Search for CP violation in D± meson decays to ϕπ±

We search for CP violation in Cabibbo-suppressed charged D meson decays by measuring the difference between the CP-violating asymmetries for the Cabibbo-suppressed decays D(±)→K(+)K(-)π(±) and the Cabibbo-favored decays D(s)(±)→K(+)K(-)π(±) in the K(+)K(-) mass region of the ? resonance. Using 955 fb(-1) of data collected with the Belle detector, we obtain A(CP)(D+→?π+)=(+0.51±0.28±0.05)%. The measurement improves the sensitivity of previous searches by more than a factor of 5. We find no evidence for direct CP violation.     

Reorientation of a nonspherical capsule in creeping shear flow

The dynamics of a capsule and a biological cell is of great interest in chemical engineering and bioengineering. Although the dynamics of a rigid spheroid is well understood by Jeffery's theory, that of a spheroidal capsule remains unclear. In this Letter, the motion of a spheroidal capsule or a red blood cell in creeping shear flow is investigated. The results show that the orientation of a nonspherical capsule is variant under time reversal, though that of a rigid spheroid is invariant. Surprisingly, the alignment of a nonspherical capsule over a long time duration shows a transition depending on the shear rate, which can be utilized for a particle-alignment technique. These findings form a fundamental basis of the suspension mechanics of capsules and biological cells.     

Measurement of the CP-violation parameter sin2φ1 with a new tagging method at the Υ(5S) resonance

We report a measurement of the CP-violation parameter sin2φ1 at the Υ(5S) resonance using a new tagging method, called "B-π tagging." In Υ(5S) decays containing a neutral B meson, a charged B, and a charged pion, the neutral B is reconstructed in the J/ψK(S)(0) CP-eigenstate decay channel. The initial flavor of the neutral B meson at the moment of the Υ(5S) decay is opposite to that of the charged B and may thus be inferred from the charge of the pion without reconstructing the charged B. From the asymmetry between B-π(+) and B-π(-) tagged J/ψK(S)(0) yields, we determine sin2φ1=0.57±0.58(stat)±0.06(syst). The results are based on 121 fb(-1) of data recorded by the Belle detector at the KEKB e(+)e(-) collider.     

Persistence of covalent bonding in liquid silicon probed by inelastic x-ray scattering

Metallic liquid silicon at 1787 K is investigated using x-ray Compton scattering. An excellent agreement is found between the measurements and the corresponding Car-Parrinello molecular dynamics simulations. Our results show persistence of covalent bonding in liquid silicon and provide support for the occurrence of theoretically predicted liquid-liquid phase transition in supercooled liquid states. The population of covalent bond pairs in liquid silicon is estimated to be 17% via a maximally localized Wannier function analysis. Compton scattering is shown to be a sensitive probe of bonding effects in the liquid state.     

Laterally coupled silicon-germanium modulator for passive waveguide systems

We model a laterally coupled Franz-Keldysh add-drop ring modulator designed to overcome the C-band indirect absorption of silicon-germanium. Although our concept is based on loss-sensitive interferometry, it utilizes the same highly absorptive germanium-rich compositions geared toward complementary metal-oxide semiconductor (CMOS) photodetectors and electroabsorption modulators. The proposed device can be integrated with passive waveguide networks in which the carrier plasma modulation mechanism is ineffective. In addition, unlike previous silicon-germanium modulator schemes, complex butt-coupling between the passive transport and the active silicon-germanium waveguides is not required. Instead, the optical mode remains guided within the transport waveguide, minimizing transition losses.     

Pattern-effect-free all-optical wavelength conversion using a hydrogenated amorphous silicon waveguide with ultra-fast carrier decay

Ultra-fast carrier decay, recently discovered in a hydrogenated amorphous silicon waveguide, can be exploited for pattern-effect-free all-optical signal processing based on optical Kerr nonlinearity. In this study, we utilized a 10 Gbit/s RZ-OOK data stream as a pump for degenerate four-wave mixing in a low-loss hydrogenated amorphous silicon waveguide. The propagation loss of the waveguide used was 1.0±0.2 dB/cm at 1550 nm. Unlike crystalline silicon waveguides, no noticeable difference was observed in the BER characteristics between the cases of PRBS 2(7)-1 and 2(31)-1.     

