Phase selection and microstructure formation in undercooled Co–61.8 at.% Si melts under various containerless processing conditions

The hypoeutectic composition Co–61.8 at.% Si was undercooled and solidified using electromagnetic levitation, electromagnetic levitation under a static magnetic field, electrostatic levitation and glass-fluxing. The samples generally showed two thermal events, either separated or continuous depending on undercooling. In situ monitoring of the two thermal events with a high-speed camera revealed a sudden decrease of dendritic growth velocities of primary phases at a critical undercooling of 88 K. Scanning electron microscopy studies of the solidified samples showed that the CoSi compound and the CoSi₂ compound nucleate as the primary phase for low and high undercoolings, respectively. The microstructure of the samples depends not only on undercooling, but also on the onset temperature or delay time of the second thermal event. Melt convection has no effect on the primary phase selection in undercooled melts, but it has a significant effect on the delay time and therefore on microstructure formation of the samples for high undercoolings.     

Electron beam welding of aluminium alloy by wire feed method (1st Report).Effect of filler wire melting configuration on bead formation

The 5XXX series of non-heat-treatable aluminium alloys, widely used in modern industry, have the peculiarity that an area near the welding bead, which reaches a temperature higher than 230°C, suffers an annealing effect that causes a considerable decrease in yield strength. The present paper deals with the three-dimensional modelling, using general-use finite element software, of a classic experiment conducted in the past by Masubushi, using the GMAW process on aluminium alloy 5052 H32, in order to determine the thermal history, and transient and residual strain and stress. Finally, a method for modelling applicable to this material type is proposed, where the model is divided into three zones; one near the weld with the properties of aluminium in annealed state, another further away with the base metal properties, and a transitional zone with intermediate properties.     

Effect of REM addition of wire on CO2 gas shielded arc phenomenon

Carbon dioxide (CO₂) gas shielded arc welding is the main arc welding method, but it generates a large amount of spatter during welding. The root cause of spatter lies in the fact that the droplet undergoes repeated irregular shaking. To solve this problem, spatter generation modes were clarified and the effects of polarity and rare earth metal (REM) addition of the wire on CO₂ gas shielded arc welding were investigated. As a result, when welding is performed with an electrode negative (DCEN) polarity using REM added wire, it was found that a conical arc plasma is formed, and the droplet which is transferred from the wire tip to the molten pool is fine and continuous, in what is termed ‘spray transfer’. Thus, spatter generation was reduced to 10% of amount of the conventional CO₂ gas shielded arc welding (from 0.058 to 0.005g/s).     

Crystallographic analysis for acicular ferrite formation in low carbon steel weld metals

Inclusions contributing to acicular ferrite nucleation were investigated from a crystallographic point of view in low carbon low alloy steelweld metals. The samples from electro slag welding (ESW) and submerged arc welding (SAW) deposits with various cooling rates were prepared in this study. In those samples, intragranular acicular ferrite formation was observed from inclusions. The inclusions contributing to acicular ferrite formation were of multi-phase type consisting of amorphous phase, spinel type and MnS. They were surrounded by a Ti-enriched layer. It was confirmed by selected area diffraction patterns and energy-dispersive X-ray spectrometer analyses that the Ti-enriched layer was TiO. The acicular ferrite had a Baker–Nutting orientation relationship with the TiO layer on the inclusion surface. The misfit was 3.0% at the interface between the acicular ferrite and TiO. Therefore, it is considered that TiO on the inclusion surface contributes to the heterogeneous nucleation of acicular ferrite by small lattice misfit. However, themorphologies of ferrite growth which nucleated from inclusions were different in both samples. Whereas the growth of ferrites nucleated from TiO was enough in ESW, the size of nucleated ferrite in SAW was a few hundred millimetres in size. In the early stage of nucleation from TiO, ferrite had small deviation from Kurdjumov–Sachs orientation relationship (K–S relationship) in both ESW and SAW. However, there was a difference in the growth stage of ferrite. The ferrite orientations were gradually changed to fit to the K–S relationship in ESW. On the other hand, the nucleated ferrite in SAW stopped growing and the newly nucleated ferrite which had K–S relationship prior to austenite was formed adjacently because of large super cooling due to small heat input.     

Electro ultrasonic remediation of polycyclic aromatic hydrocarbons from contaminated soil

The polycyclic aromatic hydrocarbons (PAHs) with high molecular mass are renown for their high persistence in the soil, hydrophobic and toxicity. Remediation of these pollutants is still an unsolved task and needs more researches to be performed. The coupling of electrokinetics (EK) with ultrasonic energy (US) has advantages on desorbing and migrating PAHs from contaminated soil. US and EK work together to destroy PAHs. The objective of this study was to treat PAHs contaminated soil by using EK and ultrasonication. The contaminated oil contained about 100 mg kg⁻¹ chrysene. Experiments with US, EK and combined EK and ultrasound were conducted in reactors and pans with and without iron anodes. Results indicated that the removal was more effective with lower concentrations of chrysene. The average removal was better in experiment with combined EK and ultrasound using iron anode. This might be due to increase in electroconductivity by iron ions.     

