Tight parabolic dark spot with high numerical aperture focusing with a circular π phase plate

The properties of tight dark focal spot created using a simple circular π phase plate are presented. For focusing elements with low numerical aperture, the focal plane intensity has r⁴ dependence, while for focusing elements with high numerical aperture, vectorial diffraction effects become important, and the focal plane intensity surprisingly approaches r² dependence, indicating a much tighter dark spot.     

X-ray scattering intensities of water at extreme pressure and temperature

We have calculated the coherent x-ray scattering intensity of several phases of water under high pressure using the ab initio density functional theory (DFT). Our calculations span the molecular liquid, ice VII, and superionic solid phases, including the recently predicted symmetrically hydrogen bonded region. We compute simulated spectra for ice VII and superionic water. We provide new atomic scattering form factors for water at extreme conditions, which take into account frequently neglected changes in ionic charge and electron delocalization. We show that our modified atomic form factors allow for a nearly exact comparison with the total x-ray scattering intensities calculated from DFT. Finally, we analyze the effect of their new form factors have on the determination of the oxygen-oxygen radial distribution function from experiment.     

Uniqueness of homogeneous CAT(0) polygonal complexes

We provide a combinatorial condition on a finite connected graph, $L$ , for which there exists a unique CAT(0) polygonal complex such that the link at each vertex is $L$ . Under the further assumption that the polygons have an even number of sides we prove that this condition is also necessary, and that there are either one or a continuum of non-isomorphic such complexes.     

Coupling the Lorentz Integral Transform (LIT) and the Coupled Cluster (CC) Methods: A Way Towards Continuum Spectra of “Not-So-Few-Body” Systems

Here we summarize how the LIT and CC methods can be coupled, in order to allow for ab initio calculations of reactions in medium mass nuclei. Results on ¹⁶O are reviewed and preliminary calculations on ⁴⁰Ca are presented.     

Monitoring of the non-steroid anti-inflammatory drug indomethacin: development of immunochemical methods for its purification and detection

The present research focused on the development of an immunoassay and an immunochemical sol–gel-based immunoaffinity purification (IAP) method for purification and detection of the non-steroid anti-inflammatory drug (NSAID) indomethacin (IMT). A polyclonal antibody (Ab) for IMT was generated, and two sensitive microplate assays for the detection of IMT were developed (termed OV and HRP formats), based on the enzyme-linked immunosorbent assay (ELISA) method. The limits of detection of the assays were 15 ± 1.25 ng mL⁻¹ (n = 50) and 12 ± 0.17 ng mL⁻¹ (n = 4) for the OVA and HRP formats, respectively. The Abs exhibited slight cross-reactivity with other NSAIDs. The Abs were also used to develop a sol–gel-based IAP method for clean-up and concentration of IMT. Several sol–gel formats with various amounts of antibodies were examined; the best and most reproducible format was at a TMOS:HCl molar ratio of 1:6 in which 120 μL of IMT Abs was entrapped. The binding capacity under these conditions was ca. 100 to 250 ng of IMT with very low non-specific binding (less than 5% of the applied amount). The sol–gel IAP method, combined with solid-phase extraction, successfully eliminated serum interference to a degree that enabled analysis of spiked serum samples by ELISA. The method was also found to be fully compatible with subsequent chemical analytical methods, such as liquid chromatography followed by mass spectrometry. The approaches developed in this study form a basis for analysis of IMT in biological samples in order to monitor their pharmacokinetic properties, and may be further used to study population exposure to IMT, and to monitor the occurrence of IMT contamination in water samples.     

Ultrafast control of grating-assisted light coupling to surface plasmons

We demonstrate subpicosecond control over the coupling of free-space radiation to surface-plasmon polaritons using 830 and 500 nm period gold gratings. Thermal changes to the electron distribution following irradiation by 100 fs, 810 nm pulses produce a shift of the 570 nm plasmon resonance by ~0.75 nm with reflectivity change up to 6% and decay time of ~1 ps.     

Loss enhanced phase locking in coupled oscillators

Phase locking, which is achieved by transferring some energy from one oscillator to the others, strongly depends on the coupling strength between the oscillators. Typically, the coupling strength must be above a certain threshold in order to achieve phase locking. Here we show how this threshold can be significantly reduced when phase-dependent losses are introduced into the oscillators. Specifically, the coupling strength can be reduced by at least an order of magnitude, thereby substantially decreasing the needed transfer of energy between oscillators. The resulting enhancement of phase locking does not only influence the laser research area, but also affects many other areas that involve coupled ensembles.     

Max–max,max–min,min–max and min–min knapsack problems with a parametric constraint

4OR - Max–max, max–min, min–max and min–min optimization problems with a knapsack-type constraint containing a single numerical parameter are studied. The goal is to present...