bluuebunny/crossref_metadata_2025_split huggingface dataset:
Enantioselective Oxidation of Alkenylbenzoates Catalyzed by Chiral Hypervalent Iodine(III) To Yield 4‐Hydroxyisochroman‐1‐ones
Authors: Shimogaki Mio , Fujita Morifumi , Sugimura Takashi 
Published: October 2013

AbstractIn this study, the enantioselective oxylactonization of ortho‐alk‐1‐enylbenzoates with chiral hypervalent iodine(III) reagents yielded 3‐alkyl‐4‐hydroxyisochroman‐1‐ones with high enantiomeric purity (ca. 90 % ee). The enantioselective oxidation was also performed under catalytic conditions, in which a catalytic amount (10 mol‐%) of a chiral iodoarene was oxidized to the hypervalent iodine species in situ using a stoichiometric co‐oxidant, m‐chloroperbenzoic acid (mCPBA). The catalytic oxidation mediated by chiral hypervalent iodine(III) species yielded enantiocontrolled syn products, while the direct oxidation of the substrate with mCPBA occurred as background oxidation to give racemic anti products. Under optimized conditions, the catalytic oxylactonization led to high levels of enantioselectivity (ca. 90 % ee) and improved syn/anti selectivities (ca. 80 % syn). The product distribution indicated that the lactate side‐chain on the chiral iodoarene precatalyst plays an important role in enhancing both the enantioselectivity and the catalytic efficiency in the oxylactonization.
BF3·OEt2‐Promoted Tandem O‐Arylation/Hydroxylation: Efficient Synthesis of 2‐Hydroxyflavanones from Triazenylaryl‐Substituted Diketones
Authors: Chen Zhengkai , Yang Weijun , Xu Lijun , Zhang Lili , Miao Maozhong , Ren Hongjun 
Published: October 2013

AbstractA transition‐metal‐free tandem O‐arylation/hydroxylation approach has been developed for the efficient synthesis of highly substituted 2‐hydroxyflavanones from triazenylaryl‐substituted diketones. The intermediate benzopyrylium cation may be involved in these reactions.
Ruthenium‐Catalyzed Transfer Hydrogenation of Amino‐ and Amido‐Substituted Acetophenones
Authors: Watson Andrew J. A. , Fairbanks Antony J. 
Published: October 2013

AbstractThe ruthenium‐catalyzed transfer hydrogenation of electron‐rich amino‐substituted acetophenones is reported. Variation of the reductant, ligands, base, and solvent allowed reaction optimization. A key discovery was the use of 1,4‐butanediol as an irreversible reducing agent, which significantly improved the conversion. A range of amino‐ and amido‐substituted aryl ketones were explored, and they all gave the corresponding alcohols in good yield, which demonstrates the wider applicability of this process.
Total Synthesis of the Neuronal Cell‐Protecting Carbazole Alkaloids Carbazomadurin A and (S)‐(+)‐Carbazomadurin B
Authors: Hieda Yuhzo , Choshi Tominari , Fujioka Haruto , Hibino Satoshi 
Published: October 2013

AbstractThe total syntheses of the neuronal cell‐protecting carbazole alkaloids carbazomadurin A and (S)‐(+)‐carbazomadurin B were achieved. The key step of the synthesis of the polysubstituted carbazole rings included an allene‐mediated electrocyclic reaction of the 6π‐electron system that involved the indole 2,3‐bond. The cleavage of the alkoxy groups of the resulting 3‐ethoxy‐8‐isopropoxycarbazole successfully gave the 3,8‐dihydroxycarbazole, which was converted into the 3,8‐bis(OSEM)‐carbazole (SEM = 2‐trimethylsilylethoxymethyl). A Suzuki–Miyaura cross‐coupling reaction of the 3,8‐bis(OSEM)‐carbazole with the corresponding alkenyl pinacol borates afforded the 1‐alkenylcarbazoles, which were treated with tetra‐n‐butylammonium fluoride (TBAF) followed by reduction with NaBH4 to provide carbazomadurin A and (S)‐(+)‐carbazomadurin B, respectively.
Constrained 3,6‐Anhydro‐Heptosides: Synthesis by a DAST‐Induced Debenzylative Reaction, and Reactivity Profile
Authors: Tikad Abdellatif , Vincent Stéphane P. 
Published: October 2013

