Mineral reaction and morphology change during gasification of coal in CO2 at elevated temperatures

Studies of the gasification of char in CO₂ at elevated temperatures are necessary for the development of IGCC technology. Experiments at high heating rates and elevated temperatures revealed that the temperature dependence of gasification reactivity was very different for low compared with high temperature ranges. To elucidate these mechanisms, the reaction of mineral matter and the change in morphology during gasification of a char at elevated temperatures were examined by char characterisation. CO₂ gasification experiments showed a large difference in gasification rate for chars prepared at higher temperatures compared to those prepared at lower temperatures. Changes in char particle morphology and mineral matter during gasification are also quite different. At higher carbonisation temperatures, mineral reactions during pyrolysis, which occurs in addition to ash fusion, appear to be one of the factors accounting for these differences. Certainly, a change of mechanism is involved. Graphite enrichment may also contribute to the decrease in char reactivity.     

Passband-width broadening design for WDM filter with lattice-forminterleave filter and arrayed-waveguide gratings

We successfully fabricated a high channel count and flat-top wavelength-division-multiplexing filter by integrating a waveguide-type interleave filter and two arrayed-waveguide grating on one chip. Optimizing the loss ripple of the interleave filter, we realized a 50-GHz spacing, 102-channel ports, a 1-dB passband of 30 GHz, and an insertion loss of 4 dB     

高速、高精度数控伺服工作台摩擦误差的研究

建立了一种考虑摩擦影响的PID控制下的高速、高精度进给伺服工作台的数学模型。伺服机构中的摩擦力是采用一种“两维混合摩擦模型”来描述的。该模型可以根据滑动速度、表面接触物体的油膜厚度等计算摩擦力。通过数值仿真与实际测量 ,在大范围的工况下 ,研究了圆运动过象限时出现凸起的误差现象。通过计算与试验结果的比较 ,证明了提出的考虑摩擦影响的数学模型能够精确地模拟PID控制下的高速、高精度进给伺服工作台的动力学过程 ,能够正确地预测进给运动过程中摩擦误差大小及特征。     

Molecular composition of the 16S toxin produced by a Clostridium botulinum type D strain, 1873

The 16S toxin was purified from a Clostridium botulinum type D strain 1873 (D-1873). Furthermore, the entire nucleotide sequences of the genes coding for the 16S toxin were determined. It became clear that the purified D-1873 16S toxin consists of neurotoxin, nontoxic nonhemagglutinin (NTNH), and hemagglutinin (HA), and that HA consists of four subcomponents, HA1, HA2, HA3a, and HA3b, the same as type D strain CB16 (D-CB16) 16S toxin. The nucleotide sequences of the nontoxic components of these two strains were also found to be identical except for several bases. However, the culture supernatant and the purified 16S toxin of D-1873 showed little HA activity, unlike D-CB16, though the fractions successively eluted after the D-1873 16S toxin peak from an SP-Toyopearl 650S column showed a low level of HA activity. The main difference between D-1873 and D-CB16 HA molecules was the mobility of the HA1 on sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). Therefore it was presumed that the loss of HA activity of D-1873 16S toxin might be caused by the differences of processing HA after the translation.     

Oligo-2',5'-adenylate synthetase in pulmonary sarcoidosis and idiopathic pulmonary fibrosis

Oligo-2',5'-adenylate synthetase (2,5AS) is an enzyme induced by all types of interferon (IFN). We measured the levels of 2,5AS activity in peripheral blood mononuclear leukocytes (PBML) and bronchoalveolar lavage fluid (BALF) cells of patients with pulmonary sarcoidosis (SAR), idiopathic pulmonary fibrosis (IPF), and normal controls (NC). In NC, the levels of BALF cell 2,5AS activity were approximately seven times as high as the levels of PBML 2,5AS activity. The measurement 2,5AS activity from isolated cells showed that the levels of 2,5AS activity are independent of cell differential from PBML and BALF cells. The levels of PBML and BALF cell 2,5AS activity in SAR were both significantly high in comparison with those in NC. In patients with IPF, the levels of PBML 2,5AS activity were significantly increased as compared with those in NC, whereas there was no significant difference regarding the levels of BALF cell 2,5AS activity between patients with IPF and NC. These results suggest the following: (1) in patients with SAR, IFN production is enhanced both in the alveolar space and peripheral circulation; (2) in patients with IPF, IFN production is greatly enhanced in the circulation, whereas IFN production is not enhanced in the alveolar space; and (3) IFN may contribute to the pathogenesis of SAR and IPF.     

