Characterization of Sr1–xDyxCoO3–δ (x = 0.1, 0.2, 0.3) Cathode Materials for IT‐SOFCs

The cobaltate perovskites Sr_1–xDy_xCoO_3–δ (SDCO, x = 0.1, 0.2, 0.3) materials were synthesized and evaluated as cathode for La_0.8Sr_0.2Ga_0.8Mg_0.2O_3–δ solid electrolyte supported intermediate‐temperature‐solid oxide fuel cells (IT‐SOFCs). The crystal structure of Sr_0.9Dy_0.1CoO_3–δ was defined in the cubic Pm–3m space group (No. 221), Sr_0.8Dy_0.2CoO_3–δ and Sr_0.7Dy_0.3CoO_3–δ had a tetragonal I4/mmm structure. The electrical conductivities were all higher than 100 S cm^–1 in the temperature of 170–800 °C. The polarization resistance (R_p) and its activation energy (E_a) increased with increasing x. SEM analysis confirmed the porous microstructure of the SDCO cathodes and good LSGM|LDC|SDCO adherence. Sr_0.9Dy_0.1CoO_3–δ exhibited the best cathode characteristics with a maximum test‐cell power density of 841 mW cm^–2, being a high potential candidate of cathode material for IT‐SOFCs.     

Electrical Conductivity Improvement of Nd2Ce2O7 Ceramic Co‐doped with Gd2O3 and ZrO2

(Nd_1–xGd_x)₂(Ce_1–xZr_x)₂O₇ (0 ≤ x ≤ 0.5) ceramic powders synthesised by the chemical‐coprecipitation and calcination method were pressureless‐sintered at 1,973 K for 10 h in air. The structure and electrical conductivity of (Nd_1–xGd_x)₂(Ce_1–xZr_x)₂O₇ ceramics were investigated by the X‐ray diffraction and impedance spectroscopy measurements. (Nd_1–xGd_x)₂(Ce_1–xZr_x)₂O₇ (0 ≤ x ≤ 0.5) ceramics exhibit a single phase of defect fluorite‐type structure. The electrical conductivity of (Nd_1–xGd_x)₂(Ce_1–xZr_x)₂O₇ ceramics increases with temperature in the range 623–1,173 K following an Arrhenius law. At identical temperature levels, the measured electrical conductivity of (Nd_1–xGd_x)₂(Ce_1–xZr_x)₂O₇ ceramics varies with doping different Gd₂O₃ and ZrO₂ contents and exhibits a maximum at x = 0.1.     

Synthesis of monodisperse CeO2–ZrO2 particles exhibiting cyclic superelasticity over hundreds of cycles

Nano‐ and microscale CeO₂–ZrO₂ (CZ) shape memory ceramics are promising materials for smart micro‐electro‐mechanical systems (MEMS), sensing, actuation and energy damping applications, but the processing science for scalable production of such small volume ceramics has not yet been established. Herein, we report a modified sol‐gel method to synthesize highly monodisperse spherical CZ particles with diameters in the range of ~0.8‐3.0 μm. Synchrotron X‐ray micro‐diffraction (μSXRD) confirmed that most of the particles are single crystal after annealing at 1450°C. Having a monocrystalline structure and a small specimen length scale, the particles exhibit significantly enhanced shape memory and superelasticity properties with up to ~4.7% compression being completely recoverable. Highly reproducible superelasticity through over five hundred strain cycles, with dissipated energy up to ~40 MJ/m³ per cycle, is achieved in the CZ particles containing 16 mol% ceria. This cycling capability is enhanced by ten times compared with our first demonstration using micropillars (only 50 cycles in Lai et al, Science, 2013, 341, 1505). Furthermore, the effects of cycling and testing temperature (in 25°C‐400°C) on superelasticity have been investigated.     

Gold‐Catalyzed 5‐ and 6‐exo‐dig Selective Cyclizations of Alkynyl Silyl Enol Ethers: Efficient Method for [3+2] and [4+2] Annulations onto α,β‐Enones

An efficient method for the annulation of five‐ and six‐membered rings onto α,β‐enones is described via gold‐catalyzed 5‐ and 6‐exo‐dig selective cyclizations of alkynyl silyl enol ethers.     

