A novel strategy for fluorescence enhancement in the solid-state: affording rigidity to fluorophores packing

Solid-state fluorescence enhancement was achieved by preparation of rigid packing that was afforded by disposition of benzylamine into tubulate spaces, serving as a powerful and useful strategy for the enhancement.     

Counter-examples to non-noetherian Elkik's approximation theorem

Elkik established a remarkable theorem that can be applied for any noetherian henselian ring. For algebraic equations with a formal solution (restricted by some smoothness assumption), this theorem provides a solution adically close to the formal one in the base ring. In this paper, we show that the theorem would fail for some non-noetherian henselian rings. These rings do not satisfy several conditions weaker than noetherianness, such as weak proregularity (due to Grothendieck et al.) of the defining ideal. We describe the resulting pathologies.     

Electrical breakdown of microwave plasma in water

The electrical breakdown of microwave plasma in water was investigated between 1 and 30 kPa. The dependency of the ignition power for generating plasma on the size of coaxial electrode was measured. The ignition power decreases with a decrease of the diameter of the inner electrode. The behavior of microwave plasma in water was observed using a high-speed camera. The plasma ignites in a bubble generated by microwave heating. The model for calculating the electric field was created on the basis of the captured images of the bubble just before plasma ignition. The method presented can be used to visualize the electrical field distribution in the bubble. The electric field breakdown was calculated using the measured ignition power. The electric field breakdown of plasma in water is of the same order as gas phase plasma.     

Practical and Scalable Organic Reactions with Flow Microwave Apparatus

Microwave irradiation has been used for accelerating organic reactions as a heating method and has been proven to be useful in laboratory scale organic synthesis. The major drawback of microwave chemistry is the difficulty in scaling up, mainly because of the low penetration depth of microwaves. The combination of microwave chemistry and flow chemistry is considered to overcome the problem in scaling up of microwave‐assisted organic reactions, and some flow microwave systems have been developed in both academic and industrial communities. In this context, we have demonstrated the scale‐up of fundamental organic reactions using a novel flow microwave system developed by the academic‐industrial alliance between the University of Shizuoka, Advanced Industrial Science and Technology, and SAIDA FDS. In this Personal Account, we summarize the recent progress of our scalable microwave‐assisted continuous synthesis using the SAIDA flow microwave apparatus.     

Computing the determinantal representations of hyperbolic forms

The numerical range of an n × n matrix is determined by an n degree hyperbolic ternary form. Helton-Vinnikov confirmed conversely that an n degree hyperbolic ternary form admits a symmetric determinantal representation. We determine the types of Riemann theta functions appearing in the Helton-Vinnikov formula for the real symmetric determinantal representation of hyperbolic forms for the genus g = 1. We reformulate the Fiedler-Helton-Vinnikov formulae for the genus g = 0, 1, and present an elementary computation of the reformulation. Several examples are provided for computing the real symmetric matrices using the reformulation.     

Solution properties of perfluorinated anionic surfactants with divalent counterion of separate electric charges

Novel surfactants of perfluorinated double long-chain salts with divalent counterion of separate electric charge, 1,1-(1,omega-alkanediyl)bispyridinium diperfluorononanoate (CnBP(FC9)2, n = 2, 4, 6, 8) were newly synthesized. Their solution properties were investigated by surface tension measurement over the temperature range from 298.2 to 313.2 K, where magnesium diperfluorononanoate (Mg(FC9)2) was employed as a reference surfactant with divalent counterion of concentrated electric charge. From change of surface tension with concentration, the critical micelle concentration (CMC), surface excess (Gamma), apparent molecular surface area (A), and -log(concentration to reduce surface tension of water by 20 mN m-1) (pC20) were determined. The CMC values of CnBP(FC9)2 decreased with increasing charge separation and with increasing temperature, where the values of CnBP(FC9)2 were much smaller than those of Mg(FC9)2. In addition, the pC20 values of the former were also much larger than those of the latter. These results indicate a strong influence of the extent of charge separation or the spacer length of the counterions upon surface activity of the fluorinated surfactants. The surface excess or the corresponding apparent molecular surface area monotonously changed with the spacer length (n < or = 6), whereas the behavior for n = 8 was much different from the other CnBP(FC9)2 due to conformational change in the in-between alkanediyl chain. The entropy changes (Deltas) for the surface adsorption or condensation were found to be mostly negative for CnBP(FC9)2, where the changes approached zero with an increase in the charge separation. On the other hand, the changes for Mg(FC9)2 were positive over the whole concentration below the CMC. In addition, Brewster angle microscopy indicated no condensation of the present surfactants just at the air/solution interface.     