Dinuclear single-molecule magnets with porphyrin-phthalocyanine mixed triple-decker ligand systems giving SAP and SP coordination polyhedra

Two terbium ions in a triple-decker complex (Pc)Tb(Pc)Tb(T(p-OMe)PP) (Pc = phthalocyaninato, T(p-OMe)PP = tetra-p-methoxyphenylporphyrinato) have shown sharply different magnetic behaviours depending on symmetry of the coordination polyhedron. The fast quantum tunnelling relaxation process in a square-prismatic site has been revealed to be hindered by magnetic-dipolar coupling between the f-electronic systems.     

Aluminum alkoxide complexes from highly substituted 3,4‐epoxy alcohols: An NMR and computational study

The organoaluminum mediated epoxide ring opening of epoxy alcohols is a key step in the oxirane‐based approach for polypropionate synthesis. However, this reaction has shown unanticipated regioselectivities when applied to 2‐methyl‐3,4‐epoxy alcohols. In order to gain mechanistic insight into the factors controlling the epoxide ring opening process, diastereomeric 2‐methyl‐3,4‐epoxy alcohols were reacted with triethylaluminum in order to identify the aluminum complexes formed by these systems. Different epoxide–aluminum complexes were calculated using ab initio HF/[13s7p/11s5p] and B3PW91/6‐31G** gauge‐including atomic orbital (GIAO) methods and compared to the experimental NMR data. The calculated and experimental data correlates with the aluminum dimer complex (TIPSOCH₂CH(OAlEt₂)CH(CH)₃CHCH(O)(AlEt₃))₂ (VIII) for the systems favoring the nucleophilic attack at the external C4 epoxide carbon, while an unusual trialuminum species TIPSOCH₂CH(OAlEt₂)CH(CH)₃CHCH(O)(AlEt₃)₂ (X) is consistent with the systems favoring the internal C3 attack. The ²⁷Al NMR data established the tetracoordinated nature of the aluminum metal in all alkoxy aluminum intermediates, while the ¹³C NMR data provided insight into the aluminum‐oxygen coordination. The formation of the complexes was dictated by the stereochemical disposition of the substituents. These complexes are different from the generally accepted bidentate intermediates proposed for 2,3‐epoxy alcohols and simpler 3,4‐epoxy alcohols. Copyright © 2012 John Wiley & Sons, Ltd.     

Performance test of passive radon–thoron discriminative detectors on environmental parameters

This paper describes how humidity, wind and ambient aerosols in air influence the detection responses of passive detectors. Two types of alpha track detectors based on a passive radon (²²²Rn)–thoron (²²⁰Rn) discriminative measurement technique were used: the Raduet and Radopot detectors that were developed and calibrated by the National Institute of Radiological Sciences, Japan. The initial experiment showed that the infiltration rate of ²²⁰Rn onto sponges with a high air exchange rate for the Raduet detectors was one third lower than that onto filters for the Radopot detectors. Little distinct dependence on humidity was observed for the ²²²Rn detection responses of both detectors. For ²²⁰Rn, the detection responses of both detectors for the high air exchange rate seemed to decrease slightly at high humidity conditions. The ²²⁰Rn detection responses of the Radopot detectors had little influence from wind speed. The ²²⁰Rn detection responses of the Raduet detectors for the high air exchange rate seemed to decrease at low wind speeds. Furthermore, there was little difference between the detection responses in the presence and absence of ambient aerosol particles because the ambient aerosols were filtered out during their passive diffusion through the sponges and filters for the Raduet and Radopot detectors, respectively.     

One-dimensional Wolter optics with a sub-50 nm spatial resolution

We studied an imaging system consisting of an elliptical mirror and a hyperbolic mirror [i.e., one-dimensional (1D) Wolter optics] to realize an achromatic full-field hard x-ray microscopy with a resolution better than 50 nm. We report the performance of this 1D Wolter optical system when the mirrors were ultraprecisely figured by elastic emission machining. Experiments to form a demagnified image (demagnification factor of 385) of a 10 μm slit were conducted at an x-ray energy of 11.5 keV at BL29XUL of SPring-8. The system could form a demagnified image with a resolution better than 50 nm over a 12.1 μm field.