Structure–Activity Studies on the Fluorescent Indicator in a Displacement Assay for the Screening of Small Molecules Binding to RNA

A series of xanthone and thioxanthone derivatives with aminoalkoxy substituents were synthesized as fluorescent indicators for a displacement assay in the study of small‐molecule–RNA interactions. The RNA‐binding properties of these molecules were investigated in terms of the improved binding selectivity to the loop region in the RNA secondary structure relative to 2,7‐bis(2‐aminoethoxy)xanthone (X2S) by fluorimetric titration and displacement assay. An 11‐mer double‐stranded RNA and a hairpin RNA mimicking the stem loop IIB of Rev response element (RRE) RNA of HIV‐1 mRNA were used. The X2S derivatives with longer aminoalkyl substituents showed a higher affinity to the double‐stranded RNA than the parent molecule. Introduction of a methyl group on the aminoethoxy moiety of X2S effectively modulated the selectivity to the RNA secondary structure. Methyl group substitution at the C1′ position suppressed the binding to the loop regions. Substitution with two methyl groups on the amino nitrogen atom resulted in reducing the affinity to the double‐stranded region by a factor of 40 %. The effect of methyl substitution on the amino nitrogen atom was also observed for a thioxanthone derivative. Titration experiments, however, suggested that thioxanthone derivatives showed a more prominent tendency of multiple binding to RNA than xanthone derivatives. The selectivity index calculated from the affinity to the double‐stranded and loop regions suggested that the N,N‐dimethyl derivative of X2S would be suitable for the screening of small molecules binding to RRE.     

Remote stereocontrol of intramolecular rhodium carbene addition driven by a small and flexible chiral 2,4-pentanediol tether

Intramolecular rhodium carbenoid additions were studied using 2,4-pentanidiol as a chiral tether between a diazo group, a precursor of the carbene, and an aromatic group to be reacted with the carbene. The reaction was designed to perform the addition at a remote position, conserving the original high stereoselectivity appeared at additions near the tether, in addition to high regioselectivity and sufficient reaction efficiency. Substitution on the near reaction sites, the carbene carbon and aromatic group, in the reactant was effective to relegate the reaction site to a remote position. In the present study, two remote reactions, one dealing with C–H insertion and the other classified in Büchner reaction, were found to give sole products in high yields.     

Oxygen ionic conductivity of La2NiO4+δ via interstitial oxygen defect

The ionic conduction properties of La₂NiO_4+δ were studied from oxygen permeation flux and defect-related transport properties. The effects of the applied oxygen chemical potential gradient and temperature on the oxygen permeability of La₂NiO_4+δ at various thickness are reported. The thermally activated oxygen permeation flux increased monotonically with increasing oxygen chemical potential gradient, yielding a maximum of 0.15 cc min^?1 cm^?2 under air/N₂ conditions for the 0.95 mm-thick La₂NiO_4+δ specimen at 900 °C. The oxygen ion conductivity of La₂NiO_4+δ was calculated as a function of temperature and oxygen partial pressure by differentiating the chemical diffusion equation for the oxygen permeation flux based on the dominant electronic transference number. In addition, the oxygen ion conductivity was extracted successfully by solving the Nernst–Einstein equation combining with the calculated self-diffusion coefficient of oxygen from the chemical diffusivity and thermodynamic enhancement factor from the equilibrium oxygen nonstoichoimetry of a La₂NiO_4+δ specimen, and a deviation of the OPP dependence of 1/6 power was observed.     

Transparent p‐NiO/n‐ZnO diodes used in circuit rectifiers

We report on the fabrication of a transparent photostable cell circuit composed of drive and resistor diodes which are face‐to‐face connected to each other with different device area. The diodes consisted of e‐beam evaporated p‐NiO on sputter‐deposited n‐ZnO for p/n diode formation on indium‐tin‐oxide glass. Our transparent diodes show photostable rectifying behavior, about 10³ on/off current ratio and even dynamic rectification at a maximum frequency of 100 Hz AC input signal in ambient light. The noticeable photo‐responsivity of the circuit was obtained only under ultraviolet (UV) light. We conclude that our transparent diode circuit is promising in enriching the field of transparent device electronics. (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Biobased vinyl levulinate as styrene replacement for unsaturated polyester resins

Vinyl levulinate (VL) is used as a biobased reactive diluent in styrene (St)‐free unsaturated polyester resins (UPR). The reactivity ratios for the radical copolymerization of VL with diethyl fumarate (DEF) are determined by the Jaacks method (r_VL = 0.01 and r_DEF = 0.81 at 60 °C in DMSO‐d₆). The properties of UPRs having a stoichiometric ratio between unsaturated groups from the UPR and either St or VL are compared. Defect‐free, slightly yellow, transparent, and rigid thermosets are obtained after a mild curing cycle. Due to unfavorable reactivity ratios about 5.5 wt % of unpolymerized VL remains inside the network and acts as plasticizer. Consequently, compared with St‐based ones, VL‐based UPRs exhibit lower α relaxation (T_α = 180 and 100 °C, respectively), lower elastic moduli at the rubbery plateau (G′ = 10⁸ and 10⁷ Pa) and lower mechanical properties as measured by three points bending tests. Strain at break (ε_f = 1.8 ± 0.2%) and Charpy impact strength (～2.7 ± 0.3 kJ m^?2) are comparable independently of the RD chemical nature. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 3356–3364     

