Effects of Thermal Annealing on Formation of Micro Porous Titanium Oxide by the Sol–Gel Method

We investigated the structural and optical properties of microporous titanium oxide (TiO₂) fabricated by the sol–gel method using templates of colloidal crystals with polystyrene spheres when the annealing temperature was changed between 600° and 1000°C. From X-ray diffraction patterns and SEM images, the rutile TiO₂ annealed at a high temperature did not form periodic porous bodies, while the anatase TiO₂ annealed at lower than 800°C formed periodic porous bodies. The porous TiO₂ obtained acts as an air-sphere/TiO₂ photonic crystal with an FCC structure. It is suggested that TiO₂ sol annealed at a lower temperature do not lead to phase transition from the anatase phase to the rutile phase to obtain the air-sphere/TiO₂ photonic crystal by the sol–gel method using templates of colloidal crystals.     

Early chick limb cartilaginous elements possess polarizing activity and express hedgehog-related morphogenetic factors

Skeletal patterning and morphogenesis in the developing limb are thought to be regulated by instructive factors and cues from the zone of polarizing activity (ZPA), the apical ectodermal ridge (AER), and the dorsal ectoderm. However, the activities of the ZPA and AER dwindle early in embryogenesis and soon after ceases, when in fact the proximal skeletal elements are still rudimentary in structure and the more distal ones are yet to become recognizable. Thus, we asked whether the chondrocytes emerging within each mesenchymal condensation may themselves start expressing properties similar to those of ZPA and/or AER and, in so doing, may bring skeletal development to completion. Indeed, we found that the cartilaginous, but not precartilaginous, tissues in early chick limbs possess ZPA-like properties. They expressed an endogenous factor related to Sonic hedgehog (Shh), most likely Indian hedgehog (Ihh), and when fragments were grafted to the anterior margin of host stage 16-20 chick wing buds, they induced supernumerary skeletal elements (polarizing activity). The acquisition of polarizing activity by the cartilaginous structures followed clear proximo-to-distal and posterior-to-anterior routes. Thus, (1) stage 25 cartilaginous humerus had polarizing activity while stage 25 prospective radius did not, (2) posteriorly-located stage 29 ulna had stronger activity than anteriorly-located stage 29 radius, and (3) ulna's diaphysis had stronger activity at stage 29 than 31 while radius's diaphysis was stronger at stage 31 than 29. Prior to inducing extra digit formation, the cartilaginous grafts induced Hoxd-12 and Hoxd-13 gene expression in adjacent competent mesenchymal tissue. Strikingly, the cartilaginous grafts activity also expression of Shh and polarizing activity in adjacent mesenchyme, which ZPA grafts cannot do; thus, the cartilaginous structures displayed activities "upstream" of those of the ZPA. The results support our hypothesis that chondrocytes may themselves direct skeletal morphogenesis. In so doing and as a result of their inductive activities, the cells may also have an important role in the completion of limb patterning and morphogenesis.     

Fragmentation behavior during molten material and coolant interactions

A safe design for a fast breeder reactor (FBR) requires post-accident heat removal (PAHR) for any potential core disruptive accident (CDA). It is important to ensure that the molten core material solidifies in the sodium coolant in the reactor vessel even if all of the core material has melted. In the present experiment, molten material was injected into water to experimentally obtain the information on the molten material jet entering the coolant and its fragmentation. Visual information was obtained with a high-speed video camera, showing that fragmentation behavior on the side of the jet was different from that on the jet front, and that the injection nozzle diameter significantly influenced the jet breakup length, while the molten jet temperature and the coolant temperature did not influence the jet breakup length. Comparison of the diameters of fragments of the solidified molten material thus obtained with fragmentation theory shows that the median fragment diameter is between the critical Weber number theory and the most-unstable wavelength of the instability theory of surface waves at a gas liquid interface.The quench behavior of the molten jet in coolant was calculated for FBR conditions by using the model that reflects actual fragmentation behavior. It was clarified that the mass of molten material in the coolant pool is related to the fragment diameter under FBR conditions.     

Standard gibbs energy of formation of Mg<Subscript>48</Subscript>Zn<Subscript>52</Subscript> determined by solution calorimetry and measurement of heat capacity from near absolute zero kelvin

The thermodynamic properties of Mg₄₈Zn₅₂ were investigated by calorimetry. The standard entropy of formation at 298 K, Δ_f S ₂₉₈ ^o , was determined from measuring the heat capacity, C _p , from near absolute zero (2 K) to 300 K by the relaxation method. The standard enthalpy of formation at 298 K, Δ_f H ₂₉₈ ^o , was determined by solution calorimetry in hydrochloric acid solution. The standard Gibbs energy of formation at 298 K, Δ_f G ₂₉₈ ^o , was determined from these data. The obtained results were as follows: Δ_f H ₂₉₈ ^o (Mg₄₈Zn₅₂)=(−1214±(300) kJ · mol⁻¹;Δ_fS ₂₉₈ ^o (Mg₄₈Zn₅₂)=(−123±0.36) J · K⁻¹ · mol⁻¹; and Δ_f G ₂₉₈ ^o (Mg₄₈Zn₅₂)=(−1177±(300) kJ · mol⁻¹. The electronic contribution to the heat capacity of Mg₄₈Zn₅₂ was found to be approximately equal to pure magnesium, indicating that the density of states in the vicinity of the Fermi level follows the free electron parabolic law.     