Synthesis of Substituted 2,2′‐Bipyridines and 2,2′:6′,2′′‐Terpyridines by Cobalt‐Catalyzed Cycloaddition Reactions of Nitriles and α,ω‐Diynes with Exclusive Regioselectivity

A variety of substituted 2,2′‐bipyridines were synthesized by a 1,2‐bis(diphenylphosphino)ethane (dppe)/cobalt chloride hexahydrate (CoCl₂⋅6 H₂O)/zinc‐catalyzed [2+2+2] cycloaddition reaction of diynes and nitriles, with all reactions exhibiting exclusive regioselectivity. Thus, symmetrical and unsymmetrical 1,6‐diynes and 2‐cyanopyridine reacted in the presence of 5 mol % of dppe, 5 mol % of CoCl₂⋅6 H₂O and 10 mol % of zinc powder to provide the corresponding 2,2′‐bipyridines. Under identical reaction conditions, 1‐(2‐pyridyl)‐1,6‐diynes and nitriles reacted smoothly with exclusive regioselectivity to produce 2,2′‐bipyridines in good yield. 2,2′‐Bipyridines were also obtained by the double [2+2+2] cycloaddition reaction of 1,6,8,13‐tetraynes with nitriles. Similarly, 2,2′:6′,2′′‐terpyridines were synthesized from 1‐(2‐pyridyl)‐1,6‐diyne and 2‐cyanopyridine. The regiochemistry observed can be explained by considering the electronic nature of cobaltacyclopentadiene intermediates and nitriles. A survey of the exclusive regiochemical trend gives reasonable credence to the synthetic potential of the present method.     

Oxygen‐Involved Oxidative Deacetylation of α‐Substituted β‐Acetyl Amides – Synthesis of α‐Keto Amides

α‐Substituted β‐acetyl amides could undergo C C bond cleavage to form α‐keto amides when treated with copper(II) chloride (CuCl₂) and boron trifluoride diethyl etherate (BF₃⋅OEt₂) under an oxygen atmosphere. The yield can be increased by the addition of tert‐butyl hydroperoxide which alone can also effect the reaction. The reaction provides a new protocol for the synthesis of α‐keto amides.

     

Mechanical Properties and Reliability of Li2O‐Stabilized β″‐Alumina Ceramics: Effect of Synthesizing Method

Li₂O‐stabilized β″‐alumina powder has been synthesized by the solid‐state and double‐zeta processes. It was shown that by the double‐zeta process, the β″‐alumina fraction of sintered samples was 10% higher, showing around 99% of β″‐alumina fraction. Using β″‐alumina powder produced by the double‐zeta process, the sintered density improved, microstructure was more uniform and leads to improvement in hardness, strength and Weibull modulus due to more uniform microstructure and absence of abnormal grain growth. The higher fracture toughness of the solid‐state‐processed samples could be due to crack deflection mechanism.     

2‐Naphthol‐containing β‐cyclodextrin–epichlorohydrin copolymers: synthesis,characterization and fluorescence studies

Fluorescent 2‐naphthol (NOH)‐containing β‐cyclodextrin (β‐CD)–epichlorohydrin (EP) copolymers were synthesized. Polymerization was confirmed through viscosity and FT‐IR spectroscopic measurements. Under certain conditions, the copolymers were water‐soluble (molar ratio of EP/β‐CD <22:1), while under other conditions water‐insoluble gels were formed (EP/β‐CD ≥ 22:1). Increase of the EP content to EP/β‐CD ≤ 39:1 increased the fluorescence intensity of the copolymer and shifted the emission maximum from 422 nm toward 352 nm (measured at pH ≥ 12). Further increases in the EP content resulted in a slight decrease in the fluorescence intensity. The fluorescence properties of our system at EP/β‐CD < 22 were sensitive to pH variation, while at EP/β‐CD ≥ 22 no pH effect was observed. These variations can be explained in terms of the exposure of the fluorophore to solvent in soluble versus insoluble polymers, as well as changes in the mode of association (host–guest complexation, trapping within the polymer network, covalent bonding, etc) of NOH with the polymers. Crystallographic studies on a single crystal grown in the absence of EP, but under basic conditions, suggest that host–guest complexation is not an important mode for NOH incorporation. Copyright © 2005 Society of Chemical Industry     

