Linearity in Optical Absorption Spectra and Gold-Silver Alloy Colloidal Particles in Epoxy Resin

Gold-silver alloy colloids were produced in epoxy resin by thermal decomposition of gold and silver complexes, and their optical absorption spectra were measured. A linear law was found for the maximal absorption wavelengths: the maximal absorption wavelength for gold-silver alloy colloids of arbitrary composition was determined from the wavelengths for pure gold and pure silver colloids and the initial concentration ratio of gold and silver complexes. The change of absorbance and absorption wavelengths with heating periods is presented. Copyright 2001 Academic Press.     

Design,Synthesis and Tumour-Selective Toxicity of Novel 1-[3-{3,5-Bis(benzylidene)-4-oxo-1-piperidino}-3-oxopropyl]-4-piperidone Oximes and Related Quaternary Ammonium Salts

A novel series of 1-[3-{3,5-bis(benzylidene)-4-oxo-1-piperidino}-3-oxopropyl]-4-piperidone oximes 3a–h and related quaternary ammonium salts 4a–h were prepared as candidate antineoplastic agents. Evaluation against neoplastic Ca9-22, HSC-2 and HSC-4 cells revealed the compounds in series 3 and 4 to be potent cytotoxins with submicromolar CC₅₀ values in virtually all cases. In contrast, the compounds were less cytocidal towards HGF, HPLF and HPC non-malignant cells revealing their tumour-selective toxicity. Quantitative structure–activity relationships revealed that, in general, both cytotoxic potency and selectivity index figures increased as the magnitude of the Hammett sigma values rose. In addition, 3a–h are cytotoxic towards a number of leukemic and colon cancer cells. 4b,c lowered the mitochondrial membrane potential in CEM cells, and 4d induced transient G2/M accumulation in Ca9-22 cells. Five compounds, namely 3c,d and 4c–e, were identified as lead molecules that have drug-like properties.     

Submillimeter-Wave Spectroscopy of TiCl in the Ground Electronic State

The submillimeter-wave rotational transitions of TiCl in the ground state were observed using a double-modulation technique. TiCl was generated in a DC-discharge of a mixture of TiCl₄ vapor (less than 1 mTorr) and Ar buffer gas (80 mTorr) at a current of 200 mA. The ⁴Φ_3/2, ⁴Φ_5/2, ⁴Φ_7/2, and ⁴Φ_9/2 spin components of Ti³⁵Cl (v=0, 1, 2) and Ti³⁷Cl (v=0) were detected. The data were analyzed using effective rotational constants for each spin component as well as with the usual N² reduced Hamiltonian. Recent Fourier transform and laser data were included in our fits and we confirm that the ground state of TiCl is a ⁴Φ_r electronic state.     

Gold-Titanium(IV) Oxide Plasmonic Photocatalysts Prepared by a Colloid-Photodeposition Method: Correlation Between Physical Properties and Photocatalytic Activities

Colloidal gold (Au) nanoparticles were prepared and successfully loaded on titanium(IV) oxide (TiO(2)) without change in the original particle size using a method of colloid photodeposition operated in the presence of a hole scavenger (CPH). The prepared Au nanoparticles supported on TiO(2) showed strong photoabsorption at around 550 nm due to surface plasmon resonance (SPR) of Au and exhibited a photocatalytic activity in mineralization of formic acid in aqueous suspensions under irradiation of visible light (>ca. 520 nm). A linear correlation between photocatalytic activity and the amount of Au loaded, that is, the number of Au nanoparticles, was observed, indicating that the activity of Au/TiO(2) plasmonic photocatalysts can be controlled simply by the amount of Au loading using the CPH method and that the external surface area of Au nanoparticles is a decisive factor in mineralization of formic acid under visible light irradiation. Very high reaction rates were obtained in samples with 5 wt % Au or more, although the rate tended to be saturated. The CPH method can be widely applied for loading of Au nanoparticles on various TiO(2) supports without change in the original size independent of the TiO(2) phase. The rate of CO(2) formation also increased linearly with increase in the external surface area of Au. Interestingly, the TiO(2) supports showed different slopes of the plots. The slope is important for selection of TiO(2) as a material supporting colloidal Au nanoparticles.     

Liouville Extensions of Artinian Simple Module Algebras

In a previous article (Amano and Masuoka, 2005 Amano , K. , Masuoka , A. ( 2005 ). Picard–Vessiot extensions of Artinian simple module algebras . J. Algebra 285 : 743 – 767 . [CSA] [Crossref], [Web of Science ®] , [Google Scholar]), the author and Masuoka developed a Picard–Vessiot theory for module algebras over a cocommutative pointed smooth Hopf algebra D. By using the notion of Artinian simple (AS)D-module algebras, it generalizes and unifies the standard Picard–Vessiot theories for linear differential and difference equations. The purpose of this article is to define the notion of Liouville extensions of AS D-module algebras and to characterize the corresponding Picard–Vessiot group schemes.     