AbstractWe report the first synthesis of a conformationally constrained 3,6‐anhydroheptoside analogue of D‐glycero‐D‐manno‐heptopyranose 7‐phosphate by a DAST (diethylaminosulfur trifluoride)‐induced intramolecular cycloetherification. The reactivity of a series of constrained bicyclic 3,6‐anhydro‐thioheptosides as glycosyl donors was also studied in glycosylation reactions and compared with the reactivities of related unconstrained mannose and heptose scaffolds. Competition experiments confirmed that in the D‐manno‐heptose series, a reversal of chair conformation leads to an enhancement of the anomeric reactivity.
Influence of 1,3‐Difluorobenzene Substituents for Palladium‐Catalyzed Direct Arylations
Authors: Yan Tao , Bheeter Charles Beromeo , Doucet Henri 
Published: October 2013

AbstractThe influence of electron‐withdrawing and electron‐donating substituents (nitro, nitrile, chloro, bromo, methoxy or amino) on 1,3‐difluorobenzenes in their palladium‐catalysed direct C2 arylation has been explored. With most substituents, the reaction proceeds nicely using air‐stable palladium catalysts (0.5–2 mol‐%) and KOAc/DMA. In general, very regioselective C2‐arylation was observed. Moreover, a variety of substituents on the aryl bromide coupling partner (ester, acetyl, formyl, nitro, nitrile, trifluoromethyl, chloro, fluoro or methyl) was tolerated.
Direct Electrochemistry and Electrocatalysis of Hemoglobin on Aligned Carbon Nanotubes Based Electrodes Modified with Au Nanoparticles and SiO2 Gel
Authors: Yang Jing , Xu Ying , He Pingang , Fang Yuzhi 
Published: October 2013

AbstractHere we report on the preparation and characterization of new electrodes based on aligned carbon nanotubes (ACNTs) for hemoglobin (Hb) electrochemistry and electrocatalysis. The ACNTs are obtained by a thermal chemical vapor deposition method under normal pressure. Then the electrodes are elaborated by first sputtering a thin Au film (thickness of 200 nm) onto the top of the ACNTs, and then removing the Au layer/ACNTs from the quartz substrate with the aide of hydrofluoric acid (HF) treatment. Field emission scanning electron microscopy (FESEM) demonstrates that after nitric acid (HNO3) treatment, the nanotubes of the removed Au layer are totally tip‐opened, purified and organized in a perfect vertically aligned architecture. The final ACNTs electrode is obtained by attaching the Au layer of ACNTs onto a glassy carbon electrode. Then the electrode was modified to act as a matrix for hemoglobin (Hb) immobilization and as an electrode for Hb electroanalysis by the assistance of Au nanoparticles (AuNPs) and SiO2 gel. Due to the individual specific effects of AuNPs, SiO2 gel and ACNTs, the resulting SiO2/Hb‐AuNPs/ACNTs electrode showed good direct electrochemistry of Hb with an apparent MichaelisMenten constant of 0.44 mM. The electrode showed an excellent electrocatalytic activity towards H2O2, possessing a linear range from 40 µM to 4 mM and the detection limit was 22 µM based on a signal to noise ratio of 3.
Highly Selective and Sensitive Determination of Dopamine in the Presence of Ascorbic Acid Using a 3D Graphene Foam Electrode
Authors: Huang Shuo , Yue Hongyan , Zhou Jin , Zhang Jianjiao , Zhang Chunyu , Gao Xin , Chang Jing 
Published: October 2013

