High-performance liquid chromatographic enantioseparation of β-amino acids using a long-tethered (+)-(18-crown-6)-2,3,11,12-tetracarboxylic acid-based chiral stationary phase

Reversed-phase high-performance liquid chromatographic methods were developed for the separation of enantiomers of eleven unnatural β²-amino acids on a new chiral stationary phase, using the 11-methylene-unit spacer of aminoundecylsilica gel for the bonding of (+)-(18-crown-6)-2,3,11,12-tetracarboxylic acid as selector. The nature and concentration of the acidic and organic modifiers, the pH, the mobile phase composition, and the structures of the analytes substantially influenced the retention and resolution. Separations were carried out at constant mobile phase compositions in the temperature range 7–40 °C and the changes in enthalpy, Δ(ΔH°), entropy, Δ(ΔS°), and free energy, Δ(ΔG°) were calculated. The elution sequence was determined in some cases: the S enantiomers eluted before the R enantiomers.     

Photo-activated pheophorbide a inhibits the growth of prostate cancer cells

Pheophorbide a (PhA) was identified as a photosensitizer to exert cytotoxicity on tumor cells. However, the efficacy of this compound on the treatment of prostate cancer remains unknown. The aim of this study was to evaluate the photodynamic effect of PhA on prostate cancer cells. Cellular uptake of PhA and cell viability after photo-activation was studied in LNCaP prostate cancer cells. The corresponding production of reactive oxygen species within cells was determined after photodynamic therapy (PDT). Our results showed that the uptake of PhA into LNCaP cells was in a time-dependent manner and the cytotoxicity of PhA-PDT was photosensitizer dose- and light dose-dependent. The intracellular reactive oxygen species was remarkably induced after PDT treatment, which was responsible for the inhibition effect on prostate cancer cells. This is the first report to evaluate the photodynamic effect of PhA on prostate cancer. Our findings demonstrate that PhA-PDT may be a potentially promising treatment for localized prostate cancer, which can be a therapeutic option after the failures of radiotherapy and hormone therapy.     

Moment computations for graphs with fractal property

In this paper, we use explicit formulas for the moments of a self-adjoint operator (radial operator), induced by a certain discrete structure, in Hilbert space. Our main theorem shows that the structures are classified by the moment computations producing an equivalence relation. Our motivation in turn derives from a groupoid-theoretic approach to spectral problems as they arise in quantum mechanics. While it is typically difficult to obtain explicit formulas for spectra, we demonstrate that our moment formulas serve as a substitute. The discrete structures $\Bbb{G}$ we study have a built in fractal feature: any portion of $\Bbb{G}$ is similar to the whole. And this fact (like in renormalization groups) serves to facilitate computations.     

Observation and analysis of in vivo vocal fold tissue instabilities produced by nonlinear source-filter coupling: a case study

Different source-related factors can lead to vocal fold instabilities and bifurcations referred to as voice breaks. Nonlinear coupling in phonation suggests that changes in acoustic loading can also be responsible for this unstable behavior. However, no in vivo visualization of tissue motion during these acoustically induced instabilities has been reported. Simultaneous recordings of laryngeal high-speed videoendoscopy, acoustics, aerodynamics, electroglottography, and neck skin acceleration are obtained from a participant consistently exhibiting voice breaks during pitch glide maneuvers. Results suggest that acoustically induced and source-induced instabilities can be distinguished at the tissue level. Differences in vibratory patterns are described through kymography and phonovibrography; measures of glottal area, open/speed quotient, and amplitude/phase asymmetry; and empirical orthogonal function decomposition. Acoustically induced tissue instabilities appear abruptly and exhibit irregular vocal fold motion after the bifurcation point, whereas source-induced ones show a smoother transition. These observations are also reflected in the acoustic and acceleration signals. Added aperiodicity is observed after the acoustically induced break, and harmonic changes appear prior to the bifurcation for the source-induced break. Both types of breaks appear to be subcritical bifurcations due to the presence of hysteresis and amplitude changes after the frequency jumps. These results are consistent with previous studies and the nonlinear source-filter coupling theory.     