Effects of Age and Mating on Female Sex Attractant Pheromone Levels in the Sorghum Plant Bug, <Emphasis Type=Italic>Stenotus rubrovittatus</Emphasis> (Matsumura)

Previous work has shown that male sorghum plant bugs, Stenotus rubrovittatus (Matsumura) (Heteroptera: Miridae), are more attracted to young virgin females than to old virgin females and are not attracted to mated females. Therefore, we examined the effects of age and mating status on female sex pheromone levels. The pheromone components, hexyl butyrate, (E)-hex-2-en-1-yl butyrate, and (E)-4-oxohex-2-enal, were collected from females in two different ways. First, the compounds were extracted from whole bodies of each female and quantified by gas chromatography-mass spectrometry (GC-MS). Pheromone levels extracted from virgin female bodies decreased with age. In females that had just mated, pheromone levels did not differ from those of virgin females, and pheromone levels in mated females remained relatively constant up to 15 d after mating. This absence of change in pheromone levels extracted from whole bodies of mated females is not congruent with previous reports of lack of male attraction to these females. In a second method for pheromone recovery (adsorption on a PDMS-coated stir bar), GC-MS analysis showed that mated females released lower amounts of pheromone components compared to those emitted by virgin females of the same age (4 d). As was the case with whole body extracts, young virgin females (3 d) released higher amounts of pheromone components than did old virgin females (8 d). The results suggest that male response in S. rubrovittatus is dictated more by the quantities of pheromone components released into the volatile headspace by females than by the quantities present in the body.     

Membrane evaluation for the treatment of acidic clear filtrate

The total effluent load of a paper mill can be significantly decreased by recycling of purified clear filtrate (CF) back to paper-making process. The CF treated with membranes can be reused, for instance, as wire section shower water and in the dilution of chemicals. The main requirements for a membrane in CF treatment are high filtration capacity, high retention of turbidity and low fouling tendency. Previous studies have shown that the regenerated cellulose (RC) ultrafiltration (UF) membrane C30F (current trade name UC030T) is especially suitable for the treatment of paper mill process waters. Every paper-making process is, however, different. Thus, filtration experiments are required in order to find the most optimal membrane for the treatment of a certain process water. In this study the best membrane for the treatment of acidic clear filtrate (ACF) was searched. The performance of the C30F membrane was compared with five UF and three microfiltration (MF) membranes. The results revealed that in addition to the C30F membrane, also some other membranes produced high filtration capacity with ACF (approximately 200 L/(m²h bar)). All the tested membranes also retained over 90% of turbidity. The extremely hydrophilic C30F membrane had, however, lower fouling tendency compared to the other tested membranes. Therefore, it was concluded that the C30F membranes were the best possible membrane for the ACF treatment.     

Homology-Based Interactions between Small RNAs and Their Targets Control Dominance Hierarchy of Male Determinant Alleles of Self-Incompatibility in Arabidopsis lyrata

Self-incompatibility (SI) is conserved among members of the Brassicaceae plant family. This trait is controlled epigenetically by the dominance hierarchy of the male determinant alleles. We previously demonstrated that a single small RNA (sRNA) gene is sufficient to control the linear dominance hierarchy in Brassica rapa and proposed a model in which a homology-based interaction between sRNAs and target sites controls the complicated dominance hierarchy of male SI determinants. In Arabidopsis halleri, male dominance hierarchy is reported to have arisen from multiple networks of sRNA target gains and losses. Despite these findings, it remains unknown whether the molecular mechanism underlying the dominance hierarchy is conserved among Brassicaceae. Here, we identified sRNAs and their target sites that can explain the linear dominance hierarchy of Arabidopsis lyrata, a species closely related to A. halleri. We tested the model that we established in Brassica to explain the linear dominance hierarchy in A. lyrata. Our results suggest that the dominance hierarchy of A. lyrata is also controlled by a homology-based interaction between sRNAs and their targets.     

Methods for determination of milt protein and epsilon-polylysine in food additive preparations and processed foods by capillary zone electrophoresis

A simple and rapid method using capillary zone electrophoresis (CZE) for the determination of milt protein (MP), which contains mainly protamine, and polylysine (PL) in food additive preparations and processed foods was developed. CZE separation was performed on poly(vinyl alcohol)-coated capillaries at a column temperature of 20 degrees C with 120 mmol/L phosphate buffer (pH 2.5) as the running buffer. The influence of various components in food additive preparations on CZE analysis of MP and PL was examined. Egg white lysozyme, glycine, sodium acetate, glycerol, fumaric acid, calcium carbonate, dextrin, emulsifiers and sodium polyphosphate and pyrophosphate had no effect. No peak of protamine was detected in preparations containing metaphosphate. The analysis method for processed foods was composed of extraction with 4% formic acid, precipitation of macromolecular compounds with ethanol, concentration in a water bath and determination by CZE. The average recoveries were 108.4% for protamine sulfate (PS) in red bean sticky rice, and 81.3% for PL in white rice, 118% in egg sandwiches, and 115% in shiraae. The limits of detection of PS in red bean sticky rice and PL in white rice were both 50 ppm.     

Evaluation of Local Mechanical Properties in Depth in MoDTC/ZDDP and ZDDP Tribochemical Reacted Films Using Nanoindentation

Local mechanical properties in depth and near the surface of MoDTC/ZDDP and ZDDP tribofilms, which exhibited obviously different friction coefficients in a pin-on-disc test, were determined by using a nanoindentation technique combined with in-situ atomic force microscopy (AFM) observation. Tapping-mode AFM observation revealed that the MoDTC/ZDDP film was much rougher than the ZDDP film. Nanoindentation measurement revealed that the MoDTC/ZDDP and ZDDP tribofilms possessed different elasto-plasticities around a depth of several nanometers from the surface, although both films showed the same hardness and modulus depth distributions except in the surface area. The same mechanical depth distributions indicated that both kinds of tribofilm were functionally graded materials; that is, they consisted of a layer near the surface with lower hardness and modulus and providing lubrication and a base layer with higher hardness and modulus and serving to modify property differences at the interface. Most importantly, the different elasto-plasticities near the tribofilm surfaces revealed that the MoDTC/ZDDP tribofilm possessed lower shearing yield stress than the ZDDP tribofilm. The results of this study suggest that the presence of some solid lubricants such as MoS₂ just below the MoDTC/ZDDP film surface reduced the boundary friction coefficient.