40 research outputs found

    Single-Shot Laser Additive Manufacturing of High Fill-Factor Microlens Arrays

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    High fill-factor microlens arrays (MLA) are key for improving photon collection efficiency in light-sensitive devices. Although several techniques are now capable of producing high-quality MLA, they can be limited in fill-factor, precision, the range of suitable substrates, or the possibility to generate arbitrary arrays. Here, a novel additive direct-write method for rapid and customized fabrication of high fill-factor MLA over a variety of substrates is demonstrated. This approach uses a single laser pulse to delaminate and catapult a polymeric microdisc from a film onto a substrate of interest. Following a thermal reflow process, the printed disc can be converted into a planoconvex microlens offering excellent sphericity and high smoothness (RRMS < 40 Å). Importantly, the transfer of solid microdiscs enables fill-factors close to 100%, not achievable with standard direct-write methods such as inkjet printing or microdispensing. Arbitrary generation of MLA over flexible and curved surfaces, with microlenses presenting a curvature ranging from 20 to 240 μm and diffraction-limited performance, is demonstrated. The ease of implementation and versatility of the approach, combined with its potential parallelization, paves the way for the high-throughput fabrication of tailored MLA directly on top of functional devices

    Very large spot size effect in nanosecond laser drilling efficiency of silicon

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    The effect of the spot diameter in nanosecond excimer laser percussion drilling of through via in silicon wafer is presented. Experimental results show a ten fold increase of the ablation efficiency when decreasing the spot diameter from 220 μm to 9 μm at constant fluence in the range 7.5 J/cm(2) to 13.2 J/cm(2). Such effect is absent when using 60 ps deep-UV laser pulses. A model is developed that explain the findings in terms of plume shielding effect on the laser pulse. The model is successfully applied also on previously published data on deep-UV laser drilling of Polyamide and Alumina

    Pseudomonas Cross-Infection from Cystic Fibrosis Patients to Non-Cystic Fibrosis Patients: Implications for Inpatient Care of Respiratory Patients

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    A 14-year-old boy with bronchiectasis secondary to chronic aspiration developed multiresistant Pseudomonas aeruginosa lower respiratory disease following several inpatient periods where accommodation and physiotherapy services were shared with cystic fibrosis (CF) patients known to be infected with the genetically identical strain of P. aeruginosa. Cross-infection with P. aeruginosa between CF patients and non-CF patients has not previously been described, and this finding raises significant issues relevant to the treatment of patients with non-CF suppurative lung disease

    Patients with enteric adenovirus gastroenteritis admitted to an Australian pediatric teaching hospital from 1981 to 1992.

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    During the period 1981 to 1992, 4,473 fecal specimens collected from children hospitalized with acute gastroenteritis at the Royal Children's Hospital, Melbourne, Australia, were examined by electron microscopy. A monoclonal antibody enzyme immunoassay for enteric adenovirus (EAd) types 40 (Ad40) and 41 (Ad41) was used when adenoviruses were visualized. Fecal samples were positive for adenovirus by both electron microscopy and enzyme immunoassay in 138 patients (3.1%). Ad40 was identified in 19 children (14%), and Ad41 was identified in 119 children (86%). These EAd were identified during each of the 12 years surveyed. EAd were present year-round, but the annual number of hospitalizations was not constant. Yearly prevalence varied from 0.7% (1981) to 6.5% (1985). This was associated with monthly fluctuations in Ad41 activity, with overall peak monthly prevalence in May (late autumn). By contrast, Ad40 numbers remained low and constant year-round. The frequency of Ad41 relative to Ad40 increased from 25% in 1981 to exceed 75% after 1983. Children admitted with EAd infection were more likely to have diarrhea for more than 5 days (P < 0.001) but less likely to be febrile or dehydrated (P < 0.05) than children with rotavirus infection. EAd are responsible for enteric symptoms of only a fraction of hospitalized children with infectious diarrhea but result in a more-protracted illness than rotavirus. Their relationship to persistent diarrhea requires further investigation
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