Laser ionization in β decay studies of Zn and Mn nuclei

Resonance ionization laser ion source (RILIS) technique has been used in the β-decay studies of ⁵⁹Mn and ⁵⁸Zn. The importance of the RILIS for production of these elements is discussed. The properties of the low-lying levels of the studied nuclei are discussed. This revised version was published online in August 2006 with corrections to the Cover Date.     

Identification of \mathrm{\ensuremath J^{\pi} = 19/2^+} and \mathrm{\ensuremath 23/2^+} isomeric states in 127Sb

The nucleus $\ensuremath {\rm ^{127}Sb}$ , which is on the neutron-rich periphery of the $\ensuremath \beta$ -stability region, has been populated in complex nuclear reactions involving deep-inelastic and fusion-fission processes with $\ensuremath {\rm {}^{136}Xe}$ beams incident on thick targets. The previously known isomer at 2325 keV in $\ensuremath {\rm {}^{127}Sb}$ has been assigned spin and parity $\ensuremath 23/2^+$ , based on the measured $\ensuremath \gamma$ - $\ensuremath \gamma$ angular correlations and total internal conversion coefficients. The half-life has been determined to be 234(12) ns, somewhat longer than the value reported previously. The 2194 keV state has been assigned $\ensuremath J^{\pi} = 19/2^+$ and identified as an isomer with $\ensuremath T_{1/2} = 14(1) {\rm ns}$ , decaying by two $\ensuremath E2$ branches. The observed level energies and transition strengths are compared with the predictions of a shell model calculation. Two $\ensuremath 15/2^+$ states have been identified close in energy, and their properties are discussed in terms of mixing between vibrational and three-quasiparticle configurations.     

Structural Factors and Mechanisms Underlying the Improved Photodynamic Cell Killing with Silicon Phthalocyanine Photosensitizers Directed to Lysosomes Versus Mitochondria

The phthalocyanine photosensitizer Pc 4 has been shown to bind preferentially to mitochondrial and endoplasmic reticulum membranes. Upon photoirradiation of Pc 4-loaded cells, membrane components, especially Bcl-2, are photodamaged and apoptosis, as indicated by activation of caspase-3 and cleavage of poly(ADP-ribose) polymerase, is triggered. A series of analogs of Pc 4 were synthesized, and the results demonstrate that Pcs with the aminopropylsiloxy ligand of Pc 4 or a similar one on one side of the Pc ring and a second large axial ligand on the other side of the ring have unexpected properties, including enhanced cell uptake, greater monomerization resulting in greater intracellular fluorescence and three-fold higher affinity constants for liposomes. The hydroxyl-bearing axial ligands tend to reduce aggregation of the Pc and direct it to lysosomes, resulting in four to six times more killing of cells, as defined by loss of clonogenicity, than with Pc 4. Whereas Pc 4-PDT photodamages Bcl-2 and Bcl-xL, Pc 181-PDT causes much less photodamage to Bcl-2 over the same dose–response range relative to cell killing, with earlier cleavage of Bid and slower caspase-3-dependent apoptosis. Therefore, within this series of photosensitizers, these hydroxyl-bearing axial ligands are less aggregated than is Pc 4, tend to localize to lysosomes and are more effective in overall cell killing than is Pc 4, but induce apoptosis more slowly and by a modified pathway.     

Quasiconformal mappings and singularity of boundary distortion

We extend a well-known theorem of Jones and Makarov [8] on the singularity of boundary distortion of planar conformal mappings. Using a different technique, we recover the previous result and generalize the result to quasiconformal mappings of the unit ball ⊂_∝ ⁿ , n ≥ 2. We also establish an estimate on the Hausdorff (gauge) dimension of the boundary of the image domain outside an exceptional set of given size on the sphere ∂ and show that this estimate is essentially sharp.     

