Synthesis of thermoresponsive copolymer/silica-coated magnetite nanoparticle composite and its application for heavy metal ion recovery

To enhance chemical stability and suppress of aggregation of magnetite nanoparticles (MNPs), which are used as a support for thermoresponsive copolymer immobilization, silica coating of the MNPs is applied via the electrooxidation method. Although the resulting silica coated-MNPs also formed aggregates, the size distribution of the aggregate shifted to smaller size range. Because of that, the surface area available for copolymer immobilization increased approximately 6.7 times at maximum as compared with that of the uncoated MNPs. It contributed to the increase of the amount of the immobilized copolymer on the silica-coated MNPs, which is approximately four times larger than that on the uncoated MNPs. Fe₃O₄ dissolution test confirmed enhancement of chemical stability of MNPs. The thermoresponsive copolymer immobilized on the silica-coated MNPs shows the ability to recycle Cu(II) ion from Cu(II) containing solution by changing temperature with significantly shorter time than those in other thermoresponsive adsorbents in gel form.     

Surface Analysis of Cr2O3‐, CoO‐, and Al2O3‐Doped Iron–Phosphate Glasses at High Temperature

Surface structures of iron–phosphate glasses were examined using X‐ray photoelectron spectroscopy (XPS). Cr₂O₃, CoO, and Al₂O₃ were introduced to the glass by the replacement of a part of Fe₂O₃, and the simulated fission products are also added. The obtained glasses showed high chemical durabilities by MCC‐1 test. In situ high‐temperature and room‐temperature XPS measurements were conducted on the polished sample surfaces and also those after 1‐week chemical durability test. Unique trends were observed in XPS spectra on heating and after the chemical durability test, respectively. Nature of the glass surface of iron–phosphate glasses was explained from the point of view of surface energy, and the origin of high chemical durability and the effect of chromium ions were discussed based on the changes on surface composition and valence states of transition‐metal ions.     

Autophagic Cell Death and Cancer

Programmed cell death (PCD) is a crucial process required for the normal development and physiology of metazoans. The three major mechanisms that induce PCD are called type I (apoptosis), type II (autophagic cell death), and type III (necrotic cell death). Dysfunctional PCD leads to diseases such as cancer and neurodegeneration. Although apoptosis is the most common form of PCD, recent studies have provided evidence that there are other forms of cell death. One of such cell death is autophagic cell death, which occurs via the activation of autophagy. The present review summarizes recent knowledge about autophagic cell death and discusses the relationship with tumorigenesis.     

Total reflection X-ray spectroscopy as a rapid analytical method for uranium determination in drainage water

Uranium concentrations in drainage water are typically determined by α-spectrometry. However, due to the low specific radioactivity of uranium, the evaporation of large volumes of drainage water, followed by several hours of measurements, is required. Thus, the development of a rapid and simple detection method for uranium in drainage water would enhance the operation efficiency of radiation control workers. We herein propose a novel methodology based on total reflection X-ray fluorescence (TXRF) for the measurement of uranium in contaminated water. TXRF is a particularly desirable method for the rapid and simple evaluation of uranium in contaminated water, as chemical pretreatment of the sample solution is not necessary, measurement times are typically several seconds, and the required sample volume is low. We herein employed sample solutions containing several different concentrations of uranyl acetate with yttrium as an internal standard. The solutions were placed onto sample holders, and were dried prior to TXRF measurements. The relative intensity, otherwise defined as the net intensity ratio of the Lα peak of uranium to the Kα peak of yttrium, was directly proportional to the uranium concentration. Using this method, a TXRF detection limit for uranium in contaminated water of 0.30 µg/g was achieved.     

