Fabrication and characterization of high performance cathode supported small-scale SOFC for intermediate temperature operation

A high performance small-scale solid oxide fuel cell supported by a microtubular cathode was successfully developed via the extrusion of a (La_0.8Sr_0.2)_0.97MnO₃ cathode support and subsequent surface coating with a (La_0.8Sr_0.2)_0.97MnO₃–Ce_0.9Gd_0.1O_1.95 activation layer followed by Sc₂O₃-doped ZrO₂ electrolyte and NiO–Ce_0.9Gd_0.1O_1.95 anode slurries. The cell was electrochemically evaluated in a humidified hydrogen (3% H₂O) atmosphere, and exhibited a stable open circuit voltage above 1.05 V in the temperature range from 550 to 750 °C. Maximum power densities of 46.5, 163.2 and 452.8 mW cm⁻² were generated at 550, 650 and 750 °C, respectively. The results indicate the realization of a stable and high performance cathode-supported micro SOFC.     

Preparation of ZnO/GO composite material with highly photocatalytic performance via an improved two-step method

ZnO/graphene oxide(ZnO/GO) composite material,in which ZnO nanoparticles were densely coated on the GO nanosheets,was successfully prepared by an improved two-step method and characterized by IR, XRD,TEM,and UV-vis techniques.The improved photocatalytic property of the ZnO/GO composite material,evaluated by the photocatalytic degradation of methyl orange(MO) under UV irradiation,is ascribed to the intimate contact between ZnO and GO,the enhanced adsorption of MO,the quick electron transfer from excited ZnO particles to GO sheets and the activation of MO molecules viaπ-πinteraction between MO and GO.     

Direct methane operation of a micro-tubular solid oxide fuel cell with a porous zirconia support

Journal of Solid State Electrochemistry - A novel micro-tubular solid oxide fuel cell (SOFC) design with an inert support was proposed for operation on direct hydrocarbon fuels with an improved...     

Development of an on-line sensor for bioreactor operation

Applied Biochemistry and Biotechnology -     

Reaction of o-oxazolinylphenyllithium with carbon monoxide. Carbonylative cyclization via an aroyllithium intermediate

The carbonylation of a phenyllithium containing an oxazoline group at the ortho position, followed by quenching with water, afforded a tricyclic compound, 3,3-dimethyl-2,3-dihydrooxazolo[2, 3-a]isoindol-5(9bH)-one, in 91% yield. This reaction proceeded via an intramolecular cyclization of the aroyllithium species, to give the tricyclic dienolate. Treatment of the tricyclic dienolate with electrophiles, such as alkyl halides, aldehydes, ketones, and epoxides gave the substituted oxazolo[2,3-a]isoindolinones in good yield.     

Development of novel low-temperature SOFCs with co-ionic conducting SDC-carbonate composite electrolytes

A series of ceria-based composite materials consisting of samaria doped ceria (SDC) and binary carbonates(Li₂CO₃–Na₂CO₃) were examined as functional electrolytes for low-temperature solid oxide fuel cells (SOFCs). DTA and SEM techniques were applied to characterize the phase- and micro-structural properties of the composite materials. Conductivity measurements were carried on the composite electrolytes with a.c. impedance in air. A transition of ionic conductivity with temperature was occurred among all samples with different carbonate content, which related to the interface phase. Single cells based on the composite electrolytes, NiO as anode and lithiated NiO as cathode, were fabricated by a simple dry-pressing process and tested at 400–600 °C. The maximum output power at 600 °C increased with the carbonate content in the composite electrolytes, and reached the maximum at 25 wt.%, then decreased. Similar trend has also shown at 500 °C, but the maximum was obtained at 20wt.%. The best performances of 1085 mW cm⁻² at 600 °C and 690 mW cm⁻² at 500 °C were achieved for the composite electrolytes containing 25 and 20 wt.% carbonates, respectively. During fuel cell operation, it found that the SDC-carbonate composites are co-ionic (O²⁻/H⁺) conductors. At lower carbonate contents, both oxide–ion and proton conductions were significant, when the content increased to 20–35 wt.%, proton conduction dominated. The detailed conduction mechanism in these composites needs further investigation.     

A regioselective etherification of pyridoxine via an ortho-pyridinone methide intermediate

The catalyst-free, regioselective synthesis of 4′-O-substituted pyridoxine derivatives under solventless conditions is described. The methodology relies on the highly regioselective formation of the ortho-pyridinone methide from pyridoxine and subsequent oxa-Michael addition of alcohol nucleophiles. This methodology provides good to excellent yields for primary and secondary alcohols and moderate yields for tertiary alcohols.     

