Preparation of Lead Lanthanum Zirconate Titanate (PLZT, (Pb,La)(Zr,Ti)O3) Fibers by Sol-Gel Method

Lead lanthanum zirconate titanate (PLZT, (Pb,La)(Zr,-Ti)O₃) ceramic fibers were prepared by the sol-gel method from a solution of lead acetate trihydrate, lanthanum isopropoxide, zirconium n -propoxide, and titanium isopropoxide that contained 2-methoxyethanol as the solvent. The sols obtained from the solution were concentrated at 156°-174°C for 2 h. Concentration at higher temperatures resulted in more-viscous sols of higher specific gravities. The concentration resulted in the formation of spinnable sols, which had viscosities >10⁵ mPas and exhibited Newtonian flow properties. These spinnable sols were formed to be so stable that no change in viscosity and spinnability was observed for more than three months when stored in a sealed container at room temperature. Gel-to-ceramic fiber conversion was investigated by means of X-ray diffractometry, infrared spectroscopy, and thermal analysis. Single-phase perovskite PLZT ceramic fibers 5-200 μm in diameter and >20 cm in length were obtained. Scanning electron microscopy (SEM) observation and Brunauer-Emmett-Teller (BET) measurement showed that heat treatment of the fibers at a lower rate resulted in the formation of fibers of denser microstructure. Although the SEM image of the cross section of the fibers revealed a relatively dense microstructure and a laser beam could be transmitted through a fiber 6 mm in length, BET measurement of the fibers indicated that the fibers had more than a few percent of open porosities, and scattering of light was observed in the laser-beam guiding test.     

The effect of a new type of pin mixing section on the performance of a single-screw extruder

The effect of a holed-pin mixing section on the performance of a single screw extruder was investigated and compared with a free flight and a normal pin mixing section, using a practical single-screw extruder. The effect of axial distance between two pins in a holed-pin mixing section on performance was also studied. Mixing ability was quantified using the statistical approach of carbon black concentration distribution in the extruded film mixed with a carbon black masterbatch. The results indicate that a free flight gives the lowest melt temperature rise, pressure drop, and driver power, but the worst mixing; a holed-pin mixing section has better mixing ability, lower melt temperature rise, and lower driver power than a normal pin mixing section does; the value of the pressure drop of the two types of pin mixing sections is approximately identical. A longer axial distance between the two pins in a holed-pin mixing section gives better mixing and lower melt temperature rise than a shorter one; however, when the distance is longer than a critical value, the improvement of mixing is not so outstanding; for different axial distances between two pins, no great change in pressure drop was found and the extrusion throughput has almost no great relation to the axial distance.     

Measurement of the Flexural Modulus of Chopped Carbon Fiber Tape Reinforced Thermoplastic with Short Beams

Applied Composite Materials - Increasing application scenarios of fiber reinforced composites pose more requirements for methodology of evaluating the material characteristics. Conventional...     

Working with robots in disasters

The Robot World Cup Initiative (RoboCup) is an international research and education initiative. It was started in order to foster artificial intelligence search. RoboCupRescue's domain is search and rescue operations in urban disasters. The RoboCup Rescue league consists of two projects: the simulation project and the robotics and infrastructure project. A multi-agent-based approach to disaster simulation provides many research themes and supports rescue operations in real situations. Simulation Project, not only agent implementation, but also the evaluation of the social agents' performance, the architecture of the distribution system, and the quality of communications, etc. The following features are important in this project to promote the research and provide verification methods.     

Optimum design of a grazing-incidence flat-field spectrograph with a spherical varied-line-space grating

A grazing-incidence spectrograph is designed by use of the flat-field image-focusing property of a spherical varied-line-space grating. Optimum grating parameters for mechanical ruling are selected by application of genetic algorithms. Two gratings, one for 2-5-nm and the other for 5-20-nm spectral regions, are designed, and their fabrication tolerances are analyzed.     

Electronic structures of hydrogen storage compound, TiFe

The electronic structures of TiFe hydrogen storage compound containing a variety of alloying elements, M, are investigated by the DV-X cluster method in order to understand alloying effects on the hydrogen absorption and desorption characteristics of this compound. It is found that hydrogen atoms make a strong chemical bond with Fe atoms rather than Ti atoms in pure TiFe, despite the larger affinity of Ti atoms for hydrogen than Fe atoms in the binary metal–hydrogen system. It is also shown that the nature of the chemical bond between the constituent atoms determines the stability of TiFe hydrides. For example, the ratio of the Fe(M)–Ti bond order to the Ti–Ti bond order correlates well with the experimental data of the equilibrium plateau pressure of hydrogen.     

氘团簇离子（d^＋3）与固体相互作用过程中的团簇行为研究

讨论了由三个氘原子组成的氘团簇离子束与独立氘离子束在轰击固体靶时,在原子过程呼Ｄ－Ｄ核聚变过程中体现出的差别。对氘团簇与固体靶相互作用的机理进行了分析。     

Developmental competence, after transfer to recipients, of porcine oocytes matured, fertilized, and cultured in vitro

The objective of this study was to evaluate the developmental ability of early porcine embryos produced in vitro and transferred to recipient gilts. Porcine cumulus-oocyte complexes were matured in modified North Carolina State University-37 solution for 44-46 h (in vitro maturation, IVM). In vitro fertilization (IVF) was performed with frozen-thawed epididymal spermatozoa. Inseminated oocytes were cultured in vitro (IVC) for 0, 24, or 48 h in modified NCSU-37 solution. Embryos were surgically transferred to the oviducts of recipients in which estrus had been synchronized with eCG and hCG. On the 29th day post-IVF, the uteri of some recipients were surgically examined for pregnancy; then pregnant females were hysterectomized in order to examine number and weight of the fetuses. Developmental rates to fetuses for IVM/IVF oocytes cultured for 24 and 48 h were significantly lower (p < 0.05, 1.7% and 2.0%, respectively) than that of IVM/IVF oocytes without IVC (6.7%). However, the weights of fetuses (1.0-1.2 g) did not differ among the experimental groups. The other recipients were examined for pregnancy using an ultrasound pregnancy detector, and pregnant females were allowed to go to term. Healthy piglets were delivered by some recipients to which embryos cultured for 0 or 24 h had been transferred; however, no farrow was obtained from embryos cultured for 48 h before the transfer. The results indicate that the viability of in vitro-produced porcine embryos is decreased by IVC after IVF; however, these embryos have competence to develop to term. An improved IVC system of porcine IVM/IVF oocytes is needed to generate advances in this field.