AbstractA three‐dimensional (3D), macroporous and highly conductive graphene foam (GF) was synthesized by atmospheric pressure chemical vapor deposition (CVD). The morphologies of the GF were characterized by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The structure of the GF was investigated by X‐ray diffraction (XRD) and Raman spectroscopy. The GF prepared by CVD was then transferred onto ITO coated glass, acting as an electrode, to detect dopamine (DA) and ascorbic acid (AA) by electrochemical methods. The results show that the GF exhibits high selectivity for the detection of DA and AA. It also shows high sensitivity for detection of DA with the lower detection limits of ∼2.0 nM in the linear response up to ∼10 µM. This demonstrates the free‐standing GF provides a promising platform as a 3D biosensing material.
A Simple and Highly Sensitive Electrochemical Biosensor for microRNA Detection Using Target‐Assisted Isothermal Exponential Amplification Reaction
Authors: Yan Yurong , Zhao Dan , Yuan Taixian , Hu Jun , Zhang Decai , Cheng Wei , Zhang Wei , Ding Shijia 
Published: October 2013

AbstractA simple and highly sensitive electrochemical biosensor for microRNA (miRNA) detection was successfully developed by integrating a target‐assisted isothermal exponential amplification reaction (EXPAR) with enzyme‐amplified electrochemical readout. The binding of target miRNA with the immobilized linear DNA template generated a part duplex and triggered primer extension reaction to form a double‐stranded DNA. Then one of the DNA strands was cleaved by nicking endonuclease and extended again. The short fragments with the same sequence as the target miRNA except for the replacement of uridines and ribonucleotides with thymines and deoxyribonucleotides could be displaced and released. Hybridization of these released DNA fragments with other amplification templates and their extension on the templates led to target exponential amplification. Integrating with enzyme‐amplified electrochemical readout, the electrochemical signal decreases with the increasing target microRNA concentration. The method could detect miRNA down to 98.9 fM with a linear range from 100 fM to 10 nM. The fabrication and binding processes were characterized with cyclic voltammetry and electrochemical impedance spectroscopy. The specificity of the method allowed single‐nucleotide difference between miRNA family members to be discriminated. The established biosensor displayed excellent analytical performance toward miRNA detection and might present a powerful and convenient tool for biomedical research and clinic diagnostic application.
A Reservoir/Wellbore‐Coupling Model for the Pressure, Flow Rate, and Optimum Perforation Distribution in Gas Wells
Authors: Hu Jiancheng 
Published: October 2013

AbstractDue to the variation in pressure drawdown along a well, pressure drop can occur in a vertical well. Accurate prediction of the inflow performance for perforated vertical wells is of great significance to reservoir analysis and perforation optimization. Under steady‐state inflow, a reservoir/wellbore‐coupling model is proposed that combines a numerical reservoir model and a semianalytical wellbore model. One type of optimization problem is also established that considers the effects of perforation density on the productivity of a vertical well, for which the vertical‐well production is treated as an objective function. A number of experiments are presented demonstrating how the model could be used to obtain the optimum perforation distribution for infinite‐conductivity and finite‐conductivity wells.
Anaerobic codigestion of poultry manure and sewage sludge under solid‐phase configuration
Authors: Fierro Julio , Martínez Judith E. , Rosas Jose G. , Blanco Daniel , Gómez Xiomar 
Published: October 2013

Anaerobic digestion (AD) is an efficient technology for valorizing biomass. However, when considering livestock farm operation, the dilution of the biomass to be treated in a conventional anaerobic digester may not be a suitable alternative. Solid phase percolating system may circumvent this problem. These types of digestion systems require low volume of water, thus needing a smaller reactor. In this line, AD of poultry manure (PM) and primary sludge (PS) was studied in a percolating reactor with high‐solid content. The process was carried out in laboratory‐scale plant at mesophilic conditions.The addition of PS as cosubstrate in a 10:1 ratio of volatile solids (VS) improved biogas yield as well as VS removal. Two‐fold higher biogas production was observed with the addition of cosubstrate along with an increase from 46 to 64% in the removal of VS. The initial acidification of the percolate could be perfectly balanced by the high alkalinity of the system. Methane yield obtained from the codigestion experiment was 56.5 l CH4/kg VS while the digestion of PM resulted in a value of 24.6. The ammonium concentration values measured in the percolate did not reach inhibitory levels in spite of the high nitrogen content present in PM.© 2013 American Institute of Chemical Engineers Environ Prog, 33: 866–872, 2014
Modeling metal bioaccumulation and tissue distribution in killifish (Fundulus heteroclitus) in three contaminated estuaries
Authors: Dutton Jessica , Fisher Nicholas S. 
Published: October 2013