Multiobjective optimization of an ultrasonic transducer using NIMBUS

The optimal design of an ultrasonic transducer is a multiobjective optimization problem since the final outcome needs to satisfy several conflicting criteria. Simulation tools are often used to avoid expensive and time-consuming experiments, but even simulations may be inefficient and lead to inadequate results if they are based only on trial and error. In this work, the interactive multiobjective optimization method NIMBUS is applied in designing a high-power ultrasonic transducer. The performance of the transducer is simulated with a finite element model, and three design goals are formulated as objective functions to be minimized. To find an appropriate compromise solution, additional preference information is needed from a decision maker, who in our case is an expert in transducer design. A realistic design problem is formulated, and an interactive solution process is described. Our findings demonstrate that interactive multiobjective optimization methods, combined with numerical simulation models, can efficiently help in finding new solution approaches and possibilities as well as new understanding of real-life problems as entirenesses. In this case, the decision maker found a solution that was better with respect to all three objectives than the conventional unoptimized design.     

Current-density imaging using ultra-low-field MRI with zero-field encoding

Electric current density can be measured noninvasively with magnetic resonance imaging (MRI). Determining all three components of the current density, however, requires physical rotation of the sample or current injection from several directions when done with conventional methods. However, the emerging technology of ultra-low-field (ULF) MRI, in which the signal encoding and acquisition is conducted at a microtesla-range magnetic field, offers new possibilities. The low applied magnetic fields can even be switched off completely within the pulse sequence, increasing the flexibility of the available sequences. In this article, we present a ULF-MRI sequence designed for obtaining all three components of a current-density pattern without the need of sample rotations. The sequence consists of three steps: prepolarization of the sample, signal encoding in the current-density-associated magnetic field without applying any MRI fields, and spatial encoding in a microtesla-range field using any standard ULF-MRI sequence. The performance of the method is evaluated by numerical simulations. The method may find applications, e.g., in noninvasive conductivity imaging of tissue.     

Comparison of carbon aerogel and carbide-derived carbon as electrode materials for non-aqueous supercapacitors with high performance

Two porous carbon materials, one synthesised by pyrolysis of an organic aerogel prepared using sol–gel method and the other synthesised from molybdenum carbide by high temperature chlorination method, were tested as supercapacitor electrode materials in a non-aqueous tetraalkylammonium salt-based electrolyte. The gravimetric capacitance values calculated for the carbon aerogel (CAG)-based system were almost two times smaller (~55?F?g^?1) compared to carbide-derived carbon (C(Mo₂C))-based system (~125?F?g^?1). However, due to the very wide region of ideal polarizability, 3.6?V for C(Mo₂C) and 3.8?V for CAG-based test cells, very high energy densities up to 63?Wh?kg^?1 (34?Wh?dm^?3) and power densities up to 757?kW?kg^?1 (314?kW?dm^?3) were estimated for these systems, respectively. CAG-based system shows very short characteristic charge/discharge time constant values (0.05?s).     

Double-resonant extremely asymmetrical scattering of electromagnetic waves in periodic arrays separated by a gap

Two strong simultaneous resonances of scattering – double-resonant extremely asymmetrical scattering (DEAS) – are predicted in two parallel, oblique, periodic Bragg arrays separated by a gap, when the scattered wave propagates parallel to the arrays. One of these resonances is with respect to frequency (which is common to all types of Bragg scattering), and another is with respect to phase variation between the arrays. The diffractional divergence of the scattered wave is shown to be the main physical reason for DEAS in the considered structure. Although the arrays are separated, they are shown to interact by means of the diffractional divergence of the scattered wave across the gap from one array into the other. It is also shown that increasing separation between the two arrays results in a broader and weaker resonance with respect to phase shift. The analysis is based on a recently developed new approach allowing for the diffractional divergence of the scattered wave inside and outside the arrays. Physical interpretations of the predicted features of DEAS in separated arrays are also presented. Applicability conditions for the developed theory are derived.