Design,Synthesis, and Biological Evaluation of Tetrahydro‐β‐carboline Derivatives as Selective Sub‐Nanomolar Gelatinase Inhibitors

Targeting matrix metalloproteinases (MMPs) is a pursued strategy for treating several pathological conditions, such as multiple sclerosis and cancer. Herein, a series of novel tetrahydro‐β‐carboline derivatives with outstanding inhibitory activity toward MMPs are present. In particular, compounds 9 f , 9 g , 9 h and 9 i show sub‐nanomolar IC₅₀ values. Interestingly, compounds 9 g and 9 i also provide remarkable selectivity toward gelatinases; IC₅₀=0.15 nm for both toward MMP‐2 and IC₅₀=0.63 and 0.58 nm , respectively, toward MMP‐9. Molecular docking simulations, performed by employing quantum mechanics based partial charges, shed light on the rationale behind binding involving specific interactions with key residues of S1′ and S3′ domains. Taken together, these studies indicate that tetrahydro‐β‐carboline represents a promising scaffold for the design of novel inhibitors able to target MMPs and selectively bias gelatinases, over the desirable range of the pharmacokinetics spectrum.     

Flame Spray Synthesis of Nanoscale La0.6Sr0.4Co0.2Fe0.8O3–δ and Ba0.5Sr0.5Co0.8Fe0.2O3–δ as Cathode Materials for Intermediate Temperature Solid Oxide Fuel Cells

Electrochemical performance and degradation was analysed by conductivity measurements as well as thermogravimetric analysis (TGA) under different atmospheres. CO₂ was identified as a critical parameter in terms of carbonate formation from Ba_0.5Sr_0.5Co_0.8Fe_0.2O_3–δ and causes a strong increase in the material resistivity, whereas La_0.6Sr_0.4Co_0.2Fe_0.8O_3–δ is unaffected. The oxygen exchange kinetic of both compositions is affected by CO₂ containing atmospheres.     

Microbial production,immobilization and applications of β‐D‐galactosidase

β‐D ‐Galactosidase (β‐D ‐galactoside galactohydrolase, E.C. 3.2.1.23), most commonly known as lactase, is one of the most important enzymes used in food processing, which catalyses the hydrolysis of lactose to its constituent monosaccharides, glucose and galactose. The enzyme has been isolated and purified from a wide range of microorganisms but most commonly used β‐D ‐galactosidases are derived from yeasts and fungal sources. The major difference between yeast and fungal enzyme is the optimum pH for lactose hydrolysis. The application of β‐D ‐galactosidase for lactose hydrolysis in milk and whey offers nutritional, technological and environmental applications to human life. In this review, the main emphasis has been given to elaborate the various techniques used in recent times for the production, purification, immobilization and applications of β‐D ‐galactosidase. Copyright © 2006 Society of Chemical Industry     

Synthesis,Structure–Activity,and Structure–Stability Relationships of 2‐Substituted‐N‐(4‐oxo‐3‐oxetanyl) N‐Acylethanolamine Acid Amidase (NAAA) Inhibitors

