多晶YAG陶瓷的制备及力学性能

本实验采用共沉淀方法制备YAG微粉 ,Al和Y元素分布均匀 ,在 90 0℃煅烧 2h即可全部转变为YAG粉体 ,无过渡相 .15 0 0℃热压 1h可获得致密烧结体 ,其抗弯强度为 2 45MPa ,断裂韧性为 2 .0MPa·m1 /2 ,晶粒大小为 3～ 6μm ;14 0 0℃放电等离子烧结 5min可获得相对密度为 93 %的烧结体 ,其抗弯强度为 3 4 8MPa,断裂韧性为 2 .1MPa·m1 /2 ,晶粒大小为 1～ 2 μm .     

Formation of False Context Fear Memory Is Regulated by Hypothalamic Corticotropin-Releasing Factor in Mice

Traumatic events frequently produce false fear memories. We investigated the effect of hypothalamic corticotropin-releasing factor (CRF) knockdown (Hy-Crf-KD) or overexpression (Hy-CRF-OE) on contextual fear memory, as fear stress-released CRF and hypothalamic–pituitary–adrenal axis activation affects the memory system. Mice were placed in a chamber with an electric footshock as a conditioning stimulus (CS) in Context A, then exposed to a novel chamber without CS, as Context B, at 3 h (B-3h) or 24 h (B-24h). The freezing response in B-3h was intensified in the experimental mice, compared to control mice not exposed to CS, indicating that a false fear memory was formed at 3 h. The within-group freezing level at B-24h was higher than that at B-3h, indicating that false context fear memory was enhanced at B-24h. The difference in freezing levels between B-3h and B-24h in Hy-Crf-KD mice was larger than that of controls. In Hy-CRF-OE mice, the freezing level at B-3h was higher than that of control and Hy-Crf-KD mice, while the freezing level in B-24h was similar to that in B-3h. Locomotor activity before CS and freezing level during CS were similar among the groups. Therefore, we hypothesized that Hy-Crf-KD potentiates the induction of false context fear memory, while Hy-CRF-OE enhances the onset of false fear memory formation.     

Color restoration method based on spectral information using normalized cut

This paper proposes a novel method for color restoration that can effectively apply accurate color based on spectral information to a segmented image using the normalized cut technique. Using the proposed method, we can obtain a digital still camera image and spectral information in different environments. Also, it is not necessary to estimate reflectance spectra using a spectral database such as other methods. The synthesized images are accurate and high resolution. The proposed method effectively works in making digital archive contents. Some experimental results are demonstrated in this paper.     

日本の寒地，北海道におけるうるち米粒外観品質の育種（日文）（网络首发、推荐阅读）

北海道では旧来，米粒外観品質を東北以南に遜色ない程度まで向上させるため，乳白，腹白などの未熟粒が少なく整粒歩合や玄米と精米の白度が高くなるように，主に達観により選抜を行ってきた。その結果，1903年以降に育成された新旧品種では，整粒は育成年次が新しいほど概して多く，未熟粒，被害粒および着色粒は減少した。とくに，1961年育成の「ユーカラ」は，整粒歩合が同時代や以前の品種に比べ顕著に高く，系譜からみてその良質性はその後に育成された良質良食味米品種に受け継がれた。1984年以降に育成された主要品種は東北以南の銘柄米品種に比べ，整粒歩合がやや低く未熟粒歩合はやや高かった。玄米と精米の白度は，1971年より前の育成品種では腹白粒等の混入が多く，それが白度を上げるため育成年次と一定の関係が無かった。それ以降，両白度は新しい品種ほど高くなり，精米蛋白質含有率が低いほど高い傾向があった。現在の主要品種は東北以南の銘柄米品種に比べ，玄米白度はやや劣るが，精米白度，玄米透明度および精米透明度には明確な差異が無かった。さらに，整粒のみの玄米白度では，差異はなかった。以上から，現在の北海道主要品種の米粒外観品質は，東北以南銘柄米品種に比べ未熟粒がやや多く整粒がやや少ないことを除き，明確な違いはなくなった。     

Simulation of densification behavior of nano-powder in final sintering stage: Effect of pore-size distribution

