Paramagnetic contribution of serum iron to the spin-spin relaxation rate (1/T 2) measured by MRI

Spin-spin relaxation timeT ₂ values of serum with and without iron were measured by magnetic resonance imaging (MRI) to find the proton relaxivity of Fe(III) in serum.T ₂ values in serum containing definite amounts of added iron were also measured before and after addition of ascorbic acid. The difference in the 1/T ₂ of serum with and without ascorbic acid was used for recalculation of the added iron values. Recalculated iron values confirm that the difference in healthy serum is caused by iron only. In addition, in order to find the paramagnetic contribution of serum iron,T ₂ values of iron-deficient, healthy and iron-overloaded serum were measured before and after addition of ascorbic acid. The difference in the 1/T ₂ values was then applied to the calculation of the serum iron values. The consistency of iron values determined from the difference to those by autoanalyzer suggests that the differences in diseased serum also represent the paramagnetic contribution of serum iron. The data imply that serum iron content in healthy, iron-deficient and iron-overloaded serum may be assessed by MRI.     

Particle production at high energies in the Cardy pomeron model

Particle production at very high energies inhh, hA andAB collisions is studied in the framework of the pomeron model with a strong self-interaction proposed by Cardy. It is shown that the interaction between pomerons substancially damps the production rate one nuclei, the multiplicities forhA collisions becomingA-independent.     

The biologically important surfactin lipopeptide induces nanoripples in supported lipid bilayers

Under specific conditions, lipid membranes form ripple phases with intriguing nanoscale undulations. Here, we show using in situ atomic force microscopy (AFM) that the biologically important surfactin lipopeptide induces nanoripples of 30 nm periodicity in dipalmitoyl phosphatidylcholine (DPPC) bilayers at 25 degrees (i.e. well below the pretransition temperature of DPPC). Whereas most undulations formed the classical straight orientation with characteristic angle changes of 120 degrees , some of them also displayed unusual circular orientations. Strikingly, ripple structures were formed at 15% surfactin but were rarely or never observed at 5 and 30% surfactin, emphasizing the important role played by the surfactin concentration. Theoretical simulations corroborated the AFM data by revealing the formation of stable surfactin/lipid assemblies with positive curvature.     

Effect of SnO2 coating on the magnetic properties of nanocrystalline CuFe2O4

Nanocrystalline CuFe₂O₄ and CuFe₂O₄/xSnO₂ nanocomposites (x=0, 1, 5 wt%) have been successfully synthesized by one-pot reaction of urea-nitrate combustion method. The transmission electron microscope study reveals that the particle size of the as synthesized CuFe₂O₄ and CuFe₂O₄/5 wt%SnO₂ are 10 and 20 nm, respectively. The SnO₂ coating on the nanocrystalline CuFe₂O₄ was confirmed from HRTEM studies. The resultant products were sintered at 1100 °C and characterized by XRD and SQUID for compound formation and magnetic studies, respectively. The X-ray diffraction pattern shows the well-defined sharp peak that confirms the phase pure compound formation of tetragonal CuFe₂O₄. The zero field cooled (ZFC) and field cooled (FC) magnetization was performed using SQUID magnetometer from 2 to 350 K and the magnetic hysteresis measurement was carried out to study the magnetic properties of nanocomposites.     

On Hall voltage and change of conductivity in transverse magnetic fields of pressed PbO2 powder

The electrical conductivity of a conducting powder is influenced by the properties of the grain surface as well as the grain core. By appropriate variation of pressure and electric frequency, the two contributions can be separated, as long as the grains have shapes nearly like spheres. From experimental data on pressed powders one can thus obtain information concerning carrier density and mobility of bulk material. Results for PbO₂ obtained in this way agree well with the properties of bulk PbO₂ samples reported in the literature.     

Advanced Optical Network

The following article describes an advanced dense wavelength division multiplexing (DWDM) Optical Network developed by L-3 Photonics. The network, configured as an amplified optical bus, carries traffic simultaneously in both directions, using multiple wavelengths. As a result, data distribution is of the form peer-to-multi-peer, it is protocol independent, and it is scalable. The network leverages the rapid growth in commercial optical technologies, including wavelength division multiplexing (WDM), and when applied to military and commercial platforms such as aircraft, ships, unmanned and other vehicles, provides a cost-effective, low-weight, high-speed, and high noise-immune data distribution system.     

The diaryl(oxy)methyl group: more than an innocent bystander in chiral auxiliaries, catalysts, and dopants

Either as the free alcohol or deprotonated, a carbinol residue bearing gemial, identical aryl residues can at first sight be recognized as an achiral structural unit. When incorporated, however, into a chiral molecule, the two aryl groups become diastereotopic. Thus, they might contribute to an enhancement in stereoselectivity and do so in a variety of reactions. This Minireview highlights developments in stereochemistry when the diaryl(oxy)methyl group is involved, with emphasis given to the beneficial effect of this moiety. Of particular focus are auxiliaries, the stoichiometric use of metal complexes, metal and organocatalysts, and finally chiral dopants for liquid crystals, all featuring the diaryl(oxy)methyl group.     

Continuous-wave mode-locked solid-state lasers with enhanced spatial hole burning

In Part I of this paper [1] experimental results were presented and discussed. In this part, we investigate theoretically the dynamics of end-pumped solid-state lasers due to enhanced spatial hole burning. This becomes possible by a fast numerical implementation of the saturated gain in the presence of strong spatial hole burning that allows to treat the multimode case for an arbitrary pumping level. We find for a wide range of laser parameters that the mode spacing of the cw running modes is essentially determined by the length of the gain medium and only weakly depends on the absorption depth of the pump transition. It is shown that spatial hole burning can lead to a completely flat saturated gain profile over half of the gain bandwidth. In mode-locked lasers, the flat gain due to spatial hole burning results in shorter pulses. But the pulses are neither Gaussian-nor sech-shaped as they are in actively or passively mode-locked lasers without spatial hole burning. Further, we show that soliton-like pulse shaping can be used to restore a transform-limited sech-shaped pulse in an end-pumped solid-state laser while exploiting the full gain bandwidth of the laser material.     

UV‐Free Microfluidic Particle Fabrication at Low Temperature Using ARGET‐ATRP as the Initiator System

A new way to fabricate monodisperse polymer particles in a microfluidic device without UV‐light and without the need for high temperatures is described in this article. By applying an activator regeneration by electron transfer ‐ atom transfer radical polymerization (ARGET‐ATRP) initiator system in a co‐capillary microfluidic setup and by separating the monomer mixture in an initiator and a catalyst phase, a fast polymerization of the droplets at low temperature without premature curing and thus clogging of the capillaries can be achieved. The influence of the flow rates on the particle sizes and their polydispersity as well as the controlled character of the polymerization are investigated. The particle size is well adjustable, but the reaction is not controlled due to the high radical concentration needed for rapid polymerization. In addition, particles with incorporated UV‐dyes are produced as a proof of concept at low temperature.