Analysis of ultrasonic welding process of mild steel and 5052 aluminium alloy

Ultrasonic welding of mild steel sheet (SPCC) and aluminium alloy sheet (A5052) was conducted using two different weld tips of a knurled tip (K-tip) and a curved shape tip without knurled edges (C-tip). Behaviours of the weld tip and the welded materials during the weld process were analysed using a high-speed camera observation and an image correlation. The C-tip welding shows a completely different displacement behaviour from the K-tip welding; a relative motion between the tool tip and A5052 in contact with the tip predominantly occurs in the C-tip in contrast to a relative motion between A5052 and SPCC observed in the K-tip. The joint strength using the C-tip was higher than that using the K-tip under the weld conditions in this study. It is demonstrated that the relative motion behaviour in the C-tip causes a macroscopic deformation of A5052 in the vibration direction. This phenomenon promotes growth of a bonded region, resulting in the increase of joint strength. It is surmised that Fe–Al intermetallic layer forms at the weld interface, and the joint strength consequently decreases for the longer weld time condition.     

Effect of substituting elements on hydrogen uptake for Pd–Rh–H and Pd–Ag–H systems evaluated by magnetic susceptibility measurement

The magnetic susceptibility and the pressure-composition isotherm were measured simultaneously for Pd–Rh–H and Pd–Ag–H systems in order to clarify the effect of Rh or Ag substitution on the hydrogen uptake from viewpoint of the electronic band structure. The magnetic susceptibility of all Pd binary alloys prepared decreased monotonically with increasing hydrogen content. At high hydrogen contents, the magnetic susceptibility became approximately zero for Pd–Rh–H and Pd–Ag–H system, and the hydrogen content at which the magnetic susceptibility gives zero corresponded with the terminal of the plateau region in the isotherm curve. The results indicated that the magnetic susceptibility of hydride phase was almost zero for all Pd binary alloys. On the basis of the band structure of Pd metal, we concluded that atom substitution only affected shift of the energy at Fermi level, and the amount of the hydrogen uptake was dominated by the number of unoccupied d-band in the alloys.     

A method to modify coordinates of detectors in positron emission tomography systems

A new method to modify coordinates of detectors in any positron emission tomography (PET) system using a radioactive point source is developed. This method is based on selecting a centered detector in each detector block of PET and measuring coincidence counts between the two centered detectors in opposite detector blocks to find the coordinates of their LOR (Line of Response). Due to slight misalignment of detector positions, measured LORs may not intersect at a single point. Based on the proposed method, the coordinates of detectors can be measured with very high accuracy and the coordinate of the center of the gantry (which is normally the same as the center of field of view) can be defined correctly. The results of the application of our method to a small animal PET system (FinePET), which was recently developed at Tohoku University, Japan, are shown here. The method is expected to contribute to the design and development of PET systems which can realize a very high spatial resolution of less than 1 mm FWHM.     

Alloying effects on the hydride formation of Zr(Mn1−xCox)2

To study the alloying effects on ZrMn₂-H system, thermodynamic properties of Zr(Mn_1−xCo_x)₂ hydride were measured by volumetric method. ZrMn₂ gave a single plateau region in the pressure-composition isotherm. On the other hand, double plateaus were clearly observed in Zr(Mn_0.7Co_0.3)₂ and Zr(Mn_0.6Co_0.4)₂-H systems. The appearance of the double plateau characteristics would be explained in view of the hydrogen binding in the tetrahedral occupation sites in Zr(Mn_1−xCo_x)₂. Since the hydrogen binding in the tetrahedral 2ZrMnCo site would be less stable than that in the 2Zr2Mn site, the equilibrium pressure increases with increasing cobalt content. The appearance of the first plateau was ascribed the increase in the bonding of Mn-H in 2Zr2Mn site adjoining the 2ZrMnCo site.     

Capacitor discharge percussion welding of pure aluminum wire to pure copper sheet

This paper presents the results of a research into capacitor discharge percussion welding (CDPW) of pure aluminum wires and pure copper sheets, using percussion welding power and special welding device. A lot of CDPW factors, which will affect aluminum and copper dissimilar bonding, are described and these parameters have also been optimized. The fracture pull, inter'ace compounds, microstructure and hardness are all studied. The results show that aluminum wire welding to copper sheet can form a sound weld and in some conditions the fracture pull is similar to that of the pure aluminum wires. The capacitance, discharge voltage, wire taper angle and machine oil as welding assistant medium affect fracture pull. The intermetallic compounds Al2 Cu appears on the copper side of joint. Narrower heat-affected zone is observed.