Effect of wall conditions on DDT in hydrogen–oxygen mixtures

Detonation in ducts is usually studied assuming adiabatic walls because of the high kinetic energy due to the incoming flow being supersonic. In the present work, numerical simulations of deflagration-to-detonation transition (DDT) using a detailed chemical reaction model are performed under adiabatic and isothermal boundary conditions in a tube with no-slip walls. The results show a local explosion driving DDT, which occurs near the tube wall in the case of an adiabatic wall, but close to the flame front in the case of an isothermal wall. Furthermore, to examine the effects of a turbulent boundary layer, a simulation using the Baldwin–Lomax turbulence model is carried out. In the case of the isothermal wall, there is again a local explosion near the tube wall, which leads to detonation. In summary, the present study confirms that the boundary conditions affect the transition to detonation and that the boundary layer is a key component of DDT.     

Thermo‐Responsive Hydrogels with Nanodomains: Rapid Shrinking of a Nanogel‐Crosslinking Hydrogel of Poly(N‐isopropyl acrylamide)

Rapidly shrinking poly(N‐isopropyl acrylamide) (PNIPAM) hydrogels are prepared by crosslinking with self‐assembled nanogels that consist of cholesteryl‐ and methacryloyl‐substituted pullulan (CHPMA). The CHPMA nanogel (R_h = 26.4 nm) was used as a crosslinker for a hydrophilic nanodomain. Transmission electron microscopy images of the nanogel‐crosslinked PNIPAM hydrogel reveal a well‐defined nanoporous structure. The nanogel‐crosslinked PNIPAM hydrogel shows rapid shrinking based on its structure. The shrinking half‐time was ≈2 min, which is about 3 400 times faster than that of a PNIPAM hydrogel crosslinked by methylene(bisacrylamide).

     

Generation of high-fidelity four-photon cluster state and quantum-domain demonstration of one-way quantum computing

We experimentally demonstrate a simple scheme for generating a four-photon entangled cluster state with fidelity over 0.860+/-0.015. We show that the fidelity is high enough to guarantee that the produced state is distinguished from Greenberger-Horne-Zeilinger, W, and Dicke types of genuine four-qubit entanglement. We also demonstrate basic operations of one-way quantum computing using the produced state and show that the output state fidelities surpass classical bounds, which indicates that the entanglement in the produced state essentially contributes to the quantum operation.     

Evidence for strong Breit interaction in dielectronic recombination of highly charged heavy ions

Resonant strengths have been measured for dielectronic recombination of Li-like iodine, holmium, and bismuth using an electron beam ion trap. By observing the atomic number dependence of the state-resolved resonant strength, clear experimental evidence has been obtained that the importance of the generalized Breit interaction (GBI) effect on dielectronic recombination increases as the atomic number increases. In particular, it has been shown that the GBI effect is exceptionally strong for the recombination through the resonant state [1s2s(2)2p(1/2)](1).     

Super-rotation flow in a precessing sphere

The super rotation here means that the majority of fluid inside a precessing sphere rotates around the precession axis with angular velocity larger than that of the precession rotation itself. This phenomenon observed experimentally and numerically is explained to be driven by a cooperative interplay between the Coriolis force, the pressure gradient and the spherical geometry in the boundary layer.     

Excited-state double-proton transfer in the 7-azaindole dimer in the gas phase. 3. Reaction mechanism studied by picosecond time-resolved REMPI spectroscopy

The excited-state double-proton-transfer (ESDPT) reaction in the jet-cooled 7-azaindole dimer (7AI2) has been investigated with picosecond time-resolved resonance-enhanced multiphoton ionization spectroscopy. The observed decay profiles of 7AI2 by exciting the origin and the intermolecular stretch fundamental in the S1 state are well reproduced by single-exponential functions with time constants of 1.9 +/- 0.9 ps and 860 +/- 300 fs, respectively. This result provides clear evidence of the concerted mechanism of ESDPT in 7AI2.     

New synthetic route to granulatimide and its structural analogues

The Stille coupling reaction of stannylindole 12 with 4-iodoimidazole 13 (or 24) in the presence of PdCl(2)(PPh(3))(2) gave the corresponding indole-imidazole coupling product 14 (or 25), thereby affording a new synthetic approach to the alkaloid granulatimide (7), isolated from the Brazilian ascidian Didemnum granulatum, as well as its structural analogues, 10-methylgranulatimide (23), 17-methylgranulatimide (30), 10,17-dimethylgranulatimide (31).     

New structure model for the GaAs(001)-c(4x4) surface

The surface structure of the As-stabilized GaAs(001)-c(4 x 4) surface has been studied. We show that the seemingly established three As-dimer model is incompatible with experimental data and propose here a new structure model which has three Ga-As dimers per c(4 x 4) unit cell. This mixed dimer model, confirmed by the rocking-curve analysis of reflection high-energy electron diffraction and first-principles calculations, resolves disagreements in the interpretation of several previous experiments. A good agreement between the observed scanning tunneling microscopy image and the simulated one further confirms the newly proposed model.     

Role of Prehistories in the Initial Value Problems of Fractional Viscoelastic Equations

The fractional viscoelastic equation (FVE), which is a second-order differential equation with fractional derivatives describing the dynamical behavior of a single-degree-of-freedom viscoelastic oscillator, is considered. Some viscoelastic damped mechanical systems may be described by FVEs. However, FVEs with conventional nonzero initial values cannot generally be solved. In this paper, the prehistories of the unknown functions before the initial times, referred to as the initial functions, are taken into account to solve FVEs. Mathematically, appropriate initial functions are essential for unique solutions of FVEs. Physically, the initial functions reflect the processes of giving the initial values. FVEs are solved for some initial functions both by analytical and numerical methods. The initial functions affect the solutions of FVEs. It is discussed how the solutions depend on the initial functions. Implication of the solutions to viscoelastic materials will be discussed.     

Determination of cysteine concentration by fluorescence increase: reaction of cysteine with a fluorogenic aldehyde

A fluorogenic method for the determination of cysteine concentration has been developed.