrole Fluorophores for Dye‐Sensitized Solar Cells
Authors: Hablot Delphine , Islam Ashraful , Han Liyuan , Ziessel Raymond 
Published: April 2012

AbstractNovel metal‐free and fluorescent dipyrrolopyrrole (DPP) dyes consisting of a central bis(lactam)‐bearing pendent benzyl or branched hydrocarbon groups as solubilizing fragments and two orthogonal side arms (dimethylaminopropyne and benzoate anion) have been designed and synthesized. The UV/Vis absorption spectra recorded in THF are dominated by intense low‐energy π–π* absorptions centered at 488 nm or 602 nm, respectively, for the phenyl‐ or thiophene‐based DPP dyes. The fluorescence spectra also display broad bands at 555 nm (ΦF=0.57 and τF=4.6 ns) for the phenyl‐ and at 624 nm (ΦF=0.31 and τF=3.5 ns) for the thiophene‐based molecular structures. Under standard global AM 1.5G irradiation a maximum photon‐to‐electron conversion efficiency of 2.54 % was achieved with dye‐sensitized solar cells based on nanocrystalline TiO2 (Jsc=7.5 mA cm−2, Voc=0.49 V, and FF=0.70) for the phenyl‐based DPP dye and 1.89 % (Jsc=7.1 mA cm−2, Voc=0.41 V, and FF=0.65) for the thiophene‐based DPP dye.
Development of CAD tools for nanomagnetic logic devices
Authors: Csaba György , Becherer Markus , Porod Wolfgang 
Published: April 2012

ABSTRACTSingle‐domain models are widely used for the approximate description of nanoscale magnetic switching. The goal of this article is to demonstrate them as a computationally efficient and physically established tool for the modeling and design of nanomagnetic logic (NML) devices. We introduce a systematic method for deriving single‐domain parameters from numerical magnetic field calculations and investigate the validity of the single‐domain description for lithographically fabricated nanomagnets in the sub‐100‐nm size range. We illustrate how a library of NML building blocks can be constructed and aid the design of complex circuitry. It will be demonstrated how single‐domain models can be used to understand error formation in NML structures. The methods described here serve as a theoretical framework for a Simulation Program with Integrated Circuit Emphasis (SPICE)‐like modeling tool for NML devices. Copyright © 2012 John Wiley & Sons, Ltd.
Uncontrolled admixture and loss of genetic diversity in a local Vietnamese pig breed
Authors: Berthouly‐Salazar Cécile , Thévenon Sophie , Van Thu Nhu , Nguyen Binh Trong , Pham Lan Doan , Chi Cuong Vu , Maillard Jean‐Charles 
Published: April 2012

AbstractThe expansion of intensive livestock production systems in developing countries has increased the introduction of highly productive exotic breeds facilitating indiscriminate crossbreeding with local breeds. In this study, we set out to investigate the genetic status of the Vietnamese Black H’mong pig breed by evaluating (1) genetic diversity and (2) introgression from exotic breeds. Two exotic breeds, namely Landrace and Yorkshire used for crossbreeding, and the H’mong pig population from Ha Giang (HG) province were investigated using microsatellite markers. Within the province, three phenotypes were observed: a White, a Spotted and a Black phenotype. Genetic differentiation between phenotypes was low (0.5–6.1%). The White phenotypes showed intermediate admixture values between exotic breeds and the Black HG population (0.53), indicating a crossbreed status. Management practices were used to predict the rate of private diversity loss due to exotic gene introgressions. After 60 generations, 100% of Black private alleles will be lost. This loss is accelerated if the admixture rate is increased but can be slowed down if the mortality rate (e.g., recruitment rate) is decreased. Our study showed that a large number of markers are needed for accurately identifying hybrid classes for closely related populations. While our estimate of admixture still seems underestimated, genetic erosion can occur very fast even through indiscriminate crossbreeding.
Environmental Monitoring and Enforcement in Europe: A Review of Empirical Research
Authors: Tosun Jale 
Published: April 2012

ABSTRACTEnvironmental concerns have been moving up on the agendas of policy makers in industrialized states, mostly involving debates about the stringency of environmental regulation. There are, however, two sides to environmental regulation that deserve attention. On the one side, there are factors that affect the definition of environmental law. On the other side, laws cannot clean up the environment unless they are properly monitored and enforced by governments and their responsible agencies. Comparatively scant attention has been paid by political scientists to this latter aspect. This article addresses the issue of environmental monitoring and enforcement and reviews the empirical research on European states. While there is some promising research on individual states, cumulative knowledge is hampered by the limited number of comparative empirical assessments. The main reason for this deficit, however, can be seen in difficulties regarding measurement and data availability. Inspired by the reviewed literature, the article suggests a measurement that takes into account changes in the legal competences of the agencies responsible, which might be helpful in overcoming the impediment to comparative analysis. Yet improving our insights by means of comparison is only one of several points that constitute the research agenda with respect to the study of environmental monitoring and enforcement in Europe. Thus, another contribution of this article is the identification of promising avenues for future research. Copyright © 2012 John Wiley & Sons, Ltd and ERP Environment
FeCl3·6H2O and TfOH as Catalysts for Allylic Amination Reaction: A Comparative Study
Authors: Trillo Paz , Baeza Alejandro , Nájera Carmen 
Published: April 2012

AbstractThe use of FeCl3·6H2O and TfOH as readily available and easy‐to‐handle catalysts for the direct allylic amination reaction using a wide variety of nitrogenated nucleophiles onto different free allylic alcohols is described. Comparative studies between these catalysts, as representative Lewis and Brønsted acids are conducted, concluding that both are suitable catalysts for this transformation. The reactions are performed in a flask open to air and using technical grade 1,4‐dioxane. In light of the results obtained from this study it can be asserted that TfOH turned out to be slightly superior than the FeIII salt since similar or better yields are obtained in most of the cases using lower catalyst loadings and milder reaction conditions. A similar trend is observed when carbonucleophiles were employed in the allylic substitution reaction. Studies for the elucidation of the reaction mechanism are in agreement with a carbocationic intermediate, being the regioselectivity governed by the stability of the final product.
Palladium‐Catalyzed Amidation and Amination of 8‐Iodopurine
Authors: Chevot Franciane , Vabre Roxane , Piguel Sandrine , Legraverend Michel 
Published: April 2012

AbstractThe synthesis of 8‐amido‐ and 8‐aminopurines by a single palladium‐catalyzed protocol is reported. The method proceeds efficiently and tolerates a wide range of amides and amines as coupling partners, including aryl, alkyl, sulfone, and acetal amides, as well as deactivated m‐ and p‐nitroanilines. In this way, a library of new 6,8,9‐trisubstituted purines has been synthesized.