High-field 1H MAS and 15N CP-MAS NMR studies of alanine tripeptides and oligomers: distinction of antiparallel and parallel beta-sheet structures and two crystallographically independent molecules

beta-Strand peptides are known to assemble into either antiparallel (AP) or parallel (P) beta-sheet forms which are very important motifs for protein folding and fibril formations occurring in silk fibroin or amyloid proteins. Well-resolved 1H NMR signals including NH protons were observed for alanine tripeptides (Ala)3 with the AP and P structures as well as (Ala)n (n = 4-6) by high-field/fast magic-angle spinning NMR. Amide NH and amino NH3+ 1H signals of (Ala)3 with the P structure were well resonated at 7.5 and 8.9 ppm, respectively, whereas they were not resolved for the AP structure. Notably, NH 1H signals of (Ala)3 and (Ala)4 taking the P structure are resonated at higher field than those of the AP structure by 1.0 and 1.1 ppm, respectively. Further, NH 15N signals of (Ala)3 with the AP structure were resonated at lower field by 2 to 5 ppm than those of (Ala)3 with the P structure. These relative 1H and 15N hydrogen bond shifts of the P structure with respect to those of the AP structure are consistent with the relative hydrogen bond lengths of the interstrand N-H...O=C bonds. Distinction between the two crystallographically independent chains present in the AP and P structures was feasible by 15N chemical shifts but not by 1H chemical shifts because of insufficient spectral resolution in the latter. Calculated 1H and 15N shielding constants by density functional theory are generally consistent with the experimental data, although some discrepancies remain depending upon the models used.     

Vertex operator algebras, extended diagram, and McKay's observation on the Monster simple group

We study McKay's observation on the Monster simple group, which relates the -involutions of the Monster simple group to the extended diagram, using the theory of vertex operator algebras (VOAs). We first consider the sublattices of the lattice obtained by removing one node from the extended diagram at each time. We then construct a certain coset (or commutant) subalgebra associated with in the lattice VOA . There are two natural conformal vectors of central charge in such that their inner product is exactly the value predicted by Conway (1985). The Griess algebra of coincides with the algebra described in his Table 3. There is a canonical automorphism of of order . Such an automorphism can be extended to the Leech lattice VOA , and it is in fact a product of two Miyamoto involutions. In the sequel (2005) to this article, the properties of will be discussed in detail. It is expected that if is actually contained in the Moonshine VOA , the product of two Miyamoto involutions is in the desired conjugacy class of the Monster simple group.

     

Optical,structural, enhanced local vibrational and fluorescence properties in K-doped ZnO nanostructures

We studied structural, optical and vibrational properties of K-doped ZnO nanostructures. X-ray diffraction studies reveal that the prepared particles are hexagonal wurtzite in structure. Increase in lattice parameters and unit cell volume is observed after K doping. Dopant influences on stress, strain of the system are studied using W–H plots. Band gap variation by doping of K is identified from optical absorption studies. Photoluminescence studies have given insight into the enhancement in blue emission observed by K doping along with the near band emission of nano ZnO. From Fourier transform infrared spectral measurements, K-related local vibration mode is observed along with the information related to influence of doping on characteristic vibrational modes of ZnO.