The effect of laser texturing of SiC surface on the critical load for the transition of water lubrication mode from hydrodynamic to mixed

Experiments were carried out to verify if the low friction range of SiC in water lubrication can be expanded by micro-pores on the contact surface. Pores were formed by laser, with a diameter of 150 μm and a depth of about 8–10 μm and were distributed in a square array on the contact surface. Seven kinds of textured specimens with different intervals between the pores were tested and compared with the untextured specimen. The effect of the pore area ratio on friction coefficient and the critical load for the transition from hydrodynamic lubrication to mixed lubrication was reported and discussed.     

Oxidation of methane over Pd/mixed oxides for catalytic combustion

Palladium catalysts supported on mixed oxides (Pd/Al₂O₃–MO_x; M=Co, Cr, Cu, Fe, Mn, and Ni) were investigated for the low-temperature catalytic combustion of methane. Although the surface area decreased with increasing NiO in Pd/mAl₂O₃–nNiO, Pd/Al₂O₃–36NiO demonstrated an excellent activity due to the small particle size of palladium. Also, the catalytic activity strongly depended on the composition of the support. Temperature-programmed desorption of oxygen revealed that the catalytic activity in the low-temperature region depends on the adsorption state of oxygen on palladium. The activity was enhanced when the amount of adsorbed oxygen increased. In-situ XRD analysis indicated that the PdO phase was thermally stabilized on Pd/Al₂O₃–36NiO.     

Modification of anion exchange membranes by oxidation of selected chemical sites for the purpose of preventing fouling during dialysis

The base membrane containing chloromethylstyrene units, prepared by the “paste method”, was treated with oxidizing reagents to determine whether the introduction of carboxylic acid groups onto the membrane surface might make the anion exchange membrane resistant to organic Fouling by anionic organic substances. The modified base membrane was then quarternized with an aqueous solution of trimethylamine.The oxidizing treatment with an aqueous solution of potassium permanganate made the resultant anion exchange membrane resistant to organic fouling by sodium dodecylbenzenesulfonate or sodium laurylsulfate.     

Novel Asymmetric Critical State in YBa2Cu3O7−δ with Columnar Defects

We studied the critical state field profile using magneto-optical technique in YBa ₂ Cu ₃ O _7– with columnar defects (CDs) when the field is tilted away from CDs. We observed an asymmetric critical state field profile with the current discontinuity line (d-line) considerably away from the center of the sample. The shift of the d-line from the center (y) has symmetric hysteresis loop with respect to H = 0. When the field sweep direction is changed, the previous d-line disappears and a new d-line is generated at the opposite side. The shift of the d-line is parallel to the tilting plane of H and toward the direction of the misalignment of H from CDs. We interpret this asymmetry as caused by the in-plane magnetization, which is originated from the alignment of vortices to CDs. The field dependence of y is discussed in relation with the correlation length of vortices along CDs.     

Chemical kinetic modeling of ammonia oxidation with improved reaction mechanism for ammonia/air and ammonia/hydrogen/air combustion

To achieve comprehensive prediction of ammonia combustion in terms of flame speed and ignition delay time, an improved mechanism of ammonia oxidation was proposed in this work. The present model (UT-LCS) was based on a previous work [Song et al., 2016] and improved by relevant elementary reactions including NH₂, HNO, and N₂H₂. The model clearly explained reported values of laminar flame speed and ignition delay time in wide ranges of equivalence ratio and pressure. This suggests that NH₂, HNO, and N₂H₂ reactivities play a key role to improve the reaction mechanism of ammonia oxidation in the present model. The model was also applied to demonstrate NH₃/H₂/air combustion. The present model also appropriately predicted the laminar flame speed of NH₃/H₂/air combustion as a function of equivalence ratio. Using the model, we discussed the reduction of NO concentration downstream and H₂ formation via NH₃ decomposition in NH₃/H₂ fuel-rich combustion. The results provide suggestions for effective combustion of NH₃ for future applications.     

Hydrogen peroxide, an excellent chromogenic reagent for reddening dyer's saffron flowers

Summary An aqueous solution of H₂O₂ promoted the reddening of dyer's saffron flowers, in which carthamin accumulated. The identity of the pigment was confirmed by TLC, HPLC, and UV, and IR spectra. The chemical procedure for flower reddening is discussed in terms of its use in carthamin production.

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Wasserstoffperoxyd, ein ausgezeichnetes Chromogenreagens zum Rotmachen von Safranblüten

Zusammenfassung Wäßrige Lösung von H₂O₂ fördert das Rotwerden von Safranblüten, in welchen Carthamin gespeichert ist. Die Identität des Farbstoffs wurde mit analytischen Methoden wie TLC, HPLC, UV- und IR-Spektren bestätigt. Die chemische Reaktion des Blütenrotwerdens wurde diskutiert zusammen mit der Nützlichkeit für die Carthamin-Farbenproduktion.

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Abbreviations ODS octadecyl silan - BAW n-butanol/acetic acid/water (4+1+2, v/v) - HOAc acetic acid/water (15+85, v/v) - PAW phenol/acetic acid/water (40+1+10, v/v) - TLC thin-layer chromatography; - HPLC high performance liquid chromatography - UV ultraviolet light - VIS visible light - IR infrared light - i.d. internal diameter