Crystal structure of oxygen-evolving photosystem II at a resolution of 1.9 Å

Photosystem II is the site of photosynthetic water oxidation and contains 20 subunits with a total molecular mass of 350 kDa. The structure of photosystem II has been reported at resolutions from 3.8 to 2.9 ?. These resolutions have provided much information on the arrangement of protein subunits and cofactors but are insufficient to reveal the detailed structure of the catalytic centre of water splitting. Here we report the crystal structure of photosystem II at a resolution of 1.9 ?. From our electron density map, we located all of the metal atoms of the Mn(4)CaO(5) cluster, together with all of their ligands. We found that five oxygen atoms served as oxo bridges linking the five metal atoms, and that four water molecules were bound to the Mn(4)CaO(5) cluster; some of them may therefore serve as substrates for dioxygen formation. We identified more than 1,300 water molecules in each photosystem II monomer. Some of them formed extensive hydrogen-bonding networks that may serve as channels for protons, water or oxygen molecules. The determination of the high-resolution structure of photosystem II will allow us to analyse and understand its functions in great detail.     

Synthesis and Thermal Property of the Poly(silpheny-lenesiloxane)s with Functional Groups

1Introduction Silicon-containing polymers have been intensively studied in the past half-century, and a great number of papers, patents and books have been published on the synthesis, properties and applications. Silicon-containing polymers, especially polymers containing silicon atoms in the backbone, including some major species as polysiloxane, polysilane, polysilazane, etc. have chains constructed of alternately arranged silicon and oxygen atoms with organic groups attached to the silicon atoms, which are the most important silicon-containing polymers so far.     

Seasonal changes of circadian pattern in human rectal temperature rhythm under semi-natural conditions

A phase delay of the circadian rectal temperature rhythm existed in three human subjects leading normal lives under semi-natural conditions: the rectal temperature began to increase later in summer than in the other three seasons.     

Design of Electro-Functional Polymeric Systems with Siloxane Components

1 Introduction Siloxane derivatives have many unique static and dynamic properties like low surface free energy, incompatibility with other component, and bond flexibility.Various functional polymeric systems were designed by taking advantage of these properties.1IntroductionSiloxane derivatives have many unique static and dynamic propertieslikelowsurface free energy,incom-patibility with other component ,and bond flexibility.Various functional polymeric systems were designed bytaking advanta…     

Negative intrinsic resistivity of an individual domain wall in epitaxial (Ga,Mn)As microdevices

Magnetic domains, and the boundaries that separate them (domain walls, DWs), play a central role in the science of magnetism. Understanding and controlling domains is important for many technological applications in spintronics, and may lead to new devices. Although theoretical efforts have elucidated several mechanisms underlying the resistance of a single DW, various experiments report conflicting results, even for the overall sign of the DW resistance. The question of whether an individual DW gives rise to an increase or decrease of the resistance therefore remains open. Here we report an approach to DW studies in a class of ferromagnetic semiconductors (as opposed to metals) that offer promise for spintronics. These experiments involve microdevices patterned from monocrystalline (Ga,Mn)As epitaxial layers. The giant planar Hall effect that we previously observed in this material enables direct, real-time observation of the propagation of an individual magnetic DW along multiprobe devices. We apply steady and pulsed magnetic fields, to trap and carefully position an individual DW within each separate device studied. This protocol reproducibly enables high-resolution magnetoresistance measurements across an individual wall. We consistently observe negative intrinsic DW resistance that scales with channel width. This appears to originate from sizeable quantum corrections to the magnetoresistance.     

A case study of WebGIS technology for distance learning between Korea and Japan

Recently，some case study of distance learning by internet line are widely carried out. Until now，the cultural or friendship exchange was a main purpose using distance learning program. In our research group， a distance learning which connected 3 sites (Nagasaki and Omura and Kagoshima in Japan) was tried as a domestic example [1]. In this case，internet exclusive line and portable telephone were utilized for DVTS technical support of distance learning. Nowadays，the international distance learning for education is also beginning. Our research group also tried international distance learning between Kwangju city of Korea and Nagasaki city of Japan using DVTS techniques with the tools of WebGIS education materials.