Protein Expression Changes in Maize Roots in Response to Humic Substances

Humic substances are known to affect plant metabolism at different levels. We characterized humic substances extracted from earthworm feces by diffuse reflectance infrared Fourier transform (DRIFT) spectroscopy and used them to treat corn, Zea mays L., seedlings to investigate changes in patterns of root protein expression. After root plasma membrane extraction and purification, proteins were separated by two-dimensional gel electrophoresis, and differential spot intensities were evaluated by image analysis. Finally, 42 differentially expressed proteins were identified by liquid chromatography-tandem mass spectrometry (LC-MS/MS). The majority of them were downregulated by the treatment with humic substances. The proteins identified included malate dehydrogenase, ATPases, cytoskeleton proteins, and different enzymes belonging to the glycolytic/gluconeogenic pathways and sucrose metabolism. The identification of factors involved in plant responses to humic substances may improve our understanding of plant-soil cross-talk, and enable a better management of soil resources.     

Morphological and electrochemical investigation of RuO<Subscript>2</Subscript>–Ta<Subscript>2</Subscript>O<Subscript>5</Subscript> oxide films prepared by the Pechini–Adams method

Preparation methods can profoundly affect the structural and electrochemical properties of electrocatalytic coatings. In this investigation, RuO₂–Ta₂O₅ thin films containing between 10 and 90 at.% Ru were prepared by the Pechini–Adams method. These coatings were electrochemically and physically characterized by cyclic voltammetry, scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD). The composition and morphology of the oxide were investigated before and after accelerated life tests (ALT) by EDX and SEM. SEM results indicate typical mud-flat-cracking morphology for the majority of the films. High resolution SEMs reveal that pure oxide phases exhibit nanoporosity while binary compositions display a very compact structure. EDX analyses reveal considerable amounts of Ru in the coating even after total deactivation. XRD indicated a rutile-type structure for RuO₂ and orthorhombic structure for Ta₂O₅. XPS data demonstrate that the binding energy of Ta is affected by Ru addition in the thin films, but the binding energy of Ru is not likewise influenced by Ta. The stability of the electrodes was evaluated by ALT performed at 750 mA cm⁻² in 80 °C 0.5 mol dm⁻³ H₂SO₄. The performance of electrodes prepared by the Pechini–Adams method is 100% better than that of electrodes prepared by standard thermal decomposition.     

Time averaged temperature calculations in pulse electrochemical machining, part II: numerical simulation

Simulation of the temperature distribution and evolution during pulse electrochemical machining can be a computationally very expensive procedure. In a previous part of the work [Smets et al. J Appl Electrochem 37(11):1345, 2007] a new approach to calculate the temperature evolution was introduced: the hybrid method, which combines averaged and pulsed calculations. The averaged calculations are performed by time averaging the boundary conditions and the bulk heat sources of the system. The timesteps used during the averaged calculations are then no longer dictated by the pulse characteristics. Using this approach, computationally very cheap, yet satisfactory results can be obtained. The analysis in the previous part of the work was obtained from analytical solutions on simplified models. In this part, the more general case is solved numerically. Multiple geometries are simulated and analyzed and methods are compared. Very satisfactory, yet cheap results are obtained.     

3,5,6-三氯吡啶-2-醇钠在超(近)临界水中的稳定性

3,5,6-三氯吡啶-2-醇钠(STCP)热稳定性的研究对于认识2,3,5,6.四氯吡啶(TCP")水解制取STCP过程和STCP废水的处理具有重要的实际意义.在管式反应器中考察了温度、压力、停留时间和物料配比对STCP稳定性及其降解产物的影响.结果表明,当温度低于280℃时,STCP具有良好的稳定性;随着反应温度的升高、压力的增大和停留时间的延长,其稳定性降低.降解产物在525 nm处出现的特征峰是STCP的异构体吡啶酮类化合物引起的.此外,在加压条件下研究了反应温度、压力、时间和原料配比对TCP水解的影响,其中反应温度是决定水解反应的关键因素,TCP与NaOH摩尔比为1:4时,140℃下反应3 h,收率达95%以上,纯度为99%.     