Semiempirical hybrid functional with improved performance in an extensive chemical assessment

It is demonstrated that there is still scope for improvement in the quality of conventional, semiempirical hybrid exchange-correlation functionals in density-functional theory. A new functional, denoted B97-3, is determined from a fit to eight chemical properties (316 data points). For a series of 25 chemical assessments (850 data points) including 17 assessments and 10 chemical properties absent from the fitting data, B97-3 provides the lowest or joint-lowest mean absolute error on 15 occasions, compared to 6, 5, and 4 occasions for B3LYP, PBE0, and B97-2, respectively [A. D. Becke, J. Chem. Phys. 98, 5648 (1993); M. Ernzerhof and G. E. Scuseria, J. Chem. Phys. 110, 5029 (1999); C. Adamo and V. Barone, J. Chem. Phys. 110, 6158 (1999); P. J. Wilson, T. J. Bradley, and D. J. Tozer, J. Chem. Phys. 115, 9233 (2001)]. Mean absolute errors from B97-3 are, on average, 21%, 18%, and 12% smaller than from these three functionals. The most notable improvements are obtained for classical reaction barriers, where the error reductions are 60%, 54%, and 27%.     

The ensemble performance index: an improved measure for assessing ensemble pose prediction performance

We present a theoretical study on the performance of ensemble docking methodologies considering multiple protein structures. We perform a theoretical analysis of pose prediction experiments which is completely unbiased, as we make no assumptions about specific scoring functions, search paradigms, protein structures, or ligand data sets. We introduce a novel interpretable measure, the ensemble performance index (EPI), for the assessment of scoring performance in ensemble docking, which will be applied to simulated and real data sets.     

A new approach toward improved low temperature performance of Li-ion battery

We report a new approach toward formulating an electrolyte for low temperature operation of Li-ion batteries. The core of this new approach is to use LiBF₄ salt instead of LiPF₆, which is the chosen solute in the state-of-the-art Li-ion electrolytes. We found that although LiBF₄-based electrolyte has lower ionic conductivity than the LiPF₆ analogue, it provides improved low temperature performance. In particular, at −30 °C, a Li-ion cell with 1 m (mol/kg solvent) LiBF₄ dissolved in 1:1:3 (wt.) propylene carbonate (PC)/ethylene carbonate (EC)/ethylmethyl carbonate (EMC) mixed solvent delivers as high as 86% of capacity, in comparison to that obtained at 20 °C. Whereas the counterpart one, using LiPF₆, only retains 72%. Furthermore, the cell with LiBF₄-based electrolyte shows lower polarization at −30 °C. The above results suggest that the ionic conductivity of the electrolyte is not the only limitation to the low temperature operation of Li-ion batteries. Analysis of cell impedance reveals that the improved low temperature performance by LiBF₄ arises from a reduced charge-transfer resistance.     

High performance dual frequency liquid crystal compounds and mixture for operation at elevated temperature

Dual frequency liquid crystal (DFLC) compounds with high birefringence and ultra-low crossover frequency have been developed. The long conjugated rigid core structure gives these compounds a high birefringence (0.3–0.4) and ultra-low Debye relaxation frequency. Using these compounds we have formulated a new DFLC mixture, designated UCF–02, for operation at elevated temperatures. The birefringence of the mixture is greater than 0.3 at 25°C and λ = 633 nm. Their initial ultra-low crossover frequency allows them to be used at elevated temperatures and significantly improves their utility.     

Development of an online two-dimensional nano-scale liquid chromatography/mass spectrometry method for improved chromatographic performance and hydrophobic peptide recovery

An online two-dimensional (2D) strong cation-exchange (SCX)/reversed-phase (RP) nano-scale liquid chromatography/mass spectrometry (nanoLC/MS) method was developed for improved separation and hydrophobic peptide recovery. Sharper and more symmetric RP peaks were observed with the use of a "band re-focusing method", in which an analytical RP column with more hydrophobicity than the RP trap column was used in the system. To recover hydrophobic peptides still unreleased from the SCX column after a conventional salt step gradient due to hydrophobic interaction, a RP step gradient from 10% to 30% acetonitrile (ACN) was applied to the SCX column in the presence of a high salt concentration following the salt gradient. There were 301 unique hydrophobic E. coli peptides identified from the RP fractions. These peptides, which were 19% of all E. coli peptides identified from a 2D run, would not have been identified without the application of the RP gradient to the SCX column.     

The destabilization of hydrogen bonds in an external E-field for improved switch performance

The effect of an electric field on a recently proposed molecular switch based on a quinone analogue was investigated using next-generation quantum theory of atoms in molecules (QTAIM) methodology. The reversal of a homogenous external electric field was demonstrated to improve the “OFF” functioning of the switch. This was achieved by destabilization of the H atom participating in the tautomerization process along the hydrogen bond that defines the switch. The “ON” functioning of the switch, from the position of the tautomerization barrier, is also improved by the reversal of the homogenous external electric field: this result was previously inaccessible. The “ON” and “OFF” functioning of the switch was visualized in terms of the response of the most preferred directions of motion of the electronic charge density to the applied external field. All measures from QTAIM and the stress tensor provide consistent results for the factors affecting the “ON” and “OFF” switch performance. Our analysis therefore demonstrates use for future design of molecular electronic devices. © 2019 Wiley Periodicals, Inc.     

