Dissolution Behavior of Rhodium in the Na2O-SiO2 and CaO-SiO2 Slags

To understand the behavior of rhodium during its recovery process, the dissolution behaviors of rhodium in Na₂O-SiO₂ and in CaO-SiO₂ slags at temperatures ranging from 1423 K to 1623 K (from 1150 °C to 1350 °C) and from 1773 K to 1873 K (from 1500 °C to 1600 °C), respectively, in an oxidizing atmosphere were investigated. The solubility of rhodium in the slags was found to increase with increasing oxygen partial pressure, temperature, and the basic oxide content. The correlation between the solubility of rhodium and the oxygen partial pressure suggested that rhodium dissolved into the slags as RhO_1.5. The dissolution of rhodium was slightly endothermic: the enthalpy change of the dissolution of solid rhodium was determined to be 50 ± 10 kJ/mol for the 50(mass pct)Na₂O-50SiO₂; and 188 ± 94 kJ/mol for the 56(mass pct)CaO-44SiO₂ slag systems. The increase in the solubility of rhodium with the basic oxide content indicated that rhodium exhibits acidic behavior in slags. The correlation between the solubility of rhodium and the sulfide capacity of the slags suggested that the ionic species of rhodium in slags is the rhodate ion, RhO ₂ ^? . The rhodate capacity of the slags was defined, and its application to estimate the possible rhodium content in various slag systems was proposed.     

Contrast enhancement in the phase plate transmission electron microscopy using an objective lens with a long focal length

A new optical condition using an objective lens (OL) of a long focal length (objective mini lens: OM) was tested to enhance image contrast in phase plate transmission electron microscopy (P-TEM). A phase plate was set on the selected area aperture plane where diffraction patterns were formed under the optical condition using the OM. A phase shift by the phase plate was added to the electron waves to visualize phase objects. The application of the OM to the P-TEM should provide higher phase contrast than that obtained by the OL for the phase objects. One of the reasons for the contrast enhancement is that high-angle scattering electron waves which would give the background intensity were not used for image formation due to the large spherical aberration. Another reason is that the cut-on frequency above which the phase shift was added by the phase plate could be smaller using the OL with a long focal length. Experimental results and model calculations showed the contrast enhancement of the biological specimens using the OM.     

Effect of nitrogen source on mycelial morphology and arachidonic acid production in cultures of Mortierella alpina

The effects of nitrogen source on arachidonic acid (AA) production and morphological changes during the culture of Mortierella alpina were investigated using an image analysis system. When yeast extract, gluten meal, or corn steep liquor was used, a circular pellet morphology was obtained. However, when Pharmamedia, fish meal, or soybean meal was used, M. alpina formed radial filamentous mycelia. The radial filamentous area in the case of soybean meal was 75% of the total mycelial area. In a jar fermentor culture, M. alpina morphology varied with the cultivation period: (i) at 0-6 h culture, the inoculated pellet-like mycelia were adapted to the new environment, (ii) at 6 h-1 d culture, filamentous mycelia grew exponentially which yielded a feather-like morphology, (iii) at 1-2 d culture, the filamentous mycelia became disentangled as a result of the mechanical agitation; consequently, the proportion of filamentous mycelia was increased, (iv) at 2-4 d culture, mycelia showed stationary growth, but the AA concentration increased rapidly, and (v) at 4-6 d culture, hyphae grew thick radially with the AA concentration continuing to increase gradually. In the case of the cultures with feather-like morphology obtained using soybean meal, the AA yield was 0.14 g/g dry cell weight, which was two times higher than that in cultures grown using yeast extract. These results suggest that the feather-like morphology of culture of M. alpina is suitable for AA production.     

Evaluation of titanium alloy fabricated using electron beam melting system for dental applications

In recently advanced rapid prototyping and manufacturing methods, one additional process is to use an electron beam to fabricate metal objects by the layer by layer sintering and/or melting metal powder. This method is often called electron beam melting (EBM). This study examined the mechanical properties, the grindability and corrosion resistance of Ti-6Al-4V ELI (extra low interstitial) specimens which were fabricated by the electron beam melting (EBM) process. Dumbbell-shaped specimens and two kinds of plate specimens were prepared using the Ti-6Al-4V ELI powder in the EBM system. The yield strength, tensile strength, modulus of elasticity and percent elongation at a crosshead speed of 0.25 mm/min were tested. The Vickers hardness in interior structures was determined. Grindability was evaluated as volume loss (mm³) when the specimen was abraded using a SiC wheel at 1250 m/min for 1 min. Lastly, corrosion behavior was examined using the dynamic potentiostatic polarization technique in an artificial saliva at 37 °C. As controls, cast and commercial wrought alloys of Ti-6Al-4V ELI and commercially pure titanium (CP Ti) were evaluated. Cast specimens were prepared in a centrifugal casting machine using a MgO based mold. For the cast specimens, all the mechanical properties, grindability and corrosion characteristics were tested. On the other hand, for wrought specimens, only grindability and corrosion properties were tested. The yield and tensile strength of the as-fabricated Ti-6Al-4V ELI specimens without any additional metallurgical treatments were found to be 735 MPa and 775 MPa, respectively. The elongation was 2.3%. These values are well within many of precious and non-precious dental casting alloys.     

