化学教育における平衡をめぐる理解と誤解について

この論文では，中等高等化学教育における平衡の理解をすすめ指導法を改良するため，平衡に関連してみられる疑問や誤解や思い違いをひろくとりあげ，検討する。生徒や学生が正確に教えられていないことを示唆する思い違い，模型を採用することで生まれる誤謬，動的平衡の歴史的な文献の記述にみられる誤解の伝播，古い化学の解釈を現代化学にそのまま持ち込む誤謬，表記法があいまいなため生まれる誤解，などである。まず，平衡の確認方法を取り上げる。ここでは，系の停留性と可逆性と復帰性の意味や，系の小部分間の相互作用の理解が要点であることを示す。次に，平衡の表現法を述べる。熱力学的法則や古典的化学平衡定数にふれ，質量作用の法則に関連する誤解のゆえんを分析する。最後に，動的平衡の理解と誤解について述べる。動的平衡の説明において，演示用化学実験のみならず，よく引用される同位体交換反応実験には，うっかりする落穴があることを指摘する。こうして，化学教育において，平衡と化学平衡の何を教授し，どこに注意をはらうべきかをあきらかにしようと試みる。The concept of equilibrium in chemistry education is put forward for consideration from a standing point of view such that: It is not taught correctly to students so that several misconceptions occur; using models for it makes some mistakes; many misunderstandings in the old chemistry and in the historical literature are now circulating in modern chemistry, and so on. This paper shows that: First, a method for confirming state of equilibrium needs to understand termination, reversibility, returnability, and interaction between subsystems. Secondly, representation of equilibrium relates to the second law of thermodynamics, the classical chemical equilibrium constant, and the law of mass action. Last, there are understandings and misunderstandings of dynamic equilibrium in both chemical experiments for student demonstration and interpretation of isotope-exchange reaction. We thus try to clarify how chemical educators should pay attention to what is taught in both equilibrium and chemical equilibrium

Magnetic Full-Heusler Compounds for Thermoelectric Applications

Full-Heusler compounds exhibit a variety of magnetic properties such as non-magnetism, ferromagnetism, ferrimagnetism and anti-ferromagnetism. In recent years, they have attracted significant attention as potential thermoelectric (TE) materials that convert thermal energy directly into electricity. This chapter reviews the theoretical and experimental studies on the TE properties of magnetic full-Heusler compounds. In Section 1, a brief outline of TE power generation is described. Section 2 introduces the crystal structures and magnetic properties of full-Heusler compounds. The TE properties of full-Heusler compounds are presented in Sections 3 and 4. The relationship between magnetism, TE properties and order degree of full-Heusler compounds is elaborated

PAX6 isoforms, along with reprogramming factors, differentially regulate the induction of cornea-specific genes

PAX6 is the key transcription factor involved in eye development in humans, but the differential functions of the two PAX6 isoforms, isoform-a and isoform-b, are largely unknown. To reveal their function in the corneal epithelium, PAX6 isoforms, along with reprogramming factors, were transduced into human non-ocular epithelial cells. Herein, we show that the two PAX6 isoforms differentially and cooperatively regulate the expression of genes specific to the structure and functions of the corneal epithelium, particularly keratin 3 (KRT3) and keratin 12 (KRT12). PAX6 isoform-a induced KRT3 expression by targeting its upstream region. KLF4 enhanced this induction. A combination of PAX6 isoform-b, KLF4 and OCT4 induced KRT12 expression. These new findings will contribute to furthering the understanding of the molecular basis of the corneal epithelium specific phenotype

Environmental impact on star-forming galaxies in a z∼0.9z \sim 0.9 cluster during course of galaxy accretion

Galaxies change their properties as they assemble into clusters. In order to understand the physics behind that, we need to go back in time and observe directly what is occurring in galaxies as they fall into a cluster. We have conducted a narrow-band and $J$-band imaging survey on a cluster CL1604-D at $z=0.923$ using a new infrared instrument SWIMS installed at the Subaru Telescope. The narrow-band filter, NB1261, matches to H$\alpha$ emission from the cluster at $z=0.923$. Combined with a wide range of existing data from various surveys, we have investigated galaxy properties in and around this cluster in great detail. We have identified 27 H$\alpha$ emitters associated with the cluster. They have significant overlap with MIPS 24$\mu$m sources and are located exclusively in the star forming regime on the rest-frame $UVJ$ diagram. We have identified two groups of galaxies near the cluster in the 2D spatial distribution and the phase-space diagram, which are likely to be in-falling to the cluster main body. We have compared various physical properties of star forming galaxies, such as specific star formation rates (burstiness) and morphologies (merger) as a function of environment; cluster center, older group, younger group, and the field. As a result, a global picture has emerged on how the galaxy properties are altered as they assemble into a denser region. This includes the occurrence of mergers, enhancement of star formation activity, excursion to the dusty starburst phase, and eventual quenching to a passive phase.Comment: 19 pages, 15 figures. Accepted for publication in ApJ. Error bars in Table 2 correcte

