Algorithms for image recovery calculation in extended single-shot phase-shifting digital holography

Optical Review - The single-shot phase-shifting method of image recovery using an inclined reference wave has the advantages of reducing the effects of vibration, being capable of operating in real...     

Euler's integrals and multiple sine functions

We show that Euler's famous integrals whose integrands contain the logarithm of the sine function are expressed via multiple sine functions.

     

Controlling the solid-state luminescence of gold(I) <Emphasis Type="Italic">N</Emphasis>-heterocyclic carbene complexes through changes in the structure of molecular aggregates

Thermally stable, solid-state luminescent organic materials are highly desired for the development of practical applications. Herein we synthesized new gold(I) complexes with N-heterocyclic carbene ligands, which have the ability to form strong metal-organic bond. Consequently, their thermochemical stability is enhanced at temperatures around 300 °C. Precise design of the molecular structure of the ligands, with a focus on ensuring low steric hindrance around Au atoms in order to limit disturbances to Au/Au interactions, provided a complex with a densely packed crystal with a shorter intermolecular Au–Au distance (3.17 Å) than the typical distance. In the solid state, this complex exhibited strong aurophilic interactions, which generated intense phosphorescence even in air at room temperature (quantum yield=16%) in spite of absence of any phosphorescence in solution. This behavior is characteristic for solid-state luminescence referred to as aggregation-controlled emission. Furthermore, the gold (I) complex displays capacity for mechano- and vapo-chromism—that is, the ability to change color reversibly in response to the application of external stimuli. We believe that the proposed design framework, which involves controlling thermal stability and luminescence property separately, provides a new opportunity for the development of practical applications using solid-state luminescent organic molecules.     

Germanium(II)-mediated reductive cross-aldol reaction of bromoaldehydes with aldehydes: NMR studies and ab initio calculations

A highly practical reductive cross-aldol reaction of alpha-bromoaldehydes with various aldehydes has been developed using Ge(II)Cl 2 to produce aldehyde germanium(IV) aldolates, which were directly transformed to various multifunctionalized compounds. A remarkable change in stereoselectivity depended on the alpha-bromoaldehydes employed; secondary alpha-bromoaldehydes gave syn selectivities, while tertiary alpha-bromoaldehydes accomplished the synthesis of anti-selective aldol products with a quaternary carbon center. NMR studies and X-ray analysis strongly suggested the formation of germanium enolate in the reaction of alpha-bromoaldehyde 2h with GeCl 2-dioxane. Detailed mechanistic studies, including NMR analysis and ab initio calculations, revealed the generation of stable germanium aldolates, which was due to the remarkably low Lewis acidity of the germanium(IV).     

Theoretical study on the second hyperpolarizabilities of phenalenyl radical systems involving acetylene and vinylene linkers: diradical character and spin multiplicity dependences

We have investigated the static second hyperpolarizabilities (gamma) of the singlet diradical systems with intermediate diradical character involving phenalenyl radicals connected by acetylene and vinylene pi-conjugated linkers, 1 and 2, using the hybrid density functional theory. For comparison, we have also examined the gamma values of the closed-shell and pure diradical systems with almost the same molecular size as 1 and 2. In agreement with our previous prediction of the diradical character dependence of gamma, it turns out that the gamma values of 1 and 2 are significantly enhanced compared to those of the closed-shell and pure diradical systems. In the present case, distinct differences in gamma values are not observed between the two pi-conjugated linkers, though the diradical character is found to depend on the kind of linker. Furthermore, we have investigated the spin multiplicity effect on gamma. Changing from the singlet to the triplet state, the gamma values of the systems with intermediate diradical character in the singlet state are quite reduced, though those of the pure diradical systems are hardly changed. Such spin multiplicity dependence of gamma is understood by considering the difference of diradical character between their singlet states together with the Pauli principle. The present results provide a possibility of a novel control scheme of gamma for phenalenyl radical systems involving pi-conjugated linkers by adjusting the diradical character through the change of the linked position of pi-conjugated linkers and the spin multiplicity.     

Laser-assisted magnetic recording light-delivery system with a coupling element and a laterally tapered vertically multistepped waveguide

In a light-delivery system for laser-assisted magnetic recording, which provides high-areal-density storage by heating the storage medium during the writing process, a laser diode light source and a near-field transducer must be efficiently coupled using inexpensive optical devices. We describe a light-delivery system using an element for end-fire coupling and a spot-size converter. To couple the light emitted from the end of an optical fiber to a spot-size converter inexpensively, a couple element requiring no other lens elements between the fiber and converter was developed. A vertically multistepped and laterally tapered waveguide suitable for fabrication by planar processing was also developed. These devices are well suited for practical use.     

Finite termination of the proximal point algorithm in Banach spaces

In this paper, we show that the convex optimization problem can be solved by the proximal point algorithm in a finite number of steps under the assumption that the solution set is a set of weak sharp minima.     

Ligand migration in myoglobin: a combined study of computer simulation and x-ray crystallography

A ligand-migration mechanism of myoglobin was studied by a multidisciplinary approach that used x-ray crystallography and molecular dynamics simulation. The former revealed the structural changes of the protein along with the ligand migration, and the latter provided the statistical ensemble of protein conformations around the thermal average. We developed a novel computational method, homogeneous ensemble displacement, and generated the conformational ensemble of ligand-detached species from that of ligand-bound species. The thermally averaged ligand-protein interaction was illustrated in terms of the potential of mean force. Although the structural changes were small, the presence of the ligand molecule in the protein matrix significantly affected the 3D scalar field of the potential of mean force, in accordance with the self-opening model proposed in the previous x-ray study.     

Interaction of piezoelectric lead zirconate titanate with 400 MeV/n xenon beam

The characteristics of radiation detector fabricated by stacking some piezoelectric lead zirconate titanate (PZT) elements were studied by irradiating it with a 400 MeV/n xenon (Xe) beam. Comparing between observed results from the detector and calculation results using Bethe–Bloch formula, it was found that the amplitude of the output voltage observed was dependent on the amount of ionization energy loss of Xe ion with PZT.     

Reactions of 4-cyano- and 4-methylimidazoles with isocyanates

4-Cyano- and 4-methylimidazoles reacted with methyl and aryl isocyanates to give exclusively 1-(substituted carbamoyl)-4-cyano- and 4-methylimidazoles, respectively. Refluxing of 1-carbamoyl-4-methylimidazoles in nitrobenzene yielded 2-carbamoyl-4-methylimidazoles through a known migration, whereas the 4-cyano analogues could not be caused to migrate. On the other hand, the treatment of 4-cyano-1-(methylcarbamoyl)imidazole with methyl isocyanate under the basic conditions resulted in the formation of 2-methyl-1-(methylcarbamoylimino)-2, 3-dihydro-1H-imidazo[1, 5-c]imidazol-3-one which must be formed via the migration of the carbamoyl group to another nitrogen followed by the intramolecular cyclization of the newly introduced carbamoyl group with its viccyano group.