Hydrodeoxygenation of HMF over Pt/C in a continuous flow reactor

The three‐phase hydrodeoxygenation reaction of 5‐hydroxymethylfurfural (HMF) with H₂ was studied over a 10 wt % Pt/C catalyst using both batch and flow reactors, with ethanol, 1‐propanol, and toluene solvents. The reaction is shown to be sequential, with HMF reacting first to furfuryl ethers and other partially hydrogenated products. These intermediate products then form dimethyl furan (DMF), which in turn reacts further to undesired products. Furfuryl ethers were found to react to DMF much faster than HMF, explaining the higher reactivity of HMF when alcohol solvents were used. With the optimal residence time, it was possible to achieve yields approaching 70% in the flow reactor with the Pt/C catalyst. Much higher selectivities and yields were obtained in the flow reactor than in the batch reactor because side products are formed sequentially, rather than in parallel, demonstrating the importance of choosing the correct type of reactor in catalyst screening. © 2014 American Institute of Chemical Engineers AIChE J, 61: 590–597, 2015     

Oxygen electrocatalysis under fuel cell conditions: behaviour of cobalt porphyrins and tetraazaannulene analogues

Under fuel cell conditions, using a protonic conductor Nafion® electrolyte, active cobalt porphyrins (TpOCH₃PPCo or CoTMPP and derivatives) and cobalt tetraazaannulene (CoTAA) supported on an active charcoal were investigated towards oxygen reduction to test their activity and stability. Over a 200 h period, performances were found almost constant with CoTAA after an 800°C heat treatment (HT 800), whereas performances with different substituted phenyl porphyrins declined. XPS analyses were also carried out on these electrodes. On all samples they displayed a complete loss of cobalt within the measurement accuracy. Heat treatment temperature effects were visible on the Nls spectra for the CoTAA samples, the most stable and active samples presenting the lowest oxidation state after current drain application.     

Inhibition of butter oxidation by <Emphasis Type="Italic">N</Emphasis>-acetyl-cysteine and glutathione

The ability of N-acetyl-cysteine and glutathione to inhibit the oxidation of butter was evaluated. Peroxide value and thiobarbituric acid reactive substances were monitored during storage of butter at 50 °C for up to 84 days and at 110 °C for up to 12 h. N-Acetyl-cysteine and glutathione inhibited butter oxidation at 50 °C and at 110 °C. They were active at 10 mg/L and in a higher degree at 20 mg/L. N-Acetyl-cysteine appeared to be more active than glutathione. At 50 °C, N-acetyl-cysteine at 20 mg/L exhibited antioxidant activity comparable to that of butylated hydroxyanisole (BHA) at 200 mg/L. Volatile aldehydes were also determined during storage of butter at 50 °C for 10 days. N-Acetyl-cysteine and glutathione, each at 20 mg/L, inhibited the formation of several volatile aldehydes such as hexanal to an extent equal to BHA at 200 mg/L. Present results indicate that N-acetyl-cysteine and glutathione, especially the former, may be taken into account as antioxidants in butter during storage and cooking.     

Inhibition of corn oil oxidation by N-acetyl-cysteine and glutathione

The ability of N-acetyl-cysteine and glutathione to inhibit the oxidation of corn oil was evaluated.     

Electron-Lattice Coupling in Manganites and Cuprates

The lattice effects of charge localization in manganites and cuprates arediscussed from the local structural point of view. Pulsed neutron atomicpair-density function (PDF) analysis indicates that in La_1–x Sr _x MnO₃ the realstructure deviates from the average crystal structure, and the localJahn–Teller (JT) distortion of Mn³⁺O₆ octahedra remains even in themetallic phase. This leads to a concept of the critical ionic size factorfor the formation of JT polarons. The colossal magnetoresistance (CMR)phenomena are observed in the crossover region from localized to delocalizedcharge states. This concept also explains the asymmetry of the phase diagramwhich is difficult to understand in the current band picture. Similarconsideration may help understand the lattice effects in superconductingcuprates.     

Functional cyclodextrins. 1. Chloroacetylated cyclodextrins

The paper discusses the synthesis of the chloroacetylated derivatives of α-, β- and γ-cyclodextrins. These novel functionalized products can be used both in the synthesis of some conjugates with bioactive substances by covalent bonding and/or for inclusion of hydrophobic compounds.     

Is the rate of sulfur-disulfide exchange between the native β-Lactoglobulin and PDS related to protein conformational stability?

Summary The sulfhydryl (SH) group of β-lactoglobulin (β-Lg) affects many of its functional properties. Native β-Lg was treated with pyridine disulfide (PDS) at pH 2.6–8.5 (25 °C). SH-disulfide exchange was monitored by spectrophotometry. The kinetics of β-Lg sulphydryl-disulphide exchange was compared with the same reaction for reduced glutathione (GSH). From such results we estimate, ΔG_ex, the free energy change for exposing the SH-group of β-Lg to solvent. The numerical value for ΔG_ex is equal to the free energy change for β-Lg dissociation at pH 7. At neutral pH, the rate of sulphydryl- disulphide exchange appears to be controlled by the dimer-monomer dissociation equilibrium. At other solvent pHs, β-Lg sulphydryl reactivity towards a small disulphide compound like PDS may not involve the dissociation of native β-Lg.     

An adaptive partitioning approach for mining discriminant regions in 3D image data

Mining discriminative spatial patterns in image data is an emerging subject of interest in medical imaging, meteorology, engineering, biology, and other fields. In this paper, we propose a novel approach for detecting spatial regions that are highly discriminative among different classes of three dimensional (3D) image data. The main idea of our approach is to treat the initial 3D image as a hyper-rectangle and search for discriminative regions by adaptively partitioning the space into progressively smaller hyper-rectangles (sub-regions). We use statistical information about each hyper-rectangle to guide the selectivity of the partitioning. A hyper-rectangle is partitioned only if its attribute cannot adequately discriminate among the distinct labeled classes, and it is sufficiently large for further splitting. To evaluate the discriminative power of the attributes corresponding to the detected regions, we performed classification experiments on artificial and real datasets. Our results show that the proposed method outperforms major competitors, achieving 30% and 15% better classification accuracy on synthetic and real data respectively while reducing by two orders of magnitude the number of statistical tests required by voxel-based approaches.     

国外低特征信号富燃料推进剂的研究进展

综述了国外低特征信号富燃料推进剂的研究进展,归纳了研究低特征信号富燃料推进剂的技术途径。认为碳氢富燃料推进剂具有低特征信号的特点,是研究低特征信号富燃料推进剂的基础,采用非金属燃料是降低推进剂一次烟烟雾特征信号的有效途径,通过添加剂消除HCl是降二次烟的有效手段。对我国低特征信号富燃料推进剂的发展提出了几点建议。