Vibration analysis of cryocoolers

The vibrations of Gifford-McMahon (GM) and pulse-tube (PT) cryocoolers were measured and analyzed. The vibrations of the cold-stage and cold-head were measured separately to investigate their vibration mechanisms. The measurements were performed while maintaining the thermal conditions of the cryocoolers at a steady state. We found that the vibration of the cold-head for the 4 K PT cryocooler was two orders of magnitude smaller than that of the 4 K GM cryocooler. On the other hand, the vibration of the cold-stages for both cryocoolers was of the same order of magnitude. From a spectral analysis of the vibrations and a simulation, we concluded that the vibration of the cold-stage is caused by an elastic deformation of the pulse tubes (or cylinders) due to the pressure oscillation of the working gas.     

Microstructural damage evolution and arrest in binary Fe–high-Mn alloys with different deformation temperatures

We investigated the damage evolution behaviors of binary Fe–28–40Mn alloys (mass%) from 93 to 393 K by tensile testing. The underlying mechanisms of the microstructure-dependent damage evolution behavior were uncovered by damage quantification coupled with in situ strain mapping and post-mortem microstructure characterization. The damage growth behaviors could be classified into three types. In type I, the Fe–28Mn alloy at 93 K showed premature fracture associated with ductile damage initiation and subsequent quasi-cleavage damage growth associated with the \(\upvarepsilon \)-martensitic transformation. In type II, the Fe–28Mn alloy at 293 K and the Fe–32Mn alloy at 93 K showed delayed damage growth but did not stop growing. In type III, when the stacking fault energy was \(>\,\)19 \(\hbox {mJ/m}^{2}\), the damage was strongly arrested until final ductile failure.     

A case of progressive saccular aneurysm caused by localized dissection of descending aorta

A 37-year-old man with alcoholic polyneuropathy showed involuntary movement as intermittent flexion-extension or abduction-adduction of his toes identical to "painful legs and moving toes (PLMT)" and muscle cramps. Regarding the sequential spreading of PLMT and cramps from unilateral to contralateral leg muscles and phasic discharges observed by a needle EMG in the foot muscles during PLMT, we suppose that a spinal or supraspinal mechanism was responsible for the production of those movements. This case showed novel aspects of PLMT which was induced by sensory stimulation of the left lower leg and subsequently initiated cramps. The destruction of the lumbar sympathetic ganglion remarkably ameliorated the spontaneous PLMT and cramps, whereas sensory stimulation of the left lower leg still induced those movements. Therefore, we think that sensory inputs from peripheral nerves played a critical role in the generation of PLMT and cramps, and abnormal activities of spinal sympathetic nerves exacerbated those involuntary movements. Sensory induced PLMT may be a subgroup of this movement disorder.     

Electrorheological properties of poly(o-anisidine) and poly(o-anisidine)-coated silica suspensions

Poly(o-anisidine) (PANs) and PANs-coated silica particles were prepared by oxidative polymerization of o-anisidine using ammonium persulphate in the absence and presence of silica particles, respectively. The entire surface of the silica particles was completely covered with PANs polymerized using low concentration of o-anisidine. The effects on the electrorheological behavior of surface modification of the silica particles coated with PANs were studied under oscillatory shear. Electrorheological properties of PANs and PANs-coated silica particle suspensions were found to exhibit higher performance in nonaqueous solutions than those of silica particle suspensions even at high temperatures.     

The rejection of polar organic solutes in aqueous solution by an interpolymer anionic composite reverse osmosis membrane

Reverse osmosis separation for many kinds of polar organic solutes (alcohols, phenols, monocarboxylic acids, amines, and ketones) was examined by an anionic charged composite membrane. The solute permeation was carried out in single-solute aqueous solution (200 mg/L) under applied pressure of 7.88 MPa at 25°C. The correlation between the solute rejection and polar parameters for these organic solutes have been investigated. For n-alkyl alcohols, monocarboxylic acids, and ketones, the solute rejection increases with molecular weight and/or molecular branching. For undissociable polar organic solutes such as alcohols and ketones, solute rejections are closely related with the Taft's number. For dissociable polar organic solutes, solute rejections depend greatly upon the dissociation constant and the degree of dissociation of solute. This membrane showed higher rejection (80%) for phenol in an undissociated state at a 98% rejection level of NaCl. Also, rejections of phenolic derivatives depend upon the pH value of the feed solution and the polar effect of substituted groups. For acetic acid and methylamine, the solute rejection increases proportionally to the degree of dissociation of solute. From these facts, the main factors in reverse-osmosis separation by an anionic composite membrane are discussed.