Traction force between rotating rolls and moving web considering the effect of air-entrainment

High-speed transportation of paper web sometimes leads the web handling system into unstable state because of increase in the air-entrainment into the gap between a rotating roll and moving web or the nip region of winding system. In this paper, the property of the traction change with increase in the air-entrainment into the gap between a paper roll and web or the nip region of winding system was investigated experimentally and theoretically. The critical speed to avoid slippage between a roll and web was found to be estimable by applying and extending the concept of “effective” frictional coefficient with the consideration of air-entrainment, which is proposed by Good et al. (Proceedings of the fourth international conference on web handling, 1997), Hashimoto (Proc JSME 1999(5):183–184, 1999a) and so on, to the estimation of the traction force defined as the frictional force on a paper roll or at the nip region. Consequently, the web handling stability at high-speed was found to be predictable.     

Tribological properties of single-walled carbon nanotube solids

Binder-free single-walled carbon nanotube (SWCNT) solids were evaluated for solid lubrication applications. The steady-state friction coefficients (mu) for the SWCNT solids were found to reach values as low as 0.22-0.24, according to unidirectional sliding friction tests using Si3N4 counterparts in air. The values were slightly higher than that of bulk graphite material (mu = 0.20). SEM and Raman analyses showed that most SWCNTs that existed in the friction surface transformed into SWCNT-derived transferred film made up of amorphous carbon during sliding. The resultant friction behavior may be related to the smearing of transferred film over the contact area, which was expected to permit easy shear and then help to achieve a lubricating effect during sliding.     

Negative thermal expansion materials: technological key for control of thermal expansion

Most materials expand upon heating. However, although rare, some materials contract upon heating. Such negative thermal expansion (NTE) materials have enormous industrial merit because they can control the thermal expansion of materials. Recent progress in materials research enables us to obtain materials exhibiting negative coefficients of linear thermal expansion over −30 ppm K⁻¹. Such giant NTE is opening a new phase of control of thermal expansion in composites. Specifically examining practical aspects, this review briefly summarizes materials and mechanisms of NTE as well as composites containing NTE materials, based mainly on activities of the last decade.     

Effect of Interlayer Thickness of Ion-Plated Pb-Coating on Its Life (SUS440C Substrates)

High-precision ball bearings (SUS440C) used in spacecraft mechanisms that are exposed to deep space vacuum are solid lubricated by thin, adherent Pb ion-plated coatings. The high reliability requirements with long endurance life of these mechanisms solely depend on the tribological aspects of this solid-lubrication coating. Since ion-plated, soft metallic coatings have a graded coating–substrate interface structure, a gradual change in mechanical, chemical and thermal properties is expected across the depth of the coating. This aspect of the interlayer plays a major role in determining the extent of optimum tribological properties of the coating. By improving the interlayer, both in terms of increased thickness and concentration of Pb, a corresponding improvement in the lubricity and endurance life of this Pb ion-plated coating on AISI 440C stainless steel (bearing material) can be assured. For this, a detailed examination of the interlayer of the ion-plated Pb film on the nano-micro level is mandatory. This report is focused on the cross-sectional examination of the interlayer by scanning electron microscopy. SUS440C steel disk specimens having similar properties as the bearing material and with a thin, ion-plated Pb coating processed under two different substrate bias conditions of ion-plating are used. The thickness of the Pb/steel interlayer and the elemental composition are analyzed using SEM and EDS respectively. The endurance life of the coatings is measured by repeated sliding wear tests with a pin-on-disk tester in vacuum. It is confirmed that with an increased thickness of the graded interfacial layer of the Pb ion-plated coating, the coating endurance life is extended remarkably.     

The Difference in Running-In Period and Friction Coefficient Between Self-Mated Si3N4 and SiC Under Water Lubrication

Running-in periods and friction coefficients of SiC and Si₃N₄ sliding against themselves under water lubrication were investigated with a pin-on-disk apparatus at sliding speed of 120 mm/s and a normal load of 5 N under ambient conditions. It was found that the running-in period of self-mated Si₃N₄ is much shorter than that of self-mated SiC, and also that the steady-state friction coefficient of self-mated Si₃N₄ was lower (0.0035) than that of self-mated SiC (0.01). The difference in mechanism was analyzed from the point of view of electronic structure and surface chemistry.     

Successive entrapping of red and yellow quinoid chalcones from aqueous extracts of dyer's saffron florets: a newly established and practically approved technique

Summary A setup for successive entrapping of red and yellow quinoid chalcone pigments was assembled. The device consists of four parts: a unit for the extraction of the pigments, a unit for their transfer to the column, a unit for entrapping the columns and a unit for releasing the trapped substances. The device enables us to extract the naturally occurring oxygen-labile, pH-sensitive and UV-fragile pigments on an economically approved scale.

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Schrittweises Freimachen von roten und gelben chinolden Chalkonen aus wäßrigen Extrakten von Safranblütenfarben; eine neue entwickelte und geprüfte Technik

Zusammenfassung Es wurde ein Plan fur das schrittweise Freimachen von roten und gelben chinoiden Pigmenten entwickelt. Die Arbeitsweise besteht aus vier Schritten. zuerst in der Extraktion der Pigmente, dann deren Überführung in die Säule, daraufhin das Freimachen aus der Säule und schließlich das Freisetzen der abgeschiedenen Stoffe. Dieses Vorgehen ermöglicht, die pH-, 02- und UV-empfindlichen Stoffe ökonomisch und gezielt zu gewinnen.

     

Vacuum and Pressured Combinatorial Processings for Exploration of Environmental Catalysts

Two types of combinatorial chemical reactors have been developed for high-throughput experimentation of catalysts that attract much interest from global environmental viewpoints. The high vacuum combinatorial laser MBE system was applied to the preparation of thin film library of TiO₂ with its film thickness gradually increased, which resulted in the discovery of new phenomenon indicating a quantum size effect in TiO₂ photo-catalysis. The combinatorial autoclave reactor was made to explore new catalysts and optimum reaction conditions efficiently for alternating CO₂ copolymerization with epoxide (oxirane) to form bio-degradable polycarbonates. Some preliminary results are reported on the CO₂ copolymerization with propylene oxide, as a means of CO₂ fixation into chemically useful material.     

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     

Tapping Effect on Friction Between Slider and Disk

The effect of tapping on friction between slider and disk in a hard-disk drive was investigated by using a model active slider with a piezo-actuator. It was found that the tapping can reduce friction, especially when the disk is smooth and the load is light. It was also found that a certain vibration amplitude is necessary to reduce friction significantly. In addition, the resonant frequency of the piezo-actuator was found to shift to higher values at higher suspension load. This frequency-shift is considered to be an important factor in optimizing the drive frequency of the actuator.     

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.