In the final sintering stage, nano-sized powder frequently forms a pore structure where most pores are surrounded by more than 5 grains. The pore structure is different from that of coarse powder. In this study, the densification behavior of nano-sized powder is modelled and simulated in the final sintering stage. The porous body has the initial size distribution of pores, represented as a Weibull function. The mechanical interaction between pores is analyzed to simulate the evolution of porosity characteristics as well as densification kinetics. The densification rate for the size-distributed pores is lower than that for single-sized ones. The experimental relationship between the densification rate and the porosity could well be reproduced by choosing appropriate pore-size distributions. The simulation also shows that the sintering stress with densification may increase or decrease depending on the size distribution, but is remarkably lower than that for single-sized pores.     

The effect of stimulus duration on the luminous efficiency functions for brightness

Spectral luminous efficiency functions were obtained by direct heterochromatic brightness matching for four different stimulus durations: namely, 10-ms, 200-ms, 1-s, and continuous presentation. The functions clearly changed in their shape, depending on the stimulus duration for two of three subjects. They showed usual double peaks at about 540 and 600 nm, which were greatly enhanced when the duration was 1 s. The enhancement decreased both with longer and shorter duration. Linear combinations of cone outputs model was applied to our results. The logR-logG type mechanism in the long-wavelength region and the logG-logR-logB type mechanism in the middle-wavelength region were found for brightness perception. For the short-wavelength region, by lifting up the short-wavelength portion of the logR-logG mechanism, luminous efficiency functions could be expressed. In the long- and middle-wavelength region, the effects of the stimulus duration were explained by changing the negative input (originating from R or G cones) to the positive input as the stimulus duration increased from 10 ms to 1 s. The amount of the short-wavelength sensitive cones' contribution in the middle-wavelength region were small and there were no systematic changes for the stimulus durations. For the short-wavelength region, the amount of the shift of the logR-logG type mechanism was largest at the 1-s duration.     

Site-directed mutagenesis of the putative active site residues of 3C proteinase of coxsackievirus B3: evidence of a functional relationship with trypsin-like serine proteinases

Picornavirus 3C proteinases (3C^pro) are cysteine proteinasesbut recent sequence analyses have shown that they are relatedto trypsin-like serine proteinases. Two models of 3C^pro structurehave been presented. Both models indicate that residues His40and Cysl47 are members of the catalytic triad but the modelsdiffer in the designation of the third member of the catalytictriad, which is assigned as either Glu71 or Asp85. To test theimportance of these four residues in the catalytic activityof 3C^pro of coxsackievirus B3, a member of the enterovirus subgroupof the picornavirus family, single amino acid substitutionswere introduced at each of the four sites. All of these mutationsresulted in the reduction or inactivation of autocatalytic cleavageof the 3C precursor protein expressed in Escherichia coli, suggestingthat all of these residues are essential for the proteolyticreaction. The substitution of Cysl47 with Ala abolished 3C^proactivity while the mutant in which Cysl47 was replaced withSer retained reduced proteolytic activity both in cis and intrans. Our results strongly support the proposal that Cysl47of 3C^pro functions as a nucleophile analogous to Serl95 of trypsin-likeserine proteinases.     

Sensitivity Analysis in Multidimensional Scaling

A sensitivity analysis method for eigenvalue problems in multivariate analysis was proposed by De Sarbo, et al. (1982) and developed by Ueda (1988). Metric multidimensional scaling (MDS) is a spectral decomposition of symmetric matrices, where eigenvalues and eigenvectors play important roles. It is shown that the ε -neighborhood vectors defined in Ueda (1988) give the 2ε-neighborhood vectors for the goodness-of-fit index in a spectral decomposition. Considering this fact and using the same method as Ueda (1988), sensitivity for metric MDS is discussed.

     

Quality assessment models for initial production process control based on stochastic differential equations

It is of great importance to assess an initial production process prior to the regular mass-production. For this purpose, many statistical methods have been proposed for practical use. In this paper, we propose two stochastic models for an assessment method of the initial production process control: a Markov process model and a Markov approximation model. These models are continuous state space models and formulated by applying mathematical techniques of stochastic differential equations. Based on each model, we derive several quantitative assessment measures for initial production process control.