Development and validation of an improved algorithm for overlaying flexible molecules

A program for overlaying multiple flexible molecules has been developed. Candidate overlays are generated by a novel fingerprint algorithm, scored on three objective functions (union volume, hydrogen-bond match, and hydrophobic match), and ranked by constrained Pareto ranking. A diverse subset of the best ranked solutions is chosen using an overlay-dissimilarity metric. If necessary, the solutions can be optimised. A multi-objective genetic algorithm can be used to find additional overlays with a given mapping of chemical features but different ligand conformations. The fingerprint algorithm may also be used to produce constrained overlays, in which user-specified chemical groups are forced to be superimposed. The program has been tested on several sets of ligands, for each of which the true overlay is known from protein–ligand crystal structures. Both objective and subjective success criteria indicate that good results are obtained on the majority of these sets.     

Stepwise cope rearrangement of cyclo-biphenalenyl via an unusual multicenter covalent pi-bonded intermediate

Multicenter covalent pi-bonding between pi-conjugated radicals has been recently recognized as a novel and important bonding interaction. The Cope rearrangement of cyclo-biphenalenyl 9 is studied by exploring its potential energy surface with density functional theory (DFT), and it is found that pi-bonding plays a critical role in the rearrangement process. Affected by this, the rearrangement of 9 takes place by a stepwise mechanism through an unusual pi-intermediate 10, of C2h symmetry, which can be characterized as a 2 x 13pi + 2 x 2pi system. The pi-intermediate has a long inter-phenalenyl distance of R approximately 2.8 angstroms, which is shorter than the sum of the van der Waals radii displaying multicenter covalent pi-bonding between the two phenalenyl units. The energy of the pi-intermediate 10 is higher than that of the sigma-bonded reactant 9 by approximately 2 kcal/mol according to the employed spin-restricted DFT. NMR chemical shift calculations support the sigma-bonded 9 as the global minimum. The calculated activation barrier of approximately 6 kcal/mol for the Cope rearrangement is consistent with the stepwise mechanism. A covalent pi-bonding effect in the pi-intermediate 10 is demonstrated indirectly by the shortening of inter-naphthalene distance of the dianion and dication of the cyclophane 14 compared to that of its neutral counterpart. The unusual pi-bonded structure with a long inter-phenalenyl distance becomes the most stable structure for the ethano-bridged derivative 13, which should have observable paramagnetism according to the calculated paramagnetic susceptibility.     

Novel synthesis of 8-deaza-5,6,7,8-tetrahydroaminopterin analogues via an aziridine intermediate

An efficient method for the construction of the tetrahydrofolate skeleton is described. Starting from pterin analogues and aromatic amines, 8-deaza-5,6,7,8-tetrahydroaminopterin derivatives and the heterocyclic benzoyl isosteres were synthesized via a novel aziridine intermediate. Following this method, the byproducts of carbon-nitrogen bond hydrogenolysis in traditional synthetic strategy can be completely avoided.     

Thermal decay of TEMPO in acidic media via an N-oxoammonium salt intermediate

Disproportionation of TEMPO in acids leads to the formation of an N-oxoammonium salt, which can further decompose under thermal conditions, yielding the corresponding hydroxylamine, N(2)O, CO(2) and a series of dimerisation products. Overall, acid-catalysed thermal decay of TEMPO leads to ca. 80% yield of hydroxylamine.     

Development and performance of an automated HPLC-analyzer for catecholamines

Summary An automated, dual-column HPLC method has been developed that can be used routinely to quantify the parent catecholamines in body fluids. The method is based on a new, laboratory-prepared column material with size exclusion and high performance affinity chromatography properties. A microprocessor controlled column-switching technique is used with an optional integrated reaction-system for postcolumn derivatization for fluorescence detection. Natural fluorescence can be used for higher concentration levels. The commercially available analyzer allows, for the first time, the direct injection (up to 0.5 ml) of an appropriate biological fluid. In its integrated sample-processing mode, it exhibits, chemoselectivity and -specificity, with a detection limit of 2 pg, high precision and speed of analysis.     

Synthesis of an influenza neuraminidase inhibitor intermediate via a highly diastereoselective coupling reaction

[reaction: see text]. A highly diastereoselective coupling reaction between TBSOP (3) and trityl sulfenimine 4 was developed which provided influenza neuraminidase inhibitor intermediate 7 in 80% yield and >99% de after crystallization. The reaction was shown to be reversible with the high diastereoselectivity resulting from a favorable H-bonding interaction in the major diastereomer.