Abstract

The present study experimentally assessed the uptake, loss, and resulting tissue distribution of As(V), Cd, Cr(III), Hg(II), and methylmercury (MeHg) in killifish (Fundulus heteroclitus) following aqueous exposure in water collected from 3 contaminated field sites—Baltimore Harbor and Elizabeth River (Chesapeake Bay), and Mare Island (San Francisco Bay)—using a radiotracer technique. Uptake rate constants (L g−1 d−1) were highest for MeHg (0.370–0.781) and lowest for As (0.00028–0.00065). Loss rate constants (d−1) were highest for As (0.046–0.096) and lowest for MeHg (0.006–0.009). Tissue distribution data showed that MeHg was redistributed around the body throughout the 9-d depuration period, and drinking may be an uptake mechanism for Cd from the aqueous phase in higher-salinity water. The kinetic parameters calculated in the present study were entered into a bioaccumulation model to calculate the predicted body burden of each metal at steady state and the percentage body burden attributable to dietary exposure on a site-specific basis. Calculated body burdens varied between field sites for all metals except Cr. The predicted values for Cd, Hg(II), and MeHg matched independent field data from contaminated estuaries, indicating that the model can account for the major processes governing metal concentration in killifish. The diet accounted for &gt;97% of the body burden of Cd and MeHg and was the predominant exposure route for As and Cr. Environ Toxicol Chem 2014;33:89–101. © 2013 SETAC
Persistence of estrogenic activity in soils following land application of biosolids
Authors: Langdon Kate A. , Warne Michael S.t.J. , Smernik Ronald J. , Shareef Ali , Kookana Rai S. 
Published: October 2013

Abstract

Estrogenic compounds may enter the environment when biosolids are applied to land. In the present study, soil samples were collected over 4 mo from a field trial following addition of biosolids. The recombinant yeast estrogen screen bioassay identified estrogenic activity in the soil at all sampling times to concentrations up to 2.3 µg 17β-estradiol equivalency/kg. The present results indicate the potential for estrogenic compounds to persist in soil following biosolids application. Environ Toxicol Chem 2014;33:26–28. © 2013 SETAC
Food security: intensification of agriculture is essential, for which current tools must be defended and new sustainable technologies invented
Authors: Pickett John A. 
Published: October 2013

AbstractTo spare land for amenity use and to preserve natural habitats, including those for ecosystem services, food production must be intensified on land which is presently farmed. Current tools, such as pesticides, although largely unsustainable in that they require seasonal application, must be defended against the growth of legislated restrictions being imposed without recourse to scientific evidence. This is the only practical short‐term approach to increasing food production without taking more land for agriculture, but more sustainable approaches delivered via the seed must be invented, including by genetic modification (GM), in order to replace seasonal inputs in the future. Eventually, perennial arable crops will be needed, thereby replacing seasonal land preparation, but, for full benefits to be realized, all crop protection and nutrition will need to be delivered via the planting material. Governments, and particularly those in the EU, must embrace risk analysis in which advantages, as well as potential hazards, are accommodated. The precautionary principle is not an appropriate approach to the registration of new technologies for achieving food security in a world suffering both climate change and rapid population increase.
Simultaneous Determination of the Permeability of a Nafion Membrane to Formic Acid and Water
Authors: Dugas R. , Guay D. , Tavares A. C. 
Published: October 2013

