X-ray Computed Tomography (CT) is the important equipment in medical care today. However, its exposed dose is very high. We propose two types of CT which use gamma ray. Compared to X-ray CT, they ...have good ability to see through the organism. In addition, the exposed dose of its examination is very low.
The photochemical reaction process of bacteriorhodopsin in the nanosecond time range (-120–860 ns) was measured in the 1400–900 cm-1 region with an improved time resolved dispersive-type infrared ...spectrometer. The system is equipped with a newly developed detection unit whose instrumental response to a 5-ns laser pulse has a full width of the half-maximum of 60 ns. It provides highly accurate data that enabled us to extract a kinetic process one order of magnitude faster than the instrumental response. The spectral changes in the 1400–900 cm-1 region were analyzed by singular value decomposition and resolved into three components. These components were separated by fitting with 10- and 1000-ns exponential functions and a step function, which were convoluted with the instrumental response function. The components with decay time constants of 10 and 1000 ns are named K and KL, respectively, on the basis of previous visible spectroscopy. The spectral shapes of K and KL are distinguishable by their hydrogen-out-of-plane (HOOP) modes, at 958 and 984 cm-1, respectively. The former corresponds to the K intermediate recorded at 77 K and the latter to a K-like photoproduct at 135 K. On the basis of published data, these bands are assigned to the 15-HOOP mode, indicating that the K and KL differ in a twist around the C14-C15 bond.
Clostridium botulinum type C 16S progenitor toxin contains a hemagglutinin (HA) subcomponent, designated HA1, which appears to play an important role in the effective internalization of the toxin in ...gastrointestinal epithelial cells and in creating a broad specificity for the oligosaccharide structure that corresponds to various targets. In this study, using the recombinant protein fused to glutathione
S-transferase, we investigated the binding specificity of the HA1 subcomponent to sugars and estimated the binding sites of HA1 based on X-ray crystallography and soaking experiments using various sugars.
N-Acetylneuraminic acid,
N-acetylgalactosamine, and galactose effectively inhibited the binding that occurs between glutathione
S-transferase–HA1 and mucins, whereas
N-acetylglucosamine and glucose did not inhibit it. The crystal structures of HA1 complex with
N-acetylneuraminic acid,
N-acetylgalactosamine, and galactose were also determined. There are two sugar-binding sites, sites I and II. Site I corresponds to the electron densities noted for all sugars and is located at the C-terminal β-trefoil domain, while site II corresponds to the electron densities noted only for galactose. An aromatic amino acid residue, Trp176, at site I has a stacking interaction with the hexose ring of the sugars. On the other hand, there is no aromatic residue at site II; thus, the interaction with galactose seems to be poor. The double mutant W176A at site I and D271F at site II has no avidity for
N-acetylneuraminic acid but has avidity for galactose. In this report, the binding specificity of botulinum C16S toxin HA1 to various sugars is demonstrated based on its structural features.
High-efficiency light-driven hydrogen evolution from water was demonstrated by using poly(phenyleneethynylene) bearing negatively charged, G3 poly(benzyl ether) dendrimeric side groups 3 L4 as ...photosensitizer. Three-dimensional wrapping of the conjugated backbone suppressed self-quenching of the photoexcited state, while methyl viologen (MV2+), a positively charged electron acceptor, was trapped on its negatively charged surface, to form a spatially separated donor−acceptor supramolecular complex. Studies with time-resolved fluorescence spectroscopy showed that the quenching rate constant (k q = 1.2 × 1015 M-1 s-1) is much greater than diffusion control rate constants. Upon excitation of 3 L4 in the presence of a mixture of MV2+, triethanolamine (TEOA; sacrificial electron donor), and a colloidal PVA-Pt, hydrogen evolution took place with an overall efficiency of 13%, 1 order of magnitude better than precedent examples. Comparative studies with several reference sensitizers showed that spatial isolation of the conjugated backbone and its long-range π-electronic conjugation, along with electrostatic interactions on the exterior surface, play important roles in achieving the efficient photosensitized water reduction.
This article explores changes in Japan's conception of and policy toward security multilateralism
1
in the Asia-Pacific region after the end of the Cold War with special reference to the ASEAN ...Regional Forum (ARF). It makes the observation that notwithstanding Japan's active role behind the establishment of the ARF in the early 1990s and continuing public expression of strong support for Asia-Pacific security multilateralism since that time, in actuality, Japan's enthusiasm for it has dwindled from the late 1990s onwards. This article argues that this has been due primarily to Japan's disappointing experiences in the ARF, evinced by its abortive efforts to promote meaningful cooperative security measures and the failings of multilateral security diplomacy in addressing its security concerns. Consequently, Japan's conception of regional security multilateralism has shifted from an optimistic liberal to a more pessimistic realist perspective from which the ARF can, at best, be seen as a venue contributing only to a minimal level of confidence building among regional countries or, to put it more cynically, 'a talking shop'. This has made Japan's ARF policy more tentative and less energetic. Japan's enthusiasm has also been diluted by a number of internal and external constraints on ARF policy, including US misgivings about Japan's tilt toward regional security multilateralism, its domestic organizational limitations, growing dissent within the Japanese government over the value of security multilateralism, the lack of political support for bureaucratic initiatives and the unexpected frictions between bilateral and multilateral security approaches in Japan's overall security policy.
Celotno besedilo
Dostopno za:
BFBNIB, DOBA, IZUM, KILJ, NUK, ODKLJ, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
PDF