The design and production of Ti-6Al-4V ELI customized dental implants

This paper addresses the production of customized Ti-6Al-4V ELI dental implants via electron beam melting (EBM). The melting of Ti-6Al-4V ELI powder produces implants with great biocompatibility, fi ne mechanical performance, and a high bone ingrowth potential. The EBM technology is used to produce one-component dental implants that mimic the exact shape of the patient’s tooth, replacing the traditional, three-component, “screw-like” standardized dental implants currently used. The new generation of implants provides the possibility of simplifying pre-insertion procedures leading to faster healing time, and the potential of better and stronger osseointegration, specifi cally through incorporating lattice structure design.     

Model Transformer Evaluation of High-Permeability Grain-Oriented Electrical Steels

1. IntroductionThe demand for grain-oriented electrical steel asthe transformer core material having reduced iron losshajs been continuously growing for the general objective to achieve ever greater energy savings and globalenvironmental preservation. In line with this trend,efforts to reduce iron loss in steel sheets have been pursued both in hysteresis and eddy-current losses. Theformer has been improved mainly through metallurgical means such as achieving higher grain-orientationand reducin…     

Fatigue simulation for titanium/CFRP hybrid laminates using cohesive elements

This paper presents a new numerical approach for predicting fatigue crack growth in fiber-metal laminate (FML). Cohesive elements are used to express the complicated damage consisting of transverse cracking, splitting, and interlaminar delamination. The damage growth in the cohesive elements due to cyclic loading is represented by the conventional damage-mechanics model. The simulation was applied to notched Ti/CFRP hybrid laminates of two stacking configurations. In both cases, the crack growth rate in the titanium layer and the delamination shape agreed well with experiments reported in the literature. Complementary analysis for crack extension in the metal sheet is performed out of consideration of the damage in internal FRP layers. The numerical results demonstrated that the underlying damage modes in the FRP layer must be taken into account to predict the fatigue crack growth at the metal layer in FMLs.     

Modeling the effect of statistical variations in length and diameter of randomly oriented CNTs on the properties of CNT reinforced nanocomposites

A nano-mechanical model has been developed to calculate the tensile modulus and the tensile strength of randomly oriented short carbon nanotubes (CNTs) reinforced nanocomposites, considering the statistical variations of diameter and length of the CNTs. According to this model, the entire composite is divided into several composite segments which contain CNTs of almost the same diameter and length. The tensile modulus and tensile strength of the composite are then calculated by the weighted sum of the corresponding modulus and strength of each composite segment. The existing micro-mechanical approach for modeling the short fiber composites is modified to account for the structure of the CNTs, to calculate the modulus and the strength of each segmented CNT reinforced composites. Multi-walled CNTs with and without inter-tube bridging have been considered. Statistical variations of the diameter and length of the CNTs are modeled by a normal distribution. Simulation results show that CNTs inter-tube bridging, length and diameter affect the nanocomposites modulus and strength. Simulation results have been compared with the available experimental results and the comparison concludes that the developed model can be effectively used to predict tensile modulus and tensile strength of CNTs reinforced composites.     

In situ blotting: a novel method for direct transfer of native proteins from sectioned tissue to blotting membrane: procedure and some applications

We describe a novel technique for direct transfer of native proteins from unfixed frozen tissues sections to an immobilizing matrix, e.g., nitrocellulose, polyvinyliden difluoride, or positively charged nylon membranes. Proteins are directly blotted onto the membrane, providing optimal accessibility for molecular detection but retaining the anatomic localization at the cellular level. Within 10 min a maximum protein transfer is achieved independent of the protein molecular weight. The total protein bound was 80% of the maximal binding capacity of the blotting membrane and independent of the section thickness. These results indicate that the proteins that bind to the membrane originate from the cut cell monolayer that has direct contact with the blotting membrane. This in situ blotting method provides direct protein mapping from a single cell layer of a tissue section. The procedure includes cryosectioning at 20 microns and collecting sections on a dry blotting membrane at -20 degrees C. For protein transfer the blotted sections are thawed and incubated for 10 min with Tris buffer. After incubation the sections are removed from the membrane by high-pressure spray. The blotted membranes can be subjected to several detection assays. In the present study the presence of several proteins was demonstrated in brain and thymus by immunochemical and enzyme histochemical procedures.