AbstractThe simultaneous diffusion of formic acid and water through Nafion was measured for four formic acid concentration differentials (1–17.5 M) and for two counter‐ions in the membrane (H+ and Ba2+). An iterative method based on Fick's law is presented to calculate the volumes and concentrations of the solutions as a function of time. Besides the initial conditions, the input parameters are two diffusion coefficients, one of formic acid and one of water, which were adjusted to fit the experimental data. Once the difference in liquid fraction between the two types of membranes is taken into account, the diffusion coefficient of formic acid through Nafion appears independent of the nature of the counter‐ion and the conductivity of the formic acid solution. The diffusion coefficient of water is 10 times higher than the formic acid diffusion coefficient and is systematically lower in membranes in the Ba2+ form than in H+ form.
NAL phase in K‐rich portions of the lower mantle
Authors: Kato Chie , Hirose Kei , Komabayashi Tetsuya , Ozawa Haruka , Ohishi Yasuo 
Published: October 2013

AbstractThe stability of the K‐rich new aluminous (NAL) phase was examined on the join Na1.00Mg2.00Al4.80Si1.15O12‐K1.00Mg2.00Al4.80Si1.15O12 (Na100‐K100) up to 144 GPa by X‐ray diffraction in a laser‐heated diamond anvil cell. Single‐phase K100 and Na50K50 NAL were formed up to the lower mantle conditions, and the NAL phase coexisted with the calcium ferrite–type (CF) phase at 120 GPa and 2300 K for the Na75K25 bulk composition. This is a striking contrast to the K‐free (Na100) NAL that becomes unstable above 27 GPa at 1850 K, which suggests that potassium stabilizes NAL at significantly higher pressures. K‐rich NAL may host potassium in the lower mantle that contains K2O more than 0.09 wt %. In addition, the NAL phase likely formed owing to partial melting in the ultralow‐velocity zone or because of a basal magma ocean. Future seismological observations may clarify whether NAL is a radiogenic heat source above the core‐mantle boundary.
Tandem Hydroformylation/Reductive Amination of 3‐Allyl‐2‐methylquinazolin‐4(3H)‐one
Authors: El‐Badry Yaser A. , El‐Farargy Ahmed F. , Eilbracht Peter 
Published: October 2013

AbstractThe 3‐allyl‐2‐methylquinazolin‐4(3H)‐one (1), a model functionalized terminal olefin, was submitted to hydroformylation and reductive amination under optimized reaction conditions. The catalytic carbonylation of 1 in the presence of Rh catalysts complexed with phosphorus ligands under different reaction conditions afforded a mixture of 2‐methyl‐4‐oxoquinazoline‐3(4H)‐butanal (2) and α,2‐dimethyl‐4‐oxoquinazoline‐3(4H)‐propanal (3) as products of ‘linear’ and ‘branched’ hydroformylation, respectively (Scheme 2). The hydroaminomethylation of quinazolinone 1 with arylhydrazine derivatives gave the expected mixture of [(arylhydrazinyl)alkyl]quinazolinones 5 and 6, besides a small amount of 2 and 3 (Scheme 3). The tandem hydroformylation/reductive amination reaction of 1 with different amines gave the quinazolinone derivatives 7–10. Compound 10 was used to prepare the chalcones 11a and 11b and pyrazoloquinazolinones 12a and 12b (Scheme 4).
Two Novel Plumeran Indole Alkaloids Isolated from Aspidosperma cylindrocarpon (Apocynaceae)
Authors: Guimarães Heloisa A. , Vieira Ivo J. C. , Braz‐Filho Raimundo , Crotti Antônio E. M. , dos Almeida Vitor S. , de Paula Renata C. 
Published: October 2013

AbstractTwo novel indole alkaloids with plumeran skeleton, N‐benzoyl‐12‐demethoxycylindrocarine and N‐cinnamoyl‐12‐demethoxycylindrocarine (1 and 2, resp.), were isolated from the MeOH extract of the stem bark of Aspidosperma cylindrocarpon Müll.Arg. These compounds were obtained by high‐speed counter‐current chromatography, and their structures were elucidated on the basis of their NMR (1D and 2D) data. They were tested in vitro against chloroquine‐resistant strains of Plasmodium falciparum, and only 2 showed a weak activity (IC50 127.97 ng/ml with respect to the standard drug). Several other known compounds, comprising steroids, flavonoids, the rarely found atraric acid, as well as the previously reported alkaloid 3, were also isolated by conventional chromatographic techniques.
Novel Intramolecular Cyclization of 2‐(Buta‐1,3‐dienyl)benzyl Anions to 6,7(9)‐Dihydro‐5H‐benzocycloheptenyl Anions Leading to Successive Formation of 1,2‐Dihydrocyclopropa[a]naphthalenes
Authors: Saitoh Hisashi , Ijuin Hisako K. , Watanabe Nobuko , Matsumoto Masakatsu 
Published: October 2013

