Multi-periodic nanostructures for photon control.

We propose multi-periodic nanostructures yielded by superposition of multiple binary gratings for wide control over photon emission in thin-film devices. We present wavelength- and angle-resolved photoluminescence measurements of multi-periodically nanostructured organic light-emitting layers. The spectral resonances are determined by the periodicities of the individual gratings. By varying component duty cycles we tune the relative intensity of the main resonance from 12% to 82%. Thus, we achieve simultaneous control over the spectral resonance positions and relative intensities.

Iterative scalar nonparaxial algorithm for the design of Fourier phase elements.

We propose an iterative algorithm based on our scalar nonparaxial propagator for the design of Fourier diffractive optical elements (DOEs) having features on the order of the illumination wavelength. The simulation results show that our algorithm, using iterative Fourier transform and iterative projection, obtains higher-performance DOEs than a purely scalar paraxial design with the same order of calculation time. Upon verification with the experimental results, we find that our scalar-based design method is valid for DOEs with surprisingly small feature sizes (about half the wavelength) and diffraction angles up to about 37°.

Pump spot size dependent lasing threshold in organic semiconductor DFB lasers fabricated via nanograting transfer.

Optically excited organic semiconductor distributed feedback (DFB) lasers enable efficient lasing in the visible spectrum. Here, we report on the rapid and parallel fabrication of DFB lasers via transferring a nanograting structure from a flexible mold onto an unstructured film of the organic gain material. This geometrically well-defined structure allows for a systematic investigation of the laser threshold behavior. The laser thresholds for these devices show a strong dependence on the pump spot diameter. This experimental finding is in good qualitative agreement with calculations based on coupled-wave theory. With further investigations on various DFB laser geometries prepared by different routes and based on different organic gain materials, we found that these findings are quite general. This is important for the comparison of threshold values of various devices characterized under different excitation areas.

Extraction of guided modes from organic emission layers by compound binary gratings.

The extraction of guided modes from a 100 nm organic emission layer by compound binary gratings with multiple superimposed periods at different ratios is investigated. We measure angle-dependent photoluminescence from samples with double-period (350 and 450 nm), triple-period (350, 400, and 450 nm), and multiperiod (350, 400, 450, and 500 nm) gratings and show that each period component produces two outcoupling features due to first-order Bragg scattering of the TE(0) guided mode. The averaged angular color change is reduced by up to a factor of 11 compared to a single-period grating structuring.

Tolerability and safety profile of 12- to 28-week treatment with interferon beta-1b 250 and 500 microg QOD in patients with relapsing-remitting multiple sclerosis: a multicenter, randomized, double-blind, parallel-group pilot study.

BACKGROUND: It is not known whether the currently available treatment regimen of interferon beta-1b (IFNbeta-1b) 250 microg provides the maximum benefit possible in the treatment of relapsing-remitting multiple sclerosis (RRMS), or whether higher doses of IFNbeta-1b will prove to be more beneficial. OBJECTIVE: The objective of the present study was to evaluate the tolerability and safety profile of IFNbeta-1b 500 microg compared with the currently approved 250-microg dose. METHODS: A multicenter, randomized, double-blind, parallel-group pilot study was carried out to compare IFNbeta-1b 250 microg with IFNbeta-1b 500 microg, both self-administered SC QOD for >or=12 weeks in patients with RRMS. Patients in both groups started with 25% (0.25 mL) of their final dose and were scheduled to increase the dose by 0.25 mL every 2 weeks, so that the full dose (1.0 mL, 250 microg or 500 microg) would be reached by week 7. The primary outcome measure was the percentage of patients experiencing each of the following adverse events (AEs): influenza-like symptoms (general term used to code the presence of >1 symptom typical of influenza), fever, myalgia, asthenia, headache, injection-site reactions, injection-site pain, or liver or hematologic abnormalities. All patients underwent a priori magnetic resonance imaging (MRI) with 0.1 mmol/kg gadolinium (Gd)-diethylenetriaminepentaacetic acid as contrast medium at screening and at week 12. MRI evaluation was included as a safety measure to monitor for excessive new disease not visible through clinical symptoms. RESULTS: Seventy-seven patients were assessed for inclusion in the study. Of these, 6 patients were screening failures and the remaining 71 were randomized to treatment (38-250 and 33-500 microg IFNbeta-1b). The uneven numbers in the groups were a consequence of the randomization process. Two patients in the 250-microg group (withdrawal of consent) and 1 in the 500-microg group (not completing follow-up visit) prematurely discontinued medication. The demographic characteristics were not significantly different between the 250-microg (n=38; mean [SD] age, 37.9 [8.3] years; weight, 83.5 [19.0] kg; height, 168.4 [9.3] cm) and 500-microg (n=33; mean [SD] age, 37.8 [7.7] years; weight, 82.3 [19.5] kg; height, 169.9 [10.5] cm) treatment groups. The patients in both groups were mostly white (87% and 73%, respectively). Baseline Expanded Disability Status Scale scores also were not significantly different between the 2 groups (mean [SD] score, 2.8 [1.4] vs 2.0 [1.4], respectively). In the IFN(2)-1b 250-microg group, 97% of the patients titrated to the full dose at some point during the course of the study, compared with 91% of the 500-microg group (P=NS). A dose-response effect was observed in some of the more frequent AEs (no. [%]) that included influenza-like syndrome (250-microg group, 13 [34] vs 500-microg group, 16 [48]), asthenia (13 [34] vs 16 [48], respectively), headache (12 [32] vs 12 [36]), myalgia (10 [26] vs 13 [39]), hypesthesia (10 [26] vs 11 [33]), nausea (6 [16] vs 8 [24]), paresthesia (6 [16] vs 8 [24]), myasthenia (4 [11] vs 8 [24]), chills (3 [8] vs 6 [18]), depression (3 [8] vs 5 [15]), back pain (2 [5] vs 5 [15]), increased liver enzymes (4 [11] vs 6 [18]), lymphopenia (4 [11] vs 3 [9]), fever (2 [5] vs 4 [12]), and pain in extremities (1 [3] vs 4 [12]). The between-group incidence of injection-site reactions was not significantly different. No new or unexpected AEs were recorded. Changes in MRI parameters between screening and 12 weeks were not significantly different between dose groups; these included median T2 lesion volume, median Gd-enhanced lesion volume, median Gd-enhanced lesion number, and mean number of newly active lesions. CONCLUSIONS: IFNbeta-1b 500 microg administered SC QOD was generally well tolerated in these patients with RRMS. Large, randomized controlled studies are needed to determine if there are significant differences in MRI end points between the 250- and 500-microg doses.