Hydrodesulfurization of thiophene on carbon nanofiber supported Co/Ni/Mo catalysts

Co, Mo, NiMo and CoMo catalysts supported on alumina, fishbone and platelet carbon nanofibers (CNFs) have been prepared. The dispersion of the oxide phases was qualitatively studied and compared using X-ray diffraction (XRD) and transmission electron microscopy (TEM). The reducibility of the catalysts was studied by temperature programmed reduction (TPR). Hydrodesulfurization (HDS) of thiophene was used as a model reaction to compare the activity of different catalysts. The activity tests showed that the alumina supported catalysts exhibited higher activity compared to the corresponding CNF supported catalysts, and the NiMo catalysts were more active than the corresponding CoMo catalysts. The thiophene HDS activity was correlated with the dispersion of the molybdenum species and the reducibility of different catalysts. Interestingly, the CNF supported Co catalysts have higher thiophene HDS activity than the CNF supported Co(Ni)Mo catalysts.     

Oxygen reduction reaction properties of carbon nanofibers: Effect of metal purification

Carbon nanofibers (CNFs) are grown on metal catalysts and electrochemical treatment is used to remove the metal catalyst residuals from the as-grown CNFs. For comparison, the CNFs are also purified by a chemical method and a thermal method. The oxygen reduction reaction (ORR) properties of CNFs purified by these three methods are examined by cyclic voltammetry. CNFs treated by the electrochemical method have a more positive ORR onset reduction potential and peak potential compared with those treated by chemical and thermal methods, and this is because the microstructures of CNFs are less changed by electrochemical method. However, they have a lower electrochemical capacity and ORR peak current than those treated by the chemical method. Cyclic voltammetric measurements at different scan rates confirm that the oxygen reductions on CNFs treated by electrochemical and chemical methods are controlled by diffusion, while on CNFs treated by thermal method is partially influenced by diffusion.     

Identification of trinucleotide repeat ligands with a FRET melting assay

DNA hairpin structures formed within a repeated tract might be a causative factor for triplet expansion observed in several debilitating diseases. We have designed and used a fluorescence resonance energy transfer (FRET) melting assay to screen for ligands that bind specifically to the CNG triplet repeats. Using this assay, we screened a panel of 33 chemicals that were previously designed to bind DNA or RNA secondary structures. Remarkably, we found that macrocyclic compounds, such as acridine dimers and trimers, exhibit interesting affinities and specificities for this motif.     

The role of the conserved threonine in P450 BM3 oxygen activation: substrate-determined hydroxylation activity of the Thr268Ala mutant

The hydroxylation activity of the Thr268Ala mutant of P450(BM3) has been shown to occur to varying degrees with small alterations in the structure of a fatty-acid substrate. Ten substrates were investigated, including straight chain, branched chain and cis-cyclopropyl substituted fatty acids with a straight-chain length that varied between 12 and 16 carbon atoms. The efficacy of the hydroxylation activity appeared to be governed by the chain length of the substrate. Substrates possessing 14 to 15 carbons afforded the highest levels of activity, which were comparable with the wild-type enzyme. Outside of this window, straight-chain fatty acids showed reduced activity over the other substrate types. These results provide a cautionary tale concerning the loss of ferryl activity in such cytochrome P450 threonine to alanine mutants, as the nature of the substrate can determine the extent to which hydroxylation chemistry is abolished.     

注射工艺对稀土β成核剂改性PP力学性能影响

考察了工艺参数对稀土β成核剂改性聚丙烯(β-PP)力学性能的影响.当注射速率在20～80 mm/s变动时,β-PP冲击强度的最大值与最小值相比提高了12.2%,熔体温度在190～250℃、保压压力在20～50 MPa和保压时间在2～60 s变动时,冲击强度相对应的提高幅度分别为22.2%,31.8%和97.7%;同时对比了不同工艺条件对α-PP(未添加β成核剂聚丙烯)和β-PP冲击性能影响的差异.结果表明.β-PP对注射工艺条件的变化更敏感.     

钽等离子体渗氮的表面过程分析

对钽表面渗氮的固－气界面反应过程进行了热力学和动力学分析,从到理论预测了各种参数（压力、气体、组成、温度、电参数等）对表面过程的影响,并借助于等离子体,在较你廿获得由层与Ｎ在ＴＡ中的固溶体组成的表面硬化层,层为六方晶系的Ｔａ６Ｎ２,５７和／或非昌态。通过调整工艺参数有效地抑制了钽表面氧的渗入和Ｔａ２Ｏ５的形成,使得离子渗氮后,仍保持较低的表面粗糙度。