AbstractWhen treated with LiNiPr2 (LDA) at −78°, 1‐[(methylsulfanyl)methyl]‐2‐[(1Z,3E)‐4‐phenylbuta‐1,3‐dien‐1‐yl]benzene easily cyclized to form benzocycloheptenyl anion, which successively underwent intramolecular nucleophilic substitution to give a cyclopropanaphthalene. Similar LDA‐mediated cyclization also occurred for 4‐phenyl‐ or 4‐methyl‐substituted 1‐[2‐(methoxymethyl)phenyl]buta‐1,3‐dienes to furnish the corresponding benzocycloheptenes and cyclopropanaphthalenes. A 4‐tert‐butyl analog also underwent LDA‐mediated cyclization to give a benzocycloheptene, but not a cyclopropanaphthalene.
Metal‐Ion‐Binding Analogs of Ribonucleosides: Preparation and Formation of Ternary Pd2+ and Hg2+ Complexes with Natural Pyrimidine Nucleosides
Authors: Golubev Oleg , Lönnberg Tuomas , Lönnberg Harri 
Published: October 2013

AbstractFour metal‐ion‐binding nucleosides, viz. 2,6‐bis(1‐methylhydrazinyl)‐9‐(β‐D‐ribofuranosyl)‐9H‐purine (2a) and its N‐acetylated derivative, 2b, 2,4‐bis(3,5‐dimethyl‐1H‐pyrazol‐1‐yl)‐5‐(β‐D‐ribofuranosyl)pyrimidine (3), and 2,4‐bis(1‐methylhydrazinyl)‐5‐(β‐D‐ribofuranosyl)pyrimidine (4) have been synthesized. The ability of these nucleosides and the previously prepared 2,6‐bis(3,5‐dimethyl‐1H‐pyrazol‐1‐yl)‐9‐(β‐D‐ribofuranosyl)‐9H‐purine to form Pd2+‐ and Hg2+‐mediated complexes with uridine has been studied by 1H‐NMR spectroscopy. To obtain additional support for the interpretation of the NMR data, comparative measurements on the ternary‐complex formation between pyridine‐2,6‐dicarboxamide (5), pyrimidine nucleosides, and K2PdCl4 were carried out.
INTEGRATION AMONG EGYPTIAN GOVERNORATES TO OPTIMIZE IRRIGATION WATER USE UTILIZING WEIGHT GOAL PROGRAMMING TECHNIQUE
Authors: El‐Gafy Inas 
Published: October 2013

ABSTRACTEgypt has limited available water resources. One of the main targets of the national water resources and agricultural policies in Egypt is the optimal use of these scarce resources. The free cropping pattern policy applied in Egypt gives farmers the right to decide on the cultivated crops according to their own choice. Pollution of the environment and saving irrigation water do not really represent constraining factors for farmers in their decision. The main objective of this research is to investigate the consequences of applying addressed integration among the Egyptian governorates, in order to produce a cropping pattern that optimizes irrigation water use, while considering the viewpoints of farmers as well as decision‐makers. Moreover, a partially free cropping pattern policy is scrutinized through the study. A multi‐objective optimization approach utilizing the weight goal programming technique was applied to achieve the research. The results of the study illustrated that applying addressed integration among the Egyptian governorates and a partially free cropping pattern policy saves water, reduces cultivated area, lessens fertilizer usage, and increases the net return from crop production. Copyright © 2013 John Wiley & Sons, Ltd.