N‐Acylethanolamine acid amidase (NAAA) is a cysteine amidase that preferentially hydrolyzes saturated or monounsaturated fatty acid ethanolamides (FAEs), such as palmitoylethanolamide (PEA) and oleoylethanolamide (OEA), which are endogenous agonists of nuclear peroxisome proliferator‐activated receptor‐α (PPAR‐α). Compounds that feature an α‐amino‐β‐lactone ring have been identified as potent and selective NAAA inhibitors and have been shown to exert marked anti‐inflammatory effects that are mediated through FAE‐dependent activation of PPAR‐α. We synthesized and tested a series of racemic, diastereomerically pure β‐substituted α‐amino‐β‐lactones, as either carbamate or amide derivatives, investigating the structure–activity and structure–stability relationships (SAR and SSR) following changes in β‐substituent size, relative stereochemistry at the α‐ and β‐positions, and α‐amino functionality. Substituted carbamate derivatives emerged as more active and stable than amide analogues, with the cis configuration being generally preferred for stability. Increased steric bulk at the β‐position negatively affected NAAA inhibitory potency, while improving both chemical and plasma stability.     

Synthesis,Structure–Activity Relationship Studies,and ADMET Properties of 3‐Aminocyclohex‐2‐en‐1‐ones as Chemokine Receptor 2 (CXCR2) Antagonists

Herein we describe the synthesis and structure–activity relationships of 3‐aminocyclohex‐2‐en‐1‐one derivatives as novel chemokine receptor 2 (CXCR2) antagonists. Thirteen out of 44 derivatives were found to inhibit CXCR2 downstream signaling in a Tango assay specific for CXCR2, with IC₅₀ values less than 10 μm . In silico ADMET prediction suggests that all active compounds possess drug‐like properties. None of these compounds show significant cytotoxicity, suggesting their potential application in inflammatory mediated diseases. A structure–activity relationship (SAR) map has been generated to gain better understanding of their binding mechanism to guide further optimization of these new CXCR2 antagonists.     

2′‐Bispyrene‐Modified 2′‐O‐Methyl RNA Probes as Useful Tools for the Detection of RNA: Synthesis,Fluorescent Properties,and Duplex Stability

The synthesis and properties two series of new 2′‐O‐methyl RNA probes, each containing a single insertion of a 2′‐bispyrenylmethylphosphorodiamidate derivative of a nucleotide (U, C, A, and G), are described. As demonstrated by UV melting studies, the probes form stable complexes with model RNAs and DNAs. Significant increases (up to 21‐fold) in pyrene excimer fluorescence intensity were observed upon binding of most of the probes with complementary RNAs, but not with DNAs. The fluorescence spectra are independent of the nature of the modified nucleotides. The nucleotides on the 5′‐side of the modified nucleotide have no effect on the fluorescence spectra, whereas the natures of the two nucleotides on the 3′‐side are important: CC, CG, and UC dinucleotide units on the 3′‐side of the modified nucleotide provide the maximum increases in excimer fluorescence intensity. This study suggests that these 2′‐bispyrene‐labeled 2′‐O‐methyl RNA probes might be useful tools for detection of RNAs.     

Synthesis,characterization, and degradation investigation of water‐soluble β‐cyclodextrin‐based epoxy resins

A series of β‐cyclodextrin‐based epoxy resins were synthesized with different epoxy equivalent weights. Their chemical structures were characterized with Fourier Transform Infrared Spectroscopy (FTIR) and Nuclear Magnetic Resonance Spectroscopy (NMR) examination. These epoxy resins were cured using L ‐arginine as a curing agent, and the degradation behavior of the cured resins was evaluated under different acidic buffer solutions at 37°C. The degradable behavior of such epoxy resins suggested potential applications as environment friendly materials. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Fluorine‐Containing 6,7‐Dialkoxybiaryl‐Based Inhibitors for Phosphodiesterase 10 A: Synthesis and in vitro Evaluation of Inhibitory Potency,Selectivity, and Metabolism