Coordinated generation of multiple ocular-like cell lineages and fabrication of functional corneal epithelial cell sheets from human iPS cells

We describe a protocol for the generation of a functional and transplantable corneal epithelium derived from human induced pluripotent stem (iPS) cells. When this protocol is followed, a proportion of iPS cells spontaneously form circular colonies, each of which is composed of four concentric zones. Cells in these zones have different morphologies and immunostaining characteristics, resembling neuroectoderm, neural crest, ocular-surface ectoderm, or surface ectoderm. We have named this 2D colony a 'SEAM' (self-formed ectodermal autonomous multizone), and previously demonstrated that cells within the SEAM have the potential to give rise to anlages of different ocular lineages, including retinal cells, lens cells, and ocular-surface ectoderm. To investigate the translational potential of the SEAM, cells within it that resemble ocular-surface epithelia can be isolated by pipetting and FACS sorting into a population of corneal epithelial-like progenitor cells. These can be expanded and differentiated to form an epithelial layer expressing K12 and PAX6, and able to recover function in an animal model of corneal epithelial dysfunction after surgical transplantation. The whole protocol, encompassing human iPS cell preparation, autonomous differentiation, purification, and subsequent differentiation, takes between 100 and 120 d, and is of potential use to researchers with an interest in eye development and/or ocular-surface regeneration. Experience with human iPS cell culture and sorting via FACS will be of benefit for researchers performing this protocol

Experimental Rugged Fitness Landscape in Protein Sequence Space

The fitness landscape in sequence space determines the process of biomolecular evolution. To plot the fitness landscape of protein function, we carried out in vitro molecular evolution beginning with a defective fd phage carrying a random polypeptide of 139 amino acids in place of the g3p minor coat protein D2 domain, which is essential for phage infection. After 20 cycles of random substitution at sites 12–130 of the initial random polypeptide and selection for infectivity, the selected phage showed a 1.7×10(4)-fold increase in infectivity, defined as the number of infected cells per ml of phage suspension. Fitness was defined as the logarithm of infectivity, and we analyzed (1) the dependence of stationary fitness on library size, which increased gradually, and (2) the time course of changes in fitness in transitional phases, based on an original theory regarding the evolutionary dynamics in Kauffman's n-k fitness landscape model. In the landscape model, single mutations at single sites among n sites affect the contribution of k other sites to fitness. Based on the results of these analyses, k was estimated to be 18–24. According to the estimated parameters, the landscape was plotted as a smooth surface up to a relative fitness of 0.4 of the global peak, whereas the landscape had a highly rugged surface with many local peaks above this relative fitness value. Based on the landscapes of these two different surfaces, it appears possible for adaptive walks with only random substitutions to climb with relative ease up to the middle region of the fitness landscape from any primordial or random sequence, whereas an enormous range of sequence diversity is required to climb further up the rugged surface above the middle region

The Quiescent Intracluster Medium in the Core of the Perseus Cluster

Clusters of galaxies are the most massive gravitationally-bound objects in the Universe and are still forming. They are thus important probes of cosmological parameters and a host of astrophysical processes. Knowledge of the dynamics of the pervasive hot gas, which dominates in mass over stars in a cluster, is a crucial missing ingredient. It can enable new insights into mechanical energy injection by the central supermassive black hole and the use of hydrostatic equilibrium for the determination of cluster masses. X-rays from the core of the Perseus cluster are emitted by the 50 million K diffuse hot plasma filling its gravitational potential well. The Active Galactic Nucleus of the central galaxy NGC1275 is pumping jetted energy into the surrounding intracluster medium, creating buoyant bubbles filled with relativistic plasma. These likely induce motions in the intracluster medium and heat the inner gas preventing runaway radiative cooling; a process known as Active Galactic Nucleus Feedback. Here we report on Hitomi X-ray observations of the Perseus cluster core, which reveal a remarkably quiescent atmosphere where the gas has a line-of-sight velocity dispersion of 164+/-10 km/s in a region 30-60 kpc from the central nucleus. A gradient in the line-of-sight velocity of 150+/-70 km/s is found across the 60 kpc image of the cluster core. Turbulent pressure support in the gas is 4% or less of the thermodynamic pressure, with large scale shear at most doubling that estimate. We infer that total cluster masses determined from hydrostatic equilibrium in the central regions need little correction for turbulent pressure.Comment: 31 pages, 11 Figs, published in Nature July