Oxygen potentials of (U,Gd)O2 ± x solid solutions in the temperature range 1000–1500°C

Oxygen potentials of U_0.86Gd_0.14O_{2 ± x} and U_0.73Gd_0.27O_{2 ± x} solid solutions, together with UO_{2 ± x}, have been measured at 1000, 1300 and 1500°C by using a thermogravimetric technique. The results at 1000°C show good agreement with the results of a previous solid electrolyte galvanic cell measurement. The oxygen potentials for the solid solutions increase positively with increasing Gd content. Stable hypostoichiometric phases are seen at the oxygen potentials below ?65 and ?50 kcal/mol between 1000 and 1500°C for U_0.86Gd_0.14O₂ and U_0.73Gd_0.27O₂, respectively. From the oxygen partial pressure dependence of x, models for the defect structure in hyper- and hypostoichiometric solid solutions are suggested.     

Thermodynamic properties of nonstoichiometric urania-gadolinia solid solutions in the temperature range 700–1100° C

Partial molar thermodynamic quantities for urania-gadolinia solid solutions of compositions U_1−yGd_yO_2+x, with y values of 0.04 to 0.27, have been obtained using a solid electrolyte galvanic cell technique. The measurements were made for O/M ratios ranging from near stoichiometry to 2.20, and for temperatures ranging from 700 to 1100°C. The results for pure UO_2+x are in accordance with data reported earlier. The oxygen potentials for U_1−yGd_yO_2+x are higher than for pure UO_2+x and increase positively with increasing Gd content or excess oxygen. They can be represented as a function of the mean U valence, except at the stoichiometric composition. Both the partial molar entropy and enthalpy increase negatively with increasing Gd content or excess oxygen.     

Fullerenes in chinese Ink. A Correction

Re-determination of fullerenes in Chinese ink sticks and their raw soots by reverse-phase HPLC analysis revealed much smaller contents of C₆₀ and C₇₀ than previously reported, 3 ppm at most. The older sticks tend to yield less C₆₀ than the more recent ones.     

Rapid fabrication of nanoparticles array on polycarbonate membrane based on positive dielectrophoresis

We report here a rapid formation of island arrays with nanoparticles on and within polycarbonate (PC) membrane based on positive dielectrophoresis (p-DEP). For the fabrication of the patterning device, PC membranes with 10 μm thickness and 100, 200 or 400 nm pore size were sandwiched by an upper bare ITO substrate and a lower disk array ITO electrode which was defined by insulation layer of negative photoresist. A suspension of 190 nm diameter polymethylmethacrylate (PMMA) particles containing rhodamine 6G (R6G) fluorescent molecules was introduced into the device between the upper ITO and the PC membrane. AC electric signal (typically 20 Vpp, 70 kHz) was then applied to the ITO, resulting in the formation of island patterns with high electric fields gradient regions on and in the PC membrane. Particles patterns with island shape were assembled on membrane within 1 s after applying AC electric field. The electrodes can be used repeatedly as the template of subsequent patterning. Although, particles islands were only formed on the PC membrane with 100 and 200 nm diameter pores, the particles penetrated the membrane with 400 nm pores to form patterns on the back surface. Since the strong electric fields were formed at the edges of disks, particles on the back surface were the projection of the disk array of ITO to form ring shapes. The unique structure with particles was explained based on the simulation of electric field distribution. The present proposal offers a procedure to fabricate particle arrays with extremely simple, rapid and highly reproducible manner.     

Development of a new tool to generate compressive residual stress within a machined surface

Generally, critical machined parts such as aircraft parts require high fatigue strength and resistance to stress corrosion cracking. These machined parts almost all usually have tensile residual stress within the machined surface after milling. However, if the compressive residual stress within the machined surface can be obtained by a milling process alone, it is expected that fatigue strength and resistance to stress corrosion cracking of the machined components will be improved. The purpose of this study is to develop a new tool that can generate compressive residual stress within the machined surface concurrently with the milling process. This tool has cutting edges for material removal and a projection pin for a burnishing-like process. It was shown that the proposed cutter could generate effective compressive residual stress within the machined surface during the milling process. Residual stress levels were in the region of −100 to −200 MPa on the machined surface, and −300 to −400 MPa at 0.05 mm beneath the surface. These levels are almost comparable with those obtained by the shot peening process.