Based on the potent phosphodiesterase 10 A (PDE10A) inhibitor PQ‐10, we synthesized 32 derivatives to determine relationships between their molecular structure and binding properties. Their roles as potential positron emission tomography (PET) ligands were evaluated, as well as their inhibitory potency toward PDE10A and other PDEs, and their metabolic stability was determined in vitro. According to our findings, halo‐alkyl substituents at position 2 of the quinazoline moiety and/or halo‐alkyloxy substituents at positions 6 or 7 affect not only the compounds′ affinity, but also their selectivity toward PDE10A. As a result of substituting the methoxy group for a monofluoroethoxy or difluoroethoxy group at position 6 of the quinazoline ring, the selectivity for PDE10A over PDE3A increased. The same result was obtained by 6,7‐difluoride substitution on the quinoxaline moiety. Finally, fluorinated compounds (R)‐7‐(fluoromethoxy)‐6‐methoxy‐4‐(3‐(quinoxaline‐2‐yloxy)pyrrolidine‐1‐yl)quinazoline ( 16 a ), 19 a – d , (R)‐tert‐butyl‐3‐(6‐fluoroquinoxalin‐2‐yloxy)pyrrolidine‐1‐carboxylate ( 29 ), and 35 (IC₅₀ PDE10A 11–65 nM ) showed the highest inhibitory potential. Further, fluoroethoxy substitution at position 7 of the quinazoline ring improved metabolic stability over that of the lead structure PQ‐10.     

Retraction: Copper‐Catalyzed Cascade Reaction for Practical and Efficient Synthesis of Alkyl 2H‐Isoindole‐1‐carboxylates

The above article in Advanced Synthesis & Catalysis, published online on December 8, 2011, in Wiley Online Library (onlinelibrary.wiley.com), and in print Volume 353, Issue 18, 2011, pages 3330–3334 (DOI: 10.1002/adsc.201100451 ), has been retracted by agreement between the authors, the journal Editor, Joe P. Richmond, and Wiley‐VCH Verlag GmbH & Co. KGaA. The retraction has been agreed to for the following reasons. As determined by X‐ray analysis carried out by Jérôme Thibonnet and co‐workers, Université François Rabelais, Tours, the products reported are not isoindoles, but rather the corresponding indoles. The reaction mechanism reported is therefore also incorrect.     

Cost‐effective Synthesis of α‐LiAlO2 Powders for Molten Carbonate Fuel Cell Matrices

Lithium aluminate (α‐/β‐LiAlO₂) particles were fabricated using three methods. The first method used organic glycerin and triethylene glycol which functioned as a catalyst for fabrication of α‐LiAlO₂ particles with Al(OH)₃ and LiOH·H₂O as the starting materials. As a result of the heat‐treatment of the starting materials, α‐/β‐LiAlO₂ particles could be obtained. The amount of α‐LiAlO₂ particles in α‐/β‐LiAlO₂ increased slightly as more organics were added. Additionally, when synthesised α‐/β‐LiAlO₂ particles were heat‐treated in a CO₂ gas flow, β‐LiAlO₂ was partially transformed to α‐LiAlO₂. In the second method, molten salts (Li₂/Na₂/K₂CO₃) were used as a catalyst to fabricate α‐LiAlO₂ as a major phase, however, this method requires a washing process which can produce unexpected impurities. In the third method, pure α‐LiAlO₂ was obtained by heat‐treatment of cheap sources such as Li₂CO₃ and Al(OH)₃ at 600–800 °C. The mean particle size (604 nm–11.85 μm) and the specific surface area (3.22–11.4 m² g^–1) of α‐LiAlO₂ were suitable for reinforcing the matrix and tape casting. Lastly, this study examined the effect of CO₂ for the synthesising of α‐LiAlO₂ particles.     

Enantioselective Synthesis of Highly Functionalized Trifluoromethyl‐Bearing Cyclopentenes: Asymmetric [3+2] Annulation of Morita–Baylis–Hillman Carbonates with Trifluoroethylidenemalonates Catalyzed by Multifunctional Thiourea‐Phosphines

On the basis of the design and synthesis of multifunctional thiourea‐phosphines, a catalytic method for the asymmetric [3+2] annulation of Morita–Baylis–Hillman carbonates with trifluoroethylidenemalonates has been developed, affording highly functionalized trifluoromethyl‐bearing cyclopentenes in excellent yields, high diastereoselectivities and enantioselectivities under mild conditions.