Long-range acoustic communication in deep water using a towed array

In September 2010 a long-range acoustic communication (LRAC10) experiment was carried out in deep water off the Southern California Coast. The experiment involved two mobile components: (1) a source towed slowly at a speed of 2-3 knots at ～75-m depth and (2) a horizontal line array towed at 3.5 knots at a depth of ～200 m. Phase-coherent communication sequences were transmitted in the frequency band of 200-300 Hz at various ranges (100-700 km). Initial analysis of the LRAC10 data demonstrates that an information rate of 50 bits/s can be achieved over ～550-km range using quadrature-phase shift-keying (QPSK) modulation and error-correction coding combined with beamforming.     

Anisotropic conformal infinity

We generalize Penrose’s notion of conformal infinity of spacetime, to situations with anisotropic scaling. This is relevant not only for Lifshitz-type anisotropic gravity models, but also in standard general relativity and string theory, for spacetimes exhibiting a natural asymptotic anisotropy. Examples include the Lifshitz and Schrödinger spaces (proposed as AdS/CFT duals of nonrelativistic field theories), warped AdS ₃, and the near-horizon extreme Kerr geometry. The anisotropic conformal boundary appears crucial for resolving puzzles of holographic renormalization in such spacetimes.     

Prepotential approach to quasinormal modes

In this paper we demonstrate how the recently reported exactly and quasi-exactly solvable models admitting quasinormal modes can be constructed and classified very simply and directly by the newly proposed prepotential approach. These new models were previously obtained within the Lie-algebraic approach. Unlike the Lie-algebraic approach, the prepotential approach does not require any knowledge of the underlying symmetry of the system. It treats both quasi-exact and exact solvabilities on the same footing, and gives the potential as well as the eigenfunctions and eigenvalues simultaneously. We also present three new models with quasinormal modes: a new exactly solvable Morse-like model, and two new quasi-exactly solvable models of the Scarf II and generalized Pöschl–Teller types.     

Quantum MIMO Communication Scheme Based on Quantum Teleportation with Triplet States

A novel quantum MIMO communication scheme is proposed by generalizing the wireless communication technique to the quantum field. The MIMO quantum teleportation can be implemented with triplet states in order to enhance the capacity and fidelity of the quantum channel, in which an n-qubit sequence of quantum signals can be transmitted through the MIMO quantum channel by applying the diversity technique. The quantum noise filtering is involved before the quantum signals are outputted. The analysis and discussions demonstrate that the quantum MIMO teleportation can be performed securely with high capacity and fidelity.     

Preparation and luminescence properties of SrTiO3:Pr,Al phosphor from the glycolate method

Spherical SrTiO₃:Pr³⁺,Al³⁺ phosphor with high crystallinity and uniform particle size distribution was formed from the glycolate precursor. The glycolate precursor was obtained by heating the mixed solution of metallic nitrates and titanium oxychloride in ethylene glycol up to 200 °C. The thermal decomposition of the glycolate precursor proceeded through three major stages, i.e., (i) evolution of glycols (∼200 °C), (ii) decomposition of glycolate precursor, and (iii) decomposition of strontium carbonate and crystallization of SrTiO₃:Pr³⁺,Al³⁺ phosphor.SrTiO₃:Pr³⁺,Al³⁺ phosphor exhibited a strong red emission, peaking at about 617 nm. SrTiO₃:Pr³⁺,Al³⁺ phosphor obtained from the glycolate complex has higher luminescent properties than the conventional solid state reaction and the Pechini method in terms of photoluminescence (PL) and cathodoluminescence (CL). High crystallinity, low residual carbon content and small grain size with uniform shape would enhance the luminescence intensity of phosphor by the glycolate method due to high surface area per unit volume and low organic content compared with the Pechini method. Also, Al³⁺ ion is more effective than Ga³⁺ ion to enhance PL intensity of SrTiO₃:Pr³⁺,Al³⁺ phosphor because of smaller Al³⁺ ion radius. Therefore, the glycolate method has been demonstrated to be a convenient and unique process for the production of muticomponent oxide with smaller grain size and higher crystallinity compared with the conventional mixed oxide reaction and the polymer precursor method.     

All-optical switching with a biexcitonic double lambda system

A double lambda four-level system could be implemented with biexcitonic transitions on GaAs quantum well. We observed that the phase dependent biexcitonic transition could be explained by interference between one-photon and three-photon transition in a double lambda four-level system. An ultralow-light switch pulse could control 80% of biexcitonic absorption, which demonstrated all-optical switching with biexcitonic double lambda system.