Theoretical study of solvent-mediated Ising-like systems: One-dimensional version

We theoretically study physical properties of solutes placed in a straight line and at regular intervals. The solute is a rigid-body and has an arrow-like shape, which changes its direction up (↑$\uparrow$) or down (↓$\downarrow$). If the rigid solutes are immersed in a continuum solvent, nothing happens in the system (it is an obvious fact). However, the property of the directions differs in a granular solvent (e.g., hard-sphere solvent). Depending on the distance between the nearest-neighbor solutes, the directional correlation between them is periodically changed as follows: “parallel-tendency (↑↑$\uparrow \uparrow$)” ↔$\leftrightarrow$ “random” ↔$\leftrightarrow$ “antiparallel-tendency (↑↓$\uparrow \downarrow$)”. Studying a newly created nanosystem, it is able to discover interesting properties hiding in the nanosystem. We believe that such an approach contributes to the development of nanotechnology.     

Laser-plasma extreme ultraviolet source at 6.7?nm using a rotating cryogenic Xe target

A laser-plasma source comprising a rotating cryogenic solid-state Xe target has been studied for use in extreme ultraviolet lithography (EUVL) systems equipped with La/B₄C mirrors. The laser-to-EUV power conversion efficiency (CE) of the cryogenic Xe target was improved to achieve a maximum CE of 0.15?% at 6.7?nm with 0.6?% bandwidth. We successfully demonstrated the continuous generation of EUV light with an average power of 80?mW at 6.7?nm with 0.6?% bandwidth using a Nd:YAG slab laser at a repetition rate of 320?Hz and an average power of 100?W. Scaling-up of the laser-plasma source for use as a future EUVL source is also discussed.     

Potential of mean force between a large solute and a biomolecular complex: a model analysis on protein flux through chaperonin system

Insertion of a large solute into an even larger vessel comprising biopolymers followed by release of the same solute from it is one of the important functions sustaining life. As a typical example, an unfolded protein is inserted into a chaperonin from bulk aqueous solution, a cochaperonin acting as a lid is attached to the chaperonin rim and the protein folds into its native structure within the closed cavity, the cochaperonin is detached after the folding is finished, and the folded protein is released back to the bulk solution. On the basis of the experimental observations manifesting that the basic aspects of the protein flux through the chaperonin system is independent of the chaperonin, cochaperonin, and protein species, we adopt a simple model system with which we can cover the whole cycle of the protein flux. We calculate the spatial distribution of the solvent-mediated potential of mean force (PMF) between a spherical solute and a cylindrical vessel or vessel/lid complex. The calculation is performed using the three-dimensional integral equation theory, and the PMF is decomposed into energetic and entropic components. We argue that an unfolded protein with a larger excluded volume (EV) and weak hydrophobicity is entropically inserted into the chaperonin cavity and constrained within a small space almost in its center. The switch from insertion to release is achieved by decreasing the EV and turning the protein surface hydrophilic in the folding process. For this release, in which the energetic component is a requisite, the feature that the chaperonin inner surface in the absence of the cochaperonin is not hydrophilic plays essential roles. On the other hand, the inner surface of the chaperonin/cochaperonin complex is hydrophilic, and the protein is energetically repelled from it: The protein remains constrained within the small space mentioned above without contacting the inner surface for correct folding. The structural and inner-surface properties of the chaperonin or complex are controlled by the adenosine triphosphate (ATP) binding to the chaperonin, hydrolysis of ATP into adenosine diphosphate (ADP) and Pi, and dissociation of ADP and Pi. The function of the chaperonin system is exhibited by synchronizing the chemical cycle of ATP hydrolysis with hydration properties of a protein in the water confined on the scale of a nanometer which are substantially different from those in the bulk water.     

Guest-responsive covalent frameworks by the cross-linking of liquid-crystalline salts: tuning of lattice flexibility by the design of polymerizable units

Cross-linked polymers prepared by the in-situ polymerization of liquid-crystalline salts were found to work as solid-state hosts with a flexible framework. As a component of such hosts, four kinds of polymerizable amphiphilic carboxylic acids bearing alkyl chains with acryloyloxy (A), dienyl (D), and/or nonreactive (N) chain ends (monomeric carboxylic acids; M(AAA), M(ANA), M(DDD), and M(DND)) were used. The carboxylic acids were mixed with an equimolar amount of a template unit, (1R,2S)-norephedrine (guest amine; G(RS)), to form the corresponding salts. Every salt exhibited a rectangular columnar LC phase at room temperature, which was successfully polymerized by (60)Co γ-ray-induced polymerization without serious structural disordering to afford the salt of cross-linked carboxylic acid (polymeric carboxylic acid; P(AAA), P(ANA), P(DDD), and P(DND)) with G(RS) . Owing to the noncovalency of the interactions between the polymer framework P and the template G(RS), the cross-linked polymers could reversibly release and capture a meaningful amount of G(RS). In response to the desorption and adsorption of G(RS), the cross-linked polymers dramatically switched their nanoscale structural order. A systematic comparison of the polymers revealed that the choice of polymerizable groups has a significant influence on the properties of the resultant polymer frameworks as solid-state hosts. Among these polymers, P(DDD) was found to be an excellent solid-state host, in terms of guest-releasing/capturing ability, guest-recognition ability, durability to repetitive usage, and unique structural switching mode.