A Rat’s Image Using Multichannel Phase Array RF Coil Specifically Designed for Animals: Focused on a Pulse Sequence and Mediator Variable

The study focuses on finding the pulse sequences depicting a rat’s tumor when the size of the field of view was reduced, using coils specifically designed for rats, and obtaining an optimized image of a rat by transforming the parameters, according to each pulse sequence. The manufactured coil is 8-channel phased array coils, and the type is a receive-only coil. The diameter of the coil is 80 mm, and the length is 150 mm. The overlapped distance among each channel was 8 mm, and the lab rats used in the experiment were the commonly used Sprague–Dawley rats. The study used three types of pulse sequences, which are the diffusion weight imaging (DWI), three-dimensional dual echo steady state (3-D DESS), and three-dimensional volumetric interpolated breath-hold (3-D VIBE). Along with the DWI results, pulse sequences of 3-D DESS and 3-D VIBE enabled to distinguish the tumors from that of normal tissues in the brain by optimizing a mediator variable and to illustrate the whole body imaging of a rat.     

Effect of Si in reactively sputtered Ti-Si-N films on structure and diffusion barrier performance

34 Si₂₃N₄₃ (b3) and Ti₃₅Si₁₃N₅₂ (c3), are synthesized by reactively sputtering a Ti₅Si₃ or a Ti₃Si target, respectively. The silicon-lean film (c3) has a columnar structure closely resembling that of TiN. As a diffusion barrier between a shallow Si n⁺p junction diode and a Cu overlayer, this material is effective up to 700 °C for 30 min annealing in vacuum, a performance similar to that for TiN. The silicon-rich (b3) film contains nanocrystals of TiN, randomly oriented and embedded in an amorphous matrix. A film of (b3) maintains the stability of the same diode structure up to 850 °C for 30 min in vacuum. This film (b3) is clearly superior to TiN or to (c3). Similar experiments performed with Al instead of Cu overlayers highlight the importance of the thermodynamic stability of a barrier layer and demonstrate convincingly that for stable barriers the microstructure is a parameter that directly determines the barrier performance. Received: 18 November 1996/Accepted: 22 January 1997     

Luminescent and aging characteristics of blue emitting (Ca1−x,Mgx)Al2Si2O8:Eu phosphor for PDPs application

We have evaluated thermal stability and aging property of a blue color-emitting phosphor, CaAl₂Si₂O₈:Eu²⁺ (CAS:Eu²⁺), synthesized by conventional solid-state reaction method. When both CAS:Eu²⁺ and BaMgAl₁₀O₁₉:Eu²⁺ (BAM) were baked in air at 500 °C for 20 min, the decrease of photoluminescence (PL) intensity of CAS:Eu²⁺ was lower than that of BAM. The aging property of CAS:Eu²⁺ was also better than that of BAM. Due to its rigid structure and unlimited framework of silicon-oxygen and aluminum-oxygen around Eu²⁺ ions, Eu²⁺ ions were protected from outer oxidizing atmosphere and plasma discharge. After analysis of aging property and thermal stability, the differences of these thermal stability and aging property of CAS:Eu²⁺ from those of BAM were ascribed to its crystal structure which plays a role of a shield for Eu²⁺ ions against oxidation atmosphere and Xe ion bombardment.     

PL fibrator properties of partially aspherical manifolds

Approximate fibrations form a useful class of maps. By definition fibrators provide instant detection of maps in this class, and PL fibrators do the same in the PL category. This paper formalizes a natural concept of partial asphericity and establishes fibrator properties of certain partially aspherical closed manifolds. One consequence is that any connected sum of aspherical PL manifolds with residually finite fundamental groups is a codimension-(2n−2) PL fibrator.     

Scintillators for Alpha and Neutron Radiations Synthesized by Room Temperature Sol–Gel Processing

Solid-state scintillating materials were synthesized by the co-doping of sol–gel components with neutron absorbers [⁶Li and ¹⁰B], organic fluorescence sensitizers such as salicylic acid and 2,5-diphenyloxazole (PPO) and activator 1,4-bis-2-(5-phenyloxazolyl)-benzene (POPOP). The room-temperature sol–gel process through the addition of organic polymers is the key to the successful entrapment of the organic sensitizers and activator in inorganic matrixes. These transparent or translucent sol–gel scintillators were evaluated for alpha radiation and neutron detections.