Microwave-assisted in situ laser dye incorporation into high sensitivity whispering gallery mode microresonators

Optical whispering gallery mode microresonators (WGM-μRs) are powerful sensitive components with many analytical applications. Here, spherical WGM-μRs have been synthesised in a single-step microwave (MW)-assisted heterophase polymerisation. The microresonators are based on poly(styrene) beads into which the organic lasing dye nile red was incorporated as gain medium in situ during the polymerisation. The particle diameter and diameter distribution of the synthesised particles were tuned in the range of around 200 nm up to 50 μm by adjusting the concentration between stabiliser poly-(N-vinyl pyrrolidone) (PVP) and monomer styrene, and the solvent composition in the dispersion process. Lower water content enabled the synthesis of spherical particles with large size polydispersity, from which WGM-μRs with a variety of diameters were selected. Microspheres with diameters ≳3.5 μm supported WGMs. The WGMs were excited through free space via the fluorescence of the laser dye. Pumping power levels <1 μW were sufficient to excite WGMs. WGM shifts of beads with diameter between ≈5 and 30 μm measured in air and water show a sensitivity up to 54 nm/RIU for the smallest particles. Dye doped WGM-μR in the low μm size range obtained by the MW-assisted polymerisation process with its versatility, low processing times and high yields opens new horizons for the applications of these systems as sensors

Laparoscopic versus conventional appendectomy - a meta-analysis of randomized controlled trials

<p>Abstract</p> <p>Background</p> <p>Although laparoscopic surgery has been available for a long time and laparoscopic cholecystectomy has been performed universally, it is still not clear whether open appendectomy (OA) or laparoscopic appendectomy (LA) is the most appropriate surgical approach to acute appendicitis. The purpose of this work is to compare the therapeutic effects and safety of laparoscopic and conventional "open" appendectomy by means of a meta-analysis.</p> <p>Methods</p> <p>A meta-analysis was performed of all randomized controlled trials published in English that compared LA and OA in adults and children between 1990 and 2009. Calculations were made of the effect sizes of: operating time, postoperative length of hospital stay, postoperative pain, return to normal activity, resumption of diet, complications rates, and conversion to open surgery. The effect sizes were then pooled by a fixed or random-effects model.</p> <p>Results</p> <p>Forty-four randomized controlled trials with 5292 patients were included in the meta-analysis. Operating time was 12.35 min longer for LA (95% CI: 7.99 to 16.72, p < 0.00001). Hospital stay after LA was 0.60 days shorter (95% CI: -0.85 to -0.36, p < 0.00001). Patients returned to their normal activity 4.52 days earlier after LA (95% CI: -5.95 to -3.10, p < 0.00001), and resumed their diet 0.34 days earlier(95% CI: -0.46 to -0.21, p < 0.00001). Pain after LA on the first postoperative day was significantly less (p = 0.008). The overall conversion rate from LA to OA was 9.51%. With regard to the rate of complications, wound infection after LA was definitely reduced (OR = 0.45, 95% CI: 0.34 to 0.59, p < 0.00001), while postoperative ileus was not significantly reduced(OR = 0.91, 95% CI: 0.57 to 1.47, p = 0.71). However, intra-abdominal abscess (IAA), intraoperative bleeding and urinary tract infection (UIT) after LA, occurred slightly more frequently(OR = 1.56, 95% CI: 1.01 to 2.43, p = 0.05; OR = 1.56, 95% CI: 0.54 to 4.48, p = 0.41; OR = 1.76, 95% CI: 0.58 to 5.29, p = 0.32).</p> <p>Conclusion</p> <p>LA provides considerable benefits over OA, including a shorter length of hospital stay, less postoperative pain, earlier postoperative recovery, and a lower complication rate. Furthermore, over the study period it was obvious that there had been a trend toward fewer differences in operating time for the two procedures. Although LA was associated with a slight increase in the incidence of IAA, intraoperative bleeding and UIT, it is a safe procedure. It may be that the widespread use of LA is due to its better therapeutic effect.</p

Whispering gallery modes of a single crystalline zinc oxide microsphere at visible wavelengths

We present photoluminescence spectra of ultrasmall zinc oxide microspheres with sharp resonances of whispering gallery modes covering the whole visible window and compare with theoretical analyses. © 2013 Optical Society of America

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Not AvailableDeficiency of boron (B), molybdenum (Mo) and zinc (Zn) is a major factor constraining crop production on acidic soils of Northeast India; yet these nutrients are conventionally not included in fertilizer recommendation for crop production. To assess the criticality of micronutrients’ application on these soils, we conducted a greenhouse experiment on an acid Alfisol where French bean (Phaseolus vulgaris L.), a micronutrient-sensitive crop, was grown with seven combinations of macro- and micronutrients. The beneficial effect of micronutrients on crop yield was mediated mostly through their effect on seed and pod characteristics, and general improvement in crop health and nutrition as reflected by improved SPAD index.Not Availabl